Digital Commons Network^™

Progress On The Use Of Surface-Immobilized Elastin-Like Polymers As A Stimuli-Responsive Biosensor For Interleukin-6 Detection, Marissa Morales

Doctoral Dissertations

Elastin-Like-Polymers (ELPs) are intrinsically disordered biopolymers with an amino acid structure comprised of the pentapeptide repeat sequence [VPGXG]n (V = valine, P = proline, G = glycine, X = guest residue, and n = total number of repeat sequences). ELPs are stimuli-responsive meaning below their transition temperature, ELPs are structurally disordered, highly solvated, and soluble in aqueous solutions. Above their transition temperature, ELPs experience coalescence and phase separation as intermolecular and intramolecular contacts form within the hydrophobic regions of the ELPs. The transition temperature of ELPs is influenced by the hydrophobic surface area, as well as changing solvent conditions including …

Existence Of Mutual Stabilization In Chaotic Neural Models, John Parker

Doctoral Dissertations

Recent work has demonstrated that interacting chaotic systems can establish persistent, periodic behavior, called mutual stabilization, when certain information is passed through interaction functions. In particular, this was first shown with two interacting cupolets (Chaotic Unstable Periodic Orbit-lets) of the double scroll oscillator. Cupolets are highly accurate approximations of unstable periodic orbits of a chaotic attractor that can be generated through a control scheme that repeatedly applies perturbations along Poincaré sections. The decision to perturb or not to perturb the trajectory is determined by a bit in a binary control sequence. One interaction function used in the original cupolet research …

Mathematical Analysis Of A Model Of Blood Flow Through A Channel With Flexible Walls, Madeline Mayes Edwards

Doctoral Dissertations

The present research is devoted to the problem of stability of the fluid flow moving in a channel with flexible walls and interacting with the walls. The walls of the vessel conveying fluid are subject to traveling waves. Experimental data shows that the energy of the flowing fluid can be transferred and consumed by the structure (the walls), which induces “traveling wave flutter.” The problem of stability of fluid-structure interaction splits into two parts: (i) stability of fluid flow in the channel with harmonically moving walls and (ii) stability of solid structure participating in the energy exchange with the flow. …

Ecological Interactions Of The Trematode Parasite Zoogonus Rubellus And Its First And Second Intermediate Hosts, Sara Edquist

Doctoral Dissertations

Trematode parasites are ubiquitous in marine environments and their importance in ecological function is becoming increasingly recognized, impacting host behaviors, food web dynamics, and community diversity. Trematodes are inextricably tied to their hosts. Therefore, to understand the role of trematodes it is essential to understand their relationships with their hosts. Trematodes typically utilize first intermediate, second intermediate, and definitive hosts to complete their life cycle. Second intermediate hosts are underrepresented in trematode research. Most parasite models and theory are thus incomplete as they rarely include this life stage of the parasite. This research examines the relationship between the trematode Zoogonus …

Speeding-Up A Random Search For The Global Minimum Of A Non-Convex, Non-Smooth Objective Function, Arnold C. Englander

Doctoral Dissertations

The need to find the global minimum of a highly non-convex, non-smooth objective function over a high-dimensional and possibly disconnected, feasible domain, within a practical amount of computing time, arises in many fields. Such objective functions and/or feasible domains are so poorly-behaved that gradient-based optimization methods are useful only locally – if at all. Random search methods offer a viable alternative, but their convergence properties are not well-studied. The present work adapts a proof by Baba et al. (1977) to establish asymptotic convergence for Monotonic Basin Hopping, a random search method used in molecular modeling and interplanetary spacecraft trajectory optimization. …

Molecular Simulation Studies Of Dynamics And Interactions In Nucleic Acids, Lev Levintov

Doctoral Dissertations

In my thesis work, I conducted molecular simulation studies to explore dynamics and interactions in nucleic acids. I began my work by applying conventional molecular dynamics (MD) simulations to study the local and global dynamics of the transactivation response (TAR) element from the type-1 human immunodeficiency virus (HIV-1) and the effect of binding of ligands on the dynamics of TAR RNA. I determined that the TAR RNA structure was stabilized on binding of ligands due to the decreased flexibility in helices that comprise TAR RNA. This rigidity of the TAR RNA structure was coupled with the decreased flipping of bulge …

