Chemistry Commons^™

Polymorphism And Polyamorphism In Bilayer Water Confined To Slit Nanopore Under High Pressure, Jaeil Bai, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

A distinctive physical property of bulk water is its rich solid-state phase behavior, which includes 15 crystalline (ice I–ice XIV) and at least 3 glassy forms ofwater, namely, low-density amorphous, highdensity amorphous, and very-high-density amorphous (VHDA). Nanoscale confinement adds a new physical variable that can result in a wealth of new quasi-2D phases of ice and amorphous ice. Previous computer simulations have revealed that when water is confined between two flat hydrophobic plates about 7–9 Å apart, numerous bilayer (BL) ices (or polymorphs) can arise [e.g., BL-hexagonal ice (BL-ice I)]. Indeed, growth of the BL-ice I through vapor deposition on …

Molecular Forensic Science Analysis Of Nuclear Materials, Dallas Reilly

UNLV Theses, Dissertations, Professional Papers, and Capstones

Concerns over the proliferation and instances of nuclear material in the environment have increased interest in the expansion of nuclear forensics analysis and attribution programs. A new related field, molecular forensic science (MFS) has helped meet this expansion by applying common scientific analyses to nuclear forensics scenarios. In this work, MFS was applied to three scenarios related to nuclear forensics analysis. In the first, uranium dioxide was synthesized and aged at four sets of static environmental conditions and studied for changes in chemical speciation. The second highlighted the importance of bulk versus particle characterizations by analyzing a heterogeneous industrially prepared …

Sample Preparation Techniques For The Improvement Of Analytical Measurements: Capillary-Channeled Polymer Fibers Employed In Protein Solid Phase Extraction Applications And Characterization Of Active Components In Botanical Dietary Supplements, Carolyn Burdette

All Dissertations

The task of sample preparation encompasses many challenges and demands for analytical techniques. Appropriate preparative steps can be the determining factor between successful measurements and failures. Too little preparation can lead to the inability to detect analytes due to low concentrations, insufficient extraction of analytes, and/or strong matrix effects; exhaustive preparation steps increases analysis times, the potential for analyte losses, and the difficulty to obtain consistent reproducible results. Discussed here are several examples of analytical techniques where sample preparation is critical and can be used to improve existing techniques. Capillary-channeled polymer (C-CP) fibers used for solid phase extraction (SPE) protein …

Fundamental And Applied Studies Of Metal Ion Extraction By Crown Ethers Into Imidazolium-Based Room Temperature Ionic Liquids, Cory Hawkins

Theses and Dissertations

Growing recognition of the extraordinary physicochemical properties and unique solvation environment afforded by ionic liquids (ILs) has drawn increasing attention to these solvents as media for chemical separations. Until recently, little was known about how ionic liquids behave as solvents in this application, particularly in the extraction of ionic solutes such as metal ions. In contrast to the single pathway observed using molecular diluents (i.e., neutral complex extraction), metal ion extraction in these systems has been shown to proceed through as many as three competing pathways over a wide range of conditions. Despite this added complexity, the favorable physicochemical characteristics …

Progress Toward Red And Near-Infrared (Nir) Emitting Saccharide Sensors, Martha Sibrian-Vazquez, Jorge O. Escobedo, Mark Lowry, Robert M. Strongin

Chemistry Faculty Publications and Presentations

Red-shifted and near-infrared (NIR)-active rhodamine analogs and their boronic acid derivatives were synthesized and studied. These latter compounds function as fluorogenic NIR active substrates for sugar sensing. The effects of benzannulation and boronic acid functionalization on fluorophore optical and sensing properties are described.

Electrochemical Detection Of Ammonia In Aqueous Solution Using Fluorescamine: A Comparison Of Fluorometric Versus Voltammetric Analysis, Panchompoo Janjira, G. Compton Richard

Journal of Electrochemistry

Fluorescamine is a non-fluorescent reagent widely used for the quantitative determination of primary amines by fluorescence spectroscopy as it reacts readily with primary amines to form a fluorescent product. In this work, a new sensitive voltammetric method for the detection of ammonia in aqueous solution by the reaction with fluorescamine has been developed. First, the electrochemical behaviour of fluorescamine in the absence and presence of ammonia was investigated in 0.1 mol L^-1 borate buffer solution (pH 9.0) by cyclic voltammetry using a glassy carbon (GC) electrode. As for fluorescamine itself, a well-defined irreversible oxidation peak could be observed at …

