Physical Sciences and Mathematics Commons^™

Solid State 13C Nmr And Thermal Analysis Of Conformational Motion And Disorder In Small And Large Molecules, Jinlong Cheng

Doctoral Dissertations

In this work it is attempted to explore the conformational motion and disorder through a large number of examples of molecular systems differing in shape, rigidity, and molecular weight: a series of tetra-n-alkylammonium bromides and iodides, a liquid-crystal-forming molecule, N,N'-bis(4-n-octyloxybenzal)-1,4-phenylenediamine (OOBPD), and polymers, poly[oxy-1,4-(3-methylphenylene)ethylene-1,4-phenyleneoxynonamethylene] (MBPE-9) and poly[oxy-1,4-(3-methylphenylene)ethylene-1,4-phenyleneoxypentamethylene] (MPBE-5). The techniques used to study the conformational motion and disorder are mainly solid state ¹³C nuclear magnetic resonance (NMR) spectroscopy and thermal analysis.

The results of this work show that conformational disordered states (condis crystals) exist indeed in these molecules containing flexible chemical bonds (single …

Determination Of The Thermal Stability Of Perfluoropolyalkyl Ethers By Tensimetry, Larry S. Helmick, William R. Jones Jr

Science and Mathematics Faculty Publications

The thermal decomposition temperatures of several perfluoropolyalkyl ether fluids were determined with a computerized tensimeter. In general, the decomposition temperatures of the commercial fluids were all similar and significantly higher than those for noncommercial fluids. Correlation of the decomposition temperatures with the molecular structures of the primary components of the commercial fluids revealed that the stability of the fluids was not affected by carbon chain length, branching, or adjacent difluoroformal groups. Instead, stability was limited by the presence of small quantities of thermally unstable material and/or chlorine-containing material arising from the use of chlorine containing solvents during synthesis. Finally, correlation …

Determination Of The Oxidative Stability Of Perfluoropolyalkyl Ethers And Correlation With Chemical Structure, Larry S. Helmick, William R. Jones Jr

Science and Mathematics Faculty Publications

The oxidative stabilities of several perfluoropolyalkyl ethers (PFPAE) with related chemical structures were determined by thermal gravimetric analysis and correlated with their chemical structures. These results show that oxidative stability increases as the number of difluoroformal groups decreases and as trifluoromethyl substituents are added. They are also consistent with a recently proposed intramolecular disproportionation reaction mechanism involving coordination of successive ether oxygens to a Lewis acid. Since polytetrafluoroethylene contains no oxygen, it provides an indication of the upper limit to oxidative stability of PFPAE fluids. These results also show that oxidative decomposition of PFPAE fluids requires the presence of an …

New Syntheses Of Diaryl Ethers, Tyrosinols, B-Hydroxytyrosinols, L,L-Isodityrosinol And L,L-Isodityrosine-Derived Agents Via The Diels-Alder Reaction, Xianqi Feng

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Syntheses of diaryl ethers were approached by use of a Diels-Alder reaction employing a new type of diene attached with an aryloxy group. Thus, 2-methyl-3-phenoxybutadiene (90b ), 2- methoxy-3-phenoxybutadiene (92b) and (4S)-3-(t- butyloxycarbony1)-2 ,2-dimethyl-4-( 4-(3-methoxy-1,3 -butadienyl-2- oxy )phenylmethyl]oxazolidine (93b) were synthesized in ~65% yields by methylenation of the carbonyl function in the corresponding 2- substituted acrylate aryl ester using Tebbe's reagent. The 1,3- bis[(trimethylsilyl)oxy ]-2-phenoxybutadiene (105) was made from 1-phenoxy-2-propanone (101) by a sequence of formylation and enolsilylation. Methyl propiolate (107) and dimethyl acetylenedicarboxylate (113) were heated at reflux with diene 9 0 b and 92b in toluene to provide …

Development Of Hplc-Ec Methodology & Its Use In The Determination Of The Daily Pattern Of Brain Octopamine Levels In Leucophaea Maderae, Maya Siddiqui

Masters Theses & Specialist Projects

A solid phase extraction technique was developed to aid in removing interfering substances from the cockroach brain extract. Quantitative analysis of octopamine was subsequently achieved by HPLC with amperometric electrochemical detection. The procedure affords 80 to 100 percent recovery of octopamine. The presence of octopamine in brain extract was confirmed by GC-MS.

