Electronic and physico-chemical properties of nanmetric boron delta-doped diamond structures

Heavily boron doped diamond epilayers with thicknesses ranging from 40 to less than 2 nm and buried between nominally undoped thicker layers have been grown in two different reactors. Two types of [100]-oriented single crystal diamond substrates were used after being characterized by X-ray white beam topography. The chemical composition and thickness of these so-called deltadoped structures have been studied by secondary ion mass spectrometry, transmission electron microscopy, and spectroscopic ellipsometry. Temperature-dependent Hall effect and four probe resistivity measurements have been performed on mesa-patterned Hall bars. The temperature dependence of the hole sheet carrier density and mobility has been investigated over a broad temperature range (6K<T<450 K). Depending on the sample, metallic or non-metallic behavior was observed. A hopping conduction mechanism with an anomalous hopping exponent was detected in the non-metallic samples. All metallic delta-doped layers exhibited the same mobility value, around 3.660.8 cm2/Vs, independently of the layer thickness and the substrate type. Comparison with previously published data and theoretical calculations showed that scattering by ionized impurities explained only partially this low common value. None of the delta-layers showed any sign of confinement-induced mobility enhancement, even for thicknesses lower than 2 nm.14 page

A Survey on Retrieval of Mathematical Knowledge

We present a short survey of the literature on indexing and retrieval of mathematical knowledge, with pointers to 72 papers and tentative taxonomies of both retrieval problems and recurring techniques.Comment: CICM 2015, 20 page

Molecular Mechanisms Generating and Stabilizing Terminal 22q13 Deletions in 44 Subjects with Phelan/McDermid Syndrome

In this study, we used deletions at 22q13, which represent a substantial source of human pathology (Phelan/McDermid syndrome), as a model for investigating the molecular mechanisms of terminal deletions that are currently poorly understood. We characterized at the molecular level the genomic rearrangement in 44 unrelated patients with 22q13 monosomy resulting from simple terminal deletions (72%), ring chromosomes (14%), and unbalanced translocations (7%). We also discovered interstitial deletions between 17–74 kb in 9% of the patients. Haploinsufficiency of the SHANK3 gene, confirmed in all rearrangements, is very likely the cause of the major neurological features associated with PMS. SHANK3 mutations can also result in language and/or social interaction disabilities. We determined the breakpoint junctions in 29 cases, providing a realistic snapshot of the variety of mechanisms driving non-recurrent deletion and repair at chromosome ends. De novo telomere synthesis and telomere capture are used to repair terminal deletions; non-homologous end-joining or microhomology-mediated break-induced replication is probably involved in ring 22 formation and translocations; non-homologous end-joining and fork stalling and template switching prevail in cases with interstitial 22q13.3. For the first time, we also demonstrated that distinct stabilizing events of the same terminal deletion can occur in different early embryonic cells, proving that terminal deletions can be repaired by multistep healing events and supporting the recent hypothesis that rare pathogenic germline rearrangements may have mitotic origin. Finally, the progressive clinical deterioration observed throughout the longitudinal medical history of three subjects over forty years supports the hypothesis of a role for SHANK3 haploinsufficiency in neurological deterioration, in addition to its involvement in the neurobehavioral phenotype of PMS

Study of (La,Sr)(Ti,Ni)O3-δ materials for symmetrical Solid Oxide Cell electrode - Part A: Synthesis and structure analysis in air

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Study of (La,Sr)(Ti,Ni)O3-δ materials for symmetrical Solid Oxide Cell electrode - Part C: Electrical and electrochemical behavior

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Study of (La,Sr)(Ti,Ni)O3-δ materials for symmetrical Solid Oxide Cell electrode - Part B: Conditions of Ni exsolution

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Exsolution of nickel nanoparticles at the surface of a conducting titanate as potential hydrogen electrode material for solid oxide electrochemical cells

International audienceA new La0.5Sr0.5Ti0.75Ni0.25O3 (LSTN25) titanate was proposed as a hydrogen electrode for Solid Oxide Cells (SOCs) with electrochemical performance given by Ni nanoparticles exsoluted at the surface of a conducting oxide. As only in-situ reduction at 800 °C has been proposed in literature to perform Ni exsolution, the reduction at higher temperature of the LSTN25 compound was also considered in this work. The high-temperature treatment led to the precipitation of Ni nanoparticles evidenced by TEM observation and to an improved electrical conductivity that may be due to the formation of a sufficiently high concentration of Ti3+. Electrochemical study of symmetrical cells tested in H2/H2O (97/3) showed a promising performance, with a polarization resistance of 0.55 Ω cm2 at 800 °C and 0.46 Ω cm2 after a thermal treatment in air that simulates the air electrode sintering

Electrochemical properties of novel SOFC dual electrode La(0.75)Sr(0.25)Cr(0.5)Mn(0.3)Ni(0.2)O(3) (-) (delta)

International audienceThe perovskite La0.75Sr0.25Cr0.5Mn0.3Ni0.2O3−δ (LSCMMn0.30Ni0.20) was evaluated as potential electrode for solid oxide fuel cells. The electrochemical performances of LSCMMn0.30Ni0.20 for hydrogen oxidation and oxygen reduction reactions were studied at 800 °C. Symmetrical cells LSCMMn0.30Ni0.20/YSZ/LSCMMn0.30Ni0.20 were studied by electrochemical impedance spectroscopy. The total conductivity of LSCMMn0.30Ni0.20 is 22 S cm−1 in air and 0.8 S cm−1 under wet 5% H2/Ar at 800 °C. The area specific resistance (ASR) at 800 °C for hydrogen oxidation reaction is 1 Ω cm2. The ASR for oxygen reduction reaction is 1.6 Ω cm2. An ageing study during 24 h shows a relatively good stability of the electrochemical performances. LSCMMn0.3Ni0.2 seems to be a promising dual electrode for a symmetrical SOFC