Physical Sciences and Mathematics Commons^™

Impact Of Post-Synthesis Modification Of Nanoporous Organic Frameworks On Selective Carbon Dioxide Capture, Timur İslamoğlu

Theses and Dissertations

Porous organic polymers containing nitrogen-rich building units are among the most promising materials for selective CO2 capture and separation applications that impact the environment and the quality of methane and hydrogen fuels. The work described herein describes post-synthesis modification of Nanoporous Organic Frameworks (NPOFs) and its impact on gas storage and selective CO2 capture. The synthesis of NPOF-4 was accomplished via a catalysed cyclotrimerization reaction of 1,3,5,7-tetrakis(4-acetylphenyl)adamantane in Ethanol/Xylenes mixture using SiCl4 as a catalyst. NPOF-4 is microporous and has high surface area (SABET = 1249 m2 g-1). Post-synthesis modification of NPOF-4 by nitration afforded (NPOF-4-NO2) and subsequent reduction resulted …

Microfluidic Devices With Integrated Sample Preparation For Improved Analysis Of Protein Biomarkers, Pamela Nsang Nge

Theses and Dissertations

Biomarkers present a non-invasive means of detecting cancer because they can be obtained from body fluids. They can also be used for prognosis and assessing response to treatment. To limit interferences it is essential to pretreat biological samples before analysis. Sample preparation methods include extraction of analyte from an unsuitable matrix, purification, concentration or dilution and labeling. The many advantages offered by microfluidics include portability, speed, automation and integration. Because of the difficulties encountered in integrating this step in microfluidic devices most sample preparation methods are often carried out off-chip. In the fabrication of micro-total analysis systems it is important …

Acid-Base Catalysis In Proton-Coupled Electron Transfer Reactions (Pcet): The Effects Of Brönsted Bases On The Oxidation Of Glutathione And Hydroquinone, Ramos Jonnathan Medina

Theses and Dissertations

This thesis presents the results and discussion of the investigation of the effects of Brönsted bases on the kinetics and thermodynamics of two proton-coupled electron transfer processes: the mediated oxidation of glutathione and the electrochemical oxidation of hydroquinone. Proton-coupled electron transfer (PCET) is the name given to reactions that involve the transfer of electron(s) accompanied by the exchange of proton(s). PCETs are found in many chemical and biological processes, some of current technological relevance such as the oxygen reduction reaction in fuel cells, which involves the transfer of four electrons and four protons (4e-, 4H+); or the splitting of water …

Part 1. Design And Synthesis Of Cysteine/Cystine Prodrugs And Bioisosteres Including Symmetrical And Unsymmetrical Disulfides Designed To Increase Cystine Levels In The Cns In Order To Drive The Cystine/Glutamate Antiporter: A Novel Treatment For Schizophrenia And Drug Addiction. Part 2. Design And Synthesis Of Subtype Selective Ester Bioisosteres Of Bzr Ligands For Gabaa/Benzodiazepine Receptors To Enhance Metabolic Stability, Edward Merle Johnson Ii

Theses and Dissertations

Part 1. Schizophrenia is a debilitating disorder that affects almost 1% of the world's population; pharmacotherapy expenditures for this disorder exceed $10 billion dollars even though existing medications exhibit a poor safety/efficacy profile. It is estimated that 75% of patients discontinue drug treatment, in part due to poor safety/efficacy. The current data set demonstrates that cysteine prodrug NAC reverse the behavioral and neurochemical effects of PCP used to model schizophrenia.

As a result cysteine prodrugs represent a highly novel approach to treating schizophrenia; indeed, these compounds may ultimately be more effective than existing medications because these drugs target the pathology …

Mitochondrial Targeting In Photodynamic Therapy. Metabolic And Drug Structure Requirements For Specific Mitochondrial Localization. A Pilot Investigation, Melissa Rhea Pergande

Theses and Dissertations

Photodynamic therapy (PTD) has shown promise in the treatment of certain types of cancer (Davis et al. 1985, Chen 1988). One appealing strategy under consideration to selectively target tumor cells in PDT is that of mitochondrial targeting (Chen 1988, Chen 1989). The concept of mitochondrial targeting has its origin in the pioneering observation by Chen and colleagues that an enhanced mitochondrial transmembrane potential (ΔΨmito) is a prevalent tumor cell phenotype (Davis et al. 1985, Chen 1988). Because the plasma transmembrane potential is negative on the inner side of the cell, and the mitochondrial transmembrane potential is negative on the matrix …

