Application of electron tomography of dislocations in beam-sensitive quartz to the determination of strain components

In this study we apply electron tomography of dislocations to quartz with a view to assess whether the von Mises-Taylor criterion is satisfied or violated in a deformed crystal of quartz. We propose a method to perform electron tomography with few projected images which allows extension of this technique to beam-sensitive materials such as quartz. The 3D characterization of the dislocation microstructure allows the evaluation of contributions to dislocation mobility with no ambiguity. From the geometrical characteristics of the dislocations and their Burgers vectors, we show how to identify the non-zero components of the strain tensor. We show that in the quartz grain investigated, the von-Mises-Taylor criterion is satisfied thanks to the climb of 〈c + a〉 dislocations.The TEM national facility in Lille (France) is supported by the Conseil Regional du Nord-Pas de Calais, the European Regional Development Fund (ERDF), and the Institut National des Sciences de l’Univers (INSU, CNRS). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program under grant agreement 787198 – TimeMan. We thank A.K. Kronenberg and an anonymous reviewer for constructive comments

4D electron tomography of dislocations undergoing electron irradiation

Imaging dislocation microstructures in 3D and monitoring their interactions over time is a major challenge. In this study, we show that enhancing the contrast of dislocation lines prior to reconstruction, allows to optimize an acquisition phase with fewer images and thus to follow the 3D evolution of a microstructure over time. We illustrate this new possibility by studying the first stages of formation of helical dislocations in MgO under electron irradiation. We highlight the role of segment mobility on the initiation of climb and reveal the existence of preferential mixed climb planes

Application of Scanning Precession Electron Diffraction in the Transmission Electron Microscope to the Characterization of Deformation in Wadsleyite and Ringwoodite

International audienceThe mantle transition zone represents an important layer in the interior of the Earth that is characterized by phase transformations of olivine polymorphs. Constraining the rheology difference between wadsleyite and ringwoodite is important in determining the viscosity contrast at a depth of 520 km. In this study, we perform a post-mortem by transmission electron microscopy of a wadsleyite + ringwoodite aggregate, deformed at high-pressure and high-temperature, in a deformation-DIA apparatus. From orientation maps acquired by scanning precession electron diffraction, we calculate local misorientations and misorientation-gradients, which are used as a proxy of plastic strain. We show that at 17.3 GPa, 1700 K, the plastic responses of wadsleyite and ringwoodite are comparable, although recovery by subgrain boundary migration is more easily activated in wadsleyite

UM ESTUDO DE CASO DE SUSTENTABILIDADE APLICADA A CONSTRUÇÃO CIVIL CONFORME ETIQUETAGEM DO PROGRAMA PBE EDIFICA

O presente trabalho apresenta a aplicação da Etiqueta Nacional de Conservação de Energia – ENCE em uma edificação comercial localizada na região serrana do Rio de Janeiro. A edificação da nova sede foi projetada e construída, segundo seu proprietário, de forma a atender critérios de sustentabilidade. Na época, no entanto, nenhum método de certificação ambiental para projeto ou construção foi utilizado. Na classificação dessa edificação, foram adotadas as metodologias estabelecidas no Regulamento Técnico da Qualidade para o Nível de Eficiência Energética de Edifícios Comerciais, de Serviços e Públicos, o RTQ-C, do Inmetro. As classificações da ENCE variam de A (mais eficiente) a E (menos eficiente). A classificação final da edificação ficou no nível C, considerando que o empreendimento era tido, na sua concepção, como sustentável

GESTÃO DE DEMANDA DE TRANSPORTES E MOBILIDADE CORPORATIVA

Com o passar dos anos, a mobilidade nas cidades tem se deteriorado progressivamente. Esse fato interfere negativamente na produtividade das empresas, que dependem de seus empregados para executar atividades (direta ou indiretamente) relacionadas à sua atividade fim. Para mitigar esse problema, executa-se a Gestão de Demanda de Transportes, proporcionando o equilíbrio entre Oferta e Demanda de transportes; para tal, as empresas têm desenvolvido Planos de Mobilidade do Empregador (PME), evidenciando o surgimento do segmento denominado Mobilidade Corporativa. Dessa forma, destaca-se a ampla aceitação dos empregados como fator crucial para adoção de um PME, enfatizando o trade-off entre custo e redução de viagens, assim como os benefícios ao Meio Ambiente e à qualidade de vida dos empregados

