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81.
Bomble YJ Vázquez J Kállay M Michauk C Szalay PG Császár AG Gauss J Stanton JF 《The Journal of chemical physics》2006,125(6):64108
The recently developed high-accuracy extrapolated ab initio thermochemistry method for theoretical thermochemistry, which is intimately related to other high-precision protocols such as the Weizmann-3 and focal-point approaches, is revisited. Some minor improvements in theoretical rigor are introduced which do not lead to any significant additional computational overhead, but are shown to have a negligible overall effect on the accuracy. In addition, the method is extended to completely treat electron correlation effects up to pentuple excitations. The use of an approximate treatment of quadruple and pentuple excitations is suggested; the former as a pragmatic approximation for standard cases and the latter when extremely high accuracy is required. For a test suite of molecules that have rather precisely known enthalpies of formation {as taken from the active thermochemical tables of Ruscic and co-workers [Lecture Notes in Computer Science, edited by M. Parashar (Springer, Berlin, 2002), Vol. 2536, pp. 25-38; J. Phys. Chem. A 108, 9979 (2004)]}, the largest deviations between theory and experiment are 0.52, -0.70, and 0.51 kJ mol(-1) for the latter three methods, respectively. Some perspective is provided on this level of accuracy, and sources of remaining systematic deficiencies in the approaches are discussed. 相似文献
82.
Szunerits S Coffinier Y Janel S Boukherroub R 《Langmuir : the ACS journal of surfaces and colloids》2006,22(25):10716-10722
This article reports chemical stability studies of a gold film electrode coated with thin silicon oxide (SiOx) layers using electrochemical, surface plasmon resonance (SPR) and atomic force microscopy (AFM) techniques. Silica films with different thicknesses (d = 6.4, 9.7, 14.5, and 18.5 nm) were deposited using a plasma-enhanced chemical vapor deposition technique (PECVD). For SiOx films with d >/= 18.5 nm, the electrochemical behavior is characteristic of a highly efficient barrier for a redox probe. SiOx films with thicknesses between 9.5 and 14.5 nm were found to be less efficient barriers for electron transfer. The Au/SiOx interface with 6.4 nm of SiOx, however, showed an enhanced steady-state current compared to that of the other films. The stability of this interface in solutions of different pH was investigated. Whereas a strongly basic solution led to a continuous dissolution of the SiOx interface, acidic treatment produced a more reticulated SiOx film and improved electrochemical behavior. The electrochemical results were corroborated by SPR measurements in real time and AFM studies. 相似文献
83.
Oulié P Boulho C Vendier L Coppel Y Etienne M 《Journal of the American Chemical Society》2006,128(50):15962-15963
The intermolecular C-H bond activation of benzene occurs under very mild conditions (room temperature) via a rare stereospecific 1,3-H addition on an unsaturated eta2-cyclopropene intermediate generated by a beta-H abstraction of CH4 from TpMe2NbMe(c-C3H5)(MeCCMe) to give TpMe2NbPh(c-C3H5)(MeCCMe). 相似文献
84.
Michel Holler Hind Mamlouk Jean-Paul Gisselbrecht Yannick Rio Nicola Armaroli 《Tetrahedron》2006,62(9):2060-2073
Two fullerene-substituted m-phenylene-bis-phenanthroline ligands have been prepared. The synthesis of the first derivative (L1) is based on an esterification reaction between a Cs symmetrical cis-2 fullerene bis-adduct bearing a carboxylic acid function and a bis-phenanthroline alcohol (5). The second ligand (L2) has been obtained by reaction of a bis-phenanthroline malonate (9) and C60 under Bingel conditions. The copper(I) complexes of L1 and L2 have been prepared by treatment with a slight excess of Cu(CH3CN)4BF4. NMR spectroscopy and mass spectrometry analysis have unambiguously shown that these complexes are bis-copper(I) helicates substituted with two fullerene moieties. The photophysical properties of the copper(I) complexes Cu2(L1)2 and Cu2(L2)2 have been investigated. In both systems photoinduced electron transfer from the central metal-complexed unit to the external fullerenes may occur, in principle, by excitation of both moieties. However, this is found to be the case only for the methanofullerene system Cu2(L2)2. Unexpectedly, for Cu2(L1)2, photoexcitation of the peripheral carbon spheres is followed by regular internal deactivation. Possible reasons for this behavior are examined in light of current theories for photoinduced energy and electron transfer. 相似文献
85.
