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The Analysis of Volatile Impurities in Air by Gas Chromatography/Mass Spectrometry

The determination of carbon monoxide is also possible by trapping CO on preconditioned molecular sieve and thermal desorption. Analysis in this case is performed by gas chromatography/mass spectroscopy, although the trapping technique is applicable to other suitable GC techniques.

Date: May 1993

Creator: Talasek, Robert Thomas

Item Type: Thesis or Dissertation

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A Materials Approach to Silicon Wafer Level Contamination Issues from the Wet Clean Process

Semiconductor devices are built using hyperpure silicon and very controlled levels of doping to create desired electrical properties. Contamination can alter these precisely controlled electrical properties that can render the device non-functional or unreliable. It is desirable to determine what impurities impact the device and control them. This study consists of four parts: a) determination of acceptable SCI (Standard Clean 1) bath contamination levels using VPD-DSE-GFAAS (Vapor Phase Decomp… more

Date: December 1996

Creator: Hall, Lindsey H. (Lindsey Harrison)

Item Type: Thesis or Dissertation

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Thermodynamic Properties of Nonelectrolyte Solutes in Ternary Solvent Mixtures

The purpose of this dissertation is to investigate the thermodynamic properties of nonelectrolyte solutes dissolved in ternary solvent mixtures, and to develop mathematical expressions for predicting and describing that behavior in the solvent mixtures. Thirty-four ternary solvent systems were studied containing either alcohol (1-propanol, 2-propanol, 1-butanol, and 2-butanol), alkane (cyclohexane, heptane, and 2,2,4-trimethylpentane) or alkoxyalcohol (2-ethoxyethanol and 2-butoxyethanol) cosol… more

Date: August 1999

Creator: Deng, Tʻai-ho

Item Type: Thesis or Dissertation

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Aluminum and Copper Chemical Vapor Deposition on Fluoropolymer Dielectrics and Subsequent Interfacial Interactions

This study is an investigation of the chemical vapor deposition (CVD) of aluminum and copper on fluoropolymer surfaces and the subsequent interfacial interactions.

Date: December 1997

Creator: Sutcliffe, Ronald David

Item Type: Thesis or Dissertation

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Experimental and Theoretical Studies of Polycarbocyclic Compounds

Part I. Diels-Alder cycloadditions of 1,2,3,4,9,9-hexachloro-1α,4α,4aα,8aβ-tetrahydro-l,4-methanonaphthalene (32) and 1,2,3,4,9,9-hexachloro-lα,4α,6,7- tetrahydro-l,4-methanonaphthalene (33) to 4-methyl- and 4-phenyl-l,2,4-triazoline-3,5-dione [MTAD and PTAD, respectively] and to N-methylmaleimide (NMM) have been studied. The structures of several of the resulting cycloadducts were determined by X-ray crystallographic methods. The observed stereoselectivity of each of these Diels-Alder reaction… more

Date: May 1998

Creator: Shukla, Rajesh, 1964-

Item Type: Thesis or Dissertation

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Interactions of Clean and Sulfur-modified Reactive Metal Surfaces with Aqueous Vapor and Liquid Environments : A Combined Ultra-high Vacuum/electrochemistry Study

The focus of this research is to explore the molecular-level interactions between reactive metal surfaces and aqueous environments by combined ultra-high vacuum/electrochemistry (UHV-EC) methodology. The objectives of this work are to understand (1) the effects of sulfate ions on the passivity of metal oxide/hydroxide surface layer, (2) the effects of sulfur-modification on the evolution of metal oxide/hydroxide surface layer, and (3) the effects of sulfur adsorbate on cation adsorption at meta… more

Date: May 1998

Creator: Lin, Tien-Chih, 1966-

Item Type: Thesis or Dissertation

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Adsorbate-enhanced Corrosion Processes at Iron and Iron Oxide Surfaces

This study was intended to provide a fuller understanding of the surface chemical processes which result in the corrosion of ferrous materials.