Nickel – Iron Catalysts For Low Temperature Dry Reforming Of Methane, Gagandeep Dhillon

Doctoral Dissertations

Dry reforming of methane (DRM) offers benefit of consuming two important greenhouse gases(CH4 and CO2) in a single reaction to produce syngas. Ni-based catalysts have been studied for DRM. However, monometallic Ni catalysts deactivate mainly because of coking. We were motivated to include earth-abundant promoter metals to suppress coke formation and studied a series of bimetallic nickel-iron catalysts supported over TiO2 and TiO2-CeO2 at 550˚C and atmospheric pressure. This dissertation mainly focuses on various approaches to synthesize Ni-Fe catalysts and examines the effect of oxide support modification over optimum Ni-Fe/TiO2 catalyst. In this context, Ni-Fe catalysts supported over TiO2 were …

Structural And Binding Studies Of The Polar Organizing Protein Z (Popz) Using Nmr Spectroscopy, Christopher Taylor Nordyke

Doctoral Dissertations

The polar organizing protein Z (PopZ) is an intrinsically disordered protein from Caulobacter crescentus that is necessary for the formation of three-dimensional microdomains at the cell poles, where it functions as a hub protein that recruits multiple regulatory proteins. Although a large portion of the protein is predicted to be disordered, PopZ can self-assemble into polymeric superstructure scaffolds that directly bind to at least ten different proteins. Here, we report the solution NMR structure of PopZΔ134–177, a truncated variant of PopZ that does not self-assemble but retains the ability to interact with heterologous proteins. We show that the unbound form …

Performance Evaluation And Review Framework Of Robotic Missions (Perform): Autonomous Path Planning And Autonomy Performance Evaluation, Allisa Dalpe

Doctoral Dissertations

The scope of this work spans two main areas of autonomy research 1) autonomous path planning and 2) test and evaluation of autonomous systems. Path planning is an integral part of autonomous decision-making, and a deep understanding in this area provides valuable perspective on approaching the problem of how to effectively evaluate vehicle behavior.

Autonomous decision-making capabilities must include reliability, robustness, and trustworthiness in a real-world environment. A major component of robot decision-making lies in intelligent path-planning. Serving as the brains of an autonomous system, an efficient and reliable path planner is crucial to mission success and overall safety. A …

Why Are We Doing This: How Students Find Meaning In Research Writing Across Contexts, Scott Lasley

Doctoral Dissertations

Building on the work of Eodice, Geller, and Lerner and other Composition and Higher Education scholars, my dissertation examines what factors create a meaningful research writing experience. Specifically, this study explores two research questions: 1) How do advanced-level student writers define themselves as writers who use research? 2) How do those identities influence how they understand and utilize research writing concepts? I pursued these questions through a year-long, IRB-approved, qualitative study of junior and senior university students across the disciplines, including English, Neuroscience, and Computer Engineering. Using surveys and interviews, I asked them about meaningful research writing they have done …

"I Know You're Family": An Exploration Of The Enduring Relevance Of A Pre-College Summer Bridge Program For Underrepresented Minoritized Students, Kathryn Slater

Doctoral Dissertations

The proposed dissertation investigates the enduring relevance of a pre-college summer bridge program for underrepresented minoritized (URM) students who participate in the program as an entry point into a predominantly White institution (PWI). Using narrative inquiry and a critical frame, this dissertation uses individual interviewing and focus group data to understand the experiences of 10 URM summer bridge program participants at different points in their undergraduate academic career. For the purposes of this study, relevance of a summer bridge program for URM students refers to the ways in which deliberate and proactive programming helps students to develop academic and socio-emotional …

Nanoelectronic Devices For Sensitive Detection Of Biomarkers In Healthcare Monitoring, Md Niazul Islam Khan

Doctoral Dissertations

In recent years, biosensors have seen an exponential rise of their applications in a number of fields including the field of health care monitoring, particularly in point-of-care diagnostics. With the contemporary rise of nanotechnology, these biosensors have experienced an ever-growing inclusion of nano scale electronic devices or nanoelectronic devices to exploit the plethora of advantages of nanoelectronics. The performances of these nanoelectronic devices, however, largely depend on the nanomaterials used. Especially, carbon-based nanomaterials such as carbon nanotubes (CNTs) and graphene have proven to be superior candidates compared to others because of their multitude of electronic and mechanical properties suitable for …