The Measure And Instruction Of Scale In Introductory Chemistry, Karrie Linn Gerlach

Theses and Dissertations

As a student, it is fundamental to comprehend how small an atom or molecule is in order to truly understand how the world works. The American Association for the Advancement of Science (AAAS) has determined that scale is a critical theme that pervades through all areas of science and is critical to a deep understanding. This project determined that students, which are more proficient with scale and moving between the macroscopic and particle worlds, were better performers in chemistry classes. Interviews were used to determine what the students understood and what common misconceptions were present. These lead to the development …

Part I. The First Enantiospecific, Stereospecific Total Synthesis Of The Indole Alkaloid Ervincidine. Part Ii. The Synthesis Of Alpha 5 Subtype Selective Ligands For Gaba(A) /Benzodiazepine Receptors, Sundari K. Rallapalli

Theses and Dissertations

Part I. The first enantiospecific, stereospecific total synthesis of ervincidine 89 has been accomplished from commercially available D-(+)-tryptophan 37 which has served both as the chiral auxiliary and the starting material. Moreover, this is the first synthesis which unequivocally sets the stereochemistry of the hydroxyl group at C-6 in sterospecific fashion, as well as the C-16 hydroxy methyl group. The stereospecific conversion of D-(+)-tryptophan 37 into the key template (−)-Na-H, Nb-benzyl tetracyclic ketone 49 via the asymmetric Pictet-Spengler reaction (600 gram scale) and Dieckmann cyclization on multi-hundred gram scale was reduced to only two reaction vessels. The optically active tetracyclic …

Rapid Knowledge Assessment (Rka): Assessing Students Content Knowledge Through Rapid, In Class Assessment Of Expertise, Erin Margaret O'Connell

Theses and Dissertations

Understanding how students go about problem solving in chemistry lends many possible advantages for interventions in teaching strategies for the college classroom. The work presented here is the development of an in-classroom, real-time, formative instrument to assess student expertise in chemistry with the purpose of developing classroom interventions. The development of appropriate interventions requires the understanding of how students go about starting to solve tasks presented to them, what their mental effort (load on working memory) is, and whether or not their performance was accurate. To measure this, the Rapid Knowledge Assessment (RKA) instrument uses clickers (handheld electronic instruments for …

Structure And Chemistry Of Model Catalysts In Ultrahigh Vacuum, Joshua D. Walker

Theses and Dissertations

The study of catalysis is a key area of focus not only in the industrial sector but also in the nature and biological systems. The market for catalysis is a multi-billion dollar industry. Many of the materials and products we use on a daily basis are formed through a catalytic process. The quest to understanding and improving catalytic mechanisms is ongoing. Many model catalysts use transition metals as a support for chemical reactions to take place due to their selectivity and activity. Palladium, gold, and copper metals are studied in this work and show the ability to be catalytically reactive. …

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 …

Microfabrication, Characterization, And Application Of Carbon Nanotube Templated Thin Layer Chromatography Plates, And Functionalization Of Porous Graphitic Carbon, David S. Jensen

Theses and Dissertations

This dissertation contains the following sections. Chapter 1 contains a detailed description of the theory of thin layer chromatography (TLC). Chapter 2 describes the benefits and practical considerations of elevated temperatures in liquid chromatography (LC). The porous graphitic carbon (PGC) I modified as part of my work is often used in elevated temperature LC. Chapter 3 shows a thermodynamic analysis of chromatographic retention at elevated temperature, and Chapter 4 contains a closer look at the van 't Hoff equation in LC and how it can be used in retention modeling. In Chapter 5, I describe a new procedure for microfabricating …

Deposition And Characterization Of Hydrophobic Coatings, Vipul Gupta

Theses and Dissertations

Hydrophobic coatings find application in various sectors of the economy including to electronics, textiles, optical devices, and in scientific and commercial equipment. These different applications demand that different hydrophobic coatings posses a range of properties that may include smoothness or roughness, thicknesses on the order of a monolayer or a micron, robustness or the ability to dissolve quickly, transparency or opacity, water resistance or water permeability, electrical conductivity, oleophobicity, etc. However, whatever the final/desired properties, deposition via dry-deposition processes offers significant advantages, including greater reproducibility, increased environmental friendliness, and cost effectiveness on an industrial scale. Herein I explore the chemical …

Investigations Into Background Correction And Retention Time Alignment To Enhance Quantitative Chemometric Analysis Of Comprehensive Two-Dimensional Liquid Chromatography-Diode Array Detection Data, Robert Allen

