Ultrafine heat-induced structural perturbations of bone mineral at the individual nanocrystal level

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Solvent contribution to the stability of a physical gel characterized by quasi-elastic neutron scattering

The dynamics of a physical gel, namely the Low Molecular Mass Organic Gelator {\textit Methyl-4,6-O-benzylidene-$\alpha$ -D-mannopyranoside ($\alpha$-manno)} in water and toluene are probed by neutron scattering. Using high gelator concentrations, we were able to determine, on a timescale from a few ps to 1 ns, the number of solvent molecules that are immobilised by the rigid network formed by the gelators. We found that only few toluene molecules per gelator participate to the network which is formed by hydrogen bonding between the gelators' sugar moieties. In water, however, the interactions leading to the gel formations are weaker, involving dipolar, hydrophobic or $\pi-\pi$ interactions and hydrogen bonds are formed between the gelators and the surrounding water. Therefore, around 10 to 14 water molecules per gelator are immobilised by the presence of the network. This study shows that neutron scattering can give valuable information about the behaviour of solvent confined in a molecular gel.Comment: Langmuir (2015

Spin-Glass Model for Inverse Freezing

We analyze the Blume-Emery-Griffiths model with disordered magnetic interaction displaying the inverse freezing phenomenon. The behaviour of this spin-1 model in crystal field is studied throughout the phase diagram and the transition and spinodal lines for the model are computed using the Full Replica Symmetry Breaking Ansatz that always yelds a thermodynamically stable phase. We compare the results both with the quenched disordered model with Ising spins on lattice gas - where no reentrance takes place - and with the model with generalized spin variables recently introduced by Schupper and Shnerb [Phys. Rev. Lett. 93, 037202 (2004)]. The simplest version of all these models, known as Ghatak-Sherrington model, turns out to hold all the general features characterizing an inverse transition to an amorphous phase, including the right thermodynamic behavior.Comment: 6 pages, 4 figures, to appear in the Proceeding for the X International Workshop on Disordered Systems (2006), Molveno, Ital

Which place for spatial modelling in GIS education?: the example of the GITTA project

The GITTA project covers the overall matter of Geographic Information Sciences (GIS). Spatial modelling (SM) is the particular theme of GIS as it is everywhere in the life cycle of Geographic Information (GI). No analysis without modelling, no database without modelling, no data capture without modelling, etc. Thus SM could be tackled in every module of a GIS course such as spatial analysis, data capture, databases. The course structure proposed for the GITTA project introduces two modules of one ECTS (European Credit Transfer System) unit each entirely devoted to SM. The particularity of SM induces that the content of the SM modules is narrowly related to the others. Deciding the place of particular modelling notions during the integration phase of the content of the modules is of prior importance. This requires that we precisely settle the frontier between modules by clearly explicating the links between modules according to their structural line. The paper aims at bringing some elements of reflexion on the enhancement of the quality of the structure and content of the GIS courses by dealing with the central issue of spatial modelling

Note: Anharmonicity of quasi-lattice modes in glass and super-fragile liquid states of decahydroisoqinoline: C9H17N

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