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Utilizing Extended Continental Shelf (Ecs) And Ocean Exploration Mapping Data For Standardized Marine Ecological Classification Of The U.S. Atlantic Margin, Derek C. Sowers

Doctoral Dissertations

Accurate maps of ocean bathymetry and seafloor habitats are needed to support effective marine ecosystem-based management (EBM) approaches. The central premise of this thesis was to synthesize geomorphological elements of large regions of the deep ocean seafloor to establish standards of characterization for ecosystem-based classification. The approach was to apply semi-automated characterization techniques on seafloor bathymetric data that were originally collected for other purposes. The purpose of generating these maps is ultimately to apply to informing ecosystem-based management for large marine regions. While seafloor classification techniques for habitat classification have been applied in shallow water and generally over more local …

Analysis Of The Population Dynamics Of Placida Dendritica And Codium Fragile In The Gulf Of Maine And A Theoretical Discussion Of Invasive Species, Seth Goodnight

Doctoral Dissertations

This dissertation examines several aspects of the biology and ecology of Codium fragile and Placida dendritica in the Gulf of Maine. Scientific interest in nonindigenous species was examined to determine if any patterns were evident that might indicate a change in the status of an invasive species. Interest in C. fragile had waned in recent years, the timing of which coincides with the decreased ecological dominance and apparent naturalization of the alga. Laboratory and field studies were combined to quantify the dynamics in the population of C. fragile and in the recruitment dynamics of P. dendritica. Results of laboratory research …

Computational Studies Of Small Molecule Transport And Binding, Yong Liu

Doctoral Dissertations

In this thesis, I have studied two classes of systems using molecular dynamics (MD) simulations as a primary approach. The first class of systems is responsible for transport of small molecules. Specically, I have investigated diffusion pathways of inhibitory gas CO within the enzyme FeFe-hydrogenase as well as water transport in articial water channels. The second class of systems are biological proteins and their interactions with ligands. I have focused on Regulators of G-protein Signaling (RGS) proteins and their binding to thiadiazolidinone (TDZD) based small-molecule inhibitors as well as phosphosdiesterase 6 (PDE6) binding with cyclic guanosine monophosphate (cGMP).

Specically, I …

Soil Health Assessment For The Agroecosystems Of West Tennessee, Surendra Singh

Doctoral Dissertations

Soil health assessment is important for making informed sustainable management decisions in production systems. An established standardized method to quantify soil health is lacking and the validity of the existing methods across agroecoregions and cropping systems is not yet proven. Therefore, this study aims to evaluate the feasibility of widely discussed three soil health tests - Haney’s Soil Health Test (HSHT), Comprehensive Assessment of Soil Health (CASH), and Alabama Soil Health Index (ASHI) to assess soil health in diverse cropping systems of Tennessee. Since these approaches were originally developed for specific agroecoregions, we hypothesized that these tests are not sensitive …

Computer Simulations Of Biological Systems: From Protein Dynamics To Drug Discovery, Rupesh Agarwal

Doctoral Dissertations

Computational biophysics methods such as molecular dynamics (MD) simulations are often used in combination with experimental techniques like neutron scattering, NMR, and FTIR to explore protein conformational landscapes. With the improvements in experimental techniques, there is also a need to continually optimize the MD forcefield parameters to make precise predictions that match experimental results. To complement many of these experiments, an accurate model of deuteration is frequently required, but has been elusive. In our work, we developed a novel method to capture isotope effects in classical MD simulations by re-parameterization of the bonded terms of the CHARMM forcefield using quantum …

3d Study Of Gas Hydrate Formation And Dissociation In Porous Media And Dem Modeling Of Granular Materials, Zaher Jarrar

Doctoral Dissertations

Natural methane gas hydrates availability and ongoing rise in demand for energy, motivated researchers to consider gas hydrates as a potential energy source. Production of methane from hydrate-bearing sediments requires hydrate dissociation for releasing mobile methane gas in sediments prior to gas production operations. Fines may migrate through or clog the pore space of sandy sediments depending on the geometry and topology of the pore space. This dissertation employs unique in situ experiments and techniques to gain a comprehensive understanding of the associated physical processes (such as fines migration, clogging and gas driven fracture) and validation of hydrate dissociation models’ …

