Engineering Commons^™

Advancing Electrochemical Microsensors For Multiplexed Neurotransmitters And Environmental Toxins Detection, Sanjeev Billa

Doctoral Dissertations

Electrochemical sensors have emerged as a promising solution for monitoring neurotransmitters and heavy metals, which could ensure good health and safety in the environment. This dissertation focuses on advancement in the field of electrochemical microsensors by improving the electrode properties and sensor metrics such as rapid response time, multiplexing, high sensitivity, high selectivity, and accuracy for the real-time monitoring of neurotransmitters (glutamate and GABA) and heavy metals (cadmium and lead). In this dissertation, a novel silicon (Si) multifunctional biosensor probe with four platinum ultramicroelectrodes (UMEs) and an on-demand in situ calibration (ODIC) microfluidic channel was optimized for sub-second simultaneous real-time …

Micropatterning Of Biologically Derived Surfaces With Functional Clay Nanotubes, Nisha Lama

Doctoral Dissertations

In this study, we have generalized an assembly of 50 nm diameter clay nanotubes on larger 20-50 μm diameter biological microfibers such as human hair (protein), cotton (cellulose) and synthetic polyethylene terephthalate- PET. We developed a common set of parameters and nanoclay coating techniques on these naturally different microfibers. We exploited and optimized the electrostatic interaction of the components through strategic adjustments in the solvent pH, employing polycation treatment, as well as selectively modifying the halloysite nanotubes with silanes. For 5 mins, a 5 wt% aqueous dispersion of halloysite nanotubes were applied to get approximately 1-2 μm thick fiber coating …

Impact Of Student Beliefs And Self-Efficacy On Performance In Higher Education Stem Courses, Lauren Nicole Fogg

Doctoral Dissertations

In engineering education, students often face feelings of inadequacy, leading to academic struggles and potential dropout. This dissertation investigates the impact of interactive course materials on students' confidence and self-efficacy in problem-solving, focusing on an Engineering Materials class at Louisiana Tech University. Over four quarters, involving seven sections and 218 students, a 13-question Likert scale survey was administered repeatedly, alongside demographic data and textbook usage surveys. The study aims to compare students’ attitudes and beliefs when not using a textbook versus when using an interactive web-native book. Hypotheses suggest that the interactive book will enhance problem-solving beliefs, confidence, and grades. …

Phase Interface Dynamics And Heat Transfer Mechanisms In Evaporating Droplet And Pool Boiling Processes, Md Tanbin Hasan Mondal

Doctoral Dissertations

Despite the significant importance and widespread use of phase-change cooling techniques, there are still fundamental questions about the microscopic processes that govern the heat transfer mechanisms. In order to gain a better understanding of the underlying physics involved, it is essential to have information at the microscale regarding the surface temperature distribution with time as well as the location and speed of the moving contact line (MCL). A comprehensive understanding of heat transfer mechanisms and phase-interface behavior during phase-change cooling is crucial for improving heat transfer models, optimizing surface engineering, and maximizing overall effectiveness. Firstly, this dissertation presents a capacitance-based …

Blow-Spun Hybrid Pcl-Peo/Hnts Scaffolds With Enhanced Biological And Mechanical Properties, Meichen Liu

Doctoral Dissertations

With the development of technology and engineering, nanotechnology has been a multidisciplinary scientific field applied in nearly all science areas, including medicine, genetics, food industry, robotics. In this respect, nanomedicine has gained increasing attention and been a useful, effective therapy for cancer diagnosis, gene transfer, and drug delivery. To design an ideal nano drug delivery system with controlled drug releasing and improved encapsulated drug’s pharmacokinetic and pharmacodynamic profiles, hydrogels and polymer composites have witnessed increased research interest during the last decades. Recently, numerous polymers have been studied to fabricate the ideal wound dressing with biocompatibility, biodegradability, porous structural, and suitable …

Development Of An Integrated Workflow For Nucleosome Modeling And Simulations, Ran Sun

Doctoral Dissertations

Nucleosomes are the building blocks of eukaryotic genomes and thus fundamental to to all genetic processes. Any protein or drug that binds DNA must either cooperate or compete with nucleosomes. Given that a nucleosome contains 147 base pairs of DNA, there are approximately 4^147 or 10^88 possible sequences for a single nucleosome. Exhaustive studies are not possible. However, genome wide association studies can identify individual nucleosomes of interest to a specific mechanism, and today's supercomputers enable comparative simulation studies of 10s to 100s of nucleosomes. The goal of this thesis is to develop and present and end-to-end workflow that serves …

