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3,900 result(s) for "Santos, J. E. L."
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Comparative Study of the Synthesis and Characterization of Reduced Graphene Oxide (RGO) Using an Eco-Friendly Reducing Agent
In this work, the reducing action of four reducing agents—ascorbic acid, inorganic salt, sodium hydrosulfite and polysaccharide—was investigated. Some reducing agents, in addition to being environmentally friendly, are good substitutes for dangerous chemicals used industrially. Graphene oxide (GO) was synthesized by the modified Hummers method and was reduced with ascorbic acid (RGO-AA), inorganic salt (RGO-SI), sodium hydrosulfite (RGO-HS) and polysaccharide (RGO-PS). The microstructural, morphological, optical, electrochemical and thermal properties of GO, RGO-AA, RGO-SI, RGO-HS and RGO-PS were characterized by x-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy/attenuated total reflectance (FTIR-ATR), x-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM)/energy-dispersive x-ray spectroscopy (EDS), field-emission scanning electron microscopy (FEG-SEM), UV–Vis, zeta potential, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The conclusive results showed that the four agents demonstrated reducing capability. It was observed that the reducing agent derived from inverted sugar (polysaccharide) was the most efficient because it presented a reduction in GO with fewer microstructural defects, a lower number of sheets, and electrochemical and thermal properties superior to the properties obtained from conventional reducing agents. Therefore, with these impressive results obtained with polysaccharide, it was concluded that an effective GO reducing agent was obtained using this green and ecological product, resulting in a reduced graphene oxide (RGO) with few sheets and fewer defects and, consequently, with greater supercapacitor application potential.
An electrochemical and magnetic approach for /H2SO4/HNO3/chitosan functionalized multi-wall carbon nanotubes stable solutions
The aim of the research was to evaluate the effects of sulfonitric and CS (CS) treatment in multilayer carbon nanotubes (MWCNT) on their electrochemical and magnetic properties. Thermogravimetric analysis (TG) showed an increase in thermal properties for CS functionalized MWCNT when compared in sulfonitric medium. High resolution transmission electron microscopy (HRTEM) images revealed a reduction in the average diameter of functionalized MWCNT in the presence of CS in addition to decreasing their interlayer spaces. As evidenced by X-ray Diffraction (XRD) patterns. In addition, X-ray photoelectron spectroscopy (XPS) spectra proved the functional groups inclusion of CS and sulfonitric solution on the (carbon nanotubes) CNT matrix. Unlike pristine MWCNT solutions which are unstable in aqueous media, functionalization with acidic solutions and contributed to its potential stabilization. The results obtained by Raman Spectroscopy prove the functionalization through the insertion of functional groups in the walls of the nanotubes. The electroanalysis showed higher capacitance values by mass and by area for samples functionalized with acids and that the addition of CS during functionalization increases the resistance to current flow, causing an insulating effect.
Simulated Optimum Sowing Date for Forage Pearl Millet Cultivars in Multilocation Trials in Brazilian Semi-Arid Region
Forage production is primarily limited by weather conditions under dryland production systems in Brazilian semi-arid regions, therefore sowing at the appropriate time is critical. The objectives of this study were to evaluate the CSM-CERES-Pearl Millet model from the DSSAT software suite for its ability to simulate growth, development, and forage accumulation of pearl millet [ (L.) R.] at three Brazilian semi-arid locations, and to use the model to study the impact of different sowing dates on pearl millet performance for forage. Four pearl millet cultivars were grown during the 2011 rainy season in field experiments conducted at three Brazilian semi-arid locations, under rainfed conditions. The genetic coefficients of the four pearl millet cultivars were calibrated for the model, and the model performance was evaluated with experimental data. The model was run for 14 sowing dates using long-term historical weather data from three locations, to determine the optimum sowing window. Results showed that performance of the model was satisfactory as indicated by accurate simulation of crop phenology and forage accumulation against measured data. The optimum sowing window varied among locations depending on rainfall patterns, although showing the same trend for cultivars within the site. The best sowing windows were from 15 April to 15 May for the Bom Conselho location; 12 April to 02 May for Nossa Senhora da Gloria; and 17 April to 25 May for Sao Bento do Una. The model can be used as a tool to evaluate the effect of sowing date on forage pearl millet performance in Brazilian semi-arid conditions.
