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 Decade: 2010-2019
 Collection: UNT Theses and Dissertations
Determinants of Mental Health Problems Among College Students

Determinants of Mental Health Problems Among College Students

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Date: December 2010
Creator: Mirbaha-Hashemi, Fariba
Description: Many college students have reported struggling with mental health problems while dealing with challenging demands of college. The initial theoretical framework for this research was Pearlin's stress process model (SPM). Building on the SPM, the three additional mediating variables of perceived control, meaninglessness, and financial worries were added to create a composite model for the research. Mental health outcomes in the model were measured by a comprehensive range of factors, which included: psychological distress, suicide, substance abuse, and anger. Data were collected from a non-probability convenience sample of 463 undergraduate students attending a large state supported university in the southwestern region of the United States. Among the social status variables measured, being married, female, and white were significant predictors of poor mental health in the sampled college students. Poor self-image, feeling of meaninglessness, and worrying about current and future finances were significant mediating variables. Poor mental health could make individuals overwhelmed and discouraged. This is a formula for failure in college. The results of this study contribute to a better understanding of the correlates of mental health problems among college students. A greater understanding means that families and college administrations will have better ideas about how to intervene to reduce ...
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Development of Indium Oxide Nanowires as Efficient Gas Sensors

Development of Indium Oxide Nanowires as Efficient Gas Sensors

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Date: December 2011
Creator: Gali, Pradeep
Description: Crystalline indium oxide nanowires were synthesized following optimization of growth parameters. Oxygen vacancies were found to impact the optical and electronic properties of the as-grown nanowires. Photoluminescence measurements showed a strong U.V emission peak at 3.18 eV and defect peaks in the visible region at 2.85 eV, 2.66 eV and 2.5 eV. The defect peaks are attributed to neutral and charged states of oxygen vacancies. Post-growth annealing in oxygen environment and passivation with sulphur are shown to be effective in reducing the intensity of the defect induced emission. The as-grown nanowires connected in an FET type of configuration shows n-type conductivity. A single indium oxide nanowire with ohmic contacts was found to be sensitive to gas molecules adsorbed on its surface.
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Development of Silicon Nanowire Field Effect Transistors

Development of Silicon Nanowire Field Effect Transistors

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Date: December 2011
Creator: Nukala, Prathyusha
Description: An economically reliable technique for the synthesis of silicon nanowire was developed using silicon chloride as source material. The 30-40 micron long nanowires were found to have diameters ranging from 40 – 100 nm. An amorphous oxide shell covered the nanowires, post-growth. Raman spectroscopy confirmed the composition of the shell to be silicon-dioxide. Photoluminescence measurements of the as-grown nanowires showed green emission, attributed to the presence of the oxide shell. Etching of the oxide shell was found to decrease the intensity of green emission. n-type doping of the silicon nanowires was achieved using antimony as the dopant. The maximum dopant concentration was achieved by post-growth diffusion. Intrinsic nanowire parameters were determined by implementation of the as-grown and antimony doped silicon nanowires in field effect transistor configuration.
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Device Engineering for Enhanced Efficiency from Platinum(II) Phosphorescent OLEDs

Device Engineering for Enhanced Efficiency from Platinum(II) Phosphorescent OLEDs

