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 Collection: UNT Theses and Dissertations
First Principle Calculations of the Structure and Electronic Properties of Pentacene Based Organic and ZnO Based Inorganic Semiconducting Materials

First Principle Calculations of the Structure and Electronic Properties of Pentacene Based Organic and ZnO Based Inorganic Semiconducting Materials

Date: May 2012
Creator: Li, Yun
Description: In this thesis, I utilize first principles density functional theory (DFT) based calculations to investigate the structure and electronic properties including charge transfer behaviors and work function of two types of materials: pentacene based organic semiconductors and ZnO transparent conducting oxides, with an aim to search for high mobility n-type organic semiconductors and fine tuning work functions of ZnO through surface modifications. Based on DFT calculations of numerous structure combinations, I proposed a pentacene and perfluoro-pentacene alternating hybrid structures as a new type of n-type semiconductor. Based on the DFT calculations and Marcus charge transfer theory analysis, the new structure has high charge mobility and can be a promising new n-type organic semiconductor material. DFT calculations have been used to systematically investigate the effect of surface organic absorbate and surface defects on the work function of ZnO. It was found that increasing surface coverage of organic groups and decreasing surface defects lead to decrease of work functions, in excellent agreement with experimental results. First principles based calculations thus can greatly contribute to the investigating and designing of new electronic materials.
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The Role of Tasks in the Internet Health Information Searching of Chinese Graduate Students

The Role of Tasks in the Internet Health Information Searching of Chinese Graduate Students

Date: May 2012
Creator: Pan, Xuequn
Description: The purpose of the study was to examine the relationships between types of health information tasks and the Internet information search processes of Chinese graduate students at the University of North Texas. the participants' Internet information search processes were examined by looking at the source used to start the search, language selection, use of online translation tools, and time spent. in a computer classroom, 45 Chinese graduate students searched the Internet and completed three health information search tasks: factual task, interpretative task, and exploratory task. Data of the Chinese graduate students’ health information search processes were gathered from Web browser history files, answer sheets, and questionnaires. Parametric and non-parametric statistical analyses were conducted to test the relationships between the types of tasks and variables identified in the search process. Results showed that task types only had a statistically significant impact on the time spent. for the three tasks, the majority of Chinese graduate students used search engines as major sources for the search starting point, utilized English as the primary language, and did not use online translation tools. the participants also reported difficulties in locating relevant answers and recommended ways to be assisted in the future when searching the Internet ...
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Blogging and Tweens: Communication Portal to Reading Selection and Engagement

Blogging and Tweens: Communication Portal to Reading Selection and Engagement

Date: May 2012
Creator: Sharber, Shelli K.
Description: The ethnographic study utilized the research techniques of observations, content analysis, and semi-structured interviews with tween participants (i.e., 9 through 13 year-old youth) during an 8-week literary blog project. Twenty-six participants created individual blog pages within a member-only classroom blog site that allowed for online communication between members. the blog project incorporated social networking applications with which youth frequently engage. the research questions ensured data regarding what facets participants found appealing and motivating during the project was collected. the questions allowed for determining if participants utilized peer blogs for reading material selection or repurposed the blogs to discuss other topics. Components of self-determination theory and engagement theory underlay the project design and aided in identifying motivational aspects of the data. Frequency tables outlined the identified patterns and structures of participants’ online activity. Participants found the ability to change the colors of their blog backgrounds and to design their individual blogs and the giving and receiving of feedback to be the two most appealing features of the project. Participants chose books from peer suggestions in the online world but also selected materials from recommendations they received in face-to-face interactions with their peers, their teacher, and the school librarian. Little evidence of ...
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Monitoring and Increasing Goal Related Instruction and Engagement in Groups of Children with Autism

Monitoring and Increasing Goal Related Instruction and Engagement in Groups of Children with Autism

Date: May 2012
Creator: Rossi, Kathleen Anne
Description: A high rate of instructional engagement is important to maximize progress in early intensive behavioral interventions (EIBI). Teachers responsible for eliciting instructional engagement may need additional support to maintain high rates of engagement. Literature suggests that goal setting and feedback is effective in increasing performance. the purpose of this study was to evaluate whether goal setting and group feedback would increase engagement in instructional activities related to the children’s goals. Results indicate that goal setting and group feedback was successful in increasing engagement in instructional activities. the results are discussed in the context of engagement, staff performance, group contingencies and performance feedback.
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Modification of Graphene Properties: Electron Induced Reversible Hydrogenation, Oxidative Etching and Layer-by-layer Thinning

Modification of Graphene Properties: Electron Induced Reversible Hydrogenation, Oxidative Etching and Layer-by-layer Thinning

Date: May 2012
Creator: Jones, Jason David
Description: In this dissertation, I present the mechanism of graphene hydrogenation via three different electron sources: scanning electron microscopy, e-beam irradiation and H2 and He plasma irradiation. in each case, hydrogenation occurs due to electron impact fragmentation of adsorbed water vapor from the sample preparation process. in the proposed model, secondary and backscattered electrons generated from incident electron interactions with the underlying silicon substrate are responsible for the dissociation of water vapor. Chemisorbed H species from the dissociation are responsible for converting graphene into hydrogenated graphene, graphane. These results may lead to higher quality graphane films having a larger band gap than currently reported. in addition, the dissertation presents a novel and scalable method of controllably removing single atomic planes from multi-layer graphene using electron irradiation from an intense He plasma under a positive sample bias. As the electronic properties or multi-layer graphene are highly dependent on the number of layers, n, reducing n in certain regions has many benefits. for example, a mask in conjunction with this thinning method could be used for device applications.
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Evaluation of Fine Particulate Matter Pollution Sources Affecting Dallas, Texas