Selective Targeting Of Microglia By Quantum Dots And Green Synthesis Of Metal Organic Biohybrids; Applications In Dynamic Cell And Assay Systems, Navya Uppu

Doctoral Dissertations

Neurological disorders are the leading cause of physical and cognitive disability across the globe, currently affecting approximately 15% of the worldwide population. Part of the glioma microenvironment are microglia, resident immune cells of the CNS that were thought to be involved in the pathogenesis of diverse neurodegenerative diseases. Though it remains uncertain what triggers microglial activation in these disorders, targeting and tracking microglial functions using nanotools like Quantum Dots (QDs) could help us elucidate them in such neurological diseases. This research focuses on the comparative study of different QDs formulations and their selective uptake by brain microglia in primary cultures …

Development And Characterization Of Injectable, Cell-Encapsulated Chitosan-Genipin Hydrogels, Tyler R. Priddy-Arrington

Doctoral Dissertations

Over 150,000 patients undergo lower extremity amputation every year in the United States, most commonly caused by complications due to diabetes mellitus, peripheral vascular disease, and trauma. Diseased or damaged tissues that are unable to naturally repair themselves must either be fully removed or replaced, otherwise the injuries can lead to further complications such as infection or death. Tissue resection and amputation, as forms of removing damaged tissue, are not favorable to patients as they can cause pain, reduce mobility, and negatively impact quality of life. However, replacing lost or damaged tissues with donor tissues carries the risks of tissue …

In Situ High Temperature Fiber-Optic Raman Sensor For Industrial Applications, Bohong Zhang

Doctoral Dissertations

"Continuous casting in steel production uses specially developed oxyfluoride glasses (mold fluxes) to lubricate a mold and control the solidification of the steel in the mold. The composition of the flux impacts properties, including basicity, viscosity, and crystallization rate, all of which affect the stability of the casting process and the quality of the solidified steel. However, mold fluxes interact with steel during the casting process, resulting in flux chemistry changes that must be considered in the flux design. Currently, the chemical composition of mold flux must be determined by extracting flux samples from the mold during casting and then …

Design And Development Of Biocompatible Mofs And Silica-Based Nanocarriers With Controlled Pharmacokinetics For Drug Delivery Applications, Neila Pederneira

Doctoral Dissertations

"In the past decade, a big interest has drawn into nanoporous metal-organic frameworks (MOFs) and silica-based materials as nanocarriers for drug delivery applications, owing to their exceptionally high surface area and highly structured porous network. The overall goal of this research was to optimize the pharmacokinetic behavior of several highly porous biocompatible drug carriers that have the potential to carry Ibuprofen, 5-Fluorouracil, and Curcumin to the desired tissue without creating a burst effect and minimizing the amount of dosage and size that conventional capsules require. The specific objectives of this study are to (i) assess the effect of drug solubility …

Improving Decision-Making Processes In Construction And Infrastructure Bidding: Qualitative And Quantitative Approaches Including Graph Theory, Game Theory, And Machine Learning, Muaz Osman Elzubeir Ahmed

Doctoral Dissertations

"Construction and infrastructure bidding is a highly competitive process that entails various uncertainties faced by contractors. Contractors weigh various factors to determine the expected benefits of a construction project and decide their bid value. However, the situation is more complex in multi-stage bidding (MSG), where general contractors must account for the bids of their subcontractors and face a greater threat of the winner’s curse (i.e., situation where the winning contractor underestimates the actual cost of the project). As such, bidding-related complexities, risks, and uncertainties, if uncontrolled, can lead to the rise of claims and disputes between stakeholders. Existing research falls …

In-Depth Characterization Of The Selective Oxidation Products Of Hafnium Carbide, Jonathan Allen Scott

Doctoral Dissertations

"Materials capable of withstanding oxidative environments at temperatures >2000°C are necessary for hypersonic applications. Hafnium carbide (HfC) shows a combination of properties that lends itself toward these applications; however, its oxidation behavior is poorly understood. At 1300°C, HfC was found to oxidize via the following mechanism: 1) Initial oxidation of both C and Hf present in the system, 2) Formation of an interconnected pore network, whose size is related to the volume of gases being generated during the oxidation process, 3) Growth of the oxide scale to become sufficiently protective, 4) Formation of an initially amorphous “HfO₂C” at …

