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排序方式: 共有235条查询结果,搜索用时 15 毫秒
111.
Frédéric Pelletier Dr. Diana Ciuculescu Jean‐Gabriel Mattei Dr. Pierre Lecante Dr. Marie‐José Casanove Dr. Nader Yaacoub Dr. Jean‐Marc Greneche Dr. Carolin Schmitz‐Antoniak Prof. Catherine Amiens 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(19):6021-6026
The effectiveness of amine–borane as reducing agent for the synthesis of iron nanoparticles has been investigated. Large (2–4 nm) Fe nanoparticles were obtained from [Fe{N(SiMe3)2}2]. Inclusion of boron in the nanoparticles is clearly evidenced by extended X‐ray absorption fine structure spectroscopy and Mössbauer spectrometry. Furthermore, the reactivity of amine–borane and amino–borane complexes in the presence of pure Fe nanoparticles has been investigated. Dihydrogen evolution was observed in both cases, which suggests the potential of Fe nanoparticles to promote the release of dihydrogen from amine–borane and amino–borane moieties. 相似文献
112.
We analyse the evolution of a two-stage chemical reaction betweentwo neighbouring plumes of reactants. Under the assumption thatthe plumes are approximately Gaussian we derive a system ofordinary differential equations for the total amount, the centroidand the variance of each reactant. We compare the solution ofthese equations with full numerical simulation of the reaction.Excellent agreement is obtained, with solution of the near-Gaussianmodel requiring considerably less computational effort thanthe full simulations. Of key importance is the yield of thereaction, and we discuss this feature in particular. 相似文献
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116.
Celine Hocquelet Christopher K. Jankowski Andre Lucien Pelletier Jean-Claude Tabet Christine Lamouroux Patrick Berthault 《Journal of inclusion phenomena and macrocyclic chemistry》2011,69(1-2):75-84
Methylated and partially methylated cyclodextrin homo- and heterodimers linked by diamidosuccinic bridges were synthesised and their inclusion properties were evaluated using NMR and isothermic microcalorimetric measurements ITC. The selective binding of ligands, such as bisadamantyl derivatives, to the cavities of unprotected cyclodextrin dimers showed the equimolar formation of bidendate inclusion complexes (2:2, two ligand guest to two cavities host). 相似文献
117.
Balaji Subramanian Nadjda Tchoukanova Yahia Djaoued Claude Pelletier Mathieu Ferron 《Journal of Raman spectroscopy : JRS》2013,44(2):219-226
Astaxanthin is a carotenoid naturally found in microbial organisms, microalgae, and many crustaceans. Its consumption has led to beneficial effects such as pigmentation of marine animals, and it favorably addresses several human health issues as a result of its high important antioxidant property. Several companies produce synthetic trans‐astaxanthin for dietary purposes in aquaculture, where it is mainly used for pigmentation. It is known that trans‐astaxanthin manifests itself as a monomer in organic solvents, as aggregates in aqueous solutions of organic solvents, or as crystalline solids. These forms display unique optical and structural properties, which have an impact on biological systems. In this work, we report on detailed Raman investigations, in conjunction with optical absorption spectroscopy, of monomer, aggregates, and crystalline forms of trans‐astaxanthin. The Raman and optical absorption spectroscopic investigations of trans‐astaxanthin aggregates were performed as a function of time, showing the formation of card‐packed aggregates after 2 h, and head‐to‐tail aggregates after 24 h in a 10% acetone–water astaxanthin solution. For the crystalline trans‐astaxanthin, a pointwise Raman mapping evidenced the presence of two distinct crystal structures. The Raman modes of these crystal structures (A and B) were correlated with the intermolecular interactions present in chloroform solvated (AXT‐Cl) and unsolvated (un‐AXT) trans‐astaxanthin single crystals. Both crystal structure A and the card‐packed aggregates have similar intermolecular π stacking interactions as AXT‐Cl. The crystal structure B and the head‐to‐tail aggregates showed linear chain features as in un‐AXT. This work also clearly demonstrates that Raman spectroscopy is a powerful tool to distinguish the crystal structures present in crystalline powder of trans‐astaxanthin. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
118.
L. B. Lurio D. Lumma M. A. Borthwick P. Falus S. G. J. Mochrie J. F. Pelletier 《Synchrotron Radiation News》2013,26(2):28-37
Stanford Synchrotron Radiation Laboratory (SSRL) entered a new era of synchrotron radiation experimentation in March 2004 with the start of the first experimental run following the completion of the SPEAR3 upgrade project [1]. Intense X-rays at the macromolecular crystallography stations, combined with state-of-the-art equipment, including high-speed CCD detectors and sophisticated control system software, now enable high-quality diffraction images to be collected in only a few seconds and entire crystallography datasets in a matter of minutes. With significant reduction in the time required to collect a dataset, the period necessary to enter the experimental hutch to manually mount and dismount crystal samples is often a significant percentage of the users' total beam time allocation. 相似文献
119.
The first aim of this paper is to generalize the online estimator of a regression function introduced by Révész [26, 27] to the multivariate framework. Similarly to the univariate framework, the study of the convergence rate of the multivariate Révész’s estimator requires a tedious condition connecting the stepsize of the algorithm and the unknown value of the density of the regressor variable at the point at which the regression function is estimated. The second aim of this paper is to apply the averaging principle of stochastic approximation algorithms to remove this tedious condition. 相似文献
120.
L. Eça M. Hoekstra A. Hay D. Pelletier 《International Journal of Computational Fluid Dynamics》2013,27(3-4):175-188
This paper presents a manufactured solution (MS), resembling a two-dimensional, steady, wall-bounded, incompressible, turbulent flow for RANS codes verification. The specified flow field satisfies mass conservation, but requires additional source terms in the momentum equations. To also allow verification of the correct implementation of the turbulence models transport equations, the proposed MS exhibits most features of a true near-wall turbulent flow. The model is suited for testing six eddy-viscosity turbulence models: the one-equation models of Spalart and Allmaras and Menter; the standard two-equation k–ε model and the low-Reynolds version proposed by Chien; the TNT and BSL versions of the k–ω model. 相似文献