Thesis (Ph. D.)--Harvard University, 1990. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Harvard University, 1990. / Includes bibliographical references. Also issued in print.

Project report (D. Min.)--George W. Truett Theological Seminary, Baylor University, 2006. / Abstract. Includes bibliographical references (leaves 152-156).

A solução sólida céria-samária é uma das principais candidatas para aplicação como eletrólito sólido em células a combustível de óxido sólido, devido sua alta condutividade iônica em temperaturas intermediárias (500-750 ºC) de operação. Um dos problemas ainda não solucionados com relação a este material é sua relativamente baixa sinterabilidade. Nesse trabalho foi utilizado o método de sinterização em duas etapas visando melhorar a densificação com reduzido tamanho médio de grãos. Soluções sólidas comercial e obtida por mistura de óxidos de composição Ce0,8Sm0,2O1,9 foram utilizadas. Para fins comparativos também foi utilizado o método denominado sinterização em duas etapas tradicional que visa a obtenção de amostras densas independentemente do tamanho médio de grãos. Resultados de densidade aparente e retração linear revelaram que ambos os tipos de amostras têm comportamento distinto. Para a solução sólida comercial, a retração total até 1400 ºC foi de ~18%. Só foram obtidos resultados de densidade significativos ao utilizar temperaturas elevadas (igual ou superior a 1300 ºC). Para o material obtido por mistura de óxidos não foi possível atingir densidades maiores que 90% da densidade teórica. A sinterização em duas etapas tradicional produziu amostras densas, da mesma forma, que a não-tradicional, mas com tamanhos de grãos consideravelmente maiores. Amostras sinterizadas por ambos os processos foram analisadas por espectroscopia de impedância para a determinação da condutividade elétrica em função da temperatura, e não apresentaram variação significativa nas condutividades intra e intergranular. A sinterização em duas etapas não resultou em melhorias na densificação e nem na condutividade elétrica das amostras. Entretanto, a redução obtida no tamanho médio de grãos pode melhorar as propriedades mecânicas. / Samaria-doped ceria solid solution has been proposed to be used as solid electrolyte in Solid Oxide Fuel Cells due to its high ionic conductivity at intermediate temperatures (500-750 ºC). One of the main problems related to this solid solution is the relatively low sinterability. In this work, sintering of powder compacts was carried out by the two-step sintering method to improve the densification with simultaneous reduction of the mean grain size. Samaria-doped ceria, both commercial and prepared by solid state reactions, with composition Ce0.8Sm0.2O1.9 were investigated. For comparison purposes, the traditional two-step sintering method, by which dense specimens are produced, was also utilized. Apparent density and linear shrinkage results showed distinct features depending on the type of specimen. Total linear shrinkage for commercial solid solution up to ~ 1400 ºC was 18%, but high density values were obtained only for sintering experiments conducted at high temperatures ( 1300 ºC). Specimens prepared by solid state reactions did not attain density values higher than 90% of the theoretical one. The traditional method produced dense specimens as well as the two-step sintering, although the grain size was considerably higher in the former. Specimens sintered by the two methods were used for electrical conductivity measurements. No significant variation in both the grain and the grain boundary conductivities was obtained. The two-step sintering did not allow any improvement in the densification and in the electrical conductivity of samaria-doped ceria. However, the decrease in the mean grain size may contribute to improve the mechanical properties of this solid solution.

This thesis deals with the ostraca from Samaria, one of the most significant archeological discovery from the point of view of religious life in northern Israel. The thesis briefly introduces the religious world of Israel Region (Egypt, Mesopotamia and Canaan) and of Israel itself. The main focus of this thesis relates to the Samaria ostraca and the main emphasis is placed on the names of recipients and owners that can be found in ostraca trees which are consequently compared to the religious situation in Israel during 8th century BC (the approximate period to which the formation of ostraca are dated). Final chapters try to complete the main purpose which is outlined in the main part of the thesis (Dating of ostraca, Kuntillet Adžrud, Bull in Old Orient). It tries to seek for possible parallels between biblical and historical texts, archeological discoveries and the ostraca themselves. In the Annex can be found tables from years 9, 10 and 15 which contains number of ostrakon, names of owners and recipicients. In conclusion of the thesis is talking about polytheism in northern Israel at 8th century BC.

