Digital Commons Network^™

Synthesis And Application Of Ceramic Paste For High-Temperature Electronic Packaging, Ardalan Nasiri

Graduate Theses and Dissertations

This dissertation research focused on the synthesis and application of ceramic paste for high-temperature applications. An alumina paste material comprising aluminum dihydric phosphate and alumina powder was developed for high-temperature electronic packaging. Nano aluminum nitride and nano-silica powders were embedded to promote the paste curing process, limit the grain growth, and increase its bond shear strength. The chip-to-substrate bond strength was enhanced and met the MIL-STD requirements for die-attach assembly. Its encapsulation property was improved with fewer cracks compared to similar commercial ceramic encapsulants. The die-attach material and encapsulation properties tested at 500°C showed no defect or additional cracks. Thermal …

Elucidating Collagen Degradation Synergy Between Col G And Col H From Hathewaya (Clostridium) Histolytica And Identifying Novel Structural Features In Hpt And Rec Domains From Vars Histidine Kinase In V. Alginolyticus, Perry Caviness

Graduate Theses and Dissertations

In this research the mechanisms by which Hathewaya (Clostridia) histolytica collagenases are secreted and work together to degrade collagens are investigated. While H. histolytica collagenases Col G and Col H have similar multi-domain structures the difference in number of and orientation of the domains hint that the two target different regions in collagen. Study small angle x-ray scattering (SAXS) was used to give a low-resolution envelope of full-length Col G and Col H and Col G/Col H non-catalytic domains bound to a collagen-like peptide (mini-collagen). SAXS derived envelopes along with structural information was used to tease out the mechanisms by …

The Relationship Between Leadership Practices And Organizational Commitment Of Telecommunicators, André Lanier

Graduate Theses and Dissertations

The performance of 9-1-1 telecommunicators can mean the difference between life and death for the person on the other end of a phone. Effective leadership is critical to the success of the public safety answer point (PSAP) and the organizational commitment of the 9-1-1 telecommunicator. Bass and Riggio’s (2006) Full Range of Leadership Theory (FLRT) is the basis for the current study. The FRLT covers leadership styles from laissez-faire to transformational (Matikainen, 2019).

The purpose of conducting the study was to identify and describe the 9-1-1 telecommunicator’s organizational commitment based on the PSAP leadership categories. The study made use of …

Thiophene Derivative Monomers Co-Electropolymerized On Microelectrodes Within Arrays For Tailored Surface Chemistry And Electrochemical Properties, Benjamin J. Jones

Graduate Theses and Dissertations

Potentiodynamic co-electropolymerization of two thiophene derivatives, (2,3-dihydrothieno[3,4-b]dioxin-2-yl)methanol (1) and 4-((2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)-methoxy)-4-oxobutanoic acid (2), in aqueous solutions (0.02 M total monomer, 0.05 M sodium dodecyl sulfate (SDS) and 0.1 M LiClO4) on gold microband electrodes in an array was investigated. A modified Steglich esterification reaction between monomer 1 and succinic anhydride produced monomer 2 at 93.6% yield. Seven deposition solutions of the two monomers, defined by mol% of monomer 2 (0, 25, 34, 50, 66, 75, 100) generated seven sets of polymer films by cyclic voltammetry in a specially designed cell to conserve monomer. The onset potential for monomer oxidation and total …

The Emotional Toil Of Paying For College: Lower Socioeconomic Status White Women’S College Experiences, 1880-1920, Heidi A. Jaeckle

Graduate Theses and Dissertations

Typically historical inquiries in higher education have been centered on privileged individuals from wealthier backgrounds who had the opportunity of attending primarily prestigious institutions. The experiences of college women from lower to middle class socioeconomic backgrounds have been for the most part ignored. This dissertation explores how socioeconomic backgrounds shaped the experiences of college women from the late nineteenth century to the early twentieth century, focusing on lower class students. With no universal financial aid program, the majority of these women were from families who could afford to pay tuition. Women from lower socioeconomic backgrounds did attend college, but their …

Rice Fortification By Parboiling In Limited-Water Soaking To Alleviate Mineral And Vitamin Deficiency, Annegret Jannasch

