UNT Theses and Dissertations - 41 Matching Results

Search Results

Note: All results matching your query require you to be a member of the UNT Community (you must be on campus or login with university credentials for access).

The Academic Steroid: Nonmedical Use of Prescription Stimulants at a North Texas University

Description: The goal of this study was to determine the extent, motivations, and justifications of nonmedical prescription stimulant use among the population at a large public university in the North Texas region. Participants consisted of 526 undergraduate students enrolled at the studied university during the spring and summer 2014 semesters. The findings of the study suggest that the nonmedical use by students was higher than the findings in much of the current literature, but was within the parameters established in the literature. The primary motivation for nonmedical use was academic in nature and was justified by moderation of nonmedical use to strategic academic times.
Date: December 2014
Creator: Pennington, Cody W.
Partner: UNT Libraries

Acute Effects of the Antibiotic Streptomycin on Neural Network Activity and Pharmacological Responses

Description: The purpose of this study is to find out that if antibiotic streptomycin decreases neuronal network activity or affects the pharmacological responses. The experiments in this study were conducted via MEA (multi-electrode array) technology which records neuronal activity from devices that have multiple small electrodes, serve as neural interfaces connecting neurons to electronic circuitry. The result of this study shows that streptomycin lowered the spike production of neuronal network, and also, sensitization was seen when neuronal network pre-exposed to streptomycin.
Date: December 2014
Creator: Zeng, Wei Rong
Partner: UNT Libraries

“The Angular Degrees of Freedom” and Other Stories

Description: The preface, " Performing Brain Surgery: The Problematic Nature of Endings in Short Fiction," deals with the many and varied difficulties short story writers encounter when attempting to craft endings. Beginning with Raymond Carver and Flannery O’Connor and moving to my own work, I discuss some of the obscure criteria used to designate a successful ending, as well as the more concrete idea of the ending as a unifying element. Five short stories make up the remainder of this thesis: "In-between Girls," "Crocodile Man," "Surprising Things, Sometimes Amusing," "Good Jewelry," and "The Angular Degrees of Freedom."
Date: December 2014
Creator: Feagin, Aprell McQueeney
Partner: UNT Libraries

Assessing Social Determinants of Severe Mental Illness in High-Risk Groups

Description: The primary objective of this research was to explore the impact of possible social factors on non-institutionalized adults 18 years of age or older residing in the United States who exhibited severe mental illness (SMI). A holistic sociological model was developed to explain SMI by incorporating elements of social learning theory, social disorganization theory, and gender socialization theory with social demographic factors. Based on the holistic sociological model, the following factors were investigated: demographic aspects of age, education, income and gender; gender socialization; influence of neighborhood area; social network influence based on communication and interaction among peers and family members; and socially deviant behaviors such as frequently smoking cigarettes, drinking alcohol and using drugs specifically marijuana. The impact of these factors on SMI was examined. A sample of 206 respondents drawn from National Survey on Drug Use and Health, 2003 was assessed. These respondents had answered all the questions related to SMI; social deviant behaviors; neighborhood environment; and communications among peers, family members and friends; and the other studied factors. Ordinary linear regression with interaction terms was employed as a statistical tool to assess the impact of social determinants on SMI. Being female, living a disorganized neighborhood, and frequent and high levels of smoking cigarettes and drinking alcohol had a significant influence on SMI. This reevaluation and reexamination of the role of gender socialization path, socially deviant behaviors like smoking and drinking, and community construction on SMI provided additional insights. This research is one of the first to develop a more holistic sociological model on SMI and explored the previously untested interactive relationships. The limitations of this study suggest the need to test a potential recursive research model and explore additional bi-directional associations.
Date: May 2014
Creator: Sun, Qi
Partner: UNT Libraries

Assessing Terrorist Cyber Threats: Engineering a Functional Construct

Description: Terrorist organizations and individuals make use of the Internet for supportive activities such as communication, recruiting, financing, training, and planning operations. However, little is known about the level of computer-based (“cyber”) threat such terrorist organizations and individuals pose. One step in facilitating the examination and assessment of the level of cyber threat posed by terrorist organizations and individuals is development of an assessment tool or methodology. This tool would guide intelligence collection efforts and would support and facilitate comparative assessment of the cyber threat posed by terrorist organizations and individuals through the provision of a consistent method of assessment across time, amongst organizations and individuals, and between analysts. This study leveraged the professional experience of experts to engineer a new functional construct – a structured analytical technique designed to assess the cyber threat posed by terrorist entities and individuals. The resultant instrument was a novel structured analytical construct that uses defined indicators of a terrorist organization/individual’s intent to carry out cyber attacks, and their capability to actually do so as measures of an organization/individual’s overall level of cyber threat.
Date: December 2014
Creator: Morgan, Deanne
Partner: UNT Libraries

