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

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

A Digital Triplet For Utilizing Offline Environments To Train Condition Monitoring Systems For Rolling Element Bearings, Ethan Wescoat

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Manufacturing competitiveness is related to making a quality product while incurring the lowest costs. Unexpected downtime caused by equipment failure negatively impacts manufacturing competitiveness due to the ensuing defects and delays caused by the downtime. Manufacturers have adopted condition monitoring (CM) techniques to reduce unexpected downtime to augment maintenance strategies. The CM adoption has transitioned maintenance from Breakdown Maintenance (BM) to Condition-Based Maintenance (CbM) to anticipate impending failures and provide maintenance actions before equipment failure. CbM is the umbrella term for maintenance strategies that use condition monitoring techniques such as Preventive Maintenance (PM) and Predictive Maintenance (PdM). Preventive Maintenance involves …

An Evaluation Of Clemson University’S Cooperative Extension Services Online Learning Programs And Framework For Program Development And Evaluation, Christina Leard

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The COVID-19 pandemic brought online learning to the forefront with the need to define online learning with best practices. Clemson University Extension conducted a retrospective observational study compiling survey data from virtual extension agents and supervisor’s conducting online programs. A literature review analyzed terminology for online learning to obtain a standardized definition to define online learning for Clemson Extension Services programs; evaluate and identify through literature strengths, weaknesses, opportunities, and challenges (SWOC) of on-line learning; determine and identify online learning competencies for instructors, assessment and evaluation; and analyze and evaluate response data from virtual extension agents delivering online programs in …

Atomistic And Mesoscale Modeling Of Microstructure Development During Solid-State Sintering, Omar Hussein

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Interfaces are ubiquitous in materials systems, and they influence the processing and properties of nearly all engineering and functional materials. Examples include grain boundaries (GBs) in polycrystalline materials, free surfaces in nanoparticles, and phase boundaries in multiphase materials. Therefore, understanding and controlling interfacial processes is a key aspect of materials design and discovery efforts.

Recent developments in advanced manufacturing and synthesis techniques have enabled the fabrication of materials architectures with intricate nanoscale features. Of particular interest is solid-state sintering, known for creating complex and high-precision geometries with controlled microstructures. While sintering science has been the subject of active research, very …

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

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

Towards Enabling Usable Batteryless Wearables, Arwa Alsubhi

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Wearable devices have become ubiquitous in modern technology, providing a convenient way for a large number of users to monitor their health and track their daily activities. However, despite their numerous benefits, wearable devices are not without their challenges. One of the most significant issues is the need to recharge their batteries, which can disrupt users’ daily routines and might result in the discontinuation of device use.

Replacing batteries with capacitors and charging them using the available harvested energy from the surrounding environment (e.g., kinetic, thermal, or solar energy) eliminates the burden of recharging or replacing batteries, resulting in convenient, …

Engineering Next-Generation Cardiovascular Therapies, Ryan Walker Barrs

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

Improving Sizing Resolution Of Particle Impactors In The Nanoparticle Range, Shivuday Kala

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The application of particle size measurement extends across many fields: air quality measurement, pharmaceutical studies, paint and coating production, and nanoparticle formulation to name a few. Therefore, accurate measurement of nanoparticles is critical to aerosol science. While devices currently exist that can size and count nanoparticles such as electrical mobility spectrometers, dynamic light scattering devices, and small angle X-ray scattering devices, their high costs, complex operation, and lack of outdoor usability, restrict their use in practical applications. Among the devices that can size aerosols down to the nanoscale, cascade impactors stand out because of their robustness, relatively simple design, low …

Embracing Identities And Affirming Agency: Exploring Effective Mentorship For Women Doctoral Students In Engineering Disciplines Using An Intersectional Lens, Jennifer Brown

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Positive mentoring experiences are crucial for retaining and advancing those who hold marginalized identities in STEM, as they foster a greater sense of belonging and self-efficacy that encourage these students to persist in their fields. Marginalized identities in STEM include, but are not limited to, women, BIPOC (Black, Indigenous, and People of Color), low-income, first-generation, neurodivergent, and members of the LGBTQ+ community. Oftentimes, these identities intersect, introduce additional nuance in interactions within engineering spaces, and affect the mentoring support that both mentees and their mentors require.

