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排序方式: 共有197条查询结果,搜索用时 15 毫秒
131.
Simone Farias Diego A. Mayer Débora de Oliveira Selene M. A. Guelli U. de Souza Antônio Augusto Ulson de Souza 《Applied biochemistry and biotechnology》2017,182(4):1290-1306
The aim of this work was to remove the dyes Reactive Blue 221 (RB 221) and Reactive Blue 198 (RB 198) of synthetic effluent using the immobilized enzyme horseradish peroxidase (HRP) in Ca-alginate beads. Experimental parameters affecting the dye removal process such as the effect of pH, temperature, hydrogen peroxide concentration, mass capsules, and reuse were evaluated, and a numerical model of mass transfer was developed. A maximum removal of 93 and 75%, respectively, for the dyes RB 221 and RB 198, at pH 5.5 and temperature of 30 °C, concentration of hydrogen peroxide of 43.75 μM for dye RB 221 and 37.5 μM for the dye of RB 198 was obtained. A removal reaction of 180 min for RB 221 and 240 min for RB 198 was observed. Three reuse cycles of use of immobilized enzyme were achieved for both dyes. The numerical model proposed led to a good fit compared to experimental data. The HRP enzyme immobilized in Ca-alginate capsules showed a great potential for biotechnological applications, especially for the removal of reactive dyes. 相似文献
132.
Rosiane M. C. Farias Marta M. Conceição Roberlúcia A. Candeia Marta C. D. Silva Valter J. FernandesJr. Antonio G. Souza 《Journal of Thermal Analysis and Calorimetry》2011,106(3):651-655
The diversity of raw materials and technological routes employed in the biodiesel production has resulted in products with
different chemical properties. This non-uniformity in the biodiesel composition may influence to the fuel quality. The aim
of this study was to evaluate biodiesel blends of passion fruit and castor oil in different proportions and their thermal
stability. Biodiesel blends of passion fruit and castor oil presented parameters in the standards of the Petroleum, Natural
Gas and Biofuels National Agency. The TG curves indicated that castor oil biodiesel was more stable. Passion fruit biodiesel
has a high content of oleic and linoleic acids, which are more susceptible to oxidation. Biodiesel blend of passion fruit
and castor oil 1:1 increased the thermal stability in relation to passion fruit biodiesel. Biodiesel blend of passion fruit
and castor oil 1:2 presented higher thermal stability, because castor oil has a high content of ricinoleic acid. 相似文献
133.
Maria J. F. Costa Antonio S. Araujo Edjane F. B. Silva Mirna F. Farias Valter J. FernandesJr. Petrus d’Amorim Santa-Cruz José G. A. Pacheco 《Journal of Thermal Analysis and Calorimetry》2011,106(3):767-771
The nanostructured hybrid AlMCM-41/ZSM-5 composite was synthesized starting from a hydrogel with molar composition SiO2:0.32Na2O:0.03Al2O3:0.20TPABr:0.16CTMABr:55H2O. The cetyltrimethylammonium bromide (CTMABr) and tetrapropylammonium bromide (TPABr) were used as templates. The above mentioned
material presents morphological properties with specific characteristics, such as the surface area of the composite which
is approximately half of the surface area of the conventional MCM-41. Another interesting feature is the formation of walls
with the double of the density of the MCM-41 structure, which characterizes the hybrid material, resulting in a high stability
material for catalytic application. The aim of this study is obtain optimized structures of the hybrid material and for this
purpose variations in the synthesis time were carried out. A comparative analysis was performed including X-ray diffraction,
Fourier transform infrared spectroscopy, and Thermogravimetry measurements. The model-free kinetic algorithms were applied
in order to determinate conversion and apparent activation energy of the decomposition of the CTMA+ and TPA+ species from the hybrid AlMCM-41/ZSM-5. 相似文献
134.
Pavel Strop Shu-Hui Liu Magdalena Dorywalska Kathy Delaria Russell G. Dushin Thomas-Toan Tran Wei-Hsien Ho Santiago Farias Meritxell Galindo Casas Yasmina Abdiche Dahui Zhou Ramalakshmi Chandrasekaran Caroline Samain Carole Loo Andrea Rossi Mathias Rickert Stellanie Krimm Teresa Wong Arvind Rajpal 《Chemistry & biology》2013,20(2):161-167
Highlights? Site-specific conjugation of diverse payloads can be achieved with transglutaminase ? Efficient conjugation was achieved at multiple positions throughout an antibody ? Site of conjugation has significant impact on ADC stability and pharmacokinetics ? Differences in ADC stability and pharmacokinetics are species dependent 相似文献
135.
