2013-05-22T00:31:06Z http://digital.library.unt.edu/explore/partners/UNTCAS/oai/

info:ark/67531/metadc29402 2011-04-04T14:46:46Z partner:UNTCAS collection:UNTSW access_rights:public

Toxicological Case Study of Dallas' Central Wastewater Treatment Plant Effluent and Ambient Trinity River Samples: 1989, 1990, 1991 University of North Texas. Institute of Applied Sciences. Toxicology -- Case studies. Trinity River Basin (Tex.) Water quality -- Texas. rivers Trinity River wastewater treatment plants Dallas Central Wastewater Treatment Plant "This study was implemented voluntarily by personnel at Dallas Water Utilities in response to concerns that the Dallas Central Wastewater Treatment Plant was adversely affecting downstream water quality." The treatment plant was studied to determine whether it was "discharging toxic materials in toxic amounts to the Trinity River" (p. 1). University of North Texas. Institute of Applied Sciences Dickson, Kenneth L. Waller, William T. Hall, David B. Dallas Water Utilities [1991] Book 326 p. : ill., maps ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc29402/ ark: ark:/67531/metadc29402 English United States - Texas 1989-1991

info:ark/67531/metadc29400 2011-04-04T16:14:54Z partner:UNTCAS collection:UNTSW access_rights:public

Remote Sensing and GIS for Nonpoint Source Pollution Analysis in the City of Dallas' Eastern Watersheds University of North Texas. Dept. of Biological Sciences Watershed management -- Remote sensing. Watershed management -- United States -- Case studies. Geographic information systems. Landscape and Nature - Water - Lakes Landscape and Nature - Water - Rivers nonpoint source pollution watersheds Eastern Watersheds lakes rivers Lake Lavon Lake Ray Hubbard Lake Tawakoni Lake Fork Lake Palestine rivers East Fork Trinity River provinces Pineywoods Province Blackland Prairie Province Post Oak Savannah Province This report describes the findings of a study conducted on the Eastern Watersheds of Lake Lavon, Lake Ray Hubbard, Lake Tawakoni, Lake Palestine and Lake Fork, which are located within the Blackland Prairie, Post Oak Savannah and Pineywoods provinces. These watersheds are among nine that provide drinking water to Dallas, Texas. The study examines the potential benefit of "remote sensing and geographic information systems (GIS) for watershed management" in these five watersheds (p. iii). University of North Texas Atkinson, S. F. Dickson, K. L. Shaw, D. M. Hunter, B. A. Marr, P. G. Coffey, J. M. Walker, S. W. 1989-06 Book xii, 110 p. : col. maps, tables ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc29400/ ark: ark:/67531/metadc29400 English United States - Texas United States - Texas - Dallas County - Dallas United States - Texas - Rockwall County United States - Texas - Kaufman County United States - Texas - Collin County 1989

info:ark/67531/metadc29399 2011-04-04T16:13:22Z partner:UNTCAS collection:UNTSW access_rights:public

Remote Sensing and GIS for Nonpoint Source Pollution Analysis in the City of Dallas' Western Watersheds University of North Texas. Dept. of Biological Sciences Watershed management -- Remote sensing. Watershed management -- United States -- Case studies. Geographic information systems. Landscape and Nature - Water - Lakes Landscape and Nature - Water - Rivers nonpoint source pollution watersheds Western Watersheds lakes rivers Lake Lewisville Lake Ray Roberts Lake Grapevine Trinity River dams Frazier Dam This report describes the findings of a study conducted on the watersheds of "Lake Lewisville, Lake Ray Roberts, Lake Grapevine and the Elm Fork of the Trinity River between Lake Lewisville and Frazier Dam," which are all part of the upper Trinity drainage basin (p. 31). The study examines the potential benefit of "remote sensing and geographic information systems (GIS) for watershed management" in and around Dallas, Texas (p. i). University of North Texas Atkinson, S. F. Dickson, K. L. Shaw, D. M. Hunter, B. A. Marr, P. G. Martin, K. R. 1988-08 Book x, 131 p. : col. maps, ports., tables ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc29399/ ark: ark:/67531/metadc29399 English United States - Texas - Dallas County - Dallas United States - Texas - Denton County - Denton United States - Texas - Tarrant County 1988

info:ark/67531/metadc29393 2012-12-21T12:51:29Z partner:UNTCAS collection:UNTSW access_rights:public

Historic Archaeology of the Johnson and Jones Farmsteads in the Ray Roberts Lake Area: 1850-1950 University of North Texas. Institute of Applied Sciences. Ray Roberts Lake Region (Tex.) -- Antiquities. Excavations (Archaeology) -- Texas -- Ray Roberts Lake Region. Farms -- Texas -- Ray Roberts Lake Region -- History. archaeological excavations farming farmsteads lakes Lake Ray Roberts construction recreational parks architecture genealogical data tax rolls population census Jones Farm Johnson Farm farm equipment This study represents the findings of research done on the Jones and Johnson farms, "situated in Johnson Branch Park in the north-central portion of the Ray Roberts Lake area." The purpose of the study was to offset future disturbances and damages to these farmsteads, and it includes "archival investigations, architectural documentation, oral-history interviews of long-time area residents and family members, farm equipment and artifact analyses, archaeological excavations, stabilization measures, and the development of interpretative exhibits for area schools, museums, and the general public" (p. i). University of North Texas. Institute of Applied Sciences U.S. Army. Corps of Engineers. Lebo, Susan A. Ferring, C. Reid Horn, Carin E. Skiles, Bob D. Yates, Bonnie C. 1996 Book viii, 233 p. : ill., ports. ; 28 cm. Text oclc: 37216539 http://digital.library.unt.edu/ark:/67531/metadc29393/ ark: ark:/67531/metadc29393 English United States - Texas United States - Texas - Denton County United States - Texas - Cooke County 1850-1950

info:ark/67531/metadc30854 2012-12-05T17:09:11Z partner:UNTCAS collection:UNTSW access_rights:public

The Media and Communication Industries: A 21st Century Perspective Albarran, Alan B. communications industries markets transformations This article discusses the media and communication industry. The media and communication industries are experiencing unprecedented change and evolution in the 21st century. This article examines this process with a case study method by analyzing the traditional and new media sectors using the following criteria: the markets in which they are engaged, the leaders in each of the respective industries, the economic potential of these industries, and their continuing evolution and transforming processes. The article argues that the media and communications industries can no longer be identified in terms of core sectors such as broadcasting or newspapers, but rather to a different structure of activities involving such areas as content, distribution, and search features. Further, the paper posits that new theoretical and methodological tools are needed by scholars to better understand the massive changes and transformation occurring across the media sector. A series of propositions concludes the paper, offering a framework on which to build future research and analysis. Universidad De Los Hemisferios 2010-11 Article 14 p. Text http://digital.library.unt.edu/ark:/67531/metadc30854/ ark: ark:/67531/metadc30854 ComHumanitas, 2010. Quito: Universidad De Los Hemisferios, pp. 1-14 English Public

info:ark/67531/metadc30853 2012-02-13T16:30:12Z partner:UNTCAS collection:UNTSW access_rights:public

Young Latinos Use of Mobile Phones: A Cross-Cultural Study Albarran, Alan B. Hutton, Brian mobile phones technologies This article is about a study designed to analyze how young people, operationalized in this study as people of Latino descent between the ages of 18-25, are using their mobile phone for various applications and what particular gratifications they derive from using the phone. But this study takes on a much larger dimension, because it involves a cross-cultural strategy. Research partners were recruited in five Latin American countries: Mexico, Colombia, Argentina, Chile and Uruguay, in order to collect data and compare it to other countries and to what is happening in the United States. Universidad de Piura Vaillard, Laura Weezel, Aldo Van Arango, German Gutierrez, Maria Elena Hudson, Eileen 2009 Article 15 p. Text http://digital.library.unt.edu/ark:/67531/metadc30853/ ark: ark:/67531/metadc30853 Revista de Comunicacion, 2009. Piura: Universidad de Piura, pp. 95-108. English Public

info:ark/67531/metadc32968 2013-03-12T18:53:54Z partner:UNTCAS collection:UNTSW access_rights:public

Reversing the Bricks: The Evolution of ETDs at UNT Terrell, Sandra L. electronic theses electronic dissertations ETDs This presentation discusses electronic theses and dissertations (ETDs). Beginning in fall 1999, UNT has required the submission of theses and dissertations in electronic format. As an early adopter of what was to become the electronic thesis and dissertation (ETD) movement in higher education, UNT encountered and overcame several challenges in the pursuit of providing greater public access to the scholarship conducted at the University. Dr. Terrell was there from the very beginning, and will share her unique perspective on how far the ETD movement has come, and what challenges remain. Texas Electronic Thesis and Dissertation Association 2011-03-31 Presentation 12 p. Image http://digital.library.unt.edu/ark:/67531/metadc32968/ ark: ark:/67531/metadc32968 Texas ETD Association (TxETD) Annual Conference, 2011, Arlington, Texas, United States English Public

info:ark/67531/metadc33119 2012-12-14T17:28:39Z partner:UNTCAS collection:UNTSW access_rights:public

UNT Wellness Initiative UNT Speaks Out Vosvick, Mark A. Williamson, Celia health wellness This presentation is part of the faculty lecture series UNT Speaks Out, the Symposium on Well-Being. In this presentation, the author discusses the importance of quality of life to achieve happiness and wellness. UNT Libraries 2011-03-24 Presentation 22 p. Image http://digital.library.unt.edu/ark:/67531/metadc33119/ ark: ark:/67531/metadc33119 UNT Speaks Out: Symposium on Well-Being, 2011, Denton, Texas, United States English Symposium on Well-Being, ark:/67531/metadc33116 Public

info:ark/67531/metadc33118 2012-12-14T17:24:27Z partner:UNTCAS collection:UNTSW access_rights:public

U.S. Mexico Migration UNT Speaks Out Molina, David J. immigration populations This presentation is part of the faculty lecture series UNT Speaks Out on Unauthorized Immigration. This presentation discusses immigration, specifically between the United States and Mexico. UNT Libraries 2011-04-13 Presentation 21 p. Image http://digital.library.unt.edu/ark:/67531/metadc33118/ ark: ark:/67531/metadc33118 UNT Speaks Out on Unauthorized Immigration, 2011, Denton, Texas, United States English Unauthorized Immigration, ark:/67531/metadc33117 Unauthorized Immigration, ark:/67531/metadc84158 Public

info:ark/67531/metadc36278 2012-12-17T11:51:56Z partner:UNTCAS collection:UNTSW access_rights:public

Who Are These Unauthorized Immigrants and What Are We Going To Do About Them? UNT Speaks Out Martinez-Ebers, Valerie immigration populations foreign-born This presentation is part of the faculty lecture series UNT Speaks Out on Unauthorized Immigration. This presentation discusses immigration in the United States, unauthorized immigration, and policies in place on immigration. UNT Libraries 2011-04-13 Presentation 30 p. Image http://digital.library.unt.edu/ark:/67531/metadc36278/ ark: ark:/67531/metadc36278 UNT Speaks Out on Unauthorized Immigration, 2011, Denton, Texas, United States English Unauthorized Immigration, ark:/67531/metadc33117 Unauthorized Immigration, ark:/67531/metadc84158 Public

info:ark/67531/metadc36311 2013-04-25T16:09:59Z partner:UNTCAS collection:UNTSW access_rights:public

The History Engine: Doing History with Digital Tools Nelson, Robert K. Nesbit, Scott Torget, Andrew J., 1978- teaching essays history narratives This article discusses the History Engine project. One of the primary goals of the History Engine project has been to design a research and writing exercise modest enough in its analytical scope and its length that it allows students to "do history" long before a senior seminar or capstone course. Another important goal, discussed in this article, is to capture this research to amass a large history archive. Academic Commons 2009-09-09 Article 6 p. Text http://digital.library.unt.edu/ark:/67531/metadc36311/ ark: ark:/67531/metadc36311 English Public

info:ark/67531/metadc38888 2012-12-06T16:48:47Z partner:UNTCAS collection:UNTSW access_rights:public

Peer Review and the Ex Ante Assessment of Societal Impacts Holbrook, J. Britt Frodeman, Robert peer reviews scientific research funding agencies This article discusses peer review. Funding agencies and research councils around the world rely on peer review to assess the potential impacts of proposed research. This article compares the procedures of two major public science agencies - the US National Science Foundation and the European Commission's 7th Framework Programme - for evaluating ex ante the potential societal impact of research proposals. In this paper the authors survey the state of the art and discuss some of the conceptual questions that arise in using ex ante peer review to assess the societal impact of scientific research. Beech Tree 2011 Article 13 p. Text doi: 10.3152/095820211X12941371876788 http://digital.library.unt.edu/ark:/67531/metadc38888/ ark: ark:/67531/metadc38888 Research Evaluation, 2011, Guildford: Beech Tree Publishing, pp. 239-246 English Public

info:ark/67531/metadc38891 2013-03-28T12:46:29Z partner:UNTCAS collection:UNTSW access_rights:public

Discourse Variations Between Usability Tests and Usability Reports Friess, Erin usability evaluations discourse analyses do-it-yourself usability testing evaluator effects data interpretations ethnography oral usability test reports This article discusses the discourse variations between usability tests and usability reports. Abstract: While usability evaluation and usability testing has become an important tool in artifact assessment, little is known about what happens to usability data as it moves from usability session to usability report. In this ethnographic case study, the author investigates the variations in the language used by usability participants in user-based usability testing sessions as compared to the language used by novice usability testers in their oral reports of that usability testing session. In these comparative discourse analyses, the author assesses the consistency and continuity of the usability testing data within the purview of the individual testers conducting "do-it-yourself" usability testing. This case study of a limited population suggests that findings in oral usability reports may or may not be substantiated in the evaluations themselves, that explicit or latent biases may affect the presentation of the findings in the report, and that broader investigations, both in terms of populations and methodologies, are warranted. Usability Professionals' Association 2011-05 Article 15 p. Text http://digital.library.unt.edu/ark:/67531/metadc38891/ ark: ark:/67531/metadc38891 Journal of Usability Studies, 2011, Bloomingdale: Usability Professionals' Association, pp. 102-116 English Public

info:ark/67531/metadc38883 2012-12-07T13:01:24Z partner:UNTCAS collection:UNTSW access_rights:public

The Sword of Data: Does Human-Centered Design Fulfill Its Rhetorical Responsibility? Friess, Erin user-centered design human-centered design This article discusses human-centered design. For more than two decades, user-centered design (UCD) has been the guiding philosophy and process in the field of design from both practice and pedagogy perspectives. Although there is no singular agreement on just what constitutes UCD and many different names for and "flavors" of UCD have emerged - human-centered design, just to name a few-nearly every version relies on an early and continual interaction with people who will actually use the product. Designers then use findings from the interactions (e.g. surveys, focus groups, card sorting exercises, document reviews, scenario-based testing, and plus-mining testing) to guide the design solutions. MIT Press 2010 Article 12 p. Text http://digital.library.unt.edu/ark:/67531/metadc38883/ ark: ark:/67531/metadc38883 Design Issues, Summer 2010, Cambridge: MIT Press, pp. 40-50 English Public

info:ark/67531/metadc38900 2013-03-21T15:35:26Z partner:UNTCAS collection:UNTSW access_rights:public

Defending Design Decisions With Usability Evidence: A Case Study Friess, Erin user-centered designs design pedagogy discourse analyses decision-making practices user interfaces This paper discusses a case study on defending design decisions with usability evidence. This case study takes a close look at what novice designers discursively use as evidence to support design decisions. User-centered design has suggested that all design decisions should be made with the concern for the user at the forefront, and, ideally, this concern should be represented by findings discovered within user-centered research. However, the data from a 12-month longitudinal study suggests that although these novice designers are well versed with user-centered design theory, in practice they routinely do not use user-centered research findings to defend their design decisions. Instead these novice designers use less definitive and more designer-centered forms of evidence. This move away from the user, though perhaps unintentional, may suggest that design pedagogy may need to be re-evaluated to ensure that novice designers continue to adhere to the implications of user-centered research throughout the design process. Association for Computing Machinery SIGCHI (Group : U.S.) 2008 Paper 8 p. Text http://digital.library.unt.edu/ark:/67531/metadc38900/ ark: ark:/67531/metadc38900 Conference on Human Factors in Computing Systems (CHI), 2008, Florence, Italy English Public

info:ark/67531/metadc38899 2013-03-21T15:35:32Z partner:UNTCAS collection:UNTSW access_rights:public

Decision-Making Strategies in Design Meetings Friess, Erin user-centered designs usability studies argumentations discourse analyses empirical studies design process theories design pedagogy user interfaces This paper is about research on decision-making strategies in design meetings. Abstract: This project aims to further our understanding of the practice of user-centered design (UCD) by observing the argumentation strategies used by designers in face-to-face meetings in the critical periods between usability research and prototype iteration. In order to conduct such an investigation, the author recorded ten meetings of graduate student designers charged with redesigning documents for the United States Postal Service. The author then used discourse analysis techniques to determine how the designers used findings from research phases as evidence to support proposed design decisions in meetings concerning prototype alterations. Results show that these designers overwhelmingly do not support their design decisions with specific evidence from usability studies. This neglect of research-based evidence may indicate that these novice UCD designers may resort to designer-centric design behaviors in decision-making periods. The authors' analysis will focus on the rhetorical reasons why designers may avoid research-based evidence. Association for Computing Machinery SIGCHI (Group : U.S.) 2007 Paper 4 p. Text http://digital.library.unt.edu/ark:/67531/metadc38899/ ark: ark:/67531/metadc38899 Conference on Human Factors in Computing Systems (CHI), 2007, San Jose, California, United States English Public

info:ark/67531/metadc38898 2012-12-21T13:05:38Z partner:UNTCAS collection:UNTSW access_rights:public

[Review] Communications and Management at Work Friess, Erin organizational communications management This book review discusses 'Communication and Management at Work' by Thomas Klikauer. The book, intended primarily for scholars of management, business, and organizational communication, invokes the theories of Kant, Habermas, Orwell, and Marx to assess at a macro level the historical and contemporary relationships between communication and control in the workplace. Cambridge University Press 2008 Review 2 p. Text http://digital.library.unt.edu/ark:/67531/metadc38898/ ark: ark:/67531/metadc38898 Language in Society, 2008, New York: Cambridge University Press, pp. 768-769 English Public

info:ark/67531/metadc39329 2012-12-21T13:11:57Z partner:UNTCAS collection:UNTSW access_rights:public

[Review] Nexus of Empire: Negotiating Loyalty and Identity in the Revolutionary Borderlands Torget, Andrew J. empires borderlands This book review discusses 'Nexus of Empire: Negotiating Loyalty and Identity in the Revolutionary Borderlands' edited by Gene Allen Smith and Sylvia L. Hilton. The book examines the individuals who inhabited the Gulf of Mexico regions, analyzing the ways in which these people defined and redefined themselves amid a world of competing loyalties. Texas State Historical Association (TSHA) 2011-01 Review 2 p. Text http://digital.library.unt.edu/ark:/67531/metadc39329/ ark: ark:/67531/metadc39329 Southwestern Historical Quarterly, 2011, Denton: Texas State Historical Association (TSHA), pp. 329-330 English Public

info:ark/67531/metadc39326 2013-04-08T16:17:22Z partner:UNTCAS collection:UNTSW access_rights:public

Examining Error in the Technical Communication Editing Test Boettger, Ryan K. technical communications usage errors This paper discusses examining errors in technical communication. Abstract: Usage error is a popular topic for technical communicators. However, its anecdotal discussions remain the best source of information on the errors that technical communicators might value over others. In this paper, the author reports the types and frequencies of errors found in 41 editing tests administered to prospective technical writers and editors. Results indicate that misspellings and faulty/missing capitalization were the most frequent and dispersed errors. Eight of the most frequent errors related to style; however, grammar punctuation errors remain the most dispersed. A larger dataset will better determine how technical communicators prioritize specific errors. Society for Technical Communication Society for Technical Communication 2011 Paper 6 p. Text http://digital.library.unt.edu/ark:/67531/metadc39326/ ark: ark:/67531/metadc39326 Society for Technical Communication Technical Communication Summit, 2011, Sacramento, California, United States English Public

info:ark/67531/metadc39316 2012-12-21T13:30:57Z partner:UNTCAS collection:UNTSW access_rights:public

Unions of Slavery: Slavery, Politics, and Secession in the Valley of Virginia Crucible of the Civil War: Virginia from Secession to Commemoration Torget, Andrew J. slavery politics secession This book chapter discusses slavery, politics, and secession in the Valley of Virginia. University of Virginia Press 2006 Book Chapter 47 p. Text http://digital.library.unt.edu/ark:/67531/metadc39316/ ark: ark:/67531/metadc39316 Crucible of the Civil War: Virginia from Secession to Commemoration, 2006, Charlottesville: University of Virginia Press, pp. 28-74 English Public

info:ark/67531/metadc40401 2013-03-20T16:47:17Z partner:UNTCAS collection:UNTSW access_rights:public

Correlation Function and Generalized Master Equation of Arbitrary Age Allegrini, Paolo Aquino, Gerardo Grigolini, Paolo Palatella, Luigi Rosa, Angelo West, Bruce J. non-Poisson arbitrary ages This article discusses correlation function and generalized master equation of arbitrary age. Abstract: We study a two-state statistical process with a non-Poisson distribution of sojourn times. In accordance with earlier work, we find that this process is characterized by aging and we study three different ways to define the correlation function of arbitrary age of the corresponding dichotomous fluctuation. These three methods yield exact expressions, thus coinciding with the recent result by Godrèche and Luck [J. Stat. Phys. 104, 489 (2001)]. Actually, non-Poisson statistics yields infinite memory at the probability level, thereby breaking any form of Markovian approximation, including the one adopted herein, to find an approximated analytical formula. For this reason, we check the accuracy of this approximated formula by comparing it with the numerical treatment of the second of the three exact expressions. We find that, although not exact, a simple analytical expression for the correlation function of arbitrary age is very accurate. We establish a connection between the correlation function and a generalized master equation of the same age. Thus this formalism, related to models used in glassy materials, allows us to illustrate an approach to the statistical treatment of blinking quantum dots, bypassing the limitations fo the conventional Liouville treatment. American Physical Society 2005-06-10 Article 12 p. Text doi: 10.1103/PhysRevE.71.066109 http://digital.library.unt.edu/ark:/67531/metadc40401/ ark: ark:/67531/metadc40401 Physical Review E, 2005, College Park: American Physical Society English Public

info:ark/67531/metadc40398 2013-03-14T17:25:02Z partner:UNTCAS collection:UNTSW access_rights:public

Brain, Music, and Non-Poisson Renewal Processes Bianco, Simone Ignaccolo, Massimiliano Rider, Mark S. Ross, Mary J. Winsor, Phil Grigolini, Paolo non-Poisson electroencephalograms This article discusses brain, music, and non-Poisson renewal processes. Abstract: In this paper we show that both music composition and brain function, as revealed by the electroencephalogram (EEG) analysis, are renewal non-Poisson processes living in the nonergodic dominion. To reach this important conclusion the authors process the data with the minimum spanning tree method, so as to detect significant events, thereby building a sequence of times, which is the time series to analyze. The the authors show that in both cases, EEG and music composition, these significant events are the signature of a non-Poisson renewal process. This conclusion is reached using a technique of statistical analysis recently developed by the authors' group, the aging experiment (AE). First, the authors find that in both cases the distances between two consecutive events are described by nonexponential histograms, thereby proving the non-Poisson nature of these processes. The corresponding survival probabilities ψ(t) are well fitted by stretched exponentials [ψ(t) ∝ exp (-(yt)a), with 0.5<a<1.] The second step rests on the adoption of AE, which shows that these are renewal processes. The authors show that the stretched exponential, due to its renewal character, is the emerging tip of an iceberg, whose underwater part has slow tails with an inverse power law structure with power index μ=1+ơ. Adopting the AE procedure, the authors find that both EEG and music composition yield μ<2. On the basis of the recently discovered complexity driving signal P with μp⩽μs, the authors conclude that the results of their analysis may explain the influence of music on the human brain. American Physical Society 2007-06-21 Article 10 p. Text doi: 10.1103/PhysRevE.75.061911 http://digital.library.unt.edu/ark:/67531/metadc40398/ ark: ark:/67531/metadc40398 Physical Review E, 2007, College Park: American Physical Society English Public

info:ark/67531/metadc40391 2013-03-19T15:35:07Z partner:UNTCAS collection:UNTSW access_rights:public

Control of Root Architecture and Nodulation by the LATD/NIP Transporter Harris, Jeanne M. Dickstein, Rebecca nodule developments lateral root developments root architecture symbiotic nitrogen fixations Medicago truncatula NRT1(PTR) gene families This article discusses root architecture and nodulation. Abstract: The Medicago truncatula LATD/NIP gene is essential for the development of lateral and primary root and nitrogen-fixing nodule meristems as well as for rhizobial invasion of nodules. LATD/NIP encodes a member of the NRT1(PTR1) nitrate and di-and tri-peptide transporter family, suggesting that its function is to transport one of these or another compound(s). Because latd/nip mutants can have their lateral and primary root defects rescued by ABA, ABA is a potential substrate for transport. LATD/NIP expression in the root meristem was demonstrated to be regulated by auxin, cytokinin and abscisic acid, but not by nitrate. LATD/NIP's potential function and its role in coordinating root architecture and nodule formation are discussed. Landes Bioscience 2010-11 Article 5 p. Text http://digital.library.unt.edu/ark:/67531/metadc40391/ ark: ark:/67531/metadc40391 Plant Signaling and Behavior, 2010, Austin: Landes Bioscience, pp. 1365-1369 English Public

info:ark/67531/metadc40414 2013-03-11T17:55:19Z partner:UNTCAS collection:UNTSW access_rights:public

The AGC Kinase MtIRE: A Link to Phospholipid Signaling During Nodulation? Pislariu, Catalina I. Dickstein, Rebecca AGC kinase nitrogen fixations nodulation Medicago truncatula Sinorhizobium meliloti infection zones 3-phosphoinositide-dependent kinase root hair elongations This article discusses the AGC Kinase gene MtIRE. Abstract: The development of nitrogen fixing root nodules is complex and involves an interplay of signaling processes. During maturation of plant host cells and their endocytosed rhizobia in symbiosomes, host cells and symbiosomes expand. This expansion is accompanied by a large quantity of membrane biogenesis. The authors recently characterized an AGC kinase gene, MtIRE, that could play a role in this expansion. MtIRE's expression coincides with host cell and symbiosome expansion in the proximal side of the invasion zone in developing Medicago truncatula nodules. MtIRE's closest homolog is the Arabidopsis AGC kinase family IRE gene, which regulates root hair elongation. AGC kinases are regulated by phospholipid signaling in animals and fungi as well as in the several instances where they have been studied in plants. Here we suggest that a phospholipid signaling pathway may also activate MtIRE activity and propose possible upstream activators of MtIRE protein's presumed AGC kinase activity. Landes Bioscience 2007 Article 3 p. Text http://digital.library.unt.edu/ark:/67531/metadc40414/ ark: ark:/67531/metadc40414 Plant Signaling and Behavior, 2007, Austin: Landes Bioscience, pp. 314-316 English Public

info:ark/67531/metadc40407 2013-03-14T13:45:26Z partner:UNTCAS collection:UNTSW access_rights:public

Beyond the Death of Linear Response: 1/f Optimal Information Transport Aquino, Gerardo Bologna, Mauro Grigolini, Paolo West, Bruce J. linear responses nonergodic processes 1/f noises This article discusses linear response and 1/f optimal information transport. Article: Nonergodic renewal processes have recently been shown by several authors to be insensitive to periodic perturbations, thereby apparently sanctioning the death of linear response, a building block of nonequilibrium statistical physics. The authors show that it is possible to go beyond the "death of linear response" and establish a permanent correlation between an external stimulus and the response of a complex network generating nonergodic renewal processes, by taking as stimulus a similar nonergodic process. The ideal condition of 1/f noise corresponds to a singularity that is expected to be relevant in several experimental conditions. American Physical Society 2010-07-21 Article 4 p. Text doi: 10.1103/PhysRevLett.105.040601 http://digital.library.unt.edu/ark:/67531/metadc40407/ ark: ark:/67531/metadc40407 Physical Review Letters, 2010, College Park: American Physical Society English Publisher's Note: Beyond the Death of Linear Response: 1/f Optimal Information Transport [Phys. Rev. Lett. 105,040601 (2010)] Public

info:ark/67531/metadc40410 2013-03-19T14:08:25Z partner:UNTCAS collection:UNTSW access_rights:public

Complexity and Synchronization Turalska, Malgorzata Lukovic, Mirko West, Bruce J. Grigolini, Paolo decision making information transmission This article discusses complexity and synchronization. Abstract: We study a fully connected network (cluster) of interacting two-state units as a model of cooperative decision making. Each unit in isolation generates a Poisson process with rate g. We show that when the number of nodes is finite, the decision-making process becomes intermittent. The decision-time distribution density is characterized by inverse power-law behavior with index μ=1.5 and is exponentially truncated. We find that the condition of perfect consensus is recovered by means of a fat tail that becomes more and more extended with increasing numbers of nodes N. The intermittent dynamics of the global variable are described by the motion of a particle in a double well potential. The particle spends a portion of the total time τs at the top of the potential barrier. Using theoretical and numerical arguments it is proved that τs ∝ (1/g)1n(const X N). The second portion of its time, τk, is spent by the particle at the bottom of the potential well and it is given by τk=(1/g)exp(const X N). We show that the time τk is responsible for the Kramers fat tail. This generates a stronger ergodicity breakdown than that generated by the inverse power law without truncation. The authors establish that the condition of partial consensus can be transmitted from one cluster to another provided that both networks are in a cooperative condition. No significant information transmission is possible if one of the two networks is not yet self-organized. We find that partitioning a large network into a set of smaller interacting clusters has the effect of converting the fat Kramers tail into an inverse power law with μ=1.5. American Physical Society 2009-08-14 Article 12 p. Text doi: 10.1103/PhysRevE.80.021110 http://digital.library.unt.edu/ark:/67531/metadc40410/ ark: ark:/67531/metadc40410 Physical Review E, 2009, College Park: American Physical Society English Public

info:ark/67531/metadc40408 2013-04-01T13:30:40Z partner:UNTCAS collection:UNTSW access_rights:public

Dynamics of Electroencephalogram Entropy and Pitfalls of Scaling Detection Ignaccolo, Massimiliano Latka, Miroslaw Jernajczyk, Wojciech Grigolini, Paolo West, Bruce J. diffusion entropy electroencephalograms This article discusses dynamics of electroencephalogram entropy and pitfalls of scaling detection. Abstract: In recent studies a number of research groups have determined that human electroencephalograms (EEG) have scaling properties. In particular, a crossover between two regions with different scaling exponents has been reported. Herein the authors study the time evolution of diffusion entropy to elucidate the scaling of EGG time series. For a cohort of 20 awake healthy volunteers with closed eyes, the authors find that the diffusion entropy of EEG increments (obtained from EEG waveforms by differencing) exhibits three features: short-time growth, an alpha wave related oscillation whose amplitude gradually decays in time, and asymptotic saturation which is achieved after approximately 1 s. This analysis suggests a linear, stochastic Ornstein-Uhlenbeck Langevin equation with a quasiperiodic forcing (whose frequency and/or amplitude may vary in time) as the model for the underlying dynamics. This model captures the salient properties of EEG dynamics. In particular, both the experimental and simulated EEG time series exhibit short-time scaling which is broken by a strong periodic component, such as alpha waves. The saturation of EEG diffusion entropy precludes the existence of asymptotic scaling. We find that the crossover between two scaling regions seen in detrended fluctuation analysis (DFA) of EEG increments does not originate from the underlying dynamics but is merely an artifact of the algorithm. This artifact is rooted in the failure of the "trend plus signal" paradigm of DFA. American Physical Society 2010-03-10 Article 9 p. Text doi: 10.1103/PhysRevE.81.031909 http://digital.library.unt.edu/ark:/67531/metadc40408/ ark: ark:/67531/metadc40408 Physical Review E, 2010, College Park: American Physical Society English Public

info:ark/67531/metadc40399 2013-04-01T13:14:52Z partner:UNTCAS collection:UNTSW access_rights:public

Dynamical Origin of Memory and Renewal Cakir, Rasit Grigolini, Paolo Krokhin, Arkadii A. fractional Brownian motion non-Poisson Lévy This article discusses a dynamical origin of memory and renewal. Abstract: We show that the dynamic approach to fractional Brownian motion (FBM) establishes a link between a non-Poisson renewal process with abrupt jumps resetting to zero the system's memory and correlated dynamic processes, whose individual trajectories keep a nonvanishing memory of their past time evolution. It is well known that the recrossings of the origin by an ordinary one-dimensional diffusion trajectory generates a Lévy (and thus renewal) process of index θ=1/2. We prove with theoretical and numerical arguments that this is the special case of a more general condition, insofar as the recrossings produced by the dynamic FBM generates a Lévy process with 0<θ<1. This result is extended to produce a satisfactory model for the fluorescent signal of blinking quantum dots. American Physical Society 2006-08-08 Article 6 p. Text doi: 10.1103/PhysRevE.74.021108 http://digital.library.unt.edu/ark:/67531/metadc40399/ ark: ark:/67531/metadc40399 Physical Review E, 2006, College Park: American Physical Society English Public

info:ark/67531/metadc40405 2012-05-10T16:22:11Z partner:UNTCAS collection:UNTSW access_rights:public

Memory Effects in Fractional Brownian Motion with Hurst Exponent H<1/3 Bologna, Mauro Vanni, Fabio Krokhin, Arkadii Grigolini, Paolo fractional Brownian motions Hurst exponents In this article, the authors study the regression to the origin of a walker driven by dynamically generated fractional Brownian motion (FBM) and the authors prove that when the FBM scaling, i.e., the Hurst exponent H<1/3, the emerging inverse power law is characterized by a power index that is a compelling signature of the infinitely extended memory of the system. Strong memory effects leads to the relation H=θ/2 between the Hurst exponent and the persistent exponent θ, which is different from the widely used relation H=1 - θ. The latter is valid for 1/3<H<1 and is known to be compatible with the renewal assumption. American Physical Society 2010-08-27 Article 4 p. Text doi: 10.1103/PhysRevE.82.020102 http://digital.library.unt.edu/ark:/67531/metadc40405/ ark: ark:/67531/metadc40405 Physical Review E, 2010, College Park: American Physical Society English Public

info:ark/67531/metadc40402 2012-05-10T15:57:26Z partner:UNTCAS collection:UNTSW access_rights:public

Temporal Complexity of the Order Parameter at the Phase Transition Turalska, Malgorzata West, Bruce J. Grigolini, Paolo decision making models criticality In this article, the authors study a decision making model in a condition where it is equivalent to the two-dimensional Ising model, and the authors show that at the onset of phase transition it generates temporal complexity, namely, nonstationary and nonergodic fluctuations. The authors argue that this is a general property of criticality, thereby opening the door to the application of the recently discovered phenomenon of complexity matching: For an efficient transfer of information to occur, a perturbing complex network must share the same temporal complexity as the perturbed complex network. American Physical Society 2011-06-24 Article 6 p. Text doi: 10.1103/PhysRevE.83.061142 http://digital.library.unt.edu/ark:/67531/metadc40402/ ark: ark:/67531/metadc40402 Physical Review E, 2011, College Park: American Physical Society English Public

info:ark/67531/metadc40400 2012-05-10T16:30:22Z partner:UNTCAS collection:UNTSW access_rights:public

Renewal, Modulation, and Superstatistics in Times Series Allegrini, Paolo Barbi, Francesco Grigolini, Paolo Paradisi, Paolo renewals modulations superstatistics In this article, the authors consider two different approaches, to which the authors refer to as renewal and modulation, to generate time series with a nonexponential distribution of waiting times. The authors show that different time series with the same waiting time distribution are not necessarily statistically equivalent, and might generate different physical properties. Renewal generates aging and anomalous scaling, while modulation yields no significant aging and either ordinary or anomalous diffusion, according to the dynamic prescription adopted. The authors show, in fact, that the physical realization of modulation generates two classes of events. The events of the first class are determined by the persistent use of the same exponential time scale for an extended lapse of time, and consequently are numerous; the events of the second class are identified with the abrupt changes from one to another exponential prescription, and consequently are rare. The events of the second class, although rare, determine the scaling of the diffusion process, and for this reason the authors term them as crucial events. According to the prescription adopted to produce modulation, the distribution density of the time distances between two consecutive crucial events might have, or not, a diverging second moment. In the former case the resulting diffusion process, although going through a transition regime very extended in time, will eventually become anomalous. In conclusion, modulation rather than ruling out the action of renewal events, produces crucial events hidden by clouds of exponential events, thereby setting the challenge for their identification. American Physical Society 2006-04-27 Article 13 p. Text doi: 10.1103/PhysRevE.73.046136 http://digital.library.unt.edu/ark:/67531/metadc40400/ ark: ark:/67531/metadc40400 Physical Review E, 2006, College Park: American Physical Society English Public

info:ark/67531/metadc40404 2012-05-10T15:59:03Z partner:UNTCAS collection:UNTSW access_rights:public

Transmission of Information Between Complex Systems: 1/ f resonance Aquino, Gerardo Bologna, Mauro West, Bruce J. Grigolini, Paolo generalized fluctuation-dissipation theorem 1/f noise In this article, the authors study the transport of information between two complex systems with similar properties. Both systems generate non-Poisson renewal fluctuations with a power-law spectrum 1/f 3-μ, the case μ=2 corresponding to ideal 1/f noise. The authors denote by μs and μp the power-law indexes of the system of interest S and the perturbing system P, respectively. By adopting a generalized fluctuation-dissipation theorem (FDT) the authors show that the ideal condition of 1/f noise for both systems corresponds to maximal information transport. The authors prove that to make the system S respond when μs < 2 the authors have to set the condition μp < 2. In the latter case, if μp < μs, the system S inherits the relaxation properties of the perturbing system. In the case where μp > 2, no response and no information transmission occurs in the long-time limit. The authors consider two possible generalizations of the fluctuation dissipation theorem and show that both lead to maximal information transport in the condition of 1/f noise. American Physical Society 2011-05-31 Article 12 p. Text doi: 10.1103/PhysRevE.83.051130 http://digital.library.unt.edu/ark:/67531/metadc40404/ ark: ark:/67531/metadc40404 Physical Review E, 2011, College Park: American Physical Society English Public

info:ark/67531/metadc40409 2012-05-10T15:56:31Z partner:UNTCAS collection:UNTSW access_rights:public

Spontaneous Brain Activity as a Source of Ideal 1/f Noise Allegrini, Paolo Menicucci, Danilo Bedini, Remo Fronzoni, Leone Gemignani, Angelo Grigolini, Paolo West, Bruce J. Paradisi, Paolo electroencephalogram 1/f noise In this article, the authors study the electroencephalogram (EEG) of 30 closed-eye subjects with a technique of analysis recently proposed to detect punctual events signaling rapid transitions between different metastable states. After single-EEG-channel event detection, the authors study global properties of events simultaneously occurring among two or more electrodes termed coincidences. The authors convert the coincidences into a diffusion process with three distinct rules that can yield the same μ only in the case where the coincidences are driven by a renewal process. The authors establish that the time interval between two consecutive renewal events driving the coincidences has a waiting-time distribution with inverse power-law index μ≈2 corresponding to ideal 1/f noise. The authors argue that this discovery, shared by all subjects of our study, supports the conviction that 1/f noise is an optimal communication channel for complex networks as in art or language and may therefore be the channel through which the brain influences complex processes and is influenced by them. American Physical Society 2009-12-18 Article 13 p. Text doi: 10.1103/PhysRevE.80.061914 http://digital.library.unt.edu/ark:/67531/metadc40409/ ark: ark:/67531/metadc40409 Physical Review E, 2009, College Park: American Physical Society English Public

info:ark/67531/metadc40403 2012-05-10T16:27:38Z partner:UNTCAS collection:UNTSW access_rights:public

Non-Poisson Dichotomous Noise: Higher-Order Correlation Functions and Aging Allegrini, Paolo Grigolini, Paolo Palatella, Luigi West, Bruce J. non-Poisson correlation functions In this article, the authors study a two-state symmetric noise, with a given waiting time distribution ψ(τ), and focus their attention on the connection between the four-time and two-time correlation functions. The transition of ψ(τ) from the exponential to the nonexponential condition yields the breakdown of the usual factorization condition of high-order correlation functions, as well as the birth of aging effects. The authors discuss the subtle connections between these two properties and establish the condition that the Liouville-like approach has to satisfy in order to produce a correct description of the resulting diffusion process. American Physical Society 2004-10-26 Article 9 p. Text doi: 10.1103/PhysRevE.70.046118 http://digital.library.unt.edu/ark:/67531/metadc40403/ ark: ark:/67531/metadc40403 Physical Review E, 2004, College Park: American Physical Society English Public

info:ark/67531/metadc40415 2012-05-10T16:10:48Z partner:UNTCAS collection:UNTSW access_rights:public

Rapid Analysis of Legume Root Nodule Development Using Confocal Microscopy Haynes, Janine G. Czymmek, Kirk J. Carlson, Carol A. Veereshlingam, Harita Dickstein, Rebecca Sherrier, D. Janine bacteroids CLSM confocal laser scanning microscopy Medicago truncatula nitrogen fixations nodules rhizobia SYTO mutants This article discusses the rapid analysis of legume root nodule development using confocal microscopy. A rapid method for detailed analysis of nodule formation has been developed. Inoculated root tissues were stained with SYTO 13, a cell-permeant fluorescent nucleic acid-binding dye, and visualized using confocal laser scanning microscopy (CLSM). Structures with high concentrations of DNA and RNA, such as plant cell nuclei and bacteria, labeled strongly. The autofluorescent properties of cell walls made it possible to use CLSM to visualize both plant and rhizobial structures and generate a three-dimensional reconstruction of the root and invading bacteria. This method allowed clear observation of stages and structures important in nodule formation, such as rhizobial attachment to root hairs, hair deformation, infection thread ramification, nodule primordium development and nodule cell invasion. Bacteroid structures were easily were easily assessed without the need for fixation that might alter cellular integrity. Plant nodulation mutants with phenotypic differences in thread growth, cellular invasion and plant defense response were also documented. Multiple samples can be assessed using detailed microscopy without the need for extensive preparative work, labor-intensive analysis, or the generation of genetically modified samples. New Phytologist Trust 2004 Article 8 p. Text doi: 10.1111/j.1469-8137.2004.01138.x http://digital.library.unt.edu/ark:/67531/metadc40415/ ark: ark:/67531/metadc40415 New Phytologist, 2004, Lancaster: New Phytologist Trust pp. 661-668 English Public

info:ark/67531/metadc40412 2012-05-10T16:10:08Z partner:UNTCAS collection:UNTSW access_rights:public

A Putative Transporter is Essential for Integrating Nutrient and Hormone Signaling with Lateral Root Growth and Nodule Development in Medicago truncatula Yendrek, Craig R. Lee, Yi-Ching Morris, Viktoriya Liang, Yan Pislariu, Catalina I. Burkart, Graham Meckfessel, Matthew H. Salehin, Mohammad Kessler, Hilary Wessler, Heath Lloyd, Melanie Lutton, Heather Teillet, Alice Sherrier, D. Janine Journet, Etienne-Pascal Harris, Jeanne M. Dickstein, Rebecca nodule developments lateral root developments root architecture symbiotic nitrogen fixation Medicago truncatula NRT1(PTR) gene families This article discusses a putative transporter for integrating nutrient and hormone signaling with lateral root growth and nodule development in Medicago truncatula. Legume root architecture involves not only elaboration of the root system by the formation of lateral roots but also the formation of symbiotic root nodules in association with nitrogen-fixing soil rhizobia. The Medicago truncatula LATD/NIP gene plays an essential role in the development of both primary and lateral roots as well as nodule development. We have cloned the LATD/NIP gene and show that it encodes a member of the NRT1(PTR) transporter family. LATD/NIP is expressed throughout the plant. pLATD/NIP-GFP promoter-reporter fusions in transgenic roots establish the spatial expression of LATD/NIP in primary root, lateral root and nodule meristems and the surrounding cells. Expression of LATD/NIP is regulated by hormones, in particular by abscisic acid which has been previously shown to rescue the primary and lateral root meristem arrest of latd mutants. latd mutants respond normally to ammonium but have defects in responses of the root architecture to nitrate. Taken together, these results suggest that LATD/NIP may encode a nitrate transporter or transporter of another compound. Society for Experimental Biology 2010 Article 13 p. Text doi: 10.1111/j.1365-313X.2010.04134.x http://digital.library.unt.edu/ark:/67531/metadc40412/ ark: ark:/67531/metadc40412 The Plant Journal, 2010, Dallas: Society for Experimental Biology, pp. 100-112 English Public

info:ark/67531/metadc40396 2012-05-10T15:56:59Z partner:UNTCAS collection:UNTSW access_rights:public

Sun-Climate Complexity Linking West, Bruce J. Grigolini, Paolo temperature anomalies complex networks This article discusses sun-climate complexity linking. It is known that Earth's short-term temperature anomalies share the same complexity index μ as solar flares. The authors show that this property is not accidental and is a consequence of the phenomenon of information transfer based on the crucial role of non-Poisson renewal events in complex networks. American Physical Society 2008-02-29 Article 4 p. Text doi: 10.1103/PhysRevLett.100.088501 http://digital.library.unt.edu/ark:/67531/metadc40396/ ark: ark:/67531/metadc40396 Physical Review Letters, 2008, College Park: American Physical Society English Public

info:ark/67531/metadc40393 2012-05-10T16:27:08Z partner:UNTCAS collection:UNTSW access_rights:public

Non-Markovian Nonstationary Completely Positive Open-Quantum-System Dynamics Budini, Adrián A. Grigolini, Paolo Markovian quantum dynamics This article discusses non-Markovian nonstationary completely positive open-quantum-system dynamics. By modeling the interaction of a system with an environment through a renewal approach, the authors demonstrate that completely positive non-Markovian dynamics may develop some unexplored nonstandard statistical properties. The renewal approach is defined by a set of disruptive events, consisting in the action of a completely positive superoperator over the system density matrix. The random time intervals between events are described by an arbitrary waiting-time distribution. The authors show that, in contrast to the Markovian case, if one performs a system preparation (measurement) at an arbitrary time, the subsequent evolution of the density-matrix evolution is modified. The nonstationary character refers to the absence of an asymptotic master equation even when the preparation is performed at arbitrary long times. In spite this property, the authors demonstrate that operator expectation values and operators correlations have the same dynamical structure, establishing the validity of a nonstationary quantum regression hypothesis. The nonstationary property of the dynamics is also analyzed through the response of the system to an external weak perturbation. American Physical Society 2009-08-04 Article 13 p. Text doi: 10.1103/PhysRevA.80.022103 http://digital.library.unt.edu/ark:/67531/metadc40393/ ark: ark:/67531/metadc40393 Physical Review A, 2009, College Park: American Physical Society English Public

info:ark/67531/metadc40406 2012-12-21T12:18:29Z partner:UNTCAS collection:UNTSW access_rights:public

Publisher's Note: Beyond the Death of Linear Response: 1/f Optimal Information Transport [Phys. Rev. Lett. 105,040601 (2010)] Aquino, Gerardo Bologna, Mauro Grigolini, Paolo West, Bruce J. linear responses nonergodic processes 1/f noises This is a Publisher's Note for the article 'Beyond the Death of Linear Response: 1/f Optimal Information Transport' [Phys. Rev. Lett. 105, 040601 (2010)]. American Physical Society 2010-08-03 Text 1 p. Text doi: 10.1103/PhysRevLett.105.069901 http://digital.library.unt.edu/ark:/67531/metadc40406/ ark: ark:/67531/metadc40406 Physical Review Letters, 2010, College Park: American Physical Association English Beyond the Death of Linear Response: 1/f Optimal Information Transport, ark:/67531/metadc40407 Public

info:ark/67531/metadc40392 2013-03-21T11:56:27Z partner:UNTCAS collection:UNTSW access_rights:public

Criticality and Transmission of Information in a Swarm of Cooperative Units Vanni, Fabio Lukovic, Mirko Grigolini, Paolo criticality swarms of cooperative units lookout birds This article discusses criticality and transmission of information in a swarm of cooperative units. Abstract: We show that the intelligence of a swarm of cooperative units (birds) emerges at criticality, as an effect of the joint action of frequent organizational collapses and of spatial correlation as extended as the flock size. The organizational collapses make the birds become independent of one another, thereby allowing the flock to follow the direction of the lookout birds. Long-range correlation violates the principle of locality, making the lookout birds transmit information on either danger or resources with a time delay determined by the time distance between two consecutive collapses. American Physical Society 2011-08-12 Article 4 p. Text doi: 10.1103/PhysRevLett.107.078103 http://digital.library.unt.edu/ark:/67531/metadc40392/ ark: ark:/67531/metadc40392 Physical Review Letters, 2011, College Park: American Physical Society English Public

info:ark/67531/metadc40395 2013-04-08T15:06:36Z partner:UNTCAS collection:UNTSW access_rights:public

Event-Driven Power-Law Relaxation in Weak Turbulence Silvestri, Ludovico Fronzoni, Leone Grigolini, Paolo Allegrini, Paolo weak turbulence linear responses This article discusses event-driven power-law relaxation in weak turbulence. Abstract: We characterize the spectral properties of weak turbulence in a liquid crystal sample driven by an external electric field, as a function of the applied voltage, and we find a 1/f noise spectrum S(f) ∝ 1/fn within the whole range 0< ɳ <2. We theoretically explore the hypothesis that the system complexity is driven by non-Poisson events resetting the system through creation and annihilation of coherent structures, retaining no memory of previous history (crucial events). The authors study the time asymptotic regime by means of the density ψ(τ) of the time distances between two crucial events, yielding ɳ = 3 - μ, where μ is defined through the long-time form ψ(τ) ∝ 1/τµ, with 1 < µ < 3. The system regression to equilibrium after an abrupt voltage change experimentally confirms the theory, proving violations of the ordinary linear response theory for both ɳ > 1 and ɳ < 1. American Physical Society 2009-01-05 Article 4 p. Text doi: 10.1103/PhysRevLett.102014502 http://digital.library.unt.edu/ark:/67531/metadc40395/ ark: ark:/67531/metadc40395 Physical Review Letters, 2009, College Park: American Physical Society English Public

info:ark/67531/metadc40394 2013-04-08T18:04:50Z partner:UNTCAS collection:UNTSW access_rights:public

Experimental Quenching of Harmonic Stimuli: Universality of Linear Response Theory Allegrini, Paolo Bologna, Mauro Fronzoni, Leone Grigolini, Paolo Silvestri, Ludovico linear response theory equilibriums harmonic stimuli This article discusses experimental quenching of harmonic stimuli. Abstract: We show that liquid crystals in the weak turbulence electroconvective regime respond to harmonic perturbations with oscillations whose intensity decay with an inverse power law of time. We use the results of this experiment to prove that this effect is the manifestation of a form of linear response theory (LRT) valid in the out-of-equilibrium case, as well as at thermodynamic equilibrium where it reduces to the ordinary LRT. We argue that this theory is a universal property, which is not confined to physical processes such as turbulent or excitable media, and that it holds true in all possible conditions, and for all possible systems, including a complex networks, thereby establishing a bridge between statistical physics and all the fields of research in complexity. American Physical Society 2009-07-15 Article 4 p. Text doi: 10.1103/PhysRevLett.103.030602 http://digital.library.unt.edu/ark:/67531/metadc40394/ ark: ark:/67531/metadc40394 Physical Review Letters, 2009, College Park: American Physical Society English Public

info:ark/67531/metadc40397 2013-04-11T16:45:29Z partner:UNTCAS collection:UNTSW access_rights:public

Fluctuation-Dissipation Theorem for Event-Dominated Processes Allegrini, Paolo Bologna, Mauro Grigolini, Paolo West, Bruce J. non-Poisson linear responses This article discusses fluctuation-dissipation theorem for event-dominated processes. Abstract: We study a system whose dynamics are driven by non-Poisson, renewal, and nonergodic events. We show that external perturbations influencing the times at which these events occur violate the standard fluctuation-dissipation prescription due to renewal aging. The fluctuation-dissipation relation of this Letter is shown to be the linear response limit of an exact expression that has been recently proposed to account for the luminescence decay in a Gibbs ensemble of semiconductor nanocrystals, with intermittent fluorescence. American Physical Society 2007-07-06 Article 4 p. Text doi: 10.1103/PhysRevLett.99.010603 http://digital.library.unt.edu/ark:/67531/metadc40397/ ark: ark:/67531/metadc40397 Physical Review Letters, 2007, College Park: American Physical Society English Public

info:ark/67531/metadc40389 2013-05-14T13:11:53Z partner:UNTCAS collection:UNTSW access_rights:public

An IRE-Like AGC Kinase Gene, MtIRE, Has Unique Expression in the Invasion Zone of Developing Root Nodules in Medicago truncatula Pislariu, Catalina I. Dickstein, Rebecca AGC kinases MtIRE Medicago truncatula This article discusses AGC kinase genes. Abstract: The AGC protein kinase family (cAMP-dependent protein kinases A, cGMP-dependent protein kinases G, and phospholipid-dependent protein kinases C) have important roles regulating growth and development in animals and fungi. They are activated via lipid second messengers by 3-phosphoinositide-dependent protein kinase coupling lipid signals to phosphorylation of the AGC kinases. These phosphorylate downstream signal transduction protein targets. AGC kiinases are becoming better studied in plants, especially in Arabidopsis (Arabidopsis thaliana), where specific AGC kinases have been shown to have key roles in regulating growth signal pathways. The authors report here the isolation and characterization of the first AGC kinase gene identified in Medicago truncatula, MtIRE. It was cloned by homology with the Arabidopsis INCOMPLETE ROOT HAIR ELONGATION (IRE) gene. Semiquantitative reverse transcription-polymerase chain reaction analysis shows that, unlike its Arabidopsis counterpart, MtIRE is not expressed in uninoculated roots, but is expressed in root systems that have been inoculated with Sinorhizobium meliloti and are developing root nodules. MtIRE expression is also found in flowers. Expression analysis of a time course of nodule development and of nodulating root systems of many Medicago nodulation mutants shows MtIRE expression correlates with infected cell maturation during nodule development. During the course of these experiments, nine Medicago nodulation mutants, including sli and dnf1 to 7 mutants, were evaluated for the first time for their microscopic nodule phenotype using S. meliloti constitutively expressing lacZ. Spatial localization of a pMtIRE-gusA transgene in transformed roots of composite plants showed that MtIRE expression is confined to the proximal part of the invasion zone, zone II, found in indeterminate nodules. This suggests MtIRE is useful as an expression marker for this region of the invasion zone. American Society of Plant Biologists 2007-06 Article 14 p. Text doi: 10.1104/pp.106.092494 http://digital.library.unt.edu/ark:/67531/metadc40389/ ark: ark:/67531/metadc40389 Plant Physiology, 2007, Rockville: American Society of Plant Biologists, pp. 682-694 English Public

info:ark/67531/metadc40388 2013-05-20T16:38:39Z partner:UNTCAS collection:UNTSW access_rights:public

LIN, a Medicago truncatula Gene Required for Nodule Differentiation and Persistence of Rhizobial Infections Kuppusamy, Kavitha T. Endre, Gabriella Prabhu, Radhika Penmetsa, R. Varma Veereshlingam, Harita Cook, Douglas R. Dickstein, Rebecca VandenBosch, Kathryn A. Medicago truncatula genes Nod factor responses This article discusses LIN, a Medicago truncatula gene. Abstract: Ethyl methanesulfonate mutagenesis of the model legume Medicago truncatula has previously identified several genes required for early steps in nodulation. Here, the authors describe a new mutant that is defective in intermediate steps of nodule differentiation. The lin (lumpy infections) mutant is characterized by a 4-fold reduction in the number of infections, all of which arrest in the root epidermis, and by nodule primordia that initiate normally but fail to mature. Genetic analyses indicate that the symbiotic phenotype is conferred by a single gene that maps to the lower arm of linkage group 1. Transcriptional markers for early Nod factor responses (RIP1 and ENOD40) are induced in lin, as is another early nodulin, ENOD20, a gene expressed during the differentiation of nodule primordia. By contrast, other markers correlated with primordium differentiation (CCS52A), infection progression (MtN6), or nodule morphogenesis (ENOD2 and ENOD8) show reduced or no induction in homozygous lin individuals. Taken together, these results suggest that LIN functions in maintenance of rhizobial infections and differentiation of nodules from nodule primordia. American Society of Plant Biologists 2004-11 Article 10 p. Text doi: 10.1104/pp.104.045575 http://digital.library.unt.edu/ark:/67531/metadc40388/ ark: ark:/67531/metadc40388 Plant Physiology, 2004, Rockville: American Society of Plant Biologists, pp. 3682-3691 English Public

info:ark/67531/metadc67641 2013-03-11T16:28:06Z partner:UNTCAS collection:UNTSW access_rights:public

Absorption and Emission in the Non-Poissonian Case Aquino, Gerardo Palatella, Luigi Grigolini, Paolo Kubo-Anderson theory non-Poisson This article discusses absorption and emission in the Non-Poissonian Case. Abstract: This Letter addresses the challenging problems posed to the Kubo-Anderson (KA) theory by the discovery of intermittent resonant fluorescence with a nonexponential distribution of waiting times. We show how to extend the KA theory from aged to aging systems, aging for a very extended time period or even forever, being a crucial consequence of non-Poisson statistics. American Physical Society 2004-07-28 Article 4 p. Text doi: 10.1103/PhysRevLett.93.050601 http://digital.library.unt.edu/ark:/67531/metadc67641/ ark: ark:/67531/metadc67641 Physical Review Letters, 2004, College Park: American Physical Society English Public

info:ark/67531/metadc67638 2013-03-12T11:57:05Z partner:UNTCAS collection:UNTSW access_rights:public

Aging and Rejuvenation with Fractional Derivatives Aquino, Gerardo Bologna, Mauro Grigolini, Paolo West, Bruce J. fractional derivatives non-Poisson This article discusses aging rejuvenation with fractional derivatives. Abstract: We discuss a dynamic procedure that makes a fractional derivatives emerge in the time asymptotic limit of non-Poisson processes. We find that two-state fluctuations, with an inverse power-law distribution of waiting times, finite first moment, and divergent second moment, namely, with the power index μ in the interval 2<μ<3, yield a generalized master equation equivalent to the sum of an ordinary Markov contribution and a fractional derivative term. We show that the order of the fractional derivative depends on the age of the process under study. If the system is infinitely old, the order of the fractional derivative, o, is given by o=3-μ. A brand new system is characterized by the degree o=μ-2. If the system is prepared at time -tₐ<0 and the observation begins at time t=0, we derive the following scenario. For times 0<t«tₐ the system is satisfactorily described by the fractional derivative with o=3-μ. Upon time increase the system undergoes a rejuvenation process that in the time limit t⪢tₐ yields o=μ-2. The intermediate time regime is probably incompatible with a picture based on fractional derivatives, or, at least, with a mono-order fractional derivative. American Physical Society 2004-09-10 Article 11 p. Text doi: 10.1103/PhysRevE.70.036105 http://digital.library.unt.edu/ark:/67531/metadc67638/ ark: ark:/67531/metadc67638 Physical Review E, 2004, College Park: American Physical Society 70:3 English Public

info:ark/67531/metadc67609 2012-12-17T11:49:14Z partner:UNTCAS collection:UNTSW access_rights:public

What's Wrong with Processed Food? UNT Speaks Out Kaplan, David M. processed foods health genetically-modified foods nutrition This presentation is part of the faculty lecture series UNT Speaks Out on the Food We Eat. The topics include what processed food is, genetically-modified foods, functional foods, and the impacts of processed foods. UNT Libraries 2011-10-24 Presentation 27 p. Image http://digital.library.unt.edu/ark:/67531/metadc67609/ ark: ark:/67531/metadc67609 UNT Speaks Out on The Food We Eat, 2011, Denton, Texas, United States English The Food We Eat: UNT Speaks Out: ark:/67531/metadc67596 Public

info:ark/67531/metadc67629 2013-03-28T11:23:27Z partner:UNTCAS collection:UNTSW access_rights:public

Diffusion Entropy and Waiting Time Statistics of Hard-X-Ray Solar Flares Grigolini, Paolo Leddon, Deborah Scafetta, Nicola diffusion entropies inverse powers This article discusses diffusion entropy and waiting time statistics of hard-x-ray solar flares. Abstract: We show at work a technique of scaling detection based on evaluating the Shannon entropy of the diffusion process obtained by converting the time series under study into trajectories. This method, called diffusion entropy, affords information that cannot be derived from the direct evaluation of waiting times. We apply this method to the analysis of the distribution of time distance τ between two nearest-neighbor solar flares. This traditional part of the analysis is based on the direct evaluation of the distribution function ψ(τ), or of the probability ψ(τ), that no time distance smaller than a given τ is found. We adopt the paradigm of the inverse power-law behavior, and the authors focus on the determination of the inverse power index μ, without ruling out different asymptotic properties that might be revealed, at larger scales, with the help of richer statistics. We then use the DE method, with three different walking rules, and the authors focus on the regime of transition to scaling. This regime of transition and the value of the scaling parameter itself, δ, depends on the walking rule adopted, a property of interest to shed light on the slow process of transition from dynamics to thermodynamics often occurring under anomalous statistical conditions. With the first two rules the transition regime occurs through-out a large time interval, and the information contained in the time series is transmitted, to a great extent, to it, as well as to the scaling regime. By using the third rule, on the contrary, the same information is essentially conveyed to the scaling regime, which, in fact, emerges very quickly after a fast transition process. We show that the DE method not only causes to emerge the long-range correlation with a given μ<3, and so a basin of attraction different from the ordinary Gaussian one, but it also reveals the presence of memory effects induced by the time dependence of the solar flare rate. When this memory is annihilated by shuffling, the scaling parameter δ is shown to fit the theoretically expected function of μ. All this leads us to the compelling conclusion that μ=2.138±0.01. American Physical Society 2002-03-25 Article 13 p. Text doi: 10.1103/PhysRevE.65.046203 http://digital.library.unt.edu/ark:/67531/metadc67629/ ark: ark:/67531/metadc67629 Physical Review E, 2002, College Park: American Physical Society English Public

info:ark/67531/metadc67632 2012-05-10T15:55:30Z partner:UNTCAS collection:UNTSW access_rights:public

Scaling Detection in Time Series: Diffusion Entropy Analysis Scafetta, Nicola Grigolini, Paolo scaling detection diffusion entropy This article discusses scaling detection in time series. The methods currently used to determine the scaling exponent of a complex dynamic process described by a time series are based on the numerical evaluation of variance. This means that all of them can be safely applied only to the case where ordinary statistical properties hold true even if strange kinetics are involved. The authors illustrate a method of statistical analysis based on the Shannon entropy of the diffusion process generated by the time series, called diffusion entropy analysis (DEA). The authors adopt artificial Gauss and Lévy time series, as prototypes of ordinary and anomalous statistics, respectively, and the authors analyze them with the DEA and four ordinary methods of analysis, some of which are very popular. The authors show that the DEA determines the correct scaling exponent even when the statistical properties, as well as the dynamic properties, are anomalous. The other four methods produce correct results in the Gauss case but fail to detect the correct scaling in the case of Lévy statistics. American Physical Society 2002-09-25 Article 10 p. Text doi: 10.1103/PhysRevE.66.036130 http://digital.library.unt.edu/ark:/67531/metadc67632/ ark: ark:/67531/metadc67632 Physical Review E, 2002, College Park: American Physical Society English Public

info:ark/67531/metadc67637 2012-05-10T16:29:50Z partner:UNTCAS collection:UNTSW access_rights:public

Random Growth of Interfaces as a Subordinated Process Failla, Roberto Grigolini, Paolo Ignaccolo, Massimiliano Schwettmann, Arne Kardar-Parisi-Zhang theory subordinated processes In this article, the authors study the random growth of surfaces from within the perspective of a single column, namely, the fluctuation of the column height around the mean value, y(τ)=h(τ)-‹h(τ)›, which is depicted as being subordinated to a standard fluctuation-dissipation process with friction y. The authors argue that the main properties of Kardar-Parisi-Zhang theory, in one dimension, are derived by identifying the distribution of return times to y(0)=0, which is a truncated inverse power law, with the distribution of subordination times. The agreement of the theoretical prediction with the numerical treatment of the (1+1)-dimensional model of ballistic deposition is remarkably good, in spite of the finite-size effects affecting this model. American Physical Society 2004-07-30 Article 4 p. Text doi: 10.1103/PhysRevE.70.010101 http://digital.library.unt.edu/ark:/67531/metadc67637/ ark: ark:/67531/metadc67637 Physical Review E, 2004, College Park: American Physical Society English Public

info:ark/67531/metadc67630 2012-05-10T15:55:06Z partner:UNTCAS collection:UNTSW access_rights:public

Scaling Breakdown: A Signature of Aging Allegrini, Paolo Bellazzini, Jacopo Bramanti, G. Ignaccolo, Massimiliano Grigolini, Paolo Yang, J. Lévy walks bilinear scaling In this article, the authors prove that the Lévy walk is characterized by bilinear scaling. This effect mirrors the existence of a form of aging that does not require the adoption of nonstationary conditions. American Physical Society 2002-07-12 Article 4 p. Text doi: 10.1103/PhysRevE.66.015101 http://digital.library.unt.edu/ark:/67531/metadc67630/ ark: ark:/67531/metadc67630 Physical Review E, 2002, New York: American Physical Society English Public

info:ark/67531/metadc67634 2012-05-10T16:31:01Z partner:UNTCAS collection:UNTSW access_rights:public

Vortex Dynamics in Evolutive Flows: A Weakly Chaotic Phenomenon Bellazzini, Jacopo Menconi, Giulia Ignaccolo, Massimiliano Buresti, Guido Grigolini, Paolo vortex dynamics entropy diffusion In this article, the authors make use of a wavelet method to extract, from experimental velocity signals obtained in an evolutive flow, the dominating velocity components generated by vortex dynamics. The authors characterize the resulting time series complexity by means of a joint use of data compression and of an entropy diffusion method. The authors assess that the time series emerging from the wavelet analysis of the vortex dynamics is a weakly chaotic process with a vanishing Kolmogorov-Sinai entropy and a power-law growth of the information content. To reproduce the Fourier spectrum of the experimental signal, the authors adopt a harmonic dependence on time with a fluctuating frequency, ruled by an inverse power-law distribution of random events. The complexity of these fluctuations is determined by studying the corresponding artificial sequences. The authors reproduce satisfactorily both spectral and complex properties of the experimental signal by locating the complexity of the fluctuating process at the border between the stationary and the nonstationary states. American Physical Society 2003 Article 10 p. Text doi: 10.1103/PhysRevE.68.026126 http://digital.library.unt.edu/ark:/67531/metadc67634/ ark: ark:/67531/metadc67634 Physical Review E, 2003, College Park: American Physical Society English Public

info:ark/67531/metadc67639 2012-05-10T16:28:16Z partner:UNTCAS collection:UNTSW access_rights:public

Power-Law Time Distribution of Large Earthquakes Mega, Mirko S. Allegrini, Paolo Grigolini, Paolo Latora, Vito Palatella, Luigi Rapisarda, Andrea Vinciguerra, Sergio earthquakes time distributions In this article, the authors study the statistical properties of time distribution of seismicity in California by means of a new method of analysis, the diffusion entropy. The authors find that the distribution of time intervals between a large earthquake (the main shock of a given seismic sequence) and the next one does not obey Poisson statistics, as assumed by the current models. The authors prove that this distribution is an inverse power law with an exponent μ = 2.06 ± 0.01. The authors propose the long-range model, reproducing the main properties of the diffusion entropy and describing the seismic triggering mechanisms induced by large earthquakes. American Physical Society 2003-05 Article 4 p. Text doi: 10.1103/PhysRevLett.90.188501 http://digital.library.unt.edu/ark:/67531/metadc67639/ ark: ark:/67531/metadc67639 Physical Review Letters, 2003, College Park: American Physical Society English Public

info:ark/67531/metadc67636 2012-05-10T15:56:00Z partner:UNTCAS collection:UNTSW access_rights:public

Solar Turbulence in Earth's Global and Regional Temperature Anomalies Scafetta, Nicola Grigolini, Paolo Imholt, Timothy Roberts, Jim West, Bruce J. solar earth temperatures This article presents a study of the influence of solar activity on the earth's temperature. In particular, the authors focus on the repercussion of the fluctuations of the solar irradiance on the temperature of the Northern and Southern hemispheres as well as on land and ocean regions. While solar irradiance data are not directly analyzed, the authors make use of a published solar irradiance reconstruction for long-time-scale fluctuations, and for short-time-scale fluctuations the authors hypothesize that solar irradiance and solar flare intermittency are coupled in such a way that the solar flare frequency fluctuations are stochastically equivalent to those of the solar irradiance. The analysis is based upon wavelet multiresolution techniques and scaling analysis methods for processing time series. The limitations of the correlation analysis applied to the short-time-scale fluctuations are discussed. The scaling analysis uses both the standard deviation and the entropy of the diffusion generated by the temperature signals. The joint use of these two scaling methods yields evidence of a Levy component in the temporal persistence of the temperature fluctuations within the temporal range from a few weeks to a few years. This apparent Levy persistence of the temperature fluctuations is found, by using an appropriate model, to be equivalent to the Levy scaling of the solar flare intermittency. The mean monthly temperature data sets cover the period from 1856 to 2002. American Physical Society 2004-02-26 Article 13 p. Text doi: 10.1103/PhysRevE.69.026303 http://digital.library.unt.edu/ark:/67531/metadc67636/ ark: ark:/67531/metadc67636 Physical Review E, 2004, College Park: American Physical Society English Public

info:ark/67531/metadc67640 2012-05-10T15:53:48Z partner:UNTCAS collection:UNTSW access_rights:public

