Physical Sciences and Mathematics Commons^™

Developing A Presumptive Test For Select Synthetic Cannabinoids, Carrie Snyder

Graduate Theses and Dissertations

Synthetic cannabinoids (SC's) began to gain popularity around the world in 2009. Since then, many of the compounds have been outlawed and methods developed to detect them and their metabolites using mass spectrometry. Our work investigated the possibility of developing a colorimetric presumptive test. The SC JWH-019 was synthesized and its ketone targeted as a possible reaction site. Many SC's contain ketones and thus a reaction at this site would be applicable to many of the compounds. Since JWH-019 is costly and time consuming to synthesize, much of the experimental work was done using benzophenone (BP). BP contains a diaryl …

Fabrication Of Tungsten Tips Suitable For Scanning Probe Microscopy By Electrochemical Etching Methods, Gobind Basnet

Graduate Theses and Dissertations

The fabrication of metal tips is becoming an interesting field for scientists who are working in spectroscopy measurements. A significant amount of work has already been done in the tips fabrication process. Metal tips used to analyze the surface of materials play a key role in the scanning tunneling microscope (STM) technique. It's remarkable quality that it is used to study the surface of material at the atomic level.

There are various methods used in the tips fabrication process. Of diverse methods, three different electrochemical etching methods: submerged method, single lamella drop-off method, and double lamella drop-off method are commonly …

Modeling Chemical Reactions In Aqueous Solutions, Osman Uner

Graduate Theses and Dissertations

The energy barriers for SN2 ligand exchange reactions between the chloride anion and para-substituted benzyl chlorides were investigated both in water solution and in the gas phase by using quantum chemical simulations at the DFT and Hartree-Fock levels. The question addressed was the effect of the solvent (water) and of the substituent on the barrier height. The para substitutient groups included NH2, OH, OCH3, CH3, C(CH3)3, H, F, Cl, Br, I, CF3, CN, NO2, and SO3- . The calculations in aqueous solution were carried out with the recently developed Ultrafast Monte Carlo method using the TIP3P explicit water model. The …

Synthesis Of Platinum And Platinum-Copper Branched Nanoparticles For Electrooxidation Of Methanol, Eric Courtland Taylor

Graduate Theses and Dissertations

Platinum and Pt alloys are among the most important heterogeneous catalysts for many organic reactions and electrochemical reactions associated with the fuel cell technologies. How to reduce Pt usage while maintaining the performance of the catalysts becomes a subject for intensive research in materials chemistry. For heterogeneous catalysis, the catalytic reactivity and selectivity are strongly correlated with different crystallographic facets exposed on the surface. The facets with high-index planes whose Miller indices with at one is larger than unity are generally more active than those with low-index planes (e.g., {100}, {111}, and {110}). Tuning the morphology of the nanoparticles to …

Optimization Of Sample Preparation In Matrix-Assisted Laser Desorption/Ionization (Maldi) Mass Spectrometry Of Macromolecules, Evgenia Akhmetova

Graduate Theses and Dissertations

New method for the matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) and Fourier transform mass spectrometry (MALDI-FTMS) analysis of low molecular weight polyvinyl acetate (PVAc) was developed and then applied to the characterization of commercially available chewing gum. The optimization of MALDI analysis of PVAc was achieved by investigating the influence of sample preparation variables such as the choice of solvent and choice of matrix-analyte ratio. It was demonstrated that the use of ethyl acetate as a solvent and 2,5-Dihydroxybenzoic acid as a matrix yielded the highest signal intensity for the pure polymer sample. The application of TOF technique did not …

New Effects Of Aging And Lattice Intercalation On Surface Properties Of Titanate Nanobelts, Roger Williams

Graduate Theses and Dissertations

Titanate nanobelts (NBs) have structural characteristics beyond that of clays. Due to a negatively charged lattice matrix of edge-shared TiO6-octahedra, the location of intercalated cations within the interlayer space may dictate the charge-conductions. This environment may in turn govern the lattice-framework's stability and surface properties, based upon our preliminary

data.

