Physical Sciences and Mathematics Commons^™

Lost Names In The Paleozoic Lithostratigraphy Of Arkansas, Noah Morris

Graduate Theses and Dissertations

The geology of Arkansas has been studied for nearly 160 years, and our understanding of it is continually evolving. Part of this ever-changing study is the nomenclature of the stratigraphy. From the early reports to today, several lithostratigraphic names have been proposed and abandoned to improve the accuracy and clarity of the understanding of Arkansas’ geology. Over these 160 years of study, 214 names have been proposed for the Paleozoic beds of Arkansas, with nearly 80 of them currently in use today. These names are a testimony and legacy of the history of Arkansas’ natural resource development and Arkansas’ geologists. …

The “Apparent” Diffusion Coefficient Of Electrons Through A Nafion Membrane, Marissa Kayle Reynolds

Graduate Theses and Dissertations

The hydrogen/oxygen fuel cell is a greener, more efficient energy solution. However, there are many problems with the fuel cell including storage, infrastructure, cost, the oxygen reduction reaction, and the durability of the proton exchange membrane (PEM). The PEM is not only used as the electrolyte for the cell but also as a physical barrier between the anode and the cathode. The integrity of this membrane is crucial to the functioning of the fuel cell. This thesis will examine using ferricyanide as a probe molecule for diagnostic experiment of Nafion membrane integrity. Using hydrodynamic voltammetry with a rotating disk electrode …

An Electrochemical Characterization Of A Vanadium-Based Deoxydehydration Catalyst, Joel Eric Baker

Graduate Theses and Dissertations

Alternative methods for the conversion of polyols into olefins, be it for carbon storage or hydrocarbon fuel production, have become prevalent in today’s chemical industry. One process in particular, deoxydehydration (DODH) has been proven effective in taking sustainable biomass derivatives and converting them through the utilization of various homogenous metal catalysts. While this process may show productive yields and material conversion, it is hindered by the need of a sacrificial reductant. This makes a novel process economically unviable and relatively unused outside of scientific research. That fact begs the question: Can the process be improved? It is proposed here that …

Molecular Dynamics Simulations Of Dna-Functionalized Nanoparticle Building Blocks On Gpus, Tyler Landon Fochtman

Graduate Theses and Dissertations

This thesis discusses massively parallel molecular dynamics simulations of nBLOCKs using graphical processing units. nBLOCKs are nanoscale building blocks composed of gold nanoparticles functionalized with single-stranded DNA molecules. To explore greater simulation time scales we implement our nBLOCK computational model as an extension to the coarse grain molecular simulator oxDNA. oxDNA is parameterized to match the thermodynamics of DNA strand hybridization as well as the mechanics of single stranded DNA and double stranded DNA. In addition to an in-depth review of our implementation details we also provide results of the model validation and performance tests. These validation and performance tests …

Characterization Of Coupled Gold Nanoparticles In A Sparsely Populated Square Lattice, Roy Truett French Iii

Graduate Theses and Dissertations

Metal nanoparticles deposited in regular arrays spaced at optical wavelengths support a resonance due to a coherent coupling between localized surface plasmon mode and lattice diffraction allowing for engineering of tunable devices for use in biological sensors, nanoantennae, and enhanced spectroscopy. Techniques such as electron beam lithography, focused ion beam lithography, nanosphere lithography, and nanoimprint lithography are used for fabrication but are limited by cost, device throughput, and small deposition. Polymer soft lithography and continuous dewetting of particles is a potentially viable alternative showing promise in all of those areas. This thesis developed the fabrication of a refined hydrophilic nanoimprinted …

A Hybrid Partially Reconfigurable Overlay Supporting Just-In-Time Assembly Of Custom Accelerators On Fpgas, Zeyad Tariq Aklah

Graduate Theses and Dissertations

The state of the art in design and development flows for FPGAs are not sufficiently mature to allow programmers to implement their applications through traditional software development flows. The stipulation of synthesis as well as the requirement of background knowledge on the FPGAs' low-level physical hardware structure are major challenges that prevent programmers from using FPGAs. The reconfigurable computing community is seeking solutions to raise the level of design abstraction at which programmers must operate, and move the synthesis process out of the programmers' path through the use of overlays. A recent approach, Just-In-Time Assembly (JITA), was proposed that enables …

