UNT Theses and Dissertations - 96 Matching Results

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The Acceptance and Use of Cloud Computing Services by Small and Medium Enterprises in Lagos, Nigeria

Description: This study explored the acceptance of cloud computing (CC) services by small and medium enterprises (SMEs) in Lagos, Nigeria, which has been missing from CC services literature. It aimed to understand the motivations for adoption, the uses of the services, and the benefits they derive from it. The uses and gratification theory was applied as the theoretic framework for this endeavor. An online survey with close-ended and open-ended questions was distributed to 1200 randomly selected participants through email. In total, 392 valid responses were collected and analyzed using descriptive statistics and categories. The results found that SMEs in Lagos, Nigeria had a low level of awareness and appreciation of CC services. The adoption rate was also low. Unlike their counterparts in other regions, SMEs primary concerns were service downtime, stable power supply, and better internet access. The study found that SMEs were not taking full advantage of the capabilities of CC services. Some sections, however, were doing better than others, such as the information and communications sub-sector. This study suggested that targeted interventions should be conducted to raise the awareness of CC services in SMEs, and to improve their efficient and effective use of CC services. The uses and gratification theory was appropriate for guiding this study to understand the acceptance and use of CC services by SMEs in Lagos, Nigeria.
Date: May 2017
Creator: Azogu, Olajumoke O
Partner: UNT Libraries

The Aesthetics of Sin: Beauty and Depravity in Early Modern English Literature

Description: This dissertation argues that early modern writers such as William Shakespeare, Thomas Middleton, George Herbert, John Milton, and Andrew Marvell played a critical role in the transition from the Neoplatonic philosophy of beauty to Enlightenment aesthetics. I demonstrate how the Protestant Reformation, with its special emphasis on the depravity of human nature, prompted writers to critique models of aesthetic judgment and experience that depended on high faith in human goodness and rationality. These writers in turn used their literary works to popularize skepticism about the human mind's ability to perceive and appreciate beauty accurately. In doing so, early modern writers helped create an intellectual culture in which aesthetics would emerge as a distinct branch of philosophy.
Date: December 2017
Creator: Jeffrey, Anthony Cole
Partner: UNT Libraries

Age Friendly Cities: The Bureaucratic Responsiveness Effects on Age Friendly Policy Adoption

Description: Challenging a long-held attachment to the medical model, this research develops a cultural model placing local governments at the center of policy making and refocusing policy attention on mobility, housing, the built environment and services. To examine the phenomenon of age friendly policy adoption by cities and the magnitude of adoption, a 21-question web-based survey was administered to a sample of 1,050 cities from the U.S. Census having a population over 10,000 and having at least 14% of their population aged 65 years and over. The goal of the questionnaire was to help identify what kind of policy objectives cities establish to facilitate the opportunity for older adults to live healthy and independent lives in their communities as they age. Multiple linear and ordinal regression models examined the likelihood of policy action by cities and provide evidence as to why some cities support more age friendly policy actions than others. Evidence illustrates theoretical advancement providing support for a cultural model of aging. The cultural model includes multiple factors including bureaucratic responsiveness reflected in the management values of the administration. Findings show variation in the integration of a cultural awareness of aging in the municipality's needs assessment, strategic goals, citizen engagement strategies, and budgetary principles. Cities with a cultural awareness of aging are more likely to adopt age friendly policies. Findings also provide support for the argument that the public administrator is not the driving sole factor in decision making. A shared spaced with mobilized citizen need of individuals 65 and over is identified.
Date: May 2017
Creator: Keyes, Laura Marie
Partner: UNT Libraries

Analysis and Performance of a Cyber-Human System and Protocols for Geographically Separated Collaborators

