1,998 research outputs found

    Características de caulinitas de alguns solos brasileiros.

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    A caulinita é o mineral predominante na fração argila da maioria dos solos tropicais e, portanto, tem forte influência em suas propriedades morfológicas, físicas e químicas. A fração argila de 10 solos de classes diferentes foi analisada por difratometria de raios x e as características de suas caulinitas encontram-se na Tabela 1

    Dissolução da sodalita formada no tratamento com NaOH 5 Mol/L utilizado para concentração de óxidos de ferro.

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    O objetivo desse trabalho é estabelecer critérios para a utilização do HCl, de forma a garantir a completa dissolução da sodalita, na etapa seguinte ao tratamento com NaOH 5 M

    DC-DC power converter for high power solar photovoltaic system

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    Worldwide there is an enormous dependence on fossil fuels to produce electricity. Burning fossil fuels results in CO2 emission into the atmosphere, causing a negative environmental impact. In order to mitigate these problems, there is a need to integrate renewable energy sources into the power grid, namely solar photovoltaic (PV) energy. Power electronics converter solutions for solar PV module interface are vast and have advantages and disadvantages depending on the purpose. In addition, when the purpose is efficiency, it is important to consider the choice of the most appropriate power semiconductors. This paper presents a study, sizing, and development of a DC-DC power converter for high-power solar PV applications. In this study, a DC-DC boost interleaved power converter with two arms controlled by an incremental conductance Maximum Power Point Tracking (MPPT) control algorithm is proposed. The MPPT is combined with a Proportional-Integral (PI) controller for individual control of the current on each arm and was applied to extract the maximum power available at the solar PV module for different solar radiation and temperature conditions. The digital control system was implemented in a TMS320F28335 microcontroller from Texas Instruments.This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020. This work has been supported by the MEGASOLAR Project POCI-01-0247-FEDER-047220. Mr. Luis A. M. Barros is supported by the doctoral scholarship PD/BD/143006/2018 granted by the Portuguese FCT foundation

    In-situ hot forging directed energy deposition-arc of CuAl8 alloy

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    Funding Information: Authors acknowledge the Portuguese Fundação para a Ciência e a Tecnologia ( FCT - MCTES ) for its financial support via the project UID/EMS/00667/2019 (UNIDEMI). VD acknowledges Portuguese Fundação para a Ciência e a Tecnologia ( FCT - MCTES ) for funding the PhD grant SFRH/BD/139454/2018 . TAR acknowledges Portuguese Fundação para a Ciência e a Tecnologia ( FCT - MCTES ) for funding the PhD grant SFRH/BD/144202/2019 . Funding of CENIMAT/i3N by national funds through the Portuguese Fundação para a Ciência e a Tecnologia, I.P., within the scope of Multiannual Financing of R&D Units , reference UIDB/50025/2020–2023 is also acknowledge. This activity has received funding from the European Institute of Innovation and Technology (EIT) Raw Materials through the project Smart WAAM: Microstructural Engineering and Integrated Non-Destructive Testing. This body of the European Union receives support from the European Union's Horizon 2020 research and innovation programme. Parts of this research were carried out at PETRA III at DESY, a member of the Helmholtz Association. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020 . This project has received funding from the EU-H2020 research and innovation programme under grant agreement No 654360 having benefitted from the access provided by PETRA III at DESY in Hamburg, Germany within the framework of the NFFA-Europe Transnational Access Activity. The authors acknowledge support by OCAS NV and GUARENTEED via Joachim Antonissen. Funding Information: Authors acknowledge the Portuguese Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/EMS/00667/2019 (UNIDEMI). VD acknowledges Portuguese Fundação para a Ciência e a Tecnologia (FCT - MCTES) for funding the PhD grant SFRH/BD/139454/2018. TAR acknowledges Portuguese Fundação para a Ciência e a Tecnologia (FCT - MCTES) for funding the PhD grant SFRH/BD/144202/2019. Funding of CENIMAT/i3N by national funds through the Portuguese Fundação para a Ciência e a Tecnologia, I.P. within the scope of Multiannual Financing of R&D Units, reference UIDB/50025/2020–2023 is also acknowledge. This activity has received funding from the European Institute of Innovation and Technology (EIT) Raw Materials through the project Smart WAAM: Microstructural Engineering and Integrated Non-Destructive Testing. This body of the European Union receives support from the European Union's Horizon 2020 research and innovation programme. Parts of this research were carried out at PETRA III at DESY, a member of the Helmholtz Association. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. This project has received funding from the EU-H2020 research and innovation programme under grant agreement No 654360 having benefitted from the access provided by PETRA III at DESY in Hamburg, Germany within the framework of the NFFA-Europe Transnational Access Activity. The authors acknowledge support by OCAS NV and GUARENTEED via Joachim Antonissen. Remark: The supplementary material is temporarily available in the Drive folder here: https://drive.google.com/drive/folders/1SFFlhJlmL5p3IkQis8cB6UVWva3wozGi?usp=sharing. Publisher Copyright: © 2022 Elsevier B.V.CuAl8 alloy finds applications in industrial components, where a good anti-corrosion and anti-wearing properties are required. The alloy has a medium strength and a good toughness with an elongation to fracture at room temperature of about 40%. Additionally, it has a good electrical conductivity, though lower than that of pure Al or pure Cu. Despite these characteristics, additive manufacturing of the CuAl8 alloy was not yet reported. In this work, the direct energy deposition-arc (DED-arc) with and without in-situ hot forging was used to determine the microstructure evolution and mechanical properties. No internal defects were seen on the parts produced. Hot forging combined with DED-arc was seen to reduce and homogenize the grain size, improve mechanical strength and isotropy of mechanical properties. Moreover, the use of this novel DED-arc variant was seen to reduce the magnitude of residual stresses throughout the fabricated part. We highlight that this alloy can be processed by DED-arc, and the hot forging operation concomitant with the material deposition has beneficial effects on the microstructure refinement and homogenization.publishersversionpublishe

