Physical Sciences and Mathematics Commons^™

Extraction And Purification Of Biologically Active Metabolites From Rhodococcus Sp. Mtm3w5.2, Mohrah Alenazi

Electronic Theses and Dissertations

Rhodococcushas been recognized as a potential antibiotic producer. Recently, a strain of Rhodococcussp. MTM3W5.2 was isolated from a soil sample collected in Morristown, Tennessee and was found to produce an inhibitory compound which is active against other related species. The purpose of this research is to extract, purify and analyze the active metabolite. The compound was extracted from RM broth cultures and purified by preliminary fractionation of crude extract through a Sephadex LH-20 column. Further purification was completed using semi-preparative reversed phase column chromatography. Final purification was obtained using multiple rounds of an analytical C18 HPLC column. Based …

Relative Permittivity As A Function Of Co-Solvent And Impedance Spectroscopy For Quantifying Anions In Solution, Yahya Sami Alseiha

Electronic Theses and Dissertations

This work measured relative permittivity from 15.0 to 55.0 °C of aqueous solutions containing acetone or tetrahydrofuran using a BI 870 dielectric meter. A cubic polynomial fit resulted in coefficients for calculating permittivity as a function of temperature and mole fraction. Literature values for other co-solvent system resulted in similar polynomial coefficients. Using BI 870, permittivity measurements of ionic solutions were not possible because of high conductivity. A simple method using impedance spectroscopy measured these solutions. Impedance decreases with increasing temperature and decreases with increasing ionic strength. Due to the temperature dependence of impedance, all measurements were at 25.0 °C. …

Dreadd Targeting Projections From The Nucleus Accumbens To The Ventral Pallidum With Nicotine Self-Administration, Amanda Smith

Electronic Theses and Dissertations

Projections from the Nucleus Accumbens (NAc) to the Ventral Pallidum (VP) play a critical role in motivation and reward. Rewards and reward-associated cues are thought to alter this pathway by suppressing GABA release to the VP, however, the role of the NAc to VP pathway has never been investigated with regard to nicotine self-administration. We hypothesized that increasing GABAergic signaling from the NAc to the VP would decrease the reinforcing effects of nicotine. To increase GABA release, CRE dependent DREADD was expressed in the NAc of male rats. Administration of low dose clozapine activated the DREADD receptor and showed a …

Groundwater Hydrogeolgy And Hydrochemistry Of Karst Springs In The Eastern Peninsula Of Fort Hood Military Installation, William Scribner Welles

Electronic Theses and Dissertations

The eastern peninsula of Fort Hood Military Installation is underlain by a complex karst spring network. These springs are a primary water source in a protected habitat for endangered songbirds, which has only recently begun to be fully investigated. These Fredericksburg Group springs express both epigenetic and hypogenetic karst signatures. The study area is part of a paleo reef trend, a hydraulically disconnected segment of the northern section of the Edwards Aquifer. This study utilized standard ion index values, repeated measures, and principal component analyses on the chemical profiles of six perennial springs to classify spring water sources and their …

An Outcrop Based Study Of The Weches Formation In Sabine County, Texas: Investigating Its Unconventional Resource Potential Through The Study Of Stratigraphy, Sedimentology, Petrology, And Geochemistry, Talban Kantala

Electronic Theses and Dissertations

Fresh Weches Formation (Middle Eocene) exposures found in aggregate quarries in Sabine County, Texas, were sampled, measured, and logged with gamma-ray spectrometry (GRS). Sedimentology and petrology characteristics of Weches samples were analyzed through thin section, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and GRS Th/K ratios analyses. The source rock quality of the Weches was evaluated with geochemical techniques involving total organic carbon (TOC), Rock-Eval pyrolysis, and GRS Th/U ratios.

