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Articles 1 - 22 of 22
Full-Text Articles in Physical Sciences and Mathematics
The Unique Electrochemical Reactivity Of Small Metal Nanoparticles., Rafael A. Masitas
The Unique Electrochemical Reactivity Of Small Metal Nanoparticles., Rafael A. Masitas
Electronic Theses and Dissertations
This dissertation describes the factors controlling metal nanoparticle (NP) oxidation, using Au oxidation in Br- and Ag oxidation in acid as model systems. We found that the oxidation potential depends on size, surface charge, and electrode material. Size has a dramatic effect, shifting about 200 mV from > 200 nm diameter down to 4 nm diameter. The shift is more dramatic below 4 nm. 2.3 nm average diameter Au NPs oxidized in the 300-500 mV range and 1.5 nm average diameter Au NPs displayed several sharp peaks from 200 mV to as low as -200 mV. These smallest Au NPs show …
Electrochemical Formation Of One-Dimensional Metal Nanostructures Across Microgaps Electrodes For Resistive Switching And Optical Sensing Applications., Nidhi Shah
Electronic Theses and Dissertations
This dissertation focuses on the electrochemical formation of one-dimensional (1D) Ag nanostructures (in particular nanowires and nanochains) directly on electrode surfaces or gap of two electrodes. Ag nanowires (NWs) and nanorods (NRs) grow directly on glass/indium tin oxide (ITO) surfaces from electrode-attached Au nanoparticle seeds in the presence of cetyltrimethylammonium bromide (CTAB) at appropriate potentials with a 5-15 % yield and the average length ranging from 100 nm to 3 µm for growth times of 30 to 120 min. This method failed when trying to grow Ag NRs/NWs across 5 µm Au electrode gaps. Interestingly, applying voltage in air leads …
Spreading Speeds And Traveling Waves In Some Population Models., Quancheng Meng
Spreading Speeds And Traveling Waves In Some Population Models., Quancheng Meng
Electronic Theses and Dissertations
Virtually every ecosystem has been invaded by exotic organisms with potentially drastic consequences for the native fauna or flora. Studying the forms and rates of invading species has been an important topic in spatial ecology. We investigate two two-species competition models with Allee effects in the forms of reaction-diffusion equations and integro-difference equations. We discuss the spatial transitions from a mono-culture equilibrium to a coexistence equilibrium or a different mono-culture equilibrium in these models. We provide formulas for the spreading speeds based on the linear determinacy and show the results on the existence of traveling waves. We also study a …
Multiple Instance Fuzzy Inference., Amine Ben Khalifa
Multiple Instance Fuzzy Inference., Amine Ben Khalifa
Electronic Theses and Dissertations
A novel fuzzy learning framework that employs fuzzy inference to solve the problem of multiple instance learning (MIL) is presented. The framework introduces a new class of fuzzy inference systems called Multiple Instance Fuzzy Inference Systems (MI-FIS). Fuzzy inference is a powerful modeling framework that can handle computing with knowledge uncertainty and measurement imprecision effectively. Fuzzy Inference performs a non-linear mapping from an input space to an output space by deriving conclusions from a set of fuzzy if-then rules and known facts. Rules can be identified from expert knowledge, or learned from data. In multiple instance problems, the training data …
The Pc-Tree Algorithm, Kuratowski Subdivisions, And The Torus., Charles J. Suer
The Pc-Tree Algorithm, Kuratowski Subdivisions, And The Torus., Charles J. Suer
Electronic Theses and Dissertations
The PC-Tree algorithm of Shih and Hsu (1999) is a practical linear-time planarity algorithm that provides a plane embedding of the given graph if it is planar and a Kuratowski subdivision otherwise. Remarkably, there is no known linear-time algorithm for embedding graphs on the torus. We extend the PC-Tree algorithm to a practical, linear-time toroidality test for K3;3-free graphs called the PCK-Tree algorithm. We also prove that it is NP-complete to decide whether the edges of a graph can be covered with two Kuratowski subdivisions. This greatly reduces the possibility of a polynomial-time toroidality testing algorithm based solely on edge-coverings …
Application Of Surface Chemistry At The Interface Of Mesoporous Tio2 Films For Stable And High Efficiency Dye-Sensitized Solar Cells., Tulashi Luitel
Application Of Surface Chemistry At The Interface Of Mesoporous Tio2 Films For Stable And High Efficiency Dye-Sensitized Solar Cells., Tulashi Luitel
Electronic Theses and Dissertations
Solar energy is widely believed to be the most promising renewable energy source to fulfill the ever-increasing energy demand from human society now and into the future. Dye-sensitized solar cells (DSSCs) have been explored as a potentially low-cost alternative to silicon solar cell technology due to their lower fabrication costs compared to crystalline semiconductor photovoltaics. However, the optimized efficiency for DSSCs has not been achieved yet, and the chemical stability between dye and semiconductor has also not been addressed completely. In this research, we applied the following four main strategies to prepare photoanodes used in DSSCs with the aim of …
Order Automorphisms On The Lattice Of Residuated Maps Of Some Special Nondistributive Lattices., Erika D. Foreman
Order Automorphisms On The Lattice Of Residuated Maps Of Some Special Nondistributive Lattices., Erika D. Foreman
Electronic Theses and Dissertations
The residuated maps from a lattice L to itself form their own lattice, which we denote Res(L). In this dissertation, we explore the order automorphisms on the lattice Res(L) where L is a finite nondistributive lattice. It is known that left and right composition of f ∈ Res(L) with automorphisms of L yields an order automorphism of Res(L). It begs the question, then, if all order automorphisms of Res(L) can be classified as such.
