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SYNTHESIS AND CHARACTERIZATION OF BIOBASED BIODEGRADABLE POLYESTERS TO REPLACE LDPE/LLDPE IN FLEXIBLE FILM PACKAGING
No full textThis dissertation investigates the recent advancements in the development of biobased and biodegradable polyesters have shown significant promise for replacing conventional petrochemical-based plastics, particularly in flexible film packaging applications. Poly (pentylene adipate-co-terephthalate) (PPeAT) and poly (dodecamethylene furandicarboxylate) (PDDF) were synthesized using direct esterification and polycondensation methods, incorporating various branching agents and nucleating agents to the former to enhance their thermal, mechanical, and rheological properties. Chapter 1 serves as the introduction to this dissertation, providing an overview of the project's motivation, rationale, and the current possible alternative polymers in the field. This chapter outlines the driving forces behind the research, detailing the pressing need for advancements in the area and the potential impact of the project. Chapter 1 dives into the reasons for undertaking the study, highlighting the gaps in existing knowledge and the anticipated contributions to the field. Chapter 2 reviews the latest technologies and methodologies that form the foundation of the research, setting the stage for the detailed exploration and innovative solutions presented in the subsequent chapters. The preliminary results for the pentanediol – furandicarboxylic acid-based polyesters are reported in Chapter 3. None of these polymers were suitable for flexible-film applications because the glass transition temperature was too high, or the melting temperature was too low. Chapter 4 explores the synthesis and characterization of PPeAT, a polymer synthesized with a 40/60 adipic acid/terephthalic acid mole ratio; a mole ratio chosen to best match the glass and melting temperatures of commercial flexible-film packaging resins. PPeAT exhibits high thermal stability and molecular weight, making it a promising candidate for film-blowing applications, despite its inherently slow crystallization rate. Chapter 5 examines the impact of incorporating nucleating agents, such as Li, Mg and Na-neutralized ethylene-methacrylic acid copolymer-based ionomers and un-neutralized ethylene-methacrylic acid copolymer. These nucleating agents significantly decreased the crystallization half-time, thereby enhancing PPeAT's potential as a biodegradable alternative to linear low-density polyethylene (LLDPE). Chapter 6 investigates the compression molded and film blowing of PPeAT. The blown polyester films were compared with film blown with commercially available polymers such as LLDPE and PBAT. PPeAT showed lower oxygen and carbon dioxide permeability compared with PBAT and LLDPE and lower water vapor transmission rate than PBAT. Film blown PPeAT showed promising results and eventually could be used as a drop-in replacement for LLDE in flexible film packaging Chapter 7 discuss the synthesis and characterization of another possible polymer useful for flexible-film: PDDF, a polymer derived from furandicarboxylic acid and a 12-carbon diol. This polymer demonstrates exceptional gas barrier properties, surpassing those of linear low-density polyethylene (LLDPE) and poly (butylene adipate-co-terephthalate) (PBAT). PDDF's reduced oxygen and carbon dioxide permeability, combined with its robust mechanical properties, makes it an excellent candidate for packaging applications. These developments underline the potential of biobased polyesters to address environmental concerns associated with plastic waste while meeting the demands of global packaging needs
Imagining Native Nationhood: The Art and Activism of Mary Kathryn Nagle's Manahatta and Sovereignty
No full textIndigenous feminist Mishuana Goeman (Seneca) refers to the engagement with the past to determine an indigenous future as (re)mapping, endorsing literary nationalist Robert Warrior’s “assertion that determining our future depends on ‘critically reading our own tradition[, which] allows us to see some of the mistakes of the past as we analyze the problems of the present’” (Goeman 13). Following Goeman’s model, this paper regards the parallel experiences of the past to explain present issues facing Cherokee Nation and the future possibilities for sovereignty. Cherokee playwright Mary Kathryn Nagle’s Manahatta (2013) and Sovereignty (2018) (re)invoke elements of traditional Cherokee women’s roles, Indigenous feminisms, and literary nationalism to (re)claim Cherokee sovereignty. Mary Kathryn Nagle’s plays are rooted in Indigenous feminist stories like those of Selu and Núñ'Yunu'Wĭ, which avow the power of women and their commitment to keeping their communities alive. Drawing on the history of Native theater’s role in Indigenous feminist activism, Manahatta and Sovereignty advocate for Indigenous feminist concerns that transcend time by melding past and present temporalities, (re)writing and (re)righting dominant binary narratives of assimilation or death, by presenting modern Native people as agents of their cultural sovereignty. Nagle positions her protagonists as sites of political protest who (re)stake political authority over their own cultures and bodies, and by extension their nations. Though both Manahatta and Sovereignty were produced before the U.S. Supreme Court heard or decided McGirt, the plays anticipate and engage with tensions surrounding state, tribal, and federal jurisdictions, and thus, sovereignty. Ultimately Nagle imagines an Indigenous feminist future for Cherokee sovereignty that simultaneously tells and (re)creates itself internally and communally, having been and continuing to be without the need for external recognition