Description: This dissertation provides an innovative mechanism to collaborate two geographically separated people on a physical task and a novel method to measure Complexity Index (CI) and calculate Minimal Complexity Index (MCI) of a collaboration protocol. The protocol is represented as a structure, and the information content of it is measured in bits to understand the complex nature of the protocol. Using the complexity metrics, one can analyze the performance of a collaborative system and a collaboration protocol. Security and privacy of the consumers are vital while seeking remote help; this dissertation also provides a novel authorization framework for dynamic access control of resources on an input-constrained appliance used for completing the physical task. Using the innovative Collaborative Appliance for REmote-help (CARE) and with the support of a remotely located expert, fifty-nine subjects with minimal or no prior mechanical knowledge are able to elevate a car for replacing a tire in an average time of six minutes and 53 seconds and with an average protocol complexity of 171.6 bits. Moreover, thirty subjects with minimal or no prior plumbing knowledge are able to change the cartridge of a faucet in an average time of ten minutes and with an average protocol complexity of 250.6 bits. Our experiments and results show that one can use the developed mechanism and methods for expanding the protocols for a variety of home, vehicle, and appliance repairs and installations.
Date: December 2017
Creator: Jonnada, Srikanth
Partner: UNT Libraries

Application of UV-Vis Spectroscopy to the Monitoring, Characterization and Analysis of Chemical Equilibria of Copper Etching Baths

Description: The continuously increasing demand for innovation in the miniaturization of microelectronics has driven the need for ever more precise fabrication strategies for device packaging, especially for printed circuit boards (PCBs). Subtractive copper etching is a fundamental step in the fabrication process, requiring very precise control of etch rate and etch factor. Changes in the etching chemical equilibrium have significant effects on etching behavior, and CuCl2 / HCl etching baths are typically monitored with several parameters including oxidation-reduction potential, conductivity, and specific gravity. However, the etch rate and etch factor can be difficult to control even under strict engineering controls of those monitoring parameters. The mechanism of acidic cupric chloride etching, regeneration and recovery is complex, and the current monitoring strategies can have difficulty controlling the interlocking chemical equilibria. A complimentary tool, thin-film UV-Vis spectroscopy, can be utilized to improve the current monitoring strategies, as UV-Vis is capable of identifying and predicting etching behavior that the current standard methodologies have difficulty predicting. Furthermore, as a chemically-sensitive probe, UV-Vis can investigate the complex changes to the chemical equilibrium and speciation of the etch bath, and can contribute overall to significant improvements in the control of the copper etching system in order to meet the demands of next-level design strategies.
Date: August 2017
Creator: Lambert, Alexander S
Partner: UNT Libraries

Attachment, Coping, and Psychiatric Symptoms among Military Veterans and Active Duty Personnel: A Path Analysis Study

Description: The purpose of this study was to examine the role of attachment processes and coping strategies in the development of psychiatric symptoms among military veterans and active duty personnel. Data were obtained from 268 male and female military veterans and active duty personnel. A path analysis was conducted to estimate the relationships between attachment processes, coping strategies, and psychiatric symptoms. Findings demonstrated that greater levels of attachment anxiety were related to increased levels of avoidant coping and psychiatric symptoms, while higher levels of attachment avoidance were related to avoidant coping and PTSD symptoms, as well as decreased levels of problem-focused coping. Alcohol use was associated with psychiatric symptoms. Avoidant coping, but not problem-focused coping, was associated with psychiatric symptoms and partially mediated the relationship between anxious attachment and psychiatric symptoms. Avoidant coping also fully or partially mediated the relationships of avoidant attachment to depression and PTSD symptoms. The findings of this study increase our knowledge of mechanisms that contribute to psychiatric symptoms among military populations, which in turn can guide treatment planning and interventions.
Date: December 2017
Creator: Romero, Daniel Hugo
Partner: UNT Libraries

Becoming Successful in Education: Beating the Odds, Despite a Background Entrenched in Poverty

Description: The purpose of this study was to investigate the impact of three relationships on academic achievement in mathematics in students of poverty. The three factors that were examined included: teacher-student relationships, parent-student relationships and peer- student relationships. The driving question for the research was as follows: Do external factors such as teacher-student relationships, parent-student relationships and peer-student relationships lead to academic success for students of poverty? The study employed a non-experimental, quantitative approach and utilized longitudinal data from a national database High School Longitudinal Study (HSLS) used a sample of 944 public and private high schools across the USA. A total 0f 28,240 were represented in the survey. Of these 28,240 students, 2641 were used in this study as identified by parental income below the poverty threshold. The outcome of the study indicated that there was little or no correlation between the three relationships and mathematics achievement (academic success). Correlations between the dependent variable (math achievement) and the independent variables even though some were statistically significant their weights had no concrete significance. The study recommends that several initiatives can be instated in schools to support and enhance academic achievement in students of poverty.
Date: May 2017
Creator: Thompson, Pauline A
Partner: UNT Libraries