Bank Capital, Efficient Market Hypothesis, and Bank Borrowing During the Financial Crisis of 2007 and 2008

Description: During the Great Recession of 2007 and 2008, liquidity and credit dried up, threatening the stability of financial institutions, particularly the banking firms. Traditional source of funds from the last resort, the Discount Window of the Federal Reserve System, failed to remedy the liquidity problem. To assuage the liquidity and credit problem, the Federal Reserve System established several emergency lending facilities and provided unprecedented amount of loans to the banking industry. Using a dataset published by Bloomberg LLP in the aftermaths of the financial crisis, which contains daily loan balances from the Fed, I conduct an event study to test whether financial markets are efficient in reflecting all public, anticipated and classified information in security prices. The most important contribution of this dissertation to the finance discipline and literature is the investigation and analysis of the Fed’s unprecedented loans to the banking industry during the Great Recession and the market reaction to it. The second major contribution of this study is the empirical test of strong form efficient market hypothesis, which has not been feasible due to legal data challenges. This dissertation has other contributions to the finance discipline and banking research. First, I develop an algorithm for measuring the amount of borrowing by banks. Second, I introduce a new “loan balance” ratio to traditional list of bank financial ratios. Third, I use event study methodologies to allow for cross-correlation, heteroscedasticity and event induced-variance change in studying US banks’ performance during the Great Recession.
Date: December 2014
Creator: Zia, Mujtaba
Partner: UNT Libraries

Business/it Alignment: the Impact of Incentive Plans on the Development of Shared Vision

Description: This study, utilizing Preston and Karahanna’s framework for shared vision development and Agency Theory, explores the impact of vision development factors and factors associated with incentive plans on shared vision and alignment. Results of the study confirm the strong relationship between shared vision and alignment, and indicate that having an effective management team is important with respect to developing and maintaining shared vision and alignment within the organization. Several vision development factors such as using the language of the business, participation on the top management team (TMT), and having knowledge of the business impact shared vision through their influence on teamwork. Also, results of this study suggest that participation on the TMT by the CIO/IT leader is more important than the individual’s position in the organizational hierarchy. In addition, attributes associated with incentive plans such as achievable and clear measures, measures linked to organizational goals, measures that align the interests of the individual with those of the organization, regular plan reviews, and using a balanced scorecard approach with respect to incentive plan design positively impact teamwork and shared vision. For practitioners, this highlights the importance of incentive plans as powerful tools that can be used to reinforce shared vision, effective teamwork, and alignment within the organization. Also, the CIO/IT leader needs to be knowledgeable of the business and must fill the role of both a technologist as well as an enterprise leader. This person must be an evangelist communicating the value and benefits of IT to the rest of the organization.
Date: December 2014
Creator: Johnson, Vess L.
Partner: UNT Libraries

El Cine De Terror Español Como Espejo De La Cultura Española

Description: This study traces the history and culture of Spain as seen through the lens of the nation´s production of horror cinema. Starting from the boom of Spanish horror film in the early 1960s, the thesis compares and contrasts the political and social aspects of Spanish society throughout three distinct eras of the 20th century: 1962 – 1975 (the boom of Spanish horror film through the Franco dictatorship), 1975 – 1999 (the transition to democracy through the end of the 20th century) and 2000 – present (the 21st century). Movies as diverse as Gritos en la noche (1962, Jesús Franco), ¿Quién puede matar a un niño? (1976, Narciso Ibáñez Serrador) and Angustia (1987, Bigas Luna) are framed by culturally-related anectodes as well as correlations to their respective social environments. Special attention has been paid to the production and release of each film, especially in regards to censorship during the Franco dictatorship. The results show that Spanish horror cinema has acted as a true mirror to culture, society and politics in its native country throughout the 20th century and that this trend will likely extend in to the future.
Date: May 2014
Creator: Donahue, Tyler
Partner: UNT Libraries

The Contribution of Mira Behn and Sarala Behn to Social and Environmental Transformation in the Indian State of Uttarakhand

