L2,3 x-ray absorption spectroscopy and multiplet calculations for KMF3 and K2 NaMF6 (M=Ni, Cu)

The electronic structures of nickel and copper have been studied for KMF3 and K2NaMF6 compounds by a-ray absorption spectroscopy at the Ni and Cu L-2.3 edges in order to characterize the M-F chemical bond. The spectral features have been interpreted based on the mixing of two ground-state configurations \3d(n)) +\3d(n+1)](L) under bar. Multiplet calculations were used to simulate each spectrum in order to quantify the charge transfer from fluorine to the transition metal yielding a 40% ground-state contribution of the 3d(8) configuration for K2NaCuF6 and 65% of the 3d(7) configuration for K2NaNiF6

Les système MF-InF3 (M = Rb, Cs, Tl)

International audienceL'étude des systèmes MF-InF3 (M = Rb, Cs, Tl) met en évidence dans tous les cas des composés de formules M3InF6, MInF4 et MIn3F10..

Transforming growth factor alpha: a promoter of motoneuron survival of potential biological relevance

International audienceExpression of transforming growth factor alpha (TGFalpha), a member of the epidermal growth factor (EGF) family, is a general response of adult murine motoneurons to genetic and experimental lesions, TGFalpha appearing as an inducer of astrogliosis in these situations. Here we address the possibility that TGFalpha expression is not specific to pathological situations but may participate to the embryonic development of motoneurons. mRNA of TGFalpha and its receptor, the EGF receptor (EGFR), were detected by ribonuclease protection assay in the ventral part of the cervical spinal cord from embryonic day 12 (E12) until adult ages. Reverse transcription-PCR amplification of their transcripts from immunopurified E15 motoneurons, associated with in situ double-immunohistological assays, identified embryonic motoneurons as cellular sources of the TGFalpha-EGFR couple. In vitro, TGFalpha promoted the survival of immunopurified E15 motoneurons in a dose-dependent manner, with a magnitude similar to BDNF neuroprotective effects at equivalent concentrations. In a transgenic mouse expressing a human TGFalpha transgene under the control of the metallothionein 1 promoter, axotomy of the facial nerve provoked significantly less degeneration in the relevant motor pool of 1-week-old mice than in wild-type animals. No protection was observed in neonates, when the transgene exhibits only weak expression levels in the brainstem. In conclusion, our results point to TGFalpha as a physiologically relevant candidate for a neurotrophic role on developing motoneurons. Its expression by the embryonic motoneurons, which also synthesize its receptor, suggests that this chemokine is endowed with the capability to promote motoneuron survival in an autocrine-paracrine manner

α-Li3InF6, a ternary fluoride with a new structure type

InF6 octahedra sharing common corners with [Li2F6], create an approximately hexagonally packed framework in the plane (1 0 0). The antiferroelectric behaviour evident from dielectric studies is confirmed by the antiparallel displacements of In and Li atoms from octahedral centres. This structure is mainly featured by the disorder observed in the lightest atoms...

Détermination structurale des fluorozirconates de thallium trivalent

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Cationic Distribution in α-MZr3F15 Series (M = Y, In, Ln, Tl)

International audienc

Isotopic composition of atmospheric nitrate in a tropical marine boundary layer

Long-term observations of the reactive chemical composition of the tropical marine boundary layer (MBL) are rare, despite its crucial role for the chemical stability of the atmosphere. Recent observations of reactive bromine species in the tropical MBL showed unexpectedly high levels that could potentially have an impact on the ozone budget. Uncertainties in the ozone budget are amplified by our poor understanding of the fate of NOx (= NO + NO2), particularly the importance of nighttime chemical NOx sinks. Here, we present year-round observations of the multiisotopic composition of atmospheric nitrate in the tropical MBL at the Cape Verde Atmospheric Observatory. We show that the observed oxygen isotope ratios of nitrate are compatible with nitrate formation chemistry, which includes the BrNO3 sink at a level of ca. 20 ± 10% of nitrate formation pathways. The results also suggest that the N2O5 pathway is a negligible NOx sink in this environment. Observations further indicate a possible link between the NO2/NOx ratio and the nitrogen isotopic content of nitrate in this low NOx environment, possibly reflecting the seasonal change in the photochemical equilibrium among NOx species. This study demonstrates the relevance of using the stable isotopes of oxygen and nitrogen of atmospheric nitrate in association with concentration measurements to identify and constrain chemical processes occurring in the MBL

Partial phase diagram of the ternary reciprocal system KF-AlF3-Al2O3-K2O

International audienceA K2ZrF6 treatment improves the wettability of SiC (or C) fibers by aluminum alloys. A possible mechanism involves the formation of K3AlF6 followed by the dissolution of the alumina film. DTA analyses of K3AlF6-α-Al2O3 mixtures show that a temperature invariant transition occurs at 1132K, the solid containing trace amounts of KAlF4 and β-alumina at room temperature. Part of the ternary reciprocal system KF-AlF3-Al2O3-K2O is calculated, the Gibbs free energy of the liquid being described according to the CIS theory. The K3AlF6-Al2O3 isopteth section is given. It is characterized by a liquidus with a deep minimum at 1132K and 11.6 wt % alumina

N-3 Polyunsaturated fatty acid supplementation improves hyperdopaminergic phenotypes in mice invalidated for dopamine transporter (DAT-KO)

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Holistic optimisation of noise reducing devices

International audienceThe work presented in this paper is part of the QUIESST European project, in which one of the objective is to perform multi-objective holistic optimisations of noise reducing devices. We present here optimisation results concerning the extrinsic performances of noise barriers. The performances under interest are acoustical, economical and environmental. The variety of noise barriers considered is very wide, ranging from straight and flat barriers, to rough or capped barriers. A total number of nine noise reducing device families are optimised. Acoustical performances are obtained from numerical calculations: the Boundary Element Method (in 2D) is used to obtain relative sound pressure levels at a set of receivers in different situations. Theses situations include road and rail sources; rural and urban cases; flat, embanked and depressed topographies. The economical performance is calculated according to the maintenance cost of the different materials in use in the barrier. Four environmental performances indicators are considered; their calculation is based on a life-cycle assessment analysis. All performances are expressed as a gain (or loss) relative to a reference screen. It is shown that the optimisation procedure allows one to obtain a wide variety of optimised noise reducing devices, and hence provides a helpful design tool by allowing one to focus on specific parameters