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Investigation Ionic Polymer Metal Composite Capacitors through Fabrication, Experimentation, and Modeling
No full textThe increasing demand for greater energy storage capacity alongside the need to minimize the size of various devices, such as hybrid electric vehicles, medical devices, and pulsed power systems—has highlighted the necessity for advanced polymer film capacitors with high energy density. While traditional batteries and electronic devices have generally sufficed for many applications, their inherent size limitations hinder their ability to deliver the high levels of peak power required for certain demanding applications. This shortfall highlights the critical ongoing challenge within the energy storage sector to improve technology and more effectively meet these growing power requirements. Flexible Ionic Polymer Metal Composites (IPMCs) fabricated utilizing platinum (Pt) or gold (Au) are studied for their applicability as Solid Polymer Electrolyte (SPE) membranes for high--power capacitors, as they have demonstrated improved electrical and mechanical properties as electronic devices.
IPMCs are types of Electroactive Polymers (EAPs) that display large deflections in response to small electric fields or voltages. IPMCs are characterized by significant displacements, but low-density forces. Also, until recently, research on IPMC materials primarily focused on their potential as actuators. However, one of the most intriguing applications of IPMC now being explored is its use in energy storage capacitors. Furthermore, the exceptional properties of IPMC- for instance, soft, high flexibility, low weight, and the potential to reach high energy density- make it an ideal candidate to replace conventional capacitors or energy storage devices. In this research, sandwich structured IPMCs were designed and fabricated. The samples for this study were fabricated utilizing the chemical reduction process (impregnation-reduction or chemical deposition) because of good surface strength achieved using this method. The mechanism behind an IPMC’s energy storage abilities rests in its capability to store charges on its surface through the mobilities of ions. When an electric potential is applied to the material, the ions inside the polymer matrix travel towards one electrode of the IPMC, resulting in charge accumulation on the surface. IPMC can be charged and discharged quickly with little to no degradation in performance.
This dissertation targeted to improve the fundamental understanding of recently observed phenomena in flexible energy storage devices. It explored the influence of key fabrication parameters, temperature variations, and different solutions on the performance of the IPMC capacitors. The electrochemical performance of IPMC capacitors was thoroughly investigated under various mechanical loadings, particularly tension and bending, to understand their behavior and characteristics.
One primary objective of this study was to assess the impact of defects or cracks induced by tensile loading on both the mechanical properties and electrochemical behavior of the IPMC-based capacitors. During tensile testing, the deformation experienced by the IPMC strips led to alterations in the ion distribution and concentration within the polymer matrix, thereby influencing the material’s performance. Electrochemical Impedance Spectroscopy (EIS) was employed to measure these changes at room temperature across a frequency range of 10 KHz to 1 Hz, offering a straightforward and efficient method with consistent results. It was observed that the capacitance of the IPMC capacitor increased notably after significant cracking occurred in the platinum electrodes because of high tensile mechanical loads. Additionally, at lower frequencies (\u3c100 \u3eHz), both the real (ε\u27) and imaginary (ε ) parts of permittivity exhibited an increase with the addition of loads, indicating a notable impact on the dielectric properties of the material. However, it was noted that at frequencies above 100 Hz, the permittivity showed weak dependence on the applied loads. Another aspect of the investigation involved analyzing the functionality of the capacitor under a wide spectrum of bending angles, ranging from 0 C to 100 C.
Through this work, this research underscored the IPMC capacitor’s adaptability to flexibly to diverse bending angles, making it particularly suitable for applications where traditional rigid capacitors may prove impractical or inefficient. Furthermore, the study contributed to the body of knowledge by employing advanced testing methods to evaluate the mechanical and electrochemical performance of this flexible capacitor under various conditions. The experimental findings were corroborated and further investigated using the COMSOL Multiphysics model to explore the characteristics of the surface electrodes
Leveling the Playing Field: An Ethnographic Study of Latinx Youth Soccer Leagues in Las Vegas
No full textThis study examines how youth sports privatization, family dynamics, coaching, and team organization affect Latinx youth’s opportunities and interests in playing competitive soccer. It also examines the role that soccer plays in identity-making for Latinx people in Las Vegas, if and how they use these soccer spaces to develop kinship ties and build community, and it documents how these soccer spaces are developed as counter-spaces. I employ Critical Ethnography paired with 36 interviews with youth and adults. I observed two club soccer teams and one soccer league in Las Vegas (the league was a public community league that primarily caters to the Latinx population in Las Vegas) to gain a better understanding of the different types of teams and leagues that operate in Las Vegas, who plays in these leagues and why, and what their experiences in these respective teams and leagues are.