Description: The influence of Mohandas K. Gandhi on social and environmental movements in post-colonial India has been widely acknowledged. Yet, the contributions of two European associates of Gandhi, Madeleine Slade and Catherine Mary Heilemann, better known in India as Mira Behn and Sarala Behn, have not received the due attention of the academic community. This dissertation is an examination of the philosophy and social activism of Mira Behn and Sarala Behn and their roles in the evolution of Gandhian philosophy of socioeconomic reconstruction and environmental conservation in the present Indian state of Uttarakhand. Instead of just being acolytes of Gandhi, I argue that these women developed ideas and practices that drew upon from an extensive intellectual terrain that cannot be limited to Gandhi’s work. I delineate the directions in which Gandhian thought and experiments in rural development work evolved through the lives, activism, and written contributions of these two women. Particularly, I examine their influence on social and environmental movements, such as the Chipko and the Anti-Tehri Dam movements, and their roles in promoting grassroots social development and environmental sustainability in the mountain communities of Uttarakhand. Mira Behn and Sarala Behn’s integrative philosophical worldviews present epistemological, sociopolitical, ethical, and metaphysical principles and practices that have local and global significance for understanding interfaith dialog, social justice, and environmental sustainability and thus constitute a useful contribution to the theory and practice of human emancipation in our times.
Date: May 2014
Creator: Mallik, Bidisha
Partner: UNT Libraries

Control and Automation of a Heat Shrink Tubing Process

Description: Heat shrink tubing is used to insulate wire conductors, protect wires, and to create cable entry seals in wire harnessing industries. Performing this sensitive process manually is time consuming, the results are strongly dependent on the operator’s expertise, and the process presents safety concerns. Alternatively, automating the process minimizes the operators’ direct interaction, decreases the production cost over the long term, and improves quantitative and qualitative production indicators dramatically. This thesis introduces the automation of a heat shrink tubing prototype machine that benefits the wire harnessing industry. The prototype consists of an instrumented heat chamber on a linear positioning system, and is fitted with two heat guns. The chamber design allows for the directing of hot air from the heat guns onto the wire harness uniformly through radially-distributed channels. The linear positioning system is designed to move the heat chamber along the wire harness as the proper shrinkage temperature level is reached. Heat exposure time as a major factor in the heat shrink tubing process can be governed by controlling the linear speed of the heat chamber. A control unit manages the actuator position continuously by measuring the chamber’s speed and temperature. A model-based design approach is followed to design and test the controller, and MATLAB/Simulink is used as the simulation environment. A programmable logic controller is selected as the controller implementation platform. The control unit performance is examined and its responses follow the simulation results with adequate accuracy.
Date: August 2014
Creator: Yousefi Darani, Shahrokh
Partner: UNT Libraries

Daily-collected Sleep Diaries Compared to Weekly-collected Sleep Diaries Via Actigraph Concordance

Description: Both sleep diaries and actigraphy have been recommended to assess sleep in research and clinical settings. Investigators have traditionally used sleep diaries that were completed daily by participants and collected weekly but have recently begun using sleep diaries that are both completed and collected daily. No research had previously assessed the agreement between daily-collected sleep diaries and actigraph data over one week. Undergraduate students were randomly assigned to use daily- or weekly-collected sleep diaries. Sleep parameters obtained from these measures were compared to each other via concordance with concurrent actigraph data. It was hypothesized that daily-collected sleep diaries would have greater concordance with actigraphy than weekly-collected sleep diaries. Results indicated that daily-collected sleep diaries provided more reliable data than weekly-collected sleep diaries, but the differences were not statistically significant. Additional aims examined self-reported sleep diary adherence, the participation day number, and day of the week. There were trends for the Daily group to have better adherence. Overall concordance did not change based on the day number or day of the week. Both sleep diaries yield comparable sleep parameter data, suggesting that clinicians and researchers can use either method to estimate sleep parameters.
Date: May 2014
Creator: Francetich, Jade M.
Partner: UNT Libraries

The Effect of Natural Gas Well Setback Distance on Drillable Land in the City of Denton, Texas

