Digital Commons Network^™

Enhancing Ammonium And Bicarbonate Tolerance In Chlorella Sorokiniana Through Ems-Induced Mutagenesis, Wentao Yang

McKelvey School of Engineering Theses & Dissertations

This study explores the enhancement of ammonium and bicarbonate tolerance in Chlorella sorokiniana via EMS-induced mutagenesis, aimed at improving the microalgae's resilience and growth under high-stress conditions of elevated NH4+ and HCO3 concentrations. By mutating C. sorokiniana using EMS, we developed mutant strains capable of thriving in conditions that are inhibitory to the wild type strain. The successful adaptation of these strains demonstrates a significant increase in biomass production and tolerance to environmental stressors, highlighting the potential of EMS mutagenesis in industrial algal applications for sustainable biofuel production and environmental remediation.

Utilization Of Sodium Flame Synthesis For The Formation And Deposition Of Pure Metal Materials For Applications In Additive Manufacturing, Zachariah Wargel

McKelvey School of Engineering Theses & Dissertations

Advanced material classes, such as high temperature alloys, ceramics, and refractory materials have become a key area of focus for expansion in the realm of additive manufacturing. Factors such as high melting points, material homogeneity, and physical properties such as ductility limit the application of popular additive manufacturing methods to these material classes. By utilizing sodium flame synthesis and deposition (SFD) technology, nanoparticle materials can be synthesized via combustion in a laminar co-flow diffusion burner and impacted such that the deposits can be used to manufacture designed components. By using the applicable precursor materials of metal chlorides and elemental sodium …

Experimental Design For Scientific Discovery, Quan Minh Nguyen

McKelvey School of Engineering Theses & Dissertations

Experimental design offers an elegant model of many problems where one navigates within a vast search space seeking data points with certain characteristics. A multitude of applications in science and engineering fall under this umbrella, with drug and materials discovery being prime examples. The experimental design approach maintains a probabilistic model of the search space, and uses Bayesian decision theory accounting for this model to guide the accumulation of observed data to maximize an experimentation objective of interest. This dissertation explores Bayesian optimization and active search, two realizations of the experimental design framework that model discovery tasks. While existing solutions …

Epigenetic Regulation Of Skeletal Development, Austin Bell-Hensley

McKelvey School of Engineering Theses & Dissertations

Treatment of disorders that disrupt homeostasis of skeletal tissues, such as osteoarthritis, and developmental skeletal diseases, such as overgrowth syndromes, requires a precise understanding of skeletal development. Osteoarthritis is a whole joint disorder that can be caused by articular cartilage defects that illicit an inflammatory immune response. Articular cartilage does not have intrinsic processes for repair or regeneration, so it is necessary to develop tissue constructs to repair the native tissue. Since articular cartilage is not capable of repair, it is difficult to engraft cartilage tissue constructs. As such, it is necessary to develop a layered osteochondral construct that can …

Optical Imaging To Investigate Neurovascular Injury, Repair, And Disease, Ryan Michael Bowen

McKelvey School of Engineering Theses & Dissertations

Local neural circuitry and global neural networks in the brain are often investigated using mesoscopic, hemodynamic imaging such as optical intrinsic signal (OIS) imaging or functional magnetic resonance imaging (fMRI), relying on oximetric signals as proxies of neural activity. However, the tight neurovascular coupling that ties regional changes in blood flow to changes in neural activity in normal states can be severely disrupted in disease states. I show that neurovascular coupling is significantly interrupted in mouse models of Cantu syndrome, a rare disease caused by gain-of-function mutations in ATP-sensitive potassium (KATP) channels. Such marked disruptions in neurovascular coupling in disease …

Design And Characterization Of 3d-Printed Hydrogel Lattices With Consistent Structural And Mechanical Anisotropy, Daniel Yoon

McKelvey School of Engineering Theses & Dissertations

This thesis explores the use of 3D printing to fabricate soft hydrogel lattice structures with consistent properties, including varying levels of mechanical anisotropy. Magnetic resonance elastography (MRE) is a non-invasive imaging tool to estimate and characterize the mechanical properties of tissue. MRE “phantoms” (physical surrogate models) have been used to assess how well MRE can measure and estimate mechanical properties. While gel phantoms generally simulate brain tissue, almost all have been isotropic. Prior studies have shown that white matter brain tissue is structurally and mechanically anisotropic. To validate anisotropic MRE, phantoms with controllable, reproducible anisotropic material properties are needed. This …

