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Articles 1 - 30 of 63
Full-Text Articles in Physical Sciences and Mathematics
Quantifying The Effects Of Land Use Change On Stream Ecosystems For Use In Ecological Risk Assessment, Katherine Sciera
Quantifying The Effects Of Land Use Change On Stream Ecosystems For Use In Ecological Risk Assessment, Katherine Sciera
All Dissertations
Land disturbance often results in a cascade of physical and chemical stressors to aquatic ecosystems which can impact their biotic integrity. This study examined three developing watersheds near Greenville, SC to evaluate the quantitative relationships between the physical stressors associated with land use alterations and biotic integrity. More specifically, the objectives of this study were to 1) quantify the mechanisms of aquatic ecosystem degradation in streams impacted by watershed urbanization, 2) demonstrate the use of quantitative relationships among the physical, chemical, and biological stressors associated with land use change in an established ecological risk assessment framework, and 3) identify the …
Synthesis, Structure And Magnetic Properties Of Oxy-Anion Based Magnetic Solids Containing Transition Metal Oxide Nanostructures, Kulugammana Gedera Ranmohotti
Synthesis, Structure And Magnetic Properties Of Oxy-Anion Based Magnetic Solids Containing Transition Metal Oxide Nanostructures, Kulugammana Gedera Ranmohotti
All Dissertations
Inline with the focus of our research, my goal for this dissertation study is to further explore new classes of magnetic insulators exhibiting novel properties. The scope of this work is twofold: 1) the exploratory synthesis of polyanion-based mixed-framework compounds containing transition metal oxide magnetic nanostructures, and 2) the investigation of the structure/property correlation with respect to the spin couplings in confined lattices. These studies are of fundamental and technological importance regarding the long-term development of low-dimensional magnetic solids for device applications in especially information storage and quantum computing. Several interesting and significant transition metal based silicate, phosphate arsenate and …
The Thermoelectric Properties Investigation Of X0.05Mo3Sb7-YTeY (X=Mn, Fe, Ni, Co; Y=1.5, 1.6, 1.7), Tim Holgate
The Thermoelectric Properties Investigation Of X0.05Mo3Sb7-YTeY (X=Mn, Fe, Ni, Co; Y=1.5, 1.6, 1.7), Tim Holgate
All Theses
With ever increasing energy costs, dwindling resources, and terms with the prefix 'green' filling headlines, the need for environmentally friendly energy sources has never been greater. Since the mid-20th century researchers have been pursuing greater efficiency in thermoelectric materials. Thermoelectric materials achieve energy conversion via the Seebeck effect (heat to electric power) and the Peltier effect (electricity to cooling power). Presented herein are the measured electrical and thermal transport properties and phenomenal analysis of the Ir3Ge7-type system: X0.05Mo3Sb7-yTey (X=Mn, Fe, Ni, Co; y=1.5, 1.6, 1.7) where 'X' are interstitially …
Synthesis And Characterization Of Biodegradable Polyurethanes For Biomedical Application, Changhong Zhang
Synthesis And Characterization Of Biodegradable Polyurethanes For Biomedical Application, Changhong Zhang
All Dissertations
This dissertation constitutes the studies about the biomedical materials research of novel polyurethanes. These elastic and degradable polyurethanes exhibited the potential for drug delivery, scaffold fabrication by novel ink-jet printing technology or other biomedical applications. This dissertation includes two parts about two different types of polyurethanes.
