Thesis (M.S.)--Rochester Institute of Technology, 1983. / Typescript. Includes bibliographical references (leaf 56).

Thesis (Ph. D.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains vii, 129 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Ronald Rousseau; Committee Co-Chair: Athanassios Sambanis; Committee Member: Amyn Teja; Committee Member: Athanasios Nenes; Committee Member: Ingeborg Schmidt-Krey. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on July 8, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Department of Chemical and Materials Engineering, University of Alberta. Includes bibliographical references.

Thesis (M.Sc.)--York University, 2003. Graduate Programme in Mathematics. / Typescript. Includes bibliographical references (leaves 115-118). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ99399

Thesis (Ph. D.)--Oregon Graduate Center, 1987.

Made available in DSpace on 2014-10-09T12:42:45Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:21Z (GMT). No. of bitstreams: 1 05244.pdf: 7104329 bytes, checksum: 5c2e4b0cdbfa5595e3825819e43fe6fe (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Crystallization is an increasingly important process in a variety of applications from drug development to single crystal X-ray diffraction structure determination. However, while there is a good deal of research into prediction of molecular crystal structure, the factors that cause a molecule to be crystallizable have so far remained poorly understood. The aim of this project was to answer the seemingly straightforward question: can we predict how easily a molecule will crystallize? The Cambridge Structural Database contains almost a million examples of materials from the scientific literature that have crystallized. Models for the prediction of crystallization propensity of organic molecular materials were developed by training machine learning algorithms on carefully curated sets of molecules which are either observed or not observed to crystallize, extracted from a database of commercially available molecules. The models were validated computationally and experimentally, while feature extraction methods and high resolution powder diffraction studies were used to understand the molecular and structural features that determine the ease of crystallization. This led to the development of a new molecular descriptor which encodes information about the conformational flexibility of a molecule. The best models gave error rates of less than 5% for both cross-validation data and previously-unseen test data, demonstrating that crystallization propensity can be predicted with a high degree of accuracy. Molecular size, flexibility and nitrogen atom environments were found to be the most influential factors in determining the ease of crystallization, while microstructural features determined by powder diffraction showed almost no correlation with the model predictions. Further predictions on co-crystals show scope for extending the methodology to other relevant applications.

Made available in DSpace on 2014-06-11T19:25:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-06-18Bitstream added on 2014-06-13T19:32:45Z : No. of bitstreams: 1 silva_fg_me_ilha.pdf: 1536045 bytes, checksum: 5e52a7e90e9528b73306cfd4b593e9d3 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Apresentamos os resultados de estudos de cristalização de possíveis crescimentos de cristais semicondutores de óxido de telúrio (CdTe) e óxido de bismuto (Bi2O3) no sistema de vidro 20WO3-80TeO2 (TW). Estes trabalho configura-se como um estagio anterior aos estudos de crescimentos de semicondutores em dimensões nanométricas(nanocristais “NCs”) em vidros teluritos. Com este objetivo foi sintetizada a amostra: dopadas com óxido de cadmio e óxido de bismuto, em diversas proporções em suas composições, e estas foram submetidas ou não a ambientes redutores. As amostras foram tratadas termicamente a diferentes temperaturas na região de transição vítrea (Tg ~ 350° C) e analisados utilizando as técnicas de DRX, DSC, FTIR e UV-Vis. Resultados de DRX mostram que acima do recozimento 400°C estimulou o crescimento de trigonal bipiramidal-estruturas conhecidas como α-TeO2 em ambas as amostras, e para as amostras TW dopadas com óxido de bismuto, o tratamento térmico induz a formação de cristais semicondutores de óxido de bismuto. Espectroscopia no infravermelho também mostrou a presença de estruturas Bi2O3. Absorção óptica UV-Vis indica que a presença de cádmio e bismuto em vidro TW sem serem submetidos a tratamento térmico não muda os valores de gap óptico, sendo que este corresponde a uma energia de ~2,8 eV / The present work shows the studies of possible crystallization growth of crystals oxide semiconductors of tellurium (CdTe) and bismuth oxide (Bi2O3) in the glass system 20WO3- 80TeO2 (TW). This work consists in the first steps of initial growth of semiconductors in nanometrics dimensions (nanocrystals “NCs”) in glasses teluritos. The sample was synthecized: doped with oxide of cadmium and bismuth oxide, in diverse ratios of its compositions, and these had been submitted or not it reducing enviroments. The samples had been thermally dealt with the different temperatures in the region glass transition (Tg ~ 350° C) and analyzed using the techniques of DRX, DSC, FTIR and UV-Vis. Results of DRX showed that up to the annealing 400°C it stimulated the trigonal growth known bipiramidal-structures as α-TeO2 in both the samples, and for samples TW (B), the thermal treatment induced the crystal formation bismuth oxide semiconductors. Spectroscopy in the infra-red ray also showed the presence of Bi2O3 structures in samples TW (B). Optic absorption UV-Vis indicated that the presence of cadmium and bismuth in glass TW without being submitted not dumb the thermal treatment the values of optic gap, being that this corresponds to an energy of ~2,8 eV