Physical Sciences and Mathematics Commons^™

“Design Of Molecular Mechanics Modeling Techniques For Exploring Molecular Recognition Using Cyclodextrins., Shannon Bradley Fox

Doctoral Dissertations

Molecular mechanics modeling techniques have been developed to study the behavior of cyclodextrins (CDs) in capillary electrophoresis (CE) separations. Using the commercial computational package, Sybyl, the mechanisms of molecular recognition between organic analytes and CDs are investigated.

Cyclodextrin-modified capillary electrochromatography (CDCE) experiments were conducted to separate neutral derivitized naphthalene solutes using carboxymethyl-beta-cyclodextrin (CM-b-CD). Grid conformation-searching programs were developed to explore the interaction space between CD and solute and to calculate their interaction energies using molecular mechanics. The interaction energies correlated remarkably well with the separation behavior. It was found that extensive minimization (more than 3000 iterations) was required at each …

A Comparative Study Of Photomultiplier Tubes And Charge Coupled Devices In Glow Discharge-Optical Emission Spectrometry, Robert James Broadwater

Masters Theses

This Masters Thesis compared two glow discharge-optical emission spectrometers designed around two different types of detectors: the photomultiplier tube (PMT) and the charge-coupled device (CCD). The two instruments compared were the LECO SA2000 (PMT-based) and the LECO GDS500a (CCD-based). Detection limit, dynamic range, precision, accuracy, and drift were determined to compare the detection systems between 165 and 450nm.

The PMT-based system outperformed the CCD-based system in all five of the categories studied based on the initial protocol. However, it was shown that improvements could be made in four of the five categories studied by exploiting the CCDs ability to monitor …

Mechanistic Studies Of The Oxidation Of Lignin And Cellulose Models, Oh-Kyu Lee

Electronic Theses and Dissertations

Oxygen delignification is an environmentally friendly pulp bleaching system. To develop a selective delignification process that results in high DP retention of carbohydrate with lignin being removed, obtaining better knowledge of reactions occurring during oxygen delignification is essential.

In this work, mixtures of guaiacol (model lignin) and methyl-ß-D-glucoside (model cellulose) were reacted in a pressurized oxygen reaction system (pH 12,65 psi O₂, and 95°C in a glass reaction vessel). In the results, methyl-ß-D-glucoside degraded only in the presence of lignin. This indicates that hydroxyl radicals, that subsequently react with methyl-ß-D-glucoside, are generated in the system. Unfortunately, we could …

Capillary Electrophoretic Separations Of Metal Ions, Elena Hofman

Masters Theses

Transition-metal (Zn(II), Co(II), Ni(II) and Cu(II)) ion separation was studied using 8-hydroxyquinoline-5-sulfonic acid and 2-methyl-8-hydroxyquinoline ligands with surfactants (cationic and anionic) by capillary electrophoresis under a variety of conditions (like pH, ionic strength, voltage and ion, ligand and surfactant amounts) and has debuted a clear separation mechanism. With cationic surfactants, ligands compete with capillary surface silanols for the metal ions; with anionic surfactants, ligands, silanols and micelles compete.

An empirical parameter, K_e, (electrophoretic-mobilities based) rationalizing the separation was proposed, experimentally analyzed and supported; it provides a silanol group per cm² value of the capillary surface, an equilibrium …

Evaluation Of 2,2'-Bipyridylpyridinetricarbonylrhenium (I) Triflate Complex As A Luminescent Probe For The Study Of Macromolecular Solution Dynamics, Richard Allen Allston

Seton Hall University Dissertations and Theses (ETDs)

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Thermochemistry And Kinetics In Pyrolysis And Oxidation Reaction Of Oxygenate Chlorocarbons, Neopentane, And Ortho-Xylene, Hongyan Sun

Dissertations

Thermochemical properties of chlorinated alcohols, chlorinated hydroperoxides and corresponding alkoxy, hydroxy alkyl radicals, peroxy and hydroperoxy alkyl radicals are determined by ab initlo and density functional calculations for modeling and optimization of complex chemical processes for combustion or incineration of chlorinated hydrocarbons. The entropy and heat capacities from vibrational, translational, and external rotational contributions are calculated by statistical mechanics, and the hindered rotational contributions to S^°₂₉₈ and C_p(T)'s are calculated by using direct integration over energy levels of the internal rotational potentials. The values of ΔH_f^°₂₉₈ are determined using isodesmic reactions …

Synthesis And Application Of Novel Chiral Ionic Liquids Derived From Alpha-Pinene, Yun Wang