On that basis, these nanomaterials have been found in our lab to possess superb biological compatibility that is closely related to the types of the intercalated cations. In addition, a prolonged agitation was proven to enable us to manipulate the titanate NBs' length. In a parallel study, a ripening was …

On Chlorine Salts: Their Detection, Stability And Implications For Water On Mars And Europa, Jennifer Hanley

Graduate Theses and Dissertations

Chlorine salts (e.g. chlorides, chlorates and perchlorates) are an important factor in the stability of water on the surfaces of planetary bodies. Here we have shown that perchlorate and chlorate salts will lower the freezing point of water, allowing it to be liquid down to ~204 K. These salts will also slow down the evaporation rate, extending the lifetime of the liquid water solution. Chlorine salts have been detected on Mars, which has significant implications for the stability of water and hence its habitability. To study their effects on the stability of water on planetary surfaces, we need to first …

An Investigation Of The Electronic Coupling In Some Dimeric Ruthenium (Ii) Polypyridine Complexes, Roland Ngebichie Njabon

Graduate Theses and Dissertations

A detailed understanding of respiration at the molecular level requires an understanding of the many electron transfer steps involved in the process. These electron transfer processes are extremely fast and are impossible to measure by simple rapid mixing techniques. In order to get around this problem, scientists have used laser flash photolysis. This technique relies on the fact that under proper conditions, a reactant can be generated by a very short laser pulse. Once generated, the course of the reaction can be monitored by various techniques capable of very rapid time response. Many applications of this methodology rely on the …

Further Studies On The Allylic Diazene Rearrangement, Maha Laxmi Shrestha

Graduate Theses and Dissertations

Former graduate student Wei Qi and Professor Matt McIntosh have reported diastereoselective reductive 1,3-transpositions of acyclic alpha, beta-unsaturated tosyl hydrazones to afford substrates with a 1,4-syn or 1,4-anti relationship between alkoxy and methyl groups that proceed via an ADR (Qi, W.; McIntosh, M. C. Org. Lett. 2008, 10, 357; Qi, W.; McIntosh, M. C. Tetrahedron 2008, 64, 7021). In these reports, silica gel was employed to accelerate the reduction. We have found that acetic acid gives the same results with high diastereoselectivity in the reaction. We further optimized the reaction by lowering the amount of catecholborane to 3 eq. Effects …

Wave Profile For Current Bearing Antiforce Waves, H. Morris, W. Childs, P. Pinkston, M. Hemmati, J. Christensen

Journal of the Arkansas Academy of Science

For fluid dynamical analysis of breakdown waves, we employ a one-dimensional, three-component (electrons, ions and neutral particles) fluid model to describe a steady-state, ionizing wave propagating counter to strong electric fields. The electron gas temperature and therefore the electron fluid pressure is assumed to be large enough to sustain the wave motion down the discharge tube. Such waves are referred to as antiforce waves. The complete set of equations describing such waves consists of the equations of conservation of mass, momentum and energy coupled with Poisson’s equation. Inclusion of current behind the wave front alters the set of electron fluid …

Microwave Assisted Synthesis Of Chloropentahaptocyclopentadienediphenylphosphinoethaneruthenium(Ii), S. Muthyala, Mark Draganjac

Journal of the Arkansas Academy of Science

No abstract provided.

Molecular Structure Of Pentahaptocyclopentadienebis (Tetrahydrothiophene) Triphenylphosphineruthenium(Ii) Triflate, Paul M. Nave, Mark Draganjac, A. W. Cordes

Journal of the Arkansas Academy of Science

No abstract provided.