Theses and Dissertations

The focus of the projects presented here was to develop possible solutions to three issues commonly encountered during chemometric analysis of comprehensive two-dimensional liquid chromatography diode array detector (LCxLC-DAD) data. The focus of the first project was to determine a means of performing background correction that removed two background ridges. The methods of simply subtracting out a mean blank sample, singular value decomposition based background correction (SVD-BC) and asymmetrically weighted least squares (AWLS) were compared. AWLS was found to be the only background correction technique to fully remove the ridges. However, AWLS was also found to attenuate the peak intensity …

Mechanism Of Action Studies On A New Class Of Anticancer Nucleosides, Megan E. Browning

Theses and Dissertations

We have completed mechanism of action studies on a new class of anticancer nucleosides typified by a novel nucleoside discovered in our lab, MAP-870. In order to study the mechanism of MAP-870, several experiments were completed on a colorectal adenocarcinoma cell line, HT-29, including trypan blue cell count, sulforhodamine B assays, flow cytometry of cell cycle, propidium iodide incorporation, and phosphatidylserine externalization, Caspase-Glo3/7 assays, DNA fragmentation gel, cyclophilin A release gel, PAMPA, and confocal imaging. Sulforhodamine B assays show that MAP-870 does indeed cause growth inhibition and cell death in the model tested. PAMPA assays show that MAP-870 does not …

Chemometric Analysis Of Comprehensive Two-Dimensional Liquid Chromatographic-Diode Array Detection Data: Peak Resolution, Quantification And Rapid Screening, Hope P. Bailey

Theses and Dissertations

This research project sought to explore, compare and develop chemometric methods with the goal of resolving chromatographically overlapped peaks though the use of spectral information gained from the four-way data sets associated with comprehensive two-dimensional liquid chromatography with diode array detection (LC ´ LC-DAD). A chemometric method combining iterative key set factor analysis (IKSFA) and multivariate curve resolution-alternating least squares (MCR-ALS) was developed. In the section of urine data analyzed, over 50 peaks were found, with 18 visually observable and 32 additional compounds found only after application of the chemometric method. Upon successful chemometric resolution of chromatographically overlapped peaks, accurate …

Mass Spectroscopic Identification And Quantification Of Protein Carbonyls, Zafer Ugur

Theses and Dissertations

It is well established that free radical mediated oxidative stress plays a critical role in aging and age-related diseases. Among the post-translational protein modifications, carbonylation has attracted a great deal of attention due to its irreversible and irreparable nature. Despite the fact that protein carbonylation is associated with a series of physiological and pathological processes, there are still issues to be clarified such as why certain proteins are more vulnerable to modification, what are the locations of the protein modifications, and how does the nature of the oxidant affect the preferred site of modification. In this study, we will seek …

Gas Phase Characterization Of Supramolecules Using Cross-Sectional Areas By Fticr And Sustained Off-Resonance Irradiation Collision Induced Dissociation Techniques In A Fourier Transform Ion Cyclotron Resonance Mass Spectrometer, Fan Yang

Theses and Dissertations

In my dissertation, I use a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FTICR-MS) to investigate supramolecules. Cross-sectional areas by Fourier transform ICR (CRAFTI), a novel technique for measurements of collision cross sections by FTICR, is demonstrated for the first time. The CRAFTI method measures the total "dephasing cross section" for removal of the ions from the coherent packet in the FTICR cell, including contributions not only from momentum transfer but also from reactive collisions including those leading to collisional dissociation. Experimental CRAFTI collision cross sections correlate linearly with theoretically computed results and with results obtained using ion mobility measurements. …

Multiple Recoding Mechanisms Produce Cyclooxygenase And Cyclooxygenase-Related Proteins From Frameshift-Containing Cox-3/Cox-1b Transcripts In Rat And Human, John Cameron Hunter

Theses and Dissertations

To increase diversity of enzymes and proteins, cells mix and match exonic and intronic regions retained in mature mRNAs by alternative splicing. An estimated 94% of all multi-exon genes express one or more alternatively spliced transcripts generating proteins with similar or modified functions. Cyclooxygenase is a signaling enzyme that catalyzes the rate-limiting step in the synthesis of diverse bioactive lipids termed prostaglandins. Prostaglandins are involved in myriad physiological and pathopysiological processes including vasoregulation, stomach mucosal maintenance, parturition, pain, fever, inflammation, neoplasia and angiogenesis and are inhibited by aspirin-like drugs known as NSAIDs. In 2002 an alternatively spliced, intron-1 retaining variant …