Ecological Adaptation of Wild Peach Palm, Its In Situ Conservation and Deforestation-Mediated Extinction in Southern Brazilian Amazonia
Background: The Arc of Fire across southern Amazonia seasonally attracts worldwide attention as forests are cut and burned for agricultural expansion. These forests contain numerous wild relatives of native South American crops, such as peach palm. Methodology/Principal Findings: Our prospecting expeditions examined critical areas for wild peach palm in the Arc of Fire in Mato Grosso, Pará, Maranhão and Tocantins, as well as areas not previously examined in Amazonas and Amapá states. Recent digitization of the RADAM Brasil project permitted comparison among RADAM's parataxonomists' observations, previous botanical collections and our prospecting. Mapping on soils and vegetation types enabled us to hypothesize a set of ecological preferences. Wild peach palm is best adapted to Ultisols (Acrisols) in open forests across the Arc of Fire and westward into the more humid western Amazonia. Populations are generally small (fewer than 10 plants) on slopes above watercourses. In northern Mato Grosso and southern Pará soybean fields and pastures now occupy numerous areas where RADAM identified wild peach palm. The controversial BR-163 Highway is already eroding wild peach palm as deforestation expands. Conclusions/Significance: Many of these populations are now isolated by increasing forest fragmentation, which will lead to decreased reproduction via inbreeding depression and eventual extinction even without complete deforestation. Federal conservation areas are less numerous in the Arc of Fire than in other parts of Brazilian Amazonia, although there are indigenous lands; these conservation areas contain viable populations of wild peach palm and require better protection than they are currently receiving. Ex situ conservation of these populations is not viable given the relative lack of importance of domesticated peach palm and the difficulty of maintaining even economically interesting genetic resources.
Exogenous application of salicylic acid induces salinity tolerance in eggplant seedlings
Abstract Under salt stress conditions, plant growth is reduced due to osmotic, nutritional and oxidative imbalance. However, salicylic acid acts in the mitigation of this abiotic stress by promoting an increase in growth, photosynthesis, nitrogen metabolism, synthesis of osmoregulators and antioxidant enzymes. In this context, the objective was to evaluate the effect of salicylic acid doses on the growth and physiological changes of eggplant seedlings under salt stress. The experiment was conducted in a greenhouse, where the treatments were distributed in randomized blocks using a central composite matrix Box with five levels of electrical conductivity of irrigation water (CEw) (0.50; 1.08; 2.50; 3.92 and 4.50 dS m-1), associated with five doses of salicylic acid (SA) (0.00; 0.22; 0.75; 1.28 and 1.50 mM), with four repetitions and each plot composed of three plants. At 40 days after sowing, plant height, stem diameter, number of leaves, leaf area, electrolyte leakage, relative water content, and total dry mass were determined. ECw and SA application influenced the growth and physiological changes of eggplant seedlings. Increasing the ECw reduced growth in the absence of SA. Membrane damage with the use of SA remained stable up to 3.9 dS m-1 of ECw. The relative water content independent of the CEw increased with 1.0 mM of SA. The use of SA at the concentration of 1.0 mM mitigated the deleterious effect of salinity on seedling growth up to 2.50 dS m-1 of ECw. Resumo Em condições de estresse salino, o crescimento das plantas é reduzido, em virtude, do desequilíbrio osmótico, nutricional e oxidativo. Contudo, o ácido salicílico atua na mitigação desse estresse abiótico por promover incremento no