Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work the structural and magnetic properties of (Y,TR)CrO3+γ (TR = Dy, Gd, Nd e Pr e γ = 0 ou 1) and YFe1-xCrxO3 (0 ≤ x ≤ 1) samples were studied and synthesized by coprecipitation method. The analysis of X-ray diffraction (XRD) allied to the Rietveld refinement method confirmed the formation of all phases in the systems proposed. The results of X ray absorption near edge (XANES) at K edge of Cr and Fe in YFe1-xCrxO3 series indicate a system mixed valences of Cr2+/Cr3+ and Fe2+/Fe3+. For the family of compounds (Y,TR)CrO3+γ, XRD in situ as a function of temperature measurements were performed and the results show a phase transition (Y,TR)CrO4 with tetragonal structure and space group I41/amd to the phase of perovskite (Y,TR)CrO3 with orthorhombic structure and space group Pbnm. These results were also confirmed by XANES in situ as a function of temperature measured in K Cr edge, which show a change in the XANES profile and pre and post edge energy due to change Cr5+ oxidation state (Y,TRCrO4) to Cr3+ oxidation state (TR,YCrO3). These results also show that depending on the ion Y or TR, the phase transition temperature unchanged. The magnetization measurements as a function of magnetic field and temperature for the samples of YFe1-xCrxO3 (0,5 ≤ x ≤ 1) (0.5 ≤ x ≤ 1) have antiferromagnetic ordering accompanied by a weak ferromagnetism. These results were also observed a strong dependence of TN with the Fe concentration in the structure. The reverse magnetization phenomenon was observed for the YFe0,5Cr0,5O3 sample, and the results show that this phenomenon has a strong dependence on the applied field. The magnetization measurements as a function of magnetic field and temperature ferromagnetic ordering to (Y, Dy, Gd)CrO4 and antiferromagnetic for (Nd,Pr)CrO4 samples, where the magnetic transition temperature occurred between 6 to 22 K. As for the systems (Dy,Gd, Nd, Pr)CrO3 samples showed predominant antiferromagnetic ordering, usually with two TN1 and TN2 transitions. / Neste trabalho foram estudadas as propriedades estruturais e magnéticas das amostras (Y,TR)CrO3+γ (TR = Dy, Gd, Nd e Pr e γ = 0 ou 1) e YFe1-xCrxO3 (0 ≤ x ≤ 1) sintetizadas pelo método da coprecipitação. As análises de difração de raios X (DRX) aliadas ao método de refinamento Rietveld confirmaram a formação das fases principais em todos os sistemas propostos. Os resultados de absorção de raios X próximo à borda (XANES) obtidos na borda K do Cr e Fe para série YFe1-xCrxO3 indicam um sistema de valências mistas de Cr2+/Cr3+ e Fe2+/Fe3+. Para a família de compostos (TR,Y)CrO3+γ, as medidas de DRX in situ em função da temperatura mostram uma transição de fase de (Y,TR)CrO4 com estrutura tetragonal e grupo espacial I41/amd para a fase do tipo perovskita (Y,TR)CrO3 que possui estrutura ortorrômbica pertencente ao grupo espacial Pbnm. Estes resultados foram também confirmados através de medidas XANES in situ em função da temperatura na borda K do Cr, os quais apresentam uma mudança significativa no perfil XANES e na energia de pré e pós borda devido a mudança do estado de oxidação Cr5+ (TR,YCrO4) para o estado de oxidação Cr3+ (TR,YCrO3). Esses resultados também mostram que a depender do íon Y ou TR, as temperaturas de transição de fase sofrem alterações. As medidas de magnetização em função do campo magnético e da temperatura para as amostras da série YFe1-xCrxO3 (0,5 ≤ x ≤ 1) apresentam ordenamento antiferromagnético acompanhado de um ferromagnetismo fraco. Nesses resultados também foi observado uma forte dependência da TN com a concentração de Fe na estrutura. O fenômeno de magnetização reversa foi observado para a amostra YFe0,5Cr0,5O3, e os resultados mostram que este fenômeno tem forte dependência com o campo aplicado. As medidas de magnetização em função do campo magnético e da temperatura indicam um ordenamento ferromagnético para as amostras (Y,Dy,Gd)CrO4 e antiferromagnético para (Nd,Pr)CrO4, onde as temperatura de transição magnética ocorreram entre 6 e 22 K. Já para os sistemas (Dy,Gd,Nd,Pr)CrO3 as amostras apresentaram ordenamento antiferromagnético predominantes, geralmente com duas transições TN1 e TN2.

