O objetivo deste trabalho foi avaliar o efeito do ambiente de sinterização vácuo e argônio na resistência de união (RUMC) de cerâmicas às ligas de Ni-Cr (Fit Cast SB), Co-Cr (Star Loy C) e titânio comercialmente puro (Tritan). A partir de uma matriz de teflon, foram obtidos 60 padrões de resina/cera em forma de cilindro, com 8 mm de comprimento e 5 mm de diâmetro. Os padrões foram incluídos e os anéis foram levados ao forno e submetidos a ciclos térmicos para a expansão do revestimento. Em seguida, os anéis para fundição em Ni-Cr e Co-Cr foram levados à máquina de fundição por indução eletrônica. Os anéis referentes ao titânio foram levados à máquina de fundição por arco voltaico. Após resfriamento dos anéis, as fundições foram desincluídas e jateadas com óxido de alumínio (100 μm). Depois de recortados dos canais de alimentação, os cilindros metálicos foram preparados para aplicação da cerâmica. Em seguida, foi realizada a aplicação e sinterização da cerâmica à vácuo ou em argônio. Para as ligas alternativas, foi utilizada a cerâmica IPS Classic V e para o titânio, a Triceram. Na sequência, os cilindros compostos pelo metal e disco cerâmico (5 mm de diâmetro e 2 mm de espessura) (n=10) foram submetidos aos ensaios de RUMC por cisalhamento na máquina de ensaios universais com célula de carga de 500 Kg e velocidade do travessão móvel de 0,5 mm/min. Após os ensaios, foram realizadas análises das fraturas por meio de microscopia óptica (MO) (15X) e microscopia eletrônica de varredura (MEV). Os dados de RUMC (MPa) obtidos foram analisados estatisticamente pelos testes ANOVA e Tukey (α=0,05). Os resultados demonstraram que a sinterização à vácuo propiciou obtenção de maiores valores (MPa) de RUMC (76,58) que a sinterização em argônio (51,31). Quanto às ligas avaliadas, as de Ni-Cr e Co-Cr apresentaram maiores valores de RUMC (71,32 e 71,28, respectivamente) que o titânio cp (49,23); sendo que entre elas não houve diferença estatística. Não houve interação entre os fatores avaliados. De acordo com a MO, houve predomínio de fraturas mistas. Segundo a MEV, os espécimes de Ni-Cr e titânio sinterizados a vácuo apresentaram maior rugosidade de superfície do que os sinterizados em argônio. Para a liga de Co-Cr não houve diferença na topografia de superfície. A sinterização em argônio influenciou negativamente a RUMC dos pares metalocerâmicos analisados. / The aim of this study was to evaluate the effect of firing atmospheres: vacuum and argon on the bond strength of ceramic to Ni-Cr (Fit Cast SB), Co-Cr (Star Loy C) and commercially pure titanium (Tritan) alloys. 60 wax/acrylic resin cylinder patterns (8 mm high and 5 mm in diameter) were prepared on a plastic custom mold for metalceramic bond strength (MCBS) test. The patterns were invested in phosphated investment and manipulated on vacuum. The rings were placed in a furnace to burn out patterns and thermally expand the molds. Then, the rings of Ni-Cr and Co-Cr were placed in an electronic machine to cast. The rings related to titanium were positioned in the casting machine with a voltaic arc. After the rings have cooled, the castings were divested manually and abraded with aluminum oxide particles (100 μm). Then, the cylinders were prepared for applying of the ceramic veneering disks. The ceramic was applied and fired in vacuum and argon atmospheres. IPS-Classic ceramic was used for alternative alloys and for titanium, Triceram ceramic. Then, the cylinders composed of metal and ceramic disk (5 mm diameter and 2 mm height) (n=10) were submitted to metal-ceramic bond strength (MCBS) shear tests on an universal testing machine with load cell of 500 Kg at a crosshead speed of 0.5 mm/min. After the tests, there were made fracture analysis by optic microscopy (OM) and scanning electron microscopy (SEM). The MCBS data (MPa) were statistically analyzed by the ANOVA and Tukey test (α=0.05). The results indicated that the vacuum firing (76.58) promoted higher MCBS values than argon firing (51.31). Among the metals, Ni-Cr and Co-Cr alloys presented higher MCBS (71.32 e 71.28, respectively) than titanium (49.23); between two base alloys there was no statistical difference. There was no interaction between the evaluated factors. According to MO analysis, there was predominance of mixed fractures. According SEM, the Ni-Cr and titanium specimens submitted to vacuum presented higher surface roughness than the specimens submitted to argon. For Co-Cr, there was no difference of surface topography. The argon firing influenced negatively the MCBS of metal-ceramic evaluated pairs.

