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81.
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
82.
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
83.
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
84.
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
85.
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
86.
87.
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
88.
Martinho PN Ortin Y Gildea B Gandolfi C McKerr G O'Hagan B Albrecht M Morgan GG 《Dalton transactions (Cambridge, England : 2003)》2012,41(25):7461-7463
A hysteretic spin transition is induced in a solution assembly of a mononuclear Fe(III) amphiphilic complex which exhibits only gradual spin crossover in the solid state. The hysteretic behavior is dependent on dynamic solution assembly and removal of solvent causes reversion to the original bulk solid magnetic response. 相似文献
89.
Esposito DV Hunt ST Kimmel YC Chen JG 《Journal of the American Chemical Society》2012,134(6):3025-3033
This work explores the opportunity to substantially reduce the cost of hydrogen evolution reaction (HER) catalysts by supporting monolayer (ML) amounts of precious metals on transition metal carbide substrates. The metal component includes platinum (Pt), palladium (Pd), and gold (Au); the low-cost carbide substrate includes tungsten carbides (WC and W(2)C) and molybdenum carbide (Mo(2)C). As a platform for these studies, single-phase carbide thin films with well-characterized surfaces have been synthesized, allowing for a direct comparison of the intrinsic HER activity of bare and Pt-modified carbide surfaces. It is found that WC and W(2)C are both excellent cathode support materials for ML Pt, exhibiting HER activities that are comparable to bulk Pt while displaying stable HER activity during chronopotentiometric HER measurements. The findings of excellent stability and HER activity of the ML Pt-WC and Pt-W(2)C surfaces may be explained by the similar bulk electronic properties of tungsten carbides to Pt, as is supported by density functional theory calculations. These results are further extended to other metal overlayers (Pd and Au) and supports (Mo(2)C), which demonstrate that the metal ML-supported transition metal carbide surfaces exhibit HER activity that is consistent with the well-known volcano relationship between activity and hydrogen binding energy. This work highlights the potential of using carbide materials to reduce the costs of hydrogen production from water electrolysis by serving as stable, low-cost supports for ML amounts of precious metals. 相似文献
90.
Yannick Crémillieux Florent Goutailler Bruno Montcel Dominique Grand Gérard Vermeulen Pierre-Etienne Wolf 《Applied magnetic resonance》2012,43(1-2):167-180
The volume of polarized sample and the delay required between successive polarizations of samples represent serious constraints for dynamic nuclear polarization (DNP) applications. With these limitations in mind, a DNP polarizer, based on a super-wide bore (150-mm diameter) vertical magnet operating at 3.35?T, was designed. The working diameter for loading/unloading samples is equal to 46?mm and the microwave cavity can accommodate up to three samples. The cryostat can be cooled to 4.2?K in typically 2?h and filled with liquid helium in 1?h. Once filled with liquid helium, the cryostat hold time is on the order of 4?h and a minimum temperature of 1.19?K can be reached. In situ polarization levels at low temperature were measured between 5 and 10?% in single and multiple samples of 13C-labeled urea and glycine. 相似文献