The influence of clamp usage on clot deposit formation inside thoracic drains

BACKGROUND: A prospective study was done to evaluate the influence of clamp usage on clot formation inside thoracic drains. METHODS: Each drain was weighed soon after removal; they were then washed, dried and weighed again. The difference between the first and second weights was taken as the amount of clot deposit formed. RESULTS: We found more clots accumulated inside the drains that were temporarily obstructed by the clamp. CONCLUSION: In this study, there were more clots formation inside thoracic drains clamped, even if they were occluded intermittently. This can lead thoracic drains to function improperly. The discussion about the correct usage of thoracic drains must be a subject for educational programs for physicians and nurses, to aim for the safest use of this widely used and highly efficient system.OBJETIVO: Conduziu-se este estudo prospectivo a fim de avaliar-se a influência do uso da braçadeira sobre o acúmulo de coágulos dentro dos drenos pleurais. MÉTODO: Os drenos pleurais foram pesados logo após sua retirada, lavados e secados e pesados novamente. A diferença entre a primeira e a segunda pesagem foi admitida como a quantidade de coágulos acumulada. RESULTADOS: Houve maior acúmulo de coágulo nos drenos temporariamente obstruídos por braçadeira em relação àqueles não obstruídos. CONCLUSÃO: Notou-se, neste estudo, maior acúmulo de coágulo dentro de drenos pleurais obstruídos, mesmo que intermitentemente, o que pode levar ao mau funcionamento de todo o sistema de drenagem. A discussão sobre o correto uso dos drenos pleurais deve ser constante e fazer parte de programas de educação continuada para médicos e enfermagem, a fim de que este sistema, amplamente utilizado e altamente eficiente, seja otimizado.798

Idiopathic Bilateral Diaphragmatic Paresis.

We report the case of a patient with severe dyspnea upon reclining. Lung disease, neuromuscular disorders and heart disease were ruled out. However, during the course of the investigation, bilateral diaphragmatic paresis was discovered. A key sign leading to the diagnosis was evidence of paradoxical respiration in the dorsal decubitus position. When the patient was moved from the orthostatic position to the dorsal decubitus position, oxygenation and forced vital capacity worsened. The orthostatic fluoroscopy was normal. Maximal inspiratory pressure was severely reduced. The responses to transcutaneous electric stimulation of the diaphragm were normal. However, electric stimulation of the phrenic nerve produced no response, leading to the diagnosis of bilateral diaphragmatic paresis.32481-

Dislocation electron tomography: A technique to characterize the dislocation microstructure evolution in zirconium alloys under irradiation

International audienceDiffraction-contrast electron tomography was used to analyse the 3D geometry of the dislocation microstructure in a zirconium alloy before and after ion irradiation. The material had been strained at room temperature prior to irradiation. After straining, the material exhibited mainly screw dislocations with Burgers vectors. From the analysis of the habit plane of dislocations with non-screw segments, it was deduced that they have glided mainly in the prismatic planes and to a lesser extent in the first order pyramidal planes. After irradiation, dislocation loops with Burgers vectors were observed. It was shown that the loops are not pure edge and have their habit plane located around the planes {10-10}, tilted up to 20° towards the planes (0001) and {11-20}. Furthermore, it was proven that the initial screw dislocations have climbed under irradiation. Several dislocations were also found to have interacted with loops during climb. The climb of dislocations under irradiation is an important mechanism that can explain part of the in-reactor deformation of zirconium alloys when subjected to simultaneous mechanical loading and irradiation. Interactions between dislocations and loops occurring during dislocation climb may also play a significant role on the in-reactor deformation of zirconium alloys

Transmission electron microscopy characterization of the dislocations and slip systems of the dense hydrous magnesium silicate superhydrous B

International audienceSuperhydrous B (shy B), is a dense hydrous magnesium silicate (DHMS) which exhibits a large stability field in cold slab conditions. It was deformed at 20GPa and at temperatures 1000-1100°C. The resulting dislocations have been characterized by transmission electron microscopy (TEM) with the weak beam dark field (WBDF) and the large angle convergent beam electron diffraction (LACBED) techniques. We emphasize the role of 010 plane in the plasticity of phase Shy B. We report that 100 and 001 glide in 010 , and also climb of 100. We also observe 101 glide in 010 and 111 planes under high stress conditions

Characterization of dislocation interactions in olivine using electron tomography

International audienceWe have investigated by electron tomography, in a transmission electronic microscope, the interactions between dislocations in olivine single crystals and polycrystals deformed in axial compression at T < 1000 °C (T < 0.5Tm). Dislocations are mostly of the [0 0 1] type, except in the polycrystal where [1 0 0] and [0 0 1] dislocations have been activated. A few 〈1 0 1〉 junctions have been found and characterized. Many collinear interactions have been identified either involving direct interactions between crossing dislocations of opposite Burgers vectors or indirect interactions between dislocations gliding in parallel planes and sessile dislocation loops. We suggest that collinear interaction, already identified as the primary source of strain hardening in FCC metals, is the main dislocation interaction mechanism in olivine deformed at temperatures below 1000 °C