Phosphinimine Zinc Complexes And Neutral Phosphinimines For Ring Opening Polymerization Of Lactides., Rajesh Thapa
Phosphinimine Zinc Complexes And Neutral Phosphinimines For Ring Opening Polymerization Of Lactides., Rajesh Thapa
Electronic Theses and Dissertations
Achiral arenesulfonates ligands having a (NNN) or (NNO) side arm have been developed (Chapter 2) and their respective zinc ethyl complexes, NNNZnEt 3.2 and NNOZnEt 3.3, have been synthesized and characterized using spectroscopic methods (Chapter 3). NNNZnEt as well as NNOZnEt complexes are stable under nitrogen atmosphere. In the NNOZnEt 3.3 complex the protons associated with the pendant (dimethylamino)ethyl arm are broad indicating that a fluxional process is operative, most likely dissociation of the (dimethylamino)ethyl arm at 25 °C in CD2Cl2. The fluxional behavior present in the 1H NMR spectrum of 3.2 could be arrested by cooling the CD2Cl2 solution …
The Local Cygnus Cold Cloud And Further Constraints On A Local Hot Bubble., Geoffrey Robert Lentner
The Local Cygnus Cold Cloud And Further Constraints On A Local Hot Bubble., Geoffrey Robert Lentner
Electronic Theses and Dissertations
Recent studies of the local interstellar medium have identified regions of nearby cold neutral gas with unexpected low temperatures and high pressures well within the boundaries of the local cavity (Meyer et al., 2006). Now, a multi-wavelength study of the local Leo cold cloud (LLCC) has strengthened our understanding of this apparent conflict with the conventional view of this environment (Peek et al., 2011, Meyer et al., 2012). The soft X-ray background observed here cannot be completely accounted for by a local hot bubble model (Snowden et al., 2015). Interstellar absorption of Na I (D2 λ5889.591 and D1 λ5895.924) was …
Combination Treatment With Conjugated Linoleic Acid And Nitrite Protects Against Myocaridal Infarction., Natia Qipshidze Kelm
Combination Treatment With Conjugated Linoleic Acid And Nitrite Protects Against Myocaridal Infarction., Natia Qipshidze Kelm
Electronic Theses and Dissertations
According to the CDC, the most common type of heart disease is coronary artery disease, which frequently leads to myocardial infarction (MI). Therapeutic approaches to lessen the resulting cardiovascular injury associated with MI are limited. Recently, the management paradigm for cardiac injury has entered the molecular era and microRNAs (miRNAs) have been shown to act as negative regulators of gene expression by inhibiting mRNA translation and/or stimulating mRNA degradation. A single miRNA can modulate physiological or disease phenotypes by regulating whole functional systems. Importantly, miRNAs can regulate cardiac function, thereby modulating heart muscle contraction, heart growth and morphogenesis. MicroRNA-499 (miRNA-499) …
Mathematical Studies Of The Glucose-Insulin Regulatory System Models., Minghu Wang
Mathematical Studies Of The Glucose-Insulin Regulatory System Models., Minghu Wang
Electronic Theses and Dissertations
Three dynamic models are proposed to study the mechanism of glucose-insulin regulatory system and the possible causes of diabetes mellitus. The progression of diabetes comes along with the apoptosis of pancreatic beta-cells. A dynamical system model is formulated based on physiology and studied by geometric singular perturbation theory. The analytical studies reveal rich analytical features, such as persistence of solutions, Hopf bifurcation and backward bifurcation, while numerical studies successfully fit available longitudinal T2DM data of Pima Indian tribe. These studies together not only validate our model, but also point out key intrinsic factors leading to the development of T2DM. We …
Chaos In Semiflows., Chad Money
Chaos In Semiflows., Chad Money
Electronic Theses and Dissertations
All the common notions about dynamics in cascades - topological transitivity, periodic points, sensitive dependence, and so forth - can be formulated in the context of a general abelian semiflow. Many intricate results, such as the redundancy of Devaney chaos, remain true (with very minor qualifications) in this wider context. However, when we examine general monoid actions on a product space, it turns out that the topological and algebraic structure of N0 plays a large role in the preservation of chaotic properties. In order to obtain meaningful results in that arena, new ideas such as “directional” and “synnrec” are introduced, …
Strong Quota Pair Systems And May's Theorem On Median Semilattices., Lucas Hoots
