Стратегия хирургического лечения местнораспространенных опухолей малого таза с применением эвисцераций. Сообщение1. Синдромы кишечной непроходимости, кровотечения и сдавления мочевых путей

Представлен обзор и анализ методов хирургической коррекции синдромов кишечной непроходимости, кровотечения и сдавления мочевых путей при местнораспространенных опухолях малого таза. Обобщен 10−летний опыт хирургического лечения данной патологии в Институте общей и неотложной хирургии. Приведена классификация основных методов оперативных пособий, направленных на достижение гемостаза и деривации мочи и кала.The methods of surgical correction of syndromes of intestinal obstruction, hemorrhage and urinary tract compression at local tumors of the small pelvis are reviewed and analyzed. The 10−year experience of surgical treatment for this pathology at Institute for General and Urgent Surgery is generalized. Main methods of operative treatment aimed at achievement of hemostasis and urine and feces derivation are presented

Ultrasmall MgH_2 Nanoparticles Embedded in an Ordered Microporous Carbon Exhibiting Rapid Hydrogen Sorption Kinetics

MgH_2 nanoparticles with different average sizes have been prepared as ordered microporous carbon by tuning the Mg amount from 15 to 50 wt %. Ultrasmall particles with mean sizes of 1.3 and 3.0 nm have been obtained for 15 and 25 wt % Mg contents, respectively. The hydrogen desorption properties strongly depend on the nanoparticle size, as evidenced by different thermal analysis techniques. The onset temperature of hydrogen desorption for MgH_2 nanoparticles below 3 nm occurs at a temperature about 245 K lower than for microcrystalline material. Two distinct hydrogen desorption peaks are noticed for nanoparticles with mean sizes of 1.3 and 3.0 nm, as confirmed by TDS and HP-DSC. 1H NMR investigations suggest the presence of two MgH_2 populations with enhanced hydrogen mobility, as compared to the microcrystalline hydride. The short hydrogen diffusion path and the enhanced hydrogen mobility may explain the increased desorption kinetics of these ultrasmall nanoparticles

Réactivité électrochimique des hydrures métalliques vis-à-vis du lithium (Electrodes négatives pour batteries Li-ion)

L utilisation d hydrures métalliques est proposée pour la première fois comme électrode négative pour la technologie à ion lithium, couplant l avantage des hautes capacités massiques et volumétriques des hydrures avec la haute densité d énergie des batteries à ions lithium. L hydrure de magnésium, avec la plus importante capacité massique (2038 mAh.g-1), un potentiel d équilibre théorique de 0,520 V et un faible coût a été naturellement choisi comme cas d école pour mener des investigations sur ce nouveau type d application des hydrures métalliques. La réaction électrochimique mise en jeu est un mécanisme de conversion : MgH2 + 2 Li+ + 2 e- Mg0 + 2LiH, au cours duquel l hydrure MgH2 réagit avec les ions lithiums pour former en fin de décharge du magnésium métallique dispersé dans une matrice d hydrure de lithium. Partant d un hydrure commercial dont la réactivité électrochimique est très faible différentes étapes de chimie préparatrice du matériau (broyage, broyage avec un carbone Ct,x, préparation solide-gaz suivie du broyage avec du carbone Ct,x) conduisant à la réduction de la taille des particules initiales de l hydrure ont été nécessaires afin d optimiser la capacité réversible qui est passée de 50 mAh.g-1 à 1450 mAh.g-1 pour une perte irréversible de 25% à un potentiel moyen de 0,5 Volt par rapport à Li+/Li0. Cet intérêt pour l hydrure de magnésium est notamment renforcé par la polarisation des courbes potentiel/capacité comprise entre 200 mV-300 mV et qui est de loin la plus faible de tous les systèmes étudiés jusqu à présent dans les réactions de conversion. Egalement très prometteuse, la réactivité de l hydrure de magnésium avec le lithium est démontrée comme étant une nouvelle voie de préparation de nano-métaux et d hydrures aux propriétés accrues pour le stockage de l hydrogène à basse température, température avec notamment une absorption et une désorption complète obtenues à 100C et 200C, pour le magnésium et l hydrure préparés électrochimiquement. Finalement, cette réactivité n est pas spécifique à l hydrure de magnésium et peut être étendue à certains hydrures binaires (NaH, TiH2) et ternaires (Mg2NiH3,7, TiNiH et, LaNi4,25Mn0,75H5), ouvrant ainsi de nouvelles perspectives de préparation de matériaux sur mesures tant pour le stockage gazeux de l hydrogène que pour la technologie Li-ion.The use of metal hydrides as negative electrode for lithium-ion batteries, combining the advantage of high gravimetric and volumetric capacities of hydrides with high energy density of lithium ion batteries, is proposed here for the first time as a promising opportunity to achieve in the coming decades powerful batteries. Magnesium hydride, with the largest gravimetric capacity (2038 mAh.g-1), a theoretical potential equilibrium of 0.520 V and a low cost, was naturally chosen as a candidate to investigate this new type of application of metal hydrides. It reacts with lithium ions according to a conversion mechanism: MgH2 + 2 Li+ + 2 e- Mg0 + 2LiH, where magnesium hydride reacts with lithium ions to form at the end of the discharge, metallic magnesium and lithium hydride. The electrochemical reactivity of commercial magnesium hydride is very low (reversible capacity lower than 50 mAh.g-1). Different preparation methods of the material such as milling, carbon addition, solid-gas preparation followed by milling with carbon were needed to improve the reactivity of commercial magnesium hydride, leading to increase the reversible capacity from 50 mAh.g-1 to 1450 mAh.g-1 (75% of the theoretical capacity 2038 mAh.g-1) for an irreversible loss of 25% with an average potential of 0.5 Volt vs. Li+/Li0. This interest for the magnesium hydride is reinforced by the polarization of the potential/capacity curves ranging between 200 mV-300 mV. The reactivity of magnesium hydride with lithium is shown to be a new way for the preparation of nanometals and nanohydrides for hydrogen storage materials by solid-gas reaction at low temperatures. Finally, this reactivity is not specific to magnesium hydride; it can be extended to some binary hydrides (NaH, TiH2) and different families of intermetallic hydrides (Mg2NiH3,7, TiNiH, LaNi4,25Mn0,75H5) thus opening new routes for preparation of materials in both fields of hydrogen storage and lithium-ion technology.AMIENS-BU Sciences (800212103) / SudocSudocFranceF

