Physical Sciences and Mathematics Commons^™

Effect Of Polymerization Conversion On The Experimental Determination Of Monomer Reactivity Ratios In Copolymerization, Sevim Zeynep Erhan

Dissertations

In this study the comparison of the methods used to calculate monomer reactivity ratios from experimental copolymer composition data is targeted.

For this purpose, nine samples of each of nine different concentrations of styrene-methyl methacrylate monomer mixtures were prepared. These mixtures were then polymerized for different times ranging from one to nine hours and the percent conversion to copolymer was determined.

The compositions of these copolymers were determined by their refractive index increments measured in two different solvents. Ultraviolet absorption spectroscopy was also studied as a possible method to find copolymer compositions. Though this method has been used previously, UV …

The Partial Oxidation Of Methane To Methanol & Formaldehyde, Terry Matthews

Masters Theses & Specialist Projects

The conversion of methane into methanol is viewed as one approach to utilizing the vast reserves of natural gas.

One such prospect for the utilization of natural gas is the partial oxidation of methane to methanol. Methanol ranks high on the commodity market. As a liquid it is easily transportable and therefore skirts the issue of vast amounts of a gas having to be transported either by pipeline or by liquifying.

The catalytic partial oxidation of methane to methanol is investigated. Two different reactor systems are employed. The first system is a fixed bed system. The second is a fluid …

First Polymer Discussions Of Dresden In Gaussig: Polymer Blends, Otto Vogl, Elizabeth Klemm

Otto Vogl

No abstract provided.

Optimization Of Effective Nonlinear Coefficients For Second-Harmonic Generation In Molecular Crystals , K.M. White, Craig J. Eckhardt

Craig J. Eckhardt Publications

Conditions for the design of organic solids capable of optimum nonlinear optical behavior are investigated. Generalized expressions describing optimum phase-matching conditions in crystals of monoclinic symmetry and having one-dimensional hyperpolarizabilities are obtained. The results are applied to specific organic molecular solids. An anisotropic in-plane molecular polarizability is shown to provide the best condition for second-harmonic generation in these systems.

Synthesis Of Polymers And Polymer Liquid Crystals: A Euchem Conference In Lahti, Finland, Otto Vogl, Franciska Sundholm

Otto Vogl

No abstract provided.

Ua66/7/2 Hilltopper News, Wku Chemistry

WKU Administration Documents

Newsletter created by and about the WKU Chemistry department.

Gas Permeation Measurements On Small Polymer Specimens, Karen S. Burns

Chemistry & Biochemistry Theses & Dissertations

Mass spectrometry was used to measure oxygen and nitrogen permeabilities while polarography was used to measure oxygen permeabilities for several contact lens materials. Applicable sample holders were designed and fabricated to accommodate curved and flat specimens with surface areas of 0.5 cm² and 1.0 cm² and thicknesses between 0.025 mm and 0.500 mm. A prepared standard was used to calibrate the mass spectrometric analyses.

The oxygen permeability values determined by mass spectrometry were significantly greater than those determined by polarography. This was attributed to the phase boundary phenomena and the limiting oxygen permeance of water inherent in the …

Investigation Of Complex Formation By Oligomers Of Cytosine And Guanosine, Steven Roberts Davis

Chemistry & Biochemistry Theses & Dissertations

Duplex formation between oligo(C:G) _n where n=3 to 4 was shown not to occur under conditions favorable for duplex formation between poly G and poly C. Instead, a stable guano sine self-structure was found to form which a T_m of 50°C for (Gp)₃ and 80°C for (Gp)₄ at strand concentrations of 10^-5M in 1M NaCl. Neither a duplex nor a self-structure formed in the absence of salt.

Oligomers of guanosine and cytosine were obtained by basic hydrolysis and separated according to chain length using DEAE Sephadex column chromatography. Separation of cytosine oligomers with chain lengths …

Determination Of Netropsin-Dna Binding Constants From Footprinting Data, Brian Ward, Robert Rehfuss, Jerry Goodisman, James C. Dabrowiak

Chemistry - All Scholarship

A theory for deriving drug-DNA site binding constants from footprinting data is presented. Plots of oligonucleotide concentration, as a function of drug concentration, for various cutting positions on DNA are required. It is assumed that the rate of cleavage at each nucleotide position is proportional to the concentration of enzyme at that nucleotide and to the probability that the nucleotide is not blocked by drug. The probability of a nucleotide position not being blocked is calculated by assuming a conventional binding equilibrium for each binding site with exclusions for overlapping sites. The theory has been used to evaluate individual site …

