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61.
62.
Miguel Gd Pérez-Morales M Martín-Romero MT Muñoz E Richardson TH Camacho L 《Langmuir : the ACS journal of surfaces and colloids》2007,23(7):3794-3801
The molecular organization of a mixed film, containing a water-soluble tetracationic porphyrin (TMPyP) and a p-tert-butyl calix[8]arene octacarboxylic acid derivative (C8A), at the air-water interface and on a solid support (LB film), has been investigated. Although the TMPyP aggregation was not detected at the air-water interface, TMPyP J-aggregates have been found in the LB films (Y-type). Unlike tetraanionic porphyrins, for example TSPP, the TMPyP J-aggregates are not induced by a zwitterion formation. The TMPyP J-aggregation is a result of a "double comb" configuration, where porphyrins from opposite layers are interwoven in a linear infinite J-aggregate. Our results confirm that TMPyP molecules tend to self-aggregate strongly, provided the electrostatic repulsions of their peripheral groups are cancelled by the anionic groups of the C8A matrix. 相似文献
63.
Ismael Herrera Rodolfo G. Camacho 《Numerical Methods for Partial Differential Equations》1997,13(1):1-18
Here, it is shown that the “traditional approach” to variable bubble-point problems, using black-oil models, is not consistent, because it violates the “bubble-point conservation law.” In order to have a consistent approach, it is necessary to incorporate shocks—discussed in previous papers—in which the bubble-point is discontinuous. A “consistent approach” is applied to specific examples, and results compared with those of the “traditional” one. The conclusion that the “traditional approach” generally yields large errors for the production rates and other parameters of interest in the oil industry, is reached. © 1997 John Wiley & Sons, Inc. 相似文献
64.
J. J. Camacho M. Santos L. Díaz J. M. L. Poyato 《Applied Physics A: Materials Science & Processing》2009,94(2):373-380
We have used ferrocene and paraffin wax as novel precursor and solvent for the growth of iron oxide nanoparticles. The proposed
method of growth has several advantages over existing methods of growth using iron pentacarbonyl a precursor. Highly crystalline
and monodispersed particles are obtained which assemble in two- and three-dimensional hexagonal closed packed superlattices.
Growth kinetics has been studied by varying concentration of the precursor and time of growth. A phenomenological model has
been proposed to explain the growth kinetics. 相似文献
65.
C. Albano N. Camacho M. Hernández A. Matheus A. Gutiérrez 《Macromolecular Symposia》2009,286(1):195-202
Lightweight aggregate is an important material in reducing the unit weight of concrete and it is essential in the construction of high-rise buildings; besides, the use of recycled PET bottles as lightweight aggregate in concrete is an effective contribution for environmental preservation. So, the objective of the present work is to study the flexural strength of PET-concrete and PET thermal degradation in the concrete, when the blends with 10 and 20 vol% of PET are exposed to different temperatures (200, 400, 600 °C). The flexural strength of PET-concrete exposed to a heat source is strongly dependent on the temperature, the water/cement ratio, as well as on the content and particle size of PET. Furthermore, the activation energy for PET degradation is affected by temperature, location of PET particles on the slabs and the water/cement ratio. A higher content of water gives rise to hydrolytic degradation on PET and a higher vapor pressure that increases the formation of cracks on the concrete. The values of activation energy are higher on the center of the slabs than on the surface, due to the poor heat conduction of concrete. 相似文献
66.
In this paper we present recent results concerning global aspects of and -actions on Stein surfaces. Our approach is based on a byproduct of techniques from Geometric Theory of Foliations (holonomy,
stability), Potential theory (parabolic Riemann surfaces, Riemann-Koebe Uniformization theorem) and Several Complex Variables
(Hartogs’ extension theorems, Theory of Stein spaces). Our main motivation comes from the original works of M. Suzuki and
Orlik-Wagreich. Some of their results are extended to a more general framework. In particular, we prove some linearization
theorems for holomorphic actions of and on normal Stein analytic spaces of dimension two. We also add a list of questions and open problems in the subject. The underlying
idea is to present the state of the art of this research field.
相似文献
67.
We study and classify actions of the complex multiplicative group on a nonsingular Stein surface with an isolated nondicritical
singularity. We prove that the corresponding foliation exhibits a holomorphic first integral of a type F = f
n
g
m
where f and g are global holomorphic functions and . Under some additional conditions on the functions f and g we prove analytic linearization for the action. Our results can be viewed as extension of the original work of Masakazu Suzuki. 相似文献
68.
In this article we study good ℂ* actions on Stein surfaces and we construct their moduli by means of the resolution data of the dicritical singularity of
the action. We also classify ℂ* transversal actions around a Riemann surface embedded in a two dimensional manifold.
相似文献
69.
Jorge F. Camacho Rosalío F. Rodríguez 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(2):21
We use a fluctuating hydrodynamics (FH) approach to study the fluctuations of the hydrodynamic variables of a thermotropic nematic liquid crystal (NLC)in a nonequilibrium steady state (NESS). This NESS is produced by an externally imposed temperature gradient and a uniform gravity field. We calculate analytically the equilibrium and nonequilibrium seven modes of the NLC in this NESS. These modes consist of a pair of sound modes, one orientation mode of the director and two visco-heat modes formed by the coupling of the shear and thermal modes. We find that the nonequilibrium effects produced by the external gradients only affect the longitudinal modes. The analytic expressions for the visco-heat modes show explicitly how the heat and shear modes of the NLC are coupled. We show that they may become propagative, a feature that also occurs in the simple fluid and suggests the realization of new experiments. We show that in equilibrium and in the isotropic limit of the NLC, our modes reduce to well-known results in the literature. For the NESS considered we point out the differences between our our modes and those reported by other authors. We close the paper by proposing the calculation of other physical quantities that lend themselves to a more direct comparison with possible experiments for this system. 相似文献
70.
Chan y Díaz E. Duarte-Moller A. Camacho Juan M. Castro-Rodríguez R. 《Applied Physics A: Materials Science & Processing》2012,106(3):619-624
SnO2 thin films have been deposited on glass substrates by pulsed Nd:YAG laser at different oxygen pressures, and the effects
of oxygen pressure on the physical properties of SnO2 films have been investigated. The films were deposited at substrate temperature of 500°C in oxygen partial pressure between
5.0 and 125 mTorr. The thin films deposited between 5.0 to 50 mTorr showed evidence of diffraction peaks, but increasing the
oxygen pressure up to 100 mTorr, three diffraction peaks (110), (101) and (211) were observed containing the SnO2 tetragonal structure. The electrical resistivity was very sensitive to the oxygen pressure. At 100 mTorr the films showed
electrical resistivity of 4×10−2 Ω cm, free carrier density of 1.03×1019 cm−3, mobility of 10.26 cm2 V−1 s−1 with average visible transmittance of ∼87%, and optical band gap of 3.6 eV. 相似文献