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141.
Mihail N. Popescu William E. Uspal Siegfried Dietrich 《The European physical journal. Special topics》2016,225(11-12):2189-2206
Chemically active colloids locally change the chemical composition of their solvent via catalytic reactions which occur on parts of their surface. They achieve motility by converting the released chemical free energy into mechanical work through various mechanisms, such as phoresis. Here we discuss the theoretical aspects of self-diffusiophoresis, which – despite being one of the simplest motility mechanisms – captures many of the general features characterizing self-phoresis, such as self-generated and maintained hydrodynamic flows “driven” by surface activity induced inhomogeneities in solution. By studying simple examples, which provide physical insight, we highlight the complex phenomenology which can emerge from self-diffusiophoresis. 相似文献
142.
A. Kameyama introduced the concept of self-similar topological system and asked the following fundamental question: given a topological self-similar system (K,(fi)i∈{1,2,...,N}), does there exist a metric on K comparable to the topology such that all the functions fi are contractions? We modify Kameyama's question (which has a negative answer for an arbitrary topological self-similar system) by weakening the requirement that the functions in the topological self-similar system be contractions to requiring that they be φ -contractions. More precisely we give an affirmative answer to the following question: given a topological self-similar system (K,(fi)i∈{1,2,...,N}) does there exist a metric δ on K which is compatible with the original topology and a comparison function φ:[0,∞)→[0,∞) such that all the functions fi:(K,δ)→(K,δ) are φ -contractions? Consequently the iterated function system ((K,d),(fi)i∈{1,2,...,N}), where d is a metric on K compatible with the original topology on K, is φ-hyperbolic. 相似文献
143.
Eva Castillejos Dr. Pierre‐Jean Debouttière Dr. Lucian Roiban Abderrahim Solhy Dr. Victor Martinez Dr. Yolande Kihn Dr. Ovidiu Ersen Dr. Karine Philippot Dr. Bruno Chaudret Dr. Philippe Serp Dr. 《Angewandte Chemie (International ed. in English)》2009,48(14):2529-2533
Are you in? Bimetallic PtRu nanoparticles have been selectively confined inside or deposited outside carbon nanotubes (see picture). The confined nanoparticles display significantly higher selectivity and catalytic activity in hydrogenation reactions.
144.
Tong LH Pascu SI Jarrosson T Sanders JK 《Chemical communications (Cambridge, England)》2006,(10):1085-1087
Suzuki and Sonogashira couplings have been used in short and efficient sequences to give access to a new family of porphyrin trimers on a practical scale. 相似文献
145.
Cazacu A Tong C van der Lee A Fyles TM Barboiu M 《Journal of the American Chemical Society》2006,128(29):9541-9548
The self-assembly of ureido crown-ether derivatives has been examined in homogeneous solution, in the solid state, and in planar bilayer membranes. The self-assembly is driven by head-to-tail hydrogen bonding between the urea functional groups. Dimers and higher oligomers are formed in CDCl3 solution as assessed by the change in the ureido NH chemical shift as a function of concentration. Single-crystal X-ray diffraction shows that an antiparallel association of the ureas produces columnar channels composed of face-to-face crown ethers. Powder X-ray diffraction studies also show the presence of a minor phase based upon a parallel urea association leading to an alternative columnar arrangement of the crown ethers. In bilayer membranes at low concentration of ureido crown ether added, membrane disruption is observed together with rare single-channel openings, but at higher concentration, a rich array of interconverting channel conductance states is observed. The channel results are interpreted as arising from discreet stacks of ureido crown ethers where the transport of cations would occur via the macrocycles, admixed with larger pores formed by association of the crown ether headgroups around a central large pore. 相似文献
146.
147.
Suppose that U is the resolvent of a Borel right process on a Lusin space X. If is a U-excessive measure on X then we show by analytical methods that for every U-excessive measure with the Radon–Nikodym derivative d/d possesses a finely continuous version. (Fitzsimmons and Fitzsimmons and Getoor gave a probabilistic approach for this result.) We extend essentially a technique initiated by Mokobodzki and deepened by Feyel. The result allows us to establish a Revuz type formula involving the fine versions, and to study the Revuz correspondence between the -finite measures charging no set that is both -polar and -negligible (U being the potential component of ) and the strongly supermedian kernels on X. This is an analytic version of a result of Azéma, Fitzsimmons and Dellacherie, Maisonneuve and Meyer, in terms of additive functionals or homogeneous random measures. Finally we give an application to the context of the semi-Dirichlet forms, covering a recent result of Fitzsimmons. 相似文献
148.
Alexey V. Novikov Mihail V. Shaleev Dmitry N. Lobanov Artem N. Yablonsky Nikolay V. Vostokov Zaharij F. Krasilnik 《Physica E: Low-dimensional Systems and Nanostructures》2004,23(3-4):416
The photoluminescence spectra of GeSi/Si (0 0 1) self-assembled islands produced by solid source molecular beam epitaxy in a wide range (460–700°C) of growth temperatures were investigated. The results showed a blue shift of the island-related photoluminescence peak with a growth temperature lowering from 600°C to 550°C. The observed blue shift of the island photoluminescence peak is associated with a sharp decrease in the average height of the island, which occurs through a change of its shape from dome to hut as the growth temperature lowers from 600°C to 550°C. 相似文献
149.
Uerpmann C Malina J Pascu M Clarkson GJ Moreno V Rodger A Grandas A Hannon MJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(6):1750-1756
A new tetracationic triple-stranded supramolecular cylinder is prepared from a bis(pyridylimine) ligand containing a diphenylmethane and two ketimine groups in the spacer. The cylinder is longer and slightly wider than the corresponding cylinder containing just diphenylmethane spacers. Inter-strand CH...pi interactions are not observed and this affects the relay of the chiral information within the cylinder; a mixture of rac and meso isomers results, with the meso isomer being the dominant solution species and characterised in the solid state by crystallography. This new cylinder does bind to DNA as confirmed by induced circular dichroism signals in both the metal-to-ligand charge transfer (MLCT) and in-ligand bands of the cylinder. Flow linear dichroism demonstrates that the cylinder binds to DNA in a specific orientation(s) and is consistent with (major) groove-binding as seen for the shorter cylinder. Some DNA bending/coiling is observed but the effect is much less dramatic than observed for the cylinder with diphenylmethane spacers confirming that coiling is not solely a consequence of the tetracationic charge, but rather is related to the precise size and shape of the cylinder. 相似文献
150.
Rusu Mihai Lucian Marutoiu Constantin Sandu Ion Tita Dumitru Gogoasa Ioan Barbu Constantin-Horia Popescu Andreea 《平面色谱法杂志一现代薄层色谱法》2007,20(2):139-140
JPC – Journal of Planar Chromatography – Modern TLC - Samples of clove, nutmeg, and cinnamon have been extracted by maceration with ethanol for 24 h and with aqueous ethanol 48 h.... 相似文献