Made available in DSpace on 2014-10-09T12:27:04Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:34Z (GMT). No. of bitstreams: 1 14386.pdf: 115351 bytes, checksum: e171f39a0d4e19bac211bcd02845aa90 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:27:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:18Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:43:32Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:20Z (GMT). No. of bitstreams: 1 06631.pdf: 7171449 bytes, checksum: 14579bbc0c3bfbe0058e6387b09d94f4 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Orientadora: Márcia Rita Fernandes Machado / Banca: Maria Rita Pacheco / Banca: Maria Angélica Dias / Resumo: Considerando-se que a paca (Cuniculus paca) é o segundo maior roedor da fauna brasileira, a pesquisa sobre estes animais vem tornando-se importante, pois além de haver grande interesse na sua criação comercial, já que apresentam carne de excelente qualidade, sendo roedores, podem vir a tornar-se animais alternativos para a experimentação, e ainda, como poucas são as informações detalhadas sobre sua morfologia, objetivou-se com este trabalho descrever a morfologia, morfometria e a ultraestrutura de segmentos das porções torácica e abdominal da aorta e segmentos das porções cranial e caudal da veia cava de quatro pacas (Cuniculus paca) machos e fêmeas. Parte dos segmentos foi analisada à microscopia de luz e parte, à microscopia eletrônica de varredura. Mensurou-se as espessuras do complexo formado pelas túnicas íntima+média e túnica adventícia da aorta e veia cava e analisou-se os resultados pela estatística descritiva, teste "T" pareado (p<0,05) e teste de Tukey (p<0,05). Em relação à espessura das túnicas estudadas, notou-se que, em todos os animais, os valores referentes à espessura do complexo formado pelas túnicas íntima+média da aorta torácica cranial foram significativamente maiores, quando comparados aos valores dos outros segmentos aórticos analisados; na veia cava comprovou-se que os valores da espessura das túnicas íntima, média e adventícia, para todos os animais, foram significativamente maiores no segmento cranial. As camadas das paredes dos vasos apresentaram variações entre si quanto à estrutura e espessura, supostamente devido a uma adaptação à exigência funcional / Abstract: Considering that the paca (Cuniculus paca) is the second largest rodent of the Brazilian fauna, researches concerning these animals are becoming important because the wide interest on its commercial production since they have excellent meat quality and as rodents they could become alternatives to animal experimentation. As there is few detailed information on their morphology, the aim of this study is describe the morphology, morphometry and ultrastructure of segments of thoracic and abdominal aorta portions and segments of cranial and caudal vena cava portions in four males and females Cuniculus paca. Part of the segments were examined by light microscopy and part by scanning electron microscopy. Thickness measures of the tunica intima and media complex and tunica adventitia of the aorta and vena cava were taken and analyzed using "T" test (p <0.05) and Tukey test (p <0.05). In all animals the thickness values for the tunica intima and media complex of the cranial thoracic aorta were significantly higher when compared to the values of other aortic segments analyzed; in vena cava the thickness values of the intima, media and adventitia, for all animals, were significantly higher in the cranial segment. The layers of the vessel walls show variations in structure and thickness, presumably due to an adaptation to functional demand / Mestre

