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Research and Development for Novel Thermal Energy Storage Systems (TES) for Concentrating Solar Power (CSP)

Description: The overall objective was to develop innovative heat transfer devices and methodologies for novel thermal energy storage systems for concentrating solar power generation involving phase change materials (PCMs). Specific objectives included embedding thermosyphons and/or heat pipes (TS/HPs) within appropriate phase change materials to significantly reduce thermal resistances within the thermal energy storage system of a large-scale concentrating solar power plant and, in turn, improve performance of the plant. Experimental, system level and detailed comprehensive modeling approaches were taken to investigate the effect of adding TS/HPs on the performance of latent heat thermal energy storage (LHTES) systems.
Date: September 26, 2013
Creator: Faghri, Amir; Bergman, Theodore L & Pitchumani, Ranga
Partner: UNT Libraries Government Documents Department

Final Report - Effects of Impurities on Fuel Cell Performance and Durability

Description: This program is focused on the experimental determination of the effects of key hydrogen side impurities on the performance of PEM fuel cells. Experimental data has been leveraged to create mathematical models that predict the performance of PEM fuel cells that are exposed to specific impurity streams. These models are validated through laboratory experimentation and utilized to develop novel technologies for mitigating the effects of contamination on fuel cell performance. Results are publicly disseminated through papers, conference presentations, and other means.
Date: August 18, 2012
Creator: Molter, Trent
Partner: UNT Libraries Government Documents Department

ASM News Volume 71 Number 9, 2005

Description: Genetic exchanges among prokaryotes, formerly considered only a marginal phenomenon, increasingly are being viewed as profoundly affecting evolution. Indeed, some researchers argue for utterly revamping our concept of microbial speciation and phylogeny by replacing the traditional ''tree'' with a newer ''net'' to account for these horizontal transfers of genes. This conceptual ferment is occurring while molecular biologists reveal how horizontal gene transfers occur even as microbes protect the integrity of their genomes. Other studies reveal the number and diversity and abundance of genetic elements that mediate horizontal gene transfers (HGTs) or facilitate genome rearrangements, deletions, and insertions. Taken together, this information suggests that microbial communities collectively possess a dynamic gene pool, where novel genetic combinations act as a driving force in genomic innovation, compensating individual microbial species for their inability to reproduce sexually. These microbial genomic dynamics can present both environmental threats and promise to humans. One major threat, for example, comes from the spread of antibiotic resistance and virulence genes among pathogenic microbes. Another less-documented issue involves transgenic plants and animals, whose uses are being restricted because of concerns that genes may be transferred to untargeted organisms where they might cause harm. A possible benefit from HGT comes from its potential to enhance the functional diversity of microbial communities and to improve their performance in changing or extreme environments. Such changes might be exploited, for example, as part of efforts to manage environmental pollution and might be achieved by spreading genes into resident microbes to confer specific biochemical activities.
Date: January 1, 2005
Creator: Smets, Tamar Barkay and Barth F.
Partner: UNT Libraries Government Documents Department

Development of Nanoscale Ceramics for Advanced Power Applications

Description: Bulk structures of unstabilized ZrO{sub 2-x}, with x in the range of 0 {<=} x {<=} 0.44, at ambient pressure have been found to exist in three different structures. (monoclinic, tetragonal and cubic.). At ambient temperature and elevated pressures above 3.5 GPa, unstabilized zirconia at these same compositions is found as a fourth phase, the orthorhombic phase. Work done in this project has demonstrated that nanoscale zirconia particles containing the orthorhombic phase in addition to amorphous material can be produced through solgel methods. Extensive characterization of this material including recent high temperature x-ray diffraction work has indicated that the structure of the synthesized zirconia appears to be linked to the oxygen vacancy population in the material, and that water appears to be a critical factor in determining the type of material formed during synthesis. These results suggest that surface energy alone is not the controlling factor in determining crystal phase.
Date: September 30, 1999
Creator: Leffler, Miriam & Helble, Joseph
Partner: UNT Libraries Government Documents Department

Effects and Mechanisms of Mechanical Activation on Hydrogen Sorption/ Desorption of Nanoscale Lithium Nitrides

