This study describes the structural and depositional evolution in the KH field in West Natuna Basin, Indonesia. Data for the study were acquired by three-dimensional (3D) seismic reflection volume and a complete suite of well logs. The regional basin underwent transtensional, sinistral shear during the rift phase that reactivated during the early to middle Miocene inversion as a traspressional, dextral shear. The study identified four periods of tectonic activity in the area which are extension, quiescence, compression and another period of quiescence. A structural closure developed along a series of north-south trending, normal splay faults defines the area's trap play. Understanding how this structural play fits into the regional tectonic picture may suggest new approaches to hydrocarbon exploration in the area.

Detailed geologic mapping of the Deseret Peak East 7.5' Quadrangle yields new interpretations regarding the stratigraphy of the Oquirrh Basin, fault and fold geometry, and structural evolution of the region. The Stansbury Range consists of the north-southtrending Deseret anticline. Basal Mississippian units rest unconformably on Cambrian beds in the central part of the range. Paleozoic uplift, Mesozoic contraction, and Cenozoic extension have created a series of broad folds, large thrust faults, and several normal faults. The area is dominated by bedrock springs, with the presence of abundant and thick Quaternary deposits unrelated to Pleistocene glaciation, burying drainages, and mantling hillslopes. The influence of bedrock on groundwater flow paths and stream baseflow is suggested by local anecdotal reports that high snowfall in the Deseret Peak region generates high discharge ten miles south in Clover Creek, though they are not in the same drainage basin.

We examine the transition between extension and strike-s lip in the San Felipe Hills, western Salton Trough, southern California using new and compiled geologic mapping, measured stratigraphic sections, magnetostratigraphy, and structural analysis. A 625 m measured section describes the Borrego, Ocotillo , and Brawley formations in the SE San Felipe Hills and constrains a regional disconformity and correlative angular unconformity at ~ 1 Ma. Sedimentation rates for the Brawley Formation above the disconformity range from 1.0 to 1.2 mm/yr, palcoflow was to the ENE. The Brawley Formation consists of three interbeddcd lithofac ics; (I) fluvial and fluvio-d eltaic, (2) lacustrinc, (3) and eolian depo sits. Changes in facies, provenance , and paleoflow , with deposition of Ocotillo and Brawley formations record onset and evolution of cross cutting strike- slip faults other than the San Jacinto fault zone in the western Salton Trough at ~ 1 Ma. Since deposition of the Brawley Formation (~ 0.5 Ma), rocks of the San Felipe hills have been uplifted and complexly deformed. new data suggest that strands of the Clark fault persist SE of its previously mapped termination, transferring slip into folded rocks in the central and southern San Felipe Hills. Equivalent right lateral slip form folding for the Clark fault in the San Felipe Hills is 5.6 km. Minimum slip rates for the Clark strand are between 9 and 11 mm/year. Since ~ 0.5 Ma, evolving strands of the San Jacinto fault zone, including the Coyote Creek and Clark faults, have deformed rocks of the San Felipe Hills.

<p>Proton exchange membrane fuel cells (PEMFCs) are considered as one of the most promising alternative clean and sustainable energy sources to fossil fuels. In general, PEMFC is consisted of anodic and cathodic electrode assembly, electrolyte, and proton-exchange membrane. While renewable fuels, such as hydrogen gas and formic acid, get oxidized at the anode to produce protons, oxygen molecules are reduced to form water at the cathode. Platinum has been widely used for both anodic and cathodic reactions due to its excellent catalytic reactivity.</p> <p><br></p> <p>Significant effort has been devoted to improving the reactivity and selectivity of Pt-based catalysts by alloying with a second metal. AuPt alloy nanoparticles have been studied extensively for electrochemical formic acid oxidation reaction, and isolated Pt species are recognized as the most active sites. While the majority body of literature focuses on structure-reactivity relationships</p> <p>based on as-synthesized materials, less attention is paid to the structural evolution during electrochemical catalysis. In this work, we develop a colloidal synthetic method to deposit Pt shell onto Au nanoparticles with variable thickness to study the microstructural evolution under electrocatalytic formic oxidation. We find that Pt atoms are submerged from the surface to form isolated Pt species in the first 100 cycles, which show enhanced FAO activity by shifting the reaction pathway. Additional CV scanning causes further depletion of Pt from the surface, resulting in the deactivation of the catalyst.</p> <p><br></p> <p>Despite the high activity of Pt-based catalysts, the use of these materials is limited by its high cost. Recently, transition metal sulfides such as cobalt sulfides have been found to show comparable activity to Pt-based catalysts in pH 7 ORR. However, it is challenging to isolate the role of coordination environment amidst multiple geometries and oxidation states that exist within any given phase. In this effort, we synthesize isolated Co atoms supported on colloidal WS₂nanosheets. By doing post synthetic treatment on these nanosheets, we are able to achieve a range of Co-S coordination number. Correlating Co-S CN to their ORR activities, we find the optimal active sites for ORR in neutral media possess a Co-S coordination number of 3-4.</p>