SC is a large club team whose goal is to become a nationally recognized academy. It is located in the general downtown Las Vegas area. They set themselves apart from other teams by having access to the highest quality facilities, coaches, and training environments. While classified as a non-profit, participation in the club is expensive as it competes in multiple tournaments throughout the year. Justice FC is also part of the same league as SC, but its focus and target are slightly different. They focus on low income and Latinx communities and their mission is to ensure the local low-income soccer community has a chance to play club soccer. The Spanish Soccer League (SSL) refers to a local Las Vegas community league that offers low- cost soccer participation for youth and adults. The league has 15 youth teams and 40 adult teams. The Spanish Soccer League is relatively low cost for youth and adult teams as there is no registration fees, participants only have to pay referee fees.
Participants across the board (coaches, parents, and youth) indicated that the high costs of sport participation limits opportunities for youth. I explain how the high costs of sport participation are making it difficult for families and youth to participate in soccer. Despite the costs of participation, some families and youth continue to view soccer participation as a vehicle for social mobility. Among Latinx participants, some viewed soccer as an opportunity for advancement and social mobility while others were happy to participate in the sport because of the sense of community and joy they experienced through it. I discuss how soccer spaces offer people from the Latinx community the opportunities to maintain a sense of their ethnic identity and build kinship ties. Overall, more work is needed on finding ways to make sport participation in general—and soccer participation specifically—more affordable for families from lower economic statuses
Integrated Transcriptomics and Proteomics Study of Starvation Selected Drosophila Melanogaster
No full textDrosophila melanogaster, selected for starvation resistance exhibits phenotypic traits such as increased body size, slower development, reduced fecundity and obesity like characteristics including higher lipid reserves and cardiac dysfunction. While prior studies have explored the metabolic and biochemical changes in these flies, the underlying genetic and molecular mechanisms remain unclear. This study aims to investigate the gene expression and protein abundance in starvation-selected Drosophila through RNAseq, proteomics, and integrating both datasets using the MixOmics package in R. I found differential gene expression in the fat body at the third instar larval stage, particularly in pathways related to lipid metabolism, calcium signaling, and immune regulation, with a potential role for long non-coding RNAs (lncRNAs). Proteomic analysis identified several differentially abundant proteins related to mitochondrial form and function, and energy homeostasis. Though there was a modest correlation of the datasets, the integration of two suggested a robust activation of metabolic pathways promoting energy storage. The mixomics identified transcription factor gene SREBP and Idh as a key player of lipid metabolsim in Drosophila. This study highlights the potential of multiomics integration to understand various complex physiologies and metabolic disorders
Assessing Disinfection Byproducts in Diverse Water Sources: Factors Affecting Formation and Accuracy in Direct and Indirect Analysis
No full textWater is a critical resource that supports economic growth, ecosystem health, food security, and overall human well-being. However, water scarcity poses significant challenges globally, affecting more than two billion people and causing conflicts, health issues, and economic instability. Water scarcity in the Southwest U.S., particularly in Las Vegas, is worsening due to drought and reliance on diminishing sources like the Colorado River. Alternative water sources, such as stormwater runoff and reclaimed water, are increasingly used but may introduce impurities, including organic matter from urban runoff and wastewater. This organic matter can form disinfection byproducts (DBPs) when treated with chlorine, including harmful regulated compounds like trihalomethanes (THMs) and haloacetic acids, as well as unregulated emerging contaminants like haloacetonitriles (HANs) and nitrosamines. Many of these DBPs are potential carcinogens, highlighting the need for a deeper understanding of their sources and impacts on water quality and public health.
This dissertation addresses three interrelated issues concerning DBP formation and measurement. The first issue examines the effects of unsheltered homelessness, urban runoff, and wastewater effluent on DBP formation potential (FP) in a tributary that feeds Lake Mead. The second issue investigates the kinetics of various quenching agents (QAs) used to halt DBP formation, as well as the impact of QAs on DBP stability. Lastly, the research explores how these QAs and chlorine affect fluorescence excitation-emission matrices (EEMs), providing insights into changes in water quality. Overall, the study aims to enhance understanding of DBP formation and the effectiveness of QAs for accurate water quality assessments.