Date: December 1994

Creator: Murray, Eric

Item Type: Thesis or Dissertation

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Ligand Substitution Studies in the Tetracobalt Cluster Co₄(CO)₁₀([mu]₄-PPh₂) and Synthesis and Reactivity Studies in the Fe₂Pt and FeCo₂ Mixed-metal Clusters

The kinetics of ligand substitution for CO in Co4(CO)10(mu4-PPh2) , 1, have been investigated for the ligands P(OMe)3, P(OEt)3, PPh2H, P(0-i-Pr)3, P(n-Bu)3, PPh3, P(i-Pr)3, and PCy3 over a wide temperature range.

Date: August 1991

Creator: Don, Ming-jaw

Item Type: Thesis or Dissertation

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The Development of Predictive Models for the Acid Degradation of Chrysotile Asbestos

The purpose of this study was to determine the factors affecting the acid degradation of chrysotile asbestos (Mg_3Si_2O_5(OH_4)) . Millions of tons of asbestos have found use in this country as insulative or ablative material. More than 95 percent of the asbestos in use is of the chrysotile variety. The remaining 5 percent is composed of various types of fibrous amphiboles. The inhalation of asbestos can lead to several diseases in humans. Asbestosis, lung cancer and mesothelioma are the most c… more

Date: May 1993

Creator: Ingram, Kevin D. (Kevin Dean)

Item Type: Thesis or Dissertation

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Survey of the Solid State Conformation of Calix[4]arenes

The characteristics of seventy-six calix[4]arene crystal structures derived from the Cambridge Crystallographic Database are presented. This survey is a discussion of the inter and intramolecular effects on the solid state cavity shape and molecular recognition ability of the compounds. In addition to this survey, four new calix[4]arene crystal structures are presented. The conformational characteristics of these four calixarenes are determined by a complicated array of inter and intramolecular… more

Date: August 1997

Creator: Obrey, Stephen J. (Stephen James)

Item Type: Thesis or Dissertation

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Conformational Analogs of Some Phytoactive Compounds

In an effort to determine if there is a specific conformational structure which is most effective at the appropriate active physiological site, the synthesis of a group of sterically restricted analogs was undertaken. A portion of the polymethylene carbon skeleton of glutaric acid was replaced by selected aromatic carbons in benzenedicarboxylic acids to produce a series of ridged conformers, and the relative plant growth regulating properties of these derivatives were determined.

Date: August 1973

Creator: Skelton, Wm. Paul

Item Type: Thesis or Dissertation

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Spectrofluorometric and Solubility Studies of Polycyclic Aromatic Hydrocarbons in Hydrogen Bonded Binary Solvent Mixtures

The purpose of this dissertation is to investigate the behavior of polycyclic aromatic hydrocarbons (PAHs) in binary solvent systems and determine and/or develop predictive mathematical expressions for describing solutions in which hydrogen-bonding occurs.

Date: May 1997

Creator: Powell, Joyce R., 1968-

Item Type: Thesis or Dissertation

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Solution Studies of the Structures and Stability of Mixed Lithium Alkoxide/Alkvllithium Aggregates

New one- and two-dimensional NMR techniques were used to elucidate the solution structures of these complex mixtures. The system, lithium tert-butoxide/tert-butyllithium, was studied as a model system with O/Li ratios varying from 0/1 to 1/1. It was found that at low O/Li ratios, a single mixed tetrameric aggregate was formed. At higher O/Li ratios, mixed hexameric species were formed. Two other systems, lithium isopropoxide/iso-propyllithium and lithium n-propoxide/n-propyllithium were also st… more

Date: December 1992

Creator: DeLong, George T. (George Thomas)

Item Type: Thesis or Dissertation

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Syntheses of Antimetabolites

In these studies several different types of antimetabolites were synthesized, and their biological effects were examined in various assay systems. More extensive investigations were done in microbial systems in which many of the compounds proved to be inhibitory to growth, and attempts were made to determine the mode of biochemical action by adding supplements of the appropriate natural metabolite.