Dpweka: Achieving Differential Privacy In Weka, Srinidhi Katla

Graduate Theses and Dissertations

Organizations belonging to the government, commercial, and non-profit industries collect and store large amounts of sensitive data, which include medical, financial, and personal information. They use data mining methods to formulate business strategies that yield high long-term and short-term financial benefits. While analyzing such data, the private information of the individuals present in the data must be protected for moral and legal reasons. Current practices such as redacting sensitive attributes, releasing only the aggregate values, and query auditing do not provide sufficient protection against an adversary armed with auxiliary information. In the presence of additional background information, the privacy protection …

Understanding N-Nitrosodimethylamine Formation In Water: Chloramine Chemistry, Kinetics, And A Proposed Reaction Pathway, Huong Thu Pham

Graduate Theses and Dissertations

The formation of N-nitrosodimethylamine (NDMA) in drinking water systems is a concern because of its potential carcinogenicity and occurrence at toxicologically relevant levels. The postulated mechanism for NDMA formation involves a substitution between dichloramine and amine-based precursors to form an unsymmetrical dimethylhydrazine (UDMH), which is then oxidized by ground-state molecular oxygen to form NDMA. However, this latter reaction is spin forbidden, thus likely occurs at a slow rate. It is hypothesized that the reaction between monochloramine and hydroxylamine (a nitrification product) may form an intermediate, which is involved in the NDMA formation pathway. This intermediate may also be generated from …

Morphology Controlled Synthesis Of Copper Based Multimetallic Nanostructures And Their Electrocatalytic Properties For Methanol Oxidation Reaction, Leanne Elizabeth Mathurin

Graduate Theses and Dissertations

This research focuses on the development of shape-controlled synthesis of Cu NM, Cu-based bimetallic and trimetallic nanostructures, and their electrocatalytic properties for methanol oxidation reaction (MOR). Copper nanomaterials (Cu NM) with specific surface facets can tailor their catalytic activity. Understanding reagents responsible for Cu NM growth is important for morphology-controlled synthesis of the nanostructures. This research studies the halide influence on Cu NM growth and morphology in an oil-based synthesis. The morphology of the Cu NM varies with the halide type (i.e., Cl-, Br-, I-), and the halide concentration. Additionally, the type of Cu precursor also influenced the morphology of …

Electrochemical Time Of Flight For Rapid And Direct Measurement Of Diffusion Coefficients, Jonathan C. Moldenhauer

Graduate Theses and Dissertations

The determination of diffusion coefficients is of fundamental importance to the understanding of electrochemistry and sensors. Developing a method by which diffusion coefficients of Red/ox active analytes can be determined quickly and elegantly, would be a great advancement over presently accepted methods. This dissertation reports the reviving electrochemical time of flight (ETOF), and developing a method that allows for empirical determination of diffusion coefficients from a single measurement. ETOF is a generate and detect experiment where the time an electrochemically generated species takes to transit a known distance is measured and related to the diffusion coefficient of the species. The …

A Bayesian Variable Selection Method With Applications To Spatial Data, Xiahan Tang

Graduate Theses and Dissertations

This thesis first describes the general idea behind Bayes Inference, various sampling methods based on Bayes theorem and many examples. Then a Bayes approach to model selection, called Stochastic Search Variable Selection (SSVS) is discussed. It was originally proposed by George and McCulloch (1993). In a normal regression model where the number of covariates is large, only a small subset tend to be significant most of the times. This Bayes procedure specifies a mixture prior for each of the unknown regression coefficient, the mixture prior was originally proposed by Geweke (1996). This mixture prior will be updated as data becomes …

Exploring Thermoresponsive Affinity Agents To Enhance Microdialysis Sampling Efficiency Of Proteins, Thaddeus Vasicek

Graduate Theses and Dissertations

Affinity agents increase microdialysis protein relative recovery, yet they have not seen widespread use within the microdialysis community due to their additional instrumentation requirements and prohibitive cost. This dissertation describes new affinity agents for microdialysis that require no additional instrumentation to use, have nearly 100% particle recovery, are 7 times more cost efficient than alternatives, and have low specificity enabling their use for a wide variety of proteins. Initially gold nanoparticles were chosen as an affinity ligand support due to their high surface area/volume ratio and colloidal stability. Poly (N-isopropylacrylamide) was immobilized to the gold nanoparticles, which served to sterically …