“We Feminine Foresters”: Women, Conservation, And The Usda Forest Service, 1850-1970, Rachel D. Kline

Doctoral Dissertations

The traditional narrative of the Forest Service places the mythic “two-fisted” male ranger as the focus of its history. The reality is that without women he would not have gotten the job done. Women’s work as advocates, foresters, rangers’ wives, clerks, information and education specialists, scientific researchers, and lookouts reveals that although women were excluded from the male domain of forestry, they created a distinct female tradition within the Forest Service—what one called a “feminine forestry” that proved without women, the Forest Service would not have achieved its accomplishments or growth throughout the twentieth century. Throughout their work, women spread …

Development Of A Sunken Oil Transport Tool Using Mesoscale Experiments, Melissa Denise Gloekler

Doctoral Dissertations

Oil spilled into fresh or saline water can float, become submerged in the water column (i.e., submerged oil), or sink to the bottom (i.e., sunken oil). Once introduced to the environment, oil can negatively impact ecological and public health, and the economy. Non-floating oil spills pose unique challenges to responders including the complexity of trajectory modeling; the inability to detect, track and recover oil due to limited visibility; the lack of readily deployable response technology; and limited understanding of how bottom substrate dynamics influence its fate and behavior. This dissertation research determined that the driving factors used to predict sunken …

Broadly-Based Graduate School Sponsored Communication Skills Programs: A Study In Three Essays Of Programs And Perceptions Of The Diversification Of Career Pathways, Jovana Milosavljevic Ardeljan

Doctoral Dissertations

It has been asserted that communication skills play a critical role in success in a job (What is technical writing?, n.d.). Traditional graduate training prepares students for communication within their field of study; however, it often fails to provide skill development opportunities needed for addressing more general audiences (Coleman, 2018). This research focuses on broadly-based oral and written communication programs which help graduate students to learn to write and orally communicate more effectively to different audiences for different purposes, in and outside of academia, enabling them to explain clearly what they do and why it matters.Using archival analysis and interviews, …

Wind, Wave, And Engineering Effects On Tidal Inlet Morphodynamics, Joshua Lincoln Humberston

Doctoral Dissertations

This body of work examines the hydro- and morpho-dynamics of tidal inlets using a diverse array of research tools. A custom X-band radar system (RIOS) is designed and used to track the evolution of shoal features over the ebb-tidal delta at Oregon Inlet, NC. Analysis of the data reveals that alongshore shoal migration rates are closely correlated to wave driven alongshore sediment transport, and also that the cross-shore bedform migration rates are tightly correlated with a sub-tidal water level gradient though the inlet. A follow up experiment with in-situ sensors suggests that the sub-tidal gradient is set up by regional …

An Empirical Evaluation Of Visual Cues For 3d Flow Field Perception, Andrew Harlan Stevens

Doctoral Dissertations

Three-dimensional vector fields are common datasets throughout the sciences. They often represent physical phenomena that are largely invisible to us in the real world, like wind patterns and ocean currents. Computer-aided visualization is a powerful tool that can represent data in any way we choose through digital graphics. Visualizing 3D vector fields is inherently difficult due to issues such as visual clutter, self-occlusion, and the difficulty of providing depth cues that adequately support the perception of flow direction in 3D space. Cutting planes are often used to overcome these issues by presenting slices of data that are more cognitively manageable. …

Exploring The Lived Experiences Of Middle-Eastern And North African (Mena) Jews Through Narrative Inquiry Using A Digital Storytelling Approach, Brandy B. Shufutinsky

Doctoral Dissertations

Cultural erasure has led to the virtual erasure of many communities from learning spaces. Discrimination, ignorance, and the politicization of knowledge production are all factors that lead to marginalization that sees certain communities being excluded from academia. One such community are the Jewish communities from Middle-Eastern and North African (MENA) lands. This dissertation directly confronts the erasure of MENA Jewish communities and the knowledge they hold by providing a platform for members of these communities to share their experiences. Storytelling is one way to combat cultural and historical erasure (Iseke, 2013). Not only does storytelling provide a way to resist …

Halloysite Modified 3d Printer Filament For Medical And Industrial Uses, Antwine William Mcfarland Jr.

