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The aldehyde oxidoreductase from Desulfovibrio gigas belongs to the family of molybdenum hydroxylases. Besides a molybdenum cofactor which constitutes their active site, these enzymes contain two [2Fe-2S](2+,1+) clusters which are believed to transfer the electrons provided by the substrate to an acceptor which is either a FAD group or an electron-transferring protein. When the three metal centers of D. gigas AOR are simultaneously paramagnetic, splittings due to intercenter spin-spin interactions are visible when the EPR spectra are recorded at low temperatures. By studying quantitatively these interactions with a model based on the X-ray crystal structure, which takes into consideration the interactions between the magnetic moments carried by all the metal sites of the system, it is possible to determine the location of the reducible sites of the [2Fe-2S] clusters. When combined with the electron-transfer pathways proposed on the basis of the X-ray crystal structure, the results provide a detailed description of the electron-transfer system of D. gigas AOR.

2014 Un important effet de pseudo-gap dans la densité d'états au niveau de Fermi a été observé au moyen de l'effet tunnel de type Schottky entre GaSb (dopé N) et le supraconducteur organique (TMTSF)2PF6 sous pression de 11 kbar (Tc = 1 K). Ce phénomène permet de prouver expérimentalement sans ambiguïté les propriétés unidimensionnelles de la divergence supraconductrice et justifie la présence de fluctuations 1-D supraconductrices jusqu'aux températures élevées. Les résultats ont permis de mesurer une énergie de condensation de paires 2 0394(0) = 3,6 meV qui démontre bien la forte intensité de la divergence supraconductrice dans la famille des supraconducteurs organiques (TMTSF)2X.

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We have studied the spin-lattice relaxation behaviour of Mn2+ in cubic ZnS at 9 375 MHz between 80 K and 900 K by measuring the line broadening of the |1/2 1/2> → 1/2 - 1/2> transition. This study shows that for high temperatures (T > 273 K) the measured spin-lattice relaxation time T1 varies as T-11 = αT 7 I6 (θD) β[sh2 θ o T]-1. The first term corresponds to a Raman process associated with the acoustical phonons, the second one arises from the optical phonons distribution. The transition probabilities calculation shows that the contributions from the optical and acoustical phonons are similar

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