The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Sylvain Deville - One of the best experts on this subject based on the ideXlab platform.
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Dynamics of the Freezing Front During the Solidification of a Colloidal Alumina Aqueous Suspension: In Situ X-Ray Radiography, Tomography, and Modeling
Journal of the American Ceramic Society, 2011Co-Authors: Alberto Bareggi, Audrey Lasalle, Eric Maire, Sylvain DevilleAbstract:Ice templating of Colloidal Suspension is gaining interest in material science because it offers the possibility to shape advanced materials, and in particular porous ceramics. Recent investigations on this peculiar process show that a correlation between the morphology of the frozen Suspension and the velocity of the freezing front do exist. The dynamics of the freezing front of a Colloidal Suspension of alumina is investigated in the present study by experimental tests, finite element numerical analysis and theoretical analytical calculations. The experimental tests are carried out by in situ X-ray radiography (investigation of the dynamics of the freezing front) and tomography (investigation of the resulting morphology of the frozen Suspension). The finite element model is a continuous properties model; it is used for investigating the dynamics and the shape of the freezing front. The analytical model is based on the two-phase Stefan problem. We propose a solution for the dynamics of the solidification front based on the calculation of the diffusivity as a function of the particle fraction and local temperature.
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Dynamics of the Freezing Front During the Solidification of a Colloidal Alumina Aqueous Suspension: In Situ X-Ray Radiography, Tomography, and Modeling
Journal of the American Ceramic Society, 2011Co-Authors: Alberto Bareggi, Audrey Lasalle, Eric Maire, Sylvain DevilleAbstract:Ice templating of Colloidal Suspension is gaining interest in material science because it offers the possibility to shape advanced materials, in particular porous ceramics. Recent investigations on this process show that a correlation between the morphology of the frozen Suspension and the velocity of the freezing front do exist. The dynamics of the freezing front of a Colloidal Suspension of alumina is investigated in this study by experimental tests, finite element analysis, and analytical calculations. The experimental tests are carried out by in situ X-ray radiography (dynamics of the freezing front) and tomography (morphology of the frozen Suspension). The finite element model is a continuous properties model; it is used for investigating the dynamics and the shape of the freezing front. The analytical model is based on the two-phase Stefan problem. We propose a solution for the dynamics of the solidification front based on the calculation of the diffusivity as a function of the particle fraction and local temperature.
Alain Roucoux - One of the best experts on this subject based on the ideXlab platform.
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moving from surfactant stabilized aqueous rhodium 0 Colloidal Suspension to heterogeneous magnetite supported rhodium nanocatalysts synthesis characterization and catalytic performance in hydrogenation reactions
Catalysis Today, 2012Co-Authors: Alain Roucoux, Carlhugo Pelisson, Lucas L R Vono, Claudie Hubert, Audrey Denicourtnowicki, Liane M RossiAbstract:Abstract Wet impregnation of pre-synthesized surfactant-stabilized aqueous rhodium (0) Colloidal Suspension on silica was employed in order to prepare supported Rh0 nanoparticles of well-defined composition, morphology and size. A magnetic core–shell support of silica (Fe3O4@SiO2) was used to increase the handling properties of the obtained nanoheterogeneous catalyst. The nanocomposite catalyst Fe3O4@SiO2-Rh0 NPs was highly active in the solventless hydrogenation of model olefins and aromatic substrates under mild conditions with turnover frequencies up to 143,000 h−1. The catalyst was characterized by various transmission electron microscopy techniques showing well-dispersed rhodium nanoparticles (∼3 nm) mainly located at the periphery of the silica coating. The heterogeneous magnetite-supported nanocatalyst was investigated in the hydrogenation of cyclohexene and compared to the previous surfactant-stabilized aqueous Rh0 Colloidal Suspension and various silica-supported Rh0 nanoparticles. Finally, the composite catalyst could be reused in several runs after magnetic separation.
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nanoheterogeneous catalytic hydrogenation of arenes evaluation of the surfactant stabilized aqueous ruthenium 0 Colloidal Suspension
Advanced Synthesis & Catalysis, 2007Co-Authors: Audrey Nowicki, Virginie Le Boulaire, Alain RoucouxAbstract:The hydrogenation of various aromatic compounds by a surfactant-stabilized aqueous ruthenium(0) Colloidal Suspension was investigated. The nanocatalysts in the size range of 2.5–3.5 nm were synthesized by reducing ruthenium trichloride salt with sodium borohydride and were stabilized by the highly water soluble N,N-dimethyl-N-cetyl-N-(2-hydroxyethyl)ammonium chloride salt according to our classical approach. The efficient catalytic reactions were performed at room temperature and under hydrogen pressure. The effect of the stirring, namely magnetic stir bar or gas projection impeller, was also studied. A comparison with an analogous rhodium nanocatalyst is described.
Alberto Bareggi - One of the best experts on this subject based on the ideXlab platform.
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Dynamics of the Freezing Front During the Solidification of a Colloidal Alumina Aqueous Suspension: In Situ X-Ray Radiography, Tomography, and Modeling
Journal of the American Ceramic Society, 2011Co-Authors: Alberto Bareggi, Audrey Lasalle, Eric Maire, Sylvain DevilleAbstract:Ice templating of Colloidal Suspension is gaining interest in material science because it offers the possibility to shape advanced materials, and in particular porous ceramics. Recent investigations on this peculiar process show that a correlation between the morphology of the frozen Suspension and the velocity of the freezing front do exist. The dynamics of the freezing front of a Colloidal Suspension of alumina is investigated in the present study by experimental tests, finite element numerical analysis and theoretical analytical calculations. The experimental tests are carried out by in situ X-ray radiography (investigation of the dynamics of the freezing front) and tomography (investigation of the resulting morphology of the frozen Suspension). The finite element model is a continuous properties model; it is used for investigating the dynamics and the shape of the freezing front. The analytical model is based on the two-phase Stefan problem. We propose a solution for the dynamics of the solidification front based on the calculation of the diffusivity as a function of the particle fraction and local temperature.