A solução sólida céria-samária é uma das principais candidatas para aplicação como eletrólito sólido em células a combustível de óxido sólido, devido sua alta condutividade iônica em temperaturas intermediárias (500-750 ºC) de operação. Um dos problemas ainda não solucionados com relação a este material é sua relativamente baixa sinterabilidade. Nesse trabalho foi utilizado o método de sinterização em duas etapas visando melhorar a densificação com reduzido tamanho médio de grãos. Soluções sólidas comercial e obtida por mistura de óxidos de composição Ce0,8Sm0,2O1,9 foram utilizadas. Para fins comparativos também foi utilizado o método denominado sinterização em duas etapas tradicional que visa a obtenção de amostras densas independentemente do tamanho médio de grãos. Resultados de densidade aparente e retração linear revelaram que ambos os tipos de amostras têm comportamento distinto. Para a solução sólida comercial, a retração total até 1400 ºC foi de ~18%. Só foram obtidos resultados de densidade significativos ao utilizar temperaturas elevadas (igual ou superior a 1300 ºC). Para o material obtido por mistura de óxidos não foi possível atingir densidades maiores que 90% da densidade teórica. A sinterização em duas etapas tradicional produziu amostras densas, da mesma forma, que a não-tradicional, mas com tamanhos de grãos consideravelmente maiores. Amostras sinterizadas por ambos os processos foram analisadas por espectroscopia de impedância para a determinação da condutividade elétrica em função da temperatura, e não apresentaram variação significativa nas condutividades intra e intergranular. A sinterização em duas etapas não resultou em melhorias na densificação e nem na condutividade elétrica das amostras. Entretanto, a redução obtida no tamanho médio de grãos pode melhorar as propriedades mecânicas. / Samaria-doped ceria solid solution has been proposed to be used as solid electrolyte in Solid Oxide Fuel Cells due to its high ionic conductivity at intermediate temperatures (500-750 ºC). One of the main problems related to this solid solution is the relatively low sinterability. In this work, sintering of powder compacts was carried out by the two-step sintering method to improve the densification with simultaneous reduction of the mean grain size. Samaria-doped ceria, both commercial and prepared by solid state reactions, with composition Ce0.8Sm0.2O1.9 were investigated. For comparison purposes, the traditional two-step sintering method, by which dense specimens are produced, was also utilized. Apparent density and linear shrinkage results showed distinct features depending on the type of specimen. Total linear shrinkage for commercial solid solution up to ~ 1400 ºC was 18%, but high density values were obtained only for sintering experiments conducted at high temperatures ( 1300 ºC). Specimens prepared by solid state reactions did not attain density values higher than 90% of the theoretical one. The traditional method produced dense specimens as well as the two-step sintering, although the grain size was considerably higher in the former. Specimens sintered by the two methods were used for electrical conductivity measurements. No significant variation in both the grain and the grain boundary conductivities was obtained. The two-step sintering did not allow any improvement in the densification and in the electrical conductivity of samaria-doped ceria. However, the decrease in the mean grain size may contribute to improve the mechanical properties of this solid solution.

Heidelberg, Univ., Mag.-Arb., 1996.

