Few Graphene layer/Carbon-Nanotube composite Grown at CMOS-compatible Temperature

We investigate the growth of the recently demonstrated composite material composed of vertically aligned carbon nanotubes capped by few graphene layers. We show that the carbon nanotubes grow epitaxially under the few graphene layers. By using a catalyst and gaseous carbon precursor different from those used originally we establish that such unconventional growth mode is not specific to a precise choice of catalyst-precursor couple. Furthermore, the composite can be grown using catalyst and temperatures compatible with CMOS processing (T < 450\degree C).Comment: 4 pages, 4 figure

Model and fitting results for the filamentary conduction in MIM resistive switching devices

Experimental results for the resistive switching effect occurring in Pt/HfO2/Pt devices are analyzed within the framework of the two-terminal Landauer theory for mesoscopic conducting systems. It is shown that the magnitude of the current and the voltage dependence of the switching conduction characteristic are mainly dictated by the size of the filamentary path generated after electroforming. The temperature dependence of the high resistance conduction characteristics is also modeled in a consistent manner with the proposed picture.Fil: Palumbo, Félix Roberto Mario. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Miranda, Enrique. Universitat Autònoma de Barcelona; EspañaFil: Ghibaudo, Gerard. Université Savoie Mont Blanc; FranciaFil: Jousseaume, V.. Université Savoie Mont Blanc; Franci

Effect of the C-bridge length on the ultraviolet-resistance of oxycarbosilane low-k films

The ultra-violet (UV) and vacuum ultra-violet (VUV) resistance of bridging alkylene groups in organosilica films has been investigated. Similar to the Si-CH3 (methyl) bonds, the Si-CH2-Si (methylene) bonds are not affected by 5.6 eV irradiation. On the other hand, the concentration of the Si-CH2-CH2-Si (ethylene) groups decreases during such UV exposure. More significant difference in alkylene reduction is observed when the films are exposed to VUV (7.2 eV). The ethylene groups are depleted by more than 75% while only about 40% methylene and methyl groups loss is observed. The different sensitivity of bridging groups to VUV light should be taken into account during the development of curing and plasma etch processes of low-k materials based on periodic mesoporous organosilicas and oxycarbosilanes. The experimental results are qualitatively supported by ab-initio quantum-chemical calculations

XAFS atomistic insight of the oxygen gettering in Ti/HfO2 based OxRRAM

Hafnia-based resistive memories technology has come to maturation and acceded to the market of nonvolatile memories. Nevertheless, the physical mechanisms involved in resistive switching are not yet fully understood and the numerous ab initio simulations studies have few many atomic-scale experimental counterparts. In this study we investigate the oxygen migration mechanism from an amorphous HfO2 layer to the Ti cap layer at a local scale before and after a thermal treatment. X-ray absorption spectroscopy at the Ti K edge and Hf L(III )edge has been performed on samples as-deposited and annealed in Ar at 400 degrees C to mimic the back-end-of-line thermal budget (BEOL) of CMOS technology. The short-range Ti and Hf environments have been determined, showing that annealing promotes the migration of O from HfO2 to Ti, the amount of which is quantified. This provokes an expansion and an increase of atomic disorder in the Ti lattice. The nature of the oxygen gettering mechanism by the Ti metal is understood by comparing samples with increasing Ti-capping thickness. We show that the Ti getter effect has to be activated by thermal treatment and that the O diffusion takes place in a region of a few nanometers close to the Ti/HfO2 interface. Therefore, the thermal budget history and the Ti cap-layer thickness determine the oxygen vacancy content in the HfO2 layer, which in turn controls the electrical properties, especially the forming operation

The prognostic value of the hypoxia markers CA IX and GLUT 1 and the cytokines VEGF and IL 6 in head and neck squamous cell carcinoma treated by radiotherapy ± chemotherapy

BACKGROUND: Several parameters of the tumor microenvironment, such as hypoxia, inflammation and angiogenesis, play a critical role in tumor aggressiveness and treatment response. A major question remains if these markers can be used to stratify patients to certain treatment protocols. The purpose of this study was to investigate the inter-relationship and the prognostic significance of several biological and clinicopathological parameters in patients with head and neck squamous cell carcinoma (HNSCC) treated by radiotherapy ± chemotherapy. METHODS: We used two subgroups of a retrospective series for which CT-determined tumoral perfusion correlated with local control. In the first subgroup (n = 67), immunohistochemistry for carbonic anhydrase IX (CA IX) and glucose transporter-1 (GLUT-1) was performed on the pretreatment tumor biopsy. In the second subgroup (n = 34), enzyme linked immunosorbent assay (ELISA) was used to determine pretreatment levels of the cytokines vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) in serum. Correlation was investigated between tumoral perfusion and each of these biological markers, as well as between the markers mutually. The prognostic value of these microenvironmental parameters was also evaluated. RESULTS: For CA IX and GLUT-1, the combined assessment of patients with both markers expressed above the median showed an independent correlation with local control (p = 0.02) and disease-free survival (p = 0.04) with a trend for regional control (p = 0.06). In the second subgroup, IL-6 pretreatment serum level above the median was the only independent predictor of local control (p = 0.009), disease-free survival (p = 0.02) and overall survival (p = 0.005). CONCLUSION: To our knowledge, we are the first to report a link in HNSCC between IL-6 pretreatment serum levels and radioresistance in vivo. This link is supported by the strong prognostic association of pretreatment IL-6 with local control, known to be the most important parameter to judge radiotherapy responses. Furthermore, the combined assessment of CA IX and GLUT-1 correlated independently with prognosis. This is a valuable indication that a combined approach is important in the investigation of prognostic markers