Description: Municipalities protect human health and environmental resources from impacts of urban natural gas drilling through setback distances; the regulation of distances between well sites and residences, freshwater wells, and other protected uses. Setback distances have increased over time, having the potential to alter the amount and geographical distribution of drillable land within a municipality, thereby having implications for future land use planning and increasing the potential for future incompatible land uses. This study geographically applies a range of setback distances to protected uses and freshwater wells in the city limits of Denton, Texas to investigate the effect on the amount of land remaining for future gas well development and production. Denton lies on the edge of a productive region of the Barnett Shale geological formation, coinciding with a large concentration of drillable land in the southwestern region of the study area. This region will have the greatest potential for impacts to future municipal development and land use planning as a result of future gas well development and higher setback standards. Given the relatively high acreage of drillable land in industrially zoned subcategory IC-G and the concern regarding gas well drilling in more populated areas, future drilling in IC-G, specifically in IC-G land cover classes mowed/grazed/agriculture and herbaceous, would have the least impact on residential uses and tree cover, as well as decreasing the potential for future incompatible land uses.
Date: May 2014
Creator: Daniel, Michael
Partner: UNT Libraries

Electrodeposition of Nickel and Nickel Alloy Coatings with Layered Silicates for Enhanced Corrosion Resistance and Mechanical Properties

Description: The new nickel/layered silicate nanocomposites were electrodeposited from different pHs to study the influence on the metal ions/layered silicate plating solution and on the properties of the deposited films. Nickel/layered silicate nanocomposites were fabricated from citrate bath atacidic pHs (1.6−3.0), from Watts’ type solution (pH ~4-5), and from citrate bath at basic pH (~9). Additionally, the new nickel/molybdenum/layered silicate nanocomposites were electrodeposited from citrate bath at pH 9.5. The silicate, montmorillonite (MMT), was exfoliated by stirring in aqueous solution over 24 hours. The plating solutions were analyzed for zeta potential, particle size, viscosity, and conductivity to investigate the effects of the composition at various pHs. The preferred crystalline orientation and the crystalline size of nickel, nickel/layered silicate, nickel/molybdenum, and nickel/molybdenum/layered silicate films were examined by X-ray diffraction. The microstructure of the coatings and the surface roughness was investigated by scanning electron microscopy and atomic force microscopy. Nickel/molybdenum/layered silicate nanocomposites containing low content of layered silicate (1.0 g/L) had increase 32 % hardness and 22 % Young’s modulus values over the pure nickel/molybdenum alloy films. The potentiodynamic polarization and electrochemical impedance measurements showed that the nickel/molybdenum/layered silicate nanocomposite layers have higher corrosion resistance in 3.5% NaCl compared to the pure alloy films. The corrosion current density of the nickel/molybdenum/layered silicate nanocomposite composed of 0.5 g/L MMT is 0.63 µA·cm-2 as compare to a nickel/molybdenum alloy which is 2.00 µA·cm-2.
Date: August 2014
Creator: Tientong, Jeerapan
Partner: UNT Libraries

Electromagnetically Modulated Sonic Structures

Description: Phononic crystals are structures composed of periodically arranged scatterers in a background medium that affect the transmission of elastic waves. They have garnered much interest in recent years for their macro-scale properties that can be modulated by the micro-scale components. The elastic properties of the composite materials, the contrast in the elastic properties of the composite materials, and the material arrangement all directly affect how an elastic wave will behave as it propagates through the sonic structure. The behavior of an elastic wave in a periodic structure is revealed in its transmission bandstructure, and modification of any the elastic parameters will result in tuning of the band structure. In this dissertation, a phononic crystal with properties that can be modulated using electromagnetic radiation, and more specifically, radio-frequency (RF) light will be presented.
Date: May 2014
Creator: Walker, Ezekiel Lee
Partner: UNT Libraries