Brain Computer Interface (BCI) Applications: Privacy Threats and Countermeasures

Description: In recent years, brain computer interfaces (BCIs) have gained popularity in non-medical domains such as the gaming, entertainment, personal health, and marketing industries. A growing number of companies offer various inexpensive consumer grade BCIs and some of these companies have recently introduced the concept of BCI "App stores" in order to facilitate the expansion of BCI applications and provide software development kits (SDKs) for other developers to create new applications for their devices. The BCI applications access to users' unique brainwave signals, which consequently allows them to make inferences about users' thoughts and mental processes. Since there are no specific standards that govern the development of BCI applications, its users are at the risk of privacy breaches. In this work, we perform first comprehensive analysis of BCI App stores including software development kits (SDKs), application programming interfaces (APIs), and BCI applications w.r.t privacy issues. The goal is to understand the way brainwave signals are handled by BCI applications and what threats to the privacy of users exist. Our findings show that most applications have unrestricted access to users' brainwave signals and can easily extract private information about their users without them even noticing. We discuss potential privacy threats posed by current practices used in BCI App stores and then describe some countermeasures that could be used to mitigate the privacy threats. Also, develop a prototype which gives the BCI app users a choice to restrict their brain signal dynamically.
Date: May 2017
Creator: Bhalotiya, Anuj Arun
Partner: UNT Libraries

Case Studies to Learn Human Mapping Strategies in a Variety of Coarse-Grained Reconfigurable Architectures

Description: Computer hardware and algorithm design have seen significant progress over the years. It is also seen that there are several domains in which humans are more efficient than computers. For example in image recognition, image tagging, natural language understanding and processing, humans often find complicated algorithms quite easy to grasp. This thesis presents the different case studies to learn human mapping strategy to solve the mapping problem in the area of coarse-grained reconfigurable architectures (CGRAs). To achieve optimum level performance and consume less energy in CGRAs, place and route problem has always been a major concern. Making use of human characteristics can be helpful in problems as such, through pattern recognition and experience. Therefore to conduct the case studies a computer mapping game called UNTANGLED was analyzed as a medium to convey insights of human mapping strategies in a variety of architectures. The purpose of this research was to learn from humans so that we can come up with better algorithms to outperform the existing algorithms. We observed how human strategies vary as we present them with different architectures, different architectures with constraints, different visualization as well as how the quality of solution changes with experience. In this work all the case studies obtained from exploiting human strategies provide useful feedback that can improve upon existing algorithms. These insights can be adapted to find the best architectural solution for a particular domain and for future research directions for mapping onto mesh-and- stripe based CGRAs.
Date: May 2017
Creator: Malla, Tika Kumari
Partner: UNT Libraries

Catalytic Properties and Mechanical Behavior of Metallic Glass Powders

Description: Lack of crystalline order and microstructural features such as grain/grain-boundary in metallic glasses results in a suite of remarkable attributes including very high strength, close to theoretical elasticity, high corrosion and wear resistance, and soft magnetic properties. By altering the morphology and tuning of composition, MGs may be transformed into high-performance catalytic materials. In this study, the catalytic properties of metallic glass powders were demonstrated in dissociating toxic organic chemicals such as AZO dye. BMG powders showed superior performance compared to state of the art crystalline iron because of their high catalytic activity, durability, and reusability. To enhance the catalytic properties, high energy mechanical milling was performed to increase the surface area and defect density. Iron-based bulk metallic glass (BMG) of composition Fe48Cr15Mo14Y2C15B6 was used because of its low cost and ability to make large surface area by high energy ball milling. AZO dye was degraded in less than 20 minutes for the 9 hours milled Fe-BMG. However, subsequent increase in ball milling time resulted in devitrification and loss of catalytic activity as measured using UV-Visible spectroscopy. Aluminum-based bulk metallic glass (Al-BMG) powder of composition Al82Fe3Ni8Y7 was synthesized by arc-melting the constituent elements followed by gas-atomization. The particle size and morphology were similar to Fe-BMG with a fully amorphous structure. A small percentage of transition metal constituents (Fe and Ni) in a mostly aluminum alloy showed high catalytic activity, with no toxic by-products and no change in surface characteristics. Al-alloy particles, being light-weight, were easily dispersed in aqueous medium and accelerated the redox reactions. The mechanism of dye dissociation was studied using Raman and Infrared (IR) spectroscopy. Breaking of -C-H- and - C-N- bonds of AZO dye was found to be the primary mechanism. Mechanical behavior of individual BMG particles was evaluated by in situ pico-indentation in a scanning electron ...
Date: May 2017
Creator: Garrison, Seth Thomas
Partner: UNT Libraries

