1,497 research outputs found

    Chiral transition-metal complexes as Brønsted-acid catalysts for the asymmetric Friedel-Crafts hydroxyalkylation of indoles.

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    The Friedel-Crafts reaction between 3,3,3-trifluoropyruvates and indoles is efficiently catalysed by the iridium complex [(η5-C 5Me5)Ir{(R)-Prophos}(H2O)][SbF 6]2 (1) with up to 84% ee. Experimental data and theoretical calculations support a mechanism involving the Brønsted-acid activation of the pyruvate carbonyl by the protons of the coordinated water molecule in 1. Water is not dissociated during the process and, therefore, the catalytic reaction occurs with no direct interaction between the substrates and the metal. This journal is © the Partner Organisations 2014.The authors acknowledge the Ministerio de Economía y Competitividad (MINECO, Grants CTQ2006-03030/BQU, CTQ2009-10303/BQU, CTQ2011-27033 and Consolider Ingenio 2010 CSD2006-003), Gobierno de Aragón (Grupo Consolidado: Catálisis Homogénea Enantioselectiva), Generalitat de Catalunya (2009SGR0259) and the ICIQ foundation for financial support. A. S. and R. R. acknowledge MINECO for predoctoral fellowships. S. D.-G. acknowledges MINECO for a “Torres Quevedo” contract.Peer Reviewe

    Representative-area approach to define blast-induced ground vibrations-damage prevention criterion abacus

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    Peer ReviewedObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura::9.2 - Promoure una industrialització inclusiva i sostenible i, a tot tardar el 2030, augmentar de manera significativa la contribució de la indústria a l’ocupació i al producte interior brut, d’acord amb les circumstàncies nacionals, i duplicar aquesta contribució als països menys avançatsObjectius de Desenvolupament Sostenible::12 - Producció i Consum ResponsablesObjectius de Desenvolupament Sostenible::12 - Producció i Consum Responsables::12.2 - Per a 2030, assolir la gestió sostenible i l’ús eficient dels recursos naturalsPostprint (published version

    Nuevos datos sobre la estructura general del Carbonífero en el Horst de La Camocha (Gijón, Asturias).

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    Una reciente campaña de investigación geológico-minera, mediante la realización de transversales de reconocimiento, sondeos de superficie e interior y perfiles sísmicos de reflexión, ha permitido profundizar en el conocimiento de la estructura del Carbonífero en el entorno de Mina La Camocha. En esta zona, al sur de Gijón, los materiales carboníferos, cubiertos por una cobertera permotriásica y jurásica, no afloran. Se precisa el estilo de plegamiento, analizándose y datándose las principales familias de fracturación. El estilo tectónico de los materiales carboníferos productivos no aflorantes, se ilustra mediante varios de los nuevos cortes obtenidos

    Flow cytometric cell cycle analysis of cultured brown bear fibroblast cells

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    The aim of this study was to assess by flow cytometry the cell cycle of brown bear fibroblast cells cultured under different growth conditions. Skin biopsies were taken in Cantabria (Spain) from a live, anaesthetized brown bear. DNA analysis was performed by flow cytometry following cell DNA staining with propidium iodide. Serum starvation increased (P < 0.01) the percentage of G0/G1 phase cells (92.7 0.86) as compared to cycling cells (39.7 0.86) or cells cultured to confluency (87.3 0.86). DMSO included for 48 h in the culture significantly increased (P < 0.01) the percentage of G0/G1 phase of the cell cycle at all concentrations used and decreased percentages of S phase in a dose-dependent fashion. Roscovitine increased the G0/G1 phase of the cell cycle (P < 0.01) at 15 mM concentration. Interestingly, the G2/M stage significantly increased at 30 and 50 mM compared to the control and 15 mM (P < 0.02). The cell cycle of brown bear adult fibroblast cells can be successfully synchronized under a variety of culture conditions

    Caracterización de los parámetros hidráulicos de la cobertera pérmica en el Horst del yacimiento carbonífero de Mina «La Camocha».

