Efeito de níveis de calcário no desenvolvimento e absorção de nutrientes em plantas jovens de açaizeiro (Euterpe oleracea Mart.).

O presente trabalho objetiva determinar a resposta para açaí cultivar BRS - Pará à aplicação de calcário dolomítico em Latossolo Amarelo de textura médi

Conducting polymer- hydrogel blends for electrochemically controlled drug release devices

Blends formed by electrochemical polymerization of polypyrrole (PPy) into polyacrylamide (PAAm) hydrogels were used as devices for controlled drug release. The influence of several parameters in the synthesis, such as type of hydrogel matrix and polymerization conditions was studied by using a fractional factorial design. The final goal was to obtain an adequate device for use in controlled release tests, based on electrochemical potential control. For controlled release tests, Safranin was used as model drug and release curves (amount of drug vs. time) have shown that these blends are promising materials for this use. The optimized blends obtained were characterized by cyclic voltammetry and Raman spectroscopy.Blendas formadas pela polimerização eletroquímica de pirrol em matriz de acrilamida (hidrogel) foram utilizadas, neste trabalho, como dispositivos para a liberação controlada de drogas. A influência de vários parâmetros nesta síntese, como tipo de matriz de hidrogel e condições de polimerização, foi estudada empregando-se planejamento fatorial fracionário. O objetivo final consistiu na obtenção de um material adequado para liberação baseada no controle de potencial. Para os testes de liberação foi utilizada Safranina, como substância modelo. As curvas de liberação demonstram a potencialidade do uso de tais dispositivos. Estes dispositivos foram também caracterizados por espectroscopia Raman e voltametria cíclica.FAPESPCNP

Concentration dependent structural, thermal, and optical features of Pr 3+-doped multicomponent tellurite glasses

Tuning the structural, thermal, and optical properties of low phonon energy glasses such as tellurite glasses (phonon energy ∼750 cm−1) with suitable rare earth dopants is a key issue in the fabrication of solid state lasers and optical amplifiers. In this work, (70-x) TeO2-10 WO3-10 ZnO-5 TiO2-5 Na2O-(x) Pr2O3 (x = 1.0–5.0 mol %) glasses were synthesized with high optical quality and characterized using X-ray diffraction (XRD), Scanning electron microscopy and Energy dispersive X-ray analysis (SEM-EDAX), Attenuated total reflectance-Fourier transform infrared (ATR-FTIR), Raman spectroscopy, Thermo-gravimetric analysis (TGA), Differential scanning calorimetry (DSC), optical absorption and luminescence techniques. The XRD and SEM measurements reveal the amorphous nature of all the prepared glasses and EDAX confirms all the elements present in the respective glasses. The presence of various functional groups such as stretching vibrations of Te[single bond]–O bonds in the [TeO4] trigonal bi-pyramid units, symmetrical stretching or bending vibrations of Te[single bond]–O[single bond]–Te or O[single bond]–Te[single bond]–O linkages at corner sharing sites along the chains of TeO4, TeO3 and TeO3+1, stretching vibrations of W[single bond]–O– and W[double bond; length as m-dash]═O bonds in WO4 tetragonal or WO6 octagonal units, vibrations of Zn[single bond]–O bonds from ZnO4 groups, including non-hygroscopic nature of the glasses are confirmed by ATR-FTIR and Raman spectra, respectively. For Pr3+-doped glasses, from the DSC profiles the glass transition temperature (Tg), onset crystallization temperature (Tx), crystallization temperature (Tc), and melting temperature (Tm) are identified and the evaluated thermal stability values varied in the temperature range of 169–220 °C with increasing Pr3+ doping concentration. Further, the Pr3+ -doped tellurite glasses demonstrate excellent glass stability with higher criterion of Hruby's value (HR) between 1.9 and 3.9. From the measured optical absorption spectrum, experimental oscillator strengths are calculated and used to evaluate three phenomenological Judd-Ofelt (J-O) intensity parameters Ω_λ_ (_λ_ = 2, 4 and 6) and respective radiative properties such as radiative transition probabilities (AR), the branching ratios (βR), and the radiative lifetime (τR) of metastable states for 1.0 mol % Pr3+-doped glass. Five main emission transitions at 3P0 → 3H5 (530 nm; green) with a shoulder at 543 nm, a weak band at 1D2 → 3H4 (592 nm; orange), 3P0 → 3H6 (615 nm; orange), 3P0 → 3F2 (649 nm; red), and 3P0 → 3F3 (686 nm; red) upon exciting at 486 nm (3H4 → 3P0) wavelength are observed from the luminescence spectra of Pr3+-doped tellurite glasses. Following the energy level diagram, Pr3+ ion concentration quenching on the luminescence intensity has been explained by a non-radiative energy transfer between the ions through cross-relaxation and energy migration processes. The concentration dependent structural, thermal, and optical behaviors of Pr 3+-doped tellurite glasses are understood and our systematic analysis could contribute towards the development of suitable optical devices fabrication. Raman spectra of all the synthesized glasses

Diagnósticos participativos da agrobiodiversidade em quatro comunidades de Lagoa Grande (PE).