In the first part of this dissertation, we studied a polyurethane that was synthesized from methylene di-p-phenyl-diisocyanate (MDI), polycaprolactone diol (PCL-diol) and N, N-bis (2-hydorxyethyl)-2-aminoethane-sulfonic acid (BES). MDI, PCL-diol and BES were polymerized into polyurethane and served as the hard segment, soft segment and chain extender respectively. The effects of the chain extender BES …
Fabrication And Optical Properties Of Noble Metal Nanostructures, Mark Kinnan
Fabrication And Optical Properties Of Noble Metal Nanostructures, Mark Kinnan
All Dissertations
Experimental and theoretical results are presented in Chapters 2, 3, and 4 on the effects of dielectric medium, particle size, and interparticle distance, respectively, on plasmon coupling in two-dimensional arrays of silver nanoparticles. The arrays were fabricated via the self-assembly of single crystal particles from c.a. 46 nm to 287 nm on PVP-modified glass substrates. Spin-coated poly(methylmethacrylate) layers were used to immobilize the particles and prevent their surface aggregation. Varying the thickness of the PMMA layer made it possible to change the average dielectric medium between the particles. UV-Visible spectra of different arrays were compared to the corresponding electron microscope …
Fluorescent Conjugated Polymer Dots For Single Molecule Imaging And Sensing Applications, Changfeng Wu
Fluorescent Conjugated Polymer Dots For Single Molecule Imaging And Sensing Applications, Changfeng Wu
All Dissertations
While single molecule imaging and sensing hold the promise of providing unprecedented detail about cellular processes, many advanced applications are limited by the lack of appropriate fluorescence probes. In many cases, currently available fluorescent labels are not sufficiently bright and photostable to overcome the background associated with various autofluorescence and scattering processes. This dissertation describes research efforts focused on the development of a novel class of fluorescent nanoparticles called conjugated polymers dots (CPdots) for single molecule fluorescence detection. The CPdots contain highly fluorescent π-conjugated polymers that have been refined over the last decades as the active material in polymer light-emitting …
Calculations Of Diffusion In Fcc Binary Alloys Using On-The-Fly Kinetic Monte Carlo, Erdi Bleda
Calculations Of Diffusion In Fcc Binary Alloys Using On-The-Fly Kinetic Monte Carlo, Erdi Bleda
All Dissertations
With the recent advancements in computer technologies and the improvements in simulation algorithms, along with the theories, has allowed scientists to carry out diffusion calculations more efficiently, especially for the cases where either the diffusion itself takes longer, or there is no available isotope to carry out the diffusion experiments such as tracer diffusion.
In this work, we present a systematic approach to diffusion in intermetallic alloys such as weakly clustered Cu — Ni and weakly ordered Au — Ag. We use Accelerated Molecular Dynamics (AMD) combined with the Embedded Atom Method (EAM) to find the necessary saddlepoint energies. With …
Synthesis, Characterization, And Application Of Ag Nanostructures, Stephen Hudson
Synthesis, Characterization, And Application Of Ag Nanostructures, Stephen Hudson
All Dissertations
Noble metal nanoparticles (NPs) have been used for many centuries; however their properties were not truly scrutinized until Michael Farady's investigations in the 1850's. Advances in the field of nanotechnology over the last three decades have enabled insights into the properties of materials as their dimensions are reduced to the nanoscale. The repercussions of these insights are seen in many modern applications.
In this dissertation, properties of novel nanostructures based on Ag NPs are presented and discussed. The exceptional optical properties of Ag NPs stem from the collective oscillations of the conduction electrons known as plasmon resonances. The excitation of …
Novel Lactide Derived Polymers; Synthesis, Properties And Applications, Dahlia Haynes
Novel Lactide Derived Polymers; Synthesis, Properties And Applications, Dahlia Haynes
All Dissertations
This dissertation primarily encompasses the synthesis, characterization, properties and discussion of applications for lactide derived polymers. The methodology focuses on altering polylactide's (PLA's) dynamic and physical properties increasing its broad market utility in both traditional and non-traditional applications. The fundamentals of this work include understanding and enhancing the polymer chemistry and materials related processes through the use of copolymerization, fluorination, composite chemistry and materials science.
The first chapter discusses the important of this research with emphasis on current world issues that focuses on the feasibility of renewable resources and sustainability implementation. Modification of renewable resource materials like lactic acid is …
Two Categories Of Refutation Decision Procedures For Classical And Intuitionistic Propositional Logic, Edward Doyle
Two Categories Of Refutation Decision Procedures For Classical And Intuitionistic Propositional Logic, Edward Doyle
All Dissertations
An automatic theorem prover is a computer program that proves theorems without the assistance of a human being. Theorem proving is an important basic tool in proving theorems in mathematics, establishing the correctness of computer programs, proving the correctness of communication protocols, and verifying integrated circuit designs.