Date: January 1970

Creator: Clifton, George Gil

Item Type: Thesis or Dissertation

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Substitution Chemistry of the Cobalt Complexes [Co₂(CO)₆(PhC≡CR) (R=Ph, H) and PhCCo₃(CO)₉] with the Diphosphine Ligands [Bis(diphenylphosphino)maleic Anhydride (BMA) and (Z)-Ph₂PCH=CHPPh₂]. Reversible Chelate-to-Bridge Diphosphine Ligand Exchange, Phosphorus-Carbon Bond Cleavage and Phosphorus-Carbon Bond Formation

The tricobalt cluster PhCCo3(CO)9 (1) reacts with the bidentate phosphine ligand 2,3-bis(diphenylphosphino)maleic anhydride (bma) in the presence of added Me3NO to give the diphosphine-substituted cluster PhCCo3(CO)7(bma) (2). Cluster 2 is unstable in solution, readily losing CO to afford Co3(CO)6[(μ2-η2/η1-C(Ph)C=C(PPh2)C(O)OC(O)](μ2-PPh2) (3) as the sole observed product. VT-31P NMR measurements on cluster 2 indicate that the bma ligand functions as both a chelating and a bridging ligand. At … more

Date: December 1994

Creator: Yang, Kaiyuan

Item Type: Thesis or Dissertation

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Combined Electrochemistry and Spectroscopy of Complexes and Supramolecules containing Bipyridyl and Other Azabiphenyl Building Blocks

A group of azabiphenyl complexes and supramolecules, and their reduced and oxidized forms when possible, were characterized by cyclic voltammetry and electronic absorption spectroscopy. The oxidized and reduced species, if sufficiently stable, were further generated electrochemically inside a specially designed quartz cell with optically transparent electrode, so that the spectra of the electrochemically generated species could be taken in situ. Assignments were proposed for both parent and pro… more

Date: August 1995

Creator: Yang, Lei

Item Type: Thesis or Dissertation

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An Approach Towards the Total Synthesis of Clonostachydiol

The syntheses of the unsymmetrical 14-membered bismacrolides have been reviewed. A total synthesis of clonostachydiol, the latest to join this family, has been attempted using trimethylsilyl acetylene as the builiding block and palladium catalyzed reactions for the formation of key bonds. The alkyne groups were introduced by Stille coupling of trimethylstannylethynyltrimethylsilane with an acid chloride for one fragment and by addition of lithiotrimethylsilyl acetylene to an aldehyde for the ot… more

Date: August 1995

Creator: Maiti, Tushar B. (Tushar Baran)

Item Type: Thesis or Dissertation

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Synthesis and Study of Bioactive Compounds: I. Pyrethroids; II. Glutathione Derivatives

Part I: In the first study of pyrethroids, twenty-one novel pyrethroid esters bearing strong electron-withdrawing groups (e.g., halomethylketo and nitro groups) in the double bond side chain of the cyclopropane acid moiety have been synthesized and evaluated for insect toxicity. Rather than the usually employed Wittig reaction for these syntheses, the novel pyrethroid acid moieties were prepared by amino acidcatalyzed Knoevenagel condensations under mild conditions. In the second study of pyre… more

Date: May 1995

Creator: Chyan, Ming-Kuan

Item Type: Thesis or Dissertation

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Stabilization of Different Lead Compounds in Portland Cement

This research investigated the chemistries and mechanisms involved in lead-cement systems through the study of a larger number of lead compounds.

Date: August 1993

Creator: Zhao, Baoshu (Baoshu Eric)

Item Type: Thesis or Dissertation

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Magnetic Exchange in Oxovanadium(IV) Complexes with N-Salicylideneamino Acids

Copper(II) and oxovanadium(IV) ions resemble one another magnetically in having one unpaired electron in their complexes irrespective of their geometrical structures and bond types involved. Copper(II) complexes with antiferromagnetic exchange are well known. On the contrary, antiferromagnetic exchange in oxovanadium(IV) complexes is rather new and not well established. Very few oxovanadium(IV) complexes have been reported to have this anomalous magnetic property. In the investigation of the ma… more

Date: January 1968

Creator: Hu, James Hung-Jen

Item Type: Thesis or Dissertation

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Spectroscopic Properties of Polycyclic Aromatic Compounds

The fluorescence spectrum of many polycyclic aromatic compounds (PACs) depends upon solvent polarity. The emission spectrum of PAC monomers consists of several major vibronic bands labeled I, II, etc., in progressive order. Emission intensity enhancement of select bands is observed in polar solvents.

