UNT Theses and Dissertations - 83 Matching Results

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The Synthesis and Reactivity of Bis(silyl)acetylenes

Description: Six bis(silyl)acetylenes with the following varied silicon substituents were prepared: I (Me, Me); II (H, H); III (Cl, H); IV (Cl, Cl); V (OMe, H); VI (OMe, OMe). While I and II may be prepared by the reaction of dilithio- or bis(bromomagnesium)-acetylide with appropriate chlorosilane, similar reactions designed to give III - VI give oligomers, YMe_2Si(C≡C-SiMe_2)_nY, VII, Y = Cl, OMe, as the major products indicating that the acetylenic functionality on silicon activates the chlorosilane towar… more
Date: May 1987
Creator: Albanesi, Todd E. (Todd Edward)
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Pressure Effects on Electric Field Spectra of Molecular Rydberg States

Description: Electric field studies, electrochromism, were used to obtain excited-state data for analogous divalent sulfur compounds. The sulfides investigated were dimethyl sulfide and small cyclic sulfides including the three to six member ring compounds. The excited-state dipole moments and polarizabilities are reported for the first s, p, and d Rydberg absorption bands which occur in the near vacuum ultraviolet region from 230 to 170 nm. The excited-state data are interpreted in terms of the particular … more
Date: December 1982
Creator: Altenloh, Daniel Dean
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Synthesis and Characterization of Copper(II) Complexes

Description: A series of dihydroxy bridged copper(II) complexes of the type [(L)Cu(OH)₂Cu(L)]x₂ * nH₂0, where L is 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine or 1,10-phenanthroline, x is a counter ion, and n is the number of water molecules, was synthesized. In the case of monohydroxy bridged copper(II) complexes, we have found a new method of synthesis for [ (L)₂Cu(OH)Cu(L)₂ ] (ClO₄)₃, where L is 2,2'-bipyridine or 1,10-phenanthroline. We have synthesized five new monohydroxy bridged copper(II) complex… more
Date: December 1984
Creator: Amani, Saeid
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Manufacturer [Sic] of Densified-Refuse Derived Fuel (d-RDF) Pellets and Methods for the Determination of d-RDF Pellet Densities

Description: There are 150 million tons of Municipal Solid Waste (MSW) annually produced in the United States, which is approximately equivalent to 150 million barrels of oil. MSW production is inexhaustible, and is increasing on an annual per capita basis of approximately three per cent. After controlling the moisture and adding a binder, the combustible portion of MSW was converted to pellets. The objects of this project were to 1) evaluate the binder, 2) prepare the pellets, and 3) evaluate the pellets w… more
Date: December 1986
Creator: Attili, Bassam Saleem
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Thermal and Flash Photolysis Studies of Ligand-Exchange Reactions of Substituted Metal Carbonyl Complexes of Cr and Mo

Description: Thermal and flash photolysis studies of ligand-substitution reactions of cis-(pip)(L)M(CO)_4 by L' (pip = piperidine; L, L' = CO, phosphines, phosphites; M = Cr, Mo) implicate square-pyramidal [(L)M(CO)_4], in which L occupies a coordination site in the equatorial plane, as the reactive species. In chlorobenzene (= CB) solvent, the predominant species formed after flash photolysis and a steady-state intermediate for the thermal reaction is cis—[(CB)(L)M(CO)_4], for which rates of CB-dissociatio… more
Date: May 1989
Creator: Awad, Hani H. (Hani Hanna)
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Studies on the Biological Activity of N-nitrosamines

Description: Two aspects of the biological activity of N-nitrosamines were studied. First, the effect of ascorbate on the mutagenicity of N-nitrosopiperidines was studied in the Ames Salmanella/ mammalian microsome mutagenicity test. The addition of ascorbate significantly enhanced the mutagenicity of these compounds. This enhancement was selective for N-nitrosamines suggesting a possible role of ascorbate in N-nitrosamine induced carcinogenicity. Second, the technique of velocity sedimentation in alkaline … more
Date: August 1980
Creator: Barton, Rodney A. (Rodney Alan)
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The Stereochemistry of Silenes and Alpha-Lithio Silanes

Description: When E- or Z-l-methyl-l-phenyl-2-neopentylsilene was generated by the retro-Diels-Alder vacuum-sealed tube thermolysis of its corresponding anthracene adduct, in the presence of various alkoxysilanes, only one diastereomeric adduct was formed in each case, showing that the reactions are stereospecific. An x-ray crystal structure of the methoxytriphenylsilane adduct of the E-silene confirmed its relative configuration as (R,S) or (S,R). This demonstrated that the addition of alkoxysilanes to sil… more
Date: May 1987
Creator: Bates, Tim Frank
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Photochemical Silene Syntheses

