39 research outputs found

    New models for ultrasonic guided wave inspections in CIVA

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    Conference of 52nd Annual Conference of the British Institute of Non-Destructive Testing 2013, BINDT 2013 ; Conference Date: 10 September 2013 Through 12 September 2013; Conference Code:107049International audienceModels for ultrasonic guided wave NDT are developed at CEA LIST and integrated into the CIVA platform. Models already available in CIVA 10 deal with plates and cylindrical guides, possibly multilayered. Mode computation, radiated field from different type of transducers (contact with or without wedge, surrounding or surrounded arrays in pipes) and response of a NDT examination in pulse-echo or pitch-catch configurations for a crack orthogonal to the guide axis are proposed. These models are now extended to deal with guides of arbitrary section with planar extrusion, modes being computed with the Semi-Analytical Finite Element (SAFE) method. A hybrid SAFE-Finite Element method has also been integrated to compute the response of a flaw of arbitrary shape, a weld or a complex junction. These new models as well as their validations are presented and discussed

    New perspectives on iron uptake in eukaryotes

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    © 2018 Sherman, Jovanovic, Stolnik, Baronian, Downard and Rawson. All eukaryotic organisms require iron to function. Malfunctions within iron homeostasis have a range of physiological consequences, and can lead to the development of pathological conditions that can result in an excess of non-transferrin bound iron (NTBI). Despite extensive understanding of iron homeostasis, the links between the "macroscopic" transport of iron across biological barriers (cellular membranes) and the chemistry of redox changes that drive these processes still needs elucidating. This review draws conclusions from the current literature, and describes some of the underlying biophysical and biochemical processes that occur in iron homeostasis. By first taking a broad view of iron uptake within the gut and subsequent delivery to tissues, in addition to describing the transferrin and non-transferrin mediated components of these processes, we provide a base of knowledge from which we further explore NTBI uptake. We provide concise up-to-date information of the transplasma electron transport systems (tPMETSs) involved within NTBI uptake, and highlight how these systems are not only involved within NTBI uptake for detoxification but also may play a role within the reduction of metabolic stress through regeneration of intracellular NAD(P)H/NAD(P)+ levels. Furthermore, we illuminate the thermodynamics that governs iron transport, namely the redox potential cascade and electrochemical behavior of key components of the electron transport systems that facilitate the movement of electrons across the plasma membrane to the extracellular compartment. We also take account of kinetic changes that occur to transport iron into the cell, namely membrane dipole change and their consequent effects within membrane structure that act to facilitate transport of ions
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