Physical Sciences and Mathematics Commons^™

Photocatalytic Degradation Of Simazine Under Visible Light Using Zinc Oxide/Molybdenum Disulfide Heterostructures, Alexandria Castillo

Theses and Dissertations

The photocatalytic degradation of simazine under visible light by using ZnO/MoS2 heterostructures was investigated. Reaction parameters studied to optimize simazine degradation included pH, loading mass of the photocatalyst, and percentage of MoS2 in the heterostructure. pH 2 was the optimal environment for the degradation reaction of all catalysts. A loading mass of 20 mg for each of the ZnO/MoS2 photocatalysts was determined to be the most effective for in the degradation process. The degradation reactions were observed to follow 2nd order kinetics for all photocatalysts at all temperatures. Band gap studies confirmed a lower energy than that of pure ZnO …

The Curious Case Of Nad-Cleaving Nudix Hydrolases, Atreyei Ray

Theses and Dissertations

Nudix proteins are members of a large family of homologous enzymes that hydrolyze nucleoside diphosphates linked to other compounds (x). These enzymes have catalytic activity on a wide range of substrates such as dNTPs (both canonical and their oxidized forms), nucleotide sugars, alcohols, dinucleoside polyphosphates, dinucleotide cofactors, and nucleoside diphosphates linked to RNA. The bacterial genome encodes around 13, while the human genome encodes for 22 such nudix proteins.

The E. coli genome encodes for a mutT mutator gene, the progenitor of the family expressing the MutT pyrophosphohydrolase (NudA) protein (Treffers et al., 1954; Bhatnagar et al., 1988). The enzyme …

Probing The Early Steps In The Catalytic Reduction Of Nitrite To Ammonia, Catalyzed By Cytochrome C Nitrite Reductase, Md Mahbbat Ali

Theses and Dissertations

Cytochrome c Nitrite Reductase (ccNiR) is a periplasmic, decaheme homodimeric enzyme that catalyzes the six-electron reduction of nitrite to ammonia. Under standard assay conditions catalysis proceeds without detected intermediates, and it’s been assumed that this is also true in vivo. However, this report demonstrates that in vitro it’s possible to trap putative intermediates by controlling the electrochemical potential at which reduction takes place. Such experiments provide valuable insights regarding ccNiR-catalyzed nitrite ammonification.

UV/Vis spectropotentiometry showed that nitrite-loaded Shewanella oneidensis ccNiR is reduced in a concerted 2-electron step to generate an {FeNO}7 moiety at the active site, with an associated midpoint …

Optimizing Hydrogen Sulfide Removal And Biogas Production Using The Water Wash Method, Brian Leightner

Theses and Dissertations

Biogas forms from decomposing organic material in agricultural digesters, landfills, and wastewater treatment plant digesters. Biogas is mostly composed of methane, and can be used as a carbon-based fuel. Microorganisms that consume organics in these waste streams also produce hydrogen sulfide (H2S) as part of the biogas, in varying trace amounts. H2S is corrosive to engines and pipes for machinery, a human health hazard when inhaled, and an aquatic hazard when dissolved in water. Water washing is an absorption process that dissolves hydrogen sulfide and other water soluble compounds in this process and carries it away from the gas, thereby …

Chemical Self-Assembly Strategies Toward The Design Of Molecular Electronic Circuits, Dustin Olson

Theses and Dissertations

The field of molecular electronics is generally divided into one of two major categories, the first focusing on the unique functionalization of single molecules to produce electronic behavior, the other utilizing large assemblies of molecules to produce electronic behavior. The former approach is largely attributed to the seminal paper by Aviram and Ratner in which they proposed a molecular donor-bridge-acceptor (D-B-A) type architecture could lead to single molecule rectification producing electronic effects similar to conventional semiconductor based diodes. Extensive research has been carried out in both fields as it is foreseen that new approaches to electronics miniaturization will be necessary …

