Structural characterization of water-bearing silicate and aluminosilicate glasses by high-resolution solid-state NMR

Various one- and two-dimensional high-resolution solid-state NMR techniques have been applied to hydrous silicate and aluminosilicate glasses: simple acquisition, cross-polarization (CP-MAS), heteronuclear correlation (HETCOR), dipolar dephasing, spin counting, double-quantum correlation, and rotational echo double resonance (REDOR). The comparison of the results obtained for sodium tetrasilicate and phonolite glasses suggests that the water incorporation mechanisms are qualitatively similar for these two compositions. From proton NMR experiments, we observe no evidence of proton clustering and a wide range of chemical shifts ranging from 0 to 16 ppm, even for the aluminosilicate phonolite glass, identifying at least three types of hydroxyl (OH) protons in addition to molecular H2O. This variety of OH groups can be discussed in terms of hydrogen bonding strength. For both compositions, the results indicate some depolymerization of the tetrahedral network, but the picture cannot be so simple as to completely exclude any of the different previously proposed models for water incorporation in silicate glasses

Revealing defects in crystalline lithium-ion battery electrodes by solid state NMR: applications to LiVPO4F

International audienceIdentifying and characterizing defects in crystalline solids is a challenging problem, particularly for lithium-ion intercalation materials, which often exhibit multiple stable oxidation and spin states as well as local ordering of lithium and charges. Here, we reveal the existence of characteristic lithium defect environments in the crystalline lithium-ion battery electrode LiVPO4F and establish the relative subnanometer-scale proximities between them. Well-crystallized LiVPO4F samples were synthesized with the expected tavorite-like structure, as established by X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM) measurements. Solid-state 7Li nuclear magnetic resonance (NMR) spectra reveal unexpected paramagnetic 7Li environments that can account for up to 20% of the total lithium content. Multidimensional and site-selective solid-state 7Li NMR experiments using finite-pulse radio frequency-driven recoupling (fp-RFDR) establish unambiguously that the unexpected lithium environments are associated with defects within the LiVPO4F crystal structure, revealing the existence of dipole–dipole-coupled defect pairs. The lithium defects exhibit local electronic environments that are distinct from lithium ions in the crystallographic LiVPO4F site, which result from altered oxidation and/or spin states of nearby paramagnetic vanadium atoms. The results provide a general strategy for identifying and characterizing lithium defect environments in crystalline solids, including paramagnetic materials with short 7Li NMR relaxation times on the order of milliseconds

Novel phosphate–phosphonate hybrid nanomaterials applied to biology

International audienceA new process for preparing oligonucleotide arrays is described that uses surface grafting chemistry which is fundamentally different from the electrostatic adsorption and organic covalent binding methods normally employed. Solid supports are modified with a mixed organic/inorganic zirconium phosphonate monolayer film providing a stable, well-defined interface. Oligonucleotide probes terminated with phosphate are spotted directly to the zirconated surface forming a covalent linkage. Specific binding of terminal phosphate groups with minimal binding of the internal phosphate diesters has been demonstrated. On the other hand, the reaction of a bisphosphonate bone resorption inhibitor (Zoledronate) with calcium deficient apatites (CDAs) was studied as a potential route to local drug delivery systems active against bone resorption disorders. A simple mathematical model of the Zoledronate/CDA interaction was designed that correctly described the adsorption of Zoledronate onto CDAs. The resulting Zoledronate-loaded materials were found to release the drug in different phosphate-containing media, with a satisfactory agreement between experimental data and the values predicted from the model

Evolution of LTCC technology for industrial applications

The LTCC (Low Temperature Cofired Ceramic) technology has been used for years in various applications like automotive (under the hood), data-processing, telecoms, datacoms, military and space, industrial, packaging. The evolution of the materials, processes and approach have reinforced its cost and performance attractivity. This is particularly true in the case of high frequency / optoelectronic products. This paper gives an overview of the enabling features of the LTCC technology for these applications, as well as an example of a 10 Gb/s transmitter

5. Chronique législative et réglementaire

Massiot Michel. 5. Chronique législative et réglementaire. In: Annuaire des collectivités locales. Tome 7, 1987. pp. 185-196

5. Chronique législative et réglementaire

Massiot Michel. 5. Chronique législative et réglementaire. In: Annuaire des collectivités locales. Tome 10, 1990. pp. 137-145

5. Chronique législative et réglementaire

Massiot Michel. 5. Chronique législative et réglementaire. In: Annuaire des collectivités locales. Tome 9, 1989. pp. 135-145

5. Chronique législative et réglementaire

Massiot Michel. 5. Chronique législative et réglementaire. In: Annuaire des collectivités locales. Tome 12, 1992. pp. 163-173