Doctoral Dissertations

Thermoplastics can be used as a replacement or alternative for a variety of medical and commercial products. The addition of halloysite nanotubes further enhance the strength and functionality of the composite. The aim of this project was to evaluate the capability polylactic acid (PLA) to be enhance with halloysite nanotubes and other additives. We created a nanocomposite that offered similar stabilization to titanium surgical plates but with the added benefit of bone generation through recruitment and differentiation of mesenchymal stem cells. Varying amounts of PLA and polycaprolactone were combined with growth factor doped halloysite nanotubes or silicon nitrate then extruded …

Performance And Retention Of Female Engineering Students When Placed In A Gender Parity Course, Allie Corinne Deleo-Allen

Doctoral Dissertations

Though women earn the majority of bachelor’s degrees in the United States of America, they are in the vast minority of those earning degrees in engineering, only 24%. In an effort to ultimately increase the number of women graduating with degrees in engineering, our study focused on improving the retention of first-year female students.

We set out to discover if female engineering students, who traditionally are in the minority of their student body, would have an increase in their performance and retention when placed in a manipulated course environment of gender parity (50% women, 50% men). Our study followed 129 …

Properties And Structures Of Alkali Molybdenum Iron Phosphate Glasses For Nuclear Waste Immobilization, Jincheng Bai

Doctoral Dissertations

"The development of glasses to immobilize nuclear wastes requires a detailed understanding of how composition affects the critical properties required to design wasteforms, including thermal stability and chemical durability. Those properties depend on the molecular-level structures of the glasses. The principal objective of this research was to develop a comprehensive understanding of the composition-structure-property relationships, including the effects of processing conditions, for glasses in the alkali- molybdenum-iron-phosphate systems that could then be used to inform the development of wasteforms of interest to the US Department of Energy.

The molecular-level structures of the alkali molybdenum iron phosphate glasses were analyzed by …

Neogene Dinoflagellate Cysts From The Tropical Americas, Damian Cardenas

Doctoral Dissertations

"Marine palynomorphs, mainly dinoflagellate cysts and acritarchs, constitute excellent proxies for biostratigraphic and paleoceanographic studies in neritic sequences. Neogene marine palynological studies have mostly focused on the Northern Hemisphere, resulting in the scarcity of dinoflagellate cysts and acritarchs from tropical latitudes. Forty samples encompassing the late Chattian-late Burgidalian time interval (~24.1- 17.3 Ma) in the Southern Caribbean were analyzed for their marine palynological contents. A biostratigraphic scheme for the region is proposed and includes the upper Chattian-lower Aquitanian Minisphaeridium latirictum Interval Zone (~23.9-22.0 Ma), the upper Aquitanian Achomosphaera alcicornu Interval Zone (~22.0-20.3 Ma), and the Burdigalian Cribroperidinium tenuitabulatum Interval Zone …

Spatiotemporal Variations Of Upper Crustal Anisotropy Along The San Jacinto Fault Zone In Southern California And The Fairview Region In Central Oklahoma, Enyuan Jiang

Doctoral Dissertations

"To discern spatial and explore the possible existence of temporal variations of upper crustal anisotropy along an ~15 km section of the San Jacinto Fault Zone (SJFZ) in California, and in the Fairview, Oklahoma, region, we conduct systematic shear wave splitting (SWS) investigations using local S-wave data recorded by seismic stations. Strong spatial variations in crustal anisotropy are revealed by 1694 and 405 pairs of splitting parameters (including the fast polarization orientation and the splitting time), respectively. For both areas, for raypaths traveling through the fault zones, the fast orientations are parallel to the faults and may be attributed to …

Extracting Metallurgy Contaminants And Hydrocarbons Removing From Water And Industrial Wastewater Using Enhanced Emulsion Liquid Membrane With Nanoparticles And Ionic Liquid, Qusay Al-Obaidi

Doctoral Dissertations

It is an uphill battle to extract pollutants such as heavy metals, hydrocarbons, and radioactive metals from water and industrial wastewater. Emulsion liquid membrane (ELM) is an emerging technology that combines extraction/recover and stripping in one stage to extract/recover heavy metals and/or hydrocarbons from water and wastewater. ELM devised a way to clean up heavy metals and/or hydrocarbons from the water and wastewater where its primary chemicals can be recycled and reused.

