Chemistry Commons^™

Spectroscopic Investigation Of The Chemical And Electronic Properties Of Chalcogenide Materials For Thin-Film Optoelectronic Devices, Kimberly Horsley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Chalcogen-based materials are at the forefront of technologies for sustainable energy production. This progress has come only from decades of research, and further investigation is needed to continue improvement of these materials.

For this dissertation, a number of chalcogenide systems were studied, which have applications in optoelectronic devices, such as LEDs and Photovoltaics. The systems studied include Cu(In,Ga)Se2 (CIGSe) and CuInSe2 (CISe) thin-film absorbers, CdTe-based photovoltaic structures, and CdTe-ZnO nanocomposite materials. For each project, a sample set was prepared through collaboration with outside institutions, and a suite of spectroscopy techniques was employed to answer specific questions about the system. These …

Human Whole-Blood (1)H2o Longitudinal Relaxation With Normal And High-Relaxivity Contrast Reagents: Influence Of Trans-Cell-Membrane Water Exchange, Gregory J. Wilson, Mark Woods, Charles S. Springer Jr., Sarah Bastawrous, Puneet Bhargava, Jeffrey H. Maki

Chemistry Faculty Publications and Presentations

PURPOSE: Accurate characterization of contrast reagent (CR) longitudinal relaxivity in whole blood is required to predict arterial signal intensity in contrast-enhanced MR angiography (CE-MRA). This study measured the longitudinal relaxation rate constants (R₁ ) over a concentration range for non-protein-binding and protein-binding CRs in ex vivo whole blood and plasma at 1.5 and 3.0 Tesla (T) under physiologic arterial conditions.

METHODS: Relaxivities of gadoteridol, gadobutrol, gadobenate, and gadofosveset were measured for [CR] from 0 to 18 mM [mmol(CR)/L(blood)]: the latter being the upper limit of what may be expected in CE-MRA.

RESULTS: In plasma, the ¹H2 O R …

Experimental Evidence For Colloid-Facilitated Transport Of Plutonium, Hilary Emerson

All Dissertations

Colloid-facilitated transport of the actinides has been observed previously in the field on the kilometer scale. The objective of this work is to investigate the mechanisms of colloid-facilitated transport with controlled settings and conditions. The experimental work in this dissertation investigates transport of a ternary complex with iron oxide colloids, organic ligands and actinides in the presence of quartz or a natural sandy soil as well as simplified systems building up to the ternary complexes. The first three papers investigate the following: (1) unsaturated transport of iron oxide colloids in a natural sandy soil lysimeter with and without natural organic …

Toward Understanding The Thermodynamics And Mechanisms Of Actinide Sorption Reactions, Shanna Estes

All Dissertations

The environmental fate of actinides is greatly influenced by interfacial reactions, including sorption onto solid surfaces. Because changes in the primary hydration sphere of the actinide are expected to greatly influence the thermodynamics (i.e., reaction enthalpy and entropy) of these reactions, examining actinide sorption thermodynamics may provide insight into actinide sorption mechanisms. Additionally, examining actinide sorption thermodynamics may enhance the ability to model or predict these reactions in environmental or engineered systems where variable or elevated temperatures are expected. However, few researchers have studied actinide sorption thermodynamics. Therefore, this research examined the thermodynamics of Eu(III) (a trivalent actinide analog), Th(IV), …

Surface Modifications Of Capillary-Channeled Polymer (C-Cp) Fiber Stationary Phases: Improving The Efficiency Of Highly Selective Analyte Separations, Abby Schadock-Hewitt

All Dissertations

High performance liquid chromatography (HPLC) is a fundamental methodology for the characterization and purification of macromolecules. Since its development in the 1970's, HPLC has significantly advanced its instrumentation and column technology to become a powerful analytical technique. A considerable amount of research focuses on advancements to the stationary phase, or solid support, on which molecules interact and separate. To overcome limitations of other phases that lead to poor mass transfer, slow speeds, and low efficiency, nonporous and superficially porous phases have been developed. Specifically, fiber based polymer stationary phases show great promise as stationary phases for protein separations. The Marcus …

Identification And The Significance Of Selective Proteins In Bile And Plasma Of Normal And Health-Compromised Chickens, Balamurugan Packialakshmi

Graduate Theses and Dissertations

During the last 50 years, animal breeding programs in commercial poultry have made significant progress in the bodyweight gain of broilers but led to several metabolic and skeletal disorders. Lameness associated with proximal femur known as femoral head separation (FHS) or femoral head necrosis (FHN) is one of the major metabolic disorders in poultry industry. In order to select for healthy chickens, markers that can distinguish between healthy and affected birds are required. Biomarkers from blood represent an ideal and rich source of markers which can be obtained using minimally invasive methods. The biomarkers were explored in an experimental model …