Investigation Of Volatility, Composition, And Gas-Particle Phase Partitioning Of Atmospheric Organic Compounds Through Novel Instrumentation And Techniques, Karolina Cysneiros De Carvalho

McKelvey School of Engineering Theses & Dissertations

Atmospheric aerosols are ubiquitous indoors and outdoors and their impact on human life on Earth is extensive. Aerosol particles scatter and absorb solar radiation, are key in the formation of clouds and precipitation, and can affect the abundance and distribution of greenhouse and atmospheric trace gases by physicochemical multiphase processes, thus they play an important role in regulating regional and global climate. On the other hand, poor indoor and outdoor air quality associated with high particulate matter (PM) levels is among the leading health risks worldwide, affecting life quality and expectancy by increasing the risk of cancer, cardiovascular and respiratory …

A Distributed And Hybrid Ai-Based Security Framework For 5g Real-Time Applications, Ali Ghubaish

McKelvey School of Engineering Theses & Dissertations

This dissertation develops a multifaceted security framework tailored for 5G-enabled real-time Internet of medical things (IoMT) systems to significantly enhance the security infrastructure within healthcare environments. The framework pivots around three core technological advancements: the development of the Light feature Engineering based on the Mean Decrease in Accuracy (LEMDA), the construction of a 5G testbed that serves as a distributed intrusion detection system (IDS), and the implementation of a hybrid deep reinforcement learning (HDRL) method. LEMDA represents a breakthrough in data processing for IoMT systems. By intelligently reducing data complexity, LEMDA enhances the speed and accuracy of threat detection mechanisms, …

Application Of Finite-State Wake Models To Rotors Re-Entering Their Own Wake, Michael Seay Morrow

McKelvey School of Engineering Theses & Dissertations

This paper details the development of a finite-state, dynamic wake model for the purpose of modeling a helicopter rotor reentering its own wake. This model stems directly from both the Peters-Morillo wake model to determine the velocity field on and above the helicopter rotor and the Peters-Fei model to compute the velocity field below the rotor. The specific case of nonzero net thrust was evaluated under assumptions of axial flow and potential flow theory. Results consist of computations of the inflow velocity for this case, along with comparison to closed-form, potential flow solutions for validation. The finite-state model is shown …

Air Quality Assessment On Local And Hyperlocal Scales, Zhiyao Li

McKelvey School of Engineering Theses & Dissertations

Air quality monitoring across local and hyperlocal scales has attracted increased attention from both the public and research community. There are several approaches such as passive samplers and low-cost air quality sensors, depending on the pollutant and measurement objectives. Local and hyperlocal air pollutant measurements help to characterize local emission sources such as traffic and industry, including separating these signals from large scale influences (e.g., urban and regional scales), and better understand how land use types and meteorology influence pollutant spatiotemporal patterns. Low-cost sensors (LCS) are now a popular approach to monitor several criteria pollutants (e.g., particulate matter (PM), ozone, …

Stimulation Of Peripheral Nerves In M. Mulatta For Somatosensory Psychophysics And Vns Applications, Tyler Schlichenmeyer

McKelvey School of Engineering Theses & Dissertations

Cuff-style peripheral nerve interfaces (PNIs) communicate with the central nervous system and offer interesting advantages when compared with other neural interfaces, including brain-computer interfaces (BCIs) and non-cuff PNI designs. PNI development must consider design factors such as volume of neural activity being driven or recorded, specificity of stimulus activation, and longevity of the device. This dissertation provides an analytical framework for PNI experiments, showcasing two experiments where PNIs were implanted in highly trained macaque monkeys. We applied foundational psychophysical procedures and other behavioral paradigms to examine the relationship between the input electrical stimulus delivered by a cuff electrode and the …

Improving And Modeling Heterogeneous Streaming Computation, Clayton Faber

McKelvey School of Engineering Theses & Dissertations

Data streaming algorithms are a class of problems that deal with moving data through a system while being processed. When implementing these types of algorithms a developer will spend time tuning an implementation for deployment, but if they are using heterogeneous architectures or when nodes of computation are physically separate from one another performance may be lost to unforeseen data movement complications. In this work we aim to alleviate some of these pain points through a combination of programming advice and mathematical models. One of the pain points often unseen and underappreciated by developers is a type of data streaming …

Development, Numerical Simulation And Turbulence Modeling Of A Sustainable Transonic Truss-Braced Wing Aircraft Using Liquid Hydrogen Fuel And Active Flow Control, Bryce Zachary Thomas