Theses

Two new chiral ionic liquids of oxazolinium cations derived from a-pinene: 9,9-Dimethyl-4-propenyl-5-propyl-3 -oxa-5-azonia-tricyclo [6.1.1.0 ^2,6] dec-4-ene tetrafluoro borate ([ChIPOZ] [BF₄]) and 9,9-Dimethyl-4-propenyl-5-propyl-3-oxa-5-azonia-tricyclo [6.1.1.0 ^2,6] dec-4-ene hexafluoro phosphate ([ChIPOZ][PF₆]). Both these chiral ionic liquids have been applied in enantiomeric copper-catalyzed 1,4-addition reactions with diethyl zinc. The enantiomeric excess for product using [ChIPOZ][BF₄] is above 70% and for [ChIPOZ][PF₆] is above 30%. Chiral ionic liquids worked as phase transfer catalysts In this reaction.

α-Pinene was used as the "chiral pool" in the synthesis of amino alcohol through a two-step reaction, followed by …

Synthesis Of Chiral Surfactants For Enantioselective Organic Synthesis., Kalyan Mondal

Electronic Theses and Dissertations

The first step of the synthesis of the hydrocarbon-based chiral surfactant (2) involved the methylation of (S)-leucinol to give (2S)-N-hexadecyl-N,N-dimethyl-(1-hydroxy-4-methyl-1-pentyl)-2-ammonium bromide (2.92g, 67%). The chiral surfactant was synthesized by reacting (2S)-N,N-dimethyl-2-amino-4-methyl-1-pentanol (1) with bromohexadecane (2.06g, 71%). The functionalized styrene for the polymer supported chiral catalyst (6) was synthesized by reacting (1) with 4-vinylbenzyl chloride. The polymerization was carried out with 10% of the functionalized monomer (5) (1.26g, 70.2%), 5% cross-linking agent divinylbenzene, and 85% of styrene with AIBN as the initiator. The structure of each of the products was confirmed by using FTIR and NMR spectroscopy. The activity of the …

Spectroscopic Examination Of The Catalytic Decomposition Of Hydrogen Peroxide By A Copper (Ii) Complex Of A Dissymmetric Schiff Base And An Imidazole Derivative., John D. Davis Jr.

Electronic Theses and Dissertations

Previous studies involving copper (II) complexed with a dissymmetric Schiff base and imidazole derivatives had identified catalase activity of these complexes towards H₂O₂. Reactions such as this are of great interest due to the important role of copper-based complexes in biological systems. Our research has been conducted to add to the base of knowledge regarding the efforts of other researchers to investigate copper complexes that exhibit similar reactivity as copper-based proteins towards dioxygen. The copper complex chosen for this study contained a tri-dentate Schiff base adduct which, when complexed with an imidazole derivative, limited the manner …

Strategies For Enhancing The Performance Of Chemical Sensors Based On Microcantilever Sensors, Christopher Tipple

Doctoral Dissertations

Microcantilever (MC) based chemical sensors have become more widely used during the past 10 years due to the advantages they possess over other chemical sensors. One of the most significant characteristics is their extremely high surface to volume ratio. This key facet allows surface forces that can be ignored on a macroscale to become a significant sensing transduction mechanism. MC based sensors also exhibit a higher mass sensitivity to adsorbates than do many other chemical sensor platforms. Under many conditions, MC based sensors directly translate changes in Gibbs free energies due to analyte-surface interactions into mechanical responses. However, the widespread …

“Enhancement Of Sensitivity And Selectivity Of Chemical Sensors Through Thin Film Coatings And Surface Modifications, Joseph Jeremy Headrick

Doctoral Dissertations

Chemical sensors have become major analytical tools for how we monitor
and obtain information about the chemical nature of ourselves and our
surroundings. Two characteristics of chemical sensors that are under constant
development and improvement are their selectivity and their sensitivity.
Selectivity is a concern of any chemical sensor, without it the signal obtained by
a chemical sensor cannot be related to the target species concentration with any
confidence. With chemical sensors the selectivity is generally created by the
used of a chemical recognition layer such as a permeable membrane, or a thin
chemical film. The sensitivity of a chemical …

Synthesis Of Porous Monoclinic Tungsten Oxides And Their Application In Sensors, Anil Bhalchandra Waghe

Electronic Theses and Dissertations

Semiconducting metal oxide sensors are limited in their usage because of their poor detection selectivity. The current approach to achieve better selectivity in SMO detection uses prefiltering/preconcentration schemes to reduce the number of gases in contact with the sensor in combination with array-based detection. In this thesis we have investigated different materials and approaches for use as elements in an array based detection system.