Designing Magnetically Responsive Ultrafiltration Membranes, Robert William Dong

Graduate Theses and Dissertations

Ultrafiltration (UF) membranes developed out of a need for protein separation processes. Currently, they are used in a variety of industries ranging from food manufacturing to pharmaceuticals for two main purposes: concentration, separation, and buffer exchange. UF membrane processes in product streams undergo frequent use and like all membrane processes experience a gradual decline in performance due to fouling phenomena both irreversible and reversible. Ultimately, performance declines to a point where the UF membrane needs to be replaced. Frequent replacement of UF membranes is detrimental to major industries that require high product throughput using UF processes. Thus, it is important …

Imaging, Spectroscopic, Mechanical And Biocompatibility Studies Of Electrospun Tecoflex® Eg 80a Nanofibers And Composites Thereof Containing Multiwalled Carbon Nanotubes, Javier Macossay-Torres, Faheem A. Sheikh, Travis Cantu, Thomas Eubanks, M. Esther Salinas, Chakavak S. Farhangi, Hassan Ahmad, M. Shamshi Hassan, Myung-Seob Khil, Shivani K. Maffi, Hern Kim, Gary L. Bowlin

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

The present study discusses the design, development and characterization of electrospun Tecoflex® EG 80A class of polyurethane nanofibers and the incorporation of multiwalled carbon nanotubes (MWCNTs) to these materials. Scanning electron microscopy results confirmed the presence of polymer nanofibers, which showed a decrease in fiber diameter at 0.5% wt. and 1% wt. MWCNTs loadings, while transmission electron microscopy showed evidence of the MWCNTs embedded within the polymer matrix. The fourier transform infrared spectroscopy and Raman spectroscopy were used to elucidate the polymer-MWCNTs intermolecular interactions, indicating that the C-N and N-H bonds in polyurethanes are responsible for the interactions with MWCNTs. …

Selective Indicators For Optical Determination Of Disease Biomarkers, Lovemore Hakuna

Dissertations and Theses

The most abundant biological thiols, homocysteine (Hcy), cysteine (Cys) and glutathione (GSH) have been the subject of intense research due to their association with a wide range of diseases. They play a key role in maintaining the redox status of biological systems. Selective detection methods for these thiols are challenging due to their similar structures and properties. Current commercially available detection methods use separations, fragile and expensive enzymatic or immunogenic materials and complex instrumentation. This has led to a global effort towards developing simple and inexpensive optical probes and indicators selective for specific biological thiols.

Highly selective chemical probes and …

Protein Expression, Characterization And Activity Comparisons Of Wild Type And Mutant Dusp5 Proteins, Jaladhi Nayak, Adam J. Gastonguay, Marat R. Talipov, Padmanabhan Vakeel, Elise A. Span, Kelsey S. Kalous, Raman G. Kutty, David R. Jensen, Phani Raj Pokkuluri, Daniel S. Sem, Rajendra Rathore, Ramani Ramchandran

Chemistry Faculty Research and Publications

Background

The mitogen-activated protein kinases (MAPKs) pathway is critical for cellular signaling, and proteins such as phosphatases that regulate this pathway are important for normal tissue development. Based on our previous work on dual specificity phosphatase-5 (DUSP5), and its role in embryonic vascular development and disease, we hypothesized that mutations in DUSP5 will affect its function.

Results

In this study, we tested this hypothesis by generating full-length glutathione-S-transferase-tagged DUSP5 and serine 147 proline mutant (S147P) proteins from bacteria. Light scattering analysis, circular dichroism, enzymatic assays and molecular modeling approaches have been performed to extensively characterize the protein form and function. …

Magnetic Nickel Nanoparticles: Synthesis, Environmental Lmplications And Potential Role As Drug Carriers, Setare Tahmasebi Nick

Dissertations

The design and synthesis of well-defined magnetic particles with nanoscale dimensions is opening new avenues in understanding their fundamental chemical and physical properties. Our work describes a novel facile procedure for the synthesis of homogenous isotropic and anisotropic magnetic nickel nanoparticles. These nanoparticles were produced using a wet-chemical process and characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), powder x-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and thermogravimetric analysis (TGA). Magnetic measurements were acquired using a superconducting quantum interference device (SQUID) magnetometer. While there is significant interest in using magnetic nanoparticles for biological …