The Weches, in the study area, is 27.4 meters thick, and delineated into three major stratigraphic facies: an upper marginal marine prodeltaic facies (Therrill Member) comprised of silty claystones and …

Depositional Environment And Facies Analyses Of The Owl Mountain Province, Fort Hood Military Installation, Bell And Coryell Counties, Texas, Jacob Meinerts

Electronic Theses and Dissertations

The Owl Mountain Province is a plateaued, karst landscape located in the eastern section of the Fort Hood Military Installation and is characterized by Lower Cretaceous Fredericksburg Group carbonates. The topography is capped by thick sequences of the Edwards limestone; steep scarps and incised valleys along the edges of the plateaus host inter-fingering outcrops of the Edwards and Comanche Peak limestones, and the lower valleys are covered by alluvial sediments and intermittent outcrops of the Walnut Clay. These formations were deposited to the north and west of the main Edwards trend, and are thought to be part of a series …

Topological Properties Of A 3-Rung Möbius Ladder, Rebecca Woods

Electronic Theses and Dissertations

In this work, we discuss the properties of the 3-rung Möbius ladder on the torus. We also prove ℤ₂ is an orientation preserving topological symmetry group of the 3-rung Möbius ladder with sides and rungs distinct, embedded in the torus.

Computational Prediction, Characterization, And Methodology Development For Two-Dimensional Nanostructures: Phosphorene And Phosphide Binary Compounds., Congyan Zhang

Electronic Theses and Dissertations

In this thesis, a comprehensive computational simulation was carried out for predicting, characterizing, and applications of two-dimensional (2D) materials. The newly discovered GaP and InP layers were selected as an example to demonstrate how to explore new 2D materials using computational simulations. The performance of phosphorene as the anode material of Lithium-ion battery was discussed as the example of the application of 2D material. Furthermore, the semi-empirical Hamiltonian for phosphorous and lithium elements have been developed for our future work on the application of phosphorus and lithium-based systems. The novel 2D materials of GaP and InP binary compounds were found …

The Regional Distribution And Molecular Interactions Of Phospholipids And Glucose In Mammalian Vitreous Humors., Abigail Nicole Schnepf

Electronic Theses and Dissertations

The vitreous humor (VH) is located in between the lens and the retina. It is composed of 98% water, hyaluronan (HA), collagen, proteins, phospholipids (PLs), and other metabolites. With aging, the VH undergoes liquefaction, a process that causes the gel-like structure of the VH to turn into a liquid and can lead to serious ocular diseases, including retinal detachment, vitreal detachment, and macular hole formation. The liquefaction process is expedited in diabetic VHs. This project focuses on understanding the molecular changes that lead to liquefaction and the reasons for which this process is accelerated with diabetes. Matrix-assisted laser desorption ionization/mass …

Electrochemical And Morphological Properties Of Chloride-Doped Lithium Argyrodite Solid Electrolytes., William Richard Arnold

Electronic Theses and Dissertations

Recently, much attention has been devoted to the development of solid electrolytes to be used in all-solid-state-batteries. One group of promising solid electrolyte (SE) materials are lithium argyrodites, a class of superconductors which are noted for their high ionic conductivities. In particular, halogen doping has been shown to increase both conductivity and stability. The majority of research has focused on material synthesis through solid state reactions, but a novel liquid synthesis method for the preparation of Cl-doped Li7PS6 solid electrolyte provides the advantages of a homogenous product and a rapid, economic synthesis. Here this thesis focuses on the liquid synthesis …

Performance Assessment Of The Extended Gower Coefficient On Mixed Data With Varying Types Of Functional Data., Obed Koomson

Electronic Theses and Dissertations

Clustering is a widely used technique in data mining applications to source, manage, analyze and extract vital information from large amounts of data. Most clustering procedures are limited in their performance when it comes to data with mixed attributes. In recent times, mixed data have evolved to include directional and functional data. In this study, we will give an introduction to clustering with an eye towards the application of the extended Gower coefficient by Hendrickson (2014). We will conduct a simulation study to assess the performance of this coefficient on mixed data whose functional component has strictly-decreasing signal curves and …

An Evaluation Of Geotagged Twitter Data During Hurricane Irma Using Sentiment Analysis And Topic Modeling For Disaster Resilience, Ike Robert Vayansky

Electronic Theses and Dissertations

Disasters require quick response times, thought-out preparations, overall community, and government support. These efforts will ensure prevention of loss of life and reduce possible damages. The United States has been battered by multiple major hurricanes in the recent years and multiple avenues of disaster response efforts were being tested. Hurricane Irma can be recognized as the most popular hurricane in terms of social media attention. Irma made landfall in Florida as a Category 4 storm and preparation measures taken were intensive thus providing a good measure to evaluate in terms of efficacy. The effectiveness of the response methods utilized are …

