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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Kinetic & Spectral Studies of Copper(II)-4,4',4",4'"-Tetrasulfophthalocyanine in Aqueous Solution

Scholl, Stephen 01 May 1983 (has links)
The monomer-dimer equilibrium of CuTSPC4- was examined by spectral methods in aqueous solution over a total dye concentration of 2 x 10-8M to 8 x 10-7M at 24°C. The value obtained for the dimerization constant, KD,was 1.1 x 107M-1 which is smaller than literature values. However, the discrepancy is not appreciable considering the differences in the methods used and the experimental conditions of the different solutions. Spectral measurements of the dimerization constant were made at only one temperature since the spectral changes were quite small when the temperature was varied. This observation is consistent with the small heat of reaction associated with the dimerization process which has been reported in the literature for this system. A comparison of the dimerization constant of CuTSPC4- with other cations shows the following trend: Cu2+ ≥ Ni2+ > H+ > Zn2+ ᷈ Vo2+ > Fe3+ > Co2+ The larger dimerization constants of CuTSPC4- and NiTSPC4- compared to the other tetrasulfonated phthalocyanines is attributed to the lack of axial ligand binding to these metals which enhances the dimerization process. Ligand binding studies made here and elsewhere on the CuTSPC4- and NiTSPC4- systems showed no evidence of ligand binding unlike the FeTSPC3- and CoTSPC4- systems where various ligands have been found to bind at the axial positions of these metals. Kinetic measurements on the monomer-dimer equilibrium of CuTSPC4- in aqueous solution were made on the stopped-flow apparatus at 24°C using a total dye concentration range of 1 x 10-6 M to 1 x 10-5M. The rate constants for the formation and dissociation of the CuTSPC4- dimer are 3.24 x 106M-1s-1 and 0.27 s-1 , respectively. Activation parameters could not be obtained due to the small spectral changes which occur at different temperatures and hence cannot be measured on the stopped-flow apparatus. The kinetic data show that the formation and dissociation rate constants of CuTSPC4- in aqueous solution is similar to those of NiTSPC4- and VOTSPC4- systems. All these tetrasulfonated metallophthalocyanine systems show no evidence of ligand binding to the central metal ion and have similar dimerization constants. On the other hand the lower dimerization constant of CuTSPC4- relative to these systems can be attributed to the smaller rate constant associated with the formation of the dimer. The presence of axial ligands on the central metal ion is believed to inhibit the formation of the dimer in CoTSPC4-.
102

Determination of the Time Delay in the Arrival of Jovian Signals at Opposite Ends of a Long Baseline Fringe Synthesis Interferometer

Scott, Roger 01 July 1970 (has links)
In order to determine the size of the decametric sources, the technique of long baseline radio interferometry is being employed. The University of Florida at Gainesville is a pioneer in this field. In 1964, T. D. Carr introduced the procedure of recording the signals received at each end of an interferometer on magnetic tape and comparing the re-corded signals at a later time. This eliminated the necessity for transmission lines over the length of the baseline, allowing greater separation to attain higher resolution.
103

Behavior of Chlorine & Sulfur During Coal Pyrolysis & Combustion

Shao, Dakang 01 December 1992 (has links)
The behavior of chlorine and sulfur in Illinois coals and during pyrolysis and combustion their forms in the coals were evaluated by combined Thermogravimetry/Fourier Transform Infrared Spectroscopy/ Ion Chromatography (TG/FTIR/IC) techniques. It was found that more than 90% of chlorine in Illinois coals was liberated as HC1 gas during pyrolysis and combustion in the temperature range of approximately 3000 - 600°C, with the amount reaching the maximum around 440°C. Similarity of the HC1 and NH3 release profiles during pyrolysis of IBC-109 indicates that the forms of chlorine in coal is associated closely with the forms of nitrogen, and that the chlorine may be bonded to the basic nitrogen-sites on the inner walls of coal micropores. Approximately more than 60% of the total sulfur in the coals was evolved mainly as SO2 and COS in the 250°C-750°C range during combustion. Except for SO2 and COS, H2S was a major gaseous sulfur-containing product observed during coal pyrolysis. The release rates of the gaseous sulfur species reached several peaks at some points within the temperature ranges during pyrolysis and combustion, and these peaks were due to the emissions of several types of the sulfur in different forms present in the coals. The effect of chlorine removal from high chlorine Illinois coal on its reactivity was also investigated by TG/FTIR/IC techniques. The weight loss behavior of the leached coals was significantly different from that of the raw coal (IBC-109) during combustion. The release profiles of gaseous chlorine (HCl) and sulfur species (SO2 and COS) of the leached coals are significantly different from those of the raw coal. The effect of the addition of CaCO3 and Ca(OH)2 on the behavior of chlorine and sulfur during combustion of high chlorine and medium sulfur Illinois coal was investigated by TG/FTIR/IC techniques. Thermogravimetry showed no significant difference in weight loss between IBC-109 and its sorbent mixtures, Coal-CaCO3 and Coal-Ca(OH)2. However, addition of 5% Ca(OH)2 or 6% CaCO3 to IBC-109, may not only reduce emission of chlorine by about 48% or 20%, but also reduce emission of total sulfur by about 68% or 52% during combustion.
104

