197 research outputs found

    Embedding Multi-Wall Carbon Nanotubes as Conductive Nanofiller onto Bi2Te3 Thermoelectric Matrix

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    Thermoelectric Generators (TEGs) are devices that have the ability to directly convert heat into electrical power, or vice-versa, and are being envisaged as one off-the-grid power source. Furthermore, carbon-based materials have been used as a conducting filler to improve several properties in thermoelectric materials. The present work studied the influence on the thermoelectric performance of Bi2Te3 bulk materials by incorporating different concentrations of Multi-Walled Carbon Nanotubes (MWCNT). In order to control and understand the influence of MWCNT dispersion in the nanocomposite, two different production methods (manual grinding and ultrasonication) were carried out and compared. It was verified that a larger dispersion leads to a better outcome for thermoelectric performance. The achieved Seebeck coefficient was up to -162 μV K-1 with a Power Factor of 0.50 μW K-2m-1, for the nanocomposite produced with 11.8 %V of MWCNT. This result demonstrates the ability to increase the thermoelectric performance of Bi2Te3 throughout the addition of MWCNT

    Assessment of habitat suitability for common cockles in the Ria the Aveiro Lagoon under average and projected environmental conditions

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    The common cockle Cerastoderma edule is a widespread bivalve species inhabiting estuarine systems across the North East Atlantic, where it provides several ecosystem services, and represents a valuable fishery resource for local economies. However, anthropogenic pressure and more frequent extreme weather events threaten the resilience of the species. Spatially explicit information on species distribution is critical for the implementation of management and conservation practices. This study assessed the potential distribution of C. edule in the Ria de Aveiro by estimating the habitat suitability using an ensemble approach based on ecological niche modeling and recently developed hydrodynamic and water quality models to forecast both average and projected estuarine conditions. The models were developed for the summer of 2013 and spring of 2019 and potential range shifts in the species distribution were forecasted under projected environmental conditions: high and low estimates of freshwater discharge, a 2 °C increase in water temperature, and the combined effect of low freshwater discharge and increased water temperature. The results suggest that salinity, time of submersion, and current velocity play an important role in the distribution of cockles, and large areas were consistently classified with high habitat suitability. Increased freshwater discharge (both seasons) and low discharge coupled to increased temperature (spring) resulted in large decreases in suitable habitat. Conversely, low freshwater discharges and average (unchanged) temperatures increased the suitable habitat in the outermost regions of the Ria. The spatially explicit information provided contributes to a better understanding of the vulnerability of C. edule in the Ria de Aveiro to extreme weather events (e.g., droughts, river floods) and may support adaptive management strategies of the cockle fishery during these conditions. Moreover, this approach can be transferred to other estuarine ecosystems for which data describing the environmental conditions (e.g., derived from numerical models), and information about species presence are available (including data-poor species).publishe

    Densidade e idade de Phillanthus amarus - genótipo UNICAMP/CPQBA -14 na produtividade de filantina.

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    Avaliou-se o efeito da densidade de plantio e da idade de Phyllanthus amarus CPQBA-14, sobre o teor e produtividade de filantina. O delineamento experimental foi em blocos ao acaso, em esquema fatorial 4 x 6, com cinco repetições, envolvendo 4 tratamentos de densidade de plantio (400.000 pl ha -1; 200.000 pl ha -1; 100.000 pl ha -1 e 66.667,68 pl ha -1) com 6 colheitas (30, 45, 60, 75, 90 e 105 dias após o transplante (DAT)). Os dados foram submetidos a Análise de Variâncias e Regressão (P > 0.001). Para o teor de Filantina, foram observados efeitos significativos e independentes dos tratamentos de idade da planta na colheita e densidade de plantio. O teor de filantina aumentou linearmente com a idade da planta, atingindo o máximo aos 105 DAT, com teor de 11,52 g Kg-1. O adensamento populacional estimado que proporcionou máximo teor de filantina (8.66 g kg-1) foi de 299.860 pl ha-1. A produtividade de filantina apresentou interação significativa entre densidade de plantio e idade da planta na colheita. Observou-se que ao longo do crescimento da planta, os tratamentos com 200 e 400.000 pl ha -1 apresentaram as maiores produtividades de filantina (39,3 e 37,8 kg ha-1) aos 97,12 e 95,17 DAT, respectivamente. Conclui-se que o espaçamento apropriado para o melhor arranjo espacial de cultivo é de 299.860 pl ha-1 para as produtividades de 3974,19 Kg (massa de matéria seca foliar) x 0,00866 kg (teor de filantina) = 34,416 kg ha-1 de filantina, com colheita programada aos 97 DAT

