Conception de nouveaux composés organiques donnant lieu à l'effet laser

It is shown that the lasing ability of organic compounds is directly related to photophysical properties such as radiative lifetime and fluorescence quantum yield which may be modified by means of substitution effects. On a theoretical basis, we show that the addition of substituants at specific positions on the molecular skeleton improves the lasing ability of molecules. In such a way, it is then possible to design the best compounds for laser action.Une molécule organique peut être modifiée, par exemple en introduisant des substituants, de manière à faire apparaître l'effet laser. L'optimisation par la méthode de la chimie quantique de certaines propriétés, la force oscillatrice de la transition de fluorescence en particulier, permet de prévoir dans une famille de composés, ceux qui sont les plus aptes à donner l'effet laser. Par ailleurs, le fait de ralentir certains mouvements intramoléculaires favorise l'émission de fluorescence qui est à la base de l'effet laser

Constitution des colis : les procédés de conditionnement

AREVA NC, en collaboration avec le CEA, s’investit dans le conditionnement des déchets. En fonction de leur catégorie, ces derniers suivent des filières adaptées. Que ce soit par le bitumage des boues STE2 ou par la vitrification en creuset froid des solutions UMo, les procédés de conditionnement sont en permanente recherche de diminution des volumes et de pérennisation du comportement des colis dans le temps

2D and 3D CFD modelling of a reactive turbulent flow in a double shell supercritical water oxidation reactor

International audienceIn order to design and define appropriate dimensions for a supercritical oxidation reactor, a comparative 2D and 3D simulation of the fluid dynamics and heat transfer during an oxidation process has been performed. The solver used is a commercial code, Fluent 6.2®. The turbulent flow field in the reactor, created by the stirrer, is taken into account with a k-ω model and a swirl imposed to the fluid. In the 3D case the rotation of the stirrer can be modelled using the sliding mesh model and the moving reference frame model. This work allows comparing 2D and 3D velocity and heat transfer calculations. The predicted values (mainly species concentrations and temperature profiles) are of the same order in both cases. The reactivity of the system is taken into account with a classical Eddy Dissipation Concept combustion model. Comparisons with experimental temperature measurements validate the ability of the CFD modelling to simulate the supercritical water oxidation reactive medium. Results indicate that the flow can be considered as plug flow-like and that heat transfer is strongly enhanced by the stirring

REACTIVE SCATTERING USING PULSED CROSSED SUPERSONIC MOLECULAR-BEAMS - EXAMPLE OF THE C+NO-]CN+O AND C+N2O-]CN+NO REACTIONS

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1ST EXPERIMENT OF ATOMIC CARBON REACTIVE COLLISIONS IN PULSED SUPERSONIC MOLECULAR-BEAMS

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1ST EXPERIMENT OF ATOMIC CARBON REACTIVE COLLISIONS IN PULSED SUPERSONIC MOLECULAR-BEAMS

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1ST EXPERIMENT OF ATOMIC CARBON REACTIVE COLLISIONS IN PULSED SUPERSONIC MOLECULAR-BEAMS

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Group A particle fluidization in supercritical carbon dioxide: Effect of operating conditions on fluidization efficiency

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