Le domaine des nanofils semi-conducteurs est en pleine expansion depuis ces dix dernières années grâce à leurs applications dans de nombreux domaines tels que l’électronique ou la conversion d’énergie. Dans cette étude on part d’une base de nanofil de germanium (le canal), on dépose des contacts métalliques qui seront chauffés par effet joule. Une différence de potentiel est alors appliquée au contact d’entrée (la source), le courant électrique est récupéré et mesuré par le contact de sortie (le drain). Une réaction à l’état solide permet aux atomes du métal de diffuser dans le nanofil. La propagation d'une phase métal/semi-conducteur est suivie dans un microscope électronique en transmission (MET) dont la résolution permet une observation à l’échelle atomique au niveau de la source, le drain et le canal. Les dispositifs caractérisés au cours de ce stage ont été élaborés à partir de deux types de membranes, l’une plane et l’autre avec des trous. Chacune d’entre elles sont constituées d’une couche de nitrate de silicium Si3N4 à leurs surfaces présentant l’avantage d’être transparents aux électrons et isolants au courant. / Semiconductor nanowires (NWs) are promising candidates for many device applications ranging from electronics and optoelectronics to energy conversion and spintronics. However, typical NW devices are fabricated using electron beam lithography and therefore source, drain and channel length still depend on the spatial resolution of the lithography. In this work we show fabrication of NW devices in a transmission electron microscope (TEM) where we can obtain atomic resolution on the channel length using in-situ propagation of a metallic phase in the semiconducting NW independent of the lithography resolution. We show results on semiconducting NW devices fabricated on two different electron transparent Si3N4 membranes: a planar membrane and a membrane where devices are suspended over holes. First we show the process of making lithographically defined reliable electrical contacts on individual NWs. Second we show first results on in-situ propagation of a metal-semiconductor phase in Ge NWs by joule heating, while measuring the current through the device. Two different devices are studied: one with platinum metal contacts and one with copper contacts. Different phenomena can occur in CuGe NWs during phase propagation.

>Magister Scientiae - MSc / The aim of this study was to produce useful composite materials from fly ash, a major waste product of coal combustion from power plants. Polyaniline-fly ash (PANI-FA) composites were prepared by in situ polymerisation of aniline in the presence of Fly Ash (FA) by two slightly different methods. In one case polystyrene sulphonic acid (PSSA) was used as a stabilizer and in another case the starting materials (aniline and FA) were aged before oxidation. The aging procedure formed nanotubes that have cross-sectional diameters of 50-110 nm. The other procedure produced nanotubes with a diameter of 100-500 nm and the length of up to 10μm. The presence of metal oxides and silica in FA were responsible for the formation of nanorods in PANI-PSSA-FA.. The formation of the composites was confirmed by UV-Vis and FTIR. The UV-Vis showed maximum absorbance at 330-360 nm ( due to π-π* transition of benzoid rings) and 600-650 nm(due to charge transfer excitons of quinoid rings), which are characteristics of emaraldine base. The electrochemical analysis of the composites showed that the composites were conductive and electroactive. The Cyclic Voltammetry of PANI-PSSA-FA showed three redox couples which are characteristics of sulphonated PANI. The morphology of the composites was studied by Scanning Electron Microscopy (SEM) and showed that our methods gave composites with improved homogeneity as compared to other reported methods. Thermo Gravimetric analysis (TGA) showed that the presence of FA in the composites improves the thermal stability of the composites by up to 100 0C.

This diploma thesis deals with the ongoing research under the auspices of the Department of Applied Physics and Technics Faculty of Education, University of South Bohemia in České Budějovice, in which the author of the work was actively participated. The thesis is divided into theoretical and experimental part. The theoretical part contains information from natural polymers, especially cellulose, plasma technology and infrared spectrometry. The subject of the experimental part of the thesis is research that deals with the functionalization of cellulose using a microwave plasma discharge on the apparatus CX-22. In the present research was also conducted to process optimization of functionalization with the liquid precursor hexamethyldisiloxane (HMDSO).

