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Articles 1 - 18 of 18
Full-Text Articles in Physical Sciences and Mathematics
Strategies To Resolve The Three-Dimensional Structure Of The Genome Of Small Single-Stranded Icosahedral Viruses, Eduardo Sanz Garcia
Strategies To Resolve The Three-Dimensional Structure Of The Genome Of Small Single-Stranded Icosahedral Viruses, Eduardo Sanz Garcia
Theses and Dissertations
The aim of this study is the three-dimensional structural characterization of the genome packaging inside viral capsids via cryo-electron microscopy and three-dimensional reconstruction. The genome of some single-stranded viruses can be densely packaged within their capsid shells. Several stretches of the genome are known to adopt stable secondary structures, however, to date, little is known about the three-dimensional organization of the genome inside their capsid shells. Two techniques have been developed to facilitate the structural elucidation of genome packaging: the asymmetric random-model method, and the symmetry-mismatch, random model method. Both techniques were successfully tested with model and experimental data. The …
Chemical Vapor Deposition Of Silanes And Patterning On Silicon, Feng Zhang
Chemical Vapor Deposition Of Silanes And Patterning On Silicon, Feng Zhang
Theses and Dissertations
Self assembled monolayers (SAMs) are widely used for surface modification. Alkylsilane monolayers are one of the most widely deposited and studied SAMs. My work focuses on the preparation, patterning, and application of alkysilane monolayers. 3-aminopropyltriethoxysilane (APTES) is one of the most popular silanes used to make active surfaces for surface modification. To possibly improve the surface physical properties and increase options for processing this material, I prepared and studied a series of amino silane surfaces on silicon/silicon dioxide from APTES and two other related silanes by chemical vapor deposition (CVD). I also explored CVD of 3-mercaptopropyltrimethoxysilane on silicon and quartz. …
High Flow Air Sampling For Field Detection Using Gas Chromatography-Mass Spectrometry, Jacolin Ann Murray
High Flow Air Sampling For Field Detection Using Gas Chromatography-Mass Spectrometry, Jacolin Ann Murray
Theses and Dissertations
The ability to rapidly detect and identify hazardous analytes in the field has become increasingly important. One of the most important analytical detection methods in the field is gas chromatography-mass spectrometry (GC-MS). In this work, a hand-portable GC-MS system is described that contains a miniature toroidal ion trap mass analyzer and a low thermal mass GC. The system is self-contained within the dimensions of 47 x 36 x 18 cm and weighs less than 13 kg. Because the instrument has a small footprint, it was used as the detector for an automated near-real-time permeation testing system. In permeation testing, materials …
Work Towards The Isolation And Characterization Of The Muscle Isoform Of Glucose 1,6-Bisphosphatase, Caleb J. Hiller
Work Towards The Isolation And Characterization Of The Muscle Isoform Of Glucose 1,6-Bisphosphatase, Caleb J. Hiller
Theses and Dissertations
Glucose 1,6-bisphosphate is an important small molecule involved in the regulation of glycolysis. Four enzymes synthesize this compound. One enzyme is known to degrade it, glucose 1,6-bisphosphatase. Other groups have produced work that indicates that there are two isoforms of this enzyme, one predominant in the brain and one in the muscle. This thesis contains the work performed in attempts to isolate and characterize the muscle isoform of glucose 1,6-bisphosphatase. While this enzyme was not isolated, much was learned about it and the results from this work may help in the future identification of this enzyme.
