Ab initio study of boron-hydrogen complexes in diamond and their effect on electronic properties

7 pagesInternational audienceThe atomic and electronic structures of neutral and charged (+ and −) boron-hydrogen complexes in diamond are studied by means of density-functional theory calculations. The stability of the different configurations is discussed and used to derive ionization energies. For neutral B-H complex, H in puckered position along B-C axis is energetically more favorable. No density of states is then found within the diamond band gap but this configuration gives rise to an acceptor level at Ev+4.44 eV. B-H2 most stable structure gives a donor level at Ec−2.80 eV. Other geometries are also investigated to explain the discrepancy observed between recent electronic structure calculations. © 2008 The American Physical Societ

Deep hole traps in boron-doped diamond

International audienceDeep hole traps in boron-doped diamond epitaxial layers are studied by means of several types of deep-level transient spectroscopy and density-functional theory calculations. Standard deep-level transient spectroscopy and highresolution isothermal transient spectroscopy permit to identify nine deep hole traps. Their capture cross-sections and ionization energies are systematically determined. In parallel, the ionization energies of donor and acceptor levels related to boron- and/or hydrogen-related complexes in diamond are assessed by ab initio calculations in this work and summarized with others from the literature including native defects. Tentative assignments of the measured deep hole traps to the calculated ones are proposed

Disponibilité des contaminants organiques hydrocarbonés dans les sols : DECORES

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Lacoste, un village artisanal et commercial

National audienc

Impact of fresh organic matter incorporation on PAH fate in a contaminated industrial soil.

The impacts of fresh organic matter (OM) incorporation in an industrial PAH-contaminated soil on its structure and contaminant concentrations (available and total) were monitored. A control soil and a soil amended with the equivalent of 10 years maize residue input were incubated in laboratory-controlled conditions over 15 months. The structure of the amended soil showed an aggregation process trend which is attributable to (i) the enhanced microbial activity resulting from fresh OM input itself and (ii) the fresh OM and its degradation products. Initially the added organic matter was evenly distributed among all granulodensimetric fractions, and then rapidly degraded in the sand fraction, while stabilizing and accumulating in the silts. PAH degradation remained slight, despite the enhanced microbial biomass activity, which was similar to kinetics of the turnover rate of OM in an uncontaminated soil. The silts stabilized the anthropogenic OM and associated PAH. The addition of fresh OM tended to contribute to this stabilization process. Thus, in a context of plant growth on this soil two opposing processes might occur: rhizodegradation of the available contaminant and enhanced stabilization of the less available fraction due to carbon input

Quels besoins des enseignants dans la conception d’un éditeur de jeu sérieux pour tous ?

International audienceEnvironnement pédagogique fondé sur les jeux sérieux et permettant l’enseignement des apprentissages théoriques et expérimentaux pour des enfants en situation de handicap ou non

HPV-circulating tumoural DNA by droplet-based digital polymerase chain reaction, a new molecular tool for early detection of HPV metastatic anal cancer? A case report

International audienceno abstrac

Un atelier monétaire gaulois près de Poitiers : les Rochereaux à Migné-Auxances (Vienne)

International audienceDie Einordnung des bäuerlichen Betriebs der Ebene von Rochereaux in Migné-Auxances als Münzprägestätte begründet sich auf folgende Argumente: (1) allein die Entdeckung in situ dieser auf die Herstellung von Schrötlingen spezialisierten Bronzewerkstätte und der damit in Verbindung stehenden Verbrennungsstrukturen und Werkzeuge; (2) das Vorhandensein von vierzig zum Teil noch zusammenhaftenden Schrötlingen in der Asche der zentralen Feuerstelle; (3) eine minimale Schätzung, die vermuten lässt, dass wenn man von einer einzigen Benutzung der 152 erfassten Schmelztiegel ausgeht, 15 000 Schrötlinge hergestellt werden konnten; (4) die Übereinstimmung von Legierung, Modulen und Gewichten der Schrötlinge und der Münzen der Fundstelle sowie die Konzentration dieses Münztyps im Territorium der Piktonen. Die Produktion der Schrötlinge und deren sehr wahrscheinliche Prägung vor Ort fand zwischen 130 und 100 v. Chr. statt. Es ist sehr wahrscheinlich, dass die fünf Kilometer von Poitiers entfernte Stätte in enger Abhängigkeit mit diesem oppidum stand.The attribution of the status of a mint to the rural establishment of the Rochereaux at Migné-Auxances (Vienne) plain is based on: (1) the discovery of the physical space of a bronzesmith workshop specialized in the fabrication of monetary blanks, associated with combustion structures and tools; (2) the presence of forty monetary blanks in the ashes of the central hearth, some of which are still associated in clusters; (3) a minimal estimation that leads us to propose that, from a single utilization of the 152 crucibles recorded, 15,000 monetary blanks could be fabricated; (4) the concurrence between - in alloys, proportions and weight - blanks and coins at the site, as well as the concentration of this type of coin in the Pictone territory. The production of blanks and their very likely minting at this site occurred between 130 and 100 BC. It is highly probable that this site, located 5 km from Poitiers, maintained close dependant links with this oppidum.L’attribution du statut d’atelier monétaire à l’établissement rural de plaine des Rochereaux à Migné-Auxances (Vienne) se fonde sur : (1) la découverte de l’espace physique de l’atelier de bronziers, spécialisé dans la fabrication de flans monétaires, associé à des structures de combustion et à des outils ; (2) la présence dans les cendres du foyer central de quarante flans monétaires, dont certains sont encore associés en grappe ; (3) une estimation minimale qui conduit à proposer que, à partir d’une seule utilisation des 152 creusets recensés, 15 000 flans monétaires ont pu être fabriqués ; (4) les coïncidences entre alliages, modules et poids des flans et des monnaies du site ainsi que la concentration de ce type de monnaies en territoire picton. La production des flans et leur très plausible frappe sur place eut lieu entre 130 et 100 av. J.-C. Il est fort possible que le site, situé à 5 km de Poitiers, ait entretenu des liens de dépendance étroits avec cet oppidum