À qui appartient la Loire-Atlantique? Propriétés et propriétaires moraux

National audienceLa caractérisation des propriétaires fonciers paraît essentielle : elle rejoint des débats contemporains – sur l'étalement urbain, les grands projets d'aménagement – et permet d'évaluer l'éventualité d'actions foncières. Elle est rendue possible à l'échelle départementale par l'exploitation de la documentation cadastrale littérale numérisée, reliant des propriétaires physiques ou moraux au parcellaire de propriété. Après s'être intéressée aux ayant-droits particuliers, une analyse géographique et quantitative de la propriété foncière en Loire-Atlantique caractérise les propriétaires moraux, leurs biens-fonds, et les spatialise. Les propriétés morales recouvrent 20% du département. Hétéroclites, elles répondent aux fonctions et aux ambitions de leurs possesseurs, et dessinent une géographie presque « habituelle » du territoire. Ecrite par l'histoire, les rapports socio-économiques régionaux, le peuplement et l'urbanisation du département, celle-ci témoigne du rôle des propriétaires fonciers, acteurs géographiques, dans la construction et l'organisation des territoires

Trajectoires résidentielles et mobilités quotidiennes. Les quatre « figures habitantes » du Pays du Vignoble nantais

International audienceThe abundant literature on modes of dwelling has cast light on the many complex socio-spatial changes at work in peri-urban areas. We propose here to update this approach by reconsidering the systemic connection between people’s residential trajectory and the forms taken by their daily mobility. After analysing the track record of 64 adults, we used factor analysis to obtain a synthetic typology of forms of rootedness. Our study revealed a predictable divide between “newcomers’’, often of urban origin and highly mobile in their daily lives, and the less mobile, more rooted native population. However, a second “inverse’’ split also emerged, embodied by two other types: “newcomers looking for local connections’’; and the “mobile rooted’’. We can thus show that the relation between residential trajectory and daily mobility is far from automatic. Rather, these two elements are combined and acting jointly to produce and differentiate modes of dwelling.Numerosos estudios sobre las maneras de habitar permiten de captar lo complejo de los cambios socio-espaciales de los habitantes del campo aledaño a las ciudades. Proponemos aquí actualizar este enfoque, teniendo en cuanta la articulación sistémica entre la trayectoria residencial de la gente y las formas de su desplazamiento cotidiano. Sobre los datos consignados en un carnet de ruta de 64 adultos, utilizamos el análisis factorial para construir una tipología sintética de formas de consolidación. En este estudio surge una separación, bastante esperada, entre los “intrusos”, frecuentemente urbanos, de alta movilidad cotidiana, y las poblaciones nativas localmente más fijas. Sin embargo, surge un segundo plan de separación “inversa” representada por otros dos tipos: los “intrusos en busca de local” y los “enraizados móviles”. Demostramos así que la relación entre la trayectoria residencial y el desplazamiento cotidiano no es mecánica, pues los dos elementos se combinan y co-actúan elaborando y diferenciando maneras de habitar.De nombreux travaux portant sur les modes d’habiter ont permis d’appréhender la complexitédes changements sociospatiaux à l’oeuvre dans les campagnes proches des villes. Nousproposons ici d’en renouveler l’approche en reconsidérant l’articulation systémique entre la trajectoire résidentielle des personnes et les formes de leur mobilité quotidienne. À partir du dépouillement du carnet de bord de 64 adultes, nous utilisons l’analyse factorielle pour faire émerger une typologie synthétique des formes d’ancrage. L’étude fait apparaître un plan de clivage assez attendu entre les « survenus », souvent d’origine urbaine et très mobiles au quotidien, et les populations natives, plus ancrées localement. Cependant, un deuxième plan de clivage « inverse» apparaît, incarné par deux autres types : les « survenus en quête de local » et les « enracinés mobiles ». Nous montrons ainsi que la relation entre la trajectoire résidentielle et la mobilité quotidienne n’est pas mécanique, mais que ces deux éléments se combinent et coagissent dans l’élaboration et la différenciation des modes d’habiter

Resistance switching of Cu/SiO2 memory cells studied under voltage and current-driven modes

International audienc