Prior research has shown the reciprocal value that is created when graduate students are …

Experimental And Computational Platforms For Studying Systems Mechanobiology, Brendyn Miller

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

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

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

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

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

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

A Scalable Transmission And Distribution Co-Simulation Platform For Ibr-Heavy Power Systems, Yousu Chen

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The grid is evolving rapidly to meet the requirements of the clean energy transition. This evolution involves an increasing penetration of renewable energy resources and new complexities with a larger number of devices and controls spread across transmission and distribution networks. The boundary between transmission and distribution becomes blur. Consequently, we face significant challenges in managing the fundamental shift in power system physics. The ubiquitous use of Inverter Based Resources (IBRs) throughout the transmission and distribution systems has made it more difficult for the grid to maintain grid stability under dynamic conditions. Therefore, there is a strong need to explore …

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

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

Citrate Hydrogels For Regenerative Medicine Applications, Mark Pitman

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

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

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

Assessing Chondrocyte Viability Of Articular Cartilage Using Label-Free Imaging Methods, Hongming Fan

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ABSTRACT

Articular cartilage covers the ends of bones, providing a protective layer that can endure forces during movement. Chondrocytes, the only cell type found in articular cartilage, produce collagen fibers and proteoglycans that maintain the extracellular matrix (ECM). Cartilage damage impairs chondrocytes and their ability to maintain tissue stability. There are various factors that can cause cell death, which can be broadly classified into two categories: programmed cell death (apoptosis) and non-programmed cell death (necrosis). The consequences of cell death can have significant impacts on the extracellular matrix (ECM). The ECM is a complex network of proteins and carbohydrates that …

An In Vitro Platform To Characterize Myocardial Wound Remodeling, Jonathan Heywood

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Heart Failure, sometimes called Congestive Heart Failure, is a collection of pathological disruptions in which the heart is unable to pump blood properly. It affects over 6 million people in the United States, with the cost-per-patient at approximately $30,000 and the total cost estimated to be $160 billion by 2030. There is no single cause of heart failure, as it can manifest as a varying array of diseases, disorders, and syndromes. However, many of these underlying diseases result specifically from dysregulation of mechanically active cells called cardiac fibroblasts, which play a critical role in the remodeling of the extracellular matrix …

Influence Of Access To Public Parks On Mortality Among Older Adults In The United States, Jiaying Dong

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Research shows the health benefits of green spaces are universal, but there's a noticeable disparity in their distribution in the U.S., especially between urban and rural areas. Marginalized groups, particularly those of lower economic status or racial minorities, often have limited access to these spaces. This inequity could be more impactful on the elderly, who are more vulnerable to health issues. However, specific health benefits of green spaces for seniors are not well defined. This study examines the correlation between park access, mortality in those over 65, and income disparities across all U.S. counties.

The study employed a quantitative approach …

Physics-Based Machine Learning Methods For Control And Sensing In Fish-Like Robots, Colin Rodwell

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Underwater robots are important for the construction and maintenance of underwater infrastructure, underwater resource extraction, and defense. However, they currently fall far behind biological swimmers such as fish in agility, efficiency, and sensing capabilities. As a result, mimicking the capabilities of biological swimmers has become an area of significant research interest. In this work, we focus specifically on improving the control and sensing capabilities of fish-like robots.

Our control work focuses on using the Chaplygin sleigh, a two-dimensional nonholonomic system which has been used to model fish-like swimming, as part of a curriculum to train a reinforcement learning agent to …

Multidimensional Chromatographic Coupling Strategies Implementing Capillary-Channeled Polymer Fiber Stationary Phases, Sarah Wysor

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Liquid chromatography (LC) is a widely employed technique in analytical separations due to the ease of implementing rapid analysis methods to isolate targeted analytes. While LC is commonplace, challenges often arise with complex macromolecules as it often effects isolation via only one attribute of the targeted analyte (i.e., physical, chemical). To cater to increasingly complex samples requiring multiple chromatographic workflows, two-dimensional liquid chromatography (2DLC) has emerged. Various applications, such as drug discovery, pharmaceutical manufacturing, and specialty chemical manufacturing, require highly pure final products for release to the market. Consequently, multiple chromatographic steps are necessary for isolation and purification. Within pharmaceuticals, …

Cfrp Delamination Density Propagation Analysis By Magnetostriction Theory, Brandon Eugene Williams

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While Carbon Fiber Reinforced Polymers (CFRPs) have exceptional mechanical properties concerning their overall weight, their failure profile in demanding high-stress environments raises reliability concerns in structural applications. Two crucial limiting factors in CFRP reliability are low-strain material degradation and low fracture toughness. Due to CFRP’s low strain degradation characteristics, a wide variety of interlaminar damage can be sustained without any appreciable change to the physical structure itself. This damage suffered by the energy transfer from high- stress levels appears in the form of microporosity, crazes, microcracks, and delamination in the matrix material before any severe laminate damage is observed. This …