One approach we have investigated involves the use of porous monoclinic WO₃ to obtain size selectivity in detection within the sensing element itself. In chapter 3 we describe the synthetic protocol used to generate high …

Effects Of Fiberimatiux Interactions On The Interfacial Deformation Micromechanics Of Cellulose-Fiberipolymer Composites, William Tai-Yin Tze

Electronic Theses and Dissertations

The overall objective of this dissertation was to gain an understanding of the relationship between interfacial chemistry and the micromechanics of the cellulose-fiber/polymer composites. Regenerated cellulose (lyocell) fibers were treated with amine-, phenylamine-, phenyl-, and octadecyl-silanes, and also styrene-maleic anhydride copolymer. Inverse gas chromatography was conducted to evaluate the modified surfaces and to examine the adsorption behavior of ethylbenzene, a model compound for polystyrene, onto the fibers. Micro-composites were formed by depositing micro-droplets of polystyrene onto single fibers. The fiber was subjected to a tensile strain, and Raman spectroscopy was employed to determine the point-to-point variation of the strain- and …

The Use Of Fluorescence To Investigate The Factors Leading To Complex Formation Between Naphthalenes And ├Ƒ-Cyclodextrins, Jamie M. Iannacone

Honors Theses

Fraiji et al. determined a binding constant (K) of 581 = 6 M-1 for the 1:1 complex between 2-acetylnaphthalene (2-AN) and β-cyclodextrin (β-CD) in H20 using fluorescence quenching experiments (Appl. Spectrosc. 1994, 48, 79). Molecular modeling experiments indicate the possibility of complex stabilization resulting from hydrogen bonds between the C=O group of 2-AN and the -OH groups on the rim of β-CD. To check this possibility, we measured the K of the 2-AN:trimethyl-β-CD (TM-β- CD) complex, where all rim -OH groups are converted to –OCH3. In this case, K decreases to 134 M-1. To show that this is due to …

Sol-Gel-Platform Optical Sensors For Oxygen Gas : Sensor Development And Investigation Of Probe Partitioning In Sol-Gel Matrices, Desiree L. Plata

Honors Theses

I have developed gas sensors that respond rapidly and noticeably to changes in oxygen concentration by doping fluorescent complexes into gas-permeable sol-gel materials. Ruthenium (II) 4,7-diphenyl-1,10- phenanthroline, Ru(dpp)32+, responds to variations in ambient oxygen concentrations through marked changes in its fluorescence intensity. I investigated the response of Ru(dpp)32+ to oxygen in solution, in aerogels (sol gels dried under ambient conditions) and in aerogels (sol gels dried using supercritical conditions). Aerogels have particularly high porosity and low density, which allows for rapid diffusion of gases into the material. The aerogel sensor responds reversibly to changes in ambient oxygen concentration within 10 …

Investigation Of Indicators In Aerogels And Xerogels, Rebecca L. Wolfe

Honors Theses

A sol-gel is a silicon-oxygen matrix that is suitable for the entrapment of chemical species, including biological species, indicators, dyes, and sensors. Aerogels are sol-gels prepared by supercritical extraction, whereas aerogels are allowed to dry under ambient conditions. The resulting materials differ considerably in their physical properties. We are investigating a series of luminescent species for use as probes of the microenvironment in different sol-gel materials. Sol gels containing each probe are prepared as both aerogels and aerogels; aerogels are formed using a novel contained mold process. Spectral properties, including absorption or excitation spectra, emission spectra, time-based fluorescence scans, and …

Solution Structure Refinement Comparing Reference Model Noe Volumes, Maura Mahar

Honors Theses

NMR is a powerful experimental technique which can be used to determine protein structures. Central to this process is conversion of peak volumes in the NOE data sets into distance constraints and then structural refinement against those constraints. In general, each solution structural analysis is initiated de novo. We are interested in the structural analysis of a series of hybrids derived from two parental proteins (rubredoxins from mesophilic bacterium Clostridium pasteurianum (Cp) and the hyperthermophilic archaeon Pyrococcus furiosus (Pf)). Near 1 A resolution X-ray structures of Cp and Pf rubredoxins are available to provide a basis for quantitative comparison of …

Pharmacophore Derivation Using Discotech And Comparison Of Semi-Emperical, Ab Initio And Density Functional Comfa Studies For Sigma 1 And Sigma 2 Receptor-Ligands, Dawoon Jung

