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排序方式: 共有159条查询结果,搜索用时 15 毫秒
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Ricardo Molina Miguel Gómez Chi-Wai Kan Enric Bertran 《Cellulose (London, England)》2014,21(1):729-739
Materials with hydrophilic–oleophobic properties are of relevance due to their application to different fields such as self-cleaning coatings, liquid–liquid separation membranes and functional textiles for different technical applications. In this work, hydrophilic–oleophobic coatings have been deposited on cellulosic materials (filter paper and bleached cotton) by means of plasma assisted polymerization of acrylic acid solutions in water followed by cationic fluorosurfactant complexation. Chemical composition of the coatings on cellulosic materials was characterized by means of FTIR–ATR and XPS whereas their morphology was studied by SEM. Hydrophilic–oleophobic behavior was characterized by means of contact angle and wetting time. Additionally wetting properties of cationic, anionic and non-ionic surfactant solutions on the hydrophilic–oleophobic coatings were used to characterize the polyelectrolyte electrostatic forces upon the functionalized layer. 相似文献
3.
This article considers the analytical approximation of limit cycles that may appear in Abel equations written in the normal form. The procedure uses an iterative approach that takes advantage of the contraction mapping theorem. Thus, the obtained sequence exhibits uniform convergence to the target periodic solution. The effectiveness of the technique is illustrated through the approximation of an unstable limit cycle that appears in an Abel equation arising in a tracking control problem that affects an elementary, second-order bilinear power converter. 相似文献
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Supported by Grant PB 85-0075 from CAICYT. 相似文献
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Motivated by some functional models arising in fuzzy logic, when classical boolean relations between sets are generalized,
we study the functional equation S(S(x, y), T(x, y)) = S(x, y), where S is a continuous t-conorm and T is a continuous t-norm. Some interesting methods for solving this type of equations are introduced. 相似文献
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David Vignolles Alain Audouard Rustem B. Lyubovskii Sergei I. Pesotskii Jrme Bard Enric Canadell Gena V. Shilov Olga A. Bogdanova Elena I. Zhilayeva Rimma N. Lyubovskaya 《Solid State Sciences》2007,9(12):1140-1148
The organic metal θ-(BETS)4HgBr4(C6H5Cl) is known to undergo a phase transition as the temperature is lowered down to about 240 K. X-ray data obtained at 200 K indicate a corresponding modification of the crystal structure, the symmetry of which is lowered from quadratic to monoclinic. In addition, two different types of cation layers are observed in the unit cell. The Fermi surface (FS), which can be regarded as a network of compensated electron and hole orbits according to band structure calculations at room temperature, turns to a set of two alternating linear chains of orbits at low temperature. The field and temperature dependence of the Shubnikov-de Haas oscillation spectrum have been studied up to 54 T. Eight frequencies are observed which, in any case, point to an FS much more complex than predicted by band structure calculations at room temperature, even though some of the observed Fourier components might be ascribed to magnetic breakdown or frequency mixing. The obtained spectrum could result from either an interaction between the FSs linked to each of the two cation layers or to an eventual additional phase transition in the temperature range below 200 K. 相似文献
10.
M. Iuga G. Steinle-Neumann J. Meinhardt 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(2):127-133
Athermal elasticity for some ceramic materials (α-Al2O3,
SiC (α and β phases), TiO2 (rutile and anatase),
hexagonal AlN and TiB2, cubic BN and CaF2, and monoclinic
ZrO2) have been investigated via density functional theory.
Energy-volume equation-of-state computations to obtain the zero pressure
equilibrium volume and bulk modulus as well as computations of the full
elastic constant tensor of these ceramics at the experimental zero pressure
volume have been performed. The present results for the single crystal
elasticity are in good agreement with experiments both for the aggregate
properties (bulk and shear modulus) and the elastic anisotropy. In contrast,
a considerable discrepancy for the zero pressure bulk modulus of some
ceramics evaluated from the energy-volume fit to the computational zero
pressure volume has been observed. 相似文献