1,259 research outputs found

    Understanding Nanopore Window Distortions in the Reversible Molecular Valve Zeolite RHO

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    Molecular valves are becoming popular for potential biomedical applications. However, little is known concerning their performance in energy and environmental areas. Zeolite RHO shows unique pore deformations upon changes in hydration, cation siting, cation type, or temperature-pressure conditions. By varying the level of distortion of double eight-rings, it is possible to control the adsorption properties, which confer a molecular valve behavior to this material. We have employed interatomic potentials-based simulations to obtain a detailed atomistic view of the structural distortion mechanisms of zeolite RHO, in contrast with the averaged and space group restricted information provided by diffraction studies. We have modeled four aluminosilicate structures, containing Li+^+, Na+^+, K+^+, Ca2+^{2+}, and Sr2+^{2+} cations. The distortions of the three different zeolite rings are coupled, and the six- and eight-membered rings are largely flexible. A large dependence on the polarizing power of the extra-framework cations and with the loading of water has been found for the minimum aperture of the eight-membered rings that control the nanovalve effect. The calculated energy barriers for moving the cations across the eight-membered rings are very high, which explains the experimentally observed slow kinetics of the phase transition as well as the appearance of metastable phases

    Effect of Plant Growth-Promoting Rhizobacteria on Salicornia ramosissima Seed Germination under Salinity, CO2 and Temperature Stress

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    In a scenario of climate change and growing population, halophyte root microbiota interactions may be a sustainable solution to improve alternative crop production while combating abiotic stress. In this work, seeds of the cash crop halophyte Salicornia ramosissima were inoculated with five different plant growth-promoting rhizobacteria consortia, isolated from the rhizosphere of five halophytes in southwestern Spain salt marshes. For the first time, we recorded seed germination response to three interactive abiotic stressors, CO2 (400 and 700 ppm), temperature (25 and 29 ℃) and salinity (171, 510 and 1030 mM NaCl), all of them related to climate change. Salinity played a decisive role, as no significant differences were registered between treatments at 171 mM NaCl and no germination took place at 1030 mM NaCl. At 510 mM NaCl, one rhizobacterial consortium improved seed parameters notably, increasing up to 114% germination percentage and 65% seedlings biomass. These first findings encourage us to think that cash crop halophytes like S. ramosissima and halophyte root microbiota may be valuable resources for human or animal feeding in a future climate reality.Ministerio de Economía y Competitividad (CGL2016-75550-R)Ministerio de Educación, Cultura y Deporte (FPU014/03987

    Contested discourses in social tourism:A relational political economy perspective

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    Social tourism initiatives often have economic as well as objectives, particularly national schemes such as the Spanish IMSERSO programme, designed to stimulate off-season tourism in mass coastal tourism destinations. Yet, there is little evidence of how such schemes responded to crises or that explores the effects on the tourism industry actors responsible for programme delivery. This article applies a relational political economy approach to assess the contested discourses surrounding the governance of the scheme. We examine the evolution of the IMSERSO programme longitudinally following the global financial crisis and up until the COVID-19 pandemic to assess the relational dynamics at play social tourism governance on destination stakeholders, outlining implications for social tourism policies internationally

    BiblogTecarios: el poder de las conexiones y del crowdsourcing

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    BiblogTecarios (“blogging librarians”) was created with a clear objective: to offer its members the possibility of having a platform to publish their knowledge, concerns and opinions about their professional sector, that of Information and Documentation. Since its beginnings it has been clear that the purpose of the project was not intended to allow a few to publish each day, but rather that the more people participating in the project, the greater variety of topics could be discussed. Now that BiblogTecarios has 40 blogs, communication tools are essential for the proper functioning of the website, as well as the desire to work on a joint (collaborative and cooperative) project. Crowdsourcing, or the collective intelligence of its members, helped this project to grow; personal connections and collective work are the key pillars for its continued growth. BiblogTecarios connects people: it is crowdsourcing

    2D and 3D Immobilization of Carbon Nanomaterials into PEDOT via Electropolymerization of a Functional Bis-EDOT Monomer