L’essor de la demande actuelle pour des matériaux architecturés, en microélectronique par exemple, ou pour des matériaux de structure, nécessite le développement d’outils de caractérisation toujours plus performants. Dans cette optique, un instrument de caractérisation multifonctionnel basé sur un couplage mécanique / électrique, a été développé au laboratoire SIMaP. Le cœur de ce dispositif est un nanoindenteur in situ FEG-SEM (Field Emission Gun Scanning Electron Microscope) couplé à des mesures électriques. Ce travail est porté par trois principales motivations: (1) L’étude du comportement mécanique d’objets petites échelles, (2) L’apport des données électriques à l’analyse quantitative du comportement mécanique pendant l’indentation, en particulier pour obtenir une meilleur estimation de l’aire de contact, (3) L’étude locale des propriétés électroniques d’empilements de films minces. L’intégration in situ SEM a été validée et permet un positionnement des indents avec une précision meilleure que 100 nm, autorisant ainsi l’étude des propriétés mécaniques à l’échelle submicrométrique. La rapidité des essais permet également des mesures statistiques. Des caractérisations mécaniques ont été menées aussi bien sur des échantillons composites massifs que sur des ilots d’or submicrométriques. Pour ce dernier cas, malgré la nature stochastique de leur comportement mécanique, une loi déterministe a pu être extraite des données mécaniques. Des mesures 3D-BCDI (Bragg Coherent Diffraction Imaging) au synchrotron ont été réalisées sur certains ilots avant et après chargement mécanique, révélant une germination de dislocations avant l’avalanche de grandes déformations plastiques. En parallèle de cette étude, des mesures électriques ont été réalisées pendant l’indentation de divers échantillons. Des mesures de nanoindentation résistive ont ainsi été effectuées sur des métaux nobles (Au) ou recouverts de leur oxyde natif (Cu, Al), soit à l’état de monocristal massif ou de film polycristallin. Les résultats quantitatifs soulignent l’importance de la présence d’une couche d’oxyde sur la réponse électrique. En présence d’un oxyde, l’interface pointe / échantillon semble être le lieu d’importantes réactions électrochimiques. En l’absence d’oxyde, la résistance mesurée peut être entièrement décrite par un modèle analytique. Dans ce cas, l’aire de contact électrique peut être prédite à partir des mesures de résistance. Enfin, des mesures capacitives ont été réalisées sur des structures MOS avec différentes épaisseurs d’oxyde. Les résultats expérimentaux sont parfaitement décrits par un modèle analytique, ce qui ouvre la voie à des mesures locales de permittivité diélectrique sous contrainte mécanique. / The increasing demand for multifunctional materials has become a recurrent challenge for a wide panel of application fields such as microelectronics and structural applications. Within the frame of this project, a multifunctional characterisation set-up has been developed at SIMaP lab, mainly based on the electrical / mechanical coupling. The heart of this device is an in situ FEG-SEM (Field Emission Gun Scanning Electron Microscope) nanoindenter coupled with an electrical measurement apparatus. This work has threefold objectives: (1) The investigation of mechanical behavior of small scale systems, (2) The input of electrical data to the quantitative analysis of mechanical behavior during indentation, in particular to obtain a better estimation of the contact area (3) The local study of electronic properties of thin film stacks. SEM integration of the device has been validated and indent positioning with a precision better than 100 nm is successfully obtained. This performance allows the studies of mechanical properties at submicrometric length scale, with a high throughput allowing statistical measurements. Various bulk composite materials have been characterized as well as submicrometric gold islands on sapphire. In the latter case, despite the stochastic nature of their mechanical behavior, a deterministic law has been extracted. 3D-BCDI (Bragg Coherent Diffraction Imaging) experiments have been performed on a few islands at synchrotron facility to investigate the crystal state before and after mechanical loading. These experiments reveal initial dislocation nucleation prior to large deformation bursts. In parallel to this study, electrical measurements have been performed during indentation on various cases. Resistive-nanoindentations have been performed on noble metals (Au) and natively oxidized metals (Cu, Al), either as bulk single crystals or as polycrystalline thin films. Qualitative results emphasize the importance of the oxide layer on the electrical response. In the presence of an oxide layer, strong electrochemical reactions seem to occur at the tip-to-sample interface. When no oxide is involved, the measured resistance can be fully described by an analytical model and the computed electrical contact area is successfully validated with residual areas measurements. Finally, capacitive measurements have been performed on MOS structures with various oxide thicknesses. Experimental results have been well described by analytical modelling, which paves the way for quantitative local dielectric permittivity measurements under mechanical loading.