crescimento, fotossíntese, metabolismo do nitrogênio, síntese de osmorreguladores e enzimas antioxidantes. Nesse contexto, objetivou-se avaliar o efeito de doses de ácido salicílico sobre o crescimento e alterações fisiológicas de mudas de berinjela sob estresse salino. O experimento foi conduzido em casa de vegetação, onde os tratamentos foram distribuídos em blocos ao acaso utilizando uma matriz composta central Box com cinco níveis de condutividade elétrica da água de irrigação (CEa) (0,50; 1,08; 2,50; 3,92 e 4,50 dS m-1), associada a cinco doses de ácido salicílico (AS) (0,00; 0,22; 0,75; 1,28 e 1,50 mM), com quatro repetições e cada parcela composta por três plantas. Aos 40 dias após a semeadura, foram determinados a altura da planta, diâmetro do caule, número de folhas, área foliar, vazamento de eletrólito, teor relativo de água e massa seca total. A CEa e a aplicação de AS influenciaram no crescimento e nas alterações fisiológicas das mudas de berinjela. O aumento da CEa reduziu o crescimento na ausência de AS. O dano de membrana com o uso de AS manteve-se estável até 3,9 dS m-1 de CEa. O conteúdo relativo de água independentemente da CEa aumentou com 1 mM de SA. O uso de AS na concentração de 1 mM mitigou o efeito deletério da salinidade no crescimento das mudas até 2,50 dS m-1 de CEa.
Genomic and epidemiological monitoring of yellow fever virus transmission potential
The yellow fever virus (YFV) epidemic in Brazil is the largest in decades. The recent discovery of YFV in Brazilian Aedes species mosquitos highlights a need to monitor the risk of reestablishment of urban YFV transmission in the Americas. We use a suite of epidemiological, spatial, and genomic approaches to characterize YFV transmission. We show that the age and sex distribution of human cases is characteristic of sylvatic transmission. Analysis of YFV cases combined with genomes generated locally reveals an early phase of sylvatic YFV transmission and spatial expansion toward previously YFV-free areas, followed by a rise in viral spillover to humans in late 2016. Our results establish a framework for monitoring YFV transmission in real time that will contribute to a global strategy to eliminate future YFV epidemics.
Rapid antidepressant effects of the psychedelic ayahuasca in treatment-resistant depression: a randomized placebo-controlled trial
Recent open-label trials show that psychedelics, such as ayahuasca, hold promise as fast-onset antidepressants in treatment-resistant depression. To test the antidepressant effects of ayahuasca, we conducted a parallel-arm, double-blind randomized placebo-controlled trial in 29 patients with treatment-resistant depression. Patients received a single dose of either ayahuasca or placebo. We assessed changes in depression severity with the Montgomery-Åsberg Depression Rating Scale (MADRS) and the Hamilton Depression Rating scale at baseline, and at 1 (D1), 2 (D2), and 7 (D7) days after dosing. We observed significant antidepressant effects of ayahuasca when compared with placebo at all-time points. MADRS scores were significantly lower in the ayahuasca group compared with placebo at D1 and D2 (p = 0.04), and at D7 (p < 0.0001). Between-group effect sizes increased from D1 to D7 (D1: Cohen's d = 0.84; D2: Cohen's d = 0.84; D7: Cohen's d = 1.49). Response rates were high for both groups at D1 and D2, and significantly higher in the ayahuasca group at D7 (64% v. 27%; p = 0.04). Remission rate showed a trend toward significance at D7 (36% v. 7%, p = 0.054). To our knowledge, this is the first controlled trial to test a psychedelic substance in treatment-resistant depression. Overall, this study brings new evidence supporting the safety and therapeutic value of ayahuasca, dosed within an appropriate setting, to help treat depression. This study is registered at http://clinicaltrials.gov (NCT02914769).
