The electrochemical reactions of Li with c-Mg2Sn have been investigated by in situ Mössbauer spectroscopy of 119Sn and X-ray diffraction. The lithiation transforms initially c-Mg2Sn part into ...LixMg2Sn alloy (x<0.5). On further lithiation Mg is extruded from the structure with formation of Li2MgSn ternary alloy. In situ Mössbauer spectroscopy provides valuable information on local environment of tin and swelling behavior and cracking of the particles during discharge and charge processes.
Ce papier présente une méthode de localisation d'engins sous-marins par mise en correspondance d'un banc de mesures bathymétriques délivrées par un sonar multifaisceau avec un modèle numérique de ...terrain (MNT). Cette mise en correspondance est réalisée par l'utilisation d'une extension des formules classiques de corrélation prenant en compte le fait que les données sonar ne sont pas échantillonnées de façon régulière dans l'espace de représentation du MNT. Le couplage de cet algorithme avec un estimateur de mouvement permet de réduire la dimension de l'espace de recherche. Les résultats obtenus avec un modèle réel de relief sous-marin illustrent les performances des algorithmes présentés.
New techniques in molecular biology can be used to characterize genes whose expression is induced by drought stress. These techniques can be used to understand responses of range plants to ...environmental stresses at the biochemical and molecular level. For example, they can be used to characterize genes that respond to drought stress conditions in the native shrub Atriplex canescens (Pursh.) Nutt. Complementary DNA (cDNA) libraries constructed from drought-induced messenger RNA (poly A+RNA) were used to characterize genes which are associated with the stress response. A cDNA library from A. canescens was prepared. This library from stressed shrubs was differentially screened with radiolabeled cDNA probes from stressed and nonstressed shrubs, and apparent drought-induced clones were identified. This is the first report of molecular characterization of drought responsive genes in fourwing saltbush. The identification of genes specific to responses to drought stress could provide a basis for understanding drought tolerance in this important range species.
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