    Preanalytical stability of plasma/serum brain-derived tau

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    INTRODUCTION: We investigated the effects of matrix type and reagent batch changes on diagnostic performances and longitudinal trajectories of brain-derived tau (BD-tau). METHODS: We evaluated (i) Cohort 1: paired EDTA plasma and serum from Alzheimer biomarker-positive older adults versus controls (n = 26); and (ii) Cohort 2: n = 79 acute ischemic stroke patients with 265 longitudinal samples across four time points. RESULTS: In Cohort 1, plasma and serum BD-tau were strongly correlated (rho = 0.96, p 99%) and correlations with CSF total-tau (rho = 0.93–0.94, p < 0.0001). However, absolute concentrations were ∼40% higher in plasma versus serum. In Cohort 2, first and repeated BD-tau measurements showed a near-perfect correlation (rho = 0.96, p < 0.0001), with no significant between-batch concentration differences. In longitudinal analyses, substituting ∼10% of the first-run concentrations for the remeasured values showed overlapping estimated trajectories without significant differences at any time point. DISCUSSION: BD-tau has equivalent diagnostic accuracies, but non-interchangeable absolute concentrations, in plasma versus serum. Furthermore, the analytical robustness is unaffected by batch-to-batch reagent variations. Highlights: Brain-derived tau (BD-tau) is a novel blood-based biomarker that quantifies tau protein of CNS origin. Effects of preanalytical handling procedures on the quality and reproducibility of BD-tau measures are unknown. In two cohorts of n = 105 participants, we compared BD-tau concentrations and diagnostic performances in paired plasma and serum samples, and evaluated impacts of batch-to-batch reagent variations. Paired plasma and serum showed equivalent diagnostic performances to separate amyloid-positive AD from amyloid-negative controls, indicating both can be used independently. Repeated measurements and longitudinal trajectories of plasma BD-tau were unaffected by batch-to-batch reagent variation

    Soil quality, resistance and resilience in traditional agricultural and agroforestry ecosystems in Brazil's semiarid region.

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    Agroforestry represents an alternative to traditional agricultural systems in semiarid regions, since it effectively provides soil coverage and improves the amount and quality of soil organic matter. The sustainability of agricultural systems can be assessed by evaluating soil quality, resistance and resilience. Therefore, this work evaluated soil quality, resistance and resilience under traditional cropping and agroforestry systems. The study took place at an experimental station in Brazil’s semiarid northeast region. Studied land use systems include agrosilvopastoral, silvopastoral and traditional cropping, as well as areas under traditional fallow for six and nine years and unaltered ecosystem. Small trenches were dug randomly to collect soil from three depth increments. Soil Quality (SQ) was assessed using chemical, physical and biological indicators. Based on these indicators, resistance, resilience and soil quality indices were calculated. The index quality of the soil was generated using soil water retention, nutrient supply and biological activity promotion functions. Comparisons of index means indicate that agroforests maintained SQ, while traditional fallow systems resulted in improved SQ up to levels similar to the unaltered ecosystem. Traditional cropping lead to a reduction in SQ, resistance and resilience. Agroforestry systems are sustainable. Fallow can improve soil quality, soil resistance and resilience