New Applications Of Mass Spectrometry For Drug And Lipid Analysis, Elizabeth Lauren Emerson

Graduate Theses and Dissertations

Mass spectrometry is an important tool used in many different disciplines and settings that include forensics, drug discovery, environmental analysis, and proteomics. Gas chromatography - mass spectrometry (GC-MS) and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI - TOF MS) are two of the most important instruments used for analysis of compounds. Chapters 1 and 2 of this discussion use GC-MS for the investigation of synthetic cannabinoids in `K2' incense products and the detection of metabolites in urine samples from individuals suspected of consuming these mixtures. Analytical standards were synthesized and used for identification and confirmation of structures. Detection of …

Refractive Index Chemical Sensing With Noble Metal Nanoparticles, Phillip Blake

Graduate Theses and Dissertations

Chemical sensing is a key component in modern society, especially in engineering applications. Because of their widespread impact, improvements to chemical sensors are a significant area of research. One class of sensors, plasmonic sensors, is being heavily researched because of their ability to detect low levels of analyte in near real time without destroying the analyte. This work studies a new class of plasmonic sensor that utilizes diffractive coupling to improve sensor performance. Specifically, this work outlines the first study of diffractive coupling sensors with typical nanoparticle shapes. Sensitivity of this new class of sensor is directly compared to typical …

Part I - A Study Of The Formation Of Carbenes By Elimination Of Α-Bromosilanes And Application Toward The Synthesis Of Transition Metal Complexed Quinone Methide Analogs. Part Ii - Development Of Novel 7-Membered Ring Carbene Ligands For Palladium Catalyzed Cross Coupling Reactions., Christian Michael Loeschel

Graduate Theses and Dissertations

In part I, we wish to report our approaches toward transition metal complexed ortho-quinone methide analogs. ortho-Quinone Methides are a class of highly reactive compounds with a wide range of chemical and biological applications. Previously, a stable iron complexed benzannulated 5-membered ring quinone methide analog was reported by Allison and Neal27. Herein, we report our approaches to improve the reactivity of that system by removing benzannulation as well as changing the metal from iron to manganese and rhenium.

Furthermore, a methodological study on generating carbenes under mild conditions by elimination of α-halosilanes and its application towards metal complexed quinone methide …

Semiconductor Nanocrystals: From Quantum Dots To Quantum Disks, Zheng Li

Graduate Theses and Dissertations

The bottom-up colloidal synthesis opened up the possibility of finely tuning and tailoring the semiconductor nanocrystals. Numerous recipes were developed for the preparation of colloidal semiconductor nanocrystals, especially the traditional quantum dots. However, due to the lack of thorough understanding to those systems, the synthesis chemistry is still on the empirical level. CdS quantum dots synthesis in non-coordinating solvent were taken as a model system to investigate its molecular mechanism and formation process, ODE was identified as the reducing agent for the preparation of CdS nanocrystals, non-injection and low-temperature synthesis methods developed. In this model system, we not only proved …

Studies Toward The Total Synthesis Of Antascomicin B, David Ross Clay

Graduate Theses and Dissertations

The following dissertation describes synthetic efforts toward the synthesis of the C21-C34 fragment of antascomicin B. Our initial enzymatic approach is detailed as well as an asymmetric transfer hydrogenation (ATH) strategy that will be used in the eventual total synthesis of the molecule. Several investigations into anomalies observed during (ATH) reactions are also discussed.

Cross-Linked Pdms Expansion Due To Submersion In Liquid And Supercritical Co2, Teng Yang

Graduate Theses and Dissertations

Characterization of micro/nano-copper particles impregnated Polydimethylsiloxane (PDMS) submersed in supercritical carbon dioxide (scCO2) was studied. The purpose of this investigation was to advance micro-corrosion sensor technology utilizing PDMS and micro-metal particle composite as the sensing element currently under-development. One of the key challenges encountered was the removal of the native oxides inherently existing on the metal particles. Numerous techniques were experimented with to counter this problem at the UA Engineered Micro/Nano Systems Laboratory (EMNSL), with swell-based protocols being identified as the most promising solution. In terms of compatibility to Micro-electro-mechanical Systems (MEMS) fabrication, CO2 is often used in the release …

Studies Toward The Development Of A Microelectrode Array For Detection Of Dopamine Through Redox Cycling, Anupama Aggarwal

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that cycles the reversible redox species between its oxidative states repeatedly on generator and collector electrodes. Two or more individually-addressable microelectrodes located close to each other allow redox cycling to be possible. Electrochemical behavior of a biologically important molecule, dopamine is examined under redox cycling conditions. To our knowledge, this is the first report on detection of physiological concentration of dopamine in presence of up to 100 times excess ascorbate with the use of redox cycling, without the involvement of polymer coating such as Nafion®.

