Molecular hydrodynamics from memory kernels

The memory kernel for a tagged particle in a fluid, computed from molecular dynamics simulations, decays algebraically as $t^{-3/2}$. We show how the hydrodynamic Basset-Boussinesq force naturally emerges from this long-time tail and generalize the concept of hydrodynamic added mass. This mass term is negative in the present case of a molecular solute, at odds with incompressible hydrodynamics predictions. We finally discuss the various contributions to the friction, the associated time scales and the cross-over between the molecular and hydrodynamic regimes upon increasing the solute radius.Comment: 5 pages, 4 figure

Formation and characterization of thioglycolic acid–silver cluster complexes

Gas phase reactivity observed in an ion trap was used to produce silver clusters protected with thioglycolic acid. Fragmentation pathways as well as optical properties were explored experimentally and theoretically. Sequential losses of SCH2 and CO2 in the ion trap lead to redox reactions with charge transfers between the metal part and the carboxylate and thiolate groups. This allows us to control the number of electrons in the metallic subunit and thus optical properties of the complexes. The presented formation process can be used as a prototype for tuning optical and chemical properties of ligated metal clusters by varying the number of confined electrons within the metallic subunit

L'identité territoriale serait-elle (vraiment) soluble dans la mobilité ? Des pratiques individuelles de mobilités à la fabrication et la territorialisation de solidarités collectives : positions critiques, propositions théoriques et problématiques

International audienceThe relationship between territories and mobility are analyzed in many ways. The literature review offers different concepts that describes this relationship: motility, travel identity, mobility, culture...However, few explanations are offered for understanding their respective construction. Many approaches deals with a paradigm of causality: the effects of mobility on the territorialities or the effects of territorialities on the mobility. However, it seems necessary to improve the previous analysis in order to define a concept that integrates the different dimensions of the individual as subject, actor and mobile. Our paper will discuss this point, by observing the effects of individual strategies related to mobility in terms of territorial and identity production: which kinds of collectives, which values for place and proximities?La relation entre territoire et mobilité constitue un objet exploré sous de nombreuses formes avec un foisonnement de nouvelles notions pour l'approcher (motilité, identité de déplacement, cultures de la mobilité ...), sans que soit encore levé le verrou de la compréhension de leur construction respective. Nombre des approches restent dans un paradigme de causalité : les effets de la mobilité sur les territoires ou bien les effets de territoire sur la mobilité. Si de nouvelles perspectives sur la territorialité des individus mobiles ont pu ainsi être ouvertes (identité de déplacement notamment), ces approches restent insuffisantes dans la saisie d'une éventuelle hybridation, qui n'opposerait pas deux types de spatialité, ni ne les dissocierait en une mécanique systémique, mais en montrerait l'intégration dans un individu-acteur-mobile. Elles rendent peu compte également des processus de construction stratégique entre l'un et l'autre, telle que l'activation du territoire comme ressource dans la réalisation de la mobilité. Considérant l'action et les stratégies issues de l'organisation et la réalisation de pratiques de mobilité individuelles, la communication discutera alors la production et la valorisation de dimensions fondatrices de territoire : l'hypothèse avancée est celle d'un individu construisant et reconstruisant des relations de proximité dans la réalisation des opportunités offertes par la mobilité, dans un processus générateur d'identification territoriale

Ag31(SG)19 and Ag15(SG)11

We report a simple synthesis of silver:glutathione (Ag:SG) clusters using a cyclic reduction under oxidative conditions. Two syntheses are described which lead to solutions containing well-defined Ag31(SG)19 and Ag15(SG)11 clusters that have been characterized by mass spectrometry. The optical properties of silver:glutathione (Ag:SG) cluster solutions have been investigated experimentally. In particular, the solution containing Ag15(SG)11 clusters shows a bright and photostable emission. For Ag31(SG)19 and Ag15(SG)11 clusters, the comparison of experimental findings with DFT and TDDFT calculations allowed us to reveal the structural and electronic properties of such low nuclearity liganded silver clusters

Ag31(SG)19 and Ag15(SG)11

We report a simple synthesis of silver:glutathione (Ag:SG) clusters using a cyclic reduction under oxidative conditions. Two syntheses are described which lead to solutions containing well-defined Ag31(SG)19 and Ag15(SG)11 clusters that have been characterized by mass spectrometry. The optical properties of silver:glutathione (Ag:SG) cluster solutions have been investigated experimentally. In particular, the solution containing Ag15(SG)11 clusters shows a bright and photostable emission. For Ag31(SG)19 and Ag15(SG)11 clusters, the comparison of experimental findings with DFT and TDDFT calculations allowed us to reveal the structural and electronic properties of such low nuclearity liganded silver clusters

Outdoor thermal monitoring of large scale structures by infrared thermography integrated in an ICT based architecture

International audienceAn infrared system has been developed to monitor transport infrastructures in a standalone configuration. Results obtained on bridges open to traffic allows to retrieve the inner structure of the decks. To complete this study, experiments were carried out over several months to monitor two reinforced concrete beams of 16 m long and 21 T each. Detection of a damaged area over one of the two beams was made by Pulse Phase Thermography approach. Measurements carried out over several months. Finally, conclusion on the robustness of the system is proposed andperspectives are presented

The detection and thermal characterization of the inner structure of the ‘Musmeci’ bridge deck by infrared thermography monitoring

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Nonlinear Refraction and Absorption of Ag 29 Nanoclusters: Evidence for Two-Photon Absorption Saturation

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Bulky Counterions: Enhancing the Two-Photon Excited Fluorescence of Gold Nanoclusters

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