Description: The objective of this project is to investigate and develop novel, mechanically activated, nanoscale Li3N-based and LiBH4-based materials that are able to store and release {approx}10 wt% hydrogen at temperatures near 100 C with a plateau hydrogen pressure of less than 10 bar. Four (4) material systems have been investigated in the course of this project in order to achieve the project objective. These 4 systems are (i) LiNH2+LiH, (ii) LiNH2+MgH2, (iii) LiBH4, and (iv) LiBH4+MgH2. The key findings we have obtained from these 4 systems are summarized below. *The thermodynamic driving forces for LiNH2+LiH and LiBH4 systems are not adequate to enable H2 release at temperatures < 100 C. *Hydrogen release in the solid state for all of the four systems is controlled by diffusion, and thus is a slow process. *LiNH2+MgH2 and LiBH4+MgH2 systems, although possessing proper thermodynamic driving forces to allow for H2 release at temperatures < 100 C, have sluggish reaction kinetics because of their diffusion-controlled rate-limiting steps. *Reducing particles to the nanometer length scale (< 50 nm) can improve the thermodynamic driving force to enable H2 release at near ambient temperature, while simultaneously enhancing the reaction kinetics as well as changing the diffusion-controlled rate-limiting step to gas desorption-controlled rate-limiting step. This phenomenon has been demonstrated with LiBH4 and offers the hope that further work along this direction will make one of the material systems, i.e., LiBH4, LiBH4+MgH2 and LiNH2+MgH2, possess the desired thermodynamic properties and rapid H2 uptake/release kinetics for on-board applications. Many of the findings and knowledge gained from this project have been published in archival refereed journal articles [1-15] and are accessible by general public. Thus, to avoid a bulky final report, the key findings and knowledge gained from this project will be succinctly summarized, particularly for those findings and knowledge available in ...
Date: April 26, 2012
Creator: Shaw, Leon, L.; Yang, Gary, Z.; Crosby, Kyle; Wwan, Xufei. Zhong, Yang; Markmaitree, Tippawan; Osborn, William et al.
Partner: UNT Libraries Government Documents Department

The Development of Low-Cost Integrated Composite Seal for SOFC: Materials and Design Methodologies

Description: This report summarizes the work conducted by UConn SOFC seal development team during the Phase I program and no cost extension. The work included composite seal sample fabrication, materials characterizations, leak testing, mechanical strength testing, chemical stability study and acoustic-based diagnostic methods. Materials characterization work revealed a set of attractive material properties including low bulk permeability, high electrical resistivity, good mechanical robustness. Composite seal samples made of a number of glasses and metallic fillers were tested for sealing performance under steady state and thermal cycling conditions. Mechanical testing included static strength (pull out) and interfacial fracture toughness measurements. Chemically stability study evaluated composite seal material stability after aging at 800 C for 168 hrs. Acoustic based diagnostic test was conducted to help detect and understand the micro-cracking processes during thermal cycling test. The composite seal concept was successfully demonstrated and a set of material (coating composition & fillers) were identified to have excellent thermal cycling performance.
Date: July 31, 2006
Creator: Huang, Xinyu; Ridgeway, Kristoffer; Narasimhan, Srivatsan; Timin, Serg; Huang, Wei; Ozevin, Didem et al.
Partner: UNT Libraries Government Documents Department

Development of Sensors Using Evanescent Wave Interactions in Sapphire Optical Fibers

Description: The development of tunable diode laser absorption sensors for measurements in industrial boilers, both through direct absorption and evanescent wave absorption have been performed in the work presented here. These sensors use both direct and indirect absorption through the use of evanescent interactions within a coal firing combustion environment. For the direct absorption sensor, wavelength modulation absorption spectroscopy with second-harmonic detection was implemented within a physical probe designed to be placed with the flue stack of a power plant. Measurements were taken of carbon dioxide and water vapor concentration during operation at a local industrial facility. The design of this sensor probe overcomes problems of beam steering and permits a reference gas measurement. Extracted concentration data and design elements from the direct absorption measurements are presented. In addition, development of a sapphire fiber-based sensor using evanescent wave absorption along the outside of the fiber is presented. Evanescent absorption allows for the laser transmission to be maintained in the fiber at all times and may alleviate problems of background emission, beam steering, and especially scattering of the laser beam from solid particles experienced through free path direct absorption measurements in particulated flows. Laboratory measurements using evanescent fiber detection are presented.
Date: December 31, 2006
Creator: Renfro, Michael W. & Jordan, Eric H.
Partner: UNT Libraries Government Documents Department

Homogeneous and Heterogeneous Reaction and Transformation of Hg and Trace Metals in Combustion Systems