Ultrafast Interfacial Electron Transfer Across Molecule-Tio2 Nanocomposites: Towards Solar Cells And Two Photon Absorption, Edwin Mghanga

Dissertations

Interfacial charge transfer (ICT) across the molecule-TiO2 nanoparticle interface has gained enormous research attention for applications in dye sensitized solar cells (DSSC), photo-catalysis, water splitting and nonlinear optics. DSSCs are promising clean alternative energy sources. However, current DSSCs suffer from lower efficiencies and higher cost. Better understanding of the ICT processes in DSSCs can help solve these problems. We have used two strategies to understand ICT in the context of DSSCs. Firstly, we used a computationally validated anchor group, acetylacetonate (acac) to bind molecules to the semiconductor surface and facilitate charge separation. Secondly, we used natural dye sensitizers, …

Designed Supramolecular Filamentous Peptides: Balance Of Nanostructure, Cytotoxicity And Antimicrobial Activity, Dawei Xu, Linhai Jiang, Anju Singh, Derek Dustin, Miao Yang, Ling Liu, Reidar Lund, Timothy J. Sellati, He Dong

Chemistry and Biochemistry Faculty Publications

This work demonstrates a design strategy to optimize antimicrobial peptides with an ideal balance of minimal cytotoxicity, enhanced stability, potent cell penetration and effective antimicrobial activity, which hold great promise for the treatment of intracellular microbial infections and potentially systemic anti-infective therapy.

Catechol Oxidation By Ozone And Hydroxyl Radicals At The Air-Water Interface, Elizabeth A. Pillar, Robert C. Camm, Marcelo I. Guzman

Chemistry Faculty Publications

Anthropogenic emissions of aromatic hydrocarbons promptly react with hydroxyl radicals undergoing oxidation to form phenols and polyphenols (e.g., catechol) typically identified in the complex mixture of humic-like substances (HULIS). Because further processing of polyphenols in secondary organic aerosols (SOA) can continue mediated by a mechanism of ozonolysis at interfaces, a better understanding about how these reactions proceed at the air–water interface is needed. This work shows how catechol, a molecular probe of the oxygenated aromatic hydrocarbons present in SOA, can contribute interfacial reactive species that enhance the production of HULIS under atmospheric conditions. Reactive semiquinone radicals are quickly produced upon …

The Detection Of Peroxynitrite Using 19f Magnetic Resonance Probes, Kevin Bruemmer

Collection of Engaged Learning

The following report presents the work done by Kevin Bruemmer for his Engaged Learning project. The 19F magnetic resonance probes 5-uoroisatin and 6-uoroisatin were reacted with ONOO- to yield anthranilic acid derivatives through a novel oxidative decarbonyaltion reaction. Utilizing 19F NMR spectroscopy techniques, the presence of ONOO- can be determined through a chemical shift switching signal. 5-uoroisatin was subsequently used to detect ONOO- in living lung epithelial cells.

Synthesis Of Hydrogenated Thiol-Silanes For Selective Reactions, Macartney Welborn

Collection of Engaged Learning

The intention of this experiment is to show the creation of multifunctional thiols from the reaction between various hydrochlorosilanes and mercaptoethanol in an attempt to utilize their distinct properties for practical applications. Multifunctional thiols have many useful applications including use in high-refractive-index lenses, ¹ heavy metal chelation, ² and degradable plastics³. Previous work, ⁵ in our lab has explored a class of reactions key to the synthesis of these compounds: the reaction between methylated chlorosilanes with mercaptoalcohols. We extended this reaction to include hydrogenated chlorosilanes. This allows us to produce multifunctional thiols with an additional functionalizable position at …

Preliminary Analysis Of Thermal Reactions Of Select Metals With Chalcogens, Elizabeth G. Cook

Student Theses and Dissertations

Metal sulfides and selenides are important industrially as semiconductor materials, pigments, electrochemical cells, solar energy conversion and catalysts. The purpose of this study was to determine if a reaction occurs at elevated temperatures between sulfur and selenium with electropositive metals. Reactions were studied using a TG/DTA instrument. The metals used to react with sulfur were copper, nickel, lead, cobalt, manganese, iron, zinc, and cadmium. For comparison, copper, lead, and nickel were reacted with elemental selenium.

