Estudamos neste trabalho a estrutura eletrônica de defeitos localizados em silício, responsáveis pela introdução de níveis profundos na faixa proibida do semicondutor. Utilizamos para tanto modelos de aglomerados moleculares dentro do formalismo do Espalhamento Múltiplo com aproximação local X para o potencial de troca (MS-X). Um tratamento adequado para os orbitais de superfície foi usado. Os defeitos estudados foram de dois tipos: defeitos simples (monovacância Si:V e oxigênio substitucional Si:O) e pares de defeitos vizinhos na rede (divacância Si : V IND 2) e par de átomos de fósforo Si: P IND 2). Os defeitos foram estudados em diferentes estados de carga (Si:O e Si : O POT -\', Si: P IND 2 e Si: P IND 2 POT + Si: V POT 0 IND 2, Si: V IND 2 POT + e Si: V POT IND 2) e no caso da divacância e do centro P IND 2 POT + foram incluídos efeitos de polarização de spin. Encontramos para todos os defeitos estudados indícios da ocorrência de efeitos Jahn-Teller. Incluímos análises das distorções dos primeiros vizinhos ao defeito nos sistemas Si: O POT , P IND 2 POT + e V POT IND 2. O modelo adotado mostrou-se capaz de descrever satisfatoriamente a estrutura eletrônica dos defeitos estudados, fornecendo resultados quantitativos que podem ser comparados diretamente com a experiência. / In this work we studied the electronic structure of deep-level defects in silicon. To do this we use molecular cluster models within the formalism of the Multiple Scattering method, in the local density functional approximation (X). The surface orbitals of the cluster are treated in a convenient way. The defects studied here were of two kinds: simple defects (single vacancy Si:V and oxygen substitutional Si:0), and pairs of defects occupying neighbouring sites in the lattice (divacancy Si :V2 and the pair of phosphoru- atoms Si :P2 ). The defects were studied in different charge states (Si:O and Si:O-, Si:P2 and Si:P+, Si:V20, SI:V2-) and for the divacancy and the center Si:P2+ the calculations were carried out to the spin-polarized limit. For all defects studied we found evidence as to the possible occurrence of Jahn-Teller effects. Analysis of nearest-neighbours distortions were included for the systems Si:O- , Si:V2+ and Si:V2-. The electronic structure of the defects studied here was satisfactorily described by the model we adopted, and quantitative results are given, that can be compared straightforwardly with experimental results.

In recent years, the American health care system has undergone major changes in organization and sponsorship. From the perspectives of Marxian and Weberian theories, the corporate or government sponsored arrangements which have emerged from these institutional changes are expected to reduce participating physicians' professional autonomy (self-control of their own activity) and authority (control of the medical care process). In opposition to this view, recent occupational theory, emphasizing the social power of professions, has argued that despite the transformations underway within health care, physicians can be expected to retain autonomy and authority. / This case-study of a state-sponsored, pediatric primary care project operating in two locations seeks to assess the relative merits of the prevailing theoretical perspectives described above and to investigate the factors which influence physicians' retention or loss of autonomy and authority. Data from interviews with participating pediatricians, nurse/case managers and with administrators at the project and state level are augmented by the responses of pediatricians in other areas of the state to a survey concerning their perceptions of, and willingness to participate in such a project. / The findings indicate that, although the predictions of both classical and recent theories are partly realized, neither has sufficiently recognized the effects of the composition, internal cohesion and local market circumstances of occupational segments within the medical profession on the strategies physicians use to preserve professional control. These characteristics of occupational segments are apparently associated with variations in professional values which underlie individual responses to specific practice arrangements as well as collective actions to influence the practice arrangements in which physicians participate. / Source: Dissertation Abstracts International, Volume: 52-03, Section: A, page: 1101. / Major Professor: Allen W. Imershein. / Thesis (Ph.D.)--The Florida State University, 1991.