Mega et al. Reply Reply to Comment [physics/0307134] by A. Helmstetter and D. Sornette Mega, Mirko S. Allegrini, Paolo Grigolini, Paolo Latora, Vito Palatella, Luigi Rapisarda, Andrea Vinciguerra, Sergio diffusion entropy non-Poisson anomalous diffusion This article is a reply to a comment by A. Helmstetter and D. Sornette about the article 'Power-Law Time Distribution of Large Earthquakes' from 2003. American Physical Society 2004-03-26 Article 1 p. Text doi: 10.1103/PhysRevLett.92.129802 http://digital.library.unt.edu/ark:/67531/metadc67640/ ark: ark:/67531/metadc67640 Physical Review Letters, 2004, College Park: American Physical Society English Public

info:ark/67531/metadc67627 2012-05-10T16:29:17Z partner:UNTCAS collection:UNTSW access_rights:public

Quantum Entanglement and Entropy Giraldi, Filippo Grigolini, Paolo quantum properties entropies This article discusses quantum entanglement and entropy. Entanglement is the fundamental quantum property behind the now popular field of quantum transport of information. This quantum property is incompatible with the separation of a single system into two uncorrelated subsystems. Consequently, it does not require the use of an additive form of entropy. The authors discuss the problem of the choice of the most convenient entropy indicator, focusing their attention on a system of two qubits, and on a special set, denoted by ℑ. This set contains both the maximally and partially entangled states that are described by density matrices diagonal in the Bell basis set. The authors select this set for the main purpose of making their work of analysis more straightforward. As a matter of fact, the authors find that in general the conventional von Neumann entropy is not a monotonic function of the entanglement strength. This means that the von Neumann entropy is not a reliable indicator of the departure from the condition of maximum entanglement. The authors study the behavior of a form of nonadditive entropy, made popular by the 1988 work by Tsallis [J. Stat. Phys. 52, 479 (1988)]. The authors show that in the set ℑ, implying the key condition of nonvanishing entanglement, this nonadditive entropy indicator turns out to be a strictly monotonic function of the strength of the entanglement, if entropy indexes q larger than a critical value Q are adopted. The authors argue that this might be a consequence of the nonadditive nature of the Tsallis entropy, implying that the world is quantum and that uncorrelated subsystems do not exist. American Physical Society 2001-08-20 Article 10 p. Text doi: 10.1103/PhysRevA.64.032310 http://digital.library.unt.edu/ark:/67531/metadc67627/ ark: ark:/67531/metadc67627 Physical Review A, 2001, College Park: American Physical Society English Public

info:ark/67531/metadc67628 2012-05-10T15:54:24Z partner:UNTCAS collection:UNTSW access_rights:public

Memory Beyond Memory in Heart Beating, a Sign of a Healthy Physiological Condition Allegrini, Paolo Grigolini, Paolo Hamilton, P. Palatella, Luigi Raffaelli, G. heart beats memories In this article, the authors describe two types of memory and illustrate each using artificial and actual heartbeat data sets. The first type of memory, yielding anomalous diffusion, implies the inverse power-law nature of the waiting time distribution and the second the correlation among distinct times, and consequently also the occurrence of many pseudoevents, namely, not genuinely random events. Using the method of diffusion entropy analysis, the authors establish the scaling that would be determined by the real events alone. The authors prove that the heart beating of healthy patients reveals the existence of many more pseudoevents than in the patients with congestive heart failure. American Physical Society 2002-04-11 Article 5 p. Text doi: 10.1103/PhysRevE.65.041926 http://digital.library.unt.edu/ark:/67531/metadc67628/ ark: ark:/67531/metadc67628 Physical Review E, 2002, College Park: American Physical Society English Public

info:ark/67531/metadc67614 2013-03-28T16:49:56Z partner:UNTCAS collection:UNTSW access_rights:public

Do I Look Illegal? Undocumented Latino/a Students and the Challenges of Life in the Shadows UNT Speaks Out Nuñez-Janes, Mariela Chapa, Shaun immigration discrimination This presentation is part of the faculty lecture series UNT Speaks Out on Unauthorized Immigration. This presentation discusses illegal immigration and the challenges for undocumented Latino/a students. University of North Texas. Libraries 2011-04-13 Presentation 24 p. Image http://digital.library.unt.edu/ark:/67531/metadc67614/ ark: ark:/67531/metadc67614 UNT Speaks Out on Unauthorized Immigration, 2011, Denton, Texas, United States English Unauthorized Immigration, ark:/67531/metadc33117 Unauthorized Immigration, ark:/67531/metadc84158 Public

info:ark/67531/metadc67635 2013-04-16T13:00:46Z partner:UNTCAS collection:UNTSW access_rights:public

Generalized Master Equation Via Aging Continuous-Time Random Walks Allegrini, Paolo Aquino, Gerardo Grigolini, Paolo Palatella, Luigi Rosa, Angelo continuous-time random walks CTRW generalized master equations GME This article discusses generalized master equation via aging continuous-time random walks. Abstract: We discuss the problem of the equivalence between continuous-time random walk (CTRW) and generalized master equation (GME). The walker, making instantaneous jumps from one site of the lattice to another, resides in each site for extended times. The sojourn times have a distribution density ψ(t) that is assumed to be an inverse power law with the power index μ. We assume that the Onsager principle is fulfilled, and we use this assumption to establish a complete equivalence between GME and the Montroll-Weiss CTRW.We prove that this equivalence is confined to the case where ψ(t) is an exponential. We argue that is so because the Montroll-Weiss CTRW, as recently proved by Barkai [E. Barkai, Phys. Rev. Lett. 90, 104101 (2003)], is nonstationary, thereby implying aging, while the Onsager principle is valid only in the case of fully aged systems. The case of a Poisson distribution of sojourn times is the only one with no aging associated to it, and consequently with no need to establish special initial conditions to fulfill the Onsager principle. We consider the case of a dichotomous fluctuation, and we prove that the Onsager principle is fulfilled for any form of regression to equilibrium provided that the stationary condition holds true. We set the stationary condition on both the CTRW and the GME, thereby creating a condition of total equivalence, regardless of the nature of the waiting-time distribution. As a consequence of this procedure the authors create a GME that is a bona fide master equation, in spite of being non-Markov. We note that the memory kernel of the GME affords information on the interaction between system of interest and its bath. The Poisson case yields a bath with infinitely fast fluctuations. We argue that departing from the Poisson form has the effect of creating a condition of infinite memory and that these results might be useful to shed light on the problem of how to unravel non-Markov quantum master equations. American Physical Society 2003 Article 11 p. Text doi: 10.1103/PhysRevE.68.056123 http://digital.library.unt.edu/ark:/67531/metadc67635/ ark: ark:/67531/metadc67635 Physical Review E, 2003, College Park: American Physical Society English Public

info:ark/67531/metadc67631 2013-05-15T17:20:30Z partner:UNTCAS collection:UNTSW access_rights:public

Lévy Scaling: The Diffusion Entropy Analysis Applied to DNA Sequences Scafetta, Nicola Latora, Vito Grigolini, Paolo diffusion entropy analyses Lévy scaling DNA sequences This article discusses Lévy scaling and the diffusion entropy analysis applied to DNA sequences. Abstract: We address the problem of the statistical analysis of a time series generated by complex dynamics with the diffusion entropy analysis (DEA) [N. Scafetta, P. Hamilton, and P. Grigolini, Fractals 9, 193 (2001)]. This method is based on the evaluation of the Shannon entropy of the diffusion process generated by the time series imagined as a physical source of fluctuations, rather than on the measurement of the variance of this diffusion process, as done with the traditional methods. We compare the DEA to the traditional methods of scaling detection and prove that the DEA is the only method that always yields the correct scaling value, if the scaling condition applies. Furthermore, DEA detects the real scaling of a time series without requiring any form of detrending. We show that the joint use of DEA and variance method allows to assess whether a time series is characterized by Lévy or Gauss statistics. We apply the DEA to the study of DNA sequences and prove that their large-time scales are characterized by Lévy statistics, regardless of whether they are coding or noncoding sequences. We show that the DEA is a reliable technique and, at the same time, we use it to confirm the validity of the dynamic approach to the DNA sequences, proposed in earlier work. American Physical Society 2002-09-20 Article 15 p. Text doi: 10.1103/PhysRevE.66031906 http://digital.library.unt.edu/ark:/67531/metadc67631/ ark: ark:/67531/metadc67631 Physical Review E, 2002, College Park: American Physical Society English Public

info:ark/67531/metadc67626 2013-05-20T16:50:46Z partner:UNTCAS collection:UNTSW access_rights:public

Linear Response to Perturbation of Nonexponential Renewal Processes Barbi, Francesco Bologna, Mauro Grigolini, Paolo linear responses nonexponential renewal processes two-state stochastic processes This article discusses the linear response to perturbation of nonexponential renewal processes. Abstract: We study the linear response of a two-state stochastic process, obeying the renewal condition, by means of a stochastic rate equation equivalent to a master equation with infinite memory. We show that the condition of perennial aging makes the response to coherent perturbation vanish in the long-time limit. American Physical Society 2005-11-23 Article 4 p. Text doi: 10.1103/PhysRevLett.95.220601 http://digital.library.unt.edu/ark:/67531/metadc67626/ ark: ark:/67531/metadc67626 Physical Review Letters, 2005, College Park: American Physical Society English Public

info:ark/67531/metadc67633 2013-05-21T17:18:40Z partner:UNTCAS collection:UNTSW access_rights:public

Long- and Short-Time Analysis of Heartbeat Sequences: Correlation with Mortality Risk in Congestive Heart Failure Patients Allegrini, Paolo Balocchi, Rita Chillemi, Santi Grigolini, Paolo Hamilton, P. Maestri, Roberto Palatella, Luigi Raffaelli, G. heartbeats congestive heart failure This paper discusses long- and short-time analysis of heartbeat sequences and the correlation with mortality risk in congestive heart failure patients. Abstract: We analyze RR heartbeat sequences with a dynamic model that satisfactorily reproduces both the long- and the short-time statistical properties of heart beating. These properties are expressed quantitatively by means of two significant parameters, the scaling δ concerning the asymptotic effects of long-range correlation, and the quantity 1 - π establishing the amount of uncorrelated fluctuations. We find a correlation between the position in the phase space (δ,π) of patients with congestive heart failure and their mortality risk. American Physical Society 2003 Article 4 p. Text doi: 10.1103/PhysRevE.67.062901 http://digital.library.unt.edu/ark:/67531/metadc67633/ ark: ark:/67531/metadc67633 Physical Review E, 2003, College Park: American Physical Society English Public

info:ark/67531/metadc71812 2013-03-15T13:28:31Z partner:UNTCAS collection:UNTSW access_rights:public

Calculations of the Relative Energies of the 2B1g and 2A2u States of Cyclobutanetetraone Radical Cation and Radical Anion Provide Further Evidence of a 3B2u Ground State for the Neutral Molecule: A Proposed Experimental Test of the Prediction of a Triplet Ground State for (CO)4 Zhou, Xin Hrovat, David A. Borden, Weston T., 1943- relative energies triplet ground states radical anions This article discusses ground states. Abstract: B3LYP, CCSD(T), and CASPT2 calculations with the 6-311+G(2df) basis set have been performed on the radical anion and radical cation of cyclobutanetetraone (1). The very similar energies computed for the 2B1g and 2A2u states of both 1·+ and 1·- indicate that the singly occupied b1g and a2u MOs in these two states of the radical cation and anion have nearly the same energies, thus supporting the previously made prediction that neutral 1 has a 3B2u ground state. Reaction of squaric acid with O.(-), followed by negative ion photoelectron spectroscopy (NIPES) on the 1.(-) thus formed, is proposed as an experimental test of the startling prediction that tetraketone (1), a molecule that would be expected to be a closed-shell singlet, actually has a triplet ground state. American Chemical Society 2010 Article 5 p. Text doi: 10.1021/jp905462b http://digital.library.unt.edu/ark:/67531/metadc71812/ ark: ark:/67531/metadc71812 Journal of Physical Chemistry A, 2010, Washington DC: American Chemical Society, pp.1304-1308 English Public

info:ark/67531/metadc71814 2013-03-15T13:31:45Z partner:UNTCAS collection:UNTSW access_rights:public

Calculations Predict That Carbon Tunneling Allows the Degenerate Cope Rearrangement of Semibullvalene to Occur Rapidly at Cryogenic Temperatures Zhang, Xue Hrovat, David A. Borden, Weston T., 1943- tunneling chemical reactions cryogenic temperatures This article discusses carbon tunneling. Abstract: Calculations on the role of tunneling in the degenerate Cope rearrangements of semibullvalene (1) and barbaralane (3) predict that, at temperatures below 40 K, tunneling from the lowest vibrational level should make the temperature-independent rate constants k = 1.43 x 10(-3) s(-1) and k = 7.28 x 10(-9) s(-1), respectively. An experiment, using semibullvalene-2(4)-d1, is proposed to test the prediction of rapid tunneling by 1 at cryogenic temperatures. American Chemical Society 2010-05-27 Article 4 p. Text doi: 10.1021/ol100879t http://digital.library.unt.edu/ark:/67531/metadc71814/ ark: ark:/67531/metadc71814 Organic Letters, 2010, Washington DC: American Chemical Society, pp. 2798-2801 English Public

info:ark/67531/metadc71808 2013-03-15T13:30:47Z partner:UNTCAS collection:UNTSW access_rights:public

Calculations Predict a Large Inverse H/D Kinetic Isotope Effect on the Rate of Tunneling in the Ring Opening of Cyclopropylcarbinyl Radical Zhang, Xue Datta, Ayan Hrovat, David A. Borden, Weston T., 1943- kinetic isotope effects cyclopropylcarbinyl radicals This article discusses calculations that predict a large inverse H/D kinetic isotope effect. Abstract: Tunneling rates are expected to decrease exponentially with the square root of the effective tunneling mass. Therefore, on substitution of a heavier for a lighter isotope, the observation of a large kinetic isotope effect (KIE), involving a substantial decrease in rate constant, is a commonly used diagnostic for a large contribution from quantum mechanical tunneling to a reaction. However, in this communication, the authors report the results of calculations that make the opposite prediction about some of the KIEs on the ring opening of cyclopropylcarbinyl radical (1) to 3-butene-1-y1 radical (2) by tunneling at cryogenic temperatures. Substitution of a heavier for a lighter isotope at the radical center (C1) of 1 is calculated to accelerate the rate of tunneling, giving KIEs at this carbon that are inverse. Of particular note is the authors' prediction that substitution of deuterium for both hydrogens at C1 will lead to a nearly 3-fold increase in the rate of reaction at temperatures so low that ring opening proceeds exclusively by tunneling from the lowest vibrational level. American Chemical Society 2009-10-15 Article 2 p. Text doi: 10.1021/ja907406q http://digital.library.unt.edu/ark:/67531/metadc71808/ ark: ark:/67531/metadc71808 Journal of the American Chemical Society, 2009, Washington DC: American Chemical Society, pp. 16002-16003 English Public

info:ark/67531/metadc71813 2013-03-21T13:38:07Z partner:UNTCAS collection:UNTSW access_rights:public

Cyclooctatetraenes Tetrakis-Annelated with α-Dithio- or α-Diselenocarbonyl Groups: Diradicals Predicted To Have Ground States with 10 π Electrons in the Eight-Membered Ring and Two-Center, Three-Electron, σ Bonds between Two Pairs of Chalcogen Atoms Zhou, Xin Hrovat, David A. Borden, Weston T., 1943- cyclooctatetraenes electrons bonds This article discusses cyclooctatetraenes. Abstract: (U)B3LYP calculations with the 6-31+G(d) and 6-311+G(2df) basis sets have been carried out on cyclooctatetraenes 6 and 7, in which the COT ring is tetrakis-annelated with α-dithio- or α-diselenocarbonyl groups. Transferring two electrons from the high-lying b1g and eu σ MOs in 6 and 7 into the unoccupied, nonbonding, COT π orbital is computed to be energetically favorable. The lowest D4h electronic state is calculated to be 3Eu, which formally contains 10 π electrons in the eight-membered ring and has two unpaired electrons in σ MOs. The 3Eu state undergoes a first-order Jahn-Teller distortion to form 6d and 7d, in which the pair of one-electron holes in the σ MOs is stabilized by the formation of two, two-center, three-electron bonds between pairs of chalcogen atoms that are diagonally across the eight-membered ring from each other. The corresponding open-shell singlets are computed to be about 1 kcal/mol lower in energy than the Jahn-Teller distorted triplets. Molecules 6i and 7i, in which the C-C bond in one four-membered ring is cleaved, are computed to be lower in energy than 6d and 7d. However, a substantial barrier is predicted to separate each of the two pairs of isomers so that 6d and 7d should, at least in principle, be isolable. American Chemical Society 2010-02-12 Article 8 p. Text doi: 10.1021/jp911705y http://digital.library.unt.edu/ark:/67531/metadc71813/ ark: ark:/67531/metadc71813 Journal of Physical Chemistry A, 2010, Washington DC: American Chemical Society, pp. 3683-3690 English Public

info:ark/67531/metadc71807 2013-03-21T13:24:34Z partner:UNTCAS collection:UNTSW access_rights:public

Current Applications of Computational Chemistry in JACS - Molecules, Mechanisms, and Materials Borden, Weston T., 1943- computational chemistry American Chemical Society molecules mechanisms materials This article discusses current applications of computational chemistry. This virtual issue of JACS Select is devoted to some of the computation chemistry that has recently been published in the Journal of the American Chemical Society (JACS). The 25 articles and Communications that appear in this issue of JACS Select were chosen on the basis of the enthusiasm of the referees for these manuscripts when they were reviewed, as well as on the number of times each of these articles has been accessed online since its publication. Diversity of subject matter was not a criterion used in selecting these 25 articles from the ca. 50 well-reviewed, frequently accessed articles that were initially considered. However, inspection of the list of the subjects covered - from amyloid fibril polymorphism to nucleation of amorphous calcium carbonate; from the structure of solid Li(NH3)4 to the role that solvation plays in the Thorpe-Ingold effect; and to the nonstatistical, gas-phase dynamics of [1,5] hydrogen shifts in chemically activated cyclopentadiene - reveals the diverse nature of some of the best papers in computational chemistry that have been published recently in JACS. American Chemical Society 2011-09-21 Article 3 p. Text doi: 10.1021/ja206656w http://digital.library.unt.edu/ark:/67531/metadc71807/ ark: ark:/67531/metadc71807 Journal of the American Chemical Society, 2011, Washington DC: American Chemical Society, pp. 14841-14843 English Public

info:ark/67531/metadc71782 2013-03-21T13:26:25Z partner:UNTCAS collection:UNTSW access_rights:public

Current Behavioral and Psychosocial Interventions for HIV/AIDS UNT Speaks Out Vosvick, Mark A. HIV AIDS therapies interventions antiretroviral HAART medications This presentation is part of the faculty lecture series UNT Speaks Out on AIDS. This presentation discusses recent directions in psychosocial research on HIV/AIDS in the United States. University of North Texas. Libraries 2011-12-01 Presentation 12 p. Image http://digital.library.unt.edu/ark:/67531/metadc71782/ ark: ark:/67531/metadc71782 UNT Speaks Out on AIDS, 2011, Denton, Texas, United States English World AIDS Day: UNT Speaks Out, ark:/67531/metadc71780 Public

info:ark/67531/metadc71790 2013-03-13T14:21:11Z partner:UNTCAS collection:UNTSW access_rights:public

Are Net Discount Ratios Stationary?: The Implications For Present Value Calculations Haslag, Joseph H. Nieswiadomy, Michael L. Slottje, Daniel J. net discount ratios wages present value calculations Abstract: This article analyzes the relationship between real interest rates and real growth rates in wages. The stationary of these time series has been discussed in the literature. However, since the net discount ratio, (1 + gτ)/(1 + rτ), is a nonlinear transformation, it is not necessarily stationary even if the interest rate and growth rate in wages series are each stationary. On the other hand, the net discount ratio may be stationary even if the interest rate and growth rate series are both non-stationary. The significant finding of this article is that this ratio is stationary. This conclusion appears robust since it holds for at least four different Treasury securities analyzed: three month, six month, one year, and three year. Therefore, a real net discount ratio, (1 + gτ)/(1 + rτ), can be used with confidence in constructing present value forecasts of expected earnings. American Risk and Insurance Association 1991-09 Article 8 p. Text http://digital.library.unt.edu/ark:/67531/metadc71790/ ark: ark:/67531/metadc71790 Journal of Risk and Insurance, 1991, Malvern: American Risk and Insurance Association English Public

info:ark/67531/metadc71789 2013-03-18T13:25:31Z partner:UNTCAS collection:UNTSW access_rights:public

Calculating Changes in Worklife Expectancies and Lost Earnings in Personal Injury Cases Nieswiadomy, Michael L. Silberberg, Eugene worklife expectancies personal injury cases This article discusses calculating changes in worklife expectancies and lost earnings in personal injury cases. Abstract: This paper utilizes the Bureau of Labor Statistics (BLS) new worklife tables' information on workforce participation probabilities to estimate the effect of an injury on a worker's life expectancy, worklife expectancy and discounted expected income. After a medical opinion has been obtained concerning the effect of an injury on a worker's probabilities of living and remaining active, the BLS's probability figures can be adjusted and incorporated into a Markov process to estimate the impact of the injury. It is shown that Alter and Becker's technique can be adapted to estimate the present value of the lost expected income. American Risk and Insurance Association 1988-09 Article 7 p. Text http://digital.library.unt.edu/ark:/67531/metadc71789/ ark: ark:/67531/metadc71789 Journal of Risk and Insurance, 1988, Malvern: American Risk and Insurance Association English Public

info:ark/67531/metadc71791 2013-03-13T14:18:22Z partner:UNTCAS collection:UNTSW access_rights:public

Are Net Discount Rates Stationary?: Some Further Evidence Haslag, Joseph H. Nieswiadomy, Michael L. Slottje, Daniel J. net discount rates analyses This article discusses net discount rates. Abstract: Gamber and Sorensen provide evidence suggesting that the net discount ratio experienced a level shift in the mean between 1977 and 1981. If such a shift occurred, the nonlinearity in the data shows up as a failure to reject the null hypothesis that a unit root is present; that is, the series is I(1). In this reply, evidence is presented - the Phillips-Perron test and a univariate version of the Stock-Watson q-test - suggesting that the net discount ratio is stationary. Hence, the mean is constant. In addition, if one extends the analysis to include the 1989 through 1993 period, the net discount ratio appears to be reverting. American Risk and Insurance Association 1994-09 Article 6 p. Text http://digital.library.unt.edu/ark:/67531/metadc71791/ ark: ark:/67531/metadc71791 Journal of Risk and Insurance, 1994, Malvern: American Risk and Insurance Association English Public

info:ark/67531/metadc71793 2013-03-19T16:25:34Z partner:UNTCAS collection:UNTSW access_rights:public

Cooperative Effects in the Annelation of Benzene by Multiple Etheno Groups Bao, Xiaoguang Hrovat, David A. Borden, Weston T., 1943- cooperative effects bond alternation orbital mixing mathematical models carbocycles density functional calculations This article discusses cooperative effects in the annelation of benzene by multiple etheno groups. Abstract: The results of B3LYP/6-31G(d) calculations show that there is a strong cooperative effect on the energies that result from annelating benzene with 1, 2, and 3 etheno groups, to form 3, 4, and 5 respectively. The etheno annelation energies have been decomposed into two major contributors - etheno annelation, with all the bonds in the six-membered ring constrained to have the same C-C bond length as in D6h benzene, and optimization of the C-C bond lengths in the annelated benzene ring. The energies computed for each of these two steps show that the etheno groups behave cooperatively in both of them. The origin of the cooperativity, calculated for each step, is described and discussed. Institute of Organic Chemistry and Biochemistry 2011-04-20 Article 22 p. Text doi: 10.1135/cccc2011037 http://digital.library.unt.edu/ark:/67531/metadc71793/ ark: ark:/67531/metadc71793 Collection of Czechoslovak Chemical Communications, 2011, Prague: Institute of Organic Chemistry and Biochemistry, pp. 481-501 English Public

info:ark/67531/metadc71792 2012-12-07T14:52:28Z partner:UNTCAS collection:UNTSW access_rights:public

Urban Water Demand Estimates Under Increasing Block Rates Nieswiadomy, Michael L. Molina, David J. residential water consumption block rate schedules This article discusses urban water demand estimates under increasing block rates. A residential water demand equation is estimated using the only data set on water consumption that contains time series (monthly) observations on individual customers facing an increasing block rate schedule. Because the price of water both determines, and is determined by, usage, ordinary least squares estimation will yield biased estimates. Thus, two-stage least squares and instrumental variables techniques are used. The estimated coefficients on lawn size, weather, house size, and income have the expected signs and are statistically significant. However, there is not any significant response to changes in water price, perhaps due to the relatively low cost of water. John Wiley & Sons 1988 Article 13 p. Text http://digital.library.unt.edu/ark:/67531/metadc71792/ ark: ark:/67531/metadc71792 Growth and Change, 1988, Hoboken: John Wiley & Sons English Public

info:ark/67531/metadc71809 2012-12-07T15:57:31Z partner:UNTCAS collection:UNTSW access_rights:public

With a Little Help from My Friends: Forty Years of Fruitful Chemical Collaborations Borden, Weston Thatcher collaborative research organic chemistry theoretical chemistry This article discusses collaborations. Over the past 40 years, much of the author's research, both computational and experimental, has involved collaborations. This Perspective describes some of the author's collaborative research in eight different areas of organic and theoretical chemistry: (1) hydrocarbons containing unsaturatively, 1,3-bridged cyclobutane rings, (2) the use of orbital topology for predicting the ground states of diradicals, (3) violations of Hund's rule, (4) the chemistry of phenylnitrenes, (5) tunneling by carbon in organic reactions, (6) the Cope rearrangement and the effect of substituents on it, (7) pyramidalized alkenes, dehydrocubanes, cubyl cation, and octanitrocubane, and (8) the effects of geminal fluorine substitution at C-2 of 1,3-diradicals. Highlighted in this Perspective are the synergism between calculations and experiments in the author's research and the many different roles that serendipity has played in the collaborations that are described herein. American Chemical Society 2011-03-31 Article 22 p. Text doi: 10.1021/jo200213x http://digital.library.unt.edu/ark:/67531/metadc71809/ ark: ark:/67531/metadc71809 The Journal of Organic Chemistry, 2011, Washington DC: American Chemical Society, pp. 2943-2964 English Public

info:ark/67531/metadc71802 2013-04-01T17:21:41Z partner:UNTCAS collection:UNTSW access_rights:public

Effects of Geminal Methyl Groups on the Tunnelling Rates in the Ring Opening of Cyclopropylcarbinyl Radical at Cryogenic Temperature Zhang, Xue Hrovat, David A. Datta, Ayan Borden, Weston T., 1943- tunnelling geminal methyl groups cyclopropylcarbinyl radicals This article discusses the effects of geminal methyl groups on the tunnelling rates in the ring opening of cyclopropylcarbinyl radical at cryogenic temperature. Abstract: CVT + SCT calculations on the rate of tunnelling at 20 K in the ring opening of cyclopropylcarbinyl radical, substituted with geminal methyl groups at a ring carbon (1b), have been performed. The calculations predict that, contrary to expectations based on the effect of mass on the rate of tunnelling, the geminal methyl substituents in 1b should make the rate of ring opening to 1,1-dimethyl-3-butenyl radical (2b) 10(4) times faster than the rate of ring opening of unsubstituted cyclopropylcarbinyl radical (1a) to 3-butenyl radical (2a) and almost 10(6) times faster than the rate of ring opening of 1b to 2,2-dimethyl1-3-butenyl radical (2c). The reasons for these unexpected findings are discussed. Royal Society of Chemistry (Great Britain) 2011 Article 4 p. Text doi: 10.1039/C0OB01238F http://digital.library.unt.edu/ark:/67531/metadc71802/ ark: ark:/67531/metadc71802 Organic and Biomolecular Chemistry, 2011, Cambridge: Royal Society of Chemistry (Great Britain), pp.3142-3145 English Public

info:ark/67531/metadc71806 2012-02-13T15:13:42Z partner:UNTCAS collection:UNTSW access_rights:public

Through-Bond Interactions in the Diradical Intermediates Formed in the Rearrangements of Bicyclo[n.m.0]alkatetraenes Lovitt, Charity Flener Dong, Hao Hrovat, David A. Gleiter, Rolf Borden, Weston Thatcher diradical intermediates through-bond interactions This article discusses through-bond interactions. The intermediates and transition structures in the degenerate thermal rearrangements of bicyclo[4.4.0]deca-2,4,7,9-tetraene (1c), bicyclo[5.5.0]dodeca-2,4,8,10-tetraene(11b), and bicyclo[5.4.0]undeca-2.4.8.10-tetraene (14) have been located by (U)B3LYP/6-31G(d) calculations. The singlet-triplet energy differences (∆Est) in the diradical intermediates (tricyclo[4.4.0.02,7]deca-3,8-dien-5,10-diyl (2c), tricyclo[5.5.0.05,11]dodeca-2,8-dien-4,10-diyl (12b), and tricyclo[5.4.0.05,11]undeca-2,8-dien-4,10-diyl(15)) have been computed, using both UB3LYP and (6/6)CASPT2 calculations. ∆Est in 2c, in which a four-membered ring is anti-bridged by two allylic radicals, is computed to be larger by a factor of 5 than ∆Est in 15, in which the anti-bridged ring is five-membered, and by a factor of 10 than that in 12b, in which the anti-bridged ring is six-membered. The reasons for the much larger interaction between two allylic radicals through the bonds of the four-membered ring in 2c than through the bonds of the five-membered ring in 15 or the six-membered ring in 12b are discussed, and the consequences of the large, through-bond stabilization of the singlet state of 2c are described. American Chemical Society 2010-09-24 Article 8 p. Text doi: 10.1021/ja106329t http://digital.library.unt.edu/ark:/67531/metadc71806/ ark: ark:/67531/metadc71806 Journal of the American Chemical Society, 2010, Washington DC: American Chemical Society, pp. 14617-14624 English

info:ark/67531/metadc71811 2012-03-21T17:09:21Z partner:UNTCAS collection:UNTSW access_rights:public

Photoelectron Spectroscopic Study of the Oxyallyl Diradical Ichino, Takatoshi Villano, Stephanie M. Gianola, Adam J. Goebbert, Daniel J. Velarde, Luis Sanov, Andrei Blanksby, Stephen J. Zhou, Xin Hrovat, David A. Borden, Weston Thatcher Lineberger, W. Carl photoelectrons oxyallyl radical anions This article discusses photoelectron spectroscopic study of the oxyallyl diradical. The photoelectron spectrum of the oxyallyl (OXA) radical anion has been measured. The radical anion has been generated in the reaction of the atomic oxygen radical anion (O߭߫) with acetone. Three low-lying electronic states of OXA have been observed in the spectrum. Electronic structure calculations have been performed for the triplet states (3B2 and 3B1) of OXA and the ground doublet state (2A2) of the radical anion using density functional theory (DFT). Spectral simulations have been carried out for the triplet states based on the results of the DFT calculations. The simulations identifies a vibrational progression of the CCC bending mode of the 3B2 state of OXA in the lower electron binding energy (eBE) portion of the spectrum. On top of the 3B2 feature, however, the experimental spectrum exhibits additional photo-electron peaks whose angular distribution is distinct from that for the vibronic peaks of the 3B2 state. Complete active space self-consistent field (CASSCF) method and second-order perturbation theory based on the CASSCF wave function (CASPT2) have been employed to study the lowest singlet state (1A1) of OXA. The simulation based on the results of these electronic structure calculations establishes that the overlapping peaks represent the vibrational ground level of the 1A1 state and its vibrational progression of the CO stretching mode. The 1A1 state is the lowest electronic state of OXA, and the electron affinity (EA) of OXA is 1.940 ± 0.010 eV. The 3B2 state is the first excited state with an electronic term energy of 55 ± 2 meV. The widths of the vibronic peaks of the X̃ 1A1 state are much broader than those of the ã 3B2 state, implying that the 1A1 state is indeed a transition state. The CASSCF and CASPT2 calculations suggest that the 1A1 state is at a potential maximum along the nuclear coordinate representing disrotatory motion of the two methylene groups, which leads to three-membered-ring formation, i.e., cyclopropanone. The simulation of b̃ 3B1 OXA reproduces the higher eBE portion of the spectrum very well. The term energy of the 3B1 state is 0.883 ± 0.012 eV. Photoelectron spectroscopic measurements have also been conducted for the other ion products of the O߭߫ reaction with acetone. The photoelectron imaging spectrum of the acetylcarbene (AC) radical anion exhibits a broad, structureless feature, which is assigned to the X̃ 3A′′ state of AC. The ground (2A′′) and first excited (2A′) states of the 1-methylvinoxy (1-MVO) radical have been observed in the photoelectron spectrum of the 1-MVO ion, and their vibronic structure has been analyzed. American Chemical Society 2011-02-16 Article 16 p. Text doi: 10.1021/jp111311k http://digital.library.unt.edu/ark:/67531/metadc71811/ ark: ark:/67531/metadc71811 Journal of Physical Chemistry A, 2011, Washington DC: American Chemical Society, pp. 1634-1649 English Public

info:ark/67531/metadc71810 2012-03-21T17:40:54Z partner:UNTCAS collection:UNTSW access_rights:public

Templated Growth of Hexagonal Nickel Carbide Nanocrystals on Vertically Aligned Carbon Nanotubes Hwang, Jun Y. Singh, Antariksh Chaudhari, Mrunalkumar Tiley, Jaimie Zhu, Yuntian Du, Jincheng Banerjee, Rajarshi nanocrystals hexagonal nickel carbide This article discusses hexagonal nickel carbide. Nanocrystals of hexagonal nickel carbide have been synthesized via physical vapor deposition of elemental nickel onto the surface of vertically aligned carbon nanotubes. Combining high-resolution transmission electron microscopy (HRTEM) with three-dimensional atom probe tomography (3DAP) confirmed that these nanocrystals have a hexagonal structure, are enriched in carbon, and have a composition of ~Ni-25 at. % C (Ni3C). This metastable hexagonal nickel carbide phase appears to be stabilized due to the growth of the nanocrystals on the surface of the nanotubes that act as a template and also as a source of carbon. The stability of this nickel carbide phase has also been investigated by density functional theory (DFT) calculations and compared to the experimental results. American Chemical Society 2010-05-18 Article 6 p. Text doi: 10.1021/jp102571g http://digital.library.unt.edu/ark:/67531/metadc71810/ ark: ark:/67531/metadc71810 Journal of Physical Chemistry C, 2010, Washington DC: American Chemical Society, pp. 10424-10429 English Public

info:ark/67531/metadc71815 2013-04-08T17:13:28Z partner:UNTCAS collection:UNTSW access_rights:public

Experimental and Computational Studies of the Isomerization Reactions of Bidentate Phosphine Ligands in Triosmium Clusters: Kinetics of the Rearrangements from Bridged to Chelated Isomers and X-ray Structures of the Clusters Os3 (CO)10 (dppbz), 1,1-Os3 (CO)10 (dppbzF4), HOs3 (CO)9 [μ -1,2-PhP (C6H4-ɳ1) C6H4PPh2], and HOs3 (CO)9- [μ-1,2-PhP (C6H4-ɳ 1) C6F4PPh2] Zhang, Xue Kandala, Srikanth Yang, Li Watson, William H. Wang, Xiaoping Hrovat, David A. Borden, Weston T., 1943- Richmond, Michael G. ligands triosmium clusters kinetics isomers This article discusses isomerization reactions of bidentate phosphine ligands in triosmium clusters. Abstract: The diphosphine ligand 1,2-bis(diphenylphosphino) benzene (dppbz) reacts with the activated cluster 1,2-Os3 (CO)10 (MeCN)2 (1) at room temperature to furnish a mixture of the triosmium clusters 1,2-Os3 (CO)10 (dppbz) (2) and 1,1-Os3 (CO)10 (dppbz) (3), along with a trace amount of the hydride cluster HOs3 (CO)9 [μ -1,2-PhP (C6H4-ɳ1) C6H4PPh2] (4). The dppbz-bridged cluster 2 forms as the kinetically controlled product and irreversibly transforms to the corresponding chelated isomer 3 at ambient temperature. The disposition of the dppbz ligand in 2 and 3 has been established by X-ray crystallography and 31P NMR spectroscopy, and the kinetics for the conversion 2 → 3 have been followed by UV-vis spectroscopy in toluene over the temperature range 318-343 K. The calculated activation parameters (ΔH‡ = 21.6(3)kcal/mol; ΔS‡ = -11(1)eu) and lack of CO inhibition support an intramolecular isomerization mechanism that involves the simultaneous migration of phosphine and CO groups about the cluster polyhedron. The reaction between 1 and the fluorinated diphosphine ligand 1,2-bis(diphenylphosphino) tetrafluorobenzene (dppbzF4) was examined under similar reaction conditions and was found to afford the chelated cluster 1,1-Os3 (CO)10 (dppbzF4) (6) as the sole observable product. The absence of the expected bridged isomer 1,2-Os3 (CO)10 (dppbzF4) (5) suggests that the dppbzF4 ligand destabilizes 5, thus accounting for the rapid isomerization of 5 to 6. Near-UV irradiation of clusters 3 and 6 leads to CO loss and ortho metalation of an ancillary aryl group. The resulting hydride clusters 4 and HOs3 (CO)9 [µ-1,2-PhP(C6H4-ɳ1) C6F4PPh2] (7) have been isolated and fully characterized by spectroscopic and X-ray diffraction analyses. Both 4 and 7 react with added CO under mild conditions to regenerate 3 and 6, respectively, in quantitative yield. The rearrangements of bridged to chelated diphosphine complexes in this genre of decacarbonyl clusters have been investigated by DFT calculations. The computational results support a concerted process, involving the scrambling of equatorial CO and phosphine groups via a classical merry-go-round exchange scheme. The barriers computed for this mechanism agree well with those that have been measured, and steric compression within the bridged diphosphine groups of the reactants has been calculated to reduce the barrier heights for the rearrangement. American Chemical Society 2011-02-22 Article Text doi: 10.1021/om100783f http://digital.library.unt.edu/ark:/67531/metadc71815/ ark: ark:/67531/metadc71815 Organometallics, 2011, Washington DC: American Chemical Society, pp. 1253-1268 English Public

info:ark/67531/metadc71805 2013-04-08T17:46:09Z partner:UNTCAS collection:UNTSW access_rights:public

Experimental Evidence for Heavy-Atom Tunneling in the Ring-Opening of Cyclopropylcarbinyl Radical from Intramolecular 12C/13C Kinetic Isotope Effects Gonzalez-James, Ollie M. Zhang, Xue Datta, Ayan Hrovat, David A. Singleton, Daniel A. Borden, Weston T., 1943- tunneling kinetic isotope effects chemical reactions This article discusses experimental evidence for heavy-atom tunneling. Abstract: The intramolecular 13C kinetic isotope effects for the ring-opening of cyclopropylcarbinyl radical were determined over a broad temperature range. The observed isotope effects are unprecedentedly large, ranging from 1.062 at 80 °C to 1.163 at -100 °C. Semiclassical calculations employing canonical variational transition-state theory drastically underpredict the observed isotope effects, but the predicted isotope effects including tunneling by a small-curvature tunneling model match well with experiment. These results and a curvature in the Arrhenius plot of the isotope effects support the recently predicted importance of heavy-atom tunneling in cyclopropylcarbinyl ring-opening. American Chemical Society 2010-08-19 Article 2 p. Text doi: 10.1021/ja1055593 http://digital.library.unt.edu/ark:/67531/metadc71805/ ark: ark:/67531/metadc71805 Journal of the American Chemical Society, 2010, Washington DC: American Chemical Society, pp. 2548-12549 English Public

info:ark/67531/metadc71804 2013-04-11T14:28:23Z partner:UNTCAS collection:UNTSW access_rights:public

First-Principles-Based Kinetic Monte Carlo Simulation of Nitric Oxide Reduction over Platinum Nanoparticles under Lean-Burn Conditions Mei, Donghai Du, Jincheng Neurock, Matthew kinetics nitric oxide platinum nanoparticles This article discusses first-principles-based kinetic Monte Carlo simulation of Nitric Oxide reduction. Abstract: The kinetics for NO reduction over supported platinum under lean condition were investigated by first-principles-based kinetic Monte Carlo simulation over three-dimensional Pt nanoparticles. Model platinum nanoparticles with diameters ranging from 2.3 to 4.6 nm were constructed using a truncated octahedral cluster consisting of a two (100) facets and eight (111) facets. First-principles density functional theory (DFT) calculations were used to calculate the intrinsic kinetic parameters including the binding energies for all of the surface intermediates as well as the activation barriers and reaction energies that comprise the reaction nanoparticle. Both intra- and inter-facet diffusion of adsorbates were included to model surface diffusion effects over the particle surface. The simulation results show that under lean conditions where there is excess oxygen, NO reduction to N2 occurs solely on the (100) facets. The oxidation of NO to NO2, while much more favored on the (111) facets, can occur on both (100) and (111) facets. Only small amounts of N2O form over the (100) facets. The simulated apparent activation energies for N2 and NO2 formation over the entire particle are 45 and 42 kJ/mol, respectively. The latter is in agreement with experimentally measured value of 39 kJ/mol [Mulla, S.S., et al., Catal. Lett. 2005, 100, 267]. The effects of particle size on the activities of NO reduction to N2 and NO oxidation to NO2 depend upon the ratios of exposed surface sites. For the three-dimensional model Pt nanoparticles examined here, the fractions of the (100) terrace sites are similar while the fraction of the (111) terrace sites increases with increasing particle size. As a result, the activity for NO reduction is somewhat insensitive to the particle size which symmetrically increases the numbers of (111) and (100) facets as the size increases. NO reduction, however, increases much more dramatically when the number of the (100) sites increases over the (111) sites. NO oxidation activity, on the other hand, appears to increase with increasing particle size regardless of the symmetry or shape of the particle as the reaction occurs predominantly over the (111) sites but can also take place on the (100) terrace sites. The structure insensitivity for NO oxidation is consistent with experimental results. American Chemical Society 2010 Article 10 p. Text doi: 10.1021/ie100999e http://digital.library.unt.edu/ark:/67531/metadc71804/ ark: ark:/67531/metadc71804 Industrial and Engineering Chemistry Research, 2010, Washington DC: American Chemical Society, pp. 10364-10373 English Public

info:ark/67531/metadc71783 2013-04-16T13:57:30Z partner:UNTCAS collection:UNTSW access_rights:public

Geographic Distribution of HIV/AIDS in Texas UNT Speaks Out Oppong, Joseph R. HIV AIDS epidemiology This presentation is part of the faculty lecture series UNT Speaks Out on HIV/AIDS. This presentation discusses the geographic distribution of HIV/AIDS in Texas and the associated factors. University of North Texas. Libraries 2011-12-01 Presentation 22 p. Image http://digital.library.unt.edu/ark:/67531/metadc71783/ ark: ark:/67531/metadc71783 UNT Speaks Out on AIDS, 2011, Denton, Texas, United States English World AIDS Day: UNT Speaks Out, ark:/67531/metadc71780 Public

info:ark/67531/metadc71788 2013-05-01T15:44:19Z partner:UNTCAS collection:UNTSW access_rights:public

Input Substitution in Irrigated Agriculture in the High Plains of Texas, 1970-80 Nieswiadomy, Michael L. elasticity of substitutions irrigation technologies pump costs Texas This article discusses input substitution in irrigated agriculture in the high plains of Texas. Abstract: The adaptability of irrigated agriculture in the High Plains region of Texas in the 1970-80 period is analyzed by estimating Allen partial elasticities of substitution for five key inputs (water, labor, center pivot, furrow, and wheel roll systems) used to produce two crops (cotton and grain sorghum). The results indicate that farmers have adapted to changes in a manner generally consistent with prior expectations concerning complementarity and substitutability among inputs. The output-constant price elasticity of water demand was statistically significant but relatively small (-.25). Western Agricultural Economics Association 1988-07 Article 8 p. Text http://digital.library.unt.edu/ark:/67531/metadc71788/ ark: ark:/67531/metadc71788 Western Journal of Agricultural Economics, 1988, Milwaukee: Western Agricultural Economics Association English Public

info:ark/67531/metadc75420 2013-03-20T16:41:39Z partner:UNTCAS collection:UNTSW access_rights:public

The correlation-consistent composite approach: Application to the G3/99 test set DeYonker, Nathan J. Grimes, Thomas V. Yockel, Scott Dinescu, Adriana Mintz, Benjamin Cundari, Thomas R., 1964- Wilson, Angela K. correlation-consistent composite approach ccCA ab initio composite techniques atomic energies molecular energies This article discusses the correlation-consistent composite approach. Abstract: The correlation-consistent composite approach (ccCA), an ab initio composite technique for computing atomic and molecular energies, recently has been shown to successfully reproduce experimental data for a number of systems. The ccCA is applied to the G3/99 test set, which includes 223 enthalpies of formation, 88 adiabatic ionization potentials, 58 adiabatic electron affinities, and 8 adiabatic proton affinities. Improvements on the original ccCA formalism include replacing the small basis set quadratic configuration interaction computation with a coupled cluster computation, employing a correction for scalar relativistic effects, utilizing the tight-d forms of the second-row correlation-consistent basis set extrapolation of MP2 energies, ccCA results in an almost zero mean deviation for the G3/99 set (with a best value of -0.10 kcal molˉ¹), and a 0.96 kcal molˉ¹ mean absolute deviation, which is equivalent to the accuracy of the G3X model chemistry. There are no optimized or empirical parameters included in the computation of ccCA energies. Except for a few systems to be discussed, ccCA performs as well as or better than Gn methods for most systems containing first-row atoms, while for systems containing second-row atoms, ccCA is an improvement over Gn model chemistries. American Institute of Physics 2006-09-13 Article 15 p. Text doi: 10.1063/1.2236116 http://digital.library.unt.edu/ark:/67531/metadc75420/ ark: ark:/67531/metadc75420 The Journal of Chemical Physics, 2006, College Park: American Institute of Physics English Public

info:ark/67531/metadc75417 2013-03-12T17:22:53Z partner:UNTCAS collection:UNTSW access_rights:public

Anomalous diffusion and ballistic peaks: A quantum perspective Stefancich, Marco Allegrini, Paolo Bonci, Luca Grigolini, Paolo West, Bruce J. ballistic peaks rotors quantum particles This article discusses anomalous diffusion and ballistic peaks. Abstract: The quantum kicked rotor and the classical kicked rotor are both shown to have truncated Lévy distributions in momentum space, when the classical phase space has accelerator modes embedded in a chaotic sea. The survival probability for classical particles at the interface of an accelerator mode and the chaotic sea has an inverse power-law structure, whereas that for quantum particles has a periodically modulated inverse power law, with the period of oscillation being dependent on Planck's constant. These logarithmic oscillations are a renormalization group property that disappears as ħ → 0 in agreement with the correspondence principle. American Physical Society 1998-06 Article 9 p. Text doi: 10.1103/PhysRevE.57.6625 http://digital.library.unt.edu/ark:/67531/metadc75417/ ark: ark:/67531/metadc75417 Physical Review E, 1998, College Park: American Physical Society, pp. 6625-6633 English Public

info:ark/67531/metadc75421 2013-03-19T16:55:23Z partner:UNTCAS collection:UNTSW access_rights:public

The correlation consistent composite approach (ccCA): An alternative to the Gaussian-n methods DeYonker, Nathan J. Cundari, Thomas R., 1964- Wilson, Angela K. composite methods correlation consistent composite approachs ccCA This article discusses the correlation consistent composite approach (ccCA). Abstract: An alternative to the Gaussian-n (G1, G2, and G3) composite methods of computing molecular energies is proposed and is named the "correlation consistent composite approach" (ccCA, ccCA-CBS-1, ccCA-CBS-2). This approach uses the correlation consistent polarized valence (cc-pVXZ) basis sets. The G2-1 test set of 48 enthalpies of formation (∆Hf), 38 adiabatic ionization potentials (IPs), 25 adiabatic electron affinities (EAs), and 8 adiabatic proton affinities (PAs) are computed using this approach, as well as the ∆Hf values of 30 more systems. Equilibrium molecular geometries and vibrational frequencies are obtained using B3LYP density functional theory. When applying the ccCA-CBS method with the cc-pVXZ series of basis sets augmented with diffuse functions, mean absolute deviations within the G2-1 test set compared to experiment are 1.33 kcal molˉ¹ for ∆Hf, 0.81 kcal molˉ¹ for IPs, 1.02 kcal molˉ¹ for EAs, and 1.51 kcal molˉ¹ for PAs, without including the "high-level correction" (HLC) contained in the original Gn methods. Whereas the HLC originated in the Gaussian-1 method as an isogyric correction, it evolved into a fitted parameter that minimized the error of the composite methods, eliminating its physical meaning. Recomputing the G1 and G3 enthalpies of formation without the HLC reveals a systematic trend where most ∆Hf values are significantly higher than experimental values. By extrapolating electronic energies to the complete basis set (CBS) limit and adding G3-like corrections for the core-valence and infinite-order electron correlation effects, ccCA-CBS-2 often underestimates the experimental ∆Hf, especially for larger systems. This is desired as inclusion of relativistic and atomic spin-orbit effects subsequently improves theoretical ∆Hf values to give a 0.81 kcal molˉ¹ mean absolute deviation with ccCA-CBS-2. The ccCA-CBS method is a viable "black box" method that can be used on systems with at least 10-15 heavy atoms. American Institute of Physics 2006-03-17 Article 17 p. Text doi: 10.1063/1.2173988 http://digital.library.unt.edu/ark:/67531/metadc75421/ ark: ark:/67531/metadc75421 The Journal of Chemical Physics, 2006, College Park: American Institute of Physics English Public

info:ark/67531/metadc75422 2013-03-14T15:55:50Z partner:UNTCAS collection:UNTSW access_rights:public

Application of the Correlation Consistent Composite Approach (ccCA) to Third-Row (Ga-Kr) Molecules DeYonker, Nathan J. Mintz, Benjamin Cundari, Thomas R., 1964- Wilson, Angela K. correlation consistent composite approachs molecules ccCA This article discusses the application of the correlation consistent composite approach (ccCA). Abstract: The correlation consistent composite approach (ccCA) has been applied to the G3/05 training set of 51 energetic properties for the atoms and molecules that contain the 4p elements, Ga-Kr. When atomic and molecular first-order spin orbit coupling corrections are added to open shell atoms and molecules, the ccCA has a mean absolute deviation from experiment (MAD) of 0.95 kcal mol-1, an improvement of 0.10 kcal mol-1 over G3 and G3X model chemistries. The performance of the ccCA on third-row-containing atoms and molecules is, therefore, commensurate in accuracy with previous studies on lighter main group elements H-Ar. While the typical methods used to compute theoretical molecular spin orbit corrections may go against the spirit of "black box" model chemistries, such corrections may be necessary for molecules containing heavy elements such as Ga-Kr. For example, when second-order spin orbit corrections are added to the atomic and molecular energies, the ccCA MAD is reduced to 0.88 kcal mol-1. American Chemical Society 2008-01-19 Article 7 p. Text doi: 10.1021/ct7002463 http://digital.library.unt.edu/ark:/67531/metadc75422/ ark: ark:/67531/metadc75422 Journal of Chemical Theory and Computation, 2008, Washington DC: American Chemical Society, pp. 328-334 English Public

info:ark/67531/metadc75424 2013-03-14T16:25:42Z partner:UNTCAS collection:UNTSW access_rights:public

Synthesis of the Five-Coordinate Ruthenium (II) Complexes [(PCP)Ru(CO)(L)][BAr'4] {PCP = 2,6-(CH2PtBu2)2 C6H3, BAr'4 = 3,5-(CF3)2C6H3, L= ɳ1-CICH2CI, ɳ 1-N2, or μ-Cl-Ru(PCP)(CO)}: Reactions with Phenyldiazomethane and Phenylacetylene Zhang, Jubo Barakat, Khaldoon A. Cundari, Thomas R., 1964- Gunnoe, T. Brent Boyle, Paul D. Petersen, Jeffrey L. Day, Cynthia S. five-coordinate complexes ruthenium II phenyldiazomethane phenylacetylene This article discusses complexes and reactions. Reaction of (PCP)Ru(CO)(CI) (1) with NaBAr'4 yields the bimetallic product [{(PCP)Ru(CO)}2 (μ-CI)][BAr'4] (2). The monomeric five-coordinate complexes [(PCP)Ru(CO)(ɳ1-CICH2CI)][BAr'4] (3) and [(PCP)Ru(CO)(ɳ1-N2)][BAr'4] (4) are synthesized upon reaction of (PCP)Ru(CO)(OTf) (6) with NaBAr'4 in CH2CI2 or C6H5F, respectively. The solid-state structures of 2,3, and 4 have been determined by X-ray diffraction studies of single crystals. The reaction of 3 with PhCHN2 or PhC=CH affords carbon-carbon coupling products involving the aryl group of the PCP ligand in transformations that likely proceed via the formation of Ru carbene or vinylidene intermediates. Density functional theory and hybrid quantum mechanics/molecular mechanics calculations were performed to investigate the bonding of weak bases to the 14-electron fragment [(PCP)Ru(CO)]+ and the energetics of different isomers of the product carbene and vinylidene complexes. American Chemical Society 2005-10-06 Article 12 p. Text doi: 10.1021/ic051074k http://digital.library.unt.edu/ark:/67531/metadc75424/ ark: ark:/67531/metadc75424 Inorganic Chemistry, 2005, Washington DC: American Chemical Society, pp. 8379-8390 English Public

info:ark/67531/metadc75419 2013-03-14T16:24:05Z partner:UNTCAS collection:UNTSW access_rights:public

Stability Studies of Transition-Metal Linkage Isomers Using Quantum Mechanical Methods, Groups 11 and 12 Transition Metals Buda, Corneliu Kazi, Abul B. Dinescu, Adriana Cundari, Thomas R., 1964- linkage isomers transition metals This article discusses stability studies of transition-metal isomers. Several hypotheses to elucidate the linkage isomer preference of the thiocyanate (SCN¯) ion have been offered. For complexes with small coordination numbers (i.e. 1 and 2) and groups 11 (Cu-triad) and 12 (Zn-triad) metals, different levels of theory and a variety of basis sets have been employed to study linkage isomerism. Similar results are obtained for all density functionals tested, pure and hybrid. Overall, good agreement, vis-á-vis experimentally identified linkage isomers, is achieved for ab initio techniques, whereas semiempirical quantum mechanical methods show a bias toward S-ligated isomers. Despite the seeming ease for the a priori prediction of the most stable thiocyanate isomers using acid/base principles, this research highlights the sensitivity of quantitative calculations of transition-metal linkage isomerism to the choice of basis set and electron correlation, particularly with post-Hartree-Fock treatments. American Chemical Society 2005-04-29 Article 6 p. Text doi: 10.1021/ci050050t http://digital.library.unt.edu/ark:/67531/metadc75419/ ark: ark:/67531/metadc75419 Journal of Chemical Information and Modeling, 2005, Washington DC: American Chemical Society, pp. 965-970 English Public

info:ark/67531/metadc75425 2013-03-18T13:16:14Z partner:UNTCAS collection:UNTSW access_rights:public

The Butterfly Dimer [(tBu3SiO)Cr]2 (μ-OSitBu3)2 and Its Oxidative Cleavage to (tBu3SiO)2 Cr(=N-N=CPh2)2 and (tBu3SiO)2 Cr=N(2,6-Ph2-C6H3) Sydora, Orson L. Kuiper, David S. Wolczanski, Peter T. Lobkovsky, Emil B. Dinescu, Adriana Cundari, Thomas R., 1964- butterfly dimers oxidative cleavage This article discusses the butterfly dimer. Abstract: Treatment of CrCl2(THF)2 with NaOSitBu3 afforded the butterfly dimer [(tBu3SiO)Cr]2 (μ-OSitBu3)2 (1 2), whose d(CrCr) of 2.658(31) Å and magnetism were indicative of strong antiferromagnetic coupling. A Boltzmann distribution of low-energy 1A1, 3B1, 5A1, 7B1, and 9A1 states obtained from calculations on [(HO)2Cr]2(μOH)2 (1'2) were used to provide a reasonable fit of the μeff vs T data. Cleavage of 1 2 with various L (L=4-picoline, p-tolunitrile, tBuCN, tBuNC, Ph2CO, and PMe3) generated (tBu3SiO)2CrL2(1-L2). The dimer was oxidatively severed by Ph2CN2 to give (tBu3SiO)2Cr(N2CPh2)2 (2) and by RN3 at 23 ˚C to afford (silox)2Cr=NR (3-R) for bulky R (adamantyl (Ad), 2,6-iPr2-C6H3, 2,4,6-Me3-C6H2 = Mes, 2,6-Ph2-C6H3) and (tBu3SiO)2Cr(=NR)2 (4-R) for smaller substituents (R = 1-Naph, 2-Anth). X-ray structural studies were conducted on 1 2, square planar 1-(OCPh2)2, pseudo-Td 2 and pseudotrigonal 3-(2,6-Ph2-C6H3), whose S = 1 ground state was discussed on the basis of calculations of (H3SiO)2Cr = NPh (3"-Ph). American Chemical Society 2006-01-12 Article 14 p. Text doi: 10.1021/ic051481w http://digital.library.unt.edu/ark:/67531/metadc75425/ ark: ark:/67531/metadc75425 Inorganic Chemistry, 2006, Washington DC: American Chemical Society, pp. 2008-2021 English Public

info:ark/67531/metadc75418 2012-05-10T16:22:41Z partner:UNTCAS collection:UNTSW access_rights:public

Non-Gaussian statistics of anomalous diffusion: The DNA sequences of prokaryotes Allegrini, Paolo Buiatti, Marco Grigolini, Paolo West, Bruce J. non-Gaussian statistics DNA sequences This article discusses non-Gaussian statistics of anomalous diffusion. The authors adopt a non-Gaussian indicator to measure the deviation from Gaussian statistics of a diffusion process generated by dichotomous fluctuations with infinite memory. The authors also make analytical predictions on the transient behavior of the non-Gaussian indicator as well as on its stationary value. The authors then apply this non-Gaussian analysis to the DNA sequences of prokaryotes adopting a theoretical model where the "DNA dynamics" are assumed to be determined by the statistical superposition of two independent generators of fluctuations: a generator of fluctuations with no correlation and a generator of fluctuations with infinite correlation "time". The authors study also the influence that the finite length of the observed sequences has on the short-range fluctuation and sequence truncation. Nevertheless, under proper conditions, fulfilled by all the DNA sequences of prokaryotes that have been examined, a non-Gaussian signature remains to signal the correlated nature of the driving process. American Physical Society 1998-09 Article 9 p. Text doi: 10.1103/PhysRevE.58.3640 http://digital.library.unt.edu/ark:/67531/metadc75418/ ark: ark:/67531/metadc75418 Physical Review E, 1998, College Park: American Physical Society, pp. 3640-3648 English Public

info:ark/67531/metadc75423 2013-03-14T16:12:29Z partner:UNTCAS collection:UNTSW access_rights:public

Low-Coordinate Chromium Siloxides: The "Box" [Cr(μ-OSitBu3)]4, Distorted Trigonal [(tBu3SiO)3Cr] [Na(benzene)] and [(tBu3SiO)3Cr] [Na(dibenzo-18-c-6)], and Trigonal (tBu3SiO)3Cr Sydora, Orson L. Wolczanski, Peter T. Lobkovsky, Emil B. Buda, Corneliu Cundari, Thomas R., 1964- transition-metal complexes chromium siloxides This article discusses low-coordinate chromium siloxides. Treatment of CrCl2(THF)2 with NaOSitBu3 afforded the tetrameric "box" [Cr(μ-OSitBu3)]4 (1,X-ray). THF cleaved 1 to provide trans-(silox)ClCr(THF)2 (2), whereas degradation of 1 with 4-picoline caused disproportionation and the generation of trans-Cl2Cr(4-pic)2 and trans-(silox)2 Cr(4-pic)x (n=2,3; 3,3-4-pic). Chromous centers in 1 were antiferromagnetically coupled, and density functional calculations on the high-spin (multiplicity = 17) model [Cr-(μ-Cl)(μ-OH)]4 (1') revealed that its singly occupied 3d orbitals spanned an energy range of ͠2 eV. The addition of 8 equiv of Na(silox) to 1 yielded [(tBu3SiO)Cr(μ-OSitBu3)2] Na·C6H6 (4, Y shaped, ∠OCrO(Na) = 91.28(7)°), and treatment of 4 with dibenzo-18-crown-6 produced [(silox)(3)Cr] [Na(dibenzo-18-crown-6)] (5, ∠OCrO = ͠120°, (120 + α)°, (120 - α)°). Calculations of [((t)Bu(3)SiO)Cr(mu-OSi(t)Bu(3))(2)]Na (4') and Cr(silox)(3)(-) (5') provided reasonable matches with the experimental geometries (X-ray). The trigonal chromic derivative (silox)(3)Cr(6) was synthesized from CrCI(3)(THF)(3) for structural and calculational comparisons to the chromous derivatives. American Chemical Society 2005-03-24 Article Text doi: 10.1021/ic0488334 http://digital.library.unt.edu/ark:/67531/metadc75423/ ark: ark:/67531/metadc75423 Inorganic Chemistry, 2005, Washington DC: American Chemical Society, pp. 2606-2618 English Public

info:ark/67531/metadc75414 2013-04-15T12:17:16Z partner:UNTCAS collection:UNTSW access_rights:public

Function of Conserved Residues of Human Glutathione Synthetase: Implications for the ATP-grasp Enzymes Dinescu, Adriana Cundari, Thomas R., 1964- Bhansali, Vikas S. Luo, Jia-Li Anderson, Mary E. glutathione synthetase enzymes This article discusses human glutathione synthetase. Abstract: Glutathione synthetase is an enzyme that belongs to the glutathione synthetase ATP-binding domain-like superfamily. It catalyzes the second step in the biosynthesis of glutathione from y-glutamylcysteine and glycine in an ATP-dependent manner. Glutathione synthetase has been purified and sequenced from a variety of biological sources; still, its exact mechanism is not fully understood. A variety of structural alignment methods were applied and four highly conserved residues of human glutathione synthetase (Glu-144, Asn-146, Lys-305, and Lys-364) were identified in the binding site. The function of these was studied by experimental and computational site-directed mutagenesis. The three-dimensional coordinates for several human glutathione synthetase mutant enzymes were obtained using molecular mechanics and molecular dynamics simulation techniques, starting from the reported crystal structure of human glutathione synthetase. Consistent with circular dichroism spectroscopy, the authors' results showed no major changes to overall enzyme structure upon residue mutation. However, semiempirical calculations revealed that ligand binding is affected by these mutations. The key interactions between conserved residues and ligands were detected and found to be essential for enzymatic activity. Particularly, the negatively charged Glu-144 residue plays a major role in catalysis. American Society for Biochemistry and Molecular Biology 2004-02-27 Article Text doi: 10.1074/jbc.M401334200 http://digital.library.unt.edu/ark:/67531/metadc75414/ ark: ark:/67531/metadc75414 Journal of Biological Chemistry, 2004, Rockville: American Society for Biochemistry and Molecular Biology, pp. 22412-22421 English Public

info:ark/67531/metadc75416 2013-04-12T15:12:52Z partner:UNTCAS collection:UNTSW access_rights:public

Fractional Brownian motion as a nonstationary process: An alternative paradigm for DNA sequences Allegrini, Paolo Buiatti, Marco, 1972- Grigolini, Paolo West, Bruce J. DNA sequences Fractional Brownian Motion This article discusses fractional Brownian motion as a nonstationary process. Abstract: The long-range correlations in DNA sequences are currently interpreted as an example of stationary fractional Brownian motion (FBM). First the authors show that the dynamics of a dichotomous stationary process with long-range correlations such as that used to model DNA sequences should correspond to Lévy statistics and not to FBM. To explain why, in spite of this, the statistical analysis of the data seems to be compatible with FBM, the authors notice that an initial Gaussian condition, generated by a process foreign to the mechanism establishing the long-range correlations and consequently implying a departure from the stationary condition is maintained approximately unchanged for very long times. This is so because due to the nature itself of the long-range correlation process, it takes virtually an infinite time for the system to reach the genuine stationary state. Then the authors discuss a possible generator of initial Gaussian conditions, based on a folding mechanism of the nucleic acid in the cell nucleus. The model adopted is compatible with the known biological and physical constraints, namely, it is shown to be consistent with the information of current biological literature on folding as well as with the statistical analyses of DNA sequences. American Physical Society 1998-04 Article 10 p. Text doi: 10.1103/PhysRevE.57.4558 http://digital.library.unt.edu/ark:/67531/metadc75416/ ark: ark:/67531/metadc75416 Physical Review E, 1998, College Park: American Physical Society, pp. 4558-4567 English Public

info:ark/67531/metadc77132 2013-03-14T16:32:13Z partner:UNTCAS collection:UNTSW access_rights:public

Bonding and Structure of Copper Nitrenes Cundari, Thomas R., 1964- Dinescu, Adriana Kazi, Abul B. copper nitrenes bonding This article discusses bonding and structure of copper nitrenes. Abstract: Copper nitrenes are of interest as intermediates in the catalytic aziridination of olefins and the amination of C-H bonds. However, despite advances in the isolation and study of late-transition-metal multiply bonded complexes, a bona fide structurally characterized example of a terminal copper nitrene has, to our knowledge, not been reported. In anticipation of such a report, terminal copper nitrenes are studied from a computational perspective. The nitrene complexes studied here are of the form (ß-diketiminate)Cu(NPh). Density functional theory (DFT), complete active space self-consistent-field (CASSCF) electronic structure techniques, and hybrid quantum mechanical/molecular mechanical (QM/MM) methods are employed to study such species. While DFT methods indicate that a triplet (S + 1) is the ground state, CASSCF calculations indicate the a singlet (S = 0) is the ground state, with only a small energy gap between the singlet and triplet. Moreover, the ground-state (open-shell) singlet copper nitrene is found to be highly multiconfigurational (i.e., biradical) and to possess a bent geometry about the nitrene nitrogen, contrasting with the linear nitrene geometry of the triplet copper nitrenes. CASSCF calculations also reveal the existence of a closed-shell singlet state with some degree of multiple bonding character for the copper-nitrene bond. American Chemical Society 2008-10-04 Article 6 p. Text doi: 10.1021/ic801337f http://digital.library.unt.edu/ark:/67531/metadc77132/ ark: ark:/67531/metadc77132 Inorganic Chemistry, 2008, Washington DC: American Chemical Society, pp. 10067-10072 English Public

info:ark/67531/metadc77128 2013-03-18T14:17:13Z partner:UNTCAS collection:UNTSW access_rights:public

Chemistry Surrounding Monomeric Copper(l) Methyl, Phenyl, Anilido, Ethoxide, and Phenoxide Complexes Supported by N-Heterocyclic Carbene Ligands: Reactivity Consistent with Both Early and Late Transition Metal Systems Goj, Laurel A. Blue, Elizabeth D. Delp, Samuel A. Gunnoe, T. Brent Cundari, Thomas R., 1964- Pierpont, Aaron W. Petersen, Jeffrey L. Boyle, Paul D. monomeric copper transition metal systems This article discusses transition metal systems. Abstract: Monomeric copper(l) alkyl complexes that possess the N-heterocyclic carbene (NHC) ligands IPr, SIPr, and IMes [IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, SIPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene, IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene] react with amines or alcohols to release alkane and form the corresponding monomeric copper(l) amido, alkoxide, or aryloxide complexes. Thermal decomposition reactions of (NHC)Cu׀ methyl complexes at temperatures between 100 and 130 °C produce methane, ethane, and ethylene. The reactions of (NHC)Cu(NHPh) complexes with bromoethane reveal increasing nucleophilic reactivity at the anilido ligand in the order (SIPR)Cu(NHPh) < (IPr)Cu(NHPh) < (IMes)Cu(NHPh) < (dtbpe)Cu(NHPh) [dtbpe = 1,2-bis(di-tert-butylphosphino)ethane]. DFT calculations suggest that the HOMO for the series of Cu anilido complexes is localized primarily on the amido nitrogen with some pπanilido-dπCu π*-character. [(IPr)Cu(μ-H)]2 and (IPr)Cu(Ph) react with aniline to quantitatively produce (IPr)Cu(NHPh)/dihydrogen and (IPr)Cu(NHPh)/benzene, respectively. Analysis of the DFT calculations reveals that the conversion of [(IPr)Cu(μ-H)]2 and aniline to (IPr)Cu(NHPh) and dihydrogen is favorable with ∆H ≈ -7 kcal/mol and ∆G ≈ -9 kcal/mol. American Chemical Society 2006-09-27 Article 14 p. Text doi: 10.1021/ic0611995 http://digital.library.unt.edu/ark:/67531/metadc77128/ ark: ark:/67531/metadc77128 Inorganic Chemistry, 2006, Washington DC: American Chemical Society, pp. 9032-9045 English Public

info:ark/67531/metadc77114 2013-03-14T17:21:45Z partner:UNTCAS collection:UNTSW access_rights:public

