160 research outputs found

    Synthesis and structural characterization of a binuclear iridium complex with bridging, bidentate N-heterocyclic carbene coordination of 2, 2 ':6 ', 2''-terpyridine

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    Thermal activation of terpyridine in the presence of an unsaturated Ir(III) fragment stabilized by a hydrotris(pyrazolyl) borate ligand gives rise to mononuclear complex 2 and binuclear 3, in which the polypyridine behaves, respectively, as a mono- or a bi-dentate N-heterocyclic carbene

    A Diels–Alder Reaction Triggered by a [4 + 3] Metallacycloaddition

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    The TpMe2Ir(III) complex 1-OH2 (TpMe2 = hydrotris(3,5-dimethylpyrazolyl)borate), which contains a labile molecule of water and an iridium-bonded alkenyl moiety (−C(R)═C(R)–(R=CO2Me)) as part of a benzo-annulated five-membered iridacycle, reacts readily with the conjugated dienes butadiene and 2,3-dimethylbutadiene to afford the corresponding Diels–Alder products. Experimental and DFT studies are in accordance with an initial [4 + 3] cyclometalation reaction between the diene and the five-coordinated 16-electron organometallic fragment 1 (generated from 1-OH2 by facile water dissociation). The reaction can be extended to a related TpIr(III) complex (Tp = hydrotris(pyrazolyl)borate) that also features a labile ligand (i.e., 2-THF).Ministerio de Economía y Competitividad CTQ2014- 51912-REDCJunta de Andalucía FQM-119, P09-FQM-483

    Catalytic Nitrene Transfer To Alkynes: A Novel and Versatile Route for the Synthesis of Sulfinamides and Isothiazoles

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    A novel transformation is reported for the reaction of terminal or internal alkynes with the nitrene precursor PhI=NTs (Ts=p-toluenesulfonyl) in the presence of catalytic amounts of Tp(Br3)Cu(NCMe) (Tp(Br3)=hydrotris(3,4,5-tribromo-pyrazolylborate). Two products containing an imine functionality have been isolated from the reaction mixtures, identified as sulfinamides and isothiazoles. The former correspond to the formal reduction of the sulfone group into sulfoxide, whereas the latter involves the insertion of an alkyne carbon atom into the aromatic ring of the N-tosyl moiety.Support for this work was provided by the MINECO (CTQ2014-52769-C3-R-1, CTQ2014-57761-R, Severo Ochoa Excellence Accreditation 2014-2018 SEV-2013-0319, Red Intecat CTQ2014-52974-REDC) and by a FPU fellowship (M.R.R.). We thank Prof. Antonio Echavarren for helpful comments and discussions

    Reactivity of TpMe2-containing hydride-iridafurans with alkenes, alkynes, and H2

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    The TpMe2-containing hydride-iridafurans 2a,b (TpMe2 = hydrotris(3,5-dimethylpyrazolyl)borate) cleanly reacted with ethylene to give the bicyclic derivatives 6a,b. Formation of the latter complexes is a reversible process, and it is proposed to occur by an electrocyclic ring closure that takes place between C2H4 and the 16e unsaturated intermediates A, resulting from hydride migration to the α carbon of the metallacycle. Similar reactions were observed with a variety of alkynes RC≡CR (R = H, Ph, CO2Me) and R′C≡CH (R′= CO2Me, Ph, CMe3), with the regioselectivity observed for the latter substrates depending on the nature of R′. In the case of Me3SiC≡CH the structure of an unexpected byproduct indicates that an alkyne–vinylidene rearrangement has taken place on the metal coordination sphere during the reaction, and this observation suggests that in the mechanism of all these coupling processes the corresponding π adducts are active intermediates. Finally, complexes 2a,b reacted with H2 to give products derived from the hydrogenation of their alkenyl arms.Ministerio de Ciencia e Innovación CTQ2010-17476. Consolider Ingenio 2010 CSD 2007-0006Junta de Andalucía FQM-119, P09-FQM-483

    Coordinación entre las asignaturas del área de ingeniería térmica y energía de los grados y el Máster Universitario en Ingeniería Naval y Oceánica de la Universidad Politécnica de Madrid

