Physical Sciences and Mathematics Commons^™

Thermodynamic And Electrochemical Studies Of Niobium In Molten Fluorides And Chloroaluminates, Gann Ting

Doctoral Dissertations

The oxide chemistry of niobium(V) has been studied in molten LiF-BeF₂ mixtures. The stoichiometry of an oxygen-containing niobium(V) species (NbO₂F) has been established in molten Li₂BeF₄ from the heterogeneous equilibrations of NiNb₂o₆ and NiO with the melt containing NiF₂, the equilibrium quotient for the reaction was determined. The equilibrium quotient for the heterogeneous reaction of Nb₂O₅ and BeO with molten LiF-BeF₂ mixtures (67-33 and 52-48 mole %) was also determined, and the effect of the melt composition on the solubility of Nb₂O_{5 …}

Approaches To The Synthesis Of Azabullvalene, Thomas Rudolph Steinheimer

Doctoral Dissertations

"Three approaches to the synthesis of the heretofore unknown azabullvalene, the pi electron equivalent heterocyclic congener of bullvalene itself, are described. Two of the schemes are based upon the assumption that the most convenient method for the introduction of the nitrogen atom is via thermal rearrangement of the appropriate azide.

The first involved the generation of the homobarrelene carbon skeleton and sub sequent decomposition of its azide. This compound arises formally as the product of the Diels-Alder addition of acetylene to the bicyclic valence isomer of tropyl azide (cyclohepta-1, 3, 5- trienyl-7-azide). In order to achieve this goal, Diels-Alder additions …

The Atomic Absorption Determination Of Ultra-Trace Tellurium In Rocks Utilizing High Sensitivity Sampling Systems, Richard D. Beaty

Doctoral Dissertations

"The sampling boat and the graphite furnace have been shown to possess the required sensitivity to detect tellurium at ultra-trace levels, in a variety of sample types, by atomic absorption. In the sampling boat approach, tellurium in sample solutions is chemically separated and concentrated by extraction into methyl isobutyl ketone before measurement. For samples exhibiting extraction interferences or excessively high background absorption, a preliminary separation of tellurium by coprecipitation with selenium is described. Using this technique, tellurium can be quantitatively detected down to 5 nanograms and linear response is observed to 100 nanograms. Relative standard deviations of better than 7% …

Anionic Polymerization Of A Series Of 5-Membered Cyclocarbosiloxanes, Balaraman Suryanarayanan

Doctoral Dissertations

"A study has been made on the anionic polymerization of a series of 5-membered cyclocarbosiloxanes with methyl and/or phenyl substituents. The polymerization was initiated by lithium n-butyldiphenylsilanolate in the presence of tetrahydrofuran. Six 5-membered cyclocarbosiloxanes (2,2,5,5-tetramethyl-1-oxa-2,5-disilacyclopentane; 2,2,5- trimethyl-5-phenyl-1-oxa-2,5-disilacyclopentane; 2,5-dimethyl-2,5-diphenyl- 1-oxa-2,5-disilacyclopentane; 2,2-dimethyl-5 ·,5-diphenyl-1-oxa- 2,5-disilacyclopentane; 2-methyl-2,5,5-triphenyl-1-oxa-2,5-disilacyclopentane; 2,2,5,5-tetraphenyl-1-oxa-2,5-disilacyclopentane) were synthesized. Since the chemical shifts of the protons of the cyclic monomers and the polymers formed were different, the rate of polymerization of the cyclic monomers was measured utilizing an NMR spectrometer. The effects of tetrahydrofuran concentration, initiator concentration and water concentration on the rate of polymer formation and on the molecular weight of …

Scavenging Of Atmospheric Particles By Water Drops, Ming-Shian Wu

Doctoral Dissertations

"In the first paper, the mechanisms of particle capture and coalescence of aerosols by a moving water drop in the atmosphere are studied using the boundary-layer flow approximation. The particle trajectory is computed by solving the equations of motion of the particle both outside and inside the boundary layer using the Adams-Moulton method. The grazing trajectory is found by a trial-and-error technique. The collision and collection efficiencies of scavenging due to particle inertia and to the velocity gradient of the flow field are then computed for water drops ranging from 0.1 to 1.0 mm in radius and for particle of …

A Study Of The Pulse-Height Response Of Silicon Surface-Barrier Detectors To High-Energy Heavy Ions, Gregory Dan Smith

Doctoral Dissertations

"The pulse-height defect (PHD) of high-energy heavy ions in silicon surface-barrier detectors can be divided into three components: (1) energy loss in the gold-surface layer, (2) a nuclear-stopping defect, and (3) a defect due to recombination of electron-hole pairs in the plasma created by the heavy ion. The plasma recombination portion of the PHD was the subject of this study using the variation of the PHD with (1) the angle of incidence of incoming heavy ions, and (2) changes in the detector bias. The Tandem Van de Graaff accelerator at Argonne National Laboratory was used to produce scattered beam ions …