L’imagerie préclinique dans le domaine de la cancérologie est en plein essor. Elle permet grâce à des modèles animaux représentatifs de cancers humains de comprendre les mécanismes de développement des pathologies et d’évaluer l’efficacité thérapeutique d’un nouveau traitement. Le principal objectif de ce travail a été de développer deux modèles orthotopiques de cancer (pancréas et colon) et d’évaluer des traitements de références ainsi qu’une nouvelle stratégie thérapeutique par plasma froid fibré appelée Plasma Gun. Les 2 modèles de cancers développés ont montré une bonne représentativité vis-à-vis des cancers humains, avec l’apparition de métastases à distance et la présence de zones hypoxiques. Le 5-fluorouracile pour le modèle orthotopique de carcinome colorectal HCT116-luc et la gemcitabine pour le modèle d’adénocarcinome pancréatique MIA PaCa2-luc ont induit à faible dose des effets discrets pouvant être mis en évidence grâce aux modalités d’imageries mises en oeuvre. Après validation de nos démarches expérimentales une nouvelle stratégie thérapeutique, le Plasma Gun, a été évaluée et a montré des effets significatifs sur l’inhibition de la croissance tumorale. Le second objectif de ma thèse a été de mettre en oeuvre des outils pour l’induction et la caractérisation des métastases osseuses ainsi que pour l’imagerie haute résolution de la vascularisation. D’une part, les métastases osseuses obtenues par injection de cellules PC3M-luc en intracardiaque ont été évaluées et quantifiées grâce à différentes modalités d’imagerie (bioluminescence, scintigraphie et scanner X). D’autre part, la réalisation d’une imagerie haute résolution de la vascularisation a été possible grâce à la technique de casting qui permet de recréer la structure 3D de l’architecture vasculaire suite à l’injection d’une résine dans la circulation. Les développements réalisés lors de cette thèse ont ainsi permis d’apporter des outils pour l’évaluation préclinique de nouvelles thérapies anticancéreuses. / Preclinical imaging in oncology is booming. It allows, using representative animal models of human cancers, to understand the mechanisms of development of pathologies and to assess the therapeutic efficiency of a new treatment. The main objective of this work was to develop two orthotopic models of cancer (pancreas and colon) and to assess on them the reference treatments as well as a new therapeutic strategy by non thermal plasma so called Plasma Gun. The two cancer models developed showed good representation in relation to human cancers, with the appearance of distant metastases and hypoxia. 5-fluorouracil for the HCT116-luc orthotopic model of colorectal carcinoma and gemcitabine for the MIA PaCa2-luc pancreatic adenocarcinoma model, have induced discrete effects at low dose wich can be detected thanks imaging modalities. After validation of our experimental steps, a new therapeutic strategy, Plasma Gun was evaluated and showed significant effects on tumor growth inhibition. The second objective was to carry out tools for the induction and the characterization of bone metastases and for high resolution imaging of the vasculature. On the one hand, bone metastases obtained by injection of PC3M-luc cells intracardially, was evaluated and quantified with different imaging modalities (bioluminescence, scintigraphy and Computed Tomography). And the other hand, the achievement of a high resolution imaging of vascularization, was possible by the casting method that restores the 3D structure of the vascular architecture following injection of a resin in the circulation.