The first task investigated the impact of unsheltered homelessness, urban runoff, and wastewater effluent on DBP FP in Lake Mead and a tributary. The study found significant correlations between water quality parameters such as UV254 absorbance, total organic carbon (TOC), and chlorine demand with THM and HAN FP, demonstrating their effectiveness as surrogates for DBP formation. Notably, wastewater effluents significantly influenced THM and HAN FP compared to non-wastewater impacted locations. Furthermore, central and northern wash sites, which are affected by unsheltered homelessness but not by wastewater discharge, also showed a substantial presence of THM and HAN precursors. The mass loading calculations for THM and HAN FP revealed the extent of wastewater treatment’s role in reducing contaminant concentrations and improving water quality. These findings highlight the intricate relationship between urban water quality, public health, and the broader implications of homelessness on water management and policy.
Task 2 examined the effectiveness of various QAs in reducing free chlorine and preventing the formation of DBPs during FP tests. QAs tested included ascorbic acid (AA), sodium bisulfite, sodium thiosulfate, sodium arsenite, 1,3,5-trimethoxybenzene (TMB), and ammonium chloride (AC), at chlorine concentrations of 3, 5, and 9 mg/L and molar ratios of 1:1, 1.3:1, 1.5:1, and 1.7:1 for QA:chlorine. At a 1:1 ratio, most QAs reduced chlorine by about 80% within 45 to 60 seconds, except for AC and TMB. Increasing the ratio to 1.7:1 improved quenching times to 10-20 seconds, with most QAs achieving over 80% reduction in 10 seconds. Kinetic analysis showed lower than expected rate constants for AC and TMB, with TMB showing minimal reduction even after five minutes. DBP levels remained stable over 24 hours in quenched samples, suggesting reliable measurements when QAs were used below 1.7:1 molar ratios.
In the final task, the effects of various QAs on the fluorescence peaks of EEMs were examined. Chlorine concentrations of 3, 5, and 9 mg/L were tested, using QA:chlorine molar ratios of 1:1 and 1.7:1 for all QAs. The study assessed the impact of chlorine on major fluorescence peaks (A, M, C, B, and T) in EEMs, revealing that the error percentage increased with higher chlorine concentrations for all peaks. Furthermore, the individual effect of QAs, as well as the combined influence of chlorine and QAs, was evaluated. Results showed statistically significant changes, with error measurements ranging from 30% to 90% across nearly all peaks.
Key findings highlight that increased organic matter from urban pollutants and wastewater significantly raises DBP FP, with implications for water safety. The kinetics of QAs vary, impacting their effectiveness in stopping DBP formation and their influence on fluorescence measurements
From Resistance to Host Response: An Integrative Study of C. difficile Infections
No full textClostridioides difficile infection (CDI) is a major healthcare challenge, causing severe gastrointestinal illness and significant mortality. Understanding the mechanisms of antibiotic resistance, epidemiology, and immune response in CDI is critical for developing effective treatments and prevention strategies.
This dissertation encompasses three complementary studies. The first study investigates the genetic mechanisms underlying cephalosporin resistance in C. difficile strain 630 through differential gene expression analysis. The second study provides a descriptive epidemiological analysis of C. difficile ribotypes in a Las Vegas patient population, highlighting differences between healthcare-associated (HA-CDI) and community-associated (CA-CDI) cases. The third study integrates serum analyte profiling and transcriptomic analysis to explore the differential immune responses in CDI, with a focus on the role of sex hormones.
The gene expression analysis identified several putative antibiotic resistance genes, including blaCDD, significantly upregulated in response to cephalosporin exposure, though deletion of these genes did not significantly affect cephalosporin resistance. These findings suggest an intrinsic resistance mechanism in C. difficile. The epidemiological study revealed diverse ribotypes with distinct distributions between HA-CDI and CA-CDI cases, with ribotype 027 being notably prevalent in healthcare settings. The integrative analysis of serum analytes and transcriptomics showed distinct hormone and cytokine profiles correlating with CDI severity and recovery, suggesting that hormonal fluctuations significantly influence immune responses.
