Les perspectives énergétiques françaises

L'auteur présente les perspectives énergétiques mondiales et les orientations générales de la politique énergétique française. Il décrit ensuite l'évolution possible du bilan énergétique de la France à l'horizon 1990-2000 compte tenu des politiques engagées dans le domaine des économies d'énergie et des différentes sources d'approvisionnement énergétique

Etude des phénomènes précoces responsables des lésions d'ischémie reperfusion en transplantation rénale (évaluation dans un modèle d'autotransplantation chez le porc)

POITIERS-BU Médecine pharmacie (861942103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Les matériaux pour les batteries Li-Ion : faut-il s’inquiéter ?

International audienceLa très forte croissance attendue du marché de la mobilité électrique va entraîner la fabrication à très grande échelle de batteries au lithium. Des interrogations se manifestent quant à la disponibilité de certains matériaux utilisés pour leur fabrication. Certaines études relaient régulièrement des interrogations mettant en cause la viabilité de ce développement : le cobalt, le nickel ou le lithium, et même le cuivre utilisé pour les moteurs, ne seraient pas disponibles en quantités suffisantes pour alimenter la demande. Qu’en est-il en réalité et, si tensions il doit y avoir, comment y faire face

High magnetic field generated by MgB2 bulk prepared by Spark Plasma Sintering

OralInternational audienceTheoretically, MgB2 bulk samples have very low density of 2.64 g/cm3, compared to REBaCuO samples which are around 6.36 g/cm3, and NdFeB permanent magnets at around 7.60 g/cm3. Practically, this ratio higher than 2-3 is maintained. From the applications point of view, this advantage must be taken into consideration and, the generation of strong magnetic flux densities using MgB2 should be investigated.In this contribution, we have studied the magnetic properties of samples with 20 mm and 30 mm in diameter and a height of 9.7 mm. These samples were processed by the fast spark plasma sintering machine that is able to produce dense and high quality MgB2 samples.Experiments were carried out both on small pieces of the samples using a SQUID-VSM and on big samples performing trapped field measurements in a Field Cooling process. At temperatures between 10 K to 30 K, the results show a strong dependence of the magnetic behavior of the big samples to the applied magnetic field sweep rate, while nothing particular appeared on the small samples.As the magnetic flux density produced by the MgB2 bulks is directly linked to the potential of the applications, we also report the field produced on the surface of one single MgB2 sample of 20 mm diameter, the field produced inside two MgB2 samples of 20 mm in diameter, and finally, the field produced on the surface of one single 30 mm MgB2 sample at various temperatures. A generation of magnetic flux density up to 4.8 T @ 10 K and 3.9 T @ 20 K inside a set of 2 MgB2 samples of 20 mm was observed. The dependence of the flux jumps on the magnetic field sweep rate observed in big samples will be also investigated in detail

High Magnetic Field Generated by Bulk MgB2 Prepared by Spark Plasma Sintering

The authors would like to thank T. Karwoth and X. Zeng for their help during trapped field measurements at Saarland University.International audienceFrom the applications point of view, the advantage of low density given by MgB2 material must be taken into consideration and, the generation of strong magnetic flux densities using MgB2 should be investigated. In this contribution, we have studied the magnetic properties of samples processed by a fast Spark Plasma Sintering machine that is able to produce dense and high quality MgB2 samples. Experiments were carried out both on small pieces of the samples and on large-sized samples performing trapped field measurements in a Field-Cooling process. For temperatures between 10 K to 30 K, the results show a strong dependence of the magnetic behavior of the large-sized samples to the applied magnetic field sweep rate, while nothing particular appeared on the small samples. As the magnetic flux density produced by MgB2 bulks is directly linked to the potential of the applications, we report the field produced at the surface of one single MgB2 sample of 30 mm diameter and the field produced inside a stack of two MgB2 samples of 20 mm in diameter. A generation of magnetic flux density (magnetic polarization µ0M) up to 4.80 T @ 10 K and 3.92 T @ 20 K inside the stack of the two MgB2 samples was observed under negative supporting field of –1.47 T and –1.95 T, respectively. According to these values, to their very low density and to their ease of manufacturing, MgB2 bulks are promising materials for the applications of superconductors