Description: We report the attempted syntheses of two photochemical dimethylsilene precursors, both of which are derived from polyphenyl silanorbornadiene skeletons. Possible synthetic schemes and our results are reported herein. Photolysis of 1,2-divinyl-1,1,2,2-tetramethyl-1,2-disilane at room temperature in a cyclohexane solution of 1,3-butadiene produces 1,1-dimethyl-2-(vinyldimethylsilylmethyl) silene which is trapped in high yields to afford the E- and Z-1,1-dimethyl-2-(vinyldimethylsilylmethyl)-3-vin… more
Date: August 1987
Creator: Bobbitt, Kevin L. (Kevin Lee)
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The Analysis of Fire Debris Using Nuclear Magnetic Resonance Spectroscopy

Description: This paper describes a new technique for analyzing fire debris using nuclear magnetic resonance (NMR) spectroscopy. Petroleum distillates, which are commonly used accelerants, were weathered, burned, and steamdistilled. These, as well as virgin samples of the accelerants, were analyzed by gas chromatography and nuclear magnetic resonance spectroscopy. In addition, solvent studies and detectibility limit studies were conducted. The use of NMR is described as a valuable adjunct to the existing me… more
Date: August 1981
Creator: Bryce, Kenneth L.
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Isolation and Characterization of Two Enzyme Proteins Catalyzing Oxido-Reduction at C-9 and C-15 of Prostaglandins from Swine Kidney

Description: Two swine kidney proteins (PI 4.8 and 5.8) both possessing 9-prostaglandin ketoreductase (9-PGKR) and 15-hydroxyprostaglandin dehydrogenase (15-PGDH) activities were purified to homogeneity. Purification increased specific activities in parallel. Molecular weight, subunit size, amino acid composition, coenzyme and substrate specificity and antigenicity of both proteins were similar. Gel filtration and SDS-polyacrylamide gel electrophoresis molecular weights of 29,500 and 29,000, respectively, s… more
Date: December 1980
Creator: Chang, David Guey-Bin
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Chromatographic and Spectroscopic Studies on Aquatic Fulvic Acid

Description: High Performance Liquid Chromatography (HPLC) was used to investigate the utility of this technique for the analytical and preparative separation of components of aquatic fulvic acids (FA). Three modes of HPLC namely adsorption, anion exchange and reversed phase were evaluated. Aquatic fulvic acids were either extracted from surface water and sediment samples collected from the Southwest of the U.S., or were provided in a high purity form from the USGS. On the adsorption mode, a major fraction… more
Date: August 1986
Creator: Chang, David Juan-Yuan
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Molecular Dynamics in the Liquid Phase by FT-NMR, FT-IR and Laser Raman Lineshape Analysis

Description: Nuclear magnetic resonance (NMR) provides a convenient probe for the study of molecular reorientation in liquids because nuclear spin-lattice relaxation times are dependent upon the details of molecular motion. The combined application of Raman and Infrared (IR) lineshape analysis can furnish more complete information to characterize the anisotropic rotation of molecules. Presented here are the studies of NMR relaxation times, together with Raman/IR Mneshape analysis of the solvent and temperat… more
Date: August 1988
Creator: Chen, Fu-Tseng Andy
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A Sythetic Study of a Cyclic Siloxydiyne and its Iron Carbonyl Complex

Description: The synthetic studies include the synthesis of the cyclic siloxydiyne, 3,3,5,5,8,8,10,10-octamethyl-4,9-dioxa-3,5,8,10-tetrasilacyclodeca-1,6- diyne [VI] and its novel iron carbonyl complex. In the preparation of [VI] by HBr promoted condensation of bis (methoxydimethylsilyl) acetylene, a minor product, a cyclic trimer was always formed along with the major product [VI]. No evidence of an equilibrium between the trimerization product and the dimerization product was found. Compound [VI] can rea… more
Date: December 1989
Creator: Chi, Xiang-yong
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Isolation, Physical and Chemical Characterization of Lecithin:Cholesterol Acyltransferase from Human Plasma

Description: The physiological role of LCAT has been the subject of a number of recent articles (Glomset, 1979; Nilsson-Ehle et al., 1980). According to most current theories, the enzyme functions in combination with high-density lipoproteins in the reverse cholesterol transport pathway which presumably returns peripheral cholesterol to the liver where cholesterol catabolism takes place. Despite the exciting potential for studies on the catalytic function and the nature of the enzyme-substrate complex, the … more
Date: December 1981
Creator: Chong, Kui Song
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Picosecond Spectroscopy of Rhodamine B

Description: A series of picosecond excite-probe experiments was performed on various concentrations of aqueous and ethanolic solutions of rhodamine B in order to determine the existence of dimerization in those solutions. The goals of the research presented in this dissertation were twofold. Initially, various techniques of time-resolved spectroscopy were to be employed to further characterize the ground and excited-state molecular properties of the aqueous RB dimer. The information obtained, and the techn… more
Date: December 1981
Creator: Clark, James Burton
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Kinetics and Mechanisms of Ligand Exchange Reactions of Chelate Complexes