Graduate Theses and Dissertations

Fortification of rice by parboiling is considered a potential alternative to currently available fortification technologies to produce rice with higher mineral and vitamin content significantly contributing to nutrient intake in populations with high prevalence of micronutrient deficiencies. Higher nutrient retention rates and improved sensory characteristics are advantages of fortified parboiled rice compared to fortified rice obtained by currently used fortification technologies including dusting, coating, and extrusion. However, conventional parboiling processes employ excess water that presents an environmental hazard if discarded without treatment. Thus, the objective of this study was to evaluate a limited-water soaking method for the fortification of rice …

Converter- And Module-Level Packaging For High Power Density And High Efficiency Power Conversion, Amol Rajendrakumar Deshpande

Graduate Theses and Dissertations

Advancements in the converter- and module-level packaging will be the key for the development of the emerging high-power, high power-density, high-eciency power conversion applications, such as traction, shipboards, more-electric-aircraft, and locomotive. Wide bandgap (WBG) devices such as silicon carbide (SiC) MOSFET attract much attention in these applications for their fast switching speeds, resulting in low loss and a consequent possibility for high switching frequency to increase the power density. However, for high-current, high power implementations, WBG devices are still available in small die sizes. Multiple SiC devices need to be connected in parallel to replace a large IGBT die. It …

The Conservation And Population Ecology Of The Imperiled Crawfish Frog (Lithobates Areolatus) In Human-Altered Landscapes, Chelsea Shannon Kross

Graduate Theses and Dissertations

The Crawfish Frog (Lithobates areolatus) is an imperiled amphibian currently experiencing severe declines across its range. As a species with unique habitat requirements that is threatened by habitat loss, understanding their status across the landscape and how they respond to environmental stressors is key to developing effective conservation strategies that maintain and expand viable populations. We used a combination of observational, experimental, and theoretical approaches to understand the status of Crawfish Frog populations in Northwest Arkansas (NWA), their individual and population-level response to human-induced changes in vegetation surrounding breeding wetlands, and the effects of fire management on larval development within …

Towards High Efficiency And High Power Density Converter: System Level Design, Modulation, And Active Emi Filters, Hongwu Peng

Graduate Theses and Dissertations

Power converter exposes strong challenges to its efficiency, power density and reliability. For the grid-connected inverter application, three-level (3-L) T-type neutral-point-clamped (TNPC) inverters has higher efficiency and lower total harmonic distortion (THD) compared to two-level inverter. Hybrid switch concept combines the benefit of both silicon carbide (SiC) MOSFET and Si IGBT. By applying hybrid switch structure in 3-L T-type inverter, the total power density of 3-L TNPC inverter will be higher while the cost will be lower than that of all-SiC 3-L T-type inverter. The hybrid switch based 3-L TNPC inverter also imposes challenge to its modulation and control, a …

Effect Of The Prospect Of Transport On Captive Tiger Behavior And Fecal Cortisol In Naïve And Experienced Tigers, Callan Lichtenwalter

Graduate Theses and Dissertations

With close to 5,000 captive tigers in the United States, it is vital to ensure that these tigers are receiving adequate welfare whether they are in an accredited facility, or privately owned. The goal of this study was to assess whether captive tigers at a rescue facility with experience being transported outside of the facility would respond differently to the presentation of their transport vehicle than their naïve counterparts who had only been transported within the facility. The behavior of 5 naïve and 7 experienced tigers (n = 12) located at Turpentine Creek Wildlife Refuge in Eureka Springs, Arkansas was …

Effects Of Terrestrial Weathering On Rare Earth Element Concentrations And Sulfur Isotopic Signatures Of Carbonaceous And Ordinary Chondrites, Ruby Virginia Patterson

Graduate Theses and Dissertations

Understanding the effects of weathering of chondrites is essential to gaining accurate and useful information about the formation of our solar system, as well as a more detailed account of the mobilization of chondritic compounds when they encounter terrestrial conditions. Elemental concentrations and stable isotope analyses of chondrites, considered to be the most primordial material in the solar system, are two tools which help unlock the weathering patterns of these specimens when they enter the earth system. However, it is not currently known exactly how time spent in the field alters rare earth element (REE) concentration or δ34S signatures within …

Heat And Mass Transfer In Parboiled Rice During Heating With 915 Mhz Microwave Energy And Impacts On Milled Rice Properties, Deandrae L.W. Smith