This multi-faceted approach provides comprehensive insights into the genetic, epidemiological, and immunological aspects of CDI. The findings emphasize the need for alternative therapeutic strategies to combat antibiotic resistance, and continuous surveillance to manage CDI outbreaks. These integrated insights can guide the development of more effective interventions for preventing and treating CDI
It’s Time to Turn the Page: A Thematic Analysis of Award-Winning African American Picturebooks
No full textThe world of children’s literature is often a child’s first introduction to reading. In an increasingly diverse society, children must see themselves and others represented positively in literature. The Coretta Scott King Book Award is awarded to African American authors and illustrators who create books about human values and African American culture. Research examines the portrayal of African Americans in award-winning books, but more current and extended research is needed to investigate themes across award-winning children’s literature. This research study aimed to identify the most prevalent themes in Coretta Scott King Book Award-winning books and the depiction of these themes in the text and images. This qualitative study used critical content analysis to identify themes across the Coretta Scott King Book Award-winning picturebooks published between 1990 and 2024
Delineating Genetic Influences on Neurodegenerative Disorders and Infectious Diseases Through Advanced Computational Methods
No full textGenetics plays a critical role in understanding the molecular mechanisms underlying neurodegenerative disorders and pathogen evolution in infectious diseases. For example, identifying genetic variants associated with a disease phenotype uncovers functional pathways that could lead to potential drug targets and therapeutic interventions. In addition, tracking the genetic evolution of pathogens enables early detection and warning of infectious disease outbreaks. In both applications, given the large amount of genetic data, advanced computational methods, including longitudinal and multivariate models, could significantly boost the statistical power and capture interrelationships among traits, environmental factors and genetic influences. This dissertation focuses on four applications of longitudinal and multivariate approaches in examining genetic influences on complex disorders and addresses two primary objectives: maximizing sample inclusion for improved statistical power and integrating comprehensive feature sets to explore multivariate relationships. More specifically, longitudinal mixed effect models or longitudinal genome wide association study methods are utilized to capture novel genetic contributions, or genetic and environmental interactions towards phenotypes in Alzheimer’s disease (AD) and repetitive head impact (RHI) induced Chronic traumatic encephalopathy (CTE) in relatively small sample sizes. Multivariate predictive models are adopted to classify AD neuropathological status with imaging genetic features. Lastly, unsupervised multivariate pipelines are developed to uncover clustered mutation patterns in the SARS-CoV-2 genome that could enable early warnings of a potential outbreak. Taken together, results from this dissertation could contribute to precision medicine approaches in neurodegenerative disorders and enhance public health surveillance capabilities for infectious diseases
Harnessing NLP and Large Language Models for Pattern Discovery and Information Extraction in Electric Health Reports
No full textIn this work, we report on a series of natural language processing tools and models to improve the efficiency and accuracy of information discovery from clinical trials and pharmacological studies. Our main contributions are: 1. The development of an open-source platform Tri-AL that • Enables dynamic tracking of clinical trials information over time, • Excels in data visualization and user interaction with a particular emphasis on enhancing the analysis and representation of race and ethnicity data to foster equity in clinical research, and • Includes a predictive model utilizing machine learning to decipher drug mechanisms of action. 2. Heterogeneous Graph Neural Network for Gene-Chemical Entity Relation Extraction: We created a supervised deep learning model that adapts a heterogeneous Graph Neural Network to extract gene-chemical components. This model augments word representations using message passing that accurately identifies gene-chemical named entities and their relationships class. 3. Bipartite Graph Model for Evaluating Summarization Performance: We proposed a bipartite graph model to evaluate the performance of large language models in summarizing clinical trials. This model provides a robust framework to assess the accuracy and effectiveness of automated summarization tools in the medical domain
Addressing Low Molecular Weight Chemical Peaking Events During Direct Potable Reuse by Granular and Biological Activated Carbon
No full textDirect Potable Reuse (DPR) is an innovative solution designed to address water scarcity by treating wastewater to directly produce safe drinking water. As droughts and water shortages become more frequent, DPR offers a sustainable and localized water supply by incorporating advanced treatment processes. DPR systems typically rely on a combination of technologies such as ozone followed by biological activated carbon (O3/BAC), reverse osmosis (RO), and advanced oxidation processes (AOPs) to remove a wide range of contaminants. However, low molecular weight organic compounds (LMWCs), particularly volatile organic compounds, can sometimes pass through RO membranes and AOP systems.
California\u27s DPR regulations currently adopt these advanced treatment techniques to maintain the highest water quality standards, but opportunities exist to optimize treatment processes for enhanced removal of LMWCs. This study investigates the potential for altering the treatment train by replacing O3/BAC (deployed pre RO) and changing the process location (post RO) with granular activated carbon (GAC) or BAC to better target LMWCs. Both coconut shell- and coal-based GACs were tested with RO permeate through isotherm experiments for their efficacy in the removal of 1,2-dichloroethane (1,2-DCA) Additionally, rapid small-scale column tests (RSSCTs) were conducted over a 20-month period, during which LMWCs, including acetone, formaldehyde, methyl tert-butyl ether (MTBE), 1,2- DCA, and 1,2,3-trichloropropane (1,2,3-TCP), were intermittently spiked at ~5,000, ~17,000, and ~42,000 bed volumes with concentrations ranging from 50 to 300 g/L.