Elizabeth Bishop in Brasil: An Ongoing Acculturation

Description: Elizabeth Bishop (1911–1979), one of the foremost modern American poets, lived in Brasil during seventeen-odd years beginning in 1951. During this time she composed the poetry collection Questions of Travel, stand-alone poems, and fragments as well as prose pieces and translations. This study builds on the work of critics such as Brett Millier and Lorrie Goldensohn who have covered Bishop’s poetry during her Brasil years. However, most American critics have lacked expertise in both Brasilian culture and the Portuguese language that influenced Bishop’s poetry. Since 2000, in contrast, Brasilian critic Paulo Henriques Britto has explored issues of translating Bishop’s poetry into Portuguese, while Maria Lúcia Martins and Regina Przybycien have examined Bishop’s Brasil poems from a Brasilian perspective. However, American and Brasilian scholars have yet to recognize Bishop’s journey of acculturation as displayed through her poetry chronologically or the importance of her belated reception by Brasilian literary and popular culture. This study argues that Bishop’s Brasil poetry reveals her gradual transformation from a tourist outsider to a cultural insider through her encounters with Brasilian history, culture, language, and politics. It encompasses Bishop’s published and unpublished Brasil poetry, including drafts from the Elizabeth Bishop Papers at Vassar College. On a secondary level, this study examines a reverse acculturation in how Brasilian popular and literary communities have increasingly focused on Bishop since her death, culminating in the 2013 film, Flores Raras (Reaching for the Moon in English). Understanding this extremely rare and sustained intercultural junction of Bishop in Brasil, a junction that no American poet has made since, adds a crucial angle to twentieth-first century transnational literary perspectives.
Date: August 2014
Creator: Neely, Elizabeth
Partner: UNT Libraries

Environmental Imagination: the Constitution and Projection of a Sustainable Ethos

Description: This dissertation provides a theoretical analysis and examination of the role of imagination in the formation of an environmental ethos. The majority of ethical theories in environmental thought largely neglect the role that imagination plays in both the relationships that humans form with their environment, and the subsequent role that imagination plays in constituting the way that those relationships are understood ethically. To explore the role of imagination in constituting and subsequently projecting such an ethical way of being, this dissertation selectively analyzes the history of imagination in philosophy, cognitive science, and environmental thought. In addition, this dissertation also explores the role that images play in forming collective responses to environmental disasters, and the further role that imagination plays in overcoming the moral motivation gap.
Date: December 2014
Creator: Day, Philip Garrett
Partner: UNT Libraries

Evaluating the Feasibility of Accelerometers in Hand Gestures Recognition

Description: Gesture recognition plays an important role in human computer Interaction for intelligent computing. Major applications like Gaming, Robotics and Automated Homes uses gesture recognition techniques which diminishes the usage of mechanical devices. The main goal of my thesis is to interpret SWAT team gestures using different types of sensors. Accelerometer and flex sensors were explored extensively to build a prototype for soldiers to communicate in the absence of line of sight. Arm movements were recognized by flex sensors and motion gestures by Accelerometers. Accelerometers are used to measure acceleration in respect to movement of the sensor in 3D. Flex sensors changes its resistance based on the amount of bend in the sensor. SVM is the classification algorithm used for classification of the samples. LIBSVM (Library for Support Vector Machines) is integrated software for support vector classification, regression and distribution estimation which supports multi class classification. Sensors data is connected to the WI micro dig to digitize the signal and to transmit it wirelessly to the computing device. Feature extraction and Signal windowing were the two major factors which contribute for the accuracy of the system. Mean Average value and Standard Deviation are the two features considered for accelerometer sensor data classification and Standard deviation is used for the flex sensor analysis for optimum results. Filtering of the signal is done by identifying the different states of signals which are continuously sampled.
Date: December 2014
Creator: Karlaputi, Sarada
Partner: UNT Libraries

Evidence for Multiple Functions of a Medicago Truncatula Transporter

Description: Legumes play an important role in agriculture as major food sources for humans and as feed for animals. Bioavailable nitrogen is a limiting nutrient for crop growth. Legumes are important because they can form a symbiotic relationship with soil bacteria called rhizobia that results in nitrogen-fixing root nodules. In this symbiosis, rhizobia provide nitrogen to the legumes and the legumes provide carbon sources to the rhizobia. The Medicago truncatula NPF1.7/NIP/LATD gene is essential for root nodule development and also for proper development of root architecture. Work in our lab on the MtNPF1.7/MtNIP/LATD gene has established that it encodes a nitrate transporter and strongly suggests it has another function. Mtnip-1/latd mutants have pleiotropic defects, which are only partially explained by defects in nitrate transport. MtNPF1.7/NIP/LATD is a member of the large and diverse NPF/NRT1(PTR) transporter family. NPF/NRT1(PTR) members have been shown to transport other compounds in addition to nitrate: nitrite, amino acids, di- and tri-peptides, dicarboxylates, auxin, abscisic acid and glucosinolates. In Arabidopsis thaliana, the AtNPF6.3/NRT1.1( CHL1) transporter was shown to transport auxin as well as nitrate. Atchl1 mutants have defects in root architecture, which may be explained by defects in auxin transport and/or nitrate sensing. Considering the pleiotropic phenotypes observed in Mtnip-1/latd mutant plants, it is possible that MtNPF1.7/NIP/LATD could have similar activity as AtNPF6.3/NRT1.1(CHL1). Experimental evidence shows that the MtNPF1.7/NIP/LATD gene is able to restore nitrate-absent responsiveness defects of the Atchl1-5 mutant. The constitutive expression of MtNPF1.7/NIP/LATD gene was able to partially, but not fully restore the wild-type phenotype in the Atchl1-5 mutant line in response to auxin and cytokinin. The constitutive expression of MtNPF1.7/NIP/LATD gene affects the lateral root density of wild-type Col-0 plants differently in response to IAA in the presence of high (1mM) or low (0.1 mM) nitrate. MtNPF1.7/NIP/LATD gene expression is not regulated by nitrate ...
Date: December 2014
Creator: Huang, Ying-Sheng
Partner: UNT Libraries

