150 research outputs found

    Thin films composed of Ag nanoclusters dispersed in TiO2: Influence of composition and thermal annealing on the microstructure and physical responses

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    Noble metal powders containing gold and silver have been used for many centuries, providing different colours in the windows of the medieval cathedrals and in ancient Roman glasses. Nowadays, the interest in nanocomposite materials containing noble nanoparticles embedded in dielectric matrices is related with their potential use for a wide range of advanced technological applications. They have been proposed for environmental and biological sensing, tailoring colour of functional coatings, or for surface enhanced Raman spectroscopy. Most of these applications rely on the so-called localised surface plasmon resonance absorption, which is governed by the type of the noble metal nanoparticles, their distribution, size and shape and as well as of the dielectric characteristics of the host matrix. The aim of this work is to study the influence of the composition and thermal annealing on the morphological and structural changes of thin films composed of Ag metal clusters embedded in a dielectric TiO2 matrix. Since changes in size, shape and distribution of the clusters are fundamental parameters for tailoring the properties of plasmonic materials, a set of films with different Ag concentrations was prepared. The optical properties and the thermal behaviour of the films were correlated with the structural and morphological changes promoted by annealing. The films were deposited by DC magnetron sputtering and in order to promote the clustering of the Ag nanoparticles the as-deposited samples were subjected to an in-air annealing protocol. It was demonstrated that the clustering of metallic Ag affects the optical response spectrum and the thermal behaviour of the films.This research was sponsored by FEDER funds through the COMPETE program (Programa Operacional Factores de Competitividade) and by FCT (Fundação para a Ciência e a Tecnologia), under the projects PEST-C/FIS/UI607/2013 and PEst-C/EME/UI0285/2013. The authors also acknowledge the financial support by the project Nano4color – Design and develop a new generation of color PVD coatings for decorative applications (FP7 EC R4SME Project No. 315286). J. Borges also acknowledges the support by the European social fund within the framework of realising the project “Support of inter-sectoral mobility and quality enhancement of research teams at Czech Technical University in Prague”, CZ.1.07/2.3.00/30.0034. C. Lopes acknowledges FCT for the PhD grant SFRH/BD/103373/2014. F.M. Couto acknowledges CAPES – Foundation, Ministry of Education of Brazil, Brasília – DF 70040-20, Brazil, funding by stage sandwich doctorate, through PDSE – Doctoral Program Sandwich

    Trabalho, terra e geração de renda em três décadas de reflorestamentos no alto Jequitinhonha.

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    A partir dos anos 1970, as chapadas do Alto Jequitinhonha, localizadas no nordeste de Minas Gerais, até então áreas de uso comum de agricultores familiares, foram plantadas com eucaliptos. O objetivo deste artigo é comparar os efeitos do reflorestamento sobre a estrutura fundiária, valor da produção agrícola e ocupação rural com os efeitos da produção agrícola familiar sobre essas mesmas variáveis na microrregião homogênea de Capelinha, no Alto Jequitinhonha. Tal microrregião foi escolhida para o estudo por ser a área de maior concentração de eucaliptais da região. Foram utilizados dados secundários dos Censos do IBGE para os anos de 1970, 1980, 1985 e 1996, além de dados secundários de pesquisas realizadas sobre a região em questão, incluindo entrevistas com dirigentes de empresas e lideranças sindicais. O artigo conclui que, em trinta anos, o reflorestamento concentrou terras e criou um número reduzido de empregos; a agricultura familiar, ao contrário, teve suas áreas de terras comprimidas e super-exploradas em decorrência da perda das chapadas, mas continuou sendo a principal responsável pela geração de ocupações e rendas na região

    Proficiency testing of virus diagnostics based on bioinformatics analysis of simulated in silico high-throughput sequencing data sets