The Electrochemical Properties Of 1-Pyrenebutyric Acid/Graphene Composites And Their Application In Glucose Biosensors, Min Wang, Jiong Wang, Fengbin Wang, Xinghua Xia

Journal of Electrochemistry

The electrochemical properties of 1-pyrenebutyric acid/graphene composites (PBA/G) obtained by one-step synthesis via π-π stacking was investigated. The electrochemical impedance titration curve shows the surface charge changes as function of solution pH by using ferricyanide/ferrocyanide redox couple as the probe. An apparent pK_a value is estimated as 6.2 according to the impedance titration curve. In addition, a glucose biosensor was constructed by immobilizing glucose oxidase (GOD) on the surface of PBA/G via covalent interaction. This biosensor shows a linear response to glucose within the concentration up to 5 mmol L^-1 with a detection limit of 0.085 mmol L …

In Situ Pm-Irras Studies Of A Floating Bilayer Lipid Membrane At Au(111) Electrode Surface, Su Zhangfei, Kycia Annia, Jay Leitch J., Lipkowski Jacek

Journal of Electrochemistry

In situ Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) was used to study the structure of a DMPC + cholesterol + GM1 floating bilayer lipid membrane (fBLM) at a Au(111) surface. 1-thio-beta-D-glucose (beta-Tg) was self-assembled onto the Au electrode to increase the overall hydrophilicity of the surface. The fBLM was deposited on the beta-Tg self-assembled monolayer (SAM) using a combination of Langmuir-Blodgett/Langmuir-Schaefer (LB/LS) techniques. The carbohydrate headgroups of the GM1 molecules were physically adsorbed to the beta-Tg SAM forming a water rich cushion between the fBLM and the modified gold substrate. The PM-IRRAS spectra indicate that the DMPC molecules within …

Studies Of Microscopic Scale Strains In Nickel Alloys Resulting From Mechanical And Chemical Forces, Jing Chao

Electronic Thesis and Dissertation Repository

The nickel-based Alloy 600, also known as Inconel 600 has been found to be susceptible to stress corrosion cracking (SCC) in high temperature aqueous environments. Despite extensive research, the mechanisms by which this process occurs remain in question. It is known that SCC results from the simultaneous effects of a chemically corrosive environment and a tensile stress. Many studies have been conducted on the microscopic chemical changes associated with SCC. There have been fewer studies of the microscopic stress/strain process. The main objective of this thesis is to use the new x-ray based diffraction technique – polychromatic x-ray microdiffraction (PXM) …

Ultimate Detectability Of Volatile Organic Compounds: How Much Further Can We Reduce Their Ambient Air Sample Volumes For Analysis?, Ki-Hyun Kim

Ki-Hyun Kim

To understand the ultimately lowest detection range of volatile organic compounds (VOCs) in air, application of a high sensitivity analytical system was investigated by coupling thermal desorption (TD) technique with gas chromatography (GC) and time of flight (TOF) mass spectrometry (MS). The performance of the TD-GC-TOF MS system was evaluated using liquid standards of 19 target VOCs prepared in the range of 35 pg to 2.79 ng per μL. Studies were carried out using both total ion chromatograms (TIC) and extracted ion chromatograms (EIC) mode. EIC mode was used for calibration to reduce background and to improve signal to noise. …

Literature Search On Using Dendrimer Nanoparticles As Drug Delivery Vehicles, Sivateja Kasaraneni

All Capstone Projects

The architectural design of dendrimers, multivalency, well-defined molecular weight and higher degree of branching differentiates them as unique and excellent nanocarriers in therapeutic applications such as drug delivery, gene transfection, tumor therapy, imaging and diagnostics. Nanoparticle drug-delivery systems are well known to increase the stability and selectivity of therapeutic agents. However immunogenicity, reticuloendothelial system uptake, drug leakage, cytotoxicity, hemolytic toxicity, poor aqueous solubility restrict the use of these drug delivery systems. These defects are overcame by surface engineering of the dendrimer molecule.