Part I: A Concise Asymmetric Synthesis Of Microtubule Inhibitor Tryprostatin B Part Ii: Synthesis And Biological Assessment Of Histone Deacetylase (Hdac) Inhibitors Part Iii: Acid Catalyzed Reactions Of Aromatic Ketones With Ethyl Diazoacetate, Md Mizzanoor Rahaman

Theses and Dissertations

PART I: A CONCISE ASYMMETRIC SYNTHESIS OF MICROTUBULE INHIBITOR TRYPROSTATIN B

Tryprostatin (TPS) A and B, microtubule inhibitor, are the members of a family of prenylated Trp-Pro diketopiperzine alkaloids. These two natural products were isolated in 1995 from the fermentation broth of Aspergillus fumigatus BM939 by Osada and coworkers. TPS and related diketopiperazine containing compounds such as phenylahistins, spirotryprostatins, and cyclotryprostatins are inhibitors of the mammalian cell cycle. They prevent cell cycle progression at the G2/M phase through a unique mechanism consisting of inhibiting the interaction between microtubule assisted proteins (MAP-2) and the C-terminal end of tubulin. TPS A and …

Controlling And Manipulating Microscopic Particles In Solution By Using Various Electric Field Geometries, Xavier Sacro Udad

Theses and Dissertations

Progress in micro- and nanotechnologies depends on our capability of manipulating and interacting with microscopic particles and nanosize material. A promising approach towards this goal is the use of electric fields, which are the dominant forces at the molecular length scale. One technique for trapping nanoparticles in solution uses an externally controlled electric field, generated by two electrode pairs, to counteract the Brownian motion of a single, selected particle. Unlike other trapping tools, such as optical tweezers or magnetic tweezers, this approach scales favorably with particle size, down to the level of a single molecule. However, it depends on real-time …

Syntheses, Characterization, And Preliminary Evaluation Of Potential Ruthenium Anticancer Complexes Containing Schiff Base Ligands, Stephen Mensah

Theses and Dissertations

Platinum-based drugs have over the years been administered in the treatment of tumours.

Unfortunately, platinum resistance and the severe side effects associated with the treatments has necessitated the research for new anti-cancer drugs. Ruthenium(II) and Ruthenium(III) complexes have shown promise as useful alternative anticancer agents. The lead candidates include the Ru(II) complex RAPTA-C, a ruthenium(II)-arene complex [Ru(η6-p-cymene)Cl2(1,3,5-triaza-7-phosphaadamantane)] and the Ru(III) complex NAMI-A [imidazoleH][trans-Ru(imidazole) (dimethyl sulfoxide)Cl4]. Both compounds have shown potent cytotoxic activity in several primary human tumor models. Unfortunately, NAMI-A could not advance in clinical evaluations due to limited efficacy in vivo, while the clinical evaluation of RAPTA-C is unknown. …

Cdse Quantum Dot Surface Chemistry Thermodynamics Via Isothermal Titration Calorimetry: An Emphasis On The Fundamentals, Megan Y. Gee

Theses and Dissertations

For several decades, the study and development of colloidal semiconductor nanocrystals, or quantum dots (QD), has become a rich field heralding improved integration into applications ranging from photovoltaics and photocatalysis to biomedical imaging and drug delivery. CdxSey is the most extensively studied QD system, however numerous compositional details still confound the nanocrystal field. Although CdSe QDs with native ligand coatings can show high fluorescence quantum yield and may be suitable for some applications, often times these original ligand layers are comprised of long aliphatic chains that preclude incorporation into biological matrices or severely impede charge transfer – depending on the …

Frontiers In Fast Voltammetry: Novel Analytes And Applications, Jordan Holmes

Theses and Dissertations

Electrochemical sensors are beneficial towards the development and advancement of monitoring devices. As this type of technology progresses, so does our ability to create state-of-the-art sensing strategies to probe environmental and biological systems at the source. In the environment, it is essential to monitor particularly harmful contaminants like trace metals in order to better mitigate risk. Additionally, biological molecules are often times challenging to measure because matrices are complex and difficult to probe; Recent advancements in chemical ex vivo and in vivo sensing platforms have offered insight into physiological processes. The brain in particular requires a sophisticated, implantable sensor as …