Regioselectivity of the sulfonyl radical mediated 5-exo-trig cyclization of 3-silylheptadienyl systems 3a-d has been studied. At low temperature, the reaction of the sulfonyl radical occurs regioselectively at the allylsilane terminus, while a reversal of regioselectivity is observed at 80 degrees C. This general trend has been rationalized on the basis of polar effects and radical stabilization. Thiyl-mediated radical cyclization of dienes 3a, 3c-d, 7 with subsequent sulfur atom transfer was also studied, providing thiabicyclo[3.3.0] skeleton in one step with excellent stereocontrol. 相似文献
86.
Anthony Delmas Yannick Le Maoult Jean-Marie Buchlin Thierry Sentenac Jean-José Orteu 《Experiments in fluids》2013,54(4):1-16
The goal of this study is to examine the perturbation induced by the convective effect (or mirage effect) on shape measurement and to give an estimation of the error induced. This work explores the mirage effect in different spectral bands and single wavelengths. A numerical approach is adopted and an original setup has been developed in order to investigate easily all the spectral bands of interest with the help of a CCD camera (Si, 0.35–1.1 μm), a near infrared camera (VisGaAs, 0.8–1.7 μm) or infrared cameras (8–12 μm). Displacements due to the perturbation for each spectral band are measured and finally some hints about how to correct them are given. 相似文献
87.
Arnoud Perrot Yannick Mélinge Damien Rangeard Francesca Micaelli Patrice Estellé Christophe Lanos 《Rheologica Acta》2012,51(8):743-754
We propose in this work to provide an efficient and simple extruder device able to evaluate the rheological and tribological behaviour of high yield stress fluids, such as extrudible materials. An extruder able to measure simultaneously both the friction force acting on the extruder wall and the total extrusion force is developed. Based on previous studies, an efficient and accurate method of data analysis is then proposed and applied in order to obtain both a flow curve and a tribological law. Experimental tests are performed on soft modelling clay, kaolin paste and cement-based materials. Results are compared to conventional rheometry measurements. This comparison helps to evaluate the accuracy of the proposed experimental device and procedure. 相似文献
88.
Yannick G. Spill Guillaume Bouvier Michael Nilges 《Journal of computational chemistry》2013,34(2):132-140
Replica‐exchange is a powerful simulation method for sampling the basins of a rugged energy landscape. The replica‐exchange method's sampling is efficient because it allows replicas to perform round trips in temperature space, thereby visiting both low and high temperatures in the same simulation. However, replicas have a diffusive walk in temperature space, and the round trip rate decreases significantly with the system size. These drawbacks make convergence of the simulation even more difficult than it already is when bigger systems are tackled. Here, we present a simple modification of the exchange method. In this method, one of the replicas steadily raises or lowers its temperature. We tested the convective replica‐exchange method on three systems of varying complexity: the alanine dipeptide in implicit solvent, the GB1 β‐hairpin in explicit solvent and the Aβ25–35 homotrimer in a coarse grained representation. For the highly frustrated Aβ25–35 homotrimer, the proposed “convective” replica‐exchange method is twice as fast as the standard method. It discovered 24 out of 27 free‐energy basins in less than 500 ns. It also prevented the formation of groups of replicas that usually form on either side of an exchange bottleneck, leading to a more efficient sampling of new energy basins than in the standard method. © 2012 Wiley Periodicals, Inc. 相似文献
89.
90.
Biofouling or adsorption of biomolecules onto surfaces in microfluidic devices limits the type of samples which can be handled. In this paper, we take advantage of the high adsorption capacity of graphene oxide (GO) for proteins as a strategy to limit biofouling, while preserving their activity for droplet-based lab-on-chip applications. 相似文献