Control And Optimization Of Energy Storage System In Power Distribution System, Waqas Ur Rehman

Doctoral Dissertations

"The widespread adoption of electric vehicles (EVs) and transportation electrification is encumbered by two chief barriers: i) the limited driving range of EVs in the market today and ii) inadequate fast-charging infrastructure for long-distance trips. Extreme fast charging (XFC) technology can recharge EVs in less than 10 minutes for 200 miles range. Firstly, a novel robust optimization-based mixed integer linear programming model is proposed to size a battery energy storage system (BESS) and PV system in an XFCS. In this part, it is assumed that the sizing and location of the XFCS are known. Secondly, the aforesaid assumption is relaxed, …

Contextualizing Renewable Energy Adoption: An Examination Of The Role Of Community Choice Aggregation, Ankit Agarwal

Doctoral Dissertations

"The rapid expansion of renewable energy generation in the U.S., both through distributed and utility-scale facilities, is largely driven by top-down policy measures and the growing engagement of residential consumers on both individual and community levels. Previous studies on motives behind residential renewable energy adoption have examined procurement options in isolation and within a static context, primarily focused on intrinsic attributes like economic incentives, emission reductions, and peer popularity. This research introduces a novel context, assessing renewable procurement options in the presence of Community Choice Aggregation (CCA), a more prevalent and accessible alternative. This dissertation makes four pivotal contributions, offering …

Non-Linearity Modeling And Quantifications For Practical Rf Interference Control, Shengxuan Xia

Doctoral Dissertations

"Radio frequency (RF) interference can degrade the receiving sensitivity of antennas (desense problem). It is essential to model the nonlinearity as it is the root-cause of the unwanted frequency components. Understanding the electromagnetic (EM) coupling or radiated emissions is also important.

Nonlinearity causes modulation-involved desense problems, and it consists of two categories: upconvertion of the baseband noise by the transmitting (TX) signal, and the passive intermodulation (PIM) of the transmitting signal itself. The upconvertion caused desense can be modeled and analyzed with the dipole-moment based coupling framework. PIM has been identified as another nonlinear distortion mechanism, specifically in the metallic …

Applications Of Computational Intelligence And Data Fusion Techniques For Biomedical Images, Anand Krishnadas Nambisan

Doctoral Dissertations

"The realm of melanoma diagnosis has been significantly advanced by deep learning (DL) techniques, yet the current approaches are not without limitations, including missed diagnoses and the challenge of interpreting these "black box" models. The research is comprised of three studies, each contributing uniquely towards advancing melanoma detection accuracy and interpretability. The first study focuses on improving the detection of specific dermoscopic structures through a deep learning-based segmentation approach, while the second study builds upon this by employing a fusion technique that combines traditional image features with advanced deep learning models. This method significantly improves melanoma detection, particularly in recall …

Lithospheric Drip And Mantle Thermal Upwelling Beneath Central Asia And The Southern Great Plains Of North America: Evidence From Receiver Function Imaging, Yangyang Liao

Doctoral Dissertations

"Investigating the depth of mantle transition zone (MTZ) discontinuities provides insights into mantle dynamics, including regional-scale downwelling of mantle lithosphere (i.e., lithospheric drip) and upwelling of thermal materials (i.e., mantle plume). In our study, we employ receiver functions to image the 410 km (d410) and 660 km (d660) mantle discontinuities and to ascertain thickness of the MTZ beneath Central Asia and the Great Plains in United States. The findings unveil a significantly thickened transition zone, exhibiting an average thickness of 284 km beneath East Sayan. When considered alongside geochemical observations, our results indicate that the descent of the lithosphere is …

Processing-Microstructure-Properties Relationships In Additively Manufactured Zrb2-Sic Ceramics, Marharyta Lakusta

Doctoral Dissertations

"The study explores the pressure less sintering (PS) and chemical compatibility of ZrB₂-30 vol.%SiC produced by additive manufacturing (AM) with CO₂. The oxidation kinetics and scale microstructures were compared for ZrB₂-SiC made by hot pressing (HP) and by AM coupled with PS. All specimens exhibited parabolic oxidation kinetics. The difference in oxidation behavior becomes evident at temperatures of 1100-1400°C (200-900h). Oxidation rates increased as grain size increased. Similar oxide scale morphologies were observed in both CO₂ and air, with an outer borosilicate layer and an inner porous ZrO₂ layer containing partially oxidized …