Estudos recentes têm demonstrado que o aprimoramento dos revestimentos odontológicos para o uso da técnica de fundição rápida pode ser considerado uma realidade no seu uso diário no laboratório de prótese. Desta forma, obtêm-se peças metálicas fundidas em menor tempo, produz-se mais em pouco tempo e, diminuem-se os custos sem perda da qualidade. Mesmo assim, ainda há incógnitas sobre como estes revestimentos se expandem. Imagina-se que para obter a melhor adaptação cervical é necessária a maior expansão total do revestimento, mas alguns estudos têm demonstrado que outros fatores podem ser determinantes para obter a melhor adaptação cervical. O objetivo deste trabalho foi averiguar a adaptação cervical de infra-estruturas metálicas à base de Ni-Cr obtidas com quatro revestimentos odontológicos para a técnica de fundição rápida e analisar as expansões de presa e térmica dos mesmos. De cada revestimento foram obtidos 10 corpos de prova. Na análise da expansão de presa e térmica utilizou-se 3 corpos de prova de cada revestimento. Para a análise estatística, utilizou-se o ANOVA e o Teste de Tukey. Estas análises demonstraram que o uso do revestimento Heat Shock resultou na melhor adaptação cervical, seguido do Flash, Bellavest SH e Micro-Fine 1700. Na expansão de presa, no período de 15 minutos após a inclusão, nenhum dos revestimentos havia completado a sua total expansão. Na expansão térmica, dentro do forno no período de 20 minutos, todos os revestimentos apresentaram a expansão completada dentro de 15 minutos. Conclui-se que todos os revestimentos têm o potencial a oferecer peças fundidas com adaptação cervical adequada e que a obtenção da mesma não depende apenas da maior expansão total, mas também do comportamento da expansão de presa e da expansão térmica. Há também indícios de que a resistência à compressão do revestimento desempenha importância considerável. / With the improvement of dental investments for accelerated casting technique, recent studies have demonstrated that the procedure can be considered safe for daily use in the dental laboratory. Thus, cast pieces can be obtained in less time, the prosthetic work as a whole can be speed up and costs are cut with no quality compromise. Even though, there are still unanswered questions on how investments expand. It is thought that to reach the best cervical adaptation the greatest investment total expansion is needed, but some studies have demonstrated that other factors can be determining. The aim of this study was to verify the cervical adaptation of nickelchromium crowns cast using four dental investments for the accelerated casting technique and to analyze the curing and thermal expansion of such investments. For each investment, ten samples were obtained. For thermal expansion analysis three samples of each investment were used. For statistical purposes ANOVA and Tukey tests were used. The use of Heat Shock yielded the best results of cervical adaptation, followed by Flash, Bellavest SH and Micro-Fine 1700. For thermal expansion, 15 minutes after investment, none of the investments had reached their complete expansion. After 20 minutes inside the oven all investments had completed their expansion. It was concluded that all investments tested are suitable to offer cast pieces with adequate cervical adaptation. Adaptation depends not only of the greatest total expansion, but also of the curing and thermal expansion. There are indications that investment compression strength plays an important role on the technique.

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No. of bitstreams: 2 Dissertação - Ítalo Careli Gondim - 2017.pdf: 3904278 bytes, checksum: bf91c0faaf4452872583b733ae957fd6 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-03-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / With the large accumulation of non-biodegradable packaging waste, along with the difficulty of recycling most of them, the stimulus to develop biodegradable packaging from renewable sources and contributes to the preservation of fruit quality. The present study aimed to produce and characterize edible films based on rice flour, pectin and sorbitol, applying the casting technique, and to evaluate the effect of the addition of rice husk celluloid nanofibers and potassium sorbate solution. The films were evaluated for mechanical properties, water vapor permeability, pH, opacity and water solubility, and characterized the best thermal properties, wettability and microstructural characteristics to be applied in fruits as an edible coating in order to increase the time Postharvest. Strawberry, guava and avocado were coated for 20 days, a post-harvest study was carried out with respect to the physiochemical and physiological quality of the respiratory rate, loss of mass, pH, soluble solids, titratable acidity, ascorbic