Evaluation of Fine Particulate Matter Pollution Sources Affecting Dallas, Texas

Date: May 2012
Creator: Puthenparampil Koruth, Joseph
Description: Dallas is the third largest growing industrialized city in the state of Texas. the prevailing air quality here is highly influenced by the industrialization and particulate matter 2.5µm (PM2.5) has been found to be one of the main pollutants in this region. Exposure to PM2.5 in elevated levels could cause respiratory problems and other health issues, some of which could be fatal. the current study dealt with the quantification and analysis of the sources of emission of PM2.5 and an emission inventory for PM2.5 was assessed. 24-hour average samples of PM2.5 were collected at two monitoring sites under the Texas Commission on Environmental Quality (TCEQ) in Dallas, Dallas convention Centre (CAMS 312) and Dallas Hinton sites (CAMS 60). the data was collected from January 2003 to December 2009 and by using two positive matrix models PMF 2 and EPA PMF the PM2.5 source were identified. 9 sources were identified from CAMS 312 of which secondary sulfate (31% by PMF2 and 26% by EPA PMF) was found to be one of the major sources. Data from CAMS 60 enabled the identification of 8 sources by PMF2 and 9 by EPA PMF. These data also confirmed secondary sulfate (35% by PMF2 and ...
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Establishing Editorial Principles to Create a Performance Edition of Selections From Appunti Op 210 By Mario Castelnuovo-tedesco

Establishing Editorial Principles to Create a Performance Edition of Selections From Appunti Op 210 By Mario Castelnuovo-tedesco

Date: May 2012
Creator: Lee, Chris
Description: This paper examined editorial methods used in producing published versions of the music of Mario Castelnuovo-Tedesco (1895-1968). From this examination, I established some editorial principles to create a performance edition of five movements from book two of Castelnuovo-Tedesco’s Appunti op. 210. This paper includes a discussion of the sources and methods used in establishing editorial criteria. at the request of the Milanese guitarist Ruggero Chiesa (1933-1993), Castelnuovo-Tedesco set out to create a collection of didactic pieces for young guitarists. the pieces were to be collaboratively edited and fingered by Chiesa, and then given final approval by the composer. Unfortunately, the composer died before finishing the work. the pieces and sketches that survive exist in four volumes published by the Italian house, Suvini Zerboni, containing the pieces that Chiesa edited with the approval of Castelnuovo-Tedesco. the published edition also includes unedited pieces that did not undergo the collaborative process. with the goal of maintaining an unadulterated portrayal of the composer’s intentions, Chiesa presented these pieces as they appear in the manuscript. Much of the music is unidiomatic and either impossible or highly impractical to play. My study established some editorial principles for use in creating a performance edition of this work. ...
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“The Way It Goes”: Stories

“The Way It Goes”: Stories

Date: May 2012
Creator: Wood, Joshua
Description: This collection of short stories attempts to examine the role of a changing and often indifferent world has in the way various characters achieve maturity. Though the past is not always obvious in each story, each protagonist is characterized as holding onto some aspect of his or her past life in a way that is detrimental to their growing as human beings. the stories attempt to portray the indifference of the world as it moves forward to the plight of these characters, and to portray the manner in which they each come to terms with such a world and with their own lives.
Contributing Partner: UNT Libraries
Implementation of Wireless Communications on Gnu Radio

Implementation of Wireless Communications on Gnu Radio

Date: May 2012
Creator: Njoki, Simon M.
Description: This thesis investigates the design and implementation of wireless communication system over the GNU Radio. Wireless applications are on the rise with advent of new devices, therefore there is a need to transfer the hardware complexity to software. This development enables software radio function with minimum hardware dependency. the purpose of this thesis is to design a system that will transmit compressed data via Software Defined Radio (SDR). Some parameters such as modulation scheme, bit rate can be changed to achieve the desired quality of service. in this thesis GNU (GNU’s not unix) radio is used while the hardware structure is Universal Software Radio Peripheral (USRP). in order to accomplish the goal, a compression technique called H264 (MPEG_4) encoding is applied for converting data into compressed format. the encoder was implemented in C++ to get compressed data. After encoding, the transmitter reads the compressed data and starts modulation. After modulation, the transmitter put the packets into USRP and sends it to the receiver. Once packets are received they are demodulated and then decoded to recover the original data.
Contributing Partner: UNT Libraries
Western Media Attitudes Toward an Immigrant of Color Sex Crime Victim: Case Study: the DSK Case

Western Media Attitudes Toward an Immigrant of Color Sex Crime Victim: Case Study: the DSK Case

Date: May 2012
Creator: Mumah, Jenny
Description: About 30 million women in the U.S. are estimated to be victims of sex crimes in their lifetimes. However, sex crimes, especially those committed against immigrants are the least reported crime in the country. Some sex crime victims say the fear of media criticism discourages them from reporting the crime. in May 2011, an African maid working at a New York hotel accused Dominique Strauss-Kahn, the former director of the International Monetary Fund, of sexually assaulting her. This qualitative content analysis examined the coverage of the DSK case, by three leading international newspapers: the New York Times, the Guardian and Le Monde. Findings suggest that Strauss-Kahn received more favorable coverage than Diallo. Frames identified in the coverage include the importance of status/prominence, race, culture differences, victim-blaming, male privilege, socioeconomic differences and focus on appearance. the study recommends that news organizations avoid judgmental coverage of sex crimes and consider identifying victims by allowing them to tell their side of the story.
Contributing Partner: UNT Libraries