Date: May 1994

Creator: Tucker, Sheryl A. (Sheryl Ann)

Item Type: Thesis or Dissertation

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Kinetics and Mechanisms of Metal Carbonyls

Pulsed laser flash photolysis with both visible and infrared detection has been applied to the study of the displacement of weakly coordinating ligands (Lw) by strongly "trapping" nucleophiles (Ls) containing either an olefinic functionality (Ls = 1-hexene, 1-decene, 1-tetradecene) or nitrogen (Ls = acetonitrile, hydrocinnamonitrile) from the photogenerated 16 electron pentacarbonylchromium (0) intermediate. 5-Chloropent-l-ene (Cl-ol), a potentially bidentate ligand, has been shown to form (ol-… more

Date: May 1998

Creator: Ladogana, Santino

Item Type: Thesis or Dissertation

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Mobile Order Theory as Applied to Polycyclic Aromatic Heterocycles

Experimental mole fraction solubilities of benzil, thianthrene, trans-stilbene, thioxanthen-9-one, diphenyl sulfone and dibenzothiophene sulfone are determined in pure noncomplexing and complexing solvents. Predicted solubility values are calculated for benzil, thianthrene, trans-stilbene and thioxanthen-9-one using expressions derived from Mobile Order theory. Large deviations between experimental and predicted solubilities in alcohol solvents exist, therefore optimized solute - solvent associ… more

Date: August 1997

Creator: Fletcher, Kristin A.

Item Type: Thesis or Dissertation

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Chemical Equilibria in Binary Solvents

Dissertation research involves development of Mobile Order Theory thermodynamic models to mathematically describe and predict the solubility, spectral properties, protonation equilibrium constants and two-phase partitioning behavior of solutes dissolved in binary solvent mixtures of analytical importance. Information gained provide a better understanding of solute-solvent and solvent-solvent interactions at the molecular level, which will facilitate the development of better chemical separation… more

Date: August 1997

Creator: McHale, Mary E. R.

Item Type: Thesis or Dissertation

UNT Libraries - 762 Matching Results

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The Analysis of Volatile Impurities in Air by Gas Chromatography/Mass Spectrometry

A Materials Approach to Silicon Wafer Level Contamination Issues from the Wet Clean Process

Thermodynamic Properties of Nonelectrolyte Solutes in Ternary Solvent Mixtures

Aluminum and Copper Chemical Vapor Deposition on Fluoropolymer Dielectrics and Subsequent Interfacial Interactions

Experimental and Theoretical Studies of Polycarbocyclic Compounds

Interactions of Clean and Sulfur-modified Reactive Metal Surfaces with Aqueous Vapor and Liquid Environments : A Combined Ultra-high Vacuum/electrochemistry Study

Adsorbate-enhanced Corrosion Processes at Iron and Iron Oxide Surfaces

Ligand Substitution Studies in the Tetracobalt Cluster Co₄(CO)₁₀([mu]₄-PPh₂) and Synthesis and Reactivity Studies in the Fe₂Pt and FeCo₂ Mixed-metal Clusters

The Development of Predictive Models for the Acid Degradation of Chrysotile Asbestos

Survey of the Solid State Conformation of Calix[4]arenes

Conformational Analogs of Some Phytoactive Compounds

Spectrofluorometric and Solubility Studies of Polycyclic Aromatic Hydrocarbons in Hydrogen Bonded Binary Solvent Mixtures

Solution Studies of the Structures and Stability of Mixed Lithium Alkoxide/Alkvllithium Aggregates

Syntheses of Antimetabolites

Combined Electrochemistry and Spectroscopy of Complexes and Supramolecules containing Bipyridyl and Other Azabiphenyl Building Blocks

An Approach Towards the Total Synthesis of Clonostachydiol

Synthesis and Study of Bioactive Compounds: I. Pyrethroids; II. Glutathione Derivatives

Stabilization of Different Lead Compounds in Portland Cement

Magnetic Exchange in Oxovanadium(IV) Complexes with N-Salicylideneamino Acids

Spectroscopic Properties of Polycyclic Aromatic Compounds

Kinetics and Mechanisms of Metal Carbonyls

Mobile Order Theory as Applied to Polycyclic Aromatic Heterocycles

Chemical Equilibria in Binary Solvents