As técnicas de remoção de catarata evoluíram nas últimas décadas. Na tentativa de oclusão da córnea após incisão para remoção da catarata, diversas técnicas têm sido propostas. Objetivou-se avaliar experimentalmente a viabilidade do emprego do adesivo de fibrina na oclusão da incisão de córnea em coelhos. Além disso, comparar os efeitos do adesivo de fibrina e do fio de sutura na oclusão da incisão de córnea em coelhos, utilizando-se os aspectos clínicos, a microscopia eletrônica de varredura e a morfometria. Dezesseis coelhos (Oryctolagus cuniculus) da raça Nova Zelândia foram submetidos à incisão de córnea bilateral. Para a oclusão da incisão utilizou-se aleatoriamente em um bulbo do olho, adesivo de fibrina e no seu contralateral, fio de sutura. Os períodos de avaliação foram de 7 e 15 dias. As repercussões dos procedimentos foram avaliadas utilizando-se exame oftálmico. Ao final dos períodos determinados, procedeu-se à avaliação da área perincisional desprovida de células endoteliais por meio da microscopia eletrônica de varredura da morfometria e a análise estatística inferencial foi obtida pelo teste t de Student para amostrar pareadas. Clinicamente, observaram-se melhores resultados nas amostras ocluídas com fio de sutura. No que se refere à área perincisional desprovida de células endoteliais, comparando-se os dois tipos de oclusão, a área das amostras seladas com fibrina apresentou-se maior que a área ocluída com fio de sutura. Neste estudo, ambas as técnicas foram eficazes na oclusão da córnea de coelhos. Porém, a avaliação valendo-se da microscopia eletrônica de varredura e da morfometria das eletromicrografias das áreas perincisionais do endotélio da córnea desprovidas de células ocluídas com fio de sutura demonstrou maior nível de significância quando comparada ao adesivo de fibrina. / The techniques for cataract removal had developed in the last decades. As an attempt to repair the cornea after incision, different techniques are proposed for corneal sealing. The objective of this study was to evaluate experimentally the viability of the use of fibrin adhesive in occlusion of the incision of the cornea in rabbits. Also compare clinically and by scanning electron microscopy and morphometry the fibrin adhesive and the suture on the sealing the cornea incision in rabbits. In this study, 16 rabbits (Oryctolagus cuniculus) New Zealand breed were used. It was performed bilateral corneal incision. In one eye the incision was sealed with suture, in the other eye, with fibrin adhesive randomly. The periods of evaluation varied from 7 to 15 days. The repercussions at the eye were studied using the ophthalmic exam. At the end of the determinate period, it was performed the evaluation of the perincisional area without endothelial cell by means of scanning electron microscopy, morphometry and the inferential statistical analysis was made by Student t test for paired samples. Comparing the two types of sealing, the perincisional average area without endothelial cells was higher in the fibrin tissue than wired in both groups. In this study, both techniques had corneal sealing, however, the evaluation by scanning electron microscopy,and electromicrographs morphometry of the perinsional areas of the corneal endothelium without devoid cells occluded with suture wire has higher level significance when compared with fibrin adhesive.