This dissertation introduces two new categories of theorem provers, one for classical propositional logic and another for intuitionistic propositional logic. For each logic a container property and generalized algorithm are introduced.
Many methods have been developed over the years to prove theorems in propositional logic. This dissertation describes and presents example proofs for …
Hybrid Bond-Order Potential For Silicon, Suleiman Oloriegbe
Hybrid Bond-Order Potential For Silicon, Suleiman Oloriegbe
All Dissertations
ABSTRACT
A new hybrid bond-order potential for silicon is developed. The functional form of the potential is derived from hybrid of expressions from empirical bond-order formalism and first principles approximations. The total energy is expressed as the sum of attractive, repulsive and promotion energies. By introducing a screening function derived from approximations to first principles expressions, the potential is made long-ranged by allowing covalent interactions beyond the first nearest neighbor shell of atoms in agreement with quantum mechanical descriptions of the bonding in silicon. Environment-dependent promotion energy is introduced that accurately accounts for energetic interactions due to changes in hybridization …
Solarization Effects On Chemical Properties Of Soils Under Kudu (Pueraria Montana) Invasion, Nicole Gilbert
Solarization Effects On Chemical Properties Of Soils Under Kudu (Pueraria Montana) Invasion, Nicole Gilbert
All Theses
Solarization is an effective method for managing small areas with kudzu (Pueraria montana) invasions that may alter soil chemical properties. Conducted from 2005 to 2007 at the Clemson University Experimental Forest in Clemson, South Carolina on a Cecil clay loam (fine, kaolinitic, thermic Typic Kanhapludult), this study compares soil chemical properties under thermally-treated and non-treated plots at different depths invaded by Kudzu.
The experimental factors of treatment and depth were arranged in a factorial treatment design with 15 treatments arranged in a split plot design. The five thermal treatments were the whole plot factors which were arranged in a randomized …
Insights Into Biogeophysical Signatures Using Polarization Force Microscopy, Elizabeth Bartosik
Insights Into Biogeophysical Signatures Using Polarization Force Microscopy, Elizabeth Bartosik
All Theses
The success of bioremediation strategies is dependent upon effective monitoring of microorganisms in the subsurface. Induced polarization (IP) may represent a cost-effective, complementary technique to existing borehole-based microbe detection schemes. Recent studies show a significant, yet poorly understood IP effect associated with the presence of bacteria in aqueous and porous media. This effect is believed to be rooted in the physicochemical surface interactions between cells and minerals which we probe using polarization force microscopy. Polarization force experiments were conducted on a hydrated mica surface using the gram positive bacterium Bacillus subtilis and the gram negative bacterium Escherichia coli. On all …
Probing Grb Environments Through X-Ray Absorption, Hala Eid
Probing Grb Environments Through X-Ray Absorption, Hala Eid
All Theses
Although long-duration GRBs (LGRBs) are highly transient in nature, their early afterglow can in principle be detected to very high redshifts (Lamb & Reichart, 2000). This makes them potent probes of the chemical evolution and content of the high-redshift universe. In this work, we use photoelectric absorption observed in the XRT spectra of LGRBs to investigate the evolution of metallicities and hydrogen column densities of LGRB host galaxies. Using a high-quality sample of LGRBs indicates the presence of a weak anti-correlation between the abundances and redshift. We also find an evolution trend in intrinsic column density. To confirm these correlations, …
Characterization Of Campus Parking Lot Stormwater And Remediation Of Risks Using Constructed Wetland Treatment Systems, Andrew Mcqueen
Characterization Of Campus Parking Lot Stormwater And Remediation Of Risks Using Constructed Wetland Treatment Systems, Andrew Mcqueen
All Theses
Campus parking lot stormwater (CPLSW) runoff mobilizes a variety of constituents from vehicular and atmospheric deposition that may pose risks to receiving aquatic systems. The overall objective of this research was to provide an approach for risk characterization, toxicity identification, and remediation of constituents of concern in CPLSW. The specific objectives of this research were to: (1) Characterize campus parking lot stormwater (CPLSW) to discern the constituents of concern present in these waters; (2) Perform TIE manipulations to identify possible fractions of concern in CPLSW, and; (3) Evaluate the performance of a pilot-scale constructed wetland treatment system (CWTS) designed to …
Physics Of Type Ia Supernovae, Ginger Bryngelson
Physics Of Type Ia Supernovae, Ginger Bryngelson
All Theses
Type Ia supernovae (SNe Ia), the thermonuclear explosion of a white dwarf, were once considered standard candles. However, increased observations reveal inhomogeneities in chemical composition and luminosity behavior, roughly dividing SNe Ia into three luminosity classes; super-luminous, sub-luminous, and normally-luminous. After introducing the problem in the context of previous observations and modeling, this thesis explores the physical processes occurring in a SN Ia after explosion, and discusses observations of SN light curves.
