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La déformation plastique des matériaux cristallins classiques est surtout dominée par des dislocations et leurs interactions mutuelles. Pour les métaux nanocrystallines (nc), des mécanismes de joints de grains différents peuvent exister en plus des mécanismes basés sur la dislocation. La dépendance à l’égard, entre autres, la forme du grain, l’orientation des grains, la densité de dislocations initiale, la structure des joints de grains et conditions extérieures favorise un ou deux mécanismes de déformation par rapport aux autres. Ces mécanismes dominants dictent la réponse globale du métal nc. L’influence des caractéristiques de microstructure doit être mieux comprise individuellement et collectivement. Dans le cadre de cette thèse, des simulations de dynamique des dislocations discrète 3D (DD) ont été effectuéessur trois grains individuels de taille micronique de même volume, mais qui diffèrent leurs rapports d’aspect. La diminution de la localisation de la déformation plastique avec l’augmentation de rapport d’aspect du grain à été observée. En raison du mécanisme inter-dérapant amélioré, des grains ayant rapport de un aspect plus elevé. La réponse plastique anisotrope des grains allongés a été quantifiée en terme d’ampleur du back-stress sur chaque système de glissement. En outre, une version polycristalline de dynamique des dislocations couple avec des éléments finis a été utilisée pour étudier le comportement mécanique des couches minces de palladium libre avec des grains colonnaires. La densité de dislocations initiale prise en compte dans les simulations est proche de celle mesurée expérimentalement. Les simulationsde DD d’un polycristal avec 12 grains hexagonaux de tailles égales reproduisent correctement le comportement d’écrouissage. L’augmentation de la résistance observée avec la diminution de l’épaisseur du film a été capturé en utilisant une distribution de taille de grains hétérogène du polycristal. L’élément essentiel est que la probabilité de grains plus petits sans dislocations initiales augmente avec la diminution de l’épaisseur du film. La différence dans les contributions en back-stress résultant de la distribution de la taille des grains dans le film a également été quantifiée. Enfin, en adaptant le modèle de Read, l’influence d’une dislocation statique électriquement chargée sur les propriétés électriques des semi-conducteurs a été étudiée. / Plastic deformation of classical crystalline materials is mostly dominated by dislocations and their mutual interactions. In nanocrystalline (nc) metals, different grain boundary mechanisms may exist in addition to the dislocation-based mechanisms. The dependency on, among other, the grain shape, grain orientation, initial dislocation density, grain boundary structure and external conditions will promote one or two deformation mechanisms over others. These dominant mechanisms dictate the overall response of nc metal. The influence of the microstructural features needs to be better understood individually and collectively. In the scope of the thesis, 3D discrete dislocation dynamics (DD) simulations were performed on three micron-sized single grains of same volume but differing in aspect ratios. Localization of plastic deformation was observed to decrease with increasing grain aspect ratio. Due to the enhanced cross-slip mechanism, grains with higher aspectratio exhibit a softer behavior. The anisotropic plastic response of elongated grains was quantified interms of the magnitude of back-stress on each slip system. Further, a polycrystalline version of dislocation dynamics code coupled with a finite elements was used, to study the mechanical behavior of free-standing palladium thin films with columnar grains. The initial dislocation density considered in the simulations is close to the one measured experimentally. DD simulations of a polycrystal with 12 equally sized hexagonal grains properly reproduce the strain hardening behavior. The increase in strength observed with decreasing film thickness was captured using a heterogenous grain size distribution of the polycrystal. The key element is that the probability of smaller grains with no inital dislocations is increasingwith decreasing thickness of the film. Difference in the back-stress contributions arising from the grain size distribution in the film was also quantified. Finally, by adapting Read’s model, the influence of a static, electrically-charged dislocation on electrical properties in semiconductors was studied.