Neste trabalho, estudam-se por espalhamento de raios-X a baixo ângulo (SAXS) a estrutura e a cinética de formação de materiais híbridos orgânico/inorgânico, preparados por processo sol-gel a partir da hidrólise de misturas de organometálicos de silício funcionalizados. Num primeiro sistema, a evolução estrutural de uma mistura hidrolisada 2:1 molar de Tetraetoxisilano (TEOS) e 3-Glicidoxipropiltrimetoxisilano (GPTS) foi estuda em função do tempo in situ por SAXS, nas temperaturas de 25&deg;C, 43&deg;C e 60&deg;C. Os resultados são compatíveis com o crescimento de domínios ricos em sílica (clusters) formados a partir de um número fixo de partículas primárias. O raio de giração, Rg , dos clusters e a intensidade de SAXS extrapolada a zero, I(0), crescem com o tempo t seguindo leis de potência da forma Rg &prop; (t-t0)&alpha; e I(0) = B(t-t0)&beta;, sendo &alpha; e &beta; e independentes da temperatura e B uma medida da constante de velocidade k = &beta;B1/ &beta; do processo, uma função de Arrhenius da temperatura. A energia de ativação &Delta;E = 67,7 &plusmn; 1,1 kJ/mol foi estimada para o processo. A intensidade I(0) também escala experimentalmente com Rg na forma I(0) &prop; RgD com D = 1,71 &plusmn; 0,01, em boa concordância com o valor &beta;/&alpha; = 1,79 &plusmn; 0,07 obtido do estudo cinético. O crescimento de macromoléculas com dimensionalidade de 1,7 é típico de macromoléculas diluídas ou semidiluídas em condições de bom solvente. Os resultados de SAXS ainda sugerem que o sistema exibe propriedades dinâmicas de escala limitadas pelo tamanho das partículas primárias. Num segundo sistema, a evolução estrutural de uma mistura hidrolisada 1:1 molar de 3-Aminopropiltrietoxisilano (APTS) e 3-Glicidoxipropiltrimetoxisilano (GPTS) foi estuda em função do tempo in situ por SAXS, em temperatura ambiente. Os resultados são compatíveis com a formação de partículas primárias e crescimento de clusters com características de fractal de massa (1 < D< 3). No estágio inicial, a população de partículas primárias não fractais (D = 3) aumenta em função do tempo. O crescimento de clusters com características fractais de massa (D < 3) a partir da agregação das partículas primárias aumenta gradativamente o raio médio de giração Rg do sistema. Nos estágios mais avançados de agregação, o crescimento dos clusters ocorre por aumento do número de partículas por cluster (enquanto o número de clusters diminui), de forma que o volume de correlação Vc dos clusters satisfaz a relação Vc &prop; RgD, mesmo que os valores de D cresçam lenta e regularmente de 1,22 a 1,57 dentro do intervalo estudado, em concordância com o carácter fractal de massa dos clusters. Esses resultados suportam um mecanismo de agregação cluster-cluster controlado por difusão. / In this work, the structure and the kinetics of formation of organic/inorganic hybrid materials, prepared by sol-gel process from the hydrolysis of mixtures of functionalized silicon organometallics, are studied by small-angle X-ray scattering (SAXS). In a first system, the structural evolution of a 2:1 molar hydrolyzed mixture of Tetraethoxysilane (TEOS) and 3-Glycidoxypropyltrimethoxysilane (GPTS) was studied in situ as a time function by SAXS, at 25&deg;C, 43&deg;C and 60&deg;C. The results are compatible with the growth of silica rich domains (clusters) from a fixed number of primary particles. The gyration radius, Rg, of the clusters and the intensity extrapolated to zero, I(0), increase in power laws with time t as Rg &prop; (t-t0)&alpha; and I(0) = B(t-t0)&beta;, being &alpha; and &beta; independents on temperature while B is a measure of the process rate constant k = &beta;B1/&beta;, an Arrhenius function of temperature. The activation energy &Delta;E = 67.7 &plusmn; 1.1 kJ/mol was evaluated for the process. The extrapolated intensity I(0) also scales experimentally with Rg as I(0) &prop; RgD with D = 1.71 &plusmn; 0.01, in good agreement with the value &beta;/&alpha; = 1.79 &plusmn; 0.07 from the kinetic study. The growth of macromolecules with dimensionality 1.7 is typical of diluted or semi-diluted macromolecules in good-solvent conditions. The SAXS results yet suggest that the system exhibits dynamic scaling properties limited by the primary particle size. In a second system, the structural evolution of a 1:1 molar hydrolyzed mixture of 3-Aminopropyltriethoxysilane (APTS) and 3-Glycidoxypropyltrimethoxysilane (GPTS) was studied in situ as a time function by SAXS, at ambient temperature. The results are compatible with formation of primary particles and growth of clusters with mass-fractal characteristics (1 < D < 3). At the initial stage, the population of the non-fractal primary particles (D = 3) increases with time. The growth of the mass-fractal clusters (D < 3) from the aggregation of the primary particles increases gradually the average radius of gyration Rg of the system. At advanced stages of aggregation, the growth of the clusters occurs by the increase of the number of particles per clusters (while the number of clusters diminishes), in such a way that the correlation volume of the clusters Vc fulfills the relationship Vc &prop; RgD, even though the values of D have increased slowly and gradually from 1.22 to 1.57 in the studied range, in agreement with a mass-fractal character of the clusters. These results support a diffusion-controlled cluster-cluster aggregation mechanism.