In this work, the Emulsion Liquid Membrane (ELM) has been enhanced by adding nanoparticles and ionic liquid to significantly improve the recovery of the water-based contaminants of heavy …

Catalytic Carbon Dioxide Hydrogenation To Methanol/Dimethyl Ether Over Copper-Based Catalysts, Xiao Fan

Doctoral Dissertations

Direct synthesis of dimethyl ether (DME) via CO₂ hydrogenation has received great attention, owing to the global warming caused by CO₂ emission and increasing energy demand worldwide. In this works, three major aspects of bifunctional catalysts development were studied: (1) investigation of the roles of interaction in the CuO-ZnO-ZrO₂-Al₂O₃/HZSM-5 bifunctional catalysts, (2) deactivation and regeneration of CuO-ZnO-ZrO₂-Al₂O₃ with different zeolitic catalysts for one-step CO₂ hydrogenation to dimethyl ether, and (3) study on the enhancement of activity and stability of CZZA/HZSM-5 bifunctional catalysts via the introduction of …

Establishing Links Between Safety Culture, Climate, Behaviors, And Outcomes Of Long-Haul Truck Drivers, Carlton Washburn

Doctoral Dissertations

“This research examines the safety relationships between safety culture, safety influences, safety climate, and safety outcomes for long-haul truck drivers. The relationships focus on the intersection of the electronic logging device (ELD) technology, regulations, and truck drivers that fall into the lone-worker category. Truck drivers were interviewed to understand their beliefs, attitudes, practices, values, and behavior patterns aligned with the phase in of the ELD system. Large truck crashes during the same time period were analyzed to understand associations. Outcomes included both a safety culture and climate were established for long-haul truck drivers. Both positive and negative safety behaviors were …

Non-Academic Support Math Faculty Members Provide In Developmental Accelerated And Corequisite Support Courses In California Community Colleges, David Vakil '92

Doctoral Dissertations

To guide practitioners of rapidly evolving developmental math reform in community colleges, this study surveyed California community college math faculty who taught accelerated developmental courses or corequisite support courses. The survey was conducted during the early implementation phase of both course types, during spring and fall 2018 terms. This study measured faculty’s self-reported provision of forms of non-academic support, frequency of implementation, and reasons faculty believed the support would help students succeed. The literature review guided grouping non-academic support into five forms: nurturing, helping students’ motivation, providing a growth mindset theory of intelligence, helping provide social integration, and helping to …

Investigating The Self-Efficacy Awareness Of Black Female Technology Leaders, Marie Roberts De La Parra

Doctoral Dissertations

Black female technology leaders lack leadership opportunities, which affects their self-efficacy and is a crucial concern. Self-efficacy is based on the concept that an individual’s belief in what they can achieve influences their actions and how much effort they invest in the selected action. Self-persuasion can provide high or low self-satisfaction as a determinant for creating incentives for success or failure and converting thoughts and emotions to actions. Limited research has investigated the mindset, the thought patterns, and the self-belief undertaken by Black females in the world of technology. Despite limited amounts of research, data suggest that Black female leaders …

Voices Of Chinese International Students: A Critical Understanding Of Their Experiences In The United States, Shudao Zhang

Doctoral Dissertations

This qualitative study investigated the lived experiences of Chinese international students in the United States. It focused on their academic learning, sociocultural relationship, self-reflection and their identity development. This study addressed the active role of international students as participants who can manage cross-cultural difficulties as well as make new interpretations of their life in the host country. This study adopted three theoretical frameworks - transnationalism, transformative learning theory, and social identity theory - to present the intricate educational and social context in study abroad. Through in-depth interviews with eight Chinese students at a private university in California, together with the …

Modeling And Assessing The Sustainability Of Distributed Solar Photovoltaics Adoption, Mingcheng Ren

Doctoral Dissertations

Participation of distributed solar photovoltaic (PV) generation in the organized electricity wholesale market is expected to increase under the Federal Energy Regulatory Commission Order 2222 announced in 2020. Our understanding about the technical, economic, and environmental tradeoffs and co-benefits of solar PV adoption on both building and regional scales remains limited, especially considering the complexity of varied distributed solar PV-battery system designs and operation strategies as well as the dynamic interactions of these distributed generations with the centralized grid. This dissertation therefore aims to investigate the grid load reduction, life cycle cost, and life cycle environmental (e.g., carbon, water, and …