Strong Quota Pair Systems And May's Theorem On Median Semilattices., Lucas Hoots
Electronic Theses and Dissertations
Kenneth May [16], in 1952, characterized simple majority rule in terms of three conditions: anonymity, neutrality, and positive responsiveness. In this thesis, we remove the condition of neutrality and obtain a characterization of the class of voting rules that satisfy anonymity and positive responsiveness. The key concept in this characterization is the notion of a strong quota pair system. The situation with two alternatives studied by May can be thought of as a very simple example of a finite median semilattice. The main result of this thesis is an extension of May’s theorem to the domain of all finite median …
Optical And Sensing Properties Of Various Shaped Gold Nanoplates And Highly Controlled Asymmetric Gold Nanoplate/Nanosphere Coupled Assemblies., Aiqin Fang
Electronic Theses and Dissertations
With the development of a strategy to correlate the dark-field light scattering spectra of individual nanostructures with scanning electron microscopy (SEM) and atomic force microscopy (AFM) images of the same nanostructures, we were able to investigate several interesting optical properties of Au nanoplates (NPs) and asymmetrically-coupled Au nanospheres (NSs) attached to Au NPs with a high level of control. The light scattering spectra of the NP/NS coupled structures depend strongly on the location of NS attachment on the NP. Attachment of multiple NSs at the edge/vertex sites leads to a unique synergistic effect. In contrast to the uniform distribution of …
Novel Applications Of And Extensions To Linear Regression Methods For The Biomedical And Materials Sciences., Joe Bible
Electronic Theses and Dissertations
In this work we present three topics, each of which centered on either the application or modification of various linear regression methods. Our work with respect to the “Materials Genome” project while undermined by oversimplification and data integrity issues in its early stages, provides a sound platform from which the project can proceed successfully. Building upon a growing body of knowledge around the use of Weighted Generalized Estimating Equations (WGEE), our second investigation proposes an extension to that framework intended to address the inherent bias present in the analysis of clustered longitudinal data with potentially informative cluster sizes and temporal …
Analysis Of Anacardic Acid On The Surface Of Pelargonium × Hortorum Using Matrix Assisted Laser Desorptoin Ionization Mass Spectrometry Imaging., Bryan Edward Wessel 1989-
Analysis Of Anacardic Acid On The Surface Of Pelargonium × Hortorum Using Matrix Assisted Laser Desorptoin Ionization Mass Spectrometry Imaging., Bryan Edward Wessel 1989-
Electronic Theses and Dissertations
The biosynthetic pathway leading to the production of anacardic acids (AnAcs) in glandular trichomes on the surface of geranium plants remains unclear. Anacardic acids are salicylic acid derivatives known to possess various medicinal benefits. Gene silencing techniques, such as RNA interference, could be useful in determining specific enzymes involved in the synthesis of AnAcs. However, it is first necessary to develop methodologies to image AnAcs. In this project, both fluorescence (FL) and mass spectral imaging (MSI) were tested. Our results indicate that cellular imaging of AnAcs, via FL, is not suitable because the spectral ranges of absorption and emission of …
Improved Self-Consistency For Sced-Lcao., Lyle C. Smith
Improved Self-Consistency For Sced-Lcao., Lyle C. Smith
Electronic Theses and Dissertations
In this document I describe a novel implementation of the generalized bisection method for finding roots of highly non-linear functions of several variables. Several techniques were optimized to reduce computation time. The implementation of the bisection method allows for the calculation of heterogeneous systems with SCED-LCAO, since derivative-based methods often fail for these systems. Systems composed of Gallium and Nitrogen are currently receiving much interest due to their behavior as semi-conductors and their ability to form nano-wires. The methods developed here were employed to create a set of SCED-LCAO parameters for homogeneous Gallium and heterogeneous Gallium Nitride systems. These parameters …
Sulfur-Oxidation Enhances Nitrile Hydration In Bioinspired Ruthenium Complexes : Catalytic, Kinetic, And Dft Investigations., Davinder Kumar
Sulfur-Oxidation Enhances Nitrile Hydration In Bioinspired Ruthenium Complexes : Catalytic, Kinetic, And Dft Investigations., Davinder Kumar
