Fractal structures and silica films formed by the Treignac water on inert and biological surfaces.

The Treignac water is a natural mineral water containing mainly orthosilicic acid. On inert substrates, it forms a silica film with fractal structures which cannot be reproduced in laboratory-reconstituted water. These structures form by condensation of orthosilicic acid monomers, following the Witten-Sander model of diffusion-limited aggregation.

Citrobacter freundii induced endocarditis in a yearling colt.

Endocarditis is a rare pathology in horses and the clinical signs can be misleading. We describe the clinical, echocardiographic, and pathological features of Citrobacter freundii induced bacterial endocarditis in a horse. This bacterium has never been reported before as an agent of vegetative endocarditis in the horse.

Interfacial reactions between humic-like substances and lateritic clay: application to the preparation of "geomimetic" materials.

The aim of this study was to understand the mechanisms responsible for the strengthening of "geomimetic" materials, especially the chemical bonding between clay and humic substances. The mineral matter is lateritic clay which mainly consists in kaolinite, goethite, hematite and quartz. The other starting products are fulvic acid (FA) and lime.

Structural and microstructural studies of montmorillonite-based multilayer nanocomposites.

Hypotheses: Montmorillonite, an abundant raw material, is a good candidate to obtain textured nanocomposites. However, the resulting structure of the composite depends on the dispersant used. This work aims at investigating the effect of organic polysaccharides, namely carboxymethylcellulose (CMC) or chitosan (Ch) differing by their side groups, on the resulting structure of montmorillonite-based nanocomposites.

Nanocomposites derived from montmorillonite and metallosupramolecular polyelectrolytes: modular compounds for electrorheological fluids.

Nanocomposites made from Na-montmorillonite and metallo-supramolecular polyelectrolytes (MEPE) based on nickel and ditopic bis-terpyridine ligands are prepared by an aqueous synthesis. Intercalation is confirmed by IR-spectroscopy, thermogravimetric analysis, and X-ray powder diffraction. The rheological response in the presence of an electric field of the dispersed nanocomposites in silicone oil is measured with a rheometer.

Surface properties of kaolin and illite suspensions in concentrated calcium hydroxide medium.

The adsorption behaviour of calcium hydroxide onto illite and kaolin clay minerals was investigated by monitoring with atomic emission spectroscopy and pH measurements the amounts of ions left in solution after exposing clay minerals to calcium hydroxide solutions of various concentrations. Both clay minerals can adsorb calcium and hydroxyl ions. Rather than just considering proton exchanges at the clay mineral surfaces, the adsorption is explained by an approach based on Lewis description of molecules.