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251.
Luis M. Reyes Geraldo M. Ribeiro Benedicto J.O. Franco JoséLuiz A. Alves Manoel L. de Siqueira 《Solid State Communications》1981,40(12):1031-1034
We have interpreted the KCl:Cu? spectrum in the context of the MS-Xα method. The results, considering only allowed electric-dipole transitions, are in good agreement with the experimental data. Four new absorption bands, peaking at 573, 390, ~324 and ~310nm, at room temperature, are reported. 相似文献
252.
Alves GA Amato S Anjos JC Appel JA Bracker SB Cremaldi LM Darling CL Dixon RL Errede D Fenker HC Gay C Green DR Jedicke R Kaplan D Karchin PE Kwan S Leedom I Lueking LH Luste GJ Mantsch PM de Mello Neto JR Metheny J Milburn RH de Miranda JM da Motta Filho H Napier A Rafatian A dos Reis AC Reucroft S Ross WR Santoro AF Sheaff M Souza MH Spalding WJ Stoughton C Streetman ME Summers DJ Takach SF Wu Z 《Physical review letters》1993,70(6):722-725
253.
A comparison is made between calculations performed nonrelativistically and relativistically for W, Re, Os, Ir, Pt, Au and Hg as substitutional impurities in silicon. The calculations were carried out using the relativistic extended Hückel method. The direct and indirect relativistic effects upon the 5d-like levels and band-gap levels are analysed. 相似文献
254.
255.
M. Alves Marques M. I. de Barros Marques M. Isabel Cabao A. M. Gaspar M. L. de Almeida 《Journal of Molecular Liquids》2004,110(1-3):23-31
Concentrated aqueous solutions of copper nitrate of different concentrations (0.66 mol dm−3 up to 4.84 mol dm−3) have been investigated by X-ray diffraction at room temperature. In these solutions a maximum of intensity (prepeak) is observed at low values of Q (approx. 0.6 to 1 Å−1) suggesting the existence of an intermediate range order in their structure, in agreement with previous investigations on different electrolytes. In order to get information on the solvation shell of the copper cation, Raman spectroscopy experiments have been performed for the more concentrated solution. Polarization observations, isotopic substitution of the solvent and the comparison with a Raman spectrum of a concentrated aqueous solution of aluminum nitrate were performed in order to improve the interpretation of the obtained results with these convergent observations. 相似文献
256.
A. M. Gaspar M. Alves Marques M. I. Cabao M. I. de Barros Marques T. Buslaps V. Honkimaki 《Journal of Molecular Liquids》2004,110(1-3):15-22
Concentrated aqueous solutions of calcium chloride and calcium bromide have been investigated by X-ray diffraction. In the diffraction patterns of aqueous chloride solutions of different concentrations, a maximum of intensity is observed in the region 0.6–1.1 Å−1, while in the investigated aqueous bromide solution no maximum is observed in that region. This pre-peak suggests the existence of positional correlations in solution beyond direct contact. The interpretation is similar to the one proposed by the authors in previous investigations, and is supported by the calculations based on ad hoc molecular models. The influence of the anion is discussed. 相似文献
257.
J. A. Alves da Silva E. Muramoto M. T. C. P. Ribela J. R. Rogero M. A. P. Camillo 《Journal of Radioanalytical and Nuclear Chemistry》2006,269(3):579-583
Summary The use of radiotracers in the research of animal venom has been scarce, although it allows an excellent approach to follow
the process of bioavailability, biodistribution and kinetics of toxins. The purpose of this study was to assess gyroxin action
mechanism, transport, compartments and action sites. This toxin is a thrombin-like and causes the barrel rotation syndrome.
The gyroxin was labeled with 125I and used as a tracer for the in vivo assay in mice. Blood samples and organs were collected at different time intervals,
weighed and analyzed in a gamma-counter. The data was related with tissues distribution of protease activated receptor (PAR).
Biodistribution assay allowed dividing the organs into three groups. The first one with the organs that followed the blood
kinetics, the second with the organs related to metabolisms and elimination, and the third with the organs in which the gyroxin
concentration increased during the observation period. 相似文献
258.
M. C. Nunes P. Batista A. Raymundo M. M. Alves I. Sousa 《Colloids and surfaces. B, Biointerfaces》2003,31(1-4):21-29
In recent years, interest in animal free foods has increased tremendously due to factors like BSE crisis, rise of nutritionally dependent illnesses, like diabetes type II, cardiovascular and digestive diseases, along with ethic orientations of denying animal intakes of any kind. The use of proteins from leguminous seeds as an alternative to the animal proteins in dairy desserts was studied. Lupin, pea and soya protein isolates were used in combination with κ-carrageenan, gellan and xanthan gum, in order to obtain a synergistic effect. Milk puddings were also produced for comparison. Texture studies suggested that mixed protein–polysaccharide systems, with vegetable proteins and κ-carrageenan or gellan gum, would be good systems to develop vegetable gelled desserts. Rheological oscillatory measurements were carried out to clarify the kinetics of gelation and characterise the microstructure of the best performing products. Results from time sweep tests showed that formulations with gellan gum present an industrial advantage over formulations with κ-carrageenan, since the maturation time for gellan gels is of the order of 5–10 h compared with 4–6 days in the case of κ-carrageenan. All the mixed gels presented the typical weak gel structure; therefore, it was possible to perform steady-state measurements, which allowed the observation of a shear-thinning behaviour for all gels. 相似文献
259.
Câmara JS Marques JC Alves A Ferreira AC 《Analytical and bioanalytical chemistry》2003,375(8):1221-1224
The maturation of Madeira wines usually involves exposure to relatively high temperatures which affect the aroma and flavour composition leading to the formation of the typical and characteristic bouquet of these wines. The formation of heterocyclic acetals (1,3-dioxanes and 1,3-dioxolanes) was investigated in order to determine levels and for possible use as indicators of wine age. The results show a linear correlation of the investigated acetals with wine age but suggest that the acetalization reaction is not particularly affected by the drastic oxidative conditions observed during maturation. 相似文献
260.
A new procedure to produce the BrO(2) transient species allowed time-resolved UV-vis spectra that show a structured band (lambda(max) = 502 nm) in dichloromethane to be obtained. In water, because of the increase of the dielectric constant, the lambda(max) presents a blue shift to 474 nm and the species decomposes much faster. The time-resolved spectra show evidence for its equilibrium with a nonidentified colorless form. This route opens new possibilities to the study this species in solution. 相似文献