McKelvey School of Engineering Theses & Dissertations

There is pressing need for emissions reduction and an increase in efficiency for the next generation of commercial aircraft in order to reduce the environmental impact of the aviation sector and combat global climate change. The implementation of alternative fuels as well as new engine and wing designs are actively being explored as methods to reduce emissions. This thesis analyzes the implementation of hydrogen fuel, a transonic truss braced wing and active flow controls as means to improve the performance of a medium range commercial airliner. The widespread adoption of cryogenic liquid hydrogen (LH2) fuel as a green alternative to …

Localization And Collision Prediction Via Rf Transceiver And Radar Methods, Aarti Singh

McKelvey School of Engineering Theses & Dissertations

In domains like automation, particularly in advanced driver-assistance and collision avoidance systems for vehicles, the need for reliable sensing and predictive capabilities is paramount. While current sensor technologies allow for quick responses to safety-critical events, there is a growing emphasis on predictive capabilities to anticipate and prevent such incidents. This opens new ideas for the development of sophisticated RF-sensors and algorithms capable of accurately predicting potential harms before they occur. Moreover, along with the benefits of enhanced sensing capabilities comes the imperative to safeguard user-privacy. Various techniques, including encryption and differential privacy, are employed to ensure that RF-based services do …

Coupling Treatment Technologies With Bioelectrochemical Systems To Optimize Resource Recovery From Wastewater, Matthew Stephen Ferby

McKelvey School of Engineering Theses & Dissertations

Wastewater is a common waste produced from municipal, agricultural, and industrial processes. As the world’s population increases, the amount of wastewater produced globally is expected to reach approximately 450 billion m3 in the next two decades. Issues surrounding water, food, and energy accessibility will also become more imminent as the population grows. Interestingly, wastewater is an unconventional source of resources including water, nutrients (e.g., NH4+ and PO43-), and energy. However, conventional wastewater treatment processes focus primarily on the removal of containments rather than the recovery of resources. Bioelectrochemical systems (BES) have the ability to recover resources from wastewater. These engineered …

Tree Recovery By Dynamic Programming, Gustavo Alberto Gratacos

McKelvey School of Engineering Theses & Dissertations

Tree-like structures are common, naturally occurring objects that are of interest to many fields of study, such as plant science and biomedicine. Analysis of these structures is typically based on skeletons extracted from captured data, which often contain spurious segments or cycles that need to be removed. We propose a dynamic programming algorithm which seeks to recover directed trees from these noisy skeletons. Our method recovers trees by removing edges and duplicating nodes while adhering to edge-label constraints. Our algorithm proceeds by iteratively merging graph nodes, such that the solution on the original graph can be obtained from those on …

Characteristics Based Factor Models - Comparison Of Estimation Procedures, Henri Ohl

McKelvey School of Engineering Theses & Dissertations

Understanding cross-sectional and time series variation of asset returns is fundamental in finance, particularly in asset pricing. This thesis explores the integration of factor theory with machine learning to deepen our comprehension of these dynamics. Characteristics based factor models offer a systematic framework for quantifying an asset's underlying risk-return structure, leveraging time-varying conditional information on model parameters carried by firm-specific characteristics. These models serve as valuable tools for discerning the driving components of an asset's expected excess return. Recent research established a novel methodology for consistent parameter estimation within this framework, only requiring a large cross-section but not a long …

Mending Trust In Ai: Trust Repair Policy Interventions For Large Language Models In Visual Data Journalism, Hangxiao Zhu

McKelvey School of Engineering Theses & Dissertations

Trust in Large Language Models (LLMs) emerged as a pivotal concern. This is because, despite the transformative potential of LLMs in enhancing the interpretability and interactivity of complex datasets, the opacity of these models and instances of inaccuracies or biases have led to a significant trust deficit among end-users. Moreover, there is a tendency for people to personify AI tools that utilize these LLMs, attributing abilities and sensibilities that they do not truly possess. This thesis exploits this personification and proposes a comprehensive framework of trust repair policies tailored to address the challenges inherent in LLM annotations within data journalism …

The Conceptual Design, Analysis And Optimization Of A Hydrogen Combustion And A Hydrogen Fuel-Cell Powered Aircraft, Michael Kiely

McKelvey School of Engineering Theses & Dissertations

In the effort to combat climate change worldwide, the aviation industry faces particularly complex design challenges in designing new, emission free vehicles. One potential solution to this problem is the use of hydrogen fuel as a means of propulsion. Hydrogen fuel has many benefits over traditional jet fuel such as a higher gravimetric energy density; however, it requires the aircraft to carry large, pressurized, cryogenic fuel tanks. This thesis examines the design challenges, potential solutions, and the analysis methods for the design of a short to medium range hydrogen powered commercial airliner. To accomplish this goal, a comprehensive conceptual design …