Observation Of An Oxygen Isotope Effect In Yba2Cu3O7, Kevin J. Leary, Hans Conrad Zur Loye, Steven W. Keller, Tanya A. Faltens, William K. Ham, James N. Michaels, Angelica M. Stacy

Faculty Publications

A small decrease in T_c of 0.3 K to 0.5 K is observed when as much as 90% of the ¹⁶O in YBa₂Cu₃O₇ is substituted with¹⁸O. This result is consistent with our observation that there is an oxygen isotope effect in La_1.85Sr_0.15CuO₄, but in contrast with previous reports that there is no isotope effect for YBa₂Cu₃O₇. This new result suggests that phonons play an important role in the electron-pairing mechanism in YBa₂Cu₃O₇.

Molecular And Electronic Structure Of Si3h6, Mark S. Gordon, David Bartol

Mark S. Gordon

The ground state of disilylsilylene ((SiH3)2Si) is predicted to be the closed-shell (lAin C2 symmetry) state, about 6 kcal/mol below the lowest triplet es, in C2v symmetry) at the MP4/6-31 0( d) //3-21 0* level of theory. A second triplet with a very small Si-Si-Si angle e A in C2 symmetry) is found to be more than 30 kcal/mol above the ground state. The global minimum on the Si3H6 ground-state surface is predicted to be trisilacyclopropane, 18.3 and 9.7 kcalfmol, respectively, below (SiH3)2Si and SiH3SiH=SiH2•

Ab Initio Calculations On Some C3sih4 Isomers, George W. Schriver, Mark J. Fink, Mark S. Gordon

Mark S. Gordon

Restricted Hartree-Fock ab initio calculations have been performed on various isomers of silacyclobutadiene (C3SiH 4). Geometry optimizations were performed by using various basis sets. Geometric results were similar, but proper description of relative energies required the larger 6-31G* basis. Calculations treating election correlation at the MP2 level were performed on the seven lowest energy structures. These calculations gave similar results. The most stable species found is 2-methylsilacycloprop-2-en-1-ylidene. Silacyclobutadiene is almost 60 kcal mol- 1 less stable, while silatetrahedrane lies a further 32 kcal mol-1 higher in energy. The most stable isomer with normal valence is 2-silabut-1-en-3-yne, 28.2 kcal mol-1 above …

Polymerization In Nonaqueous Lyotropic Liquid Crystals With A Polymerizable Solvent, Stig Friberg, Chang Sup Wohn, Frances E. Lockwood

Chemistry Faculty Research & Creative Works

Lamellar liquid crystals of lecithin and 2-hydroxyethyl methacrylate (HEMA) were polymerized by using UV radiation. Optical microscopy, infrared spectroscopy, and small-angle X-ray diffraction were used to compare the structure prior to and after polymerization. The lamellar structure was retained after polymerization with increased interlayer spacing. © 1987, American Chemical Society. All rights reserved.

Dynamic Structure Of A Nonaqueous Lamellar Liquid Crystal: Comparison With The Aqueous Case, Stig Friberg, Anthony J.I. Ward, David W. Larsen

Chemistry Faculty Research & Creative Works

The lamellar phase of sodium dodecyl sulfate/decanol/glycerol has been compared to the analogous water-based system. Results of NMR studies of deuteriated alcohol and surfactant showed the bilayer to be more disordered in the nonaqueous case than in the phase made with water. The order profiles of the two systems, however, were of the same form, implying that the same essential packing requirements applied to each case. The overall increase in dynamic disorder observed in the glycerol system is a result of a transversely more disordered bilayer/solvent interface. © 1987, American Chemical Society. All rights reserved.

Surface-Enhanced Raman Study Of The Effect Of Ph And Electrode Potential On The Surface Concentrations Of The Electroactive Forms Of Pyridinecarboxaldehydes, Dennis Evans, Mark Anderson

Mark R. Anderson

No abstract is currently available.

Observation Of An Isotope Shift In The Superconducting Transition Temperature Of La1.85Sr0.15Cuo4, Tanya A. Faltens, William K. Ham, Steven W. Keller, Kevin J. Leary, James N. Michaels, Angelica M. Stacy, Hans Conrad Zur Loye, Donald E. Morris, T W. Barbee Iii, Marvin L. Cohen, Cohen S. Hoen, A Zettl

Faculty Publications

An oxygen isotope shift is observed in superconducting La_1.85Sr_0.15CuO₄ when ¹⁸O is substituted partially for ¹⁶O; the superconducting transition temperature T_c is lowered by 0.3 to 1.0 K in different samples. We examine these results using conventioanl phonon-mediated BCS theory and conclude that, for La_1.85Sr_0.15CuO₄, phonons play an important role in the pairing mechanism.