This study examined the role of the Saudi Arabian National Guard as an instrument of modernization. The focus of the study was the ability of the National Guard to instill in its members the Arab traditional values--male status, family ties, respect for the elderly, and predisposition toward traditional values--while strengthening the development-related values--rationality of consumption, occupational aspiration, respect for time, raising the status of women, independent decision making, and motivation. / Data were collected with questionnaires and interviews. The random sample was 803 National Guard personnel. / The results of bivariate analysis indicated that, with the exception of the male status variable, the Saudi Arabian National Guard has played a significant role in influencing the attitudes and behavior of its personnel in the desired direction with both traditional and development-related values. / A multivariate analysis was used to assess the individual and collective impact of experience in the National Guard along with eight other variables found to contribute strongly to shaping the ten examined values. These included level of education, age, local and foreign training, knowledge of foreign language, reading a weekly magazine, marital status, and place of birth. The regression analysis indicated that experience in the National Guard was the major contributor in shaping almost all the studied values. The exceptions were the male status variable, to which experience in the National Guard did not contribute, and raising the status of women, in which education was a stronger contributor than experience in the National Guard. / The study concluded with an evaluation of the concept of modernization and the feasibility of its application in Third World countries, suggesting that it should be viewed as a national goal, and offering suggestions for future research in this area. / Source: Dissertation Abstracts International, Volume: 49-03, Section: A, page: 0635. / Major Professor: Monte Palmer. / Thesis (Ph.D.)--The Florida State University, 1988.

Les élastomères sont des macromolécules qui, sous l’effet de la vulcanisation, vont présenter des propriétés d’hyper-élasticité remarquables rendant leur utilisation indispensable dans de nombreux secteurs industriels et biens de consommation. Cependant, afin d’obtenir des propriétés mécaniques suffisantes pour de telles applications, les élastomères ont besoin d’être renforcés par des charges, telles que le noir de carbone ou la silice. Si ces charges sont couramment utilisées dans l’industrie, elles présentent toutefois des inconvénients majeurs, notamment leur forte densité (> 1,8), et leur incorporation à fort taux conduit à des matériaux lourds. L’objectif des travaux présentés ici est alors d’étudier un nouveau mode de renforcement, à base de polyuréthanes synthétisés in situ lors de la mise en œuvre des élastomères afin de former des matériaux plus légers que ceux existants. Les mélanges élastomère/polyuréthane ainsi formés ont été caractérisés afin de déterminer leurs propriétés rhéologiques, mécaniques, thermiques et thermomécaniques. Ces études ont permis de prouver notre concept comme les matériaux renforcés par des PUs présentent des propriétés mécaniques correctes vis-à-vis d’un renfort classique tout en ayant une densité plus faible. / Elastomers are macromolecules which, under the effect of vulcanization, present remarkable properties of hyper-elasticity, making their use essential in many industrial sectors and consumer goods. However, in order to obtain sufficient mechanical properties for such applications, fillers, such as carbon black and silica, need to be incorporated in rubber formulations. Even if they are commonly used in the industry, these fillers present some major limitations, especially their high density (> 1,8), leading to heavy materials when incorporated at high rate. The aim of these works is to study a new type of reinforcement, based on polyurethanes synthesized in situ during elastomers processing, in order to decrease their weight. Elastomer/polyurethane blends thus formed were characterized to determine their rheological, mechanical, thermal, thermomechanical properties in addition of their densities. This work has proven our concept as PUs reinforced materials present lower densities compared to a conventional reinforcement while having correct mechanical properties.