Designing the Organ Case: Interviews with Selected Organ Designers and Builders
No full textThis study investigates the artistic process of designing organ cases through a series of semi-structured interviews with three currently active, well-established designers working since 1970 – Lynn Dobson, Didier Grassin, and Gesa Graumann. These interviews probe the aesthetic, architectural, visual, and engineering considerations and rationale informing the organ case design process required for a successful musical instrument and art object. Chapter One introduces the basic concepts of the organ case, the purpose and need for this study, biographical sketches for the three interviewees, and research procedures. Chapter Two offers a two-part literature review, tracing the history of the organ case and a survey of scholarship written by designers. Chapter Three details interviews individually, highlighting distinctive thoughts and themes expressed by each respectively. Chapter Four places Dobson, Grassin, and Graumann in ‘conversation’ by identifying various points of commonality and disagreement. A brief conclusion and suggestions for further research concludes the chapter. Complete transcriptions of all three interviews are provided in the appendix
NEWS MANAGERS’ PERCEPTION OF AI ADOPTION IN US NEWSROOMS: A STUDY ON PROFESSIONALISM, JURISDICTION, CONTROL & AUTHORITY
No full textMore and more professional journalists are now learning to adapt to changes AI adoption is bringing into their workplace and how they practice journalism. This study used the concepts of professionalism, jurisdiction, control and authority to conduct in-depth interviews with ten news managers to explore their perceptions on the adoption of AI in local newsrooms in the U.S. The study found that local newsroom managers perceived that without proper training, AI had the potential to erode professionalism standards in journalism and control over journalistic processes to wane. The findings also suggest that participants rejected the idea that AI could replace humans in journalism despite possibilities the jurisdiction to perform journalistic activities could be compromised as the technology continues to evolve. The study also found that although these news managers recognized AI as a tool in the newsroom, they were unwilling to share the authority with AI in framing the narrative
Metabolic Dependencies Drive Species Interactions in the Microbial Communities
Get PDFMicrobial interactions are fundamental to ecosystem dynamics, influencing processes such as nutrient cycling, energy flow, and ecosystem stability. This dissertation explores the complexity of microbial communities across diverse contexts, from environmental ecosystems to human health, using advanced multi-omics technologies and computational modeling. By examining both natural and synthetic microbial consortia, the research presented here highlights how metabolic dependencies, such as cross-feeding and syntrophy, shape community structure, stability, and functionality.A key focus of the research is on microbial metabolic dependencies and their role in ecological processes such as nutrient cycling and organic matter decomposition. Recent advances in multi-omics approaches have revealed how these dependencies influence the assembly, stability, and adaptation of microbial communities, with implications for agriculture, environmental management, and biotechnology. Further investigations into synthetic microbial consortia reveal how higher-order interactions lead to emergent properties that are not present in simpler systems. A synthetic quad-culture, composed of microorganisms responsible for cellulose degradation and methane production, exhibited both positive and negative synergies, demonstrating enhanced methane production and reduced cellulose degradation compared to simpler consortia. These findings highlight the potential for engineering microbial communities for industrial applications such as bioenergy production and waste management. The dissertation also examines the effects of environmental stressors, such as oxygen and sulfate exposure, on microbial communities in wetland soils, key players in global carbon cycling. The research reveals that elevated sulfate and oxygen levels suppress methane emissions while increasing carbon dioxide production, providing insights into how microbial communities respond to climate change and influence greenhouse gas dynamics. In the clinical context, this work explores the effects of dietary interventions on the gut microbiomes of women with gestational diabetes mellitus (GDM) and their infants. The results demonstrate that targeted dietary modifications can significantly alter microbial diversity and function, with potential implications for managing metabolic disorders through personalized nutrition and microbiome-based therapies. Overall, this dissertation contributes to a deeper understanding of microbial interactions, emphasizing their role in ecosystem stability, industrial processes, and human health. By leveraging the power of multi-omics technologies and computational models, this work provides a framework for predicting microbial community behavior and designing targeted interventions for both environmental and clinical applications
ENHANCING HYDROGEN ENERGY STORAGE AND TRANSPORTATION SYSTEMS: PREDICTIVE MODELING OF SEALING MATERIALS THROUGH EX-SITU EXPERIMENTAL ANALYSIS