Orientador: Carlos José Leopoldo Constantino / Banca: José Alberto Giacometti / Banca: Henrique de Santana / Banca: Eduardo René Perez Gonzalez / Banca: Marcelo Mulato / Banca: Rogério Pinto Mota / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: Neste trabalho foram preparados filmes finos de ftalocianinas de zinco (ZnPc) e de níquel (NiPc) através da técnica de evaporação térmica à vácuo (PVD - physical vapor deposition) em diversas espessuras e em escala nanométrica com o objetivo de determinar a arquitetura molecular destes filmes bem como suas propriedades ópticas e elétricas. Em última análise buscam-se gerar subsídios para as possíveis aplicações, especialmente dispositivos eletrônicos a base de semicondutores orgânicos e sensores de gás. A ZnPc e a NiPc em pó foram caracterizadas utilizando-se as técnicas de termogravimetria (TG), calorimetria exploratória diferencial (DSC) e os filmes PVD por espectroscopias de absorção no ultravioleta-visível (UV-vis), no infravermelho com transformada de Fourier (FTIR), espalhamento Raman, difração de raios-X, microscopias óptica e de força atômica (AFM) e caracterização elétrica cc (tensão x corrente). Os resultados mostraram que é possível a fabricação de filmes PVD de ZnPc e NiPc, uma vez que estas moléculas não são termicamente degradadas durante o processo de evaporação térmica a vácuo, e que o crescimento dos filmes pode ser controlado em escala nanométrica para ambos os materiais. Em termos estruturais, os filmes PVD de ZnPc e NiPc são cristalinos (forma α) e possuem as moléculas arranjado-se na forma de agregados e monômetros e ordenadas com o anel macrociclo inclinado em relação à superfície do substrato. Tais agregados podem ser vistos em escala nanométrica, porém, em escala micrométrica os filmes apresentam-se morfologicamente homogêneos. Em relação às propriedades ópticas e elétricas, observou-se que ambos os filmes PVD absorvem na região do visível com a ZnPc apresentando fotoluminescência quando irradiado com laser 785 nm. A condutividade elétrica é de 1,2x'10 POT. -10' S/m para a ZnPc e de 72x'10 POT... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this work thin films of phthalocyanines of zinc (ZnPc) and nickel (NiPc) were fabricated through the vacuum thermal evaporation technique (PVD - physical vapor deposition) for different thicknesses at nanometric scale with the objective of determining the molecular architecture of these films as well as their optical and electrical properties. The final idea is to generate subsidies for applications of these films in electronic devices based on organic semiconductors and gas sensors. The PVD films were characterized using thermogravimetry (TG), differential scanning calorimetry (DSC), ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) absorption spectroscopies, Raman scattering, X-ray diffraction, optical and atomic force (AFM) microscopies, and electrical characterization (tension x current dc). The results showed that the fabrication of ZnPc and NiPc films is possible since these molecules are not thermally degraded during the process of vacuum thermal evaporation and that the growth of the films can be controlled at nanometric scale for both materials. Structurally, the PVD films of ZnPc and NiPc possess the molecules organized with the macrocycle ring tilted in relation to the substrate surface. They are crystalline (α form) and possess molecular aggregates in the form of dimmers or higher order of aggregates and monomers. Such aggregates can be seen at nanometric scale, however, at micrometric scale the films are morphologically homogeneous. In relation to the optical and electrical properties, it was observed that boh PVD films absorb in the visible region with the ZnPc presenting photoluminescence when irradiated with the 785 nm laser line. The electric conductivity at 1,2x'10 POT. -10' S/m for ZnPc and 72x'10 POT. -10' S/m for NiPc. They also presented photoconductivity with the ZnPc more photoconductor than NiPc. Finally, after thermal treatment... (Complete abstract click electronic access below) / Doutor

Made available in DSpace on 2014-06-11T19:32:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-26Bitstream added on 2014-06-13T19:43:38Z : No. of bitstreams: 1 zanfolim_aa_dr_bauru.pdf: 2078904 bytes, checksum: 89fecc6406c0fe251fffb9f3101d20dd (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho foram preparados filmes finos de ftalocianinas de zinco (ZnPc) e de níquel (NiPc) através da técnica de evaporação térmica à vácuo (PVD - physical vapor deposition) em diversas espessuras e em escala nanométrica com o objetivo de determinar a arquitetura molecular destes filmes bem como suas propriedades ópticas e elétricas. Em última análise buscam-se gerar subsídios para as possíveis aplicações, especialmente dispositivos eletrônicos a base de semicondutores orgânicos e sensores de gás. A ZnPc e a NiPc em pó foram caracterizadas utilizando-se as técnicas de termogravimetria (TG), calorimetria exploratória diferencial (DSC) e os filmes PVD por espectroscopias de absorção no ultravioleta-visível (UV-vis), no infravermelho com transformada de Fourier (FTIR), espalhamento Raman, difração de raios-X, microscopias óptica e de força atômica (AFM) e caracterização elétrica cc (tensão x corrente). Os resultados mostraram que é possível a fabricação de filmes PVD de ZnPc e NiPc, uma vez que estas moléculas não são termicamente degradadas durante o processo de evaporação térmica a vácuo, e que o crescimento dos filmes pode ser controlado em escala nanométrica para ambos os materiais. Em termos estruturais, os filmes PVD de ZnPc e NiPc são cristalinos (forma α) e possuem as moléculas arranjado-se na forma de agregados e monômetros e ordenadas com o anel macrociclo inclinado em relação à superfície do substrato. Tais agregados podem ser vistos em escala nanométrica, porém, em escala micrométrica os filmes apresentam-se morfologicamente homogêneos. Em relação às propriedades ópticas e elétricas, observou-se que ambos os filmes PVD absorvem na região do visível com a ZnPc apresentando fotoluminescência quando irradiado com laser 785 nm. A condutividade elétrica é de 1,2x'10 POT. -10' S/m para a ZnPc