Orientador: Anselmo Eduardo Diniz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-09T18:35:54Z (GMT). No. of bitstreams: 1 Marques_DanielCirillo_M.pdf: 1133787 bytes, checksum: 7116947050a42005d85657f4c29da1a2 (MD5) Previous issue date: 2007 / Resumo: O objetivo deste trabalho foi estudar a influência do teor de níquel de ligas FeCrNi na vida da ferramenta de metal duro em processo de torneamento em acabamento. Para este estudo foram preparadas ligas com composição básica 18%Cr-0,01%C-0,2%Si-0,4%Mn e com teores de níquel variados (0, 10, 20, 30, 40, 50 e 60%). A medida que o teor de níquel subia, o teor de ferro diminuía na mesma proporção. Os ensaios foram realizados com pastilhas de metal duro classe M15 revestidas com TiC/Al2O3/TiN. Todos os materiais foram usinados nas mesmas condições (vc = 230 m/min, ap = 0,6 mm e f = 0,1 mm/volta), garantindo assim, como única fonte de variação, o teor de níquel. Os resultados mostram que a vida da ferramenta diminui com o aumento do teor de níquel e que o principal mecanismo de desgaste da ferramenta é a adesão e arrancamento de partículas da ferramenta. Uma exceção se deu com o material com 30% de níquel, que apesar de apresentar o mesmo mecanismo de desgaste, mostrouse mais fácil de usinar, gerando maior tempo de vida da ferramenta / Abstract: The aim of this work was to study the influence of nickel content in FeCrNi alloys on the coated cemented carbide tool life during the finish turning process. For this purpose 18%Cr-0,01%C-0,2%Si-0,4%Mn base composition and variable nickel content (0, 10, 20, 30, 40, 50 and 60 weight %) alloys were prepared. As the nickel content increased, the iron content decreased in the same proportion. Tests were carried out with coated cemented carbide inserts, M15 class with TiC/Al2O3/TiN coating. All alloys were machined on the same cutting conditions (vc = 230 m/min, ap = 0,6 mm and f = 0,1 mm/rev), in order to set nickel content as the only input variable. Results indicate that tool life decreases with the growth of nickel content, and the mainly tool wear mechanism is attrition. An exception was the material with 30% of nickel, that presented the same tool wear mechanism but showed out higher machinability, allowing longer tool life / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Os ânions inorgânicos nitrato (NO3-) e nitrito (NO2-) por muito tempo foram considerados produtos finais inertes do metabolismo do óxido nítrico (NO) e constituintes indesejáveis da dieta. Entretanto, é crescente o interesse das potenciais reações que podem se processar em meio fisiológico e, que envolvem especialmente o íon nitrito mediadas por complexos de metais de transição. Ferro-heme presente em proteínas como a mioglobina podem formar complexos porfirínicos com NO, gerando espécies que podem atuar principalmente como catalisadores em diversas vias biológicos importantes. Complexos com NOx coordenado a ferro-heme estão envolvidos tanto no processo da cura da carne (pigmentação da carne), como em processos redox, nos quais são capazes de oxidar substratos indiretamente pela produção de espécies reativas ou diretamente por reações de transferência de átomo de oxigênio (TAO). Os lipídeos, constituintes celulares fundamentais na composição de membranas e lipoproteínas, podem servir como substratos para essas reações e, sua oxidação pode ocasionar danos ao organismo. Tióis, importantes antioxidantes e constituintes de proteínas, também podem participar desse tipo de reações e, conseqüentemente gerar danos ao organismo. Considerando que o mecanismo e os parâmetros cinéticos e termodinâmicos destas reações ainda não foram completamente estabelecidos para explicar a vasta funcionalidade destes complexos, o