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Hershkovits E Tannenbaum A Tannenbaum R 《The journal of physical chemistry. B》2008,112(17):5317-5326
In this paper, we have developed a geometric-based scaling model that describes the adsorption of diblock copolymer chains from good solvents and theta-solvents onto reactive surfaces of varying curvatures. To evaluate the impact of particle size on the adsorption process, we probed the adsorption of poly(styrene-b-methymethacrylate) (PS-PMMA) diblock copolymers from solvents with different degrees of selectivity on aluminum oxide (Al(2)O(3)) surfaces belonging to particles of different sizes. When the adsorbed PMMA layer is dense enough (in the case of a theta-solvent for the PMMA block), our results show good correlation between the theory and experimental results, pointing to the formation of a PMMA adsorption layer and a brushlike PS layer. Conversely, when adsorption occurs from a nonpreferential solvent, particularly on particles with high curvature, the PMMA adsorption layer at the surface becomes less dense and the grafted PS moiety exhibits a transitional morphology consisting of several layers of increasingly sparsely spaced blobs. 相似文献
95.
Peleg O Bartal G Freedman B Manela O Segev M Christodoulides DN 《Physical review letters》2007,98(10):103901
We study wave dynamics in honeycomb photonic lattices, and demonstrate the unique phenomenon of conical diffraction around the singular diabolical (zero-effective-mass) points connecting the first and second bands. This constitutes the prediction and first experimental observation of conical diffraction arising solely from a periodic potential. It is also the first study on k space singularities in photonic lattices. In addition, we demonstrate "honeycomb gap solitons" residing in the gap between the second and the third bands, reflecting the special properties of these lattices. 相似文献
96.
Seyed?Hassan?AlaviEmail authorView authors OrcID profile Ashraf?Daneshkhah 《Monatshefte für Mathematik》2017,184(2):175-184
An element of a group G is called semi-rational if all generators of \(\langle x\rangle \) lie in the union of two conjugacy classes of G. If all elements of G are semi-rational, then G is called a semi-rational group. In this paper, we determine all semi-rational simple groups. Our study in this article generalises Feit and Seitz’s result (Ill J Math 33(1):103–131, 1989) to semi-rational groups. 相似文献
97.
The use of bioadhesives and sealants for wound closure and healing applications is becoming more and more popular, particularly when other techniques, such as stapling or suturing, are impractical or inefficient. Loading adhesives with fibers has tremendous potential for improving their mechanical properties. The concept of fiber‐reinforced bioadhesives and sealants is novel and has not been investigated to date. In the present study, natural cellulose fibers were selected for enhancement of bioadhesive properties. A bioadhesive formulation based on a combination of gelatin and alginate crosslinked with water‐soluble carbodiimide was used as a generic formulation for this study, on the basis of our previous studies. The polymeric matrix and the cellulose fibers showed high affinity, which resulted in a dramatic increase in the viscosity and in the burst strength. They moderately affected the curing time, swelling, and weight loss. A mixed response was found in the compression modulus and the bonding strength in lap shear. We demonstrated that fiber‐reinforced bioadhesives have a great potential for surgical sealant applications because of improvement in the cohesive strength of the composite hydrogel. This study presents proof of the concept of using fibers for the enhancement of bioadhesive properties as a result of fiber‐reinforcement and may comprise the basis for future studies in this field. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
98.
Ultrasonic waves are monitored to detect the microstructure changes in cast iron. Specimens are made from nonalloyed spheroidal graphite cast iron (before and after heat treatment), eutectoid carbon steel (0.8% C), and ingot iron. The ultrasonic longitudinal wave speed increased with increase in the graphite shape factor, pearlite volume fraction, specific length of grain boundaries and cementite-ferrite interface boundaries. Decrease in the wave speed corresponds to increase in the graphite volume fraction, graphite precipitates and austenitizing temperature and time. 相似文献
99.
Unsteadiness of the shock wave structure in attached and separated compression ramp flows 总被引:2,自引:0,他引:2
Wall pressure fluctuations have been measured upstream of the corner-line in several two dimensional, adiabatic, compression ramp flows. The nominal freestream Mach number was 3 and the Reynolds number, based on boundary layer thickness, was 1.4 million. The measurements show that the shockwave structure is unsteady in both separated and attached flows, resulting in a region in which the wall pressure signal is intermittent. Statistical properties of this intermittent region, and of the separated flow, are presented and correlated with results from other studies. 相似文献
100.
Motivated by applications in unsourced random access, this paper develops a novel scheme for the problem of compressed sensing of binary signals. In this problem, the goal is to design a sensing matrix A and a recovery algorithm, such that the sparse binary vector can be recovered reliably from the measurements , where is additive white Gaussian noise. We propose to design A as a parity check matrix of a low-density parity-check code (LDPC) and to recover from the measurements using a Markov chain Monte Carlo algorithm, which runs relatively fast due to the sparse structure of A. The performance of our scheme is comparable to state-of-the-art schemes, which use dense sensing matrices, while enjoying the advantages of using a sparse sensing matrix. 相似文献