Drug molecule can be efficiently conjugated or encapsulated into the interior of the dendrimer or physically adsorbed onto …

Quality Assurance Plan Project For Copper Determination Using Flame Atomic Absorption Spectroscopy, Bharath Raparthi

All Capstone Projects

This study developed a method for determination of Copper by flame atomic absorption spectrometry (FAAS) from the soil samples and mine tailings using Perkin Elmer AAnalyst 800 atomic absorption spectrometer. A detailed procedure has been developed with a detection limit of 0.12 mg/L. In the recent decades, pollution from heavy metals has been increased. Copper is one of the trace metals that has a significant impact and carries risk to the human health. Calibration curve was established with working range 0.1 ppm to 5 ppm with a correlation coefficient of 0.9994. Over 50 environmental samples from the historic Copper mining …

A Novel Microfluidic Enrichment Technique For Carbonylated Proteins, Bryant C. Hollins

Doctoral Dissertations

Proteins are the building blocks of cells in living organisms, and are composed of amino acids. The expression of proteins is regulated by the processes of transcription and translation. Proteins undergo post-translational modifications in order to dictate their role physiologically within a cell.

Not all post-translational modifications are beneficial for the protein or the cell. One type of post-translational modification, called carbonylation, irreversibly places a carbonyl group onto an amino acid residue, most commonly proline, lysine, arginine, and threonine. This modification can have severe consequences physiologically, including loss of solubility, loss of function, and protein aggregation.

Carbonylated proteins have commonly …

Quantitative Determination Of Acetylsalicyclic Acid And Acetaminophen By Q-Nmr (Quantitative Nuclear Magnetic Resonance) Technique, Gouthami Kanduri

All Student Theses

The pharmaceutical industry mainly uses chromatographic techniques such as High Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC), to determine the quantity of the active ingredient and other material in the drugs. A large effort goes into developing methods using chromatography techniques. The method development and running HPLC and GC are time consuming. Methods need to be updated as the chromatographic columns and the instruments wear out. On the other hand, Nuclear Magnetic Resonance (NMR) technique is mainly used for qualitative analysis to determine the identity of compounds. However, Proton-NMR technique does provide quantitative information of compounds but to develop …

Project Synthesis Of N Acetyl L Histidine Ethyl Amide And Standard Operating Procedure For Fractional Collector, Maneesha Jakkampudi

All Student Theses

Photo oxidation of proteins leads to the formation of cross links of the amino acids in the proteins and leads to induction of cataracts, photo aging of the skin and in the Photodynamic therapy of tumors.

Oxidation of proteins involves significant modification of particular amino acids residues with consequent photodynamic damage. Studies show that tryptophan, tyrosine and histidine side chains gives rise to semi stable peroxides on exposure to singlet oxygen these oxidized structures are studied with low temperature NMR. These peroxides or species derived from them have been postulated as key intermediates in subsequent reactions such as cross linking …

Evaluation And In Vitro Studies Of Folate Peg Biotin And Other Peg Agents, Syed Zahid Hussain

All Capstone Projects

Folate is a member of vitamin B family and plays an essential role in cell survival by participating in the biosynthesis of nucleic and amino acids. Receptors folic acid are frequently over expressed on epithelial cancer cells. These receptors are believed to serve as a receptor-mediated transport system of folic acid into cancer cells and cells associated with inflammation. Interesting, most normal cells in the body have lower frequency of these receptors. Based on these attributes, folate based drug delivery, imaging systems, and diagnostic systems are in several stages of development worldwide.

In this current project, we have characterized the …

Method For Arsenic Detection In Mine Samples From The Upper Peninsula Of Michigan, Vinay Babu Yalamanchili

All Capstone Projects

Arsenic is the 20th abundant element in the earth crust. High concentrations of Arsenic is seen in mine operating countries which can affect public health and biological environment. This may reach to drinking water through ground or surface run-off water. Long term exposure to arsenic causes cancer of bladder, skin, and lungs. So detecting the amount of arsenic in soil and drinking has been an analytical challenge. Arsenic is found in variety of chemical forms in organic and inorganic compounds which results in chemical and physical interferences in the analysis. Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) was used to measure …

Purification And Analysis Of Folate-Dye Conjugate, Sravya Mothe

All Capstone Projects

Folate receptor has achieved great importance for use in targeted drug delivery and in vitro and in vivo diagnostic assays. Folate receptor (FR) is over expressed on several cancer cell types and activated macrophages, but exists in relatively low abundance on the surface of non-cancerous tissue and non-inflammatory cells. This unique attribute is the hallmark of folate – targeted methodologies allowing the diagnostic agent and/or drug to be ferried to the specific disease sites while preventing “off target” effects in normal tissues. Although several folate-based dyes have been reported, simple and detailed synthetic and purification methods for these conjugates have …