A simple model of the expanding ejecta calculates the energy deposition from the decay of radioactive Ni56 as well as photon diffusion. It produces light curves that match …
Application Of Web Services To A Simulation Framework, Matthew Bennink
Application Of Web Services To A Simulation Framework, Matthew Bennink
All Theses
The Joint Semi-Automated Forces (JSAF) simulator is an excellent tool for military training and a great testbed for new SAF behaviors. However, it has the drawback that behaviors must be ported into its own Finite State Machine (FSM) language. Web Services is a growing technology that seamlessly connects service providers to service consumers. This work attempts to merge these two technologies by modeling SAF behaviors as web services. The JSAF simulator is then modeled as a web service consumer.
This approach allows new Semi-Automated Forces (SAF) behaviors to be developed independently of the simulator, which provides the developer with greater …
Transformation Of Sulfonamide Antibiotics On Soil Mineral Oxides, Baishu Guo
Transformation Of Sulfonamide Antibiotics On Soil Mineral Oxides, Baishu Guo
All Theses
Determining the occurrence and potential adverse effects of antibiotic pharmaceuticals released into the environment is a critical step towards responsible environmental stewardship. Under aqueous conditions typically found in soils and natural waters, the antibiotic agent sulfamethoxazole (SMX) was transformed in the presence of pyrolusite MnO2 via oxidative pathways. At least 50% loss of SMX was observed after 269 hr in acidic and basic solutions (pH 3-9). A maximum of 100% loss was recorded at pH 3 and 66% loss was recorded at circumneutral pH. Concomitantly, aqueous manganese concentrations increased to around 10 µM at pH 3 and 2 µM at …
The Origin Of The 511 Kev Positron Annihilation Emission Morphology, Bethany Johns
The Origin Of The 511 Kev Positron Annihilation Emission Morphology, Bethany Johns
All Theses
The 511 keV positron annhilation emission from the Galactic bulge has yet to solely be attributed to any astrophysical source of positrons. The 511 keV line, characteristic of electron-positron annihilation, was discovered in 1970 by Johnson and Haymes [1973] almost 40 years ago. Most recently the INTERnational Gamma-Ray Astrophysical Laboratory (INTEGRAL) [Knodlseder 1997] has measured the annihilation rates of both components of the Galaxy. The bulge and disk annihilation rates are (1.5 ± 0.1) x 10^43 e+ s^-1 and(0.3 ± 0.2) x 10^43 e+ s^-1, respectively. The ratio of the bulge rate to that of the disk ranges from 3-9. …
Fast Fourier Transform Algorithms With Applications, Todd Mateer
Fast Fourier Transform Algorithms With Applications, Todd Mateer
All Dissertations
This manuscript describes a number of algorithms that can be used to quickly evaluate a polynomial over a collection of points and interpolate these evaluations back into a polynomial. Engineers define the 'Fast Fourier Transform' as a method of solving the interpolation problem where the coefficient ring used to construct the polynomials has a special multiplicative structure. Mathematicians define the 'Fast Fourier Transform' as a method of solving the evaluation problem. One purpose of the document is to provide a mathematical treatment of the topic of the 'Fast Fourier Transform' that can also be understood by someone who has an …
Numerical Analysis Of A Fractional Step Theta-Method For Fluid Flow Problems, John Chrispell
Numerical Analysis Of A Fractional Step Theta-Method For Fluid Flow Problems, John Chrispell
All Dissertations