The daily pattern of brain octopamine levels in cockroach Leucophaea maderae was investigated using the HPLC-EC assay procedure. It was concluded that the concentration of brain octopamine in the cockroach L. maderae does not exhibit daily rhythm.

The Palladium (Ii) –Catalyzed Homogeneous Oxidation Of 1-Hexene, Margarita Kirova

Masters Theses & Specialist Projects

The Palladium(II)-catalyzed homogeneous oxidation of 1-hexene in methanolic medium has been studied, copper(II) chloride being used as cocatalyst. Aspects of the kinetics, mechanism and product composition were investigated in several series of oxidations involving variation of hexene concentration, oxygen partial pressure, Cu(II): Pd(II) ratio and concentration and temperature. The progress of the reaction was studied in the course of periodic sampling runs. Reaction products were identified by gas chromatography, and verified by means of GC/mass spectrometry. The expected product of 1-hexene oxidation was 2-hexeanone: however, 3-hexanone occurs as a major coproduct, arising from concurrent Pd(II)-catalyzed isomerization of 1-hexene to 2-hexene. …

Mobilization Of Iron Enhances The Iron-Dependent Biochemical Reactivity Of Asbestos In Vitro And Contributes To The Cytotoxicity Of Asbestos In Cultured Cells, Loren Glen Lund

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Asbestos related research began approximately 60 years ago, yet, the mechanism(s) by which asbestos exerts its biological effects is not well understood. The hypothesis upon which this dissertation is based is that mobilization of iron from asbestos enhances the iron-dependent biochemical reactivity of asbestos in vitro and contributes to asbestos-dependent cytotoxicity. The specific aims for this hypothesis were, 1) to determine whether iron was responsible for the biochemical reactivity of asbestos in vitro and asbestos-induced cytotoxicity in cultured cells, and 2) to determine whether mobilization of iron from asbestos enhanced the reactions catalyzed by asbestos in vitro and contributes to …

The Synthesis And Characterization Of Metal Binding Polymers Containing 2,2'-Biimidazole, R. A. Proctor

Opportunities for Undergraduate Research Experience Program (OURE)

Epoxides are known to form ring-opened polymer products that have demonstrated improved material strength, high heat stability, and chemical resistance as adhesives, coatings, and molding materials. It has been suggested that imidazoles can be used in the catalysis of this polymerization, and that the pyridyl nitrogen of the imidazole ring participates in epoxy ring-opening and is then incorporated in the polymeric structure. This study was conducted to test this theory of the role of pyridyl nitrogen in the reaction of 1,1'-dihydroxyethyl-2,2'- biimidazole (HEB) and metal-HEB complexes with the diglycidyl ether of bisphenol A (DGEBA). Of particular interest in this study …

Viscoelastic Properties Of A Liquid-Crystalline Monomer And Its Dimer, Gregory A. Dilisi, Charles Rosenblatt, Anselm C. Griffin, Uma Hari

Faculty Publications

Quasielastic-light-scattering measurements are reported for a dialkoxyphenylbenzoate monomer and its dimer in their respective nematic phases. The splay and twist elastic moduli of the dimer are found to be nearly independent of molecular length. The dimer's bend modulus, however, shows an anomalous increase with decreasing temperature well below the nematic-isotropic phase transition. Monomer viscosities are consistent with typical literature values, although γ₁/η_splay and η_bend seem to be larger than expected for the dimer, where γ₁ is the twist viscosity. The results are discussed in terms of viscoelastic properties of semiflexible rods. The elastic properties in …

Optimization In Chemical Kinetics, Arthur T. Benjamin, Gordon J. Hogenson '92

All HMC Faculty Publications and Research

No abstract provided in this article.

