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Observation by flow sup 1 H NMR and dimerization kinetics and products of reactive ortho-quinodimethanes and benzocyclobutadiene

Description: The reactive o-quinodimethanes, 1,2-dimethylene-1,2-dihydronaphthalene (9) and o-xylylene (1) were observed by flow {sup 1}H NMR spectroscopy at room temperature. The {sup 1}H NMR spectrum of 9 was obtained in the absence of precursor and dimers. However, the {sup 1}H NMR spectrum of the more reactive 1, generated in a similar manner from (o-((trimethylsilyl)methyl)benzyl)trimethylammonium iodide (5.) could be obtained only in the presence of its stable (4 + 2) and (4 + 4) dimers. The dimerizat… more
Date: September 21, 1990
Creator: Fischer, David
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Electrocatalysis of anodic oxygen-transfer reactions at modified lead dioxide electrodes

Description: The electrocatalytic activities were compared for pure and chloride-doped beta-PbO{sub 2} (Cl-PbO{sub 2}) films on gold and platinum substrates. Rate constants were increased significantly for oxidations of Mn{sup 2+}, toluene, benzyl alcohol, dimethylsulphoxide (DMSO) and benzaldehyde in acidic media by the incorporation of Cl{sup {minus}} into the oxide films. These reactions are concluded to occur by the electrocatalytic transfer of oxygen from H{sub 2}O to the reaction products. Results of … more
Date: September 21, 1990
Creator: Hsiao, Yun-Lin.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Magnetic and thermal properties of high Tc superconductors

Description: Measurements of the normal state magnetic susceptibility {chi}(T) of YBa{sub 2}Cu{sub 3}O{sub 7}, Bi{sub 1.8}Pb{sub 0.2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}, and Bi{sub 2{minus}x}Pb{sub x}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+{delta}} (x = 0.2 and 0.25) were carried out. All {chi}(T) data show negative curvature below {approximately}2{Tc}. The data for YBa{sub 2}Cu{sub 3}O{sub 7} are in excellent agreement with a new calculation of the superconducting fluctuation diamagnetism. From the analysis, … more
Date: September 21, 1990
Creator: Lee, Wonchoon
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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An investigation of the mechanisms of calcination and sulfation in coal-water mixtures

Description: The purpose of this investigation is to study the mechanisms of sulfur capture when burning coal-water-limestone mixtures (CWLM) in fluidized beds. Special care is taken to make comparisons with to dry coal and sorbent under comparable experimental conditions. A series of experiments were performed in an eight-inch diameter bubbling fluidized bed combustor to address this problem. 33 refs., 17 figs., 5 tabs.
Date: September 21, 1990
Creator: Christofides, N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A Search for Thermal Isomerization of Olefins to Carbenes: Thermal Generations of the Silicon-Nitrogen Double Bond

Description: The first part of this thesis will search for the thermal isomerization of olefins to carbenes which is predicted to be a high energy process by calculations and has only been observed in a few strained olefins. The possibility of thermal isomerization of simple olefins to carbenes will be explored. Substitution of a silyl group on the double bond of an olefin allows a potential intermediate which has a {beta}-radical to the silyl group during the cis-trans isomerization. The effects of a trime… more
Date: September 21, 1990
Creator: Zhang, Xianping
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Precipitation of jarosite-type double salts from spent acid solutions from a chemical coal cleaning process

Description: The precipitation of jarosite compounds to remove Na, K, Fe, and SO{sub 4}{sup 2{minus}} impurities from spent acid solutions from a chemical coal cleaning process was studied. Simple heating of model solutions containing Fe{sub 2}(SO{sub 4}){sub 3}, Na{sub 2}SO{sub 4}, and K{sub 2}SO{sub 4} caused jarosite (KFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}) to form preferentially to natrojarosite (NaFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}). Virtually all of the K, about 90% of the Fe, and about 30% of th… more
Date: September 21, 1990
Creator: Norton, G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Physical metallurgy and magnetic behavior of Cd stabilized bcc (beta)Gd alloys