29th Rocky Mountain Conference

Rocky Mountain Conference on Magnetic Resonance

Program and abstracts from the 29th annual meeting of the Rocky Mountain Conference, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, August 2-6, 1987.

Π Bond Strengths In The Second And Third Periods, Michael W. Schmidt, Phi N. Truong, Mark S. Gordon

Mark S. Gordon

All possible pi bonds formed between the elements C, N, 0, Si, P, and S are considered. The pi bond strengths are estimated by the cis-trans rotation barriers (where possible) and by hydrogenation energies. The ability of these elements to form strong pibonds is in the order 0 > N "" C » S > P > Si. In addition, computed bond lengths and vibrational stretching frequencies are reported for both the singly and doubly bound compounds. The structure of the lowest triplet state of each double-bonded compound is given, along with the singlet-triplet splitting.

Mode Anharmonicity In Molecular Crystals Studied By Piezomodulated Raman Spectrosocpy , K.M. White, Craig J. Eckhardt

Craig J. Eckhardt Publications

Piezomodulated Raman scattering is used to determine the extent of anharmonicity, the phonon-phonon coupling, and the presence of modes involved in the phase transition of 1,2,4,5-tetrabromobenzene. The experiments support earlier theoretical predictions and demonstrate that piezomodulated Raman spectroscopy is an important new approach to the experimental study of lattice dynamics.

Electron Transfer-Oxy Radical Mechanism For Anti-Cancer Agents: 9-Anilinoacridines, Peter Kovacic, James R. Ames, Michael D. Ryan

Chemistry Faculty Research and Publications

A possible mode of action involving electron transfer is advanced for the 9- anilinoacridines. The mechanism entails formation of toxic oxy radicals which destroy the neoplasm. Cyclic voltammetry was performed on iminium type ions derived by protonation of the acridines. Reductions were generally reversible with potentials of about - 0.60 V. Involvement of quinoidal metabolites is also a possibility. The relationship of electrochemical behavior to structure and physiological activity is addressed.

Analysis Of Forms Of Sulfur In Coal, Gary Ruba

Masters Theses & Specialist Projects

Methods for the determination of sulfur forms are reviewed. Each method is compared to the ASTM D 2492 standard method when data are available. The extraction of pyrites with dilute nitric acid is reviewed in detail because of its relationship to data presented in this thesis.

A new technique for the analysis of organic sulfur was developed in response to a need by the coal community for an accurate and inexpensive method. In this method nitric acid extraction is used to remove the inorganic sulfur forms and the residual coal is then analyzed for organic sulfur. Organic sulfur values obtained …

The Systematic Design Of A Composite Electrolyte, Michael Setter, J. Wagner

Michael P. Setter

No abstract provided.

Calculation Of The Thermophysical Properties Of Ground State Sodium Atoms, Paul M. Holland, Louis Biolsi Jr.

Chemistry Faculty Research & Creative Works

Transport properties of dilute monatomic gases depend on the two body interaction potentials between the atoms. When two ground state sodium atoms interact, they can follow either of two potential energy curves corresponding to the Na₂ molecule in the X¹Σ⁺_g or the ³Σ⁺_u. Transport collision integrals and second virial coefficients of monatomic sodium have been calculated by accurately representing quantum mechanical potential energy curves with the Hulburt-Hirschfelder potential. The generally good agreement of calculated viscosities and second virial coefficients with the available experimental viscosities and with previously calculated virial coefficients provides …

Thermal Decomposition Of Methanethiol And Ethanethiol, Kim K. Baldridge, Mark S. Gordon, Douglas E. Johnson

Mark S. Gordon

Selected ground-state decomposition pathways for methanethiol and ethanethiol are considered, using ab initio electronic structure calculations including electron correlation. The decomposition of methanethiol to form methylene and hydrogen sulfide requires a large activation energy (108.3 kcaljmol). In contrast, the energy required for the homolytic cleavage of the C-S bond is calculated to be just 67.2 kcaljmol. For ethanethiol, carbene formation is more competitive with radical processes. Here, the activation energy for the 1,1 elimination of H2S to form ethylidene (76.9 kcaljmol) is smaller than that for the direct formation of ethylene via a 1,2 elimination (106.6 kcaljmol) and only 12 …

Lake Mead Cover Enhancement Project, Jennifer Stevens Haley, Suzanne Leavitt, Larry Paulson, Donald H. Baepler

Publications (WR)

Ninety-three wildlife agencies were surveyed for information on their attempts to improve fish habitat. In addition, an annotated bibliography including over 100 summaries was completed on:

1. largemouth bass cover requirements and preferences,

2. use and effectiveness of artificial cover,

3. aquatic plant introduction and species requirements for germination and establishment,

4. terrestrial plant introduction and species requirements for germination and establishment, and

5. nutrient exchange between sediment, aquatic plants, and water.