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Date: August 2010
Creator: Li, Minghang
Description: Phosphorescent organic light emitting diodes (PHOLEDs) based on efficient electrophosphorescent dopant, platinum(II)-pyridyltriazolate complex, bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II) (Pt(ptp)2) have been studied and improved with respect to power efficiency, external efficiency, chromacity and efficiency roll-off. By studying the electrical and optical behavior of the doped devices and functionality of the various constituent layers, devices with a maximum EQE of 20.8±0.2 % and power efficiency of 45.1±0.9 lm/W (77lm/W with luminaries) have been engineered. This improvement compares to devices whose emission initially could only be detected by a photomultiplier tube in a darkened environment. These devices consisted of a 65 % bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II) (Pt(ptp)2) doped into 4,4'-bis(carbazol-9-yl)triphenylamine (CBP) an EML layer, a hole transporting layer/electron blocker of 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), an electron transport layer of 1,3,5-tris(phenyl-2-benzimidazolyl)-benzene (TPBI), and a LiF/Al cathode. These devices show the acceptable range for warm white light quadrants and qualify to be called "warm white" even w/o adding another emissive layer. Dual EML devices composed of neat Pt(ptp)2 films emitting orange and CBP: Pt(ptp)2 film emitting blue-green produced a color rendering index (CRI) of 59 and color coordinates (CIE) of (0.47,0.49) at 1000Cd/m² with power efficiency of 12.6±0.2 lm/W and EQE of 10.8±0.2 %. Devices with two blue fluorescent emission layers as singlet ...
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Dolores Dyer: Women's Basketball and the American Dream

Dolores Dyer: Women's Basketball and the American Dream

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Date: December 2012
Creator: Roberts, Jackie
Description: Dolores Dyer played from 1952-1953 for the Texas Cowgirls, a barnstorming women's basketball team that provided a form of entertainment popular throughout the United States in that era. The story of Dyer's life demonstrates how a woman could attempt to achieve the American dream—a major theme in American history—through success in athletic competition. Dyer's participation with the Texas Cowgirls also provides a look into the circumstances that limited women's participation in professional sport during the mid-twentieth century. Women's sports studies, although some are very thorough, have gaps in the research, and women's barnstorming basketball is one of the areas often overlooked. In light of this gap, this thesis relies on a variety of sources, including primary documents from unpublished collections, archived materials, and original oral histories from several members of the Texas Cowgirls team. This thesis contains analysis of the socioeconomic factors that influenced Dolores Dyer's maturation into a professional basketball player, examines what the American dream meant to her, and evaluates the extent to which she achieved it. Overall, it constructs a social history that can serve as a foundational source for further study of women in sports during the twentieth century.
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Dream of a Thousand Keys: A Concerto for Piano and Orchestra

Dream of a Thousand Keys: A Concerto for Piano and Orchestra

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Date: May 2011
Creator: Choi, Da Jeong
Description: Dream of a Thousand Keys is a concerto for piano and orchestra, which consists of four movements presenting multiple dimensional meanings as suggested by the word "key." I trace the derivation of Korean traditional rhythmic cycles and numerical sequences, such as the Fibonacci series, that are used throughout the work, and explore the significant role of space between the soloist and piano that are emphasized in a theatrical aspect of the composition. The essay addresses the question of musical contrasts, similarities, and metamorphosis. Lastly, I cover terms and concepts of significant 21st-century compositional techniques that come into play in the analysis of this work.
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A Driver, Vehicle and Road Safety System Using Smartphones

A Driver, Vehicle and Road Safety System Using Smartphones

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Date: May 2012
Creator: Gozick, Brandon
Description: As vehicle manufacturers continue to increase their emphasis on safety with advanced driver assistance systems (ADAS), I propose a ubiquitous device that is able to analyze and advise on safety conditions. Mobile smartphones are increasing in popularity among younger generations with an estimated 64% of 25-34 year olds already using one in their daily lives. with over 10 million car accidents reported in the United States each year, car manufacturers have shifted their focus of a passive approach (airbags) to more active by adding features associated with ADAS (lane departure warnings). However, vehicles manufactured with these sensors are not economically priced while older vehicles might only have passive safety features. Given its accessibility and portability, I target a mobile smartphone as a device to compliment ADAS that can bring a driver assist to any vehicle without regards for any on-vehicle communication system requirements. I use the 3-axis accelerometer of multiple Android based smartphone to record and analyze various safety factors which can influence a driver while operating a vehicle. These influences with respect to the driver, vehicle and road are lane change maneuvers, vehicular comfort and road conditions. Each factor could potentially be hazardous to the health of the driver, ...
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Economic Mobility into the Planter Class in Texas, 1846-1860