presente projeto de pesquisa visa proporcionar um melhor conhecimento das reações redox envolvendo NOx e mediadas por porfirinas de ferro em alimentos e sistemas biológicos. / For long time, the anions nitrate (NO3-) and nitrite (NO2-) were considered inert end products of nitric oxide (NO) metabolism and undesirable constituents of the diet. Currently, there is an increasing interest for potential reactions which may occur in physiological conditions involving specially the nitrite ion and mediated by transition metal complexes. Heme NOx iron complexes are involved in meat curing process (meat pigmentation) and are able to oxidize substrates indirectly generating reactive species or directly by oxygen atom transfer reactions (OAT). Lipids, fundamental cellular constituents of membranes and lipoproteins, and thiols, important antioxidants and protein constituents, may serve as substrates to OAT and their oxidation may promote damage to the organism Considering that the mechanism and kinetic and thermodinamic parameters of these reaction have not yet been fully elucidated to explain the varied functionality of these complexes, the present research project aim to bring a better understanding of redox reactions involving NOx mediated by iron porphyrins in foods and biological systems. Thiols, important antioxidants and protein constituents, may serve as substrates to OAT and their oxidation may promote damage to the organism. The present work aims to bring a better understanding of the mechanism, kinetic and thermodynamic parameters of the reaction involving nitrite mediated by iron-porphyrins in food and biological systems.

Made available in DSpace on 2014-08-20T13:59:11Z (GMT). No. of bitstreams: 1 dissertacao_janete_mariza_adamski.pdf: 870957 bytes, checksum: 3780a4713aace89a20cbc46f8e882d7f (MD5) Previous issue date: 2011-02-15 / Iron is an essential element for growth and development of plants and is involved in essential metabolic processes such as photosynthesis and respiration. However, homeostasis of this metal is essential, both excess and deficiency are harmful. One of the characteristic symptoms of deficiency is chlorosis, caused by the decrease in chlorophyll biosynthesis. On the other hand, the free iron in excess can cause oxidative stress. Study of the effects of different concentrations of iron in morphological, physiological or biochemical parameters are essential to a better understanding of this nutrient homeostasis in plants. In the present work, plants of sweet potato were submitted under hydroponics system, to different concentrations of ferric-EDTA in nutrient solution: 0.45; 0.9; 4.5 and 9.0 mmol dm-3. Photosynthetic and growth characteristics, nutrient absorption, antioxidant enzymes, stomatal density and diameter, ultra structure of root and leaves cells and histochemical iron in the leaves were evaluated. The toxicity of iron in excess (9.0 mmol dm-3) led to the appearance of brown spots on leaves, often forming necroses, with significant reductions in growth. In these plants, the activity of superoxide dismutase and ascorbate peroxidase increased. Also, the absorption of other micronutrients was affected mainly of the manganese. The iron content in the shoot increased, also qualitatively confirmed by the histochemical test. The light reactions of photosynthesis were not affected, but there was a decrease in stomatal density and net assimilation rate. The ultra structure of root cells reveals the damage of mitochondria in treatments with high concentrations of iron. However, in these plants, the ultra structure of chloroplasts is not affected. / O ferro é um elemento essencial para o crescimento e desenvolvimento das plantas, estando envolvido em