Multiphysics Assessment Of Accident Tolerant Fuel, Cladding, And Core Structural Material Concepts, Jacob Preston Gorton

Doctoral Dissertations

The severe accident at the Fukushima-Daiichi nuclear power plant in 2011 ignited a global research and development effort to replace traditionally-used materials in Light Water Reactors (LWRs) with Accident Tolerant Fuel (ATF) materials. These materials are intended to extend the coping time of nuclear power plants during severe accident scenarios, but must undergo thorough safety and performance evaluations before being implemented. Four ATF concepts are analyzed in this dissertation using state-of-the-art computer modeling tools: (1) iron-chromium-aluminum (FeCrAl) fuel rod cladding, (2) silicon carbide (SiC) fiber-reinforced, SiC matrix composite (SiC/SiC) boiling water reactor (BWR) channel boxes, (3) mixed thorium mononitride (ThN) …

Engineered Carbon Materials With Nano-Graphitic Domains Derived From Lignin, Valerie Garcia Negron

Doctoral Dissertations

This work focuses on establishing a comprehensive understanding of lignin-derived materials as a function of carbonization with the goal of identifying processing-structure-property-performance relationships. A combination of modeling, statistical, and empirical materials characterization techniques are applied to lignin materials varying in feedstock source, extraction method, and processing conditions. The first part of this study evaluates the structure of carbon composite materials, possessing both crystalline and amorphous domains, using scattering techniques. One approach performs atomistic simulations of a proposed structure, from which the analogous scattering pattern can be obtained for validation. An alternative approach based on a hierarchical decomposition of the radial …

A Review Of Horticultural Therapy And Horticultural Therapy Education In The United States: Addressing Challenges And Opportunities, Derrick R. Stowell

Doctoral Dissertations

The Horticultural Therapy (HT) profession has been formally organized in the United States since 1973. Despite the long history of horticulture being used as therapy, the profession of HT in the United States has not advanced as quickly as other allied healthcare professions. This study will review the current challenges and opportunities for HT and HT education in the United States.

A qualitative study of the status of the profession was conducted to determine what challenges and opportunities the profession of HT currently has and how the profession can meet those challenges and opportunities. The study sample was recruited from …

Nonparametric Bayesian Deep Learning For Scientific Data Analysis, Devanshu Agrawal

Doctoral Dissertations

Deep learning (DL) has emerged as the leading paradigm for predictive modeling in a variety of domains, especially those involving large volumes of high-dimensional spatio-temporal data such as images and text. With the rise of big data in scientific and engineering problems, there is now considerable interest in the research and development of DL for scientific applications. The scientific domain, however, poses unique challenges for DL, including special emphasis on interpretability and robustness. In particular, a priority of the Department of Energy (DOE) is the research and development of probabilistic ML methods that are robust to overfitting and offer reliable …

Discontinuous Recycled And Repurposed Carbon Fiber Reinforced Thermoplastic Organosheet Composites, Philip R. Barnett

Doctoral Dissertations

There is a significant need for low cost, high volume composites in the automotive industry to aid in vehicle lightweighting and safety. The current state-of-the-art severely compromises the mechanical properties of composites to achieve cost and cycle time goals. In this dissertation, a novel composite format, termed discontinuous carbon fiber organosheets, using recycled and repurposed carbon fibers in a thermoplastic matrix is developed and studied. Unlike traditional composites, the long fiber length and rapid processing time yield mechanical properties and cycle times competitive with automotive metals.

Several studies were performed to characterize this new material format. First, samples were manufactured …

Enhanced Kinetics And Modeling Of Pan-Based Carbon Felt Anodes In Vanadium Redox Flow Batteries, Michael Cyrus Daugherty

Doctoral Dissertations

All-vanadium redox flow batteries (VRFBs) are a promising technology for grid-level energy storage, however, there are still several limitations in the forms of durability, efficiency, and overall costs, which are barriers to its commercial viability. With both bulk electrolyte flowing through its porous matrix and species flux at the solid-electrolyte interface, electrodes are the component of VRFB systems which host electrochemical reactions and facilitate contact between the liquid phase electrolyte and the electronically conductive solid phase. While the more limiting electrode in VRFB systems is dependent on the material, for polyacrylonitrile (PAN)-based carbon felts, the anode constitutes a larger portion …