Description: As a continuation of the research on bcc Gd-Mg alloy system by Herchenroeder and Gschneidner, the metastable bcc Gd-Cd alloys were studied with the emphasis on their metallurgical and magnetic properties. An essentially single phase alloy could be retained for Cd concentrations from 15 at. % Cd to 19 at. % Cd, which is in the vicinity of the eutectoid composition of {beta}Gd in the Gd-Cd system. The lattice constants obtained for these alloys were used to determine the lattice constant of pure … more
Date: September 21, 1990
Creator: Tang. Jinke
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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A reciprocal space approach for locating symmetry elements in Patterson superposition maps

Description: A method for determining the location and possible existence of symmetry elements in Patterson superposition maps has been developed. A comparison of the original superposition map and a superposition map operated on by the symmetry element gives possible translations to the location of the symmetry element. A reciprocal space approach using structure factor-like quantities obtained from the Fourier transform of the superposition function is then used to determine the best'' location of the sym… more
Date: September 21, 1990
Creator: Hendrixson, Ton
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Electrical Resistivity of Some Zintl Phase and the Precursors

Description: Resistivity measurements have been performed for electric characterization of the compounds Ba{sub 5}Sb{sub 3} and Ba{sub 5}Sb{sub 3}Cl, both with the Mn{sub 5}Si{sub 3} structure type, along with Ca{sub 5}Bi{sub 3} and Ca{sub 5}Bi{sub 3}F, both with the {beta}-Yb{sub 5}Sb{sub 3} structure type. These measurements were taken as a function of temperature using the four probe method on pressed polycrystalline pellets of the compounds. A sealed apparatus was developed for containing these air-sens… more
Date: September 21, 1990
Creator: Wolfe, Larry
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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High-resolution angle-resolved photoemission studies of high Tc superconductor Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8

Description: An angle-resolved photoemission study of the normal and superconducting states in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} was performed. Measurements in the normal state show bands dispersing through the Fermi level from at least 350 meV below E{sub F}. The Fermi level crossings are consistant with local-density band calculation, including a point calculated to be of Bi-O character. Additional measurements were made where bands crossed the Fermi level between 100 and 250K, along with measurements… more
Date: September 21, 1990
Creator: Liu, Rong
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Reactions of the excited state of polypyridyl chromium(III) ion

Description: There has been much recent interest in the photochemistry and photophysics of transition metal polypyridine complexes due to the possibility of their use in solar energy conversion systems. The excited state of these compounds are known to undergo useful electron transfer and energy transfer reactions. This work attempts to elucidate the mechanism of the quenching of *CrL{sub 3}{sup 3+} (where L = 2,2{prime}-bipyridine, 4,4{prime}-dimethyl-2,2{prime}-bipyridine, 1,10-phenanthroline, 5-chloro-1,… more
Date: September 21, 1990
Creator: Steffan, Carl
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Fundamental Investigations of Supported Monometallic and Bimetallic Catalysts by Proton Magnetic Resonance Spectroscopy

Description: Proton magnetic resonance spectroscopy, or nuclear magnetic resonance (NMR) of hydrogen, has been applied to investigate silica-supported Group VIII monometallic and Group VIII-Group IB bimetallic catalysts and alumina- and silica-supported platinum-rhenium bimetallic catalysts. Two adsorbed states of hydrogen, i.e., irreversible and reversible hydrogen, on the surfaces of monometallic Ru, Pt, and Cu particles and bimetallic Ru-Group Ib, Pt-Group Ib, and Pt-Re particles were observed directly v… more
Date: September 21, 1990
Creator: Wu, Xi
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Electrocatalysis of Anodic and Cathodic Oxygen-Transfer Reactions

Description: The electrocatalysis of oxygen-transfer reactions is discussed in two parts. In Part I, the reduction of iodate (IO{sub 3}{sup {minus}}) is examined as an example of cathodic oxygen transfer. On oxide-covered Pt electrodes (PtO), a large cathodic current is observed in the presence of IO{sub 3}{sup {minus}} to coincide with the reduction of PtO. The total cathodic charge exceeds the amount required for reduction of PtO and IO{sub 3}{sup {minus}} to produce an adsorbed product. An electrocatalyt… more
Date: September 21, 1990
Creator: Wels, Brian R.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Exclusive neutral strange particle production from double Pomeron exchange produced by proton-proton interactions at radical s = 62 GeV