Description: Certain ligand substitution reactions proceed to a complete displacement of the chelate ligand. Certain reactions proceed through a mechanism involving an initial fission of the tungsten-sulfur bond to afford a coordinatively-unsaturated intermediate which is rapidly attacked by chlorobenzene. The resulting solvated intermediate establishes an equilibrium which involves desolvation-solvation. Although main group organometallic chemistry has received a great deal of attention, this discussion wi… more
Date: May 1989
Creator: Cortés, José E. (José Enrique)
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The Quantitative Determination of Glass in Slag and Fly Ash by Infrared Spectroscopy

Description: The present study was aimed at developing a new inexpensive and accurate analytical method for determining the glass content of slag and fly ash. Infrared absorption spectroscopy using an internal standard proved to be the method of choice. Both synthetic and commercial slags and fly ashes were investigated.
Date: December 1983
Creator: Eberendu, Alexis N. R.
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Stereochemical Studies of Nitrosamines: The Induced Circular Dichroism of Achiral Nitrosasmines

Description: The induced circular dichroism (ICD) of several chiral nitrosamines and various chiral reagents has been investigated. The interaction is attributed to a 1:1 hydrogen bonded complex between the NO group of the nitrosamine and the hydroxyl groups of alcohols and polyols, or the amino group of amines. Only those chiral reagents possessing large differences in size of the groups about the hydrogen bonding site contributed to CD anomalies. The acyclic 2-octanols did not give observable Cotton effec… more
Date: August 1980
Creator: Fribush, Howard M.
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Simultaneous Part-Per-Billion Determination of Sodium and Chloride Ions

Description: The method utilizes both cation and anion concentrator columns in parallel as a preconcentration system. The preconcentrator system is loaded using a reagent delivery module operated for a specific time at a preset flow rate. Total injection volumes of 2-5 ml are routinely used. Various chromatograms are discussed along with detailed information concerning detection limits for sodium and chloride, the system operating conditions, and the solutions to other pitfalls which have arisen during the … more
Date: August 1987
Creator: Gan, Din-Chung
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Intramolecular 2+2 Cycloadditions of Ketenes

Description: The objective of this study was to explore intramolecular ketene cycloadditions with the anticipated results of developing new synthetic methodology for the synthesis of polycyclic compounds difficult to obtain by other procedures. (o-Alkenylphenoxy)ketenes were initially selected for this study because these ketenes provided a favorable proximity for the intramolecular [2+2] cycloaddition reactions. The difunctional precursors, (o-alkenylphenoxy)- acetic acids, were readily prepared from o-alk… more
Date: December 1986
Creator: Giang, Yun-Seng F. (Yun-Seng Frank)
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Separation and Characterization of Variant Forms of Phosphoglucose Isomerase: Purification and Structural Analysis of Active Site Peptides from Human and Rabbit Phosphoglucose Isomerase

Description: A method has been developed for the rapid, quantitative separation of normal and abnormal phosphoglucose isoemrase allozymes from individuals heterozygous for genetic variant forms of the enzyme. The method utilizes a substrate gradient elution of the enzyme from carboxymethyl Biogel and is far superior in terms of resolution and recovery to methods based on electrophoresis and isoelectric focusing. Four different genetic variant forms of the enzyme were isolated and subjected to a systematic c… more
Date: May 1980
Creator: Gibson, David R.
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Calcium Aluminates Synthesis, Characterization, and Hydration Behavior

Description: The hydration behavior of the calcium aluminates as a function of the glass content, the curing temperature, and the water-solid ratio was investigated. In order to keep them from influencing the results, the free-lime content and the surface area of all samples were kept constant, whenever possible. Samples were hydrated with a water-solid ratio of 10/1 for periods of 1 to 90 days. Three curing temperatures were studied; 2°C, 25°C, and 50°C. Samples were hydrated in tightly sealed polyethylene… more
Date: December 1984
Creator: Griffin, Joseph George
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Intramolecular [2+2] Cycloadditions of Phenoxyketenes and Intermolecular [2+2] Cycloadditions of Aminoketenes

Description: One objective of this study was to explore the intramolecular [2+2] cycloadditions of phenoxyketenes to carbonyl groups with isoflavones and benzofurans as target compounds. The other objective was to investigate the eyeloaddition reactions of rarely studied aminoketenes. The conversion of 2-(carboxyalkoxy)benzils to the corresponding phenoxyketenes leads to an intramolecular [2+2] cycloaddition to ultimately yield isoflavones and/or 3-aroylbenzofurans. The product distributions are dependent … more
Date: May 1989
Creator: Gu, Yi Qi
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Synthesis and Reactions of Some N-Nitrosamines

Description: Nucleophiles react with the α-acetoxy derivative of α-hydroxybenzylbenzylnitrosamine at the carbonyl carbon of the acetoxy moiety followed by fragmentation to the very same intermediates formed by oxidative metabolism. Since α-acetoxybenzylbenzylnitrosamine has been shown to be able to acylate nucleophiles and since the nucleic acids are nucleophiles, then it is possible that this compound may cause mutations by an acylation pathway instead of or in addition to the more common alkylation pathwa… more
Date: December 1982
Creator: Gunn, Valerie E. (Valerie Elizabeth)
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