Get PDFAs the global energy trend shifts towards cleaner alternatives, hydrogen arises as a prospective candidate due to its high energy density and zero carbon emissions. However, significant challenges persist, particularly in the durability and reliability of materials used for hydrogen storage and sealing. This study explores the challenges and opportunities associated with hydrogen production, incorporating CO2 capture technology and the interaction of materials to understand the correlation between materials and hydrogen exposure. This dissertation presents a literature review and experimental analysis focused on hydrogen-induced aging in polymeric sealing materials, specifically nitrile butadiene rubber (NBR), ethylene propylene diene monomer (EPDM), and silicon. The research reviewed hydrogen-induced aging mechanisms, including thermal, chemical, mechanical, and thermo-mechanical aging, which leads to the loss of integrity of sealing materials. A series of controlled experiments were conducted to simulate real-world conditions, with the aim of assessing the effects of high-pressure hydrogen exposure on the physical, mechanical and electrical properties of NBR, EPDM and silicon. Findings from the experimental results indicate a complex interaction among swelling, hardness reduction, and tensile strength degradation in sealing materials under hydrogen exposure. Tensile strength degradation was strongly associated with crack formation. At the same time, Silicon exhibited the lowest swelling due to its Si-O-Si backbone but showed significant reductions in tensile strength and hardness and high crack and cavity counts. EPDM displayed moderate swelling and hardness loss, coupled with strong leak resistance and minimal morphological degradation, due to its saturated backbone and low hydrogen solubility. Despite the higher hydrogen solubility and free volume, NBR retained hardness better than Silicon but exhibited moderate morphological degradation that weakened the leak resistance over time. NBR’s absolute resistivity was found to remain much lower than that of Silicon and EPDM with hydrogen exposure. Both EPDM and NBR maintained comparable sealing performance up to 1500 psi, however, EPDM’s resilience against further degradation under prolonged pressures suggests it as the optimal elastomeric material for consistent sealing under high-pressure hydrogen system. Several machine learning approaches were applied to predict key sealing properties of materials exposed to hydrogen. This study employed multiple models like Multivariate Linear Regression (MLR), Generalized Additive Model (GAM), and Random Forest to capture linear and non-linear dependencies between pressure and sealing properties. It was observed that MLR performed better handling linear relationships, especially for tensile strength and hardness, while GAM performed better in capturing non-linear resistivity behavior. A CNN model is trained on SEM images to capture morphological changes, showing the lowest MAE for Silicon. The final recommendation is a combined MLR-CNN model, which balances numerical and morphological predictions for optimal material property assessment under hydrogen exposure, suggesting EPDM for high-pressure applications. This research is expected to contribute to the life cycle estimation and customization of elastomeric materials for hydrogen infrastructure. That will assist in accurately improving the scheduling of e the predictive maintenance of the seals used in the hydrogen industry. Thus, this research will help the industry to meet ISO 15869 and the ASME B31.12 through the developed predictive models for seal failure and performance in hydrogen pipelines. It provides a foundation for future research in sealing technology, aimed at enhancing the long-term safety and performance of hydrogen storage and transportation systems
The Triangle of Res: A Trinary Model of Best Practices for the Performance of African Choral Music in the United States
No full textThe religious and educational components of the European colonial enterprise in Africa resulted in the initial manifestations of Western-influenced African music, which is now part of what is considered world music. The United States occupies a distinctive position within world music because of the continuous infusion of global traditions and genres that have influenced its musical environment. Among the many categories of world music, African music's pop genre (Afrobeats) is known globally due to the rise of streaming services, social media, technological advancements, and creative partnerships with worldwide celebrities. Following the model of Afrobeat's popularity, African music's choral genre may attain mainstream recognition through collaborative access to the works of indigenous African composers for performances by American choral directors. Therefore, within this discourse, African music refers to choral music from sub-Saharan Africa rooted in folk tradition and culturally indigenous: created by composers who understand their native African cultures and traditions. A framework of best practices for promoting and ensuring authentic cultural portrayals of African music on the American stage is the Triangle of Res (ToRes). It addresses several performance considerations, such as publishing notated sheet music of indigenous works, production of audio-visual aids, text-pitch negotiations/IPA pronunciation guide, and collaborative interest from American choral conductors. The preparation and performance of two Igbo choral pieces at the University of Oklahoma between 2022 and 2023 will be discussed to evaluate the effectiveness of the ToRes model