    Determining temporal sampling schemes for passive acoustic studies in different tropical ecosystems

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    Among different approaches to exploring and describing the ecological complexity of natural environments, soundscape analyses have recently provided useful proxies for understanding and interpreting dynamic patterns and processes in a landscape. Nevertheless, the study of soundscapes remains a new field with no internationally accepted protocols. This work provides the first guidelines for monitoring soundscapes in three different tropical areas, specifically located in the Atlantic Forest, Rupestrian fields, and the Cerrado (Brazil). Each area was investigated using three autonomous devices recording for six entire days during a period of 15 days in both the wet and dry seasons. The recordings were processed via a specific acoustic index and successively subsampled in different ways to determine the degree of information loss when reducing the number of minutes of recording used in the analyses. We describe for the first time the temporal and spectral soundscape features of three tropical environments. We test diverse programming routines to describe the costs and the benefits of different sampling designs, considering the pressing issue of storing and analyzing extensive data sets generated by passive acoustic monitoring. Schedule 5 (recording one minute of every five) appeared to retain most of the information contained in the continuous recordings from all the study areas. Less dense recording schedules produced a similar level of information only in specific portions of the day. Substantial sampling protocols such as those presented here will be useful to researchers and wildlife managers, as they will reduce time- and resource-consuming analyses, whilst still achieving reliable results

    Systematics of half-lives for proton radioactivity

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    Abstract -Half-life measurements for both ground-state and isomeric transitions in proton radioactivity are systematized by using a semiempirical, one-parameter model based on tunneling through a potential barrier, where the centrifugal and overlapping effects are taken into account within the spherical nucleus approximation. This approach, which has been successfully applied to alpha decay cases covering ∼ 30 orders of magnitude in half-life, has shown, in addition, very adequate at fitting all existing data on partial half-life, T 1/2 p , of proton emission from nuclei. Nearly 70 measured half-life values have been analysed, and the data could be described by two straight lines relating the pure Coulomb contribution to halflife with the quantity is the atomic number of the daughter nucleus, µ 0 is the reduced mass, and Q p is the total nuclear energy available for decay). These straight lines are shown to correspond to different degrees of deformation, namely, very prolate (δ 0.1), and other shaped (δ 0.1) parent nuclei. The goodness in reproducing the data attained in the present systematics allows for half-life predictions for a few possible cases of proton radioactivity not yet experimentally accessed

    Combined effect of bumetanide, bromide, and GABAergic agonists: An alternative treatment for intractable seizures

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    Univ Fed Sao Joao del Rei, Lab Neurociencia Expt & Computac, Programa Inst Bioengn, Sao Joao Del Rei, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Expt Neurol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Fisiol, São Paulo, BrazilPontificia Univ Catolica Rio Grande do Su, Inst Cerebro, Porto Alegre, RS, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Expt Neurol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Fisiol, São Paulo, BrazilWeb of Scienc

    Ticks on Didelphis albiventris from a Cerrado area in the Midwestern Brazil.

