Non-Equilibrium Ionic Liquid-Electrode Interface at Elevated Temperature and Its Influence on Co2+Reduction Process

Electrodeposition in Ionic Liquid (IL) media is still at its infancy stage. Recently much attention is devoted to exploration of the IL-electrode interface for better understanding of the electrochemical processes at the electrified surfaces. Herein, we provide a new perspective of the temperature-driven IL-substrate interface structuring. We observed an increase in Co2+ reduction kinetics induced by applying a high temperature gradient. In contrast, keeping the cell at a high constant temperature (100°C) leads to slower Co2+ reduction kinetics, it results in a shift of the reduction onset and evolution of the cyclic voltammogram shape with time. We could ascribe these phenomena to the disturbance of the electrochemical double layer (induced by heating) and its further slow reorganization at constant temperature. We showed that such non-equilibrium behavior can be beneficial for the synthesis of metallic thin films from ILs. Electrochemical quartz crystal microgravimetry, impedance spectroscopy, cyclic voltammetry and chronoamperometry were employed within this work

Electrochemical Method for Direct Deposition of Nanometric Bismuth and Its Electrochemical Properties vs Li

We report that nanometric bismuth can directly be electrodeposited at room temperature without the use of a nanoporous template. The morphology, microstructure, and purity of the as-prepared electrodeposits were characterized by scanning electron microscopy, transmission electron microscopy, and infrared spectroscopy. Typically, well-crystallized nanometer-sized particles of Bi ranging from 10 to 20 nm are obtained. The key to success of such a process lies in the electrochemical coreduction of pyrocatechol violet during the bismuth deposition, which disturbs the electrocrystallization process. As a first possible application, we show that Bi/Cu nanoarchitectured electrodes exhibit interesting rate capabilities when used as electrode material vs Li

Importance of the double layer structure in the electrochemical deposition of Co from soluble Co2+ - based precursors in Ionic Liquid media

Electrodeposition in Ionic Liquid (IL) media is being widely used to obtain different metals, alloys and more recently binary compounds. However, the understanding of this process is still slim due to poor knowledge in the chemistry of ILs and also the complex structure of the double layer at the electrode surface. It is then difficult to predict deposition conditions when trying to synthesize a desired deposit. In this work, we provide insight into the processes taking place at the electrode by detailed studies of Co2+ reduction in ionic liquid media at elevated temperature, which have revealed an unusual Cyclic Voltammetry profile. A drastic drop in the reaction rate was observed, together with a well-shaped reduction peak during the oxidation sweep. Using Electrochemical Quartz Crystal Microbalance, Impedance Spectroscopy measurements and varying bath parameters, we ascribed those phenomena to the reconstruction of the double layer structure upon imposed polarization. Similar behaviors were observed for other systems (Mn2+, Ni2+, Zn2+). Finally, this work provides new insight into the electrochemical processes in ILs. We anticipate that it will also result in significant improvement in preparing metal and other deposits in the ionic liquid media

3D lithium ion batteries—from fundamentals to fabrication

3D microbatteries are proposed as a step change in the energy and power per footprint of surface mountable rechargeable batteries for microelectromechanical systems (MEMS) and other small electronic devices. Within a battery electrode, a 3D nanoarchitecture gives mesoporosity, increasing power by reducing the length of the diffusion path; in the separator region it can form the basis of a robust but porous solid, isolating the electrodes and immobilising an otherwise fluid electrolyte. 3D microarchitecture of the whole cell allows fabrication of interdigitated or interpenetrating networks that minimise the ionic path length between the electrodes in a thick cell. This article outlines the design principles for 3D microbatteries and estimates the geometrical and physical requirements of the materials. It then gives selected examples of recent progress in the techniques available for fabrication of 3D battery structures by successive deposition of electrodes, electrolytes and current collectors onto microstructured substrates by self-assembly methods

Spectral method for the time-dependent Gross-Pitaevskii equation with a harmonic trap

We study the numerical resolution of the time-dependent Gross-Pitaevskii equation, a non-linear Schroedinger equation used to simulate the dynamics of Bose-Einstein condensates. Considering condensates trapped in harmonic potentials, we present an efficient algorithm by making use of a spectral Galerkin method, using a basis set of harmonic oscillator functions, and the Gauss-Hermite quadrature. We apply this algorithm to the simulation of condensate breathing and scissors modes.Comment: 23 pages, 5 figure