Single And Double Ionization Of Helium By Highly Charged Sulfur Ions, Karen M. Lifrieri

Masters Theses

Single and double ionization of helium by highly charged sulfur projectiles is investigated over an energy range of 0.16 to 1.6 MeV/u. Absolute cross sections for the processes of pure ionization, ionization associated with single capture, and ionization associated with single loss by S^6,13+ projectiles were experimentally determined and compared with previous results and theories. Ratios of double-tosingle ionization for each outgoing projectile charge state were also determined and compared with theory. The pure ionization ratios for S⁶⁺ at the highest energies investigated show the q²/E dependence predicted by Knudsen et al. (1984). For S^{13+ …}

Thermal Properties Of Some Lipid Components Of Cell Membranes, Lihua Wei

Masters Theses & Specialist Projects

Phospholipids are the major structural components of the lipid portion of biological membranes. The study of the thermal properties of these phospholipid provides a systematic understanding of the relationships between the chemical structures and functional properties of phospholipid molecules in artificial and biological membranes. This study examined the thermal behavior of phospholipids in the solid state using DSC and TG coupled with FITR. The phospholipids were found to have phase transitions below the melting point. Egg-yolk lecithin had four transitions below its melting point; sphingomyelin had two phase transitions below its melting point. Phosphatidylethanolamine and phosphatidylserine had complex phase transitions. …

Thermal Analysis Of Milkweed Floss Using Tg/Ftir, Pei Gu

Masters Theses & Specialist Projects

The thermal analysis of milkweed and several individual commercial samples of .similar chemical composition has been carried out. By combining a two-stage thermal process. (pyrolysis-combustion) with TG-FTIR, it has been possible to identify the major organic volatile products during pyrolysis and to correlate gas evolution with the decomposition of the individual components (cellulose, hemicellulose and lignin) of the floss. During pyrolysis, acetic acid, formic acid and methanol are formed 1n addition to CO2, and H2O. The data also show that pyrolytic decomposition of the three chemical constituents of milkweed occur without any apparent synergistic interaction. The combustion of …

Biodegradation Of Crude Oil By Marine Higher Fungi, Brian J. Dyer

Biological Sciences Theses & Dissertations

Four experiments were performed to determine the ability of marine higher fungi to grow in and degrade crude oil. Eight species, previously determined to be hydrocarbonoclastic, were grown in artificial sea water medium (ASM) and southern Louisiana crude oil. The dry mycelial weights were measured and consumption of crude oil was measured gravimetrically. The two species with the best growth, Corollospora maritima and Zalerion maritimum, were grown in ASM containing crude oil spiked with three known hydrocarbons. To this was added glucose (0.15%) and incubated 49 days to test for possible cometabolism of hydrocarbons. Hydrocarbons remaining in the growth …

Selectivity In Detection Of Analytes In Flowing Streams Using Piezoelectric Quartz, Mark Anderson, John Roush, David Thacker

Mark R. Anderson

No abstract is currently available.

Characterization Of Electrochemical Double Layer From The Infrared Spectroscopic Behavior Of Adsorbed Carbon Monoxide, Mark Anderson

Mark R. Anderson

No abstract is currently available.

Vibrational Branching Ratios From The Dissociation Of The Neibr Van Der Waals Molecule, Sarah Anne Walter , '91, Thomas Alex Stephenson

Chemistry & Biochemistry Faculty Works

The degree of vibrational excitation in the IBr fragment from the vibrational predissociation of NeIBr (A (3)PI(1)) has been measured using two-color pump-probe laser-induced fluorescence spectroscopy. We find that for the lowest initial vibrational states examined, DELTA-upsilon = -1 dissociation pathways dominate the dynamics, while this channel is closed for upsilon greater-than-or-equal-to 17. From this result, the A state binding energy (D0) of the complex is determined to be 67 +/- 4 cm-1, while that in the X electronic state is found to be 73 +/- 4 cm-1. The X state binding energy is identical to that for NeI2 and …

Hypercoordination In Group Iv Mh5 And Mh5- Systems, Marshall T. Carroll, Mark S. Gordon, Theresa L. Windus