Community succession, the orderly changes a community experiences with time, is considered to be the result of either autogenic or allogenic factors working singularly or in combination. It has been further suggested that, as communities undergo succession, certain biological parameters change in a predictable manner. Examination of members 2 through 4 of the Mississippian (KinderhookOsage) Lodgepole Formation of Samaria Mountain, Idaho provides a means to evaluate these concepts. Within the study section comprised of 125 beds (61.5 m thick), four rock types are recognized. These include: (1) fossiliferous wackestone (78% of beds), which ranges in color from dark-gray (N3) to medium-light gray (N6), is fine to coarse crystalline, has an average insoluble content of 3.1 percent by weight, and an average organic content of 0.25 percent by weight; (2) fossiliferous mudstone (1S% of beds), which ranges in color from dark-gray (N3) to medium-gray (NS), is very fine to fine crystalline, has an average insoluble content of 2.3 percent and an average organic content of 0.30 percent by weight; (3) fossiliferous packstone (6% of beds), which ranges in color from medium-gray (NS) to light-gray (N7), is medium to coarse crystalline, has an average insoluble content of 3.3 percent by weight and an average organic content of O. 17 percent by weight; and (4) crystalline carbonate (1% of beds), which is light-gray (N7) in color, is coarse crystalline, has an insoluble content of 9.3 percent by weight, and an organic content of 0.2 percent by weight. However, at ninety-five percent confidence level, no statistical relationship could be seen between the rock types and either the insoluble contents or the organic content. Twenty-one taxa, including corals, brachiopods, crinoids, blastoids, gastropods, echinoids, and sharks were recognized, with most taxa ranging throughout the study section. Well-preserved fossils are generally rare. However, this deficiency seems to be due to weathering of the containing strata rather than to currents acting on the skeletons prior to burial. Orientational data support this conclusion. Measurements of the direction (vector) from the apical end to the calical end of the horn coral Zaphrentis show that the orientations of toppled corals is random. Two biological parameters are calculated for each of the bedding surfaces examined, i.e., diversity and calcified biovolume. Diversity is calculated two ways, i.e., in terms of equitability, and in terms of richness. For richness, values range from 0.0 to 7.41, with a mean of 4.12, and for dominance diversity, values range from 0.0 to 1.95, with a mean value of 0.87. Calcified biovolume, which is used as the basis for inferences involving biomass, ranges from 0 to 30,015 cubic centimeters per bedding surface, with a mean value of 744.1 cubic centimeters per bedding surface. Three faunal associations, as well as several sub-associations within the three major associations, are indicated by the clustering of indices of affinity. These associations include: (1) Zaphrentis-Crinoid- Syringopora-Echinoid-Cleiothryridina-Unispirifer-Spirifer-Orthotetes- Flexaria-Camarotoechia-Schizophoria-Lithostrotionella; (2) Cruziana-Dwelling tube; (3) Shark-Blastoid-Helminthopsis. Trophic relationships within the three associations suggest that they were the result of two factors: (1) the tendency towards a vertical stratification of the association's members, which resulted in a more efficient use of the water column; (2) direct physical interaction among association members, in the form of predator-prey or symbiotic relationships. The former type of interaction may have been operative between the sharks and blastoids of faunal association 3. Environmental reconstruction involved the determination of four parameters: (1) paleocurrent direction and intensity; (2) sedimentation rate; (3) bathymetry; and (4) substrate. From the study of both physical and biological evidence, it is concluded that, during the time of Lodgepole deposition a very weak, unidirectional current, or multidirectional currents of similar competency operated over a carbonate-mud substrate. Evidence suggests that the sedimentati on rate was extremely low, and that the Eh= 0 line was just below the sediment-water interface. The water depth at this location was probably below normal effective wave base, but above the zone of oxygen depletion. Study of fossils on bedding surfaces overlying barren bedding surfaces or surfaces containing fossil hash, suggests that four successional stages can be recognized. Because changes in the faunal composition between the various successional stages appear to take place both with (10 times), and without lithologic changes (16 times), it is concluded that succession may result from either biological modifications of the environment or physical changes. Therefore, succession was both autogenically or allogenically controlled. Additionally, the comnrunities were retrograded to an "earlier" successional stage 24 times within the 125 bed succession. As succession proceeded through the successional sequence, values for equability-diversity and calcified biovolume generally increase. This trend is in agreement with previously predicted trends. With succession the overall trend observed in the trophic structure appears to be one of an increase in the proportion of filter feeders in the community relative to the proportion of deposit feeders in the community.

Our perception, of the Omrid kings of the Kingdom oflsrael in the ninth century BCE, is based on the Books of 1 and 2 Kings in the Hebrew Bible. The Biblical author's concentration, on Omrid apostasy rather than on their abilities and accomplishments, has robbed these competant monarchs of the prominence allotted to kings like David and Solomon. Recent archaeological excavations, in conjunction with extra-Biblical sources, have however projected a different image. Excavations at the royal Omrid cities of Samaria, and especially Jezreel, have indicated that Omri, and his son Ahab, had erected immense and grandiose structures. These edifices bear testimony to periods of peace, stability and great economic prosperity. The Omrids deserve new assessments as to their accomplishments, and therefore, by means of visible and tangible structural remains, I wish to promote the persuasion of archaeology as vindication of Omrid grandeur and achievement at Samaria and Jezreel. / Biblical and Ancient Studies / M.A. (Biblical Studies)

Our perception, of the Omrid kings of the Kingdom oflsrael in the ninth century BCE, is based on the Books of 1 and 2 Kings in the Hebrew Bible. The Biblical author's concentration, on Omrid apostasy rather than on their abilities and accomplishments, has robbed these competant monarchs of the prominence allotted to kings like David and Solomon. Recent archaeological excavations, in conjunction with extra-Biblical sources, have however projected a different image. Excavations at the royal Omrid cities of Samaria, and especially Jezreel, have indicated that Omri, and his son Ahab, had erected immense and grandiose structures. These edifices bear testimony to periods of peace, stability and great economic prosperity. The Omrids deserve new assessments as to their accomplishments, and therefore, by means of visible and tangible structural remains, I wish to promote the persuasion of archaeology as vindication of Omrid grandeur and achievement at Samaria and Jezreel. / Biblical and Ancient Studies / M.A. (Biblical Studies)