Study Of Transition State Stabilization Using Molecular Rotors, Erik Carl Vik

Theses and Dissertations

Molecular devices that function as rotors and measurement devices are the main topic of this dissertation. Each study contains a device based on an N-phenylimide framework, which has restricted rotation about the N-C (imide-phenyl) single bond due to a steric clash from the imide carbonyl and the phenyl rings ortho substituent. In general, two ground states are observed by 1H NMR, which are separated by a single transition state (TS). Incorporation of non-covalent interactions into the TS led to measurable changes in the rate for rotation. While the molecules in this dissertation revealed details that could not have been predicted, …

Elucidating The Mechanism Of Bone Morphogenetic Protein (Bmp) -Mediated Sox2 Downregulation In Ovarian Cancer, Zainab Motolani Shonibare

Theses and Dissertations

Sex determining region Y-box 2 (Sox2) is a transcription factor essential for maintaining self-renewal and pluripotency of undifferentiated embryonic stem cells. Sox2 is involved in multiple processes of cancer cells, however, regulation of Sox2 expression and the consequences of that regulation in cancer remains elusive. Previously, we demonstrated that BMP9/GDF2 is significantly reduced in expression in ovarian cancer (OVCA) cells, methylated in patient tumors and, promoted anoikis resistance in both breast and OVCA cell lines. In an attempt to identify genes downstream of BMP9 that may provide anoikis resistance, transcriptomics was performed leading to the identification of Sox2, a developmental …

A Spatial Heterodyne Spectrometer For Raman Imaging And Remote Spectroscopy, Ashley Nicole Allen

Theses and Dissertations

Raman and Laser-Induced Breakdown Spectroscopy (LIBS) are optical techniques that provide information about the chemical makeup of a sample without any preparation or physical contact with it. For this reason, Raman and LIBS spectrometers are among the instruments selected for NASA’s Mars 2020 rover mission and are being considered for future missions to the Jovian moons, asteroids and comets. Such future missions will require smaller, more ruggedized Raman and LIBS spectrometers, and the new type of spectrometers discussed here, the spatial heterodyne Raman and LIBS spectrometers are being developed for this purpose. The SHS is a wide-field, Fourier transform, stationary …

Macromolecular Engineering Of Biomass Polymers And Stimuli-Responsive Materials Towards Enhanced Thermomechanical Properties, Meghan E. Lamm

Theses and Dissertations

Commodity polymers are used in every aspect of daily life, and most of these polymeric materials are synthesized using petroleum-derived sources. There are direct environmental consequences to this petroleum dependence including greenhouse gas emissions and climate change. Biomass-based polymers show promise for the mitigation on negative environmental impact, in comparison with petroleum-derived counterparts. However, some biopolymers suffer from low chain entanglement due to bulky or long side chain structures, resulting in poor mechanical properties. In this dissertation work, macromolecular engineering is used to design biomass-derived polymers featuring a variety of structures and functionalities. Additionally, biopolymer properties (including thermomechanical enhancement) and …

Studies On The Mechanism And Application Of Steam Thermography, Raymond Gerard Belliveau Iii

Theses and Dissertations

The detection of blood on fabrics for forensic purposes is a widely studied topic in forensic science, and to that end, effort in this laboratory has been devoted to developing a thermal imaging method called steam thermography. Steam thermography is a method used to enhance chemical contrast in thermographic images by exposing a surface to water vapor during imaging. The exposure of water vapor to the surface generates heat, and can differentially increase the thermographically measured apparent temperature of imaged surfaces. This can result in thermographic contrast between surfaces with different chemical properties. Previously reported proposed mechanisms to describe the …

