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Cleaner Futures: Covalent Organic Frameworks for Sustainable Degradation of Lignocellulosic Materials

As countries pledge their commitment to a net-zero future, much of the previously forgotten climate change research were revitalized by efforts from both governmental and private sectors. In particular, the utilization of lignocellulosic materials saw a special spotlight in research interest for its abundance and its carbon removal capability during photosynthesis. The initial effort in mimicking enzymatic active sites of β-glucosidase will be explored. The crystalline covalent organic frameworks (COFs) allowed for the introduction of a variety of noncovalent interactions, which enhanced the adsorption and the catalytic activity against cellobiose and its glycosidic bonds. The physical processes associated with this reaction, such as the kinetics, equilibrium, and activation energies, will be closely examined and compared with existing standard materials and comparable advanced catalysts. In addition, several variants of COFs were synthesized to explore the effect of various noncovalent interactions with cellobiose. A radical-bearing COF was synthesized and characterized. The stability of this radical was examined by electron paramagnetic resonance spectroscopy (EPR) and its oxidative capability tested with model lignin and alcoholic compounds. The reaction products are monitored and identified using gas chromatography-mass spectroscopy (GC-MS). An oxidative coupling of phenol was explored, and its initial results are presented in chapter 5.
Date: May 2023
Creator: Lan, Pui Ching
System: The UNT Digital Library

In-situ Electrochemical Surface Engineering in Additively Manufactured CoCrMo for Enhanced Biocompatibility

Laser-based additive manufacturing is inherently associated with extreme, unprecedented, and rapid thermokinetics which impact the microstructural evolution in a built component. Such a unique, near to non-equilibrium microstructure/phase evolution in laser additively manufactured metallic components impact their properties in engineering application. In light of this, the present work investigates the unique microstructural traits as a result of process induced spatial and temporal variation in thermokinetic parameters in laser directed energy deposited CoCrMo biomedical alloy. The influence of such a unique microstructural evolution in laser directed energy deposited CoCrMo on electrochemical response in physiological media was elucidated and compared with a conventionally manufactured, commercially available CoCrMo component. Furthermore, while investigation of the electrochemical response, such a microstructural evolution in laser directed energy deposited CoCrMo led to in-situ surface modification of the built components in physiological media via selective, non-uniform electrochemical etching. Such in-situ surface modification resulted in enhanced biocompatibility in terms of mammalian cell growth, cell-substrate adhesion, blood compatibility, and antibacterial properties indicating improved osteointegration, compared to a conventionally manufactured, commercially available CoCrMo component.
Date: May 2023
Creator: Mazumder, Sangram
System: The UNT Digital Library
The Effect of Formal Leadership Coaching Support on Principal Self-Efficacy (open access)

The Effect of Formal Leadership Coaching Support on Principal Self-Efficacy

Principals today face greater job complexities and more diverse challenges than ever before because of decreases in resources, funding, and district support, along with increases in accountability expectations, student diversity, and unfunded federal and state mandates. Principals today are tasked with myriad responsibilities ranging from facilities management and fiscal and legal concerns to instructional leadership and stakeholder relationships. The purpose of this study is to examine the role of formal, structured leadership coaching and engage in further inquiry to determine the effect of leadership coaching on principal efficacy in a complex and challenging educational environment. This convergent parallel mixed-method research approach is meant to determine if elementary principals' participation in formal leadership coaching programs increases their level of efficacy, as well as how different districts structure and implement these programs for the benefit of their administrators.
Date: May 2023
Creator: Heskett, Lori L.
System: The UNT Digital Library
Laser Powder Bed Fusion of H13 Tool Steel: Experiments, Process Optimization and Microstructural Characterization (open access)

Laser Powder Bed Fusion of H13 Tool Steel: Experiments, Process Optimization and Microstructural Characterization