Mark S. Gordon

The energetics and bonding of the group IV hypervalent MH5 and MH5- D3h structures (M = C, Si, Ge, Sn) are examined in this paper. Ab initio all-electron calculations are used to predict the energies and geometries of the systems. The resulting electron densities are analyzed using the topological theory of atoms in molecules. It is found that the anion energetically is more stable than the neutral radical for M = Si, Ge, and Sn but not for M = C. Further distinguishing carbon from the other members of the group is the fact that the CH bond mostly is …

Experimental And Theoretical Evidence In Support Of An Intermediate Complex In The Insertion Reaction Of Silylene Into Silane, R. Becerra, H. M. Frey, B. P. Mason, R. Walsh, Mark S. Gordon

Mark S. Gordon

The reaction between silylene, SiH2, and silane, SiH4, viz. SiH2 + SiH4 - Si2H6 (1) may reasonably be considered the prototype Si-H insertion process of silicon hydride chemistry. This reaction, which is also the second step in the thermolysis of silane1 leading ultimately to solid silicon and silicon hydride deposition, is known to be fast. Experimental measurements of the rate constant2-4 show the reaction to proceed at close to the collisional limit. Theoretical calculations of the energy surface for the decomposition of Si2H6 show that it possesses no energy barrier at the threshold of dissociation,5 which suggests a zero barrier …

Development Of A System For Survey Of Radon Concentration Of The Dayton Area Using A Liquid Scintillation Counter And Analysis Of The Data, Taewon Kim

Theses and Dissertations

A system to do a large scale survey was developed. The data obtained from the survey was analyzed using a database. The database incorporated an equation for converting cpm into radon concentration pCi/ℓ). The equation of conversion, protocol for measuring radon concentration, survey form, and a database program were modified (from previous theses) or developed for this thesis. The elution time constant, adsorption time constant, and calibration factor were calculated for equation of conversion. Two surveys were during the course of the thesis. On the first survey, the arithmetic average radon concentration with standard error of the mean was 2.9 …

Calculation Of Barriers To Proton Transfer Using Variations Of Multiconfiguration Self‐Consistent‐Field Methods. Ii. Configuration Interaction, K. Luth, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Various means are tested of including additional electron correlation into multiconfiguration self‐consistent‐field (MCSCF) methods for computing proton transfer potentials in HF₂⁻, H₇N₂⁺, H₃O₂⁻, and H₅O₂⁺. Configuration interaction allowing single excitations (CIS) and configuration interaction with single + double excitations (CISD) calculations are performed following MCSCF expansion of the wave function using various different MCSCF reference wave functions. The CISD results are excellent, being fairly independent of choice of reference space although it is important that the occupied orbitals be balanced between the …

Tem Observations Of The Mechanism Of Delamination Of Chromium Films From Silicon Substrates, D. Goyal, Alexander H. King

Alexander H. King

We have observed the complete delamination of polycrystalline chromium films from single crystal silicon substrates during deposition due to the formation of high internal stresses. These intrinsic stresses can give rise to interfacial defects which assist in the separation of the film from the substrate. Stresses in the film are balanced by stresses in the substrate, which cause mechanical failure in the substrate near the interface. Extensive arrays of dislocations and cracking of the substrate have been observed. We find that the delamination of the films from the substrate is initiated by the formation of damage in the substrate, rather …

Determining The Chemical Composition Of Cloud Condensation Nuclei, Allen L. Williams, Jane E. Rothert, Kent E. Mcclure, Darryl J. Alofs, Donald E. Hagen, Daniel R. White, A. R. Hopkins, Max B. Trueblood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This second progress report describes the status of the project one and one-half years after the start. The goal of the project is to develop the instrumentation to collect cloud condensation nuclei (CCN) in sufficient amounts to determine their chemical composition, and to survey the CCN composition in different climates through a series of field measurements. Our approach to CCN collection is to first form droplets on the nuclei under simulated cloud humidity conditions, which is the only known method of identifying CCN from the background aerosol. Under cloud chamber conditions, the droplets formed become larger than the surrounding aerosol, …

Evidence For Atomic Processes In Molecular Valence Double Ionization, U. Becker, Oliver Hemmers, B. Langer, A. Menzel, R. Wehlitz, W. B. Peatman

Environmental Studies Faculty Publications

Complete molecular valence-electron spectra were measured for CO. Unexpectedly, discrete lines at low kinetic energies were found, superimposed on a continuous energy spectrum representing direct double-ionization processes. The appearance of these lines is discussed in the context of the formation of the C⁺+O⁺ ion pair near its associated threshold at 38.4 eV. It is ascribed to valence-excited repulsive (CO⁺)^* states, which dissociate to a large part rapidly into atomic fragments before electronic relaxation takes place. From our spectra, partial cross sections for the different processes leading to dissociative valence double ionization are derived.