acid content, Antioxidant activity, total phenolics, color, texture and pigments (chlorophyll and anthocyanins). The films with 5 g of rice flour, 5 g of pectin, 25 mL of sorbitol solution, 3 mL of rice husk cellulosic nanofibres and 2 mL of potassium sorbate solution show good processability, allowing the production of edible coating, With mechanical properties, water vapor barrier and opacity that may contribute to prolong post-harvest time of fruits. It is possible to double the shelf life of strawberries by applying the edible coating. The coating contributed to delay the ripening of the avocados, reducing the respiratory rate, the loss of mass, helping to maintain the firmness of the fruits and delaying the ripening of the fruits for 12 days with the application of the coating. The edible coating contributed to retarding the metabolism of the coated guava by doubling the ripening start time along the refrigerated storage. / Com o grande acumulo de resíduos de embalagens não biodegradáveis, junto com a dificuldade de reciclagem da maior parte dessas, o estimulo de desenvolver embalagens biodegradáveis a partir de fontes renováveis e contribuir para a preservação da qualidade dos frutos. O presente estudo teve como objetivo produzir e caracterizar filmes comestíveis à base de farinha de arroz, pectina e sorbitol, aplicando a técnica de casting, e avaliar o efeito da adição de nanofibras celulosídicas de casca de arroz e solução de sorbato de potássio. Os filmes foram avaliados quanto à s propriedades mecânicas, permeabilidade ao vapor de água, pH, opacidade e solubilidade em água, e caracterizado o melhor quanto a propriedade térmica, molhabilidade e característica microestrutural para aplicar em frutas como revestimento comestível o intuito de aumentar o tempo de pós-colheita. Morango, goiaba e abacate foram revestidos por 20 dias, realizado um estudo de pós-colheita, com relação à qualidade físico-química e fisiológica quanto a taxa respiratória, perda de massa, pH, sólidos solúveis, acidez titulável, teor de ácido ascórbicos, atividade antioxidante, fenólicos totais, cor, textura e pigmentos (clorofila e antocianinas). Os filmes com 5 g de farinha de arroz, 5 g de pectina, 25 mL de solução de sorbitol, 3 mL de nanofibras celulosídicas de casca de arroz e 2 mL de solução de sorbato de potássio apresentam boa processabilidade, possibilitando a produção de revestimento comestível, com propriedades mecânicas, de barreira ao vapor de água e opacidade que poderão contribuir para prolongar o tempo de pós-colheita de frutos. É possível dobrar a vida útil de morangos, com a aplicação do revestimento comestível. O revestimento contribuiu para retardar o amadurecimento dos abacates, reduzindo a taxa respiratória, a perda de massa, auxiliando na manutenção da firmeza dos frutos e retardando o amadurecimento dos frutos por 12 dias com a aplicação do revestimento elaborado. O revestimento comestível contribuiu para o retardamento do metabolismo da goiaba revestida dobrando o tempo de início do amadurecimento ao longo do armazenamento sob refrigeração.

Aluminium die casting is a process used to transform molten aluminium material into automotive gearbox housings, wheels and electronic components, among many other uses. It is used because it is a very efficient method of achieving near net shape with the required mechanical properties. Life Cycle Assessment (LCA) is a technique used to determine the environmental impacts of a product or process. The Life Cycle Inventory (LCI) is the initial phase of an LCA and describes which emissions will occur and which raw materials are used during the life of a product or during a process. This study has improved the LCI technique by adding in manufacturing and other costs to the ISO standardised methods. Although this is not new, the novel application and allocation methods have been developed independently. The improved technique has then been applied to Aluminium High Pressure Die Casting. In applying the improved LCI to this process, the cost in monetary terms and environmental emissions have been determined for a particular component manufactured by this process. A model has been developed in association with an industry partner so this technique can be repeatedly applied and used in the prediction of costs and emissions. This has been tested with two different products. Following this, specialised LCA software modelling of the aluminium high pressure die casting process was conducted. The variations in the process have shown that each particular component will have different costs and emissions and it is not possible to generalise the process by modelling only one component. This study has concentrated on one process within die casting but the techniques developed can be used across any variations in the die casting process.

