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排序方式: 共有639条查询结果,搜索用时 15 毫秒
291.
Domenico Acierno Eugenio Amendola Cosimo Carfagna Luigi Nicolais Rossella Nobile 《Molecular Crystals and Liquid Crystals》2013,570(1):553-562
In this work the effect of the inclusion of low percentages of theliquid crystal polymer PET/PHBGO on the rheological and mechanical behaviour of Polycarbonate is described. 相似文献
292.
Marc Morant-Giner Isaac Brotons-Alcázar Nikita Y. Shmelev Dr. Artem L. Gushchin Luke T. Norman Prof. Andrei N. Khlobystov Dr. Antonio Alberola Dr. Sergio Tatay Dr. Josep Canet-Ferrer Dr. Alicia Forment-Aliaga Prof. Eugenio Coronado 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(29):6670-6678
The preparation of 2D stacked layers combining flakes of different nature gives rise to countless numbers of heterostructures where new band alignments, defined at the interfaces, control the electronic properties of the system. Among the large family of 2D/2D heterostructures, the one formed by the combination of the most common semiconducting transition metal dichalcogenides, WS2/MoS2, has awakened great interest owing to its photovoltaic and photoelectrochemical properties. Solution as well as dry physical methods have been developed to optimize the synthesis of these heterostructures. Here, a suspension of negatively charged MoS2 flakes is mixed with a methanolic solution of a cationic W3S4-core cluster, giving rise to a homogeneous distribution of the clusters over the layers. In a second step, a calcination of this molecular/2D heterostructure under N2 leads to the formation of clean WS2/MoS2 heterostructures, where the photoluminescence of both counterparts is quenched, proving an efficient interlayer coupling. Thus, this chemical method combines the advantages of a solution approach (simple, scalable, and low-cost) with the good quality interfaces reached by using more complicated traditional physical methods. 相似文献
293.
Manuel Martínez–Quesada Eugenio Roldán Germán J. de Valcárcel 《Optics Communications》2011,284(10-11):2554-2559
We study the emission properties of a class A bidirectional laser under the action of an amplitude modulated injected signal, i.e. a rocked bidirectional laser. We derive two coupled autonomous amplitude equations valid close to the emission threshold and study their solutions. The most relevant result is that while in the absence of rocking the laser can only emit in either of the two unidirectional solutions, under suitable rocking conditions cw bidirectional emission appears and, moreover, it coexist bistably with unidirectional emission. 相似文献
294.
295.
Clemente-León M Coronado E López-Muñoz A Repetto D Catala L Mallah T 《Langmuir : the ACS journal of surfaces and colloids》2012,28(9):4525-4533
We report a novel method to prepare patterns of nanoparticles over large areas of the substrate. This method is based on the adsorption of the negatively charged nanoparticles dispersed in an aqueous subphase onto a monolayer of the phospholipid dipalmitoyl-l-α-phosphatidylcholine (DPPC) at the air-water interface. It has been used to prepare patterns of nanoparticles of Prussian blue analogues (PBA) of different size (K(0.25)Ni[Fe(CN)(6)](0.75) (NiFe), K(0.25)Ni[Cr(CN)(6)](0.75) (NiCr), K(0.25)Ni[Co(CN)(6)](0.75) (NiCo), Cs(0.4)Co[Cr(CN)(6)](0.8) (CsCoCr), and Cs(0.4)Co[Fe(CN)(6)](0.9) (CsCoFe)). The behavior of DPPC monolayer at the air-water interface in the presence of the subphase of PBA nanoparticles has been studied by the compression isotherms and Brewster angle microscopy (BAM) images. Atomic force microscopy (AFM) of the transferred films on mica substrates shows that patterns of the nanoparticles are observed for a 10(-4) M concentration of the subphase, based on the nanoparticle precursors, at surface pressures between 1 and 6 mN/m and transfer velocities from 10 to 80 mm/min. Vertical, horizontal, or tilted fringes of the nanoparticles with respect to the transfer direction can be obtained depending on the transfer velocity and surface pressure. 相似文献
296.