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    En la cobertera pérmica existente sobre el yacimiento carbonífero actualmente en explotación por Mina La Camocha, S. A., se localiza un acuífero multicapa con varios niveles claramente diferenciados. Por medio de diversas técnicas de estudio, se ha tratado de determinar los parámetros hidráulicos de estos materiales en varias localidades próximas a Gijón, con el fin de elaborar un esquema de funcionamiento hidráulico y estimar la posible influencia de este acuífero en las labores de explotación

    The kinematics of the quadrupolar nebula M1-75 and the identification of its central star

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    The link between the shaping of bipolar planetary nebulae and their central stars is still poorly understood. The kinematics and shaping of the multipolar nebula M 1-75 are hereby investigated, and the location and nature of its central star are briefly discussed. Fabry-Perot data from GHaFAS on the WHT sampling the Doppler shift of the [N II] 658.3 nm line are used to study the dynamics of the nebula, by means of a detailed 3-D spatio-kinematical model. Multi-wavelength images and spectra from the WFC and IDS on the INT, and from ACAM on the WHT, allowed us to constrain the parameters of the central star. The two pairs of lobes, angularly separated by ~22 degrees, were ejected simultaneously approx. ~3500-5000 years ago, at the adopted distance range from 3.5 to 5.0 kpc. The larger lobes show evidence of a slight degree of point symmetry. The shaping of the nebula could be explained by wind interaction in a system consisting of a post-AGB star surrounded by a disc warped by radiative instabilities. This requires the system to be a close binary or a single star which engulfed a planet as it died. On the other hand, we present broad- and narrow-band images and a low S/N optical spectrum of the highly-reddened, previously unnoticed star which is likely the nebular progenitor. Its estimated V-I colour allows us to derive a rough estimate of the parameters and nature of the central star.Comment: 8 pages, 6 figures, accepted for publication in Astronomy & Astrophysic

    Obtención de modelos urbanos tridimensionales

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    The use of 3D urban models extends increasingly to a broader range of areas and applications, but its use as a standard tool in the process of realization of the architectural and urban design is limited by the slow pace of the generation processes of models and the derived high cost of realization and maintenance of the models. That is why we find that its use, the size of the project permitting, often framed in purposes of visualization in the final stage. The authors of this paper have developed a methodology for the automation of the process of generation of these city models, cut time and costs, and that will allow a greater generalization of its use.El uso de modelos urbanos 3D se extiende cada vez a una mayor diversidad de áreas y aplicaciones, pero su utilización como una herramienta habitual dentro del proceso de realización del proyecto arquitectónico y urbanístico se ve limitada por la lentitud de los procesos de generación de los modelos y el alto coste de realización y mantenimiento de los mismos. Su uso, si el alcance del proyecto lo permite, suele estar encuadrado en propósitos de visualización en la etapa final. Los autores de este trabajo han desarrollado una metodología para la automatización del proceso de generación de estos modelos de ciudad, que reduce tiempos y costes, y que permitirá una mayor generalización de su uso

    Spin-orbit torque from the introduction of Cu interlayers in Pt/Cu/Co/Pt nanolayered structures for spintronic devices

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    Spin currents can modify the magnetic state of ferromagnetic ultrathin films through spin-orbit torque. They may be generated by means of spin-orbit interactions by either bulk or interfacial phenomena. Electrical transport measurements reveal a 6-fold increase of the spin-orbit torque accompanied by a drastic reduction of the spin Hall magnetoresistance upon the introduction of an ultrathin Cu interlayer in a Pt/Cu/Co/Pt structure with perpendicular magnetic anisotropy. We analyze the dependence of the spin Hall magnetoresistance with the thickness of the interlayer, ranging from 0.5 to 15 nm, in the frame of a drift diffusion model that provides information on the expected spin currents and spin accumulations in the system. The results demonstrate that the major responsibility of both effects is spin memory loss at the interface. The enhancement of the spin-orbit torque when introducing an interlayer opens the possibility to design more efficient spintronic devices based on materials that are cheap and abundant such as copper. More specifically, spin-orbit torque magnetic random access memories and spin logic devices could benefit from the spin-orbit torque enhancement and cheaper material usage presented in this study
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