Flow Valve Diagnostics For Label-Free, Quantitative Biomarker Detection: Device Fabrication, Surface Modification, And Testing, Danielle Scarlet Mansfield

Theses and Dissertations

Diseases are often diagnosed by detection of disease-specific biomarkers in fluid samples. However, many state-of-the-art detection methods require a lab with complex machinery, trained operators, and/or lengthy analysis time. In contrast, point-of-care (POC) devices are brought to the patient's location, they are easy to use, and results are obtained almost immediately. Many current POC devices are too difficult to be used without a skilled assistant, and although many are able to detect analytes above a threshold value, they give little or no quantitative information. This work presents the development of polymer-based microfluidic devices capable of sensing and quantifying biomarkers in …

Synthesis And Biological Evaluation Of Various Derivatives Of A Broad-Spectrum Anticancer Nucleoside, Jadd R. Shelton

Theses and Dissertations

Recently the Peterson lab discovered a promising anticancer adenosine derivative-- 2´,3´-bis-O-tert-butyldimethylsilyl-5´-deoxy-5´-[N-(methylcarbamoyl)amino]-N6-(N-phenylcarbamoyl)adenosine. This compound showed selective toxicity against human colon cancer cells in vitro with LC50's = 6--10 µM. It was hypothesized that the lead compound exerted its cytotoxic effects by interacting with a protein kinase. A systematic Structure Activity Relationship (SAR) was undertaken in an attempt to increase the kinase-binding affinity of the lead compound. Many regions of the lead compound were examined: the N6-phenyl urea moiety, the 5´-N-methyl urea group, the 2´,3´-bis-O-TBS groups, the nucleobase, and the ribose sugar. Results of these studies produced some promising new derivatives. In …

Accurate Methodology For Monitoring Biomembrane Events, Christine A. Winschel

Theses and Dissertations

Abstract ACCURATE METHODOLOGY FOR MONITORING BIOMEMBRANE EVENTS By Christine A. Winschel, Ph.D. A Dissertation submitted in partial fulfillment of the requirements for the degree of Doctorate of Philosophy in Chemistry at Virginia Commonwealth University. Virginia Commonwealth University, 2012 Major Director: Dr. Vladimir A. Sidorov ASSOCIATE PROFESSOR, DEPARTMENT OF CHEMISTRY This study describes the synthesis and characterization of a new receptor (cyclen 1) capable of strong selective binding of pyrene-based anionic dyes under near-physiological conditions. This receptor comprises four naphthylthiourea groups tethered to a cyclen core via an ester linkage. The most important finding was the ability of cyclen 1 to …

Development Of Nano-Scale Featured Materials For Electrode Modification And Solid Supports., Amy Rue

Theses and Dissertations

This work utilized the sol-gel process in two ways. First, macroporous silica thin films were developed using a combination of casting techniques and templating. Macroporsity was introduced to the silica thin films by either doping the silica sol before casting or by ordering the template on a substrate and then casting a sol over it. These techniques were first used to create silica thin films with long microchannel pores (200 nm x 60 µm) from a doped sol with the bacteria, B. Megaterium, as the template for nanomaterial formation. To enable the formation long microchannels, the flexible bacteria chains were …

The Synthesis And Structural Characterization Of Metal Oxide Nanoparticles Having Catalytic Applications, Stacey Janel Smith

Theses and Dissertations

Nanotechnology is blossoming into one of the premiere technologies of this century, but the key to its progress lies in developing more efficient nanosynthesis methods. Variations in synthetic technique, however, can cause variations in size, structure, and surface characteristics, thereby altering the physical properties and functionality of the particles. Careful structural characterizations are thus essential for understanding the properties and appropriate applications for particles produced by new synthetic techniques.In this work, a new ‘solvent-deficient’ method is presented for the synthesis of an unprecedentedly wide range of metal oxide nanomaterials including at least one metal oxide from each group in Groups …

Unconventional Superhalogens: Design And Applications, Devleena Samanta

Theses and Dissertations

Electron affinity is one of the most important parameters that guide chemical reactivity. Halogens have the highest electron affinities among all elements. A class of molecules called superhalogens has electron affinities even greater than that of Cl, the element with the largest electron affinity (3.62 eV). Traditionally, these are metal-halogen complexes which need one electron to close their electronic shell. Superhalogens have been known to chemistry for the past 30 years and all superhalogens investigated in this period are either based on the 8-electron rule or the 18-electron rule. In this work, we have studied two classes of unconventional superhalogens: …