The present work provides a definitive answer to the problem of quantifying relaxation to equilibrium of the solution to the spatially homogeneous Boltzmann equation for Maxwellian molecules. Under really mild conditions on the initial datum and a weak, physically consistent, angular cutoff hypothesis, our main result (Theorem 1) contains the first precise statement that the total variation distance between the solution and the limiting Maxwellian distribution admits an upper bound of the form \(C e^{\varLambda _b t}\) , \(\varLambda _b\) being the least negative eigenvalue of the linearized collision operator and \(C\) a constant depending only on the initial datum. The validity of this quantification was conjectured, about fifty years ago, by Henry P. McKean. As to the proof of our results, we have taken as point of reference an analogy between the problem of convergence to equilibrium and the central limit theorem of probability theory, highlighted by McKean. 相似文献
297.
Gustavo Garrigós Eugenio Hernández Maria de Natividade 《Advances in Computational Mathematics》2012,37(2):255-283
We prove optimal embeddings for nonlinear approximation spaces $\mathcal{A}^{\alpha}_q$ , in terms of weighted Lorentz sequence spaces, with the weights depending on the democracy functions of the basis. As applications we recover known embeddings for N-term wavelet approximation in L p , Orlicz, and Lorentz norms. We also study the ??greedy classes?? ${\mathcal{G}_{q}^{\alpha}}$ introduced by Gribonval and Nielsen, obtaining new counterexamples which show that ${\mathcal{G}_{q}^{\alpha}}\not=\mathcal{A}^{\alpha}_q$ for most non-democratic unconditional bases. 相似文献
298.
299.
Kuheli Das Amitabha Datta Chittaranjan Sinha Jui-Hsien Huang Eugenio Garribba Ching-Sheng Hsiao Chin-Lin Hsu 《ChemistryOpen》2012,1(2):80-89
The reactions of the tridentate hydrazone ligand, N′-[1-(pyridin-2-yl)ethylidene]acetohydrazide (HL), obtained by condensation of 2-acetylpyridine with acetic hyadrazide, with copper nitrate trihydrate in the presence of thiocyanate, or with CuCl2 produce two distinct coordination compounds, namely a one-dimensional helical coordination chain of [CuL(NCS)]n (1) units, and a doubly chlorido-bridged dinuclear complex [Cu2L2Cl2] (2) (where L=CH3C(O)=N–N=CCH3C5H4N). Single-crystal X-ray structural determination studies reveal that in complex 1, a deprotonated hydrazone ligand L− coordinates a copper(II) ion that is bridged to two neighbouring metal centres by SCN− anions, generating a one-dimensional helical coordination chain. In complex 2, two symmetry-related, adjacent copper(II) coordination entities are doubly chlorido-bridged, producing a dicopper entity with a Cu⋅⋅⋅Cu distance of 3.402 (1) Å. The two coordination compounds have been fully characterised by elemental analysis, spectroscopic techniques including IR, UV–vis and electron paramagnetic resonance, and variable-temperature magnetic studies. The biological effects of 1 and 2 on the viability of human colorectal carcinoma cells (COLO-205 and HT-29) were evaluated using an MTT assay, and the results indicate that these complexes induce a decrease in cell-population growth of human colorectal carcinoma cells with apoptosis. 相似文献
300.
Francesco Caruso Steven Saverwyns Marina Van Bos Delia Francesca Chillura?Martino Anne-Emmanuelle Ceulemans Joris de Valck Eugenio Caponetti 《Applied Physics A: Materials Science & Processing》2012,107(1):197-202
In recent years, a growing attention has been addressed to the study of the varnish from early musical instruments. The surfaces
of nine historical Low Countries stringed musical instruments from the collection of the “Musical Instruments Museum” in Brussels
were non-destructively analysed by in situ micro-X-Ray Fluorescence spectroscopy in dispersive mode. It was found that the
main pigments dispersed in the varnish were iron- and manganese-based earths. The presence of a chromium-based pigment in
one of the analysed instruments makes it appreciably different from the others. Other findings were discussed and compared
with previously published results. The collection of such information plays a relevant role in the recovery of the applied
formulations that is an interesting issue for conservators, luthiers and art historians. 相似文献