Resumo: Esse estudo avaliou o efeito da tecnica de inclusao de revestimentos fosfatados nafluidez, rugosidade de superficie, camada de reacao (α-case) e adaptacao marginal de copings fundidos em Ti cp. Os padroes foram incluidos de forma convencional ou pela tecnica de inclusao experimental, na qual os padroes foram cobertos comRematitan Ultra - RU previamente a inclusao. Os revestimentos fosfatados estudados foram: Rematitan Plus (RP), Rema Exakt (RE), Castorit Super C (CA) e o revestimento a base de espinelio Rematitan Ultra (RU) foi o grupo controle. Sete grupos experimentais foram constituidos: G1: RU (controle); G2: RP; G3: RP e RU; G4: RE; G5: RE e RU; G6: CA; G7: CA e RU. Para fluidez foram feitos corpos-de-prova quadrados (15 mm X 15 mm X 0.3 mm) e a area (mm2) foi medida por um sistema analisador de imagens (n=8). Para a rugosidade de superficie as medidas (Ra) foram feitas em rugosimetro Mitutoyo (Mitutoyo SJ 400, Kanagawa, Japan) em corpos-de-prova quadrados (12 mm x 12 mm x 2 mm) n =8. A camada de reacao foi analisada por dureza Vickers, micro-analise por energia dispersiva (EDX), microscopia optica e a composicao dos revestimentos. Para dureza Vickers as medidas foram feitas em corpos-de-prova cilindricos (obtidos a partir dos sprues fundidos nos copos-de-prova para o teste de fluidez) em profundidades de 25, 50, 100, 150, 200 e 300Wm da superficie para o centro, em durometro Micromet 2100 (Buehler, Lake Bluff, Illinois, EUA) n= 8. Para a micro-analise por energia dispersiva (EDX) um equipamento EDX LINK ANALYTICAL, modelo QX 2000, com microscopio eletronico LEO (Zeiss - Germany) e detector OXFORD (Oxford Instrumentos de nano-analises Halifax Alta Rotacao WycombeBucks-HP12 3SE, UK) foram feitas em tres areas da camada de reacao (25 Wm, 75Wm e 150 Wm). Para a microscopia optica, as amostras foram polidas e limpas com solucao acida de Kroll por 20 segundos e observadas em Microscopio... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study evaluated the effect investing technique with phosphate-bonded investment on the castability, surface of roughness, reaction layer (α-case) and marginal coping fit of CP titanium. For all analysis the specimen were coated with Rematitan Ultra - RU (experimental technique), previously to the inclusion (conventional technique) and invested into the phosphate-bonded investments: Rematitan Plus (RP), Rema Exakt (RE), Castorit Super C (CA). The seven groups studied were: G1: RU (control), G2: RP; G3: RP and RU; G4: RE; G5: RE and RU; G6: CA; G7: CA and RU. For castability, square patterns (15 mm X 15 mm X 0.3 mm) were made. The castability area (mm2) was measured by an image analysis system (n=8). The surface roughness was measured (Ra) with a rugosimeter Mitutoyo (Mitutoyo SJ 400, Kanagawa, Japan) in square resin patterns (12 mm x 12 mm x 2 mm) n =8. The reaction layer was analyzed by Vicker's hardness, Energy Dispersive X-ray microanalysis (EDX), optical microscopy and the investments composition were studied by X ray diffraction (XRD). The Vicker's hardness measurements were made sprue of castability test in cross - section at depths of 25, 50, 100, 150, 200 and 300Wm from the surface to the interior, using a durometer Micromet 2100 (Buehler, Lake Bluff, Illinois, EUA) n= 8. For Energy Dispersive X-ray microanalysis (EDX) was used an equipment EDX Link Analytical, model QX 2000, with Microscopy Electronic LEO (Zeiss - Germany) with detector Oxford (Oxford Instruments-Nano Analysis Halifax Road High WycombeBucks-HP12 3SE, UK) in three areas of reaction layer (25 Wm, 75Wm e 150 Wm). For the optical microscopy the samples were polished, cleaned and acid etched with the Kroll solution for 20 seconds and observed in an optical microscope Quimis (200 X) attached to an image analyzer Leika Qwin. For the study of the investments composition, samples with... (Complete abstract click electronic access below) / Orientador: Gelson Luís Adabo / Coorientador: Ricardo Faria Ribeiro / Banca: Sicknan Soares da Rocha / Banca: Renata Crisrina Silviera Ferracioli / Banca: João Neudenir Arioli Filho / Banca: Carlos Alberto dos Santos Cruz / Doutor