Chemistry Graduate Teaching Assistants' Experiences In Academic Laboratories And Development Of A Teaching Self-Image, Todd Adam Gatlin

USF Tampa Graduate Theses and Dissertations

Graduate teaching assistants (GTAs) play a prominent role in chemistry laboratory instruction at research based universities. They teach almost all undergraduate chemistry laboratory courses. However, their role in laboratory instruction has often been overlooked in educational research. Interest in chemistry GTAs has been placed on training and their perceived expectations, but less attention has been paid to their experiences or their potential benefits from teaching.

This work was designed to investigate GTAs' experiences in and benefits from laboratory instructional environments. This dissertation includes three related studies on GTAs' experiences teaching in general chemistry laboratories. Qualitative methods were used for each …

Evaluation And Application Of Instruments Measuring Spatial Ability And Attitude For College Chemistry Students, Xiaoying Xu

USF Tampa Graduate Theses and Dissertations

Student performance in college chemistry courses remains a concern for educators seeking to help improve the future STEM workforce. Besides math ability and prior chemistry knowledge, spatial ability and attitude toward chemistry have been considered as important factors influencing college chemistry performance. This work includes five studies and uses data collected from instruments to examine the relationships of these two factors - spatial ability and attitude - with student chemistry performance, and provides psychometric evidence for using the Purdue Visualization of Rotations test (ROT) and Attitude toward the Subject of Chemistry Inventory (ASCIv2) to measure these two factors, respectively, in …

Metallopeptides From Design To Catalysis: Structure, Oxidative Activities, And Inhibition Studies Of Designed And Naturally Occurring Metallopeptides, Alaa Hassan Hashim

USF Tampa Graduate Theses and Dissertations

Structural and mechanistic complexities of copper-dioxygen systems have attracted much attention in the field of bioinorganic chemistry, both in model systems and trapped protein intermediates. The research presented herein is focused on model and naturally occurring metallopeptide systems, from its design to catalysis. Copper is used as the coordinating metal ion, with cobalt and zinc as probes for metal binding. The bioinorganic chemistry of copper proteins and its coordination and spectroscopic properties are briefly discussed in chapter 1. The next two chapters are centered on the de novo design of a minimalistic metallopeptide system with an amino acid sequence of …

Co(Ii) Based Metalloradical Catalysis: Carbene And Nitrene Transfer Reactions, Joseph B. Gill

USF Tampa Graduate Theses and Dissertations

Radical chemistry has attracted a large amount of research interest over the last few decades and radical reactions have recently been recognized as powerful tools for organic synthesis. The synthetic applications of radicals have been demonstrated in many fields, including in the synthesis of complex natural products. Radical reactions have a number of inherent synthetic advantages over their ionic counterparts. For example, they typically proceed at fast reaction rates under mild and neutral conditions in a broad spectrum of solvents and show significantly greater functional group tolerance. Furthermore, radical processes have the capability of performing in a cascade fashion, allowing …

Evolution Of Acyl-Substrate Recognition By A Family Of Acyl-Homoserine Lactone Synthases, Quin H. Christensen, Ryan M. Brecht, Dastagiri Dudekula, E. Peter Greenberg, Rajesh Nagarajan

Chemistry and Biochemistry Faculty Publications and Presentations

Members of the LuxI protein family catalyze synthesis of acyl-homoserine lactone (acyl-HSL) quorum sensing signals from S-adenosyl-L-methionine and an acyl thioester. Some LuxI family members prefer acyl-CoA, and others prefer acyl-acyl carrier protein (ACP) as the acyl-thioester substrate. We sought to understand the evolutionary history and mechanisms mediating this substrate preference. Our phylogenetic and motif analysis of the LuxI acyl-HSL synthase family indicates that the acyl-CoA-utilizing enzymes evolved from an acyl-ACP-utilizing ancestor. To further understand how acyl-ACPs and acyl-CoAs are recognized by acyl-HSL synthases we studied BmaI1, an octanoyl-ACP-dependent LuxI family member from Burkholderia mallei, and BjaI, an …

Self-Assembly And Ring-Opening Metathesis Polymerization Of A Bifunctional Carbonate–Stilbene Macrocycle, Yuewen Xu, Weiwei L. Xu, Mark D. Smith, Linda S. Shimizu

Faculty Publications

No abstract provided.

Molecular Approaches To Chromatography Using Single Molecule Spectroscopy, Lydia Kisley

Faculty Scholarship

No abstract provided.