Heterogeneous Ozonation Of Model Drinking Water Contaminants Using Cbv-720 Zeolite, Benson Maxwell Solomon

Theses and Dissertations

Advanced Oxidation Processes (AOPs) are designed to remove aqueous organic contaminants through their reaction with hydroxyl radicals (HO∙). Ozone is classified as an AOP due to its ability to produce hydroxyl radicals, as well as its ability to oxidize a wide range of organic contaminants. Due to the unselective nature of hydroxyl radicals, many organic and inorganic co-solutes can act as scavengers, reducing the efficiency of an AOP. Here we show a probe system for testing the hypothesis that adsorptive ozonation of contaminants may yield a more selective environment that favors neutral contaminant oxidation over oxidation of co-solutes.

Initial experiments …

The Development Of Multi-Functional System That Combine Patterned Hydrogels, Plasmin-Degradable Nanoparticles And Stem Cells For Applications In Tissue Engineering And Growth Factors Delivery, Safaa I. Kader

Theses and Dissertations

This thesis spots the light on the development of a novel multi-functionalized system for application in tissue engineering and on-demand morphogens delivery. Three types of materials used in this study are synthetic polymer, biopolymer, and nanomaterials. Polyethylene glycol (PEG), a synthetic polymer was chosen in this study because of its high biocompatibility, non-immunogenicity, inert nature, ease of modification, and reduces protein denaturation to provide a wide range of physical and mechanical properties. Here, PEG is used one time as a hydrogel, linear polyethylene glycol-co-lactide (LPELA), and another time as peptide-PEG based nanoparticles (PxSPCP). Gelatin, a natural polymer has been widely …

Designing, Constructing, And Employing Two-Dimensional Ultrafast Spectroscopy To Resolve Complex Kinetics, Jason R. Darvin

Theses and Dissertations

Multiple population-period transient spectroscopy (MUPPETS) is a two dimensional ultrafast time resolved spectroscopy technique. MUPPETS uses three pairs of optical pulses over two time periods to separate homogeneous and heterogeneous causes of rate dispersion. This dissertation details improvements to the MUPPETS optical assembly enabling measurements on systems that previously fell outside of the MUPPETS 2-ns time window. In addition, the theoretical groundwork is laid to unveil the hidden coordinate controlling rate exchange using 2D and 3D correlation functions.

The first project details improvements made to the MUPPETS assembly. A detailed method was developed to eliminate astigmatism, coma, and spherical aberration …

Studies Of Ch Activation In Unsaturated Amides And Esters By Trinuclear Metal Carbonyl Clusters Of Osmium, Morteza Maleki

Theses and Dissertations

The chemistry of the reaction of Os3(CO)10(NCCH3)2 with representatives of unsaturated amides and esters, RCOCHCH2 (R=(CH3)2N, CH3O) has been investigated. In these reactions, it has been observed that a CH bond on the β-carbon atom is readily activated by triosmium carbonyl clusters. The activation of β-carbon C-H bond in unsaturated amides and esters provides a robust platform for studying multicenter C-H bond transformations and for C-C bond formation via hydrogen shift and CO insertion processes. In this work, proposed mechanistic approaches have been taken in order to better understand and study the relationship between the characterized species. In addition, a …

Self-Assembly And Emergent Properties Of Urea Tethered Triphenylamines For The Formation Of Regenerable Radicals, Ammon J. Sindt

Theses and Dissertations

Self-assembly of photoactive compounds in the solid-state can give rise to new photophysical properties. Key to these properties, is how these compounds can be organized in a uniform way. For this, hydrogen bonding building blocks can be used to guide the assembly of these compounds into organized structures. For instance, ureas, thioureas, and squaramides which contain both hydrogen bond donors and acceptors can guide the assembly of small m-xylene macrocycles in three distinct manners: 1-D columns, edge-to-face Herringbone patterns, and interdigitated networks. The former of these is commonly employed in our group to make either linear or macrocyclic dimers …

Investigation Of Electrostatic Interactions Towards Controlling Silylation-Based Kinetic Resolutions And Exploring The Effect Of The Polymer Backbone On Silylation-Based Kinetic Resolutions Employing A Polymer-Supported Triphenylsilyl Chloride, Tian Zhang

Theses and Dissertations

This dissertation focuses on studies of silylation-based kinetic resolution methodology developed by the Wiskur group, which is a powerful method for the separation of a single enantiomer from a mixture of racemic secondary alcohols. Chapter 1 introduces the background of our silylation-based kinetic resolution..