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    El trabajo que se presenta tiene por objetivo establecer la coordinación existente entre los objetivos y actividades de las asignaturas del área de ingeniería térmica, energía y propulsión del Máster en Ingeniería Naval y Oceánica, y los objetivos y actividades del mismo tipo de asignaturas en los Grados en Ingeniería Marítima y en Arquitectura Naval de la ETSI Navales de la Universidad Politécnica de Madrid. Igualmente, se plantea estudiar la coordinación de estas materias entre sí dentro de los Grados. Pueden mencionarse asignaturas obligatorias tales como Termodinámica, Ingeniería Térmica, Energía y Propulsión, Motores Diésel Marinos, Turbomáquinas Térmicas y Diseño integral de plantas de Energía y Propulsión. Entre las asignaturas optativas se encuentran Refrigeración y Climatización en Buques y Tecnología de las Pilas de Combustible y Energía del Hidrógeno. Para poder coordinar dos especialidades de Grado universitario con campos tan dispares, pero a la vez tan relacionados, con el Máster Universitario que se cursará en ambos casos, se deben exigir unas pautas muy marcadas para no solapar las actividades y/o habilidades necesarias para alcanzar dichas capacidades. De la necesidad de comprender mejor y con mayor exactitud las necesidades de cada uno de los planes de estudios en el área de ingeniería térmica, energía y propulsión, y más concretamente, las relaciones que existen entre ellos, nace este trabajo. Para mejorar la eficacia de la enseñanza de los actuales y futuros alumnos, será fundamental desarrollar, entre otras, una serie de acciones que incluyen un estudio a fondo de los objetivos del Máster y de los Grados en relación con estas materias; el diseño y aplicación de una plantilla de descripción de las asignaturas en Máster y en Grado, que permita la elaboración de árboles de relación entre Máster-Grados; partiendo del Máster que vinculen los objetivos, las competencias generales, específicas y transversales (y el nivel de desarrollo propuesto) y los conocimientos previos; la confección y análisis de encuestas dirigidas a alumnos egresados, profesores y empresas, que emplean a estos alumnos con el fin de evaluar el nivel de consecución de los objetivos planteados. Esto permitirá determinar, en cuanto al área de ingeniería térmica, energía y propulsión, la viabilidad de la consecución de los objetivos del Máster en función de los objetivos planteados en los Grados al identificar vacíos y redundancias en cuanto a los objetivos, las competencias y los conocimientos previos del Máster en relación con los Grados. Con todo ello será posible proponer las modificaciones oportunas, en los casos en los que se consideren necesarias.Los autores desean agradecer a la Universidad Politécnica de Madrid su soporte y ayuda en este trabajo, en el marco del Proyecto de Innovación Educativa IE1415-08002

    FOOT: a new experiment to measure nuclear fragmentation at intermediate energies

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    Summary: Charged particle therapy exploits proton or 12C beams to treat deep-seated solid tumors. Due to the advantageous characteristics of charged particles energy deposition in matter, the maximum of the dose is released to the tumor at the end of the beam range, in the Bragg peak region. However, the beam nuclear interactions with the patient tissues induces fragmentation both of projectile and target nuclei and needs to be carefully taken into account. In proton treatments, target fragmentation produces low energy, short range fragments along all the beam range, which deposit a non negligible dose in the entry channel. In 12C treatments the main concern is represented by long range fragments due to beam fragmentation that release their dose in the healthy tissues beyond the tumor. The FOOT experiment (FragmentatiOn Of Target) of INFN is designed to study these processes, in order to improve the nuclear fragmentation description in next generation Treatment Planning Systems and the treatment plans quality. Target (16O and 12C nuclei) fragmentation induced by –proton beams at therapeutic energies will be studied via an inverse kinematic approach, where 16O and 12C therapeutic beams impinge on graphite and hydrocarbon targets to provide the nuclear fragmentation cross section on hydrogen. Projectile fragmentation of 16O and 12C beams will be explored as well. The FOOT detector includes a magnetic spectrometer for the fragments momentum measurement, a plastic scintillator for ΔE and time of flight measurements and a crystal calorimeter to measure the fragments kinetic energy. These measurements will be combined in order to make an accurate fragment charge and isotopic identification. Keywords: Hadrontherapy, Nuclear fragmentation cross sections, Tracking detectors, Scintillating detector

    Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

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    The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality
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