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601.
Luiz Fernando C. de Oliveira Maurício A. P. Silva Adílson R. Brandão Rodrigo Stephani Carlos Ivan R. de Oliveira Rogéria R. Gonçalves Anne J. Barbosa Hernane S. Barud Younes Messaddeq Sidney J. L. Ribeiro 《Journal of Sol-Gel Science and Technology》2009,50(2):158-163
Amorphous Mn2+ polyphosphate materials were prepared at room temperature through the coacervation of polyphosphate solutions. These new
materials display the typical Mn2+ red emission with a broad band centered at 15,290 cm−1 (bandwidth—1,320 cm−1). Excitation spectra display typical Mn2+ (d5) absorption bands assigned to transitions from the 6A1g ground state to the 4T2g, (4A1g, 4Eg), 4T2g, and 4T1g Mn2+ excited states. Transition energies allow estimating the Mn2+ ligand field strength as intermediate between the one observed in Mn2+ aqueous solutions and the one observed in Mn2+ phosphate glasses. Azo dyes, methyl red and methyl orange, were incorporated into the manganese polyphosphate coacervates
structure. Raman scattering and visible light reflectance results show azo dyes acid forms inside the hydrated polyphosphate
structure and sensitivity to the atmosphere pH. Release of azo dyes species was observed from these new solid hybrid materials
in aqueous medium. 相似文献
602.
C. M. B. M. Barbosa E. Falabella M. J. Mendes N. M. Lima C. A. M. Abreu 《Reaction Kinetics and Catalysis Letters》1999,68(2):291-298
Hydrogenation of sucrose over Ru/NaY, Ru/USY and Ru/CaY catalysts was carried out in a slurry reactor at 135°C and 12 atm.
The catalysts were prepared by ion exchange followed by calcination and reduction. These were characterised as AA, TPR, DTA/TGA,
H2/Chemisorption, CO-FTIR, XRD and t-plot. To describe kinetic product distribution, the 4th order Runge-Kutta method was used for determining the kinetic parameters. 相似文献
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606.
Changing seasonality in Europe’s air temperature 总被引:1,自引:0,他引:1
S. M. Barbosa 《The European physical journal. Special topics》2009,174(1):81-89
607.
M.G.S. Cavalcanti H.R.C. Araújo M.H.S. Paiva G.M. Silva C.C.G.S. Barbosa L.F. Silva F.A. Brayner L.C. Alves 《Micron (Oxford, England : 1993)》2009,40(3):394-400
An alternative to identify the critical processes necessary to the parasite establishment of the host is to focus on the evolutionary stage responsible for the primary invasion, i.e. the infection structure. The objective of this study was to ultrastructurally characterize Schistosoma mansoni cercariae, using cytochemical techniques. In order to identify basic proteins, techniques such as ethanolic phosphotungstic acid (EPTA) and ammoniacal silver staining were used. Calcium sites location was achieved using the Hepler technique and to evidence anionic groups, we used cationic ferritin particles and enzyme treatment with trypsin Vibrio cholerae, chondroitinase and neuraminidase. The EPTA technique highlighted the presence of basic tegument proteins, nucleus and nucleolus from subtegumental cells, inclusion bodies and preacetabular glands. After using ammoniacal silver, we observed a strong staining in all infective larvae, particularly in the nuclei of muscle cells, circular muscle tissue and preacetabular glands. Calcium site locations were shown to be uniform, thereby limiting the inner spaces of the larvae, especially muscle cells. Samples treated with cationized ferritin particles presented strong staining at the cuticular level. Neuraminidase treatment did not alter the stained shape of such particles on the trematode surface. However, trypsin or chondroitinase treatment resulted in absence of staining on the larval surface. This information on the biochemical composition of the infecting S. mansoni larvae provides data for a better understanding of the biology of this parasite and background on the intriguing parasite–host relationship. 相似文献
608.
Nathlia V. Barbosa Estela P. Troiani Qusia G. Silva Andr S. Afonso Ronaldo C. Faria 《Electroanalysis》2019,31(4):766-770
Herein, we reported the detection of dopamine (DA) based on use of a cathodically pretreated polyaniline (PANI) modified electrode. The PANI electrode presents a remarkable change in their electrocatalytic properties after a simple cathodic pretreatment, which consisted in applying a potential of ?0.7 V for 3 s. While the as‐prepared PANI shows no electrochemical response for DA, the cathodically pretreated PANI presented reversible electrochemical responses with well‐defined anodic and cathodic peaks. The electrochemical behavior of DA at the PANI electrode was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under the optimized experimental conditions, the anodic peak currents increased proportionally to the DA concentration, displaying a linear relationship in the concentration range of 0.11 to 1.75×10?4 M with a detection limit of 13.7 μM (3 σ/slope). Recovery studies in pharmaceutical formulations presented values between 98 % and 104 %. The cathodically pretreated PANI electrode was successfully applied for DA detection in real samples of pharmaceutical formulation showing good agreement with spectrometric comparative method. The unexpected easily capability of modulate the electrocatalytic properties of the electropolymerized PANI film using a simple pretreatement was successfully demonstrated. The cathodically pretreatment PANI electrode showed electrochemical responses for DA with excellent selectivity, sensitivity, and high stability. 相似文献
609.
J. G. G. S. Ramos A. F. Macedo-Junior A. L. R. Barbosa 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(11):232
We investigate statistical aspects of the entanglement production for open chaotic mesoscopic billiards in contact with superconducting parts, known as Andreev billiards. The complete distributions of concurrence and entanglement of formation are obtained by using the Altland–Zirnbauer symmetry classes of circular ensembles of scattering matrices, which complements previous studies in chaotic universal billiards belonging to other classes of random matrix theory. Our results show a unique and very peculiar behavior: the realization of entanglement in a Andreev billiard always results in non-separable state, regardless of the time reversal symmetry. The analytical calculations are supported by a numerical Monte Carlo simulation. 相似文献
610.
R. Aldrovandi A. L. Barbosa L. P. Freitas 《International Journal of Theoretical Physics》1997,36(12):3021-3050
A simple procedure to obtain complete, closed expressions for Lie algebra invariants is presented. The invariants are ultimately
polynomials in the group parameters. The construction of finite group elements requires the use of projectors, whose coefficients
are invariant polynomials. The detailed general forms of these projectors are given. Closed expressions for finite Lorentz
transformations, both homogeneous and inhomogeneous, as well as for Galilei transformations, are found as examples. 相似文献