Late Holocene Spit Evolution On Centennial Timescales In The Southeast Delaware Bay, Usa, Ryan Eli Phillip

Electronic Theses and Dissertations

The relationship between barrier spit growth and longshore drift is well established. However, the role of storm activity in spit evolution on an intermediate (centennial) timescale is more of a mystery due to a knowledge gap between decadal-scale shoreline processes and millennial-scale stratigraphic data. Recent studies in the northwestern Atlantic basin using ground-penetrating radar (GPR) and optically-stimulated luminescence (OSL) are providing the opportunity to study centennial-scale shoreline evolution and examine similar age storm activity. Cape Henlopen, Delaware exhibits preserved remnants of a long-term northward-growing spit coastline that evolved from a recurved spit complex, to a cuspate spit, to the present-day …

Structure And Thermodynamics Of Polyglutamine Peptides And Amyloid Fibrils Via Metadynamics And Molecular Dynamics Simulations, Riley Workman

Electronic Theses and Dissertations

Aggregation of polyglutamine (polyQ)-rich polypeptides in neurons is a marker for nine neurodegenerative diseases. The molecular process responsible for the formation of polyQ fibrils is not well understood and represents a growing area of study. To enable development of treatments that could interfere with aggregation of polyQ peptides, it is crucial to understand the molecular mechanisms by which polyQ peptides aggregate into fibrils. Many experimental techniques have been employed to probe polyQ aggregation, however, observations from these studies have not lead to a unified understanding of the properties of these systems, instead yielding competing, fragmented theories of polyQ aggregation. This …

Economics Of Managing Loblolly Pine Plantations For Increased Wildlife Biodiversity, Melissa Griffith

Electronic Theses and Dissertations

The goal of this thesis was to identify the differences between the costs incurred and revenues gained from managing loblolly pine (Pinus taeda) plantations in East Texas for strictly timber production or a combination of timber production and wildlife biodiversity. Management regimes evaluated had varying planting densities, thinning frequency and intensities, prescribed burn intervals, and site indices. Economic analyses used to evaluate management regimes over a range of nonindustrial private landowner (NIPF) alternative rates of return (ARRs) and site indexes were net present worth, land expectation value, and equal annual annuity. These economic analyses demonstrated that altering management …

T-De Vries Algebra, Nawal Alznad

Electronic Theses and Dissertations

The main point of this dissertation is to introduce the action on de Vries algebra by a topological monoid and we denoted the resulting category by dVT. In order to reach our goal, we started with introducing new proofs for some well known results in the category of flows. Then, we studied the Generalized Smirnov's Theorem for flows. After we studied the new category (dVT), we were able to provide a new way to construct the Čech-stone flow compactification of a given flow. Finally, we developed the co-free T-de Vries algebra for a special case.

Improving The Accuracy Of Mobile Touchscreen Qwerty Keyboards, Amanda Kirk

Electronic Theses and Dissertations

In this thesis we explore alternative keyboard layouts in hopes of finding one that increases the accuracy of text input on mobile touchscreen devices. In particular, we investigate if a single swap of 2 keys can significantly improve accuracy on mobile touchscreen QWERTY keyboards. We do so by carefully considering the placement of keys, exploiting a specific vulnerability that occurs within a keyboard layout, namely, that the placement of particular keys next to others may be increasing errors when typing. We simulate the act of typing on a mobile touchscreen QWERTY keyboard, beginning with modeling the typographical errors that can …

Fuel Specific Emissions Trends For In-Use Medium And Heavy-Duty Vehicle Fleets In California, Molly J. Haugen

Electronic Theses and Dissertations

New heavy-duty vehicle regulations have caused significant reductions in hazardous air pollutants, such as particulate matter (PM) and nitrogen oxides (NO_x), due to better engine management and utilization of advanced after-treatment systems. The University of Denver has collected data for gaseous and PM emission measurements from on-road heavy-duty vehicles (HDVs). The On-Road Heavy-Duty Vehicle Emissions Measurement System (OHMS) collected fuel specific emission information on individual HDVs of in-use fleets at two California locations in the spring of 2013, 2015 and 2017. These complimentary fleets, studied over multiple years, produced 7,075 measurements of gaseous and particle emission data providing …