Dans le cadre de ce travail, une méthode chimique, la voie « polymère précéramique », a été mise en œuvre pour générer des (nano)composites céramiques à matrice de carbure, carbonitrure et nitrure de silicium et contenant des (nano)cristaux à base de métaux de transition (Ti ou Zr). Ces matériaux ont été préparés sous forme d’objets massifs. Cette thèse consiste tout d’abord en un premier chapitre de bibliographie décrivant les (nano)composites, la méthode de préparation mise en œuvre dans ce manuscrit ainsi que les matériaux visés et leur application, principalement dans le domaine de l’énergie nucléaire et solaire à concentration. L’étude consiste dans un deuxième chapitre à décrire les méthodes de synthèse mises en jeu dans notre étude ainsi que les différentes techniques de caractérisation mises en œuvre pour caractériser les précurseurs de départ, les matériaux au cours de leur élaboration et les matériaux finaux. Le chapitre 3 s’est intéressé à l’élaboration des (nano)composites autour du système Si-C-Ti, pouvant notamment entrer dans la composition de gaines à combustible au sein des réacteurs nucléaires à fission de génération IV. Ces matériaux ont été élaborés à partir de mélanges de nanopoudres à base de titane et d’un polycarbosilane hyperbranché, l’allylhydridopolycarbosilane (AHPCS). Les nanopoudres à base de titane jouent le rôle de charges passives/actives dans l’AHPCS pour s’opposer au retrait volumique que subit le polymère lorsque celui-ci est pyrolysé sous argon à 1000°C. Des objets massifs sont élaborés par moulage. Une étude détaillée du comportement à la pyrolyse des différentes formulations est faite et les matériaux finaux ont été caractérisés structuralement. Une étude préliminaire en implantation hélium de ces matériaux est réalisée. Dans le chapitre 4, nous nous sommes intéressés au même système en travaillant plus particulièrement la chimie de polymères précéramiques. L’objectif a été de synthétiser des polymères dit à « source unique » (=polytitanocarbosilanes) qui, par des traitements thermiques appropriés, conduisent à des (nano)composite dans lesquels des nanocristaux de carbure de titane (nc-TiC) sont dispersés dans une phase amorphe ou cristallisée de carbure de silicium sans phases secondaires comme dans l’approche détaillée au chapitre 3. Ces polymères ont été synthétisés pour être adaptés à la conception d’objets massifs par compactage à chaud puis traitement thermique des compacts polymères. Les matériaux finaux ont alors été caractérisés par différentes techniques afin de sélectionner les paramètres opératoires, allant de la synthèse des polymères à leur conversion en céramique, conduisant aux (nano)composite souhaités (e.g. matrice amorphe de carbure de silicium) avec les propriétés visées (e.g. comportement sous implantation Helium). Dans un cinquième chapitre, l’étude est plus fondamentale et vise à suivre la même démarche de chimiste que le chapitre 4 pour synthétiser des polymétallocarbosilazanes qui sont des précurseurs des systèmes carbonitrures et nitrures de type Si-N-M-(C) (M = Ti, Zr). Une étude de l’effet de la nature du polymère sur les propriétés des (nano)composites est notamment entreprise par RMN du solide, analyse thermogravimétrique et diffraction des rayons X. Une étude préliminaire d’application de ces matériaux en énergie solaire à concentration est proposée. / In the present work, the Polymer Derived Ceramics (PDCs) route has been investigated to prepare silicon carbide (SiC), silicon carbonitride (SiCN) and silicon nitride (Si3N4) matrix (nano)composites in which transition metal-containing (nano)phases (Ti or Zr) are distributed. This approach has been applied to produce bulk materials. In the first chapter, we develop a literature review on the definition and the different types of nanocomposites, the different strategies to prepare them with a particular focus on the PDCs route and the targeted applications in the nuclear and concentrating solar system energy field. In a second chapter, the synthesis experimental protocols and the various methods to characterize the materials at each step of their preparation have been described. The third chapter focuses on the Si-C-Ti compositional system which displays potential to be