by Chi-Keung Lam. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 100-103). / Abstract also in Chinese. / Acknowledgments --- p.i / Abstract --- p.ii / 摘要 --- p.iii / Table of contents --- p.iv / Index of compounds --- p.v / List of tables --- p.vi / List of figures --- p.vii / Chapter Chapter 1. --- Introduction / Chapter 1.1 --- Some aspects of urea/thiourea inclusion chemistry --- p.1 / Chapter 1.2 --- General chemistry of monocyclic oxocarbons --- p.5 / Chapter 1.2.1 --- Synthesis of monocyclic oxocarbons --- p.5 / Chapter 1.2.2 --- Aromaticity of monocyclic oxocarbon anions --- p.20 / Chapter 1.2.3 --- Reactions of monocyclic oxocarbons --- p.25 / Chapter 1.3 --- Aim of the present research --- p.31 / Chapter Chapter 2. --- Description of crystal structures / Chapter 2.1 --- Urea-anion inclusion compounds --- p.32 / Chapter 2.1.1 --- Bis(tetra-n-propylammonium) squarate-urea-water (1/ 6/2) --- p.32 / Chapter 2.1.2 --- Tetra-n-butylammonium hydrogen squarate-urea-water (1/1/1) --- p.38 / Chapter 2.1.3 --- Bis(tetraethylammonium) squarate-tetraethylammonium hydrogen carbonate- urea-water (1/2/4/6) --- p.42 / Chapter 2.1.4 --- Bis(tetra-n-propylammonium) croconate-urea-water (1/5/2) --- p.47 / Chapter 2.2 --- Thiourea-anion inclusion compounds --- p.53 / Chapter 2.2.1 --- Bis(tetraethylammonium) squarate-thiourea-water (1/4/ 2) --- p.53 / Chapter 2.2.2 --- Bis(tetraethylammonium) squarate-thiourea (1/6) --- p.59 / Chapter 2.2.3 --- Bis(tetra-n-propylammonium) squarate-thiourea-water (1/ 4/2) --- p.66 / Chapter Chapter 3. --- Summary and discussion / Chapter 3.1 --- Urea/thiourea monocyclic oxocarbon anions inclusion compounds --- p.71 / Chapter 3.2 --- Structural features and topological correlations of the host lattices --- p.72 / Chapter 3.3 --- Hydrogen bonding and linkage modes of urea and thiourea molecules --- p.87 / Chapter Chapter 4. --- Experimental / Chapter 4.1 --- Preparation of crystals --- p.91 / Chapter 4.2 --- X-ray Crystallography --- p.93 / References --- p.100 / Appendix Atomic coordinates and thermal parameters of the new inclusion compounds --- p.104

No description available.