Exploration of Visual, Acoustic, and Physiological Modalities to Complement Linguistic Representations for Sentiment Analysis

Description: This research is concerned with the identification of sentiment in multimodal content. This is of particular interest given the increasing presence of subjective multimodal content on the web and other sources, which contains a rich and vast source of people's opinions, feelings, and experiences. Despite the need for tools that can identify opinions in the presence of diverse modalities, most of current methods for sentiment analysis are designed for textual data only, and few attempts have been made to address this problem. The dissertation investigates techniques for augmenting linguistic representations with acoustic, visual, and physiological features. The potential benefits of using these modalities include linguistic disambiguation, visual grounding, and the integration of information about people's internal states. The main goal of this work is to build computational resources and tools that allow sentiment analysis to be applied to multimodal data. This thesis makes three important contributions. First, it shows that modalities such as audio, video, and physiological data can be successfully used to improve existing linguistic representations for sentiment analysis. We present a method that integrates linguistic features with features extracted from these modalities. Features are derived from verbal statements, audiovisual recordings, thermal recordings, and physiological sensors signals. The resulting multimodal sentiment analysis system is shown to significantly outperform the use of language alone. Using this system, we were able to predict the sentiment expressed in video reviews and also the sentiment experienced by viewers while exposed to emotionally loaded content. Second, the thesis provides evidence of the portability of the developed strategies to other affect recognition problems. We provided support for this by studying the deception detection problem. Third, this thesis contributes several multimodal datasets that will enable further research in sentiment and deception detection.
Date: December 2014
Creator: Pérez-Rosas, Verónica
Partner: UNT Libraries

Forgotten Glory - Us Corps Cavalry in the ETO

Description: The American military experience in the European Theater of Operations during the Second World War is one of the most heavily documented topics in modern historiography. However, within this plethora of scholarship, very little has been written on the contributions of the American corps cavalry to the operational success of the Allied forces. The 13 mechanized cavalry groups deployed by the U.S. Army served in a variety of roles, conducting screens, counter-reconnaissance, as well as a number of other associated security missions for their parent corps and armies. Although unheralded, these groups made substantial and war-altering impacts for the U.S. Army.
Date: May 2014
Creator: Nance, William Stuart
Partner: UNT Libraries

High-Density Polyethylene/Peanut Shell Biocomposites

Description: A recent trend in the development of renewable and biodegradable materials has led to the development of composites from renewal sources such as natural fibers. This agricultural activity generates a large amount of waste in the form of peanut shells. The motivation for this research is based on the utilization of peanut shells as a viable source for the manufacture of biocomposites. High-density polyethylene (HDPE) is a plastic largely used in the industry due to its durability, high strength to density ratio, and thermal stability. This research focuses in the mechanical and thermal properties of HDPE/peanut shell composites of different qualities and compositions. The samples obtained were subjected to dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and mechanical tensile strength tests. TO prepare the samples for analysis, the peanut shells were separated into different mesh sizes and then mixed with HDPE at different concentrations. The results showed that samples with fiber size number 10 exhibited superior strength modulus of 1.65 GPa versus results for HDPE alone at 1.32 GPa. The analysis from the previous experiments helped to determine that the fiber size number 10 at 5%wt. ratio in HDPE provides the most optimal mechanical and thermal results. From tensile tests the highest modulus of elasticity of 1.33 GPa was achieved from the samples of peanut shells size number 10 in HDPE at 20%wt. ratio, while the results for HDPE alone were only of 0.8 GPa. The results proved the hypothesis that the addition of peanut shells to HDPE enhances both the thermal and mechanical properties of the composite.
Date: May 2014
Creator: Londoño Ceballos, Mauricio
Partner: UNT Libraries

