UNT Libraries - 26 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)
Item Type: Refine your search to only Thesis or Dissertation
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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)
Item Type: Refine your search to only Thesis or Dissertation
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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
Item Type: Refine your search to only Thesis or Dissertation
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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)
Item Type: Refine your search to only Thesis or Dissertation
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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.
Item Type: Refine your search to only Thesis or Dissertation
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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
Item Type: Refine your search to only Thesis or Dissertation
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The Electronic Spectrum of (-)-S-(pS)-2,5,3',6'-Tetrahydro-2.2-Paracyclophane-2-Carboxylic Acid

Description: A new, efficient route was used in the synthesis of [2.2]-paracyclophane-2-carboxylic acid. The acid as then resolved and the Birch reduction performed yielding one enantiomer of tetrahydro-[2.2]-paracyclophane-2-carboxylic acid. The ultraviolet spectrum of tetrahydro-[2.2]-paracyclophane- 2-carboxylic acid in isopenthane shows one absorption at 206 nm (Emax = 5,271). There are three bands observed in the circular dichroism spectrum in isopentane at 236 nm ([] = 1.8 X 104), 201 nm ([0] = -16 X … more
Date: May 1980
Creator: Hall, Lindsey
Item Type: Refine your search to only Thesis or Dissertation
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Vibrational Dephasing of Haloalkanes and Halobenzenes

Description: The Raman linewidths of the carbon-halogen stretching mode was measured as a function of temperature in ethyl bromide, isopropyl chloride, isopropyl bromide, t-butyl chloride, t-butyl bromide, chlorobenzene, bromobenzene, iodobenzene and o-dichlorobenzene. The vibrational relaxation times showed a very clear trend. Together with earlier work on methyl iodide, these results provide evidence that the vibrational dephasing efficiencies (T^-1_iso) of the carbon-halogen mode vary in the order of Cl … more
Date: May 1983
Creator: Ho, Salina Yuen-Han
Item Type: Refine your search to only Thesis or Dissertation
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The Photolytic Ozonation of Organics in Aqueous Solutions

Description: The aim of the investigation described in this work is to gain a better understanding of the processes involved in the oxidation of organic compounds by photolytic ozonation in a laboratory scale reactor. The results and discussions are presented in Chapter III. This chapter contains four parts. In the first part, mass transfer efficiency and the calculation of the mass transfer coefficient, KLa, as well as the ozone decomposition rate constant, KD, are presented and compared with those obtaine… more
Date: May 1980
Creator: Huang, Francis Y.
Item Type: Refine your search to only Thesis or Dissertation
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Studies on Lipoprotein Specificity of Human Plasma Lecithin Cholesterol Acyltransferase

Description: Huian plasma high-density lipoprotein (HDL) were isolated by a procedure employing polyanion precipitation and column chromatography. Lipid and protein composition of the HDL isolated by this method was found to be similar to another HDL preparation isolated by ultracentrifugation. However, minor differences were noted, including a higher phospholipid and apoproteinE content and lower triglyceride content of the HDL isolated by column chromatography. Four subfraction of HDL were obtained follow… more
Date: May 1981
Creator: Jahani, Mehrnoosh
Item Type: Refine your search to only Thesis or Dissertation
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Synthesis and Structure of Polynitro- and Polymenthylpolycyclic "Cage" Monomers and Polymers

Description: The objective of this study was to synthesize and characterize new energetic polycyclic "cage" compounds. As part of a program involved in the synthesis of new polynitropolycyclic compounds, 2,6-dinitro-5-methoxy- 7-carbomethoxypentacyclo[5. 3 .0 . 0* • * . CP • i ° . 0* •8]decane has been synthesized. This is a model system which can be used to study (1) the effect of nitro substitution on the photolability of carbon-carbon double bonds and (2) to develop methods for avoiding Haller-Bauer clea… more
Date: May 1987
Creator: Jin, Pei-Wen
Item Type: Refine your search to only Thesis or Dissertation
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Methods Development for Simultaneous Determination of Anions and Cations by Ion Chromatography