Evaluation Of The Correlation Between The Oxidation Reduction Potential And Free Chlorine Residual For Different Chlorine Sources Used In Poultry Drinking Water Sanitation, Samantha Renee Cox

Graduate Theses and Dissertations

A critical component in commercial poultry production is to ensure birds are provided clean, quality water. Multiple disinfectants can be utilized to optimize a good water quality program. The goal of these water disinfectants is to greatly reduce or eliminate the presence of all bacteria. In recent years, the oxidation-reduction potential (ORP) meter has been a tool utilized by the poultry industry to monitor chlorine efficacy in drinking water. An ORP reading of 650-750 millivolts (mV) has become the industry standard for assuring an acceptable sanitizing residual of free chlorine is present for controlling microbial contamination regardless of the actual …

On Rings Of Invariants For Cyclic P-Groups, Daniel Juda

Graduate Theses and Dissertations

This thesis studies the ring of invariants R^G of a cyclic p-group G acting on k[x_1,\ldots, x_n] where k is a field of characteristic p >0. We consider when R^G is Cohen-Macaulay and give an explicit computation of the depth of R^G. Using representation theory and a result of Nakajima, we demonstrate that R^G is a unique factorization domain and consequently quasi-Gorenstein. We answer the question of when R^G is F-rational and when R^G is F-regular.

We also study the a-invariant for a graded ring S, that is, the maximal graded degree of the top local cohomology module of S. …

Ecological Importance Of Invader Source Population And Disturbance In Aquatic Invasions, Nicole Elizabeth Graham

Graduate Theses and Dissertations

Invasive species are a global problem and their effects on recipient ecosystems may be mediated by disturbance and intraspecific variation. Crayfish can substantially influence stream structure and function, and invasive crayfish often have differential impacts than native crayfish in aquatic ecosystems. Since species traits often vary across a distribution, it is possible that invasive crayfish from different source populations may have distinct impacts on recipient ecosystem structure and function. In the Ozark Highlands of Arkansas and Missouri, USA, invasive O. neglectus (the Ringed Crayfish) may be leading to the displacement of native O. eupunctus (the Coldwater Crayfish). The objective of …

Controlled Synthesis And Utilization Of Metal And Oxide Hybrid Nanoparticles, Cameron Cowgur Crane

Graduate Theses and Dissertations

This dissertation reports the development of synthetic methods concerning rationally-designed, hybrid, and multifunctional nanomaterials. These methods are based on a wet chemical, solution phase approach that utilizes the knowledge of synthetic organic and inorganic chemistry to generate building blocks in solution for the growth of nanocrystals and hybrid nanostructures. This work builds on the prior knowledge of shape-controlled synthesis of noble metal nanocrystals and expands into the challenging realm of the more reactive first row transition metals. Specifically, a microemulsion sol-gel method was developed to synthesize Au-SiO2 dimers as precursors for the synthesis of segmented heterostructures of noble metals that …

Using Cross-Sets For Paleodischarge Estimation And Paleocurrent Vectors In The Parthenon Sandstone, Northwest Arkansas, Sean Robert Parry

Graduate Theses and Dissertations

In this thesis, set thicknesses are used to estimate the paleohydraulics (paleodischarge and give magnitudes for paleocurrent directions) of the ancient river system which deposited the Parthenon Sandstone in northwest Arkansas. Set thickness is the vertical thickness of a group of strata conformable series (Mckee and Weir, 1953); set thickness represents truncated dunes. The goal of this thesis is to: 1) obtain paleodischarge estimates of the Parthenon sandstone via cross-sets and compare the results with previously calculated discharge estimates which use basin area to discharge collation techniques and 2) use paleodischarge estimates calculated within this thesis to give magnitude to …

Wayne E. Sabbe Arkansas Soil Fertility Studies 2016, Nathan A. Slaton

Arkansas Agricultural Experiment Station Research Series

Rapid technological changes in crop management and production require that the research efforts be presented in an expeditious manner. The contributions of soil fertility and fertilizers are major production factors in all Arkansas crops. The studies described within will allow producers to compare their practices with the university’s research efforts. Additionally, soil-test data and fertilizer sales are presented to allow comparisons among years, crops, and other areas within Arkansas.

