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71.
Barton Ivo Matejec Vlastimil Jan Mrazek Podrazky Ondrej Matousek Josef 《Journal of Sol-Gel Science and Technology》2017,81(3):867-879
Journal of Sol-Gel Science and Technology - The paper presents results on sol–gel preparation and characterization of multilayered coatings, Bragg mirrors, on silica slides, silica fibers,... 相似文献
72.
73.
The palladium-catalyzed, hydroxyl-directed cyclization reactions of 1,6-enynes provide a highly diastereoselective process for the syntheses of stereochemically defined cyclopentanes. Consistently high levels of cis-selectivity are possible using homopropargyl alcohols in contrast to the corresponding propargyl alcohols. Hydroborylative enyne cyclizations coupled with this directing group effect provide a useful method for the syntheses of multifaceted compounds bearing all carbon quaternary centers. 相似文献
74.
Cells respond to and are directed by physiochemical cues in their microenvironment, including geometry and substrate stiffness. The development of substrates for cell culture with precisely controlled physiochemical characteristics has the potential to advance the understanding of cell biology considerably. In this communication, E-jet printing is introduced as a method for creating high-resolution protein patterns on substrates with controlled elasticity. It is the first application of E-jet printing on a soft surface. Protein spots as small as 5 μm in diameter on polyacrylamide are demonstrated. The patterned hydrogels are shown to support cell attachment and spreading. Polyacrylamide substrates patterned by E-jet printing may be applied to further the study of cellular mechanobiology. 相似文献
75.
Convex and concave relaxations are used extensively in global optimization algorithms. Among the various techniques available
for generating relaxations of a given function, McCormick’s relaxations are attractive due to the recursive nature of their
definition, which affords wide applicability and easy implementation computationally. Furthermore, these relaxations are typically
stronger than those resulting from convexification or linearization procedures. This article leverages the recursive nature
of McCormick’s relaxations to define a generalized form which both affords a new framework within which to analyze the properties
of McCormick’s relaxations, and extends the applicability of McCormick’s technique to challenging open problems in global
optimization. Specifically, relaxations of the parametric solutions of ordinary differential equations are considered in detail,
and prospects for relaxations of the parametric solutions of nonlinear algebraic equations are discussed. For the case of
ODEs, a complete computational procedure for evaluating convex and concave relaxations of the parametric solutions is described.
Through McCormick’s composition rule, these relaxations may be used to construct relaxations for very general optimal control
problems. 相似文献
76.
77.
The evolution of several structural characteristics during isothermal heat treatment of poly(p-phenylene terephthalamide) was studied. In this work, heat treatment was interrupted after different treatment times, with the specimens immediately quenched to room temperature. These specimens were then characterized by tensile testing, wide- and small-angle x-ray scattering, and optical microscopy. Structural parameters obtained from these measurements relate to crystal perfection (via the paracrystalline axial distortion parameter), axial crystallite size, transverse crystallite size, degree of chain misorientation, and degree of pleating. Structural and mechanical parameters were then plotted against heat-treatment time to obtain kinetic isotherms for each parameter. The kinetics of the removal of chain misorientation parallels that of tensile modulus increase under all conditions. Of the other structural parameters, only the kinetics of pleat removal mimics that of modulus change, indicating that pleat removal is the effective cause of increased chain alignment and thereby of increased axial stiffness. ©1995 John Wiley & Sons, Inc. 相似文献
78.
79.
A two-parameter family of supersymmetric background field solutions of the recently formulated version of gauged N = 4 supergravity is found. This constitutes strong evidence that the theory has stable vacua, despite energy densities that are unbounded below. The background geometries are metric products of (AdS)2 × S2, and there are covariantly constant magnetic and electric fields. For a special choice of parameters the (AdS)2 factor becomes a flat Minkowski space and electric fields vanish. 相似文献
80.
Tributylphosphine-diphenyldisulphide reduces nitroalkanes to imines which can be trapped intramolecularly to give pyrroles. 相似文献