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    Quality management and independent assessment of high-throughput sequencing-based virus diagnostics have not yet been established as a mandatory approach for ensuring comparable results. The sensitivity and specificity of viral high-throughput sequence data analysis are highly affected by bioinformatics processing using publicly available and custom tools and databases and thus differ widely between individuals and institutions. Here we present the results of the COMPARE [Collaborative Management Platform for Detection and Analyses of (Re-) emerging and Foodborne Outbreaks in Europe] in silico virus proficiency test. An artificial, simulated in silico data set of Illumina HiSeq sequences was provided to 13 different European institutes for bioinformatics analysis to identify viral pathogens in high-throughput sequence data. Comparison of the participants’ analyses shows that the use of different tools, programs, and databases for bioinformatics analyses can impact the correct identification of viral sequences from a simple data set. The identification of slightly mutated and highly divergent virus genomes has been shown to be most challenging. Furthermore, the interpretation of the results, together with a fictitious case report, by the participants showed that in addition to the bioinformatics analysis, the virological evaluation of the results can be important in clinical settings. External quality assessment and proficiency testing should become an important part of validating high-throughput sequencing-based virus diagnostics and could improve the harmonization, comparability, and reproducibility of results. There is a need for the establishment of international proficiency testing, like that established for conventional laboratory tests such as PCR, for bioinformatics pipelines and the interpretation of such results

    Multidisciplinary Scientific Cruises for Environmental Characterization in the Santos Basin – Methods and Sampling Design

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    The Santos Basin (SB) is the main petroliferous basin in the Brazilian continental margin and one of the most studied marine areas in Brazil. However, historical data suggest that new efforts should be carried out to acquire quantitative biological data, especially in the deep sea, to establish the baseline of essential ocean variables in different ecosystems for future monitoring programs. The Brazilian energy company Petrobras planned and executed 24 oceanographic cruises over a period of 2 years to assess the benthic (SANSED cruise) and pelagic (SANAGU cruise) systems of the SB (356 days at sea in 2019 and 2021/2022). These efforts were part of the Santos Project, which comprised a comprehensive environmental study aimed at investigating benthic and pelagic variables to characterize ecology, biogeochemistry, thermohaline properties of water masses, and ocean circulation patterns, geomorphology, and sedimentology, as well as organic and inorganic chemistry. Here we present the detailed sampling designs and the field methods employed on board, during the SB scientific cruises. All sampling protocols were based on standardized approaches. For the benthos analyses, triplicate sediment samples were performed using a GOMEX-type box corer (0.25 m²) or a large modified Van Veen grab (0.75 m²) at 100 stations ranging from 25 to 2400 m depth. At each station, 25 geochemical and physico-chemical parameters were analyzed in addition to micro-, meio-, and macrofauna and living foraminifera samples. For the pelagic system, 60 stations were selected to investigate the plankton community, ranging in size from pico- to macroplankton, through vertical, horizontal, and oblique net hauls (20, 200, and 500 μm mesh size), as well as 25 biogeochemical parameters collected with an aid of a CTD-rosette sampler. Part of this scientific information also serves the Regional Environmental Characterization Project (PCR-BS) in support of Petrobras’ Santos Basin drilling licensing process led by the Brazilian Environmental Agency – IBAMA. This project contributes to the sustainable development of the SB, in line with the guidelines of the United Nations Decade of Ocean Science for Sustainable Development

    Intoxicação aguda com sementes de Crotalaria spectabilis (Leg. Papilionoideae) em suínos

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    Relata-se necrose hepatocelular em suínos após consumo de ração que continha grãos de sorgo-granífero (Sorghum bicolor) acidentalmente contaminado com sementes de Crotalaria spectabilis. Morreram 76 suínos em quatro propriedades no município de Juscimeira, MT. Os sinais clínicos iniciaram-se 24-48 horas após o consumo da ração contaminada e foram caracterizados por depressão, letargia, apatia, inapetência, vômito, mucosas ictéricas ou pálidas, ascite, decúbito esternal, decúbito lateral com movimentos de pedalagem e convulsões, a evolução clínica foi de 48-60 horas seguida de morte. As Principais alterações macroscópicas foram fígado aumentado de tamanho com evidenciação do padrão lobular, ascite e hidrotórax com líquido de coloração amarelo avermelhado contendo filamentos com aspecto de fibrina, linfonodos aumentados e edema pulmonar interlobular. A doença foi reproduzida utilizando-se 16 suínos divididos em seis grupos que receberam sementes de C. spectabilis em diferentes doses. Necrose hepatocelular ocorreu em sete suínos, sendo dois que receberam doses diárias 2,5g/kg e cinco que receberam doses únicas de 5,0 e 9,5g/kg. Dez doses diárias de 0,5 e 1,25g/kg causaram fibrose hepática
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