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151.
Sachse A Ameloot R Coq B Fajula F Coasne B De Vos D Galarneau A 《Chemical communications (Cambridge, England)》2012,48(39):4749-4751
The metal-organic framework Cu-BTC has been successfully synthesized as nanoparticles inside the mesopores of silica monoliths featuring a homogeneous macropore network enabling the use of Cu-BTC for continuous flow applications in liquid phase with low pressure drop. High productivity was reached with this catalyst for the Friedl?nder reaction. 相似文献
152.
Benoît Moreau Dino Alberico Vincent N.G. Lindsay André B. Charette 《Tetrahedron》2012,68(17):3487-3496
A Cu(I)-catalyzed asymmetric cyclopropanation of alkenes with an iodonium ylide has been developed. The copper source, hypervalent iodine source, solvent, and additives all have a significant effect on the yields and enantioselectivities. High enantioselectivity (up to 99:1 er) and diastereoselectivity (95:5 dr trans/cis) were achieved for a wide range of alkenes. Conditions were developed to convert the trans products to the cis isomers. In addition, 1-nitrocyclopropyl carboxylates were transformed into the corresponding substituted cyclopropane amino acids and aminocyclopropanes. Moreover, a comparative study between Zn- and In-mediated reduction reactions of the nitro group in these compounds with regards to the er erosion in the process is also documented. 相似文献
153.
Axel Coussement Olivier Gicquel Jean Caudal Benoît Fiorina Gérard Degrez 《Journal of computational physics》2012,231(17):5571-5611
The Navier–Stokes characteristic boundary conditions (NSCBC) is a very efficient numerical strategy to treat boundary conditions in fully compressible solvers. The present work is an extension of the 3D-NSCBC method proposed by Yoo et al. and Lodato et al. in order to account for multi-component reactive flows with detailed chemistry and complex transport. A new approach is proposed for the outflow boundary conditions which enables clean exit of non-normal flows, and the specific treatment of all kinds of edges and corners is carefully addressed. The proposed methodology is successfully validated on various challenging multi-component reactive flow configurations. 相似文献
154.
Hydroxyl surface density in porous silica drops down to nearly zero when the pH of the confined aqueous solution is greater than 10.5. To study such extreme conditions, we developed a model of slit silica nanopores where all the hydrogen atoms of the hydroxylated surface are removed and the negative charge of the resulting oxygen dangling bonds is compensated by Ca(2+) counterions. We employed grand canonical Monte Carlo and molecular dynamics simulations to address how the Ca(2+) counterions affect the thermodynamics, structure, and dynamics of confined water. While most of the Ca(2+) counterions arrange themselves according to the so-called "Stern layer," no diffuse layer is observed. The presence of Ca(2+) counterions affects the pore filling for strong confinement where the surface effects are large. At full loading, no significant changes are observed in the layering of the first two adsorbed water layers compared to nanopores with fully hydroxylated surfaces. However, the water structure and water orientational ordering with respect to the surface is much more disturbed. Due to the super hydrophilicity of the Ca(2+)-silica nanopores, water dynamics is slowed down and vicinal water molecules stick to the pore surface over longer times than in the case of hydroxylated silica surfaces. These findings, which suggest the breakdown of the linear Poisson-Boltzmann theory, provide important information about the properties of nanoconfined electrolytes upon extreme conditions where the surface charge and ion concentration are large. 相似文献
155.
Mouas M Gasser JG Hellal S Grosdidier B Makradi A Belouettar S 《The Journal of chemical physics》2012,136(9):094501
Molecular dynamics (MD) simulations of liquid tin between its melting point and 1600 °C have been performed in order to interpret and discuss the ionic structure. The interactions between ions are described by a new accurate pair potential built within the pseudopotential formalism and the linear response theory. The calculated structure factor that reflects the main information on the local atomic order in liquids is compared to diffraction measurements. Having some confidence in the ability of this pair potential to give a good representation of the atomic structure, we then focused our attention on the investigation of the atomic transport properties through the MD computations of the velocity autocorrelation function and stress autocorrelation function. Using the Green-Kubo formula (for the first time to our knowledge for liquid tin) we determine the macroscopic transport properties from the corresponding microscopic time autocorrelation functions. The selfdiffusion coefficient and the shear viscosity as functions of temperature are found to be in good agreement with the experimental data. 相似文献
156.
Francisco J. Valdés-Parada Jose Alvarez-Ramirez Benoît Goyeau J. Alberto Ochoa-Tapia 《Transport in Porous Media》2009,78(3):459-476
In this paper, mass transfer at the fluid–porous medium boundaries is studied. The problem considers both diffusive and convective
transport, along with adsorption and reaction effects in the porous medium. The result is a mass flux jump condition that
is expressed in terms of effective transport coefficients. Such coefficients (a total dispersion tensor and effective reaction
and adsorption coefficients) may be computed from the solution of the corresponding closure problem here stated and solved
as a function of the Péclet number (Pe), the porosity and a local Thiele modulus. For the case of negligible convective transport (i.e., ), the closure problem reduces to the one recently solved by the authors for diffusion and reaction between a fluid and a
microporous medium. 相似文献
157.
Maxime Guillaume Benoît Champagne Eric A. Perpète Jean-Marie André 《Theoretical chemistry accounts》2001,105(6):431-436
The electronic structure of finite and infinite linear, cyclic and M?bius strip polyacenes has been investigated by adopting
Hückel and semiempirical schemes. Using the Hückel approach, it turns out that the M?bius belting process modifies the highest
occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap in such a way its evolution with chain length
is similar to the linear polyacenes rather than their cyclic analogs. These results are corroborated at the Austin model 1
(AM1) level, where the geometry relaxation effects are taken into account. The optimized AM1 structures show that the M?bius
defect is localized and extends over a third of the ring. With respect to the Hückel approach, accounting for geometry distortion
at the AM1 levels results in an increase in the HOMO–LUMO gap of the M?bius strip relative to the linear and cyclic finite-size
structures. On the other hand, when including electron-hole correlation at the configuration interaction singles/Zerner's
intermediate neglect of differential overlap level the behavior with system size of the first excitation energy of cyclic
and M?bius polyacenes differs from their linear analogs and leads to smaller singlet excitation energies.
Received: 20 September 2000 / Accepted: 21 September 2000 / Published online: 28 February 2001 相似文献
158.
Delduc Francois Lacroix Sylvain Magro Marc Vicedo Benoît 《Letters in Mathematical Physics》2020,110(7):1645-1687
Letters in Mathematical Physics - In the approach recently proposed by K. Costello and M. Yamazaki, which is based on a four-dimensional variant of Chern–Simons theory, we derive a simple and... 相似文献
159.
We consider a two dimensional viscous shallow water model with friction term. Existence of global weak solutions is obtained
and convergence to the strong solution of the viscous quasi-geostrophic equation with free surface term is proven in the well
prepared case. The ill prepared data case is also discussed.
Received: 4 October 2002 / Accepted: 22 January 2003
Published online: 28 May 2003
Communicated by P. Constantin 相似文献
160.
Benoı^t Chevallier 《Mathematische Annalen》1997,307(1):1-28
Sans résumé
Re?u le 8 august 1994 / Version révisée re?ue le 13 novembre 1995 相似文献