Modification Of A Single-Molecule Afm Probe With Highly Defined Surface Functionality, Fei Long, Bin Cao, Ashok Khanal, Shiyue Fang, Reza Shahbazian-Yassar

Michigan Tech Publications

Single-molecule force spectroscopy with an atomic force microscope has been widely used to study inter- and intramolecular interactions. To obtain data consistent with single molecular events, a well-defined method is critical to limit the number of molecules at the apex of an AFM probe to one or to a few. In this paper, we demonstrate an easy method for single-molecule probe modification by using the Cu-catalyzed alkyne–azide cycloaddition reaction. Excess terminal alkynes were covalently attached to the probe, and a bi-functional molecule containing an azide at one end and a carboxylic acid at the other was dissolved in the reaction …

Facile Electrochemical Synthesis Of Antimicrobial Tio2 Nanotube Arrays, Yu Zhao, Qi Xing, Jagadeesh Janjanam, Kun He, Fei Long, Ke-Bin Low, Ashutosh Tiwari, Feng Zhao, Reza Shahbazian-Yassar, Tolou Shokuhfar

Department of Chemistry Publications

Infection-related complications have been a critical issue for the application of titanium orthopedic implants. The use of Ag nanoparticles offers a potential approach to incorporate antimicrobial properties into the titanium implants. In this work, a novel and simple method was developed for synthesis of Ag (II) oxide deposited TiO₂ nanotubes (TiNTs) using electrochemical anodization followed by Ag electroplating processes in the same electrolyte. The quantities of AgO nanoparticles deposited in TiNT were controlled by selecting different electroplating times and voltages. It was shown that AgO nanoparticles were crystalline and distributed throughout the length of the nanotubes. Inductively coupled plasma …

Synthesis And Formation Mechanism Of Cuins2 Nanocrystals With A Tunable Phase, Chao Yu, Linlin Zhang, Long Tian, Dan Liu, Fanglin Chen, Cheng Wang

Faculty Publications

Chalcopyrite CuInS₂ (CIS) hierarchical structures composed of nanoflakes with a thickness of about 5 nm were synthesized by a facial solvothermal method. The thermodynamically metastable wurtzite phase CIS would be obtained by using InCl₃ instead of In(NO₃)₃ as In precursor. The effects of the In precursor and the volume of concentrated HCl aqueous solution on the phases and morphologies of CIS nanocrystals have been systematically investigated. Experimental results indicated that the obtained phases of CIS nanocrystals were predominantly determined by precursor-induced intermediate products. The photocatalytic properties of chalcopyrite and wurtzite CIS in visible-light-driven degradation of …

The Development Of A Valid And Reliable Biogeochemistry Concept Inventory, Chris Mead

Discipline-Based Education Research Group Speaker Series

Concept inventories are a commonly used tool to measure conceptual understanding. To date, concept inventories have been published for geology, chemistry, and biology, but no instrument has been designed to measure conceptual understanding at the intersection of those fields. To fill that gap, we constructed a 32‐item biogeochemistry concept inventory (BGC‐CI). Item response theory analysis, using the Rasch model, shows the BGC‐CI is a reliable and valid tool to measure the biogeochemistry knowledge of science majors. Because biogeochemistry is an interdisciplinary field, we were concerned about the unidimensionality of the instrument. However, our analysis showed the BGC‐CI to be acceptably …

Mimicking Metabolism Of A Reversed Chloroquine Antimalarial, Kelsie Lynn Kendrick

Dissertations and Theses

The aim of this study was to elucidate the oxidation products of a candidate antimalarial drug, PL69, using a porphyrin system and to determine the accuracy of the oxidation products produced, as compared to what is expected in metabolism. PL69 is a reversed chloroquine (RCQ) that is active against chloroquine resistant malaria. Porphyrin oxidation systems have been shown to mimic in vitro enzymatic metabolism reactions. PL69 and its known metabolite, PL16, were incubated with the porphyrin system, and then the oxidation products were collected and separated by HPLC. The oxidation products were characterized by NMR and mass spectrometry and compared …

Cold Magnetically Trapped 2DG Scandium Atoms. I. Interaction Potential, Tijs Karman, Xi Chu, Gerrit C. Groenenboom

Chemistry and Biochemistry Faculty Publications

We present a first principles description of the interaction of two ground-state scandium atoms. Scandium has a ²D_g ground state. Thirty molecular states correlate to the lowest dissociation limit of the dimer. In the short range, potential energy curves are calculated using second-order n-electron valence state perturbation theory. The first-order long-range interaction is calculated at the complete active space self-consistent field level. We determine the second-order long-range dispersion interaction from atomic dynamic polarizabilities at imaginary frequencies. These polarizabilities are calculated using time-dependent density functional theory. We merge the short-range approach with the long-range model to obtain a physical …