A reconnaissance of existing terrestrial and aquatic vegetation was completed in June 1986 including the production of a video tape of the Nevada shoreline of Lake Mead.

Cover …

Methyl Reorientation In Methylphenanthrenes: 1. Solid-State Proton Spin-Lattice Relaxation In The 3-Methyl, 9-Methyl, And 3,9-Dimethyl Systems, K. G. Conn, Peter A. Beckmann, C. W. Mallory, Frank B. Mallory

Chemistry Faculty Research and Scholarship

We have investigated the dynamics of methyl group reorientation in solid methyl‐substituted phenanthrenes. The temperature dependence of the proton spin–lattice relaxation rates has been measured in polycrystalline 3‐methylphenanthrene (3‐MP), 9‐methylphenanthrene (9‐MP), and 3,9‐dimethylphenanthrene (3,9‐DMP) at Larmor frequencies of 8.50, 22.5, and 53.0 MHz. The data are interpreted using a Davidson–Cole spectral density which implies either that the correlation functions for intramolecular reorientation are nonexponential or that there is a distribution of exponential correlation times. Comparing the fitted parameters that characterize the relaxation data for the three molecules shows that the individual contributions to the relaxation rate from the 3‐ and …

Determination Of Amino Acids And Chloramino Acids In Municipal Wastewater, Jeffrey Taylor Jewell

Chemistry & Biochemistry Theses & Dissertations

It is well known that unchlorinated municipal wastewater contains high levels of organic and inorganic amino nitrogen compounds, the single most abundant amino-N species being ammonia. Upon chlorination, these compounds are transformed almost instantaneously and quantitatively into N-chloramino derivatives. The organic chloramines have been shown to

interfere with disinfection and have lower disinfection capacities than their inorganic counterpart monochloramine. The environmental effects imposed by the discharge of these compounds into natural receiving waters is unknown. This study has shown that amino acid precursors for N-chloramino acids range in concentration from 1.4 X 10^-7 M to 9.0 X 10^{-7 …}

Reactions Of Organic N-Chloramines In The Gastric Fluid Of The Rat, Kathryn E. Mazina

Chemistry & Biochemistry Theses & Dissertations

Using chlorine as a drinking water disinfectant may have potential health effects due to its reactivity with organic amino nitrogen compounds found in the stomach. Organic N-chloramines have been shown to form in the stomachs of laboratory rats. The possible reactions of N-chloramines in the stomach fluid were examined in this study using a model radiolabeled N-chloramine. ³⁶Cl-N-Chloropiperidine, was synthesized and purified to remove ³⁶Cl-chloride. Stomach fluid was obtained from Sprague-Dawley rats which had been first fasted for 24 or 48 hours and then administered 3 mL of deionized water. Different concentrations of radiolabeled chloramine were reacted with …

Synthesis Of Potential Long Acting Calcium Channel Antagonists: A Study Of 1,4-Dihydropyridine Analogs, Thomas E. Christos

Chemistry & Biochemistry Theses & Dissertations

An investigation was undertaken to synthesize and evaluate longer acting analogs to the antihypertensive agent nifedipine. Analogs that are capable of covalent bonding to the nifedipine receptor were considered. These compounds may show increased activity as they will remain at the receptor for a longer period of time.

During the course of this study, previously unreported and unexpected products were encountered and lead to a more intense examination of the Hantzsch synthesis. Of particular interest was the oxazolidine 25 which was a major component of the Hantzsch synthesis when ethanolamine was used instead of ammonium hydroxide. Also isolated during this …

Measurement Of The Condensation Coefficient Of Water In The Umr Cloud Simulation Chamber, Daniel R. White, James L. Kassner, John C. Carstens, Donald E. Hagen, John L. Schmitt, Darryl J. Alofs, A. R. Hopkins, Max B. Trueblood, M. W. Alcorn

Physics Faculty Research & Creative Works

Measurements of the condensation coefficient of water under conditions closely approximating those in natural atmospheric cloud have been made in the cooled-wall UMR cloud simulation chamber. Current measurements disclose a value of condensation coefficient near unity at the outset of the experiment, generally decreasing to lower values (~ .01) as the experiment progresses. The significance of the magnitude of condensation coefficient in atmospheric cloud is briefly discussed.