Valorisation du capital humain dans la banque

Enhancing Human Capital Value in the Banking Industry. Nowadays it is common knowledge to consider that the value of a company’s staff is a key factor of its performance. Even if there is no straightforward indicator of this value, banks are more and more aware of it, even if it is hard to define. Banks address this issue in several ways : firstly, by trying to hire the best talents available on the labour market ; secondly, by trying to keep and make these talents more productive (incentives, training...) and thirdly, by complying with extra financial rating agencies’ criteria. This last point is a rather new stake but is becoming more and more pressing. Classification JEL : G24, J24, J30.Il est généralement admis aujourd’hui que la valeur des individus composant une entreprise est un élément incontournable de sa performance. Bien qu’il n’existe aucune représentation directe de cette valeur, les banques attachent une importance de plus en plus grande à ce concept même si, comme tout le monde, elles ont de grandes difficultés à le cerner. L’action des banques dans ce domaine présente plusieurs aspects. Tout d’abord, elles cherchent par le recrutement à se procurer sur le marché du travail les meilleurs talents. Ensuite, elles cherchent à conserver et à faire fructifier ce capital initial par divers moyens tels que les politiques de rémunération, les incitations diverses, le repérage des plus talentueux, la formation. Enfin, il leur faut désormais satisfaire aux demandes des agences de notation extra financière qui prennent en compte la valorisation du capital humain dans leur notation «socialement responsable » selon des critères globaux largement influencés par la culture anglo-saxonne. Il s’agit là d’un enjeu relativement nouveau mais de plus en plus prégnant. Classification JEL : G24, J24, J30.Guéry Jean-Claude. Valorisation du capital humain dans la banque. In: Revue d'économie financière, n°104, 2011. Les relations capital et industrie - Capital humain et finance. pp. 195-205

Room temperature efficient regeneration of spent LiFePO4 by direct chemical lithiation

International audienceHerein, we report a direct recycling process of the spent LiFePO4 by direct room temperature chemical lithiation. A fine characterization of a recovered LFP cathode from a spent commercial battery demonstrates that the end of life of the battery is mainly due to the lithium loss, while the structure of the LFP cathode material is globally preserved. It is shown here that such a cathode can be efficiently recovered by direct lithiation in solution using LiI in different solvents (acetonitrile, ethanol, cyclohexane, methanol, DMSO and propan-1,2-ol) with optimized experimental parameters. The best electrochemical performance is obtained with ethanol, one of the greenest and cheapest solvents, without any additional heat treatment. More interestingly, the regeneration of LFP can be achieved directly with the material cast onto its aluminum collector, which paves the way to more efficient recycling preserving the whole electrode formulation and avoiding a new electrode casting. The chemically lithiated LFP cathode in ethanol exhibits a full reversible capacity of ∼168 mAh/g vs. Li metal with a stable coulombic efficiency exceeding 98% for 25 cycles. In addition, this recovery process produces regenerated electrodes showing good electrochemical performance also at high current density

The TLR-mediated response of plasmacytoid dendritic cells is positively regulated by estradiol in vivo through cell-intrinsic estrogen receptor α signaling.

International audiencePlasmacytoid dendritic cells (pDCs) produce large amounts of type I interferons (IFN-α/β) in response to viral or endogenous nucleic acids through activation of their endosomal Toll-like receptors (TLR-7 and TLR-9). Enhanced TLR-7-mediated IFN-α production by pDCs in women, compared with men, has been reported, but whether sex hormones, such as estrogens, are involved in this sex-based difference is unknown. Here we show, in humanized mice, that the TLR-7-mediated response of human pDCs is increased in female host mice relative to male. In a clinical trial, we establish that treatment of postmenopausal women with 17β-estradiol markedly enhances TLR-7- and TLR-9-dependent production of IFN-α by pDCs stimulated by synthetic ligands or by nucleic acid-containing immune complexes. In mice, we found exogenous and endogenous estrogens to promote the TLR-mediated cytokine secretion by pDCs through hematopoietic expression of estrogen receptor (ER) α. Genetic ablation of ERα gene in the DC lineage abrogated the enhancing effect of 17β-estradiol on their TLR-mediated production of IFN-α, showing that estrogens directly target pDCs in vivo. Our results uncover a previously unappreciated role for estrogens in regulating the innate functions of pDCs, which may account for sex-based differences in autoimmune and infectious diseases