Cattle Capitalists: The XIT Empire in Texas and Montana

Description: The Texas Constitution of 1876 set aside three million acres of Texas public land in exchange for construction of the monumental red granite Capitol that continues to house Texas state government today. The Capitol project and the land went to an Illinois syndicate led by men influential in business and politics. Austin's statehouse is a recognizable symbol of Texas around the world. So too, the massive Panhandle tract given in exchange -- what became the "fabulous" XIT Ranch -- has come to, for many, symbolize Texas and its role in the nineteenth century cattle boom. After finding sales prospects for the land, known as the Capitol Reservation, weak at the time, backed by British capital, the Illinois group, often called the Capitol Syndicate, turned their efforts to cattle ranching to satisfy investors until demand for the land increased. The operation included a satellite ranch in Montana to which two-year-old steers from Texas were sent for fattening, often "over the trail" on a route increasingly blocked by people and settlement. Rather than a study focused on ranching operations on the ground -- the roundups, the cattle drives, the cowboys -- this instead uncovers the business and political side of the Syndicate's ranching operation, headquartered in Chicago. The operation of the XIT Ranch looked more like other Gilded Age businesses employing armies of clerks, bookkeepers, and secretaries instead of how great western ranches have been portrayed for years in popular literature and media. The XIT Ranch existed from 1885 to 1912, yet from Texas to Montana the operation left a deep imprint on community culture and historical memory.
Date: December 2017
Creator: Miller, Michael M
Partner: UNT Libraries

Characteristics of Mothers among Counselor Education Faculty

Description: Pre-tenured faculty in higher education and as well as mothers have reportedly struggled with low wellness levels, high demands, little social support, and an imbalance of work and home life. Mothers in higher education and in counselor education have reported struggling with work-life balance, high scholarly productivity, and long hours as well as the emotional and physical energy demands of working with counselors-in-training. A search of the professional literature revealed a paucity of quantitative research regarding demographic characteristics, wellness levels, and social support levels of mothers among counselor education faculty (MCEs). Participants for this study were faculties of counselor education programs recruited from the Holland List of Counseling Programs and from the Council for Accreditation of Counseling and Related Educational Programs online directory. A total of 180 MCEs participated (aged 29-63, with mean age 40.6 years; 83% Caucasian, 8% other, 5% African American, 3% Hispanic, <1% Asian). Results showed that faculty rank did not account for a significant difference among wellness scores of MCEs and that reported social support, tenure or non-tenure track, number of children in the care of MCEs, number of children under age 8, number of publications, and teaching workload accounted for 14% of the variance in wellness levels of MCEs. Specifically, reported higher teaching workload (β = -.194, rs2 = .35, p = .012) and higher social support (β = -.258, rs2 = .36, p = <.001) were found to be significant predictors of lower wellness levels among MCEs, both with small effects. Based on these results, MCEs may benefit from advocating that their departments and universities adapt to their unique needs to improve their levels of wellness and social support through mentoring, which, in turn, may result in not only their own increased productivity but also their students' increased wellness levels.
Date: May 2017
Creator: Jimenez, Kyrstin Anne
Partner: UNT Libraries