BOV - a web-based BLAST output visualization tool Gollapudi, Rajesh Revanna, Kashi V. Hemmerich, Chris Schaack, Sarah Dong, Qunfeng output visualization tools blast output visualization BOV genomic research This article discusses BOV, a web-based BLAST output visualization tool. Abstract: Background: The BLAST program is one of the most widely used sequence similarity search tools for genomic research, even by those biologists lacking extensive bioinformatics training. As the availability of sequence data increases, more researchers are downloading the BLAST program for local installation and performing larger and more complex tasks, including batch queries. In order to manage and interpret the results of batch queries, a host of software packages have been developed to assist with data management and post-processing. Among these programs, there is almost a complete lack of visualization tools to provide graphic representation of complex BLAST pair-wise alignments. The authors have developed a web-based program, BLAST Output Visualization Tool (BOV), that allows users to interactively visualize the matching regions of query and database hit sequences, thereby allowing the user to quickly and easily dissect complex matching patterns. Results: Users can upload the standard BLAST output in pair-wise alignment format as input to the web server (including batch queries generated installing and running the stand-alone BLAST program on a local server). The program extracts the alignment coordinates of matching regions between the query and the corresponding database hit sequence. The coordinates are used to plot each matching region as colored lines or trapezoids. Using the straightforward control panels throughout the web site, each plotted matching region can be easily explored in detail by, for example, highlighting the region of interest or examining the raw pair-wise sequence alignment. Tutorials are provided at the website to guide users step-by-step through the functional features of BOV. Conclusion: BOV provides a user-friendly web interface to visualize the standard BLAST output for investigating wide-ranging genomic problems, including single query and batch query datasets. In particular, this software is valuable to users interested in identifying regions of co-linearity, duplication, translocation, and inversion among sequences. A web server hosting BOV is accessible via http://bioportal.cgb.indiana.edu/cgi-bin/BOV/index.cgi and the software is freely available for local installations. BioMed Central Ltd. 2008-09-15 Article 6 p. Text doi: 10.1186/1471-2164-9-414 http://digital.library.unt.edu/ark:/67531/metadc77114/ ark: ark:/67531/metadc77114 BMC Genomics, 2008, London: BioMed Central Ltd. English Public

info:ark/67531/metadc77145 2013-03-18T13:34:09Z partner:UNTCAS collection:UNTSW access_rights:public

Catalytic Tuning of a Phosphinoethane Ligand for Enhanced C-H Activation Cundari, Thomas R., 1964- Jimenez-Halla, J. Oscar C. Morello, Glenn R. Vaddadi, Sridhar phosphinoethane ligand C-H activation catalytic tuning This article discusses catalytic tuning of a phosphinoethane ligand for enhanced C-H activation. Abstract: Hydrogen atom abstraction (HAA) from 1,4-cyclohexadiene (CD-H) by (dtbpe)Ni(NAr) to form a Niǀ-amide, (dtbpe)Ni(NHAr), and cyclohexadienyl radical is calculated to be thermodynamically reasonable, ∆Hʜᴀᴀ(dtbpe) = -1.3 kcal/mol, dtbpe = bis(di-tert-butylphosphino)ethane, Ar = 2,6-diisopropylphenyl. However, radical rebound to form a metal-bound amine is highly endothermic (∆Hreb(dtbpe) = +25.1 kcal/mol). Analysis of bond enthalpies indicates that weakening of the Ni-N bond (Ni-amide→Ni-amine) upon radical rebound is not compensated by the weak C-N bond formed. Hence, a ligand was sought that would enhance the metal-amine bond strength while diminishing the metal-amide bond strength. Reaction of (dfmpe)Ni(NAr) with CD-H was thus analyzed, dfmpe = bis(di(trivluoromethyl)phosphino)ethane. While there is a small change in the thermodynamics of HAA (∆Hʜᴀᴀ(dfmpe) = -5.7 kcal/mol), there is a profound change in the rebound step (∆Hreb(dfmpe) = -7.8 kcal/mol) upon replacing dtbpe by dfmpe. Regeneration of the nitrene active species by reaction of ArN3 with the metal-bound product is calculated to be highly exothermic, ∆Hreg = -36.7 kcal/mol. Two candidates for a precatalyst, (dfmpe)Ni(COD) and (dfmpe)Ni(bpy), COD = 1,5-cyclooctadiene and bpy = 2,2´-bipyridine, were calculated to undergo highly exothermic reactions with ArN3 to form the nitrene active species. The calculated enthalpic barrier for HAA of CD-H by (dfmpe)Ni(NAr) is 21.3 kcal/mol. Hence, consideration of the computed thermodynamics and kinetics suggests that nickel-nitrenes with fluorinated phosphine supporting ligation are promising candidates for catalytic amination of C-H bonds. American Chemical Society 2008-09-05 Article 8 p. Text doi: 10.1021/ja803176 http://digital.library.unt.edu/ark:/67531/metadc77145/ ark: ark:/67531/metadc77145 Journal of the American Chemical Society, 2008, Washington DC: American Chemical Society, pp. 13051-13058 English Public

info:ark/67531/metadc77140 2013-03-20T11:25:07Z partner:UNTCAS collection:UNTSW access_rights:public

Comparative Reactivity of TpRu(L)(NCMe)Ph (L = CO or PMe3): Impact of Ancillary Ligand L on Activation of Carbon-Hydrogen Bonds Including Catalytic Hydroarylation and Hydrovinylation/Oligomerization of Ethylene Foley, Nicholas A. Lail, Marty Lee, John P. Gunnoe, T. Brent Cundari, Thomas R., 1964- Petersen, Jeffrey L. benzene C-H activation catalytic ethylene hydrophenylation catalytic production isotopic labeling kinetic studies reversible dissociation This article discusses comparative reactivity of TpRu(L)(NCMe)Ph (L = CO or PMe3). Abstract: Complexes of the type TpRu(L)(NCMe)R [L = CO or PMe3; R = Ph or Me; Tp = hydridotris-(pyrazolyl)borate] initiate C-H activation of benzene. Kinetic studies, isotopic labeling, and other experimental evidence suggest that the mechanism of benzene C-H activation involves reversible dissociation of acetonitrile, reversible benzene coordination, and rate-determining C-H activation of coordinated benzene. TpRu(PMe3)(NCMe)Ph initiates C-D activation of C6D6 at rates that are approximately 2-3 times more rapid than that for TpRu(CO)(NCMe)Ph (depending on substrate concentration); however, the catalytic hydrophenylation of ethylene using TpRu(PMe3)(NCMe)Ph is substantially less efficient than catalysis with TpRu(CO)(NCMe)Ph. For TpRu(PMe3)(NCMe)Ph, C-H activation of ethylene, to ultimately produce TpRu-(PMe3)(ɳ3-C4H7), is found to kinetically compete with catalytic ethylene hydrophenylation. In THF solutions containing ethylene, TpRu(PMe3)(NCMe)Ph and TpRu(CO)(NCMe)Ph separately convert to TpRu(L)(ɳ3-C4H7)(L = PMe3 or CO, respectively) via initial Ru-mediated ethylene C-H activation. Heating mesitylene solutions of TpRu(L)(ɳ3-C4H7) under ethylene pressure results in the catalytic production of butenes (i.e., ethylene hydrovinylation) and hexenes. American Chemical Society 2007-05-09 Article 17 p. Text doi: 10.1021/ja068542p http://digital.library.unt.edu/ark:/67531/metadc77140/ ark: ark:/67531/metadc77140 Journal of the American Chemical Society, 2007, Washington DC: American Chemical Society, pp. 6765-6781 English Public

info:ark/67531/metadc77141 2013-03-14T15:55:33Z partner:UNTCAS collection:UNTSW access_rights:public

Activation of Carbon-Hydrogen Bonds via 1,2-Addition across M-X (X = OH or NH2) Bonds of d6 Transition Metals as a Potential Key Step in Hydrocarbon Functionalization: A Computational Study Cundari, Thomas R., 1964- Grimes, Thomas V. Gunnoe, T. Brent activating electrophiles benzene C-H bonds catalytic functionalization cycles ligand X transition metal complexes This article discusses the activation of carbon-hydrogen bonds. Abstract: Recent reports of 1,2-addition of C-H bonds across Ru-X(X = amido, hydroxo) bonds of TpRu-(PMe₃)X fragments {Tp = hydridotris(pyrazolyl)borate} suggest opportunities for the development of new catalytic cycles for hydrocarbon functionalization. In order to enhance understanding of these transformations, computational examinations of the efficacy of model d6 transition metal complexes of the form [(Tab)M-(PH3)2X]q (Tab = tris-azo-borate; X = OH, NH2; q = -1 to +2; M = Tc(I), Re(I), Ru(II), Co(III), Ir(III), Ni(IV) Pt(IV) for the activation of benzene C-H bonds, as well as the potential for their incorporation into catalytic functionalization cycles, are presented. For the benzene C-H activation reaction steps, kite-shaped transition states were located and found to have relatively little metal-hydrogen interaction. The C-H activation process is best described as a metal-mediated proton transfer in which the metal center and ligand X function as an activating electrophile and intramolecular base, respectively. While the metal plays a primary role in controlling the kinetics and thermodynamics of the reaction coordinate for C-H activation/functionalization, the ligand X also influences the energetics. On the basis of three thermodynamic criteria characterizing salient energetic aspects of the proposed catalytic cycle and the detailed computational studies reported herein, late transition metal complexes (e.g., Pt, Co, etc.) in the d6 electron configuration {especially the TabCo(PH3)2(OH)+ complex and related Co(III) systems} are predicted to be the most promising for further catalyst investigation. American Chemical Society 2007-10-06 Article 11 p. Text doi: 10.1021/ja074125g http://digital.library.unt.edu/ark:/67531/metadc77141/ ark: ark:/67531/metadc77141 Journal of the American Chemical Society, 2007, Washington DC: American Chemical Society, pp. 13172-13182 English Public

info:ark/67531/metadc77136 2013-03-14T15:54:46Z partner:UNTCAS collection:UNTSW access_rights:public

3-Center-4-Electron Bonding in [(silox)2Mo=NtBu]2(μ-Hg) Controls Reactivity while Frontier Orbitals Permit a Dimolybdenum π-Bond Energy Estimate Rosenfeld, Devon C. Wolczanski, Peter T. Barakat, Khaldoon A. Buda, Corneliu Cundari, Thomas R., 1964- bonding reactivity energies magnetic studies This article discusses 3-center-4-electron bonding. Abstract: Na/Hg reduction of (silox)2Cl2Mo=NtBu (3) afforded C2h [(silox)2Mo=NtBu]2(μ-Hg) (12-Hg), which consists of two distorted trigonal monoprisms with Hg at the each apex (d(MoHg) = 2.6810(5)Å). Calculations reveal 3c4e bonding in the linear MoHgMo linkage that renders 12-Hg susceptible to nucleophilic cleavage. Exposure to PMe3 and pyridine rapidly (<5 min) affords (silox)2(tBuN)MoLn (L = PMe3, n = 1 (1-PMe3); py, n = 2 (1-py2)), while poorer nucleophiles (L = C2H4, 2-butyne) yield adducts (e.g., 1-C2H4 and 1-C2Me2) after prolonged heating. The HOMO and LUMO of 12-Hg are "stretched" π and π* orbitals from which four states arise: 1Ag (GS), 3Bu, 1Bu, and 1Ag. ∆E = E(1Bu) - E(3Bu) = 2K, where K is the exchange energy. Magnetic studies indicate E(3Bu) - E(1Ag) ≈ 550 cm-1 (calcd 1744 cm-1), and a UV-vis absorption at 10 000 cm-1 is assigned to 1Ag → 1Bu, permitting K to be evaluated as 4725 cm-1. With the π → π* transition in Schrock's [Mo(NAr)(CH2tBu)(OC6F5)]2 (4) assigned at 528 nm, this estimation places its π-bond energy as {E(π2 → π-1 → π*1 in 4) - E(1Ag → 1Bu in 12-Hg)} + E(1Ag → 3Bu in 12-Hg) = 27 kcal/mol. American Chemical Society 2005-05-18 Article 2 p. Text doi: 10.1021/ja051070e http://digital.library.unt.edu/ark:/67531/metadc77136/ ark: ark:/67531/metadc77136 Journal of the American Chemical Society, 2005, Washington DC: American Chemical Society English Public

info:ark/67531/metadc77120 2012-12-07T14:10:24Z partner:UNTCAS collection:UNTSW access_rights:public

Tunneling rate fluctuations induced by nonlinear resonances: A quantitative treatment based on semiclassical arguments Bonci, Luca Farusi, Andrea Grigolini, Paolo Roncaglia, Roberto tunneling classical chaos nonlinear resonance This article discusses tunneling rate fluctuations induced by nonlinear resonances. The authors investigate the tunneling process between two symmetric stable islands of a forced pendulum Hamiltonian in the weak chaos regime. The authors show that when the tunneling doublet is quantized over a classical nonlinear resonance the tunneling rate strongly deviates from the semiclassical prediction. This mechanism is responsible for the irregular dependence of the tunneling rate on the system parameters. The weak-chaos condition allows us to make a theoretical prediction that agrees very well with the numerical results. This opens up a possible avenue to a general theory on the dependence of quantum tunneling on classical chaos. American Physical Society 1998-11 Article 4 p. Text doi: 10.1103/PhysRevE.58.5689 http://digital.library.unt.edu/ark:/67531/metadc77120/ ark: ark:/67531/metadc77120 Physical Review E, 1998, College Park: American Physical Society, pp. 5689-5692 English Public

info:ark/67531/metadc77119 2012-12-06T17:18:40Z partner:UNTCAS collection:UNTSW access_rights:public

Re-assessing the science - society relation: The case of the US National Science Foundation's broader impacts merit review criterion (1997 - 2011) Holbrook, J. Britt U.S. National Science Foundation (NSF) merit reviews peer reviews broader impacts scientific autonomy scientific accountability philosophy of science policies metrics This article discusses the science - society relation. In 2005, the author published the first scholarly article on the US National Science Foundation's Broader Impacts Merit Review Criterion. In the intervening years, much has happened, both in terms of scholarship on the Broader Impacts Criterion and in terms of the Broader Impacts Criterion itself. Here, the author revisits that original article, answering some questions, filling in some blanks, expanding some bits, contracting others, updating and generally rethinking the whole thing. The National Science Board has also rethought the Broader Impacts Criterion, and 2011 marks the gestation, if not the birth, of a much different criterion, a sort of Broader Impacts Criterion and about the dialectic between the values of autonomy and accountability in the science - society relation. Elsevier 2012 Article 22 p. Text http://digital.library.unt.edu/ark:/67531/metadc77119/ ark: ark:/67531/metadc77119 Technology in Society, 2005, Amsterdam: Elsevier English Public

info:ark/67531/metadc77112 2012-03-02T11:47:25Z partner:UNTCAS collection:UNTSW access_rights:public

Tracembler - software for in-silico chromosome walking in unassembled genomes Dong, Qunfeng Wilkerson, Matthew D. Brendel, Volker Tracembler software chromosomes genomes This article discusses Tracembler. Background: Whole genome shotgun produces increasingly higher coverage of a genome with random sequence reads. Progressive whole genome assembly and eventual finishing sequencing is a process that typically takes several years for large eukaryotic genomes. In the interim, all sequence reads of public sequencing projects are made available in repositories such as the NCBI Trace Archive. For a particular locus, sequencing coverage may be high enough early on to produce a reliable local genome assembly. The authors have developed software, Tracembler, that facilitates in silico chromosome walking by recursively assembling reads of a selected species from the NCBI Trace Archive starting with reads that significantly match sequence seeds supplied by the user. Results: Tracembler takes one or multiple DNA or protein sequence(s) as input to the NCBI Trace Archive BLAST engine to identify matching sequence reads from a species of interest. The BLAST searches are carried out recursively such that BLAST matching sequences identified in previous rounds of searches are used as new queries in subsequent rounds of BLAST searches. The recursive BLAST search stops when either no more new matching sequences are found, a given maximal number of queries is exhausted, or a specified maximum number of rounds of recursion is reached. All the BLAST matching sequences are then assembled into contigs based on significant sequence overlaps using the CAP3 program. The authors demonstrate the validity of the concept and software implementation with an example of successfully recovering a full-length Chrm2 gene as well as its upstream and downstream genomic regions from Rattus norvegicus reads. In a second example, a query with two adjacent Medicago truncatula genes as seeds resulted in a contig that likely identifies the microsyntenic homologous soybean locus. Conclusion: Tracembler streamlines the process of recursive database searches, sequence assembly, and gene identification in resulting contigs in attempts to identify homologous loci of genes of interest in species with emerging whole genome shotgun reads. A web server hosting Tracembler is provided at http://www.plantgdb.org/tool/tracembler/, and the software is also freely available from the authors for local installations. BioMed Central 2007-05 Article 6 p. Text doi: 10.1186/1471-2105-8-151 http://digital.library.unt.edu/ark:/67531/metadc77112/ ark: ark:/67531/metadc77112 BMC Bioinformatics, 2007, London: BioMed Central English Public

info:ark/67531/metadc77117 2012-04-06T16:49:47Z partner:UNTCAS collection:UNTSW access_rights:public

The Synergy Between Qualitative Theory, Quantitative Calculations, and Direct Experiments in Understanding, Calculating, and Measuring the Energy Differences Between the Lowest Singlet and Triplet States of Organic Diradicals Lineberger, W. Carl Borden, Weston Thatcher qualitative theory quantitative calculations energy differences organic diradicals This article discusses qualitative theory, quantitative calculations, and direct experiments. This Perspective describes research, carried out in the authors' labs over the past forty years, aimed at understanding, predicting, and measuring the singlet-triplet energy differences (∆Est) in diradicals. A theory for qualitatively predicting the ground states of diradicals and the use of Negative Ion Photoelectron Spectroscopy (NIPES) for measuring ∆Est are described. The application of this theory, ab initio calculations, and NIPES to the prediction and measurement of ∆Est in a wide variety of organic diradicals is detailed. Among the diradicals that are discussed in this Perspective are HN, CH3N, PhN, CH2, trimethylenemethane (TMM), oxyallyl (OXA), meta-benzoquinodimethane (MBQDM), meta-benzoquinone (MBQ), tetramethyleneethane (TME), 1,2,4,5-tetramethylenebenzene (TMB), and D8h COT were, in fact, collaborations between the research groups of the authors. These two projects both took advantage of the ability to NIPES to provide information about transition states. Transition-state spectroscopy was used to measure the cabonyl stretching frequency in the singlet state of OXA and to establish that D8h COT violates the strictest version of Hund's rule. Royal Society of Chemistry 2011-04-18 Article 45 p. Text doi: 10.1039/C0CP02786C http://digital.library.unt.edu/ark:/67531/metadc77117/ ark: ark:/67531/metadc77117 Physical Chemistry Chemical Physics, 2011, Cambridge: Royal Society of Chemistry English Public

info:ark/67531/metadc77113 2013-04-08T12:19:06Z partner:UNTCAS collection:UNTSW access_rights:public

ESTPiper - a web-based analysis pipeline for expressed sequence tags Tang, Zuojian Choi, Jeong-Hyeon Hemmerich, Chris Sarangi, Ankita Colbourne, John K. Dong, Qunfeng analysis pipelines expressed sequence tags ESTPiper genome sequencing technologies This article discusses ESTPiper, a web-based analysis pipeline for expressed sequence tags. Abstract: Background: EST sequencing projects are increasing in scale and scope as the genome sequencing technologies migrate from core sequencing centers to individual research laboratories. Effectively, generating EST data is no longer a bottleneck for investigators. However, processing large amounts of EST data remains a non-trivial challenge for many. Web-based EST analysis tools are proving to be the most convenient option for biologists when performing their analysis, so these tools must continuously improve on their utility to keep in step with the growing needs of research communities. The authors have developed a web-based EST analysis pipeline called ESTPiper, which streamlines typical large-scale EST analysis components. Results: The intuitive web interface guides users through each step of base calling, data cleaning, assembly, genome alignment, annotation, analysis of gene ontology (GO), and microarray oligonucleotide probe design. Each step is modularized. Therefore, a user can execute them separately or together in batch mode. In addition, the user has control over the parameters used by the underlying programs. Extensive documentation of ESTPiper's functionality is embedded throughout the web site to facilitate understanding of the required input and interpretation of the computational results. The user can also download intermediate results and port files to separate programs for further analysis. In addition, the authors' server provides a time-stamped description of the run history for reproducability. The pipeline can also be installed locally, allowing researchers to modify ESTPiper to suit their own needs. Conclusion: ESTPiper streamlines the typical process of EST analysis. The pipeline was initially designed in part to support the Daphnia pulex cDNA sequencing project. A web server hosting ESTPiper is provided at http://estpiper.cgb.indiana.edu/ to now support projects of all size. The software is also freely available from the authors for local institutions. BioMed Central Ltd. 2009-04-21 Article 8 p. Text doi: 10.1186/1471-2164-10-174 http://digital.library.unt.edu/ark:/67531/metadc77113/ ark: ark:/67531/metadc77113 BMC Genomics, 2009, London: BioMed Central Ltd., English Public Attribution

info:ark/67531/metadc77138 2013-04-08T15:56:05Z partner:UNTCAS collection:UNTSW access_rights:public

Evidence for the Net Addition of Arene C-H Bonds across a Ru(II)-Hydroxide Bond Feng, Yuee Lail, Marty Barakat, Khaldoon A. Cundari, Thomas R., 1964- Gunnoe, T. Brent Petersen, Jeffrey L. crystallography hydroxides organometallic compounds ruthenium molecular This articles discusses evidence for the net addition of arene C-H bonds. TpRu(PMe3)2(OH) (1) reacts with C6D6 to initiate H/D exchange between the hydroxide ligand and the deuterated benzene. In addition, complex 1 catalyzes H/D exchange between H20 and C6D6. Mechanistic and computational studies suggest that a likely reaction pathway for the H/D exchange involves loss of PMe3 to produce {TpRu(PMe3)(OH)}, followed by the net addition of a benzene C-H(D) bond across the Ru-OH bond to form the putative complex TpRu(PMe3)(OH2)(Ph). American Chemical Society 2005-09-27 Article 2 p. Text doi: 10.1021/ja054101e http://digital.library.unt.edu/ark:/67531/metadc77138/ ark: ark:/67531/metadc77138 Journal of the American Chemical Society, 2005, Washington DC: American Chemical Society, pp. 14174-14175 English Public

info:ark/67531/metadc77129 2013-04-08T15:47:35Z partner:UNTCAS collection:UNTSW access_rights:public

Evidence for Strong Tantalum-to-Boron Dative Interactions in (silox)3Ta(BH3) and (silox)3Ta(ɳ2-B,CI-BCI2Ph) (silox = tBu3SiO)1 Bonanno, Jeffrey B. Henry, Thomas P. Wolczanski, Peter T. Pierpont, Aaron W. Cundari, Thomas R., 1964- tantalum-to-boron transition metal complexes This article discusses strong tantalum-to-boron dative interactions. Abstract: Treatment of (silox)3 Ta (1, silox = tBu3SiO) with BH3·THF and BCI2Ph afforded (silox)3Ta(BH3) (2) and (silox)3Ta-(ɳ2-B,CI-BCI2Ph) (3), which are both remarkably stable Ta(III) compounds. NMe3 and ethylene failed to remove BH3 from 2, and no indication of BH3 exchange with BH3-THF-d8 was noted via variable-temperature 1H NMR studies. Addition of BH3-THF to (silox)3TaH2 provided the borohydride-hydride (silox)3HTa(ɳ3-BH4) (5), and its thermolysis released H2 to generate 2. Exposure of 2 to D2 enabled the preparation of isotopologues (silox)3Ta(BH3-nDn) (n = 0,2; 1,2-D; 2, 2-D₂; 3, 2-D₃) for isotopic perturbation of chemical shift studies, but these failed to distinguish between "inverse adduct" (i.e., (silox)3Ta→BH3) or (silox)3Ta(ɳ2-B,H-BH3) forms of 2. Computational models (RO)3Ta(BH3) (R = H, 2′-, SiH3, 2SiH SiMe3, 2SiMe, and SitBu3, 2SiBu) were investigated to assess the relative importance of steric and electronic effects on structure and bonding. With small R, ɳ2-B,H structures were favored, but for 2SiMe and 2SiBu, the dative structure proved to be similar in energy. The electronic and vibrational features of both structure types were probed. The IR spectrum of 2 was best matched by the ɳ2-B,H conformer of 2SiBu. In related computations pertaining to 3, small R models favored the oxidative addition of a BCI bond, while with R = SitBu3 (3SiBu), an excellent match with its X-ray crystal structure revealed the critical steric influence of the silox ligands. American Chemical Society 2007-01-24 Article 11 p. Text doi: 10.1021/ic0616885 http://digital.library.unt.edu/ark:/67531/metadc77129/ ark: ark:/67531/metadc77129 Inorganic Chemistry, 2007, Washington DC: American Chemical Society, pp. 1222-1232 English Public

info:ark/67531/metadc77121 2013-04-12T15:27:09Z partner:UNTCAS collection:UNTSW access_rights:public

Fractional calculus as a macroscopic manifestation of randomness Grigolini, Paolo Rocco, A. (Andrea) West, Bruce J. fractional calculus statistical mechanics This article discusses fractional calculus as a macroscopic manifestation of randomness. Abstract: We generalize the method of Van Hove [Physica (Amsterdam) 21, 517 (1955)] so as to deal with the case of nonordinary statistical mechanics, that being phenomena with no time-scale separation. We show that in the case of ordinary statistical mechanics, even if the adoption of the Van Hove method imposes randomness upon Hamiltonian dynamics, the resulting statistical process is described using normal calculus techniques. On the other hand, in the case where there is no time-scale separation, this generalized version of Van Hove's method not only imposes randomness upon the microscopic dynamics, but it also transmits randomness to the macroscopic level. As a result, the correct description of macroscopic dynamics has to be expressed in terms of the fractional calculus. American Physical Society 1999-03 Article 11 p. Text doi: 10.1103/PhysRevE.59.2603 http://digital.library.unt.edu/ark:/67531/metadc77121/ ark: ark:/67531/metadc77121 Physical Review E, 1999, College Park: American Physical Society, pp. 2603-2613 English Public

info:ark/67531/metadc77143 2013-04-17T10:44:05Z partner:UNTCAS collection:UNTSW access_rights:public

The Reactivity Patterns of Low-Coordinate Iron-Hydride Complexes Yu, Ying Sadique, Azwana R. Smith, Jeremy M. Dugan, Thomas R. Cowley, Ryan E. Brennessel, William W. Flaschenriem, Christine J. Bill, Eckhard Cundari, Thomas R., 1964- Holland, Patrick L. alkynes carbon monoxide cyanides hydrogen spectroscopy nitrogen x ray diffraction This article discusses the reactivity patterns of low-coordinate iron-hydride complexes. The authors report a survey of the reactivity of the first isolable iron-hydride complexes with a coordiination number less than 5. The high-spin iron(II) complexes [(β-diketiminate)Fe(μ-H)]2 react rapidly with representative cyanide, isocyanide, alkyne, N2, alkene, diazene, azide, CO2, carbodilimide, and Brønsted acid containing substrates. The reaction outcomes fall into three categories: (1) addition of Fe-H across a multiple bond of the substrate, (2) reductive elimination of H2 to form iron(I) products, and (3) protonation of the hydride to form iron(II) products. The products include imide, isocyanide, vinyl, alkyl, azide, triazenido, benzo[c]cinnoline, amidinate, formate, and hydroxo complexes. These results expand the range of known bond transformations at iron complexes. Additionally, they give insight into the elementary transformations that may be possible at the iron-molybdenum cofactor of nitrogenases, which may have hydride ligands on high-spin, low-coordinate metal atoms. American Chemical Society 2008-04-30 Article 15 p. Text doi: 10.1021/ja710669w http://digital.library.unt.edu/ark:/67531/metadc77143/ ark: ark:/67531/metadc77143 Journal of the American Chemical Society, 2008, Washington DC: American Chemical Society, pp. 6624-6638 English Public

info:ark/67531/metadc77133 2013-04-17T10:44:31Z partner:UNTCAS collection:UNTSW access_rights:public

Redox Activation of Alkene Ligands in Platinum Complexes with Non-innocent Ligands Boyer, Julie L. Cundari, Thomas R., 1964- DeYonker, Nathan J. Rauchfuss, Thomas B. Wilson, Scott R. alkene ligands platinum complexes non-innocent ligands This article discusses redox activation of alkene ligands. The reactivity of metal olefin complexes with non-innocent ligands (NILs) was examined. Treatment of PtCl2(diene) with the deprotonated catechol or aminophenol ligands afforded the corresponding Pt(NIL)(diene) complexes. The Pt(ͭBAfPh)(COD), Pt(tBAfPh)(nbd), and Pt(O2C6H2tBu2)(COD) (H2tBAfPh = 2-(2-trifluoromethyl)anilino-4,6-di-tert-butylphenol, H2O2C6H2tBu2 = 3,5-di-tert-butylcatechol) complexes were examined by cyclic voltammetry. Treatment of Pt(tBAfPh)(COD) or Pt(tBAfPh)(ndb) with AgPF6 afforded the imino-semiquinones [Pt(tBAfPh)(COD)] PF6 or [Pt(tBAfPh)(nbd)]PF6 respectively. The [Pt(tBAfPh)(COD)] complex was unreactive toward nucleophiles, whereas the oxidized derivative, [Pt(tBAfPh)(COD)]PF6, rapidly and stereospecifically added alkoxides at the carbon trans to the phenolate. The Pt(tBAfPh)(COD), [Pt(tBAfPh)(COD)]PF6, Pt(tBAfPh)(C8H12OMe), and [Cp2Co][Pt-(tBAfPh)(C8H12OMe)] complexes were characterized crystallographically. American Chemical Society 2009-12-19 Article 8 p. Text doi: 10.1021/ic8017248 http://digital.library.unt.edu/ark:/67531/metadc77133/ ark: ark:/67531/metadc77133 Inorganic Chemistry, 2009, Washington DC: American Chemical Society, pp. 638-645 English Public

info:ark/67531/metadc77126 2013-04-17T10:39:27Z partner:UNTCAS collection:UNTSW access_rights:public

Metal Effect on the Supramolecular Structure, Photophysics, and Acid-Base Character of Trinuclear Pyrazolato Coinage Metal Complexes Omary, Mohammad A. Rawashdeh-Omary, Manal A. Gonser, M.W. Alexander Elbjeirami, Oussama Grimes, Thomas V. Cundari, Thomas R., 1964- Diyabalanage, Himashinie V.K. Gamage, Chammi S. Palehepitiya Dias, H.V. Rasika metal effects supramolecular structures photophysics metal complexes This article discusses metal complexes. Varying the coinage metal in cyclic trinuclear pyrazolate complexes is found to significantly affect the solid-state packing, photophysics, and acid-base properties. The three isoleptic compounds used in this study are {[3,5-(CF3)2Pz]M}3 with M = Cu, Ag, and Au (i.e., Cu3, Ag3, and Au3, respectively). They form isomorphous crystals and exist as trimers featuring nine-membered M3N6 rings with linear two-coordinate metal sites. On the basis of the M-N distances, the covalent radii of two-coordinate Cuǀ, Agǀ, and Auǀ were estimated as 1.11, 1.34, and 1.25 Å, respectively. The cyclic {[3,5-(CF3)2Pz]M}3 complexes pack as infinite chains of trimers with a greater number of pairwise intertrimer M···M interactions upon proceeding to heavier coinage metals. However, the intertrimer distances are conspicuously short in Ag3 (3.204 Å) versus Au3 (3.885 Å) or Cu3 (3.813 Å) despite the significantly larger covalent radius of Agǀ. Remarkable luminescence properties are found for the three M3 complexes, as manifested by the appearance of multiple unstructured phosphorescence bands whose colors and lifetimes change qualitatively upon varying the coinage metal and temperature. The multiple emissions are assigned to different phosphorescent excimeric states that exhibit enhanced M···M bonding relative to the ground state. The startling luminescence thermochromic changes in crystals of each compound are related to relaxation between the different phosphorescent excimers. The trend in the lowest energy phosphorescence band follows the relative triplet energy of the three Mǀ atomic ions. DFT calculations indicate that {[3,5-(R)2Pz]M}3 trimers with R = H or Me are bases with the relative basicity order Ag « Cu < Au while fluorination (R = CF3) renders even the Au trimer acidic. These predictions were substantiated experimentally by the isolation of the first acid-base adduct, {[Au3]2:toluene}∞, in which a trinuclear Auǀ complex acts as an acid. American Chemical Society 2005-09-10 Article 11 p. Text doi: 10.1021/ic0508730 http://digital.library.unt.edu/ark:/67531/metadc77126/ ark: ark:/67531/metadc77126 Inorganic Chemistry, 2005, Washington, DC: American Chemical Society, pp. 8200-8210 English Public

info:ark/67531/metadc77144 2013-04-17T10:38:08Z partner:UNTCAS collection:UNTSW access_rights:public

Low Coordinate, Monomeric Molybdenum and Tungsten(III) Complexes: Structure, Reactivity and Calculational Studies of (silox)3Mo and (silox)3ML (M = Mo, W; L = PMe3, CO; silox = tBu3SiO) Kuiper, David S. Wolczanski, Peter T. Lobkovsky, Emil B. Cundari, Thomas R., 1964- monomeric molybdenum tungsten complexes mononuclear species This article discusses low coordinate, monomeric molybdenum and tungsten(III) complexes. Treatment of (silox)3MCI (M = Mo, 1-CI; W, 2-CI; silox = tBu3SiO) with PMe3 and Na/Hg led to formation of monomeric, d3 phosphine adducts, (silox)3MPMe3 (M = Mo, 1-PMe3; W, 2-PMe3) via (silox)3CIMPMe3 (M = Mo, 1-CIPMe3; W, 2-CIPMe3). Structural studies show 1-PMe3 and 2-PMe3 to be highly distorted; calculations on full chemical models corroborate experimentally determined S = ½ ground states and their structural features. The compounds contain a bent M-P bond that is characteristic of significant σ/π-mixing. PMe3 may be thermally removed from 1-PMe3 in vacuo to produce 4A2´ (silox)3Mo (1), which was derivatized with CO, NO, and 1/4 P4 to form (silox)3Mo (1-CO), (silox)3MoNo (1-NO), and (silox)3MoP (1-P), respectively. Calculations revealed (silox)3W (2´) to have as S = ½ ground state, which may render it too reactive to be isolated. Treatment of 2-PMe3 with CO, NO, and 1/4 P4 formed (silox)3WCO (2-CO), (silox)3WNO (2-NO), and (silox)3WP (2-P), respectively. 2-CO and 2-NO are more conveniently prepared from Na/Hg reductions of 2-CI in the presence of CO and NO, respectively. Calculations reveal subtle effects of ndz2/(n+1)s mixing in differentiating the chemistry of Mo and W and in rationalizing the generation of mononuclear species. American Chemical Society 2008-09-06 Article 13 p. Text doi: 10.1021/ja802706u http://digital.library.unt.edu/ark:/67531/metadc77144/ ark: ark:/67531/metadc77144 Journal of the American Chemical Society, 2008, Washington DC: American Chemical Society, pp. 12931-12943 English Public

info:ark/67531/metadc77137 2013-04-17T10:54:21Z partner:UNTCAS collection:UNTSW access_rights:public

Studies of Low-Coordinate Iron Dinitrogen Complexes Smith, Jeremy M. Sadique, Azwana R. Cundari, Thomas R., 1964- Rodgers, Kenton R. Gudrun Lukat-Rodgers Lachicotte, Rene J. Flaschenriem, Christine J. Vela, Javier Holland, Patrick L. low-coordinate iron dinitrogen complexes This article discusses low-coordinate iron dinitrogen complexes. Understanding the interaction of N₂ with iron is relevant to the iron catalyst used in the Haber process and to possible roles of the FeMoco active site of nitrogenase. The work reported here uses synthetic compounds to evaluate the extent of NN weakening in low-coordinate iron complexes with an FeNNFe core. The steric effects, oxidation level, presence of alkali metals, and coordination number of the iron atoms are varied, to gain insight into the factors that weaken the NN bond. Diiron complexes with a bridging N2 ligand, LRFeNNFeLR (LR = β-diketiminate; R = Me, tBu), result from reduction of [LRFeCl]n under a dinitrogen atmosphere, and an iron(I) precursor of an N2 complex can be observed. X-ray crystallographic and resonance Raman data for LRFeNNFeLR show a reduction in the N-N bond order, and calculations (density functional and multireference) indicate that the bond weakening arises from cooperative back-bonding into the N2 π* orbitals. Increasing the coordination number of iron from three to four through binding of pyridines gives compounds with comparable N-N weakening, and both are substantially weakened relative to five-coordinate iron-N2 complexes, even those with a lower oxidation state. Treatment of LRFeNNFeLR with KC8 gives K2LRFeNNFeLR, and calculations indicate that reduction of the iron and alkali metal coordination cooperatively weaken the N-N bond. The complexes LRFeNNFeLR react as iron(I) fragments, losing N2 to yield iron(I) phosphine, CO, and benzene complexes. They also reduce ketones and aldehydes to give the products of pinacol coupling. The K2LRFeNNFeLR compounds can be alkylated at iron, with loss of N2. American Chemical Society 2005-12-31 Article 14 p. Text doi: 10.1021/ja052707x http://digital.library.unt.edu/ark:/67531/metadc77137/ ark: ark:/67531/metadc77137 Journal of the American Chemical Society, 2005, Washington DC: American Chemical Society, pp. 756-769 English Public

info:ark/67531/metadc77127 2013-04-17T10:55:13Z partner:UNTCAS collection:UNTSW access_rights:public

A T-Shaped Three-Coordinate Nickel(l) Carbonyl Complex and the Geometric Preferences of Three-Coordinate d9 Complexes Eckert, Nathan A. Dinescu, Adriana Cundari, Thomas R., 1964- Holland, Patrick L. three-coordinate complexes transition metals This article discusses a T-shaped three-coordinate nickel(l) carbonyl complex and the geometric preferences of three-coordinate d9 complexes. A three-coordinate diketiminate-nickel(l) complex with a carbonyl ligand has been characterized using EPR and IR spectroscopies and X-ray crystallography. The T geometry (bending from the sterically favored C2v structure) contrasts with that of isosteric d9 copper(ll) complexes. DFT calculations on a truncated model reproduce experimental geometries, implying that the geometric differences are electronic in nature. Analysis of the charge distribution in the complexes shows that the geometry of the three-coordinate d9 complexes is affected by differential charge donation of the ligands to the metal center. American Chemical Society 2005-10-05 Article 3 p. Text doi: 10.1021/ic0510213 http://digital.library.unt.edu/ark:/67531/metadc77127/ ark: ark:/67531/metadc77127 Inorganic Chemistry, 2005, Washington DC: American Chemical Society, pp. 7702-7704 English Public

info:ark/67531/metadc77131 2013-04-12T15:01:19Z partner:UNTCAS collection:UNTSW access_rights:public

Four-Coordinate Mo(II) as (silox)2Mo(PMe3)2 and Its W(IV) Congener (silox)2HW(ɳ2-CH2PMe2) (silox = tBu3SiO) Kuiper, David S. Wolczanski, Peter T. Lobkovsky, Emil B. Cundari, Thomas R., 1964- molybdenum tungsten This article discusses four-coordinate Mo(II). Abstract: The reduction of [(tBu3SiO)2MoCI]2 (22) provided the cyclometalated derivative, (silox)2HMoMo(k-O,C-OSitBu2CMe2CH2)(silox) (3), and alkylation of 22 with MeMgBr afforded [(tBu3SiO)2MoCH3]2 (42). The hydrogenation of 42 was ineffective, but the reduction of 22 under H2 generated [(tBu3SiO)2MoH]2 (52), and the addition of 2-butyne to 3 gave [(silox)2Mo]2 (μ:ɳ2ɳ2-C2Me2) (6), thereby implicating the existence of [(silox)2Mo]2 (12). The addition of (silox)H to Mo(NMe2)4 led to (silox)2Mo(NMe2)2 (7), but further elaboration of the core proved ineffective. The silanolysis of MoCI5 afforded (silox)2MoCI4 (8) and (silox)3 MoCI3 (9) as a mixture from which pure 8 could be isolated, and the addition of THF or PMe3 resulted in derivatives of 9 as (silox)2CI3MoL (L = THF, 10; PMe3, 11). Reductions of 11 and (silox)2WCI4 (15) in the presence of excess PMe3 provided (silox)2CI2MPMe3 (M = Mo, 12; W, 16) or (silox)2HW(ɳ2-CH2PMe2)PMe3 (14). While "(silox)2W(PMe3)2" was unstable with respect to W(IV) as 14, a reduction of 12 led to the stable Mo(II) diphosphine, (silox)2Mo(PMe3)2 (17). X-ray crystal structures of 10 (pseudo-Oh), 12 (square pyramidal), and 14 and 17 (distorted Td) are reported. Calculations address the diamagnetism of 12 and 16, and the distortion of 17 and its stability to cyclometalation in contrast to 14. American Chemical Society 2008-10-21 Article 12 p. Text doi: 10.1021/ic8011958 http://digital.library.unt.edu/ark:/67531/metadc77131/ ark: ark:/67531/metadc77131 Inorganic Chemistry, 2008, Washington DC: American Chemical Society, pp. 10542-10553 English Public

info:ark/67531/metadc77130 2013-04-17T10:48:33Z partner:UNTCAS collection:UNTSW access_rights:public

Molybdenum and Tungsten Structural Differences are Dependent on ndz2/(n + 1)ѕ Mixing: Comparisons of (silox)3MX/R (M = Mo, W; silox = tBu3SiO) Kuiper, David S. Douthwalte, Richard E. Mayoi, Ana-Rita Wolczanski, Peter T. Lobkovsky, Emil B. Cundari, Thomas R., 1964- Lam, Oanh P. Meyer, Karsten transition metals molybdenum tungsten This article discusses molydbenum and tungsten structural differences. Treatment of trans-(Et2O)2MoCI4 with 2 or 3 equiv of Na(silox) (i.e., NaOSitBu3) afforded (silox)3MoCI2 (1-Mo) or (silox)3MoCI (2-Mo). Purification of 2-Mo was accomplished via addition of PMe3 to precipitate (silox)3CIMoPMe3 (2-MoPMe3), followed by thermolysis to remove phosphine. Use of MoCI3(THF)3 with various amounts of Na(silox) produced (silox)2CIMoMoCI(silox)2 (3-Mo). Alkylation of 2-Mo with MeMgBr or EtMgBr afforded (silox)3MoH, which was prepared from 2-Mo and NaBEt3H. Thermolysis of WCI6 with HOSitBu3 afforded (silox)2WCI4 (4-W), and sequential treatment of 4-W with Na/Hg and Na(silox) provided (silox)3WCI2 (1-W, tbp, X-ray), which was alternatively prepared from trans-(Et2S)2WCI4 and 3 equiv of TI(silox). Na/Hg reduction of 1-W generated (silox)3WCI (2-W). Alkylation of 2-W with MeMgBr produced (silox)3WMe (2-WMe), which dehydrogenated to (silox)3WCH (6-W) with ∆ H‡ = 14.9(9) kcal/mol and ∆S‡ = -26(2) eu. Magnetism and structural studies revealed that 2-Mo and 2-MoEt have triplet ground states (GS) and distorted trigonal monopyramid (tmp) and tmp structures, respectively. In contrast, 2-W and 2-WMe possess squashed-Td (distorted square planar) structures, and the former has a singlet GS. Quantum mechanics/ molecular mechanics studies of the S = 0 and S = 1 states are full models of 2-Mo, 2-MoEt, 2-W, and 2WMe corroborate the experimental findings and are consistent with the greater ndz2I(n + 1)s mixing in the third-row transition-metal species being the dominant feature in determining the structural disparity between molybdenum and tungsten. American Chemical Society 2008-07-15 Article 15 p. Text doi: 10.1021/ic800139c http://digital.library.unt.edu/ark:/67531/metadc77130/ ark: ark:/67531/metadc77130 Inorganic Chemistry, 2008, Washington DC: American Chemical Society, pp. 7139-7153 English Public

info:ark/67531/metadc77142 2013-04-17T10:49:56Z partner:UNTCAS collection:UNTSW access_rights:public

Olefin Substitution in (silox)3M(olefin) (silox = tBu3SiO; M = Nb, Ta): The Role of Density of States in Second vs Third Row Transition Metal Reactivity Hirsekorn, Kurt F. Hulley, Elliott B. Wolczanski, Peter T. Cundari, Thomas R., 1964- density states binding energies olefin complexes This article discusses the role of density of states in second vs third row transition metal reactivity. The substitution chemistry of olefin complexes (silox)3M(ole) (silox = tBu3SiO; M = Nb (1-ole), Ta (2-ole); ole = C2H4 (as 13C2H4 or C2D4), C2H3Me, C2H3Et, cis-2-C4H8, iso-C4H8, C2H3Ph, cC5H8, cC6H10, cC7H10 (norbornene)) was investigated. For 1-ole, substitution was dissociative (∆Gǂdiss), and in combination with calculated olefin binding free energies (∆G˚bind), activation free energies for olefin association (∆Gǂassoc) to (silox)3Nb (1) were estimated. For 2-ole, substitution was not observed prior to rearrangement to alkylidenes. Instead, activation free energies for olefin association to (silox)3Ta (2) were measured, and when combined with ∆G˚bind(calcd), estimates of olefin dissociation rates from 2-ole were obtained. Despite stronger binding energies for 1-ole vs 2-ole, the dissociation of olefins from 1-ole is much faster than that from 2-ole. The association of olefins to 1 is also much faster than that to 2. Linear free energy relationships (with respect to ∆G˚bind) characterize olefin dissociation from 1-ole, but not olefin dissociation from 2-ole, and olefin association to 2, but not olefin association to 1. Calculated transition states for olefin dissocation from (HO)3M(C2H4) (M = Nb, 1´-C2H4; Ta, 2´-C2H4) are asymmetric and have orbitals consistent with either singlet or triplet states. The rearrangement of (silox)3Nb(trans-Vy,Ph-cPr) to (silox)3Nb=CHCH=CHCH2CH2Ph (3) is consistent with a diradical intermediate akin to the transtion state for substitution. The disparity between Nb and Ta in olefin substitution chemistry is rationalized on the basis of a greater density of states (DOS) for the products (i.e., (silox)3M + ole) where M = Nb, leading to intersystem crossing events that facilitate dissociation. At the crux of the DOS difference is the greater 5dz2/6s mixing for Ta vs the 4dz2/5s mixing of Nb. This rationalization is generalized to explain the nominally swifter reactivities of 4d vs 5d elements. American Chemical Society 2008-01-08 Article Text doi: 10.1021/ja074972j http://digital.library.unt.edu/ark:/67531/metadc77142/ ark: ark:/67531/metadc77142 Journal of the American Chemical Society, 2008, Washington DC: American Chemical Society, pp. 1183-1196 English Public

info:ark/67531/metadc77147 2013-04-17T10:50:23Z partner:UNTCAS collection:UNTSW access_rights:public

Oxygen Atom Transfer Energetics: Assessment of the Effect of Method and Solvent Dinescu, Adriana Whiteley, Clinton Combs, Rachel R. Cundari, Thomas R., 1964- density functional methods oxygen atom transfer energetics This article discusses oxygen atom transfer energetics. Several density functional methods, the semiempirical methods AM1 and PM3, Hartree-Fock, and Gaussian3 theories were applied to compute the oxygen atom transfer enthalpies for 14 X/XO couples (inorganic and organic systems, charged and neutral species, light and heavy main group element containing molecules). The calculated reaction enthalpies were compared to available experimental data. The G3 method alone was found to perform within the experimental error, while the popular B3LYP and BLYP functionals provided inadequate results. Solvent effects were estimated for 19 neutral and anionic X/XO couples by using the conductor-like polarizable continuum model and several cavity models coupled with the B3LYP/6-31++G-(2d,2p) level of theory. Surprisingly, the magnitude of the aqueous solvent correction was found to vary significantly for different solute cavity models, occasionally giving larger errors than the gas-phase calculation. American Chemical Society 2006-02-23 Article 4 p. Text doi: 10.1021/jp055060b http://digital.library.unt.edu/ark:/67531/metadc77147/ ark: ark:/67531/metadc77147 Journal of Physical Chemistry A, 2006, Washington DC: American Chemical Society, pp. 4053-4056 English Public

info:ark/67531/metadc77135 2013-04-17T10:51:44Z partner:UNTCAS collection:UNTSW access_rights:public

Thermodynamics, Kinetics, and Mechanism of (silox)3M(olefin) to (silox)3M(alkylidene) Rearrangements (silox = tBu3SiO; M = Nb, Ta) Hirsekorn, Kurt F. Veige, Adam S. Marshak, Michael P. Koldobskaya, Yelena Wolczanski, Peter T. Cundari, Thomas R., 1964- Lobkovsky, Emil B. thermodynamics kinetics mechanisms complexes This article discusses thermodynamics, kinetics, and mechanisms. Olefin complexes (silox)3M(ole) (silox = tBu3SiO; M = Nb (1-ole), Ta (2-ole); ole = C2H4, C2H3Me, C2H3Et, C2H3C6H4-p-X (X = OMe, H, CF₃), C₂H3tBu, cC5H8, cC6H10, cC7H10 (norbornene)) rearrange to alkylidene isomers (silox)3M(alk) (M = Nb (1=alk), Ta (2=alk); alk = CHMe, CHEt, CHnPr, CHCH2C6H4-p-X (X = OMe, H, CF3 (Ta only)), CHCH2tBu, cC5H8, cC6H10, cC7H10 (norbornylidene)). Kinetics and labeling experiments suggest that the rearrangement proceeds via a ơ-abstraction on a silox CH bond by the β-olefin carbon to give (silox)2RM(κ2-O,C-OSitBu2CMe2CH2) (M = Nb (4-R), Ta (6-R); R = Me, Et, nPr, nBu, CH2-CH2C6H4-p-X (X = OMe, H, CF3 (Ta only)), CH2CH2tBu, cC5H9, cC6H11, cC7H11 (norbornyl)). A subsequent α-abstraction by the cylometalated "arm" of the intermediate on an α-CH bond of R generates the alkylidene 1=alk or 2=alk. Equilibrations of 1-ole with ole' to give 1-ole' and ole, and relevant calculations on 1-ole and 2-ole, permit interpretation of all relative ground and transition state energies for the complexes of either metal. American Chemical Society 2005-03-10 Article 22 p. Text doi: 10.1021/ja046180k http://digital.library.unt.edu/ark:/67531/metadc77135/ ark: ark:/67531/metadc77135 Journal of the American Chemical Society, 2005, Washington DC: American Chemical Society, pp. 4809-4830 English Public

info:ark/67531/metadc77146 2013-04-17T10:45:56Z partner:UNTCAS collection:UNTSW access_rights:public

Unusual Electronic Features and Reactivity of the Dipyridylazaallyl Ligand: Characterizations of (smif)2M [M = Fe, Co, Co+, Ni; smif = {(2-py)CH}2N] and [(TMS)2NFe]2(smif)2 Frazier, Brenda A. Wolczanski, Peter T. Lobkovsky, Emil B. Cundari, Thomas R., 1964- dipyridylazaallyl ligands density functional theory electronic features This article discusses unusual electronic features and reactivity of the dipyridylazaallyl ligand. Application of the dipyridylazaallyl ligand (2-py)CHNCH(2-py) (smif) to a series of first-row transition metals afforded (smif)2Mn [n = 0, M = Fe (1), Co (2), Ni (3); n = +1, M = Co (2+)] and {(TMS)2NFe}2(smif)2 (42) via metathetical procedures. The Mössbauer spectrum of 1 (S = 0) and TDDFT calculations, including a UV-vis spectral simulation, reveal it to be covalent, strong-field system with ∆ₒ estimated as ~18 000 cm-1 and B ≈ 470 cm-1. (smif)2Ni (3) has S = 1 (SQUID), and calculations show that the unpaired spins reside in the dz2 and dх2-y2 orbitals. X-ray structural parameters suggest that low-spin d6 1 and 2+ are relatively symmetric D2d species, but 2 and 3 manifest a distortion in which one smif is canted in the plane perpendicular to the other. (smif)FeN(TMS)2 (4) is principally monomeric in solution, but reversibly dimerizes (Keq ≈ 10-4 M-1) via C-C bond formation in the azaallyl backbone to crystallize as {(TMS)2NFe}2(smif)2 (42). The azaallyl compounds possess extraordinary UV-vis absorptivities (Ɛ ≈ 18000-52000) at 580 ± 15nm and 406(25)nm that have been identified as intraligand bands with Cnb→smif π* character. American Chemical Society 2009-02-19 Article 2 p. Text doi: 10.1021/ja8089747 http://digital.library.unt.edu/ark:/67531/metadc77146/ ark: ark:/67531/metadc77146 Journal of the American Chemical Society, 2009, Washington DC: American Chemical Society, pp. 3428-3429 English Public

info:ark/67531/metadc77139 2013-04-26T15:37:52Z partner:UNTCAS collection:UNTSW access_rights:public

Hydrogen-Deuerium Exchange between TpRu(PMe3)(L)X (L = PMe3 and X = OH, OPh, Me, Ph, or NHPh; L = NCMe and X = Ph) and Deuterated Arene Solvents: Evidence for Metal-Mediated Processes Feng, Yuee Lail, Marty Foley, Nicholas A. Gunnoe, T. Brent Barakat, Khaldoon A. Cundari, Thomas R., 1964- Petersen, Jeffrey L. metal mediated processes ligands This article discusses evidence for metal-mediated processes. Abstract: At elevated temperatures (90-130 ˚C), complexes of the type TpRu(PMe3)2X (X = OH, OPh, Me, Ph, or NHPh; Tp = hydridotris(pyrazolyl)borate) undergo regioselective hydrogen-deuterium (H/D) exchange with deuterated arenes. For X = OH or NHPh, H/D exchange occurs at hydroxide and anilido ligands, respectively. For X = OH, OPh, Me, Ph, or NHPh, isotopic exchange occurs at the Tp 4-positions with only minimal deuterium incorporation at the Tp 3- or 5-positions or PMe3 ligands. For TpRu(PMe3)-(NCMe)Ph, the H/D exchange occurs at 60 ˚C at all three Tp positions and the phenyl ring. TpRu(PMe3)2-CI, TpRu(PMe3)2OTf(OTf = trifluoromethanesulfonate), and TpRu(PMe3)2SH do not initiate H/D exchange in C6D6 after extended periods of time at elevated temperatures. Mechanistic studies indicate that the likely pathway for the H/D exchange involves ligand dissociation (PMe3 or NCMe), Ru-mediated activation of an aromatic C-D bond, and deuteration of basic nondative ligand (hydroxide or anilido) or Tp positions via net D+ transfer. American Chemical Society 2006-05-24 Article 13 p. Text doi: 10.1021/ja0615775 http://digital.library.unt.edu/ark:/67531/metadc77139/ ark: ark:/67531/metadc77139 Journal of the American Chemical Society, 2006, Washington DC: American Chemical Society, pp. 7982-7994 English Public

info:ark/67531/metadc77111 2013-04-25T14:00:36Z partner:UNTCAS collection:UNTSW access_rights:public

GSV: a web-based genome synteny viewer for customized data Revanna, Kashi V. Chiu, Chi-Chen Bierschank, Ezekiel Dong, Qunfeng genomics genome synteny viewers GSV This article discusses GSV, a web-based genome synteny viewer for customized data. Abstract: Background: The analysis of genome synteny is a common practice in comparative genomics. With the advent of DNA sequencing technologies, individual biologists can rapidly produce their genomic sequences of interest. Although web-based synteny visualization tools are convenient for biologists to use, none of the existing ones allow biologists to upload their own data for analysis. Results: The authors have developed the web-based Genome Synteny Viewer (GSV) that allows users to upload two data files for synteny visualization, the mandatory synteny file for specifying genomic positions of conserved regions and the optional genome annotation file. GSV presents two selected genomes in a single integrated view while still retaining the browsing flexibility necessary for exploring individual genomes. Users can browse and filter for genomic regions of interest, change the color or shape of each annotation track as well as re-order, hide or show the tracks dynamically. Additional features include downloadable images, immediate email notification and tracking of usage history. The entire GSV package is also light-weighted which enables easy local installation. Conclusions: GSV provides a unique option for biologists to analyze genome synteny by uploading their own data set to a web-based comparative genome browser. A web server hosting GSV is provided at http://cas.bioinfo.cas.unt.edu/gsv, and the software is also freely available for local installations. BioMed Central Ltd. 2011 Article 4 p. Text doi: 10.1186/1471-2105-12-316 http://digital.library.unt.edu/ark:/67531/metadc77111/ ark: ark:/67531/metadc77111 BMC Informatics, 2011, London: BioMed Central Ltd. English Public Attribution

info:ark/67531/metadc77134 2013-05-14T14:36:26Z partner:UNTCAS collection:UNTSW access_rights:public

Jahn - Teller Distortion in the Phosphorescent Excited State of Three-Coordinate Au(I) Phosphine Complexes Barakat, Khaldoon A. Cundari, Thomas R., 1964- Omary, Mohammad A. phosphine complexes transition metal complexes This article discusses three-coordinate Au(I) phosphine complexes. Abstract: DFT calculations were used to optimize the phosphorescent excited state of three-coordinate [Au(PR3)3]+ complexes. The results indicate that the complexes rearrange from their singlet ground-state trigonal planar geometry to a T-shape in the lowest triplet luminescent excited state. The optimized structure of the exciton contradicts the structure predicted based on the AuP bonding properties of the ground-state HOMO and LUMO. The rearrangement to T-shape is a Jahn-Teller distortion because an electron is taken from the degenerate e' (5dxy, 5dx2-y2) orbital upon photoexcitation of the ground-state D3h complex. The calculated UV absorption and visible emission energies are consistent with the experimental data and explain the large Stokes' shifts while such correlations are not possible in optimized models that constrained the exciton to the ground-state trigonal geometry. American Chemical Society 2003-11-04 Article 2 p. Text doi: 10.1021/ja036508u http://digital.library.unt.edu/ark:/67531/metadc77134/ ark: ark:/67531/metadc77134 Journal of the American Chemical Society, 2003, Washington DC: American Chemical Society, pp. 14228-14229 English Public

info:ark/67531/metadc77174 2013-03-19T14:40:40Z partner:UNTCAS collection:UNTSW access_rights:public

Computational s-Block Thermochemistry with the Correlation Consistent Composite Approach DeYonker, Nathan J. Ho, Dustin S. Wilson, Angela K. Cundari, Thomas R., 1964- thermodynamics earth metal oxides earth metal hydroxides alkali alkaline This article discusses computational s-block thermochemistry with the correlation consistent composite approach. Abstract: The correlation consistent composite approach (ccCA) is a model chemistry that has been shown to accurately compute gas-phase enthalpies of formation for alkali and alkaline earth metal oxides and hydroxides (Ho, D.S.; DeYonker, N.J.; Wilson, A.K.; Cundari, T.R., J. Phys. Chem. A 2006, 110, 9767). The ccCA results contrast to more widely used model chemistries where calculated enthalpies of formation for such species can be in error by up to 90 kcal molˉ¹. In this study, the authors have applied ccCA to a more general set of 42 s-block molecules and compared the ccCA ∆Hf values to values obtained using the G3 and G3B model chemistries. Included in this training set are water complexes such as Na(H₂O)n⁺ where n = 1 - 4, dimers and trimers of ionic compounds such as (LiCl)₂ and (LiCl)₃, and the largest ccCA computation to date: Be-(acac)₂, BeC₁₀H₁₄O₄. Problems with the G3 model chemistries seem to be isolated to metal-oxygen bonded systems and Be-containing systems, as G3 and G3B still perform quite well with a 2.7 and 2.6 kcal mol⁻¹ mean absolute deviation (MAD), respectively, for gas-phase enthalpies of formation. The MAD of the ccCA is only 2.2 kcal mol⁻¹ for enthalpies of formation (∆ Hf) for all compounds studied herein. While this MAD is roughly double that found for a ccCA study of >350 main group (i.e., p-block) compounds, it is commensurate with typical experimental uncertainties for s-block complexes. Some molecules where G3/G3B and ccCA computed ∆Hf values deviate significantly from experiment, such as (LiCl)₃, NaCN, and MgF, are inviting candidates for new experimental and high-level theoretical studies. American Chemical Society 2007-10-03 Article 5 p. Text doi: 10.1021/jp0736241 http://digital.library.unt.edu/ark:/67531/metadc77174/ ark: ark:/67531/metadc77174 Journal of Physical Chemistry A, 2007, Washington DC: American Chemical Society English Public

info:ark/67531/metadc77164 2013-03-15T13:59:21Z partner:UNTCAS collection:UNTSW access_rights:public

Canonical and noncanonical equilibrium distribution Annunziato, Mario Grigolini, Paolo West, Bruce J. equilibrium distributions canonical noncanonical Lévy distribution This article discusses canonical and noncanonical equilibrium distribution. Abstract: We address the problem of the dynamical foundation of noncanonical equilibrium. We consider, as a source of divergence from ordinary statistical mechanics, the breakdown of the condition of time scale separation between microscopic and macroscopic dynamics. We show that this breakdown has the effect of producing a significant deviation from the canonical prescription. We also show that, while the canonical equilibrium can be reached with no apparent dependence on dynamics, the specific form of noncanonical equilibrium is, in fact, determined by dynamics. We consider the special case where the thermal reservoir driving the system of interest to equilibrium is a generator of intermittent fluctuations. We assess the form of the noncanonical equilibrium reached by the system in this case. Using both theoretical and numerical arguments we demonstrate that Lévy statistics are the best description of the dynamics and that the Lévy distribution is the correct basin of attraction. We show that the correct path to noncanonical equilibrium by means of strictly thermodynamic arguments has not yet been found, and that further research has to be done to establish a connection between dynamics and thermodynamics. American Physical Society 2001 Article 13 p. Text doi: 10.1103/PhysRevE.64.011107 http://digital.library.unt.edu/ark:/67531/metadc77164/ ark: ark:/67531/metadc77164 Physical Review E, 2001, College Park: American Physical Society English Public

info:ark/67531/metadc77188 2013-03-18T13:33:43Z partner:UNTCAS collection:UNTSW access_rights:public

Catalytic Synthesis of Arylisocyanates from Nitroaromatics. A Computational Study Kazi, Abul B. Cundari, Thomas R., 1964- Baba, Eduard DeYonker, Nathan J. Dinescu, Adriana Spaine, Lloyd catalytic synthesis nitroaromatics copper-catalyzed phenylisocyanate synthesis This article discusses catalytic synthesis of arylisocyanates from nitroaromatics. Abstract: Several conclusions of interest have emerged from a computational study of copper-catalyzed phenylisocyanate synthesis from nitrobenzene and carbon monoxide. Nitrobenzene complexes coordinate in a κ1-N fashion. With regard to thermodynamics, differences were observed for neutral (amidate, amidinate, β-diketiminate) versus cationic (diimine, NHC) complexes, although discernible trends were less evident for calculated kinetic barriers. The deoxygenation of the nitroso oxygen of the nitrosobenzene complex to form a copper-nitrene intermediate is postulated to be the rate-determining step. For the mechanism assumed in eqs 2 through 5, each step is exothermic. These individual steps are also calculated to possess reasonable kinetic barriers. Hence, copper-based complexes deserve consideration as potential catalysts for the phosgene-free synthesis of arylisocyanates from nitroaromatics. American Chemical Society 2007-01-10 Article 5 p. Text doi: 10.1021/om060762o http://digital.library.unt.edu/ark:/67531/metadc77188/ ark: ark:/67531/metadc77188 Organometallics, 2007, Washington DC: American Chemical Society, pp. 910-914 English Public

info:ark/67531/metadc77179 2013-03-20T11:45:54Z partner:UNTCAS collection:UNTSW access_rights:public

Conversions of Ruthenium (III) Alkyl Complexes to Ruthenium (II) through Ru-Calkyl Bond Homolysis Lail, Marty Gunnoe, T. Brent Barakat, Khaldoon A. Cundari, Thomas R., 1964- single-electron oxidation ruthenium bond homolysis complexes This article discusses conversions of Ruthenium(III) alkyl complexes. Abstract: Single-electron oxidation of the Ru(II) complexes TpRu(L)(L')(R) (L = CO, L' = NCMe, and R = CH3 or CH2CH2Ph; L = L' = PMe3 and R = CH3) with AgOTf leads to alkyl elimination reactions that produce TpRu(L)(L')(OTf) and organic products that likely result from Ru-Calkyl bond homolysis. Density functional calculations on TpRu(CO)(NCMe)(Me) and its Ru(III) cation indicate that the Ru-CH3 homolytic bond dissocation enthalpy is substantially reduced (48.6 to 23.2 kcal/mol) upon oxidation. American Chemical Society 2005-02-12 Article 5 p. Text doi: 10.1021/om049145v http://digital.library.unt.edu/ark:/67531/metadc77179/ ark: ark:/67531/metadc77179 Organometallics, 2005, Washington DC: American Chemical Society, pp. 1301-1305 English Public

info:ark/67531/metadc77162 2013-03-12T17:30:39Z partner:UNTCAS collection:UNTSW access_rights:public

Anomalous diffusion associated with nonlinear fractional derivative Fokker-Planck-like equation: Exact time-dependent solutions Bologna, Mauro Tsallis, Constantino Grigolini, Paolo anomalous diffusion fractional derivatives This article discusses anomalous diffusion associated with nonlinear fractional derivative Fokker-Planck-like equation. Abstract: We consider the d=1 nonlinear Fokker-Planck-like equation with fractional derivatives (∂/∂t)P(x,t) = D(∂ƴ/∂xƴ)[P(x,t]v. Exact time-dependent solutions are found for v = (2 - y)/(1 + y)(-∞ < y ⩽ 2). By considering the long-distance asymptotic behavior of these solutions, a connection is established, namely, q = (y + 3)/(Y + 1)(0 < y ⩽ 2), with the solutions optimizing the nonextensive entropy characterized by index q. Interestingly enough, this relation coincides with the only already known for Lévy-like superdiffusion (i.e., v = 1 and 0 < y ⩽ 2). Finally, for (y,v) = (2,0) the authors obtain q=5/3, which differs from the value q = 2 corresponding to the y = 2 solutions available in the literature (v < 1 porous medium equation), thus exhibiting nonuniform convergence. American Physical Society 2000-08 Article 6 p. Text doi: 10.1103/PhysRevE.62.2213 http://digital.library.unt.edu/ark:/67531/metadc77162/ ark: ark:/67531/metadc77162 Physical Review E, 2000, College Park: American Physical Society, pp. 2213-2218 English Public

info:ark/67531/metadc77189 2013-03-19T12:44:32Z partner:UNTCAS collection:UNTSW access_rights:public

Combined Experimental and Computational Study of TpRu{P(pyr)3} (NCMe)Me (pyr = N-pyrrolyl): Inter- and Intramolecular Activation of C-H Bonds and the Impact of Sterics on Catalytic Hydroarylation of Olefins Foley, Nicholas A. Lail, Marty Gunnoe, T. Brent Cundari, Thomas R., 1964- Boyle, Paul D. Petersen, Jeffrey L. C-H bonds catalytic hydroarylation olefins This article discusses a combined experimental and computational study of TpRu{P(pyr)3} (NCMe)Me (pyr = N-pyrrolyl). Abstract: Complexes of the type TpRu{P(pyr)3} (L)R {L = PPh3 or NCMe; R = Cl, OTf = trifluoromethanesulfonate), Me, or Ph; Tp = hydridotris(pyrazolyl)borate; pyr = N-pyrrolyl} and TpRu-{κ2-P, C-P(pyr)2(NC4H3)}NCMe. TpRu{P(pyr)3}(NCMe)Ph catalyzes the hydrophenylation of ethylene in benzene to produce ethylene by TpRu{P(pyr)3}(NCMe)Ph suggest that inefficient catalysis is not due to difficulty in the C-H activation of benzene by the active catalyst species, but rather likely arises from the steric bulk of the tris-N-pyrrolyl phosphine ligand, which inhibits coordination of ethylene and thus thwarts c-C bond formation. American Chemical Society 2007-10-04 Article 10 p. Text doi: 10.1021/om700666y http://digital.library.unt.edu/ark:/67531/metadc77189/ ark: ark:/67531/metadc77189 Organometallics, 2007, Washington DC: American Chemical Society, pp. 5507-5516 English Public

info:ark/67531/metadc77173 2013-03-14T15:55:00Z partner:UNTCAS collection:UNTSW access_rights:public

Accurate Enthalpies of Formation of Alkali and Alkaline Earth Metal Oxides and Hydroxides: Assessment of the Correlation Consistent Composite Approach (ccCA) Ho, Dustin S. DeYonker, Nathan J. Cundari, Thomas R., 1964- Wilson, Angela K. alkali alkaline earth metal oxides correlation consistent composite approach ccCA This article discusses accurate enthalpies of formation of alkali and alkaline earth metal oxides and hydroxides. Abstract: Computing the enthalpies of formation for alkali metal and alkaline earth metal oxides (MₓO) and hydroxides [M(OH)n] using the Gaussian-n (Gn) and Weismann-n (Wn) ab initio model chemistries is difficult due to an improper treatment of core-valence electron correlation effects. Using a new model chemistry called the correlation consistent Composite Approach (ccCA), enthalpies of formation were determined for eight different alkali/alkaline earth metal oxides and hydroxides. Unlike the Gn and Wn model chemistries, which must be modified to properly account for core-valence electron correlation, the standard implementations of the ccCA provide acceptable results, and all enthalpies of formation obtained with the ccCA are within the accepted range of recommended values. American Chemical Society 2006-07-12 Article 4 p. Text doi: 10.1021/jp062624i http://digital.library.unt.edu/ark:/67531/metadc77173/ ark: ark:/67531/metadc77173 Journal of Physical Chemistry A, 2006, Washington DC: American Chemical Society, pp. 9767-9770 English Public

info:ark/67531/metadc77190 2013-03-14T15:57:33Z partner:UNTCAS collection:UNTSW access_rights:public

