786 research outputs found

    Chemical Functionalization of Cellulosic Materials — Main Reactions and Applications in the Contaminants Removal of Aqueous Medium

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    The cellulose is the most abundant biopolymer in the world and presents a higher chemical variability for presence of several hydroxyl groups. These hydroxyl groups allow surface modification of biomaterials, with insertion of several chemical groups which change cellulose characteristics. This natural biopolymer and its derivatives have been used a lot as adsorbent, from several contaminants of aqueous medium due to biocompatibility, chemical degradability, and variability. Therefore, this chapter has the objective to review the literature about several cellulose surfaces or cellulosic material (incorporation of carboxymethyl, phosphorus, carboxyl, amines, and sulfur), presenting the main characteristics of reactions and showing its adsorption in application of aqueous medium (metals, dyes, and drugs), locating the main interactions between biomaterial/contaminant

    A Herpetofauna Do Parque Nacional Da Serra Das Confusões, Piauí, Brasil, Com Uma Lista Regional Para Uma área Ecotonal Entre O Cerrado E A Caatinga

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    Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Different physiognomies at Parque Nacional da Serra das Confusões (PNSCo) were intensively sampled aiming to access the distribution pattern of its herpetofauna. Sixty six species were found in the park (47 reptiles and 19 amphibians); the rarefaction curve for lizards, although not fully stabilized in an asymptote, indicates that the sampling effort was enough to reveal most lizard species occurring in the area; and richness estimators recovered values close to observed. For amphibians, the curve shows a weak tendency to stabilization with richness estimators indicating that additional records could be done. Field work carried out at PNSCo has highlighted an unique herpetofauna: five new species were described and there are three candidates as new species. The regional list including Cerrados’s units - Estação Ecológica Serra Geral do Tocantins (EESGT) and Estação Ecológica de Uruçuí-Una (EEUU) with Caatinga’s ones - PNSCo and Parque Nacional da Serra da Capivara (PNSCa), shows a high herpetofaunal diversity (191 species) to the region. The cluster analysis recovered the Cerrados’s units and Caatinga’s ones, in separate clusters evidencing a species turnover between domains, despite its geographical proximity. Thus, although there is widespread fauna throughout region shared by the units, each reserve holds its own faunal identity, harboring a singular assemblage of species. © 2016, Universidade Estadual de Campinas UNICAMP. All rights reserved.1632011/50206-9, FAPESP, Fundação de Amparo Pesquisa do Estado de São Paulo303545/2010-0, CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico565046/2010-1, CNPq, Conselho Nacional de Desenvolvimento Científico e TecnológicoFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

    Comparison of recovery methods for the enumeration of injured Listeria innocua cells under isothermal and non-isothermal treatments

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    This study compares the feature of different media with the combination of selective with non-selective media in a TAL method for recovery of Listeria innocua cells exposed to thermal treatments. Experiments were conducted in broth at constant temperature (52.5 and 65.0 ºC) and pH (4.5 and 7.5) conditions, using NaCl or glycerol to adjust water activity to 0.95. Four different media were used in bacterial cell enumeration: (i) a non-selective medium e TSAYE, (ii) two selective media e TSAYE þ 5%NaCl and Palcam Agar and (iii) TAL medium (consisting of a layer of Palcam Agar overlaid with one of TSAYE). Two food products were used as case studies aiming at comparison of results obtained on selective and TAL media enumeration. Parsley samples were inoculated with L. innocua and subjected to posterior thermal treatments both under isothermal (52.5, 60.0 and 65.0 ºC) and non-isothermal (heating rate of 1.8 ºC/min from 20.0 to 65.0 ºC) conditions. The recovery capability of TAL method was also studied when a pre-cooked frozen food (i.e. meat pockets) was fried (oil temperature of w180 ºC). TAL method proved to be better than Palcam Agar in terms of capability to recover injured cells and was effective in L. innocua enumeration when non-sterile samples were analysed.info:eu-repo/semantics/acceptedVersio

    Nanoindentation study of the interfacial zone between cellulose fiber and cement matrix in extruded composites

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    [EN] The present study shows the application of the nanoindentation technique to evaluate the properties of the cellulose fiber-cement matrix interfacial zone in composites prepared with an auger extruder. The degree of strength of the bond between fiber and matrix is recognized as important variable that influences macro-mechanical properties, such as modulus of rupture and toughness of cement based composites. The nanoindentation measurements showed the highest hardness and elastic modulus in the part inner of the cellulosic fiber after hydration process due to precipitation and re-precipitation of cement hydration products. These results indicate that mineralization of the cellulosic fibers can affect the stress distribution and interfacial bond strength in the cement based composite.The authors acknowledge by financial support provided by Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP, process no 2013/03823-8), Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, process no 3886/2014) and Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq, process no 152069/2016), in Brazil. Special thanks for Fibria and Infibra for providing raw materials the development of this work.Teixeira, R.; Tonoli, G.; Santos, S.; Rayón, E.; Amigó, V.; Savastano, HJ.; Rocco Lahr, F. (2018). Nanoindentation study of the interfacial zone between cellulose fiber and cement matrix in extruded composites. Cement and Concrete Composites. 85:1-8. https://doi.org/10.1016/j.cemconcomp.2017.09.018S188

