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31.
Ferreira H Lúcio M Lima JL Matos C Reis S 《Analytical and bioanalytical chemistry》2005,382(5):1256-1264
In this work the interaction of a non-steroidal anti-inflammatory drug (NSAID), diclofenac, with egg yolk phosphatidylcoline (EPC) liposomes, used as cell-membrane models, was quantified by determination of the partition coefficient. The liposome/aqueous phase partition coefficient was determined by derivative spectrophotometry, fluorescence quenching, and measurement of zeta-potential. Theoretical models based on simple partition of the diclofenac between two different media, were used to fit the experimental data, enabling the determination of Kp. The three techniques used yielded similar results. The effects of the interaction on the membranes characteristics were further evaluated, either by studying membrane potential changes or by effects on membrane fluidity. The liposome membrane potential and the size and size-homogeneity of liposomes were measured by light scattering. The effects of diclofenac on the internal viscosity or fluidity of the membrane were determined by use of spectroscopic probes—a series of n-(9-anthroyloxy) fatty acids in which the carboxyl terminal group is located at the interfacial region of the membrane and the fluorescent anthracene group is attached at different positions along the fatty acid chain. The location of the diclofenac on the membrane was also evaluated, by fluorescence quenching using the same series of fluorescent probes. Because the fluorescent anthracene group is attached at different positions along the fatty acid chain, it is possible to label at a graded series of depths in the bilayer. The interactions between the drug and the probe are a means of predicting the location of the drug on the membrane. 相似文献
32.
Frontispiece: Enantioselective Organocatalytic Cascade Approach to Different Classes of Benzofused Acetals
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33.
Tonatiuh Matos Darío Núñez F. Siddhartha Guzmán Erandy Ramírez 《General Relativity and Gravitation》2002,34(2):283-305
In an arbitrary axisymmetric stationary spacetime, we determine the expression for the tangential velocity of test objects following a circular stable geodesic motion in the equatorial plane, as function of the metric coefficients. Next, we impose the condition, observed in large samples of disks galaxies, that the magnitude of such tangential velocity be radii independent in the dark matter dominated region, obtaining a constraint equation among the metric coefficients, and thus arriving to an iff (iff means: if and only if.) condition: The tangential velocity of test particles is radii independent iff the metric coefficients satisfied the mentioned constraint equation. Furthermore, for the static case, the constraint equation can be easily integrated, leaving the spacetime at the equatorial plane essentially with only one independent metric coefficient. With the geometry thus fixed, we compute the Einstein tensor and equate it to an arbitrary stress energy tensor, in order to determine the type of energy-matter which could produce such a geometry. Within an approximation, we deduce a constraint equation among the components of the stress energy tensor. We test in that constraint equation several well known types of matter, which have been proposed as dark matter candidates and are able to point for possible right ones. Finally, we also present the spherically symmetric static case and apply the mentioned procedure to perfect fluid stress energy tensor, recovering the Newtonian result as well as the one obtained in the axisymmetric case. We also present arguments on the need to use GR to study types of matter different than the dust one. 相似文献
34.
A 21.7-km nonzero dispersion-shifted fiber was used to obtain 4x multiplication of the repetition rate of a 20-GHz train of 4.2-ps optical pulses through the temporal Talbot effect. Raman compression in the same fiber shortened and developed the pulses into 2.0-ps solitons and resulted in a lower duty cycle. It is shown that the linear Talbot effect and nonlinear Raman compression occurred in different sections of the fiber, the lengths of which could be varied through adjustments in the input pulse power. 相似文献
35.
Continuous-wave-pumped Raman-assisted fiber optical parametric amplifier and wavelength converter in conventional dispersion-shifted fiber 总被引:1,自引:0,他引:1
We present a continuous-wave-pumped fiber optical parametric amplifier, operating near 1539 nm in conventional dispersion-shifted fiber, with maximum on-off gain and wavelength-conversion efficiency of 13.7 and 13.1 dB, respectively. In addition, we show a novel configuration based on Raman amplification assistance in the parametric gain fiber that further increases the gain and wavelength-conversion efficiencies to 16.7 and 16.2 dB, respectively. 相似文献
36.
We propose a scheme for producing large Fock states in cavity QED via the implementation of a highly selective atom-field interaction. It is based on Raman excitation of a three-level atom by a classical field and a quantized field mode. Selectivity appears when one tunes to resonance a specific transition inside a chosen atom-field subspace, while other transitions remain dispersive, as a consequence of the field dependent electronic energy shifts. We show that this scheme can be also employed for reconstructing, in a new and efficient way, the Wigner function of the cavity field state. 相似文献
37.
J. S. Matos J. L. Trenzado E. Romano M. N. Caro M. E. Pérez 《Journal of solution chemistry》2001,30(3):263-279
Excess molar volumes, at the temperature 25°C and atmospheric pressure over the whole composition range, are reported for the following binary mixtures: methyl ethanoate + (n-octane, n-decane); methyl ethanoate + 1-chlorooctane; 1-chlorooctane + (n-heptane, n-octane, n-nonane, n-decane); and for the ternary mixtures methyl ethanoate + 1-chlorooctane + (n-heptane, n-octane, n-nonane, n-decane). The values of excess molar volumes were calculated from density and composition results. The excess volumes were utilized to test the multiproperty group-contribution model of Nitta et al. using parameter sets available in the literature. Experimental results from ternary mixtures have also been compared to predictions from several empirical and semiempirical models, which utilize, exclusively, results from binary mixtures. 相似文献
38.
Oscar García Josep Vehí Jose Campos e Matos António Abel Henriques Joan Ramon Casas 《Journal of Computational and Applied Mathematics》2008
An efficient health monitoring system for damage detection in civil engineering structures using on-line monitoring data is being developed to identify any possible damage in short time. The present work is based on the treatment of uncertainties, which is one of the basic common difficulties faced when modelling structures. A methodology, based on interval analysis (IA) theory [R.E. Moore, Interval Analysis, Prentice-Hall, Englewood Cliffs, NJ, 1966] applied to a numerical constraint satisfaction problem (CSP) [J.R. Casas, J.C. Matos, J.A. Figueiras, J. Vehí, O. García, P. Herrero, Bridge monitoring and assessment under uncertainty via interval analysis, in: Ninth International Conference On Structural Safety And Reliability—ICOSSAR2005, 2005. pp. 487–494], is implemented in the damage detection [J.R. Casas, J.C. Matos, J.A. Figueiras, J. Vehí, O. García, P. Herrero, Bridge monitoring and assessment under uncertainty via interval analysis, in: Ninth International Conference On Structural Safety And Reliability—ICOSSAR2005, 2005. pp. 487–494] and modelling system of a long-term monitoring project in order to achieve such an objective. An algorithm is being developed for using such methodology with the obtained data. 相似文献
39.
40.
Stephan Matos Camacho 《Discrete Mathematics》2009,309(15):4916-4919
In 1992 Gyárfás showed that a graph G having only k odd cycle lengths is (2k+1)-colourable, if it does not contain a K2k+2. In this paper, we will present the results for graphs containing only odd cycles of length 2m−1 and 2m+1 as done in [S. Matos Camacho, Colourings of graph with prescribed cycle lengths, diploma thesis, TU Bergakademie Freiberg, 2006. [3]]. We will show that these graphs are 4-colourable. 相似文献