Aromatic C-H Activation and Catalytic Hydrophenylation of Ethylene by TpRu{P(OCH2)3CEt} (NCMe)Ph Foley, Nicholas A. Ke, Zhuofeng Gunnoe, T. Brent Cundari, Thomas R., 1964- Petersen, Jeffrey L. C-H activations catalytic hydrophenylation benzene This article discusses aromatic C-H activation and catalytic hydrophenylation of ethylene by TpRu{P(OCH2)3CEt} (NCMe)Ph. Abstract: The complexes TpRu{P(OCH2)3CEt}(L)R {L = PPh3 or NCMe; R = Cl, OTf (OTf = trifluoromethane-sulfonate), or Ph; Tp = hydridotris(pyrazolyl)borate} and TpRu{P(OCH2)3CEt} (ɳ3-C3H4Me) were synthesized and isolated. TpRu{P(OCH2)3CEt} (NCMe)Ph was found to initiate C-H activation of benzene and to catalyze the hydrophenylation of ethylene to produce ethylbenzene. Ethylene C-H activation to ultimately produce TpRu{P(OCH2)3CEt} (ɳ3-C3H4Me) kinetically competes with the catalytic hydrophenylation of ethylene. Computational studies were undertaken on reactions in the proposed catalytic ethylene hydrophenylation cycle as well as key side reactions. American Chemical Society 2008-06-05 Article 11 p. Text doi: 10.1021/om800275b http://digital.library.unt.edu/ark:/67531/metadc77190/ ark: ark:/67531/metadc77190 Organometallics, 2008, Washington DC: American Chemical Society, pp. 3007-3017 English Public

info:ark/67531/metadc77191 2013-03-14T15:57:47Z partner:UNTCAS collection:UNTSW access_rights:public

Arylpalladium Phosphonate Complexes as Reactive Intermediates in Phosphorus-Carbon Bond Forming Reactions Kohler, Mark C. Grimes, Thomas V. Wang, Xiaoping Cundari, Thomas R., 1964- Stockland, Robert A., Jr. phosphorus-carbon bonds transition metal complexes diphosphine ligands This article discusses arylpalladium phosphonate complexes as reactive intermediates in phosphorus-carbon bond forming reactions. Abstract: Phosphorus-carbon bond formation from discrete transition metal complexes have been investigated through a combination of synthetic, spectroscopic, crystallographic, and computational methods. Reactive intermediates of the type (diphosphine)Pd(aryl)P(O)(OEt)2) have been prepared, characterized, and studied as possible intermediates in metal-mediated coupling reactions. Several of the reactive intermediates were characterized crystallographically, and a discussion of the solid state structures is presented. In contrast to other carbon-heteroelement bond forming reactions, palladium complexes containing electron-donating substituents on the aromatic fragment exhibited faster rates of reductive elimination. Large bit angle diphosphine ligands induced rapid rates of elimination, while bipyridine and small bite angle diphosphine ligands resulted in much slower rates of elimination. An investigation of the effect of typical impurities on the elimination reaction was carried out. While excess diphosphine, pyridine, and acetonitrile had little effect on the observed rate, the addition of water slowed the phosphorus-carbon bond forming reaction. Coordination of water to the complex was observed spectroscopically and crystallographically. Computational studies were utilized to probe the reaction pathways for P-C bond formation via Pd catalysis. American Chemical Society 2009-01-21 Article 9 p. Text doi: 10.1021/om800906m http://digital.library.unt.edu/ark:/67531/metadc77191/ ark: ark:/67531/metadc77191 Organometallics, 2009, Washington DC: American Chemical Society, pp. 1193-1201 English Public

info:ark/67531/metadc77166 2013-03-14T13:53:00Z partner:UNTCAS collection:UNTSW access_rights:public

Bianucci, Mannella, and Grigolini Reply Bianucci, Marco Mannella, Riccardo Grigolini, Paolo linear response theories LRT equilibrium This article is a reply to a comment by Massimo Falcioni and Angelo Vulpiani. In a previous letter, the authors have discussed the linear response theory (LRT) and shown that the breakdown of this theory occurring at intermediate times, observed in an earlier paper [2] as well as in [1], disappears upon an increase of the number of degrees of freedom. In a comment to [1] Falcioni and Vulpiani [3] claim that this breakdown is rather a consequence of the lack of mixing: according to them, regardless of the number of degrees of freedom, mixing is the key ingredient behind the LRT. American Physical Society 1997-08-18 Article 1 p. Text doi: 10.1103/PhysRevLett.79.1419 http://digital.library.unt.edu/ark:/67531/metadc77166/ ark: ark:/67531/metadc77166 Physical Review Letters, 1997, College Park: American Physical Society, pp. 1419 English Public

info:ark/67531/metadc77192 2013-03-18T17:47:55Z partner:UNTCAS collection:UNTSW access_rights:public

Coinage Metal-Ethylene Complexes Supported by Tris(pyrazolyl)borates: A Computational Study Kazi, Abul B. Dias, H. V. Rasika Tekarli, Sammer M. Morello, Glenn R. Cundari, Thomas R., 1964- metal-ethylene complexes metal bonding This article discusses coinage metal-ethylene complexes supported by tris(pyrazolyl)borates. Abstract: Data from computational and experimental sources have been combined to address the bonding and structure of [RB(3-(R1),5-(R2)Pz)3]M(C2H4) complexes, where M = Cu, Ag, Au. A k3 to k2 distortion of the scorpionate ligand was also studied. NMR properties were deemed to be the most useful in assessing the nature of the bonding in these complexes. Using computational recipes, 13C chemical shifts accurately reproduced quantitative experimental values and trends as a function of metal, ligand, and substituent. Au-ethylene complexes are found to be substantially "less π-complex" (T-shaped structure) in their bonding description versus Ag and Cu congeners, although the former are by no means entirely metallacyclopropane in their constitution. Combining the present calculations with prior contributions to coinage metal bonding leads the authors to propose that similarity of molecular structure among a congeneric series of coinage metal complexes reflects a principally ionic coinage metal-ligand bonding regime, while dissimilarity of structure within the series reflects a primarily covalent bonding regime. American Chemical Society 2009-02-18 Article 6 p. Text doi: 10.1021/om8010454 http://digital.library.unt.edu/ark:/67531/metadc77192/ ark: ark:/67531/metadc77192 Organometallics, 2009, Washington DC: American Chemical Society, pp. 1826-1831 English Public

info:ark/67531/metadc77167 2013-04-01T12:50:13Z partner:UNTCAS collection:UNTSW access_rights:public

Dynamic Approach to the Thermodynamics of Superdiffusion Buiatti, Marco, 1972- Grigolini, Paolo Montagnini, Anna thermodynamics Lévy index Brownian motion This article discusses dynamic approach to the thermodynamics of superdiffusion. Abstract: We address the problem of relating thermodynamics to mechanics in the case of microscopic dynamics without a finite time scale. The solution is obtained by expressing the Tsallis entropic index q as a function of the Lévy index α, and using dynamic rather than probabilistic arguments. American Physical Society 1999-04-26 Article 5 p. Text doi: 10.1103/PhysRevLett.82.3383 http://digital.library.unt.edu/ark:/67531/metadc77167/ ark: ark:/67531/metadc77167 Physical Review Letters, 1999, College Park: American Physical Society, pp. 3383-3387 English Public

info:ark/67531/metadc77157 2012-12-06T16:46:35Z partner:UNTCAS collection:UNTSW access_rights:public

Pediatric functional magnetic resonance neuroimaging: tactics for encouraging task compliance Schlund, Michael W. Cataldo, Michael F. Siegle, Greg J. Ladouceur, Cecile D. Silk, Jennifer S. Forbes, Erika E. McFarland, Ashley Iyengar, Satish Dahl, Ronald E. Ryan, Neal D. neuroimaging functional magnetic resonance imaging pediatrics fMRI This article discusses pediatric functional magnetic resonance neuroimaging. Background: Neuroimaging technology has afforded advances in our understanding of normal and pathological brain function and development in children and adolescents. However, noncompliance involving the inability to remain in the magnetic resonance imaging (MRI) scanner to complete tasks is one common and significant problem. Task noncompliance is an especially significant problem in pediatric functional magnetic resonance imaging (fMRI) research because increases in noncompliance produces a greater risk that a study sample will not be representative of the study population. Method: In this preliminary investigation, the authors describe the development and application of an approach for increasing the number of fMRI tasks children complete during neuroimaging. Twenty-eight healthy children ages 9-13 years participated. Generalization of the approach was examined in additional fMRI and event-related potential investigations with children at risk for depression, children with anxiety and children with depression (N = 120). Essential features of the approach include a preference assessment for identifying multiple individualized rewards, increasing reinforcement rates during imaging by pairing tasks with chosen rewards and presenting a visual 'road map' listing tasks, rewards and current progress. Results: Our results showing a higher percentage of fMRI task completion by healthy children provides proof of concept data for the recommended tactics. Additional support was provided by results showing our approach generalized to several additional fMRI and event-related potential investigations and clinical populations. Discussion: The authors propose that some forms of task noncompliance may emerge from less than optimal reward protocols. While the authors' findings may not directly support the effectiveness of the multiple reward compliance protocol increased attention to how rewards are selected and delivered may aid cooperation with completing fMRI tasks. Conclusion: The proposed approach contributes to the pediatric neuroimaging literature by providing a useful way to conceptualize and measure task noncompliance and by providing simple cost effective tactics for improving the effectiveness of common reward-based protocols. BioMed Central 2011 Article 10 p. Text doi: 10.1186/1744-9081-7-10 http://digital.library.unt.edu/ark:/67531/metadc77157/ ark: ark:/67531/metadc77157 Behavioral and Brain Functions, 2011, London: BioMed Central English Public Attribution

info:ark/67531/metadc77156 2012-12-06T13:17:05Z partner:UNTCAS collection:UNTSW access_rights:public

Neural correlates of derived relational responding on tests of stimulus equivalence Schlund, Michael W. Cataldo, Michael F. Hoehn-Saric, Rudolf temporal lobes transitive inference stimulus equivalence This article discusses neural correlates of derived relational responding on tests of stimulus equivalence. Background: An essential component of cognition and language involves the formation of new conditional relations between stimuli based upon prior experiences. Results of investigations on transitive inference (TI) highlight a prominent role for the medial temporal lobe in maintaining associative relations among sequentially arranged stimuli (A > B > C > D > E). In this investigation, medial temporal lobe activity was assessed while subjects completed "Stimulus Equivalence" (SE) tests that required deriving conditional relations among stimuli within a class (A ≡ B ≡ C). Methods: Stimuli consisted of six consonant-vowel-consonant triads divided into two classes (A1, B1, C1; A2, B2, C2). A simultaneous matching-to-sample task and differential reinforcement were employed during pretraining to establish the conditional relations A1:B1 and B1:C1 in class 1 and A2:B2 and B2:C2 in class 2. During functional neuroimaging, recombined stimulus pairs were presented and subjects judged (yes/no) whether stimuli were related. SE tests involved presenting three different types of within-class pairs: Symmetrical (B1 A1; C1 B1; B2 A2; C2 B2), and Transitive (A1 C1; A2 C2) and Equivalence (C1 A1; C2 A2) relations separated by a nodal stimulus. Cross-class 'Foils' consisting of unrelated stimuli (e.g., A1 C2) were also presented. Results: Relative to cross-class Foils, Transitive and Equivalence relations requiring inferential judgements elicited bilateral activation in the anterior hippocampus while Symmetrical relations elicited activation in the parahippocampus. Relative to each derived relation, Foils generally elicited bilateral activation in the parahippocampus, as well as in frontal and parietal lobe regions. Conclusion: Activation observed in the hippocampus to nodal-dependent derived conditional relations (Transitive and Equivalence relations) highlights its involvement in maintaining relational structure and flexible memory expression among stimuli within a class (A ≡ B ≡ C). BioMed Central 2008-02-01 Article 8 p. Text doi: 10.1186/1744-9081-4-6 http://digital.library.unt.edu/ark:/67531/metadc77156/ ark: ark:/67531/metadc77156 Behavioral and Brain Functions, 2008, London: BioMed Central English Public Attribution

info:ark/67531/metadc77172 2013-03-28T14:06:46Z partner:UNTCAS collection:UNTSW access_rights:public

Disproportionation of Gold(II) Complexes. A Density Functional Study of Ligand and Solvent Effects Barakat, Khaldoon A. Cundari, Thomas R., 1964- Rabaâ, Hassan Omary, Mohammad A. gold(II) complexes ligands solvent effects This article discusses disproportionation of gold(II) complexes. Abstract: A computational study of gold(II) disproportionation is presented for the atomic ion as well as complexes with chloride and neutral ligands. The Au²⁺ atomic ion is stable to disproportionation, but the barrier is more than halved to 119 kcal/mol in an aqueous environment vs 283 kcal/mol in the gas phase. For dissociative disproportionation of chloride complexes, the loss of chlorine, either as an atom (∆Gaq = +20 kcal/mol) or as an anion (∆Gaq = +15 kcal/mol) represents the largest calculated barrier. The calculated transition state for associative disproportionation is only 9 kcal/mol above separated Auᴵᴵ complex, a nonpolar solvent is preferred. With the exception of [Au(CO₃]²⁺, disproportionation of AuᴵᴵL₃ complexes to AuᴵL and AuᴵᴵᴵL₃ is exergonic in solution phase for the ligands investigated. The driving force is provided by the very favorable solvation free energy of the trivalent gold complex. The solvation free energy contribution to the reaction (∆Gsolv) is very large for small and polar ligands such as ammonia and water. Furthermore, calculations imply that choosing ligands that would yield neutral species upon disproportionation may provide an effective route to thwart this decomposition pathway for Auᴵᴵ complexes. Likewise, bulkier ligands that yield larger, more weakly solvated complex ions would appear to be desirable. American Chemical Society 2006-07-13 Article 7 p. Text doi: 10.1021/jp062501y http://digital.library.unt.edu/ark:/67531/metadc77172/ ark: ark:/67531/metadc77172 Journal of Physical Chemistry B, 2006, Washington DC: American Chemical Society, pp. 14645-14651 English Public

info:ark/67531/metadc77165 2012-05-10T15:58:24Z partner:UNTCAS collection:UNTSW access_rights:public

Trajectory versus probability density entropy Bologna, Mauro Grigolini, Paolo Karagiorgis, Markos Rosa, Angelo density entropy transport equations In this article, the authors show that the widely accepted conviction that a connection can be established between the probability density entropy and the Kolmogorov-Sinai (KS) entropy is questionable. The authors adopt the definition of density entropy as a functional of a distribution density whose time evolution is determined by a transport equation, conceived as the only prescription to use for the calculation. Although the transport equation is built up for the purpose of affording a picture equivalent to that stemming from a trajectory dynamics, no direct use of trajectory time evolution is allowed, once the transport equation is defined. With this definition in mind the authors prove that the detection of a time regime of increase of the density entropy with a rate identical to the KS entropy is possible only in a limited number of cases. The proposals made by some authors to establish a connection between the two entropies in general, violate the authors' definition of density entropy and imply the concept of trajectory, which is foreign to that of density entropy. American Physical Society 2001 Article 9 p. Text doi: 10.1103/PhysRevE.64.016223 http://digital.library.unt.edu/ark:/67531/metadc77165/ ark: ark:/67531/metadc77165 Physical Review E, 2001, College Park: American Physical Society English Public

info:ark/67531/metadc77169 2012-03-09T14:17:36Z partner:UNTCAS collection:UNTSW access_rights:public

xGDB: open-source computational infrastructure for the integrated evaluation and analysis of genome features Schlueter, Shannon D. Wilkerson, Matthew D. Dong, Qunfeng Brendel, Volker open-source computational infrastructures genomes xGDB eXtensible Genome Data Broker This article discusses xGDB. The eXtensible Genome Data Broker (xGDB) provides a software infrastructure consisting of integrated tools for the storage, display, and analysis of genome features in their genomic context. Common features include gene structure annotations, spliced alignments, mapping of repetitive sequence, and microarray probes, but the software supports inclusion of any property that can be associated with a genomic location. The xGDB distribution and user support utilities are available online at the xGDB project website, http://xgdb.sourceforge.net/. BioMed Central 2006-11-20 Article 11 p. Text http://digital.library.unt.edu/ark:/67531/metadc77169/ ark: ark:/67531/metadc77169 Genome Biology, 2006, London: BioMed Central English Public

info:ark/67531/metadc77163 2012-05-10T15:57:51Z partner:UNTCAS collection:UNTSW access_rights:public

Towards the thermodynamics of localization processes Grigolini, Paolo Pala, Marco G. Palatella, Luigi Roncaglia, Roberto thermodynamics quantum mechanical models In this article, the authors study the entropy time evolution of a quantum mechanical model, which is frequently used as a prototype for Anderson's localization. Recently Latora and Baranger [Phys. Rev. Lett. 82, 520 (1999)] found that there exist three entropy regimes, a transient regime of passage from dynamics to thermodynamics, a linear-in-time regime of entropy increase, that is, a thermodynamic regime of Kolmogorov kind, and a saturation regime. The authors use the nonextensive entropic indicator advocated by Tsallis [J. Stat. Phys. 52, 479 (1988)] with a mobile entropic index q, and the authors find that the adoption of the "magic" value q = Q = 1/2, compared to the traditional entropic index q = 1, reduces the length of the transient regime and makes earlier the emergence of the Kolmogorov regime. The authors adopt a two-site model to explain these properties by means of an analytical treatment and the authors argue that Q = 1/2 might be a typical signature of the occurrence of Anderson localization. American Physical Society 2000-09 Article 8 p. Text doi: 10.1103/PhysRevE.62.3429 http://digital.library.unt.edu/ark:/67531/metadc77163/ ark: ark:/67531/metadc77163 Physical Review E, 2000, College Park: American Physical Society, pp. 3429-3436 English Public

info:ark/67531/metadc77159 2012-03-09T14:17:36Z partner:UNTCAS collection:UNTSW access_rights:public

RICHEST - a web server for richness estimation in biological data Durden, Chris Dong, Qunfeng diversity estimations biological data complex simple populations This article discusses RICHEST, a web server for richness estimation in biological data. Richness is defined as the number of distinct species or classes in a sample or population. Although richness estimation is an important practice, it requires mathematical and computational methods that are challenging to understand and implement. The authors have developed a web server, RICHness ESTimator (RICHEST), which implements three non-parametric statistical methods for richness estimation. Its user-friendly web interface allows users to analyze and compare their data conveniently over the web. Biomedical Informatics Publishing Group 2009-02-27 Article 3 p. Text issn: 0973-2063 http://digital.library.unt.edu/ark:/67531/metadc77159/ ark: ark:/67531/metadc77159 Bioinformation, 2009, India: Biomedical Informatics Publishing Group English Public

info:ark/67531/metadc77180 2013-04-08T16:48:14Z partner:UNTCAS collection:UNTSW access_rights:public

Experimental and Computational Studies of Ruthenium(II)-Catalyzed Addition of Arene C-H Bonds to Olefins Lail, Marty Bell, Christen M. Conner, David Cundari, Thomas R., 1964- Gunnoe, T. Brent Petersen, Jeffrey L. olefins reaction pathways ruthenium This article discusses experimental and computational studies of Ruthenium(II)-Catalyzed addition of arene C-H bonds to olefins. Abstract: Hydroarylation reactions of olefins are catalyzed by the octahedral Ru(II) complex TpRu-(CO)(NCMe)(Ph) (1) (Tp = hydridotris(pyrazolyl)borate). Experimental studies and density functional theory calculations support a reaction pathway that involves initial acetonitrile/olefin ligand exchange and subsequent olefin insertion into the ruthenium-phenyl bond. Metal-mediated C-H activation of arene to form a Ru-aryl bond with release of alkyl arene completes the proposed catalytic cycle. The cyclopentadienyl complex CpRu(PPh3)2(Ph) produces ethylbenzene and styrene from a benzene/ethylene solution at 90 ˚C; however, the transformation is not catalytic. A benzene solution of (PCP)Ru(CO)(Ph) (PCP = 2,6-)CH2Pt-Bu2)2C6H3) and ethylene at 90 ˚C produces styrene in 12% yield without observation of ethylbenzene. Computational studies (DFT) suggest that the C-H activation step does not proceed through the formation of a Ru(IV) oxidative addition intermediate but rather occurs by a concerted pathway. American Chemical Society 2004-09-10 Article 14 p. Text doi: 10.1021/om049404g http://digital.library.unt.edu/ark:/67531/metadc77180/ ark: ark:/67531/metadc77180 Organometallics, 2004, Washington DC: American Chemical Society, pp. 5007-5020 English Public

info:ark/67531/metadc77161 2013-04-11T16:21:12Z partner:UNTCAS collection:UNTSW access_rights:public

Fluctuation-dissipation process without a time scale Annunziato, Mario Grigolini, Paolo Riccardi, Juri dissipation processes diffusion dynamics Lévy distribution This article discusses fluctuation-dissipation process without a time scale. Abstract: We study the influence of a dissipation process on diffusion dynamics triggered by fluctuations with long-range correlations. We make the assumption that the perturbation process involved is of the same kind as those recently studied numerically and theoretically, with a good agreement between theory and numerical treatment. As a result of this assumption the equilibrium distribution departs from the ordinary canonical distribution. The distribution tails are truncated, the distribution border is signaled by sharp peaks, and, in the weak dissipation limit, the central distribution body becomes identical to a truncated Lévy distribution. American Physical Society 2000-05 Article 8 p. Text doi: 10.1103/PhysRevE.61.4801 http://digital.library.unt.edu/ark:/67531/metadc77161/ ark: ark:/67531/metadc77161 Physical Review E, 2000, College Park: American Physical Society, pp. 4801-4808 English Public

info:ark/67531/metadc77168 2013-04-16T13:56:19Z partner:UNTCAS collection:UNTSW access_rights:public

Genome-wide mutagenesis of Zea mays L. using RescueMu transposons Fernandes, John Dong, Qunfeng Schneider, Bret Morrow, Darren J. Nan, Guo-Ling Brendel, Volker Walbot, Virginia maize gene discoveries mutant phenotypic analysis RescueMu This article discusses genome-wide mutagenesis of Zea mays L. using RescueMu transposons. Abstract: Derived from the maize Mu I transposon, RescueMu provides strategies for maize gene discovery and mutant phenotypic analysis. 9.92 Mb of gene-enriched sequences next to RescueMu insertion sites were co-assembled with expressed sequence tags and analyzed. Multiple plasmid recoveries identified probable germinal insertions and screening of RescueMu plasmid libraries identified plants containing probable germinal insertions. Although frequently recovered parental insertions and insertion hotspots reduce the efficiency of gene discovery per plasmid, RescueMu targets a large variety of genes and produces knockout mutants. BioMed Central Ltd. 2004 Article 20 p. Text http://digital.library.unt.edu/ark:/67531/metadc77168/ ark: ark:/67531/metadc77168 Genome Biology, 2004, London: BioMed Central Ltd. English Public

info:ark/67531/metadc77196 2013-04-17T10:41:04Z partner:UNTCAS collection:UNTSW access_rights:public

Performance of the correlation consistent composite approach for transition states: A comparison to G3B theory Grimes, Thomas V. Wilson, Angela K. DeYonker, Nathan J. Cundari, Thomas R., 1964- correlation consistent composite approach ccCA G3B This article discusses performance of the correlation consistent composite approach for transition states. The correlation consistent composite approach (ccCA) was applied to the prediction of reaction barrier heights (i.e., transition state energy relative to reactants and products) for a standard benchmark set of reactions comprised of both hydrogen transfer reactions and nonhydrogen transfer reactions (i.e., heavy-atom transfer, Sn2, and unimolecular reactions). The ccCA method was compared against G3B for the same set of reactions. Error metrics indicate that ccCA achieves "chemical accuracy" with a mean unsigned error (MUE) of 0.89 kcal/mol with respect to the benchmark data for barrier heights; G3B has a mean unsigned error of 1.94 kcal/mol. Further, the greater accuracy of ccCA for predicted reaction barriers is compared to other benchmarked literature methods, including density functional (BB1K, MUE=1.16 kcal/mol) and wavefunction-based [QCISD(T), MUE=1.10 kcal/mol] methods. American Institute of Physics 2007-10-19 Article 8 p. Text doi: 10.1063/1.2790011 http://digital.library.unt.edu/ark:/67531/metadc77196/ ark: ark:/67531/metadc77196 Journal of Chemical Physics 127, 2007, College Park: American Institute of Physics, English Public

info:ark/67531/metadc77185 2013-04-17T10:43:00Z partner:UNTCAS collection:UNTSW access_rights:public

Reactions of a Ru(II) Phenyl Complex with Substrates that Possess C-N or C-O Multiple Bonds: C-C Bond Formation, N-H Bond Cleavage, and Decarbonylation Reactions Lee, John P. Pittard, Karl A. DeYonker, Nathan J. Cundari, Thomas R., 1964- Gunnoe, T. Brent Petersen, Jeffrey L. phenyl complexes substrates multiple bonds This article discusses reactions of a Ru(II) phenyl complex. The Ru(II) phenyl complex TpRu(CO)(NCMe)(Ph) (1) (Tp = hydridotris(pyrazolyl)borate) reacts with carbodiimides to yield amidinate complexes that result from C-C bond formation between the phenyl ligand and the carbodiimide carbon. Complex 1 and N-methylacetamide react to produce benzene and the amidate complex TpRu(CO){N,O-OC(Me)N(Me)} (4). The reaction of complex 1 with C≡N(tBu)}(Ph) (5), and heating a solution of PMe3 and 5 results in the observation of an equilibrium with the product of isonitrile insertion TpRu(CO){C(Ph)=NtBu}(PMe3) (6) (∆H = +9(1) kcal/mol and ∆S = +20(3)eu). The reaction of 1 with aromatic aldehydes at elevated temperatures results in C-H activation and decarbonylation of the aldehyde to produce TpRu(CO)2(Ar) (Ar = phenyl or p-tolyl) and free benzene. DFT calculations have been incorporated to study coordination and insertion reactions of ethylene, methyleneimine, formaldehyde, HC=C=NH, and C=NH into the Ru-Ph bond of the model fragment (Tab)Ru(CO)(Ph) (Tab = tris(azo)borate). In addition, the energetics of Ru-mediated decarbonylation of formaldehyde have been calculated. American Chemical Society 2006-02-08 Article 11 p. Text doi: 10.1021/om050967h http://digital.library.unt.edu/ark:/67531/metadc77185/ ark: ark:/67531/metadc77185 Organometallics, 2006, Washington DC: American Chemical Society, pp. 1500-1510 English Public

info:ark/67531/metadc77182 2013-04-17T10:43:33Z partner:UNTCAS collection:UNTSW access_rights:public

Reactions of TpRu(CO) (NCMe) (Me) (Tp = Hydridotris(pyrazolyl)borate) with Heteroaromatic Substrates: Stoichiometric and Catalytic C-H Activation Pittard, Karl A. Lee, John P. Cundari, Thomas R., 1964- Gunnoe, T. Brent Petersen, Jeffrey L. heteroaromatic substrates C-H activations complexes This article discusses reactions of TpRu(CO)(NCMe)(Me) (Tp = Hydridotris(pyrazolyl)borate) with heteroaromatic substrates. The Ru(II) complex TpRu(CO)(NCMe)(Me) (Tp = hydridotris(pyrazolyl)borate) initiates carbon-hydrogen bond activation at the 2-position of furan and thiophene to produce methane and TpRu(CO)(NCMe)(aryl) (aryl = 2-furyl or 2-thienyl). Solid-state structures have been determined for TpRu(CO)(NCMe)(2-thienyl) and [TpRu(CO)(μ-C,S-thienyl)]2. The complex TpRu(CO)(NCMe)(2-furyl) serves as a catalyst for the formation of 2-ethylfuran from ethylene and furan. DFT calculations of the C-H activation of furan by {(Tab)Ru-(CO)(Me)} (Tab = tris(azo)borate) indicate that the C-H activation sequence does not proceed through a Ru(IV) oxidative addition intermediate. American Chemical Society 2004-10-15 Article 10 p. Text doi: 10.1021/om049508r http://digital.library.unt.edu/ark:/67531/metadc77182/ ark: ark:/67531/metadc77182 Organometallics, 2004, Washington DC: American Chemical Society, pp. 5514-5523 English Public

info:ark/67531/metadc77183 2013-04-17T10:54:47Z partner:UNTCAS collection:UNTSW access_rights:public

Synthesis and Reactivity of a Coordinatively Unsaturated Ruthenium(II) Parent Amido Complex: Studies of X-H Activation (X = H or C) Conner, David Jayaprakash, K. N. Cundari, Thomas R., 1964- Gunnoe, T. Brent ruthenium parent amido complexes ruthenium This article discusses synthesis and reactivity of a coordinatively unsaturated Ruthenium(II) parent amido complex. The five-coordinate parent amido complex (PCP)Ru(CO)(NH2) (2) (PCP = 2,6-(CH2P-tBu2)2C6H3) has been prepared by two independent routes that involve deprotonation of Ru(II) ammine complexes. Complex 2 reacts with phenylacetylene to yield the Ru(II) acetylide complex (PCP)Ru(CO)(C≡CPh) (5) and ammonia. In addition, complex 2 rapidly activates dihydrogen at room temperature to yield ammonia and the previously reported hydride complex (PCP)Ru(CO)(H). The ability of the amido complex 2 to cleave the H-H bond is attributed to the combination of a vacant coordination site for binding/activation of dihydrogen and a basic amido ligand. Complex 2 also undergoes an intramolecular C-H activation of a methyl group on the PCP ligand to yield ammonia and a cyclometalated complex. The reaction of (PCP)Ru(CO)(CI) with MeLi allows the isolation of (PCP)Ru(CO)(Me) (8), and complex 8 undergoes an intramolecular C-H activation analogous to the amido complex 2 to produce methane and the cyclometalated complex. Determination of activation parameters for the intramolecular C-H activation transformations of 2 and 8 reveal identical ∆Hǂ {18(1) kcal/mol} with ∆Sǂ = -23(4) eu and -18(4) eu, respectively. Density functional theory has been applied to the study of intermolecular activation of methane and dihydrogen by (PCP')Ru(CO)(NH2) to yield (PCP')Ru(CO)(NH3)(X) (X = Me or H; PCP' = 2,6-(CH2-PH2)2C6H3). The results indicate that the activation of dihydrogen is both exoergic and exothermic. In contrast, the addition of a C-H bond of methane across the Ru-NH2 bond has been calculated to be endoergic and endothermic. The surprising endoergic nature of the methane C-H activation has been attributed to a large and unfavorable change in Ru-N bond dissociation energy upon conversion from Ru-amido to Ru-ammine. American Chemical Society 2004-04-27 Article 10 p. Text doi: 10.1021/om049836r http://digital.library.unt.edu/ark:/67531/metadc77183/ ark: ark:/67531/metadc77183 Organometallics, 2004, Washington DC: American Chemical Society, pp. 2724-2733 English Public

info:ark/67531/metadc77186 2013-04-17T10:53:31Z partner:UNTCAS collection:UNTSW access_rights:public

Single-Electron Oxidation of Monomeric Copper(I) Alkyl Complexes: Evidence for Reductive Elimination through Biomolecular Formation of Alkanes Goj, Laurel A. Blue, Elizabeth D. Delp, Samuel A. Gunnoe, T. Brent Cundari, Thomas R., 1964- Petersen, Jeffrey L. monomeric copper alkyl complexes biomolecular mechanisms This article discusses single-electron oxidation of monomeric copper(I) alkyl complexes. Monomeric Cu(I) alkyl complexes (NHC)Cu(R) (NHC = N-heterocyclic carbene; R = Me or Et) and (dtbpe)Cu(Me) (dtbpe = 1,2-bis(di-tert-butylphosphino)ethane) have been prepared, isolated, and characterized. Single-electron oxidation of the Cu(I) alkyl complexes upon reaction with AgOTf to form putative Cu(II) intermediates of the type [(L)Cu(R)]+ (L = NHC or dtbpe, R = Me or Et) results in the rapid production of (L)Cu(X) (X = OTf) and R2. Experimental studies suggest that the reductive elimination of R2 from Cu(II) occurs through a nonradical bimolecular mechanism. Computational studies of the Cu-Cmethyl yield bond dissocation enthalpies of [(SIPr)Cu-CH3]n+ (80 kcal/mol for n = 0 {Cu(I)} and 38 kcal/mol for n = 1 {Cu(II)}). American Chemical Society 2006-07-21 Article 8 p. Text doi: 10.1021/om060409i http://digital.library.unt.edu/ark:/67531/metadc77186/ ark: ark:/67531/metadc77186 Organometallics, 2006, Washington DC: American Chemical Society, pp. 4097-4104 English Public

info:ark/67531/metadc77193 2013-04-17T10:53:57Z partner:UNTCAS collection:UNTSW access_rights:public

Six-, Five-, and Four-Coordinate Ruthenium(II) Hydride Complexes Supported by N-Heterocyclic Carbene Ligands: Synthesis, Characterization, Fundamental Reactivity, and Catalytic Hydrogenation of Olefins, Aldehydes, and Ketones Lee, John P. Ke, Zhuofeng Ramírez, Magaly A. Gunnoe, T. Brent Cundari, Thomas R., 1964- Boyle, Paul D. Petersen, Jeffrey L. ruthenium hydride complexes carbene ligands olefins aldehydes ketones This article discusses six-, five-, and four-coordinate ruthenium(II) hydride complexes. The Ru(II) hydride complex (IMes)2Ru(Cl)(H)(CO) (1) {IMes = 1,3-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene} was synthesized from [Ru(CO)2Cl2]n and free IMes. Complex 1 rapidly reacts with CO to produce the cis-dicarbonyl Ru(II) complex (IMes)2Ru(Cl)(H)(CO)2 (2). The reaction of 1 with NaBAr'4 {Ar' = 3,5-(CF3)C6H3} produces the four-coordinate Ru(II) cationic complex [(IMes)2Ru(H)(CO)][BAr'4] (4), which can be trapped by two equivalents of tert-butylisonitrile to produce [(IMes)2Ru(H)(CO)(CNtBu)2][BAr'4] (5). Experimental and computational studies suggest that complex 4 is a diamagnetic system that adopts a sawhorse structure. The hydride ligand of complex 2 is readily displaced as dihydrogen upon reaction with HCI to produce (IMes)2Ru(CI)2(CO)2 (3). Both complex 1 and 4 were found to react with D2 (30 psi) at room temperature to produce the isotopomers (IMes)2Ru(CI)(D)(CO) (1-d1) and [(IMes)2Ru(D)(CO)][BAr'4] (4-d1), respectively, with the rate of formation of 4-d1 at least 28 times faster than the conversion of 1/D2 to 1-d1. In the presence of excess D2 complex 4 reversibly incorporates deuterium into the ortho methyl groups of the IMes ligands, whereas complex 1 does not show evidence of H/D exchange with the IMes ligands. Both 1 and 4 were found to catalyze the hydrogenation of olefins, ketones, and aldehydes. American Chemical Society 2009-02-20 Article 18 p. Text doi: 10.1021/om801111c http://digital.library.unt.edu/ark:/67531/metadc77193/ ark: ark:/67531/metadc77193 Organometallics, 2009, Washington DC: American Chemical Society, pp. 1758-1775 English Public

info:ark/67531/metadc77158 2013-04-16T12:51:02Z partner:UNTCAS collection:UNTSW access_rights:public

Generalized anxiety modulates frontal and limbic activation in major depression Schlund, Michael W. Verduzco, Guillermo Cataldo, Michael F. Hoehn-Saric, Rudolf anxiety modulates frontal activation limbic activation depression This article discusses generalized anxiety modulates frontal and limbic activation in major depression. Abstract: Background: Anxiety is relatively common in depression and capable of modifying the severity and course of depression. Yet our understanding of how anxiety modulates frontal and limbic activation in depression is limited. Methods: The authors used functional magnetic resonance imaging and two emotional information processing tasks to examine frontal and limbic activation in ten patients with major depression and comorbid with preceding generalized anxiety (MDD/GAD) and ten non-depressed controls. Results: Consistent with prior studies on depression, MDD/GAD patients showed hypoactivation in medial and middle frontal regions, as well as in the anterior cingulate and insula. However, heightened anxiety in MDD/GAD patients was associated with increased activation in middle frontal regions and the insula and the effects varied with the type of emotional information presented. Conclusions: The authors' findings highlight frontal and limbic hypoactivation in patients with depression and comorbid anxiety and indicate that anxiety level may modulate frontal and limbic activation depending upon the emotional context. One implication of this finding is that divergent findings reported in the imaging literature on depression could reflect modulation of activation by anxiety level in response to different types of emotional information. BioMed Central Ltd. 2012-02-09 Article 14 p. Text doi: 10.1186/1744-9081-8-8 http://digital.library.unt.edu/ark:/67531/metadc77158/ ark: ark:/67531/metadc77158 Behavioral and Brain Functions, 2012, London: BioMed Central Ltd. English Generalized anxiety modulates frontal and limbic activation in major depression, ark:/67531/metadc122164 Public Attribution

info:ark/67531/metadc77184 2013-04-17T10:52:39Z partner:UNTCAS collection:UNTSW access_rights:public

Ruthenium(II)-Mediated Carbon-Carbon Bond Formation between Acetonitrile and Pyrrole: Combined Experimental and Computational Study Pittard, Karl A. Cundari, Thomas R., 1964- Gunnoe, T. Brent Day, Cynthia S. Petersen, Jeffrey L. bonds transition metal complexes This article discusses ruthenium(II)-mediated carbon-carbon bond formation between acetonitrile and pyrrole. The reaction of TpRu(CO)(NCMe)(Me) (1) and pyrrole forms TpRu(CO) {κ2-N,N-(H)N = C(Me)(NC4H3)} (2). The formation of complex 2 involves the cleavage of the N-H bond and 2-position C-H bonds of pyrrole as well as a C-C bond forming step between pyrrole and the acetonitrile ligand of 1. Mechanistic studies indicate that the most likely reaction pathway involves initial metal-mediated N-H activation of pyrrole to produce TpRu(CO)(N-pyrrolyl)-(NCMe) (3) followed by C-C bond formation and proton transfer. Complex 3 has been independently prepared and demonstrated to convert to 2. Computational studies support the suggested selectivity for initial N-H bond cleavage in preference to C-H bond activation. American Chemical Society 2005-09-13 Article 10 p. Text doi: 10.1021/om0506668 http://digital.library.unt.edu/ark:/67531/metadc77184/ ark: ark:/67531/metadc77184 Organometallics, 2005, Washington DC: American Chemical Society, pp. 5015-5024 English Public

info:ark/67531/metadc77181 2013-04-17T10:50:48Z partner:UNTCAS collection:UNTSW access_rights:public

Reversible Beta-Hydrogen Elimination of Three-Coordinate Iron(II) Alkyl Complexes: Mechanistic and Thermodynamic Studies Vela, Javier Vaddadi, Sridhar Cundari, Thomas R., 1964- Smith, Jeremy M. Gregory, Elizabeth A. Lachicotte, Rene J. Flaschenriem, Christine J. Holland, Patrick L. beta-hydrogen three-coordinate iron(II) alkyl complexes mechanistic thermodynamics This article discusses reversible beta-hydrogen elimination of three-coordinate iron(II) alkyl complexes. High-spin organometallic complexes have not received extensive mechanistic study, despite their potential importance as unsaturated intermediates in catalytic transformations. The authors have found that, with a suitably bulky bidentate ligand, three-coordinate, high-spin alkyl complexes of iron(II) are stable. They undergo isomerization and exchange reactions of the alkyl group through β-hydride elimination and reinsertion, and the β-hydride elimination step is rate-limiting. The alkyl complexes transfer a β-hydrogen atom to C=C, C=N, and C=O double bonds and undergo deprotonation by Brønsted acids. The reversible β-hydride elimination reactions can be used to explore relative M-C bond energies. Competition experiments and density functional calculations demonstrate an enthalpic preference for alkyl isomers with iron bound to the terminal carbon of the alkyl fragment. This preference arises from steric and electronic effects. The steric preference could be overcome with a phenyl substituent, which steers iron to the benzylic position. A Hammett correlation and density functional calculations suggest that the substituent effect is attributable to resonance stabilization of partial negative charge on the alkyl ligand. American Chemical Society 2004-10-01 Article 14 p. Text doi: 10.1021/om049415+ http://digital.library.unt.edu/ark:/67531/metadc77181/ ark: ark:/67531/metadc77181 Organometallics, 2004, Washington DC: American Chemical Society, pp. 5226-5239 English Public

info:ark/67531/metadc77187 2013-04-17T10:49:26Z partner:UNTCAS collection:UNTSW access_rights:public

Octahedral [TpRu(PMe3)2OR]n+ Complexes (Tp = hydridotris(pyrazolyl)borate; R = H or Ph; n = 0 or 1): Reactions at Ru(II) and Ru(III) Oxidation States with Substrates that Possess Carbon-Hydrogen Bonds Feng, Yuee Gunnoe, T. Brent Grimes, Thomas V. Cundari, Thomas R., 1964- carbon-hydrogen bonds phenylacetylene This article discusses octahedral [TpRu(PMe3)2OR]n+ Complexes (Tp = hydridotris(pyrazolyl)borate. The Ru(II) complexes TpRu(PMe3)2OR (R = H or Ph) react with excess phenylacetylene at elevated temperatures to produce the phenylacetylide complex TpRu(PMe3)2(C≡CPh). Kinetic studies indicate that the reaction of TpRu(PMe3)2OH and phenylacetylene likely proceeds through a pathway that involves TpRu(PMe3)2OTf as a catalyst. The reaction of TpRu(PMe3)2OH with 1,4-cyclohexadiene at elevated temperature forms benzene and TpRu(PMe3)2H, while TpRu(PMe3)2OPh does not react with 1,4-cyclohexadiene even after 20 days at 80 ˚C. The paramagnetic Ru(III) complex [TpRu(PMe3)2OH][OTf] is formed upon single-electron oxidation of TpRu(PMe3)2OH with AgOTf. Reactivity studies suggest that [TpRu(PMe3)2OH][OTf] initiates reactions, including hydrogen atom abstraction, with C-H bonds that have bond dissociation energy < 80 kcal/mol. Experimentally, the O-H bond strength of the Ru(II) cation [TpRu(PMe3)2(OH2)][OTf] is estimated to be between 82 and 85 kcal/mol, while computational studies yield a BDE of 84 kcal/mol, which are in reasonable agreement with the observed reactivity of [TpRu(PMe3)2OH]+. American Chemical Society 2006-09-15 Article 10 p. Text doi: 10.1021/om0606385 http://digital.library.unt.edu/ark:/67531/metadc77187/ ark: ark:/67531/metadc77187 Organometallics, 2006, Washington DC: American Chemical Society, pp. 5456-5465 English Public

info:ark/67531/metadc77160 2013-05-15T17:13:11Z partner:UNTCAS collection:UNTSW access_rights:public

Lévy diffusion as an effect of sporadic randomness Bologna, Mauro Grigolini, Paolo Riccardi, Juri lévy diffusions randomness This article discusses Lévy diffusion as an effect of sporadic randomness. Abstract: The Lévy diffusion processes are a form of nonordinary statistical mechanics resting, however, on the conventional Markov property. As a consequence of this, their dynamic derivation is possible provided that (i) a source of randomness is present in the corresponding microscopic dynamics and (ii) the consequent process of memory erasure is properly taken into account by the theoretical treatment. American Physical Society 1999-12 Article 8 p. Text doi: 10.1103/PhysRevE.60.6435 http://digital.library.unt.edu/ark:/67531/metadc77160/ ark: ark:/67531/metadc77160 Physical Review E, 1999, College Park: American Physical Society, pp. 6435-6442 English Public

info:ark/67531/metadc77171 2013-05-14T11:41:06Z partner:UNTCAS collection:UNTSW access_rights:public

Intertrimer and Intratrimer Metallophilic and Excimeric Bonding in the Ground and Phosphorescent States of Trinuclear Coinage Metal Pyrazolates: A Computational Study Grimes, Thomas V. Omary, Mohammad A. Dias, H. V. Rasika Cundari, Thomas R., 1964- metallophilic bonding excimeric bonding trinuclear coinage metal pyrazolates This article discusses intertrimer and intratrimer metallophilic and excimeric bonding. Abstract: The interactions present in cyclic trinuclear coinage metal pyrazolates were studied computationally. Cuprophilic interaction was found to bind the singlet ground state of the dimer of trimers {[Cu(Pz)]₃}₂, overcoming electrostatic repulsion. The large variation in intertrimer separations found in the literature for coinage metal pyrazolates is consistent with the relatively weak metallophilic interaction. The emissive triplet excited-state geometry of {[M(Pz]₃}₂ is predicted by density functional calculations to show major geometric distortion caused by Jahn-Teller instability and excimeric M-M bonding. Large calculated Stokes' shifts, which are also observed for experimental models, are consistent with significant excited-state distortions for these materials. The major finding derived from the present study is that the intertrimer M⋯M contraction in the emissive T₁ state is much more than the intratrimer contraction in all {[M(Pz)]₃}₂ models, giving rise to a lower T₁ → S₀ phosphorescence energy in these models than in analogous monomer-of-trimer models. The observations made here point to a great potential for rationally tuning the emission properties of trinuclear coinage metal complexes through choice of the metal and ligands. American Chemical Society 2006-04-08 Article 8 p. Text doi: 10.1021/jp0605146 http://digital.library.unt.edu/ark:/67531/metadc77171/ ark: ark:/67531/metadc77171 Journal of Physical Chemistry A, 2006, Washington DC: American Chemical Society, pp. 5823-5830 English Public

info:ark/67531/metadc77226 2013-03-18T15:55:32Z partner:UNTCAS collection:UNTSW access_rights:public

Ciencia y política: perspectiva histórica y modelos alternativos Science and politics: historical perspective and alternative models Mitcham, Carl Briggle, Adam science policies ethics scientific budgets alternative models This article discusses science and policy. Abstract: Should ethical matters make use of political means to influence the direction of scientific research? To what extent the influence of political and economic competition in the trajectory of scientific research could -or should- be allowed? These questions guide the critical review of the relations between science and policy made by the authors. In order to carry out this task they offer an analysis of the historical antecedents of the policy of science and they also provide comparative data and ethical reflections on the policy of scientific budget. Finally, they explain the reaches of alternative models of science policies. Science Technology Society 2007-04 Article 16 p. Text http://digital.library.unt.edu/ark:/67531/metadc77226/ ark: ark:/67531/metadc77226 Ibero-American Journal of Science, Technology and Society, 2007, Buenos Aires: Science Technology Society, pp. 143-158 Spanish Public

info:ark/67531/metadc77214 2012-12-14T15:18:08Z partner:UNTCAS collection:UNTSW access_rights:public

Not in My Back Yard! UNT Speaks Out Briggle, Adam oil gas energy fracking This presentation is part of the faculty lecture series UNT Speaks Out on Gas Well Drilling Redux. This presentation discusses the 'not in my back yard' (NIMBY) attitude - opposition by residents to a proposal for new development that is close to their homes - and focus on whether is it principled or hypocritical to simultaneously oppose the development while benefiting economically from it. UNT Libraries 2012-02-08 Presentation 22 p. Image http://digital.library.unt.edu/ark:/67531/metadc77214/ ark: ark:/67531/metadc77214 UNT Speaks Out: Gas Well Drilling Redux, 2012, Denton, Texas, United States English Gas Well Drilling, ark:/67531/metadc83315 Public

info:ark/67531/metadc77221 2012-12-07T11:46:28Z partner:UNTCAS collection:UNTSW access_rights:public

[Review] Tempting Fate: The Ethics of Dual-Use Research Briggle, Adam societal ethical nanotechnology This review is of the book Tempting Fate: The Ethics of Dual-Use Research by Seumas Miller and Michael J. Selgelid. The dual-use dilemma, which Miller and Selgelid argue arises from the fact that "one and the same piece of scientific research sometimes has the potential to be used for harm as well as for good". Springer 2009-03-20 Article 3 p. Text doi: 10.1007/s11569-009-0059-x http://digital.library.unt.edu/ark:/67531/metadc77221/ ark: ark:/67531/metadc77221 Nanoethics, 2009, Enschede: Springer, pp. 75-77 English Public

info:ark/67531/metadc77216 2012-12-06T13:18:41Z partner:UNTCAS collection:UNTSW access_rights:public

A New Philosophy for the 21st Century Briggle, Adam Frodeman, Robert philosophy education academics This article discusses a new philosophy for the 21st century. The authors have devoted their lives to philosophy. They want the field to survive and, if possible, prosper. But it is increasingly doubtful that academic philosophy can thrive in an era of declining budgets, soaring debts, antipathy to tax increases, and new technologies such as distance education. Of course, philosophy is secure at America's elite universities. But what of the vast number of universities whose future is tied to the decisions of state legislatures or other financial conditions? The Chronicle of Higher Education 2011-12-11 Article 7 p. Text http://digital.library.unt.edu/ark:/67531/metadc77216/ ark: ark:/67531/metadc77216 The Chronicle, 2011, Washington DC: The Chronicle of Higher Education English Public

info:ark/67531/metadc77225 2013-05-14T12:11:18Z partner:UNTCAS collection:UNTSW access_rights:public

Introducing a Policy Turn in Environmental Philosophy Briggle, Adam Frodeman, Robert Holbrook, J. Britt environmental philosophies policies philosophers This article discusses policies in environmental philosophy. Abstract: This essay inaugurates a commitment to devote a small part of Environmental Philosophy to reflection on how environmental philosophers can better engage scientists and decision-makers already involved in their own conversation about the environment. Philosophers generally have not made the question of how to make philosophy a relevant or useful part of their philosophical research. By way of introduction, we begin to articulate a theoretical framework for how we might integrate the humanities, philosophy in general, and environmental philosophy in particular with issues of public policy via a practical engagement of scholars across the humanities in a conversation that simultaneously invites non-academics within and takes us beyond the walls of academia. International Association for Environmental Philosophy 2006 Article 6 p. Text http://digital.library.unt.edu/ark:/67531/metadc77225/ ark: ark:/67531/metadc77225 Environmental Philosophy, 2006, Rochester: International Association for Environmental Philosophy, pp. 70-77 English Public

info:ark/67531/metadc78294 2013-03-20T11:22:01Z partner:UNTCAS collection:UNTSW access_rights:public

Comparative Plant Genomics Resources at Plant GDB Dong, Qunfeng Lawrence, Carolyn J. Schlueter, Shannon D. Wilkerson, Matthew D. Kurtz, Stefan Brendel, Volker Lushbough, Carol plant molecular sequences expressed sequence tags genes This article discusses comparative plant genomics resources at PlantGDB. Abstract: PlantGDB is a database of plant molecular sequences. Expressed sequence tag (EST) sequences are assembled into contigs that represent tentative unique genes. EST contigs are functionally annotated with information derived from known protein sequences that are highly similar to the putative translation products. Tentative Gene Ontology terms are assigned to match those of the similar sequences identified. Genome survey sequences are assembled similarly. The resulting genome survey sequence contigs are matched to ESTs and conserved protein homologs to identify putative full-length open reading frame-containing genes, which are subsequently provisionally classified according to established gene family designations. For Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa), the exon-intron boundaries for gene structures are annotated by spliced alignment of ESTs and full-length cDNAs to their respective complete genome sequences. Unique genome browsers have been developed to present all available EST and cDNA evidence for current transcript models. In addition, a number of bioinformatic tools have been integrated at PlantGDB that enable researchers to carry out sequence analyses on-site using both their own data and data residing within the database. American Society of Plant Biologists 2005-10 Article 9 p. Text doi: 10.1104/pp.104.059212 http://digital.library.unt.edu/ark:/67531/metadc78294/ ark: ark:/67531/metadc78294 Plant Physiology, 2005, Rockville: American Society of Plant Biologists, pp. 610-618 English Public

info:ark/67531/metadc78320 2013-03-18T17:00:24Z partner:UNTCAS collection:UNTSW access_rights:public

Cluster Core-Level Binding-Energy Shifts: The Role of Lattice Strain Richter, B. Kuhlenbeck, H. Freund, H.-J. Bagus, Paul S. lattice strains binding energies chemical bonding This article discusses cluster core-level binding-energy shifts. Abstract: Our combined experimental and theoretical analysis of the shifts, with particle size, of core-level binding energies (BE's) of metal nanoparticles on insulating supports, shows that these shifts have an important initial state contribution arising, in large part, because of lattice strain. This contribution of BE shifts has not been recognized previously. Lattice strain changes the chemical bonding between the metal atoms and this change induces BE shifts. American Physical Society 2004-07 Article 4 p. Text doi: 10.1103/PhysRevLett.93.026805 http://digital.library.unt.edu/ark:/67531/metadc78320/ ark: ark:/67531/metadc78320 Physical Review Letters, 2004, College Park: American Physical Society English Public

info:ark/67531/metadc78333 2013-03-20T11:04:50Z partner:UNTCAS collection:UNTSW access_rights:public

Characteristic Male Urine Microbiomes Associate with Asymptomatic Sexually Transmitted Infection Nelson, David E. Van Der Pol, Barbara Dong, Qunfeng Revanna, Kashi V. Fan, Baochang Easwaran, Shraddha Sodergren, Erica Weinstock, George M., 1949- Diao, Lixia Fortenberry, J. Dennis microbiomes infections bacteria urine This article discusses characteristic male urine microbiomes. Abstract: Background: The microbiome of the male urogenital tract is poorly described but it has been suggested that bacterial colonization of the male urethra might impact risk of sexually transmitted infection (STI). Previous cultivation-dependent studies showed that a variety of non-pathogenic bacteria colonize the urethra but did not thoroughly characterize these microbiomes or establish links between the compositions of urethral microbiomes and STI. Methodology/Findings: Here, the authors used 165 rRNA PCR and sequencing to identify bacteria in urine specimens collected from men who lacked symptoms of urethral inflammation but who differed in status for STI. All of the urine samples contained multiple bacteria genera and many contained taxa that colonize the human vagina. Uncultivated bacteria associated with female genital tract pathology were abundant in specimens from men who had STI. Conclusions: Urine microbiomes from men with STI were dominated by fastidious, anaerobic and uncultivated bacteria. The same taxa were rare in STI negative individuals. The authors' findings suggest that the composition of male urine microbiomes is related to STI. Public Library of Science 2010-11 Article 7 p. Text doi: 10.1371/journal.pone.0014116 http://digital.library.unt.edu/ark:/67531/metadc78333/ ark: ark:/67531/metadc78333 PLoS One, 2010, San Francisco: Public Library of Science English Public

info:ark/67531/metadc78274 2012-12-14T15:16:20Z partner:UNTCAS collection:UNTSW access_rights:public

No Longer Collecting Dust: How ETD & Open Access Will Revolutionize the Academy Meernik, James David electronic collections theses dissertations open access This is the presentation for the closing remarks at the Texas Electronic Theses and Dissertations (TxETD) Annual Conference. It discusses how ETDs and open access will revolutionize the academy. University of North Texas Libraries 2012-02 Presentation 8 p. Image http://digital.library.unt.edu/ark:/67531/metadc78274/ ark: ark:/67531/metadc78274 Texas Electronic Theses and Dissertations Annual (TxETDA) Conference, 2012, Denton, Texas, United States English Public

info:ark/67531/metadc78339 2012-12-06T13:07:11Z partner:UNTCAS collection:UNTSW access_rights:public

Multiple domains in MtENOD8 protein including the signal peptide target it to the symbiosome Meckfessel, Matthew H. Blancaflor, Elison B. Plunkett, Michael Dong, Qunfeng Dickstein, Rebecca plant cells proteins symbiotic nitrogen fixation nodules This article discusses multiple domains in MtENOD8 protein. Symbiotic nitrogen fixation occurs in nodules, specialized organs on the roots of legumes. Within nodules, host plant cells are infected with rhizobia that are encapsulated by a plant-derived membrane forming a novel organelle, the symbiosome. In Medicago truncatula, the symbiosome consists of the symbiosome membrane (SymM), a single rhizobium, and the soluble space between them, called the symbiosome space (Syms). The SymS is enriched with plant-derived proteins, including the MtENOD8 protein. Here, the authors present evidence from GFP fusion experiments that the MtENOD8 protein contains at least three symbiosome targeting domains, including its N-terminal signal peptide (SP). When ectopically expressed in non-nodulated root tissue, the MtENOD8 SP delivers GFP to the vacuole. During the course of nodulation, there is a nodule-specific re-direction MtENOD8-SP-GFP from the vacuole to punctate intermediates and subsequently to symbiosomes, with re-direction of MtENOD8-SP-GFP from the vacuole to punctate intermediates preceding intracellular rhizobial infection. Experiments with Medicago mutants having defects in rhizobial infection and symbiosome development demonstrated that the MtNIP/LATD gene is required for re-direction of the MtENOD8-SP-GFP from the vacuoles to punctate intermediates in nodules. The authors' evidence shows that MtENOD8 has evolved redundant targeting sequences for symbiosome targeting and that intracellular localization of ectopically expressed MtENOD8-SP-GFP is useful as a marker for monitoring the extent of development in mutant nodules. American Society of Plant Biologists 2012-05 Article 41 p. Text doi: 10.1104/pp.111.191403 http://digital.library.unt.edu/ark:/67531/metadc78339/ ark: ark:/67531/metadc78339 Plant Physiology, 2012, Rockville: American Society of Plant Biologists English Public

info:ark/67531/metadc78288 2013-04-01T16:08:39Z partner:UNTCAS collection:UNTSW access_rights:public

Effective carbon partitioning driven by exotic phloem-specific regulatory elements fused to the Arabidopsis thaliana AtSUC2 sucrose-proton symporter gene Srivastava, Avinash C. Ganesan, Savita Ismail, Ihab O. Ayre, Brian G. carbon partitioning sucrose-proton symporter genes This article discusses effective carbon partitioning. Abstract: Background: AtSUC2 (At1g22710) from Arabidopsis thaliana encodes a phloem-localized sucrose/proton symporter required for efficient photoassimilate transport from source tissues to sink tissues. AtSUC2 plays a key role in coordinating the demands of sink tissues with the output capacity of source leaves, and in maintaining phloem hydrostatic pressure during changes in plant-water balance. Expression and activity are regulated, both positively and negatively, by developmental (sink or source transition) and environmental cues, including light, diurnal changes, photoassimilate levels, turgor pressure, drought and osmotic stress, and hormones. Results: To assess the importance of this regulation to whole-plant growth and carbon partitioning, AtSUC2 cDNA was expressed from two exotic, phloem-specific promoters in a mutant background debilitated for AtSUC2 function. The first was a promoter element from Commelina Yellow Mottle Virus (CoYMV), and the second was the rolc promoter from Agrobacterium rhizogenes. CoYMVp::AtSUC2 cDNA restored growth and carbon partitioning to near wild-type levels, whereas plants harboring rolCp::AtSUC2 cDNA showed only partial complementation. Conclusion: Expressing AtSUC2 cDNA from exotic, phloem-specific promoters argues that strong, phloem-localized expression is sufficient for efficient transport. Expressing AtSUC2 from promoters that foster efficient phloem transport but are subject to regulatory cascades different from the endogenous sucrose/proton symporter genes has implications for biotechnology. BioMed Central Ltd. 2009-01-20 Article 13 p. Text doi: 10.1186/1471-2229-9-7 http://digital.library.unt.edu/ark:/67531/metadc78288/ ark: ark:/67531/metadc78288 BMC Plant Biology, 2009, London: BioMed Central Ltd. English Public Attribution

info:ark/67531/metadc78299 2013-04-01T14:02:58Z partner:UNTCAS collection:UNTSW access_rights:public

The Ecoresponsive Genome of Daphnia pulex Colbourne, John K. Pfrender, Michael E. Gilbert, Donald Thomas, W. Kelley Tucker, Abraham Oakley, Todd H. Tokishita, Shinichi Aerts, Andrea Arnold, Georg J. Basu, Malay Kumar Bauer, Darren J. Cáceres, Carla E. Carmel, Liran Casola, Claudio Choi, Jeong-Hyeon Detter, John C. Dong, Qunfeng Dusheyko, Serge Eads, Brian D. Fröhlich, Thomas Geiler-Samerotte, Kerry A. Gerlach, Daniel Hatcher, Phil Jogdeo, Sanjuro Krijgsveld, Jeroen Kriventseva, Evgenia Kültz, Dietmar Laforsch, Christian Lindquist, Erika Lopez, Jacqueline Manak, J. Robert Muller, Jean Pangilinan, Jasmyn Patwardhan, Rupali P. Pitluck, Samuel Pritham, Ellen J. Rechtsteiner, Andreas Rho, Mina Rogozin, Igor B. Sakarya, Onur Salamov, Asaf Schaack, Sarah Shapiro, Harris Shiga, Yasuhiro Skalitzky, Courtney Smith, Zachary Souvorov, Alexander Sung, Way Tang, Zuojian Tsuchiya, Dai Tu, Hank Vos, Harmjan Wang, Mei Wolf, Yuri I. Yamagata, Hideo Yamada, Takuji Ye, Yuzhen Shaw, Joseph R. Andrews, Justen Crease, Teresa J. Tang, Haixu Lucas, Susan M. Robertson, Hugh M. Bork, Peer Koonin, Eugene V. Zdobnov, Evgeny M. Grigoriev, Igor V. Lynch, Michael Boore, Jeffrey L. Daphnia pulex gene families genome This article discusses the ecoresponsive genome of Daphnia pulex. Abstract: We describe the draft genome of the microcrustacean Daphnia pulex, which is only 200 megabases and contains at least 30,907 genes. The high gene count is a consequence of an elevated rate of gene duplication resulting in tandem gene clusters. More than a third of Daphnia's genes have no detectable homologs in any other available proteome, and the most amplified gene families are specific to the Daphnia lineage. The coexpansion of gene families interacting within metabolic pathways suggests that the maintenance of duplicated genes is not random, and the analysis of gene expression under different environmental conditions reveals that numerous paralogs acquire divergent expression patterns soon after duplication. Daphnia-specific genes, including many additional loci within sequenced regions that are otherwise devoid of annotations, are the most responsive genes to ecological challenges. American Association for the Advancement of Science 2011-02-04 Article 7 p. Text doi: 10.1126/science.1197761 http://digital.library.unt.edu/ark:/67531/metadc78299/ ark: ark:/67531/metadc78299 Science, 2011, Washington DC: American Association for the Advancement of Science, pp. 555-561 English Public

info:ark/67531/metadc78324 2013-04-01T17:11:40Z partner:UNTCAS collection:UNTSW access_rights:public

Effects of covalency on the p-shell photoemission of transition metals: MnO Bagus, Paul S. Ilton, Eugene S. transition metals x-ray photoemission spectra XPS This article discusses the effects of covalency on the p-shell photoemission of transition metals. Abstract: The effect of the solid-state environment for an Mn cation in MnO on the Mn 2p- and 3p-shell x-ray photoemission spectra (XPS) has been investigated using ab initio relativistic wave functions for an embedded MnO6 cluster model of MnO. These wave functions include many-body effects due to the angular momentum coupling and recoupling of the open-shell electrons. They also include the covalent mixing of the metal d orbitals with ligand p orbitals. The treatment of covalency has not been included previously in ab initio theoretical studies of the 2p-shell XPS of transition-metal complexes. In this work, covalent interactions between the metal and ligands are treated on an equal footing with spin-orbit splittings. The four-component spinors used in these wave functions are optimized separately for the ground and for the 2p- and 3p-hole configurations. This orbital relaxation leads to a "closed-shell" interatomic screening of the Mn core hole. The different orbital sets optimized for the ground and core-ionized configurations mean that mutually nonorthogonal orbital sets are used to determine the matrix elements for the XPS relative intensities. The authors' treatment of the transition intensities is rigorous, and no approximations are introduced to handle the orbital nonorthogonality. The closed-shell screening is important because changes in the XPS obtained for the MnO6 cluster from that obtained for an isolated Mn2+ cation can be directly linked to this screening and to the consequent reduction in the values of certain exchange integrals. The present work is compared to prior, semiempirical calculations; these comparisons allow the authors to identify unresolved questions about the origin of certain features of the MnO XPS and to suggest further calculations to resolve these questions. American Physical Society 2006-04-13 Article 14 p. Text doi: 10.1103/PhysRevB.73.155110 http://digital.library.unt.edu/ark:/67531/metadc78324/ ark: ark:/67531/metadc78324 Physical Review B, 2006, College Park: American Physical Society English Public

info:ark/67531/metadc78330 2013-04-02T14:55:30Z partner:UNTCAS collection:UNTSW access_rights:public

Enabling Large Scale Scientific Computations for Expressed Sequence Tag Sequencing over Grid and Cloud Computing Clusters Pallickara, Sangmi Lee Pierce, Marlon Dong, Qunfeng Kong, ChinHua grid computing cloud computing bioinformatics scientific computing high throughput computing This paper discusses expressed sequence tag sequencing over grid and cloud computing clusters. Abstract: Computer-intensive biological applications are heavily reliant on the availability of computing resources. Grid based HPC clusters and emerging Cloud computing clusters provide a large scale computing environment for scientific users. However, large scale biological application often involves various types of computational tasks which can benefit from different types of computing clusters. Therefore, a high level job scheduling environment which integrates the Grid style HPC clusters and the Cloud computing clusters and manages jobs accordingly based on the characteristics of the jobs is required. In this paper, the authors propose a Web service framework for high-level job scheduling - Swarm. Swarm is developed for scientific applications that must submit massive number of high-throughput jobs or workflows to highly distributed computing clusters. Swarm allows the users to submit jobs to both Grid HPC and Cloud computing clusters. The Swarm service itself is designed to be extensible, lightweight, and easily installable on a desktop or a small server. As a Web service, derivative services based on Swarm can be straightforwardly integrated with Web portals and science gateways. This paper provides the motivation for this research, the architecture of the Swarm framework, and a performance evaluation of the system prototype. Springer-Verlag TeraGrid 2009-09 Paper 10 p. Text http://digital.library.unt.edu/ark:/67531/metadc78330/ ark: ark:/67531/metadc78330 Eighth International Conference on Parallel Processing and Applied Mathematics (PPAM), 2009, Wroclaw, Poland English Public

info:ark/67531/metadc78335 2012-04-02T16:46:30Z partner:UNTCAS collection:UNTSW access_rights:public

The Microbial Communities in Male First Catch Urine Are Highly Similar to Those in Paired Urethral Swab Specimens Dong, Qunfeng Nelson, David E. Toh, Evelyn Diao, Lixia Gao, Xiang Fortenberry, J. Dennis Van Der Pol, Barbara microbials bacteria urine This article discusses microbial communities. Urine is the CDC-recommended specimen for STI testing. It was unknown if the bacterial communities (microbiomes) in urine reflected those in the distal male urethra. The authors compared microbiomes of 32 paired urine and urethral swab specimens obtained from adult men attending an STD clinic, by 16S rRNA PCR and deep pyrosequencing. Microbiomes of urine and swabs were remarkably similar, regardless of STI status of the subjects. Thus, urine can be used to characterize urethral microbiomes when swabs are undesirable, such as in population-based studies of the urethral microbiome or where multiple sampling of participants is required. Public Library of Science (PLoS) 2011-05-13 Article 5 p. Text doi: 10.1371/journal.pone.0019709 http://digital.library.unt.edu/ark:/67531/metadc78335/ ark: ark:/67531/metadc78335 PLoS One, 2011, San Francisco: Public Library of Science (PLoS) English Public

info:ark/67531/metadc78321 2012-04-02T16:46:30Z partner:UNTCAS collection:UNTSW access_rights:public

Work Function Changes Induced by Charged Adsorbates: Origin of the Polarity Asymmetry Bagus, Paul S. Käfer, Daniel Witte, Gregor Wöll, Christof adsorbates polarity asymmetry In this article, a theoretical analysis of charged adsorbates on a metal surface reveals a pronounced polarity asymmetry between electropositive and electronegative species, thus reproducing a well known but so far not properly understood experimental fact. For ionic adsorbates on metal surfaces, the authors analyze the several, often canceling, terms that contribute to the change of the interface dipole and, hence, to work-function changes, ∆ϕ. The authors demonstrate that for the prototypic case of I on Cu(111) the magnitudes and the signs of these terms can be understood on the basis of their physical and chemical origins. An important consequence of their cancellation is that negatively charged adsorbates can lead to a paradoxical ∆ϕ < 0 rather than the expected ∆ϕ > 0. American Physical Society 2008-03-28 Article 4 p. Text doi: 10.1103/PhysRevLett.100.126101 http://digital.library.unt.edu/ark:/67531/metadc78321/ ark: ark:/67531/metadc78321 Physical Review Letters, 2008, College Park: American Physical Society English Public

info:ark/67531/metadc78326 2012-04-02T16:46:30Z partner:UNTCAS collection:UNTSW access_rights:public

Many-body effects in the 4f x-ray photoelectron spectroscopy of the U5+ and U4+ free ions Ilton, Eugene S. Bagus, Paul S. x-ray photoemission spectra Dirac configuration interaction wave functions This article discusses many-body effects in the 4f x-ray photoelectron spectroscopy of the U5+ and U4+ free ions. A strictly ab initio many-electron theory was used to calculate the 4f x-ray photoelectron spectroscopy (XPS) of the free U5+ and U4+ ions. The calculations, based on relativistic Dirac-Fock self-consistent field (DF-SCF) and Dirac configuration interaction (DCI) wave functions (WF's), indicate that the atomic spectra have a considerable multiplet structure. However, the multiplet splitting, which is mainly manifest as a broadening of the 4f5/2 and 4f7/2 lines, is not as strong as for the first-row transition metals. As expected, the U4+ primary peaks are broader and have more associated satellite structure than does U5+. A comparison of a synthetic spectrum for U4+ with the observed XPS of UO2 indicates that interatomic, solid-state, effects may decrease the multiplet and spin-orbital splitting, relative to the free ion. Notably, the 7 eV satellite characteristic of UO2 is absent from the calculated XPS of U4+. American Physical Society 2005-05-31 Article 6 p. Text doi: 10.1103/PhysRevB.71.195121 http://digital.library.unt.edu/ark:/67531/metadc78326/ ark: ark:/67531/metadc78326 Physical Review B, 2005, College Park: American Physical Society English Public

info:ark/67531/metadc78332 2012-04-02T16:46:30Z partner:UNTCAS collection:UNTSW access_rights:public