Halo Ion Trap Mass Spectrometry: Design, Instrumentation, And Performance, Miao Wang
Halo Ion Trap Mass Spectrometry: Design, Instrumentation, And Performance, Miao Wang
Theses and Dissertations
New ion trap mass spectrometry (ITMS) instrumentation, the toroidal IT and halo IT, were developed to meet the significant growth in on-site analysis applications. The miniature toroidal IT mass analyzer was operated with radio frequency (RF) trapping voltages of 3 kVp-p or less. Despite its reduced dimensions, it has roughly the same ion trapping capacity as conventional 3D quadrupole ITs. Unit-mass resolved spectra for n-butylbenzene, xenon, and naphthalene were obtained. The desired linear mass scale was obtained using conventional mass-selective instability scan combined with resonance ejection. The halo IT was also based on toroidal trapping geometry and microfabrication technology, consisting …
Functionalization Of Diamond And Its Application In High Performance Liquid Chromatography And Solid Phase Extraction, Gaurav Saini
Functionalization Of Diamond And Its Application In High Performance Liquid Chromatography And Solid Phase Extraction, Gaurav Saini
Theses and Dissertations
The primary focus of my work was to chemically functionalize diamond as normal and reversed phases for solid phase extraction (SPE) and high performance liquid chromatography (HPLC). Diamond was functionalized with -NH2 groups via self-limiting adsorption of an amine-containing polymer, polyallylamine (PAAm), onto oxidized diamond particles. The chemical stability of these particles was improved by thermal curing or chemical crosslinking with 1,2,5,6-diepoxycyclooctane. The reversed phase material for SPE was synthesized by reacting amine-functionalized diamond particles with long chain alkyl and a perfluorinated isocyanate. Unlike commercially available silica, functionalized diamond particles were stable under extreme pH conditions (pH 0-14). Functionalized diamond …
Axial Temperature Gradients In Gas Chromatography, Jesse Alberto Contreras
Axial Temperature Gradients In Gas Chromatography, Jesse Alberto Contreras
Theses and Dissertations
The easiest and most effective way to influence the separation process in gas chromatography (GC) is achieved by controlling the temperature of the chromatographic column. In conventional GC, the temperature along the length of the column is constant at any given time, T(t). In my research, I investigated the effects of temperature gradients on GC separations as a function of time and position, T(t,x), along the column. This separation mode is called thermal gradient GC (TGGC). The research reported in this dissertation highlights the fundamental principles of axial temperature gradients and the separation potential of the TGGC technique. These goals …
Integrated Affinity Column Capillary Electrophoresis Microdevices For Biomarker Analysis, Weichun Yang
Integrated Affinity Column Capillary Electrophoresis Microdevices For Biomarker Analysis, Weichun Yang
Theses and Dissertations
In this dissertation, microfluidic systems that integrate antibody-based sample preparation methods with electrophoretic separation are developed to analyze multiple biomarkers in a point-of-care setting. To form an affinity column, both monolith materials and wall-coated channels were explored. I successfully demonstrated that monolith columns can be prepared in microfluidic devices via photopolymerization. The selectivity of monolith columns was improved by immobilizing antibodies on the surface. These affinity columns can selectively enrich target analytes and reduce the signal of contaminant proteins up to 25,000 fold after immunoaffinity extraction. These results clearly demonstrate that microchip affinity monoliths can selectively concentrate and purify target …
Synthesis And Characterization Of An Oligothiophene-Ruthenium Complex And Synthesis And Optical Properties Of Oligothiophene-Ruthenium Complexes Bound To Cdse Nanoparticles, Nathan A. Bair
Theses and Dissertations
Oligothiophenes are of increasing interest in organic based electronic devices in part due to their high electron and hole mobilities. In an organic photovoltaic (OPV) device, the electronic properties of oligothiophenes make them advantageous as charge transfer junctions. To serve as charge transfer junctions, oligothiophenes must be functionalized to bind to the donor and acceptor parts of the device. The donor and acceptor parts are different materials and the synthesis of asymmetric oligothiophenes is of great interest. Previous researchers in our lab synthesized four asymmetric oligothiophenes, two with two thiophene subunits and two with four. Each set of oligothiophenes contained …
