465 research outputs found

    Development of Novel DNA Cleavage Systems Based on Copper Complexes. Synthesis and Characterisation of Cu(II) Complexes of Hydroxyflavones

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    Copper(II) complexes of several hydroxyflavones were prepared and characterised through their physico-chemical properties. The nuclease activity of three synthesised complexes is reported. These copper(II) complexes present more nuclease activity than the ligands and the copper(II) ion

    Double quantum dot with tunable coupling in an enhancement-mode silicon metal-oxide semiconductor device with lateral geometry

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    We present transport measurements of a tunable silicon metal-oxide-semiconductor double quantum dot device with lateral geometry. Experimentally extracted gate-to-dot capacitances show that the device is largely symmetric under the gate voltages applied. Intriguingly, these gate voltages themselves are not symmetric. Comparison with numerical simulations indicates that the applied gate voltages serve to offset an intrinsic asymmetry in the physical device. We also show a transition from a large single dot to two well isolated coupled dots, where the central gate of the device is used to controllably tune the interdot coupling.Comment: 4 pages, 3 figures, to be published in Applied Physics Letter

    Effect of ambient temperature variations on an indigenous microalgae-nitrifying bacteria culture dominated by Chlorella

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    [EN] Two outdoor photobioreactors were operated to evaluate the effect of variable ambient temperature on an indigenous microalgae-nitrifying bacteria culture dominated by Chlorella. Four experiments were carried out in different seasons, maintaining the temperature-controlled PBR at around 25¿°C (by either heating or cooling), while the temperature in the non-temperature-controlled PBR was allowed to vary with the ambient conditions. Temperatures in the range of 15¿30¿°C had no significant effect on the microalgae cultivation performance. However, when the temperature rose to 30¿35¿°C microalgae viability was significantly reduced. Sudden temperature rises triggered AOB growth in the indigenous microalgae culture, which worsened microalgae performance, especially when AOB activity made the system ammonium-limited. Microalgae activity could be recovered after a short temperature peak over 30¿°C once the temperature dropped, but stopped when the temperature was maintained around 28¿30¿°C for several days.This research work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO, Projects CTM2014-54980-C2-1-R and CTM2014-54980-C2-2-R) jointly with the European Regional Development Fund (ERDF), both of which are gratefully acknowledged. It also received support from the Spanish Ministry of Education, Culture and Sport via a pre-doctoral FPU fellowship to authors J. González-Camejo (FPU14/05082) and S. Aparicio (FPU/15/02595).Gonzalez-Camejo, J.; Aparicio Antón, SE.; Ruano, M.; Borrás, L.; Barat, R.; Ferrer, J. (2019). Effect of ambient temperature variations on an indigenous microalgae-nitrifying bacteria culture dominated by Chlorella. Bioresource Technology. 290:1-10. https://doi.org/10.1016/j.biortech.2019.121788S11029

    Prácticas de comercialización y consumo en Tandil : El circuito del salame y queso

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    Este trabajo explora los circuitos cortos de comercialización en la ciudad de Tandil (sudeste de la provincia de Buenos Aires), teniendo en cuenta la valorización y las prácticas de compra de los consumidores de productos regionales, particularmente salame y queso. El término circuito corto se relaciona con un consumidor que conoce la procedencia del producto que va a comprar (ya sea por su etiqueta o porque el vendedor se lo comunica o por estar visitando una localidad con trayectoria en productos regionales). Por ello, en este trabajo se caracterizan los comercios especializados en ventas de productos regionales de Tandil y se observan las prácticas de compra venta. En esa interacción del mundo de la compra y la venta, se analizan las percepciones de los consumidores y su construcción de imaginarios y calidad de los quesos y chacinados, en particular, el salame con Denominación de Origen (DO). Si bien, más de la mitad de los consumidores analizados son turistas, todos asocian la calidad de los productos regionales con la producción artesanal y local. La observación en los locales comerciales permitió constatar que co-existen múltiples valorizaciones de productos y formas de comprar.Mesa 25: Economía social solidaria y tercer sector. De la emergencia a la estrategia: más allá del “alivio a la pobreza”Facultad de Humanidades y Ciencias de la Educació

    Prácticas de comercialización y consumo en Tandil : El circuito del salame y queso

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    Este trabajo explora los circuitos cortos de comercialización en la ciudad de Tandil (sudeste de la provincia de Buenos Aires), teniendo en cuenta la valorización y las prácticas de compra de los consumidores de productos regionales, particularmente salame y queso. El término circuito corto se relaciona con un consumidor que conoce la procedencia del producto que va a comprar (ya sea por su etiqueta o porque el vendedor se lo comunica o por estar visitando una localidad con trayectoria en productos regionales). Por ello, en este trabajo se caracterizan los comercios especializados en ventas de productos regionales de Tandil y se observan las prácticas de compra venta. En esa interacción del mundo de la compra y la venta, se analizan las percepciones de los consumidores y su construcción de imaginarios y calidad de los quesos y chacinados, en particular, el salame con Denominación de Origen (DO). Si bien, más de la mitad de los consumidores analizados son turistas, todos asocian la calidad de los productos regionales con la producción artesanal y local. La observación en los locales comerciales permitió constatar que co-existen múltiples valorizaciones de productos y formas de comprar.Mesa 25: Economía social solidaria y tercer sector. De la emergencia a la estrategia: más allá del “alivio a la pobreza”Facultad de Humanidades y Ciencias de la Educació