Dissertations

This study describes the development of pharmacophore and CoMFA models for sigma receptor ligands. CoMFA studies were performed for 48 bioactive sigma 1 receptorligands using [H³ ](+) pentazocine as the radioligand, for 30 PCP derivatives for sigma 1 receptor-ligands using [³H](+)SK-F 10047 as the radioligand and for 24 bioactive sigma 2 receptor-ligands using the radioligand [H³](+)DTG in the presence of pentazocine. Distance Comparisons (DISCOtech) was used as the starting point for CoMFA studies. The conformers, derived by DISCOtech were optimized using AMi, or HF/3-21G* in Gaussian 98. The optimized geometries were aligned with the pharmacophore, …

Studies Of Electroosmotic Flow Dynamics During Electrophoretic Separations, Jason Lasseter Pittman

Doctoral Dissertations

Instrumentation and techniques for monitoring electroosmotic flow (EOF) during capillary electrophoretic (CE) separations in both fused-silica capillaries and glass microfluidic devices are presented. These techniques were applied under conventional and sample stacking separation conditions. The instrumentation developed for monitoring EOF was also used to develop optically gated vacancy separations in microfluidic devices.

A recently developed technique for monitoring EOF in capillary electrophoresis by periodic photobleaching of a neutral fluorophore added to the running buffer was further characterized and optimized and then applied to monitoring EOF during a typical capillary electrophoresis separation. The concentration of neutral fluorophore (rhodamine B) added to …

Dipole-Bound Anions, Nathanael Isaac Hammer

Doctoral Dissertations

Any molecule with a dipole moment above approximately 2.5 Debye can form a stable negative ion (dipole-bound anion). These anions are best produced by “resonance” charge exchange from atoms in high Rydberg states (Rydberg electron transfer, RET). RET to form dipole-bound anions occurs over a narrow range of effective principle quantum number, n*. Dipole-bound anions for 32 molecules with dipole moments between 2.5 and 6.0 Debye have been studied. The excess electron in such an anion is very diffuse and weakly bound. Binding energies (electron affinities, EAs) are estimated from the narrow range of n* at which charge exchange occurs …

Surface Interactions Of Mercury On Gold Foil Electrodes In Electrodeposition And Stripping And ; An Investigation Of Free Thiolate Ions From Metal-Thiolate Chalcogenides, Charles Martin Watson

Electronic Theses and Dissertations

Mercury, a highly toxic metal, whose environmental concentration magnifies with ascension of the food chain, is monitored in our waters, food and air. Monitoring mercury is generally done by sample collection, transport to the laboratory; followed by: digestion of the sample, separation of the mercury and detection of the mercury: mostly by cold vapor atomic absorption or, cold vapor atomic fluorescence. These monitoring methods, preclude, routine, in-the-field mercury determination. New analytical techniques have been proposed for in the field determination of mercury. They consist of mercury adsorption onto a sensor or electrode and measuring how much is there either as …

Oxygen Delignification Kinetics And Selectivity Improvement, Steven M. Violette

Electronic Theses and Dissertations

Pulp strength loss during oxygen delignification is caused by cellulose chain cleavage resulting fiom attack by oxygen-based radicals generated through reactions with lignin. The objective of this research was to improve the lignin-to-cellulose selectivity during oxygen delignification by using radical-scavenging polymeric additives that adsorb on the cellulose surfaces where protection fiom radicals is needed. Among the polymers evaluated were starch, carboxymethyl-cellulose, galactomannan, xylan, and glucomannan. Oxygen delignification experiments were conducted on Northeast softwood Kraft pulps at different temperatures, sodium hydroxide charges, reaction times, and pretreatments. The effect of polymer additives on the selectivity and kinetics was studied. Polymer adsorption on …

Relationship Between Alkaline Pulp Yield And The Mass Fraction And Degree Of Polymerization Of Cellulose In Pulp, Mehmet Sefik Tunc

Electronic Theses and Dissertations

Wood as a raw material is generally the dominant cost factor for the production of chemical pulp. Therefore, an increase in pulp yield has a major impact on the competitiveness of a mill. In order to optimize pulp yield, for example by changing operating conditions, a mill must be able to monitor the yield accurately. However, an accurate "real-time" pulp yield measurement method is not available at the present time. Pulping yield is presently measured from the amount of pulp produced from a given quantity of wood consumed over a 3 to 6 month time frame. This method is obviously …

Reactions Of Alcohols And Organophosphonates On Tungsten Trioxide Epitaxial Films, Shuguo Ma