Economic Mobility into the Planter Class in Texas, 1846-1860

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Date: December 2011
Creator: Nelson, Robert Nicholas
Description: This study examines upward economic mobility into the planter class in Texas during the antebellum statehood period, 1846-1860. Using quantitative methods to analyze data from census and tax records, this study addresses several questions regarding the property owning experience of Texas planters. Did any of the 1860 planters, men or women, rise to that status from another class? If so, how many rose from small slaveholder or small planter origins, and how many advanced from plain folk origins? In what ways did the amount and nature of wealth of these individuals change in the period studied? In what ways do these findings provide insights into the debate over planter dominance versus ‘plain folk’ inclusive herrenvolk democracy and the relationship between the planters and the other classes? Did the experiences of female planters differ from that of male planters? Did female planter experiences in Texas differ from female planters in other parts of the Old South? The results of these questions demonstrate that economic class mobility into the richest class was significant but limited and that women’s experiences were closely tied to those of male kin.
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Effect of Retting on Surface Chemistry and Mechanical Performance Interactions in Natural Fibers for High Performance Polymer Composites

Effect of Retting on Surface Chemistry and Mechanical Performance Interactions in Natural Fibers for High Performance Polymer Composites

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Date: May 2013
Creator: Ramesh, Dinesh
Description: Sustainability through replacement of non-renewable fibers with renewable fibers is an ecological need. Impact of transportation costs from South-east Asia on the life cycle analysis of the composite is detrimental. Kenaf is an easily grown crop in America. Farm based processing involves placing the harvested crop in rivers and ponds, where retting of the fibers from the plant (separation into fibers) can take 2 weeks or more. The objective of this thesis is to analyze industrially viable processes for generating fibers and examine their synergistic impact on mechanical performance, surface topography and chemistry for functional composites. Comparison has been made with commercial and conventional retting process, including alkali retting, enzymatic retting, retting in river and pond water (retting occurs by natural microbial population) with controlled microbial retting. The resulting kenaf fibers were characterized by dynamic mechanical analysis (DMA), Raman spectroscopy (FT-Raman), Fourier transform infrared spectroscopy (FT-IR), polarized optical microscopy (POM), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) optical fluorescence microscopy, atomic force microscopy (AFM) and carbohydrate analysis. DMA results showed that pectinase and microbe treated fibers have superior viscoelastic properties compared to alkali retting. XPS, Raman, FT-IR and biochemical analysis indicated that the controlled microbial and pectinase retting was ...
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Electrochemically Deposited Metal Alloy-silicate Nanocomposite Corrosion Resistant Materials

Electrochemically Deposited Metal Alloy-silicate Nanocomposite Corrosion Resistant Materials

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Date: May 2013
Creator: Conrad, Heidi Ann
Description: Zinc-nickel ?-phase silicate and copper-nickel silicate corrosion resistant coatings have been prepared via electrochemical methods to improve currently available corrosion resistant materials in the oil and gas industry. A layered silicate, montmorillonite, has been incorporated into the coatings for increased corrosion protection. For the zinc nickel silicate coatings, optimal plating conditions were determined to be a working pH range of 9.3 -9.5 with a borate based electrolyte solution, resulting in more uniform deposits and better corrosion protection of the basis metal as compared to acidic conditions. Quality, strongly adhering deposits were obtained quickly with strong, even overall coverage of the metal substrate. The corrosion current of the zinc-nickel-silicate coating is Icorr = 3.33E-6 for a borate based bath as compared to a zinc-nickel bath without silicate incorporation (Icorr = 3.52E-5). Step potential and direct potential methods were examined, showing a morphological advantage to step potential deposition. The effect of borate addition was examined in relation to zinc, nickel and zinc-nickel alloy deposition. Borate was found to affect the onset of hydrogen evolution and was examined for absorption onto the electrode surface. For copper-nickel silicate coatings, optimal conditions were determined to be a citrate based electrolytic bath, with pH = 6. ...
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