Soil Moisture Sensitivity Of Microbial Processing Of Soil Organic Carbon, Shikha Singh

Doctoral Dissertations

Soil organic carbon (SOC) is the largest terrestrial C pool and understanding SOC decomposition in response to environmental factors is critical for accurate predictions of climatic change. Soil moisture is one of the most important, yet less explored, environmental factors controlling soil microbial respiration. The relationship between soil moisture and respiration also varies with soil texture. Currently, it is difficult to predict feedbacks to climatic changes from changes in soil moisture, as most earth system models lack site-specific, experimentally-derived parameters to represent soil moisture-texture-respiration relationships. The overarching goals of this dissertation are to gain a fundamental understanding of the interactive …

Development Of A Novel Casting Alloy Composed Of Aluminum And Cerium With Other Minor Additions, Zachary Cole Sims

Doctoral Dissertations

Eutectic casting alloys of aluminum and cerium are a recent discovery and early research describes an alloy with great potential to meet the growing demand for a lightweight, economical, high specific strength material for use in high-temperature or extremely corrosive environments. The broad application of aluminum alloys across industry sectors is driven by their collection of balanced properties including economical cost, high specific strength, and flexibility of their production pathways. Additionally, their high corrosion resistance makes them a good choice for structural materials. Despite this, the push to use aluminum alloys in ever more extreme environments with higher temperatures, stresses, …

Portrayals Of Hashtag Activism In Southeast Asia: A Case Study Of #Novatoneducation Citizen Movement In Bangladesh, Umana Anjalin

Doctoral Dissertations

During 2015, the government of Bangladesh imposed a value-added tax (VAT) on private university education in order to expand the purview of revenue collection. Fearing this additional hike in the tuition fees, thousands of mostly middle-class students protested that this would add to the already existing burden on their families in supporting their education. The country’s socioeconomic backdrop of culture and the economic scenario was such where the parents had to bear a lot for their children’s expenses for a long time until the children became independent. On top of such already overpriced expenses, the question of bearing VAT became …

Principals’ Perspectives On Turning Around Failing Urban Middle Schools: A Study Of Change In Two Schools, Moniqueca Hicks

Doctoral Dissertations

Principal leadership plays an important role in the achievement of students. However, extant school reform literature notes that there is a shortage of highly qualified principals prepared to turn around failing schools, putting many students at risk. A multi-site qualitative case study was utilized and data was collected from two urban middle school principals through semi-structured interviews, observations and the collection of documents. This study examines how two urban middle school principals in the state of Tennessee, who have been successful in turning around a school, articulate their process and strategies for change. The method used in choosing the site …

Emerging Zoonotic Pathogens At The Human-Wildlife Interface In Protected Areas: Game In The Southeastern United States And Bushmeat In Northern Uganda, Breeanna M. Dell

Doctoral Dissertations

The emergence of zoonotic pathogens through contact with animal reservoirs is a well-documented phenomenon and growing concern for public health. Particularly in light of the ongoing Ebola epidemic in the Democratic Republic of the Congo and the coronavirus pandemic, the need to understand mechanisms of contact and disease transmission at the human-wildlife interface and to understand which infectious agents may reside within wildlife reservoirs crucial. In this project, we investigated the potential introduction of zoonotic cestode Echinococcus canadensis to public lands in Tennessee subsequent to elk translocation effort and aimed to identify whether a transmission cycle was established in this …

Fall Risk Factors Among Hospitalized Older Adults With Alzheimer’S Disease And Related Dementias, Jean Bettencourtt Sconza

Doctoral Dissertations

Falls are a common and devastating complication of hospital admission for older adults. Falls are especially significant for those with Alzheimer’s Disease and related dementias (ADRD) as they are at high risk to fall and to suffer injuries from falling. Despite the large body of research on falls in hospitals, less is known about fall risk factors among patients with ADRD. The purpose of this retrospective case-control study was to determine which risk factors are predictors of falls among hospitalized older adults with Alzheimer’s disease and related dementias (ADRD) by comparing those who fell with those who did not fall. …

A High Resolution Study Of Long-Term Vertebrate Decomposition In Human And Animal Model Systems, Lois S. Taylor