Chapter 2 involves mechanistic studies of electrostatic interactions in controlling enantioselectivities of our silylation-based kinetic resolution. Electrostatic interactions between a silylated isothiourea intermediate and an ester π system is determined via linear free energy relationship study. To be specific, how variations in sterics and electronics affect the selectivity of a silylation-based kinetic resolution.

Chapter 3 is …

Ultra-Fast Sensors To Study The Fundamental Neurochemistry Underlying Disease, Alyssa West

Theses and Dissertations

Serotonin is a vital neurotransmitter whose exact roles are ill-defined. Dysfunctions in serotonin signaling are thought to underlie a myriad of neurological problems including depression and autism spectrum disorder (ASD). Prior to investigating serotonin’s role in disease states, one must understand more about the functionality of serotonin in healthy in vivo models. To study serotonin in vivo, fast-scan cyclic voltammetry (FSCV) and fast- scan controlled adsorption voltammetry (FSCAV) are employed to measure evoked and basal serotonin concentration, respectively. These methods, combined with mathematical modeling, provide information regarding regulatory mechanisms of serotonin neurotransmission. FSCV and FSCAV are first applied to …

Synthesis And Characterization Of Hyaluronic Acid Based Biomaterials For Drug Delivery And Virus Modification, Amanda Wagner

Theses and Dissertations

In this thesis, hyaluronic acid based biomaterials are studied. The properties and potential applications of these polymers are characterized and discussed.

In Chapter 1, biomaterials are introduced as well as hydrogels and nanogels. Hyaluronic acid is highlighted as a remarkable bio-polymer. The overall objectives of my research are also discussed.

Chapter 2 is focused around trials for utilizing graphene oxide as a nanomaterial for controlling the drug release of an aromatic compound. Hyaluronic acid based hydrogels were synthesized as a delivery vessel. The results of the drug release profiles are examined and discussed.

A different direction is taken in Chapter …

Cationic Cobaltocene Derivatives And Polyelectrolyte Membranes For Energy Storage Applications, Tianyu Zhu

Theses and Dissertations

Metal-containing polyelectrolytes (or metallo-polyelectrolytes) represent a new class of polymeric materials with distinct properties compared to traditional organo- polyelectrolytes or neutral metallopolymers. This emerging class of synthetic materials is ubiquitous for a myriad of utilities ranging from traditional electrolyte chemistry to biomedicals to sustainable applications, to name just a few. This dissertation work is focused on the design, synthesis, characterization and application of advanced metallo- cations and metallo-polyelectrolytes for energy storage applications. First, a template method to prepare metallo-polyelectrolytes based on cationic cobaltocene and polyethylene backbone was described. The resulting membranes are mechanically tough, ionically conductive and chemically inert. Second, …

Preparation And Detailed X-Ray Photoelectron Spectroscopy And Spectroscopic Ellipsometryanalysis Of Ultrathin Protective Coatings, Brian Ivins Johnson

Theses and Dissertations

Ultra-thin films (UTFs) are important in many applications, seen in the semiconductor industry, in chromatography, in sensing, in microfluidics, in aerospace, and in robotics. They also protect materials from corrosion, change surface energies, limit water intrusion into materials, allow material self-cleaning and self-healing, provide scratch resistance, and impart other specific chemical properties. In many cases, UTFs drastically alter surface properties and therefore their applications. It is imperative that proper and consistent characterization be performed on coatings to confirm and understand their desired properties. In Chapter two, Al oxidation under MgF2 protective layers is studied using real time X-ray photoelectron spectroscopy …