E.E. Farias M. Raineri J. Reyna Almandos F.O. Borges 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(15):2463-2468
The spectrum of five-time ionized krypton, Kr VI, was recorded in the 240-2600 Å wavelength range, resulting in 61 new classified lines as transitions between levels of configurations 4p3, 4s25p, 4s4p4d, 4s4p5s and 4s4p5p. All the 18 energy levels belonging to 4s4p5p configuration except one were determined. Eight new energy level values corresponding to configurations 4s4p4f and 4p24d, supported by 26 new classified lines were also determined and used in the interpretation of the observed 4s4p5p configuration. The experimental data were obtained from a capillary-discharge tube and theta pinch light sources. Multiconfiguration Hartree-Fock calculations with relativistic corrections and a least-squares fitted parametric calculation has been carried out. 相似文献
136.
Approximate value iteration is a simple algorithm that combats the curse of dimensionality in dynamic programs by approximating iterates of the classical value iteration algorithm in a spirit reminiscent of statistical regression. Each iteration of this algorithm can be viewed as an application of a modified dynamic programming operator to the current iterate. The hope is that the iterates converge to a fixed point of this operator, which will then serve as a useful approximation of the optimal value function. In this paper, we show that, in general, the modified dynamic programming operator need not possess a fixed point; therefore, approximate value iteration should not be expected to converge. We then propose a variant of approximate value iteration for which the associated operator is guaranteed to possess at least one fixed point. This variant is motivated by studies of temporal-difference (TD) learning, and existence of fixed points implies here existence of stationary points for the ordinary differential equation approximated by a version of TD that incorporates exploration. 相似文献
137.
M. A.A. Monteiro G. A. Farias R. N. Costa Filho N. S. Almeida 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(2):121-126
We study the influence of interface effects on the
magnetostatic modes propagating in a coupled
ferromagnetic/antiferromagnetic bilayer. We assume that the magnetic
layers are thick enough to be described by the bulk parameters and
they are coupled through the interaction between the magnetic
moments located at the interface. We use a phenomenological approach
taking into account the presence of different magnetic layers in the
system to calculate the modified dynamical response of each
material. We use the corrected magnetic permeability of the layers
to obtain a correlation between the interface characteristics and
the physical behavior of the magnetic excitations propagating in the system. 相似文献
138.
139.
V. EymetA.M. Brasil M.El HafiT.L. Farias P.J. Coelho 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,74(6):697-718
The effect of aggregation on soot radiative properties in the infrared region of the spectrum is numerically investigated using Rayleigh-Debye-Gans theory for fractal aggregates (RDG-FA). In order to use the RDG-FA theory for a wide range of aggregate sizes and wavelengths, the predicted phase functions, scattering and absorption coefficients are compared with a more accurate theory, the integral equation formulation for scattering—IEFS. The importance of scattering when compared with absorption is investigated, as well as the effect of aggregation on the phase function shape and on the scattering cross section. It is concluded that in the case of small aggregates formed with small primary particles the scattering coefficient is negligible compared with the absorption coefficient, and scattering and aggregation of primary particles can be ignored. Thus, the Rayleigh approximation can be used leading to isotropic scattering. In the case of large aggregates constituted by large primary particles, aggregation becomes important and the scattering cross section is of the same order of magnitude of the absorption cross section. Moreover, the phase function becomes highly peaked in the forward direction. Therefore, the Rayleigh and the equivalent volume Mie sphere approximations are not valid, and the RDG-FA method emerges as a good compromise between accuracy and simplicity of application. However, radiative transfer calculations between two infinite, parallel, black walls show that scattering may always be neglected in the calculation of total radiative heat source and heat fluxes to the walls. The minor influence of scattering on the accuracy of the predictions is explained by the shift between the spectral region where scattering is important and the region where the spectral radiative heat source is large. 相似文献
140.
Glacio S. Araujo Leonardo J.B.L. Matos Jader O. Fernandes Samuel J.M. Cartaxo Luciana R.B. Gonçalves Fabiano A.N. Fernandes Wladimir R.L. Farias 《Ultrasonics sonochemistry》2013,20(1):95-98
Microalgae have the ability to grow rapidly, synthesize and accumulate large amounts (approximately 20–50% of dry weight) of lipids. A successful and economically viable algae based oil industry will depend on the selection of appropriate microalgal strains and the selection of the most suitable lipid extraction method. In this paper, five extraction methods were evaluated regarding the extraction of lipids from Chlorella vulgaris: Bligh and Dyer, Chen, Folch, Hara and Radin, and Soxhlet. Furthermore, the addition of silica powder was studied to evaluate the introduction of more shear stress to the system as to increase the disruption of cell walls. Among the studied methods, the Bligh and Dyer method assisted by ultrasound resulted in the highest extraction of oil from C. vulgaris (52.5% w/w). Addition of powder silica did not improve the extraction of oil. 相似文献