Using WebGBrowse to Visualize Genome Annotation on GBrowse Podicheti, Ram Dong, Qunfeng GBrowse genomes This article discusses using WebGBrowse to visualize genome annotation on GBrowse. Although GBrowse is popular for visualizing genomic features along a reference sequence, its installation and configuration are difficult for many biologists. WebGBrowse is a web server that takes a user-supplied annotation file, guides users to configure the display of each genomic feature, and allows users to visualize the genome annotation with integrated GBrowse software. This protocol guides the user through each step of using WebGBrowse. Cold Spring Harbor Laboratory Press 2010 Article 6 p. Text doi: 10.1101/pdb.prot5392 http://digital.library.unt.edu/ark:/67531/metadc78332/ ark: ark:/67531/metadc78332 Cold Spring Harbor Protocols, 2010, USA: Cold Spring Harbor Laboratory Press English Public

info:ark/67531/metadc78297 2012-12-07T13:04:34Z partner:UNTCAS collection:UNTSW access_rights:public

TableMaker: An ad hoc Query Tool for Relational Databases Lushbough, Carol Duvick, Jon Dong, Qunfeng Jennewein, Douglas Reynoldson, Joe Brendel, Volker ad hoc queries relational databases This paper discusses an ad hoc query tool for relational databases. Most Web servers hosting biological data limit users to a defined set of search options and output formats that are short of the whole range of options available to users with direct database access. However, to make full use of the wealth of data in the database resource, it is desirable to have an intermediate solution that provides a broad range of flexible query and output options through a Web portal. CSREA Press 2008-07 Paper 4 p. Text http://digital.library.unt.edu/ark:/67531/metadc78297/ ark: ark:/67531/metadc78297 International Conference on Bioinformatics and Computational Biology (BIOCOMP), 2008, Las Vegas, Nevada, United States English Public

info:ark/67531/metadc78308 2012-12-21T13:28:12Z partner:UNTCAS collection:UNTSW access_rights:public

Metaphoric Analysis of a Shipyard Union Dispute: Theory and Method in the Cultural Analysis of Collective Action Figurative Speech and Cognition: Metaphoric Analysis of a Shipyard Union Dispute Culture, Social Movements, and Protests: Chapter 7 Ignatow, Gabe cultural analyses collective behaviors This book chapter discusses the metaphoric analysis of a shipyard union dispute and the theory and method in the cultural analysis of collective action. Rather than treating grievances and political opportunities, given, and exogenous to organized movement groups, cultural analysts of social movements have recently focused on cognitive and linguistic processes by which factors relevant to collective behavior are themselves interpreted collectively. Ashgate 2009-02 Book Chapter 24 p. Text isbn: 978-0-7546-7446-7 http://digital.library.unt.edu/ark:/67531/metadc78308/ ark: ark:/67531/metadc78308 Culture, Social Movements, and Protests, 2009, Farnham: Ashgate, pp. 157-180 English Public

info:ark/67531/metadc78286 2013-04-09T13:22:57Z partner:UNTCAS collection:UNTSW access_rights:public

Expression of genes associated with carbohydrate metabolism in cotton stems and roots Taliercio, Earl W. Romano, Gabriela Scheffler, Jodi Ayre, Brian G. plants crops cotton genes carbohydrate metabolism This article discusses the expression of genes associated with carbohydrate metabolism in cotton stems and roots. Abstract: Background: Cotton (Gossypium hirsutum L) is an important crop worldwide that provides fiber for the textile industry. Cotton is a perennial plant that stores starch in stems and roots to provide carbohydrates for growth in subsequent seasons. Domesticated cotton makes these reserves available to developing seeds which impacts seed yield. The goals of these analyses were to identify genes and physiology pathways that establish cotton stems and roots as physiological sinks and investigate the role these pathways play in cotton development during seed set. Results: Analysis of field-grown cotton plants indicated that starch levels peaked about the time of first anthesis and then declined similar to reports in greenhouse-grown cotton plants. Starch accumulated along the length of the stem and the shape and size of the starch grains from stems were easily distinguished from transient starch. Microarray analyses compared gene expression in tissues containing low levels of starch with tissues rapidly accumulating starch. Statistical analysis of differentially expressed genes indicated increased expression among genes associated with starch synthesis, starch degradation, hexose metabolism, raffinose synthesis and trehalose synthesis. The anticipated changes in these sugars were largely confirmed by measuring soluble sugars in selected tissues. Conclusion: In domesticated cotton starch stored prior to flowering was available to support seed production. Starch accumulation observed in young field-grown plants was not observed in greenhouse grown plants. A suite of genes associated with starch biosynthesis was identified. The pathway for starch utilization after flowering was associated with an increase in expression of a glucan water dikinase gene as has been implicated in utilization of transient starch. Changes in raffinose levels and levels of expression of genes controlling trehalose and raffinose biosynthesis were also observed in vegetative cotton tissues as plants age. BioMed Central Ltd. 2009-01-22 Article 10 p. Text doi: 10.1186/1471-2229-9-11 http://digital.library.unt.edu/ark:/67531/metadc78286/ ark: ark:/67531/metadc78286 BMC Plant Biology, 2009, London: BioMed Central Ltd. English Public

info:ark/67531/metadc78290 2013-04-15T15:28:24Z partner:UNTCAS collection:UNTSW access_rights:public

Functional Characterization of the Arabidopsis AtSUC2 Sucrose/H+ Symporter by Tissue-Specific Complementation Reveals an Essential Role in Phloem Loading But Not in Long-Distance Transport Srivastava, Avinash C. Ganesan, Savita Ismail, Ihab O. Ayre, Brian G. phloem plants flanking tissues carbon partitioning This article discusses functional characterization of the Arabidopsis AtSUC2 Sucrose/H+ Symporter. Abstract: AtSUC2 (At1g22710) encodes a phloem-localized sucrose (Suc)/H+ symporter necessary for efficient Suc transport from source tissues to sink tissues in Arabidopsis (Arabidopsis thaliana). AtSUC2, however, is also expressed strongly in the transport phloem, where its role is more ambiguous, and it has been implicated in mediating both efflux and retrieval to and from flanking tissues via the apoplast. To characterize the role of AtSUC2 in controlling carbon partitioning along the phloem path, AtSUC2 cDNA was expressed from tissue-specific promoters in an Atsuc2 mutant background. Suc transport in this mutant is highly compromised, as indicated by stunted growth and the accumulation of large quantities of sugar and starch in vegetative tissues. Expression of AtSUC2 cDNA from the 2-kb AtSUC2 promoter was sufficient to restore growth and carbon partitioning to nearly wild-type levels. The GALACTINOL SYNTHASE promoter of Cucumis melo (CmGAS1p) confers expression only in the minor veins of mature leaves, not in the transport phloem of larger leaf veins and stems. Mutant plants expressing AtSUC2 cDNA from CmGAS1p had intermediate growth and accumulated sugar and starch, but otherwise they had normal morphology. These characteristics support a role for AtSUC2 in retrieval but not efflux along the transport phloem and show that the only vital function of AtSUC2 in photoassimilate distribution is phloem loading. In addition, AtSUC2 mutant plants, although debilitated, do grow, and AtSUC2-independent modes of phloem transport are discussed, including an entirely symplastic pathway from mesophyll cells to sink tissues. American Society of Plant Biologists 2008-09 Article 12 p. Text doi: 10.1104/pp.108.124776 http://digital.library.unt.edu/ark:/67531/metadc78290/ ark: ark:/67531/metadc78290 Plant Physiology, 2008, Rockville: American Society of Plant Biologists, pp. 200-211 English Public

info:ark/67531/metadc78283 2013-05-14T11:29:13Z partner:UNTCAS collection:UNTSW access_rights:public

Interpolative multidimensional scaling techniques for the identification of clusters in very large sequence sets Hughes, Adam Ruan, Yang Ekanayake, Saliya Bae, Seung-Hee Dong, Qunfeng Rho, Mina Qiu, Judy Fox, Geoffrey bacterial populations pyrosequencing genes multidimensional scaling This article discusses interpolative multidimensional scaling techniques for the identification of clusters in very large sequence sets. Abstract: Background: Modern pyrosequencing techniques make it possible to study complex bacterial populations, such as 16S rRNA, directly from environmental or clinical samples without the need for laboratory purification. Alignment of sequences across the resultant large data sets (100,000+ sequences) is of particular interest for the purpose of identifying potential gene clusters and families, but such analysis represents a daunting computational task. The aim of this work is the development of an efficient pipeline for the clustering of large sequence read sets. Methods: Pairwise alignment techniques are used here to calculate genetic distances between sequence pairs. These methods are pleasingly parallel and have been shown to more accurately reflect accurate genetic distances in highly variable regions of rRNA genes that do traditional multiple sequence alignment (MSA) approaches. By utilizing Needleman-Wunsch (NW) pairwise alignment in conjunction with novel implementations of interpolative multidimensional scaling (MDS), the authors have developed an effective method for visualizing massive biosequence data sets and quickly identifying potential gene clusters. Results: This study demonstrates the use of interpolative MDS to obtain clustering results that are qualitatively similar to those obtained through full MDS, but with substantial cost savings. In particular, the wall clock time required to cluster a set of 100,000 sequences has been reduced from seven hours to less than one hour through the use of interpolative MDS. Conclusions: Although work remains to be done in selecting the optimal training set size for interpolative MDS, substantial computational cost savings will allow the authors to cluster much larger sequence sets in the future. BioMed Central Ltd. 2012-03-13 Article 6 p. Text doi: 10.1186/1471-2105-13-S2-S9 http://digital.library.unt.edu/ark:/67531/metadc78283/ ark: ark:/67531/metadc78283 BMC Bioinformatics, 2012, London: BioMed Central Ltd. English Public Attribution

info:ark/67531/metadc78328 2013-05-20T16:13:27Z partner:UNTCAS collection:UNTSW access_rights:public

Ligand-field effects for the 3p photoelectron spectra of Cr2O3 Bagus, Paul S. Ilton, Eugene S. Rustad, James R. photoemissions photoelectrons spectra electron spectroscopy This article discusses ligand-field effects for the 3p photoelectron spectra of Cr2O3. Abstract: A major reason for the departure of core level X-ray photoelectron spectra (XPS) of transition metal cations in oxides from the predictions of atomic models is shown to arise from ligand field splittings in the initial state of photoemission. This splitting often leads to a change in the spatial degeneracy of the initial state but the consequences of this for XPS have not been explicitly identified in prior work. Further changes arise from ligand field splittings in the core-hole final states. Results are reported for non-empirical, cluster model many body wavefunctions for the 3p XPS of Cr2O3. The agreement of the theoretical cluster model XPS with experiment is considerably improved over the pure atomic model. Furthermore, the treatment allows screening of the core hole through changes in the covalent character of the cluster orbitals. This is quite different from the usual description of screening in oxides within the framework of charge transfer configurations and it offers new insights into the role of charge transfer for satellite structure. American Physical Society 2004-05-28 Article 6 p. Text doi: 10.1103/PhysRevB.69.205112 http://digital.library.unt.edu/ark:/67531/metadc78328/ ark: ark:/67531/metadc78328 Physical Review B, 2004, College Park: American Physical Society English Public

info:ark/67531/metadc81383 2013-03-21T13:46:25Z partner:UNTCAS collection:UNTSW access_rights:public

A cytochrome P450 monooxygenase commonly used for negative selection in transgenic plants causes growth anomalies by disrupting brassinosteroid signaling Dasgupta, Kasturi Ganesan, Savita Manivasagam, Sindhu Ayre, Brian G. P450 genes plants brassinosteroid signaling homeostasis This article discusses a cytochrome P450 monooxygenase. Abstract: Background: Cytochrome P450 monooxygenases form a large superfamily of enzymes that catalyze diverse reactions. The P450su1 gene from the soil bacteria Streptomyces griseolus encodes CYP105A1 which acts on various substrates including sulfonylurea herbicides, vitamin D, coumarins, and based on the work presented here, brassinosteroids. P450su1 is used as a negative-selection marker in plants because CYP105A1 converts the relatively benign sulfonyl urea pro-herbicide R7402 into a highly phytotoxic product. Consistent with its use for negative selection, transgenic Arabidopsis plants were generated with P450su1 situated between recognition sequences for FLP recombinase from yeast to select for recombinase-mediated excision. However, unexpected and prominent developmental aberrations resembling those described for mutants defective in brassinosteroid signaling were observed in many of the lines. Results: The phenotypes of the most affected lines included severe stunting, leaf curling, darkened leaves characteristic of anthocyanin accumulation, delayed transition to flowering, low pollen and seed yields, and delayed senescence. Phenotype severity correlated with P450su1 transcript abundance, but not with transcript abundance of other experimental genes, strongly implicating CYP105A1 as responsible for the defects. Germination and seedling growth of transgenic and control lines in the presence and absence of 24-epibrassinolide indicated that CYP105A1 disrupts brassinosteroid signaling, most likely by inactivating brassinosteroids. Conclusions: Despite prior use of this gene as a genetic tool, deleterious growth in the absence of R7402 has not been elaborated. The authors show that this gene can cause aberrant growth by disrupting brassinosteroid signaling and affecting homeostasis. BioMed Central Ltd. 2011-04-15 Article 13 p. : col. ill. Text http://digital.library.unt.edu/ark:/67531/metadc81383/ ark: ark:/67531/metadc81383 BMC Plant Biology, 2011, London: BioMed Central Ltd. English Public

info:ark/67531/metadc81379 2012-09-10T18:48:48Z partner:UNTCAS collection:UNTSW access_rights:public

Symplastic Continuity between Companion Cells and the Translocation Stream: Long-Distance Transport Is Controlled by Retention and Retrieval Mechanisms in the Phloem Ayre, Brian G. Keller, Felix Turgeon, Robert companion cells phloem sieve elements minor veins This article discusses symplastic continuity between companion cells and the translocation stream. Substantial symplastic continuity appears to exist between companion cells (CCs) and sieve elements of the phloem, which suggests that small solutes within the CC are subject to indiscriminate long-distance transport via the translocation stream. To test this hypothesis, the distributions of exotic and endogenous solutes synthesized in the CCs of minor veins were studied. Octopine, a charged molecule derived from arginine and pyruvate, was efficiently transported through the phloem but was also transferred in substantial amounts to the apoplast, and presumably other non-phloem compartments. The disaccharide galactinol also accumulated in non-phloem compartments, but long-distance transport was limited. Conversely, sucrose, raffinose, and especially stachyose demonstrated reduced accumulation and efficient transport out of the leaf. The authors conclude that small metabolites in the cytosol of CCs do enter the translocation stream indiscriminately but are also subject to distributive forces, such as nonselective and carrier-mediated membrane transport and symplastic dispersal, that may effectively clear a compound from the phloem or retain it for long-distance transport. A model is proposed in which the transport or oligosaccharides is an adaptive strategy to improve photoassimilate retention, and consequently translocation efficiency, the phloem. American Society of Plant Biologists 2003-04 Article 11 p. Text doi: 10.1104/pp.012054 http://digital.library.unt.edu/ark:/67531/metadc81379/ ark: ark:/67531/metadc81379 Plant Physiology, 2003, Rockville: American Society of Plant Biologists, pp. 1518-1528 English Public

info:ark/67531/metadc81382 2012-04-06T16:58:04Z partner:UNTCAS collection:UNTSW access_rights:public

WebGBrowse 2.1 - A Web Server Supporting Multiple Versions of the Generic Genome Browser for Customizable Genome Annotation Display Podicheti, Ram Revanna, Kashi V. Dong, Qunfeng servers genome browsers GBrowse software In this book, the authors discuss WebGBrowse 2.1. Genome browsers are critical bioinformatics tools for biologists to visualize genome annotations and the other sequence features along a reference sequence. GBrowse is one of the most popular genome browsers used by the research community. However, its installation and configuration prove to be difficult for many biologists. The authors have developed a web server, WebGBrowse, which takes a user-supplied annotation file in GFF3 format, guides users through the configuration of the display of each genomic feature, and allows them to visualize the genome annotation information via the GBrowse software. This book describes an upgraded WebGBrowse server, WebGBrowse 2.0, which provides users with a choice to display their genome annotation with different versions of the GBrowse software. Nova Science Publishing, Inc. 2011-04 Book 40 p. Text isbn: 978-1-61122-873-1 2011 http://digital.library.unt.edu/ark:/67531/metadc81382/ ark: ark:/67531/metadc81382 English Public

info:ark/67531/metadc81385 2012-12-21T13:27:29Z partner:UNTCAS collection:UNTSW access_rights:public

Media and Communication The Oxford Handbook of Interdisciplinarity: Chapter 15 Briggle, Adam Christians, Clifford G. communication interdisciplinarity This book chapter discusses media and communication. Language is commonly singled out as the essence of humanity (Cassirer 1925). Human beings are co-creators, because they give names to the plants and animals. They invent symbols to represent things in their world, which allows them to share the contents of their minds with one another. Thus, as linguistic creatures, humans are also inherently social, because they inhabit a shared symbolic order made possible by their powers of representation and communication. And because of this pervasive character of communication in the development of the human species, media and communication studies have not been contained in an explicit discipline, with its own subject matter. Interdisciplinarity has been essential for understanding it. Oxford University Press 2010-07 Book Chapter 26 p. Text isbn: 978-0-19-923691-6 http://digital.library.unt.edu/ark:/67531/metadc81385/ ark: ark:/67531/metadc81385 The Oxford Handbook of Interdisciplinarity, 2010, Oxford: Oxford University Press English Public

info:ark/67531/metadc81378 2013-04-15T12:35:50Z partner:UNTCAS collection:UNTSW access_rights:public

Functional and Phylogenetic Analyses of a Conserved Regulatory Program in the Phloem of Minor Veins Ayre, Brian G. Blair, Jaime E. Turgeon, Robert phloem minor veins genes This article discusses functional and phylogenetic analyses of a conserved regulatory program in the phloem of minor veins. Abstract: The minor-vein phloem of mature leaves is developmentally and physiologically distinct from the phloem in the rest of the vascular system. Phloem loading of transport sugars occurs in the minor veins, and consistent with this, galactinol synthase is expressed in the minor veins of melon (Cucumis melo) as part of the symplastic-loading mechanism that operates in this species. A galactinol synthase promoter from melon drives gene expression in the minor-vein companion cells of both transgenic tobacco (Nicotiana tabacum) and Arabidopsis. Neither of these plants use galactinol in the phloem-loading process, implying that the promoter responds to a minor-vein-specific regulatory cascade that is highly conserved across a broad range of eudicotyledons. Detailed analysis of this promoter by truncation and mutagenesis identified three closely coupled sequences that unambiguously modulate tissue specificity. These sequences cooperate in a combinatorial fashion: two promote expression throughout the vascular system of the plant, whereas the third functions to repress expression in the larger bundles. In a complementary approach, phylogenetic footprinting was used to obtain single-nucleotide resolution of conserved sites in orthologous promoters from diverse members of the Cucurbitaceae. This comparative analysis confirmed the importance of the closely coupled sites but also revealed other highly conserved sequences that may modulate promoter strength or contribute to expression patterns outside of the phloem. The conservation of this regulatory design among species that phloem load by different mechanisms supports a model for organismal development in which tissues and cell types are controlled by relatively ancient and conserved paradigms but expression of genes influencing final form and function are relatively plastic. American Society of Plant Biologists 2003-11 Article 11 p. Text doi: 10.1104/pp.103.027714 http://digital.library.unt.edu/ark:/67531/metadc81378/ ark: ark:/67531/metadc81378 Plant Physiology, 2003, Rockville: American Society of Plant Biologists, pp. 1229-1239 English Public

info:ark/67531/metadc81380 2013-04-25T12:08:38Z partner:UNTCAS collection:UNTSW access_rights:public

Graft Transmission of a Floral Stimulant Derived from CONSTANS Ayre, Brian G. Turgeon, Robert flowering plants grafts photoperiod This article discusses graft transmission of a floral stimulant derived from CONSTANS. Abstract: Photoperiod in plants is perceived by leaves and in many species influences the transition to reproductive growth through long-distance signaling. CONSTANS (CO) is implicated as a mediator between photoperiod perception and the transition to flowering in Arabidopsis. To test the role of CO in long-distance signaling, CO was expressed from a promoter specific to the companion cells of the smallest veins of mature leaves. This expression in tissues at the inception of the phloem translocation stream was sufficient to accelerate flowering at the apical meristem under noninductive (short-day) conditions. Grafts that conjoined the vegetative stems of plants with different flower-timing phenotypes demonstrated that minor-vein expression of CO is able to substitute for photoperiod in generating a mobile flowering signal. The authors' results suggest that a CO-derived signal(s), or possibly CO itself, fits the definition of the hypothetical flowering stimulant, florigen. American Society of Plant Biologists 2004-08 Article 8 p. Text doi: 10.1104/pp.104.040592 http://digital.library.unt.edu/ark:/67531/metadc81380/ ark: ark:/67531/metadc81380 Plant Physiology, 2004, Rockville: American Society of Plant Biologists, pp. 2271-2278 English Public

info:ark/67531/metadc81381 2013-04-29T10:45:22Z partner:UNTCAS collection:UNTSW access_rights:public

Identification of Phloem Involved in Assimilate Loading in Leaves by the Activity of the Galactinol Synthase Promoter Haritatos, Edith Emily, 1969- Ayre, Brian G. Turgeon, Robert phloem galactinol synthase This article discusses identification of phloem. Abstract: The definition of "minor" veins in leaves is arbitrary and of uncertain biological significance. Generally, the term refers to the smallest vein classes in the leaf, believed to function in phloem loading. The authors found that a galactinol synthase promoter, cloned from melon (Cucumis melo), directs expression of the gusA gene to the smallest veins of mature Arabidopsis and cultivated tobacco (Nicotiana tabacum) leaves. This expression pattern is consistent with the role of galactinol synthase in sugar synthesis and phloem loading in cucurbits. The expression pattern in tobacco is especially noteworthy since galactinol is not synthesized in the leaves of this plant. Also, the authors unexpectedly found that expression in tobacco is limited to two of three companion cells in class-V veins, which are the most extensive in the leaf. Thus, the "minor" vein system is defined and regulated at the genetic level, and there is heterogeneity of response to this system by different companion cells of the same vein. American Society of Plant Physiologists 2000-07 Article 9 p. Text http://digital.library.unt.edu/ark:/67531/metadc81381/ ark: ark:/67531/metadc81381 Plant Physiology, 2000, Rockville: American Society of Plant Physiologists, pp. 929-937 English Public

info:ark/67531/metadc83329 2013-03-21T14:31:56Z partner:UNTCAS collection:UNTSW access_rights:unt

Dear Facebook Facebook and Philosophy: What's on Your Mind?: Chapter 14 Briggle, Adam Facebook online social networks Internet social aspects This book chapter is written in the form of a break-up letter from the author to the social networking website, Facebook. It discusses social networking, technological changes, urbanization, globalization, media technology, and philosophical ideas about society. Open Court Publishing Company 2010 Book Chapter 11 p. Text isbn: 978-8126-9675-2 http://digital.library.unt.edu/ark:/67531/metadc83329/ ark: ark:/67531/metadc83329 Facebook and Philosophy: What's on Your Mind?, 2010, Chicago: Open Court Publishing Company, pp. 161-171 English Use restricted to UNT Community

info:ark/67531/metadc83320 2013-03-25T12:14:09Z partner:UNTCAS collection:UNTSW access_rights:public

Design of highly specific cytotoxins by using trans-splicing ribozymes Ayre, Brian G. Köhler, Uwe Haseloff, Jim Goodman, Howard M. cytotoxins trans-splicing ribozymes This article discusses the design of highly specific cytotoxins by using trans-splicing ribozymes. Abstract: We have designed ribozymes based on a self-splicing group I intron that can trans-splice exon sequences into a chosen RNA target to create a functional chimeric mRNA and provide a highly specific trigger for gene expression. We have targeted ribozymes against the coat protein mRNA of a widespread plant pathogen, cucumber mosaic virus. The ribozymes were designed to trans-splice the coding sequence of the diphtheria toxin A chain in frame with the viral initiation codon of the target sequence. Diphtheria toxin A chain catalyzes the ADP ribosylation of elongation factor 2 and can cause the cessation of protein translation. In a Saccharomyces cerevisiae model system, ribozyme expression was shown to specifically inhibit the growth of cells expressing the virus mRNA. A point mutation at the target splice site alleviated this ribozyme-mediated toxicity. Increasing the extent of base pairing between the ribozyme and target dramatically increased specific expression of the cytotoxin and reduced illegitimate toxicity in vivo. Trans-splicing ribozymes may provide a new class of agents for engineering virus resistance and therapeutic cytotoxins. National Academy of Sciences (U.S.) 1999-03-30 Article 6 p. Text http://digital.library.unt.edu/ark:/67531/metadc83320/ ark: ark:/67531/metadc83320 Proceedings of the National Academy of Sciences (U.S.), 1999, Washington DC: National Academy of Sciences (U.S.), pp. 3507-3512 English Public

info:ark/67531/metadc83322 2012-12-21T13:01:35Z partner:UNTCAS collection:UNTSW access_rights:public

[Review] A Grammar of Mongsen Ao Chelliah, Shobhana L. linguistics languages Mongsen Ao grammar phonology This book review discusses 'A Grammar of Mongsen Ao' by Alec R. Coupe. Ao is one of the approximately 20 indigenous languages of Nagaland spoken in around fifty villages in northwestern area of the state. This book reviews discusses each of the eleven chapters in the book. University of California Santa Barbara 2010 Review 9 p. Text http://digital.library.unt.edu/ark:/67531/metadc83322/ ark: ark:/67531/metadc83322 Himalayan Linguistics, 2010, Santa Barbara: University of California Santa Barbara, pp. 1-9 English Public

info:ark/67531/metadc83330 2013-04-17T10:42:30Z partner:UNTCAS collection:UNTSW access_rights:public

Rational Design of Macrometallocyclic Trinuclear Complexes with Superior π-Acidity and π-Basicity Tekarli, Sammer M. Cundari, Thomas R., 1964- Omary, Mohammad A. density functional theory π-acidity π-basicity organic compounds This article discusses the rational design of macrometallocyclic trinuclear complexes with superior π-acidity and π-basicity. Density functional theory (DFT) has been used to assess the π-acidity and π-basicity of metal-organic trimetallic macromolecular complexes of the type [M(µ-L)]3, where M = Cu, Ag, or Au and L = carbeniate, imidazolate, pyridiniate, pyrazolate, or triazolate. The organic compounds benzene, triazole, imidazole, pyrazole, and pyridine were also modeled, and their substituent effects were compared to those of the coinage metal trimers. Our results, based on molecular electrostatic potential surfaces and positive charge attraction energy curves, indicate that the metal-organic macromolecules show superior π-acidity and -basicity compared to their organic counterparts. Moreover, the metal-organic cyclic trimers are found to exhibit π-acidity and -basicity that can be systematically tuned both coarsely and finely by judicious variation of the bridging ligand (relative π-basicity imidazolate > pyridiniate > carbeniate > pyrazolate > triazolate), metal (relative π-basicity Au > Cu > Ag), and ligand substituents. These computational findings are thus guiding experimental efforts to rationally design novel [M(µ-L)]3 materials for applications in molecular electronic devices that include metal-organic field-effect transistors and light-emitting diodes. American Chemical Society 2008 Article 7 p. Text doi: 10.1021/ja076527u http://digital.library.unt.edu/ark:/67531/metadc83330/ ark: ark:/67531/metadc83330 Journal of the American Chemical Society, 2008, Washington DC: American Chemical Society, pp. 1669-1675 English Public

info:ark/67531/metadc83332 2013-04-17T10:35:40Z partner:UNTCAS collection:UNTSW access_rights:public

Combined Experimental and Computational Studies on the Nature of Aromatic C-H Activation by Octahedral Ruthenium(II) Complexes: Evidence for σ-Bond Metathesis from Hammett Studies DeYonker, Nathan J. Foley, Nicholas A. Cundari, Thomas R., 1964- Gunnoe, T. Brent Petersen, Jeffrey L. octahedral ruthenium Hammett correlatioin arene C-H bonds This article discusses combined experimental and computational studies on the nature of aromatic C-H activation by octahedral ruthenium(II) complexes. Abstract: Octahedral ruthenium complexes of the type TpRu(L)(NCMe)R [Tp = hydridotris(pyrazolyl)borate; R = alkyl or aryl; L = CO or PMe3] have been shown previously to initiate the C-H activation of aromatic substrates. In order to probe the nature of the C-H activation step, reaction rates have been theoretically obtained for the conversion of TpRu(L)(ƞ2-C,C-C6H5X)Me to TpRu(L)(ρ-C6H4X) and CH4 where X is varied among Br, Cl, CN, F, H, NH2, NO2, and OMe. A linear Hammett correlation is calculated with a positive ρ value of 2.6 for L = CO and 3.2 for L = PMe3. Calculated kinetic data for the aromatic C-H activations indicate that an electrophilic aromatic substitution mechanism is unlikely. While experiments cannot fully replicate the entire range of calculated Hammett plots, reactivity trends are consistent with the calculations that suggest activation barriers to overall metal-mediated arene C-H bond cleavage are reduced by the presence of electron-withdrawing groups in the position para to the site of activation. Previous mechanistic studies, as well as the structure and imaginary vibrational modes of the present transition states, validate that the C-H activation for this family of TpRu complexes occurs through a σ-bond metathesis-type pathway. American Chemical Society 2007-11-27 Article 8 p. Text doi: 10.1021/om7009057 http://digital.library.unt.edu/ark:/67531/metadc83332/ ark: ark:/67531/metadc83332 Organometallics, 2007, Washington DC: American Chemical Society, pp. 6604-6611 English Public

info:ark/67531/metadc83795 2013-03-20T11:11:49Z partner:UNTCAS collection:UNTSW access_rights:public

Comment on "Modification of graphene properties due to electron-beam irradiation" Jones, Jason D. Ecton, Philip A. Mo, Yudong Pérez, José M. scanning electron microscopes graphenes electron-beam irradiations This article is a comment on another article titled 'Modification of graphene properties due to electron-beam irradiation'. These articles discuss the modification of graphene properties due to electron-beam irradiation. American Institute of Physics 2009-12-17 Article 2 p. Text doi: 10.1063/1.3272954 http://digital.library.unt.edu/ark:/67531/metadc83795/ ark: ark:/67531/metadc83795 Applied Physics Letters, 2009, College Park: American Institute of Physics English Public

info:ark/67531/metadc83792 2013-03-11T15:23:38Z partner:UNTCAS collection:UNTSW access_rights:public

The 2012 Republican Primaries UNT Speaks Out Eshbaugh-Soha, Matthew politics political parties delegates elections voting This presentation is part of the faculty lecture series UNT Speaks Out on the 2012 Presidential Primaries. In this presentation, the author gives the audience an overview of the structure of the primaries, and provides a recap of past primaries. The author also speaks about the money, momentum, and media attention in the primaries. University of North Texas. Libraries. 2012-04-24 Presentation 14 p. Image http://digital.library.unt.edu/ark:/67531/metadc83792/ ark: ark:/67531/metadc83792 UNT Speaks Out on the 2012 Republican Primaries, 2012, Denton, Texas, United States English 2012 Presidential Primaries, ark:/67531/metadc83784 Public

info:ark/67531/metadc83788 2012-12-14T14:41:55Z partner:UNTCAS collection:UNTSW access_rights:public

Mediated Primaries UNT Speaks Out Lain, Brian elections politics rhetoric debates This presentation is part of the faculty lecture series UNT Speaks Out on the 2012 Presidential Primaries. In this presentation, the author uses his background in rhetoric and debate, as well as his interests in ideological criticism, and the politics of representation to comment on the candidates' rhetoric. UNT Libraries 2012-04-24 Presentation 13 p. Image http://digital.library.unt.edu/ark:/67531/metadc83788/ ark: ark:/67531/metadc83788 UNT Speaks Out on the 2012 Presidential Primaries, 2012, Denton, Texas, United States English 2012 Presidential Primaries, ark:/67531/metadc83784 Public

info:ark/67531/metadc83790 2012-12-14T16:09:43Z partner:UNTCAS collection:UNTSW access_rights:public

Racial and Ethnic Politics in the 2012 Presidential Primaries UNT Speaks Out Carey, Tony E. elections politics presidential primaries This presentation is part of the faculty lecture series UNT Speaks Out on the 2012 Presidential Primaries. In this presentation, the author discusses how members of different racial and ethnic backgrounds responded to the 2012 Republican primary candidates. UNT Libraries 2012-04-24 Presentation 12 p. Image http://digital.library.unt.edu/ark:/67531/metadc83790/ ark: ark:/67531/metadc83790 UNT Speaks Out on the 2012 Presidential Primaries, 2012, Denton, Texas, United States English 2012 Presidential Primaries, ark:/67531/metadc83784 Public

info:ark/67531/metadc83797 2012-12-12T14:33:55Z partner:UNTCAS collection:UNTSW access_rights:public

Mapping Texts: Combining Text-Mining and Geo-Visualization To Unlock The Research Potential of Historical Newspapers Mapping Texts Torget, Andrew J. Mihalcea, Rada Christensen, Jon McGhee, Geoff text-mining geo-visualization newspapers historical documents This paper discusses a grant project to develop a series of experimental models for combining possibilities of text-mining with geospatial mapping in order to unlock the research potential of large-scale collections of historical newspapers. This paper documents the experiments and their outcomes, as well as the authors' recommendations for future work. National Endowment for the Humanities 2011 Paper 53 p. Text grantno: HD-51188-10 http://digital.library.unt.edu/ark:/67531/metadc83797/ ark: ark:/67531/metadc83797 National Endowment for the Humanities Level II Digital Humanities Start-Up Grant English Public

info:ark/67531/metadc83794 2012-05-14T15:40:27Z partner:UNTCAS collection:UNTSW access_rights:public

Atomic structure of steps and defects on the clean diamond (100)-2 X 1 surface studied using ultrahigh vacuum scanning tunneling microscopy Stallcup, Richard E. Pérez, José M. scanning tunneling microscopy chemical vapor depositions atomic structures In this article, the authors report ultrahigh vacuum scanning tunneling microscopy studies of the clean nonhydrogen-terminated diamond (100)-2 X 1 surface showing single- and double-layer steps that are rebonded. The main defects observed are single, multiple, and row dimer vacancies, and antiphase boundaries. Buckling of dimers is not observed, consistent with symmetric dimers. American Institute of Physics 2002-12-09 Article 3 p. Text doi: 10.1063/1.1527697 http://digital.library.unt.edu/ark:/67531/metadc83794/ ark: ark:/67531/metadc83794 Applied Physics Letters, 2002, College Park: American Institute of Physics, pp. 4538-4540 English Public

info:ark/67531/metadc83799 2012-12-07T13:58:40Z partner:UNTCAS collection:UNTSW access_rights:public

Topic Modeling on Historical Newspapers Yang, Tze-I Torget, Andrew J. Mihalcea, Rada newspapers historians automatic text processing In this paper, the authors explore the task of automatic text processing applied to collections of historical newspapers, with the aim of assisting historical research. In particular, in this first stage of the project, the authors experiment with the use of topical models as a means to identify potential issues of interest for historians. Association for Computational Linguistics (ACL) 2011-06 Paper 9 p. Text http://digital.library.unt.edu/ark:/67531/metadc83799/ ark: ark:/67531/metadc83799 Association for Computational Linguistics (ACL) Workshop on Language Technology for Cultural Heritage, Social Sciences, and Humanities (LATECH), 2011, Portland, Oregon, United States English Public

info:ark/67531/metadc84149 2013-03-19T15:29:00Z partner:UNTCAS collection:UNTSW access_rights:public

Control of chaos in a CO2 laser Pérez, José M. Steinshnider, J. Stallcup, Richard E. Aviles, A. F. carbon dioxide lasers chaotic systems feedback stabilization instability pulse techniques This article discusses the control of chaos in a CO2 laser. Abstract: We report the experimental control of chaos in an optically modulated CO2 laser. The CO2 laser was driven into chaos by injecting a feedback beam modulated by an electro-optical modulator. Control of chaos was achieved using a modified proportional feedback technique in which the control pulses were delayed by approximately one relaxation period. Using this technique, it was possible to control unstable periodic orbits up to period 6. American Institute of Physics 1994-09-05 Article 3 p. Text doi: 10.1063/1.112075 http://digital.library.unt.edu/ark:/67531/metadc84149/ ark: ark:/67531/metadc84149 Applied Physics Letters, 1994, College Park: American Institute of Physics, pp. 1216-1218 English Public

info:ark/67531/metadc84147 2013-03-13T16:49:09Z partner:UNTCAS collection:UNTSW access_rights:public

Atomic resolution ultrahigh vacuum scanning tunneling microscopy of epitaxial diamond (100) films Stallcup, Richard E. Aviles, A. F. Pérez, José M. diamonds chemical vapor deposition morphology surface structures surface reconstruction STM epitaxial layers In this article, the authors report atomic resolution images of chemical vapor deposition grown epitaxial diamond (100) films obtained in ultrahigh vacuum (UHV) with a scanning tunneling microscope. A (2X1) dimer surface reconstruction and amorphous atomic regions are observed. The (2X1) unit cell is measured to be 0.51±0.01X0.25±0.01 nm2. The amorphous regions are identified as carbon. A radial structure 1.5 nm in diameter is observed on a plane at a 20° slope to the (2X1) surface. Tunneling current versus voltage spectra in UHV and Raman spectra are also obtained. American Institute of Physics 1995-05-01 Article 4 p. Text doi: 10.1063/1.113973 http://digital.library.unt.edu/ark:/67531/metadc84147/ ark: ark:/67531/metadc84147 Applied Physics Letters, 1995, College Park: American Institute of Physics, pp. 2331-2333 English Public

info:ark/67531/metadc84154 2012-12-06T16:24:31Z partner:UNTCAS collection:UNTSW access_rights:public

Nucleation of β-FeSi2 nanostructures at pinned step bunches on the Si(111) surface Brady, Ryan P. Sharma, A.S. Giblet, R.L. Cottier, Ryan J. Golding, Terry D. Pérez, José M. nanostructured materials iron compounds nanotechnology nucleation annealing surface topography scanning tunnelling microscopy atomic force microscopy semiconductor materials In this article, the authors report the preferential nucleation and synthesis of β-FeSi2 nanostructures at pinned step bunches on the Si(111) surface. The nanostructures are synthesized by depositing Fe on Si at room temperature and subsequent annealing. The surface topography is studied using scanning tunneling microscopy and atomic force microscopy. The size, shape and orientation of the nanostructures indicate that the phase is the semiconducting β-FeSi2 phase. American Institute of Physics 2005-05-24 Article 3 p. Text doi: 10.1063/1.1940128 http://digital.library.unt.edu/ark:/67531/metadc84154/ ark: ark:/67531/metadc84154 Applied Physics Letters, 2005, College Park: American Institute of Physics English Public

info:ark/67531/metadc84157 2012-12-07T11:55:34Z partner:UNTCAS collection:UNTSW access_rights:public

Scanning Tunneling Microscopy Studies of Temperature-Dependent Etching of Diamond (100) by Atomic Hydrogen Stallcup, Richard E. Pérez, José M. temperature-dependent etching atomic hydrogen scanning tunneling microscopy In this article, the authors present a technique for obtaining atomic resolution ultrahigh vacuum scanning tunneling microscopy images of diamond (100) films by atomic hydrogen. The authors find that etching by atomic hydrogen is highly temperature dependent, resulting in a rough and pitted surface at T ≈ 200 and 500˚C, respectively. At T ≈ 1000˚C etching results in a smooth surface and is highly anisotropic, occurring predominantly in the direction of dimer rows. This observation supports recent theoretical models that propose anisotropic etching as the mechanism for the growth of smooth diamond (100) films. American Physical Society 2001-04-09 Article 4 p. Text doi: 10.1103/PhysRevLett.86.3368 http://digital.library.unt.edu/ark:/67531/metadc84157/ ark: ark:/67531/metadc84157 Physical Review Letters, 2001, College Park: American Physical Society, pp. 3368-3371 English Public

info:ark/67531/metadc84153 2012-12-06T13:11:51Z partner:UNTCAS collection:UNTSW access_rights:public

Nanoparticle-assisted microwave absorption by single-wall carbon nanotubes Wadhawan, Atul Garrett, David Pérez, José M. iron catalysts radiation effects nanoparticles electromagnetic wave absorption In this article, the authors report the effects of microwave irradiation on both unpurified and purified iron-catalyzed high-pressure disproportionation (HiPco)-grown single-walled carbon nanotubes (SWNTs) in ultrahigh vacuum. Under microwave irradiation, the authors observe that unpurified HiPco SWNTs quickly reach temperatures of approximately 1850 ºC. As a result, H2, H2O, CO, CO2, and CH4 gases are observed, and the Fe catalyst nanoparticles melt and coalesce into larger crystallites approximately four times their original diameter. In contrast, carbon black and purified HiPco SWNTs heat up to temperatures of 500-650 ºC. The authors propose that the significant heating of unpurified HiPco SWNTs is due to the Fe catalysts. American Institute of Physics 2003-09-29 Article 3 p. Text doi: 10.1063/1.1615679 http://digital.library.unt.edu/ark:/67531/metadc84153/ ark: ark:/67531/metadc84153 Applied Physics Letters, 2003, College Park: American Institute of Physics, pp. 2683-2685 English Public

info:ark/67531/metadc84148 2013-04-01T17:14:49Z partner:UNTCAS collection:UNTSW access_rights:public

Effects of Cs deposition on the field-emission properties of single-walled carbon-nanotube bundles Wadhawan, Atul Stallcup, Richard E. Pérez, José M. carbon nanotubes electron field emissions adsorption tunnelling surface states caesium vacuum microelectronics This article discusses the effects of Cs deposition on the field-emission properties of single-walled carbon-nanotube bundles. Abstract: We report the effects of Cs deposition on the field-emission (FE) properties of single-walled carbon-nanotube bundles. We observe that Cs deposition decreases the turn-on field for FE by a factor of 2.1-2.8 and increases the FE current by six orders of magnitude. After Cs deposition, the FE current versus voltage (I-V) curves show non-Fowler-Nordheim behavior at large currents, consistent with tunneling from adsorbate states. At lower currents, the ratio of the slope of the FE I-V curves before and after Cs deposition is approximately 2.1. Exposure to N2 does not decrease the FE current, while exposure to O2 decreases the FE current. American Institute of Physics 2001-01-01 Article 3 p. Text doi: 10.1063/1.1338493 http://digital.library.unt.edu/ark:/67531/metadc84148/ ark: ark:/67531/metadc84148 Applied Physics Letters, 2001, College Park: American Institute of Physics, pp. 108-110 English Public

info:ark/67531/metadc84150 2013-04-01T17:38:08Z partner:UNTCAS collection:UNTSW access_rights:public

Effects of O2, Ar, and H2 gases on the field-emission properties of single-walled and multiwalled carbon nanotubes Wadhawan, Atul Stallcup, Richard E. Stephens, Kenneth F. Pérez, José M. Akwani, Ikerionwu A. carbon nanotubes electron field emissions oxygen argon hydrogen In this article, the authors compare the effects of O2, Ar, and H2 gases on the field-emission (FE) properties of single-walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes (MWNTs). The authors find that H2 and Ar gases do not significantly affect the FE properties of SWNTs or MWNTs. O2 temporarily reduces the FE current and increases the turn-on voltages in an O2 environment cause a permanent decrease of the FE current and an increase in the turn-on field of MWNTs. The ratios of the slopes before and after O2 exposure are approximately 1.04 and 0.82 for SWNTs and MWNTs, respectively. American Institute of Physics 2001-09-17 Article 3 p. Text doi: 10.1063/1.1401785 http://digital.library.unt.edu/ark:/67531/metadc84150/ ark: ark:/67531/metadc84150 Applied Physics Letters, 2001, College Park: American Institute of Physics, pp. 1867-1869 English Public

info:ark/67531/metadc84151 2013-04-01T17:41:39Z partner:UNTCAS collection:UNTSW access_rights:public

Effects of O2, H2, and N2 gases on the field emission properties of diamond-coated microtips Lim, Seong-Chu Stallcup, Richard E. Akwani, Ikerionwu A. Pérez, José M. molybdenum electron field emissions vacuum microelectronics scanning tunnelling microscopy etching diamonds CVD coatings This article discusses the effects of O2, H2, and N2 gases on the field emission properties of diamond-coated microtips. Abstract: We report the effects of O2, H2, and N2 residual gases on the field emission properties of uncoated and diamond-coated individual Mo microtips. The microtips are made using electrochemical etching techniques and positioned 5 µm from the anode using a scanning tunneling microscopy system. The authors observe that the field emission (FE) current and turn-on voltage of diamond-coated microtips are significantly less degraded by O2 exposure that those of uncoated Mo microtips. H2 exposure enhances the FE properties of both uncoated and diamond-coated microtips, while N2 exposure does not have any significant effect. American Institute of Physics 1999-08-23 Article 3 p. Text doi: 10.1063/1.124636 http://digital.library.unt.edu/ark:/67531/metadc84151/ ark: ark:/67531/metadc84151 Applied Physics Letters, 1999, College Park: American Institute of Physics, pp. 1179-1181 English Public

info:ark/67531/metadc84155 2012-12-06T16:30:53Z partner:UNTCAS collection:UNTSW access_rights:public

On the mechanism for plasma hydrogenation of graphene Jones, Jason D. Hoffmann, William D. Jesseph, Aaron V. Morris, Christopher Verbeck, Guido F. Pérez, José M. graphene hydrogen compounds hydrogenation In this article, the authors report that hydrogenation of mono-, bi-, and trilayer graphene samples via exposure to H2 plasma occurs as a result of electron irradiation of H2O adsorbates on the samples, rather than H species in the plasma as reported by [Elias et al., Science 323, 610 (2009)]. The authors propose that the hydrogenation mechanism is electron-impact fragmentation of H2O adsorbates into H+ ions. At incident electron energies >60 eV, the authors observe hydrogenation that is significantly more stable at temperatures >200 ºC than previously reported. American Institute of Physics 2010-12-06 Article 4 p. Text doi: 10.1063/1.3524517 http://digital.library.unt.edu/ark:/67531/metadc84155/ ark: ark:/67531/metadc84155 Applied Physics Letters, 2010, College Park: American Institute of Physics English Public

info:ark/67531/metadc84143 2012-12-17T16:20:58Z partner:UNTCAS collection:UNTSW access_rights:public

Mock Trial on Stalin and Stalinism University Forum on Teaching & Learning (UFTL) Velikanova, Olga V. Stalin mock trials education This poster describes an experiential learning activity for the UNT course History 5040, Historiography of Stalinism. The goal is to apply critical reasoning to Stalin's politics in a courtroom environment. Center for Distributive Learning at University of North Texas (CLEAR) 2012-03-28 Poster 1 p. Image http://digital.library.unt.edu/ark:/67531/metadc84143/ ark: ark:/67531/metadc84143 University Forum on Teaching and Learning (UFTL), 2012, Denton, Texas, United States English Public

info:ark/67531/metadc84146 2012-12-17T16:57:42Z partner:UNTCAS collection:UNTSW access_rights:public

Teaching French Verbal Aspect through Concept-Based Instruction University Forum on Teaching & Learning (UFTL) Williams, Lawrence verbal aspects languages concept-based instructions This poster describes a pilot study on teaching French verbal aspect through concept-based instruction. This poster outlines and describes the background and context of a verbal aspect, the tasks and assessments for the study, student learning outcomes, the theoretical framework, and the results of the study. Center for Distributive Learning at University of North Texas (CLEAR) 2012-03-28 Poster 1 p. Image http://digital.library.unt.edu/ark:/67531/metadc84146/ ark: ark:/67531/metadc84146 University Forum on Teaching and Learning (UFTL), 2012, Denton, Texas, United States English Public

info:ark/67531/metadc84145 2012-12-17T17:11:02Z partner:UNTCAS collection:UNTSW access_rights:public

Using Calibrated Peer Review to Facilitate Writing Assignments in Large Classes University Forum on Teaching & Learning (UFTL) Ishiyama, John Watson, Wendy calibrated peer review writing essays This poster discusses a project using Calibrated Peer Review (CPR). CPR is a web-based instructional tool. CPR assignments require students to write an essay, evaluated three 'canned' calibration essays on the same topic, evaluate three of their peers' essays, and finally evaluate their own essay. The authors' goal was to determine whether the CPR process improves student learning of the essay content and whether the CPR process improves student writing. Center for Distributive Learning at University of North Texas (CLEAR) 2012-03-28 Poster 1 p. Image http://digital.library.unt.edu/ark:/67531/metadc84145/ ark: ark:/67531/metadc84145 University Forum on Teaching and Learning (UFTL), 2012, Denton, Texas, United States English Public

info:ark/67531/metadc84135 2013-04-16T12:06:01Z partner:UNTCAS collection:UNTSW access_rights:public

Gender and globalization through film: A Wiki course University Forum on Teaching & Learning (UFTL) Altiok, Özlem gender globalization films This poster discusses a learning activity with a Wiki course on gender and globalization through film. The course aims to help students understand how existing gender inequalities are challenged and furthered by processes of international development and globalization. Center for Distributive Learning at University of North Texas 2012-03-28 Poster 1 p. Image http://digital.library.unt.edu/ark:/67531/metadc84135/ ark: ark:/67531/metadc84135 University Forum on Teaching and Learning (UFTL), 2012, Denton, Texas, United States English Public

info:ark/67531/metadc84142 2013-04-25T15:51:41Z partner:UNTCAS collection:UNTSW access_rights:public

History 4263: Palestinian History University Forum on Teaching & Learning (UFTL) Stockdale, Nancy L. Palestinian histories group projects historical cases This poster discusses a project for a UNT history course, History 4263, on Palestinian history. In the course, students explore historical foundations and interpretations of modern Palestinian history. Center for Distributive Learning at University of North Texas 2012-03-28 Poster 1 p. Image http://digital.library.unt.edu/ark:/67531/metadc84142/ ark: ark:/67531/metadc84142 University Forum on Teaching and Learning (UFTL), 2012, Denton, Texas, United States English Public

info:ark/67531/metadc84328 2013-04-01T11:28:16Z partner:UNTCAS collection:UNTSW access_rights:public

Does open access really threaten peer review? Holbrook, J. Britt open access peer reviews scholarly communication publishing In this paper, the author discusses whether open access threatens peer review, as implied by the Association of American Publishers in their endorsement of the Research Works Act. The author suggests that we need to experiment with new models of peer evaluation. 2012-01-11 Paper 3 p. Text http://digital.library.unt.edu/ark:/67531/metadc84328/ ark: ark:/67531/metadc84328 University of North Texas. Center for the Study of Interdisciplinarity, 2012 English Public

info:ark/67531/metadc84349 2012-12-07T14:53:55Z partner:UNTCAS collection:UNTSW access_rights:public

The Use Of Societal Impacts Considerations In Grant Proposal Peer Review: A Comparison Of Five Models Holbrook, J. Britt peer review societal impacts accountability expertise This article discusses the use of societal impacts considerations in grant proposal peer review. Increasing demands on the part of the public for a demonstrable return on their investment in scientific and technical research have led to the widespread introduction of considerations of societal impacts into the peer review processes at public science and technology funding agencies. This answer to the accountability challenge also introduces a peculiar strain on peer review: expertise in particular areas of scientific and technical research is no guarantee of expertise in addressing the societal impacts of proposed research. Presenting preliminary results of a larger study, this article describes five current models of the peer review of grant proposals and shows that different agencies have very different ways of incorporating societal impacts considerations. The article also elucidates a notion of theoretical adequacy, which will be used to determine whether and how some peer review processes are better than others. The objectives of this article are to lay out the description of the agencies and to offer a preliminary assessment of each model's theoretical adequacy. The objective of the authors' larger study is to determine the best ways to incorporate societal impacts considerations into the peer review of grant proposals, thus helping funding agencies respond to the demand for demonstrable results. Cognizant Communication Corporation 2010 Article 12 p. Text doi: 10.3727/194982410X12895770314078 http://digital.library.unt.edu/ark:/67531/metadc84349/ ark: ark:/67531/metadc84349 Technology and Innovation, 2010, Putnam Valley: Cognizant Communications Corporation, pp. 213-224 English Public

info:ark/67531/metadc84353 2012-12-12T16:40:39Z partner:UNTCAS collection:UNTSW access_rights:public

Philosophy Matters - Examining the Value of Knowledge Frodeman, Robert Holbrook, J. Britt impacts peer review knowledge value This paper discusses the University of North Texas' (UNT) Center for the Study of Interdisciplinarity (CSID), where philosophers continue to examine the value of knowledge. The authors also discuss one example of CSID's work with the Comparative Assessment of Peer Review (CAPR) project. CAPR is a four-year project (2008-2012) studying the changing nature of peer review processes across six U.S. and foreign public science agencies. CAPR is funded by the U.S. National Science Foundation's (NSF) Science of Science and Innovation Policy (SciSIP) program. 2012-05-10 Paper 6 p. Text http://digital.library.unt.edu/ark:/67531/metadc84353/ ark: ark:/67531/metadc84353 UNT Research and Economic Development, 2012 English Public

info:ark/67531/metadc84327 2013-03-28T12:35:50Z partner:UNTCAS collection:UNTSW access_rights:public

Direct evidence for the amorphous silicon phase in visible photoluminescent porous silicon Pérez, José M. Villalobos, J. McNeill, P. Prasad, J. Cheek, R. Kelber, J. Estrera, J. P. Stevens, P. D. Glosser, R. silicon porous materials photoluminescence phase studies Raman spectroscopy microanalysis photoelectron spectroscopy silicon oxides amorphous states This article discusses direct evidence for the amorphous silicon phase in visible photoluminescent porous silicon. Abstract: We report on micro-Raman spectroscopy studies of porous silicon which show an amorphous silicon Raman line at 480 R cm-1 from regions that emit visible photoluminescence. A Raman line corresponding to microcrystalline silicon at 510 R cm-1 is also observed. X-ray photoelectron spectroscopy data is presented which shows a high silicon-dioxide content in porous silicon consistent with an amorphous silicon phase. American Institute of Physics 1992-08-03 Article 4 p. Text doi: 10.1063/1.107837 http://digital.library.unt.edu/ark:/67531/metadc84327/ ark: ark:/67531/metadc84327 Applied Physics Letters, 1992, College Park: American Institute of Physics, pp. 563-565 English Public

info:ark/67531/metadc84361 2012-05-18T10:45:38Z partner:UNTCAS collection:UNTSW access_rights:public

Scanning tunneling microscopy of the electronic structure of chemical vapor deposited diamond films Pérez, José M. Lin, C. Rivera, W. Hyer, R.C. Green, M. Sharma, S.C. Chopra, D.R. Chourasia, A.R. diamonds chemical vapor deposition scanning tunneling microscopy IV characteristics surface states band structures morphology crystal structures plasma productions This article discusses scanning tunneling microscopy of the electronic structure of chemical vapor deposited diamond films. Scanning tunneling microscopy has been used to characterize the electronic structure and surface morphology of diamond films grown using the hot filament and microwave plasma chemical vapor deposition techniques. The authors observe a significant difference between the current-voltage (I-V) curves for the two types of films. The I-V curves for the hot-filament grown films are characterized by a well-defined zero-current region from which a surface band gap of 4.1 eV is measured. The I-V curves for the microwave plasma grown films exhibit a rectifying behavior which can be modeled by surface band bending. The authors compare the surface density of states obtained from the I-V curves with those obtained from x-ray photoelectron and appearance potential spectroscopies. American Institute of Physics 1993-04-19 Article 4 p. Text doi: 10.1063/1.109533 http://digital.library.unt.edu/ark:/67531/metadc84361/ ark: ark:/67531/metadc84361 Applied Physics Letters, 1993, College Park: American Institute of Physics, pp. 1889-1891 English Public

info:ark/67531/metadc84367 2012-05-18T10:45:38Z partner:UNTCAS collection:UNTSW access_rights:public

Nanotubes in Microwave Fields: Light Emission, Intense Heat, Outgassing, and Reconstruction Imholt, Timothy Dyke, Christopher A. Hasslacher, Brosl Pérez, José M. Price, D.W. Roberts, Jim Scott, J.B. Wadhawan, Atul Ye, Z. Tour, James M. single-walled carbon nanotubes SWNTs microwave absorption light emissions outgassing This article discusses nanotubes in microwave fields. Single-walled carbon nanotubes (SWNTs) exhibit diverse and unique properties. Recently, a surprising feature has been the ignition of nanotubes in the presence of an ordinary camera flash. Here, the authors report that SWNTs, produced via the HiPco process, display strong microwave absorption (1.01 x 10⁻⁵ eV microwave field) with subsequent dramatic light emission, intense heat release, outgassing, and nanotube reconstruction. American Chemical Society 2003-09-27 Article 2 p. Text doi: 10.1021/cm034530g http://digital.library.unt.edu/ark:/67531/metadc84367/ ark: ark:/67531/metadc84367 Chemistry of Materials, 2003, Washington DC: American Chemical Society, pp. 3969-3970 English Public

info:ark/67531/metadc84364 2012-05-18T10:45:38Z partner:UNTCAS collection:UNTSW access_rights:public

The observation of silicon nanocrystals in siloxene Pinizzotto, Russell F. Yang, H. Pérez, José M. Coffer, J.L. silicon nanostructures TEM microstructures amorphous states high-resolution methods In this article, the authors report the direct observation of silicon nanocrystals in unannealed siloxene using high resolution transmission electron microscopy. The microstructure consists of an amorphous matrix plus silicon crystallites with dimensions of a few nanometers. This is additional evidence that the photoluminescence of silicon-based materials is due to quantum confinement. American Institute of Physics 1994-05-01 Article 4 p. Text doi: 10.1063/1.355938 http://digital.library.unt.edu/ark:/67531/metadc84364/ ark: ark:/67531/metadc84364 Journal of Applied Physics, 1994, College Park: American Institute of Physics, pp. 4486-4488 English Public

info:ark/67531/metadc84357 2012-12-07T11:19:38Z partner:UNTCAS collection:UNTSW access_rights:public

Resistance to impact criteria can lead to a tightening of the accountability noose Holbrook, J. Britt Frodeman, Robert impacts peer review autonomy accountability This article discusses how resistance to impact criteria can lead to a tightening of the accountability noose. Vague impact criteria are a blessing in disguise. The authors write that researchers who push against criteria that allow considerable autonomy are foolish and should learn from overseas contemporaries that a clearer definition of impact requirements is not dissimilar from a tightening of the noose. London School of Economics and Political Science (LSE) 2012-03-15 Article 3 p. Text http://digital.library.unt.edu/ark:/67531/metadc84357/ ark: ark:/67531/metadc84357 Impact of Social Sciences blog, 2012 English Public

info:ark/67531/metadc84363 2012-12-21T10:58:01Z partner:UNTCAS collection:UNTSW access_rights:public

The Promise and Perils of Transformative Research Frodeman, Robert Holbrook, J. Britt science policies transformative research Kuhn This report is on the workshop 'Transformative Research: Ethical and Societal Implications'. Workshop conversations cluster under the four headings of the history and definitions, promotion, evaluation, and integration of transformative research (TR): 1. History and Definitions: The National Science Board's 2007 report (NSB-07-32) on transformative research called for more effort directed at defining TR. The present report offers additional context and clarity regarding meanings of the term. But it also argues that there are virtues in leaving the term open to multiple interpretations. 2. Promotion: The report welcomes new mechanisms for promoting TR, such as NSF 'CREATIV' grants. It embraces additional means for promoting TR, such as increased emphasis on interdisciplinary research, and explores how different interpretations of how TR occurs imply different strategies for promoting TR. It also calls for increased attention to the broader societal impacts of TR at the levels of policy, of NSF programs, and of individual research projects. 3. Evaluation: The report emphasizes the need to develop means for evaluating attempts to promote TR. It also concludes that research should be directed toward evaluating transformative research at the project level. 4. Integration: The report suggests that consideration of the broader societal impacts of TR be fully integrated with transformative research itself. Attention to the broader impacts of TR should inform the development of policies and programs designed to promote TR, for instance through the creation of mechanisms such as an Advisory Committee for Transformative Research (ACTR). U.S. National Science Foundation (NSF) 2012-03 Report 54 p. Text http://digital.library.unt.edu/ark:/67531/metadc84363/ ark: ark:/67531/metadc84363 Workshop on Transformative Research: Social and Ethical Implications, 2012, Arlington, Virginia, United States English Public

info:ark/67531/metadc84334 2013-04-25T10:52:01Z partner:UNTCAS collection:UNTSW access_rights:public

Good Transformations: Ambiguity and the NSF's Experiment with 'Transformative' Research Holbrook, J. Britt Barr, Kelli Frodeman, Robert transformative research peer review science policies This article discusses a recent workshop on Transformative Research held at the headquarters of the U.S. National Science Foundation (NSF) in Arlington, Virginia. The authors led the two-day workshop to once again raise the question of the meaning of "transformative research" (TR). TR has come to encapsulate an increasingly central question across both U.S. and foreign science agencies: In a hypercompetitive global economy, with pressing challenges in many areas (energy, food, water, disease, etc.), how can we do a better job of picking research projects that are true game changers? Center for American Progress 2012-03-22 Article 3 p. Text http://digital.library.unt.edu/ark:/67531/metadc84334/ ark: ark:/67531/metadc84334 Science Progress, 2012, Washington DC: Center for American Progress English Public

info:ark/67531/metadc86163 2013-03-11T16:58:22Z partner:UNTCAS collection:UNTSW access_rights:public

Accountable Science: The COMPETES Act Needs to Demonstrate an Accountability Attitude Holbrook, J. Britt science policies accountability autonomy This article discusses the U.S. National Science Foundation's (NSF) Broader Impacts Merit Review Criterion in relation to the America COMPETES Reauthorization Act of 2010. Center for American Progress 2010-09-16 Article 5 p. Text http://digital.library.unt.edu/ark:/67531/metadc86163/ ark: ark:/67531/metadc86163 Science Progress, 2010, Washington DC: Center for American Progress English Public

info:ark/67531/metadc86179 2013-03-19T13:15:20Z partner:UNTCAS collection:UNTSW access_rights:public

Comparative Assessment of Peer Review (CAPR): EU/US workshop on peer review: Assessing "broader impact" in research grant applications Holbrook, J. Britt Frodeman, Robert peer review digital repositories research European Commission grant applications This is the report of a workshop focusing on the use of broader societal impacts criteria as part of the review process at the European Commission. There is both a historical account and some thinking about how 'impact' ought to be incorporated into Horizon 2020 (the funding scheme formerly known as FP8). Since the US NSF is also currently rethinking the details of its merit review process, and since there is an interesting comparison between NSF's and the EC's approaches to impact, the authors have also included a focus on NSF's Broader Impacts Criterion. The workshop was both a research opportunity (under SciSIP grant #0830387) and an effort to use that research to help inform policy for science (in terms of informing peer review models). European Commission. Directorate General for Research 2010-12 Report Text http://digital.library.unt.edu/ark:/67531/metadc86179/ ark: ark:/67531/metadc86179 EU-US Workshop on Peer Review: Assessing "Broader Impact" in Research Grant Applications, 2010, Brussels, Belgium English Public

info:ark/67531/metadc86186 2012-12-07T11:56:25Z partner:UNTCAS collection:UNTSW access_rights:public

Science: For Science's or Society's Sake? Owning the National Science Foundation's Broader Impacts Criterion Holbrook, J. Britt Frodeman, Robert science policies peer review impacts This article describes changes in the U.S. National Science Foundation's (NSF) merit review criteria. The authors argue that scientists are more likely to preserve their autonomy by embracing - or 'owning' - the new Broader Impacts Criterion rather than resisting it. Center for American Progress 2012-03-01 Article 4 p. Text http://digital.library.unt.edu/ark:/67531/metadc86186/ ark: ark:/67531/metadc86186 Science Progress, 2012, Washington DC: Center for American Progress English Public

info:ark/67531/metadc96837 2013-04-17T10:41:33Z partner:UNTCAS collection:UNTSW access_rights:public

Periodic and Molecular Modeling Study of Donor - Acceptor Interactions in (dbbpy)Pt(tdt) • TENF and [Pt(dbbpy)(tdt)]₂ • TENF Cundari, Thomas R., 1964- Chilukuri, Bhaskar Hudson, Joshua M. Minot, Christian Omary, Mohammad A. Rabaâ, Hassan Hückel tight binding EHTB analyses clusters TENF This article discusses a periodic and molecular modeling study. Supramolecular stacked materials (dbbpy)Pt(tdt)•TENF and [Pt(dbbpy)(tdt)]₂•TENF are built from (dbbpy)Pt(tdt) donors (D) with TENF acceptors (A) (TENF = 2,4,5,7-tetranitro-9-fluorenone; dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine; tdt = 3,4-toluenedithiolate). Simulations using extended Hückel tight binding (EHTB) and plane-wave DFT methods are performed. From EHTB analysis, the density of states (DOS) of D/A and DD/A stacks exhibit metallic behavior with a large contribution from TENF π in the valence band mixed with more significant Pt character in the D/A than in the DD/A stacks. DOS modification and charge transfer are estimated via analysis of the stacking sequences. Theoretical results from plane-wave DFT calculations give evidence of semimetallic behavior for the D/A material (gap < 0.1 eV) and metallic behavior for DD/A. Fragment analysis was performed, and similarities and differences between EHTB and DFT were noted. Molecular DFT computations suggest that the close (~3.6 Å) D-A distances are sufficient to allow some intermolecular donor-to-acceptor charge transfer and high interaction energy in DD/A than in D/A units, consistent with the periodic calculations for the solid-state stacks. Calculations of metric data via modeling of a (dbbpy)Pt(tdt)•TENF cluster as well as neutral, cationic, and anionic TENF are used to assess the fractional charge on TENF and hence the degree of D → A charge transfer. American Chemical Society 2010-01-15 Article 6 p. Text doi: 10.1021/om900696m http://digital.library.unt.edu/ark:/67531/metadc96837/ ark: ark:/67531/metadc96837 Organometallics, 2010, Washington DC: American Chemical Society, pp. 795-800 English Public

info:ark/67531/metadc97936 2013-03-19T14:57:02Z partner:UNTCAS collection:UNTSW access_rights:public

Construyendo una Red Chilena para Estudios Socioecológicos a Largo Plazo: Avances, enfoques y relevancia Building a Chilean Network for Long-Term Socio-Ecological Research: Advances, perspectives and relevance Sub-Antarctic Biocultural Conservation Program Anderson, Christopher B. Rozzi, Ricardo, 1960- Armesto, Juan J., 1953- Gutiérrez, Julio R., 1953- LTER LTSER South America subantarctic temperate This article discusses building a Chilean network for long-term socio-ecological research. Abstract: Since their formal inception in 1980, long-term ecological research (LTER) programs have served as a successful organizing framework to create research agendas and funding mechanisms that allow scientists to address meaningful ecological phenomena at the scales they occur. In its 30 years of existence, LTER has expanded its geographic range (currently the International LTER network has more than 40 country members with sites on every continent) and disciplinary foci (principally encompassing the natural and social sciences and leading some to call for a name change to long-term socio-ecological research efforts exist in both Chile and Argentina, and in 2008, the Institute of Ecology and Biodiversity launched Chile's first concerted effort to link three existing sites (Fray Jorge Forest National Park -33° S, Senda Darwin Biological Station - 43° S, and Omora Ethnobotanical Park - 55° S). Here, the authors present a special feature of the Revista Chilena de Historia Natural, dedicated to LTSER, with the aim of 1) providing a synthesis of some of the most emblematic cases of long-term socio-ecological research in Chile; 2) demonstrating the value of these efforts for the integration of research, education and social outcomes, such as decision making; and 3) offering the perspective of a broad array of participants involved in these initiatives, including graduate students with associated programs from Ibero-America and North America and North America. It is the authors' hope that these compiled works will contribute to the consolidation of the LTSER approach in southern South America both within the academic community and also to better link academia and society. Sociedad de Biología de Chile 2010 Article 12 p. Text http://digital.library.unt.edu/ark:/67531/metadc97936/ ark: ark:/67531/metadc97936 Revista Chilena de Historia Natural, 2010, Santiago: Sociedad de Biología de Chile, pp. 1-11 Spanish Building a Chilean Network for Long-Term Socio-Ecological Research: Advances, perspectives and relevance, ark:/67531/metadc97937 Public

info:ark/67531/metadc97937 2013-03-14T17:34:24Z partner:UNTCAS collection:UNTSW access_rights:public

Building a Chilean Network for Long-Term Socio-Ecological Research: Advances, perspectives and relevance Construyendo una Red Chilena para Estudios Socioecológicos a Largo Plazo: Avances , enfoques y relevancia Sub-Antarctic Biocultural Conservation Program Anderson, Christopher B. Rozzi, Ricardo, 1960- Armesto, Juan J. Gutiérrez, Julio R. LTER LTSER South America subantarctic temperate This article discusses building a Chilean network for long-term socio-ecological research. Abstract: Since their formal inception in 1980, long-term ecological research (LTER) programs have served as a successful organizing framework to create research agendas and funding mechanisms that allow scientists to address meaningful ecological phenomena at the scales they occur. In its 30 years of existence, LTER has expanded its geographic range (currently the International LTER network has more than 40 country members with sites on every continent) and disciplinary foci (principally encompassing the natural and social sciences and leading some to call for a name change to long-term socio-ecological research efforts exist in both Chile and Argentina, and in 2008, the Institute of Ecology and Biodiversity launched Chile's first concerted effort to link three existing sites (Fray Jorge Forest National Park -33° S, Senda Darwin Biological Station - 43° S, and Omora Ethnobotanical Park - 55° S). Here, the authors present a special feature of the Revista Chilena de Historia Natural, dedicated to LTSER, with the aim of 1) providing a synthesis of some of the most emblematic cases of long-term socio-ecological research in Chile; 2) demonstrating the value of these efforts for the integration of research, education and social outcomes, such as decision making; and 3) offering the perspective of a broad array of participants involved in these initiatives, including graduate students with associated programs from Ibero-America and North America and North America. It is the authors' hope that these compiled works will contribute to the consolidation of the LTSER approach in southern South America both within the academic community and also to better link academia and society. Sociedad de Biología de Chile 2010 Article 9 p. Text http://digital.library.unt.edu/ark:/67531/metadc97937/ ark: ark:/67531/metadc97937 Revista Chilena de Historia Natural, 2010, Santiago: Sociedad de Biología de Chile, pp. 1-12 English Construyendo una Red Chilena para Estudios Socioecológicos a Largo Plazo: Avances , enfoques y relevancia, ark:/67531/metadc97936 Public

info:ark/67531/metadc97943 2013-03-14T15:38:25Z partner:UNTCAS collection:UNTSW access_rights:public