    Characterization of green composites from biobased epoxy matrices and bio-fillers derived from seashell wastes

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    The seashells, a serious environmental hazard, are composed mainly by calcium carbonate, which can be used as filler in polymer matrix. The main objective of this work is the use of calcium carbonate from seashells as a bio-filler in combination with eco-friendly epoxy matrices thus leading to high renewable contents materials. Previously obtaining calcium carbonate, the seashells were washed and grinded. The powder obtained and the resin was characterized by DSC, TGA, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), and rheology plate-plate. The results show that addition of 30 wt.% of seashell bio-filler increase mechanical properties as flexural modulus (over 50%) and hardness Shore D (over 6%) and thermal properties as an increase around 13% in glass transitions temperature. The results show that the addition of calcium carbonate from seashells is an effective method to increase mechanical properties of bio-composite and to reduce the residue of seashells from industrial production. (C) 2013 Elsevier Ltd. All rights reserved.L. Bernardi would like to thank CNPq, Consejo Nacional de Desenvolvimiento Cientifico y Tecnologico - Brasil for financial support through a scholarship number.Fombuena Borrás, V.; Bernardi, L.; Fenollar Gimeno, OÁ.; Boronat Vitoria, T.; Balart Gimeno, RA. (2014). Characterization of green composites from biobased epoxy matrices and bio-fillers derived from seashell wastes. Materials and Design. 57:168-174. doi:10.1016/j.matdes.2013.12.0321681745

    Mechanical, stress corrosion cracking and crystallographic study on flat components processed by two combined severe plastic deformation techniques

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    Although the current field of application of Al–alloy 7075 (AA7075) is vast, it is still limited due to some drawbacks, especially due to its susceptibility to stress corrosion cracking (SCC). This work aims to evaluate the microstructural, mechanical, and stress corrosion cracking (SCC) behaviors on an AA7075 in flat format deformed by a combination of repetitive corrugation and straightening (RCS) and accumulative roll bonding (ARB) techniques. Four different deformation routes were applied, namely: ARB (A), RCS (R), RCS + ARB (RA) and ARB + RCS (AR). As expected, the efficiency for grain refinement depends on the applied route, in terms of average grain size regarding the initial condition IC): AR > A > RA > R. All conditions resulted in unimodal and widened grain size distributions of micro-, submicro- and nano-metric dimensions. The study of crystallographic orientations showed that route R did not generate any new texture, whereas different preferred orientations were obtained for routes A, RA, and AR. The hardness and three-point bending tests showed an improvement of mechanical strength in the following order: AR > RA > A > R. The cracks per cm2 obtained in the corrosion study indicated that the best SCC resistance was R > A > AR > RA. Based on the above, the best combination of microstructural, mechanical, and SCC properties until one deformation pass was obtained by the single route of the ARB process.Peer ReviewedPostprint (published version

    Repetitive corrugation and straightening effect on the microstructure, crystallographic texture and electrochemical behavior for the Al-7075 alloy

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    Anti-corrosion susceptibility is one of the top criteria for selecting metallic materials for several industrial applications. This work studies the corrosion performance on an Al-7075 alloy obtained by Repetitive Corrugation and Straightening (RCS). This processing method generated a microstructure formed by randomly distributed micro-, submicro-, and nano- metric grain sizes. The samples exhibited a drop in corrosion resistance for a longer duration in the electrolyte and higher deformation. However, the samples processed by RCS showed better electrochemical stability in comparison with the non-deformed condition. The improvement of electrochemical stability could be associated with the particular microstructure generated during the RCS process.Postprint (published version

    Exfoliation syndrome: assembling the puzzle pieces

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    PURPOSE: To summarize various topics and the cutting edge approaches to refine XFS pathogenesis that were discussed at the 21st annual Glaucoma Foundation Think Tank meeting in New York City, Sept. 19-20, 2014. METHODS: The highlights of three categories of talks on cutting edge research in the field were summarized. RESULTS: Exfoliation syndrome (XFS) is a systemic disorder with a substantial ocular burden, including high rates of cataract, cataract surgery complications, glaucoma and retinal vein occlusion. New information about XFS is akin to puzzle pieces that do not quite join together to reveal a clear picture regarding how exfoliation material (XFM) forms. CONCLUSION: Meeting participants concluded that it is unclear how the mild homocysteinemia seen in XFS might contribute to the disarrayed extracellular aggregates characteristic of this syndrome. Lysyl oxidase-like 1 (LOXL1) variants are unequivocally genetic risk factors for XFS but exactly how these variants contribute to the assembly of exfoliation material (XFM) remains unclear. Variants in a new genomic region, CACNA1A associated with XFS, may alter calcium concentrations at the cell surface and facilitate XFM formation but much more work is needed before we can place this new finding in proper context. It is hoped that various animal model and ex vivo systems will emerge that will allow for proper assembly of the puzzle pieces into a coherent picture of XFS pathogenesis. A clear understanding of XFS pathogenesis may lead to 'upstream solutions' to reduce the ocular morbidity produced by XFS
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