The accurate numerical approximation of viscoelastic fluid flow poses two difficulties: the large number of unknowns in the approximating algebraic system (corresponding to velocity, pressure, and stress), and the different mathematical types of the modeling equations. Specifically, the viscoelastic modeling equations have a hyperbolic constitutive equation coupled to a parabolic conservation of momentum equation. An appealing approximation approach is to use a fractional step $\theta$-method. The $\theta$-method is an operator splitting technique that may be used to decouple mathematical equations of different types as well as separate the updates of distinct modeling equation variables when modeling mixed systems of partial …
The Effects Of Nanoparticle Inclusions Upon The Microstructure And Thermoelectric Transport Properties Of Bismuth Telluride-Based Composites, Nick Gothard
All Dissertations
Research into materials that have high efficiencies of thermoelectric heat-energy conversion has been at a plateau since the middle of the last century. During this time, efficiencies have been engineered high enough for several interesting niche applications but not high enough for widespread adaptation into traditional power generation or refrigeration technologies. The past decade has seen considerable advancement as a number of theoretical works have suggested that lower dimensional structures could hold the key for enhanced efficiency, and several experiments have provided the proof of principle needed to inspire just such a research direction. The benefit of low dimensional structures …
3-D Calculation Of Atom-Surface Collisions With Direct Scattering, Trapping And Desorption, Guoqing Fan
3-D Calculation Of Atom-Surface Collisions With Direct Scattering, Trapping And Desorption, Guoqing Fan
All Dissertations
In this work a scattering theory is developed to simulate the gas-surface scattering procedure in three dimensions, using an iterative algorithm and classical mechanics for the collision process, that describes both direct scattering and trapping-desorption of an incident beam of atomic particles. The initially trapped fraction of particles can be followed as they continue to make further collisions with the surface until they are all eventually promoted back into the positive energy continuum and leave the surface region.
With two different models, the discrete model and the smooth-surface model of the differential reflection coefficient, a series of calculation are made …
Structure And Transport Characteristics Of Highly Rigid Ionomers, Lilin He
Structure And Transport Characteristics Of Highly Rigid Ionomers, Lilin He
All Dissertations
The structure and transport characteristics in a novel family of ionomers consisting of a hydrophobic polyphenylene backbone substituted by sulfonic acid functionalized phenyl side chains (sPPs) have been investigated. These polymers have potential applications in electrochemistry as well as separation both as membranes and thin films. The bulk structure as a function of hydration has been explored by X-ray and neutron scattering. Interfacial structure was studied by AFM and neutron reflectometry. The characteristics of water in the bulk were studied by NMR and FTIR and that in thin films by neutron reflectometry.
The sPPs exhibit characteristic structure due to their …
Lead Chalcogenide Nano-Composites: Synthesis, Thermal And Electrical Transport Properties, Bo Zhang
Lead Chalcogenide Nano-Composites: Synthesis, Thermal And Electrical Transport Properties, Bo Zhang
All Dissertations
This dissertation focused on the investigation of the thermoelectric properties of PbTe nanocomposites, presenting a series of experimental investigation and qualitative theoretical analysis regarding utilizing the nanostructures to enhance the thermoelectrical properties. Three innovative synthesis techniques, which are related to fabricating nanocomposites, were developed. These three techniques are the size-selective growth of PbTe nanoparticles by a convection CVD technique, the nanolayer coating technique by hydrothermal method, and the alkali-metal-nano-surface-treatment. In the future, these techniques can be applied to many other thermoelectric material systems.
