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71.
Stereoretentive Copper‐Catalyzed Directed Thioglycosylation of C(sp2)−H Bonds of Benzamides
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Amélie Chabrier Dr. Alexandre Bruneau Sara Benmahdjoub Dr. Belkacem Benmerad Dr. Sabrina Belaid Jean‐Daniel Brion Dr. Mouâd Alami Dr. Samir Messaoudi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(42):15006-15010
An efficient thioglycosylation of C(sp2)?H bonds with thiosugars has been established for the first time. Using only Cu(OAc)2?H2O as a catalyst and Ag2CO3 as an additive in DMSO, the protocol proved to have broad scope, and a variety of complex thioglycosides have been prepared in good yields with exclusive β‐selectivity. 相似文献
72.
A composite material of polybithiophene (PBTh) and β-MnO2 was prepared by electrodeposition of organic conducting polymer on β-MnO2 surface in 0.1 M LiClO4/0.01 M BTh/CH3CN. Synthesized material was characterized by using various techniques, i.e., X-ray diffractometry (XRD), scanning electron
microscopy (SEM), and magnetic measurements (SQUID). Electrochemical features of oxygen reduction reaction were investigated
using cyclic voltammetry on β-MnO2 and PBTh/β-MnO2 electrode, and chronopotentiometry tests were carried out at different currents. The results show that peak current and potential
of oxygen reduction are changed for β-MnO2 modified by polybithiophene. 相似文献
73.
The aim of this work is to show that the output from a double-output laser cavity exhibits distinctive features, manifesting themselves through typical asymmetry in the corresponding spectral-line shapes. Such asymmetry in an inhomogeneously broadened gas laser usually appears with a clear, but unpredictable shift of the maximum intensity level either towards the high or low frequency sides with respect to line centre. In the case of a double-output laser, the spectral profiles show opposite shifts. This means that when the maximum intensity of one output moves towards the high frequency side of the profile, the maximum intensity of the other moves towards the low frequency side. This gives rise to a frequency shift with respect to the Lamb-dip for a classical laser. On the theoretical side, we apply the standard disturbed Gaussian beam model to provide a quantification of the frequency shifts obtained at both sides of the system. 相似文献
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Tao H Allison TK Wright TW Stooke AM Khurmi C van Tilborg J Liu Y Falcone RW Belkacem A Martinez TJ 《The Journal of chemical physics》2011,134(24):244306
Using a combined theoretical and experimental approach, we investigate the non-adiabatic dynamics of the prototypical ethylene (C(2)H(4)) molecule upon π → π? excitation. In this first part of a two part series, we focus on the lifetime of the excited electronic state. The femtosecond time-resolved photoelectron spectrum (TRPES) of ethylene is simulated based on our recent molecular dynamics simulation using the ab initio multiple spawning method with multi-state second order perturbation theory [H. Tao, B. G. Levine, and T. J. Martinez, J. Phys. Chem. A 113, 13656 (2009)]. We find excellent agreement between the TRPES calculation and the photoion signal observed in a pump-probe experiment using femtosecond vacuum ultraviolet (hν = 7.7 eV) pulses for both pump and probe. These results explain the apparent discrepancy over the excited state lifetime between theory and experiment that has existed for ten years, with experiments [e.g., P. Farmanara, V. Stert, and W. Radloff, Chem. Phys. Lett. 288, 518 (1998) and K. Kosma, S. A. Trushin, W. Fuss, and W. E. Schmid, J. Phys. Chem. A 112, 7514 (2008)] reporting much shorter lifetimes than predicted by theory. Investigation of the TRPES indicates that the fast decay of the photoion yield originates from both energetic and electronic factors, with the energetic factor playing a larger role in shaping the signal. 相似文献
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77.
The goal of this work is to study a model of the strongly damped wave equation with dynamic boundary conditions and nonlinear boundary/interior sources and nonlinear boundary/interior damping. First, applying the nonlinear semigroup theory, we show the existence and uniqueness of local in time solutions. In addition, we show that in the strongly damped case solutions gain additional regularity for positive times t>0. Second, we show that under some restrictions on the initial data and if the interior source dominates the interior damping term and if the boundary source dominates the boundary damping, then the solution grows as an exponential function. Moreover, in the absence of the strong damping term, we prove that the solution ceases to exists and blows up in finite time. 相似文献
78.
Belkacem Sahli 《Applied Mathematics Letters》2012,25(1):77-80
The question of non-uniqueness in the integral formulation of an exterior boundary value problem in the elastic two-dimensional case has been resolved using the modified Green’s function technique. In this work, a new criterion of optimality based on the minimization of the norm of the kernel of the modified integral operator is established. 相似文献
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80.