排序方式: 共有39条查询结果,搜索用时 15 毫秒
1.
Rodella Cristiane B. Franco Roberto W.A. Magon Claudio J. Donoso Jose P. Nunes Luis A.O. Saeki Margarida J. Aegerter Michel A. Sargentelli Vagner Florentino Ariovaldo O. 《Journal of Sol-Gel Science and Technology》2002,25(1):83-88
Raman spectroscopy and Electron Paramagnetic Resonance (EPR) studies were performed on a series of V2O5/TiO2 catalysts prepared by a modified sol-gel method in order to identify the vanadium species. Two species of surface vanadium were identified by Raman measurements, monomeric vanadyls and polymeric vanadates. Monomeric vanadyls are characterized by a narrow Raman band at 1030 cm–1 and polymeric vanadates by two broad bands in the region from 900 to 960 cm–1 and 770 to 850 cm–1. The Raman spectra do not exhibit characteristic peaks of crystalline V2O5. These results are in agreement with those of X-ray Diffractometry (XRD) and Fourier Transform Infrared (FT-IR) previously reported (C.B. Rodella et al., J. Sol-Gel Sci. Techn., submitted). At least three families of V4+ ions were identified by EPR investigations. The analysis of the EPR spectra suggests that isolated V4+ ions are located in sites with octahedral symmetry substituting for Ti4+ ions in the rutile structure. Magnetically interacting V4+ ions are also present as pairs or clusters giving rise to a broad and structureless EPR line. At higher concentration of V2O5, a partial oxidation of V4+ to V5+ is apparent from the EPR results. 相似文献
2.
We report in this work a fast protocol for protein quantification and for peptide mass mapping that rely on 18O isotopic labeling through the decoupling procedure. It is demonstrated that the purity and source of trypsin do not compromise the labeling degree and efficiency of the decoupled labeling reaction, and that the pH of the labeling reaction is a critical factor to obtain a significant 18O double labeling. We also show that the same calibration curve can be used for MALDI protein quantification during several days maintaining a reasonable accuracy, thus simplifying the handling of the quantification process. In addition we demonstrate that 18O isotopic labeling through the decoupling procedure can be successfully used to elaborate peptide mass maps. BSA was successfully quantified using the same calibration curve in different days and plasma from a freshwater fish, Cyprinus carpio, was used to elaborate the peptide mass maps. 相似文献
3.
Santos HM Glez-Peña D Reboiro-Jato M Fdez-Riverola F Diniz MS Lodeiro C Capelo-Martínez JL 《Electrophoresis》2010,31(20):3407-3419
In the present work we report on a novel and fast protocol for accurate bottom-up protein quantification that overcomes the drawbacks of in-gel digestion and MALDI analysis, while maintaining their benefits. It relies on the following steps: (i) gel electrophoresis separation of proteins, (ii) fast in-gel protein digestion with trypsin, (iii) (18)O-labeling through the decoupled method, (iv) quantification through selected peptides previously chosen using the (18)O inverse labeling approach and that, finally, (v) it takes advantage of software specifically developed to select the peptides that will drive the quantification of the protein in an automated mode. We have accurately quantified the following six proteins: glycogen phosphorylase, BSA, ovalbumin, carbonic anhydrase, trypsin inhibitor, and α-lactalbumin. As a case study we have quantified the protein vitellogenin in plasma of Cyprinus carpio exposed to high levels of estrogens. The proposed new protocol was validated against the traditional ELISA method; both were found to provide comparable results (non-parametric Mann-Whitney U-test). 相似文献
4.
Juan de Dios Pérez Florentino G. Santos 《Differential Geometry and its Applications》2005,22(2):181-188
We classify real hypersurfaces in complex projective spaces whose structure Jacobi operator is Lie parallel in the direction of the structure vector field. 相似文献
5.
Carlos A. A. Florentino 《Geometriae Dedicata》2006,121(1):167-186
We obtain an explicit characterization of the stable points of the action of on the cartesian product G
× n
by simultaneous conjugation on each factor in terms of the corresponding invariant functions. From this, a simple criterion
for the irreducibility of representations of finitely generated groups into G is derived. We also obtain analogous results for the action of on the vector space of n-tuples of 2 × 2 complex matrices. For a free group F
n
of rank n, we show how to generically reconstruct the 2
n-2 conjugacy classes of representations F
n
→ G from their values under the map considered in Magnus [Math. Zeit. 170, 91–103 (1980)], defined by certain 3n − 3 traces of words of length one and two.
相似文献
6.
Nanograin sizes and crystal lattice microstrains in nanocrystalline materials are typically evaluated from the broadening of their x-ray diffraction (XRD) peaks under the assumption of symmetrical diffraction profiles. Since this assumption is not entirely satisfactory, we formulate a line-broadening analysis model of a single peak that considers explicitly the XRD peak asymmetry. The model is a generalization of the variance method in which the shape of the XRD peaks is idealized through asymmetrical split pseudo-Voigt functions. The model is validated on two nanocrystalline powders. 相似文献
7.
Carlos Florentino 《manuscripta mathematica》2001,105(1):69-83
We study a natural map from representations of a free group of rank g in GL(n,ℂ), to holomorphic vector bundles of degree 0 over a compact Riemann surface X of genus g, associated with a Schottky uniformization of X. Maximally unstable flat bundles are shown to arise in this way. We give a necessary and sufficient condition for this map
to be a submersion, when restricted to representations producing stable bundles. Using a generalized version of Riemann's
bilinear relations, this condition is shown to be true on the subspace of unitary Schottky representations.
Received: 13 June 2000 / Revised version: 29 December 2000 相似文献
8.
Aliano Filho Angelo de Oliveira Florentino Helenice Pato Margarida Vaz Poltroniere Snia Cristina da Silva Costa Joo Fernando 《Annals of Operations Research》2022,314(2):347-376
Annals of Operations Research - This work proposes a binary nonlinear bi-objective optimization model for the problem of planning the sustainable cultivation of crops. The solution to the problem... 相似文献
9.
10.
Rafael González Florentino Murrieta-Guevara Arturo Trejo 《Journal of solution chemistry》1986,15(10):791-801
We present in this work the results of measurements of excess volumes of mixing V
E
at 30°C over the whole composition range for sixteen mixtures of n-hexanenitrile, n-octanenitrile, n-decanenitrile, and n-dodecanenitrile mixed individually with n-heptane, n-decane, n-tridecane, and n-hexadecane. The experimental values of V
E
show a regular pattern of behavior for the four sets of binary systems. In each group of mixtures for a given n-alkanenitrile, the magnitude of V
E
decreases as the n-alkane chain-length decreases. For mixtures containing a common n-alkane, V
E
decreases with increasing n-alkanenitrile chain-length. In order to explain the observed behavior, we have used the Prigogine-Flory-Patterson theory, which divides V
E
into three different contributions. The agreement between the theoretical and experimental V
E
is reasonable for the systems studied. 相似文献