Children with Emotional and Behavioral Disorders in Saudi Arabia: A Preliminary Prevalence Screening

Description: Education in Saudi Arabia, including the education of children with special needs, is developing rapidly. However, children with emotional and behavioral disorders are neither consistently identified nor adequately served in Saudi Arabia although they are recognized as a distinct category of children who require special education services. The goal of this study was to examine the prevalence of emotional and behavioral disorders among children in Saudi Arabia to assess the need for intervention services to help those children reach their potential. The current research identified the types of behaviors that are most evident in the study sample. Also, the relationship between demographics and emotional and behavioral disorders is studied to identify possible predictors of disruptive forms of behavior. Parents of children aged 4-17 years in Saudi Arabia were surveyed using the Strengths and Difficulties Questionnaire. The findings of the study suggest that children with emotional and behavioral disorders in Saudi Arabia may account for 20% of the population of children between the ages of 4 and 17. The findings also revealed that over 20% of children in Saudi Arabia have difficulties in peer relationship and lack the necessary prosocial behaviors. The parent reporting, child gender, child education type, the geographical region, the father's education level, and the family's socioeconomic status were found to be statistically significant predictors of children's difficulties. However, these predictors were only able to explain a small portion of the difficulty scores.
Date: December 2017
Creator: Maajeeny, Hassan
Partner: UNT Libraries

Civil Liberties and National Unity: Reaction to the Sedition Act in the Southern States, 1798

Description: The traditional narrative of political party development in the United States of America during the latter half of the 1790s ascribes the decline in popularity of the Federalist Party in the Election of 1800 to that party's passage of controversial legislation, specifically the Sedition Act of 1798, prior to the election. Between the passage of the Sedition Act and the Election of 1800, however, the midterm elections of 1798-1799 transpired and resulted in a significant increase in Federalist popularity in four states – North Carolina, South Carolina, Georgia, and Virginia. This study seeks to ascertain why these four states increased their support for the Federalist Party in 1798-1799, despite the passage of the Sedition Act by the Federalist Party. By examining newspapers and election results, this study analyzes the reaction of these four states to the passage of the Sedition Act and finds that generally, these states did not react strongly against the Sedition Act in the immediate aftermath of its passage. Instead, all four states urged national unity and emphasized the need to support the national government because the United States faced the threat of war with France. This study employs a state-by-state formula to determine each state's individual reaction to the Sedition Act and the Quasi-War, finding that ultimately, the Sedition Act did not have as significant of an impact in these states as the popular narrative holds.
Date: December 2017
Creator: Robinson, Sarah Elizabeth
Partner: UNT Libraries

Collective Security and Coalition: British Grand Strategy, 1783-1797

Description: On 1 February 1793, the National Convention of Revolutionary France declared war on Great Britain and the Netherlands, expanding the list of France's enemies in the War of the First Coalition. Although British Prime Minister William Pitt the Younger had predicted fifteen years of peace one year earlier, the French declaration of war initiated nearly a quarter century of war between Britain and France with only a brief respite during the Peace of Amiens. Britain entered the war amid both a nadir in British diplomacy and internal political divisions over the direction of British foreign policy. After becoming prime minister in 1783 in the aftermath of the War of American Independence, Pitt pursued financial and naval reform to recover British strength and cautious interventionism to end Britain's diplomatic isolation in Europe. He hoped to create a collective security system based on the principles of the territorial status quo, trade agreements, neutral rights, and resolution of diplomatic disputes through mediation - armed mediation if necessary. While his domestic measures largely met with success, Pitt's foreign policy suffered from a paucity of like-minded allies, contradictions between traditional hostility to France and emergent opposition to Russian expansion, Britain's limited ability to project power on the continent, and the even more limited will of Parliament to support such interventionism. Nevertheless, Pitt's collective security goal continued to shape British strategy in the War of the First Coalition, and the same challenges continued to plague the British war effort. This led to failure in the war and left the British fighting on alone after the Treaty of Campo Formio secured peace between France and its last continental foe, Austria, on 18 October 1797.
Date: May 2017
Creator: Jarrett, Nathaniel W
Partner: UNT Libraries