Determination of Energy Levels & Oscillator Strengths of 2% Nd:Y2O3

Shao, Kung-Chuan 01 December 1979 (has links)
The absorption spectrum of 2% Nd:Y2O3 has been obtained at room termperature. It has been used to determine the crystalline energy levels. Through counting the number of Stark components, degeneracies have been determined for oscillator strength calculations. Overlapping absorption lines were analyzed into their components. Oscillator strengths have been measured for those well-identified and analyzed transitions in the variable and near ultraviolet regions of the 2% Nd:Y2O3 absorption spectrum.
105

Development of HPLC-EC Methodology & Its Use in the Determination of the Daily Pattern of Brain Octopamine Levels in Leucophaea Maderae

Siddiqui, Maya 01 May 1992 (has links)
A solid phase extraction technique was developed to aid in removing interfering substances from the cockroach brain extract. Quantitative analysis of octopamine was subsequently achieved by HPLC with amperometric electrochemical detection. The procedure affords 80 to 100 percent recovery of octopamine. The presence of octopamine in brain extract was confirmed by GC-MS. The daily pattern of brain octopamine levels in cockroach Leucophaea maderae was investigated using the HPLC-EC assay procedure. It was concluded that the concentration of brain octopamine in the cockroach L. maderae does not exhibit daily rhythm.
106

An Analysis of a New Partizan Game Using Combinatorial Techniques

Snodgrass, James, III 01 July 1979 (has links)
John Horton Conway's combinatorial game theory was applied to a new partizan game with a complete analysis as the result. Mathematical values were assigned to the countably infinite number of positions in the game. Direct computation of the first eight values and extension via the Principle of Mathematical Induction made the assignments possible. Examination of these values (which repeat with period 2) shows that the game, played on a strip of squares, can be won by the first player if the strip is of odd length and can be won by the second player if the strip is of even length. Further examination of the values leads to a completely general symmetry strategy for the first and second player wins in the appropriate cases.
107

The Low-Temperature Pyrolysis of a Nitrated North Dakota Lignite

Spears, Dennis 01 May 1984 (has links)
Low-temperature pyrolysis is the thermal degradation of coal in an inert atmosphere at temperatures below 700°C. Coal pyrolysis is well-studied, being a complex mix of many reactions. Pyrolysis is affected by changes in many different process variables, such as temperature, pressure and heating rate. Low-temperature pyrolysis is an old and well-studied process. Chemical pretreatments have been used to beneficiate conversion processes, inducln pyrolysis. Nitration has not been one of them. Pyrolyzing a nitrated coal would, hopefully, rapidly devolatilize the coal and break up the matrix into more commercially usable products. The nitration procedure developed by The Standard Oil Company minimizes oxidation of the coal, reducing the adverse affects of such a treatment. Lignite, both untreated and nitrated at two different levels, was pyrolyzed at temperatures of 250, 425 and 600°C, helium pressures of 0, 500, and 1000 psig, with sample masses of about 1, 3, and 5 grams. Residence times of 0.5, 1.5 and 2.5 hours were used. The yields of volatiles (gas), oils,asphaltenes, preasphaltenes, and char were monitored. The char was subjected to elemental analysis, and the pyrolysis gas was analyzed by gas chromatography. Nitration does not appear to improve lignite lowtemperature pyrolysis substantially. Nitrated and untreated lignites the char nitrogen content is hydrogen content of the char not cause the expected rapid produce similar char and oil yields. After nitration raised substantially, and the is decreased. Nitration does devolatilization, nor does it substantially improve the quality of the off-gas. Nitration does de-ash and desulfurize the coal.
108