O objetivo deste trabalho foi diagnosticar a agrobiodiversidade em comunidades de Lagoa Grande ? PE (Sítio Roseiras, Caldeirãozinho e Assentamentos Riacho Fundo e Abreu e Lima). Para isto, foram realizadas visitas às residências dos agricultores. O diagnóstico foi realizado com aplicação de questionário, visando obter informações sobre os cultivos e criações desenvolvidos na comunidade. Foi identificado pelo menos um guardião de sementes nas referidas comunidades, com exceção do Assentamento Abreu e Lima e Sitio Roseiras. Os resultados mostram a importância de promover a distribuição de kits de diversidade nas três comunidades estudadas devido ao risco de erosão genética, bem como de incentivar atividades participativas visando o fortalecimento da comunidade com intuito de desenvolver atividades sustentáveis

X-ray photoelectron spectroscopy (XPS) and radiation shielding parameters investigations for zinc molybdenum borotellurite glasses containing different network modifiers

Zinc molybdenum borotellurite glasses containing different network modifiers with the nominal composition of 60 TeO2–10 B2O3–10 MoO3–10 ZnO–10 MO (MO = Li2O, Na2O, K2O, MgO, CaO, and PbO) were prepared by melt quenching method. The X-ray photoelectron spectroscopy (XPS) studies allow to monitor the structural modifications leading to the formation of bridging oxygens (Te–O–Te, B–O–B, Mo–O–Mo, and Te–O–Mo bonds) and nonbridging oxygens (Te = O, Te–O−M+, Mo–O− bonds in the MoO6 octahedral units, Zn–O bonds from ZnO4) with the addition of alkali (Li, Na, and K), alkaline (Mg, Ca), or heavy metal (Pb) oxides. The Te 3d localized core-levels spectra show an asymmetry due to the existence of different Te-based structural clusters and were fitted with three contributions such as Te ions in TeO4 trigonal bipyramid configuration, Te ions in TeO3 − trigonal pyramid configuration and TeO3+1 polyhedra, respectively. The analysis of the Mo 3d spectra indicates prevailingly Mo6+ ions only. The Zn 2p core-level XPS spectra demonstrate that the zinc is mainly coordinated by four oxygen atoms. The essential radiation shielding parameters were studied for the prepared glasses in the photon energy range 1 keV to 100 GeV using WinXCom software program. Parameters like mass attenuation coefficient (μ/ρ), effective atomic number (Z eff), and mean free path (MFP) are evaluated. Further, by using geometric progression method, exposure buildup factor (EBF) values were also calculated in the incident photon energy range 0.015–15 MeV, up to penetration depth of 40 mfp (mean free path). The macroscopic effective removal cross sections (∑R) for fast neutrons have been calculated. The maximum values of μ/ρ and Z eff were found for PbO-introduced glass though it possesses a lower value for MFP and EBF. The obtained results indicate that PbO-based glass is the best radiation shielding material among the studied glasses

Seleção de bucha vegetal por agricultores familiares.

Este trabalho consistiu em dois ensaios de seleção participativa de bucha vegetal. O primeiro ensaio foi implantado na comunidade Cacimba do Baltazar, Petrolina, PE sendo avaliadas quatro variedades locais (VLs) em canteiros de diversidade com seis plantas por VL. O outro ensaio foi conduzido no Campo Experimental de Bebedouro da Embrapa Semiárido com seis VLs em blocos ao acaso com três repetições e seis plantas por parcela. As avaliações foram realizadas por agricultores familiares das comunidades Cacimba do Baltazar, Tanque Novo, Casa Nova, BA e Lagoa do Mari, Sento Sé, BA, usando as ferramentas participativas seleção com espetos de madeira, tempestade de ideias e matriz de classificação. As características definidas pelos agricultores das três comunidades para a seleção foram praticamente as mesmas, ou seja, tamanho do fruto, textura da fibra, produtividade e adequação para artesanato. Os agricultores familiares da Cacimba do Baltazar selecionaram a VL2, seguida pela VL3, VL4 e VL5. No entanto a VL4 recebeu mais votos para tamanho do fruto. Os agricultores familiares da Lagoa do Mari e Tanque Novo selecionaram a VL6, seguida pela VL4, VL7, VL8, VL3 e VL5. As VLs selecionadas serão usadas em programas de melhoramento participativo conforme interesse dos agricultores familiare

Double-detonation sub-Chandrasekhar supernovae: synthetic observables for minimum helium shell mass models

Abridged. In the double detonation scenario for Type Ia supernovae (SNe Ia) a detonation initiates in a shell of He-rich material accreted from a companion star by a sub-Chandrasekhar-mass White Dwarf (WD). This shell detonation drives a shock front into the carbon-oxygen (C/O) WD that triggers a secondary detonation in the core. The core detonation results in a complete disruption of the WD. Earlier studies concluded that this scenario has difficulties in accounting for the observed properties of SNe Ia since the explosion ejecta are surrounded by the products of explosive He burning in the shell. Recently, it was proposed that detonations might be possible for much less massive He shells than previously assumed. Moreover, it was shown that even detonations of these minimum He shell masses robustly trigger detonations of the C/O core. Here we present time-dependent multi-wavelength radiative transfer calculations for models with minimum He shell mass and derive synthetic observables for both the optical and {\gamma}-ray spectral regions. These differ strongly from those found in earlier simulations of sub-Chandrasekhar-mass explosions in which more massive He shells were considered. Our models predict light curves which cover both the range of brightnesses and the rise and decline times of observed SNe Ia. However, their colours and spectra do not match the observations. In particular, their B-V colours are generally too red. We show that this discrepancy is mainly due to the composition of the burning products of the He shell of our models which contain significant amounts of Ti and Cr. Using a toy model, we also show that the burning products of the He shell depend crucially on its initial composition. This leads us to conclude that good agreement between sub-Chandrasekhar-mass explosions and observed SNe Ia may still be feasible but further study of the shell properties is required.Comment: 17 pages, 13 figures. Accepted for publication by Ap