APPLICATION OF 4D SEISMIC ATTRIBUTES TO MONITOR RESERVOIR FLUID MOVEMENT AND PRODUCTION DISCREPANCIES: MAUI FIELD, TARANAKI BASIN, NEW ZEALAND
No full text4D timelapse seismic data is commonly implemented to monitor reservoir evolution associated with fluid changes over time. This research utilizes seismic attributes and machine learning to improve upon traditional 4D seismic workflows to better understand fluid movement in 4D time lapse seismic data within the C Upper Sand reservoir of the Maui Field off the western coast of New Zealand. This technique is unique as it implements attributes calculated on two separate 3D seismic volumes acquired in different years in the attempt to image changes in fluid types associated with concurrent hydrocarbon production. Additionally, a computed difference volume, looking at the variation between these two original seismic volumes, is analyzed with each attribute for further insights.In particular, instantaneous, spectral, and geometric attributes are utilized to provide a better understanding of reservoir fluid movement in this 4D analysis. Instantaneous attributes, sensitive to frequency and amplitude variations are implemented to track movement of both reservoir gas and water associated with production. Spectral attributes are used to indicate facies heterogeneity throughout the reservoir that may affect fluid flow behavior. Geometric attributes are used to elucidate any previously overlooked reservoir baffles that could prohibit fluid movement through the reservoir as it is produced. Following these attribute calculations, attribute volumes were cross referenced with fluid saturation models and production maps to validate the accuracy of what each attribute is portraying in regards of fluid movement. Additionally, attributes that contribute to the overall understanding of reservoir fluid movement are combined in a principal component analysis (PCA) to accentuate reservoir heterogeneity and changes, spanning from lithologic facies to fluid alterations. After PCA computation, well logs were used to validate the interpretation of geologic reservoir heterogeneity for differential reservoir depletion among zones, finding that baffles and facies that are prone to diagenetic cementation hinder fluid movement. The research concludes that employing a 4D attribute-based workflow aids in a more thorough comprehension of the geologic control of reservoir fluid movement during production in the Maui C Upper Sand over time
VOICES OF A NATION: EXPLORING NATIONALISM IN JAMAICAN CHORAL MUSIC FROM THE 20TH CENTURY ONWARD
No full textThis document will explore late-twentieth century and post-twentieth century nationalist choral music in Jamaica. By delving into the historical context of nationalism in the region, I will examine how colonial legacies and resistance movements paved the way for the emergence of nationalist sentiment in the twentieth century, significantly impacting expression through choral music. Through an analysis of nationalist choral music in Jamaica, characterized by folk elements which involve the fusion of African and European musical cultures, this document will examine representative choral works and will analyze three such works. Additionally, this document will highlight potential performance problems and offer solutions. Finally, I will underscore the continued influence of nationalist choral music on contemporary Jamaican musical expressions, inviting further research and exploration into this vibrant cultural heritage
A NOVEL FRAMEWORK FOR EVALUATING ENGINEERING SELF-CONCEPT: EXPLORING ITS EFFECTS ON SELF-EFFICACY AND IDENTITY STATUS TRANSITIONS AMONG FIRST-YEAR STUDENTS
No full textEngineering education research can benefit from comprehensive tools for assessing studentself-concept and its relationship to identity development. This research addresses this gap by introducing a novel framework for evaluating engineering self-concept and exploring its influence on identity status transitions among first-year students. Key sub-constructs of engineering selfconcept were identified through an extensive literature review, distinguishing it from self-efficacy. A new survey instrument for assessing engineering self-concept was developed, pre-tested with subject matter experts and was statistically validated. Confirmatory factor analysis was used to validate the theoretical framework and to examine the relationship between engineering selfconcept and self-efficacy. After establishing the framework for engineering self-concept, measures of identity status were integrated into the analysis to investigate identity status transitions in first-year engineering undergraduates. Significant transitions were observed amongst cohorts of students. A qualitative interview methodology provided insights into specific transition patterns that were observed. Interpretations further explored connections between engineering self-concept and various identity statuses. Findings contribute to the field of engineering education by providing a validated tool for assessing engineering self-concept and insights into the relationship between self-concept and identity development. Implications extend to structural adaptations to enhance undergraduate student identity development, improve student performance and commitment to engineering, and inform educational strategies for increasing retention and persistence in engineering programs. This work lays the foundation for future research aimed at supporting the holistic development of engineering students during their critical first year