This work focused on laser powder bed fusion (LPBF) of H13 tool steel to examine microstructure and melt pool morphology. Experiments were conducted with varying laser power (P) in the range of 90-180 W and scan speed (v) in the range of 500-1000 mm/s. layer thickness (l) and hatch spacing (h) were kept constant. Volumetric energy density (γ) was calculated using the above process parameters. In order to find a relation between the recorded density and top surface roughness with changing process parameters, set of equations were derived using the non-dimensional analysis. For any chosen values of laser power, scan speed, hatch spacing and layer thickness, these equations help to predict top surface roughness and density of LPBF processed H13 tool steel. To confirm the universal relation for these equations, data of In718 and SS316L processed in LPBF was input which gave a R-square of >94% for top surface roughness and >99% for density. A closed box approach, response surface model, was also used to predict the density and surface roughness which allows only in the parametric range. Material microstructures were examined to identify the melting modes such as keyhole, transition and conduction modes. X-ray diffraction data revealed that there …
Date: May 2023
Creator: Channa Reddy, Sumanth Kumar Reddy
System: The UNT Digital Library

Effects of Hypoxia Responses during Moderate- and Severe-Intensity Exercise Performed to Exhaustion

The purpose of the study was to investigate the effects of hypoxia responses during moderate- and severe-intensity exercise performed to exhaustion. Nine healthy university students, five men, and four women (mean ± SD, age, 23 ± 1 y; height 167 ± 8 cm; weight 73 ± 7 kg) performed a cycle ergometer test in normoxia and hypoxia conditions. Cardiorespiratory, metabolic, and perceptual responses were measured during moderate-intensity and during severe-intensity exercise. During moderate-intensity exercise, hypoxia exaggerates the cardiorespiratory and ventilatory responses and delays the attainment of the steady state VO2 kinetics. However, during severe-intensity exercise, compensatory responses were not adequate, oxygen demand was slightly increased and VO2 max was reduced in hypoxia affecting the overall performance. Therefore, the greater reliance on the anaerobic pathways could have a serious implication on the performance of the exercise over a wide range of intensities.
Date: May 2023
Creator: Kumawat, Mandeepa Mohanlal
System: The UNT Digital Library
Lived Experiences in the Pecan Capital of the World: Oral Histories with People of the San Saba Pecan Industry (open access)

Lived Experiences in the Pecan Capital of the World: Oral Histories with People of the San Saba Pecan Industry

The growth of the pecan industry in San Saba offers a microcosm into the evolution of the industry as a whole. Individual ingenuity in agriculture, business, and technology carved a path for success for the native nut in San Saba. Thanks in part to the efforts by founding families of the area and their descendants, the pecan has become a widely-used ingredient in holiday sweets of the American South and a symbol of Texas identity. Yet, the industry's development and the lives of the people who have cultivated it are stories that have remained largely untold. Through oral histories with family pecan growers, descendants of migrant farm laborers, and others working in the industry as well as primary sources such as those from early pecan sales catalogs, United States Department of Agriculture and other government documents, this project will trace the history of the pecan in San Saba – including how it has shaped the natural landscape and the individual and collective identities of San Saba and its residents.
Date: May 2023
Creator: Noel, Heather N.
System: The UNT Digital Library
The Arsenal of the Red Warriors: U.S. Perceptions of Stalin's Red Army and the Impact of Lend-Lease Aid on the Eastern Front in the Second World War (open access)

The Arsenal of the Red Warriors: U.S. Perceptions of Stalin's Red Army and the Impact of Lend-Lease Aid on the Eastern Front in the Second World War