Nanocrystalline beta-silicon carbide (ß-SiC) was synthesized at relatively low temperature (<1300C) by carbothermal reduction (CTR) reaction in fine scale carbon/silica mixtures. The fine scale mixing of the reactants (i.e., carbon and silica) was achieved by solution-based processing and subsequent heat treatment. The mechanism of the CTR reaction in the current system was investigated from different aspects. The condensates of the volatile species generated during the CTR reaction was collected and analyzed. The results supported previous investigations which suggested that the CTR reaction is a multi-step process that involves silicon monoxide (SiO) vapor as a reaction intermediate. The kinetics of the CTR reaction was investigated by isothermal weight loss study and by the study which determined the amount of SiC formed via quantitative X- ray diffraction (QXRD) analysis. The results of kinetic study were consistent with the "shrinking-core" model, in which the reaction between SiO vapor and carbon at the carbon surface to produce SiC is the rate-controlling step. In addition, several techniques, including XRD, gas adsorption analysis, laser diffraction particle size analysis, SEM, TEM, etc., had been used to study the structural evolutions of the reaction product of CTR. It was demonstrated that the evolutions of product structure characteristics such as crystallite size, specific surface area, specific pore volume, pore size distribution, particle size distribution, and powder morphology, etc. were consistent with each other and provided support to the reaction mechanism proposed.