Description: The overall goal of this project was to produce a working dynamic model to predict the transformation and partitioning of trace metals resulting from combustion of a broad range of fuels. The information provided from this model will be instrumental in efforts to identify fuels and conditions that can be varied to reduce metal emissions. Through the course of this project, it was determined that mercury (Hg) and arsenic (As) would be the focus of the experimental investigation. Experiments were therefore conducted to examine homogeneous and heterogeneous mercury oxidation pathways, and to assess potential interactions between arsenic and calcium. As described in this report, results indicated that the role of SO{sub 2} on Hg oxidation was complex and depended upon overall gas phase chemistry, that iron oxide (hematite) particles contributed directly to heterogeneous Hg oxidation, and that As-Ca interactions occurred through both gas-solid and within-char reaction pathways. Modeling based on this study indicated that, depending upon coal type and fly ash particle size, vaporization-condensation, vaporization-surface reaction, and As-CaO in-char reaction all play a role in arsenic transformations under combustion conditions.
Date: August 31, 2009
Creator: Helble, J.; Smith, Clara & Miller, David
Partner: UNT Libraries Government Documents Department

Multifunctional Nanowire/film Composites based Bi-modular Sensors for In-situ and Real-time High Temperature Gas Detection

Description: This final report to the Department of Energy/National Energy Technology Laboratory for DE-FE0000870 covers the period from 2009 to June, 2013 and summarizes the main research accomplishments, which can be divided in sensing materials innovation, bimodular sensor demonstration, and new understanding and discoveries. As a matter of fact, we have successfully completed all the project tasks in June 1, 2013, and presented the final project review presentation on the 9th of July, 2013. Specifically, the major accomplishments achieved in this project include: 1) Successful development of a new class of high temperature stable gas sensor nanomaterials based on composite nano-array strategy in a 3D or 2D fashion using metal oxides and perovskite nanostructures. 2) Successful demonstration of bimodular nanosensors using 2D nanofibrous film and 3D composite nanowire arrays using electrical resistance mode and electrochemical electromotive force mode. 3) Series of new discoveries and understandings based on the new composite nanostructure platform toward enhancing nanosensor performance in terms of stability, selectivity, sensitivity and mass flux sensing. In this report, we highlight some results toward these accomplishments.
Date: June 1, 2013
Creator: Gao, Pu-Xian & Lei, Yu
Partner: UNT Libraries Government Documents Department

Three-Dimensional Composite Nanostructures for Lean NOx Emission Control

Description: This final report to the Department of Energy (DOE) and National Energy Technology Laboratory (NETL) for DE-EE0000210 covers the period from October 1, 2009 to July 31, 2013. Under this project, DOE awarded UConn about $1,248,242 to conduct the research and development on a new class of 3D composite nanostructure based catalysts for lean NOx emission control. Much of the material presented here has already been submitted to DOE/NETL in quarterly technical reports. In this project, through a scalable solution process, we have successfully fabricated a new class of catalytic reactors, i.e., the composite nanostructure array (nano-array) based catalytic converters. These nanocatalysts, distinct from traditional powder washcoat based catalytic converters, directly integrate monolithic substrates together with nanostructures with well-defined size and shape during the scalable hydrothermal process. The new monolithic nanocatalysts are demonstrated to be able to save raw materials including Pt-group metals and support metal oxides by an order of magnitude, while perform well at various oxidation (e.g., CO oxidation and NO oxidation) and reduction reactions (H{sub 2} reduction of NOx) involved in the lean NOx emissions. The size, shape and arrangement of the composite nanostructures within the monolithic substrates are found to be the key in enabling the drastically reduced materials usage while maintaining the good catalytic reactivity in the enabled devices. The further understanding of the reaction kinetics associated with the unique mass transport and surface chemistry behind is needed for further optimizing the design and fabrication of good nanostructure array based catalytic converters. On the other hand, the high temperature stability, hydrothermal aging stability, as well as S-poisoning resistance have been investigated in this project on the nanocatalysts, which revealed promising results toward good chemical and mechanical robustness, as well as S-poisoning resistance. Further investigation is needed for unraveling the understanding, design and selection principles of ...
Date: July 31, 2013
Creator: Gao, Pu-Xian
Partner: UNT Libraries Government Documents Department