Mössbauer And Neutron Diffraction Studies Of Y₂(Fe₁₋ₓmnₓ)₁₄B, Oran Allan Pringle, Gaya Kanishka Marasinghe, Gary J. Long, William Joseph James, William B. Yelon, Decai Xie, Fernande Grandjean

Physics Faculty Research & Creative Works

We have used Mössbauer spectroscopy and neutron diffraction to study a series of Y₂(Fe_1-xMn_x)_{1 4}B samples in the composition range from x=0.0 to 0.4. Y ₂(Fe_0.6Mn_0.4)₁₄B is paramagnetic at both room temperature and 85 K. The iron quadrupole splitting in this paramagnetic compound allows us to place an upper limit on the quadrupole shift in the magnetic Y₂(Fe_1-xMn_x) ₁₄B alloys. Refinement of Y₂(Fe _1-xMn_x)₁₄B neutron diffraction data have been used to …

I. Removal Of Chromium From A Highly Contaminated Soil/Slag Matrix By Soil Washing At Low Ph, Ii. Removal Of Chromium From Impregnated Clay Matrices By Soil Washing At Low Ph, Erez Gotlieb

Theses

Section I. Chromium is a major soil contaminant of industrial sites in New Jersey, as well as in many of the Superfund sites throughout the United States. Removal of chromium by soil/slag washing with low pH sulfuric acid solutions is described. The extraction parameters are acid concentration, contact time, temperature, solvent/soil ratio, and acid type. The effect of two-stage extraction is discussed.

Soil/slag washing with sulfuric acid concentrations of 2% weight:volume (units are g/ml. This concentration is approximately equal to 0.4 N) at 75:1 v:w solvent/soil ratios yielded chromium extraction efficiencies of 95%, but 50% of the soil matrix was …

Selective No Absorption From Gas Streams With Tertiary Organic Hydroperoxide Solutions, Huihong Ao

Theses

The selective removal of nitric oxide from gas streams was investigated using 3,6-dimethyl-3-octyl hydroperoxide, p-menthane hydroperoxide, pinane hydroperoxide, and cumene hydroperoxide in solutions of n-hexadecane (cetane). The influence of different parameters such as temperature, gas stream flow rate (or residence time), and concentration of hydroperoxide compounds on efficiency of NO removal was evaluated. The basis of this research was to duplicate atmospheric reactions between hydroperoxides and NO in order to produce NO₂. We succeeded in removing NO from gas streams, but failed to produce NO₂. NO reacted with the hydroperoxides to produce nitrates. These nitrates are …

Characterization Of Low Pressure Chemical Vapor Deposited Silicon Dioxide Thin Films, Xue Du

Theses

LPCVD deposited amorphous silicon dioxide SiO₂ thin films from a new chemical vapor source, diethylsilane (DES), were characterized. This work is focused on evaluation of SiO₂ films prepared by varies deposition temperatures and flow rates series.

SiO₂ thin films were evaluated for density, porosity, and refractive index. Techniques for evaluation of the above mentioned parameters for this work included the use of infrared absorption spectroscopy, preferential etch procedures, optical measurement of refractive index and thickness, and thermal annealing of CVD films. The densification in vacuum ambient has been carried out at the temperature of 600 °, 750 …

Hplc Analysis Of Amino Acid-Derived Chloramines, Thomas Goyne, Suzanne Furness, Scott Miller, Matthew Nelsen

Thomas Goyne

No abstract provided.

Palladium(Ii) Catalysis, Glenn Noronha

Dissertations

No abstract provided.