本文运用化学计算软件Gaussian03以及基于赝势和平面波基组的从头计算分子软件VASP， 研究了阴离子簇合物M⁻L[subscript n], (M⁻ = Na⁻, Li⁻,; L = H₂O, NH₃ ; n = 1-10) 中的电子结构和溶剂化作用。 / 文中选用基于密度泛函理论的B3LYP方法和6-311++G** 基组, 从Na⁻ 离子和Li⁻ 离子分别与不同溶剂分子 (H₂O和NH₃) 的相互作用入手，探讨以这类气态团簇化合物作为载体的体系中，溶解于其中的两个电子之间的相互作用以及电子与溶剂分子之间的相互作用。对于因溶剂分子极性的差异，导致形成不同形态的簇合物，进而影响了溶解于其中的电子对状态的研究，为实验上进一步探究被溶解的电子对提供了有利的理论依据。 / 在阴离子簇合物Li⁻(H₂O)[subscript n]中, 锂负离子和氧原子的强相互作用使得锂负离子被水分子包围。当n = 10，锂负离子的两个外层电子转移到水分子团簇中，并且电子对可以以单重态或三重态的电子态稳定存在。与之相反，在阴离子簇合物Na⁻(H₂O)n中，钠负离子的两个外层电子没有向溶剂中转移，钠负离子更倾向于与水分子团簇表面的氢原子相互作用而稳定在团簇表面。 / 在以氨分子为溶剂的阴离子簇合物Na⁻(NH₃)n和Li⁻(NH₃)n中, 金属负离子Na⁻ 和Li ⁻的两个外层电子随着溶剂分子的增加逐渐从金属离子上转移到溶剂 中。事实上，当n = 10时，簇合物Na⁻(NH₃)[subscript n]和Li⁻(NH₃)[subscript n]形成了两个溶解中心：被溶剂分子包围的金属阳离子，及其附近分散在溶剂分子中的电子对。这对电子可以以单重态或三重态的电子态稳定存在。与以水为溶剂的簇合物Na⁻(H₂O)[subscript n]和Li⁻(H₂O)[subscript n]不同的是，在Na⁻(NH₃)[subscript n]和Li⁻(NH₃)[subscript n]中，被溶解电子对更加弥散，广泛分布于溶剂分子中。 / The solvation and electronic structures in M⁻Ln₂, M⁻ = Li⁻ and Na⁻, L = H₂O and NH₃, and n = 1-10 were explored computationally by quantum chemistry calculation using Gaussian 03 package and by density functional theory based ab initio molecular dynamics simulation (AIMD) method with pseudopententials and a plane wave basis set using Vienna Ab Initio Simulation package (VASP). / Interactions of Na⁻ and Li⁻ anions in different solvent molecules, H₂O and NH₃, were calculated by B3LYP method with a basis set of 6-311++G** in order to explore the possibility that these clusters could serve as gas-phase molecule models for the solvation of two electrons. Such models would capture the electron-electron interaction in a solution environment. / For Li⁻(H₂O)[subscript n], the Li⁻ is buried in the water cluster due to the strong Li-O interaction, and by n = 10, the two loosely bound s electrons are indeed detached from lithium, and they could in either the singlet (spin-paring) or the triplet (spin-coupling) state. In contrast, for Na⁻(H₂O)[subscript n], the electron pair stays on the sodium, and the Na⁻ stays on the cluter surface, which is solvated by no more than 4 hydrogen atoms. The solvent-solvent interactions are favored as the water molecules from structures similar to observed in water anions. The formation of a solvated electron pair and the variation in solvation structures make these two cluster series interesting subjects for further experimental investingation. / With two s electrons, the Na⁻(NH₃)[subscript n] and Li⁻(NH₃)[subscript n] clusters are unique in that they capture the important aspect of the coupling between two solvated electrons. By first principles calculations, we demonstrate that the two electrons are detached from the metal by n = 10, which produces a cluster with a solvated electron pair in the vicinity of a solvated alkali cation, and the two electrons could also exist in both singlet and triplet state. They are quite distinct from the hydrated anionic clusters Na⁻(H₂O)[subscript n] and Li⁻(H₂O)[subscript n], in that the solvated electrons are delocalized and widely distributed among the solvent ammonia molecules. The Na⁻(NH₃)[subscript n] and Li⁻(NH₃)[subscript n] series therefore provide another interesting type of molecular model for the investigation of solvated electron pairs. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Zhang, Han. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / TITLE PAGE --- p.I / ABSTRACT --- p.II / 论文摘要 --- p.IIV / ACKNOWLEDGEMENTS --- p.VI / CONTENTS --- p.VII / LIST OF TABLES --- p.X / LIST OF FIGURES --- p.XIII / Chapter Chapter One --- General Research Background / Chapter 1.1 --- General Introduction --- p.1 / Chapter 1.2 --- Electron in polar solvent --- p.1 / Chapter 1.2.1 --- Electron in water molecules --- p.1 / Chapter 1.2.2 --- Electron in ammonia molecules --- p.6 / Chapter 1.3 --- Experimental background of metal anion --- p.9 / Chapter 1.3.1 --- Li⁻(H₂O)[subscript n] and Na⁻(H₂O)[subscript n] --- p.9 / Chapter 1.3.2 --- Li⁻(NH₃)[subscript n] and Na⁻(NH₃)[subscript n] --- p.11 / Chapter 1.4 --- Scope of this thesis --- p.13 / Chapter 1.5 --- References --- p.14 / Chapter Chapter Two --- Theoretical Background / Chapter 2.1 --- Introduction --- p.18 / Chapter 2.2 --- The Schrödinger Equation and Born-Oppenheimer Approximation --- p.19 / Chapter 2.3 --- Hartree-Fock Theory --- p.20 / Chapter 2.4 --- Post-HF methods --- p.24 / Chapter 2.5 --- Density Functional Theory --- p.25 / Chapter 2.5.1 --- Kohn Sham (KS) scheme --- p.26 / Chapter 2.5.2 --- Local Density Approximation (LDA) --- p.29 / Chapter 2.5.3 --- Generalized Gradient Approximation (GGA) --- p.30 / Chapter 2.5.4 --- Hybrid Functionals --- p.30 / Chapter 2.6 --- DFT based ab initio Molecular Dynamics (AIMD) --- p.31 / Chapter 2.6.1 --- Plane Wave Basis Set --- p.34 / Chapter 2.6.2 --- Pseudopotentials and Projector Augmented Wave Method --- p.35 / Chapter 2.6.3 --- Molecular dynamics at constant temperature --- p.39 / Chapter 2.7 --- References --- p.40 / Chapter Chapter Three --- The identification of a solvated electron pair in the gaseous clusters of Na(H2O)n and Li(H2O)n / Chapter 3.1 --- Introduction --- p.42 / Chapter 3.2 --- Computaional methods --- p.45 / Chapter 3.3 --- Results and discussion --- p.46 / Chapter 3.3.1 --- Structure and energy for Na⁻(H₂O) and Li⁻(H₂O) --- p.46 / Chapter 3.3.2 --- H end structure for Na⁻(H₂O)[subscript n] --- p.52 / Chapter 3.3.3 --- O end structure for Li⁻(H₂O)[subscript n] --- p.58 / Chapter 3.3.4 --- Triplet structures for Li⁻(H₂O)[subscript n] --- p.64 / Chapter 3.3.5 --- Comparison between singlet and triplet Li⁻(H₂O)[subscript n] --- p.69 / Chapter 3.4 --- Conclusion --- p.73 / Chapter 3.5 --- References --- p.74 / Chapter Chapter Four --- The solvation of two electrons in the gaseous clusters of Na⁻(NH₃)n and Li⁻(NH₃)[subscript n] / Chapter 4.1 --- Introduction --- p.78 / Chapter 4.2 --- Computaional methods --- p.80 / Chapter 4.3 --- Results and discussion --- p.82 / Chapter 4.3.1 --- n = 1 --- p.82 / Chapter 4.3.2 --- H End Structures for Na⁻(NH₃)[subscript n] --- p.87 / Chapter 4.3.3 --- N End Structures for Li⁻(NH₃)n and Na⁻(NH₃)[subscript n] --- p.90 / Chapter 4.3.4 --- Triplet N End Structures for Li⁻(NH₃)[subscript n] --- p.97 / Chapter 4.3.5 --- Comparison between singlet and triplet Li⁻(NH₃)[subscript n] --- p.103 / Chapter 4.4 --- Conclusion --- p.105 / Chapter 4.5 --- References --- p.106