Helium, Oxygen, Proton, and Electron (HOPE) Mass Spectrometer for the Radiation Belt Storm Probes Mission
The HOPE mass spectrometer of the Radiation Belt Storm Probes (RBSP) mission (renamed the Van Allen Probes) is designed to measure the in situ plasma ion and electron fluxes over 4 π sr at each RBSP spacecraft within the terrestrial radiation belts. The scientific goal is to understand the underlying physical processes that govern the radiation belt structure and dynamics. Spectral measurements for both ions and electrons are acquired over 1 eV to 50 keV in 36 log-spaced steps at an energy resolution Δ E FWHM / E ≈15 %. The dominant ion species (H + , He + , and O + ) of the magnetosphere are identified using foil-based time-of-flight (TOF) mass spectrometry with channel electron multiplier (CEM) detectors. Angular measurements are derived using five polar pixels coplanar with the spacecraft spin axis, and up to 16 azimuthal bins are acquired for each polar pixel over time as the spacecraft spins. Ion and electron measurements are acquired on alternate spacecraft spins. HOPE incorporates several new methods to minimize and monitor the background induced by penetrating particles in the harsh environment of the radiation belts. The absolute efficiencies of detection are continuously monitored, enabling precise, quantitative measurements of electron and ion fluxes and ion species abundances throughout the mission. We describe the engineering approaches for plasma measurements in the radiation belts and present summaries of HOPE measurement strategy and performance.
Quantitative flow ratio versus fractional flow reserve for coronary revascularisation guidance (FAVOR III Europe): a multicentre, randomised, non-inferiority trial
Fractional flow reserve (FFR) or non-hyperaemic pressure ratios are recommended to assess functional relevance of intermediate coronary stenosis. Both diagnostic methods require the placement of a pressure wire in the coronary artery during invasive coronary angiography. Quantitative flow ratio (QFR) is an angiography-based computational method for the estimation of FFR that does not require the use of pressure wires. We aimed to investigate whether a QFR-based diagnostic strategy yields a non-inferior 12-month clinical outcome compared with an FFR-based strategy. FAVOR III Europe was a multicentre, randomised, open-label, non-inferiority trial comparing a QFR-based with an FFR-based diagnostic strategy for patients with intermediate coronary stenosis. Enrolment was performed in 34 centres across 11 European countries. Patients aged 18 years or older with either chronic coronary syndrome or stabilised acute coronary syndrome, and with at least one intermediate non-culprit stenosis (40–90% diameter stenosis by visual estimate; referred to here as a study lesion), were randomly assigned (1:1) to the QFR-guided or the FFR-guided group. Randomisation was done using a concealed web-based system and was stratified by diabetes and presence of a left anterior descending coronary artery study lesion. The primary endpoint was a composite of death, myocardial infarction, and unplanned revascularisation at 12 months. The predefined non-inferiority margin was 3·4% and the primary analysis was performed in the intention-to-treat population. The trial was registered with ClinicalTrials.gov (NCT03729739) and long-term follow-up is ongoing. Between Nov 6, 2018, and July 21, 2023, 2000 patients were enrolled and randomly assigned to the QFR-guided strategy (1008 patients) or the FFR-guided strategy (992 patients). The median age was 67·3 years (IQR 59·9–74·7); 1538 (76·9%) patients were male and 462 (23·1%) were female. Median follow-up time was 365 days (IQR 365–365). At 12 months, a primary endpoint event had occurred in 67 (6·7%) patients in the QFR group, and in 41 (4·2%) patients in the FFR group (hazard ratio 1·63 [95% CI 1·11–2·41]). The event proportion difference was 2·5% (90% two-sided CI 0·9–4·2). The upper limit of the 90% CI exceeded the prespecified non-inferiority margin of 3·4%. Therefore, QFR did not meet non-inferiority to FFR. A total of 18 (1·8%) patients in each group experienced an adverse procedural event, the most frequent being procedure-related myocardial infarction, which occurred in ten (1·0%) patients in the QFR group and seven (0·7%) in the FFR group. One patient in the QFR group died in relation to the index procedure. The results of the FAVOR III Europe trial do not support the use of QFR if FFR is available to guide revascularisation decisions in patients with intermediate coronary stenosis. This finding could have implications for current clinical guidelines recommending QFR for this purpose. Medis Medical Imaging Systems and Aarhus University.