In-Capillary Reduction And Digestion Of Proteins At Nano-Liter Volume Using Capillary Electrophoresis, Thasneen Naina Nazeema

Electronic Thesis and Dissertation Repository

To analyze the proteins present in biological samples several major steps are involved. One of the crucial steps in proteomics has been sample preparation. Prior to mass spectral analysis proteins containing disulfide bonds must be reduced which is followed by digestion. In this work, a novel way of performing protein reduction and digestion at nano-liter volume using capillary electrophoresis is presented. In this work, zone passing CE technique was utilized to analyze the reduction products in CE. After the successful in-capillary reduction, digestion of protein was also performed. A pH mediated stacking was used to bring the reduced protein and …

Ultraviolet Photoinitiated On-Fiber Copolymerization Of Ionic Liquid Sorbent Coatings For Headspace And Direct Immersion Solid-Phase Microextraction, Tien D. Ho, Honglian Yu, William T.S. Cole, Jared L. Anderson

Jared L. Anderson

A high-throughput method for the production of solid-phase microextraction (SPME) sorbent coatings via ultraviolet (UV) photoinitiated copolymerization of ionic liquid (IL) monomers on a fused silica support is described. The copolymerization of monocationic and dicationic IL cross-linkers was performed “on-fiber” using UV initiated free radical polymerization. Mixtures composed of various amounts of the IL cross-linker, UV initiator (DAROCUR 1173), and IL monomer were dip-coated onto an etched and derivatized fused silica support and placed in a high-capacity UV reactor. The method requires no organic dispersive solvent and is much more rapid compared to traditional methods in which polymeric ionic liquid …

Fundamental Studies And Bioanalytical Applications Of Nanostructured-Initiator Mass Spectrometry (Nims), Jin Li

Electronic Thesis and Dissertation Repository

Nanostructured-Initiator Mass Spectrometry (NIMS), which uses ‘initiator’ molecules trapped within a nanostructured material to assist the release and ionization of intact molecules adsorbed on that material's surface upon laser or ion irradiation, is a new soft desorption/ ionization technique with several positive attributes including extraordinarily high detection sensitivities, relatively simple sample preparation protocols, and can be initiated using photon or ion irradiation sources. As result NIMS has a great deal of potential for the ready detection of small molecules from complex biofluids including metabolites, and for tissue imaging.

In the thesis, a variety of nanostructured materials including porous silicon (pSi), …

Analysis Of Adp-Ribosylation And Protein Sample Preparation By Capillary Electrophoresis, Ming Huang

Electronic Thesis and Dissertation Repository

ADP-ribosylation is one of many biologically important protein post-translational modifications (PTMs) that received considerable research interest in the past decade. The first part of this work presents the analysis of ADP-ribosylation, with special focus on the catalytic domain of an enzyme ARTD-10. The application of capillary electrophoresis (CE) is proposed in this work to separate the in vitro enzymatic mono-ADP-ribosylated ARTD-10 catalytic domain and its unmodified form. Another exciting aspect of CE application with growing interest is the sample preparation. The effectiveness and efficiency for in-vial reaction, in-capillary mixed reaction and on-capillary-tip reaction by performing methyl esterification on phophopeptides were …

Investigations Of Zeolite Growth By Atomic Force Microscopy (Afm), Donghan Chen

Electronic Thesis and Dissertation Repository

Zeolites are microporous materials that have been used extensively in various fields. A better understanding on their crystallization process is important for their investigations. Atomic force microscopy (AFM) is a powerful tool for studying the growing traces on the crystal surface, providing information regarding the relation between surface events and framework structure. This thesis mainly focuses on the surface investigation of several zeolites and microporous materials. ZSM-11 single crystals were synthesized under hydrothermal conditions, and their crystallization process was monitored by AFM, PXRD, SEM, and SSNMR. SAPO-34 prepared under both HTS and DGC conditions showed morphological differences that are related …

Electrochemical Sensing Of Guanine And Adenine Based On The Boron-Doped Carbon Nanotubes Modified Electrode, Ya-Lin Xia, Chun-Yan Deng, Juan Xiang

Journal of Electrochemistry

In this work, the boron-doped carbon nanotubes (BCNTs) modified glassy carbon (GC) electrode was simply fabricated, and the electrochemical oxidation behaviors of guanine and adenine at the BCNTs/GC electrode were investigated. Compared with the bare GC and CNTs/GC electrodes, the BCNTs-modified electrode exhibited extraordinary electrocatalytic activity towards the oxidations of guanine and adenine as indicated by the obvious increase in current responses. Moreover, the peak separation between guanine and adenine was large enough for their potential recognition in mixture without any separation or pretreatment. Therefore, the simultaneous determination of guanine and adenine was successfully achieved. The BCNTs/GC electrode showed high …

