Compositon of Tantalum Nitride Thin Films Grown by Low-Energy Nitrogen Implantation: A Factor Analysis Study of the Ta 4f XPS Core Level

Tantalum nitride thin films have been grown by in situ nitrogen implantation of metallic tantalum at room temperature over the energy range of 0.5-5keV. X-ray photoelectron spectroscopy (XPS) and Factor Analysis (FA) have been used to characterise the chemical composition of the films. The number of the different Ta-N phases formed during nitrogen implantation, as well as their spectral shape and concentrations, have been obtained using principal component analysis (PCA) and iterative target transformation factor analysis (ITTFA), without any prior assumptions. According to FA results, the composition of the tantalum nitride films depends on both the ion dose and ion energy, and is mainly formed by a mixture of metallic tantalum, beta-TaN0.05, gamma-Ta2N and cubic/hexagonal TaN phases.Comment: 24 pages, 5 figures submitted to Applied Physics

Nernst-Planck model of photo-triggered, pH-tunable ionic transport through nanopores functionalized with "caged" lysine chains

We describe the fabrication of asymmetric nanopores sensitive to ultraviolet (UV) light, and give a detailed account of the divalent ionic transport through these pores using a theoretical model based on the Nernst-Planck equations. The pore surface is decorated with lysine chains having pH-sensitive (amine and carboxylic acid) moieties that are caged with photo-labile 4,5-dimethoxy- 2-nitrobenzyl (NVOC) groups. The uncharged hydrophobic NVOC groups are removed using UV irradiation, leading to the generation of hydrophilic “uncaged” amphoteric groups on the pore surface. We demonstrate experimentally that polymer membranes containing single pore and arrays of asymmetric nanopores can be employed for the pH-controlled transport of ionic and molecular analytes. Comparison between theory and experiment allows for understanding the individual properties of the phototriggered nanopores, and provides also useful clues for the design and fabrication of multipore membranes to be used in practical applications. © 2013 American Institute of Physics.The authors would like to thank Miguel Ferrandez and Juan Pablo Arranz for assistance in the preparation of the artwork. P. R. and S. M. acknowledge financial support from the Ministerio de Economia y Competitividad (Projects Nos. MAT2009-07747 and MAT2012-32084), the Generalitat Valenciana (Project No. PROMETEO/GV/0069), and FEDER. S.N., M. A., and W. E. gratefully acknowledge financial support by the Beilstein-Institut, Frankfurt/Main, Germany, within the research collaboration NanoBiC, and L. F. and I. A. DFG-CFN Excellence Initiative Project A5.7. The authors thank Dr. Christina Trautmann from GSI (Materials research group) for support with the heavy ion irradiation experiments, and Dr. M. N. Tahir (Mainz University) for fruitful discussions and help in performing the UV light irradiation experiments.Nasir, S.; Ramirez Hoyos, P.; Ali, M.; Ahmed, I.; Fruk, L.; Mafé, S.; Ensinger, W. (2013). Nernst-Planck model of photo-triggered, pH-tunable ionic transport through nanopores functionalized with "caged" lysine chains. Journal of Chemical Physics. 138(3):034709-1-034709-11. doi:10.1063/1.4775811S034709-1034709-111383Healy, K. (2007). Nanopore-based single-molecule DNA analysis. Nanomedicine, 2(4), 459-481. doi:10.2217/17435889.2.4.459Griffiths, J. (2008). The Realm of the Nanopore. Analytical Chemistry, 80(1), 23-27. doi:10.1021/ac085995zJovanovic-Talisman, T., Tetenbaum-Novatt, J., McKenney, A. S., Zilman, A., Peters, R., Rout, M. P., & Chait, B. T. (2008). Artificial nanopores that mimic the transport selectivity of the nuclear pore complex. Nature, 457(7232), 1023-1027. doi:10.1038/nature07600Schoch, R. B., Han, J., & Renaud, P. (2008). Transport phenomena in nanofluidics. 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La metodología de la investigación en Traductología

Empirical research methods in Translation Studies have been used in Spain for a decade. A glimpse of the most recent studies carried out in our country is given, as well as the actual trends in research. A research methodology based on the scientific method is proposed, and a research design to study the acquisition of translation competence in trainees is presented, including three original measuring instruments created for the study: the first instrument measures the translation notions of the students; the second one measures students' performance when faced with translation problems; and the third one measures performance regarding translation errors

Electrodeposition of palladium dotted nickel nanowire networks as a robust self supported methanol electrooxidation catalyst

Mass activity and long term stability are two major issues in current fuel cell catalyst designs. While supported catalysts normally suffer from poor long term stability but show high mass activity, unsupported catalysts tend to perform better in the first point while showing deficits in the latter one. In this study, a facile synthesis route towards self supported metallic electrocatalyst nanoarchitectures with both aspects in mind is outlined. This procedure consists of a palladium seeding step of ion track etched polymer templates followed by a nickel electrodeposition and template dissolution. With this strategy, free standing nickel nanowire networks which contain palladium nanoparticles only in their outer surface are obtained. These networks are tested in anodic half cell measurements for demonstrating their capability of oxidising methanol in alkaline electrolytes. The results from the electrochemical experiments show that this new catalyst is more tolerant towards high methanol concentrations up to 5molL amp; 8722;1 than a commercial carbon supported palladium nanoparticle catalyst and provides a much better long term stability during potential cyclin