Electronic Theses and Dissertations

The adsorption, diffusion, reactions, and desorption of water, alcohols, ethers, and an organophosphonate were studied using calibrated thermal desorption spectroscopy (CTDS) on thin film WO₃(OOl) surfaces grown epitaxially on a single crystal α- Al₂O₃(li02) (sapphire) substrate. The studies were conducted on oxidized and reduced surfaces, which were characterized by x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The desorption spectra for molecular desorption of all of these molecules shifted to lower temperature with increasing coverage, and had overlapping tails on the high temperature side. Monte Carlo simulations show that this typical desorption shape …

Asymmetric Transfer Hydrogenation Of Allylic Alcohols, Joseph M. Laquidara

Seton Hall University Dissertations and Theses (ETDs)

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Measurement Of Proton Transfer Reaction Rates In A Microwave Cavity Discharge Flowing Afterglow, George M. Brooke Iv

Physics Theses & Dissertations

The reaction rate coefficients between the hydronium ion and the molecules ethene (C₂H₄), propene (C₃H₆), 1-butene (C₄H₈) and hydrogen sulfide (H₂S) were measured at 296 K. The measured reaction rates were compared to collision rates calculated using average dipole orientation (ADO) theory. Reaction efficiency depends primarily upon the proton affinity of the molecules. All the measurements were obtained using the newly developed microwave cavity discharge flowing afterglow (MCD-FA) apparatus. This device uses an Asmussen-type microwave cavity discharge ion source that is …

Analysis Of Anion Distributions In The Developing Strata Of A Constructed Wetland Used For Chlorinated Ethene Remediation, Joshua D. Kovacic

Theses and Dissertations

Perchloroethene (PCE), Trichloroethene (TCE) and their degradation products are among the most common organic groundwater contaminants in the United States. Constructed wetlands utilizing upward flow harbor reduction-oxidation conditions that have demonstrated the potential to promote both partial and total mineralization of PCE and TCE through the process of natural attenuation. Organic acid and inorganic anion concentrations are indicative of reduction-oxidation processes that drive chlorinated ethene degradation. These analytes were investigated to assess their development within three vertically stratified regions of a constructed wetland cell at Wright-Patterson Air Force Base fed by groundwater contaminated with PCE and TCE. Data collected during …

Flanking Sequences Modulate Diepoxide Cross-Linking Efficiencies At The 5'-Gnc Sste, Gregory A. Sawyer

Honors Theses

Diepoxybutane, diepoxyoctane, and mechlorethamine are cytotoxic DNA crosslinking agents that vary in their carcinogenic versus chemotherapeutic potentials. Interstrand cross-linking occurs between the N7 positions of deoxyguanosine residues on opposite strands of the DNA duplex. Each synthetic DNA oligomer used in this study contained four 5'-N\GN2CN3 sites (within a 32 base sequence) and we have systematically varied the bases in the N1 and N2 positions to determine the resulting cross-linking efficiencies of each cytotoxic agent. Each duplex was 5' -end labeled and incubated with cross-linking agent. Interstrand cross-links were purified through denaturing polyacrylamide gel electrophoresis and then subjected to piperidine cleavage. …

Phosphoproteomic Studies Of Smooth Muscle Contraction: Investigation Of Differential Phosphorylation In Relaxed/Contracted Rat Aortic Smooth Muscle Tissue Using Maldi-Tof Ms, Tonya M. Pekar

Theses, Dissertations and Capstones

Many human disorders are associated with the malfunction of smooth muscle tissue, or are related to the capabilities of its proper function—asthma, glaucoma, renal inefficiency, hypertension, and cardiovascular disease. Dysfunctional proteins are frequently implicated as the source of such disorders. As the second highest cause of death in the United States, the epidemic of cardiovascular disease makes the study of smooth muscle of utmost concern.

The capabilities of proteomics and mass spectrometry allow the entire proteome complement of a cell or tissue type to be analyzed at once. This investigation employs such techniques in an effort to better understand the …

Investigations Of Supramolecular And Catalytic Properties Of Ppi Dendrimers, Aaron K. Holley

Theses, Dissertations and Capstones

The research reported in this thesis focused on supramolecular and catalytic properties of poly(propylene imine) (PPI) dendrimers. Analytical techniques used in this research included high resolution NMR spectroscopy, as well as UV-vis and fluorescence spectroscopies and scanning electron microscopy. This investigation showed that: (1) PPI dendrimers interact with diacids to form interlock self-assemblies by electrostatic interactions (with an increase in dendrimer generation, smaller diacids are required to form the most efficient self-assembly); (2) PPI/diacid self-assemblies are able to encapsulate fluorescent dyes within the void spaces of the PPI/diacid moieties; (3) PPI-3 can chelate many types of metal cations, and these …