Community College Student Retention and Completion based on Financial Expenditures and Hispanic-Serving Status

Description: Despite declining community college funding being allocated increasingly on the basis of student success, U.S. community college student retention and completion rates over the past decade have either remained steady or decreased, especially for Latino students. Using descriptive statistics and multiple regression models with secondary data procured from the Integrated Postsecondary Education Data System (IPEDS), I analyzed student success rates—full time student retention and completion rates—based on community college financial allocations and Hispanic-serving institution (HSI) status. To equitably analyze community colleges in the sample (n = 909), I separated them into four groups based on institutional size as defined by the Carnegie Classification. Descriptive results indicated that instructional divisions spent an average of 43% of the college's total allocated budget—often more than three times the allocated budget of any other division. Regression results indicated that instructional expenditures had the most consistent impact on student success regardless of college size and that scholarship expenditures and academic support expenditures generally had a negative impact on student retention and completion rates. Regarding Latino student success in particular, findings indicated that the manner in which colleges allocated their funds impacted only small and medium-sized community colleges. Of the nine different types of institutional expenditures, only student services expenditures and public services expenditures had a statistically significant impact on Latino student success. Additionally regression analysis indicated that community college HSI status did not have a large impact on overall full-time student retention and completion rates but did have a significant impact on full-time Hispanic student retention and completion rates for all institution sizes. Findings of this study confirmed that HSI status does impact Latino student success in public community colleges. This finding is consistent with prior studies on the positive impact of instructional expenditures on student success rates. Further research on the specific elements within ...
Date: May 2017
Creator: DaSilva, Jose E.
Partner: UNT Libraries

Corporeal Judgment in Shakespeare's Plays

Description: In this dissertation, I examine the complex role that the body played in early modern constructions of judgment. Moving away from an overreliance on anti-theatrical texts as the authority on the body in Shakespeare's plays, my project intervenes in the field Shakespearean studies by widening the lens through which scholars view the body's role in the early modern theater. Through readings of four plays—Richard II, Hamlet, King Lear, and The Winter's Tale—I demonstrate that Shakespeare uses a wide range of ideas about the human body from religious, philosophical, medical, and cultural spheres of thought to challenge Puritan accusations that the public theater audience is incapable of rational judgment. The first chapter outlines the parameters of the project. In Chapter 2, I argue that Richard II draws parallels between the theatrical community and the community created through the sacramental experiences of baptism and communion to show that bodies play a crucial role in establishing common experience and providing an avenue for judgment. In Chapter 3, I argue that Shakespeare establishes correspondences between bodily and social collaboration to show how both are needed for the memory-making project of the theater. In the next chapter, I show how Shakespeare appropriates what early moderns perceived of as the natural vulnerability in English bodies to suggest the passionate responses associated with impressionability can actually be sources of productive judgment and self-edification. I argue the storm models this passionate judgment, providing a guide for audience behavior. In Chapter 5, I argue that the memories created by and within the women in The Winter's Tale evoke the tradition of housewifery and emphasize the female role in preservation. Female characters stand in for hidden female contributors to the theater and expose societal blindness to women's work. Through each of these chapters, I argue that Shakespeare's plays emphasize the ...
Date: December 2017
Creator: Cephus, Heidi Nicole
Partner: UNT Libraries

Delivery of CRISPR/Cas9 into Blood Cells of Zebrafish: Potential for Genome Editing in Somatic Cells

Description: Factor VIII is a clotting factor found on the intrinsic side of the coagulation cascade. A mutation in the factor VIII gene causes the disease Hemophilia A, for which there is no cure. The most common treatment is administration of recombinant factor VIII. However, this can cause an immune response that renders the treatment ineffective in certain hemophilia patients. For this reason a new treatment, or cure, needs to be developed. Gene editing is one solution to correcting the factor VIII mutation. CRISPR/Cas9 mediated gene editing introduces a double stranded break in the genomic DNA. Where this break occurs repair mechanisms cause insertions and deletions, or if a template oligonucleotide can be provided point mutations could be introduced or corrected. However, to accomplish this goal for editing factor VIII mutations, a way to deliver the components of CRISPR/Cas9 into somatic cells is needed. In this study, I confirmed that the CRISPR/Cas9 system was able to create a mutation in the factor VIII gene in zebrafish. I also showed that the components of CRISPR/Cas9 could be piggybacked by vivo morpholino into a variety of blood cells. This study also confirmed that the vivo morpholino did not interfere with the gRNA binding to the DNA, or Cas9 protein inducing the double stranded break.
Date: August 2017
Creator: Schneider, Sara Jane
Partner: UNT Libraries

