Digital Commons Network^™

Ti-6al-4v Β Phase Selective Dissolution: In Vitro Mechanism And Prediction, Michael A Kurtz

All Dissertations

Retrieval studies document Ti-6Al-4V β phase dissolution within total hip replacement systems. A gap persists in our mechanistic understanding and existing standards fail to reproduce this damage. This thesis aims to (1) elucidate the Ti-6Al-4V selective dissolution mechanism as functions of solution chemistry, electrode potential and temperature; (2) investigate the effects of adverse electrochemical conditions on additively manufactured (AM) titanium alloys and (3) apply machine learning to predict the Ti-6Al-4V dissolution state. We hypothesized that (1) cathodic activation and inflammatory species (H₂O₂) would degrade the Ti-6Al-4V oxide, promoting dissolution; (2) AM Ti-6Al-4V selective dissolution would occur …

The Use Of The South Carolina School Improvement Model - Quick Cycles In Sixth-Grade Science Classrooms, Jennifer Gnann

All Dissertations

Using data to make informed decisions about instruction strengthens a teacher’s delivery of content within the classroom. However, many teachers have not been taught how to properly use a model of rapid improvement cycles to analyze data and apply it to their classroom instruction. I modified the South Carolina School Improvement Model so that it could be used in short cycles to see how teachers used it to plan for, monitor, and adjust instruction in their classrooms.

I conducted a single case study over a six-week period in which I instructed two sixth-grade science teachers on how to use the …

Exploring Modalities Of Productivity And Critical Quality Attributes In Fed-Batch Chinese Hamster Ovary Cell Cultures, Stephanie Klaubert

All Dissertations

Chinese hamster ovary (CHO) cells are among the most commonly used mammalian cell lines for the production of recombinant therapeutic proteins due to ease of culturing and humanlike post-translational modification capabilities. However, when compared to microbial systems, CHO cell line growth and productivity is relatively low. As the demand for monoclonal antibody (mAb) treatments continues to rise, it is critical to explore modalities for improved growth and productivity in CHO cell cultures, with the goal of increased protein concentrations and maintained product quality. Though some mechanisms for improved productivity, including temperature and cell culture media formulations, are relatively well understood; …

Engineering Next-Generation Cardiovascular Therapies, Ryan Walker Barrs

All Dissertations

Cardiovascular diseases are the leading cause of death worldwide. Heart disease, in particular, accounted for 1 in every 5 deaths in the United States in 2021, representing a substantial public health burden that will require more effective treatment options to alleviate. Heart transplant surgery is currently the only option to completely restore cardiac function, but many patients die while waiting for a transplant due to a longstanding organ donor shortage. Thus, there is a dire need for accessible treatment options that can repair damaged hearts. Recent advances in tissue engineering and regenerative medicine have accelerated the development of therapies for …

Experimental And Computational Platforms For Studying Systems Mechanobiology, Brendyn Miller

All Dissertations

Mechanical stimulation through physical activity has been shown to play an important role in treating and preventing several non-communicable diseases such as hypertension, lower back pain (LBP), type-2 diabetes mellitus, and several cancers. This is accomplished through the regulation of cellular behavior and tissue remodeling within the body at both the micro- and macro-scale levels. The goal of mechanobiology research is to gain in-depth knowledge and understanding of how cells sense physical forces in conjunction with other biochemical cues and translate those factors into important biological functions that either maintain tissue homeostasis or lead to pathological states. Understanding these processes …

Cellular Mechanism Of Pentagalloyl Glucose-Mediated Prevention And Reversal Of Abdominal Aortic Aneurysms, Greg Halsey

All Dissertations

Abdominal aortic aneurysm (AAA) has been the 15th leading cause of death in persons older than 55 for the past ten years in several Western countries, with rupture resulting in an almost 100% mortality rate. AAA is a focal dilation of the aorta characterized by progressive loss of elastin and vascular smooth muscle cells (SMCs), as well as persistent inflammatory response [1]. The only treatment for AAA is surgery; however, the mortality post-procedure is still 1-4%, with a 15-30% chance of morbidity [2].