Description: The problem with which this research is concerned is the determination of inorganic anions and cations with single injection ion chromatography. Direct detection of the separated analyte ions occurs after the analyte ions have passed through ion-exchange resins where they are separated according to their affinity for the ion-exchange resin active sites. The techniques involve the use of essentially a non-suppressed ion chromatographic system followed by a suppressed ion chromatographic system. … more
Date: May 1987
Creator: Jones, Vonda K. (Vonda Kaye)
Item Type: Refine your search to only Thesis or Dissertation
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Evaluation of Adsorption and Microcoulometric Methods for Determination of Halogenated Organic Compounds in Water

Description: Two adsorption/microcoulometric methods have been investigated for total organic halogen (TOX) in water. TOX, a proposed water-quality parameter, is a rapid, surrogate method to detect halides microcoulometrically and does not require compound identification before water quality can be judged. An XAD resin is used to concentrate organic halides that are eluted by a two-step, two-solvent procedure, followed by analysis using :chromatography or pyrolysis to convert organic halides to halide. In t… more
Date: May 1980
Creator: Kinstley, Warren O. (Warren Owen)
Item Type: Refine your search to only Thesis or Dissertation
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Purification and Studies of Methylglyoxal Reductase from Sheep Liver

Description: The objectives of these investigations were (1) the purification of MG reductase from sheep liver and (2) studies of some of its characteristics. MG reductase was purified 40 fold and showed a single band on SDS-PAGE. Molecular weight estimations with SDS-PAGE showed a molecular weight of 44,000; although gel filtration with Sephadex G-150 gave a molecular weight of 87,000 indicating that the enzyme might be a dimer. The Km for MG is 1.42 mM and for NADH it is 0.04 mM. The pH optimum for the pu… more
Date: May 1983
Creator: Lambert, Patricia A.
Item Type: Refine your search to only Thesis or Dissertation
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The Effect of Ozonation in Reducing Trihalomethane Formation Potential

Description: Trihalomethanes such as chloroform, dichlorobromomethane, dibromochloromethane, and bromoform are formed when natural water is chlorinated in water treatment. This investigation explores the use of ozone to remove organic precursors from natural water, thus decreasing trihalomethane formation potential. The data suggest a mechanism involving formation of secondary precursors after prolonged contact with ozone, suggesting that trihalomethane precursors may be minimized by using low doses of ozon… more
Date: May 1981
Creator: Lin, Simon H.
Item Type: Refine your search to only Thesis or Dissertation
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The Nature of Intermediates Produced Through Ligand-Substitution Reactions of Octahedral Metal Carbonyls

Description: Pulsed laser time-resolved ligand-substitution photochemistry for (DTO)W(CO)4, (DTN)W(CO)4, and (NP)Mo(CO)4 (DTO = 2,2,7,7-tetramethyl-3,6-diathiaoctane; DTN = 2,2,8,8- tetramethyl-3,7-diathianonane; NP = l-diethylamino-2- diphenylphosphinoethane) proceeds via initial fission of the W-S and Mo-P bonds, affording Cs and C4v five-coordinate intermediates for DTN and NP but largely Cs for DTO. The rates of reaction of these intermediates, via chelate ring closure and competitive bimolecular intera… more
Date: May 1986
Creator: Mansour, Saber E. (Saber El-Sayed)
Item Type: Refine your search to only Thesis or Dissertation
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Analysis of PAH and PCB Emissions from the Combustion of dRDF and the Nondestructive Analysis of Stamp Adhesives

Description: This work includes two unrelated areas of research. The first portion of this work involved combusting densified refuse derived fuel (dRDF) with coal and studying the effect that Ca(0H)2 binder had on reducing polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) emissions. The second area of work was directed at developing nondestructive infrared techniques in order to aid in the analysis of postage stamp adhesives. With Americans generating 150-200 million tons a year of Mu… more
Date: May 1989
Creator: Poslusny, Matthew
Item Type: Refine your search to only Thesis or Dissertation
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An NMR Investigation of Aryl Mercury Compounds

