Mesure de la vitesse de déplacement d'un arc de coupure sur une electrode plane

Dans cet article les auteurs montrent comment ils ont mesuré la vitesse de déplacement sur une surface plane métallique, d'un pied d'arc électrique parcouru par un courant compris entre 500 et 3 000 A. Le dispositif expérimental réalisé permet d'effectuer les mesures nécessaires en temps réel sans perturber le phénomène. Les résultats illustrent le caractère instable du plasma et montrent que le déplacement s'effectue de manière aléatoire

Natural deep eutectic solvents as thermostabilizer for Humicola insolens cutinase

As a new generation of green solvents, deep eutectic solvents (DESs) are considered a promising alternative to current harsh organic solvents and find application in many chemical processing methods such as extraction and synthesis. DESs, normally formed by two or more components via various hydrogen bond interactions, offer high potential as medium for biocatalysis reactions where they can improve efficiency by enhancing substrate solubility and the activity and stability of the enzymes. In the current study, the stabilization of Humicola insolens cutinase (HiC) in natural deep eutectic solvents (NADESs) was assessed. The best hydrogen bond donor among sorbitol, xylitol, erythritol, glycerol and ethylene glycol, and the best acceptor among betaine, choline chloride, choline acetate, choline dihydrogen citrate and tetramethylammonium chloride, were selected, evaluating binding energies and molecular orientations through molecular docking simulations, and finally used to prepare NADES aqueous solutions. The effects of component ratio and NADES concentration on HiC thermostability at 90 degrees C were also investigated. The choline dihydrogen citrate:xylitol, in a 1:1 ratio with a 20 wt% concentration, was selected as the best combination in stabilizing HiC, increasing its half-life three-fold

Étude des grandeurs caractéristiques de la tache cathodique d'un arc électrique

The cathode of an electric arc burning freely in air was studied during a half-wave of a sinusoidal, 50 Hz current. For mean intensities ranging from 500 to 2 000 A, five characteristic parameters for the cathode spot were determined : the mean radius a, the temperature T, the electric field E, the total current density J, and the fraction s of the current density due to electrons. The experimental measurement of the erosion of the cathode together with five simultaneous equations enabled the parameters above to be obtained for copper and silver electrodes. The first part of the results gives mean values. The second part shows the changes occuring in the cathode spot as a function of time for the half-wave of the current.On étudie la cathode d'un arc électrique brulant librement dans l'air pendant une demi-alternance d'un courant sinusoïdal de fréquence 50 Hz. Nous avons déterminé pour des intensités moyennes variant entre 500 et 2 000 A cinq grandeurs physiques caractéristiques de la tache cathodique : le rayon moyen a, la température T, le champ électrique E, la densité totale de courant J et la fonction s de la densité de courant due aux électrons. La mesure expérimentale de l'érosion de la cathode associée à un système de cinq équations a permis d'obtenir ces grandeurs pour des électrodes en cuivre et en argent. La première partie des résultats donne des valeurs moyennes, tandis que la deuxième partie montre l'évolution de la tache cathodique en fonction du temps pour la demi-alternance de courant

Polyaniline coated conducting fabrics : chemical and electrochemical characterization

Polyaniline coated conducting fabrics have been obtained by chemical oxidation of aniline by potassium peroxydisulfate on polyester fabrics. Two different acids have been employed to carry out the synthesis (HCl and H2SO4), obtaining the best results of conductivity with the latter one. The conducting fabrics have been characterized chemically by means of Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), energy dispersive X-Ray (EDX) and X-ray photoelectron spectroscopy (XPS). The morphology of the coatings has been observed by means of scanning electron microscopy (SEM). The conducting properties of the fabrics have been measured by means of electrochemical impedance spectroscopy (EIS). The electrochemical characterization has been carried out by means of cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM). The conducting fabrics have also shown electrochromic properties, changing its color from green yellowish at −1 V to dark green at +2 V. The durability of the coating has been evaluated by means of washing and rubbing fastness tests.Authors thank to the Spanish Ministerio de Ciencia e Innovacion and European Union Funds (FEDER) (contract CTM2010-18842-C02-02) and Universitat Politecnica de Valencia (Primeros Proyectos de Investigacion (PAID-06-10)) for the financial support. J. Molina is grateful to the Conselleria d'Educacio (Generalitat Valenciana) for the FPI fellowship

Ionic association and interactions in aqueous methylsulfate alkyl-imidazolium-based ionic liquids