Pentagalloyl glucose (PGG) treatment is effective in the reversal of AAA. While its stabilizing interactions with extracellular …

Addressing Mercury Contamination From Artisanal Gold Mining In Colombia: Pollution Exposure, Health Risk, And Educational Efforts In The Communities Of La Toma, Colombia, Kelli Mccourt

All Dissertations

Artisanal and small-scale gold mining (ASGM) has become a primary environmental and public health concern in the region of Colombia known as Alto Cauca. The predominantly Afro-descendent communities of Yolombó and La Toma in Alto Cauca have experienced pollution linked to the use of mercury in the ASGM process. For the past decade, mercury has emerged as a contaminant of increasing concern in the communities due to its toxicity and ability to bioaccumulate and biomagnify. Likewise, mining in the region raises concerns over the leaching of metals into local waters. Given the complexity of risk and pollution in the communities, …

Delineating The Impact Of Vascular Smooth Muscle Cell Abca1/G1 And Mir-33a Expression On Atherosclerosis, Olanrewaju Oladosu

All Dissertations

Atherosclerotic cardiovascular disease is the leading cause of mortality worldwide due to being the predominant factor in heart attack and stroke deaths. Atherosclerotic cardiovascular disease is caused by cholesterol accumulating in arteries. It is historically thought that the cell type most responsible for causing atherosclerosis via excessive cholesterol accumulation is intimal monocyte-derived macrophages. However, macrophage-like cells (MLC) of vascular smooth muscle cell (VSMC) origin have now been proposed as another cell type to trigger atherosclerosis, since VSMC cholesterol accumulation results in these cells to trans-differentiate into a MLC phenotype. Three major genes involved in cholesterol metabolism are ABCA1, ABCG1, and …

Enhancing Security And Performance Of Deep Neural Networks, Azadeh Gholamrezazadeh Famili

All Dissertations

The significance of security is often overlooked until a catastrophic event occurs. This holds for the security of existing IoT devices. Numerous devices have been deployed and repurposed without adequately considering their security vulnerabilities. There is a lack of comprehensive security protocols for devices that frequently interact with one another. Even in emerging fields like machine learning (ML), which has found extensive applications in strategy optimization, decision-making, data classification, and other domains, discussions around security vulnerabilities are not widespread. Regarding security in ML, the focus tends to revolve around specific topics such as adversarial attacks. However, due to the remarkable …

Characterization Of The Effects Of The Pyrazolopyrimidine Inhibitor Grassofermata (Nav-2729) In The Eukaryotic Pathogen Trypanosoma Brucei, Kristina Marie Parman

All Dissertations

The protozoan pathogen, Trypanosoma brucei, is the causative agent of sleeping sickness in humans and nagana in livestock in sub-Saharan Africa. T. brucei cycles between tsetse fly and mammalian hosts, and it is adapted to survive in diverse host tissues. Variant Surface Glycoprotein (VSG) plays a key role in immune evasion in the mammalian host. The VSG membrane anchor requires two myristates, 14-carbon saturated fatty acids (FAs) that are scarce in the host. T. brucei can synthesize FAs de novo, but also readily takes up exogenous FAs, despite lacking homologs to fatty acid uptake proteins found in other …

Influence Of Photoreactor Design Parameters On The Performance Of Ultraviolet Light-Induced Degradation Of Per-And Polyfluoroalkyl Substances By Bismuth Oxy Hydroxy Phosphate And Hexagonal Boron Nitride Photocatalystsinfluence Of Photoreactor Design Parameters On The Performance Of Ultraviolet Light-Induced Degradation Of Per-And Polyfluoroalkyl Substances By Bismuth Oxy Hydroxy Phosphate And Hexagonal Boron Nitride Photocatalysts, Mojtaba Qanbarzadeh