Organic-Inorganic Hybrid Materials For Piezoelectric/Triboelectric Nanogenerator, Aminur Rashid Chowdhury

Theses and Dissertations

Nanogenerator has been a major focus among researchers of recent time due to its versatile use in everyday life. Though the discovery of the piezoelectricity and the triboelectricity dates back to 19th century, the use of these phenomena has not been in practical use till 2006. In this study we demonstrate the practical application of piezoelectric and triboelectric nanogenerator comprised of different copolymer and piezoelectric ceramic. The largely known piezoelectric polymer Polyvinylidene fluoride (PVDF) has also been utilized. The enhancement of piezoelectric properties of PVDF has been achieved by utilizing surface activation of accommodating ceramic. The Li doped ZnO has …

Removal Of As (Iii) And As (V) From Potable Water Using Zno Nanoparticles, Grecia Torreblanca Baez

Theses and Dissertations

Heavy metal and toxic element contamination of the environment has been increasing with increasing industrialization. Arsenic has become an element of particular concern because of its toxicity, which is oxidation state dependent. As(III) is observed to be much more toxic than As(V), as well the removal is more difficult than As(V) in traditional water treatment technology. In the present study, As (III) and As(V) removal was investigated using a zinc oxide nanomaterial that was synthesized using a titration/precipitation technique, and characterized using powder x-ray diffraction. In the present study, the kinetics of adsorption, the adsorption isotherms as well as the …

Preparation, Functionalization, And/Or Characterization By X-Ray Photoelectron Spectroscopy Of Carbon Surfaces For Biosensors And Other Materials, Varun Jain

Theses and Dissertations

My dissertation is primarily divided into two parts. The first deals with the preparation, functionalization, and characterization of carbon surfaces prepared by direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HiPIMS) as substrates for bioarrays. Part two discusses applications of XPS peak fitting in surface chemical analysis. Chapter 1, the introduction, includes (i) a discussion of the construction of bioarrays and the preparation of sputtered surfaces, e.g., by DCMS and HiPIMS, and also functionalization (bioconjugate) chemistry with special emphasis on the importance of covalent functionalization of surfaces, and (ii) a discussion of the surface characterization techniques and …

Computational Studies Of High-Oxidation State Main-Group Metal Hydrocarbon C-H Functionalization, Clinton R. King

Theses and Dissertations

High-oxidation state main-group metal complexes are potential alternatives to transition metals for electrophilic C-H functionalization reactions. However, there is little known about how selection of the p-block, main-group metal and ligand impact C-H activation and functionalization thermodynamics and reactivity. Chapter 2 reports density functional theory (DFT) calculations used to determine qualitative and quantitative features of C-H activation and metal-methyl functionalization energy landscapes for reaction between high-oxidation state d10s0 InIII, TlIII, SnIV, and PbIV carboxylate complexes with methane. While the main-group metal influences the C-H activation barrier height in a periodic manner, the carboxylate ligand has a much larger quantitative impact …

A Study In Molecular Recognition: Synthesis Of A Β-Sheet Mimic & Quantitation Of Metal Ions In Aqueous Solutions Through Solid Supported Semi-Selective Chemosensors, Tyler G. Fenske

Theses and Dissertations

From the hydrophobic effect, which is responsible for the organization of amphipathic molecules into cellular membranes, to the highly specific hydrogen binding patterns found in DNA base pairs that keeps our genetic material “zipped up”, non-covalent and reversible interactions are critical to properly functioning biological processes. Molecular recognition is an area of study that seeks to better understand these observed phenomena. In a general sense, association of “Host” and “Guest” molecules are based on ionic forces, hydrophobic interactions, cation-π effects, π-π stacking, conformational restriction, and many others. This dissertation will primarily focus on two projects that have an emphasis on …