Many Eyes on Nature: Diverse Perspectives in the Cape Horn Biosphere Reserve and their Relevance for Conservation Sub-Antarctic Biocultural Conservation Program Berghoefer, Uta Rozzi, Ricardo, 1960- Jax, Kurt biodiversity biosphere reserve Chile conflicts conservation local ecological knowledge participation protected areas valuation This article discusses research on diverse perspectives in the Cape Horn Biosphere Reserve in Chile and their relevance for conservation. Relationships between humans and nature take multiple forms. This is a fundamental issue in conservation but one that is often neglected, leading to poor conservation outcomes. It is thus imperative that we come to understand better the complex relationships between humans and nature. To do so, we need to examine "nature" and the often assumed dichotomy between humans and nature. The authors conducted a qualitative social research inquiry to explore the societal relationships with nature in the Cape Horn Biosphere Reserve in Chile. From the results, the authors developed a framework that illustrates how different "natures" are created in the three-way relationship among the individual, society and the physical world. The authors further discuss the implications of the co-existence of various "natures" in one place. Their explicit consideration bears important potential for improving conservation practice. The framework can then serve as a heuristic tool for uncovering and addressing challenges in other conservation contexts. Resilience Alliance 2010 Article 34 p. Text http://digital.library.unt.edu/ark:/67531/metadc97943/ ark: ark:/67531/metadc97943 Ecology and Society, 2010, Wolfville: Resilience Alliance English Public

info:ark/67531/metadc97954 2013-03-14T15:39:05Z partner:UNTCAS collection:UNTSW access_rights:public

[Review] Infinite Nature Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- sustainable developments nature ecology human behaviors cultural perspectives This book review discusses 'Infinite Nature', by R. Bruce Hull. Hull's book dissolves dichotomous positions by portraying a plurality of views about nature and relations between human communities and their environments. American Institute of Biological Science 2007-03 Review 3 p. Text doi: 10.1641/B570319 http://digital.library.unt.edu/ark:/67531/metadc97954/ ark: ark:/67531/metadc97954 BioScience, 2007, Reston: American Institute of Biological Science, pp. 292-293 English Public

info:ark/67531/metadc97945 2013-03-14T15:40:04Z partner:UNTCAS collection:UNTSW access_rights:public

Senda Darwin Biological Station: Long-term ecological research at the interface between science and society Estación Biológica Senda Darwin: Investigación ecológica de largo plazo en la interfase ciencia-sociedad Sub-Antarctic Biocultural Conservation Program Carmona, Martín R. Aravena, J. C. Bustamante-Sanchez, Marcela A. Celis-Diez, Juan L. Charrier, Andrés Díaz, Iván A. Díaz-Forestier, Javiera Díaz, María F. Gaxiola, Aurora Gutiérrez, Alvaro G. Hernandez-Pellicer, Claudia Ippi, Silvina Jaña-Prado, Rocío Jara-Arancio, Paola Jiménez, Jaime Manuschevich, Daniela Necochea, Pablo Nuñez-Avila, Mariela Papic, Claudia Pérez, Cecilia Pérez, Fernanda Reid, Sharon Rojas, Leonora Salgado, Beatriz Smith-Ramírez, Cecilia Troncoso, Andrea Vásquez, Rodrigo A. Willson, Mary F. Rozzi, Ricardo, 1960- Armesto, Juan J. biodiversity education long-term socio-ecological research private protected areas temperate rainforests This article discusses Senda Darwin Biological Station (SDBS). SDBS is a field research center immersed in the rural landscape of northern Chiloé island (42°S), where remnant patches of the original evergreen forests coexist with open pastures, secondary successional shrublands, Sphagnum bogs, Eucalyptus plantations and other anthropogenic cover types, constituting an agricultural frontier similar to other regions in Chile and Latin America. Since 1994, the authors have conducted long-term research on selected species of plants (e.g., Pilgerodendron uviferum) and animals (e.g., Aphrastura spinicauda, Dromiciops gliroides) that are considered threatened, poorly known or important for their ecological functions in local ecosystems, and on ecosystems of regional and global relevance (e.g., Sphagnum bogs, North Patagonian and Valdivian rain forests). Research has assessed the responses of species and ecosystems to anthropogenic land-use change, climate change, and the impact of management. During this period, more than 100 scientific publications in national and international journals, and 30 theses (graduate and undergraduate) have been produced by scientists and students associated with SDBS. Because of the authors' understanding of the key role that humans play in ecological processes at this agricultural frontier, since the establishment of SDBS the authors have been committed to creative research on the communication of science to society and ecological education. The integration of SDBS to the nascent Chilean network of long-term socio-ecological research will consolidate and strengthen basic and applied research to project the authors' work into the next decade. Sociedad de Biología de Chile 2010 Article 26 p. Text http://digital.library.unt.edu/ark:/67531/metadc97945/ ark: ark:/67531/metadc97945 Revista Chilena de Historia Natural, 2010, Santiago: Sociedad de Biología de Chile, pp. 113-142 English Estación Biológica Senda Darwin: Investigación ecológica de largo plazo en la interfase ciencia-sociedad, ark:/67531/metadc97946 Public

info:ark/67531/metadc97942 2013-03-14T15:40:26Z partner:UNTCAS collection:UNTSW access_rights:public

Superando la Dicotomía Entre Conocimiento Local y Global: Diversas Perspectivas sobre la Naturaleza en la Reserva de Biosfera Cabo de Hornos Local versus Global Knowledge: Diverse Perspectives on Nature in the Cape Horn Biosphere Reserve Sub-Antarctic Biocultural Conservation Program Berghöfer, Uta Rozzi, Ricardo, 1960- Jax, Kurt Cape Horn Biosphere Reserve ecological environments cultural environments nature This article discusses local versus global knowledge. A case study of socio-ecological research conducted in Puerto Williams, Chile reveals that persons belonging to different sociocultural groups in Cape Horn have a diversity of perspectives and relationships with nature. For example, a strong sense of home and belonging was expressed by the indigenous Yahgan community and by old residents, mostly descendents of early twentieth-century colonizers. However, people identified with resource use did not include positive answers for a sense of home. The concept of common land presented marked contrasts among respondents. Those identified with a cultivating type of relationship favored private property over public land. For respondents identified with an embedded type of relationship, freedom of movement was one of their most essential values. Some respondents identified with resource use and those identified with intellectual and aesthetic relationships with nature also valued common land. The approach used in this study transforms polarized and dichotomous notions into gradients of perspectives related to different degrees of local and global ecological and cultural environments. The resulting hybrid vision of perspectives on nature may be helpful in times of global change, where both local and global scales contribute to identify specific problematic asymmetries as well as opportunities for communication among different sociocultural groups. The University of North Texas 2008 Article 23 p. Text http://digital.library.unt.edu/ark:/67531/metadc97942/ ark: ark:/67531/metadc97942 Environmental Ethics, 2008, Denton: The University of North Texas, pp. 57-79 Spanish Local versus Global Knowledge: Diverse Perspectives on Nature in the Cape Horn Biosphere Reserve, ark:/67531/metadc97941 Public

info:ark/67531/metadc97956 2013-03-14T15:40:41Z partner:UNTCAS collection:UNTSW access_rights:public

Ten Dimensions of a Biocultural Conservation Approach at the Austral Tip of the Americas Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Massardo, Francisca Anderson, Christopher B. Silander, John biocultural conservation Cape Horn This article discusses ten dimensions of a biocultural conservation approach at the austral tip of the Americas. In the context of the conference "Building Sustainable Communities in Mexico & U.S.A." organized by the Center for US/Mexico Alliance for Community Renewal, UNT in January 2003, the authors were invited to present a view on sustainability and conservation based on their experience at the southern extreme of the Americas: the Region of Cape Horn, Chile. First, the authors introduce the regional scenario of biological and cultural conservation, and then the authors provide an overview of their approach by defining ten criteria that aim to achieve social well-being and biocultural conservation at the austral tip of the continent. The University of North Texas 2004 Article 8 p. Text http://digital.library.unt.edu/ark:/67531/metadc97956/ ark: ark:/67531/metadc97956 Sustainable Communities Review, 2004, Denton: The University of North Texas, pp. 76-83 English Public

info:ark/67531/metadc97958 2013-03-14T15:40:54Z partner:UNTCAS collection:UNTSW access_rights:public

Ten Principles for Biocultural Conservation at the Southern Tip of the Americas: The approach of the Omora Ethnobotanical Park Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Massardo, Francisca Anderson, Christopher B. Heidinger, Kurt Silander, John biocultural conservation biosphere reserve Cape Horn Chile environmental education environmental ethics flagship species interdisciplinary interinstitutional sustainability traditional ecological knowledge Yahgan This article discusses ten principles for biocultural conservation at the southern tip of the Americas. Although there is general agreement among conservation practitioners about the need for (1) social involvement on the part of scientists; (2) interdisciplinary approaches; (3) working on local, regional, and global levels; and (4) implementing international agreements on biodiversity and environmental protection, a major challenge we face in conservation today is how to integrate and implement these multiple dimensions. Few researchers have actually offered hands-on examples for showing in practical terms how such integration can be accomplished. To address this challenge the authors present an innovative case study: the Omora Ethnobotanical Park, a long-term biocultural conservation initiative at the southern extreme of the Americas. Located near Puerto Williams (55° S), Cape Horn Archipelago region, Chile, the Omora Park is a public-private reserve that provides material and conceptual foundations for three complementary conservation actions: (1) interdisciplinary scientific research; (2) informal and formal education, i.e., school, university, and training courses; and (3) biocultural conservation. The latter entails an actual reserve that protects biodiversity and the water quality of Puerto Williams' watershed, as well as programs on Yahgan traditional ecological knowledge and interdisciplinary activities, such as "field environmental ethics" and ecotourism, carried out in the reserve. Being at the "end of the world," and within one of the most remote and pristine ecoregions on the planet, Omora Park offers a "bio-cultural treasure." At the same time, its geographical and technological isolation presents a challenge for implementing and sustaining conservation actions. To achieve the general conservation goals, the authors have defined 10 principles that have guided the actions of Omora: (1) interinstitutional cooperation, (2) a participatory approach, (3) an interdisciplinary approach, (4) networking and international cooperation, (5) communication through the media, (6) identification of a flagship species, (7) outdoor formal and information education, (8) economic sustainability and ecotourism, (9) administrative sustainability, and (10) research and conceptual sustainability for conservation. These principles have been effective for establishing the long-term Omora initiative, as well as involving multiple actors, disciplines, and scales. Upon these foundations, the Omora initiative has extended its local goals to the regional level through a successful 5-yr process in cooperation with the Chilean government to create the Cape Horn Biosphere Reserve, designated by UNESCO in June 2005, with the goal of establishing a long-term institutional-political framework that promotes social well-being and biocultural conservation at the southernmost tip of the Americas. Resilience Alliance 2006 Article 56 p. Text http://digital.library.unt.edu/ark:/67531/metadc97958/ ark: ark:/67531/metadc97958 Ecology and Society, 2006, Wolfville: Resilience Alliance English Public

info:ark/67531/metadc97959 2013-04-10T17:31:39Z partner:UNTCAS collection:UNTSW access_rights:public

Filosofía ambiental de campo y conservación biocultural en el Parque Etnobotánico Omora: Aproximaciones metodológicas para ampliar los modos de integrar el componente social ("S") en Sitios de Estudios Socio-Ecológicos a Largo Plazo (SESELP) Field environmental philosophy and biocultural conservation at the Omora Ethnobotanical Park: Methodological approaches to broaden the ways of integrating the social component ("S") in Long-Term Socio-Ecological Research (LTSER) Sites Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Anderson, Christopher B. Pizarro, J. Cristóbal Massardo, Francisca Medina, Yanet Mansilla, Andrés O. Kennedy, James H. Ojeda, Jaime Contador, Tamara Morales, Verónica Moses, Kelli Poole, Alexandria Armesto, Juan J. Kalin Arroyo, Mary T. Cape Horn Biosphere Reserve environmental ethics metaphor subantarctic Sustainable Biosphere Initiative This article discusses field environmental philosophy and biocultural conservation at the Omora Ethnobotanical Park. Abstract: In order to effectively address the problems derived from global environmental change, environmental scientists, citizens and decision-makers now recognize the need to integrate more fully the human or social component into ecological research. The authors propose that to achieve this integration, Long-Term Socio-Ecological Research (LTSER) networks offer an ideal platform, because such sites enable research at ecological, cultural, and political local scales, and at the same time allow addressing these issues at a global scale. However, this socio-ecological work still requires better articulation of programs developed at multiple geographic, ecological and political scales. In addition, until now the social component considered in LTSER programs has focused on economic factors, omitting ethical dimensions. A central reason for this omission is the lack of methodologies to systematically integrate ethics into LTSER programs. As a contribution to resolve this limitation, here the authors develop a methodological approach that the authors call "field environmental philosophy." It integrates ecological research and environmental ethics into biocultural education and conservation through an interrelated four-step cycle: i) interdisciplinary ecological and philosophical research, ii) composition of metaphors, and communication through simple narratives, iii) design of guided field experiences with an ecological and ethical orientation, and iv) implementation of in situ conservation areas. This cycle has been defined a posteriori, by analyzing successful experiences of biocultural research, education and conservation program at the Omora Ethnobotanical Park (OEP) in the Cape Horn Biosphere Reserve (CHBR). The Masters of Science in Subantarctic Conservation at the University of Magallanes (UMAG) adopted this cycle as a structured methodology to design theses and academic curricula for students who are creating innovative educational and ecotourism activities, such as "Ecotourism with a Hand Lens" and "Ethical Birding." To articulate the programs at multiple scales, the OEP functions at the local scale as a research center in the CHBR, at the national level as a cofounder and southernmost site of the Chilean LTSER network coordinated by the Institute of Ecology and Biodiversity (IEB), Chile, and at the coordinated by UMAG, IEB and the University of North Texas (UNT). This organization of nested units has permitted to synergistically articulate the work at local, national and international scales. Collaborative research has led to the discovery of biological and cultural diversity singularities in the remote Magellanic subantarctic ecoregion, enabled education and conservation work with multiple social actors and institutions, and has strengthened the incorporation of environmental philosophy into socio-ecological research. In this way, OEP's program is contributing to broaden the definition of the social ("S") component in LTSER, and to generate methodologies to integrate, at multiple scales, ecological and ethical dimensions into socio-ecological research, as well as biocultural education and conservation programs, which could be implemented and assessed at other LTSER sites. Sociedad de Biología de Chile 2010 Article 42 p. Text http://digital.library.unt.edu/ark:/67531/metadc97959/ ark: ark:/67531/metadc97959 Revista Chilena de Historia Natural, 2010, Santiago: Sociedad de Biología de Chile, pp. 27-68 Spanish Field environmental philosophy and biocultural conservation at the Omora Ethnobotanical Park: Methodological approaches to broaden the ways of integrating the social component ("S") in Long-Term Socio-Ecological Research (LTSER) Sites [Material Complentario], ark:/67531/metadc97960 Field environmental philosophy and biocultural conservation at the Omora Ethnobotanical Park: Methodological approaches to broaden the ways of integrating the social component ("S") in Long-Term Socio-Ecological Research (LTSER) Sites, ark:/67531/metadc97961 Public

info:ark/67531/metadc97960 2013-04-10T16:45:20Z partner:UNTCAS collection:UNTSW access_rights:public

Field environmental philosophy and biocultural conservation at the Omora Ethnobotanical Park: Methodological approaches to broaden the ways of integrating the social component ("S") in Long-Term Socio-Ecological Research (LTSER) Sites [Material Complementario] Filosofía ambiental de campo y conservación biocultural en el Parque Etnobotánico Omora: Aproximaciones metodológicas para ampliar los modos de integrar el componente social ("S") en Sitios de Estudios Socio-Ecológicos a Largo Plazo (SESELP) Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Anderson, Christopher B. Pizarro, J. Cristóbal Massardo, Francisca Medina, Yanet Mansilla, Andrés O. Kennedy, James H. Ojeda, Jaime Contador, Tamara Morales, Verónica Moses, Kelli Poole, Alexandria Armesto, Juan J., 1953- Kalin Arroyo, Mary T. Cape Horn Biosphere Reserve environmental ethics metaphor subantarctic Sustainable Biosphere Initiative This article discusses field environmental philosophy and biocultural conservation at the Omora Ethnobotanical Park. Abstract: In order to effectively address the problems derived from global environmental change, environmental scientists, citizens and decision-makers now recognize the need to integrate more fully the human or social component into ecological research. The authors propose that to achieve this integration, Long-Term Socio-Ecological Research (LTSER) networks offer an ideal platform, because such sites enable research at ecological, cultural, and political local scales, and at the same time allow addressing these issues at a global scale. However, this socio-ecological work still requires better articulation of programs developed at multiple geographic, ecological and political scales. In addition, until now the social component considered in LTSER programs has focused on economic factors, omitting ethical dimensions. A central reason for this omission is the lack of methodologies to systematically integrate ethics into LTSER programs. As a contribution to resolve this limitation, here the authors develop a methodological approach that the authors call "field environmental philosophy." It integrates ecological research and environmental ethics into biocultural education and conservation through an interrelated four-step cycle: i) interdisciplinary ecological and philosophical research, ii) composition of metaphors, and communication through simple narratives, iii) design of guided field experiences with an ecological and ethical orientation, and iv) implementation of in situ conservation areas. This cycle has been defined a posteriori, by analyzing successful experiences of biocultural research, education and conservation program at the Omora Ethnobotanical Park (OEP) in the Cape Horn Biosphere Reserve (CHBR). The Masters of Science in Subantarctic Conservation at the University of Magallanes (UMAG) adopted this cycle as a structured methodology to design theses and academic curricula for students who are creating innovative educational and ecotourism activities, such as "Ecotourism with a Hand Lens" and "Ethical Birding." To articulate the programs at multiple scales, the OEP functions at the local scale as a research center in the CHBR, at the national level as a cofounder and southernmost site of the Chilean LTSER network coordinated by the Institute of Ecology and Biodiversity (IEB), Chile, and at the coordinated by UMAG, IEB and the University of North Texas (UNT). This organization of nested units has permitted to synergistically articulate the work at local, national and international scales. Collaborative research has led to the discovery of biological and cultural diversity singularities in the remote Magellanic subantarctic ecoregion, enabled education and conservation work with multiple social actors and institutions, and has strengthened the incorporation of environmental philosophy into socio-ecological research. In this way, OEP's program is contributing to broaden the definition of the social ("S") component in LTSER, and to generate methodologies to integrate, at multiple scales, ecological and ethical dimensions into socio-ecological research, as well as biocultural education and conservation programs, which could be implemented and assessed at other LTSER sites. Sociedad de Biología de Chile 2010 Article 37 p. Text http://digital.library.unt.edu/ark:/67531/metadc97960/ ark: ark:/67531/metadc97960 Revista Chilena de Historia Natural, 2010, Santiago: Sociedad de Biología de Chile English Filosofía ambiental de campo y conservación biocultural en el Parque Etnobotánico Omora: Aproximaciones metodológicas para ampliar los modos de integrar el componente social ("S") en Sitios de Estudios Socio-Ecológicos a Largo Plazo (SESELP), ark:/67531/metadc97959 Field environmental philosophy and biocultural conservation at the Omora Ethnobotanical Park: Methodological approaches to broaden the ways of integrating the social component ("S") in Long-Term Socio-Ecological Research (LTSER) Sites, ark:/67531/metadc97961 Public

info:ark/67531/metadc97957 2013-03-21T17:43:54Z partner:UNTCAS collection:UNTSW access_rights:public

Desde la ciencia hacia la conservación: el programa de educación y ética ambiental del Parque Etnobotánico Omora Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Draguicevic, Juan Manuel Arango, Ximena Sherriffs, Margaret Ippi, Silvina Anderson, Christopher B. Acevedo, Mitzi Plana, Jordi Cortés, Erika Massardo, Francisca environmental ethics education ecological sciences This article discusses the program of education and environmental ethics. The relationship between scientists and society theme of the Symposium of Mendoza, are addressed by the program of education and environmental ethics Omora Park on three interconnected levels: (1) level of ecological sciences, (2) level environmental ethics and (3) biocultural conservation level. Centro de Investigación y Planificación para el Medio Ambiente 2005 Article 10 p. Text http://digital.library.unt.edu/ark:/67531/metadc97957/ ark: ark:/67531/metadc97957 Ambiente y Desarrollo. 2005, Santiago: Centro de Investigación y Planificación para el Medio Ambiente, pp. 20-29 Spanish Public

info:ark/67531/metadc97949 2013-03-28T12:29:15Z partner:UNTCAS collection:UNTSW access_rights:public

Dinámica estacional y patrones de distribución de la avifauna asociada a humedales subantárticos en la Reserva de Biosfera Cabo de Hornos (54-55°S), Chile Seasonal dynamics and distribution patterns of birds associated to sub-Antarctic wetlands in the Cape Horn Biosphere Reserve (54-55°S), Chile Sub-Antarctic Biocultural Conservation Program Ibarra, J. Tomás Rozzi, Ricardo, 1960- Gilabert, Horacio Anderson, Christopher B. McGehee, Steven M. Bonacic, Cristián Avifauna wetlands seasonal variations Cape Horn Navarino Island sub-Antarctic This article discusses the seasonal dynamics and distribution patterns of birds associated to the sub-Antarctic wetlands in Cape Horn Biosphere Reserve (54-55°S), Chile. Abstract: Little is known about bird ecology in sub-Antarctic ecosystems of the Cape Horn Reserve (CHBR), Chile. The authors examined the role of altitude, seashore distance, lake size, season, and vegetation cover in affecting bird diversity and abundance on Navarino Island (54-55°S, 67°W) in the CHBR. The authors determined avian community composition, species richness and relative abundance for wetlands and their adjacent habitats on a seasonal basis. A total of 56 species belonging to 10 orders and 25 families were recorded, and significant seasonal changes for bird species (P = 0.001) and abundance (P < 0.01) were observed, with 33.9% residents, 48.2% winter migrants, and 17.9% with unknown migratory status. The distance of wetlands from the coastline was the main predictor variable for annual species richness (P < 0.01) and total avian abundance (P < 0.05). Wetlands far from the seashore and at higher altitudes had lower diversity and abundance, although the change in elevation was relatively slight (< 300 m). These data show the seasonal patterns and dynamics, as well as the major underlying mechanisms, for birds of wetlands and adjacent habitats in the CHBR. Neotropical Ornithological Society 2009 Article 18 p. Text http://digital.library.unt.edu/ark:/67531/metadc97949/ ark: ark:/67531/metadc97949 Ornitologia Neotropical, 2009, Saint Louis: Neotropical Ornithological Society, pp. 321-337 Spanish Public

info:ark/67531/metadc97950 2013-03-28T14:29:08Z partner:UNTCAS collection:UNTSW access_rights:public

Diversity and singularity of the avifauna in the austral peat bogs of the Cape Horn Biosphere Reserve, Chile Sub-Antarctic Biocultural Conservation Program Ibarra, J. Tomás Anderson, Christopher B. Altamirano, Tomás A. Rozzi, Ricardo, 1960- Bonacic, Cristián assemblage Cape Horn Biosphere Reserve Navarino Island Patagonia Sphagnum spp. wetlands This article discusses diversity and singularity of the avifauna in the austral peat bogs of the Cape Horn Biosphere Reserve, Chile. Abstract: Sphagnum-dominated peat bogs that are strongly embedded within the southern temperate forest matrix are increasingly being used for agriculture. Nevertheless, little is known about their biodiversity. Moreover, the remote areas of southern Chile where peat bogs are found, such as Cape Horn Biosphere Reserve (CHBR, 54-55°S), where birds are the most diverse and best represented group of vertebrates, have not been well-investigated. With the aim to broaden this knowledge in the CHBR, the authors studied the diversity of the avian assemblage in peat blogs on Navarino Island. The authors compared the composition of avian species between wetlands with and without peat bogs to test if Sphagnum bogs represented a singular habitat for birds in this area. Furthermore, the 37 bird species recorded in these habitats were classified according to guild structure. The community similarity values showed that peat bogs hosted a bird composition that was different from that present in wetlands without Sphagnum, suggesting that peat bogs are a singular type of habitat for birds in the CHBR. The most frequently feeding groups recorded in these wetlands were insectivores (48.7%), followed by omnivores (23.1%). The authors' results showed that, in contrast to previous studies of birds in peat bogs, these environments constituted a distinct wetland habitat for feeding, reproduction and sheltering for some species in the CHBR. Thus, plans for the conservation and rational use of peat ecosystems should consider the high value of these habitats for biodiversity on a landscape scale, especially for birds of the southernmost extreme of the Americas. Universidad Católica de Chile 2010 Article 15 p. Text http://digital.library.unt.edu/ark:/67531/metadc97950/ ark: ark:/67531/metadc97950 Ciencia e Investigación Agraria, 2010, Santiago: Universidad Católica de Chile, pp. 29-43 English Public

info:ark/67531/metadc97944 2013-03-14T15:25:53Z partner:UNTCAS collection:UNTSW access_rights:public

The Autecology of the Fío-Fío (Elaenia Albiceps Lafresnaye and D'Orbigny) in Subantarctic Forests of the Cape Horn Biosphere Reserve, Chile Autoecología del Fío-Fío (Elaenia Albiceps Lafresnaye and D'Orbigny) en los Bosques Subantárticos de la Reserva de Biosfera Cabo de Hornos, Chile Sub-Antarctic Biocultural Conservation Program Brown, Clare E. Anderson, Christopher B. Ippi, Silvina Sherriffs, Margaret Charlin, Rina McGehee, Steven M. Rozzi, Ricardo, 1960- avian community ecological role niche Nothofagus This article discusses the autecology of the fío-fío. Abstract: As the most diverse and abundant terrestrial vertebrates in the Cape Horn Archipelago, birds potentially play key roles in the ecology of subantarctic ecosystems. However, the lack of long-term ornithological studies in southern South America has previously hindered the identification of relevant aspects of the autecology of even the most common species. One abundant species in the austral summer is the fío-fío's ecology in the CHBR by determining: a) longevity and site fidelity, b) arrival-departure dates, c) abundance of adults and juveniles, d) diet and e) morphology. A total 827 fío-fíos were banded during the study period. Of the 67 recaptures, it was possible to determine that fío-fíos may live at least up to 7 years. Fío-fíos arrived as early as 28 October and left as late as 15 April with juveniles fledging in January. In the austral archipelago, the fío-fío's diet consisted of 10 invertebrate orders and at least 5 plant species. Males had significantly longer tails and wings than females, while females were significantly heavier in the pre-fledging season (Oct-Dec). This study provides new information on the autecology of fío-fío in the world's southernmost forests. Universidad de Magallanes 2007 Article 12 p. Text http://digital.library.unt.edu/ark:/67531/metadc97944/ ark: ark:/67531/metadc97944 Anales Instituto Patagonia, 2007, Magallanes: Universidad de Magallanes, pp. 29-40 English Public

info:ark/67531/metadc97940 2013-03-14T15:26:21Z partner:UNTCAS collection:UNTSW access_rights:public

Biocultural conservation in Cape Horn: the Magellanic woodpecker as a charismatic species Sub-Antarctic Biocultural Conservation Program Arango, Ximena Rozzi, Ricardo, 1960- Massardo, Francisca Ibarra, J. Tomás biocultural conservation woodpeckers sustainability This book chapter discusses a research project to promote biocultural conservation in Cape Horn, Chile. At the southernmost tip of the Americas, the Cape Horn Biosphere Reserve (CHBR) encompasses one of the world's most pristine remaining wilderness areas and is home to the indigenous Yaghan (or Yamana) community, which featured prominently in Charles Darwin's 'Voyage of the Beagle'. Its remoteness and uniqueness, however, are threatened by the introduction of exotic species such as the North American beaver and American mink, increasing development pressures from new connectivity, resource exploitation, and the development of tourism. To implement the biosphere reserve and conserve its natural and cultural richness requires the active participation of the community, as well as linkages and integration between various disciplines and institutions. In an effort to achieve the goal of transdisciplinary integration, the authors used the strategy of identifying a charismatic species, since doing so serves to motivate people towards biodiversity conservation, to communicate ecological concepts, and to integrate both the ecological and social dimensions of sustainability. This study was developed together with the population of Puerto Williams, a town with 2200 inhabitants located on Navarino Island, and the largest human settlement within the CHBR. Oxford University Press 2010-03-11 Book Chapter 2 p. Text isbn: 978-0-19-923691-6 http://digital.library.unt.edu/ark:/67531/metadc97940/ ark: ark:/67531/metadc97940 The Oxford Handbook of Interdisciplinarity, 2010, Oxford: Oxford University Press English Public

info:ark/67531/metadc97951 2013-03-14T15:24:45Z partner:UNTCAS collection:UNTSW access_rights:public

Annual Variation of Abundance and Composition in Forest Bird Assemblages on Navarino Island, Cape Horn Biosphere Reserve, Chile Sub-Antarctic Biocultural Conservation Program Ippi, Silvina Anderson, Christopher B. Rozzi, Ricardo, 1960- Elphick, Chris S. forest birds subantarctic forests Chile Cape Horn point-count surveys This article discusses the annual variation of abundance and composition in forest bird assemblages on Navarino Island, Cape Horn Biosphere Reserve, Chile. Abstract: The structure and dynamics of avian communities in the temperate forests of southern South America have been generally studied during the breeding season (November - March), and reports about seasonal variations and migratory behavior of species are almost lacking. This study examined intra-annual variations on a monthly basis in bird species composition and abundance in the world's southernmost forested ecosystems, found in the Cape Horn Biosphere Reserve, Chile (55°S). Combining data obtained through point-count surveys, mist-netting, and checklist methods, the authors recorded a total of 34 bird species belonging to 20 families. Eighteen of these species were Passeriformes, and the most abundant year-round resident species were Thorn-tailed Rayadito (Aphrastura spinicauda) and Patagonian Sierra-Finch (Phrygilus patagonicus). The most abundant seasonal migrants species were White-crested Elaenia (Elaenia albiceps) and Southern House Wren (Troglodytes musculus). Point-count and mist-netting methods showed a reduction in species richness and abundance during winter, with one third of the bird assemblage absent. This proportion was lower than that documented for more northern Nothofagus forests. Additionally, the authors' data provided no evidence that intra-annual patterns of avian community structure were significantly affected by a recently implemented tourism trail through the Omora Park. The authors believe that understanding seasonal patterns of richness, abundance, and migratory status of Chilean temperate forests birds will help to better understand the world's southernmost forest ecosystem, implement effective conservation, facilitate sustainable ecotourism, and lead to new ecological and evolutionary research. Neotropical Ornithological Society 2009 Article 15 p. Text http://digital.library.unt.edu/ark:/67531/metadc97951/ ark: ark:/67531/metadc97951 Ornitologia Neotropical, 2009, Neotropical Ornithological Society, pp. 231-245 English Public

info:ark/67531/metadc97946 2013-04-08T11:59:43Z partner:UNTCAS collection:UNTSW access_rights:public

Estación Biológica Senda Darwin: Investigación ecológica de largo plazo en la interfase ciencia-sociedad Senda Darwin Biological Station: Long-term ecological research at the interface between science and society Sub-Antarctic Biocultural Conservation Program Carmona, Martín R. Aravena, J. C. Bustamante-Sanchez, Marcela A. Celis-Diez, Juan L. Charrier, Andrés Díaz, Iván A. Díaz-Forestier, Javiera Díaz, María F. Gaxiola, Aurora Gutiérrez Ilabaca, Alvaro G. 1977- Hernandez-Pellicer, Claudia Ippi, Silvina Jaña-Prado, Rocío Jara-Arancio, Paola Jiménez, Jaime Manuschevich, Daniela Necochea, Pablo Nuñez-Avila, Mariela Papic, Claudia Pérez, Cecilia Pérez, Fernanda Reid, Sharon Rojas Bracho, Leonora Salgado, Beatriz Smith-Ramírez, Cecilia Troncoso, Andrea Vásquez, Rodrigo A. Willson, Mary F. Rozzi, Ricardo, 1960- Armesto, Juan J., 1953- biodiversity education long-term socio-ecological research private protected areas temperate rainforests This article discusses Senda Darwin Biological Station. Abstract: Senda Darwin Biological Station (SDBS) is a field research center immersed in the rural landscape of northern Chiloé island (42°S), where remnant patches of the original evergreen forests coexist with open pastures, secondary successional shrublands, Sphagnum bogs, Eucalyptus plantations and other anthropogenic cover types, constituting an agricultural frontier similar to other regions in Chile and Latin America. Since 1994, the authors have conducted long-term research on selected species of plants (e.g., Pilgerodendron uviferum) and animals (e.g., Aphrastura spinicauda, Dromiciops gliroides) that are considered threatened, poorly known or important for their ecological functions in local ecosystems, and on ecosystems of regional and global relevance (e.g., Sphagnum bogs, North Patagonian and Valdivian rain forests). Research has assessed the responses of species and ecosystems to anthropogenic land-use change, climate change, and the impact of management. During this period, more than 100 scientific publications in national and international journals, and 30 theses (graduate and undergraduate) have been produced by scientists and students associated with SDBS. Because of the authors' understanding of the key role that humans play in ecological processes at this agricultural frontier, since the establishment of SDBS the authors have been committed to creative research on the communication of science to society and ecological education. The integration of SDBS to the nascent Chilean network of long-term socio-ecological research will consolidate and strengthen basic and applied research to project the authors' work into the next decade. Sociedad de Biología de Chile 2010 Article 30 p. Text http://digital.library.unt.edu/ark:/67531/metadc97946/ ark: ark:/67531/metadc97946 Revista Chilena de Historia Natural, 2010, Santiago: Sociedad de Biología de Chile, pp. 113-142 Spanish Senda Darwin Biological Station: Long-term ecological research at the interface between science and society, ark:/67531/metadc97945 Public

info:ark/67531/metadc97955 2013-04-08T14:09:36Z partner:UNTCAS collection:UNTSW access_rights:public

La ética siempre ha sido ambiental: Implicancias para la conservación biocultural y un concepto geocultural de áreas protegidas Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- environmental ethics biocultural conservation This article discusses environmental ethics and the implications for biocultural conservation and geo-cultural concepts of protected areas. 2008 Article 3 p. Text http://digital.library.unt.edu/ark:/67531/metadc97955/ ark: ark:/67531/metadc97955 Boletín Conser-V-Acción, 2008 Spanish Public

info:ark/67531/metadc97952 2013-04-10T16:04:08Z partner:UNTCAS collection:UNTSW access_rights:public

Fenología de Tayloria dubyi (Splachnaceae) en las turberas de la Reserva de Biosfera Cabo de Hornos Phenology of Tayloria dubyi (Splachnaceae) in the peatlands of the Cape Horn Biosphere Reserve Sub-Antarctic Biocultural Conservation Program Jofre, Jocelyn Massardo, Francisca Rozzi, Ricardo, 1960- Goffinet, Bernard Marino, Paul Raguso, Robert A. Navarro, Nelso P. bryophytes Cape Horn Biosphere Reserve phenology reproduction Splachnaceae sub-Antarctic Magellanic ecoregion This article discusses the phenology of Tayloria dubyi (Splachnaceae) in the peatlands of the Cape Horn Biosphere Reserve. Abstract: The sub-Antarctic Magellanic ecoregion harbors a high diversity of bryophytes, greater than the species richness of vascular plants. Despite this fact, phenological studies on bryophytes are lacking for this ecoregion and Chile. Based on the study of the sporophytic phase of Tayloria dubyi, an endemic moss from the sub-Antarctic Magellanic ecoregion, the authors propose a methodology for phonological studies on austral bryophytes. The authors defined five phenophases, easily distinguishable with a hand-lens, which were monthly recorded during 2007 and 2008 in populations of T. dubyi at the Omora Ethnobotanical Park and Mejillones Bay on Navarino Island (55°S) in the Cape Horn Biosphere Reserve. The sporophytic (or reproductive) phase of T. dubyi presented a clear seasonality. After growing in November, in three months (December - February) of the austral reproductive season the sporophytes mature and release their spores; by March they are already senescent T. dubyi belongs to the Splachnaceae family for which entomochory (dispersal of spores by insects, specifically Diptera) has been detected in the Northern Hemisphere. The period of spores release in T. dubyi coincides with the months of highest activity of Diptera which are potential dispersers of spores; hence, entomochory could also take place in sub-Antarctic Magellanic ecoregion. In sum, the authors' work: (i) defines a methodology for phenological studies in austral bryophytes, (ii) it records a marked seasonality ion the sporophyte phase of T. dubyi, and (iii) it proposes to evaluate in future research the occurrence of entomochory in splachnaceae species growing in the sub-Antarctic peatlands and forest ecosystems in the Southern Hemisphere. Sociedad de Biología de Chile 2010 Article 12 p. Text http://digital.library.unt.edu/ark:/67531/metadc97952/ ark: ark:/67531/metadc97952 Revista Chilena de Historia Natural, 2010, Santiago: Sociedad de Biología de Chile, pp. 195-206 Spanish Public

info:ark/67531/metadc97961 2013-04-10T16:39:46Z partner:UNTCAS collection:UNTSW access_rights:public

Field environmental philosophy and biocultural conservation at the Omora Ethnobotanical Park: Methodological approaches to broaden the ways of integrating the social component ("S") in Long-Term Socio-Ecological Research (LTSER) Sites Filosofía ambiental de campo y conservación biocultural en el Parque Etnobotánico Omora: Aproximaciones metodológicas para ampliar los modos de integrar el componente social ("S") en Sitios de Estudios Socio-Ecológicos a Largo Plazo (SESELP) Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Anderson, Christopher B. Pizarro, J. Cristóbal Massardo, Francisca Medina, Yanet Mansilla, Andrés O. Kennedy, James H. Ojeda, Jaime Contador, Tamara Morales, Verónica Moses, Kelli Poole, Alexandria Armesto, Juan J., 1953- Kalin Arroyo, Mary T. Cape Horn Biosphere Reserve environmental ethics metaphor subantarctic Sustainable Biosphere Initiative This article discusses field environmental philosophy and biocultural conservation at the Omora Ethnobotanical Park. Abstract: In order to effectively address the problems derived from global environmental change, environmental scientists, citizens and decision-makers now recognize the need to integrate more fully the human or social component into ecological research. The authors propose that to achieve this integration, Long-Term Socio-Ecological Research (LTSER) networks offer an ideal platform, because such sites enable research at ecological, cultural, and political local scales, and at the same time allow addressing these issues at a global scale. However, this socio-ecological work still requires better articulation of programs developed at multiple geographic, ecological and political scales. In addition, until now the social component considered in LTSER programs has focused on economic factors, omitting ethical dimensions. A central reason for this omission is the lack of methodologies to systematically integrate ethics into LTSER programs. As a contribution to resolve this limitation, here the authors develop a methodological approach that the authors call "field environmental philosophy." It integrates ecological research and environmental ethics into biocultural education and conservation through an interrelated four-step cycle: i) interdisciplinary ecological and philosophical research, ii) composition of metaphors, and communication through simple narratives, iii) design of guided field experiences with an ecological and ethical orientation, and iv) implementation of in situ conservation areas. This cycle has been defined a posteriori, by analyzing successful experiences of biocultural research, education and conservation program at the Omora Ethnobotanical Park (OEP) in the Cape Horn Biosphere Reserve (CHBR). The Masters of Science in Subantarctic Conservation at the University of Magallanes (UMAG) adopted this cycle as a structured methodology to design theses and academic curricula for students who are creating innovative educational and ecotourism activities, such as "Ecotourism with a Hand Lens" and "Ethical Birding." To articulate the programs at multiple scales, the OEP functions at the local scale as a research center in the CHBR, at the national level as a cofounder and southernmost site of the Chilean LTSER network coordinated by the Institute of Ecology and Biodiversity (IEB), Chile, and at the coordinated by UMAG, IEB and the University of North Texas (UNT). This organization of nested units has permitted to synergistically articulate the work at local, national and international scales. Collaborative research has led to the discovery of biological and cultural diversity singularities in the remote Magellanic subantarctic ecoregion, enabled education and conservation work with multiple social actors and institutions, and has strengthened the incorporation of environmental philosophy into socio-ecological research. In this way, OEP's program is contributing to broaden the definition of the social ("S") component in LTSER, and to generate methodologies to integrate, at multiple scales, ecological and ethical dimensions into socio-ecological research, as well as biocultural education and conservation programs, which could be implemented and assessed at other LTER sites. Sociedad de Biología de Chile 2010 Article 35 p. Text http://digital.library.unt.edu/ark:/67531/metadc97961/ ark: ark:/67531/metadc97961 Revista Chilena de Historia Natural, 2010, Santiago: Sociedad de Biología de Chile, pp. 27-68 English Filosofía ambiental de campo y conservación biocultural en el Parque Etnobotánico Omora: Aproximaciones metodológicas para ampliar los modos de integrar el componente social ("S") en Sitios de Estudios Socio-Ecológicos a Largo Plazo (SESELP), ark:/67531/metadc97959 Field environmental philosophy and biocultural conservation at the Omora Ethnobotanical Park: Methodological approaches to broaden the ways of integrating the social component ("S") in Long-Term Socio-Ecological Research (LTSER) Sites [Material Complementario], ark:/67531/metadc97960 Public

info:ark/67531/metadc97938 2013-05-03T12:52:12Z partner:UNTCAS collection:UNTSW access_rights:public

Integrando la Ciencia y la Sociedad a través de la Investigación Socio-Ecológica de Largo Plazo Integrating Science and Society through Social-Ecological Research Long Term Sub-Antarctic Biocultural Conservation Program Anderson, Christopher B. Likens, Gene E., 1935- Rozzi, Ricardo, 1960- Gutiérrez, Julio R., 1953- Armesto, Juan J., 1953- Poole, Alexandria long-term ecological research LTER long-term socio-ecological research LTSER biocultural conservation This article discusses integrating science and society through long-term socio-ecological research. Abstract: Long-term ecological research (LTER), addressing problems that encompass decadal or longer time frames, began as a formal term and program in the United States in 1980. While long-term ecological studies and observation began as early as the 1400s and 1800s in Asia and Europe, respectively, the long-term approach was not formalized until the establishment of the U.S. long-term ecological research programs. These programs permitted ecosystem-level experiments and cross-site comparisons that led to insights into the biosphere's structure and function. The holistic ecosystem approach of this initiative also allowed the incorporation of the human-dimension of ecology and recently has given rise to a new concept of long-term socio-ecological research (LTSER). Today, long-term ecological research programs exist in at least thirty-two countries (i.e., members of the International Long-Term Ecological Research Network, ILTER). However, consolidation of the international network within the long-term socio-ecological research paradigm still requires: (1) inclusion of certain remote regions of the world, such as southwestern South America, that are still poorly represented; (2) modifications of the type of research conducted, such as integrating social and natural sciences with the humanities and ethics; and (3) the incorporation of findings and results into broader social and political processes. In this context, a nascent long-term socio-ecological research network in Chile, which extends over the longest latitudinal range of temperate forest in the Southern Hemisphere, adds a new remote region to international long-term ecological research previously overlooked. In addition, collaboration with the University of North Texas and other international partners helps to further develop an interdisciplinary approach for the integration of the ecological sciences and environmental philosophy together with traditional ecological knowledge, informal and formal education, policy, the humanities, socio-political processes, and biocultural conservation. University of North Texas 2008 Article 19 p. Text http://digital.library.unt.edu/ark:/67531/metadc97938/ ark: ark:/67531/metadc97938 Environmental Ethics, 2008, Denton: University of North Texas, pp. 81-99 Spanish Integrating Science and Society through Social-Ecological Research Long Term, ark:/67531/metadc97939 Public

info:ark/67531/metadc97939 2013-05-13T09:55:22Z partner:UNTCAS collection:UNTSW access_rights:public

Integrating Science and Society through Long-Term Socio-Ecological Research Integrando la Ciencia y la Sociedad a través de la Investigación Socio-Ecológica de Largo Plazo Sub-Antarctic Biocultural Conservation Program Anderson, Christopher B. Likens, Gene E., 1935- Rozzi, Ricardo, 1960- Gutiérrez, Julio R., 1953- Armesto, Juan J., 1953- Poole, Alexandria long-term ecological research LTER long-term socio-ecological research LTSER biocultural conservation This article discusses integrating science and society through long-term socio-ecological research. Abstract: Long-term ecological research (LTER), addressing problems that encompass decadal or longer time frames, began as a formal term and program in the United States in 1980. While long-term ecological studies and observation began as early as the 1400s and 1800s in Asia and Europe, respectively, the long-term approach was not formalized until the establishment of the U.S. long-term ecological research programs. These programs permitted ecosystem-level experiments and cross-site comparisons that led to insights into the biosphere's structure and function. The holistic ecosystem approach of this initiative also allowed the incorporation of the human-dimension of ecology and recently has given rise to a new concept of long-term socio-ecological research (LTSER). Today, long-term ecological research programs exist in at least thirty-two countries (i.e., members of the International Long-Term Ecological Research Network, ILTER). However, consolidation of the international network within the long-term socio-ecological research paradigm still requires: (1) inclusion of certain remote regions of the world, such as southwestern South America, that are still poorly represented; (2) modifications of the type of research conducted, such as integrating social and natural sciences with the humanities and ethics; and (3) the incorporation of findings and results into broader social and political processes. In this context, a nascent long-term socio-ecological research network in Chile, which extends over the longest latitudinal range of temperate forest in the Southern Hemisphere, adds a new remote region to international long-term ecological research previously overlooked. In addition, collaboration with the University of North Texas and other international partners helps to further develop an interdisciplinary approach for the integration of the ecological sciences and environmental philosophy together with traditional ecological knowledge, informal and formal education, policy, the humanities, socio-political processes, and biocultural conservation. University of North Texas 2008 Article 18 p. Text http://digital.library.unt.edu/ark:/67531/metadc97939/ ark: ark:/67531/metadc97939 Environmental Ethics, 2008, Denton: University of North Texas, pp. 295-312 English Integrando la Ciencia y la Sociedad a través de la Investigación Socio-Ecológica de Largo Plazo, ark:/67531/metadc97938 Public

info:ark/67531/metadc97948 2013-05-14T12:35:17Z partner:UNTCAS collection:UNTSW access_rights:public

Invasive American mink Mustela vison in wetlands of the Cape Horn Biosphere Reserve, southern Chile: what are they eating? Sub-Antarctic Biocultural Conservation Program Ibarra, J. Tomás Fasola, Laura MacDonald, David W. (David Whyte) Rozzi, Ricardo, 1960- Bonacic, Cristián American mink Cape Horn diet invasive species Mustela vison seasonal variations wetlands This article discusses invasive American mink Mustela vison in wetlands of the Cape Horn Biosphere Reserve, southern Chile. Abstract: The impact of alien American mink on the native fauna of oceanic islands has been demonstrated in a number of locations. In the sub-Antarctic Cape Horn Biosphere Reserve of southern Chile the species is currently expanding in an area where the native fauna evolved in the absence of terrestrial predators. To evaluate any emerging problems, the authors therefore investigated seasonal variation in prey use by mink on Navarino Island within the Reserve. The authors identified undigested remains in 414 scats collected from the shores of 27 ponds over January-November 2006. Diet consisted mainly of mammals and birds. Mammals, including both native and exotic rodents, were the predominant prey in all seasons but birds were of equal importance during the summer (when birds breed and their abundance and diversity increases on the island). Exotic rodents were the only identifiable mammalian prey item during winter. Native wetlands birds constituted a substantial proportion of mink diet, and greater than that reported in other areas. Many birds breeding on Navarino Island are ground-nesting, a strategy that evolved in the absence of native mammalian predators. Considering the international importance of this region, the authors' results emphasize the need for an assessment of the impact of mink predation on the populations of native prey. Cambridge University Press 2009-01 Article 4 p. Text doi: 10.1017/S0030605308099997 http://digital.library.unt.edu/ark:/67531/metadc97948/ ark: ark:/67531/metadc97948 Fauna and Flora International, Oryx, 2009, New York: Cambridge University Press, pp. 87-90 English Public

info:ark/67531/metadc97941 2013-05-20T17:35:10Z partner:UNTCAS collection:UNTSW access_rights:public

Local versus Global Knowledge: Diverse Perspectives on Nature in the Cape Horn Biosphere Reserve Superando la Dicotomía Entre Conocimiento Local y Global: Diversas Perspectivas sobre la Naturaleza en la Reserva de Biosfera Cabo de Hornos Sub-Antarctic Biocultural Conservation Program Berghöfer, Uta Rozzi, Ricardo, 1960- Jax, Kurt, 1958- Cape Horn Biosphere Reserve ecological environments cultural environments nature This article discusses local versus global knowledge and diverse perspectives on nature in the Cape Horn Biosphere Reserve. Abstract: A case study of socio-ecological research conducted in Puerto Williams, Chile reveals that persons belonging to different sociocultural groups in Cape Horn have a diversity of perspectives and relationships with nature. For example, a strong sense of home and belonging was expressed by the indigenous Yahgan community and by old residents, mostly descendents of early twentieth-century colonizers. However, people identified with resource use did not include positive answers for a sense of home. The concept of common land presented marked contrasts among respondents. Those identified with a cultivating type of relationship favored private property over public land. For respondents identified with an embedded type of relationship, freedom of movement was one of their most essential values. Some respondents identified with resource use and those identified with intellectual and aesthetic relationships with nature also valued common land. The approach used in this study transforms polarized and dichotomous notions into gradients of perspectives related to different degrees of local and global ecological and cultural environments. The resulting hybrid vision of perspectives on nature may be helpful in times of global change, where both local and global scales contribute to identify specific problematic asymmetries as well as opportunities for communication among different sociocultural groups. University of North Texas. Center for Environmental Philosophy 2008 Article 22 p. Text http://digital.library.unt.edu/ark:/67531/metadc97941/ ark: ark:/67531/metadc97941 Environmental Ethics, 2008, Denton: University of North Texas. Center for Environmental Philosophy, pp. 273-294 English Superando la Dicotomía Entre Conocimiento Local y Global: Diversas Perspectivas sobre la Naturaleza en la Reserva de Biosfera Cabo de Hornos, ark:/67531/metadc97942 Public

info:ark/67531/metadc97964 2013-03-14T15:41:07Z partner:UNTCAS collection:UNTSW access_rights:public

A Tribute to Carlos Augusto Angel Maya Sub-Antarctic Biocultural Conservation Program Noguera de Echeverri, Ana Patricia Rozzi, Ricardo, 1960- environmental philosophies Latin America Maya, Carlos Augusto Angel Capra, Fritjof This article offers a tribute to Carlos Augusto Angel Maya. The authors explain Maya's life and work and his legacy of infinite value for the community of environmental thought in Colombia, in Latin America, and throughout the world. The University of North Texas 2011 Article 2 p. Text http://digital.library.unt.edu/ark:/67531/metadc97964/ ark: ark:/67531/metadc97964 Environmental Ethics, 2011, Denton: The University of North Texas, pp. 3-4 English Public

info:ark/67531/metadc102295 2013-03-20T11:10:50Z partner:UNTCAS collection:UNTSW access_rights:public

Comentario: Archipiélago Patagónico. La última frontera Sub-Antarctic Biocultural Conservation Program Notas Y Comentarios Bibliográficos Rozzi, Ricardo, 1960- Patagonia archipelago frontiers ecosystems ecotourism This article offers comment by the author on the Patagonian Archipelago as the Final Frontier, as written about in a book by Matthew B. Martinic titled, 'Patagonia Archipelago. The Final Frontier. Universidad de Magallanes 2005 Article 7 p. Text http://digital.library.unt.edu/ark:/67531/metadc102295/ ark: ark:/67531/metadc102295 Magallania, 2005, Magallanes: Universidad de Magallanes, pp. 177-184 Spanish Public

info:ark/67531/metadc102292 2013-03-14T15:38:51Z partner:UNTCAS collection:UNTSW access_rights:public

La Reserva De Biosfera Cabo De Hornos: Un Desafío Para La Conservación De La Biodiversidad E Implementación Del Desarrollo Sustentable En El Extremo Austral De América Cape Horn Biosphere Reserve: A Challenge For Biodiversity Conservation, And Implementation Of Sustainable Development In Southernmost South America Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Massardo, Francisca Mansilla, Andrés O. Anderson, Christopher B. Berghöfer, Augustin Mansilla, Miguel Gallardo, María Rosa Plana, Jordi Berghöfer, Uta Arango, Ximena Russell, Shaun Araya, Pedro Barros, Eduardo Cape Horn biodiversity ecosystems This article discusses biodiversity conservation and implementation of sustainable development in southernmost South America and the new biosphere reserve in Cape Horn, located in Antarctica Chilena Province. Universidad de Magallanes 2007 Article 16 p. Text http://digital.library.unt.edu/ark:/67531/metadc102292/ ark: ark:/67531/metadc102292 Anales Instituto Patagonia, 2007, Magallanes: Universidad de Magallanes, pp. 55-70 Spanish Public

info:ark/67531/metadc102287 2013-03-14T15:41:24Z partner:UNTCAS collection:UNTSW access_rights:public

Watershed Conservation and Aquatic Benthic Macroinvertebrate Diversity in the Alberto D'Agostini National Park, Tierra del Fuego, Chile Estado de Conservación de las Cuencas Hidrográficas y Diversidad de los Macroinvertebrados Bentónicos Dulceacuícolas del Parque Nacional Alberto D'Agostini, Tierra del Fuego, Chile Sub-Antarctic Biocultural Conservation Program Moorman, Michelle C. Anderson, Christopher B. Gutiérrez, Alvaro G. Charlin, Rina Rozzi, Ricardo, 1960- Biosphere Reserve Cape Horn Tierra del Fuego macroinvertebrates sub-Antarctic disturbances wilderness areas This article discusses watershed conservation and aquatic benthic macroinvertebrate diversity in the Alberto D'Agostini National Park, Tierra Del Fuego, Chile. Southern South America is known globally for its remote and rugged landscapes, which include one of Chile's largest national park: Alberto De Agostini. The singular nature of this area, however, is also found in is flora and fauna. The recent designation of Magellanic Sub-Antarctic Forests as one of the world's last wilderness areas propelled us to question whether there was detailed evidence for this classification in the Tierra del Fuego portion of the De Agostini Park. Therefore, in January 2004 and 2005 boat-based expeditions were carried out around the south-west portion of Tierra del Fuego Island, as well as adjacent islands south of the Beagle Channel. Their purpose was to evaluate the current state of the park's natural resources and to create a baseline of physical, chemical, biological and ecological information that can be used in the administration, conservation and future research of this area. The authors utilized a watershed analysis approach, examining vegetation cover, habitat type and disturbance. Along the major watercourse of each basin, the authors quantified the presence of exotic species, water quality and the aquatic macroinvertebrate assemblage. The authors found that habitats types were highly diverse with mixed and deciduous forests dominating the eastern portion of the study area and Magellanic evergreen forests and tundra in the west. On average, approximately 50% of the watersheds' areas were covered by forests with exposed rock and tundra occupying 28% and 17%, respectively. Glaciers and herbaceous habitats only made up 3% of study sites. Disturbances from human impacts and introduced species were rare and focused mainly outside the national park and in the eastern portion of the Brecknock peninsula, but significant localized exceptions occurred even in isolated fjords and where fishing and tourism activities were being carried out. Finally, one quality of the archipelago that had not previously been well evaluated was its freshwater ecosystems and biota. The authors' water quality analysis showed that these streams were highly pristine and contained a diverse and largely endemic aquatic macroinvertebrate fauna (e.g. Trichoptera Monocosmoecus hyadesi and Rheochorema magellanicum and the Plecoptera Notoperla fuegiana). Furthermore, many of these taxa provide ideal taxonomic, evolutionary and biogeographic study subjects, given their isolated and ancient lineages, as well as the fact that several orders and families reach their global southern distribution limit in the Fuegian Archipelago (e.g. Ephemeroptera, Trichoptera, Plecoptera and Diptera simuliidae and Coleoptera Dytiscidae). The authors expect these data to further a greater appreciation and understanding of the pristine areas of Tierra del Fuego and that it will help to establish ecological monitoring criteria for Alberto De Agostini National Park, which is also part of the new Cape Horn Biosphere Reserve, and mitigate impacts of development on an area that is currently still in a largely natural state. Universidad de Magallanes 2006 Article 18 p. Text http://digital.library.unt.edu/ark:/67531/metadc102287/ ark: ark:/67531/metadc102287 Anales Instituto Patagonia, 2006, Magallanes: Universidad de Magallanes, pp. 41-58 English Public

info:ark/67531/metadc102296 2013-04-10T16:50:45Z partner:UNTCAS collection:UNTSW access_rights:public

Field Environmental Philosophy and Biocultural Conservation: The Omora Ethnobotanical Park Educational Program Filosofía Ambiental de Campo y Conservación Biocultural: El Programa Educativo del Parque Etnobotánico Omora Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Arango, Ximena Massardo, Francisca Anderson, Christopher B. Heidinger, Kurt Moses, Kelli habitats biocultural conservation environmental ethics Cape Horn Biosphere Reserve This article discusses field environmental philosophy and biocultural conservation. Abstract: Habitats (where we live), habits (how we live), and inhabitants (who we are) constitute an ecosystem unit. The biosphere is composed of a reticulate mosaic of these habitat-habit-inhabitant units, where humans (with their indigenous languages, ecological knowledge, and practices) have coevolved. Today, these diverse ecosystem units are being violently destroyed by the imposition of a single global colonial cultural model. In Cape Horn at the southern end of the Americas, educators, authorities, and decision makers do not know about the native habitats, language, and flora, and do not distinguish between Cape Horn's flora and the flora that grows in other parts of the country or the world. In contrast, indigenous people and old residents have a detailed knowledge, but they do not participate in education, and decision making. It is not Homo Sapiens in general, but bioculturally biased educators, authorities, and decision makers who need to be transformed into (educated and responsible) members and citizen of biocultural communities. The Omora Ethnobotanical Park educational program was launched to contribute to a biocultural citizenship involving three critical steps: (1) the disclosing of biocultural diversity with a "fine filter" approach that permits understanding of the cultural and ecological diversity hidden by general universal labels; (2) direct "face-to-face" encounters with human and nonhuman co-inhabitants; and (3) actions for protection of habitats and implementation of interpretative spaces that facilitate direct encounters and conservation of biocultural diversity. These steps have been implemented at local and regional scales through the creation of the Omora Ethnobotanical Park and the UNESCO Cape Horn Biosphere Reserve. University of North Texas 2008 Article 12 p. Text http://digital.library.unt.edu/ark:/67531/metadc102296/ ark: ark:/67531/metadc102296 Environmental Ethics, 2008, Denton: University of North Texas, pp. 325-336 English Filosofía Ambiental de Campo y Conservación Biocultural: El Programa Educativo del Parque Etnobotánico Omora, ark:/67531/metadc102297 Public

info:ark/67531/metadc102297 2013-04-10T17:29:33Z partner:UNTCAS collection:UNTSW access_rights:public

Filosofía Ambiental de Campo y Conservación Biocultural: El Programa Educativo del Parque Etnobotánico Omora Field Environmental Philosophy and Biocultural Conservation: The Omora Ethnobotanical Park Educational Program Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Arango, Ximena Massardo, Francisca Anderson, Christopher B. Heidinger, Kurt Moses, Kelli habitats biocultural conservation environmental ethics Cape Horn Biosphere Reserve This article discusses field environmental philosophy and biocultural conservation. Abstract: Habitats (where we live), habits (how we live), and inhabitants (who we are) constitute an ecosystem unit. The biosphere is composed of a reticulate mosaic of these habitat-habit-inhabitant units, where humans (with their indigenous languages, ecological knowledge, and practices) have coevolved. Today, these diverse ecosystem units are being violently destroyed by the imposition of a single global colonial cultural model. In Cape Horn at the southern end of the Americas, educators, authorities, and decision makers do not know about the native habitats, language, and flora, and do not distinguish between Cape Horn's flora and the flora that grows in other parts of the country or the world. In contrast, indigenous people and old residents have a detailed knowledge, but they do not participate in education, and decision making. It is not Homo Sapiens in general, but bioculturally biased educators, authorities, and decision makers who need to be transformed into (educated and responsible) members and citizen of biocultural communities. The Omora Ethnobotanical Park educational program was launched to contribute to a biocultural citizenship involving three critical steps: (1) the disclosing of biocultural diversity with a "fine filter" approach that permits understanding of the cultural and ecological diversity hidden by general universal labels; (2) direct "face-to-face" encounters with human and nonhuman co-inhabitants; and (3) actions for protection of habitats and implementation of interpretative spaces that facilitate direct encounters and conservation of biocultural diversity. These steps have been implemented at local and regional scales through the creation of the Omora Ethnobotanical Park and the UNESCO Cape Horn Biosphere Reserve. University of North Texas 2008 Article 14 p. Text http://digital.library.unt.edu/ark:/67531/metadc102297/ ark: ark:/67531/metadc102297 Environmental Ethics, 2008, Denton: University of North Texas, pp. 115-128 Spanish Field Environmental Philosophy and Biocultural Conservation: The Omora Ethnobotanical Park Educational Program, ark:/67531/metadc102296 Public

info:ark/67531/metadc102291 2013-03-18T13:23:13Z partner:UNTCAS collection:UNTSW access_rights:public

Cabo de Hornos: un parque nacional libre de especies exóticas en el confín de América Cape Horn: A National Park Free From Alien Species In Southernmost South America Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Charlin, Rina Ippi, Silvina Dollenz Álvarez, Orlando Cape Horn exotic plants natural vegetation biodiversity This article discusses Cape Horn, a National park free from alien species in southernmost South America. The Cape Horn Archipelago, tam- also called Wollaston archipelago, retains its pristine condition, almost completely free of exotic plant species. Universidad de Magallanes 2004 Article 8 p. Text http://digital.library.unt.edu/ark:/67531/metadc102291/ ark: ark:/67531/metadc102291 Anales Instituto Patagonia, 2004, Magallanes: Universidad de Magallanes, pp. 55-62 Spanish Public

info:ark/67531/metadc102284 2013-04-01T13:55:17Z partner:UNTCAS collection:UNTSW access_rights:public

Ecological theory and values in the determination of conservation goals: examples from temperate regions of Germany, United States of America, and Chile Sub-Antarctic Biocultural Conservation Program Jax, Kurt, 1958- Rozzi, Ricardo, 1960- conservation comparative approaches ecological theories Chile ecotourism ecosystem management Germany images of nature Magellan region social values Yellowstone This article discusses ecological theory and values in the determination of conservation goals. Abstract: The definition of conservation goals is a complex task, which involves both ecological sciences and social values. A brief history of conservation strategies in Germany (protection of cultural landscapes), United States (wilderness ideal), and southern Chile (preservation paradigm and the more recent interest in ecotourism) illustrates a broad range of conservation goals. To encompass such an array of conservation dimensions and goals, the ecosystem approach adopted by the Conference of the Parties of the Convention on Biological Diversity represents a good approach. However, to become effective, this kind of approach requires clarifying and agreeing upon basic concepts, such as ecosystem. To serve that purpose, the authors present a scheme that considers the selected phenomena, internal relationship, and the component resolution to define an ecosystem. The authors conclude that: (1) conservation traditions encompass interests in the preservation of both natural and cultural heritages, which also appear as mutually dependent dimensions. Hence, nature and humans are brought together as much in the goals as in the processes of conservation. (2) In the context of current global change, it is impossible to completely "isolate" protected areas from direct or indirect human influences. In addition, the current view of nature points out that biota and ecosystems will change over time, even in protected areas. Hence, in order to preserve species or habitats it is not enough to isolate protected areas, but it often requires active management and conservation actions. The two former conclusions suggest the need to revise the conservation approach that has been undertaken in the southern region of Chile, because (a) local people have been systematically excluded from protected areas, and (b) these areas lack personnel and facilities to conduct appropriate conservation and/or management programs. (3) Our analyses of the views of nature and conservation goals in different regions and/or historical moments demonstrate that these involve not only scientific criteria, but also philosophical, political and broader cultural, social and economic dimensions. Hence, effective conservation requires a greater degree of interdisciplinary and interagency cooperation. Sociedad de Biología de Chile 2004 Article 18 p. Text http://digital.library.unt.edu/ark:/67531/metadc102284/ ark: ark:/67531/metadc102284 Revista Chilena de Historia Natural, 2004, Santiago: Sociedad de Biología de Chile, pp. 349-366 English Public

info:ark/67531/metadc102305 2012-09-11T10:10:19Z partner:UNTCAS collection:UNTSW access_rights:public

The Origin and Composition of Cucurbit "Phloem" Exudate Zhang, Cankui Yu, Xiyan Ayre, Brian G. Turgeon, Robert exudate cucurbit phloem Cucurbita maxima Cucumis sativus This article discusses the origin and composition of cucurbit phloem exudate. Cucurbits exude profusely when stems or petioles are cut. The authors conducted studies on pumpkin (Cucurbita maxima) and cucumber (Cucumis sativus) to determine the origin and composition of the exudate. Morphometric analysis indicated that the exudate is too voluminous to derive exclusively from the phloem. Cold, which inhibits phloem transport, did not interfere with exudation. However, ice water applied to the roots, which reduces root pressure, rapidly diminished exudation rate. Sap was seen by microscopic examination to flow primarily from the fascicular phloem in cucumber, and several other cucurbit species, but primarily from the extrafascicular phloem in pumpkin. Following exposure of leaves to 14CO2, radiolabeled stachyose and other sugars were detected in the exudate in proportions expected of authentic phloem sap. Most of this radiolabel was released during the first 20 s. Sugars in exudate were dilute. The sugar composition of exudate from extrafascicular phloem near the edge of the stem differed from that of other sources in that it was high in hexose and low in stachyose. The authors conclude that sap is released from cucurbit phloem upon wounding but contributes negligibly to total exudate volume. The sap is diluted by water from cut cells, the apoplast, and the xylem. Small amounts of dilute, mobile sap from sieve elements can be obtained, although there is evidence that it is contaminated by the contents of other cell types. The function of P-proteins may be to prevent water loss from the xylem as well as nutrient loss from the phloem. American Society of Plant Biologists 2012-04 Article 10 p. Text doi: 10.1104/pp.112.194431 http://digital.library.unt.edu/ark:/67531/metadc102305/ ark: ark:/67531/metadc102305 Plant Physiology, 2012, Rockville: American Society of Plant Biologists, pp. 1873-1882 English Public

info:ark/67531/metadc102299 2013-03-26T11:15:43Z partner:UNTCAS collection:UNTSW access_rights:public

Diet of the American mink Mustela vison and its potential impact on the native fauna of Navarino Island, Cape Horn Biosphere Reserve, Chile Dieta del visón norteamericano Mustela vison y su impacto potencial sobre la fauna nativa de Isla Navarino, Reserva de Biosfera Cabo de Hornos, Chile Sub-Antarctic Biocultural Conservation Program Schüttler, Elke Cárcamo, Jaime Rozzi, Ricardo, 1960- conservation exotic mammals management mustelids waterbirds This article discusses the diet of the American mink Mustela vison. Abstract: Invasive exotic species of mammalian predators represent a major cause of vertebrate animal extinctions on islands, particularly those that lack native mammalian carnivores. In 2001, the American mink (Mustela vison) was recorded for the first time on Navarino Island, in the Cape Horn Biosphere Reserve (55° S) in Chile, representing the southernmost population of mink worldwide. In order to assess its potential impact on native fauna, the authors studied its diet on Navarino Island, as part of an integrative management program on invasive species. Over a three-year period (2005-2007) the authors collected 512 scats in semi-aquatic habitats: marine coasts, riparian and lake shores. Overall, the main prey was mammals (37% biomass), and birds (36%), followed by fish (24%). Over the spring and summer, mink consumed significantly more birds, whereas mammals constituted the main prey over the autumn and winter when migratory birds had left the area. Among birds, the mink preyed mainly on adult Passeriformes, followed by Anseriformes and Pelecaniformes, caught as chicks. Among mammals, the exotic muskrat (Ondatra zibethicus) was the most important prey, and together with the native rodent Abrothrix xanthorhinus it accounted for 78% of the biomass intake. For an integrated management of invasive exotic mammal species on Navarino Island and in the Cape Horn Biosphere Reserve it is important to further research interactions established here among the various introduced mammals, and to initiate immediate control of the mink population in its initial stage of invasion. Sociedad de Biología de Chile 2008 Article 14 p. Text http://digital.library.unt.edu/ark:/67531/metadc102299/ ark: ark:/67531/metadc102299 Revista Chilena de Historia Natural, 2008, Santiago: Sociedad de Biología de Chile, pp. 585-598 English Public

info:ark/67531/metadc102285 2013-04-16T11:56:00Z partner:UNTCAS collection:UNTSW access_rights:public