The Effects Of Math Pathways On Pupils In Poverty, Edward Kameen

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This was a Mixed Methods study that evaluated the implementation of a Math Pathways Program at Crestview High School. The study leveraged Improvement Science and a long-range PDSA cycle with the aim of improving outcomes for Pupils in Poverty in Dual Credit math courses. This study sought to answer three research questions. The first two research questions were answered with quantitative data and the final research question was answered with qualitative data. The research questions that guided this study were (1) What effects did the Math Pathways Program have on the enrollment of Pupils in Poverty in Dual Credit math? …

Atomistic And Mesoscale Modeling Of Microstructure Development During Solid-State Sintering, Omar Marwan Isa Hussein

All Dissertations

Interfaces are ubiquitous in materials systems, and they influence the processing and properties of nearly all engineering and functional materials. Examples include grain boundaries (GBs) in polycrystalline materials, free surfaces in nanoparticles, and phase boundaries in multiphase materials. Therefore, understanding and controlling interfacial processes is a key aspect of materials design and discovery efforts. Recent developments in advanced manufacturing and synthesis techniques have enabled the fabrication of materials architectures with intricate nanoscale features. Of particular interest is solid-state sintering, known for creating complex and high-precision geometries with controlled microstructures. While sintering science has been the subject of active research, very …

Improving Hexapod Platform Pose Accuracy - A Photogrammetry-Based Approach, Sourabh Karmakar

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The aim of this research is to make a newly constructed Stewart-Gough Platform-based test frame Tiger 66.1 operational by developing control software and estimating the error in its pose accuracy. The accuracy of the platform is affected by one source or multiple sources. The typical error sources are kinematic and structural, some of them originate from manufacturing imperfections, assembly deviations, elastic deformations, thermal deformations, and joint clearances which change the expected kinematic behavior of the manipulator. Also, some non-mechanical errors like transmission error, sensor accuracy, algorithm error, and truncation error in calculation contribute significantly in some cases. Using pose deviations …

Did That Help? Harnessing Natural Language Processing To Uncover Characteristics Of Peer Feedback And Their Impacts On Teamwork-Skills Learning., Annamaria V. Wolf

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Peer Evaluation Systems (PESs) allow members of student teams to provide one another with computer-mediated feedback in the form of qualitative, open-ended comments. The current research leverages unsupervised Natural Language Processing (NLP), namely Biterm Topic Modeling (BTM) and sentiment analysis, to uncover latent topics and degree of positivity and negativity expressed in peer feedback, respectively. BTM results revealed a 6-topic model that was reliably replicated over 10 Gibbs initializations 80% of the time. Topics were labeled Timely Communication, Idea Generation, Coordination & Adaptation, Work Quality, Team Support & Focusing, and Work Accountability. Qualitative comparison suggests that these topics demonstrate …

New Preconditioned Conjugate Gradient Methods For Some Structured Problems In Physics, Tianqi Zhang

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This dissertation concerns the development and analysis of new preconditioned conjugate gradient (PCG) algorithms for three important classes of large-scale and complex physical problems characterized by special structures. We propose several new iterative methods for solving the eigenvalue problem or energy minimization problem, which leverage the unique structures inherent in these problems while preserving the underlying physical properties. The new algorithms enable more efficient and robust large-scale modeling and simulations in many areas, including condensed matter physics, optical properties of materials, stabilities of dynamical systems arising from control problems, and many more. Some methods are expected to be applicable to …

Hpc-Enabled Fast And Configurable Dynamic Simulation, Analysis, And Learning For Complex Power System Adaptation And Control, Cong Wang

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This dissertation presents an HPC-enabled fast and configurable dynamic simulation, analysis, and learning framework for complex power system adaptation and control. Dynamic simulation for a large transmission system comprising thousands of buses and branches implies the latency of complicated numerical computations. However, faster-than-real-time execution is often required to provide timely support for power system planning and operation. The traditional approaches for speeding up the simulation demand extensive computing facilities such as CPU-based multi-core supercomputers, resulting in heavily resource-dependent solutions. In this work, by coupling the Message Passing Interface (MPI) protocol with an advanced heterogeneous programming environment, further acceleration can be …

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

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

Trust-Based Variable Impedance Control And Passivity-Based Switched System Analysis For Human-Robot Cooperative Manipulation, Zhanrui Liao

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Human-robot cooperative manipulation (co-manipulation) is one of the most prominent human-robot collaboration (HRC) tasks, where humans and robots manipulate the same object. Trust in HRC is crucial in determining human acceptance of robots and, hence, robot utilization. A probabilistic dynamic Bayesian network (DBN) trust model that integrates a time-series trust model is presented in this thesis. The trust model is learned using a continuous and normalized Baum-Welch (BW) algorithm, devised to account for the continuous nature of trust evolution and the limitations of the classic parameter learning method. To ensure a good HRC in co-manipulation, a variable impedance control framework …