Electronic Theses and Dissertations
The current dissertation focuses on the effects of sulfur‒oxidation on nitrile hydration activity of a series of ruthenium(II) complexes inspired by nitrile hydratase (NHase). NHase catalytically hydrates nitriles to amides at a low spin non‒heme Fe(III) or non‒corrin Co(III) metal center. The active‒site employs a N2S3X type donor set using two carboxamido nitrogens and three cofacial cysteinic sulfurs that are present in distinct oxidation states as sulfinate (RSO2¯), sulfenate (RSO¯), and thiolate (RS¯). The apical site is occupied by substrate or solvent. A lack of sulfur‒oxidation renders the enzyme inactive. Three precatalysts, LnRuPPh3 (n = 1‒3), are employed to assess …
High-Precision Time-Series Photometry For The Discovery And Characterization Of Transiting Exoplanets., Karen Alicia Collins 1962-
High-Precision Time-Series Photometry For The Discovery And Characterization Of Transiting Exoplanets., Karen Alicia Collins 1962-
Electronic Theses and Dissertations
The discovery of more than a thousand planets orbiting stars other than the Sun (i.e. exoplanets) over the past 20 years has shown that planetary systems are commonplace in the Milky Way galaxy. However, these discoveries are only a starting point in the quest to answer one of the most compelling questions posed by mankind for centuries – "are we alone in the universe?". This research aims to help build the foundation needed to search for that answer by optimizing data reduction techniques, determining and refining fundamental properties of known exoplanets, and searching for new exoplanets. Many exoplanets have been …
Optcluster : An R Package For Determining The Optimal Clustering Algorithm And Optimal Number Of Clusters., Michael N. Sekula
Optcluster : An R Package For Determining The Optimal Clustering Algorithm And Optimal Number Of Clusters., Michael N. Sekula
Electronic Theses and Dissertations
Determining the best clustering algorithm and ideal number of clusters for a particular dataset is a fundamental difficulty in unsupervised clustering analysis. In biological research, data generated from Next Generation Sequencing technology and microarray gene expression data are becoming more and more common, so new tools and resources are needed to group such high dimensional data using clustering analysis. Different clustering algorithms can group data very differently. Therefore, there is a need to determine the best groupings in a given dataset using the most suitable clustering algorithm for that data. This paper presents the R package optCluster as an efficient …
A Study Of The Catalytic And Chemical Properties Of Palladium And Palladium-Silver Monolayer Protected Clusters., Luther Benjamin Hutcherson
A Study Of The Catalytic And Chemical Properties Of Palladium And Palladium-Silver Monolayer Protected Clusters., Luther Benjamin Hutcherson
Electronic Theses and Dissertations
This thesis describes a study of the ligand chemistry of Pd Monolayer-Protected Clusters (MPCs) synthesized in the presence of octylamine. MPCs consists of a metal core surrounded by various organic stabilizers. Pd MPCs coated with alkanethiols, alkylamine, dendrimers, surfactants, and polymers have recently been explored for catalysis applications.Pd MPCs coated with alkylamines are more catalytically active than alkanethiols for hydrogentation/isomerization of allyl alcohol, but at shorter chain lengths are unstable in H2. We explored Pd MPCs synthesized in the presence of octylamines and discovered that the ligands attach to Pd as octanenitrile. This amine to nitrile conversion is catalyzed by …
Summary Of Survival Analysis With Sas Procedures., Derek Duane Childers 1990-
Summary Of Survival Analysis With Sas Procedures., Derek Duane Childers 1990-
Electronic Theses and Dissertations
The research conducted for this thesis was performed to summarize some of the most commonly used survival analysis techniques as well as to create one macro that will provide the solutions for these techniques. Some of the techniques that this thesis focuses on are survival and hazard functions, mean and median survival times, life table, log rank test, proportional hazards/model building, and competing risk. To further analyze these survival analysis techniques I will use the Bone Marrow Transplantation for Leukemia dataset. This trial consists of either acute myelocytic leukemia (AML 99 patients) or acute lymphoblastic leukemia (ALL 38 patients). There …