Through the U.S. Lend-Lease program, President Franklin D. Roosevelt sought to keep Joseph Stalin's Red Army fighting Adolf Hitler's forces to prevent a separate peace and Nazi Germany's colonization of Soviet territory and strategic resources during the Second World War. Yet after the Red Army's 1943 counterattacks, Roosevelt unnecessarily increased Soviet Lend-Lease aid, oversupplying Stalin's soldiers with more armament than they required for the Soviet Union's defense and enabling their subsequent conquest of East Central Europe and large parts of East Asia. Roosevelt's underestimation of the Red Army's capabilities, his tendency to readily rely on Soviet-influenced advisers, and his unquestioning acceptance of Stalin's implicit threats to forge a separate peace all contributed to his excessive arming of Moscow from 1943 forward. Expanding on the findings of other scholars, this work identifies and explains the impact of the Brest-Litovsk Treaty on Roosevelt's reasoning, the key role of the Arctic convoys in delivering material to the Red Army, and how the unnecessary aid routes through Iran and Alaska resulted in the oversupplying of Stalin's troops. Had Roosevelt not opened these unnecessary routes, the Arctic convoys could have continued to sufficiently supply the Red Army's defensive efforts without empowering it to aggressively spread …
Date: May 2023
Creator: Fancher, James Reagan
System: The UNT Digital Library

Worker Displacement by Artificial Intelligence (AI): The Impact of Boundary-Spanning Employees

Limited literature examines the impact of the displacement of boundary-spanning employees artificial intelligence (AI). Scholars and practitioners appear focused on tangible benefits of AI adoption, and do not seem concerned by any less tangible and possibly untoward implications of worker (particularly boundary-spanning worker) displacement. My dissertation addresses this gap in the literature. In Essay 1, a qualitative study is performed to anchor the research on the appropriate ethnographic setting, the firms where this displacement phenomenon is taking place, by utilizing the Straussian grounded theory approach. The outcome of iterative coding of the first order data collected from the interviews and content analysis is a conceptual framework which amongst other findings shows how the unique competences of boundary-spanning employees and those of AI are best suited for different spectra of interorganizational collaborative activities. In Essays 2 and 3, I investigate major themes that emerged from Essay 1 utilizing quantitative and qualitative research methods in both studies. Initially I test research models using structural equation modelling on practitioner survey data, after which I probe further via focused interviews to better understand the survey results. The two papers allow us to put forth several theoretical and managerial contributions, specifically emphasizing the positive essential …
Date: May 2023
Creator: Ekezie, Uchenna P.
System: The UNT Digital Library

Multiomics Data Integration and Multiplex Graph Neural Network Approaches

With increasing data and technology, multiple types of data from the same set of nodes have been generated. Since each data modality contains a unique aspect of the underlying mechanisms, multiple datatypes are integrated. In addition to multiple datatypes, networks are important to store information representing associations between entities such as genes of a protein-protein interaction network and authors of a citation network. Recently, some advanced approaches to graph-structured data leverage node associations and features simultaneously, called Graph Neural Network (GNN), but they have limitations for integrative approaches. The overall aim of this dissertation is to integrate multiple data modalities on graph-structured data to infer some context-specific gene regulation and predict outcomes of interest. To this end, first, we introduce a computational tool named CRINET to infer genome-wide competing endogenous RNA (ceRNA) networks. By integrating multiple data properly, we had a better understanding of gene regulatory circuitry addressing important drawbacks pertaining to ceRNA regulation. We tested CRINET on breast cancer data and found that ceRNA interactions and groups were significantly enriched in the cancer-related genes and processes. CRINET-inferred ceRNA groups supported the studies claiming the relation between immunotherapy and cancer. Second, we present SUPREME, a node classification framework, by comprehensively …
Date: May 2023
Creator: Kesimoglu, Ziynet Nesibe
System: The UNT Digital Library
Experience Effects on Risk Perception and Protective Action Decision Making when Facing a Rare Tornado Threat (open access)

Experience Effects on Risk Perception and Protective Action Decision Making when Facing a Rare Tornado Threat