Description: A variable temperature ^13 C and ^199 Hg NMR study has been conducted for diphenyl-, bis(o-tolyl)-, bis(m-tolyl)-, and bis(2, 6-xylyl)mercury in dimethyl sulfoxide and 1,1,2,2 tetrachloroethane; ^13 C T1 relaxation times are reported as a function of temperature. Barriers to rotation of the aryl rings are obtained. Chemical shifts and couplings in CDCl_3 are given for bis(p-tolyl)-, bis(2, 5-xylyl)-, bis(mesityl)-,phenyl(o-tolyl)-, phenyl(m-tolyl)mercury, and the compounds listed above. The ste… more
Date: May 1987
Creator: Rowland, Keith E. (Keith Edward)
Item Type: Refine your search to only Thesis or Dissertation
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Hydraulic Activity in Synthetic and Commercial Slags

Description: Slag, by itself, shows very little hydraulic activity. However, hydration is greatly accelerated by incorporation of the slag with Portland cement. This phenomenon is due to the activating role of calcium hydroxide released from the hydration of Portland cement. This study was aimed at finding other activators that will increase hydration in both synthetic and commercial slags. The effects of chemical composition and the aggregation state of the slag on the hydration process were also investiga… more
Date: May 1982
Creator: Saad, Bahruddin bin
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Synthesis of Aziridine Analogues of Pyrethroids

Description: Rules which correlate structure and insecticidal activity of pyrethroids have evolved over the last thirty years from the results obtained in the testing of various synthetic pyrethroids. The major portion of these rules have dealt either with the development of new alcohol moieties or variations in the unsaturated side chain of the cyclopropane ring. There has been very little work done concerning modifications of the cyclopropane ring. This study was initiated to discover the affect of substi… more
Date: May 1981
Creator: Sheppard, Rex Gerald
Item Type: Refine your search to only Thesis or Dissertation
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The Regulation of HMG-CoA Reductase by Enzyme-Lipid Interactions

Description: The temperature-dependent catalytic activity of rat liver 3-hydroxy-3 -methylglutaryl coenzyme A reductase (HMG-CoA reductase) displays the nonlinear Arrhenius behavior characteristic of many membrane-bound enzymes. A two-conformer equilibrium model has been developed to characterize this behavior. In the model, HMG-CoA reductase undergoes a conformational change from a low specific activity to a high specific activity form. This conformation change is apparently driven by a temperature-depende… more
Date: May 1981
Creator: Smith, Vana L.
Item Type: Refine your search to only Thesis or Dissertation
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Methods Development for Ion Chromatography

Description: Ion chromatography (IC) as developed by Small et. al. in 1975 has become an efficient and reliable analytical technique for simultaneous analysis of multiple ions in solution. The principle requirement prior to use the IC for an analysis is sample preparation; these include sample decomposition, solvent extraction, and trapping in case the target element is in the gas phase, etc. Solvent extractions for fluoride, chloride, sodium, ammonium, and potassium ions which are soluble in soils are desc… more
Date: May 1986
Creator: Supachai Maketon
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Syntheses of Highly Strained Energetic Molecules and Development of New Synthetic Methodology

Description: The objective of this study was to synthesize new energetic, strained, saturated polycyclic compounds. For this purpose, new methodology has been developed, as follows: (i) Ketenes have been generated in situ via treatment of aldo-, keto- or alkenoic acid with either toluenesulfonyl chloride or 2-chloro-1-methylpyridfniurn iodide (Mulkaiyama's reagent). The reactive intermediates thereby generated have been found to undergo intramolecular [2+2] cycloaddition reactions in these systems.
Date: May 1987
Creator: Wu, An-hsiang
Item Type: Refine your search to only Thesis or Dissertation
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