All Dissertations

The main objective of this study is to evaluate the practical applicability of heterogeneous photocatalysis technology powered by ultraviolet (UV) photons for the degradation of per and -polyfluoroalkyl substances (PFAS) in contaminated groundwater samples. For this purpose, bismuth oxyhydroxy phosphate (BOHP) and hexagonal boron nitride (hBN) were utilized as the main photocatalysts in slurry photodegradation systems. BOHP (Bi₃O(OH)(PO₄)₂) is a wide bandgap semiconductor with high activity for degrading long-chain perfluorocarboxylic acids (PFCAs) in mild operational conditions. Boron nitride (BN) is another wide bandgap semiconductor material that was used in this study due to its …

Citrate Hydrogels For Regenerative Medicine Applications, Mark Pitman

All Dissertations

Regenerative medicine focuses on restoring cells and tissues to re-establish proper function. Hydrogels are a customizable and adaptable set of materials that can be engineered as tools for regenerative medicine. My research has focused on developing and applying biomaterials to spinal cord injury and chronic wounds. Spinal cord injury and chronic wounds share pathophysiological issues with oxidative stress, excess free, and macrophage polarization. Furthermore, both conditions lack robust, effective treatments. We hypothesized that citrate hydrogels – hydrogels that contain citric acid as a functional component – would provide radical scavenging and iron chelation that would benefit both conditions. The hydrogels …

Making The Move Toward Meaningfulness In Learning Activities: Enhancing Teacher Self-Efficacy In Student Engagement Through An Instructional Coaching Approach In Improvement Science, Maureen Tiller

All Dissertations

Student engagement is a common problem in schools today and a challenging one to solve. Choosing to dive deeper into this complex problem at one high school, ten teachers participated in a coaching cycle designed to impact self-efficacy in student engagement with the support of the school’s instructional coach in collaboration with the principal. One overarching research question guided this improvement science study: What impact does an instructional coaching cycle focused on meaningfulness in learning activities have on teachers’ self-efficacy in student engagement? To answer the research question, I conducted a quantitative and qualitative data analysis of pre- and …

Integrated Techniques To Identify And Characterize Resistance To Fusarium Wilt Caused By Fusarium Oxysporum, F. Sp. Vasinfectum Race 4 In Two Domesticated Gossypium Species, Stephen Parris

All Dissertations

Fusarium wilt of cotton (Gossypium hirsutum and G. barbadense), caused by Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4), is the most threatening disease faced by today’s cotton breeders. During the past 20 years, over $7 million have been dedicated to efforts in breeding upland cotton for resistance to FOV4 while yielding little to no results. To counteract this, we conducted a study in Clint, TX, that utilized control plots and geostatistical methods to adjust phenotypic data for the heterogeneous distribution of FOV4 in the field, improving the accuracy of genetic resistance assessments. Concurrently, early-generation genetic mapping in …

Developing Recommendations For Broad Mite, Polyphagotarsonemus Latus Banks, In Blackberry, Rubus Subgenus Rubus, Jared Bradley Linn

Graduate Theses and Dissertations

Broad mite, (Polyphagotarsonemus latus Banks) (Acari: Tarsonemidae), is an economically important pest of blackberry production across the world. Since it was first reported on primocane-fruiting blackberries in 2010, little work has gone into developing IPM tools and understanding impact on floricane-fruiting cultivars. The objective of this thesis was to evaluate the effect of broad mite feeding on floricane-fruiting cultivars of blackberry, develop an efficient and accurate field scouting strategy, and investigate the impact of cultivar and trellising technique on the development of broad mite populations. Experiments consisted of evaluating floricane fruiting cultivars by quantifying broad mite populations and cataloging their …

Effects Of Seasonal Environment On Abundance, Behavior, Visual Signaling, And Perception In Prairie Butterflies, Grace Elizabeth Hirzel

