Visina Schottkyjeve barijere Pb/Si(111)1×1–H

We studied Schottky barrier height of lead on n- and p-type ideally terminated Si(111)1×1-H unreconstructed surface by electrical measurements and X-ray photoelectron spectroscopy (XPS). The hydrogenation of the Si(111) surface was done by means of wet etching in HF and NH4F. The deposition of Pb was made under ultrahigh vacuum conditions. There are differences between the barrier heights from the I-V and from the XPS measurements. The reasons seem to be a bad wettability of Pb to Si(111)1×1-H and a possible surface reconstruction of Si under the thicker metal film.Električnim mjerenjima i rendgenskom fotoelektronskom spektroskopijom (XPS) proučavana je visina Schottkyjeve barijere olova na n– i p– idealno završenoj nerekonstruiranoj površini Si(111)1×1–H. Hidrogenizacija Si(111) površine načinjena je jetkanjem u vodenoj otopini HF i NH4F. Olovo je napareno u ultravisokom vakuumu. Opažena je neusklađenost rezultata za visinu barijere I −V i XPS mjerenjima, što se tumači lošom močivošću Pb na Si(111)1 × 1–H i mogućom obnovom površine Si pod debljim slojem Pb

Germanene: a novel two-dimensional germanium allotrope akin to graphene and silicene

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.We have grown an atom-thin, ordered, two-dimensional multi-phase film in situ through germanium molecular beam epitaxy using a gold (111) surface as a substrate. Its growth is similar to the formation of silicene layers on silver (111) templates. One of the phases, forming large domains, as observed in scanning tunneling microscopy, shows a clear, nearly flat, honeycomb structure. Thanks to thorough synchrotron radiation core-level spectroscopy measurements and advanced density functional theory calculations we can identify it as a √3 × √3 R(30°) germanene layer in conjunction with a √7 × √7 R(19.1°) Au(111) supercell, presenting compelling evidence of the synthesis of the germanium-based cousin of graphene on gold.Funding from the 2D-NANOLATTICES project within the 7th Framework Programme for Research of the European Commission, under FET-Open grant number 270749 is greatly appreciated. We acknowledge support from the European Research Council Advanced Grant DYNamo (ERC-2010-AdG-267374), Grupos Consolidados UPV/EHU del Gobierno Vasco (IT-578-13) and European Commission project CRONOS (grant number 280879-2).Peer Reviewe

Hervé Faye (1814-1902)

Cette chronologie non exhaustive rassemble des informations éparses, des évènements et faits inconnus ou méconnus jusqu’à présent, permettant au lecteur de se faire une idée générale du déroulement de la vie et de la carrière d’Hervé Faye. Le lecteur se reportera aux divers articles de ce volume pour le développement de tel ou tel aspect de son oeuvre. La bibliographie est construite sur l’inventaire de la BNF (Opale Plus) et ne prend en compte que les principaux ouvrages imprimés et les cour..

Graphene-like silicon nanoribbons on Ag(110): A possible formation of silicene

Scanning tunneling microscopy (STM) and ab initio calculations based on density functional theory (DFT) were used to study the self-aligned silicon nanoribbons on Ag(110) with honeycomb, graphene-like structure. The silicon honeycombs structure on top of the silver substrate is clearly observed by STM, while the DFT calculations confirm that the Si atoms adopt spontaneously this new silicon structure

The fate of the 2√3 × 2√3R(30°) silicene phase on Ag(111)

Silicon atoms deposited on Ag(111) produce various single layer silicene sheets with different buckling patterns and periodicities. Low temperature scanning tunneling microscopy reveals that one of the silicene sheets, the hypothetical √7 × √7 silicene structure, on 2√3 × 2√3 Ag(111), is inherently highly defective and displays no long-range order. Moreover, Auger and photoelectron spectroscopy measurements reveal its sudden death, to end, in a dynamic fating process at ∼300 °C. This result clarifies the real nature of the 2√3 × 2√3R(30°) silicene phase and thus helps to understand the diversity of the silicene sheets grown on Ag(111)

Various atomic structures of monolayer silicene fabricated on Ag(111)

Silicene, a monolayer of silicon atoms arranged in honeycomb lattices, can be synthesized on the Ag(111) surface, where it forms several superstructures with different buckling patterns and periodicity. Using scanning tunneling microscopy (STM), we obtained high-resolution images of silicene grown on Ag(111) and revealed its five phases, i.e., 4 × 4 − α, 4 × 4 − β, − α, − β and − γ, some observed for the first time. For each of the phases, we have determined its atomic structure by comparing the atomic-resolution STM images with theoretical simulation results previously reported. We thus eliminate the contradictions of previous studies on the structural models of various silicene phases supported by the Ag(111) surface.EC/FP7/270749/EU/Strongly anisotropic Graphite-like semiconductor/dielectric 2D nanolattices/2D-NANOLATTICE

Vascular endothelial cell expression of JAK2V617F is sufficient to promote a pro-thrombotic state due to increased P-selectin expression

Thrombosis is the main cause of morbidity and mortality in patients with JAK2V617F myeloproliferative neoplasms. Recent studies have reported the presence of JAK2V617F in endothelial cells of some patients with myeloproliferative neoplasms. We investigated the role of endothelial cells that express JAK2V617F in thrombus formation using an in vitro model of human endothelial cells overexpressing JAK2V617F and an in vivo model of mice with endothelial-specific JAK2V617F expression. Interestingly, these mice displayed a higher propensity for thrombus. When deciphering the mechanisms by which JAK2V617F-expressing endothelial cells promote thrombosis, we observed that they have a pro-adhesive phenotype associated with increased endothelial P-selectin exposure, secondary to degranulation of Weibel-Palade bodies. We demonstrated that P-selectin blockade was sufficient to reduce the increased propensity of thrombosis. Moreover, treatment with hydroxyurea also reduced thrombosis and decreased the pathological interaction between leukocytes and JAK2V617F-expressing endothelial cells through direct reduction of endothelial P-selectin expression. Taken together, our data provide evidence that JAK2V617F-expressing endothelial cells promote thrombosis through induction of endothelial P-selectin expression, which can be reversed by hydroxyurea. Our findings increase our understanding of thrombosis in patients with myeloproliferative neoplasms, at least those with JAK2V617F-positive endothelial cells, and highlight a new role for hydroxyurea. This novel finding provides the proof of concept that an acquired genetic mutation can affect the pro-thrombotic nature of endothelial cells, suggesting that other mutations in endothelial cells could be causal in thrombotic disorders of unknown cause, which account for 50% of recurrent venous thromboses