“The Inevitable: Withdrawn”

Description: The Inevitable: Withdrawn is a critical preface and collection of non-fiction writing: personal essay, lyric essay, fragments, and experimental forms. The work’s cohesive subject matter is the author’s European vacation directly following her divorce. Within the pieces, the author attempts to reconcile who she is when starting over and she begins to ask questions regarding the human condition: How do I learn to exhibit intimacy again, not just with romantic partners, but with also in a familial way with my father, and how does absence in these relationships affect my journey and how I write about it? How do I view, and remake myself, when finding my identity that was tied to another individual compromised? How does a body, both physical and belonging to me, and physical as text, take certain shapes to reflect my understanding? How do I define truth, and how do I interpret truth and authenticity in both experience and writing? How do I define and know the difference between belief and truth? And finally, how does narrative and language protect, or expose me? The Inevitable: Withdrawn considers debates regarding the definition of narrative in order to address a spectrum of non-fiction writing. The collection takes into consideration non-fiction conventions, form as functionality, philosophy, linguistics, cognitive psychology, prose and poetic theory, and the works of other notable writers.
Date: May 2014
Creator: Christy, Gwendolyn Anne
Partner: UNT Libraries

The Influence of Surface Roughness and Its Geometry on Dynamic Behavior of Water Droplets

Description: In this study the author reports the effects of surface roughness on dynamic behavior of water droplets on different types of rough structures. First, the influence of roughness geometry on the Wenzel/ Cassie-Baxter transition of water droplets on one-tier (solid substrates with Si micropillars) surfaces is studied (Chapter 3). In order to address distinct wetting behaviors of the advancing and receding motions, the author investigates the Wenzel/ Cassie-Baxter transition of water droplets on one-tier surfaces over a wide range of contact line velocities and droplet volumes in both advancing and receding movements. The discussions are strengthened by experimental results. According to the author’s analysis, the advancing contact zone tends to follow the Cassie-Baxter behavior for a wider range of geometric ratios than the receding contact zone. Physical phenomena such as advancing contact line rolling mechanism and the pinning of the receding contact line are introduced to justify distinct transition points of the advancing and receding movements respectively. Based on the analysis provided in Chapter 3, the author experimentally investigates the contact line fluctuations and contact line friction coefficients of water droplets on smooth, one-tier, and two-tier (with carbon nanotubes (CNTs) grown on Si micropillars) surfaces in Chapters 4 and 5. Both the advancing and receding contact line fluctuations/friction coefficients have been measured, analyzed and compared on smooth, one-tier, and two-tier surfaces over a wide range of contact line velocities and droplet volumes. A comprehensive analysis is provided to explain the experimental observations.
Date: December 2014
Creator: Sadeghpour, Nima.
Partner: UNT Libraries

Interaction of Plasmons and Excitons for Low-Dimension Semiconductors

Description: The effects of surface plasmon for InGaN/GaN multi-quantum wells and ZnO nanoparticles optical linear and nonlinear emission efficiency had been experimentally studied. Due to the critical design for InGaN MQWs with inverted hexagonal pits based on GaN, both contribution of surface plasmon effect and image charge effect at resonant and off resonant frequencies were experimentally and theoretically investigated. With off- resonant condition, the InGaN MQWs emission significantly enhanced by metal nanoparticles. This enhancement was caused by the image charge effect, due to the accumulation of carriers to NPs region. When InGaN emission resonated with metal particles SP modes, surface Plasmon effect dominated the emission process. We also studied the surface plasmon effect for ZnO nanoparticles nonlinear optical processes, SHG and TPE. Defect level emission had more contribution at high incident intensity. Emissions are different for pumping deep into the bulk and near surface. A new assumption to increase the TPE efficiency was studied. We thought by using Au nanorods localized surface plasmon mode to couple the ZnO virtual state, the virtual state’s life time would be longer and experimentally lead the emission enhancement. We studied the TPE phenomena at high and near band gap energy. Both emission intensity and decay time results support our assumption. Theoretically, the carriers dynamic mechanism need further studies.
Date: December 2014
Creator: Lin, Jie (physicist)
Partner: UNT Libraries