Graduate Theses and Dissertations

Phenotypic plasticity is a widespread mechanism that allows animals to respond quickly to seasonal changes in their environment. However, the depth and complexity of these plastic responses is still being discovered. One aspect of seasonal physiology that is relatively unstudied is changes to sensory physiology and how it may explain changes in behavior. To determine how changes in seasonal conditions affect behavior, coloration, and vision, I examined populations of wild butterflies in Northwest Arkansas. Focusing on a single species, the common buckeye Junonia coenia, I found that seasonal coloration covaries with thermoregulating behavior and is accompanied by changes in visual …

Impact Of Reducing Ammonia Concentration By Ozone Technology And Its Potential Improvement On Broiler Performance, Odilpio Quintana Ortega

Graduate Theses and Dissertations

The employment of ozone in livestock production as a means of mitigating ammonia is used for enhancing air quality within animal confinement facilities, such as swine or poultry barns. Ammonia is a byproduct of animal excrement. Elevated ammonia concentrations can adversely affect the well-being of both animals and humans. The aim of this thesis was to investigate the effects of Ozone Technology Machine Unit (OTMU) utilization in poultry barns regarding ammonia concentration and its potential benefit in terms of broilers performance and welfare. In recent years, there has been a significant boom in technological advances. New devices that help mitigate …

Geochemistry Of Metal-Rich Black Shales And Their Genetic Relationship To Mississippi Valley-Type Pb-Zn Ore Deposits, Midcontinent U.S., Noah S. Morris

Graduate Theses and Dissertations

The formation of Mississippi Valley-type (MVT) lead-zinc (Pb-Zn) ores is complex, involving an interaction of tectonic compression, hydrothermal fluid migration, and geochemical processes within the subsurface. Fundamental questions regarding this interaction remain unclear, including the source(s) of the Pb and Zn ions that make up the ores. A genetic link between black shales and MVT ores has been thought to exist because of (1) the presence of mature hydrocarbon and brine fluid inclusions within many MVT ores, (2) the association of the hydrothermal fluids that are linked to MVT ore formation with organic compounds and oil-like droplets, and (3) the …

A Generic Qualitative Inquiry Of The Challenges For Black African American Men Who Have Experienced Trauma, Randall Lee Maurice Shakir

Graduate Theses and Dissertations

Black African American Men (BAAM) suffer disproportionately from trauma related challenges and have a higher risk of encountering trauma across the lifespan. The negative impact of trauma is a major public health concern in the United States, evidence suggests trauma negatively impacts the physical well-being, mental health, and mortality rate. BAAM have increased rates of trauma exposure and their traumatic experience is historically complex involving a variety of contemporary issues (i.e. Adverse Childhood Experiences (ACEs), depression, victimization and desensitization, stress). This research aims to explore the complex nature of their trauma-related challenges among a purposeful sample of BAAM participants in …

Social Media And Mental Health: The Public Health Impact And Future Policy Directives, Renae A. Merrill

Graduate Theses and Dissertations

The relationship between social media use among young people and the increasing concerns of mental health problems in the U.S. and globally is on systemic agendas. Furthermore, research on social media use and mental health indicate reasons to suspect a causal relationship, but more work needs to be done. Therefore, this three-article dissertation seeks to explore (1) associations between social media use, personality, and depression; (2) associations between social media emotional support, anxiety, and personality; and (3) the relationship between social media use and mental health using Deborah Stone’s causal stories framework. Findings from this study provide an improved understanding …

Geospatial Analysis Of Weathering And Recession On Architectural Limestone At The 1891 Powerhouse/Icehouse In Eureka Springs, Arkansas, Stuart Bruce Wright

Graduate Theses and Dissertations

The objective of this study of the architectural limestone of the 1891 Powerhouse/Icehouse in Eureka Springs, Arkansas was to analyze the environmental factors that influenced the deterioration and surface recession of this historical stone structure. The focus of this research was to examine and establish a baseline study that may assist in future monitoring and documentation of this historic limestone structure on stone weathering. A replicable methodology was specifically created toward this baseline research in hopes that it represented a solid baseline study. Observations and data analyses revealed the relationship between the architectural limestone building structure and the dominating recession …