Damaging tornadoes are possible in all U.S. regions beyond the traditionally recognized "tornado alleys" in the southern plains and mid-south. Hence, this research examines how study participants respond to rare tornado events. Specifically, how disaster experiences affect risk perceptions and protective actions when facing a rare tornado event. This study used the protective action decision model (PADM) as the theoretical lens to investigate this issue. The PADM shows that personal characteristics, including personal disaster experience, could affect risk perceptions and how protective action decisions are made. This study applies the theory by recruiting 136 human subjects from the state of Washington to participate in a social experiment. The participants take part in a study that includes hypothetical tornado scenarios, ranging from thunderstorm warning to a tornado emergency then answering questions regarding the presented scenarios. Findings suggest that disaster experience and demographics influence how people perceive and respond to tornado disasters. Overall, people with direct and indirect tornado experiences showed significantly lower risk perceptions in the early stages of the threat when compared with those without any tornado experiences. Their tornado risk perceptions later increased when the threats were higher, and they tended to be more complacent regarding protective actions. This …
Date: May 2023
Creator: Stander, Barend
System: The UNT Digital Library

Who are You Going to Believe: Me or Your Lying Eyes? Three Essays on Gaslighting in Organizations

In this dissertation, I theorize on how gaslighting manifests in managerial and organizational settings. I discuss the process of gaslighting and how the use of various manipulation tactics manifests between people in organizations over time. I take three distinctive approaches to study this complex phenomenon. First, using a rich case study, I develop new theory to explain how one notorious child molester was able to sustain a career for decades while assaulting hundreds of children and young women. In doing so, I introduce the concept of gaslighting which previously has only been rigorously applied to intimate interpersonal relationships in domestic (e.g., at home) settings. In essay 2, I expand on the individual level theory developed in essay 1 to develop a more generalized theory of gaslighting in organizations. I situate gaslighting within a nomological net of related constructs and illustrate how gaslighting is a unique construct with different antecedents and consequences that occurs in organizations more often than it should. In my final essay, I build on one of the propositions developed in essay 2 and empirically test what antecedents are likely to influence whether or not a firm is accused of gaslighting on Twitter. Through doing so, I find …
Date: May 2023
Creator: Kincaid, Paula A.
System: The UNT Digital Library
Invariant Differential Derivations for Modular Reflection Groups (open access)

Invariant Differential Derivations for Modular Reflection Groups

The invariant theory of finite reflection groups has rich connections to geometry, topology, representation theory, and combinatorics. We consider finite reflection groups acting on vector spaces over fields of arbitrary characteristic, where many arguments of classical invariant theory break down. When the characteristic of the underlying field is positive, reflections may be nondiagonalizable. A group containing these so-called transvections has order which is divisible by the characteristic of the underlying field, so is in the modular setting. In this thesis, we examine the action on differential derivations, which include products of differential forms and derivations, and identify the structure of the set of invariants under the action of groups fixing a single hyperplane, groups with maximal transvection root spaces acting on vector spaces over prime fields, as well as special linear groups and general linear groups over finite fields.
Date: May 2023
Creator: Hanson, Dillon James
System: The UNT Digital Library
A Schenkerian Analysis and Interpretation of Joseph Jongen's Eclectic "Vingt-quatre petits préludes dans tous les tons pour piano," Op. 116 (1940-1941) (open access)

A Schenkerian Analysis and Interpretation of Joseph Jongen's Eclectic "Vingt-quatre petits préludes dans tous les tons pour piano," Op. 116 (1940-1941)

Belgian composer Joseph Jongen (1873-1953) was an eclectic composer who successfully maintained his own unique musical vocabulary—particularly in his piano compositions. Jongen composed very little between 1940-1941—the period in which he and his family fled to the countryside of Mazères, France, living as refugees for several months before returning to Sart-lez-Spa, Belgium, due to the outbreak of WWII. Reflective of this time in his life, Vingt-quatre petits préludes dans tous les tons pour piano, op. 116 is composed in a particularly intimate and despairing way. Through a complete Schenkerian analysis and outline of the musical framework of op. 116—Jongen's last collection of piano pieces—this dissertation sheds light on the technique, imagination, and uniqueness of Jongen's WWII-period piano compositions. More specifically, this research outlines the deep-level tonal and formal structures, investigates the cryptic semantic meaning and intimate personal expression, and defines the aesthetic achievements of Jongen's Twenty-four Little Preludes in All Keys for Piano, op. 116.
Date: May 2023
Creator: Liu, Yi
System: The UNT Digital Library
The Role of Play Therapists' Characteristics and Self-Efficacy in Predicting Barriers to Engaging Parents (open access)