International audienceSeveral experimental techniques were used to study ionic association and interactions in aqueous [C1C2Im][MeSO4], 1-ethyl-3-methylimidazolium methylsulfate, and [C1C4Im][MeSO4], 1-butyl-3-methylimidazolium methylsulfate. Two transport properties, viscosity and electrical conductivity, were determined for these two binary mixtures. For a better assessment of the ionic association and the perturbation of water into the molecular structure of the ionic liquid, diffusion coefficients of ions and water molecules were obtained by NMR spectroscopy while molecular interactions were probed by IR spectroscopy.The comparison of the two ionic liquids shows that for the shorter alkyl chain the viscosity was lower and the electrical conductivity was higher. While the viscosity of the mixture drops already with small additions of water, the electrical conductivity of the solution is only significantly increased for high water concentrations. A maximum is observed for compositions around xwater = (0.90 to 0.95). The SO3 asymmetric stretching band of the IR spectrum can be used as a probe to observe the evolution of the structure around the anion which was mainly occurring for high concentrations of water. Several experimental techniques show than the main change in the ionic association was only observed for high water contents (water mole fraction > 0.8)

Deep Eutectic Solvent to decrease the cost of CO2 capture processes.

International audienc

Mesure de la vitesse de déplacement d'un arc de coupure sur une electrode plane

In the present work, the authors explain their way of measuring the speed at which the spot of an electric arc moves along a flat metallic surface, when carrying a current from 500 to 3 000 A. The set-up devised enables the necessary measurements to be made in real time without perturbing the process. The results illustrate the unsteady character of plasma and show that the motion occurs randomly.Dans cet article les auteurs montrent comment ils ont mesuré la vitesse de déplacement sur une surface plane métallique, d'un pied d'arc électrique parcouru par un courant compris entre 500 et 3 000 A. Le dispositif expérimental réalisé permet d'effectuer les mesures nécessaires en temps réel sans perturber le phénomène. Les résultats illustrent le caractère instable du plasma et montrent que le déplacement s'effectue de manière aléatoire

Article original SociaBillyQuizz, un jeu pour l'entraînement aux habiletés sociales chez l'enfant et l'adolescent : étude exploratoire The SociaBillyQuizz game: A mediation for social skills training in children and adolescents

Résumé Contexte. -Le SociaBillyQuizz est un jeu thérapeutique élaboré pour servir de médiation à des groupes d'entraînement aux habiletés sociales (GEHS) chez les enfants et adolescents. Il sollicite, de manière ludique, différentes dimensions : l'exposition, les cognitions, la communication, l'imagination et l'expression émotionnelle. Abstract Background. -The SociaBillyQuizz is a therapeutic game designed for social skills training groups with children and adolescents. Using an entertaining method, this media requests several dimensions: exposure, cognition, communication skills, imagination, emotional expression and sign decoding. In this preliminary study, the setting includes two groups of six adolescents, one with social anxiety disorder and the other with Asperger syndrome. Objective. -To evaluate, in an exploratory study, the effects of a therapeutic device involving this game for these two clinically different groups of adolescents. Methods. -During 26 of 1 hour weekly sessions, two adolescents groups participate to a program including the SociaBillyQuizz and cognitive behavioral therapies. The groups are moderated by two therapists. The SociaBillyQuizz is a board game for two to six players; its goal is to collect points by answering instructions from the different thematic cards. There are four thematic cards: action cards (players have to do something), brainstorming cards (players have to use their imagination and demonstrate cognitive flexibility), interview cards (players have to express themselves about what they think or feel) and mystery cards (unexpected instructions). According to the groups' clinical characteristics, * Auteur correspondant. Pourre et al. / Neuropsychiatrie de l'enfance et de l'adolescence 60 (2012) [155][156][157][158][159] some aims are specifically highlighted. In the anxiety disorder group, the cognitive dimension is privileged and in the Asperger syndrome group, we emphasise the pretend, cognitive flexibility and theory of mind. The effects are measured by the Rathus Assertiveness Schedule and the Fear Avoidance Hierarchy (FAH) for the social anxiety disorder group and by the Faux Pas Recognition Test and the Social Responsiveness Scale (parent version) for the Asperger group. Results. -These assessment tools indicate, for both groups, a significant increase of the scores corroborating the observed clinical effects. For eleven of the twelve adolescents, a clinical interview 6 months after the retest shows a continuity of therapeutic benefit. Discussion. -These early results suggest that a social skills training device featuring the SociaBillyQuizz produces clinical improvements in these two groups of adolescents. In future researches, with control group and more complete follow-up, nature and effectiveness of its contribution should be specified. Conclusion. -In this preliminary study, the SociaBillyQuizz appears to be an interesting therapeutic tool that can increase implication, motivation, participation and cohesiveness of the group. It also makes easier the cognitive-behavioural-strategies learning

Using bio-based solvents as CO2 absorbents in refrigeration processes.

International audienc

Elaboration of Bi-based Nanoparticles by reactive magnetron sputtering on Ionic Liquid for photocatalytic applications.

International audienc