Electrochemical Immunosensor Based On Polycalconcarboxylic Acid Modified Electrode For The Determination Of Alpha-Fetoprotein, Xiao Lin, Shao-Huang Weng, Jian-Zhang Zhou, Ai-Lin Liu, Xin-Hua Lin, Yong-Ji You

Journal of Electrochemistry

A highly sensitive electrochemical immunosensor based on novel electropolymerized polycalconcarboxylic acid modified electrode (poly-CCA/GC) has been fabricated for the detection of alpha-fetoprotein (AFP). The differences of the poly-CCA/GC electrodes before and after the immobilization of AFP antibody were characterized via scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The immobilization of antibody/antigen/antibody-HRP sandwich was formed on the poly-CCA modified electrode for the determination of special AFP concentrations. The electrochemical signals generated from the HRP which catalyzed the TMB substrate were measured. Experiment results indicated that the developed immunosensor showed a good sensitivity and precision.

Scanning Electrochemical Microscopy Studies Of Nickel Surfaces And T24 Single Live Cells, Yu Sun

Electronic Thesis and Dissertation Repository

Scanning electrochemical microscopy offers a good insight into nickel surface analysis and human bladder cancer cell studies.

The surface microstructures are related with chemical reactivity by superimposing SECM, SEM and Tof-SIMS images together. Depth scans were exploited for studying chemical reactivity quantitatively by comparison with COMSOL simulation results. Simulation models are described.

Extracellular reactive oxygen species are detected by SECM. Quantitative results were demonstrated by simulation, and concentrations of H₂O₂ and O₂ were acquired. The interaction between cancer cells and vitamin C was investigated. The switch-type behaviour of vitamin C on the PMA-induced ROS burst of …

Migration Behaviour Of Discontinuous Buffers In Capillary Electrophoresis During Protein Enrichment, Ting Li

Electronic Thesis and Dissertation Repository

To enrich protein at sub-microliter sample volumes, our group has developed a discontinuous buffer system which consists of an acid and a base inside a capillary. Upon voltage application, the protein moves towards and stacks at the pH junction. Prior to this work, we only focused on the protein enrichment and have not investigated the migration behaviour of various ions in this system. However, it is important to understand the mechanism of the migration of these ions, because the pH junction formation and further the protein enrichment are based on it. In this work, the ion migration patterns at the …

Nontargeted Comprehensive Two-Dimensional Gas Chromatography/Time-Of-Flight Mass Spectrometry Method And Software For Inventorying Persistent And Bioaccumulative Contaminants In Marine Environments, Eunha Hoh, Nathan G. Dodder, Steven J. Lehotay, Kristin C. Pangallo, Christopher M. Reddy, Keith A. Maruya

Kristin Pangallo

Surface Structuring Strategies For Micro-Cantilever Sensing Platforms And Applications For Hydrogen Related Issues, James F. Patton

Doctoral Dissertations

Recent developments in microelectro-mechanical systems have enabled the exploration of transduction modes that involve mechanical energy and are based primarily on mechanical phenomena. As a result an innovative family of chemical and biological sensors has emerged which utilize a transducer in the form of microcantilevers (MCs). MCs offer greater sensitivity than comparable mass-responding sensors due in large part to their small dimension. These low cost devices can be deployed for remote testing, providing real-time information for the analyst. An additional advantage is the ability to employ MCs in an arrayed fashion adding a unique selectivity not available to many sensing …

New Approaches To Electroanalysis Of Metals And Pretreatment Of Biological And Environmental Samples, Stefanie Bragg

Doctoral Dissertations

Biological and environmental sample pretreatment followed by electrochemical sensing are the focus of this dissertation. The Advanced Oxidation Process (AOP) treatment using aqueous hydrogen peroxide and UV irradiation with acid deactivation of the enzyme catalase in blood has been developed and optimized. The kinetics of whole blood AOP in a single-cell reactor was studied, and the effect of pH on the AOP process has been investigated. A new method of dry ashing whole blood has been developed and optimized for trace metal analyses. The new method and subsequent metal analyses in the blood samples has been used to confirm results …