Analytical Pyrolysis of Eastern Oil Shales

Sturgeon, Lizbeth 01 May 1983 (has links)
The Sunbury shale and the Cleveland member of the Ohio shale were studied utilizing the technique of analytical pyrolysis (pyrolysis gas chromatography). The effects of ceiling temperature, heating rate, and pyrolysis interval on the pyrolysis yield and relative product distribution for these eastern oil shales were observed. Carefully monitored pyrolysis of the shale allows separation of high and low volatile components and measurement of the relative peak areas in the pyrogram provides the yield of the high and low volatile fractions. Linear temperature ramps of 5000, 2000, and 100°C per second were employed. Ceiling temperatures of 450°C to 950°C and pyrolysis intervals of up to 20 seconds were probed. Some samples were repeatedly pulsed to obtain intervals of up to 120 seconds. Carbon-hydrogennitrogen and thermogravimetric analyses were also performed on the spent shale. The preliminary data implies the following trends: The total smount of pyrolysis product increases with increasing ceiling temperature. The product molecular weight distribution decreases with increasing ceiling temperature and with increased rates of heating. Yield enhancement due to the effect of increased heatup rates seems to be greatest in the 650°to 750°C region. Lower ceiling temperatures require substantially longer pyrolysis intervals in order to obtain optimum yields.
109

Extraction Rate Study of Ni(III) Oxinate & Separation of Cu(II) & Ni(II) with Oxide Based on Differences in Rates of Extraction

Taichilassunthorn, Somchai 01 August 1976 (has links)
This study was conducted with metal ion concentrations in the range of parts per million and used batch extraction techniques to study the non-equilibrium extraction of Cu(II) and Ni(II) oxinates. Contrary to other authors, atomic absorption was used exclusively for the analysis of phases. The two main areas of investigation in this study were: Kinetics study of extraction of Ni(II) oxinate. Separation of Cu(II) and Ni(II) with oxine based on differences in rates of extraction. It was the purpose of this work to study the extraction of Cu(II) and Ni(II) with oxine in chloroform. This particular pair of elements was chosen for study for several reasons. One prominent reason was that these metals form stable complexes with oxine which remain stable upon extraction with various organic solvents. The extraction curves (pH versus percent extraction) were found to lie very close together making it impossible to separate one from the other without the use of masking agents. Another factor which was important to the undertaking of this extraction rate study was the fact that the equilibrium behavior of metal oxinates (and of oxine) distributed between water and various organic solvents had been previously studied in detail. Finally, it was believed that it should be possible to separate the Cu(II) and Ni(II) ions (and perhaps other as well) by a non-equilibrium method even though it was not possible to separate these same two ions by an equilibrium extraction. The present work was aimed at determining the optimum conditions of pH, oxine concentration, shaking time and solvent used for the maximum separation of the ion pair, Cu(II)-Ni(II).
110

Photochemistry of beta-Methyl-beta-Nitrostyrene & Its Derivatives

Tang, Donald 01 December 1974 (has links)
A series of β- methyl-β-nitrostyrenes have been synthesized and subjected to ultraviolet irradiation. A new technique has been developed for synthesis of 1-phenyl-1,2-propanedione-1-oxime and its derivatives by irradiation of the corresponding styrene. The yields of the oximes were almost quantitative [except 1-(p-nitrophynyl)-1,2-propanedione-1-oxime and 1-(m-nitrophenyl)-1,2-propanedione-1-oxime]. It has been found that irradiation of the appropriate styrene is a very simple, efficient, and general procedure for the synthesis of 1-phenyl-1,2-propanedione-1-oxime and a number of its derivatives. A number of derivatives of β- methyl-β-nitrostyrene (p-CH3, p-Ch30, p-Cl, p-No2, and m-NO2) were irradiated. It was found that the substituent effects on the rearrangement of the styrene to the oxime were fairly small. The nitro group attached at the para or meta position of the phenyl ring appeared to inhibit the rearrangement and seemed to promote the fragmentation to form the corresponding acid and aldehyde. Kinetics studies also indicated that the p-nitro and m-nitro-β- methyl-β-nitrostyrene showed a slower rate of disappearance of unsaturated nitro group during irradiation than any of the other substituents studied.

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