The Role of Play Therapists' Characteristics and Self-Efficacy in Predicting Barriers to Engaging Parents

The current study sought to explore play therapists' barriers to engaging parents in their clinical work as well as understand the relationship between play therapist characteristics and their attitudes toward parents. Using a demographic questionnaire, Therapist Barriers to Engaging Parents (TBEP), and the Counseling Self- Estimate Inventory (COSE), 136 members of the Association for Play Therapy were surveyed to explore predictors to engaging with parents. Overall, play therapists reported low scores on barriers to engaging parents indicating play therapists are likely to report positive attitudes toward working with parents. Through two multiple regression analyses measuring the predictive value of self-efficacy subscales including Dealing with Difficult Clients and Counseling Process, play therapist identification as a parent, years of experience, and hours of training on parent engagement, both models demonstrated statistically significant findings with large effect sizes. This study found that play therapist self-efficacy was the strongest predictor of play therapists' attitudes toward parents accounting for approximately 80% of the variance in the models. Play therapists' identification as a parent as well as years of practice also predicted their barriers to engaging parents. Hours of training in parent engagement had no relationship to TBEP scores. Implications for practice include a need to …
Date: May 2023
Creator: Line, Ahou Vaziri
System: The UNT Digital Library
William Duckworth's "Southern Harmony": A Comprehensive Exploration into the Synthesis of Two Archetypal American Genres (open access)

William Duckworth's "Southern Harmony": A Comprehensive Exploration into the Synthesis of Two Archetypal American Genres

In his Southern Harmony collection, William Duckworth extracts existing material from shape-note hymns found in William Walker's 1835 publication A Southern Harmony and Musical Companion. He then applies minimalist and postminimalist processes to this material to create innovation choral compositions. This document provides a comprehensive analysis of the methods used to construct all twenty works in Duckworth's collection by tracing the extracted source material through the fabric of the new compositions. This study provides substantial evidence of Duckworth's place as a pioneer of the postminimalist genre. It also provides a discussion on the vocal implications of utilizing shape-note hymns as source material as traditional performances of the genre are typically associated with a unique vocal style.
Date: May 2023
Creator: Boyd, Jordan D.
System: The UNT Digital Library
Intermodal Stimulus Compounding with Ambient Odors Produces Averaging in Rats (open access)

Intermodal Stimulus Compounding with Ambient Odors Produces Averaging in Rats

In an organism's natural environment, there are always an uncountable number of stimuli, and stimulus features, available to gain control over behavior. When these component stimuli are presented simultaneously, this new stimulus compound can occasion a previously unseen effect on behavior. Stimulus compounding is a method used to better understand how variables in stimulus features may impact the final effect on an organism's responding when presented with a stimulus compound. While stimulus compounding experiments are often conducted using intermodal tone and light stimuli, it is conducted far less often using intramodal stimuli, potentially due to the competing stimulus features of same-modality stimuli. Even less conducted research has been done using two odor component stimuli, despite the large impact odor has on many species' behavior. The purpose of this study was to conduct a stimulus compounding experiment using intramodal ambient odor stimuli in rats, to see what kind of effect a mixed odor compound would have on the subject's behavior. This was done using a wind tunnel designed operant chamber, where both subjects were trained to respond to independently presented odor stimuli. Following training a compound mixture of both component odors was presented to the subjects. The results of this study …
Date: May 2023
Creator: Kirkland, Sophia B.
System: The UNT Digital Library
Relevance Criteria when Searching and Evaluating Online Video for Informational Use (open access)

Relevance Criteria when Searching and Evaluating Online Video for Informational Use