technical report and journal articles

Description: Objective: This project seeks to improve the application of noble gas isotope studies to multiphase fluid processes in the Earth's crust by (1) identifying the important noble gas carrier phases in sediments to address the processes that have led to the observed enrichment and depletion patterns in sedimentary rocks and fluids, (2) examine the mechanisms by which such noble gas patterns are acquired, trapped and subsequently released to mobile crustal fluids, and (3) evaluate the time and length scales for the transport of noble gas components, such as radiogenic 4He, through the continental crust.. Project Description: Sedimentary rocks and oil field gases typically are enriched in heavy noble gases: Xe/Ar ratios of ~10-10,000 times the ratio in air have been observed that cannot be explained by adsorption hypotheses. Laboratory experiments designed to isolate sedimentary phases for noble gas analysis are conducted to identify the carrier phase(s). It has been observed that radiogenic 4He accumulates in confined aquifer waters at rates that exceed the rate of local production and approaching the whole crustal production rate. A literature evaluation of 4He, 3He crustal fluxes is being conducted to evaluate crustal scale mass transport in terms of the rate, mechanisms, temporal and spatial variability and the role played by tectonic processes. Results: The laboratory study has concentrated on noble gas abundances in a variety of sedimentary silica samples. We have found that, in general, samples of inorganic silica have noble gas abundances that are consistent with occlusion of air-saturated water in fluid inclusions and lack requisite enrichment/depletion factors needed to explain the noble gas inventory in oil field fluids. However, numerous replicate analyses of noble gases extracted from silica spicules from live sponges (Calyxnicaeensis) show significantly enriched Ar, Kr, and Xe concentrations ([iNg]sample/[iNg]asw > 1), but with very little if any mass dependence ...
Date: March 25, 2011
Creator: Torgerson, Thomas & Kennedy, B. M.
Partner: UNT Libraries Government Documents Department

Sugar Transport and Metabolism in Thermotoga

Description: The work conducted under this grant demonstrated that the hyperthermophilic bacterium Thermotoga neapolitana carries out glucose and lactose transport in a sodium-dependent manner and that energization of anaerobic cells is required to observe transport. We also demonstrated that Thermotoga maritima carries out maltose and glucose transport using periplasmic sugar binding proteins. We began defining patterns of expression of genes encoding sugar transport and catabolic functions in both T. maritima and T. neapolitana. We began a collaborative effort to identify all the genes regulated at the transcriptional level in response to sugars substrates. These funds also allowed us to begin an examination of the functions of several periplasmic substrate binding proteins encoded in the genome of T. maritima.
Date: February 11, 2003
Creator: Noll, Kenneth M. & Romano, Antonio H.
Partner: UNT Libraries Government Documents Department

Modeling of Diffusion of Plutonium in Other Metals and of Gaseous Species in Plutonium-Based Systems

Description: The problem being addressed is to establish standards for temperature conditions under which plutonium, uranium, or neptunium from nuclear wastes permeates steel, with which it is in contact, by diffusion processes. The primary focus is on plutonium because of the greater difficulties created by the peculiarities of face-centered-cubic-stabilized (delta) plutonium (the form used in the technology generating the waste). Temperature is the key controllable diffusion processes, i.e., temperature controls the rate of diffusion. The scientific goal of this project is to predict diffusion constants on an ab initio basis, i.e. diffusion distances in specified time at specified temperature for plutonium from plutonium-based waste materials into various steels or technologically-pertinent metallic alloys. This predictive ability will help to provide information relevant to setting temperature standards for maintaining structures, ducts, equipment or waste-containing vessels until such time as decontamination and decommissioning and/or permanent storage can be carried out. In addition, this knowledge will aid in assessing the depth of penetration that must be dealt with in any surface treatment for decontamination. The scientific steps of the methodology are (1) to recognize the stabilizing mechanism and the electronic structure pertinent to that stabilization for face-centered-cubic (fcc) delta-stabilized plutonium, (2) to extract the information needed to perform dynamic simulations from ab initio electronic structure calculations, (3) to perform and report the dynamic simulations predicting the diffusion behavior.
Date: June 1, 1999
Creator: Cooper, Bernard R. & Fernando, Gayanath
Partner: UNT Libraries Government Documents Department

Horizontal gene transfer as adaptive response to heavy metal stress in subsurface microbial communities. Final report for period October 15, 1997 - October 15, 2000