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    Carbon nanomaterials (CNMs) and conjugated polymers (CPs) are actively investigated in applications such as optics, catalysis, solar cells, and tissue engineering. Generally, CNMs are implemented in devices where the relationship between the active elements and the micro and nanostructure has a crucial role. However, they present some limitations related to solubility, processibility and release or degradability that affect their manufacturing. CPs, such as poly(3,4-ethylenedioxythiophene) (PEDOT) or derivatives can hide this limitation by electrodeposition onto an electrode. In this work we have explored two different CNMs immobilization methods in 2D and 3D structures. First, CNM/CP hybrid 2D films with enhanced electrochemical properties have been developed using bis-malonyl PEDOT and fullerene C60. The resulting 2D films nanoparticulate present novel electrochromic properties. Secondly, 3D porous self-standing scaffolds were prepared, containing carbon nanotubes and PEDOT by using the same bis-EDOT co-monomer, which show porosity and topography dependence on the composition. This article shows the validity of electropolymerization to obtain 2D and 3D materials including different carbon nanomaterials and conductive polymers.This research was funded by the Spanish Ministry of Economy and Competitiveness MINECO (project CTQ2016-76721-R), the University of Trieste, Diputación Foral de Gipuzkoa program Red (101/16), the European Commission (H2020-MSCA-RISE-2016, grant agreement no. 734381, acronym CARBO-IMmap) and ELKARTEK bmG2017 (ref: Elkartek KK-2017/00008, BOPV resolution: 8 Feb 2018). M.P., as the recipient of the AXA Chair, is grateful to the AXA Research Fund for financial support. This work was performed under the Maria de Maeztu Units of Excellence Program from the Spanish State Research Agency Grant no. MDM-2017-0720. N.A. has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 753293, acronym NanoBEAT

    Safe Cultivation of Medicago sativa in Metal-Polluted Soils from Semi-Arid Regions Assisted by Heatand Metallo-Resistant PGPR

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    Soil contamination with heavy metals is a constraint for plant establishment and development for which phytoremediation may be a solution, since rhizobacteria may alleviate plant stress under these conditions. A greenhouse experiment was conducted to elucidate the effect of toxic metals on growth, the activities of ROS (reactive oxygen species)-scavenging enzymes, and gene expression of Medicago sativa grown under different metal and/or inoculation treatments. The results showed that, besides reducing biomass, heavy metals negatively affected physiological parameters such as chlorophyll fluorescence and gas exchange, while increasing ROS-scavenging enzyme activities. Inoculation of M. sativa with a bacterial consortium of heat- and metallo-resistant bacteria alleviated metal stress, as deduced from the improvement of growth, lower levels of antioxidant enzymes, and increased physiological parameters. The bacteria were able to effectively colonize and form biofilms onto the roots of plants cultivated in the presence of metals, as observed by scanning electron microscopy. Results also evidenced the important role of glutathione reductase (GR), phytochelatin synthase (PCS), and metal transporter NRAMP1 genes as pathways for metal stress management, whereas the gene coding for cytochrome P450 (CP450) seemed to be regulated by the presence of the bacteria. These outcomes showed that the interaction of metal-resistant rhizobacteria/legumes can be used as an instrument to remediate metal-contaminated soils, while cultivation of inoculated legumes on these soils is still safe for animal grazing, since inoculation with bacteria diminished the concentrations of heavy metals accumulated in the aboveground parts of the plants to below toxic levelsMarruecos. Centre National pour la Recherche Scientifique et Technique (CNRST)-España, Ministerio de Economía y Competitividad (MINECO)-PPR2 /2016/42Unión Europea (FEDER)-CGL2016-75550-