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Dynamics of the Freezing Front During the Solidification of a Colloidal Alumina Aqueous Suspension: In Situ X-Ray Radiography, Tomography, and Modeling
Journal of the American Ceramic Society, 2011Co-Authors: Alberto Bareggi, Audrey Lasalle, Eric Maire, Sylvain DevilleAbstract:Ice templating of Colloidal Suspension is gaining interest in material science because it offers the possibility to shape advanced materials, in particular porous ceramics. Recent investigations on this process show that a correlation between the morphology of the frozen Suspension and the velocity of the freezing front do exist. The dynamics of the freezing front of a Colloidal Suspension of alumina is investigated in this study by experimental tests, finite element analysis, and analytical calculations. The experimental tests are carried out by in situ X-ray radiography (dynamics of the freezing front) and tomography (morphology of the frozen Suspension). The finite element model is a continuous properties model; it is used for investigating the dynamics and the shape of the freezing front. The analytical model is based on the two-phase Stefan problem. We propose a solution for the dynamics of the solidification front based on the calculation of the diffusivity as a function of the particle fraction and local temperature.
Thomas Speck - One of the best experts on this subject based on the ideXlab platform.
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crystallization in a sheared Colloidal Suspension
Journal of Chemical Physics, 2013Co-Authors: Boris Lander, Udo Seifert, Thomas SpeckAbstract:We study numerically the crystallization process in a supersaturated Suspension of repulsive Colloidal particles driven by simple shear flow. The effect of the shear flow on crystallization is two-fold: while it suppresses the initial nucleation, once a large enough critical nucleus has formed its growth is enhanced by the shear flow. Combining both effects implies an optimal strain rate at which the overall crystallization rate has a maximum. To gain insight into the underlying mechanisms, we employ a discrete state model describing the transitions between the local structural configurations around single particles. We observe a time-scale separation between these transitions and the overall progress of the crystallization allowing for an effective Markovian description. By using this model, we demonstrate that the suppression of nucleation is due to the inhibition of a pre-structured liquid.
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mobility and diffusion of a tagged particle in a driven Colloidal Suspension
EPL, 2010Co-Authors: Boris Lander, Udo Seifert, Thomas SpeckAbstract:We study numerically the influence of density and strain rate on the diffusion and mobility of a single tagged particle in a sheared Colloidal Suspension. We determine independently the time-dependent velocity autocorrelation functions and, through a novel method, the response functions with respect to a small force. While both the diffusion coefficient and the mobility depend on the strain rate the latter exhibits a rather weak dependency. Somewhat surprisingly, we find that the initial decay of response and correlation functions coincide, allowing for an interpretation in terms of an "effective temperature". Such a phenomenological effective temperature recovers the Einstein relation in nonequilibrium. We show that our data is well described by two expansions to lowest order in the strain rate.
Eric Maire - One of the best experts on this subject based on the ideXlab platform.
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Dynamics of the Freezing Front During the Solidification of a Colloidal Alumina Aqueous Suspension: In Situ X-Ray Radiography, Tomography, and Modeling
Journal of the American Ceramic Society, 2011Co-Authors: Alberto Bareggi, Audrey Lasalle, Eric Maire, Sylvain DevilleAbstract:Ice templating of Colloidal Suspension is gaining interest in material science because it offers the possibility to shape advanced materials, and in particular porous ceramics. Recent investigations on this peculiar process show that a correlation between the morphology of the frozen Suspension and the velocity of the freezing front do exist. The dynamics of the freezing front of a Colloidal Suspension of alumina is investigated in the present study by experimental tests, finite element numerical analysis and theoretical analytical calculations. The experimental tests are carried out by in situ X-ray radiography (investigation of the dynamics of the freezing front) and tomography (investigation of the resulting morphology of the frozen Suspension). The finite element model is a continuous properties model; it is used for investigating the dynamics and the shape of the freezing front. The analytical model is based on the two-phase Stefan problem. We propose a solution for the dynamics of the solidification front based on the calculation of the diffusivity as a function of the particle fraction and local temperature.
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Dynamics of the Freezing Front During the Solidification of a Colloidal Alumina Aqueous Suspension: In Situ X-Ray Radiography, Tomography, and Modeling
Journal of the American Ceramic Society, 2011Co-Authors: Alberto Bareggi, Audrey Lasalle, Eric Maire, Sylvain DevilleAbstract:Ice templating of Colloidal Suspension is gaining interest in material science because it offers the possibility to shape advanced materials, in particular porous ceramics. Recent investigations on this process show that a correlation between the morphology of the frozen Suspension and the velocity of the freezing front do exist. The dynamics of the freezing front of a Colloidal Suspension of alumina is investigated in this study by experimental tests, finite element analysis, and analytical calculations. The experimental tests are carried out by in situ X-ray radiography (dynamics of the freezing front) and tomography (morphology of the frozen Suspension). The finite element model is a continuous properties model; it is used for investigating the dynamics and the shape of the freezing front. The analytical model is based on the two-phase Stefan problem. We propose a solution for the dynamics of the solidification front based on the calculation of the diffusivity as a function of the particle fraction and local temperature.