Becoming A Father, Staying A Father: An Examination Of The Cumulative Fatherhood Wage Premium To U.S. Residential Fathers, Ohjae Gowen

Research Collection School of Social Sciences

The instability of fathers’ co-residence with children has become an increasingly prevalent experience for U.S. families. Despite long-standing scholarship examining the relationship between fatherhood and wage advantages, few studies have investigated how variation in fathers’ stable co-residence with a child may produce temporal changes in the wage premium over the life course. Building on prior explanations of the fatherhood wage premium, I test if the wage premium grows with time since the birth of a resident child and if the premium depends on fathers’ co-residence with a child. I use marginal structural models with repeated outcome measures and data from …

The Developmental Process For Adenoviral Vectored Canine Influenza Vaccines, Nicholas Jeanjaquet

School of Biological Sciences: Dissertations, Theses, and Student Research

Canine Influenza Virus (CIV) is a recently emerged branch of Influenza A virus that is highly infectious in dogs. The first strain was isolated in 2003, and it has quickly become endemic in areas with dense dog populations, most notably in Asia. The proximity of dogs to humans, along with their potential to serve as mixing vessels for reassortment, raises concern for possible zoonotic transmission and a potential human pandemic. Available vaccines are not frequently updated and struggle to prevent the spread of currently circulating strains. This highlights the need for a new and more effective vaccine. We outline the …

Sars-Cov-2 Seroprevalence In Pregnant Women In Kilifi, Kenya From March 2020 To March 2022, Angela Koech, Geoffrey Omuse, Alex Mugo, Isaac Mwaniki, Joseph Mutunga, Moses Mukhanya, Onesmus Wanje, Grace Mwashigadi, Geoffrey Katana, Marleen Temmerman

Centre of Excellence in Women and Child Health

Background: Seroprevalence studies are an alternative approach to estimating the extent of transmission of SARS-CoV-2 and the evolution of the pandemic in different geographical settings. We aimed to determine the SARS-CoV-2 seroprevalence from March 2020 to March 2022 in a rural and urban setting in Kilifi County, Kenya.

Methods: We obtained representative random samples of stored serum from a pregnancy cohort study for the period March 2020 to March 2022 and tested for antibodies against the spike protein using a qualitative SARS-CoV-2 ELISA kit (Wantai, total antibodies). All positive samples were retested for anti-SARS-CoV-2 anti-nucleocapsid antibodies (Euroimmun, ELISA kits, NCP, …

Metabox: A Benchmark Platform For Meta-Black-Box Optimization With Reinforcement Learning, Zeyuan Ma, Hongshu Guo, Jiacheng Chen, Zhenrui Li, Guojun Peng, Yue-Jiao Gong, Yining Ma, Zhiguang Cao

Research Collection School Of Computing and Information Systems

Recently, Meta-Black-Box Optimization with Reinforcement Learning (MetaBBO-RL) has showcased the power of leveraging RL at the meta-level to mitigate manual fine-tuning of lower-level black-box optimizers. However, this field is hindered by the lack of a unified benchmark. To fill this gap, we introduce MetaBox, the first benchmark platform expressly tailored for developing and evaluating MetaBBO-RL methods. MetaBox offers a flexible algorithmic template that allows users to effortlessly implement their unique designs within the platform. Moreover, it provides a broad spectrum of over 300 problem instances, collected from synthetic to realistic scenarios, and an extensive library of 19 baseline methods, including …

Preparation Of Zein-Based Nanoparticles : Nanoprecipitation Versus Microfluidic-Assisted Manufacture, Effects Of Pegylation On Nanoparticle Characteristics And Cellular Uptake By Melanoma Cells, Jitkasem Meewan, Sukrut Somani, Jamal Almowalad, Partha Laskar, Margaret Mullin, Graeme Mackenzie, Swapnil Khadke, Yvonne Perrie, Christine Dufès

School of Medicine Publications

Background: The manufacture of nanoparticles using manual methods is hampered by its challenging scaleup and poor reproducibility. To overcome this issue, the production of zein nanoparticles entrapping a lipophilic drug model, coumarin-6, by using a microfluidic system was assessed in this study. The influence of PEG density and chain length on zein nanoparticle characteristics, as well as their uptake efficacy in melanoma cancer cells, was also evaluated.