Integrating Implantable Bci Devices Within Bci2000 Using A Unified Framework And Toolchain For In-Vivo Research, Dhruva Mehta

McKelvey School of Engineering Theses & Dissertations

The field of neurotechnology research has a bright and promising future as more devices are created. However, there are still many gaps in the field as the potential for neuromodulation grows. Devices such as the Micro-Leads StimZ system and the Ripple Grapevine/Summit system help bridge that gap by allowing for a broader variety of closed-loop neuromodulation experiments to be implemented thanks to their portability and versatility. Despite these devices being on the market, however, there needs to be a method to collaborate and interact with them across multiple research institutions. BCI2000 helps to address that by creating a standardized working …

Evaluating Neuroimaging Modalities In The A/T/N Framework: Single And Combined Fdg-Pet And T1-Weighted Mri For Alzheimer’S Diagnosis, Peiwang Liu

McKelvey School of Engineering Theses & Dissertations

With the escalating prevalence of dementia, particularly Alzheimer's Disease (AD), the need for early and precise diagnostic techniques is rising. This study delves into the comparative efficacy of Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) and T1-weighted Magnetic Resonance Imaging (MRI) in diagnosing AD, where the integration of multimodal models is becoming a trend. Leveraging data from the Alzheimer's Disease Neuroimaging Initiative (ADNI), we employed linear Support Vector Machines (SVM) to assess the diagnostic potential of these modalities, both individually and in combination, within the AD continuum. Our analysis, under the A/T/N framework's 'N' category, reveals that FDG-PET consistently outperforms T1w-MRI across …

Fabrication Of Two-Dimensional Material-Based Nano-Capacitors Using Bismuth Selenite (Bi2seo5) To Study Its Dielectric Properties, Major Kc

McKelvey School of Engineering Theses & Dissertations

In recent years, the demand for high-performance micro and nanodevices has surged, necessitating the exploration of novel dielectric materials to replace conventional silicon dioxide. Following the continuation of the Moorse law, as device dimensions reduce to nanoscale levels, the properties of silicon dioxide can degrade, leading to issues such as increased leakage current and reduced gate control. Materials with superior electrical properties, such as higher dielectric constant, lower leakage current, and better thermal stability allowing for the development of faster, more efficient, and more reliable devices are in higher demand than ever. Two-dimensional layered semiconductor nanomaterials represented by compounds such …

Investigating Murine Uterine Tissue Dynamics: Biomechanical And Histological Perspectives On Postpartum Involution And Scar-Induced Remodeling, Savannah Elizabeth Chatman

McKelvey School of Engineering Theses & Dissertations

During pregnancy, the uterus undergoes structural and mechanical transformations to withstand the demands of a successful delivery. In cases where vaginal birth is not feasible, a Cesarean section (c-section), which involves a transverse abdominal incision, is used to facilitate delivery of the fetus and placenta¹. Following the procedure, the uterus and abdominal tissue are carefully sutured to support postpartum recovery, leading to uterine scarring at the incision site^1,2. Understanding the relationship between uterine scar integrity, postpartum involution, and the biomechanics of uterine tissue is a crucial step toward predicting the risk of uterine rupture during future …

Development Of A Wearable Short-Wave Infrared Photoplethysmography Device For Detection And Monitoring Of Hemodilution During Postpartum Hemorrhage, Hannah Gruensfelder

McKelvey School of Engineering Theses & Dissertations

ABSTRACT OF THE THESIS

A Thesis on the Development of a Wearable Short-Wave Infrared Photoplethysmography Device for Detection and Monitoring of Hemodilution During Postpartum Hemorrhage

by

Hannah Gruensfelder

Master of Science in Biomedical Engineering

Washington University in St. Louis, 2024

Professor Christine O’Brien, Chair

Postpartum hemorrhage (PPH), the leading cause of maternal death and morbidity, affects nearly 14 million people worldwide each year, disproportionally impacting racial minorities and people in low resource settings. A timely diagnosis of PPH is key in providing optimal patient care, as an estimated 90% of deaths due to PPH are preventable with early diagnosis and …

Numerical Simulations Of Supersonic/ Hypersonic Flows In Compression Corners And A Hypersonic Flow Study Of Atmospheric Entry Of Mars Science Laboratory Capsule, Dexter Allen