Description: Horizontal gene transfer as adaptive response to heavy metal stress in the presence of heavy metal stress was evaluated in oligotrophic subsurface soil laboratory scale microcosms. Increasing levels of cadmium (10, 100 and 1000 mM) were applied and an E. coli donor was used to deliver the target plasmids, pMOL187 and pMOL222, which contained the czc and ncc operons, and the helper plasmid RP4. Plasmid transfer was evaluated through monitoring of the heavy metal resistance and presence of the genes. The interactive, clearly revealed, effect of biological and chemical external factors on the extent of plasmid-DNA propagation in microbial communities in contaminated soil environments was observed in this study. Additionally, P.putida LBJ 415 carrying a suicide construct was used to evaluate selective elimination of a plasmid donor.
Date: December 21, 2001
Creator: Smets, B. F.
Partner: UNT Libraries Government Documents Department

Molecular analysis of a thylakoid K+ channel

Description: The work undertaken during the prior granting period sought to use a novel probe to identify and clone plant ion (K) channels. It was also proposed that in vitro biochemical studies of cation transport across purified preparations of thylakoid membrane be employed to characterize a putative K channel in this membrane system. Over the last several years (including those of the previous grant period), an enormous data base of partially-sequenced mRNAs and numerous genomes (including those of plants) has evolved and provides a powerful alternative to this brute-force approach to identify and clone cDNAs ending physiologically important membrane proteins such as channels. The utility of searching genetic databases for relevant sequences, in addition to the difficulty of working with membrane proteins, led to changes in research focus during the prior granting period, and has resulted in the identification of a new class of plant ion channels, which will be the focus of research during the proposed new granting period.
Date: May 1, 2000
Partner: UNT Libraries Government Documents Department

Modeling of Diffusion of Plutonium in Other Metals and of Gaseous Species in Plutonium-Based Systems

Description: The problem being addressed is to establish standards for temperature conditions under which plutonium, uranium, or neptunium from nuclear wastes permeates steel, with which it is in contact, by diffusion processes. The primary focus is on plutonium because of the greater difficulties created by the peculiarities of face-centered-cubic-stabilized (delta) plutonium (the form used in the technology generating the waste). Temperature is the key controllable diffusion process, i.e., temperature controls the rate of diffusion. The scientific goal of this project is to predict diffusion constants on an ab initio basis, i.e. diffusion distances in specified time at specified temperature for plutonium from plutonium-based waste materials into various steels or technologically-pertinent metallic alloys. This predictive ability will help to provide information relevant to setting temperature standards for maintaining structures, ducts, equipment, or waste-containing vessels until such time as decontamination and decommissioning and/or permanent storage can be carried out. In 2 addition, this knowledge will aid in assessing the depth of penetration that must be dealt with in any surface treatment for decontamination. The scientific steps of the methodology are (1) to recognize the stabilizing mechanism and the electronic structure pertinent to that stabilization for face-centered-cubic (fcc) deltastabilized plutonium, (2) to extract the information needed to perform dynamic simulations from ab initio electronic structure calculations, (3) to perform and report the dynamic simulations predicting the diffusion behavior.
Date: June 1, 2001
Creator: Cooper, Bernard R. & Fernando, Gayanath W.
Partner: UNT Libraries Government Documents Department

Modeling of Diffusion of Plutonium in Other Metals and of Gaseous Species in Plutonium-Based Systems

Description: The problem being addressed is to establish standards for temperature conditions under which plutonium, uranium, or neptunium from nuclear wastes permeates steel, with which it is in contact, by diffusion processes. The primary focus is on plutonium because of the greater difficulties created by the peculiarities of face-centered-cubic-stabilized (delta) plutonium (the form used in the technology generating the waste). Temperature is the key controllable diffusion processes, i.e., temperature controls the rate of diffusion. The scientific goal of this project is to predict diffusion constants on an ab initio basis, i.e. diffusion distances in specified time at specified temperature for plutonium from plutonium-based waste materials into various steels or technologically-pertinent metallic alloys. This predictive ability will help to provide information relevant to setting temperature standards for maintaining structures, ducts, equipment, or waste-containing vessels until such time as decontamination and decommissioning and/or permanent storage can be carried out. In addition, this knowledge will aid in assessing the depth of penetration that must be dealt with in any surface treatment for decontamination. The scientific steps of the methodology are (1) to recognize the stabilizing mechanism and the electronic structure pertinent to that stabilization for face-centered-cubic (fcc) deltastabilized plutonium, (2) to extract the information needed to perform dynamic simulations from ab initio electronic structure calculations, (3) to perform and report the dynamic simulations predicting the diffusion behavior.
Date: June 1, 2000
Creator: Cooper, Bernard, R. & Fernando, Gayanath W.
Partner: UNT Libraries Government Documents Department