Relevance is a core concept in the field of Information Science and a common term in everyday vernacular that generally refers to the usefulness of information. However, relevance has not been sufficiently or consistently defined or explored in the information science literature. Relevance criteria are the factors that information users employ when determining whether information they encounter is relevant. Identifying relevance criteria is a crucial step to understanding relevance. Relevance criteria employed with newer information formats like online video are especially important to study. Online video is now widespread, and people are increasingly likely to rely on video for information. This study identifies relevance criteria employed during relevance assessments of online video through a explanatory sequential mixed-methods study of frequent online video users including students, faculty, librarians, and video professionals. Methods included an online survey and interviews.
Date: May 2023
Creator: Dewitt-Miller, Erin
System: The UNT Digital Library
The Colonial Subject in the Early British Novel: Revisiting Colonial Captivity in "Robinson Crusoe" (open access)

The Colonial Subject in the Early British Novel: Revisiting Colonial Captivity in "Robinson Crusoe"

Scholars today deem Robinson Crusoe the first British novel. Defoe's construction of Crusoe as the atypical British traveler asserts his collective subjectivity within the framework of intimate personal experiences, accentuating his individualism. Yet, as scholars of Orientalism and Transatlantic theory can attest, calling Robinson Crusoe the first novel provides problematic methodologies that arise from affiliating the novel form to a structure associated the British colonialism and fashioning a "superior" British subject. In this essay, I work to emphasize the hybridity present within the novel, utilize historical context to provide a voice to marginalized Indigenous Americans to show how the format relies upon a relationship between collectivism and individualism, assert Indigenous voices matter in the novel, and analyze the relationship of a new collectivism that arises from narratives that cross into American spaces.
Date: May 2023
Creator: Kunasek, Caleb John
System: The UNT Digital Library
Evaluating an Exchange Program for the Treatment of Problem Behavior Maintained by Access to Tangibles (open access)

Evaluating an Exchange Program for the Treatment of Problem Behavior Maintained by Access to Tangibles

Previous studies, typically with children, have used delay-tolerance training to treat problem behavior maintained by access to tangibles. This often involves physical prompting and waiting rather than exchanging, two practices that may not be possible or relevant to adults with intellectual disabilities (ID). For many adults with ID in residential settings, exchanging items, rather than waiting per se, may be evocative for problem behavior. In the current study, I evaluated an exchange program to treat problem behavior maintained by access to tangibles for adults diagnosed with ID at a residential facility. I measured the latency to exchange low- and high-preference items following a request for the item and the individual's problem behaviors. Results demonstrated that the exchange program increased relinquishing of an item while decreasing the rate of problem behavior. This analysis provides another method to treat problem behavior maintained by access to tangibles for adults without using physical prompting.
Date: May 2023
Creator: Bauer, Melanie Sue
System: The UNT Digital Library
Dimensions of statistically self-affine functions and random Cantor sets (open access)

Dimensions of statistically self-affine functions and random Cantor sets

The subject of fractal geometry has exploded over the past 40 years with the availability of computer generated images. It was seen early on that there are many interesting questions at the intersection of probability and fractal geometry. In this dissertation we will introduce two random models for constructing fractals and prove various facts about them.
Date: May 2023
Creator: Jones, Taylor
System: The UNT Digital Library
Faulty Stimulus Control and Reduced Treatment Integrity: An Analysis of Position Biases (open access)

Faulty Stimulus Control and Reduced Treatment Integrity: An Analysis of Position Biases