We proposed to use the grain boundary engineering technique route in the thermoelectric nanocomposite field and successfully …
Synthesis And Pharmacology Of N-Alkyl-3-(Halo-Naphthoyl)Indoles, Valerie Smith
Synthesis And Pharmacology Of N-Alkyl-3-(Halo-Naphthoyl)Indoles, Valerie Smith
All Dissertations
The medicinal values of marijuana have often been overshadowed due to the psychotropic, 'recreational' effects it brings about in a user. For hundreds of years the therapeutic uses of cannabis sativa were appreciated, but the inability to control the dosage of the main constituent, and therefore the psychotropic effects, rendered the drug a liability. The elucidation of the structure of this main psychoactive constituent, ∆9-tetrahydrocannabinol (∆9-THC) by Gaoni and Mechoulam in 1964 opened the door to the discovery of a vast array of knowledge about cannabinoids. From the multiple classes of cannabinoids and the ways these compounds interact with the …
Homomorphisms Of Graphs, Samuel Lyle
Homomorphisms Of Graphs, Samuel Lyle
All Dissertations
Understanding the structure of graphs is fundamental to advances in many areas of graph theory, as well as in many applications. In many cases, an analysis of the structure of graphs follows one of two approaches; either many structural properties are considered over a restricted class of graphs, or a particular structural property is considered over many classes of graphs. Both approaches will be considered in this dissertation.
Graphs which do not contain a clique of size r, i.e., Kr-free graphs, are of fundamental importance in the area of extremal graph theory. Many results have been obtained …
Effects Of Polyphenol Compounds On Iron-And Copper-Mediated Dna Damage: Mechanisms And Predictive Models, Nathan Perron
Effects Of Polyphenol Compounds On Iron-And Copper-Mediated Dna Damage: Mechanisms And Predictive Models, Nathan Perron
All Dissertations
Polyphenol compounds are widely recognized for their antioxidant activity; however, under some conditions these compounds can also exhibit prooxidant activity. This work examined the interactions of polyphenols with iron and copper to improve understanding of both their antioxidant and prooxidant effects. Polyphenols with catechol and gallol groups effectively inhibit iron-mediated oxidative DNA damage by chelating iron, with IC50 values ranging from 1-59 µM. Gallate compounds are more potent than their catecholate analogues in every instance, and their antioxidant potencies correlate to pKa values for the most acidic phenolic hydrogen. This correlation represents the first predictive model of …
Portfolio Selection Under Various Risk Measures, Hariharan Kandasamy
Portfolio Selection Under Various Risk Measures, Hariharan Kandasamy
All Dissertations
Portfolio selection has been a major area of study after Markowitz's ground-breaking paper. Risk quantification for portfolio selection is studied in the literature extensively and many risk measures have been proposed.
In this dissertation we study portfolio selection under various risk measures. After exploring important risk measures currently available we propose a new risk measure, Unequal Prioritized Downside Risk (UPDR). We illustrate the formulation of UPDR for portfolio selection as a mixed-integer program. We establish conditions under which UPDR can be formulated as a linear program.
We study single-period portfolio selection using two risk measures simultaneously. We propose four alternate …
Electrochemical Synthesis And Characterization Of Polymers From Bis(3,4-Ethylenedioxythiophene)-Thiophenes (Bedot-Ts) And Bis(3,4-Ethylenedioxythiophene)-Benzenes (Bedot-Bs) As Optoelectronic Materials, Kalya Eaiprasertsak
All Dissertations
ABSTRACT
A series of bis(3,4-ethylenedioxythiophene)-thiophene derivatives (BEDOT-Ts) and bis(3,4-ethylenedioxythiophene)-benzene derivatives (BEDOT-Bs) monomers were electrochemically polymerized onto glassy carbon or ITO-coated glass electrodes. Cyclic voltammetry (CV), infrared (IR), UV-vis-NIR and photoluminescence (PL) spectroscopy were employed to investigate and characterize properties of resulting polymers. dc-conductivities of these polymers were measured by the four-point probe method.
Cyclic voltammetry studies show that the redox half potentials of PBEDOT-3BT, PBEDOT-3OT, PBEDOT-3TBS and PBEDOT-3MPT are -290, -297, -325 and -284 mV versus Ag/Ag+, respectively. The redox half potentials of PBEDOT-TOL, PBEDOT-BOB and PBEDOT-FB are -130, -147 and -327 mV vs. Ag/Ag+, respectively, and a bit higher …