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    This experiment studied tick fauna associated to Didelphis albiventris Lund 1840 from a Cerrado area (Mato Grosso do Sul State, non-adjoining to Pantanal) inserted in a pasture and agricultural activities matrix, with few natural preserved forest patches. Authors also summarized data on ticks parasitizing Didelphis spp. in Brazil, and discussed infestation patterns in different biomes and locations. Study took place in Cervinho Farm, Bandeirantes Municipality. For captures, Tomahawk-like traps were distributed along two forest patches (30 each) during five nights. Captures occurred monthly (July/2013 to September/2014), sampling both fragments on alternate months. Animals were sedated and ticks were collected and stored in vials containing ethanol (70%) for identification. 51 D. albiventris were captured in 15 campaigns. Tick prevalence was 100%, and 49.5% of the animals were co-infested by two or more tick species. Four parasitizing species were found: Amblyomma sculptum Berlese, 1888 (78 nymphs), Ixodes loricatus Neumann, 1899 (56 adults), Amblyomma dubitatum Neumann, 1899 (45 nymphs), Amblyomma coelebs Neumann, 1899 (32 nymphs) and Amblyomma sp. (123 larvae). A. sculptum was the most abundant tick, but most frequent species were A. coelebs and A. dubitatum, followed by I. loricatus. Co-occurrences of more than two species were observed among all tick pairs. D. albiventris usually presents high prevalence of tick infestation. However, this study presented 100% prevalence. Knowledge of host-parasite relation and interactions between different ticks that coexist on a same host are essential, since such interaction may favor pathogen dissemination. This is of special relevance regarding D. albiventris, known for participating in maintenance of ecological cycles of Spotted Fever Group rickettsiae

    Avaliação do ataque da broca-do-tronco em genótipos de cajueiro-anão.

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    A cajucultura é uma das principais atividades agrícolas do sertão semiárido do Nordeste brasileiro. O sucesso da produtividade do cajueiro está associado à escolha de clones que estejam adaptados ao ambiente e apresentem certo grau de resistência aos insetos-praga e às doenças (Paiva; Barros, 2004). broca-do-tronco, Marshallius anacardii (Lima, 1979) (Coleoptera: Curculionidae), é uma coleobroca que causa danos irreversíveis ao caule do cajueiro (Melo; Bleicher, 1998). Suas larvas consomem o tecido do floema, ocasionando a obstrução do fluxo da seiva e, sob altas infestações, podem levar à morte da planta (Melo; Bleicher, 1998).bitstream/item/222821/1/CT-271.pd

    Cardiac Harms of Sofosbuvir: Systematic Review and Meta-Analysis

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    INTRODUCTION: Sofosbuvir is a new direct-acting pyrimidine nucleotide analogue antiviral drug that has shown remarkable efficacy in the treatment of hepatitis C in clinical trials. However, observational anecdotal data have recently suggested an increased risk of serious bradycardia among patients treated with sofosbuvir and amiodarone. OBJECTIVE: We aimed to estimate and characterize the cardiac safety of sofosbuvir by performing a systematic review of randomized controlled trials (RCTs). METHODS: We conducted a systematic review of RCTs (PROSPERO 2016: CRD42016033109) comparing sofosbuvir and non-sofosbuvir regimens in patients with chronic hepatitis C by searching the MEDLINE, Embase, and Cochrane Library databases up to January 2017. Non-published data were obtained from the sofosbuvir marketing authorization holder. Random-effects meta-analysis was performed to derive pooled estimates of relative risks (RRs) and corresponding 95% confidence intervals (CIs). RESULTS: Six trials, enrolling 2346 patients (1625 treated with sofosbuvir), were included. The overall risk of bias across studies was moderate. The risk of reported cardiac events (RR 0.87; 95% CI 0.41-1.85), arrhythmias (RR 0.93; 95% CI 0.34-2.51), bradycardia (RR 0.47; 95% CI 0.04-5.20), and tachycardia (RR 0.91; 95% CI 0.20-4.20) were not significantly different between sofosbuvir and non-sofosbuvir regimens. The risks of reported syncope, presyncope, loss of consciousness, or palpitations were similar among those receiving sofosbuvir regimens and controls. CONCLUSIONS: The pooled data from RCTs did not show an increased risk of cardiac outcomes, including arrhythmias (and bradycardia), among sofosbuvir-treated patients, although the overall quality of the evidence supporting this conclusion was very low
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