processos metabólicos essenciais, como fotossíntese e respiração. Entretanto, a homeostase desse metal é fundamental, pois tanto o excesso quanto a deficiência são prejudiciais. Um dos sintomas característico da deficiência é a clorose, causada pelo decréscimo na biossíntese da clorofila. Por outro lado, o ferro quando livre e em excesso pode gerar estresse oxidativo. Buscar entender os efeitos de diferentes concentrações de ferro, em nível morfológico, fisiológico ou bioquímico, é indispensável para um melhor entendimento da homeostase desse micronutriente nas plantas. No presente trabalho, plantas de batata-doce foram submetidas, sob sistema de hidroponia, a diferentes concentrações de EDTA-férrico em solução nutritiva: 0,45; 0,9; 4,5 e 9,0 mmol dm-3. Foram avaliadas características fotossintéticas e de crescimento, absorção de nutrientes, atividade de enzimas antioxidantes, densidade e tamanhos dos estômatos, ultra-estrutura de células radiciais e de células da folha e histoquímica do ferro nos tecidos foliares. A toxidez por excesso de ferro (9,0 mmol dm-3) levou ao surgimento de manchas marrons nas folhas, muitas vezes formando necroses, com reduções significativas no crescimento. Nestas plantas, a atividade da superóxido dismutase e ascorbato peroxidase aumentou. Também, a absorção dos demais micronutrientes foi afetada, principalmente do Mn. O teor de ferro na parte aérea aumentou significativamente, sendo visualizado pelo teste histoquímico. As reações luminosas da fotossíntese não foram comprometidas, porém houve queda na densidade estomática e na taxa assimilatória líquida. A ultra-estrutura das células radiciais revela o comprometimento das mitocôndrias nos tratamentos com altas concentrações de ferro. Porém, nestas plantas, a ultra-estrutura dos cloroplastos não é afetada.

[pt] A dissertação estuda, primeiramente, a interpelação da psicanálise à fé cristã, conforme o psicanalista e teólogo espanhol Domínguez Morano. É apresentado o conflito gerador da crítica à religião: o ser humano objetiva a religião, no intuito de aplacar a angústia da culpa ou de satisfazer sua necessidade de consolo e proteção. O resultado é a idéia do Deus da onipotência infantil. Num segundo momento, e já no campo da reflexão teológica, procura-se identificar em que consiste a relação adulta com o Deus de Jesus de Nazaré, a partir da experiência vivida por Ele. A reflexão está fundamentada no pensamento do mesmo Domínguez Morano, enriquecido com a contribuição de outros teólogos da atualidade que estudam a temática. Finalmente, são apresentadas algumas pistas, a serviço da vida cristã e da pastoral, com a intenção de colaborar na superação do egocentrismo religioso e na vivência da abertura ao Deus desvelado por Jesus. / [en] The text discusses, firstly, the claim of psychoanalysis unto the Christian faith, as per the Spanish psychoanalyst and theologist Domínguez Morano. The generating conflict of the criticism of religion is presented: the human being clings to religion aiming to ease the anguish from guilt or to fill the need for protection and solace. The result is the God of childish omnipotence. Secondly, already within the field of theological reflexion, the attempt is to identify the actual meaning of the adult relationship with the God of Jesus of Nazareth, as from the experience lived by Him. The reflexion is based upon the thoughts of the same Domínguez Morano, enlightened by the contribution of other contemporary theologists who study the subject. Lastly, a few clues are presented to the service of the Christian life and of the pastoral, with the objective of overcoming the religious egotism and in the actual living of the individual opening to the God by Jesus revealed.