    The chemistry of Brazilian Lauraceae XLVI. Notes on Aniba species

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    Aniba affinis, A. cylindriflora and A. mas (Lauraceae) were found to contain respectively benzofuranoid (and a previously unknown bicyclo [3, 2, 1] octanoid) neolignans, 6-styryl-2-pyrones and 6-styryl-4-methoxy-2-pyrones.A madeira do tronco das espécies amazônicas Aniba affinis, A. cylindriflora e A. mas contém respectivamente neolignanas benzofuranoídicas (e uma biciclo [3, 2, 1] octanoídica previamente desconhecida), 6-estiril-2-pironas e 6-estiril-4-metoxi-2-pironas

    Desempenho agronômico de linhagens de arroz irrigado em ensaio de VCU no RS - safra 2011/12.

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    O objetivo deste trabalho foi avaliar o desempenho das linhagens de arroz irrigado em ensaios de VCU do programa de melhoramento genético da Embrapa, almejando possível lançamento de novas cultivares

    Propriedades químicas de um solo sob manejo tradicional em diferentes períodos de pousio no semiárido cearense.

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    Resumo: O semiárido brasileiro é caracterizado por altas temperaturas, reduzida pluviosidade e pequena produção de fitomassa. Somando-se a essas condições edafoclimáticas, observa-se predomínio da agricultura tradicional, que degrada os recursos naturais tornando-se insustentável. Objetivou-se comparar as propriedades químicas do solo de agroecossistemas sob manejo tradicional e diferentes períodos de pousio no semi árido cearense. Os agroecossistemas tradicionais foram: tradicional implantado em 2009 (TRAD 0); tradicional em pousio há 6 anos (TRAD 6); tradicional em pousio há 9 anos (TRAD 9); e uma área sob mata nativa (MN). O experimento foi realizado na Fazenda Crioula, pertencente a Embrapa Caprionos e Ovinos, em Sobral, Ceará. Foram analisadas as seguintes propriedades do solo: N total , pH em água, P disponível, Ca2+ , Mg2+ e K+ trocáveis e acidez potencial (H+ + Al3+). Foram calculados; soma de bases (SB), capacidade de troca catiônica (CTC); saturação de bases (V%) e matéria orgânica (MO). Os valores do pH e fósforo foram maiores no TRAD 0. As variáveis SB, CTC e V foram maiores no TRAD 6 que obteve as maiores médias, o que mostra recuperação do impacto causado pela manejo tradicional. O TRAD 9 não obteve resultados elevados, provavelmente, porque os nutrientes podem estar fixados nas plantas

    QUANTITATIVE REAL-TIME PCR (Q-PCR) FOR SPUTUM SMEAR DIAGNOSIS OF PULMONARY TUBERCULOSIS AMONG PEOPLE WITH HIV/AIDS

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    Objective: To assess quantitative real-time polymerase chain reaction (q-PCR) for the sputum smear diagnosis of pulmonary tuberculosis (PTB) in patients living with HIV/AIDS with a clinical suspicion of PTB. Method: This is a prospective study to assess the accuracy of a diagnostic test, conducted on 140 sputum specimens from 140 patients living with HIV/AIDS with a clinical suspicion of PTB, attended at two referral hospitals for people living with HIV/AIDS in the city of Recife, Pernambuco, Brazil. A Löwenstein-Jensen medium culture and 7H9 broth were used as gold standard. Results: Of the 140 sputum samples, 47 (33.6%) were positive with the gold standard. q-PCR was positive in 42 (30%) of the 140 patients. Only one (0.71%) did not correspond to the culture. The sensitivity, specificity and accuracy of the q-PCR were 87.2%, 98.9% and 95% respectively. In 39 (93%) of the 42 q-PCR positive cases, the CT (threshold cycle) was equal to or less than 37. Conclusion: q-PCR performed on sputum smears from patients living with HIV/AIDS demonstrated satisfactory sensitivity, specificity and accuracy, and may therefore be recommended as a method for diagnosing PTB
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