Microfabrication was used to produce different geometries (parallel bands …

Visualizing The Spatial Localization Of Active Matrix Metalloproteinases (Mmps) Using Maldi Imaging Ms, Sasirekha Muruganantham

Graduate Theses and Dissertations

Biomaterial implantation induces the foreign body response (FBR). Development of longer-term implants relies on the thorough understanding of the FBR. The progression of the FBR is regulated by a number of biomolecules including cytokines, chemokines, and matrix metalloproteinases (MMPs). The nature of the FBR requires the spatial and temporal regulation of these mediators. MMPs are an extremely large and diverse group of enzymes that play key roles in regulating the FBR. Precise spatiotemporal regulation of MMPs defines their proteolytic activities. The aim of this project is to develop a new bioanalytical method to visualize the localization of active MMPs at …

The Design, Synthesis And Application Of A Novel Class Of N-Heterocyclic Carbene Catalysts, Abigail Lynn Hubbard

Graduate Theses and Dissertations

A copper carbenoid representative of a novel class of N-heterocyclic carbene (NHC) catalysts has been synthesized. This compound was characterized by X-ray crystallography and was found to confirm the rationale of our synthetic design: The C2-symmetric structure places four stereocenters in close proximity (<5Å) to the reactive site of the carbene via a trans-annular gearing effect. The copper carbenoid was found to catalyze the hydrosilylation of prochiral ketones with superb selectivity in high yield.

Dynamics And Catalytic Resolution Of Selected Chiral Organolithiums, Timothy Kum Beng

Graduate Theses and Dissertations

One of the most important developments of the last decade has been the emergence of new methods to dynamically resolve racemic organolithiums using stoichiometric amounts of the chiral ligand. When this concept is implemented successfully, it obviates the need for covalently attached chiral auxiliary based methods, asymmetric deprotonation, and asymmetric synthesis of a precursor stannane as ways to access enantioenriched organolithium compounds for use in asymmetric synthesis. Since certain electrophiles consume the chiral ligand, it is desirable to render this process catalytic in the chiral ligand.

As part of a larger study on the amenability of chiral organolithiums to a …

Review Of Science For Science Librarians: Graphene, Kathleen A. Lehman

University Libraries Faculty Publications and Presentations

Graphene is, in many ways, a simple substance. Made of a single atomic layer of graphite, graphene has emerged as a material providing many surprises and having immense scientific and industrial potential. In 2010, scientists Andre K. Geim and Konstantin S. Novoselov received the Nobel Prize in Physics for their isolation of graphene and for their research pertaining to the ultrathin material. In his presentation speech, Professor Per Delsing described how we all have made graphene each time we write with a pencil: microscopic bits of graphite and graphene flake away as the pencil moves across the paper (Delsing 2010). …

Symmetry-Based Techniques For Qualitative Understanding Of Rovibrational Effects In Spherical-Top Molecular Spectra And Dynamics, Justin Chadwick Mitchell

Graduate Theses and Dissertations

Using light to probe the structure of matter is as natural as opening our eyes. Modern physics and chemistry have turned this art into a rich science, measuring the delicate interactions possible at the molecular level.

Perhaps the most commonly used tool in computational spectroscopy is that of matrix diagonalization. While this is invaluable for calculating everything from molecular structure and energy levels to dipole moments and dynamics, the process of numerical diagonalization is an opaque one. This work applies symmetry and semi-classical techniques to elucidate numerical spectral analysis for high-symmetry molecules.