Memoria (licenciado en ciencias jurídicas y sociales) / En el presente trabajo ofreceremos una descripción sistemática de los resultados de esta labor jurisprudencial. Previamente, y para situarnos en el momento en que se hicieron necesarias estas disquisiciones romanas en torno al error, la fuerza y al dolo, comenzaremos con una relación de los orígenes de la compraventa como contrato consensual y de buena fe. Luego revisaremos el tratamiento otorgado al error y al dolo enfatizando que soluciones se aplicaban en caso de presentarse en en contrato de compraventa. Hacia el final de este trabajo analizaremos el tratamiento jurídico que dieron los romanos al miedo en la compraventa, tratamiento que, a diferencia del derecho moderno, no consideró a esta anomalía propiamente como un atentado a la libertad de contratar, y en consecuencia, como un vicio del consentimiento

Because of an eventual ban of creosote-impregnated products, alternative materials for poles used in the electrical grid are needed. Concrete is one alternative and spun concrete poles have been manufactured for the Swedish grid before. These poles are still in use since the high strength and good functioning. However, they weigh too much in terms of the way that poles are assembled on the grid today. Therefore, a study comparing the capacity of different geometries, resulting in lower weight, is of interest.  In this Master’s Thesis, crack initiation and compressive failure in concrete poles are examined by creating FE-models in the software BRIGADE/Plus, using concrete damage plasticity. Thus, guidance is provided about how thin the concrete walls can be made without risking failure – which also means how low the weight of such a pole can be. The failure most likely to occur is a compressive failure in the concrete with a ductile behavior. The result shows that a geometry change, which implies a thinner concrete wall, is possible. This means a weight reduction between 30-75 % or even more, depending on which network the poles are designed for.

Carbon-fibre reinforced polymer (CFRP) laminates are widely used in various engineering applications, such as in race cars and aircrafts, because they are light, stiff and strong. They commonly contain stress raisers in the form of holes and notches (for mechanical joining methods, routing of pipes and cables etc.) and are also often subjected to complex combined multi-axial stress conditions during service. Yet their notched multi-axial fracture behaviour remains largely unexplored. This is the main contribution of the thesis. First, a novel loading fixture for applying a wide range of in-plane loading modes is developed based on the popular Arcan’s method. Termed the ‘modified Arcan rig’, it utilises friction gripping to transfer loads into tabbed specimens. This loading fixture is used to test centre-notched multi-directional CFRP laminates under different combinations of tension and shear stresses. Together with penetrant-enhanced X-ray CT and laminate de-ply, the fracture behaviour of quasi-isotropic CFRP specimens is investigated for the following loading modes: pure tension, pure compression, in-plane shear, and combined tension and shear. Two notch geometries (sharp notch and circular hole) are investigated to allow for an assessment of the role of stress concentration upon strength and damage development to be performed. Three distinct fracture modes are observed in a tensile/compressive-shear stress space (termed Mechanism A, Mechanism B and Mechanism C). It is observed that quasi-isotropic specimens with a central sharp notch are consistently stronger than equivalent specimens with a central circular hole (for all stress states investigated). An underlying micromechanical explanation concerning the effects of damage upon strength is proposed. Second, a finite element (FE) model is developed using the commercial FE program, Abaqus FEA to simulate the observed progressive damage and failure in the quasi-isotropic specimens. The FE model employs independent material property data as inputs. Overall, good correlation between the simulations and the experiments is obtained, validating the FE strategy. The capabilities of the model are extended to predict the notched fracture behaviour of the specimens under combined compression and shear loading, for which experimental work has not been done by the author, but for which literature data exists. Finally, the effect of laminate lay-up upon the notched multi-axial fracture behaviour of the CFRP specimens is explored by considering a 0° ply-dominated lay-up, a ±45° ply-dominated lay-up and a cross-ply lay-up, alongside the quasi-isotropic lay-up. Experiments reveal that all lay-ups exhibit Mechanisms A, B and C. However, the extent of damage in each Mechanism as well as the regime in which each Mechanism operates in (in the failure envelopes) strongly depend on the lay-up of the specimen. As expected, the tensile strengths and compressive strengths increase with the proportion of 0° plies. Surprisingly, the shear strengths do not scale with the proportion of ±45° plies; the specimen geometry and material orthotropy are attributed as reasons for this. In contrast to the case of the quasi-isotropic lay-up, the extent of subcritical damage induced by the circular hole is not always lower than that induced by the sharp notch for the other lay-ups. The difference in the extent of damage between both notch geometries is reflected in the notched strengths of the lay-up in question. These experimental observations are adequately predicted by the FE strategy, which further validates it as a reliable predictive tool for composite fracture.

