1,129 research outputs found
Content and label diagnosis of commercialized herbal drug of Uncaria tomentosa (Willd.) DC. in Rio de Janeiro and Minas Gerais.
Uncaria tomentosa, known as cat's claw, is a medicinal plant used as antiinflammatory in folk medicine and in SUS fitotherapy. To ensure safety and effectiveness in its use, it's necessary to certify the authenticity of the drug. This work aims to know if the herb drugs of U. tomentosa offered in Rio de Janeiro and Minas Gerais markets are authentic, and if their labels are according to RDC10/2010
Efeito da matéria orgânica oriunda da capoeira triturada (Mulching) na produtividade de pastagem.
Comparing slash-and-burn and slash-and-trituration/mulch as land preparation for pasture establishment in brazilian eastern Amazon: soil humidity.
Assembly of sol-gel-grown Li<SUB>x</SUB>CoO<SUB>2</SUB> nanocrystals through electromagnetic irradiation
We report the fabrication of assembled nanostructures from the pre-synthesized nanocrystals building blocks through optical means of exciton formation and dissociation. We demonstrate that Lix CoO2 nanocrystals assemble to an acicular architecture, upon prolonged exposure to ultraviolet-visible radiation emitted from a 125 W mercury vapor lamp, through intermediate excitation of excitons. The results obtained in the present study clearly show how nanocrystals of various materials with band gaps appropriate for excitations of excitons at given optical wavelengths can be assembled to unusual nanoarchitectures through illumination with incoherent light sources. The disappearance of exciton bands due to Li xCoO2 phase in the optical spectrum of the irradiated film comprising acicular structure is consistent with the proposed mechanism of exciton dissociation in the observed light-induced assembly process. The assembly process occurs through attractive Coulomb interactions between charged dots created upon exciton dissociation. Our work presents a new type of nanocrystal assembly process that is driven by light and exciton directed
Quantificação de polifenóis totais da polpa de açaí cultivar BRS-Pará.
Este trabalho teve como objetivo determinar o teor de polifenóis da cultivar BRS-Pará
Endohelmintos parasitos de 16 espécies de Cichlidae da Bacia do Igarapé Fortaleza, Macapá, Estado do Amapá, Brasil.
ENBRAPOA
Gaussian coordinate systems for the Kerr metric
We present the whole class of Gaussian coordinate systems for the Kerr
metric. This is achieved through the uses of the relationship between Gaussian
observers and the relativistic Hamilton-Jacobi equation. We analyze the
completeness of this coordinate system. In the appendix we present the
equivalent JEK formulation of General Relativity -- the so-called
quasi-Maxwellian equations -- which acquires a simpler form in the Gaussian
coordinate system. We show how this set of equations can be used to obtain the
internal metric of the Schwazschild solution, as a simple example. We suggest
that this path can be followed to the search of the internal Kerr metric
7-pentoxyresorufin-o-depentilase and 7-Benzyloxyresorufin-o-debenzylase as potential biomarkers of exposure to 17B-estradiol in nile tilapia.
Oleic acid esterification catalyzed by zeolite y - model of the biomass conversion
Lignocellulosic biomass is a promising renewable source for production of fuels and chemicals with significant life cycle and economy of scale advantages over other biomass sources, such as starches, vegetable oils, and animal fats. The large-scale application of zeolites in biomass conversion can be explained by with adjustable confinement at the nano scale, Brønsted acid strength that derive from its Si/Al ratio and high thermal stability1. In this context, the aim of this study was to test the catalytic activity of zeolite H-Y with high Si/Al ratio for its application in the esterification reaction of oleic acid (OA) with methanol (MeOH) for the synthesis of alkyl esters. Zeolite Y in protonated form with Si / Al = 80 ratio was obtained from Zeolyst International. The catalytic activity of zeolite H-Y was carried out using the esterification reaction of OA by MeOH. The experiments were conducted in reflux system with magnetic stirring at different temperatures (60 and 75 °C), catalyst contents (10 %), OA mass ratios (1:2, 1:3 and 1:6) and residence times (0.5, 1, 1.5, 2, 3, 4.5, 6, 8, 12 and 16 hs). The reaction mixture was collected from the reflux system, and cooled to room temperature. The solution was removed from the catalyst by filtration. The conversion was defined as the change of acid content before and after the oil reaction by the acid content of the initial oil. An interpretation of the catalytic activity is given from theoretical calculations.Analysis indicate that the increase in reaction time results in higher ester conversion rates, reaching the reaction equilibrium after 16 hs of reaction, according to Kirumakki et. al. the time required to achieve equilibrium depends on the reactants used2. It is observed that the conversion of OA results in a high reaction time when is compared to previous works2-4, the main effect for this system is centered in the high Si/Al ratio, which results in the less presence of active sites available in the catalytic process. The optimum reaction conditions were obtained with a molar ratio of 1:3 and 75 °C, resulting in 82 % conversion of ester after 16 hs of reaction. The higher alcohol concentration in the system shifts the equilibrium of the reaction towards the formation of products, as well as the decrease in the viscosity of the reactional system, reducing the transfer rate, which results in a high conversion when compared to the others catalytic tests. According to our previous work, the esterification of carboxylic acids presents a competitive adsorption between methanol and carboxylic acid on the Brønsted acid site5, so that the main hypothesis for the lower product conversion in the esterification reaction with 1:6 molar ratio is related to the adsorption of MeOH on the active site. The effect of self-catalysis on the reactional environment is not reported in the studies cited, according to Raia et. al., auto-catalysis in esterification has a significant importance in the conversion of free fatty acids6. The uncatalyzed reaction resulted in approximately 16 % conversion after 16 hs of reaction, and this result serves as a comparison for the conditions in which the catalyst is added to the system. The H-Y catalyst proved to be efficient and promising for the esterification of OA with MeOH, however, it presented a high reaction time can be optimized with the increase of temperature and greater mass of catalyst, thus, further studies are needed to describe the reaction mechanisms in order to understand the conversion of biomass on the surface of acid zeolites.Fil: Gomes, Glaucio José. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura. Departamento de Química. Laboratorio de Estructura Molecular y Propiedades; Argentina. Universidade Estadual de Maringá. Departamento de Engenharia Química.; BrasilFil: Dal Pozzo, Daniel M.. Universidade Federal do Paraná; BrasilFil: Zalazar, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Química Básica y Aplicada del Nordeste Argentino. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Química Básica y Aplicada del Nordeste Argentino; ArgentinaFil: Costa, M. B.. Universidade Federal do Paraná; BrasilFil: Arroyo, Pedro Augusto. Universidade Estadual de Maringá. Departamento de Engenharia Química.; BrasilFil: Bittencourt, Paulo R. S.. Universidade Federal do Paraná; BrasilVI San Luis School and Conference on Surfaces, Interfaces and CatalysisSanta FeArgentinaInstituto de Investigaciones en Catálisis y PetroquímicaUniversidad Nacional del Litora
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