Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1910. / C. A. Burdick determined to be Charles Adrian Burdick and H. W. Connelly determined to be Harry Wade Connelly from "Forty-First Annual Catalogue. School of Mines and Metallurgy, University of Missouri". The entire thesis text is included in file. Typescript. Illustrated by authors. Title from title screen of thesis/dissertation PDF file (viewed February 26, 2009)

La recherche dans le domaine de la chimie industrielle s’engage pour la mise en place de nouvelles stratégies de synthèse plus respectueuses de l’environnement. Le méthylmercaptan (CH3SH) est un précurseur de la méthionine, un acide aminé essentiel, dont la demande mondiale ne cesse de croitre. La synthèse du CH3SH est réalisée industriellement par réaction catalytique entre l’H2S et le méthanol, lui-même synthétisé à partir d’un mélange CO/H2, ce qui rend attractives les voies de synthèse directes à partir de CO/H2 et H2S ou encore CO2/H2 et H2S, permettant la valorisation et le recyclage du CO2 un coproduit de la réaction. Dans ce travail de thèse de nouveaux catalyseurs ont été développés en menant parallèlement une étude sur la nature et la quantification de la phase active des différents systèmes catalytiques mis au point. Une étude de la teneur en Mo, de l’effet de la calcination, de l’ajout de dopants cuivre et/ou zinc a été réalisée sur des catalyseurs de type K-Mo supportés sur alumine. L’utilisation d’autres supports oxydes permet d’améliorer sensiblement les performances catalytiques évaluées dans un micro-pilote travaillant dans des conditions préindustrielles. La mise en regard et confrontation des caractérisations par XPS, TEM, DRX et Raman des catalyseurs activés mettent en évidence, dans tous les systèmes catalytiques, la présence majoritaire d’une phase de type 1T-MoS2 lamellaire, intercalée par des ions potassium. La quantification de cette phase intercalée a permis de la corréler à la productivité en méthylmercaptan, démontrant ainsi que cette phase est la phase active des catalyseurs de synthèse directe du méthylmercaptan. / In the field of chemistry, industrial research is committed to the development of environmentally friendly synthesis strategies. Methyl mercaptan (CH3SH) is a precursor to methionine whose worldwide demand is steadily growing. It is currently produced by a catalytic reaction between H2S and methanol. Due to the production of methanol involving multiple reaction steps, the direct synthesis of methyl mercaptan from syngas (CO/H2) and H2S or from (CO2/H2) and H2S (assuming a CO2 recycling) appears as a financially attractive industrial process. This work focused on the development of new catalysts for this reaction, specifically on identifying and quantifying the active phase of different catalytic systems. Studies on the effects of molybdenum loading, calcination procedures and copper and/or zinc doping were carried out on an alumina-supported potassium-molybdenum catalyst. Others metal oxide carriers were also employed, remarkably improving catalytic performances. Catalytic tests were performed with a micro-pilot reactor operated in near-industrial conditions. Catalysts were characterized using X-ray photoelectron spectroscopy, transmission emission microscopy, X-ray diffraction and Raman spectroscopy, evidencing the presence of a significant lamellar 1T-MoS2 type phase, intercalated by potassium ions. Quantification of this intercalated phase was correlated with methyl mercaptan productivity, demonstrating its role as the catalytically active phase which drives methyl mercaptan direct synthesis.

Potassium-argon apparent ages obtained on biotite and amphibole from various phases of the Guichon Creek batholith present on the Bethlehem Copper property are reported and their geological significances are discussed in this thesis. Although the individual phases were found to be essentially indistinguishable in terms of their potassium-argon apparent ages, the results obtained indicated with considerable certainty that these phases were emplaced during an interval not greater than 10 m.y. centered around 200 m.y. ago and that no major metamorphic event has occurred in this area since this time. It is also believed that this average apparent age of 200 m.y. may represent a better approximation to the maximum age of the Triassic-Jurassic boundary than that previously reported in the literature. The potassium and argon analytical techniques employed are described briefly, and the analytical precision and accuracy obtained are discussed. Descriptions of the samples collected and samples analyzed are given as an appendix. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

archives@tulane.edu / Background: Chronic kidney disease (CKD) is a disease that affects 13.6% of American adults. The prevalence of abnormal serum potassium levels and their downstream renal and cardiovascular effects in CKD are not clearly understood. Objective: The objective of this project is to determine the prevalence of abnormal serum potassium in the CKD population in the United States and to identify associations between abnormal serum potassium and renal and cardiovascular endpoints in CKD patients. Paper 1: At baseline, 4.07% of CRIC study participants had hypokalemia and 7.65% had hyperkalemia. Non-Hispanic Black participants had the highest prevalence of hypokalemia (5.67%), and Hispanic CKD patients had the highest prevalence of hyperkalemia (10.92%). Women, non-Hispanic Black individuals, and individuals who were non-diabetic and/or middle-aged at baseline were likelier to experience hypokalemia at some point during the CRIC study. Male gender, Hispanic ethnicity, diabetes at baseline, higher CKD stage at baseline, and younger age at baseline were found to be risk factors for ever experiencing hyperkalemia. Overall, over 40% of participants experienced an abnormal serum potassium level at some point during the study. Paper 2: Using time-updated serum potassium, hypokalemia was associated with increased risk of ESRD. Hyperkalemia was associated with increased risk of both ESRD and CKD progression. Baseline-only modeling of hypokalemia and hyperkalemia as exposures did not identify significant associations with renal outcomes. Paper 3: Using baseline-only serum potassium, hypokalemia was associated with both all-cause mortality [HR = 1.31; 95% CI: (1.01, 1.71)] and cardiovascular disease [HR = 1.49; 95% CI: (1.18, 1.89)]. However, marginal structural models with repeated potassium measures only identified elevated risk of cardiovascular disease associated with hypokalemia [HR = 1.36; 95% CI: (1.18, 1.89)]. Conclusion: The results of this project demonstrate that abnormal serum potassium is a prevalent problem in the United States CKD population. Very low and very high potassium levels are associated with severe renal and cardiovascular outcomes, and these associations are stronger in some subgroups compared to others, including older and Hispanic CKD patients. This information can help clinicians identify individuals at high risk for severe endpoints and intervene early to prevent these outcomes from occurring. Future research should focus on establishing causality, which could provide a new treatment target for preventing renal and cardiovascular outcomes in CKD patients. / 1 / Andrei Stefanescu

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<p> The semi-classical path-integral method for finding the magnetoconductivity is specialised to cubic one-electron metals having a spherical Fermi surface, isotropic effective mass and anisotropic scattering times. Properties of the conductivity and resistivity tensors are deduced for this special case, in more detail for high magnetic fields. The magnetoconductivity for potassium, and the quantities derived from it - magnetoresistance and induced torque - are calculated as functions of temperature, field strength, impurity concentration and crystal orientation. Comparison is made with experimental results.</p> / Thesis / Master of Science (MSc)

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