used in the fuel cladding of the 4th generation of nuclear fission reactor. The precursors are prepared by mixing titanium (Ti)-based nanofillers and a hyperbranched polycarbosilane named allyhydridopolycarbosilanes (AHPCS) to be cast into a green compact then pyrolyzed to generate bulk (nano)composites which represent multiphase materials according to the composition of the nanofillers. In particular, the active behavior of Ti nanopowders into the AHPCS significantly limit the volume shrinkage of the polymer during its pyrolysis at 1000°C under argon to form (nano)composites composed of titanium carbide, titanium silicide and silicon carbide phases. Their structure has been investigated in details and a preliminary study on helium implantation has been done on these materials. In the chapter IV, we considered the same system. Here, our objective was to focus on the chemistry of preceramic polymers to prepare single-source precursors called polytitanocarbosilanes. We investigated their chemistry and structure by solid-state NMR as well as their pyrolysis behavior by thermogravimetric analyses up to 1000°C under argon. Amorphous materials were generated at 1000°C. Titanium carbide nanocrystals precipitated during a further heat-treatment up to 1600°C in a silicon carbide matrix. Dense pieces were prepared by warm-pressing of polytitanocarbosilanes followed by pyrolysis of the green compact. Helium implantation tests have been done and compared with the results gained in chapter 3. In the fifth chapter, we followed the same strategy, with a more fundamental aspect, for (nano)composites prepared in the Si-N-M-(C) (M=Ti, Zr). The effect of the polymetallocarbosilazane formulation on the (nano)composite properties has been investigated by solid-state NMR analysis, thermogravimetric analysis and X-ray diffraction. The structural evolution of these materials has been investigated up to 1600°C under ammonia and nitrogen atmosphere. The final materials represent nanocomposites of the type nc-TiN/a-Si3N4 with nc, nanocrystals and a being amorphous after a pyrolysis at 1400°C. By increasing the temperature up to 1600°C, the matrix crystallized. The effect of zirconium instead of titnanium has been investigated. A preliminary study on the potential of these materials as solar absorber for concentrating solar power (CSP) is reported.

Made available in DSpace on 2014-10-09T12:41:52Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:05Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:41:52Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:05Z (GMT). No. of bitstreams: 0 / O objetivo deste trabalho foi determinar a influência do ferro e do manganês em uma liga de alumínio com 9% de silício (% em peso). Para isto, foram elaboradas duas famílias de liga Al-9%Si: uma com os teores de 0,1%, 0,4%, 0,8% e 1,2% de Fe e uma segunda liga de Al-9%Si-0,8%Fe com teores de 0,1%, 0,4% e 0,7% de Mn. Para a realização deste estudo, foram produzidos corpos de prova de tração fundidos em coquilha, segundo a norma ASTM B108. Os corpos de prova obtidos foram tracionados para avaliação das propriedades mecânicas, em seguida, foram submetidos a uma análise microestrutural por microscopia óptica (MO) e eletrônica de varredura (MEV). As superfícies de fratura dos corpos de prova tracionados foram também observadas por MEV com a finalidade de comparar o efeito das adições de Fe e Mn. O efeito da adição crescente de Fe na liga Al-9%Si foi observado no ensaio de tração que mostrou queda tanto nos limites de resistência e de escoamento como no alongamento, decorrentes da formação da fase β-Al5FeSi que apresentou morfologia em plaquetas, interrompendo a continuidade da matriz de alumínio. Para teores abaixo de 0,4% de Fe, ocorreu um ligeiro aumento da resistência mecânica que pode ser atribuído à formação da fase α-Al8Fe2Si, que apresentou morfologia tipo escrita chinesa, que não interrompe a continuidade da matriz. Com adição de teores crescentes de Mn na liga Al-9%Si-0,8%Fe ocorreu uma elevação do limite de resistência e do alongamento, mas uma queda do limite de escoamento, quando comparados com a mesma liga sem adição de Mn. Conclui-se que esse comportamento pode ser atribuído a mudança de morfologia do intermetálico de plaquetas para escrita chinesa que intercala a matriz dúctil com a fase frágil, devido a adição do Mn. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Estudos recentes têm demonstrado que o aprimoramento dos revestimentos odontológicos para o uso da técnica de fundição rápida pode ser considerado uma realidade no seu uso diário no laboratório de prótese. Desta forma, obtêm-se peças metálicas fundidas em menor tempo, produz-se mais em pouco tempo e, diminuem-se os custos sem perda da qualidade. Mesmo assim, ainda há incógnitas sobre como estes revestimentos se expandem. Imagina-se que para obter a melhor adaptação cervical é necessária a maior expansão total do revestimento, mas alguns estudos têm demonstrado que outros fatores podem ser determinantes para obter a melhor adaptação cervical. O objetivo deste trabalho foi averiguar a adaptação cervical de infra-estruturas metálicas à base de Ni-Cr obtidas com quatro revestimentos odontológicos para a técnica de fundição rápida e analisar as expansões de presa e térmica dos mesmos. De cada revestimento foram obtidos 10 corpos de prova. Na análise da expansão de presa e térmica utilizou-se 3 corpos de prova de cada revestimento. Para a análise estatística, utilizou-se o ANOVA e o Teste de Tukey. Estas análises demonstraram que o uso do revestimento Heat Shock resultou na melhor adaptação cervical, seguido do Flash, Bellavest SH e Micro-Fine 1700. Na expansão de presa, no período de 15 minutos após a inclusão, nenhum dos revestimentos havia completado a sua total expansão. Na expansão térmica, dentro do forno no período de 20 minutos, todos os revestimentos apresentaram a expansão completada dentro de 15 minutos. Conclui-se que todos os revestimentos têm o potencial a oferecer peças fundidas com adaptação cervical adequada e que a obtenção da mesma não depende apenas da maior expansão total, mas também do comportamento da expansão de presa e da expansão térmica. Há também indícios de que a resistência à compressão do revestimento desempenha importância considerável. / With the improvement of dental investments for accelerated casting technique, recent studies have demonstrated that the procedure can be considered safe for daily use in the dental laboratory. Thus, cast pieces can be obtained in less time, the prosthetic work as a whole can be speed up and costs are cut with no quality compromise. Even though, there are still unanswered questions on how investments expand. It is thought that to reach the best cervical adaptation the greatest investment total expansion is needed, but some studies have demonstrated that other factors can be determining. The aim of this study was to verify the cervical adaptation of nickelchromium crowns cast using four dental investments for the accelerated casting technique and to analyze the curing and thermal expansion of such investments. For each investment, ten samples were obtained. For thermal expansion analysis three samples of each investment were used. For statistical purposes ANOVA and Tukey tests were used. The use of Heat Shock yielded the best results of cervical adaptation, followed by Flash, Bellavest SH and Micro-Fine 1700. For thermal expansion, 15 minutes after investment, none of the investments had reached their complete expansion. After 20 minutes inside the oven all investments had completed their expansion. It was concluded that all investments tested are suitable to offer cast pieces with adequate cervical adaptation. Adaptation depends not only of the greatest total expansion, but also of the curing and thermal expansion. There are indications that investment compression strength plays an important role on the technique.

Intermetallic alloys gama TiAl are prospective materials of future thanks its excellent machanical qualities and low density. However this alloy clash with for wider expansion to the practice on burdensomeness production and processing. Among disavantages belongs to also her bad fluidity. The diploma work is angaged in possibilities imporing fluidity alloys TiAl by the help of centrifuge casting. Casting healthy casts was achieved in experimental part.