Graduate Theses and Dissertations

Microwave (MW) heating offers an energy-efficient, fast method to dry high moisture content (MC) parboiled rice to safe storage MC. However, there is limited research that describes the fundamentals of heat and mass transport in rice kernels exposed to MW energy at 915 MHz, the most promising heating frequency for industrialized processing. This information is vital to explain the implications of MW technology on dried rice quality. The overall objective of this study was to develop a microwave heating technology that can sufficiently dry high MC parboiled rough rice kernels in one pass using a 915-MHz industrial microwave system. An …

Market Coverage, Franchise Ownership, And Outlet Survival, Jingbo Zhang

Graduate Theses and Dissertations

This dissertation investigates the relationships between market coverage, franchise ownership, and franchise outlet survival rate.

In the first essay, I develop a spatial market coverage measure by integrating geocodes of outlets across five fast-food franchise systems. This spatial market coverage builds upon one navigation system algorithm by utilizing geographic coordinates. This measure can be applied by entrepreneurs to examine their geographic coverage and address issues of market oversaturation and lack of coverage.

In the second essay, I extend the spatial market coverage and examine how this spatial market coverage and franchise ownerships affect franchise outlet survival rate, which has not …

A Macroevolutionary View On Extinction In Aves, Chiroptera, And Odonata, Peter Hasik

Graduate Theses and Dissertations

A central goal of conservation biology is to identify and understand the factors that lead to extinction. The Earth is currently undergoing a 6th mass extinction event, in large part because of human activity. In the last century, rates of extinction have increased anywhere from 8-100 times the background rate of 2 extinctions per 10,000 species every 100 years. However, there remains a debate over whether certain species are predisposed to a higher extinction risk. In particular, it is not known if the macroevolutionary history of a lineage is a major contributor to the probability of extinction, nor is it …

Reactions To Gulf War I And Gulf War Ii In American And Iraqi Cinema And Theatre: The Quest For A Global Utopia, Tajaddin Salahaddin Noori

Graduate Theses and Dissertations

Many American and Iraqi cultural reactions to Gulf War I and Gulf War II, including the texts selected for this story, expressed the dystopian consequences of these wars. However, this study focuses on exploring the utopian dimensions of the selected texts and investigates how these texts attempt to reconcile both sides of the conflict and produce visions toward a global utopia. Significantly, this study represents the visions toward a global utopia as a series of visions toward oneness. That is, oneness of human beings over otherness, oneness of different nation states under one global community, and oneness of cultural productions’ …

Nutritional Supplementation And Skeletal Muscle Health In Chronic Diseases, Hexirui Wu

Graduate Theses and Dissertations

Prevalence of chronic diseases in the United States keeps increasing in recent years. There are approximately four in ten adults having chronic diseases in America. Chronic diseases include obesity, aging, heart diseases, cancer and many others. This thesis mainly focuses on obesity and aging. Skeletal muscle performance is impaired in obesity and aging conditions. One common reason causing this could be higher fat mass and lower muscle mass. However, there is no study showing what pathways are involved in the imbalance of body composition. Therefore, the first objective of the thesis is to determine gene expression of selected pathways in …

Liver Transcriptomic Analysis After Short- And Long-Term Feeding Of Soy Protein Isolate And Its Ability To Reduce Liver Steatosis In Obese Zucker Rats, Melisa Kozaczek

Graduate Theses and Dissertations

According to the Centers for Disease Control and Prevention (CDC) the prevalence of obesity in adults in the United States during 2017-2018 was a 42.4%, a high number considering all the risks factors associated with this disorder, such as cardiovascular disease, insulin resistance, diabetes type 2, and fatty liver disease, among others. Fatty liver disease is the accumulation of lipids in the liver that can account for more than 5 to 10% of the liver’s weight. There are two types of fatty liver disease, alcoholic fatty liver disease (AFLD), and non-alcoholic fatty liver disease (NAFLD). AFLD is the detrimental accumulation …