    Low-loss inverted taper edge coupler in silicon nitride

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    "This paper is a postprint of a paper submitted to and accepted for publication in IET Optoelectronics and is subject to Institution of Engineering and Technology Copyright. The copy of record is available at IET Digital Library"[EN] An inverted lateral taper with one vertical discrete step was designed for a medium confinement silicon nitride waveguide platform in the C-band, as a chip edge coupler, with a predicted insertion loss of 0.58¿dB. The design is supported by an extensive study to evaluate the impact of fabrication process variations on the performance of such a coupler. The device was manufactured and measured, showing an insertion loss of 1.47 dB, which was traced back to fabrication process variations as cross-checked with simulations. To the authors¿ knowledge, the reported edge coupler is the shortest and among the best performing found for silicon nitride platforms.The authors acknowledge financial support through projects TEC2015-69787-REDT PIC4TB, TEC2016-80385-P SINXPECT, TEC2014-54449-C3-1-R, GVA PROMETEO 2017/103, EC H2020-ICT-27-2015 PICs4all CSA 68777.Fernández-Vicente, J.; Baños Lopez, R.; Doménech Gómez, JD.; Domínguez-Horna, C.; Muñoz Muñoz, P. (2019). Low-loss inverted taper edge coupler in silicon nitride. IET Optoelectronics. 13(2):62-66. https://doi.org/10.1049/iet-opt.2018.5065S6266132Marcatili, E. A. J. (1969). Dielectric Rectangular Waveguide and Directional Coupler for Integrated Optics. Bell System Technical Journal, 48(7), 2071-2102. doi:10.1002/j.1538-7305.1969.tb01166.xMiller, S. E. (1969). Integrated Optics: An Introduction. Bell System Technical Journal, 48(7), 2059-2069. doi:10.1002/j.1538-7305.1969.tb01165.xTomlinson, W. J., & Brackett, C. A. (1987). Telecommunications applications of integrated optics and optoelectronics. Proceedings of the IEEE, 75(11), 1512-1523. doi:10.1109/proc.1987.13912Lim, A. E.-J., Junfeng Song, Qing Fang, Chao Li, Xiaoguang Tu, Ning Duan, … Tsung-Yang Liow. (2014). Review of Silicon Photonics Foundry Efforts. IEEE Journal of Selected Topics in Quantum Electronics, 20(4), 405-416. doi:10.1109/jstqe.2013.2293274Smit, M., Leijtens, X., Ambrosius, H., Bente, E., van der Tol, J., Smalbrugge, B., … van Veldhoven, R. (2014). An introduction to InP-based generic integration technology. Semiconductor Science and Technology, 29(8), 083001. doi:10.1088/0268-1242/29/8/083001Taillaert, D., Bogaerts, W., Bienstman, P., Krauss, T. F., Van Daele, P., Moerman, I., … Baets, R. (2002). An out-of-plane grating coupler for efficient butt-coupling between compact planar waveguides and single-mode fibers. IEEE Journal of Quantum Electronics, 38(7), 949-955. doi:10.1109/jqe.2002.1017613Dillon, T., Murakowski, J., Shi, S., & Prather, D. (2008). Fiber-to-waveguide coupler based on the parabolic reflector. Optics Letters, 33(9), 896. doi:10.1364/ol.33.000896Li, H., Cao, Z., Lu, H., & Shen, Q. (2003). Free-space coupling of a light beam into a symmetrical metal-cladding optical waveguide. Applied Physics Letters, 83(14), 2757-2759. doi:10.1063/1.1616205Cardenas, J., Poitras, C. B., Luke, K., Luo, L.-W., Morton, P. A., & Lipson, M. (2014). High Coupling Efficiency Etched Facet Tapers in Silicon Waveguides. IEEE Photonics Technology Letters, 26(23), 2380-2382. doi:10.1109/lpt.2014.2357177Shiraishi, K., Yoda, H., Ohshima, A., Ikedo, H., & Tsai, C. S. (2007). A silicon-based spot-size converter between single-mode fibers and Si-wire waveguides using cascaded tapers. Applied Physics Letters, 91(14), 141120. doi:10.1063/1.2795337Tao, H., Song, J., Fang, Q., Yu, M., Lo, G., & Kwong, D. (2008). Improving coupling efficiency of fiber-waveguide coupling with a double-tip coupler. Optics Express, 16(25), 20803. doi:10.1364/oe.16.020803Muñoz, P., Micó, G., Bru, L., Pastor, D., Pérez, D., Doménech, J., … Domínguez, C. (2017). Silicon Nitride Photonic Integration Platforms for Visible, Near-Infrared and Mid-Infrared Applications. Sensors, 17(9), 2088. doi:10.3390/s17092088Papes, M., Cheben, P., Benedikovic, D., Schmid, J. H., Pond, J., Halir, R., … Vašinek, V. (2016). Fiber-chip edge coupler with large mode size for silicon photonic wire waveguides. Optics Express, 24(5), 5026. doi:10.1364/oe.24.005026Cheben, P., Schmid, J. H., Wang, S., Xu, D.-X., Vachon, M., Janz, S., … Picard, M.-J. (2015). Broadband polarization independent nanophotonic coupler for silicon waveguides with ultra-high efficiency. Optics Express, 23(17), 22553. doi:10.1364/oe.23.022553Shani, Y., Henry, C. H., Kistler, R. C., Orlowsky, K. J., & Ackerman, D. A. (1989). Efficient coupling of a semiconductor laser to an optical fiber by means of a tapered waveguide on silicon. Applied Physics Letters, 55(23), 2389-2391. doi:10.1063/1.102290Zhuang, L., Marpaung, D., Burla, M., Beeker, W., Leinse, A., & Roeloffzen, C. (2011). Low-loss, high-index-contrast Si_3N_4/SiO_2 optical waveguides for optical delay lines in microwave photonics signal processing. Optics Express, 19(23), 23162. doi:10.1364/oe.19.02316