When learning conditional discriminations, it is possible that faulty sources of control develop and interfere with acquisition. In 2021, Bergmann et al. reported the effects of different integrity levels (i.e., to what degree an intervention is implemented correctly) on undergraduate students' mastery of an arbitrary matching to sample task. They found that participants in the reduced integrity conditions at or below 80% were more likely to show stimulus biases (i.e., selecting a particular incorrect stimulus in the presence of a sample stimulus) than participants in integrity conditions at or above 85%. Bergmann et al. did not investigate whether participants were likely to show responding that was biased by position. A position bias is a type of faulty stimulus control that involves allocating more responses to one or a few positions (e.g., first, second, middle, left). We conducted a secondary analysis of data from Bergmann et al., and we used a chi-square goodness of fit test to identify which participants showed a position bias. We found 25 participants out of 168 with potential position biases. We used a chi-square test of independence to analyze the distribution of participants with biased responding by condition and did not find a statistically significant difference. …
Date: May 2023
Creator: Nielsen, Leif Erik
System: The UNT Digital Library
Modeling of Hypertrophic Cardiomyopathy Using hiPSC-Derived Cardiomyocytes with Static Mechanical Stretching (open access)

Modeling of Hypertrophic Cardiomyopathy Using hiPSC-Derived Cardiomyocytes with Static Mechanical Stretching

The heart is a dynamic environment that is constantly experiencing some degree of remodeling from the point of development, all the way through adulthood. While many genetic components may contribute to the overall presentation of hypertrophic cardiomyopathy (HCM), mutations occurring in sarcomere components such as myosin binding protein C3 (MYBPC3) are of the greatest popularity for study. Aiming to understand the mechanisms underlying heart diseases and to develop effective treatments that circumvent the need for direct patient study, we investigated the use of a platform to mimic the unique physiological conditions of HCM within an in-vitro setting. Following the induction of mechanical stretch on three human induced pluripotent stem cell derived cardiomyocyte (hiPSC-CM) cell lines containing mutations for MYBPC3 (WT, HET, HOM), all displayed HCM like reactions in calcium waveform. In conclusion, this system demonstrated the potential to apply a constant, static strain to healthy and mutated hiPSC-CMs for the MYBPC3 protein to model HCM in-vitro.
Date: May 2023
Creator: Rogozinski, Nicholas
System: The UNT Digital Library

"Mexican Goodbye"

Mexican Goodbye is a collection of poetry that interrogates the dichotomy of a family fractured in conjunction with a speaker's coming of age. The collection reckons with divorce and the subsequent dissolution of the speaker's Mexican American family. Individual poems deal with sisterhood, daughterhood, Chicanismo, grief, the intergenerational impact of the immigrant experience, and inherited trauma. The titular poem illustrates the typical Mexican goodbye, a Latine despedida which can last hours, extended by continued chisme and prolonged conversation. It is this cultural phenomenon that the collection endeavors to encapsulate by lingering in narrative, listing childhood experiences, and allowing the speaker to yearn to return and remain in the past. Ultimately, the speaker desires to linger in the farewell.
Date: May 2023
Creator: Hernandez, Xaviera
System: The UNT Digital Library

Structures of Multicomponent Silicate and Borosilicate Glasses from Molecular Dynamics Simulations: Effects of Iron Redox Ratio and Cation Field Strength

Multicomponent silicate and borosilicate glasses find wide technological applications ranging from optical fibers, biomedicine to nuclear waste disposal. As a common component of earth's mantle and nuclear waste, iron is a frequent encounter in silicate and borosilicate melts and glasses. The redox ratio in glass matrix defined by the ratio of ferrous and ferric ions is dependent on factors such as temperature, pressure, and oxygen fugacity. Understanding their roles on the short- and medium-range structure of these glasses is important in establishing the structure-property relationships which are important for glass composition design but usually difficult to obtain from experimental characterization techniques alone. Classical molecular dynamics simulations were chosen in this dissertation to study iron containing glasses due to challenges in experimental techniques such as NMR spectroscopy originated from the paramagnetic nature of iron. Magnesium is also a common element in the oxide glass compositions and its effect on the structure of boroaluminosilicate glasses were also investigated. Magnesium ion (Mg2+) has relatively higher cation field strength than other modifier cations and its structural role in oxide glasses is still under debate. Therefore, investigating the effects of cation field strength of modifier cations in light of MgO in boroaluminosilicate glasses is also …
Date: May 2023
Creator: Tuheen, Manzila Islam
System: The UNT Digital Library