High Viscosity Friction Reducer Evaluation At High Temperature And High Tds Environments, Ghith Ali Ahmed Biheri

Doctoral Dissertations

"In unconventional reservoirs, proppant transport during hydraulic fracturing treatments could be successful when the proppant is placed further within the reservoir's fracture networks. This could increase the reservoir formation conductivities and improve the productivity of the wells. This job of improving the reservoir conductivity by distributing and transporting proppant can be conducted by reliable fracture fluids with excellent fluid rheology (e.g., viscosity and elasticity). However, several challenges, including the high temperatures and the presence of high TDS in produced water, may limit the capability of fracture fluids to transport proppant. Additionally, the use of fracture fluid has raised fears regarding …

A Structure From Motion Photogrammetric Method For Continuously Measuring And Tracking The Deformations Of Soils During Triaxial Testing, Xiaolong Xia

Doctoral Dissertations

"Measuring soil deformation characteristics during triaxial testing is an important part of characterizing the stress-strain behavior of both saturated and unsaturated soils. The total and local deformations and volume changes of a soil specimen are indispensable parameters that need to be measured and are of great significance for understanding volume change and shear strength characteristics of the soil. Over the past several decades, numerous efforts have been made to measure the soil deformations during triaxial testing. However, it remains a great challenge for researchers to measure the volume-changes of unsaturated soils due to the existence of the air phase.

This …

Comprehensive Investigation Of Using Tire-Derived Aggregate In Chip Seal Subjected To Various Traffic And Environmental Conditions, Alireza Pourhassan

Doctoral Dissertations

"Chip seal is one of the most cost- and performance-effective pavement preservation treatments commonly used in the United States. Using crumb rubber obtained from scrap tires as a partial or full replacement for mineral aggregate has been proposed as a sustainable solution to reduce the negative environmental impacts of scrap tire accumulation and excessive consumption of natural resources. However, there was no data available regarding the performance of rubberized chip seal under traffic loads and environmental conditions. An extensive study using laboratory specimens and conditioning as well as field implementation and assessments were conducted to bridge this gap. Different traffic …

Sustainable Cementitious Materials For Building And Sorption Applications, Sukanta Kumar Mondal

Doctoral Dissertations

"Ordinary Portland Cement (OPC) is the most widely used cement material, but it contributes over 8% of the global CO₂ emission and the process is energy intensive. Moreover, OPC faces durability challenges, particularly in aggressive environments. Hence, there is rapidly increasing interest in sustainable alternative cements with lower carbon footprint, lower energy consumption, and those that offer superior properties that are beneficial for specific applications. Two sustainable cementitious materials that are frequently researched as an alternative to OPC are calcium sulfoaluminate (CSA) cement and alkali-activated materials (AAMs). CSA cement lowers CO₂ emission by over 40% compared to OPC, …

Novel Supercritical Biodiesel Plant Design & Process Scale-Up, Ghana Shyam Paudel

Doctoral Dissertations

"Current energy prices, national energy security, and global climate change fuel our momentum to find efficient advanced fuels choices. In this study, biodiesel processing, and a novel design for next generation biodiesel plants are explored. During a National Science Foundation (NSF) I-Corps project we identified three creative and profitable improvements to the process: 1. Incorporating Energy intensive separations and reactions 2. Utilizing Low commodity glycerol and 3. Applying process intensification principles.

Current biodiesel processes are catalyzed processes using continuous stir reactors with distillation systems to separate material constituents. We tested a lab-scale nocatalyst supercritical biodiesel process using waste cooking oil …

Advanced Manufacturing Of Nanomaterials For Energy Storage And Biomedical Applications, Hiep Pham

Doctoral Dissertations

"Nanomaterials have emerged as an important component to the advancement of many fields, ranging from advanced energy materials in the energy field to highly sophisticated treatment vehicles in the biomedical field. Understanding the physical behavior of nanomaterials is critical to design materials with excellent properties and performance for the many disciplines in which they are utilized and is necessary to master the various manufacturing processes that influence nanomaterial properties and behavior. This research focused on a fundamental study into the behaviors of newly developed nanomaterials under both conventional and new manufacturing processes for high performance lithium-ion batteries and for advanced …