Thesis (Ph.D.)--Case Western Reserve University, 2009 / Department of Materials Science and Engineering Available online via the OhioLINK ETD Center

Neste trabalho, estudam-se por espalhamento de raios-X a baixo ângulo (SAXS) a estrutura e a cinética de formação de materiais híbridos orgânico/inorgânico, preparados por processo sol-gel a partir da hidrólise de misturas de organometálicos de silício funcionalizados. Num primeiro sistema, a evolução estrutural de uma mistura hidrolisada 2:1 molar de Tetraetoxisilano (TEOS) e 3-Glicidoxipropiltrimetoxisilano (GPTS) foi estuda em função do tempo in situ por SAXS, nas temperaturas de 25&deg;C, 43&deg;C e 60&deg;C. Os resultados são compatíveis com o crescimento de domínios ricos em sílica (clusters) formados a partir de um número fixo de partículas primárias. O raio de giração, Rg , dos clusters e a intensidade de SAXS extrapolada a zero, I(0), crescem com o tempo t seguindo leis de potência da forma Rg &prop; (t-t0)&alpha; e I(0) = B(t-t0)&beta;, sendo &alpha; e &beta; e independentes da temperatura e B uma medida da constante de velocidade k = &beta;B1/ &beta; do processo, uma função de Arrhenius da temperatura. A energia de ativação &Delta;E = 67,7 &plusmn; 1,1 kJ/mol foi estimada para o processo. A intensidade I(0) também escala experimentalmente com Rg na forma I(0) &prop; RgD com D = 1,71 &plusmn; 0,01, em boa concordância com o valor &beta;/&alpha; = 1,79 &plusmn; 0,07 obtido do estudo cinético. O crescimento de macromoléculas com dimensionalidade de 1,7 é típico de macromoléculas diluídas ou semidiluídas em condições de bom solvente. Os resultados de SAXS ainda sugerem que o sistema exibe propriedades dinâmicas de escala limitadas pelo tamanho das partículas primárias. Num segundo sistema, a evolução estrutural de uma mistura hidrolisada 1:1 molar de 3-Aminopropiltrietoxisilano (APTS) e 3-Glicidoxipropiltrimetoxisilano (GPTS) foi estuda em função do tempo in situ por SAXS, em temperatura ambiente. Os resultados são compatíveis com a formação de partículas primárias e crescimento de clusters com características de fractal de massa (1 < D< 3). No estágio inicial, a população de partículas primárias não fractais (D = 3) aumenta em função do tempo. O crescimento de clusters com características fractais de massa (D < 3) a partir da agregação das partículas primárias aumenta gradativamente o raio médio de giração Rg do sistema. Nos estágios mais avançados de agregação, o crescimento dos clusters ocorre por aumento do número de partículas por cluster (enquanto o número de clusters diminui), de forma que o volume de correlação Vc dos clusters satisfaz a relação Vc &prop; RgD, mesmo que os valores de D cresçam lenta e regularmente de 1,22 a 1,57 dentro do intervalo estudado, em concordância com o carácter fractal de massa dos clusters. Esses resultados suportam um mecanismo de agregação cluster-cluster controlado por difusão. / In this work, the structure and the kinetics of formation of organic/inorganic hybrid materials, prepared by sol-gel process from the hydrolysis of mixtures of functionalized silicon organometallics, are studied by small-angle X-ray scattering (SAXS). In a first system, the structural evolution of a 2:1 molar hydrolyzed mixture of Tetraethoxysilane (TEOS) and 3-Glycidoxypropyltrimethoxysilane (GPTS) was studied in situ as a time function by SAXS, at 25&deg;C, 43&deg;C and 60&deg;C. The results are compatible with the growth of silica rich domains (clusters) from a fixed number of primary particles. The gyration radius, Rg, of the clusters and the intensity extrapolated to zero, I(0), increase in power laws with time t as Rg &prop; (t-t0)&alpha; and I(0) = B(t-t0)&beta;, being &alpha; and &beta; independents on temperature while B is a measure of the process rate constant k = &beta;B1/&beta;, an Arrhenius function of temperature. The activation energy &Delta;E = 67.7 &plusmn; 1.1 kJ/mol was evaluated for the process. The extrapolated intensity I(0) also scales experimentally with Rg as I(0) &prop; RgD with D = 1.71 &plusmn; 0.01, in good agreement with the value &beta;/&alpha; = 1.79 &plusmn; 0.07 from the kinetic study. The growth of macromolecules with dimensionality 1.7 is typical of diluted or semi-diluted macromolecules in good-solvent conditions. The SAXS results yet suggest that the system exhibits dynamic scaling properties limited by the primary particle size. In a second system, the structural evolution of a 1:1 molar hydrolyzed mixture of 3-Aminopropyltriethoxysilane (APTS) and 3-Glycidoxypropyltrimethoxysilane (GPTS) was studied in situ as a time function by SAXS, at ambient temperature. The results are compatible with formation of primary particles and growth of clusters with mass-fractal characteristics (1 < D < 3). At the initial stage, the population of the non-fractal primary particles (D = 3) increases with time. The growth of the mass-fractal clusters (D < 3) from the aggregation of the primary particles increases gradually the average radius of gyration Rg of the system. At advanced stages of aggregation, the growth of the clusters occurs by the increase of the number of particles per clusters (while the number of clusters diminishes), in such a way that the correlation volume of the clusters Vc fulfills the relationship Vc &prop; RgD, even though the values of D have increased slowly and gradually from 1.22 to 1.57 in the studied range, in agreement with a mass-fractal character of the clusters. These results support a diffusion-controlled cluster-cluster aggregation mechanism.