Surface Entropy Of Shifts Of Finite Type, Dennis Pace

Electronic Theses and Dissertations

Let χ be the class of 1-D and 2-D subshifts. This thesis defines a new function, H_S : χ x R → [0,∞] which we call the surface entropy of a shift. This definition is inspired by the topological entropy of a subshift and we compare and contrast several structural properties of surface entropy to entropy. We demonstrate that much like entropy, the finiteness of surface entropy is a conjugacy invariant and is a tool in the classification of subshifts. We develop a tiling algorithm related to continued fractions which allows us to prove a continuity result about surface …

Developing A Femtosecond Stimulated Raman Spectroscopy Experiment For Solid State Materials, Daniel Hammerland

Electronic Theses and Dissertations

Femtosecond Stimulated Raman Spectroscopy (FSRS) is a ultrafast spectroscopy technique first implemented by chemists to understand isomerization and other ultrafast molecular morphology changes by resolving vibrational dynamics[1, 2, 3]. FSRS has an unparalleled temporal and spectral resolution [4, 1, 5, 6] that arises as a result of a clever combination of picosecond and femtosecond pulses. However, despite this capability, FSRS has yet to be applied to modern materials in condensed matter physics. This thesis explores the design and implementation of FSRS to study two-dimensional materials in order to measure their quantum confined vibrational dynamics on utlrafast time scales.

A Bi-Encoder Lstm Model For Learning Unstructured Dialogs, Diwanshu Shekhar

Electronic Theses and Dissertations

Creating a data-driven model that is trained on a large dataset of unstructured dialogs is a crucial step in developing a Retrieval-based Chatbot systems. This thesis presents a Long Short Term Memory (LSTM) based Recurrent Neural Network architecture that learns unstructured multi-turn dialogs and provides implementation results on the task of selecting the best response from a collection of given responses. Ubuntu Dialog Corpus Version 2 (UDCv2) was used as the corpus for training. Ryan et al. (2015) explored learning models such as TF-IDF (Term Frequency-Inverse Document Frequency), Recurrent Neural Network (RNN) and a Dual Encoder (DE) based on Long …

Polarized Bow Shock Nebulae Reveal Features Of The Winds And Environments Of Massive Stars, Manisha Shrestha

Electronic Theses and Dissertations

Massive stars strongly affect their surroundings through their energetic stellar winds during their lifetime and through their energetic deaths as supernovae. When a stellar wind interacts with the local interstellar medium (ISM), if the relative velocity between wind and ISM is supersonic, then a stellar wind bow shock is formed. Bow shocks and related density enhancements produced by the winds of massive stars moving through the interstellar medium provide important information regarding the motions of the stars, the properties of their stellar winds, and the characteristics of the local medium. Since bow shock nebulae are aspherical structures, light scattering within …

Factorization In Integral Domains., Ryan H. Gipson

Electronic Theses and Dissertations

We investigate the atomicity and the AP property of the semigroup rings F[X; M], where F is a field, X is a variable and M is a submonoid of the additive monoid of nonnegative rational numbers. In this endeavor, we introduce the following notions: essential generators of M and elements of height (0, 0, 0, . . .) within a cancellative torsion-free monoid Γ. By considering the latter, we are able to determine the irreducibility of certain binomials of the form Xπ − 1, where π is of height (0, 0, 0, . . .), in the monoid domain. Finally, …

D-Fens: Dns Filtering & Extraction Network System For Malicious Domain Names, Jeffrey Spaulding

Electronic Theses and Dissertations

While the DNS (Domain Name System) has become a cornerstone for the operation of the Internet, it has also fostered creative cases of maliciousness, including phishing, typosquatting, and botnet communication among others. To address this problem, this dissertation focuses on identifying and mitigating such malicious domain names through prior knowledge and machine learning. In the first part of this dissertation, we explore a method of registering domain names with deliberate typographical mistakes (i.e., typosquatting) to masquerade as popular and well-established domain names. To understand the effectiveness of typosquatting, we conducted a user study which helped shed light on which techniques …

Hydrolysis Of Cellulose And Biomass Using Blue Molybdenum, Farouk Awudu

Electronic Theses and Dissertations

Hydrolysis of cellulosic biomass is an important and ongoing subject of research due to generating precursors for biofuel synthesis. This work involves hydrolysis of microcrystalline cellulose and Arundo donax to glucose. Methods for acid hydrolysis include the use of sulfuric acid, phosphomolybdic acid, blue molybdenum using low concentrations at 40-100 °C. For comparison purposes, enzymatic hydrolysis was also carried out using cellulase. Products were quantified by measuring total organic carbon and reducible sugars using dinitrosalicylic acid. Use of phosphomolybdic acid, blue molybdenum and sulfuric acid even at 6.0 M did not increase the amount of glucose compared to using water …