Synthesis Of Glycolipids And Evaluation Of Their Nkt Cell Stimulatory Properties, Yang Liu
Synthesis Of Glycolipids And Evaluation Of Their Nkt Cell Stimulatory Properties, Yang Liu
Theses and Dissertations
Natural killer T (NKT) cells are a subset of T cells that modify a variety of immune responses. NKT cells recognize glycolipid antigen presented by a molecule called CD1d, a nonclassical antigen-presenting molecule. The best known subset of CD1d-dependent NKT cells expresses an invariant T cell receptor Vα (TCR-α) chain. These are referred to as type I or invariant NKT (iNKT) cells. When stimulated by a glycolipid, NKT cells rapidly release large amounts of cytokines. Cytokines released by NKT cells can induce either Th1 or Th2 responses. Th1 cytokines are effective in regulating bacterial, parasitic, and viral infections. But Th1 …
Targeting Complex Cyclic Peptides For Synthesis: The Celogentin And Theonellamide Families, Joshua Wayne Robinson
Targeting Complex Cyclic Peptides For Synthesis: The Celogentin And Theonellamide Families, Joshua Wayne Robinson
Theses and Dissertations
Celogentin C and theonellamide F are a class of natural products that have potential antimitotic behavior. They both contain interesting bicyclic structures with unusual linkages within a central moiety. Celogentin C's highly functionalized tryptophan moiety has two unusual linkages, a β-substituted Leu connection to the C6 of the indole structure that makes up the left-hand ring, and a τ-N connection of the imidazole to the C2 of the indole constructing the right-hand ring. This right-hand ring connection was solved via a novel oxidative coupling procedure developed in our group and the left-hand ring was initially constructed via a radical conjugated …
Celogentin C And Thioviridamide: Synthetic And Structural Studies, Dmitry Nikolayevich Litvinov
Celogentin C And Thioviridamide: Synthetic And Structural Studies, Dmitry Nikolayevich Litvinov
Theses and Dissertations
Project I Celogentin C, isolated by Kobayashi from the seeds of Celosia argentea in 2001 exhibits strong inhibitory behavior towards polymerization of tubulin – globular protein, which plays crucial role during the cell division cycle. We have attempted synthesis of the left-hand ring of celogentin C via the intramolecular alkylation and the Knoevenagel condensation strategies. Utilizing synthetic methodologies in the field of nitroacetyl chemistry, developed by Kornblum and Rajappa we have successfully prepared the intermolecular Knoevenagel condensation product – the late-stage precursor to the left-hand ring of celogentin C. Synthesis of this key intermediate subsequently led to the preparation of …
Ribosomal Rna Mutations That Inhibit The Activity Of Transfer-Messenger Rna Of Stalled Ribosomes, Jacob N. Crandall
Ribosomal Rna Mutations That Inhibit The Activity Of Transfer-Messenger Rna Of Stalled Ribosomes, Jacob N. Crandall
Theses and Dissertations
In eubacteria, stalled ribosomes are rescued by a conserved quality-control mechanism involving transfer-messenger RNA (tmRNA) and its protein partner SmpB. Mimicking a tRNA, tmRNA enters stalled ribosomes, adds Ala to the nascent polypeptide, and serves as a template to encode a short peptide that tags the nascent protein for destruction. To further characterize the tagging process, we developed two genetic selections that link tmRNA activity to cell death. These negative selections can be used to identify inhibitors of tagging or to identify mutations in key residues essential for ribosome rescue. Little is known about which ribosomal elements are specifically required …
Role Of Members Of The Phosducin Gene Family In Protein Translation And Folding, Nana Sono-Koree
Role Of Members Of The Phosducin Gene Family In Protein Translation And Folding, Nana Sono-Koree
Theses and Dissertations
G proteins regulate various physiological processes by way of transducing a wide variety of signals ranging from hormonal to sensory stimuli. Malfunctions in G protein signaling lead to numerous diseases. G protein signaling begins with binding of a ligand to a G protein-coupled receptor resulting in a conformational change that leads to the exchange of a GDP for a GTP on G α. The GTP bound α subunit dissociates for its stable Gβγ dimer partner. G α-GTP and Gβγ control the activity of effector enzymes and ion channels that ultimately orchestrate the cellular response to stimulus. Current reports have shown …