Coconut shell-based GACs proved to have higher adsorption performance on the LMWCs based on isotherm testing. RSSCTs results indicated that GAC is effective at removing MTBE, 1,2-DCA, and 1,2,3-TCP, with removal rates exceeding 99%. Conversely, highly hydrophilic compounds like acetone and formaldehyde were less effectively removed by GAC alone. The conversion of the GAC to BAC (post RO) demonstrated the removal of biodegradable LMWCs, i.e., acetone and formaldehyde, suggesting that the GAC to BAC conversion could provide removal for a broader range of LMWCs. Optimizing treatment trains by integrating both GAC and BAC technologies post RO has the potential to enhance the reliability and sustainability of DPR systems, ensuring safer drinking water and promoting more efficient resource use in the context of increasing water scarcity, and should be investigated for future work
Let’s Get in (Racial) Formation: A Three-Paper Exploration of Dual- and Multiple-Designated Minority-Serving Institutions
No full textIn 2015, a bipartisan, bicameral bill was proposed to amend Title III of the Higher Education Act to “strengthen minority-serving institutions” by allowing institutions awarded a Title III grant to receive concurrent funding from other sections under Titles III and V (Minority-Serving Institution Fairness Act, H.R. 4098 114th Cong., 2015; Minority-Serving Institution Fairness Act, S. 2317 114th Cong., 2015). While the identical bills never made it out of committees, they point to a legislative conundrum: institutions are forced to choose between grants despite meeting eligibility for more than one Minority-Serving Institution (MSI) classification. This issue is more pronounced as institutions racially diversify and meet the federal criteria for two or more enrollment-based MSI designations, such as being a dual-designated Asian American and Native American Pacific Islander-Serving Institution (AANAPISI) and Hispanic-Serving Institution (HSI), institutions meeting criteria that is contingent, in part, on racial enrollment thresholds. Yet, beyond this funding restriction, institutions may still be grappling (or not) with even being an MSI generally, let alone grappling with being MSIs tied to specific racially minoritized student bodies.
Race is constantly being (re)made. In this three-paper dissertation, I argue that dual- and multiple-designated MSIs are critical, emerging sites of racial formation in the United States. I project that institutions are increasingly meeting dual or multiple MSI designations and hypothesize that as institutions increasingly become dual- or multiple-designated, this can intensify racial phenomenon (e.g., race-making, reifying or reorganizing racial hierarchies and positions). Situating this legislative conundrum and its implications against a backdrop of racial logics (e.g., monoracial normativity or monoracialism; Ford et al., 2021; Johnston-Guerrero & Renn, 2016), the overall purpose of this inquiry is to explore (a) the current landscape context of and institutional variation among and within multiracial dual- and multiple-designated MSIs; (b) the racial logics undergirding the charge of MSI policy in the Higher Education Act; and (c) how institutions negotiate meeting dual and multiple MSI designations.
First, I chart institutional characteristics and diversity among and within dual- and multiple-designated MSIs and report any trends over time. Then, turning to MSI policy in the current version of the Higher Education Act and using Critical Race Discourse Analysis or Critical Discourse Analysis grounded in Critical Race Theory (CRT; Delgado & Stefancic, 2017; Matsuda et al., 1993) and drawing on relational race formation (Molina et al., 2019), I explore how race is (re)made in federal policies. Finally, using differential racialization from CRT (Delgado & Stefancic, 2017) and relational race formation (Molina et al., 2019), I explore how institutions negotiate dual and multiple designations through an exploratory multiple case study of four public AANAPISI-HSIs across three U.S. Census Divisions (i.e., East North Central, Mountain, Pacific) drawing on the perspectives of key campus actors involved in MSI efforts as my primary data source. I attend to how institutions negotiate designations that are racially minoritized themselves, as well as how institutions negotiate these racially minoritized designations in relationship to one another.
Together, these separate and interrelated studies exploring dual- and multiple-designated MSIs highlight the role of overarching racial logics, federal policy, and key campus actors in racial formation or race-making. I offer implications for policy, practice, and research, including ideas around how cross-racial coalitions can better contribute to collective advocacy for investing in and strengthening MSIs