Comparing Laser Assisted Pulling And Chemical Vapor Deposition Methods In The Fabrication Of Carbon Ultramicro- And Nanoelectrodes, Theophilus Neequaye

Electronic Theses and Dissertations

Ultramicroelectrodes (UMEs) (limiting dimensions <~25 μm) and nanoelectrodes (<~100 nm) exhibit enhanced electrochemical properties compared to macroscopic electrodes. Their small sizes and enhanced properties make them well-suited for various interesting and important applications such as measuring redox-active species in nonaqueous solvents, studying intermediates of fast electrochemical reactions, and investigating electrochemical and electrocatalytic properties of single nanoparticles. While UMEs are commercially available, nanoelectrode fabrication is still largely confined to research labs. Various methods for constructing nanoelectrodes have been reported and continue to be developed, but most require considerable expertise, and comparisons between different fabrication processes are lacking. In this work, a comparison of laser-assisted pulling and chemical vapor deposition (CVD) methods of electrode fabrication is made with the aim of optimizing production of carbon nanoelectrodes for single nanoparticle electrochemical measurements. By examining effects of pulling parameters, post-pulling treatments, and CVD processing, electrodes as small as ~50 nm were successfully produced.

Developing Optimization Techniques For Logistical Tendering Using Reverse Combinatorial Auctions, Jennifer Kiser

Electronic Theses and Dissertations

In business-to-business logistical sourcing events, companies regularly use a bidding process known as tendering in the procurement of transportation services from third-party providers. Usually in the form of an auction involving a single buyer and one or more sellers, the buyer must make decisions regarding with which suppliers to partner and how to distribute the transportation lanes and volume among its suppliers; this is equivalent to solving the optimization problem commonly referred to as the Winner Determination Problem. In order to take into account the complexities inherent to the procurement problem, such as considering a supplier’s network, economies of scope, …

The Expected Number Of Patterns In A Random Generated Permutation On [N] = {1,2,...,N}, Evelyn Fokuoh

Electronic Theses and Dissertations

Previous work by Flaxman (2004) and Biers-Ariel et al. (2018) focused on the number of distinct words embedded in a string of words of length n. In this thesis, we will extend this work to permutations, focusing on the maximum number of distinct permutations contained in a permutation on [n] = {1,2,...,n} and on the expected number of distinct permutations contained in a random permutation on [n]. We further considered the problem where repetition of subsequences are as a result of the occurrence of (Type A and/or Type B) replications. Our method of enumerating the Type A replications causes double …

Clustering Mixed Data: An Extension Of The Gower Coefficient With Weighted L2 Distance, Augustine Oppong

Electronic Theses and Dissertations

Sorting out data into partitions is increasing becoming complex as the constituents of data is growing outward everyday. Mixed data comprises continuous, categorical, directional functional and other types of variables. Clustering mixed data is based on special dissimilarities of the variables. Some data types may influence the clustering solution. Assigning appropriate weight to the functional data may improve the performance of the clustering algorithm. In this paper we use the extension of the Gower coefficient with judciously chosen weight for the L2 to cluster mixed data.The benefits of weighting are demonstrated both in in applications to the Buoy data set …

Room Temperature Operation Of Quantum Cascade Lasers Monolithically Integrated Onto A Lattice-Mismatched Substrate, Rowel Go

Electronic Theses and Dissertations

Quantum Cascade Lasers (QCLs) are semiconductor devices that, currently, have been observed to emit radiation from ~ 2.6 μm to 250 μm (1 to 100 terahertz range of frequencies.) They have established themselves as the laser of choice for spectroscopic gas sensing in the mid-wavelength infrared (3-8 μm) and long-wavelength infrared (8-15 μm) region. In the 4-12 μm wavelength region, the highest performing QCL devices, in terms of wall-plug efficiency and continuous wave operation, are indium phosphide (InP) based. The ultimate goal is to incorporate this InP-based QCL technology to silicon (Si) substrate since most opto-electronics are Si-based. The main …