Description: Data are presented for the first time on exclusive Pomeron-Pomeron interactions which produce a neutral strange and neutral antistrange particle pair in a central system X. In this paper, the system, X, is identified as one of the following neutral combinations; K{sub s}{sup 0}K{sub s}{sup 0}, K{sub s}{sup 0}K{sup {plus minus}}{pi}{sup {minus plus}}, {Lambda}{sup 0}{bar {Lambda}}{sup 0}, {Lambda}{sup 0}{bar {Lambda}}{sup 0}*. These data were obtained in proton-proton collisions at {radical}s = … more
Date: September 21, 1990
Creator: Skeens, John
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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The growth, structure, and thermal stability of vapor deposited ultra-thin metal films: Rh on Ag(100), Au on Pd(110), and Pt on Pd(110)

Description: The growth, structure, and thermal stability of ultra-thin metal films (Rh on Ag(100); Au on Pd(110) and Pt on Pd(110)) is investigated using surface sensitive techniques. The three systems studied present a variety of differing characteristics which can contribute to the growth mode, two-dimensional structure, and thermal stability of the films. The main factors contributing to the differing properties of the three systems presented here are: (1) the different substrate morphologies; (2) the d… more
Date: September 21, 1990
Creator: Schmitz, P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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High precision numerical solutions to electric fields in a radial drift chamber

Description: A modification to the proportional chamber design makes it possible to achieve 5{mu}m spatial resolution in particle tracking. Achieving this requires knowing exactly what the electric field is in the chamber, and simple approximations to the field are not accurate enough. The operation of the chamber and techniques which accurately evaluate the electric field are discussed.
Date: September 21, 1990
Creator: Faust, Jonathan
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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An analysis of commerical zeolite catalysts by multinuclear NMR

Description: This work involves studying two commercial hydrocracking catalysts by solid state multinuclear NMR silicon 29 and aluminum 27 with the goal of developing a method of determining the fraction zeolite in the catalysts. The zeolite fraction is known to be one of the faujasite zeolites type X or Y. The clay matrix of the catalyst is assumed to be kaolinite. Fresh, air-exposed commercial hydrocracking catalysts were provided by Phillips Petroleum. Sample 33351-86 was known to be a physical mixture o… more
Date: September 21, 1990
Creator: Flanagan, L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Platinum(II) complexes as spectroscopic probes for biomolecules

Description: The use of platinum(II) complexes as tags and probes for biomolecules is indeed advantageous for their reactivities can be selective for certain purposes through an interplay of mild reaction conditions and of the ligands bound to the platinum. The use of {sup 195}Pt NMR as a method of detecting platinum and its interactions with biomolecules was carried out with the simplest model of platinum(II) tagging to proteins. Variable-temperature {sup 195}Pt NMR spectroscopy proved useful in studying t… more
Date: September 21, 1990
Creator: Ratilla, Eva
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Synthesis, characterization, and reactivity of sulfided hexanuclear molybdenum cluster compounds

Description: Hexanuclear molybdenum clusters with mixed chloride and sulfide bridging ligands were prepared by reacting {alpha}-MoCl{sub 2} with sodium hydrosulfide in the presence of sodium butoxide. The resulting species, Mo{sub 6}Cl{sub (8-x)}S{sub x}{center dot}npy(x {congruent} 3.6, n {congruent} 4, py = pyridine), was pyrophoric and insoluble. The mixed sulfide chloride cluster species Mo{sub 6}S{sub 4}Cl{sub 4}{center dot}6OPEt{sub 3} and Mo{sub 6}S{sub {approximately}5}Cl{sub {approximately}3}{cente… more
Date: September 21, 1990
Creator: Spink, D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Cellular membrane trafficking of mesoporous silica nanoparticles

Description: This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the e… more
Date: June 21, 2012
Creator: Fang, I-Ju
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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