334 research outputs found

    Supramolecular Hierarchy among Halogen-Bond Donors

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    Through a combination of structural chemistry, vibrational spectroscopy, and theory, we have systematically examined the relative structure-directing importance of a series of ditopic halogen-bond (XB) donors. The molecular electrostatic potential surfaces of six XB donors were evaluated, which allowed for a charge-based ranking. Each molecule was then co-crystallized with 21 XB acceptors and the results have made it possible to map out the supramolecular landscape describing the competition between I/Br-ethynyl donors, perfluorinated I/Br donors, and I/Br-phenyl based donors. The results offer practical guidelines for synthetic crystal engineering driven by robust and directional halogen bonds. Copyright 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    Halogen and hydrogen bonding in multicomponent crystals of tetrabromo-1H-benzotriazole

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    4,5,6,7-Tetrabromo-1H-benzotriazole (TBBT) is still considered a reference inhibitor of casein kinase II (CK2), a valuable target for anticancer therapy, even though the poor solubility in water of this active pharmaceutical ingredient (API) has prevented its implementation in therapy. We decided to explore the interactions preferentially formed by TBBT in crystalline solids in order to obtain information helpful for the development of new TBBT cocrystals possibly endowed with improved bioavailability. In this paper, we describe the synthesis and the structural characterization of the TBBT methanol solvate and of the TBBT salt with N,N,Nâ\u80²,Nâ\u80²-tetramethylethylenediamine. It is shown that TBBT can give rise to several competing interactions. This API is clearly a good halogen bond (XB) donor, with bromine atoms adjacent to the triazole ring possibly better donors than the two others. TBBT is also a good hydrogen bond (HB) donor, with the triazole hydrogen forming an HB with the acceptor or being transferred to it. Interestingly, one of the triazole nitrogens was proven to be able to work as a hydrogen bond acceptor

    Microsurgery in pediatric upper limb reconstructions: An overview

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    Pediatric microsurgery; Brachial plexus palsy; Upper limbMicrocirugía pediátrica; Parálisis del plexo braquial; Extremidad superiorMicrocirurgia pediàtrica; Paràlisi del plexe braquial; Extremitat superiorThe use of microsurgery has spread during the last decades, making resolvable many complex defects considered hitherto inapproachable. Although the small vessel diameter in children was initially considered a technical limitation, the increase in microsurgical expertise over the past three decades allowed us to manage many pediatric conditions by means of free tissue transfers. Pediatric microsurgery has been shown to be feasible, gaining a prominent place in the treatment of children affected by limb malformations, tumors, nerve injuries, and post-traumatic defects. The aim of this current concepts review is to describe the more frequent pediatric upper limb conditions in which the use of microsurgical reconstructions should be considered in the range of treatment options

    Desde microorganismos a la macrofauna: un estudio comparativo de las comunidades bentónicas profundas y su respuesta a las variables ambientales a lo largo del talud de Malta (mar Jónico)

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    A comparative study for abundance, biomass and diversity was carried out for the prokaryote, meiofauna and macrofauna communities at three depth stations (1200, 1800 and 2100 m) along the Malta Escarpment (Mediterranean Sea). Our investigation showed a two-fold increase with depth in prokaryote abundance; the contribution of prokaryote biomass to the total benthic biomass was predominant at all depths. Bacteria were the dominant prokaryote component and Archaea formed a considerable fraction (20%-30%) of the prokaryote assemblages. The meio- and macrofauna abundances and meiofauna biomass did not decrease significantly with depth but macrofauna biomass did. The α diversity did not follow a clear bathymetric trend for both nematode and macrofauna species. Probably because of the large number of eurybathic nematode genera, nor did the turnover diversity in nematode composition change down the depth gradient. Conversely, for the macrofauna there was a perceptible change in community composition between the shallowest station and the two deeper stations. Food availability affected only the macrobenthic component. The increase in the prokaryote organisms with depth and the dominance of nematodes and macrofauna deposit feeders suggest active grazing by the two benthic components on microbes. This would transfer energy to the higher trophic levels through the microbial compartment.Se llevó a cabo un estudio comparativo de las comunidades de procariotas, meiofauna y macrofauna sobre la abundancia, biomasa y diversidad. Fue realizado en tres estaciones en varias profundidades (1200, 1800 y 2100 m) a lo largo del talud de Malta (mar Mediterráneo). Nuestra investigación muestra que, aumentando la profundidad, la abundancia de procariotas se duplica. La contribución de la biomasa procariota al total de la biomasa bentónica predominó en todas las profundidades. Las bacterias eran la fracción procariota dominante y junto con los Archaea representaban al 20-30% del total de procariotas. Por otra parte la abundancia de la meiofauna y macrofauna y la biomasa de la meiofauna no disminuían significativamente con la profundidad, mientras que la biomasa de la macrofauna sí lo hacía. La diversidad α no siguió una tendencia batimétrica muy clara para las especies de los nematodos y macrofauna. Probablemente debido a la gran abundancia de géneros de nematodos eurybatiales, la tasa derenovación de la diversidad en la composición de nematodos tampoco cambió por el gradiente de profundidad. En cambio, para la macrofauna hubo un cambio apreciable en la composición de la comunidad entre la estación más superficial y las dos estaciones más profundas. La disponibilidad de alimentos afectó sólo al componente macrobentónico. El aumento con la profundidad de los organismos procariotas, el dominio de los nematodos y la macrofauna que se alimenta de los materiales depositados sugieren un medio activo para los dos componentes bentónicos microbianos. Esto daría lugar a una transferencia de energía a niveles tróficos superiores a través del compartimento microbiano
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