COMPUTATION OF 3D INDUCTION HARDENING PROBLEMS BY COMBINED FINITE AND BOUNDARY-ELEMENT METHODS

International audienceA method for the solution of high frequency three dimensional coupled magneto-thermal problems such as those of the induction hardening of steel is proposed. The magnetic problem is treated first using the Boundary Element Method (BEM) to calculate magnetic parameters. From eddy-currents and Joule effects, source values are obtained to solve the thermal problem by the Finite Element Method (FEM). The two problems are then indirectly coupled to obtain a solution for the entire problem

Etude de la représentivité d'un essai de vieillissement accéléré par un calcul de champs tridimensionnel

National audienceL'essai de vieillissement accéléré est utilisé par EDF pour qualifier les isolateurs composite utilisés sur son réseau. Cette communication justifie, grâce à des caiculs de champs, l'emploi d'une maquette MT pour la qualification d'isolateur HT au cours de cet essai. Elle montre toutefois que pour la qualification d'appareils, à enveloppe synthétique, dotés de parties internes actives, l'utilisation d'une maquette est plus difficile. De plus, la modélisation de la couche de pollution présente à la surface de i'objet en essai pendant certains cycles de l'essai de vieillissement accéléré, est nécessaire pour expliquer certaines des dégradations observées au cours de l'essai. Elle nécessite l'utilisation d'un code de calcul spécifique

A multiplexed cell-free assay in double emulsion droplets

We introduce a novel on-chip assay, performed in water-in-oil-in-water double emulsions, that uses cell-free protein synthesis and artificial liposomes for the screening of membrane disrupting toxin DNA libraries according to their antimicrobial activity and host membrane safety. Our method represents a unique approach to the selection and potentially directed evolution of membrane-disrupting toxins

Surface impedances, BIEM and FEM coupled with 1D non linear solutions to solve 3D high frequency eddy current problems

International audienceThe BIEM coupled with surface impedances gives good results at a low cost for 3D high frequency eddy-currents calculation with linear materials. In this paper, we review the possible extensions to non linear materials. We propose (and test in 3D) an original method, based on 1D computations of the complex surface impedance. Results are applied to induction hardening processes. This paper presents essentially validations of the method of non linear surface impedances; a future publication will be devoted to the thermal validations

Effect of the alkyl linker length on the photoisomerization of hydrazone switches on metal surfaces

A series of bistable hydrazone switches containing alkyl thiolate linkers of various lengths (Cn HAT, n = 3, 8, 10, and 11) were synthesized. We explore the length effect of the carbon chain on the photoisomerization of hydrazone switches using UV-vis spectroscopy and tip-enhanced Raman spectroscopy (TERS). The conversion efficiency (photostationary state, PSS, after irradiation at 415 or 340 nm) of the isomerization of Cn HAT monolayers on Au rises with increasing length of the alkyl chain, with an optimum result for n-octyl (C8) thiolate or longer linkers. The low PSS415 of C3 HAT is attributed to strong quenching by the metal surface, as confirmed by density functional theory (DFT) calculations based on a one-dimensional double-well model. The partial trap of photo-induced hot carriers in the excited states of C3 HAT in the potential well of Au reduces the lifetime of its excited states. Such calculation results provide insight into the detailed mechanism of surface quenching effect. Furthermore, UV-vis results suggest that after irradiation at 415 nm, Cn HATs cannot isomerize when bound to Ag; higher photon energies are necessary in this case. These results validate the previously proposed substratemediated isomerization mechanism

Effect of the alkyl linker length on the photoisomerization of hydrazone switches on metal surfaces

A series of bistable hydrazone switches containing alkyl thiolate linkers of various lengths (Cn HAT, n = 3, 8, 10, and 11) were synthesized. We explore the length effect of the carbon chain on the photoisomerization of hydrazone switches using UV-vis spectroscopy and tip-enhanced Raman spectroscopy (TERS). The conversion efficiency (photostationary state, PSS, after irradiation at 415 or 340 nm) of the isomerization of Cn HAT monolayers on Au rises with increasing length of the alkyl chain, with an optimum result for n-octyl (C8) thiolate or longer linkers. The low PSS415 of C3 HAT is attributed to strong quenching by the metal surface, as confirmed by density functional theory (DFT) calculations based on a one-dimensional double-well model. The partial trap of photo-induced hot carriers in the excited states of C3 HAT in the potential well of Au reduces the lifetime of its excited states. Such calculation results provide insight into the detailed mechanism of surface quenching effect. Furthermore, UV-vis results suggest that after irradiation at 415 nm, Cn HATs cannot isomerize when bound to Ag; higher photon energies are necessary in this case. These results validate the previously proposed substrate-mediated isomerization mechanism