Semi-classical techniques, such as the Potential Energy Surfaces, …

Protein-Lipid Interactions: Influence Of Anchoring Groups And Buried Arginine On The Properties Of Membrane-Spanning Peptides, Vitaly V. Vostrikov

Graduate Theses and Dissertations

Designed transmembrane peptides were employed for investigations of protein-lipid interactions by means of oriented solid-state deuterium NMR spectroscopy using isotope-enriched alanine residues. Using the model GWALP23 sequence (GGALW(LA)6LWLAGA) as a host peptide having single interfacial tryptophan anchor residues, the effects of different guest mutations were explored. Replacements of glycine residues 2 and 22 to positively charged lysine or arginine on both termini had little influence on the peptide average orientation. Conversely, glycine to tryptophan substitutions had profound effects, manifested in the increased dynamics and altered tilt direction of the peptide. While the charged residues at the peptide termini did not …

New Interfacial Nanochemistry On Sensory Bioscaffold-Membranes Of Nanobelts, Feng Chen

Graduate Theses and Dissertations

Nanostructured bioscaffolds and biosensors are evolving as popular and powerful tools in life science and biotechnology, due to the possible control of their surface and structural properties at the nm-scale. Being seldom discussed in literature and long-underexploited in materials and biomedical sciences, development of nanofiber-based sensory bioscaffolds has great promises and grand challenges in finding an ideal platform for low-cost quantifications of biological and chemical species in real-time, label-free, and ultrasensitive fashion. In this study, titanate nanobelts were first of all synthesized, from hydrothermal reactions of a NaOH (or KOH solution) with TiO2 powder, to possess underexploited structure and surface …

Synthesis, Characterization, And Properties Of Homometallic Dinuclear Ruthenium Complex Containing Chloro-Phenanthroline And Bipyridine, A. A. Bhuiyan, S. Kudo

Journal of the Arkansas Academy of Science

This paper deals with the synthesis and spectroscopic investigation of homometallic dinuclear ruthenium(II) complex containing chlorophenanthroline and bipyridine ligands. This bimetallic ruthenium polypyridine complex may be useful for biological electron transfer studies. Heteroleptic ruthenium monomer complex Ru(bpy)2(Cl-phen) (where bpy = 2,2’-bipyridine and Cl-phen = 5-chloro- 1,10-phenanthroline) was prepared in a two step procedure previously developed in our laboratory. This monomer complex was used to prepare the ruthenium dimer complex, (bpy)2Ru(phen-phen)Ru(bpy)2, by utilizing the Ni-catalyzed coupling reaction. Both the complexes were purified by column chromatography. The identity and the integrity of the complexes were confirmed by elemental analysis as well as …

Redox-Magnetohydrodynamic (Mhd) Microfluidics: Fundamentals, Optimization, And Applications To Analytical Chemistry, Melissa Christine Weston

Graduate Theses and Dissertations

Microfluidic systems are of great interest in analytical chemistry for the development of lab-on-a-chip devices. This dissertation describes fundamental investigations of magnetohydrodynamics with added redox species (redox-MHD) as a new microfluidic approach for use in analytical applications. Redox-MHD is attractive because it offers a unique combination of desirable features that are otherwise only available separately with individual micropumps. Redox-MHD is compatible with aqueous and nonaqueous solutions, does not require moving parts, easily reverses flow direction, and requires only low voltages. An ion flux is generated from the oxidation or reduction of an electroactive species at specific locations by activated electrodes …

Molecular Structure Of Fac-Aquadichlorotris(Dimethylsulfoxide)Ruthenium(Ii), L. Foster, J. Hardin, Mark Draganjac, B. C. Noll

Journal of the Arkansas Academy of Science

No abstract provided.

Factors Affecting Redox Magnetohydrodynamics For Flow In Small Volumes, Matthew D. Gerner

Graduate Theses and Dissertations

Lab-on-a-chip technologies offer the possibility of developing analytical devices that are low-cost, portable, disposable, fast, and operable by non-technical personnel. Such devices require automated methods to manipulate ultra-small volumes (picoliters) of samples and solution, including pumping, stirring, and positioning. Current methods for ultra-small volume microfluidics have limitations that restrict their use including high voltage requirements, disadvantageous flow profiles or rates, and relatively complicated fabrication due to mechanical parts. Redox magnetohydrodyanmics (RMHD) that utilizes permanent magnets for portability shows promise as a micropump with ease of switching flow direction, no moving parts, compatibility with both aqueous and non-aqueous solutions, low voltages …