The Asymmetric Phase-Transfer Catalyzed Alkylation Of Imidazolyl Ketones And Aryl Acetates And Their Applications To Total Synthesis, Michael Andrew Christiansen
The Asymmetric Phase-Transfer Catalyzed Alkylation Of Imidazolyl Ketones And Aryl Acetates And Their Applications To Total Synthesis, Michael Andrew Christiansen
Theses and Dissertations
Phase-transfer catalysts derived from the cinchona alkaloids cinchonine and cinchonidine are widely used in the asymmetric alkylation of substrates bearing moieties that resonance stabilize their enolates. The investigation of α-oxygenated esters revealed decreased α-proton acidity, indicating the oxygen's overall destabilizing effect on enolates by electron-pair repulsion. Alkylation of α-oxygenated aryl ketones with various alkyl halides proved successful with a cinchonidine catalyst, giving products with high yield and enantioselectivity. The resulting compounds were converted to esters through modified Baeyer-Villiger oxidation. Alkylation with indolyl electrophiles gave products that underwent decomposition under Baeyer-Villiger conditions. Alternative N-methylimidazolyl ketones were explored. Alkylated imidazolyl ketones, obtained …
Time-Resolved Infrared Spectroscopy And Density Functional Theory Study Of Weak Interactions Of Metal Carbonyls And Organic Solvents, Carolyn Evans Sheffield
Time-Resolved Infrared Spectroscopy And Density Functional Theory Study Of Weak Interactions Of Metal Carbonyls And Organic Solvents, Carolyn Evans Sheffield
Theses and Dissertations
Pulsed laser flash photolysis of M(CO)6 (M = Cr, W) in cyclohexane with a small amount of benzene results in three sequential reactions. The first is the photodissociation of the parent to yield a M(CO)5:C6H12 complex, which takes place faster than the time resolution of our experiments. The second reaction is the replacement of the cyclohexane ligand with benzene to form a M(CO)5:C6H6 complex, in which benzene is coordinated to the metal via one side of the ring. This complex then falls apart in solution as M(CO)5 coordinates with a trace impurity in the solution that is likely water. Kinetic …
The Heat Capacity And Thermodynamic Properties Of The Iron Oxides And Their Relation To The Mineral Core Of The Iron Storage Protein Ferritin, Claine Lindsey Morton Snow
The Heat Capacity And Thermodynamic Properties Of The Iron Oxides And Their Relation To The Mineral Core Of The Iron Storage Protein Ferritin, Claine Lindsey Morton Snow
Theses and Dissertations
The iron oxides are a group of materials with geological, biological, and technological importance. A thermodynamic understanding of these materials is important because it provides information about their relative stabilities, chemical reactivity, and transformations. This study provides the heat capacity of a nanocrystalline magnetite (Fe3O4) sample, bulk hematite (α-Fe2O3), nanocrystalline hematite, akaganéite (β-FeOOH), and lepidocrocite (γ-FeOOH) at temperatures as low as 0.5 K. These measurements were fit to theoretical functions at temperatures lower than 15 K, and the respective thermophysical properties of these materials are discussed. Also the molar entropies of bulk hematite and hydrous nanocrystalline hematite as well as …
Differences In The Mechanism Of Collagen Lattice Contraction By Myofibroblasts And Smooth Muscle Cells, J. C. Dallon, H P. Ehrlich
Differences In The Mechanism Of Collagen Lattice Contraction By Myofibroblasts And Smooth Muscle Cells, J. C. Dallon, H P. Ehrlich
Faculty Publications
Both rat derived vascular smooth muscle cells (SMC) and human myofibroblasts contain $\alpha$ smooth muscle actin (SMA), but they utilize different mechanisms to contract populated collagen lattices (PCLs). The difference is in how the cells generate the force that contracts the lattices. Human dermal fibroblasts transform into myofibroblasts, expressing $\alpha$-SMA within stress fibers, when cultured in lattices that remain attached to the surface of a tissue culture dish. When attached lattices are populated with rat derived vascular SMC, the cells retain their vascular SMC phenotype. Comparing the contraction of attached PCLs when they are released from the culture dish on …