    Random walk on random walks

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    Analysis and Stochastic

    Will ultrathin CIGS solar cells overtake the champion thin-film cells? Updated SCAPS baseline models reveal main differences between ultrathin and standard CIGS

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    Cu(In,Ga)Se2 (CIGS) solar cells are amongst the best performing thin-film technologies, with the latest performance gains being mainly due to recent years improvements obtained with post-deposition treatments (PDT). Moreover, thinning of the absorber layer down to sub-micrometre values (ultrathin absorbers) is of extreme importance for CIGS to be even more cost-effective and sustainable. However, electrical and optical limitations, such as rear interface recombination and insufficient light absorption, prevent the widespread implementation of ultrathin CIGS devices. The recent electrical CIGS simulation baseline models have failed to keep up with the experimental developments. Here an updated and experimentally based baseline model for electrical simulations in the Solar Cell Capacitor Simulator (SCAPS) software is presented and discussed with the incorporation of the PDT effects and increased optical accuracy with the support from Finite-Difference Time-Domain (FDTD) simulation results. Furthermore, a champion solar cell with an equivalent architecture validates the developed thin-film model. The baseline model is also applied to ultrathin CIGS solar cell devices, validated with the ultrathin champion cell. Ultimately, these ultrathin models pave the way for an ultrathin baseline model. Simulations results reveal that addressing these absorbers' inherent limitations makes it possible to achieve an ultrathin solar cell with at least 21.0% power conversion efficiency, with open-circuit voltage values even higher than the recent thin-film champion cells.This work was supported by the Fundação para a Ciência e Tecno-logia (FCT) grant numbers DFA/BD/7073/2020, DFA/BD/4564/2020, SFRH/BD/146776/2019, IF/00133/2015, UIDB/50025/2020, UIDP/50025/2020, UIDB/04730/2020, and UIDP/04730/2020. The authors want to acknowledge the funding from the project NovaCell (PTDC/ CTM-CTM/28075/2017). The authors also acknowledge the financial support of the project Baterias 2030, with the reference POCI-01-0247-FEDER-046109, co-funded by Operational Programme for Competitiveness and Internationalization (COMPETE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDFinfo:eu-repo/semantics/submittedVersio

    Microorganismos que mejoran el crecimiento de las plantas y la calidad de los suelos. Revisión

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    The present article of revision arise from theory and practical subjects developed during the course “Characterization and contribution of plant growth-promoting microorganisms in the agricultural sustainability” carried out in the Laboratory of Soil Microbiology of the Colombian Corporation of Agricultural Research (Corpoica) located in Mosquera (Cundinamarca), Colombia, in July 2010. This activity is in the framework of the Dimiagri network that includes researchers from Argentina, Brazil, Colombia, Spain, Guatemala, Mexico and Uruguay, gathered in a Coordination Action funded by the Iberoamerican Program of Science and Technology for the Development (Cyted). Aspects inherent to the growth and plant health, root system, the surrounding soil (rhizosphere), microorganisms that system partners and their contribution to sustainable management of soil-plant were analyzed in this work. Topics related to the microbial biodiversity and its effect on soil quality; nutrient cycling in the soil by microbiological activity; the importance of microorganisms in plant growthpromotion and their biotechnological application as an alternative to favor sustainability and soil quality were presented. The aim of this review is to show important concepts related to the soil-plant-microorganism system, which will allow to achieve the general objective: to mitigate the negative environmental impact due to the excessive use of chemical products on agricultural crops by using plant growth-promoting microorganisms, including bacteria and beneficial fungi associated to plant roots.El presente artículo surge de la revisión de la teoría y temas prácticos desarrollados durante el curso”Caracterización y contribución de las plantas que promueven el crecimiento de microorganismos en la sostenibilidad de la agricultura”, llevado a cabo en el Laboratorio de Microbiología de Suelos de la Corporación Colombiana de Investigación Agropecuaria (Corpoica), ubicado en Mosquera (Cundinamarca), Colombia, en julio de 2010. Esta actividad fue desarrollada en el marco de la Red Dimiagri que incluye a investigadores de Argentina, Brasil, Colombia, España, Guatemala, México y Uruguay, reunidos en una acción de coordinación financiada por el Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo (Cyted). Los aspectos inherentes al crecimiento y la sanidad vegetal, el sistema radical, el suelo circundante (rizósfera), los microorganismos asociados en ese sistema y su contribución al manejo sustentable del complejo suelo-planta fueron analizados en este trabajo. También se abordan temas como la biodiversidad microbiana y su efecto en la calidad del suelo; el ciclado de nutrientes del suelo por acción microbiológica; la importancia de los microorganismos en la promoción del crecimiento vegetal y su utilización biotecnológica como alternativa para favorecer la sustentabilidad y calidad de los suelos. Además se pretende interiorizar en los conceptos relacionados con el consorcio suelo-planta-microorganismo y el objetivo de mitigar el impacto ambiental negativo causado por el uso excesivo de insumos químicos en los cultivos agrícolas, mediante la utilización de microorganismos promotores del crecimiento vegetal, que incluyen tanto a bacterias como a hongos benéficos asociados con las raíces de las plantas.   &nbsp
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