McKelvey School of Engineering Theses & Dissertations

This thesis consists of two related parts. The first part is the study of supersonic/hypersonic flow in compression corners. The compression corners are simple geometries but rich in flow-features that can be challenging for accurate prediction of their flow fields in high-speed compressible flow using the Reynold-Averaged Navier-Stokes (RANS) equations in conjunction with a turbulence model. At higher degrees of corner angles, there exists a shock-boundary layer interaction region which includes a significant recirculation zone in the corner. In this thesis, experimentally available test cases for compression corner at Mach 3, 8, and 11 at various corner angles are modeled …

Environment And Response Of 3d-Encapsulated Mesenchymal Stem Cells To Mechanical Loading, Augustus Greenwood

McKelvey School of Engineering Theses & Dissertations

This thesis explores the micromechanical environment induced when cyclically compressing hydrogels via finite element modeling and experimentally on the impact of loading on mesenchymal stem cells (MSCs) when encapsulated withing 3D hydrogel matrices. Degenerative joint diseases, characterized by cartilage degradation, present significant challenges due to cartilage's limited self-repair capacity. Innovative approaches, including stem cell-based therapies and engineered biomaterials, have emerged as promising strategies for cartilage repair and regeneration. This work specifically investigates the calibration of a bioreactor, the uniformity of load response across the hydrogel constructs via finite element modeling (FEM), and the stress response of MSCs subjected to various …

The Role Of Voluntary Descending Control In Enhancing Motor Function Via Transcutaneous Spinal Cord Stimulation, Yoon Kim

McKelvey School of Engineering Theses & Dissertations

Spinal cord injury (SCI) is a life-changing event that causes lasting motor impairments. Transcutaneous spinal cord stimulation (tSCS), a non-invasive form of neuromodulation in which electrodes are placed on the skin and used to stimulate the spinal circuits via an electrical current, has demonstrated positive effects on motor function recovery in individuals who have had SCIs. However, the precise mechanism of how tSCS interacts with voluntary descending drive remains poorly understood. This study aims to investigate the role of voluntary descending control in influencing reflex responses triggered by tSCS.

Electromyography (EMG) recordings were performed in ten unimpaired individuals while they …

Modeling Of Nk Cells In Pediatric Patients With Unusually Severe Or Recurrent Hsv Using High-Dimensional Flow Cytometry, Yunran Feng

McKelvey School of Engineering Theses & Dissertations

HSV infection is broadly spread all over the world with some patients having severe and/or recurrent HSV infections. Our lab studies human Natural Killer (NK) cells, which are important in innate immune responses to viral infections and tumors. A publication in 2013 by Ornstein et al from our lab studied HSV+ pediatric patients and found some associations between severe infection and defects in NK cytolytic function. PLCG2 haploinsufficient variants found in 2 HSV patients causing PLCγ2 hypophosphorylation, and loss of cytolytic function in NK cells is a novel finding recently published by Alinger et al from our lab in 2023. …

Low Impedance, Durable, Self-Adhesive Hydrogel Epidermal Electrodes For Electrophysiology Recording, Naiyan Wu

McKelvey School of Engineering Theses & Dissertations

Traditional electrodes used for electrophysiology recording, characterized by their hard, dry, and inanimate nature, are fundamentally mismatched with the soft, moist, and bioactive characteristics of biological tissues, leading to suboptimal skin-electrode interfaces. Hydrogel materials, mirroring the high water content and biocompatibility of biological tissues, emerge as promising candidates for epidermal electronic materials due to their adjustable physicochemical properties. However, challenges such as inadequate electrical conductivity, elevated skin impedance, unreliable adhesion in moist conditions, and performance decline from dehydration have significantly restricted the efficacy and applicability of hydrogel-based electrodes. In this thesis, we report a high-performance hydrogel epidermal electrode patch for …

Engineering Mussel Foot Protein 5 (Mfp5) For Enhanced Adhesive Performance In Tendon And Bone Repair, Ziyue Zhu

McKelvey School of Engineering Theses & Dissertations

This study explores the development of Mussel Foot Protein 5 (MFP5) bioadhesives to improve tendon-to-tendon and tendon-to-bone adhesive outcomes. MFP5, known for its underwater adhesive properties, was synthesized using recombinant techniques and optimized through coacervation and cross-linking. Adhesion tests demonstrated the superior performance of the optimized MFP5 adhesive on the tendon and bone samples. Improved protein concentration testing and purification methods enhanced MFP5 yield and consistency. Future research will focus on further standardization, exploring alternative purification methods, and evaluating the adhesive's performance in animal models. This study lays a foundation for developing robust MFP5-based bioadhesives, potentially revolutionizing surgical repair techniques …