Geminivirus-Mediated Delivery of Florigen Promotes Determinate Growth in Aerial Organs and Uncouples Flowering from Photoperiod in Cotton McGarry, Roisin C. Ayre, Brian G. Flowering Locus T Single Flower Truss plant architecture genetic diversity This article discusses geminivirus-mediated delivery of florigen. Abstract: Background: Plant architecture and the timing and distribution of reproductive structures are fundamental agronomic traits shaped by patterns of determinate and indeterminate growth. Florigen, encoded by FLOWERING LOCUS T (FT) in Arabidopsis and SINGLE FLOWER TRUSS (SFT) in tomato, acts as a general growth hormone, advancing determinate growth. Domestication of upland cotton (Gossypium hirsutum) converted it from a lanky photoperiodic perennial to a highly inbred, compact day-neutral plant that is managed as an annual row-crop. This dramatic change in plant architecture provides a unique opportunity to analyze the transition from perennial to annual growth. Methodology/Principle Findings: To explore these architectural changes, the authors addressed the role of day-length upon flowering in an ancestral, perennial accession and in a domesticated variety of cotton. Using a disarmed Cotton leaf crumple virus (CLCrV) as a transient expression system, the authors delivered FT to both cotton accessions. Ectopic expression of FT in ancestral cotton mimicked the effects of day-length, promoting photoperiod-independent flowering, precocious determinate architecture, and lanceolate leaf shape. Domesticated cotton infected with FT demonstrated more synchronized fruiting and enhanced "annualization". Transient expression of FT also facilitated simple crosses between wild photoperiodic and domesticated day-neutral accessions, effectively demonstrating a mechanism to increase genetic diversity among cultivated lines of cotton. Virus was not detected in the F₁ progeny, indicating that crosses made by this approach do not harbor recombinant DNA molecules. Conclusions: These findings extend our understanding of FT as a general growth hormone that regulates shoot architecture by advancing organ-specific and age-related determinate growth. Judicious manipulation of FT could benefit cotton architecture to improve crop management. Public Library of Science 2012-05 Article 10 p. Text http://digital.library.unt.edu/ark:/67531/metadc102285/ ark: ark:/67531/metadc102285 PLoS One, 2012, San Francisco: Public Library of Science English Public

info:ark/67531/metadc102280 2013-04-16T13:32:51Z partner:UNTCAS collection:UNTSW access_rights:public

Genetic Manipulation of a "Vacuolar" H+ -PPase: From Salt Tolerance to Yield Enhancement under Phosphorus-Deficient Soils Gaxiola, Roberto A. Sanchez, Charles A. Paez-Valencia, Julio Ayre, Brian G. Elser, James J. food production agriculture plant nutrients sustainability This article discusses genetic manipulation of a "Vacuolar" H+ -PPase. Abstract: Plant scientists face the difficult challenge of increasing food production without further degradation of the environment. In order to protect drinking water resources and prevent the proliferation of harmful algal blooms and "dead zones" in coastal marine ecosystems, it is imperative to reduce anthropogenic nutrient inputs (Conley et al., 2009). These challenges are further compounded by the goal of utilizing agriculture to provide replacement fuels such as biodiesel and alcohol for our oil-based economy. Phosphate (Pi) is an essential macronutrient required for plant growth and development (Chen et al., 2008). Plant nutrient acquisition and partitioning depend on the H+ gradients generated by the plasma membrane H+ -ATPases (Palmgren, 2001; Fuglsang et al., 2011). In this update, the authors discuss the potential role that the type I H+ -proton- pyrophosphatase (PPase) could play in optimizing Pi use efficiency in plants. American Society of Plant Biologists 2012-05 Article 9 p. Text doi: 10.1104/pp.112.195701 http://digital.library.unt.edu/ark:/67531/metadc102280/ ark: ark:/67531/metadc102280 Plant Physiology, 2012, Rockville: American Society of Plant Biologists, pp. 3-11 English Public

info:ark/67531/metadc102289 2013-04-16T11:01:40Z partner:UNTCAS collection:UNTSW access_rights:public

Future Environmental Philosophies and Their Biocultural Conservation Interfaces Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- environmental philosophies cultural conservation ecology This article discusses future environmental philosophies and their biocultural conservation interfaces. University of Georgia 2007 Article 4 p. Text http://digital.library.unt.edu/ark:/67531/metadc102289/ ark: ark:/67531/metadc102289 Ethics and the Environment, 2007, Athens: University of Georgia, pp. 142-145 English Public

info:ark/67531/metadc102294 2013-05-03T14:13:30Z partner:UNTCAS collection:UNTSW access_rights:public

Integrando las Ciencias Ecológicas y la Ética Ambiental en la Conservación Biocultural de los Ecosistemas Templados Subantárticos de Sudamérica Integrating Ecological Sciences and Environmental Ethics into Biocultural Conservation in South American Temperate Sub-Antarctic Ecosystems Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Armesto, Juan J., 1953- Frodeman, Robert ecosystems biocultural conservation environmental ethics This article is in a special issue of Environmental Ethics based on the workshop "Integrating Ecological Sciences and Environmental Ethics: New Approaches to Understanding and Conserving Frontier Ecosystems," held in the temperate sub-Antarctic region of southern Chile, in March 2007. The workshop was jointly organized by the Department of Philosophy and Religion Studies of the University of North Texas (UNT) and the Institute of Ecology and Biodiversity (IEB-Chile), in collaboration with the Center for Environmental Philosophy, and followed a three-week field graduate course, "Conservation and Society: Biocultural Diversity and Environmental Ethics," involving graduate students from the U.S. and Latin America. These events built on a decade of collaboration between UNT environmental philosophers and Chilean ecologists, and were followed by two symposia held subsequently at two annual meetings of the Ecological Society of America (2007 and 2008). University of North Texas 2008 Article 8 p. Text http://digital.library.unt.edu/ark:/67531/metadc102294/ ark: ark:/67531/metadc102294 Environmental Ethics, 2008, Denton: University of North Texas, pp. 9-16 Spanish Integrating Ecological Sciences and Environmental Ethics into Biocultural Conservation in South American Temperate Sub-Antarctic Ecosystems Public

info:ark/67531/metadc102288 2013-04-29T12:16:53Z partner:UNTCAS collection:UNTSW access_rights:public

Implicaciones éticas de narrativas Yaganes y Mapuches sobre las aves de los bosques templados de Sudamérica austral Ethical implications of Yahgan and Mapuche indigenous narratives about the birds of the austral temperate forests of South America Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Avifauna Chile environmental ethics ethno-ornithology intrinsic values instrumental values Mapuche metaphors temperate forests Yahgan This article discusses the ethical implications of Yahgan and Mapuches narratives of the birds of the temperate forests of southern South America. Abstract: This paper analyzes the ethical implications of Yahgan and Mapuche stories about forest birds of southern Chile and Argentina, from the perspective of biological conservation and environmental philosophy. To allow comparisons among notions of traditional ecological knowledge, evolutionary-ecological sciences, and environmental ethics, the author focuses in two well known metaphors: the "tree of life" and the "web of life". The analysis of the first metaphor allows to conclude that both modern sciences and the Yahgan and Mapuche indigenous cosmogonies affirm a common origin for birds and humans. This notion supports the intrinsic value of the avifauna, because birds are regarded as our evolutionary relatives. This implies that, to a certain degree, the life of birds can be subject to moral considerations based on ontological and ethical judgements commensurable with those involved in assessing the value of human life. The analysis of the metaphor of the "web of life" also reveals essential correspondences between contemporary scientific knowledge and Yahgan and Mapuche traditional ecological knowledge regarding the net of biotic interactions and ecosystem processes. Bird stories such as the Green-backed Firecrown (Sephanoides sephaniodes) or omora (in yagán) and the Andean Tapaeulo (Scytalopus magellanicus) or tiftifken (in mapuche) affirm, as much as sciences, that it is necessary to preserve the community of birds, and biodiversity in general, to ensure water supply and other ecosystem services and goods in the long term. The ethical imperatives, implicit in the second metaphor, are consistent with the notion of instrumental value. According to it, the conservation of birds can be regarded as an instrument for human survival. Traditional ornithological knowledge and modern sciences provide support for the instrumental and intrinsic value of biodiversity, today both values appeal for a respectful living together with birds. Neotropical Ornithological Society 2004 Article 10 p. Text http://digital.library.unt.edu/ark:/67531/metadc102288/ ark: ark:/67531/metadc102288 Ornitologia Neotropical, 2004, Saint Louis: Neotropical Ornithological Society, pp. 435-444 English Public

info:ark/67531/metadc102283 2013-04-25T17:21:08Z partner:UNTCAS collection:UNTSW access_rights:public

The Hunting Behavior of Black-Shouldered Kites (Elanus Caeruleus Leucurus) in Central Chile Sub-Antarctic Biocultural Conservation Program Jaksić, Fabian M. Rozzi, Ricardo, 1960- Labra, Antonieta Jiménez, Jaime hunting behaviors hunting success hovering black-shouldered kites central Chile This article discusses the hunting behavior of black-shouldered kites in central Chile. Abstract: Kites of the genus Elanus are found throughout the world principally in open areas such as grasslands, sparse shrublands, and agricultural fields (Brown and Amadon 1968). Because of their characteristic hover-hunting, and their widespread distribution, these kites make interesting subjects for analyses of their hunting behavior. Such studies have been conducted in several regions, including North America (Waian and Stendall 1970, Warner and Rudd 1974, Koplin et al. 1980), Europe (Amat 1979, Heredia 1983), Africa (Tarboton 1978, Mendelsohn 1982), and Australia (Baker-Gabb 1984). However, quantitative information on the hunting behavior of South American kites was nonexistent until now, and is reported here from a locality in central Chile. Cooper Ornithological Society 1987 Article 5 p. Text http://digital.library.unt.edu/ark:/67531/metadc102283/ ark: ark:/67531/metadc102283 The Condor, 1987, Waco: Cooper Ornithological Society, pp. 907-9011 English Public

info:ark/67531/metadc102293 2013-05-03T14:27:37Z partner:UNTCAS collection:UNTSW access_rights:public

Integrating Ecological Sciences and Environmental Ethics into Biocultural Conservation in South American Temperate Sub-Antarctic Ecosystems Integrando las Ciencias Ecológicas y la Ética Ambiental en la Conservación Biocultural de los Ecosistemas Templados Subantárticos de Sudamérica Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- Armesto, Juan J., 1953- Frodeman, Robert ecosystems biocultural conservation environmental ethics This article is in a special issue of Environmental Ethics based on the workshop "Integrating Ecological Sciences and Environmental Ethics: New Approaches to Understanding and Conserving Frontier Ecosystems," held in the temperate sub-Antarctic region of southern Chile, in March 2007. The workshop was jointly organized by the Department of Philosophy and Religion Studies of the University of North Texas (UNT) and the Institute of Ecology and Biodiversity (IEB-Chile), in collaboration with the Center for Environmental Philosophy, and followed a three-week field graduate course, "Conservation and Society: Biocultural Diversity and Environmental Ethics," involving graduate students from the U.S. and Latin America. These events built on a decade of collaboration between UNT environmental philosophers and Chilean ecologists, and were followed by two symposia held subsequently at two annual meetings of the Ecological Society of America (2007 and 2008). University of North Texas 2008 Article 7 p. Text http://digital.library.unt.edu/ark:/67531/metadc102293/ ark: ark:/67531/metadc102293 Environmental Ethics, 2008, Denton: University of North Texas, pp. 229-234 English Integrando las Ciencias Ecológicas y la Ética Ambiental en la Conservación Biocultural de los Ecosistemas Templados Subantárticos de Sudamérica Public

info:ark/67531/metadc102290 2013-05-14T17:01:32Z partner:UNTCAS collection:UNTSW access_rights:public

De las ciencias ecológicas a la ética ambiental From ecological sciences to environmental ethics Sub-Antarctic Biocultural Conservation Program Rozzi, Ricardo, 1960- environmental ethics ecological sciences society nature Leopold, Aldo This article discusses ecological sciences and environmental ethics. The ecological and evolutionary sciences provide a "mental image" that offers a spectrum of relationships between society and the natural world broader than that used by classical economics and ethics. Evolutionary sciences claim humans share a common origin with the other biological species. Ecological sciences recognize that human beings establish interactions with a multitude of biological species and ecosystem processes, and more recently emphasized that the welfare of human communities and biotic communities are complementary (Rozzi 2001, Millenium Ecosystem Assessment 2005). Sociedad de Biología de Chile 2007 Article 14 p. Text http://digital.library.unt.edu/ark:/67531/metadc102290/ ark: ark:/67531/metadc102290 Revista Chilena de Historia Natural, 2007, Santiago: Sociedad de Biología de Chile, pp. 521-534 Spanish Public

info:ark/67531/metadc102286 2013-05-14T17:24:38Z partner:UNTCAS collection:UNTSW access_rights:public

Late-Summer Presence of the Patagonian Tyrant, Colorhamphus Parvirostris (Darwin) on Navarino Island, Cape Horn County, Chile Presencia de la Viudita, Colorhamphus Parvirostris (Darwin) a Fines de Verano en Isla Navarino, Comuna Cabo De Hornos, Chile Sub-Antarctic Biocultural Conservation Program McGehee, Steven M. Rozzi, Ricardo, 1960- Anderson, Christopher B. Ippi, Silvina Vásquez, Rodrigo A. Woodland, Sue Colorhamphus parvirostris Navarino Island mist-netting reverse migration Sub-Antarctic forests Tyrannidae This article discusses the late-summer presence of the Patagonian tyrant, Colorhamphus parvirostris (Darwin) on Navarino Island, Cape Horn County, Chile. Abstract: The southernmost representative of the Tyrannidae, a diversified family with approximately 420 species endemic to the Americas, belongs to a monotypic genus Colorhamphus with only one species: C. parvirostris. Little is known about the Patagonian tyrant, which is considered rare throughout its breeding range and vulnerable to the forest disturbances and habitat fragmentation. Even its distribution and life history are poorly known. During the breeding season it migrates to higher latitudes (>40°S) in southern Chile and Argentina, but small numbers remain within central-southern latitudes year-round (30-40°S). In the high latitudes of Tierra del Fuego it is said to be an accidental visitor, but records of C. parvirostris are extremely rare. As part of the long-term mistnetting and bird census program at the Omora Ethnobotanical Park on Navarino Island, Cape Horn County, Chile (55°S) a total of 1,542 birds belonging to 17 species have been captured with mistnets on Navarino Island. Only 12 were C. parvirostris (<1%). Therefore, this species is indeed rare. However, from 2000 to 2003 all of the few Patagonian tyrants have been captured from late March and April. Its presence on Navarino Island could have become more frequent due to an extension of its latitudinal range associated with global climate change. However, additional observations made on successive years during late summer and fall suggest an alternative, and perhaps complementary, explanation - a short southward migration performed by some individuals prior to their northward migration. This would be the first time that this phenomena is reported for the Southern Hemisphere. Taken together these two hypotheses could re-enforce one other, whereby the southern limit of post-reproductive southerly migrations could be extending due to global warming. Universidad de Magallanes 2004 Article 9 p. Text http://digital.library.unt.edu/ark:/67531/metadc102286/ ark: ark:/67531/metadc102286 Anales Instituto Patagonia, 2004, Magallanes: Universidad de Magallanes, pp. 25-33 English Public

info:ark/67531/metadc103256 2013-03-19T15:58:21Z partner:UNTCAS collection:UNTSW access_rights:public

Controlled terahertz frequency response and transparency of Josephson chains and superconducting multilayers Yampol'skii, V. A. Savel'ev, Sergey Usatenko, O. V. Mel'nik, S. S. Kusmartsev, F. V. Krokhin, Arkadii A. Nori, Franco wave propagation terahertz frequency electromagnetic waves This article discusses controlled terahertz frequency response and transparency of Josephson chains and superconducting multilayers. Abstract: A fundamental property of wave propagation is Anderson localization, which affects the transfer of information, energy, mass, and charge in disordered media. This localization can manifest itself via, e.g., the metal-insulator transition. We exactly map the behavior of a quantum particle moving in a potential with correlated disorder to teh sub-terahertz wave propagation in either Josephson chaines or superconducting multilayers. When the Josephson junction parameters vary randomly, the sub-THz electromagnetic waves cannot propagate through these Josephson structures due to localization. For parameter variations with long-range correlations, we predict sharp transitions from transparent to reflective frequency regions for Josephson plasma waves. With appropriate choices of the correlation function, frequency windows with targeted or designed transparencies for THz or sub-THz electromagnetic waves could be achieved. This could be useful for tailoring the electromagnetic wave spectrum of Josephson arrays within the THz frequency range, which is important for applications in physics, astronomy, chemistry, biology, and medicine. American Physical Society 2007-01-26 Article 7 p. Text doi: 10.1103/PhysRevB.75.014527 http://digital.library.unt.edu/ark:/67531/metadc103256/ ark: ark:/67531/metadc103256 Physical Review B, 2007, College Park: American Physical Society English Public

info:ark/67531/metadc103255 2013-03-19T15:42:31Z partner:UNTCAS collection:UNTSW access_rights:public

Controllable enhanced dragging of light in ultradispersive media Rostovtsev, Yuri V. Davuluri, Sankar Fizeau effects electromagnetically induced transparency coherent population trapping ultradispersive media This article discusses controllable enhanced dragging of light in ultradispersive media. Abstract: We have theoretically demonstrated an enhanced Fizeau effect due to dragging the light that occurs when the group velocity of light is ultraslow. The proposed experiment can be done in a cell of atomic Rb vapor under conditions such that the group velocity of light is of the order of a few hundred meters per second. We show theoretically that higher-order dispersion can influence the Fizeau effect and can be observed experimentally. It has been shown that the change of phase is sensitive to the motion of the cell with the speed of the order of 10⁻³ cm/s and for possible displacements as small as 10 Å. The enhanced dragging effect can be applied for position control, detection of slow mechanical motion, and efficient modulators of light. American Physical Society 2012-07-05 Article 7 p. Text doi: 10.1103/PhysRevA.86.013806 http://digital.library.unt.edu/ark:/67531/metadc103255/ ark: ark:/67531/metadc103255 Physical Review A, 2012, College Park: American Physical Society English Public

info:ark/67531/metadc103257 2013-03-12T12:41:20Z partner:UNTCAS collection:UNTSW access_rights:public

Analytical solutions for a two-level system driven by a class of chirped pulses Jha, Pankaj K. Rostovtsev, Yuri V. chirped pulses quantum systems lasers optical pulses In this article, the authors present analytical solutions for the problem of a two-level atom driven by a class of chirped pulses. The solutions are given in terms of Heun functions. By use of the appropriate chirping parameters, an enhancement of four orders of magnitude in the population transfer is obtained. American Physical Society 2010-07-06 Article 4 p. Text doi: 10.1103/PhysRevA.82.015801 http://digital.library.unt.edu/ark:/67531/metadc103257/ ark: ark:/67531/metadc103257 Physical Review A, 2010, College Park: American Physical Society English Public

info:ark/67531/metadc103270 2013-03-18T17:42:54Z partner:UNTCAS collection:UNTSW access_rights:public

Coherent control of refractive index in far-detuned Λ systems O'Brien, Chris Anisimov, Petr M. Rostovtsev, Yuri V. Kocharovskaya, Olga density-matrix electromagnetic fields refractive indexes This article discusses the coherent control of refraction index in far-detuned Λ systems. Abstract: Enhancement and control of the index of refraction in a mixture of two three-level atomic species that form a pair of far-detuned Λ schemes under two-photon resonance and has been studied. We employ the density-matrix approach to properly take population relaxation into account and to describe the interaction of each Λ system with the electromagnetic fields. Both Λ systems are driven by a corresponding far-detuned coherent field at one atomic transition and are probed by the same weak field. In the dressed-state basis, it represents a superposition of effective two-level subsystems with the positions, widths, and amplitudes of the resonances controlled by the driving fields and allows for efficient control of the susceptibility of the total system; leading to refractive index (RI) enhancement with vanishing absorption in the absence of amplification. We analyze the experimental implementation of such a system in a cell of Rb atoms with a natural abundance of isotopes. An upper limit estimate of the RI enhancement is obtained. American Physical Society 2011-12-15 Article 8 p. Text doi: 10.1103/PhysRevA.84.063835 http://digital.library.unt.edu/ark:/67531/metadc103270/ ark: ark:/67531/metadc103270 Physical Review A, 2012, College Park: American Physical Society English Public

info:ark/67531/metadc103262 2013-03-18T17:44:59Z partner:UNTCAS collection:UNTSW access_rights:public

Coherent excitation of a two-level atom driven by a far-off-resonant classical field: Analytical solutions Jha, Pankaj K. Rostovtsev, Yuri V. two-level atoms coherent excitation Heun functions This article discusses the coherent excitation of a two-level atom driven by a far-off-resonant classical field. Abstract: We present an analytical treatment of coherent excitation of a two-level atom driven by a far-off-resonant classical field. A class of pulse envelope is obtained for which this problem is exactly solvable. The solutions are given in terms of the Heun function, which is a generalization of the hypergeometric function. Degeneracy of the Heun to a hypergeometric equation can give all the exactly solvable pulse shapes of Gauss hypergeometric form from the generalized pulse shape obtained here. We discuss the application of the results obtained to the generation of soft x-ray and ultraviolet radiations. American Physical Society 2010-03-15 Article 8 p. Text doi: 10.1103/PhysRevA.81.033827 http://digital.library.unt.edu/ark:/67531/metadc103262/ ark: ark:/67531/metadc103262 Physical Review A, 2010, College Park: American Physical Society English Public

info:ark/67531/metadc103266 2013-03-18T17:33:28Z partner:UNTCAS collection:UNTSW access_rights:public

Coherent control of atomic excitation using off-resonant strong few-cycle pulses Jha, Pankaj K. Eleuch, Hichem Rostovtsev, Yuri V. few-cycle pulses many-cycle pulses lasers This article discusses coherent control of atomic excitation using off-resonant strong few-cycle pulses. Abstract: We study the dynamics of a two-level system driven by an off-resonance few-cycle pulse which has a phase jump ø at t = t₀, in contrast to many-cycle pulses, under the nonrotating-wave approximation (NRWA). We give a closed form analytical solution for the evolution of the probability amplitude |Cₐ(t)| for the upper level. Using the appropriate pulse parameters like the phase jump ø, jump time t₀, pulse width Շ, frequency ν, and Rabi frequency Ώ₀ the population transfer after the pulse is gone can be optimized and, for the pulse considered here, an enhancement factor of 10⁶-10⁸ was obtained. American Physical Society 2010-10-20 Article 4 p. Text doi: 10.1103/PhysRevA.82.045805 http://digital.library.unt.edu/ark:/67531/metadc103266/ ark: ark:/67531/metadc103266 Physical Review A, 2010, College Park: American Physical Society English Public

info:ark/67531/metadc103274 2013-03-18T13:32:51Z partner:UNTCAS collection:UNTSW access_rights:public

Carrier-Envelope Phase Effect on Atomic Excitation by Few-Cycle rf Pulses Li, Hebin Sautenkov, Vladimir A. Rostovtsev, Yuri V. Kash, Michael M. Anisimov, Petr M. Welch, George R. Scully, Marlan O. carrier-envelope-phase radio-frequency pulses pulses density matrix equations This article discusses carrier-envelope phase effect on atomic excitation by few-cycle rf pulses. Abstract: We present an experimental and theoretical study of the carrier-envelope phase effects on population transfer between two bound atomic states interacting with intense ultrashort pulses. Radio frequency pulses are used to transfer population among the ground state hyperfine levels in rubidium atoms. These pulses are only a few cycles in duration and have Rabi frequencies of the order of the carrier frequency. The phase difference between the carrier and the envelope of the pulses has a significant effect on the excitation of atomic coherence and population transfer. The authors provide a theoretical description of this phenomenon using density matrix equations. The authors discuss the implications and possible applications of their results. American Physical Society 2010-03-08 Article 4 p. Text doi: 10.1103/PhysRevLett.104.103001 http://digital.library.unt.edu/ark:/67531/metadc103274/ ark: ark:/67531/metadc103274 Physical Review Letters, 2010, College Park: American Physical Society English Public

info:ark/67531/metadc103259 2013-04-02T12:05:15Z partner:UNTCAS collection:UNTSW access_rights:public

Electromagnetically induced transparency controlled by a microwave field Li, Hebin Sautenkov, Vladimir A. Rostovtsev, Yuri V. Welch, George R. Hemmer, Philip R. Scully, Marlan O. (Marlan Orvil), 1939- microwave fields optical fields electromagnetic This article discusses electromagnetically induced transparency controlled by a microwave field. Abstract: We have experimentally studied the propagation of two optical fields in a dense rubidium (Rb) gas in the case when an additional microwave field is coupled to the hyperfine levels of Rb atoms. The Rb energy levels form a close-Λ three-level system coupled to the optical fields and the microwave field. It has been found that the maximum transmission of the probe field depends on the relative phase between the optical and the microwave fields. We have observed both constructive and destructive interferences in electromagnetically induced transparency. A simple theoretical model and a numerical simulation have been developed to explain the observed experimental results. American Physical Society 2009-08-21 Article 9 p. Text doi: 10.1103/PhysRevA.80.023820 http://digital.library.unt.edu/ark:/67531/metadc103259/ ark: ark:/67531/metadc103259 Physical Review A, 2009, College Park: American Physical Society English Public

info:ark/67531/metadc103276 2013-04-02T12:16:44Z partner:UNTCAS collection:UNTSW access_rights:public

Electron localization in a two-channel tight-binding model with correlated disorder Bagci, V. M. K. Krokhin, Arkadii A. localization lengths DNA nucleotides This article discusses electron localization in a two-channel tight-binding model with correlated disorder. Abstract: We calculate the localization length in a two-channel tight-binding model for correlated disordered site potential. Both intra- and interchannel correlations are taken into account. The localization length is obtained in quadratic approximation by expanding the two-channel conductance over weak disorder. The result is applied to a simple two-stranded model of DNA molecule and it is shown that a strong pair coupling between the basic nucleotides in the strands is not sufficient to delocalize electronic states. American Physical Society 2007-10-05 Article 7 p. Text doi: 10.1103/PhysRevB.76.134202 http://digital.library.unt.edu/ark:/67531/metadc103276/ ark: ark:/67531/metadc103276 Physical Review B, 2007, College Park: American Physical Society English Public

info:ark/67531/metadc103277 2013-04-01T16:32:57Z partner:UNTCAS collection:UNTSW access_rights:public

Effective dielectric constants of photonic crystal of aligned anisotropic cylinders and the optical response of a periodic array of carbon nanotubes Reyes, E. Krokhin, Arkadii A. Roberts, James A. anisotropic crystals photonic crystals carbon nanotubes This article discusses effective dielectric constants of photonic crystal of aligned anisotropic cylanders and the optical response of a periodic array of carbon nanotubes. Abstract: We calculate the static dielectric tensor of a periodic system of aligned anisotropic dielectric cylinders. Exact analytical formula for the effective dielectric constants for the H-eigenmodes is obtained for arbitrary 2D Bravais lattice and arbitrary cross section of anisotropic cylinders behaves like uniaxial or biaxial natural crystals. The developed theory of homogenization of anisotropic cylinders is applied for calculations of the dielectric properties of photonic crystals of carbon nanotubes. American Physical Society 2005-10-25 Article 4 p. Text doi: 10.1103/PhysRevB.72.155118 http://digital.library.unt.edu/ark:/67531/metadc103277/ ark: ark:/67531/metadc103277 Physical Review B, 2005, College Park: American Physical Society English Public

info:ark/67531/metadc103258 2012-09-24T12:38:53Z partner:UNTCAS collection:UNTSW access_rights:public

Tracking molecular wave packets in cesium dimers by coherent Raman scattering Yuan, Luqi Murawski, Robert K. Ariunbold, Gombojav O. Zhi, Miaochan Wang, Xi Sautenkov, Vladimir A. Rostovtsev, Yuri V. Siebert, Torsten Sokolov, Alexei V. wave-packet dynamics wave-packet dynamics cesium dimers molecules In this article, the authors explore wave-packet dynamics in the ground X ¹Σg+ and excited B ¹Πu states of cesium dimers (Cs₂). In particular, the authors study the dependence of the wave-packet dynamics on the relative timing between femtosecond pump, Stokes, and probe pulses in a nondegenerate BOXCARS beam geometry, which are commonly used for coherent anti-Stokes Raman scattering (CARS) spectroscopy. The experimental results are elucidated by theoretical calculations, which are based on the Liouville equations for the density matrix for the the molecular states. The authors observe oscillations in CARS signals as functions of both Stokes and probe pulse delays with respect to the pump pulse. The oscillation period relates to the wave-packet motion cycle in either the ground or excited state of Cs₂ molecules, depending on the sequence of the input laser pulses in time. The performed analysis can be applied to study and/or manipulate wave-packet dynamics in a variety of molecules. It also provides an excellent test platform for theoretical models of molecular systems. American Physical Society 2012-08-31 Article 10 p. Text doi: 10.1103/PhysRevA.86.023421 http://digital.library.unt.edu/ark:/67531/metadc103258/ ark: ark:/67531/metadc103258 Physical Review A, 2012, College Park: American Physical Society English Public

info:ark/67531/metadc103269 2012-09-24T12:38:53Z partner:UNTCAS collection:UNTSW access_rights:public

Ultradispersive adaptive prism based on a coherently prepared atomic medium Sautenkov, Vladimir A. Li, Hebin Rostovtsev, Yuri V. Scully, Marlan O. optical prisms atomic vapors spectral angular dispersion ultradispersive prisms In this article, the authors have experimentally demonstrated an ultra-dispersive optical prism made from a coherently driven Rb atomic vapor. The prism possesses spectral angular dispersion that is 6 orders of magnitude higher than that of a prism made of optical glass; such angular dispersion allows one to spatially resolve light beams with different frequencies separated by a few kilohertz. The prism operates near the resonant frequency of atomic vapor and its dispersion is optically controlled by a coherent driving field. American Physical Society 2010-06-23 Article 6 p. Text doi: 10.1103/PhysRevA.81.063824 http://digital.library.unt.edu/ark:/67531/metadc103269/ ark: ark:/67531/metadc103269 Physical Review A, 2010, College Park: American Physical Society English Public

info:ark/67531/metadc103271 2012-09-24T12:38:53Z partner:UNTCAS collection:UNTSW access_rights:public

Microwave absorption by an array of carbon nanotubes: A phenomenological model Ye, Z. Deering, W.D. Krokhin, Arkadii Roberts, J.A. nanotubes electromagnetic energy microwaves wave equations This article discusses microwave absorption by an array of carbon nanotubes. A simple model to explain microwave-induced heating of carbon nanotubes (CNTs) through transformation of electromagnetic energy into mechanical vibrations is proposed and analyzed. The model provides a way to understand recent observations of heating of CNTs exposed to microwaves in the range of 2-20 GHz. It is shown that transverse vibrations of CNTs during microwave irradiation can be associated with parametric resonance, as occurs in the analysis of acoustic experiments on forced longitudinal vibrations of a stretched elastic string. For carbon nanotubes [single wall nanotube (SWNT), double wall nanotube (DWNT), multiwall nanotube (MWNT), ropes, and strands] the resonant parameters are shown to be located in a region of instability of the Mathieu's equation. Wave equations with cubic nonlinearity were used to qualitatively describe the effects of phonon-phonon interactions and energy transfer from microwaves to CNTs at a rate much exceeding the traditional Joule heating via electron-phonon interaction. American Physical Society 2006-08-29 Article 5 p. Text doi: 10.1103/PhysRevB.74.075425 http://digital.library.unt.edu/ark:/67531/metadc103271/ ark: ark:/67531/metadc103271 Physical Review B, 2006, College Park: American Physical Society English Public

info:ark/67531/metadc103278 2012-09-24T12:38:53Z partner:UNTCAS collection:UNTSW access_rights:public

Surface and waveguide Josephson plasma waves in slabs of layered superconductors Slipchenko, T.M. Kadygrob, D.V. Bogdanis, D. Yampol'skii, V.A. Krokhin, Arkadii superconductors plasma waves electromagnetic In this article, the authors discuss the propagation of symmetric and antisymmetric Josephson plasma waves in a slab of layered superconductor clad between two identical dielectrics. The authors predict two branches of surface waves in the terahertz frequency range, one above and another below the Josephson plasma frequency. Apart from this, there exists a discrete set of waveguide modes with electromagnetic fields oscillating across the slab thickness and decaying exponentially away from the slab. The authors consider the excitation of the predicted waves by means of the attenuated-total-reflection method. It is shown that for a specific set of the parameters of the structure, the excitation of the waveguide modes is accompanied by the total suppression of specular reflection. American Physical Society 2011-12-20 Article 8 p. Text doi: 10.1103/PhysRevB.84.224512 http://digital.library.unt.edu/ark:/67531/metadc103278/ ark: ark:/67531/metadc103278 Physical Review B, 2011, College Park: American Physical Society English Public

info:ark/67531/metadc103265 2012-09-24T12:38:53Z partner:UNTCAS collection:UNTSW access_rights:public

Low-frequency index of refraction for a two-dimensional metallodielectric photonic crystal Krokhin, Arkadii Reyes, E. Gumen, L. photonic crystals electromagnetic fields In this article, the authors calculate analytically the effective index of refraction n(eff) of a periodic arrangement of nonmagnetic metallic cylinders in the low-frequency limit. At ω→0 the dielectric constant of the cylanders is singular, ﾼm(ω)≈-(ωp/ω)², allowing propagation in the plane of periodicity of a mode with the magnetic field parallel to the cylanders (H polarization). The in-plane electric field induces eddy currents, which are localized in a narrow skin layer. The authors show that the magnetic moment of the eddy current leads to diamagnetic response if the radius of the cylanders is larger than the skin depth δ-10⁻⁵ cm. Otherwise, the cylinders are transparent for the electromagnetic field and their magnetic moment can be neglected. Magnetization of the cylinders gives rise to distinct values of the quasistatic and static indices of refraction and explains a paradox with noncommuting limits ﾼm→∞ and ω→0. American Physical Society 2007-01-29 Article 5 p. Text doi: 10.1103/PhysRevB.75.045131 http://digital.library.unt.edu/ark:/67531/metadc103265/ ark: ark:/67531/metadc103265 Physical Review B, 2007, College Park: American Physical Society English Public

info:ark/67531/metadc103264 2012-09-24T12:38:53Z partner:UNTCAS collection:UNTSW access_rights:public

Observation of picosecond superfluorescent pulses in rubidium atomic vapor pumped by 100-fs laser pulses Ariunbold, Gombojav O. Kash, Michael M. Sautenkov, Vladimir A. Li, Hebin Rostovtsev, Yuri V. Welch, George R. Scully, Marlan O. superfluorescent atoms laser pulses In this article, the authors study the superfluorescence (SF) from a gas of rubidium atoms. The atoms of a dense vapor are excited to the 5D state from the 5S state by a two-photon process driven by 100-fx laser pulses. The atoms decay to the 6P state and then to the 5S state. The SF emission at 420 nm on the 6P-5S transition is recorded by a streak camera with picosecond time resolution. The time duration of the generated SF is tens of picoseconds, which is much shorter than the time scale of the usual relaxation processes, including spontaneous emission and atomic coherence dephasing. The dependence of the time delay between the reference input pulse and SF is measured as a function of laser power. THe experimental data are described quantitatively by a simulation based on the semiclassical atom-field interaction theory. The observed change in scaling laws for the peak intensity and delay time can be elucidated by an SF theory in which the sample length is larger than the cooperation length. American Physical Society 2010-10-20 Article 9 p. Text doi: 10.1103/PhysRevA.82.043421 http://digital.library.unt.edu/ark:/67531/metadc103264/ ark: ark:/67531/metadc103264 Physical Review A, 2010, College Park: American Physical Society English Public

info:ark/67531/metadc103263 2012-09-24T12:38:53Z partner:UNTCAS collection:UNTSW access_rights:public

Symmetry-induced tunneling in one-dimensional disordered potentials Diez, Enrique Izrailev, F.M. Krokhin, Arkadii Rodriguez, A. tunneling wave packets circuits This article discusses symmetry-induced tunneling in one-dimensional disordered potentials. A nontraditional mechanism of tunneling at macroscopic distances is proposed for a wave packet localized in a one-dimensional disordered potential with mirror symmetry, V(-x)=V(x). Unlike quantum tunneling through a regular potential barrier, which occurs only at the energies lower than the barrier height, the proposed mechanism of tunneling exists even for weak white-noise-like scattering potentials. It also exists in classical circuits of resonant contours with random resonant frequencies. The latter property may be used as a new method of secure communication, which does not require coding and decoding of the transmitting signal. American Physical Society 2008-07-17 Article 5 p. Text doi: 10.1103/PhysRevB.78.035118 http://digital.library.unt.edu/ark:/67531/metadc103263/ ark: ark:/67531/metadc103263 Physical Review B, 2008, College Park: American Physical Society English Public

info:ark/67531/metadc103268 2012-09-24T12:38:53Z partner:UNTCAS collection:UNTSW access_rights:public

Propagation of 0π pulses in a gas of three-level atoms Sun, Dong Sariyanni, Zoe-Elizabeth Das, Sumanta Rostovtsev, Yuri V. Gaussian electromagnetic fields laser pulses probe pulses In this article, the authors have theoretically studied the pulsed regime of electromagnetically induced transparency. In particular, simulations of propagation of Gaussian and 0π copropagating laser pulses in a medium consisting of three-level Λ atoms have been performed. It has been found that even at the two-photon resonance, the length of propagation for the 0π pulses is much smaller than the one for the Gaussian probe pulses. Using the dark and bright basis, the authors explain this behavior. Some possible applications are discussed. American Physical Society 2011-06-15 Article 10 p. Text doi: 10.1103/PhysRevA.83.063815 http://digital.library.unt.edu/ark:/67531/metadc103268/ ark: ark:/67531/metadc103268 Physical Review A, 2012, College Park: American Physical Society English Public

info:ark/67531/metadc103275 2013-04-02T16:26:42Z partner:UNTCAS collection:UNTSW access_rights:public

Enhancement of Localization in One-Dimensional Random Potentials with Long-Range Correlations Kuhl, Ulrich Izrailev, Felix M. Krokhin, Arkadii A. random potentials single-mode waveguide scatterers This article discusses the enhancement of localization in one-dimensional random potentials with long-range correlations. Abstract: We experimentally study the effect of enhancement of localization in weak one-dimensional random potentials. Our experimental setup is a single-mode waveguide with 100 tunable scatterers periodically inserted into the waveguide. By measuring the amplitudes of transmitted and reflected waves in the spacing between each pair of scatterers, we observe a strong decrease of the localization length when white-noise scatterers are replaced by a correlated arrangement of scatterers. American Physical Society 2008-03-28 Article 4 p. Text doi: 10.1103/PhysRevLett.100.126402 http://digital.library.unt.edu/ark:/67531/metadc103275/ ark: ark:/67531/metadc103275 Physical Review Letters, 2008, College Park: American Physical Society English Public

info:ark/67531/metadc103261 2013-04-08T17:59:15Z partner:UNTCAS collection:UNTSW access_rights:public

Experimental observation of carrier-envelope-phase effects by multicycle pulses Jha, Pankaj K. Rostovtsev, Yuri V. Li, Hebin Sautenkov, Vladimir A. Scully, Marlan O. (Marlan Orvil), 1939- carrier-envelope-phase multicycle pulses radio-frequency pulses Rabi frequency This article discusses experimental observation of carrier-envelope-phase effects by multicycle pulses. Abstract: We present an experimental and theoretical study of carrier-envelope-phase (CEP) effects on the population transfer between two bound atomic states interacting with pulses consisting of many cycles. Using intense radio-frequency pulse with Rabi frequency of the order of the atomic transition frequency, the authors investigate the influence of the CEP on the control of phase-dependent multiphoton transitions between the Zeeman sublevels of the ground state of ⁸⁷Rb. Our scheme has no limitation on the duration of the pulses. Extending the CEP control to longer pulses creates interesting possibilities to generate pulses with accuracy that is better than the period of optical oscillations. American Physical Society 2011-03-10 Article 6 p. Text doi: 10.1103/PhysRevA.83.033404 http://digital.library.unt.edu/ark:/67531/metadc103261/ ark: ark:/67531/metadc103261 Physical Review A, 2012, College Park: American Physical Society English Public

info:ark/67531/metadc103267 2013-04-10T15:44:07Z partner:UNTCAS collection:UNTSW access_rights:public

Femtosecond wave-packet dynamics in cesium dimers studied through controlled stimulated emission Yuan, Luqi Ariunbold, Gombojav O. Murawski, Robert K. Pestov, Dmitry Wang, Xi Patnaik, Anil K. Sautenkov, Vladimir A. Sokolov, Alexei V. Rostovtsev, Yuri V. Scully, Marlan O. (Marlan Orvil), 1939- cesium dimers wave packets pump-probe techniques Liouville equation This article discusses femtosecond wave-packet dynamics in cesium dimers studied through controlled stimulated emission. Abstract: We study the dynamics of wave packets in cesium dimers using a femtosecond-controlled pump-probe technique. We implement configurations with one pulse (pump) or two pulses (pump to control) to produce vibrational wave packets on the electronic excited state. The transmission of an additional, variable-delay probe pulse is measured to monitor the time evolution of the wave packets. In the case of the pump-control-probe configuration, a superposition of two independent wave packets is observed. In order to elucidate the observed experimental data, we develop a theory based on the Liouville equation for the density matrix associated with the Franck-Condon factors. Both the numerical and analytical calculations are in good agreement with our experimental results. American Physical Society 2010-05-12 Article 8 p. Text doi: 10.1103/PhysRevA.81.053405 http://digital.library.unt.edu/ark:/67531/metadc103267/ ark: ark:/67531/metadc103267 Physical Review A, 2010, College Park: American Physical Society English Public

info:ark/67531/metadc103260 2013-04-16T13:09:44Z partner:UNTCAS collection:UNTSW access_rights:public

Generation of correlated binary sequences from white noise Izrailev, Felix M. Krokhin, Arkadii A. Makarov, N. M. Usatenko, O. V. white noise binary sequences correlation properties This article discusses the generation of correlated binary sequences from white noise. Abstract: We suggest a method for generation of random binary sequences of elements 0 and 1, with prescribed correlation properties. It is based on a modification of the widely used convolution method of constructing continuous random processes. Using this method, a binary sequence with a power-law decaying pair correlator can be easily generated. American Physical Society 2007-08-21 Article 4 p. Text doi: 10.1103/PhysRevE.76.027701 http://digital.library.unt.edu/ark:/67531/metadc103260/ ark: ark:/67531/metadc103260 Physical Review E, 2007, College Park: American Physical Society English Public

info:ark/67531/metadc103272 2013-04-29T17:45:49Z partner:UNTCAS collection:UNTSW access_rights:public

Inhomogeneous DNA: Conducting exons and insulating introns Krokhin, Arkadii A. Bagci, V. M. K. Izrailev, Felix M. Usatenko, O. V. Yampol'skii, V. A. DNA exons introns nucleotides This article discusses inhomogeneous DNA. Abstract: Parts of DNA sequences known as exons and introns play very different roles in coding and storage of genetic information. Here, the authors show that their conducting properties are also very different. Taking into account long-range correlations among four basic nucleotides that form double-stranded DNA sequence, the authors calculate electron localization length for exon and intron regions. Analyzing different DNA molecules, the authors obtain that the exons have narrow bands of extended states, unlike the introns where all the states are well localized. The band of extended states is due to a specific form of the binary correlation function of the sequence of basic DNA nucleotides. American Physical Society 2009-08-17 Article 6 p. Text doi: 10.1103/PhysRevB.80.085420 http://digital.library.unt.edu/ark:/67531/metadc103272/ ark: ark:/67531/metadc103272 Physical Review B, 2009, College Park: American Physical Society English Public

info:ark/67531/metadc103273 2013-05-21T17:25:04Z partner:UNTCAS collection:UNTSW access_rights:public

Long-range surface plasmons in dielectric-metal-dielectric structure with highly anisotropic substrates Nagaraj Krokhin, Arkadii A. plasmons long-range surface plasmons dielectric crystals This article discusses long-range surface plasmons in dielectric-metal-dielectric structure with highly anisotropic substrates. Abstract: We present a theoretical study of long-range surface plasmons propagating in a thin metallic film clad between two identical uniaxial anisotropic dielectric crystals. We show that the proper orientation of the optical axis of the crystal with respect to the metal surface enhances the propagation length in a wide range of frequencies, including the telecommunication region. To increase the role of anisotropy than the natural optical crystals. We propose Kronig-Penney model for plasmonic crystal where the substrate is a periodic sequence of dielectric delta peaks. In this model the dispersion relation for surface plasmon has a band structure where the band width tends to zero when the frequency approaches the resonant frequency. American Physical Society 2010-02-22 Article 9 p. Text doi: 10.1103/PhysRevB.81.085426 http://digital.library.unt.edu/ark:/67531/metadc103273/ ark: ark:/67531/metadc103273 Physical Review B, 2010, College Park: American Physical Society English Public

info:ark/67531/metadc103279 2013-05-21T17:17:10Z partner:UNTCAS collection:UNTSW access_rights:public

Long-range propagation of surface plasmons in a thin metallic film deposited on an anisotropic photonic crystal Krokhin, Arkadii A. Neogi, Arup McNeil, David plasmonic devices anisotropic photonic crystals optoelectronic devices surface plasmon This article discusses long-range propagation of surface plasmons in a thin metallic film deposited on an anisotropic photonic crystal. Abstract: We propose using a strongly anisotropic dielectric as a substrate for plasmonic devices. We show that the propagation range of surface plasmons is increased if the substrate is a birefringent dielectric crystal with a properly oriented optical axis. The increase of the propagation range depends on the degree of anisotropic is weak. However, in specially designed photonic crystals, the anisotropy may be very strong, thus leading to appreciable increase of the propagation range. A photonic-crystal substrate, being a medium with nonlinear dispersion, also affects the dispersion law of the surface plasmon. All these effects may increase the efficiency of modern plasmonic and optoelectronic devices. American Physical Society 2007-06-15 Article 5 p. Text doi: 10.1103/PhysRevB.75.235420 http://digital.library.unt.edu/ark:/67531/metadc103279/ ark: ark:/67531/metadc103279 Physical Review B, 2007, College Park: American Physical Society English Public

info:ark/67531/metadc107806 2013-03-19T14:44:57Z partner:UNTCAS collection:UNTSW access_rights:public

Computational Study of Polarizabilities and Second Hyperpolarizabilities of Inorganic Transition Metal Thiometalates and Metalates in Solution Cundari, Thomas R., 1964- Kurtz, Henry A. Zhou, Tie nonlinear optical inorganic transition metals thiometalates metalates This article discusses a computational study of polarizabilities and second hyperpolarizabilities of inorganic transition metal thiometalates and metalates in solution. Abstract: A systematic study of nonlinear optical (NLO) properties of inorganic transition metal (TM) thiometalates and metalates is reported. Polarizabilities (α) and second hyperpolarizabilities (y) are calculated in solution within the polarizable continuum model. It is found that NLO properties of anionic inorganic complexes can be successfully modeled in solution, when this cannot be done so in the gas phase. Solvent effects are found to significantly increase α and y. The effects are stronger on y (up to 80%) than on α (up to 40%) and stronger on TM thiometalates than on metalates. For α, solvent effects are found to be more important than electron correlation effects. For y, the two effects are similarly important. Solvent effects on α and y caused by subordinate factors other than the dominant electrostatic solute-solvent interactions were studied and assessed to be negligible. Upon solvation, large TM and ligand modification effects on α and y are found. One oxo-to-sulfido substitution results in an increase in α by 38 au and y by 10 000 au. American Chemical Society 2000-03-08 Article 7 p. Text doi: 10.1021/jp993838l http://digital.library.unt.edu/ark:/67531/metadc107806/ ark: ark:/67531/metadc107806 Journal of Physical Chemistry A, 2000, Washington DC: American Chemical Society, pp. 4711-4717 English Public

info:ark/67531/metadc107798 2013-03-14T16:20:44Z partner:UNTCAS collection:UNTSW access_rights:public

[Review] Chemistry of Advanced Materials: An Overview Cundari, Thomas R., 1964- nonlinear optical chemical vapor deposition materials science This book review discusses 'Chemistry of Advanced Materials: An Overview', edited by Leonard V. Interrante from Renssalaer Polytechnic Institute, and Mark J. Hampden-Smith from the University of New Mexico. American Chemical Society 1998-12-29 Review 1 p. Text doi: 10.1021/ja985537f http://digital.library.unt.edu/ark:/67531/metadc107798/ ark: ark:/67531/metadc107798 Journal of the American Chemical Society, 1998, Washington DC: American Chemical Society, pp. 490-490 English Public

info:ark/67531/metadc107796 2013-03-14T16:21:13Z partner:UNTCAS collection:UNTSW access_rights:public

[Review] Deciphering the Chemical Code: Bonding Across the Periodic Table Cundari, Thomas R., 1964- chemical bonding electronic structure theory computational chemistry This book review discusses 'Deciphering the Chemical Code: Bonding Across the Periodic Table' by Nicolaos D. Epiotis from the University of Washington. The reviewer describes the work as a new theoretical framework for describing chemical bonding and gives specific information on what's covered in the book, the themes, and ideal audiences. American Chemical Society 1997-08-20 Review 1 p. Text doi: 10.1021/ja965712x http://digital.library.unt.edu/ark:/67531/metadc107796/ ark: ark:/67531/metadc107796 Journal of the American Chemical Society, 1997, Washington DC: American Chemical Society, pp. 7908-7908 English Public

info:ark/67531/metadc107789 2013-03-15T14:36:55Z partner:UNTCAS collection:UNTSW access_rights:public

Carbon-Oxygen Bond Formation via Organometallic Baeyer-Villiger Transformations: A Computational Study on the Impact of Metal Identity Figg, Travis M. Webb, Joanna R. Cundari, Thomas R., 1964- Gunnoe, T. Brent carbon-oxygen bonds metal identity density functional theory This article discusses a computational study on the impact of metal identity. Abstract: Metal-mediated formation of C-O bonds is an important transformation that can occur by a variety of mechanisms. Recent studies suggest that oxygen-atom insertion into metal-hydrocarbyl bonds in a reaction that resembles the Baeyer-Villiger transformation is a viable process. In an effort to identify promising new systems, this study is designed to assess the impact of metal identity on such O-atom insertions for the reaction [(bpy)ₓM(Me)(OOH)]ⁿ → [(bpy)ₓM(OMe)(OH)]ⁿ (x = 1 or 2; bpy = 2,2'-bipyridyl; n is varied to maintain the d-electron count at d⁶ or d⁸). Six d⁸-square-planar complexes (M = Ptᴵᴵ, Pdᴵᴵ, Niᴵᴵ, Irᴵ, Rhᴵ, and Coᴵ) and eight d⁶-octahedral systems (M = Irᴵᴵᴵ, Rhᴵᴵᴵ, Coᴵᴵᴵ, Feᴵᴵ, Ruᴵᴵ, Osᴵᴵ, Mnᴵ, and Tcᴵ) are studied. Using density functional theory calculations, the structures and energies of ground-state and transition-state species are elucidated. This study shows clear trends in calculated ∆G‡'s for the O-atom insertions. The organometallic Baeyer-Villiger insertions are favored by lower coordination numbers (x = 1 versus x = 2), earlier transition metals, and first-row (3d) transition metals. American Chemical Society 2011-12-20 Article 8 p. Text doi: 10.1021/ja2102778 http://digital.library.unt.edu/ark:/67531/metadc107789/ ark: ark:/67531/metadc107789 Journal of the American Chemical Society, 2012, Washington DC: American Chemical Society, pp. 2332-2339 English Public

info:ark/67531/metadc107781 2013-03-15T14:09:10Z partner:UNTCAS collection:UNTSW access_rights:public

Carbon-Hydrogen Bond Activation by Titanium Imido Complexes. Computational Evidence for the Role of Alkane Adducts in Selective C-H Activation Cundari, Thomas R., 1964- Klinckman, Thomas R. Wolczanski, Peter T. carbon-hydrogen bonds titanium imido alkane adducts This article discusses carbon-hydrogen bond activation by Titanium imido complexes. Abstract: This paper reports calculations that probe the role of R (hydrocarbon) and R' (ligand substituent) effects on the reaction coordinate for C-H activation: Ti(OR')₂(=NR') + RH → adduct → transition state → (OR')₂Ti(N(H)R')(R). Compounds with R = H, Me, Et, Vy, cPr, Ph, Cy, Bz, and cubyl are studied using quantum (R' = H, SiH₃, SiMe₃) and classical (R' = SiᵗBu₃) techniques. Calculated geometries are in excellent agreement with data for experimental models. There is little variability in the calculated molecular structure of the reactants, products, and most interestingly, transition states as R and R' are changed. Structural flexibility is greatest in the adducts Ti(OR')₂(=NR')•••HR. Despite the small structural changes observed for Ti(OR')₂(=NR') with different R', significant changes are manifested in calculated electronic properties (the Mulliken charge on Ti becomes more positive and the Ti=N bond order decreases with larger R'), changes that should facilitate C-H activation. Substantial steric modification of the alkane complex is expected from R-R' interactions, given the magnitude of ∆Gadd and the conformational flexibility of the adduct. Molecular mechanics simulations of Ti(OSiᵗBu₃)₂(=NSiᵗBu₃)•••isopentane adducts yield an energy ordering as a function of the rank of the C-H bond coordinated to Ti that is consistent with experimental selectivity patterns. Calculated elimination barriers compare very favorably with experiment; larger SiH₃ and TMS ligand substituents generally yield better agreement with experiment, evidence that the modeling of the major contributions to the elimination barrier (N-H and C-H bond making) is ostensibly correct. Calculations indicate that weakening the C-H bond of the hydrocarbon yields a more strongly bound adduct. Combining the different conclusions, the present computational research points to the adduct, specifically the structure and energetics of the substrate/Ti-imido interaction, as the main factor in determining the selectivity of hydrocarbon (R) C-H activation. American Chemical Society 2002-01-19 Article 7 p. Text doi: 10.1021/ja0162481 http://digital.library.unt.edu/ark:/67531/metadc107781/ ark: ark:/67531/metadc107781 Journal of the American Chemical Society, 2002, Washington DC: American Chemical Society, pp. 1481-1487 English Public

info:ark/67531/metadc107777 2013-03-15T12:28:41Z partner:UNTCAS collection:UNTSW access_rights:public

Calculation of a Methane C-H Oxidative Addition Trajectory: Comparison to Experiment and Methane Activation by High-Valent Complexes Cundari, Thomas R., 1964- methane high-valent complexes effective core potentials intrinsic reaction coordinate This article discusses the calculation of a methane C-H oxidative addition trajectory. Abstract: An effective core potential (ECP), parallel supercomputing study of methane activation by 14-electron, Ir(PH₃)₂(X) complexes (X = H, Cl) is presented. Considerable weakening of the coordinated methane C-H bond occurs upon formation of an ɳ²-CH coordinated (X)(PH₃)₂Ir•••HCH₃ adduct. A more strongly bound adduct (with greater weakening of the coordinated C-H bond) occurs when X = Cl versus X = H. The calculated Ir(PH₃)₂(H) + CH₄ → Ir(PH₃)₂(H)₂(Me) reaction enthalpy is -12.8 kcal mol⁻¹, and -41.6 kcal mol⁻¹ for the chloro analogue. The intrinsic reaction coordinate is calculated and compared to an experimental trajectory. Analysis of the wave function along the intrinsic reaction coordinate (IRC) suggests that although donation of electron density from methane to metal is essential for adduct formation, it is not until backdonation to σ* сʜ increases that the C-H bond is activated and cleaved. The electronic and molecular structure of the reacting system along the IRC suggest a two-stage mechanism: substrate to complex donation is important in the early part of the reaction (electrophilic stage) while complex to substrate backdonation is necessary later on (nucleophilic stage) for C-H scission. Finally, comparison of IRCs for low- and high-valent methane-activating complexes shows similar topology in the early portion of the activation event; differentiation between oxidative addition and σ-bond metathesis occurs at the point at which there is a shift from the electrophilic to nucleophilic stage of the reaction. American Chemical Society 1994-01 Article 8 p. Text doi: 10.1021/ja00080a039 http://digital.library.unt.edu/ark:/67531/metadc107777/ ark: ark:/67531/metadc107777 Journal of the American Chemical Society, 1994, Washington DC: American Chemical Society, pp. 340-347 English Public

info:ark/67531/metadc107780 2013-03-14T16:24:24Z partner:UNTCAS collection:UNTSW access_rights:public

Stepwise Reduction of Dinitrogen Bond Order by a Low-Coordinate Iron Complex Smith, Jeremy M. Lachicotte, Rene J. Pittard, Karl A. Cundari, Thomas R., 1964- Lukat-Rodgers, Gudrun Rodgers, Kenton R. Holland, Patrick L. chemical processes nitrogen-containing compounds iron dinitrogen This article discusses stepwise reduction of dinitrogen bond order by a low-coordinate iron complex. Conversion of atmospheric N₂ into NH₃ is one of the most important chemical processes, because ammonia is the industrial and biological precursor to many nitrogen-containing compounds. Large-scale transformation of N₂ and H₂ into ammonia is performed in industry by the Haber-Bosch process, using "potassium-promoted" porous iron. A view of the N₂-reducing active site of iron-molybdenum nitrogenase, which contains unusual iron atoms with only three sulfur donors, is shown in Chart 1. The presence of iron in the active sites of this and other nitrogenases suggests that iron is again important for activating dinitrogen. Thus iron plays a major role in both natural and industrial N₂ reduction catalysis. American Chemical Society 2001-08-24 Article Text doi: 10.1021/ja016094+ http://digital.library.unt.edu/ark:/67531/metadc107780/ ark: ark:/67531/metadc107780 Journal of the American Chemical Society, 2001, Washington DC: American Chemical Society, pp. 9222-9223 English Public

info:ark/67531/metadc107797 2013-03-14T16:24:41Z partner:UNTCAS collection:UNTSW access_rights:public

Structural Dichotomy in Six-Coordinate d⁰ Complexes: Trigonal Prismatic (ᵗBu₃SiC≡C)₆Ta⁻ and Octahedral (ᵗBu₃SiC≡C)₆M²⁻ (M = Zr, Hf) Vaid, Thomas P. Veige, Adam S. Lobkovsky, Emil B. Glassey, Wingfield V. Wolczanski, Peter T. Liable-Sands, Louise M. Rheingold, Arnold L. Cundari, Thomas R., 1964- metal polyacetylides d⁰ hexaacetylides This article discusses structural dichotomy in six-coordinate d⁰ complexes. Utilization of the bulky acetylide, ᵗBu₃SiC≡C⁻, enabled the synthesis of several early metal polyacetylides. Addition of NaC≡CH to ᵗBu₃SiBr in dimethyl sulfoxide afforded ᵗBu₃SiC≡CH, which was deprotonated to yield ᵗBu₃SiC≡CLi. Treatment of ZrCl₄, HfCl₄, adn TaCl₅ with varying amounts of ᵗBu₃SiC≡CLi gave {(THF)₂Li(ᵗBu₃SiC≡C)₂}Zr(C≡CSiᵗBu₃)₃(THF) (1; THF = tetrahydrofuran), {Et₂O)Li(ᵗBu₃SiC≡C)₂}Hf(C≡CSiᵗBu₃)₃(OEt₂) (2), {Li(ᵗBu₃SiC≡C)₃}₂M(M = Zr, 6; Hf, 7), and {Li(ᵗBu₃SiC≡C)₃}Ta(C≡CSiᵗBu₃)₃ (3). Metathesis of 3 with KOTf generated KTa(C≡CSiᵗBu₃)₆ (4) and cation sequestration of 4 with crypt 2.2.2 provided [K(crypt 2.2.2)][Ta(C≡CSiᵗBu₃)₆](5). Single-crystal X-ray structural studies determined the structures (core symmetry) of 1 (Oh), 2, (Oh), 3 (D₃), 5 (D₃), 6 (Oh), and 7 (Oh). The D₃h to D₃ twist in 3 and 5 has a steric origin, and the counterion position appears inconsequential. Origins of the structural preferences illustrated by the dichotomous twisted trigonal prismatic and octahedral cores of the d⁰ hexaacetylides 5 and 6 were probed through density functional (ADF) and effective core potential (GAMESS) calculations. The structural difference results from a lessening electronic preference for the trigonal prism-primarily a greater HOMO/LUMO gap-upon moving from Ta to Zr, minor steric factors, and increased interligand repulsions in the dianion (VSEPR). American Chemical Society 1998-09-19 Article 13 p. Text doi: 10.1021/ja9802899 http://digital.library.unt.edu/ark:/67531/metadc107797/ ark: ark:/67531/metadc107797 Journal of the American Chemical Society, 1998, Washington DC: American Chemical Society, pp. 10067-10079 English Public

info:ark/67531/metadc107801 2013-03-18T17:11:33Z partner:UNTCAS collection:UNTSW access_rights:public

CO₂ Reduction on Transition Metal (Fe, Co, Ni, and Cu) Surfaces: In Comparison with Homogeneous Catalysis Liu, Cong Cundari, Thomas R., 1964- Wilson, Angela K. transition metals density functional theory Perdew-Burke-Ernzerhof heterogeneous catalysis This article discusses CO₂ reduction on transition metal (Fe, Co, Ni, and Cu) surfaces. Abstract: Reduction of CO₂ to CO on Fe, Co, Ni, and Cu surfaces has been studied using density functional theory (DFT) methods. Three reaction steps were studied: (a) adsorption of CO₂ (M + CO₂/M) (M = transition metal surface), (b) decomposition of CO₂ (CO₂/M = (CO + O)/M), and (c) desorption of CO ((CO + O)/M = O/M + CO). Binding energies and reaction energies were calculated using the generalized gradient approximation (GGA) via the Perdew-Burke-Ernzerhof (PBE) functional. Calculations show an interesting trend for reaction energies and total reaction barriers, as a function of metal: from Fe to Cu, reactions tend to be less exergonic; the metals earlier in the 3d series have lower total barriers for CO₂ reduction. However, "overbinding" of CO₂ on Fe causes a thermodynamic sink on the reaction coordinate, adn Co and Ni are more favorable in terms of a smaller fluctuation in reaction energies/barriers for these elementary catalytic steps. A Brønsted-Evans-Polanyi (BEP) relationship was analyzed for C-O bond scission of CO₂ on the metal surfaces. Heterogeneous catalysis is also compared with the homogeneous models using transition metal β-diketiminato complexes, showing that both heterogeneous and homogeneous catalysis of CO₂ reduction display the same energetic trend as a function of metal. American Chemical Society 2012-02-22 Article 8 p. Text doi: 10.1021/jp210480c http://digital.library.unt.edu/ark:/67531/metadc107801/ ark: ark:/67531/metadc107801 Journal of Physical Chemistry C, 2012, Washington DC: American Chemical Society, pp. 5681-5688 English Public

info:ark/67531/metadc107767 2013-03-14T15:55:20Z partner:UNTCAS collection:UNTSW access_rights:public

Activation of Carbon-Hydrogen and Hydrogen-Hydrogen Bonds by Copper-Nitrenes: A Comparison of Density Functionality Theory with Single- and Multireference Correlation Consistent Composite Approaches Tekarli, Sammer M. Williams, T. Gavin Cundari, Thomas R., 1964- density functional theory correlation consistent Composite Approach copper-mediated nitrene This article discusses a comparison of density functional theory with single- and multireference correlation consistent composite approaches. Abstract: The kinetics and thermodynamics of copper-mediated nitrene insertion into C-H and H-H bonds (the former of methane) have been studied using several levels of theory: B3LYP/6-311++G(d,p), B97-1/cc-pVTZ, PBE1KCIS/cc-pVTZ, and ccCA (correlation consistent Composite Approach). The results show no significant difference among the DFT methods. All three DFT methods predict the ground state of the copper-nitrene model complex, L'Cu(NH), to be a triplet, while single reference ccCA predicts the singlet to be the ground state. The contributions to the total ccCA energy indicate that the singlet state is favored at the MP2/CBS level of theory, while electron correlation beyond this level (CCSD(T)) favors a triplet state, resulting in a close energetic balance between the two states. A multireference ccCA method is applied to the nitrene active species and supports the assignment of a singlet ground state. In general, the largest difference in the model reaction cycles between DFT and ccCA methods is for processes involving radicals and bond dissociation. American Chemical Society 2009-10-19 Article 8 p. Text doi: 10.1021/ct900277m http://digital.library.unt.edu/ark:/67531/metadc107767/ ark: ark:/67531/metadc107767 Journal of Chemical Theory and Computation, 2009, Washington DC: American Chemical Society, pp. 2959-2966 English Public

info:ark/67531/metadc107776 2013-03-14T16:23:51Z partner:UNTCAS collection:UNTSW access_rights:public

Small Molecule Elimination from Group IVB (Ti, Zr, Hf) Amido Complexes Cundari, Thomas R., 1964- Gordon, Mark S. amido complexes transition states molecules This article discusses small molecule elimination from group IVB (Ti, Zr, Hf) amido complexes. An ab initio quantum chemical analysis of HX (X = H, CH₃, Cl, NH₂, SiH₃) elimination by group IVB (Ti, Zr, Hf) amidos (H₂(X)M - NH₂ → H₂M = NH + HX), of interest in the context of CVD precursor design, is reported. Several deductions may be drawn from the calculations. First, in the transition state (TS) for HX elimination, electropositive and electroneutral X give rise to metal-transannular hydrogen (Ht) distances only slightly longer than normal metal-terminal hydride bonds lengths, while electronegative X groups yield substantially longer MHt distances. Second, the HX elimination barrier (∆Hǂelim) is lower when HX is polarized Hδ- • Hδ+ (X = SiH₃) or nonpolar (X = H). Third, a plot of calculated ∆Hǂelim versus MHt distances in the TS. Fourth, analysis of the electronic structure along the intrinsic reaction coordinate (IRC) supports the importance of N-H•••M agostic interactions preceding N-H scission. Fifth, the IRC shows the MHt distance decreasing as Ht is transferred from N to X, reaching a minimum when the transfer is roughly half complete, and then increasing once more is HX is eliminated. These results point to the leaving group (X) playing a crucial role in tuning the bonding the energetics of the TS, and thus the rate of HX elimination. The results lead to the conclusion that materials precursors designed to enhance MHt interaction, through the intermediacy of X, in the TS and along the reaction coordinate will lead to lower activation barriers to XH elimination. American Chemical Society 1993-05 Article 8 p. Text doi: 10.1021/ja00063a044 http://digital.library.unt.edu/ark:/67531/metadc107776/ ark: ark:/67531/metadc107776 Journal of the American Chemical Society, 1993, Washington DC: American Chemical Society, pp. 4210-4217 English Public

info:ark/67531/metadc107775 2013-03-14T16:28:41Z partner:UNTCAS collection:UNTSW access_rights:public

Transition Metal Imido Complexes Cundari, Thomas R., 1964- transition metal imido molecular orbital core potentials molecular structures This articles discusses transition metal imido complexes. A wide range of transition metal imido (TMI) complexes is studied using ab initio molecular orbital (MO) calculations. The main computational point of interest is the further testing of effective core potentials (ECPs) and valence basis sets to allow for the accurate calculation of properties for reasonably sized transition metal complexes. On the chemical side, several results from the study are to be noted. The agreement between geometries for calculated models and their experimental counterparts ranges from very good to excellent, as found in previous studies of multiply bonded transition metal-group IVA complexes. Taken together, these data suggest that the accuracy one has come to expect for the prediction of structural properties for main-group compounds may yet become a reality for transition metal complexes. The correct prediction of molecular structure also leads one to infer that the bonding in these complexes is also accurately described. The MC/LMO/CI (multiconfigurational/localized MO/configuration interaction) technique shows that eight resonance structures are most significant in the description of the metal-imido linkage. Three of these account for roughly two-thirds of the total contributions; two resonance structures, both possessing a dative σ bond, correspond to novel bonding descriptions for TMI complexes. The dative character of the σ bond has been largely unappreciated. The MC/LMO/CI results also indicate that the metal-imido bond is intermediate between a double and a triple bond. Nucleophilic resonance structures decrease as one goes to the right in the transition series while electrophilic ones show the reverse behavior, in agreement with observed reactivity. American Chemical Society 1992-09-01 Article 10 p. Text doi: 10.1021/ja00046a037 http://digital.library.unt.edu/ark:/67531/metadc107775/ ark: ark:/67531/metadc107775 Journal of the American Chemical Society, 1992, Washington DC: American Chemical Society, pp. 7879-7888 English Public

info:ark/67531/metadc107790 2013-03-18T13:16:58Z partner:UNTCAS collection:UNTSW access_rights:public

C-H Functionalization Reactivity of a Nickel-Imide Wiese, Stefan McAfee, Jason L. Pahls, Dale R. McMullin, Claire L. Cundari, Thomas R., 1964- Warren, Timothy H. hydrocarbyl radicals dinickel imide C-H amination systems This article discusses C-H functionalization reactivity of a Nickel-Imide. Abstract: We report report bifunctional reactivity of the β-diketiminato Ni(III)-imide [Me₃NN]Ni=NAd (1), which undergoes H-atom abstraction (HAA) reactions with benzylic substrates R-H (indane, ethylbenzene, toluene). Nickel-imide 1 competes with the nickel-amide HAA product [Me₃NN]Ni-NHAd (2) for the resulting hydrocarbyl radical R• to give the nickel-amide [Me₃NN]Ni-N(CHMePh)Ad (3) (R-H = ethylbenzene) or aminoalkyl tautomer [Me₃NN]Ni(ɳ²-CH(Ph)NHAd) (4) (R-H = toluene). A significant amount of functionalized amine R-NHAd is observed in the reaction of 1 with indane along with the dinickel imide {[Me₃NN]Ni}₂(μ-NAd) (5). Kinetic and DFT analyses point to rate-limiting HAA from R-H by 1 to give R•, which may add to either imide 1 or amide 2, each featuring significant N-based radical character. Thus, these studies illustrate a fundamental competition possible in C-H amination systems that proceed via a HAA/radical rebound mechanism. American Chemical Society 2012-05-22 Article 8 p. Text doi: 10.1021/ja302149k http://digital.library.unt.edu/ark:/67531/metadc107790/ ark: ark:/67531/metadc107790 Journal of the American Chemical Society, 2012, Washington DC: American Chemical Society, pp. 10114-10121 English Public

info:ark/67531/metadc107779 2013-03-21T17:03:16Z partner:UNTCAS collection:UNTSW access_rights:public