The Medieval British Legacy Of The Founding Myth Of Britain, Timothy J. Nelson

Graduate Theses and Dissertations

The Medieval British Legacy of the Founding Myth of Britain” examines the historiographical development of the founding myth of Britain between the 9th and 14th centuries. This study begins with an overview of the Latin, Anglo-Norman French, Middle English, and Middle Welsh texts that transmit this founding myth across medieval Britain. The stylistic features and the motivations of the authors who are adapting this myth are addressed but the main objective of this overview is to introduce the texts in question and to start establishing the intertextual relationships between these works. The textual examination of the historiographical development of the …

The Postsecondary Enrollment Of Black American Men: The Perceived Influence Of Environmental Factors, David V. Tolliver, Iii

Graduate Theses and Dissertations

In the United States, there has been a consistent under-enrollment of Black American men who have enrolled and graduated from four-year colleges and universities. The result of this lack of educational attainment is problematic, as it can be seen in lower employment rates, higher under-employment rates, higher rates of incarceration, poorer health, and even a lower quality life. Institutional leaders and policymakers have struggled to find solutions for increasing the participation of Black American men with largely mixed results. Most of these programmatic attempts, however, have been limited in their approach and have not taken into account family and informal …

Elucidating Basis Of Rice Discoloration And Developing Prevention Strategies, Zeinab Mohammadi Shad

Graduate Theses and Dissertations

Economically, discolored rice kernels have less market value, which can seriously impact farm net profit. The reasons for rice discoloration during storage have not been studied extensively and many questions remain. Therefore, the primary goal of this study was to improve understanding of the role and contributions of storage practices on rice quality degradation and discoloration. In this study, three rice cultivars including XL753 (hybrid), Roy J (pureline), and Titan were assessed for changes in quality and microbial kinetics. The rice samples at a high moisture content (MC) of 21% w.b. and a low MC of 16% were stored at …

Framing And Newspaper Coverage Of Racial Integration, Amy Unruh

Graduate Theses and Dissertations

For many Americans who grew up in the 1960s, the first published information about Africans came directly from Africa, in the form of exotic photographs and stories in National Geographic. Susan Goldberg, Editor in Chief of National Geographic, addressed the issue of race portrayals in the magazine, reflecting on the realization that National Geographic often provided readers “their first look at the world” while rarely acknowledging the struggles of race in the United States. The magazine displayed full-color photographs depicting Africans from many nations, dressed in native clothing and jewelry, positioned in settings that implied dignity, beauty and strength. Meanwhile, …

Efficacy Of Multivitaim-Mineral Supplementation On Health-Related Quality Of Life And Physical Activity In Young Adults, Sarah Pendergraft

Graduate Theses and Dissertations

Micronutrients are essential for both physical and mental health. There is a correlation between poor health and mood and micronutrient deficiencies. Young adults age 18-24 are an at-risk, understudied population likely to benefit from multivitamin mineral supplementation. Multivitamin mineral supplementation is a potential way to bridge gaps in micronutrient levels, thus influencing health-related outcomes. Here, we provide the first attempt at influencing health-related quality of life and physical activity with a multivitamin mineral supplement in young adults. Using a supplement formulated without herbal extracts and caffeine, this double-blind study examined the efficacy of a daily multivitamin mineral supplement for 30 …

Self, Emily Aguayo

Graduate Theses and Dissertations

This is a translation of Dr. Erika Almenara’s complete published collection of poetry. The original publications span a period of over twelve years of work, with books published in 2006, 2008, and 2018. The first book of poetry in this series of translations, Reino Cerrado (Closed Kingdom), explores the profound contemplations of life and how to turn those thoughts into words and put them on paper. We see images of nature, hear faint religious overtones, and feel the distress of a woman searching for a healthy relationship, and having little luck. Para evitar los rastros (To Avoid All Traces), the …

Stigma And Disclosure Of Chronic Pain In Higher Education: A Qualitative Study, Jennifer K. Davenport

Graduate Theses and Dissertations

Students with chronic pain represent an overlooked population in higher education institutions, due to the barriers their conditions present and the stigma associated with chronic pain. There is existing research examines treatment of elderly populations and best practices for university students with disabilities, facing discrimination. This study sheds light on a gap in the existing research, where a niche population of students in chronic pain navigated disclosure issues and stigma in the academic environment. The purpose of the qualitative research study was to examine how anticipated or experienced stigma associated with chronic pain conditions influenced disclosure of chronic pain for …

The Stigmatization Of Hunger: The Impact Of Social Stigma On Arkansas Youths’ Food Security, Emily Thompson

Graduate Theses and Dissertations

In Arkansas, 26.3% of children are food insecure, meaning they do not have enough or lack the ability to obtain enough food for adequate nutrition (Miller 2019). In recent years, a new phenomenon has been taking place called lunch shaming where children are sometimes forced to wear signs or handstamps that say the child’s lunch account is overdue. This research analyzes how the media frames food insecurity and how perceived social stigmas affect a student’s willingness to seek out help when struggling with food security.