How To Collect Your Water Sample & Interpret The Results For The Domestic Analytical Packages, Bradley J. Austin, Mike Daniels, Brian E. Haggard

Fact Sheets

Whether you rely on a municipal water source or a private well for your drinking water needs, having access to clean drinking water is important to everyone. The Arkansas Water Resources Center (AWRC) in cooperation with the UA Cooperative Extension Service, both of which are part of the U of A System’s Division of Agriculture, offers several analytical packages to assess the quality of your water resources. This document is intended to provide guidance on collecting water samples for analysis and understanding the Domestic Water Report Form”provided by the AWRC’s Water Quality Laboratory (Lab). The AWRC Water Quality Lab is …

How To Collect Your Water Sample And Interpret The Results For The Irrigation Analytical Package, Bradley J. Austin, Leo Espinoza, Chris Henry, Mike Daniels, Brian E. Haggard

Fact Sheets

Irrigation represents a significant portion of the total production cost for crops. Because of this it is important to have your water tested to ensure that it is suitable for the crops you are growing, and to aid in developing management plans that might help alleviate existing issues such as high salt levels or high alkalinity. The Arkansas Water Resources Center (AWRC) in cooperation with the UA Cooperative Extension Service offers several analytical packages to assess the quality of your water resources. This document is intended to provide guidance to farmers on collecting water samples for analysis and understanding the …

Arkansas Bulletin Of Water Research - Inaugural Issue 2017, Erin E. Scott, Brian E. Haggard

Arkansas Bulletin of Water Research

The Arkansas Bulletin of Water Research is a publication of the Arkansas Water Resources Center (AWRC). This bulletin is produced in an effort to share water research relevant to Arkansas water stakeholders in an easily searchable and aesthetically engaging way. This is the inaugural publication of the bulletin and will be published annually. The submission of a paper to this bulletin is appropriate for topics at all related to water resources, by anyone conducting water research or investigations. This includes but is not limited to university reserachers, consulting firms, watershed groups, and other agencies. Prospective authors should read the “Introduction …

How To Collect Your Water Sample And Interpret The Results For The Poultry Analytical Package, Bradley J. Austin, Josh B. Payne, Susan E. Watkins, Mike Daniels, Brian E. Haggard

Fact Sheets

Rapidly growing birds may consume up to twice as much water as feed (Scantling and Watkins 2013), which means a plentiful supply of clean water is crucial for poultry health and productivity. To determine the quality of your poultry’s water resources, periodic sampling and analysis is needed. Analyzing water supplies can also be a crucial tool in identifying existing or potential challenges. The Arkansas Water Resources Center (AWRC) in cooperation with the UA Cooperative Extension Service offers several analytical packages to assess the quality of your water resources. This document is intended to provide guidance to poultry producers on collecting …

Eco-Cosplay: Upcycling As A Sustainable Method Of Costume Construction, Sarah West, Kathleen Smith

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

This research addresses sustainability in the apparel industry from the specific perspective of repurposing materials for use in costume development. Repurposing discarded materials, also referred to as upcycling, is examined as a viable approach to waste management and evaluated for its impact on sustainability in apparel and textile production, especially in relation to costume development. Current issues in sustainability in the apparel industry that are a focus for this research include waste from production as well as post-consumer waste. The project includes the design and construction of two costume pieces based on a style of costume known as cosplay. Cosplay …

Final Report To Governors From The Joint Study Committee And Scientific Professionals, Brian Haggard, Derek Smithee, Ryan Benefield, Shellie Chard, Marty Matlock, Shanon Phillips, Ryan King

Technical Reports

The intent of this publication of the Arkansas Water Resources Center is to provide a location whereby a final report on water research to a funding entity can be archived. The States of Arkansas and Oklahoma signed the Second Statement of Joint Principles and Actions in 2013 to form a governors’ appointed ‘Joint Study Committee’ to oversee the ‘Joint Study’ and make recommendations on the phosphorus criteria in Oklahoma’s Scenic Rivers. This publication has maintained the original format of the report as submitted to the Governors of Arkansas and Oklahoma.

