Structural and electrical properties of tellurovanadate glasses containing Li2O

Glassy materials are promising intercalation compounds, due to their open network structure and absence of grain boundaries. Some glasses containing alkali ions and a high concentration of transition metal ions can present mixed ionic-electronic conductivity and are therefore potential candidates for application as cathode material in Li-ion batteries. The present work is devoted to the ternary system xLi(2)O-(1-x)[0.3V(2)O(5)-0.7TeO(2)] with 0 <= x <= 0.4. These compounds were prepared by heat treatment in air at 800 degrees C followed by traditional quenching. Raman spectroscopy and V-51 nuclear magnetic resonance measurements were performed in order to highlight the structural short range order modifications induced by the introduction of the Li2O network modifier. These structural effects can be related to the electrical behaviour, as studied by complex impedance spectroscopy measurements. (c) 2006 Elsevier B.V. All rights reserved

The metrological stakes of the european water framework directive

International audienceWith the new Water Directive the European Union has given a new dimension to environmental monitoring. It is now necessary to follow and account for the ecological and chemical status of aquatic ecosystems. This status should improve with the objective of "good status" in 2015 for all waters of Member States. Such a regulation will lead to an intensification of chemical contaminants control and has important metrological implications. In order to ensure the comparability of data, it appears necessary to develop internationally validated standard methods and to organise intercomparison exercises for analytical laboratories

Impact du prélèvement sur la qualité des données de la surveillance

A collaborative sampling trial was performed by AQUAREF (French national reference laboratory for water and the aquatic environment) at Paladru Lake, Isere, France. This trial was the first national test aiming at improving knowledge of the effect, in lake water, of sampling on global variability. Ten sampling teams regularly involved in Water Framework Directive monitoring of lake water were asked to participate, in agreement with the Regional Water Agencies. All the samples were collected and analyzed by INERIS in order to minimize the analytical impact on global variability. Overall results for a few metals (cobalt and nickel) showed predominance (>90%) of sampling uncertainty compared to analytical variability. For other metals (zinc, lead and aluminium), the initial blank tests showed possible contamination of sampling systems, and really pointed to the importance of blank sampling. Finally, this trial highlighted the need for general guidelines for sampling that could minimize the risk of misclassification of lake-water status.La directive 2000/60/CE vise à atteindre un bon état des masses d’eaux en 2015 pour l’ensemble des milieux aquatiques européens. À l’intérieur de ce cadre réglementaire, la qualité et la maîtrise des données acquises ont une importance capitale, non seulement pour comparer des résultats à des valeurs seuils, mais également pour identifier avec un degré de confiance suffisant les tendances des niveaux des concentrations en polluants. Les notions de comparabilité des données et d’estimation des incertitudes de mesures sont abordées par les laboratoires à travers notamment la participation aux essais d’aptitude analytique. Cependant, de tels essais portant sur les aspects « échantillonnage » sont pour l’instant encore rares. Depuis 2007, le consortium Aquaref s’est focalisé sur l’amélioration et l’harmonisation des pratiques d’échantillonnage. Un essai collaboratif sur l’échantillonnage d’eau en plan d’eau a été organisé en 2010 pour étudier l’impact des opérations de prélèvement sur la qualité des résultats d’analyse. Coordinateur et promoteur de l’étude, l’INERIS a réalisé, en partenariat avec le LNE(1) et l’Inra(2), ces travaux financés par l’Onema(3)

Structural and electrochemical characterization of mesoporous thin films of Nb2xV2-2xO5 upon lithium intercalation

Nb2xV2 - 2xO5 (0 <= x <= 1) powders were prepared by a synthetic route based on the inorganic polymerization of alkoxy-choride precursors and characterized by a combination of X-ray diffraction V-51 and Nb-93 NMR and Raman spectroscopy. Amorphous mesoporous thin films of similar compositions were successfully prepared by a modified Evaporation Induced Self Assembly method using polystyrene-b-polyethyleneoxide diblock copolymer as structuring agent. The electrochemical properties of the mesoporous films upon lithium insertion-deinsertion are investigated by cyclic voltammetry. This study highlights the advantages of such nanoarchitecture in terms of increased capacity to insert lithium. (C) 2009 Elsevier B.V. All rights reserved.Interuniversity Attraction Pole INANOMAT (P6/17

Evaluation of innovative tools for micropollutant research in sewage network

International audienc

Metrological aspects of collaborative field trials, including coping with unexpected events

International audienceWith the support of the French River Basin Agencies (RBAs), and the French Ministry of Ecology and its local offices, the French National Institute for Industrial Environment and Risks organized a collaborative field trial in June 2007 on a minor tributary of the River Seine near Paris. After sampling errors were recognized in the context of ISO 17025 as an important factor affecting the quality of an analytical result, the needs for consistency of data arising from the European Water Framework Directive 2000/60/EC rendered enhancement of metrological knowledge in this step of the measurement chain more significant. This trial was the first national attempt to improve knowledge of the effect in natural river waters of sampling activity undertaken as part of regulatory monitoring. Of the 14 sampling teams that took part in the trial, all selected by the RBAs, three were not linked to an analytical team. The Epone sampling spot was selected because of its central location, because its rural characteristics are representative of the majority of the RBA sampling stations, and because it enabled more than 40 people to be brought together in a secure environment. The monitoring parameters selected were : pH, oxygen, temperature and conductivity (field parameters); and, suspended particulate matter (SPM), nitrites, orthophosphates, barium, di(ethylhexyl) phthalate (DEHP), and one organic halogenated volatile (OHV) substance, tetrachloroethylene (parameters to be analyzed in a laboratory, also called non-field parameters). The aim of this study was to evaluate several sampling procedures, including standardized, to determine the variability induced by sampling operations in subsequent analytical processes. "Sampling activities" included sampling performance and external inputs (e.g., weather). individual field observations were also performed in order to understand the reasons for reference methods not being rigorously followed and to propose improvements that will make these methods more acceptable to sampling staff, and thus more reliable. This article focuses on the results obtained for non-field parameters and on the solutions that we developed to overcome the difficulties caused by a storm the day before the trial