京都大学 / 0048 / 新制・課程博士 / 博士(経済学) / 甲第19258号 / 経博第523号 / 新制||経||275(附属図書館) / 32260 / 京都大学大学院経済学研究科経済学専攻 / (主査)教授 宇仁 宏幸, 教授 黒澤 隆文, 准教授 田中 彰 / 学位規則第4条第1項該当 / Doctor of Economics / Kyoto University / DGAM

Polymer-derived ceramics are a new class of materials synthesized by thermal decomposition of polymer precursors. Previous studies have shown that the materials exhibit excellent thermo-mechanical properties and can be stable at temperatures up to 2000oC. Furthermore, the novel polymer-to-ceramics process enables the manipulation of the ceramic structures at the atomic/nano level by designing the chemistry of polymer precursors and controlling the pyrolysis conditions, thereby, the properties of ceramics. In this dissertation, oxidation/hot-corrosion behavior and the structural evolution of Si-Al-C-N ceramics have been studied. The structural evolution and crystallization behavior of the SiCN and SiAlCN ceramics are investigated using FT-IR, XRD, and NMR. The results revealed that aluminum could greatly affect the structural evolution and crystallization behavior of polymer-derived ceramics, resulting to better stability. The oxidation kinetics of the SiCN and SiAlCN ceramics in air is determined by directly measuring the thickness of the oxide scale with SEM as a function of oxidation time. The results revealed that while the oxidation of the SiCN ceramics follows parabolic kinetics in all of the ranges of testing temperatures, oxidation of the SiAlCN ceramics is complicated: their oxidation rates are similar to that of SiCN ceramics at the earlier stage, but they decrease to very low levels after a certain time. The oxidation rate of the SiAlCN ceramics is more than an order of magnitude lower than any other silicon based ceramics previously reported. The transportation behavior of oxygen through the oxide scales is studied by 18O diffusion. The results indicate that oxidation is controlled by molecular oxygen diffusing through the oxides for both SiCN and SiAlCN ceramics; however, the oxygen diffusion rate in the oxides on SiAlCN ceramics is remarkably retarded. The structures of the oxides are characterized by XRD and NMR. A structural model is advanced to account for the aluminum effect on the oxygen diffusion in the oxide. The oxidation and hot-corrosion kinetics of the SiCN and SiAlCN ceramics in water vapor are determined by measuring their weight changes as a function of annealing time. The kinetic constants, kp and kl, are obtained by fitting the weight-change data with a paralinear model. The results reveal that the SiAlCN ceramics have a much better corrosion resistance than the SiCN and CVD SiC/Si3N4. After annealing at 1400oC for 300 hours, the SiAlCN-20 still retains more than 70% of its original strength, while the SiCN only retains about 20% of its original strength. The improvement in oxidation/hot-corrosion resistance of the SiAlCN ceramics is attributed to the low activity of the SiO2 in the Al2O3-containing silica. In summary, I have developed a new class of high-temperature materials, Si-Al-C-N ceramics. It is demonstrated that these new materials have excellent oxidation and corrosion resistance and thermal stability. Together with their easy processability, the materials will find many high temperature applications such as environmental barrier coatings, ceramic matrix composites, and MEMS for harsh environments.