Doctoral Dissertations

The effects of vertebrate decomposition are wide-ranging across multiple foodwebs, and have been shown to persist in the environment, however there is a lack of systematic assessment of these changes over long periods of time or in sufficiently high resolution as to resolve seasonal flux patterns. The ultimate aim of this body of research was to explore nematode systematics in decomposition environments, culminating in a pair of long-term human decomposition seasonal trials, in high resolution, with the specific intent of integrating the fields of soil chemistry, microbial ecology, and nematology in order to assess the relationships of cross-disciplinary impacts. Of …

Analysis Of The Population Dynamics Of Placida Dendritica And Codium Fragile In The Gulf Of Maine And A Theoretical Discussion Of Invasive Species, Seth Goodnight

Doctoral Dissertations

This dissertation examines several aspects of the biology and ecology of Codium fragile and Placida dendritica in the Gulf of Maine. Scientific interest in nonindigenous species was examined to determine if any patterns were evident that might indicate a change in the status of an invasive species. Interest in C. fragile had waned in recent years, the timing of which coincides with the decreased ecological dominance and apparent naturalization of the alga. Laboratory and field studies were combined to quantify the dynamics in the population of C. fragile and in the recruitment dynamics of P. dendritica. Results of laboratory research …

Utilizing Extended Continental Shelf (Ecs) And Ocean Exploration Mapping Data For Standardized Marine Ecological Classification Of The U.S. Atlantic Margin, Derek C. Sowers

Doctoral Dissertations

Accurate maps of ocean bathymetry and seafloor habitats are needed to support effective marine ecosystem-based management (EBM) approaches. The central premise of this thesis was to synthesize geomorphological elements of large regions of the deep ocean seafloor to establish standards of characterization for ecosystem-based classification. The approach was to apply semi-automated characterization techniques on seafloor bathymetric data that were originally collected for other purposes. The purpose of generating these maps is ultimately to apply to informing ecosystem-based management for large marine regions. While seafloor classification techniques for habitat classification have been applied in shallow water and generally over more local …

Computational Studies Of Small Molecule Transport And Binding, Yong Liu

Doctoral Dissertations

In this thesis, I have studied two classes of systems using molecular dynamics (MD) simulations as a primary approach. The first class of systems is responsible for transport of small molecules. Specically, I have investigated diffusion pathways of inhibitory gas CO within the enzyme FeFe-hydrogenase as well as water transport in articial water channels. The second class of systems are biological proteins and their interactions with ligands. I have focused on Regulators of G-protein Signaling (RGS) proteins and their binding to thiadiazolidinone (TDZD) based small-molecule inhibitors as well as phosphosdiesterase 6 (PDE6) binding with cyclic guanosine monophosphate (cGMP).

Specically, I …

Thermoplastic Additive Manufacturing For Composites And Molds, Pritesh S. Yeole

Doctoral Dissertations

Recent inventions in the ability of additive manufacturing (AM) to use carbon fiber (CF) reinforced pellets as a feedstock material to manufacture components has complemented its purpose from prototypes to structural load-bearing parts. In the first part of this research, we investigated the processability, microstructure, and mechanical performance of twin-screw compounded short CF reinforced polyphenylene sulfide (PPS) pellets as a feedstock material for extrusion deposition fabrication-additive manufacturing (EDF-AM) using big area AM (BAAM). The performance of the BAAM components was compared to that of traditional processing methods, namely injection molding (IM) and extrusion-compression molding (ECM). It was found that the …

Development Of A Robust Wideband Gnss Rf Frontend With Resilient Interference Blocking, Farshid Tamjid

Doctoral Dissertations

Recently, there has been an increasing demand for GNSS systems’ use for numerous applications such as public security, disaster relief, weather forecast, transportation, hydrologic monitoring, aviation, navigation positions and so on. Such systems must have a wideband performance (1.16 GHz to 1.61 GHz), high quality reception (which requires antenna with low AR, high RHCP gain, high F/B ratio, and high RL), portable size, and low cost. Our efforts here are geared towards the receiving side of such communication. The antennas are the first stage of the long receiver chain. Development of such wideband high quality antennas is challenging as most …

More Than The Sum Of Their Parts: Building A Framework For Understanding Host-Microbe Interactions In Medicago Sativa, Katherine Mackenzie Moccia