Refining Vibrationally-Resonant Sum Frequency Generation Spectroscopy For Studies Of Interfacial Interactions, Alexander D. Curtis

Theses and Dissertations

Many phenomena of interest to science and engineering occur at interfaces; however, access to, or discrimination of, interfacial interactions has been challenging, especially at buried interfaces. Vibrationally resonant sum-frequency generation (VR-SFG) spectroscopy is a powerful tool for investigating the molecular structure of free or buried interfaces, but spectral analysis has relied on many assumptions. To claim accurate new insights, practitioners must be able to make unique determinations from the data without experimental artifacts affecting the final results. For example, two independent and overlapping studies for the polystyrene/air interface were carried out, but reported different surface structures. Initially, this difference was …

Solvation Of Organic Cations In The Gas Phase And Within Molecular Clusters, Ahmed Hamid

Theses and Dissertations

The role of the solvent in ionic and ion-molecule interactions is of fundamental importance in kinetics and thermodynamics of solution chemistry. However, the study of the ionic interactions in the presence of a large number of solvent molecules is very challenging. Therefore, the gas-phase is the appropriate medium to study such reactions on a molecular level where the ion-solvent interaction can be examined by studying ions surrounded with a cluster of solvent molecules in the complete absence of the any interference caused by the bulk of the solvent. In nature, organic ions can form hydrogen bonds with solvents. An insight …

Chemoselective Oxidation Of 6,13-Bis(Decylthio) Pentacene, Claire Eunhye Cho

Theses and Dissertations

Organic semiconductors present much potential for industrial use because of their possible low cost production, Pentacene and pentacene derivatives are promising candidates for organic semiconductor research since their ^-conjugated electronic structures possess small HOMO- LUMO gaps and high field effect mobility. Whereas there is much potential in devices made from pentacenes they do however undergo short lifetimes and poor processability due to photodegradation and poor solubility of pentacene. Previous research has shown that the pentacene lifetime and solubility can be enhanced by arylthio and alkylthio substituents placed on the pentacene backbone. For example 6,13-i?/s(decylthio)pentacene was one of the longest lived …

Drug Delivery Strategies Using Light Sensitive Molecules, Martin Dcona

Theses and Dissertations

Cancer remains one of the most dreaded diseases due to inevitable suffering and possible fatality. Only cardiac disease has caused more deaths than cancer. Present day cancer treatment involves radiation, surgery or chemotherapy. In chemotherapy, an anti-tumoral drug is used to treat the tumor either by killing or stalling the growth of the tumor cells. In certain types of cancer, for e.g. metastatic breast cancer, the first line of therapy is often chemotherapy. But the inability of current clinically approved drugs to selectively target tumor cells, ultimately results in side effects. To reduce these side effects, prodrug therapies have been …

Follicular Dendritic Cells, Human Immunodeficency Virus Type 1, And Alpha 1 Antitrypsin, Xueyuan Zhou

Theses and Dissertations

HIV/AIDS is raging and causing millions of deaths around the world. The major challenge in treating HIV/AIDS is the establishment of HIV reservoirs where the viruse escapes both drug and immune system attempts at eradication. Throughout the course of HIV/AIDS, productive HIV infection occurs primarily in the lymphoid follicles or germinal centers (GC) surrounding follicular dendritic cells (FDC). In the GCs, FDCs trap and maintain infectious HIV for years and provide these infectious viruses to the host cells. FDCs also attract B and T cells into the GCs and increase the ability of CD4+ T cells to be infected. Additionally, …

Novel Phosducin-Like Protein Binding Partners: Exploring Chaperone And Tumor Suppressor Protein Interactions, Amy Jetaun Gray

Theses and Dissertations

Many proteins cannot fold into their native state without the assistance of one or more molecular chaperones. Chaperonins are an essential class of chaperones that provide an isolated chamber for proteins to fold. CCT, a group II chaperonin found in eukaryotes assists in the folding of actins, tubulins, and many other cellular proteins. PhLP1 is a member of the phosducin protein family that assists CCT in the folding of Gβ and its subsequent assembly with Gγ. However, previous studies have not addressed the scope of PhLP1 and CCT-mediated Gβγ; assembly. The data presented in Chapter 2 shows that PhLP1 plays …