Hydrogénation de charbons : étude par résonance magnétique nucléaire du

La fonctionalité et différents paramètres structuraux (facteurs d'aromaticité [math] fractions de carbones aromatiques non protonés et protonés [math] de résidus lourds obtenus après l'hydrogénation de deux charbons français (Gardanne et Vouters) à différents temps de traitement, avec ou sans catalyseur, ont été déterminés par spectroscopies de R.M.N. du 13C solide et Infra-Rouge à Transformée de Fourier. Les résultats montrent un accroissement du facteur d'aromaticité en fonction du temps de traitement des charbons. Cet accroissement est suivi par la disparition de certains groupements fonctionnels aromatiques et aliphatiques

Nuclear magnetic resonance spectroscopy of bone substitutes

9th European Meeting on Injectable Bone and Joint Substitution Materials, LAUSANNE, SWITZERLAND, MAR 01-02, 1999Calcium phosphate bone replacement biomaterials are widely used in different applications. Structure, composition, and organization are, before implantation, analyzed with different methods. Among them, X-ray diffraction is a recognized test. As bioresorption produces more amorphous material, the process is observed and quantified via scanning electron microscopy, Comparatively high-resolution P-31 solid-state nuclear magnetic resonance spectroscopy is able to analyze raw ceramics composition and to estimate osteoformation, (Bone 25:103S-105S; 1999) (C) 1999 by Elsevier Science Inc. All rights reserved

Specific characteristics of wet nanocrystalline apatites. Consequences on biomaterials and bone tissue.

International audienceThe anal. of wet nanocryst. apatites by spectroscopic techniques (FTIR, solid state NMR) reveals fine, transient, structural details testifying for the existence of a structured hydrated layer on the surface of nanocrystals probably related although not identical, to the structure of octacalcium phosphate. On drying this layer loses its very fragile structure and gives a disordered assembly of ions corresponding to non-apatitic environments. The existence of a hydrated layer with mobile ionic entities due to an enhanced surface reactivity, gives nanocryst. apatites very specific and interesting properties, which are used by living organisms in mineralized tissue and which can be utilized in material science. They allow strong intercryst. interactions, specific adsorption properties and adhesion to other surfaces