Arkansas Aprons: Food Power And Women In Arkansas, 1857 To 1891, Robyn Shahan Spears

Graduate Theses and Dissertations

Arkansas foodways in the late nineteenth century were defined by times of plenty and scarcity, need and connection, traditions and innovations. These components created a unique culture in which women through food exchange, were able to improve their standard of living. The years of plenty established in the antebellum era lay in stark contrast to the scarcity during the Civil War. What followed during the Progressive Era are fascinating histories of women employing their agency to empower and improve not only their lives but also future generations. I argue that these women utilized their agency to engage in “food power,” …

Perceptions Of Help-Seeking Likelihood For Depression: Examining The Relative Predictive Value Of Ethnicity And Barriers To Care, Linda Esperanza Guzman

Graduate Theses and Dissertations

Latinx and non-Latinx White adults 18 years of age and older experience depression at proportional rates. However, Latinxs seek specialized care for depression at lower rates than non-Latinx Whites, suggesting these groups experience barriers in accessing care differently. This study sought to test the theoretical steps of help-seeking as informed by the Gaining Access and Treatment Equity model (GATE model; Bridges, 2018). According to the GATE model, successful help-seeking means navigating a series of barriers: sequentially, these are perceived need, attitudinal barriers, and structural barriers. Participants (N = 987) were either Latinx (n = 437) or non-Latinx White (n = …

Design And Simulation Of Power Electronics Modules, Haonan Jia

Graduate Theses and Dissertations

Silicon carbide (SiC), a wide-bandgap semiconductor material, greatly improves the performance of power semiconductor devices. Its electrical characteristics have a positive impact on the size, efficiency, and weight of the power electronics systems. Parasitic circuit elements and thermal properties are critical to the power electronics module design. This thesis investigates the various aspects of layout design, electrical simulation, thermal simulation, and peripheral design of SiC power electronic modules. ANSYS simulator was used to design and simulate the power electronic modules. The parasitic circuit elements of the power module were obtained from the device parameters given in the datasheet of these …

Determination Of Critical Y-Leaf Potassium Concentrations Across Reproductive Growth Stages For Direct-Seeded Delay-Flooded Rice, Chandler Edwin Gruener

Graduate Theses and Dissertations

Rice (Oryza sativa L.) grain yield can be limited by potassium (K) deficiency on soils low in exchangeable K. Visually diagnosing K deficiency during early reproductive growth is not easily done and the interpretation of traditional tissue analysis is limited to select growth-stages. Our primary focus was to define continuous critical Y-leaf-K concentrations during reproductive growth for the production of maximal grain yield. A secondary objective was to examine Y-leaf sap-K concentration, measured using a handheld device, as a rapid in-field method of monitoring rice plant K nutrition. The Y-leaf is defined as the uppermost fully extended leaf with a …

Relational Uncertainty In Romantic Relationships: The Influence Of Attachment And Relational Maintenance Behaviors, Jay Cruz

Graduate Theses and Dissertations

This study examined the influence of attachment and relational maintenance behaviors on relational uncertainty. Ninety individuals currently involved in romantic relationships completed measures assessing their attachment (i.e., secure, preoccupied, dismissive, fearful), relational uncertainties (i.e., self, partner, relationship), and relational maintenance behaviors (i.e., shared tasks, shared networks, positivity, openness, assurances). Findings demonstrated that both secure attachment and fearful attachment were not significantly associated with self, partner, or relationship uncertainty. In addition, dismissive attachment was negatively associated with partner uncertainty and positively associated with relationship uncertainty. Preoccupied attachment was positively associated with both partner and relationship uncertainty. Furthermore, secure attachment was positively …