Deoxygenations of (silox)₃WNO and R₃PO by (silox)₃M (M = V, Ta) and (silox)₃NbL (silox = ᵗBu₃SiO): Consequences of Electronic Effects Veige, Adam S. Slaughter, Lee M. Wolczanski, Peter T. Matsunaga, Nikita Decker, Stephen A. Cundari, Thomas R., 1964- deoxygenations electronic effects organic synthesis This article discusses the consequences of electronic effects. Oxygen atom transfers involving metal-oxo functionalities are central to many biological transformations , prominent in applications to organic synthesis, and of increasing importance in inorganic systems as synthetic tools, objectives in biomimicry, and targets of fundamental studies. As a synthetic route to (silox)₃WN (4, silox = ᵗBu₃SiO), the deoxygenation of (silox)₃WNO (2) by (silox)₃Ta (1-Ta) was attempted without success, despite ample precedent in cleavages of epoxides, N₂O, NO, CO₂, and CO. A comparison study involving sources of M(silox)₃ (1-M; M = V, Nb, Ta) revealed that features of deoxygenations of 2 and R₃PO) (R = Me, Ph, ᵗBu) are the consequences of electronic effects enforced by a limiting steric environment. American Chemical Society 2001-06-06 Article Text doi: 10.1021/ja004329w http://digital.library.unt.edu/ark:/67531/metadc107779/ ark: ark:/67531/metadc107779 Journal of the American Chemical Society, 2001, Washington DC: American Chemical Society, pp. 6419-6420 English Public

info:ark/67531/metadc107793 2013-03-18T17:29:36Z partner:UNTCAS collection:UNTSW access_rights:public

Cobalt-Dinitrogen Complexes with Weakened N-N Bonds Ding, Keying Pierpont, Aaron W. Brennessel, William W. Lukat-Rodgers, Gudrun Rodgers, Kenton R. Cundari, Thomas R., 1964- Holland, Patrick L. Bill, E. (Eckhard), 1953- cobalt-dinitrogen complexes N-N bonds nitrogen transition metals This article discusses research on cobalt-dinitrogen complexes with weakened N-N bonds. Abstracts: Reported N₂ complexes of cobalt do not have substantial weakening of the N-N bond. Using diketiminate ligands to enforce three-coordinate geometries, we have synthesized several novel CoNNCo complexes. In formally univalent complexes, cobalt is poorer than iron at weakening the N-N bond, but in formally zerovalent complexes, cobalt and iron give similar N-N weakening. The weakening is due to cobalt-to-N₂ π-backbonding, and potassium cations pull more electron density into N₂. These results show that the low coordination number of a trigonal-planar geometry is impetus enough to make even the electronegative cobalt weaken the N-N bond of N₂. American Chemical Society 2009-06-19 Article 2 p. Text doi: 10.1021/ja808783u http://digital.library.unt.edu/ark:/67531/metadc107793/ ark: ark:/67531/metadc107793 Journal of the American Chemical Society, 2009, Washington DC: American Chemical Society, pp. 9471-9472 English Public

info:ark/67531/metadc107783 2013-04-02T12:42:27Z partner:UNTCAS collection:UNTSW access_rights:public

Electronically Unsaturated Three-Coordinate Chloride and Methyl Complexes of Iron, Cobalt, and Nickel Holland, Patrick L. Cundari, Thomas R., 1964- Perez, Lanyn L. Eckert, Nathan A. Lachicotte, Rene J. three-coordinate chloride methyl ligands electrons This article discusses electronically unsaturated three-coordinate chloride and methyl complexes of iron, cobalt, and nickel. Abstract: Three-coordinate organometallic complexes are rare, especially with the prototypical methyl ligand. Using a hindered, rigid bidentate ligand (L), it is possible to create 12-electron methyliron (II) and 13-electron methylcobalt (II) complexes. These complexes are thermally stable, and ¹H NMR spectra suggest that the low coordination number is maintained in solution. Attempts to create the 14-electron LNiCH₃ led instead to the three-coordinate nickel(I) complex LNi(THF). Single crystals of LMCH₃ are isomorphous with the new three-coordinate chloride complexes LNiCl and LCoCl. Along with the recently reported LFeCl (Smith, J.M.; Lachicotte, R.J.; Holland, P.L. Chem Commun. 2001, 1542), these are the only examples of three-coordinate iron(II), cobalt(II), and nickel(II) complexes with terminal chloride ligands, enabling the systematic evaluation of the effect of coordination number and metal identity on M-Cl bond lenghts. Electronic structure calculations predict the ground states of the trigonal complexes. American Chemical Society 2002-11-08 Article 9 p. Text doi: 10.1021/ja025583m http://digital.library.unt.edu/ark:/67531/metadc107783/ ark: ark:/67531/metadc107783 Journal of the American Chemical Society, 2002, Washington DC: American Chemical Society, pp. 14416-14424 English Public

info:ark/67531/metadc107778 2013-04-01T16:14:51Z partner:UNTCAS collection:UNTSW access_rights:public

An Effective Core Potential Study of Transition-Metal Chalcogenides. 1. Molecular Structure Benson, Michael T. Cundari, Thomas R., 1964- Lim, Soon J. Nguyen, Hoang D. Pierce-Beaver, Karen transition metals chalcogenides molecular structures This article discusses an effective core potential study of transition-metal chalcogenides. Abstract: A structural analysis is reported of roughly 150 transition-metal (TM)-chalcogenido complexes in a variety of chemical environments. With few exceptions, agreement between calculated and experimental geometries is excellent. The research provides convincing evidence that computational methods employed are adequately describing the bonding in these diverse TM complexes. Interesting trends in relative TMCh (Rмсh-Rмсh) bond lengths are found. Experimental and computational data show that other than the zirconocene-and halfnocene-oxos there is similar behavior in relative bond lengths for widely varying TM-chalcogenido complexes. Relative bond lengths versus oxo (S-O, Se-O, and Te-O) in group IVB metallocenes tend to be larger than for other families of complexes and show less variation among the heavier chalcogens (Se-S, Te-S, and Te-Se). Analysis of localized wave functions for Cp₂ZrCh point to a greater contribution from a singly-bonded Zr-Ch structure (relative to Zr=Ch) when Ch is O compared to heavier chalcogens. Taken together, the data suggest that there is a fundamental difference in the Zr-oxo (and Hf-oxo) bond in relation to heavier chalcogens, consistent with recent experimental data. In previous studies of multiply bonded TM complexes the authors have focused on the ability of ECPs to make computations feasible for complexes incorporating even the heaviest transition metals. The present work also evaluates ECP methods for heavier main group (MG) elements. The chalcogens (CH) O, S, Se, and Te are included in this study. American Chemical Society 1994-05 Article 12 p. Text doi: 10.1021/ja00088a035 http://digital.library.unt.edu/ark:/67531/metadc107778/ ark: ark:/67531/metadc107778 Journal of the American Chemical Society, 1994, Washington DC: American Chemical Society, pp. 3955-3966 English Public

info:ark/67531/metadc107773 2013-03-14T16:17:58Z partner:UNTCAS collection:UNTSW access_rights:public

Principal Resonance Contributors to High-Valent, Transition-Metal Alkylidene Complexes Cundari, Thomas R., 1964- Gordon, Mark S. transition metals alkylidene complexes carbene bonding This article discusses principal resonance contributors to high-valent, transition-metal alkylidene complexes. The results of ab initio calculations are reported for prototypical high-valent, alkylidene complexes. Stationary points on each potential energy surface are characterized and compared to experimental information where available; as long as a suitably flexible valence basis set is used, good agreement between theoretically calculated and experimentally determined geometries is obtained. The complexes of interest include group IVB (Ti, Zr and Hf) and group VB (Nb and Ta) alkylidenes with hydride ligands as well as models for the four-coordinate, olefin metathesis catalysts (Mo-, W-, and Re-alkylidenes) which have been recently synthesized and characterized. In light of the fact that much of the discussion concerning the reactivity of transition-metal carbene complexes has been presented in terms of the resonance contributors derived from rearranging the electrons in the M-C σ and π orbitals, the minima obtained from the portion of the study are then subjected to a further procedure to calculate these contributions. Resonance structures in which the carbon is the negative end of the M-C bond (i.e., nucleophilic resonance structures) contribute 50% to the ground-state wave function of these complexes. Those in which the carbon is formally neutral account for much of the remainder (45%). Only 5% is comprised of electrophilic resonance structures, i.e., those in which the carbon is the positive end of the M-C bond. Furthermore, the metal-carbon double bond is predominantly comprised of five resonance structures. Four of these resonance structures correspond to models of carbene bonding which have been discussed previously in the literature. The other resonance structure, which contributes roughly 33% to the ground-state wave function, has hitherto not been considered when examining the chemical reactivity of carbenes. This large resonance contributor can be described as arising from a dative carbon-to-metal σ bond plus a covalent M-C π bond. American Chemical Society 1991-07 Article 13 p. Text doi: 10.1021/ja00014a015 http://digital.library.unt.edu/ark:/67531/metadc107773/ ark: ark:/67531/metadc107773 Journal of the American Chemical Society, 1991, Washington DC: American Chemical Society, pp. 5231-5243 English Public

info:ark/67531/metadc107782 2013-03-14T16:18:17Z partner:UNTCAS collection:UNTSW access_rights:public

A Priori Assessment of the Stereoelectronic Profile of Phosphines and Phosphites Cooney, Katharine D. Cundari, Thomas R., 1964- Hoffman, Norris W. Pittard, Karl A. Temple, M. Danielle Zhao, Yong stereoelectronic profiles phosphines phosphites ligands This article discusses research that has demonstrated the utility of a rigorously calibrated, molecular mechanics/semiempirical quantum mechanical protocol for developing stereoelectronic (Tolman) maps for phosphine ligands. A computational analysis of alkyl and aryl phosphines in common usage suggests that these ligands are quite similar stereoelectronically. A noticeable gap int he Tolman map for common phosphines is observed for large, electron-poor phosphines. Several candidates meeting these criteria were identified, the most promising of which is P(t-C₄F₉)₃. Phosphines in which the phosphorus participates in a ring, which comprise a very small subset of reported phosphines, have very interesting stereoelectronic properties, particularly those in which the ligating phosphorus is part of a three-membered ring. In terms of steric properties, the symmetric deformation coordinate proposed by Orpen and co-workers on the basis of crystallographic studies is calculated with sufficient accuracy using PM3(tm) to allow good confidence in predictions of novel phosphines. For quantification of the electronic properties of phosphines, the authors analyzed changes in the CO stretching frequency upon changing the ancillary phosphine ligands. American Chemical Society 2003-03-15 Article 7 p. Text doi: 10.1021/ja021254i http://digital.library.unt.edu/ark:/67531/metadc107782/ ark: ark:/67531/metadc107782 Journal of the American Chemical Society, 2003, Washington DC: American Chemical Society, pp. 4318-4324 English Public

info:ark/67531/metadc107807 2013-03-14T16:14:15Z partner:UNTCAS collection:UNTSW access_rights:public

Methane Activation by Group IVB Imido Complexes Cundari, Thomas R., 1964- methane alkane complexes This article discusses methane activation by group IVB imido complexes. An ab initio study of methane activation by group IVB imido complexes, when coupled with available experimental data, reveals an interesting picture of this important reaction. Initial interaction of methane and (H)₂M=NH leads to the formation of alkane complexes bound by ≈9 kcal mol⁻¹. Experiment indicates that the polarity of the metal-ligand bond upon which the C-H is activated plays an important role in facilitating subsequent scission. Calculations support this hypothesis and suggest that formation of the alkane complex acts to increase Cδ-Hδ polarization, setting the stage for C-H cleavage. Calculated methane elimination barriers for (H)₂M(CH₃)(NH₂) (M=Ti, Zr, Hf) are in good agreement with experimental models in terms of absolute numbers and trends as a function of metal. Calculated methane activation barriers follow the order Ti > Zr > Hf, in line with calculated exothermicities. Calculated geometries indicate a late transition state for methane elimination, in agreement with experimentally determined activation parameters. The TSs have a kite-shaped geometry with an obtuse angle about the H of the C-H bond being activated (Ht) and a short MHt distance, 1-2% greater than normal. The short MHt distance suggests a stabilizing interaction, supported by a positive bond overlap population. Calculation of the intrinsic reaction coordinate demonstrates the importance of agostic interactions between N-H and M along the reaction coordinate. American Chemical Society 1992 Article 7 p. Text doi: 10.1021/ja00052a060 http://digital.library.unt.edu/ark:/67531/metadc107807/ ark: ark:/67531/metadc107807 Journal of the American Chemical Society, 1992, Washington DC: American Chemical Society, pp. 10557-10563 English Public

info:ark/67531/metadc107771 2012-10-09T10:02:29Z partner:UNTCAS collection:UNTSW access_rights:public

Speed of Sound in Periodic Elastic Composites Krokhin, Arkadii Arriaga, J. Gumen, L. homogenization sound waves phononic crystals In this article, the authors consider the low-frequency limit (homogenization) for propagation of sound waves in periodic elastic medium (phononic crystals). Exact analytical formulas for the speed of sound propagating in a three-dimensional periodic arrangement of liquid and gas or in a two-dimensional arrangement of solids are derived. The authors apply their formulas to the well-known phenomenon of the drop of the speed of sound in mixtures. For air bubbles in water, the authors obtain a perfect agreement with the recent results of coherent potential approximation obtained by M. Kafesaki, R.S. Penciu, and E.N. Economou [Phys. Rev. Lett. 84, 6050 (2000)] if the filling of air bubbles is far from close parking. When air spheres almost touch each other, the approximation gives 10 times lower speed of sound than the exact theory does. American Physical Society 2003-12-29 Article 4 p. Text doi: 10.1103/PhysRevLett.91.264302 http://digital.library.unt.edu/ark:/67531/metadc107771/ ark: ark:/67531/metadc107771 Physical Review Letters, 2003, College Park: American Physical Society English Public

info:ark/67531/metadc107802 2013-04-02T17:40:21Z partner:UNTCAS collection:UNTSW access_rights:public

Enthalpy of Formation of the Cyclohexadienyl Radical and the C-H Bond Enthalpy of 1,4-Cyclohexadiene: An Experimental and Computational Re-Evaluation Gao, Yide DeYonker, Nathan J. Garrett, E. Chauncey Wilson, Angela K. Cundari, Thomas R., 1964- Marshall, Paul cyclohexadienyl radical thermochemistry C-H bond This article discusses the enthalpy of formation of the cyclohexadienyl radical and the C-H bond enthalpy of 1,4-cyclohexadiene. Abstract: A quantitative understanding of the thermochemistry of cyclohexadiene is beneficial for diverse areas of chemistry. Given the interest in these two species, it is surprising that more detailed thermodynamic data concerning the homolytic C-H bond enthalpies of such entities have not been forthcoming. The authors thus undertook an experimental and computational evaluation of (a) the enthalpy of formation of cyclohexadienyl radical (C₆H₇), (b) the homolytic C-H bond enthalpy of 1,4-cyclohexadiene (C₆H₈), and (c) the enthalpy of the addition of a hydrogen atom to benzene. Using laser photolysis experiments coupled with highly accurate ab initio quantum mechanical techniques, a newly recommended enthalpy of formation for C₆H₇ is determined to be 208.0 ± 3.9 kJ mol⁻¹, leading to a homolytic bond dissociation enthalpy of 321.7 ± 2.9 kJ mol⁻¹, almost 9 kJ mol⁻¹ higher than previously determined enthalpies that used less certain experimental values for the C₆H₇ enthalpy of formation. American Chemical Society 2009-06-02 Article 9 p. Text doi: 10.1021/jp901314y http://digital.library.unt.edu/ark:/67531/metadc107802/ ark: ark:/67531/metadc107802 Journal of Physical Chemistry A, 2009, Washington DC: American Chemical Society, pp. 6955-6963 English Public

info:ark/67531/metadc107791 2013-04-11T15:43:33Z partner:UNTCAS collection:UNTSW access_rights:public

Flavin-Catalyzed Insertion of Oxygen into Rhenium-Methyl Bonds Pouy, Mark J. Milczek, Erika M. Figg, Travis M. Otten, Brooke M. Prince, Bruce M. Gunnoe, T. Brent Cundari, Thomas R., 1964- Groves, John T. flavins metal-carbon bonds molecules This article discusses flavin-catalyzed insertion of oxygen into rhenium-methyl bonds. Abstract: Flavins and related molecules catalyze organic Baeyer-Villiger reactions. Combined experimental and DFT studies indicate that these molecules also catalyze the insertion of oxygen into metal-carbon bonds through a Baeyer-Villiger-like transition state. American Chemical Society 2010-07-24 Article 4 p. Text doi: 10.1021/ja3054139 http://digital.library.unt.edu/ark:/67531/metadc107791/ ark: ark:/67531/metadc107791 Journal of the American Chemical Society, 2012, Washington DC: American Chemical Society, pp. 12920-12923 English Public

info:ark/67531/metadc107787 2013-04-17T10:38:32Z partner:UNTCAS collection:UNTSW access_rights:public

A Masked Two-Coordinate Cobalt (I) Complex That Activates C-F Bonds Dugan, Thomas R. Sun, Xianru Rybak-Akimova, Elena V. Olatunji-Ojo, Olayinka Cundari, Thomas R., 1964- Holland, Patrick L. cobalt complexes two-coordinate complexes C-F bonds fluorobenzene In this article, the authors report the isolation, characterization, and reactions of the unsaturated complex LᵗᴮᵘCo (Lᵗᴮᵘ = bulky β-diketiminate ligand). The unusual slipped kN,ɳ⁶-arene binding mode in LᵗᴮᵘCo interconverts rapidly and reversibly with the traditional k²N,N' ligation mode upon binding of Lewis bases, making it a "masked" two-coordinate complex. The mechanism of this isomerization is demonstrated using kinetic studies. LᵗᴮᵘCo is a stable yet reactive synthon for low-coordinate cobalt(I) complexes and is capable of cleaving the C-F bond in fluorobenzene. American Chemical Society 2011-07-19 Article 4 p. Text doi: 10.1021/ja2052914 http://digital.library.unt.edu/ark:/67531/metadc107787/ ark: ark:/67531/metadc107787 Journal of the American Chemical Society, 2011, Washington DC: American Chemical Society, pp. 12418-12421 English Public

info:ark/67531/metadc107788 2013-04-17T10:38:59Z partner:UNTCAS collection:UNTSW access_rights:public

Mechanistic Studies of Ethylene Hydrophenylation Catalyzed by Bipyridyl Pt(II) Complexes McKeown, Bradley A. Gonzalez, Hector Emanuel Friedfeld, Max R. Gunnoe, T. Brent Cundari, Thomas R., 1964- Sabat, Michal ethylene ethylbenzene hydrophenylation catalytic reactions This article discusses mechanistic studies of ethylene hydrophenylation catalyzed by bipyridyl Pt(II) complexes. Cationic platinum (II) complexes [(ᵗbpy)Pt(Ph)-(L)]⁺[ᵗbpy=4,4'-di-tert-butyl-2,2'-bipyridyl; L = THF, NC₅F₅, or NCMe] catalyze the hydrophenylation of ethylene to generate ethylbenzene and isomers of diethylbenzene. Using ethylene as the limiting reagent, an 89% yield of alkylarene products is achieved after 4 h at 120 ˚C. Catalyst efficiency for ethylene hydrophenylation is diminished only slightly under aerobic conditions. Mechanistic studies support a reaction pathway that involves ethylene coordination to Pt(II), insertion of ethylene into the Pt-phenyl bond, and subsequent metal-mediated benzene C-H activation. Studies of stoichiometric benzene (C₆H₆ or C₆D₆) C-H/C-D activation by [(ᵗbpy)Pt(Ph-dn)-(THF)]⁺ (n = 0 or 5) indicate a kʜ/kᴅ = 1.4(1), while comparative rates of ethylene hydrophenylation using C₆H₆ and C₆D₆ reveal kʜ/kᴅ = 1.8(4) for the overall catalytic reaction. DFT calculations suggest that the transition state for benzene C-H activation is the highest energy species along the catalytic cycle. In CD₂Cl₂, [(ᵗbpy)Pt(Ph)(THF)][BAr'₄] [Ar' = 3,5-bis(trifluoromethyl)phenyl] reacts with ethylene to generate [(ᵗbpy)Pt(CH₂CH₂Ph)(ɳ²-C₂H₄)][BAr'₄] with kobs = 1.05(4) x 10⁻³ s⁻¹ (23 ˚C, [C₂H₄] = 0.10(1) M). In the catalytic hydrophenylation of ethylene, substantial amounts of diethylbenzenes are produced, and experimental studies suggest that the selectivity for the monoalkylated arene is diminished due to a second aromatic C-H activation competing with ethylbenzene dissociation. American Chemical Society 2011-11-08 Article 22 p. Text doi: 10.1021/ja206064v http://digital.library.unt.edu/ark:/67531/metadc107788/ ark: ark:/67531/metadc107788 Journal of the American Chemical Society, 2011, Washington DC: American Chemical Society, pp. 19131-19152 English Public

info:ark/67531/metadc107799 2013-04-17T10:42:03Z partner:UNTCAS collection:UNTSW access_rights:public

Quantitative Computational Thermochemistry of Transition Metal Species DeYonker, Nathan J. Peterson, Kirk A. Steyl, Gideon Wilson, Angela K. Cundari, Thomas R., 1964- thermochemistry transition metals correlation consistent Composite Approach ccCA This article discusses quantitative computational thermochemistry of transition metal species. The correlation consistent Composite Approach (ccCA), which has been shown to achieve chemical accuracy (±1 kcal mol⁻¹) for a large benchmark set of main group and s-block metal compounds, is used to compute enthalpies of formation for a set of 17 3d transition metal species. The training set includes a variety of metals, ligands, and bonding types. Using the correlation consistent basis sets for the 3d transition metals, the authors find that gas-phase enthalpies of formation can be efficiently calculated for inorganic and organometallic molecules with ccCA. However, until the reliability of gas-phase transition metal thermochemistry is improved, both experimentally and theoretically, a large experimental training set where uncertainties are near ±1 kcal mol⁻¹ (akin to commonly used main group benchmarking sets) remains an ambitious goal. For now, an average deviation of ±3 kcal mol⁻¹ appears to be the initial goal of "chemical accuracy" for ab initio transition metal model chemistries. The ccCA is also compared to a more robust but relatively expensive composite approach primarily utilizing large basis set coupled cluster computations. For a smaller training set of eight molecules, ccCA has a mean absolute deviation (MAD) of 3.4 kcal mol⁻¹ versus the large basis set coupled-cluster-based model chemistry, which has a MAD of 3.1 kcal mol⁻¹. However, the agreement for transition metal complexes is more system dependent than observed in previous benchmark studies of composite methods and main group compounds. American Chemical Society 2007-05-15 Article 9 p. Text doi: 10.1021/jp0715023 http://digital.library.unt.edu/ark:/67531/metadc107799/ ark: ark:/67531/metadc107799 Journal of Physical Chemistry A, 2007, Washington DC: American Chemical Society, pp. 11269-11277 English Public

info:ark/67531/metadc107805 2013-04-17T10:39:54Z partner:UNTCAS collection:UNTSW access_rights:public

Modeling Nonlinear Optical Properties of Transition Metal Complexes. Basis Set, Effective Core Potential, and Geometry Effects Cundari, Thomas R., 1964- Kurtz, Henry A. Zhou, Tie transition metal complexes nonlinear optical electrons ligands This article discusses modeling nonlinear optical properties of transition metal complexes. Nonlinear optical (NLO) properties of transition metal complexes are studied using quantum chemical calculations. By comparison with all electron calculations, effective core potentials have been shown to be competent for the calculation of NLO properties as long as the valence basis sets are comparable. While overall the basis set effects are important for calculation of NLO properties, they are found to be less important for the central transition metal than for the surrounding ligands. Augmenting the basis set of main group elements with diffuse, s, p, and d functions in a proper way could provide the best compromise between speed and accuracy of the computation. Interesting trends are found in the calculation of NLO properties of [MO₄]q⁻. Both polarizability (α) and second hyperpolarizability (y) decrease toward the right across the transition series. The second series [MO₄]q⁻ have the largest α among the three metalates in a triad. For group IVB and VB complexes with larger charges (-4 and -3, respectively), the second series [MO₄]q⁻ have the largest y, while for groups VIB, VIIB, and VIII, with less anionic metalates (-2, -1, and 0, respectively), the third series metalates have the largest y. The relative difference in both α and y values among the three series in the same group is much smaller than between different groups. Overall, variations in the calculated values of NLO properties correlate with M-O bond lengths and hence the size of the metalate ion. American Chemical Society 1998-04-04 Article 5 p. Text doi: 10.1021/jp980438+ http://digital.library.unt.edu/ark:/67531/metadc107805/ ark: ark:/67531/metadc107805 Journal of Physical Chemistry A, 1998, Washington DC: American Chemical Society, pp. 2962-2966 English Public

info:ark/67531/metadc107803 2013-04-17T10:55:38Z partner:UNTCAS collection:UNTSW access_rights:public

Theoretical Estimation of Vibrational Frequencies Involving Transition Metal Compounds Cundari, Thomas R., 1964- Raby, Philip D. transition metal compounds effective core potentials vibrational frequencies This article discusses the theoretical estimation of vibrational frequencies involving transition metal compounds. The reliability of effective core potentials (ECPs) for estimating vibrational frequencies of transition metal (TM) complexes is assessed in relation to all-electron methods for main group compounds. Complexes with a multiple bond between a transition metal and chalcogen (O,S, or Se), chalcogenides, are investigated using the Stevens ECP/valence basis set scheme. Statistical treatment of the data indicates that ECPs, in addition to reliably modeling electronic structure, can be successful in estimating vibrational frequencies for TM complexes. As expected, theoretical prediction of vibrational data is not as accurate as the prediction of metric data for chalcogenides. However, agreement with experiment is still very good at the Hartree-Fock level of theory and is in even better accord upon the use of simple correlations to model well-known computational deficiencies (e.g., the neglect of anharmonic effects). Analysis of the data show interesting differences in predictive ability for first row transition metals versus second- and third-row analogues and oxo complexes versus their congeners with heavier chalcogens. American Chemical Society 1997-08-07 Article 6 p. Text doi: 10.1021/jp963952t http://digital.library.unt.edu/ark:/67531/metadc107803/ ark: ark:/67531/metadc107803 Journal of Chemical Theory and Computation, 1997, Washington DC: American Chemical Society, pp. 5783-5788 English Public

info:ark/67531/metadc107786 2013-04-17T10:53:06Z partner:UNTCAS collection:UNTSW access_rights:public

Selectivity and Mechanism of Hydrogen Atom Transfer by an Isolable Imidoiron (III) Complex Cowley, Ryan E. Eckert, Nathan A. Vaddadi, Sridhar Figg, Travis M. Cundari, Thomas R., 1964- Holland, Patrick L. hydrogen atom transfers iron-imido complexes kinetic isotopes ligands This article discusses the selectivity and mechanism of hydrogen atom transfer by an isolable imidoiron (III) complex. In the literature, iron-oxo complexes have been isolated and their hydrogen atom transfer (HAT) reactions have been studied in detail. Iron-imido complexes have been isolated more recently, and the community needs experimental evaluations of the mechanism of HAT from late-metal imido species. The authors report a mechanistic study of HAT by an isolable iron (III) imido complex, LᴹᵉFeNAd (Lᴹᵉ = bulky β-diketiminate ligand, 2,4-bis(2,6-diisopropylphenylimido)pentyl; Ad = 1-adamantyl). HAT is preceded by binding of tert-butylpyridine (ᵗBupy) to form a reactive four-coordinate intermediate LᴹᵉFe(NAd)(ᵗBupy), as shown by equilibrium and kinetic studies. In the HAT step, very large substrate H/D kinetic isotope effects around 100 are consistent with C-H bond cleavage. The elementary HAT rate constant is increased by electron-donating groups on the pyridine additive, and by a more polar medium. When combined with the faster rate of HAT from indene versus cyclohexadiene, this trend is consistent with H⁺ transfer character in the HAT transition state. The increase in HAT rate in the presence of ᵗBupy may be explained by a combination of electronic (weaker Fe=N π-bonding) and thermodynamic (more exothermic HAT) effects. Most importantly, HAT by these imido complexes has a strong dependence on the size of the hydrocarbon substrate. This selectivity comes from steric hindrance by the spectator ligands, a strategy that has promise for controlling the regioselectivity of these C-H bond activation reactions. American Chemical Society 2011-05-12 Article 16 p. Text doi: 10.1021/ja2005303 http://digital.library.unt.edu/ark:/67531/metadc107786/ ark: ark:/67531/metadc107786 Journal of the American Chemical Society, 2011, Washington DC: American Chemical Society, pp. 9796-9811 English Public

info:ark/67531/metadc107804 2013-04-17T10:48:07Z partner:UNTCAS collection:UNTSW access_rights:public

Molecular Modeling of Vanadium-Oxo Complexes. A Comparison of Quantum and Classical Methods Cundari, Thomas R., 1964- Saunders, Leah Sisterhen, Laura L. molecular modeling vanadium-oxos transition metals quantum mechanics This article discusses molecular modeling of vanadium-oxo complexes. A force field for vanadium-oxos was developed and tested with a variety of complexes with coordination numbers of 5 or 6 and formal oxidations states of +4 or +5 on the metal. Similarly, a semiempirical quantum mechanical method for transition metals was extended to vanadium. In this research soft and hard ligands were studied, as were ligands coordinated through single, multiple, and dative bonds. Despite the diversity of vanadium coordination chemistry, generally good modeling is achieved in a fraction of the time with less computational resources using molecular mechanics and semiempirical quantum mechanics. The L₄V⁴⁺O and L₅V⁵⁺O groups were emphasized given their prevalence and importance. In general, the predictive ability was superior for the former structural motif. The combination of molecular mechanics and semiempirical quantum calculations provide an effective and efficient tool for analysis of the steric and electronic energy differences between isomers. American Chemical Society 1998-01-22 Article 8 p. Text doi: 10.1021/jp972827u http://digital.library.unt.edu/ark:/67531/metadc107804/ ark: ark:/67531/metadc107804 Journal of Physical Chemistry A, 1998, Washington DC: American Chemical Society, pp. 997-1004 English Public

info:ark/67531/metadc107800 2013-04-17T10:47:15Z partner:UNTCAS collection:UNTSW access_rights:public

Modeling the Deposition of Metal Atoms on a p-Type Organometallic Conductor: Implications for Stability and Electron Transfer Chilukuri, Bhaskar Cundari, Thomas R., 1964- organometallic semiconductors metal atoms electron transfers This article discusses modeling the deposition of metal atoms on a p-Type organometallic conductor. A computational study of the interaction of metal atoms (M') with cyclo-[Au(μ-Pz)]₃ trimer (T) (Pz = Pyrazo-late ligand), a p-type organometallic semiconductor is reported in this article. The metal atoms chosen for the study are both high and low work function electrode metals (M' = Al, Au, Cu, La, Ni, Pd, Pt, Ru, Ni) used in electronic devices. Metal (M'м) and ligand (M'ʟ) sites of the gold trimer are investigated as the possible sites of deposition for the metal atoms. Examination of metal binding, geometric, and electronic properties indicated that low work function metals La and Ti favor the ligand coordination (M'ʟ); Al, Au, Cu, Ni, Pt, and Ru favor coordination to the metal (i.e., gold) site of the trimer. Pd has equal stability at both the M'ʟ and the M'м sites of the trimer. Changes in geometry of the trimer upon deposition of the metal atom are negligible for M'м-T complexes but more change is seen for M'ʟ-T complexes. All metal atoms except Pd exhibited good orbital hybridization with the gold trimer in M'-T complexes. These combinations of observations suggest that, for these metal-based, p-type conductors will form stable interfaces with good electron transfer with typical source/drain electrode metals. American Chemical Society 2011-03-10 Article 7 p. Text doi: 10.1021/jp111337r http://digital.library.unt.edu/ark:/67531/metadc107800/ ark: ark:/67531/metadc107800 Journal of Physical Chemistry C, 2011, Washington DC: American Chemical Society, pp. 5997-6003 English Public

info:ark/67531/metadc107769 2013-04-17T10:47:42Z partner:UNTCAS collection:UNTSW access_rights:public

Modified embedded atom method study of the mechanical properties of carbon nanotube reinforced nickel composites Uddin, Jamal Baskes, Michael I. Srinivasan, S.G. Cundari, Thomas R., 1964- Wilson, Angela K. single-walled carbon nanotubes SWCNT multiwalled carbon nanotubes MWCNT carbon atoms nickel atoms In this article, the authors report an atomistic simulation study of the behavior of nanocomposite materials that are formed by incorporating single-walled carbon nanotubes (SWCNTs), with three different diameters, and a multiwalled carbon nanotube (MWCNT) into a single-crystal nickel matrix. The interactions between carbon and nickel atoms are described by a modified embedded atom method potential. Mechanical properties of these nanocomposite materials are predicted by atomistic calculations and compared with that of fcc nickel and pristine CNTs. The authors' simulations predict that all Ni/CNT composites studied in this work are mechanically stable. Their elastic properties depend on the volume fraction and diameter of embedded CNTs. The single-crystal Young's modulus (E₁₁) of Ni/SWCNT composites exhibit a large increase in the direction of CNTs alignment compared to that of a single-crystal nickel. However, a moderate but gradual decrease is seen for E₂₂ and E₃₃ in the transverse directions with increase in CNT diameters. As a consequence, Ni/SWCNTs show a gradual decrease for the polycrystalline Young's, bulk and shear moduli with the increasing CNT diameters and volume fractions. These reductions, although moderate, suggest that enhancement of mechanical properties for polycrystalline Ni/SWCNT nanocomposites are not achievable at any CNT volume fraction. The Ni/MWCNT composite with high CNT volume fraction shows the highest increase in E₁₁. Unlike the E₂₂ and E₃₃ for Ni/SWCNTs, there is a significant increase in the E₂₂ and the E₃₃ for Ni/MWCNT. As a result, polycrystalline Ni/MWCNT composites show slight increase in the elastic properties. This suggests that nickel nanocomposites with enhanced mechanical properties can be fabricated using large volume fractions of larger diameter MWCNTs. Depending on type, alignment and volume fraction, Ni/CNT composites show varying degrees of elastic anisotropy and Poisson's ration compared to pure Ni. Simulation predicts strong adhesion at the Ni/CNT interface and a significant interfacial stress transfer between CNT and Ni matrix. American Physical Society 2010-03-11 Article 12 p. Text doi: 10.1103/PhysRevB.81.104103 http://digital.library.unt.edu/ark:/67531/metadc107769/ ark: ark:/67531/metadc107769 Physical Review B, 2010, College Park: American Physical Society English Public

info:ark/67531/metadc107784 2013-04-17T10:51:12Z partner:UNTCAS collection:UNTSW access_rights:public

[Review] Computational Inorganic and Bioinorganic Chemistry Cundari, Thomas R., 1964- inorganic chemistry bioinorganic chemistry density functional theory This book review discusses 'Computational Inorganic and Bioinorganic Chemistry', edited by Edward I. Solomon from Stanford University, Robert A. Scott from the University of Georgia Athens, and R. Bruce King from the University of Georgia Athens. American Chemical Society 2010-04-28 Review 1 p. Text doi: 10.1021/ja9103254n http://digital.library.unt.edu/ark:/67531/metadc107784/ ark: ark:/67531/metadc107784 Journal of the American Chemical Society, 2010, Washington DC: American Chemical Society, pp. 7557-7557 English Public

info:ark/67531/metadc107795 2013-04-17T10:48:57Z partner:UNTCAS collection:UNTSW access_rights:public

Net Hydrogenation of Pt-NHPh Bond Is Catalyzed by Elemental Pt Webb, Joanna R. Pierpont, Aaron W. Munro-Leighton, Colleen Gunnoe, T. Brent Cundari, Thomas R., 1964- Boyle, Paul D. net hydrogenation bond transformations transition metal systems anionic ligands This article discusses the net hydrogenation of Pt-NHPh bond catalyzed by elemental Pt. The addition of H₂ across M-NHR or M-OR moieties is a central reaction for several synthetic transformations. For example, Stryker's reagent, [(Ph₃P)CuH]₆, a catalyst for conjugate addition reactions, is generated by hydrogenolysis of a Cu-OᵗBu bond. Additionally, net H₂ addition across M-O₂CH bonds completes catalytic conversion of CO₂ and H₂ to formic acid, H₂ addition across Pt-OH bonds has been proposed in a cycle for olefin epoxidation, and H₂ addition across M-NHR bonds has been implicated in asymmetric hydrogenations. Despite their importance, reports of well-defined reactions with late(r) transition metal systems are rare and mechanistic studies are limited. Recently, C-H activation of hydrocarbons via net 1,2-addition of C-H bonds across metal-heteroatom bonds using late transition metals (with ≥ 6 d-electrons) bearing formally anionic ligands (e.g., -NHR or -OR) has been reported. Despite interest in these C-H and H-H bond transformations, questions regarding the mechanism remain. American Chemical Society 2010-03-11 Article 2 p. Text doi: 10.1021/ja9102309 http://digital.library.unt.edu/ark:/67531/metadc107795/ ark: ark:/67531/metadc107795 Journal of the American Chemical Society, 2010, Washington DC: American Chemical Society, pp. 4520-4521 English Public

info:ark/67531/metadc107792 2013-04-17T10:44:58Z partner:UNTCAS collection:UNTSW access_rights:public

Reductive Elimination of Alkylamines from Low-Valent, Alkylpalladium(II) Amido Complexes Hanley, Patrick S. Marquard, Seth L. Cundari, Thomas R., 1964- Hartwig, John F. alkylamines amido complexes ligands N-heterocyclic carbene NHC This article discusses reductive elimination of alkylamines from low-valent, alkylpalladium(II) amido complexes. A series of three-coordinate norbornylpalladium amido complexes ligated by bulky N-heterocyclic carbene (NHC) ligands were prepared that undergo reductive eliminations to form the alkyl-nitrogen bond of alkylamine products. The rates of reductive elimination reveal that complexes containing more-electron-donating amido groups react faster than those with less-electron-donating amido groups, and complexes containing more-sterically bulky amido groups undergo reductive elimination more slowly than complexes containing less-sterically bulky amido groups. Complexes ligated by more-electron-donating ancillary NHC ligands undergo reductive elimination faster than complexes ligated by less-electron-donating NHC ligands. In contrast to the reductive elimination of benzylamines from bisphosphine-ligated palladium amides, these reactions occur with retention of configuration at the alkyl group, indicating that these reductive eliminations proceed by a concerted pathway. The experimentally determined free energy barrier of 26 kcal/mol is close to the computed free energy barrier of 23.9 kcal/mol (363 K) for a concerted reductive elimination from the isolated, three-coordinate NHC-ligated palladium anilido complex. American Chemical Society 2012-08-30 Article 4 p. Text doi: 10.1021/ja307558x http://digital.library.unt.edu/ark:/67531/metadc107792/ ark: ark:/67531/metadc107792 Journal of the American Chemical Society, 2012, Washington DC: American Chemical Society, pp. 15281-15284 English Public

info:ark/67531/metadc107785 2013-04-17T10:45:25Z partner:UNTCAS collection:UNTSW access_rights:public

A Two-Coordinate Nickel Imido Complex That Effects C-H Amination Laskowski, Carl A. Miller, Alexander J.M. Hillhouse, Gregory L. Cundari, Thomas R., 1964- nickel imido low-coordinate density functional theory This article discusses a two-coordinate nickel imido complex that effects C-H amination. An exceptionally low coordinate nickel imido complex, (IPr*)Ni=N(dmp) (2) (dmp=2,6-dimesitylphenyl), has been prepared by the elimination of N₂ from a bulky aryl azide in its reaction with (IPr*)Ni(ɳ⁶-C₇H₈) (1). The solid-state structure of 2 features two-coordinate nickel with a linear C-Ni-N core and a short Ni-N distance, both indicative of multiple-bond character. Computational studies using density functional theory showed a Ni=N bond dominated by Ni(dπ)-N(pπ) interactions, resulting in two nearly degenerate singly occupied molecular orbitals (SOMOs) that are Ni-N π* in character. Reaction of 2 with CO resulted in nitrene-group transfer to form (dmp)NCO and (IPr*)Ni(CO)₃ (3). Net C-H insertion was observed in the reaction of 2 with ethene, forming the vinylamine (dmp)NH(CH=CH₂) (5) via an azanickelacyclobutane intermediate, (IPr*)Ni{N,C:k²-N(dmp)CH₂CH₂} (4). American Chemical Society 2010-12-22 Article 3 p. Text doi: 10.1021/ja1101213 http://digital.library.unt.edu/ark:/67531/metadc107785/ ark: ark:/67531/metadc107785 Journal of the American Chemical Society, 2010, Washington DC: American Chemical Society, pp. 771-773 English Public

info:ark/67531/metadc107768 2013-04-25T16:42:26Z partner:UNTCAS collection:UNTSW access_rights:public

Homogenization of Magnetodielectric Photonic Crystals Krokhin, Arkadii A. Reyes, E. magnetodielectric photonic crystals magnetic semiconductors optical properties This article discusses homogenization of magnetodielectric photonic crystals. Abstract: We calculate the low-frequency index of refraction of a medium which is homogeneous along axis z and possesses a periodic dependence of the permittivity ɛ(r) and permeability μ(r) in the x-y plane (2D magnetodielectric photonic crystal). Exact analytical formulas for the effective index of refraction for two eigenmodes with vector E or H polarized along axis z are obtained. We show that, unlike nonmagnetic photonic crystals where the E mode is ordinary and the H mode is extraordinary, now both modes exhibit extraordinary behavior. Because of this distinction, the magnetodielectric photonic crystals exhibit optical properties that do not exist for natural crystals. We also discuss the limiting case of perfectly conducting cylinders and clarify the so-called problem of noncommuting limits, ω → 0 and ɛ → ∞. American Physical Society 2004-07-09 Article 4 p. Text doi: 10.1103/PhysRevLett.93.023904 http://digital.library.unt.edu/ark:/67531/metadc107768/ ark: ark:/67531/metadc107768 Physical Review Letters, 2004, College Park: American Physical Society English Public

info:ark/67531/metadc107794 2013-04-25T13:37:28Z partner:UNTCAS collection:UNTSW access_rights:public

Group-Transfer Reactions of Nickel-Carbene and -Nitrene Complexes with Organoazides and Nitrous Oxide that Form New C=N, C=O, and N=N Bonds Harrold, Nicole D. Waterman, Rory Hillhouse, Gregory L. Cundari, Thomas R., 1964- group-transfer reactions nitrous oxide nitrene complexes organoazides This article discusses group-transfer reactions of nickel-carbene and -nitrene complexes with organoazides and nitrous oxide that form new C=N, C=O, and N=N bonds. Abstract: 1-Adamantyl- and mesitylazide react with (dtbpe)Ni=CPh2 (1; dtbpe = 1,2-bis(di-tert-butylphosphino)ethane) at ambient temperature to give the ketimines RN=CPh2 (2a, R = Mes; 2b, R = Ad) in high yield. Kinetic studies for the reaction of 1 with N3Ad yield activation parameters of ∆H‡ = +8(±1) kcal/mol and ∆S‡ = -44(±3) cal/(mol•K). Treatment of 1 with N2O at low temperature results in clean conversion to the benzophenone complex (dtbpe)Ni=NR (4a, R = Mes; 4b, R = Ad) react with N3Mes and N3Ad at ambient temperature to give the diazenes RN=NR (6a, R = Mes; 6b, R = Ad) in good yield. B3LYP/6-311+G(d) calculations support a mechanism for all three reactions that features 1,3-dipolar cycloaddition to give five-membered ring (Huisgen) intermediates, followed by N2 elimination to give the products. Calculated activation parameters for the reaction of (dhpe)Ni=CH2 (dhpe = 1,2-bis(dihydridophosphino)ethane) with N3Me compare well with the experimental values. American Chemical Society 2009-08-19 Article 2 p. Text doi: 10.1021/ja904370h http://digital.library.unt.edu/ark:/67531/metadc107794/ ark: ark:/67531/metadc107794 Journal of the American Chemical Society, 2009, Washington DC: American Chemical Society, pp. 12872-12873 English Public

info:ark/67531/metadc107774 2013-04-25T15:13:36Z partner:UNTCAS collection:UNTSW access_rights:public

High-Valent Transition-Metal Alkylidene Complexes: Effect of Ligand and Substituent Modification Cundari, Thomas R., 1964- Gordon, Mark S. transition metals alkylidene complexes ligands substituents This article discusses high-valent transition-metal alkylidene complexes. Abstract: An ab initio investigation into the effects of ligand and substituent modification on the metal-carbon double bond is reported. Prototypical group IVB (Ti, Zr, Hf) and Group VB (Nb, Ta) alkylidenes are chosen for this study. The MC/LMO/CI (multiconfiguration/localized molecular orbital/configuration interaction) procedure is used to examine the electronic structures of these complexes in terms of the prime resonance contributors to the ground-state wave function. The main conclusion drawn from this work is that the intrinsic nature of the metal-carbon double bond can typically be changed only within certain limits by modification of the electronegativity of the ligands (L) and substituents (Z). In other words, the Ta=C bond in H₃TaCCl₂ and Cl₃TaCH₂ and presumably in experimentally characterized analogues with larger ligands and substituents, e.g., Cp and neopentyl. Significant changes in the electronic structure are effected in three ways: The first way is through the introduction of a highly electropositive substituent, e.g., Li. This makes the metal-carbon bond closer to a triple bond for the Ta-alkylidenes. The second way to change the electronic structure of the alkylidenes significantly is to change the central metal atom. The heaviest members of groups IVB (Hf) and VB (Ta) are the most nucleophilic at the α-carbon. The third way in which the metal-carbon bond could be significantly altered is through the use of π-donor substituents. The introduction of π-donor substituents on Cα increases the electrophilicity of the α-carbon. American Chemical Society 1992 Article 10 p. Text doi: 10.1021/ja00028a022 http://digital.library.unt.edu/ark:/67531/metadc107774/ ark: ark:/67531/metadc107774 Journal of the American Chemical Society, 1992, Washington DC: American Chemical Society, pp. 539-548 English Public

info:ark/67531/metadc107772 2013-05-13T13:39:12Z partner:UNTCAS collection:UNTSW access_rights:public

Inter- and Intramolecular Experimental and Calculated Equilibrium Isotope Effects for (silox)₂(ᵗBu₃SiND)TiR + RH (silox = ᵗBu₃SiO): Inferred Kinetic Isotope Effects for RH/D Addition to Transient (silox)₂Ti=NSiᵗBu₃ Slaughter, LeGrande M. Wolczanski, Peter T. Klinckman, Thomas R. Cundari, Thomas R., 1964- isotope effects kinetic gas-phase partition functions This article discusses inter- and intramolecular experimental and calculated equilibrium isotope effects. Abstract: Intermolecular equilibrium isotope effects (EIEs) were measured (26.5 ˚C) and calculated for (silox)₂₋ (ᵗBu₃SiND)TiRᴅ (1-ND-Rᴅ) + RʜH ⇆ (silox)₂(ᵗBu₃SiNH)TiRʜH/RᴅD = CH₄/CD₄, 2.00(6), calcd 1.88; C₂H₆/C₂D₆, 2.22(8), 1.93; ᶜC₃H₆/C₃D₆, 1.71(4), 1.48; C₂H₄/C₂D₄, 1.41(11), 1.34; C₆H₆/C₆D₆, 1.22(7), 1.26; C₇H₈/C₇D₈ (50.0 ˚C), 1.59(6), 1.55. Related intramolecular EIEs for (silox)₂(ᵗBu₃SiND)- TiR' (1-ND-R') ⇆ (silox)₂(ᵗBu₃SiNH)TiR (1-R) are provided: RH = R'D = CH₃D, 3.16(25), calcd 2.60; CH₂D₂, 1.13(8), 0.911; CHD₃, 0.389(20), 0.303; CH₃CD₃, 1.53(3), 1.44; 1, 1-ᶜC₃H₄D₂, 2.58(6), 2.53; trans-HDC=CHD, 1.00(2), 1.00; 1,3,5-C₆H₃D₃, 1.273(4), 1.25; PhCH₂D (50.0 ˚C), 2.06(2), 1.98. Calculations of pertinent model complexes (e.g., (HO)₂(H₂N)TiR (1'R)) generated the vibrational frequencies necessary to interpret the EIEs in terms of a statistical mechanics description utilizing gas-phase partition functions; EIE = SYM x MMI x EXC x EXP[-(∆∆ZPE/kʙT)]. The large MMI term in the intermolecular cases-a consequence of using perprotio vs perdeuterio small molecule substrates-is attenuated by EXC and EXP[-(∆∆ZPE/kʙT)] contributions derived from low-energy core vibrations. The EIEs are differentiated on the basis of the EXP [-(∆∆ZPE/kʙT)] term, with CH-based bending vibrations playing the major role. Substrate bending vibrations that are absent in intramolecular cases are primarily responsible for the greater intermolecular values. Using measured (or calculated) EIEs and kinetic isotope effects for 1,2-RH-elimination (KIEelim) from 1-R, KIEaddn values for 1,2-RH-addition to putative intermediate (silox)₂Ti=NSiᵗBu₃ (2) were inferred via EIE = KIEaddn/KIEelim. Extraordinary intermolecular KIEaddn values ranging from ~ 30(CH₄/CD₄, C₂H₆/C₂D₆) to ~ 9 (C₆H₆/C₆D₆) are consistent with previous mechanistic accounts and may be conventionally rationalized. American Chemical Society 2000-08-23 Article 23 p. Text doi: 10.1021/ja000112q http://digital.library.unt.edu/ark:/67531/metadc107772/ ark: ark:/67531/metadc107772 Journal of the American Chemical Society, 2000, Washington DC: American Chemical Society, pp. 7953-7975 English Public

info:ark/67531/metadc109722 2013-04-17T10:40:24Z partner:UNTCAS collection:UNTSW access_rights:public

Performance of Density Functional Theory for 3d Transition Metal-Containing Complexes: Utilization of the Correlation Consistent Basis Sets Tekarli, Sammer M. Drummond, Michael L. Williams, T. Gavin Cundari, Thomas R., 1964- Wilson, Angela K. density functional theory transition metals correlation consistent basis sets This article discusses the performance of density functional theory for 3d transition metal-containing complexes. The performance of 44 density functionals used in conjunction with the correlation consistent basis sets (ccpVnZ where n = T and Q) has been assessed for the gas-phase enthalpies of formation at 298.15 K of 3d transition metal (TM) containing systems. Nineteen molecules were examined: ScS, VO, VO₂, Cr(CO)₆, MnS, MnCl₂, Mn(CO)₅Cl, FeCl₃, Fe(CO)₅, CoH(CO)₄, NiCl₂, Ni(CO)₄, CuH, CuF, CuCl, ZnH, ZnO, ZnCl, and Zn(CH₃)₂. Of the functionals examined, the functionals that resulted in the smallest mean absolute deviation (MAD, in parentheses, kcal molˉ¹) from experiment were B97-1(6.9), PBE1KCIS (8.1), TPSS1KCIS (9.6), B97-2(9.7), and B98(10.7). All five of these functionals include some degree of Hartree-Fock (HF) exchange. The impact of increasing the basis set from cc-pVTZ to cc-pVQZ was found to be slight for the generalized gradient approximation (GGA) and meta-GGA (MGGA) functionals studied, indicating basis set saturation at the triple-ζ level. By contrast, for most of the generalized gradient exchange (GGE), hybrid GGA (HGGA), and hybrid meta-GGA (HMGGA) functionals considered, improvements in the average MAD of 2-3 kcal molˉ¹ were seen upon progressing to a quadruple-ζ level basis set. Overall, it was found that the functionals that include Hartree-Fock exchange performed best overall, but those with greater than 40% HF exchange exhibit significantly poor performance for the prediction of enthalpies of formation for 3d TM complexes. Carbonyl-containing complexes, a mainstay in organometallic TM chemistry, are demonstrated to be exceedingly difficult to describe accurately with all but 2 of the 44 functionals considered. The most accurate functional, for both CO-containing and CO-free compounds, is B97-1/cc-pVQZ, which is shown to be capable of yielding results within 1 kcal molˉ¹ of high-level ab initio composite methodologies. American Chemical Society 2009-07-02 Article 8 p. Text doi: 10.1021/jp811503v http://digital.library.unt.edu/ark:/67531/metadc109722/ ark: ark:/67531/metadc109722 Journal of Physical Chemistry A, 2009, Washington DC: American Chemical Society, pp. 8607-8614 English Public

info:ark/67531/metadc111247 2012-12-14T13:19:22Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Rutherford and Radon Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. scientific research chemical elements science technology chemistry radon Rutherford, Ernest, 1871-1937. Dorn, E. (Ernst), 1848-1916. radiation radioactivity Soddy, Frederick, 1877-1956. Article describing the history of the discovery of radon. Tourist information is included for areas significant to radon and its discoverers. Alpha Chi Sigma 2010-22 Article 22-26 p. : col. ill. ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111247/ ark: ark:/67531/metadc111247 The Hexagon, Volume 101, Number 2, Summer 2010, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 101, Number 2, Summer 2010, ark:/67531/metadc111255/ Canada - Québec Province - Île de Montréal - Montréal 1848-2010

info:ark/67531/metadc111246 2012-12-14T13:19:46Z partner:UNTCAS collection:UNTSW access_rights:public

Foucault's Pendulum Marshall, James L., 1940- Marshall, Virginia R. scientific research chemical elements science technology chemistry Panthéon (Paris, France) Foucault, Léon, 1819-1868. pendulums Front cover of the Summer 2010 issue of The Hexagon featuring Foucault's pendulum in the Panthéon of Paris, France. A large weight hangs from the ceiling over a circular table with degrees written onto its surface. A round fence with hash marks and numbers surrounds the display. Columns and a raised statue of men are visible in the background. The inside cover features a table of contents, staff list, an editorial, and a description of the front cover. Alpha Chi Sigma 2010-22 Article 17-18 p. : col. ill. ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111246/ ark: ark:/67531/metadc111246 The Hexagon, Volume 101, Number 2, Summer 2010, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 101, Number 2, Summer 2010, ark:/67531/metadc111255/ France - Île-de-France Region - Département de Ville de Paris - Paris 1851-2010

info:ark/67531/metadc111245 2012-12-14T13:18:12Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Madam Curie Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. scientific research chemical elements science technology chemistry radium polonium Curie, Marie, 1867-1934. Curie, Pierre, 1859-1906. Article describing the career of Marie Curie and the discovery of polonium and radium. Tourist information regarding the areas where the Curies were most active are included. Alpha Chi Sigma 2010-21 Article 6-11 p. : col. ill. ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111245/ ark: ark:/67531/metadc111245 The Hexagon, Volume 101, Number 1, Spring 2010, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 101, Number 1, Spring 2010, ark:/67531/metadc111254/ France - Île-de-France Region - Département de Ville de Paris - Paris 1859-2010

info:ark/67531/metadc111237 2012-12-14T13:12:17Z partner:UNTCAS collection:UNTSW access_rights:public

The Statue of Copernicus Marshall, James L., 1940- Marshall, Virginia R. scientific research chemical elements science technology chemistry Copernicus, Nicolaus, 1473-1543. Front cover of the Summer 2009 issue of The Hexagon, featuring a statue of Copernicus sitting on a block, wearing a flowing robe, and holding a compass up to a heliocentric model. The next page contains a table of contents, a staff list, and an editorial regarding the twentieth anniversary of the events at Tiananmen Square. Alpha Chi Sigma 2009-22 Article 17-18 p. : col. ill. ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111237/ ark: ark:/67531/metadc111237 The Hexagon, Volume 100, Number 2, Summer 2009, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 100, Number 2, Summer 2009, ark:/67531/metadc111242/ 2009 China - Beijing Shi Municipality - Beijing

info:ark/67531/metadc111238 2012-12-14T13:12:42Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Ruthenium Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. scientific research chemical elements science technology chemistry platinum ruthenium Sobolevsky, Peter Grigorievich Osann, Gottfried Wilhelm, 1797-1866. Klaus, Karl Karlovich, 1796-1864. Article describing the discovery of platinum in Russia and the history of ruthenium. Tourist information regarding sites pertinent to this history are included. Alpha Chi Sigma 2009-22 Article 20-23 p. : col. ill. ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111238/ ark: ark:/67531/metadc111238 The Hexagon, Volume 100, Number 2, Summer 2009, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 100, Number 2, Summer 2009, ark:/67531/metadc111242/ Russia - Siberia General Region Russia - Rossiya - Sverdlovskaya Oblast' - Nizhniy Tagil Russia - Respublika Tatarstan - Kazan' 1580-2009

info:ark/67531/metadc111240 2012-12-14T13:13:48Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Courtois and Iodine Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. scientific research chemical elements science technology chemistry iodine saltpeter Courtois, Bernard, 1777-1838. nitraries Ecole polytechnique (France) Davy, Humphry, Sir, 1778-1829. Gay-Lussac, Joseph Louis, 1778-1850. Boyle, Robert, 1627-1691. Article describing the history of iodine, including its discovery by Bernard Courtois while during the production of saltpeter. Tourist information regarding pertinent locations is included. Alpha Chi Sigma 2009-24 Article 72-75 p. : col. ill. ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111240/ ark: ark:/67531/metadc111240 The Hexagon, Volume 100, Number 4, Winter 2009, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 100, Number 4, Winter 2009, ark:/67531/metadc111243/ China Europe France - Île-de-France Region - Département de Ville de Paris - Paris England - Greater London Metropolitan Area - London France - Bergundy Region - Côte-d'Or Department - Dijon 600~-2009

info:ark/67531/metadc111230 2012-12-14T13:09:44Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Jáchymov (Joachimsthal), Czech Republic Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. scientific research chemical elements science technology chemistry tourism radon pitchblende uranium Article describing Jáchymov, Czech Republic, and its relation to radon. Tourist information is included for pertinent areas. Alpha Chi Sigma 2008-24 Article [5] p. : col. ill. ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111230/ ark: ark:/67531/metadc111230 The Hexagon, Volume 99, Number 4, Winter 2008, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 99, Number 4, Winter 2008, ark:/67531/metadc111234/ Czech Republic - Western Bohemia Region - Jáchymov 1512-2008

info:ark/67531/metadc111176 2012-12-14T12:35:08Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Titanium, Manaccan, Cornwall, England Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. Marshall, James L., 1940- Marshall, Virginia R. scientific research chemical elements science technology travel churches Manaccan Church Gregor, William, 1761-1817. Titanium Klaproth, M. H. (Martin Heinrich), 1743-1817. chemistry Article wherein James and Virginia Marshall visit Manaccan, England, to explore the site where titanium was first discovered. The area is described, as well as the man who discovered titanium, Reverend William Gregor. Alpha Chi Sigma 2001-23 Article 4-5 p. : ill. (some col.) ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111176/ ark: ark:/67531/metadc111176 The Hexagon, Volume 92, Number 1, Spring 2001, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 92, Number 1, Spring 2001, ark:/67531/metadc111181/ England - Cornwall County - Manaccan 1791-2001

info:ark/67531/metadc111174 2012-12-14T12:35:42Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Tellurium and Fata Baii (Fascebanya), Romania. Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. Clarke, Edward Daniel, 1769-1822. Tellurium museums scientific research chemical elements science technology mines travel gold nagyagite Fata Baii Mine Fascebanya Mine maps sylvanite chemistry Article describing the discovery of the element tellurium. The authors travel through Romania to visit the Transylvanian mine where tellurium was discovered. They also visit the Brukenthal Museum of Sibiu and describe the museum's mineral collection. Alpha Chi Sigma 2000-23 Article 43-45 p. : ill. (some col.) ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111174/ ark: ark:/67531/metadc111174 The Hexagon, Volume 91, Number 3, Fall 2000, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 91, Number 3, Fall 2000, ark:/67531/metadc111175/ Romania - Sibiu County - Sibiu Romania - Cluj County - Cluj-Napoca Romania - Alba County - Zlatna 1767-2000

info:ark/67531/metadc111173 2012-12-14T12:36:00Z partner:UNTCAS collection:UNTSW access_rights:public

Discovering "Rediscovery" Marshall, James L., 1940- Coppola, Brian P. Marshall, James L., 1940- Marshall, Virginia R. scientific research chemical elements science technology travel chemistry Article containing an interview of James Marshall by Brian Coppola regarding Marshall's "Rediscovery of the Elements" articles. Marshall discusses his motivations for traveling to European locations where elements were discovered, his plans for the future, and other projects. Alpha Chi Sigma 2000-23 Article [1] : ill. ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111173/ ark: ark:/67531/metadc111173 The Hexagon, Volume 91, Number 3, Fall 2000, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 91, Number 3, Fall 2000, ark:/67531/metadc111175/ 1995~-2000

info:ark/67531/metadc111172 2012-12-14T12:36:29Z partner:UNTCAS collection:UNTSW access_rights:public

Manaccan Church, Lizard Peninsula, Cornwall, England. Marshall, James L., 1940- Marshall, Virginia R. Marshall, James L., 1940- Marshall, Virginia R. scientific research chemical elements science technology travel chemistry churches Manaccan Church Cover of The Hexagon bearing the image of the Church of Manacca in Cornwall, England. The church is a stone building with arched windows visible on two levels. A crenelated tower extends up from the nearest portion of the church. Tombstones are visible near the bottom of the image, with a fronded plant to the left. The picture has the logo of The Hexagon across its top, a photo of James and Virginia Marshall on the right, and a photo from an article about pharmaceutical jobs near the center. Alpha Chi Sigma 2000-23 Article 33-34 p. : ill. ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111172/ ark: ark:/67531/metadc111172 The Hexagon, Volume 91, Number 3, Fall 2000, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 91, Number 3, Fall 2000, ark:/67531/metadc111175/ 2000 England - Cornwall County - Manaccan

info:ark/67531/metadc111177 2012-12-14T12:37:44Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Germanium Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. Germanium Germans mines miners mineralogy chemical elements chemistry scientific research Winkler, Clemens Alexander, 1838-1904. tourism maps Agricola, Georg, 1494-1555. Technisches Institut Bergakademie. Werner, Abraham Gottlob, 1749-1817. Technical Institute of Mining Academy Argyrodite Himmelsfürst (Germany) Article recounting the history of the element Germanium, including background material on mining in Germany and the isolation of Germanium by Clemens A. Winkler. Tourist information is provided regarding Winkler's laboratory and mines open to the public as museums. Alpha Chi Sigma 2001-22 Article 20-22 p. : ill. (some col.) ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111177/ ark: ark:/67531/metadc111177 The Hexagon, Volume 92, Number 2, Summer 2001, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 92, Number 2, Summer 2001, ark:/67531/metadc111182/ Germany - Saxony - Chemnitz National District - Freiberg 1542-2001-22

info:ark/67531/metadc111178 2012-12-14T12:38:58Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Montpellier and Bromine Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. Bromine French salts Aigues-Mortes (France) mineralogy chemical elements chemistry scientific research Balard, Antoine-Jérome, 1802-1876. tourism maps Article recounting the history of the element Bromine, including its discovery in the salt lagoons of the Montpellier region of France by Antoine-Jérome Balard. Maps of the region and of Balard's birthplace are presented. Alpha Chi Sigma 2001-23 Article 36-39 p. : ill. (some col.) ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111178/ ark: ark:/67531/metadc111178 The Hexagon, Volume 92, Number 3, Fall 2001, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 92, Number 3, Fall 2001, ark:/67531/metadc111180/ France - Languedoc-Roussillon Region - Hérault Department - Montpellier France - Languedoc-Roussillon Region - Hérault Department - Sète 1826-2001-23

info:ark/67531/metadc111225 2012-12-14T13:04:33Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Klaproth Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. uranium scientific research chemical elements science technology travel chemistry Klaproth, M. H. (Martin Heinrich), 1743-1817. zirconium experiments mineralogy museums mines mining Article describing the life and career of Martin Heinrich Klaproth, including his discoveries of uranium and zirconium. Tourist information regarding locations significant to his history is included. Alpha Chi Sigma 2008-22 Article 20-24 p. : col. ill. ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111225/ ark: ark:/67531/metadc111225 The Hexagon, Volume 99, Number 2, Summer 2008, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 99, Number 2, Summer 2008, ark:/67531/metadc111233/ Germany - Berlin - Berlin Germany - Saxony-Anhalt - Magdeburg National District - Wernigerode Germany - Saxony - Chemnitz National District - Johanngeorgenstadt 1743-2008

info:ark/67531/metadc111216 2012-12-14T12:57:22Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: The Road to Karlsruhe Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. atomic weight scientific research chemical elements science technology travel chemistry Dalton, John, 1766-1844. Geoffroy, Etienne-François, 1672-1731. Dumas, J.-B. (Jean-Baptiste), 1800-1884. Karlsruhe Congress Berthollet, Claude-Louis, 1748-1822. Avogadro, Amedeo, 1776-1856. Cannizzaro, Stanislao, 1826-1910. Gay-Lussac, Joseph Louis, 1778-1850. Dulong, M. (Pierre Louis), 1785-1838. Article describing the history of atomic weight and the events leading up to the Karlsruhe Congress of chemists. The authors visited several sites pertinent to these events and offer tourist information. Alpha Chi Sigma 2007-21 Article 3-9 p. : ill. (some col.) ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111216/ ark: ark:/67531/metadc111216 The Hexagon, Volume 98, Number 1, Spring 2007, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 98, Number 1, Spring 2007, ark:/67531/metadc111221/ Germany - Baden-Württemberg - Karlsruhe Region - Karlsruhe 1808-2007

info:ark/67531/metadc111219 2012-12-14T13:02:31Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Jöns Jakob Berzelius Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. atomic weight scientific research chemical elements science technology travel chemistry Berzelius, Jöns Jakob, friherre, 1779-1848. periodic table experiments atoms museums Article describing the life and career of Jöns Jakob Berzelius. Tourist information regarding locations significant to his history is included. Alpha Chi Sigma 2007-24 Article 70-76 p. : ill. (some col.) ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111219/ ark: ark:/67531/metadc111219 The Hexagon, Volume 98, Number 4, Winter 2007, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 98, Number 4, Winter 2007, ark:/67531/metadc111223/ Sweden - Stockholm County - Stockholm Sweden - Uppsala County - Uppsala 1779-2007

info:ark/67531/metadc111217 2012-12-14T12:58:03Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: The Periodic Table Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. atomic weight scientific research chemical elements science technology travel chemistry Meyer, Lothar, 1830-1895. Mendeleyev, Dmitry Ivanovich, 1834-1907. Lomonosov, Mikhail Vasilʹevich, 1711-1765. periodic table Article recounting the history of the development of the Periodic Table. Sites pertinent to this development were visited by the authors, who provide related tourist information. Alpha Chi Sigma 2007-22 Article 23-29 p. : ill. (some col.) ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111217/ ark: ark:/67531/metadc111217 The Hexagon, Volume 98, Number 2, Summer 2007, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 98, Number 2, Summer 2007, ark:/67531/metadc111222/ Poland - Dolnośla̜skie Voivodship - Breslau Germany - Brandenburg - Frankfurt National District - Eberswalde Russia - Rossiya Republic - Saint Petersburg Autonomous City - Saint Petersburg 1830-2007

info:ark/67531/metadc111224 2012-12-14T13:03:03Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Yttrium and Johan Gadolin Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. thermochemistry scientific research chemical elements science technology travel chemistry Berzelius, Jöns Jakob, friherre, 1779-1848. periodic table experiments Yttrium museums mines Article describing the life and career of Johan Gadolin. Tourist information regarding locations significant to his history is included. Alpha Chi Sigma 2008-21 Article 8-11 p. : col. ill. ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111224/ ark: ark:/67531/metadc111224 The Hexagon, Volume 99, Number 1, Spring 2008, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 99, Number 1, Spring 2008, ark:/67531/metadc111232/ Sweden - Stockholm County - Stockholm Sweden - Uppsala County - Uppsala Finland - Länsi-Suomen Lääni Province - Turku 1779-2008

info:ark/67531/metadc111227 2012-12-14T13:06:01Z partner:UNTCAS collection:UNTSW access_rights:public

Rediscovery of the Elements: Mineral Waters and Spectroscopy Rediscovery of the Elements Marshall, James L., 1940- Marshall, Virginia R. scientific research chemical elements science technology chemistry Bunsen, R. (Robert), 1811-1899. rubidium cesium mineral waters Kirchhoff, G. (Gustav), 1824-1887. spectroscopy tourism maps Article describing the career of Robert Bunsen and the history of spectroscopy and its use in mineral analysis. The discovery of cesium and rubidium using spectroscopy on mineral water is included. In addition, the authors offer tourist information regarding locations pertinent to Bunsen and certain mineral water springs. Alpha Chi Sigma 2008-23 Article 42-46 p. : col. ill. ; 28 cm. Text http://digital.library.unt.edu/ark:/67531/metadc111227/ ark: ark:/67531/metadc111227 The Hexagon, Volume 99, Number 3, Fall 2008, Alpha Chi Sigma, Indianapolis, Indiana English The Hexagon, Volume 99, Number 3, Fall 2008, ark:/67531/metadc111231/ England - Kent County - Leeds Germany - Baden-Württemberg - Karlsruhe National District - Heidelberg Germany - Berlin - Berlin 1767-2008

info:ark/67531/metadc111228 2012-12-14T13:06:22Z partner:UNTCAS collection:UNTSW access_rights:public

The Story Behind the Cover Marshall, James L., 1940- Marshall, Virginia R. scienti