Design Considerations and Implementation of Portable Mass Spectrometers for Environmental Applications

Description: Portable mass spectrometers provide a unique opportunity to obtain in situ measurements. This minimizes need for sample collection or in laboratory analysis. Membrane Inlet Mass Spectrometry (MIMS) utilizing a semi permeable membrane for selective rapid introduction for analysis. Polydimethylsiloxane membranes have been proven to be robust in selecting for aromatic chemistries. Advances in front end design have allowed for increased sensitivity, rapid sample analysis, and on line measurements. Applications of the membrane inlet technique have been applied to environmental detection of clandestine drug chemistries and pollutants. Emplacement of a mass spectrometer unit in a vehicle has allowed for large areas to be mapped, obtaining a rapid snapshot of the various concentrations and types of environmental pollutants present. Further refinements and miniaturization have allowed for a backpackable system for analysis in remote harsh environments. Inclusion of atmospheric dispersion modeling has yielded an analytical method of approximating upwind source locations, which has law enforcement, military, and environmental applications. The atmospheric dispersion theories have further been applied to an earth based separation, whereby chemical properties are used to approximate atmospheric mobility, and chemistries are further identified has a portable mass spectrometer is traversed closer to a point source.
Date: May 2017
Creator: Mach, Phillip Michael
Partner: UNT Libraries

Design, Construction, and Application of an Electrostatic Quadrupole Doublet for Heavy Ion Nuclear Microprobe Research

Description: A nuclear microprobe, typically consisting of 2 - 4 quadrupole magnetic lenses and apertures serving as objective and a collimating divergence slits, focuses MeV ions to approximately 1 x 1 μm for modification and analysis of materials. Although far less utilized, electrostatic quadrupole fields similarly afford strong focusing of ions and have the added benefit of doing so independent of ion mass. Instead, electrostatic quadrupole focusing exhibits energy dependence on focusing ions. A heavy ion microprobe could extend the spatial resolution of conventional microprobe techniques to masses untenable by quadrupole magnetic fields. An electrostatic quadrupole doublet focusing system has been designed and constructed using several non-conventional methods and materials for a wide range of microprobe applications. The system was modeled using the software package "Propagate Rays and Aberrations by Matrices" which quantifies system specific parameters such as demagnification and intrinsic aberrations. Direct experimental verification was obtained for several of the parameters associated with the system. Details of the project and with specific applications of the system are presented.
Date: December 2017
Creator: Manuel, Jack Elliot
Partner: UNT Libraries

Design of Bioinspired Conductive Smart Textile

Description: Electrically conductive fabrics are one of the major components of smart textile that attracts a lot of attention by the energy, medical, sports and military industry. The principal contributors to the conductivity of the smart textiles are the intrinsic properties of the fiber, functionalization by the addition of conductive particles and the architecture of fibers. In this study, intrinsic properties of non-woven carbon fabric derived from a novel linear lignin, poly-(caffeyl alcohol) (PCFA) discovered in the seeds of the vanilla orchid (Vanilla planifolia) was investigated. In contrast to all known lignins which comprise of polyaromatic networks, the PCFA lignin is a linear polymer. The non-woven fabric was prepared using electrospinning technique, which follows by stabilization and carbonization steps. Results from Raman spectroscopy indicate higher graphitic structure for PCFA carbon as compared to the Kraft lignin, as seen from G/D ratios of 1.92 vs 1.15 which was supported by a high percentage of graphitic (C-C) bond observed from X-ray photoelectron spectroscopy (XPS). Moreover, from the XRD and TEM a larger crystal size (Lc=12.2 nm) for the PCFA fiber was obtained which correlates to the higher modulus and conductivity of the fiber. These plant-sourced carbon fabrics have a valuable impact on zero carbon footprint materials. In order to improve the strength and flexibility of the non-woven carbon fabric, lignin was blended with the synthetic polymer Poly acrylonitrile (PAN) in different concertation, resulting in electrical conductivity up to (7.7 S/cm) on blend composition which is enough for sensing and EMI shielding applications. Next, the design of experiments approach was used to identify the contribution of the carbonization parameters on the conductivity of the fabrics and architecture of the fibers, results show carbonization temperature as the major contributing factor to the conductivity of non-woven fabric. Finally, a manufacturing procedure was develop inspired by the ...
Date: August 2017
Creator: Rizvi, Syed Hussain Raza
Partner: UNT Libraries