    El portal web CaCoCu: un canal de cultura contemporánea de las universidades públicas andaluzas

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    The Association of Public Andalusian Universities (AUPA) has displayed a portal that offers diverse multimedia contents related to the cultural events organized by these institutions, with object to spread this rich cultural heritage through Internet. The website, named “CaCoCu”, allows users to access to audio-visual material as audio or video recordings, text documents and image galleries related to different thematic. This paper describes the architecture of the web portal, taking into account the technological and documentary aspects, as well as the functionalities and services that are provided.La Asociación de Universidades Públicas Andaluzas (AUPA) ha presentado un portal que ofrece contenidos multimedia relacionados con los actos culturales organizados por dichas instituciones, con objeto de difundir este rico patrimonio cultural a través de Internet. Este portal, denominado “CaCoCu”, permite el acceso a material audiovisual tal como grabaciones de video y audio, documentos de texto o galerías de imágenes que versa sobre temáticas muy variadas. En este artículo se describe la arquitectura del portal, tanto en el aspecto tecnológico como en el documental, así como las funcionalidades y servicios que se prestan a través del mismo

    Rotation-Based Mixed Formulations for an Elasticity-Poroelasticity Interface Problem

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    In this paper we introduce a new formulation for the stationary poroelasticity equations written using the rotation vector and the total fluid-solid pressure as additional unknowns, and we also write an extension to the elasticity-poroelasticity problem. The transmission conditions are imposed naturally in the weak formulation, and the analysis of the effective governing equations is conducted by an application of Fredholm's alternative. We also propose a monolithically coupled mixed finite element method for the numerical solution of the problem. Its convergence properties are rigorously derived and subsequently confirmed by a set of computational tests that include applications to subsurface flow in reservoirs as well as to dentistry-oriented problems.Fondo Nacional de Desarrollo Científico y Tecnológico/[11160706]/FONDECYT/ChilePrograma Concurso Apoyo a Centros Científicos y Tecnológicos de Excelencia/[AFB170001]/PIA/ChileUCR::Sedes Regionales::Sede de OccidenteUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Matemátic

    Matrimonios concertados y violencia de género: Un estudio de caso con mujeres subsaharianas en Zaragoza

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    El presente trabajo de fin grado realiza un estudio exploratorio sobre la relación de matrimonios concertados con casos de violencia de género en mujeres subsaharianas residentes en Zaragoza
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