Journal Of The Arkansas Academy Of Science- Volume 71 2017, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

Hydrothermally Emplaced, Lower Mississippian, Tripolitic Chert And Its Possible Relationship To The Tri-State Lead-Zinc Mining District, J. Chick, J. Cains, F. Mcfarlin, S. Mckim, A. Potra

Journal of the Arkansas Academy of Science

Across the southern Ozark Region, northern Arkansas, southwestern Missouri, and northeastern Oklahoma, exposures of the Lower Mississippian Boone Formation and its equivalents exhibit well-developed tripolitic chert that has been mined, more or less continuously, for at least 80 years. The tripolitic chert is a replacement of an interval within the basal portion of the upper Boone Formation in Arkansas and Oklahoma, and equivalent to the Elsey Formation in Missouri. The movement of silica-rich, hydrothermal fluids appears to have been much like that of a confined aquifer. It followed the basal upper Boone Formation (Arkansas) = Elsey Formation (Missouri) and was …

Bond Length And Bond Valence For Tungsten-Oxygen And Tungsten-Sulfur Bonds, F. D. Hardcastle, R. Lykins

Journal of the Arkansas Academy of Science

In 1947, Linus Pauling presented an “empirical” dependence of bond valence (s, also referred to as bond order) and bond length R: s = exp[(R₀-R)/b], where R₀ is bond length of unit valence and “b” is a fitting parameter. Recently, an expression was derived for relating the b fitting parameter to theoretically derived atomic orbital exponents. With a method to calculate b, both R₀ and atomic orbital exponents can be experimentally determined through optimized fitting for W-O and W-S bonds. In the present study, bond …

Wave Profile For Breakdown Waves With A Large Current Behind The Wave Front, M. Hemmati, J. Griffiths, M. Bowman

Journal of the Arkansas Academy of Science

For analytical solution of breakdown waves with a large current behind the wave front, we employ a one-dimensional, steady-state, three-component (electrons, ions, and neutral particles) fluid model. This project involves breakdown waves propagating in the opposite direction of the electric field force on electrons, anti-force waves (return stroke in lightning); and the electron gas partial pressure is considered to provide the driving force for the propagation of the wave. The basic set of equations consists of the equation of conservation of mass flux, equation of conservation of momentum, equation of conservation of energy, plus Poisson’s equation. The waves are considered …

Lithologic Stratigraphic Position, Sequence And Diagenetic History, Lower Mississippian Tripolitic Chert, Northern Arkansas And Southern Missouri, S. Mckim, J. Cains, J. Chick, F. Mcfarlin, A. Potra

Journal of the Arkansas Academy of Science

Tripolitic chert development in the southern Ozark region is associated with a third-order, transgressive-regressive cycle comprising St. Joe transgressive packstones, succeeded by lower Boone calcisiltites, with black, penecontemporaneous, nodular chert deposited during maximum flooding, overlain by basal upper Boone calcisiltites deposited during highstand. The onset of regression produced upper Boone packstones and grainstones with white-gray, later diagenetic chert reflecting groundwater replacement along bedding planes. Tripolitic chert is a product of the highstand calcisiltites at the base of the upper Boone Formation of Arkansas, and its equivalent, the Elsey Formation of southern Missouri. This tripolitic chert appears to reflect a hydrothermal …

Sequence Stratigraphic And Tectono-Stratigraphic Successions, Ozark Shelf, Tri-State Region, Southern Midcontinent, E. C. Bello

Journal of the Arkansas Academy of Science

The southern Ozark region, Arkansas, Missouri, and Oklahoma occupies the southern border of the North American craton. Its sedimentary succession preserves a complete Wilson Cycle reflecting the Late Precambrian-Cambrian rifting of Rodinia into the Laurussian and Gondwanan landmasses that opened the Iapetus Ocean Basin during the Late Cambrian-Middle Mississippian. The basin was closed during the Late Mississippian-Middle Pennsylvanian by the collision of Laurussia with Gondwana. During the Late Cambrian through the Middle Pennsylvanian, the Ozark Shelf, including its gently sloping, Northern Arkansas Structural Platform (NASP) and adjacent ramp, records both transgression and regression by epeiric seas as well as regional …