Design, Synthesis and Optoelectronic Properties of Monovalent Coinage Metal-Based Functional Materials toward Potential Lighting, Display and Energy-Harvesting Devices

Description: Groundbreaking progress in molecule-based optoelectronic devices for lighting, display and energy-harvesting technologies demands highly efficient and easily processable functional materials with tunable properties governed by their molecular/supramolecular structure variations. To date, functional coordination compounds whose function is governed by non-covalent weak forces (e.g., metallophilic, dπ-acid/dπ-base stacking, halogen/halogen and/or d/π interactions) remain limited. This is unlike the situation for metal-free organic semiconductors, as most metal complexes incorporated in optoelectronic devices have their function determined by the properties of the monomeric molecular unit (e.g., Ir(III)-phenylpyridine complexes in organic light-emitting diodes (OLEDs) and Ru(II)-polypyridyl complexes in dye-sensitized solar cells (DSSCs)). This dissertation represents comprehensive results of both experimental and theoretical studies, descriptions of synthetic methods and possible application allied to monovalent coinage metal-based functional materials. The main emphasis is given to the design and synthesis of functional materials with preset material properties such as light-emitting materials, light-harvesting materials and conducting materials. In terms of advances in fundamental scientific phenomena, the major highlight of the work in this dissertation is the discovery of closed-shell polar-covalent metal-metal bonds manifested by ligand-unassisted d10-d10 covalent bonds between Cu(I) and Au(I) coinage metals in the ground electronic state (~2.87 Å; ~45 kcal/mol). Moreover, this dissertation also reports pairwise intermolecular aurophilic interactions of 3.066 Å for an Au(I) complex, representing the shortest ever reported pairwise intermolecular aurophilic distances among all coinage metal(I) cyclic trimetallic complexes to date; crystals of this complex also exhibit gigantic luminescence thermochromism of 10,200 cm-1 (violet to red). From applications prospective, the work herein presents monovalent coinage metal-based functional optoelectronic materials such as heterobimetallic complexes with near-unity photoluminescence quantum yield, metallic or semiconducting integrated donor-acceptor stacks and a new class of Au(III)-based black absorbers with cooperative intermolecular iodophilic (I…I) interactions that sensitize the harvesting of all UV, all visible, and a broad spectrum of near-IR ...
Date: August 2017
Creator: Ghimire, Mukunda Mani
Partner: UNT Libraries

Determinants of Corporate Governance Choices: Evidence from Listed Foreign Firms on U.S. Stock Exchanges

Description: This study analyzes corporate governance practices of foreign (non-U.S.) issuers listed on the New York Stock Exchange (NYSE) and Nasdaq. Specifically, I examine the extent to which these foreign issuers voluntarily comply with U.S. stock exchange corporate governance requirements applicable to domestic issuers. My sample consists of 201 foreign companies primarily domiciled in Brazil, China, Israel, and the United Kingdom. I find that 151 (75 per cent) of the sample firms do not elect to comply with any of the U.S. corporate governance requirements. Logistic regression analysis generally supports the hypotheses that conformance with U.S. GAAP and percentage of managerial ownership are positively associated, and that percentage ownership by major shareholders is negatively associated with foreign firms electing to comply with U.S. corporate governance rules. This evidence is relevant for regulators and investors.
Date: May 2017
Creator: Attachot, Weerapat
Partner: UNT Libraries