Metal hydrides: an innovative and challenging conversion reaction anode for lithium-ion batteries

The state of the art of conversion reactions of metal hydrides (MH) with lithium is presented and discussed in this review with regard to the use of these hydrides as anode materials for lithium-ion batteries. A focus on the gravimetric and volumetric storage capacities for different examples from binary, ternary and complex hydrides is presented, with a comparison between thermodynamic prediction and experimental results. MgH2 constitutes one of the most attractive metal hydrides with a reversible capacity of 1480 mA·h·g−1 at a suitable potential (0.5 V vs Li+/Li0) and the lowest electrode polarization (<0.2 V) for conversion materials. Conversion process reaction mechanisms with lithium are subsequently detailed for MgH2, TiH2, complex hydrides Mg2MHx and other Mg-based hydrides. The reversible conversion reaction mechanism of MgH2, which is lithium-controlled, can be extended to others hydrides as: MHx + xLi+ + xe− in equilibrium with M + xLiH. Other reaction paths—involving solid solutions, metastable distorted phases, and phases with low hydrogen content—were recently reported for TiH2 and Mg2FeH6, Mg2CoH5 and Mg2NiH4. The importance of fundamental aspects to overcome technological difficulties is discussed with a focus on conversion reaction limitations in the case of MgH2. The influence of MgH2 particle size, mechanical grinding, hydrogen sorption cycles, grinding with carbon, reactive milling under hydrogen, and metal and catalyst addition to the MgH2/carbon composite on kinetics improvement and reversibility is presented. Drastic technological improvement in order to the enhance conversion process efficiencies is needed for practical applications. The main goals are minimizing the impact of electrode volume variation during lithium extraction and overcoming the poor electronic conductivity of LiH. To use polymer binders to improve the cycle life of the hydride-based electrode and to synthesize nanoscale composite hydride can be helpful to address these drawbacks. The development of high-capacity hydride anodes should be inspired by the emergent nano-research prospects which share the knowledge of both hydrogen-storage and lithium-anode communities

Experimental Challenges in Studying Hydrogen Absorption in Ultrasmall Metal Nanoparticles

International audienc

Synthesis and stability of Pd–Rh nanoalloys with fully tunable particle size and composition

International audienc

Hydrogen absorption properties of carbon supported Pd–Ni nanoalloys

International audienc

Exploring the hydrogen absorption into Pd–Ir nanoalloys supported on carbon

International audienc

Composition and size dependence of hydrogen interaction with carbon supported bulk-immiscible Pd–Rh nanoalloys

International audienc

Influence of nanosizing on hydrogen electrosorption properties of rhodium based nanoparticles/carbon composites

International audienc