e de 72x'10 POT... / In this work thin films of phthalocyanines of zinc (ZnPc) and nickel (NiPc) were fabricated through the vacuum thermal evaporation technique (PVD - physical vapor deposition) for different thicknesses at nanometric scale with the objective of determining the molecular architecture of these films as well as their optical and electrical properties. The final idea is to generate subsidies for applications of these films in electronic devices based on organic semiconductors and gas sensors. The PVD films were characterized using thermogravimetry (TG), differential scanning calorimetry (DSC), ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) absorption spectroscopies, Raman scattering, X-ray diffraction, optical and atomic force (AFM) microscopies, and electrical characterization (tension x current dc). The results showed that the fabrication of ZnPc and NiPc films is possible since these molecules are not thermally degraded during the process of vacuum thermal evaporation and that the growth of the films can be controlled at nanometric scale for both materials. Structurally, the PVD films of ZnPc and NiPc possess the molecules organized with the macrocycle ring tilted in relation to the substrate surface. They are crystalline (α form) and possess molecular aggregates in the form of dimmers or higher order of aggregates and monomers. Such aggregates can be seen at nanometric scale, however, at micrometric scale the films are morphologically homogeneous. In relation to the optical and electrical properties, it was observed that boh PVD films absorb in the visible region with the ZnPc presenting photoluminescence when irradiated with the 785 nm laser line. The electric conductivity at 1,2x'10 POT. -10' S/m for ZnPc and 72x'10 POT. -10' S/m for NiPc. They also presented photoconductivity with the ZnPc more photoconductor than NiPc. Finally, after thermal treatment... (Complete abstract click electronic access below)

Dans cette thèse, deux dispositifs de culture in vitro de cellules ont été développés selon des technologies de microfabrication, qui offrent de nouveaux niveaux de contrôle sur le microenvironnement de la culture cellulaire. Les applications des dispositifs développés dans la recherche sur le cancer et la neurobiologie ont été démontrées, notamment pour l'étude fondamentale de métastases du cancer et le pathfinding axonal de neurones. La puce microfluidique dédiée à la transmigration comprend des microcanaux utilisées pour mimer les capillaires des tissus le long de la trajectoire des cellules cancéreuses lors de la métastase. La transparence optique du dispositif a permis une bonne observation de la déformation et de la migration des cellules dans les capillaires artificiels. Les résultats ont montré que la déformation du noyau de la cellule rigide était une des étapes les fastidieuses du processus de transmigration. Les restrictions physiques modifient la morphologie des cellules, mais elles affectent aussi de manière significative leur profil de migration. D'autres études sur le contenu moléculaire et les propriétés biologiques des cellules transmigrées ont montré que le blocage des modifications des histones par un médicament spécifique peut inhiber la transmigration des cellules cancéreuses dans le microcanal, ce qui pourrait avoir des implications sur la prévention et le traitement du cancer. La puce microfluidique peut également être utilisée pour évaluer la déformabilité de la cellule, qui est un marqueur pronostique potentiel pour le diagnostic du cancer. La puce de la culture de neurones permet la culture de cellules dans un microenvironnement au sein duquel de protéines sont imprimées selon des motifs géométriques précis. Les somas et axones des neurones mis en culture dans le dispositif peuvent être polarisés dans différents environnements fluidiquement isolés sur une longue période. L'extension des axones peut être guidée par des protéines immobilisées sur le substrat de verre. La croissance axonale orientée peut en outre être modulée par un traitement médicamenteux localisé. Les études sur le mécanisme moléculaire sous-jacent ont révélé que ces processus ont été étroitement associés à des protéines synthétisées localement dans les extrémités d'axones en croissance / In this PhD project, two in vitro cell culture devices were developed via microfabrication technologies, which provided entirely new levels of controls over the cell culture microenvironment. The applications of the developed devices in cancer and neurobiology researches were demonstrated, specifically for the fundamental study of cancer metastasis and neural axonal pathfinding. The microfluidic transmigration chip used microchannel structures to mimic the tissue capillaries along the path of cancer cell metastasis. The transparent optical qualities of the device allowed good observation of the deformation and migration of cells in the artificial capillaries. Results showed that deformation of the stiff cell nucleus were the most time-consuming steps during the transmigration process. The physical restrictions not only changed the morphology of the cells, but also significantly affect their migration profile. Further studies on the molecular contents and biological properties of the transmigrated cells showed that blocking the histone modifications by specific drug can inhibit the transmigration of cancer cells in the microchannel, which might have implications on cancer prevention and treatment. The microfluidic chip can also be used to evaluate cell deformability, which is a potential prognostic marker for cancer diagnosis. The neural culture chip integrated microfluidic cell culture and protein patterning techniques. The somas and axons of neurons cultured in the device can be polarized into different fluidically isolated environments for long period, and the extension of the axons can be guided by proteins immobilized on the glass substrate into specific patterns. The oriented axon growth can be further modulated by localized drug treatment. Studies on the underlying molecular mechanism revealed that these processes were closely associated with the proteins synthesized locally in the tips of growing axons