Fire has always been one of the most serious threats of collapse to structural building frames. The September 11 incident has stimulated significant interests in analyzing and understanding the behavior of the structures under fire events. The strength of the material decreases due to the elevated temperature caused by fire, and this reduction in strength leads to the failure of the member. Frames that do not have sufficient ductility can suffer progressive collapse of the entire structure if one member fails during a fire event. Such collapse could result in loss of human life and serious economic consequences. The motivation for this thesis is to provide an understanding of the continuity effects in steel frames under fire conditions. The continuity effects of the structure can provide additional strength to the system to sustain the loads under fire event. Different scenarios of the frame and beam structures which include changes to member sizes, fire locations, and bay size, are investigated with the assistance of SAP2000 and ANSYS. These programs can provide the collapse analysis for each scenario at different temperature. The continuity effect was investigated from the strength point of view of the structure. Ultimately, the thesis presents a design tool for aiding member design under fire conditions. The design tool consists of different graphs that maybe use to determine the collapse load capacity of a continuous structure at elevated temperature based on the analysis of a simpler, determinate structure.

Based on ethnography, oral history and archival research, this study examines the culture of the Accompong Maroons by focusing on the political, economic, social, religious and kinship institutions, foodways, and land history. This research demonstrates that like the South American Maroons, the Accompong Maroons differ in their ideology and symbolisms from the larger New World population. However, the Accompong Maroons have assimilated, accommodated and integrated into the state in every other aspect. As a consequence, the Accompong Maroons can only be considered maroons in name only. Today's Accompong Maroons resemble any other rural peasant community in Jamaica. Grounded in historical analysis, the study also demonstrate that social stratification in Accompong Town results from unequal access to land and other resources, lack of economic infrastructure, and constraints on food marketeers and migration. This finding does not support the concept of communalism presented in previous studies.

This study examines attitudes toward sources of assistance in a white, working class, ethnic neighborhood in east Baltimore. The study is based on a random sample of one hundred ethnic neighborhood residents. The sample includes fifty Polish-Americans and fifty Italian-Americans between the ages of twenty-one and fifty. The primary method of data collection is the face-to-face interview. The interview schedule includes structured and unstructured questions in addition to six reaction vignettes developed by Shirley Star. The study is an attempt to provide up-to-date information regarding preferred sources of assistance in an urban, ethnic neighborhood. The major finding of the study is that working class, ethnic, Catholics prefer traditional structures for meeting social needs. Traditional structures such as the family, the church, and to some extent the ethnic voluntary association, have not been significantly overshadowed by functionally specialized service organizations of the wider community. Members of the extended family and traditional professionals such as the clergy and the general physician are key gatekeepers and preferred sources of assistance. The data in the study provide a basis for suggesting adaptations in case services and greater pluralism in social service delivery strategies.