Doctoral Dissertations

This dissertation seeks to understand plant-microbe interactions in the agriculturally relevant plant Medicago sativa from three distinct vantage points within microbiology. Within the plant microbiome, we examine how primer usage and the application of peptide nucleic acids impacts 16S and 18S rRNA gene sequencing. In doing so, we design a novel peptide nucleic acid, PNA, and test its impact using multiple primers and sequencing protocols. Once microbial sequencing methodology is established, we generate a synthetic consortium of bacterial isolates from M. sativa leaves and modulate nitrogen levels to better understand microbial structure. Drop out communities, where we remove one member …

Above- And Below-Ground Community Responses To A Mutualism-Disrupting Allelopathic Invasive Plant, Morgan Dake Roche

Doctoral Dissertations

To understand the dynamics of biological invasions, mechanisms of invaders’ impacts must be assessed across scales of ecological organization, and under different biotic and abiotic conditions. Traits of invasive species that generate successful competitors such as high fecundity, efficient resource acquisition, or novel chemical weapons allow them to rapidly increase in abundance and negatively affect native communities. Mycorrhizal mutualism disruption is a common and well-supported mechanism of impact of invasive plants, where allelopathic chemicals indirectly impact native plant species via disruption of mycorrhizal soil resource uptake. However, not all native plant species depend on mycorrhizal fungi, creating opportunities for allelopathic …

3d Genome Architecture Under Stress: A Survey Of Ionizing Radiation, Progeria, And Osmotic Stress, Jacob Tyler Sanders

Doctoral Dissertations

The human nucleus contains 2 meters of DNA which is intricately folded into a three-dimensional (3D) structure. It has become increasingly clear that this 3D structure plays an important role in the expression of genes. Proper gene expression is necessary for cellular homeostasis, cell state, and response to environmental/physical perturbations. Faithful repair of damage DNA damage is necessary to prevent genomic aberrations, such as translocations, which may lead to misregulation of gene expression. Hi-C, a sequencing technique that labels proximal chromatin interactions, provides a clearer picture of how the genome is spatially organized within the nucleus. Here, we discuss the …

Engineering Platforms For Advancing Plant Synthetic Biology, Tayler Marie Schimel Mcneillie

Doctoral Dissertations

This work describes research aimed at adapting advanced engineering systems for plant biotechnology. The droplet interface bilayer (DIB) is a robust and versatile platform for replicating model cell membranes, providing a bottom-up approach for synthetic cell- and tissue-like structures. In this work, a microfluidic device featuring five inlets, one for the continuous oil phase and four discrete aqueous channels for droplet generation was designed. Droplet production rates were controlled by adjusting the applied pressure of each inlet; and thus, altering the droplet sequence for capturing linear DIB networks in a downstream hydrodynamic trapping array. This microfluidic system provides a high-throughput …

Root Phosphomonoesterase As A Vital Component Of Increasing Phosphorus Availability In Tropical Forests, Kristine Grace Manno Cabugao

Doctoral Dissertations

Tropical forests, relative to other terrestrial ecosystems, exchange the largest amount of carbon with the atmosphere and also constitute a significant carbon sink. However, nutrient limitation, particularly of phosphorus (P), could limit growth of tropical forests and their function with the global carbon cycle. Thus, understanding root mechanisms to acquire P is necessary to representing the P cycle and corresponding interactions with plant growth. A large portion of total soil P in tropical forests occurs in organic forms, only accessible through root and microbial production of phosphatase enzymes. These phosphatase enzymes mineralize organic P into orthophosphate, the form of P …

Local Structure And Dynamic Studies Of Mixed Ch4-Co2 Gas Hydrates Via Computational Simulation And Neutron Scattering, Bernadette Rita Cladek

Doctoral Dissertations

Permeated throughout the ocean floor and arctic permafrost, natural gas hydrates contain an estimated 3000 trillion cubic meters, over three times that of traditional shale deposits, of CH₄ that is accessible for extraction. Gas hydrates are a crystal structure in which water molecules form a cage network, the host, through hydrogen bonds while trapping a guest molecule such as CH₄ in the cavities. These compounds form naturally where the appropriate low temperature and high pressure conditions occur. A promising and tested method of methane recovery is through exchange with CO₂, which energetically takes place of the …