No description available.

Dans le cadre de cette thèse, nous nous sommes intéressés à la caractérisation des mécanismes de déformation et de leurs interactions pour un zinc polycristallin pur, sous les conditions de chargement complexe et local qui caractérisent l'essai de nanoindentation. En effet, l'interaction des différents mécanismes mis en jeu a généralement été étudiée sur la base de sollicitations dites simples, telles que les essais de traction uniaxiale, biaxiale… Sous l'action d'un chargement uniforme, la prépondérance d'un système particulier sera conditionnée par l'orientation du cristal et par le sens du chargement par rapport à l'axe sénaire. La situation peut être rendue plus complexe dans le cas d'un chargement non simple, comme c'est le cas de l'essai d'indentation. Nous avons réalisé des essais de nanoindentation sur des grains de différentes orientations cristallographiques (mesurées par EBSD), et les résultats obtenus en termes de courbes "charge-profondeur de pénétration" et topographie des empreintes résiduelles ont été analysés. La complexité de l'état de contrainte qui se développe dans le matériau dépend des caractéristiques géométriques de l'indenteur et des orientations cristallographiques en présence, ce qui peut donner lieu à diverses interactions entre les modes de déformation. Ces interactions impacteront directement l'écoulement plastique local du matériau, et par voie de conséquence les propriétés mécaniques macroscopiques du matériau. En adoptant une loi de comportement en plasticité cristalline, nous avons ensuite procédé à la détermination des cissions résolues critiques et des paramètres d'écrouissage pour les différents mécanismes observés. Cette détermination s'est basée sur la résolution d'un problème inverse, au cours duquel nous avons couplé la simulation numérique 3D de l'essai de nanoindentation à l'identification des paramètres de la loi de comportement au moyen d'algorithmes génétiques. La confrontation des résultats expérimentaux et numériques en termes de courbes "charge-profondeur de pénétration" et profils de déformation montrent la bonne adéquation entre les données expérimentales et le modèle identifié. Les résultats obtenus ont ainsi permis de caractériser les mécanismes de déformation observés, et de proposer des perspectives à ce travail. / Within the scope of this thesis, we focused on the characterization of deformation mechanisms and their interactions for pure polycrystalline zinc under complex and local loading conditions such that those involved in a nanoindentation test. Indeed, the interaction between the different mechanisms involved has generally been studied on the basis of so-called simple tests, such as uniaxial or biaxial tensile tests ... Given uniform loading conditions, the predominance of a given deformation system depends on the crystal orientation and the loading direction relative to the crystal c-axis. The situation may be further complicated in case of a complex stress state, as it is the case of the indentation test. We performed nanoindentation tests on grains of different crystallographic orientations (measured by EBSD) and the results (curves "load-penetration depth" and topography of residual imprints) were analyzed. The complexity of the stress state that develops underneath the indenter depends on both the geometrical characteristics of the latter and the crystallographic orientations of the grains, which can give rise to different interactions between the deformation modes. Those interactions will directly affect the local plastic flow, and thus the mechanical properties of the macroscopic material.By using a crystal plasticity model, we have then determined the critical resolved shear stresses and hardening parameters for the observed deformation mechanisms. This determination is based on the solution of an inverse problem, in which we have coupled 3D numerical simulations of the nanoindentation test to genetic algorithms to solve an optimization problem. Comparison between experimental and numerical results in terms of "load-penetration depth" curves and penetration depth profiles show a good agreement between the experimental data and the identified model. The results enabled to characterize the observed deformation mechanisms, and to provide perspectives to this work.