High Magnetic Field Generated by Bulk MgB2 Prepared by Spark Plasma Sintering

The authors would like to thank T. Karwoth and X. Zeng for their help during trapped field measurements at Saarland University.International audienceFrom the applications point of view, the advantage of low density given by MgB2 material must be taken into consideration and, the generation of strong magnetic flux densities using MgB2 should be investigated. In this contribution, we have studied the magnetic properties of samples processed by a fast Spark Plasma Sintering machine that is able to produce dense and high quality MgB2 samples. Experiments were carried out both on small pieces of the samples and on large-sized samples performing trapped field measurements in a Field-Cooling process. For temperatures between 10 K to 30 K, the results show a strong dependence of the magnetic behavior of the large-sized samples to the applied magnetic field sweep rate, while nothing particular appeared on the small samples. As the magnetic flux density produced by MgB2 bulks is directly linked to the potential of the applications, we report the field produced at the surface of one single MgB2 sample of 30 mm diameter and the field produced inside a stack of two MgB2 samples of 20 mm in diameter. A generation of magnetic flux density (magnetic polarization µ0M) up to 4.80 T @ 10 K and 3.92 T @ 20 K inside the stack of the two MgB2 samples was observed under negative supporting field of –1.47 T and –1.95 T, respectively. According to these values, to their very low density and to their ease of manufacturing, MgB2 bulks are promising materials for the applications of superconductors

High magnetic field generated by MgB2 bulk prepared by Spark Plasma Sintering

OralInternational audienceTheoretically, MgB2 bulk samples have very low density of 2.64 g/cm3, compared to REBaCuO samples which are around 6.36 g/cm3, and NdFeB permanent magnets at around 7.60 g/cm3. Practically, this ratio higher than 2-3 is maintained. From the applications point of view, this advantage must be taken into consideration and, the generation of strong magnetic flux densities using MgB2 should be investigated.In this contribution, we have studied the magnetic properties of samples with 20 mm and 30 mm in diameter and a height of 9.7 mm. These samples were processed by the fast spark plasma sintering machine that is able to produce dense and high quality MgB2 samples.Experiments were carried out both on small pieces of the samples using a SQUID-VSM and on big samples performing trapped field measurements in a Field Cooling process. At temperatures between 10 K to 30 K, the results show a strong dependence of the magnetic behavior of the big samples to the applied magnetic field sweep rate, while nothing particular appeared on the small samples.As the magnetic flux density produced by the MgB2 bulks is directly linked to the potential of the applications, we also report the field produced on the surface of one single MgB2 sample of 20 mm diameter, the field produced inside two MgB2 samples of 20 mm in diameter, and finally, the field produced on the surface of one single 30 mm MgB2 sample at various temperatures. A generation of magnetic flux density up to 4.8 T @ 10 K and 3.9 T @ 20 K inside a set of 2 MgB2 samples of 20 mm was observed. The dependence of the flux jumps on the magnetic field sweep rate observed in big samples will be also investigated in detail

Facile One-Step Synthesis of Polyoxazoline-Coated Iron Oxide Nanoparticles

International audienceHereby, a facile one step synthesis of polyoxazoline coated Superparamagnetic Iron Oxide Nanoparticles is reported. The functionalization efficiency is demonstrated using several complementary techniques including direct High Resolution-Transmission Electron Microscopy observations of the polyoxazoline layer. The hybrid nanoparticles have a spinel Fd-3 m structure, a mean particle size of around 12 nm and a high saturation magnetization of 72 emu/g

Influence of Hypoxic Preservation Temperature on Endothelial Cells and Kidney Integrity

International audienceIschemia-reperfusion (IR) injury is unavoidable during organ transplantation and impacts graft quality. New paradigms areemerging including preservation at higher temperature than “hypothermia” or “cold”: although 4∘Cremainslargelyusedforkidney preservation, recent studies challenged this choice. We and others hypothesized that a higher preservation temperature,closer to physiological regimen, could improve organ quality. For this purpose, we used anin vitromodel of endothelial cellsexposed to hypoxia-reoxygenation sequence (mimicking IR) and anex vivoischemic pig kidneys static storage model.In vitro,19∘C, 27∘C, and 32∘C provided protection against injuries versus 4∘C, by reducing cell death, mitochondrial dysfunction, leukocyteadhesion, and inflammation. However,ex vivo, the benefits of 19∘Cor32∘C were limited, showing similar levels of tissue preservationdamage.Ex vivo4∘C-preserved kidneys displayed a trend towards reduced damage, including apoptosis. Macrophage infiltration,tubulitis, and necrosis were increased in the 19∘Cand32∘Cversus4∘C preserved kidneys. Thus, despite a trend for an advantageof subnormothermia as preservation temperature, ourin vitroandex vivomodels bring different insights in terms of preservationtemperature effect. This study suggests that temperature optimization for kidney preservation will require thorough investigation,combining the use of complementary relevant models and the design of elaborated preservation solution and new technologies