Room-temperature cycling of metal fluoride electrodes: Liquid electrolytes for high-energy fluoride ion cells

Fluoride ion batteries are potential “next-generation” electrochemical storage devices that offer high energy density. At present, such batteries are limited to operation at high temperatures because suitable fluoride ion–conducting electrolytes are known only in the solid state. We report a liquid fluoride ion–conducting electrolyte with high ionic conductivity, wide operating voltage, and robust chemical stability based on dry tetraalkylammonium fluoride salts in ether solvents. Pairing this liquid electrolyte with a copper–lanthanum trifluoride (Cu@LaF_3) core-shell cathode, we demonstrate reversible fluorination and defluorination reactions in a fluoride ion electrochemical cell cycled at room temperature. Fluoride ion–mediated electrochemistry offers a pathway toward developing capacities beyond that of lithium ion technology

Discrimination of Radiotoxic and Chemotoxic Effects of Uranium on Mouse Embryo Fibroblasts

Uranium (U) is a natural radioactive heavy metal used in the nuclear industry, in different forms with different isotopic compositions (natural, depleted or enriched in 235U) and solubilities. Uranium internal exposure is a major risk for the nuclear workers. Uranium uptake can occur accidentally after inhalation, ingestion, or absorption through intact or injured skin. Due to these physical and chemical properties, U toxicity results from both chemical and radiological toxicity. The aim of this work was to find biological markers of internal contamination able to discriminate between chemotoxic and radiotoxic effects of U. The study was carried out in vitro on mouse C3H10T1/2 embryo fibroblasts contaminated either with 0.3% depleted uranium in isotope 235U (DU) or with 12% enriched uranium in isotope 235U (EU). In our experimental conditions, EU has a specific activity 20 times higher than DU. Fibroblasts were grown in culture medium containing various concentrations of DU or EU (0µM, 5µM, 50µM, 500µM and 1000µM). Genotoxic effects of both DU and EU were assessed with the cytokinesis-block micronucleus assay in combination with the fluorescent in situ hybridization of centromeric DNA probes. Binucleated cells with one micronucleus (BN-1MN), binucleated cells with centromere-negative micronucleus (BN-MNC-), mononucleated cells with one MN (Mono-1MN) and nucleoplasmic bridges (NPBs) were scored. Moreover ?-H2AX immunostaining was achieved to detect DNA double-strand breaks (DSB). The percentage of BN-1MN increased with both DU and EU concentration. The percentage of BN-MNC- was significantly higher when cells were contaminated with EU compared to DU for all concentrations (for example, 1,2% and 0,4% for a 50µM EU and DU concentration, respectively), this result confirms clastogen effect of EU. The frequency of NPBs increased with the U concentration. However EU induces more NPBs than DU (for example, 1,35% and 0,25% for a 50µM EU or DU concentration, respectively). In addition, the percentage of Mono-1MN is higher after a contamination with EU compared to DU (for example, 5,5% and 4,5% for a 50µM EU and DU concentration, respectively). The percentage of cells with DSB increased with U concentration. As a conclusion, our experiments show that BN-1MN and DSB seem to be a marker of U genotoxicity (chemical + radiological). The BN-MNC-, NPBs, and to a lesser extent Mono-1MN seem to be a marker of a radiotoxic effect. A microdosimetric calculation is in process and will consolidate these results

Caractérisation des cellules solaires silicium (n)-In2O3 (dope Sn) préparées par une méthode de vaporisation

International audienc

Polynorbornene-polyethylene glycol based polymers as electrolyte materials for rechargeable lithium batteries

Polymer electrolytes are a promising alternate to flammable liq. polymer electrolytes. Their use in lithium based rechargeable batteries is limited by low ion cond. (< 10-5 S/cm) and mech. stability. There has been considerable effort to develop dry solid polymer electrolyte materials with higher conductivities (10-4 S/cm) at room temps. Achieving both high cond. and mech. stability in a polymer is challenging. Towards that goal we have synthesized polynorbornene-polyethylene glycol based copolymers. Cond. and mech. properties of these materials were explored towards their use in lithum rechargeable batteries

Identifying contagion

Identifying contagion effects during periods of financial crisis is known to be complicatedby the changing volatility of asset returns during periods of stress. Tountangle this we propose a GARCH (generalized autoregressive conditional heteroskedasticity)common features approach, where systemic risk emerges from acommon factor source (or indeed multiple factor sources) with contagion evidentthrough possible changes in the factor loadings relating to the common factor(s).Within a portfolio mimicking factor framework this can be identified using momentconditions. We use this framework to identify contagion in three illustrations involvingboth single and multiple factor specifications: to the Asian currency marketsin 1997–1998, to US sectoral equity indices in 2007–2009 and to the CDS (creditdefault swap) market during the European sovereign debt crisis of 2010–2013. Theresults reveal the extent to which contagion effects may be masked by not accountingfor the sources of changed volatility apparent in simple measures such as correlation