Methods: Zein nanoparticles were prepared by both manual and microfluidic approaches to allow comparison between the two processes. PEGylated zein nanoparticles with various PEG densities and chain lengths were produced by …

Analyses Of Mybl1 In Triple Negative Breast Cells And Validation Of Genes Colocalized To Chromosome 8q Loci, La Tajia D. Thirston

Theses (2016-Present)

Fifteen percent of breast cancer are characterized as the triple negative breast cancer subtype. The cancers are recognized as negative for estrogen, progesterone and ErRB2 receptors, genes that function as transcription and growth factor functions, respectively. Previous data show the MYBL1 transcription factor is over-expressed in some triple negative breast cancers-suggesting dysregulation of the gene in the cancers. MYBL1 gene is a strong transcriptional regulator associated with regulation of cell cycle proliferation which is a key event in cancer progression. To determine genes either directly or indirectly associating with MYBL1 in these cancers we knocked the gene down, performed microarray …

Molca: Molecular Graph-Language Modeling With Cross-Modal Projector And Uni-Modal Adapter, Zhiyuan Liu, Sihang Li, Yanchen Luo, Hao Fei, Yixin Cao, Kenji Kawaguchi, Xiang Wang, Tat-Seng Chua

Research Collection School Of Computing and Information Systems

Language Models (LMs) have demonstrated impressive molecule understanding ability on various 1D text-related tasks. However, they inherently lack 2D graph perception — a critical ability of human professionals in comprehending molecules’ topological structures. To bridge this gap, we propose MolCA: Molecular Graph-Language Modeling with Cross-Modal Projector and Uni-Modal Adapter. MolCA enables an LM (i.e., Galactica) to understand both text- and graph-based molecular contents via the cross-modal projector. Specifically, the cross-modal projector is implemented as a QFormer to connect a graph encoder’s representation space and an LM’s text space. Further, MolCA employs a uni-modal adapter (i.e., LoRA) for the LM’s efficient …

Through The Lens Of A Naturalist: How Learning About Nature Promotes Nature Connectedness Via Awe, Shu Tian Ng, Angela K. Y. Leung, Sarah Hian May Chan

Research Collection School of Social Sciences

Environmental educators stress the importance of engaging with the wonders of the Earth in promoting nature connectedness. However, it remains unclear if learning about nature has an incremental effect beyond mere exposure to nature and what psychological mechanism can explain such a learning effect if it exists. To fill this gap, we propose a mediation model in which learning about nature promotes a sense of awe—a self-transcendent emotion associated with the recognition of vastness in nature. A sense of awe, in turn, promotes nature connectedness. Study 1 employed a cross-sectional survey and offered preliminary support for the proposed model, with …

When Social Status Gets In The Way Of Mating: The Incompatibility Between Social Status And Reproductive Goals In Modern Contexts, Jose C. Yong, Amy J. Y. Lim, Norman P. Li

Research Collection School of Social Sciences

Low fertility is a growing concern in modern societies. While economic and structural explanations of reproductive hindrances have been informative to some extent, they do not address the fundamental motives that underlie reproductive decisions and are inadequate to explain why East Asian countries, in particular, have such low fertility rates. The current paper advances a novel account of low fertility in modern contexts by describing how modern environments produce a mismatch between our evolved mechanisms and the inputs they were designed to process, leading to preoccupations with social status that get in the way of mating and reproductive outcomes. We …