Characterization Of The Acquisition Parameters Of A Submersible Gamma-Ray Computed Tomography System, Zhongmin Jin

Doctoral Dissertations

"The purpose of this work is to study a component of a submersible gamma-ray computed tomography (CT) system used in the non-destructive testing of irradiated nuclear fuels. The first section of this study proposes two acceleration approaches for rapidly modeling a transmission-type gamma-ray tomography system. The first relies on Monte Carlo simulations with a monodirectionally biased source sampled from a sub-volume of the whole source volume. This method estimates the real count rate using analytical correction factors. The second way of acceleration is based on deterministic calculations that use the Beer-Lambert law and detector response characteristics. It shows that both …

Novel Uses Of Distributed Optical Fiber Sensing For Geo-Mechanical Monitoring, Samuel Vincent Nowak

Doctoral Dissertations

"Rock mass monitoring in underground excavations is crucial for ensuring workplace safety and efficiency. As mines become deeper and more complex, the need to monitor larger volumes of rock during mining becomes impractical with existing instruments due to high costs. Distributed Optical Fiber Sensing (DOFS) is a powerful technology with advantages like long sensor length, real-time measurement capabilities, ease of installation, low cost, and distributed measurement. However, its application in rock mass monitoring is limited, especially in the mining industry. This study addresses a major gap in DOFS technology, specifically the inability of long-range distributed optical fiber strain sensors to …

Monitoring And Control Of Coal Dust Exposure Using Low-Cost Pm Sensors And Computational Fluid Dynamics, Nana Kobina Amoako Amoah

Doctoral Dissertations

"Overexposure to respirable coal mine dust has been linked to causing serious health problems including coal workers pneumoconiosis (CWP) and chronic massive fibrosis. The prevalence of these health problems has been on the increase since the 2000s due to increased exposure levels with roof bolter operators having the highest exposure levels. The currently used PDM3700 is too expensive, heavy and bulky which limits their use only for regulatory monitoring failing to measure miners’ personal exposure levels. Also, since roof bolter operators are more prone to elevated coal dust levels, the canopy air curtain (CAC) was developed to protect then high …

Modeling And Analysis Methods For Esd And Emi Problems, Xin Yan

Doctoral Dissertations

"Electrostatic discharge (ESD) failures and Electromagnetic interference (EMI) problems are becoming more critical in electronic devices and large systems. In this work, four studies are presented to model and analyze ESD and EMI problems.

First, a simplified physical-based model for deep-snapback transient voltage suppressors (TVS) is developed. While based on physics, the number of parameters and components is minimized. Results show that the proposed model captures the most important behaviors of the TVS response using a limited number of parameters, allowing the model to be tuned relatively easily using data obtained only from package-level transient and quasi-static measurements. Second, a …

Investigation Of Asphaltene Instability Under Gas Injection In Unconventional Reservoirs And Its Impact On Oil Recovery Performance, Mukhtar Elturki

Doctoral Dissertations

"Unconventional reservoirs, such as shale gas and tight oil formations, have become an important source of energy in recent years. However, these reservoirs often contain high levels of asphaltenes, which can lead to deposition and blockages in production wells and reduce the flow of hydrocarbons during gas enhanced oil recovery (GEOR) techniques. This study aims to experimentally evaluate the impact of miscible and immiscible carbon dioxide (CO₂) and nitrogen (N₂) on asphaltene deposition and its impact on oil recovery performance in unconventional shale reservoirs.

This research began with a comprehensive literature review and data analysis of GEOR methods in unconventional …

Melt Pool Feature Extraction, A State-Space Model And Spatial Layer-To-Layer Control For Powder Bed Fusion, Xin Wang

Doctoral Dissertations

"Powder Bed Fusion (PBF) is an Additive Manufacturing (AM) technique which can reduce material waste and is a fast-prototyping technique for complex geometries. However, the lack of consistent quality is a major problem in industrial applications. An InfraRed (IR) camera is a common tool to monitor a surface temperature field and melt pool morphology in PBF. With melt pool features from camera videos, manufacturing researchers use spatial feature maps to visualize defect locations and control researchers use layer-to-layer control to achieve more uniform melt pools and less defects.

Paper I presents a simulation method to characterize the effect of down-sampling …