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31.
Zelong Wang Silin Chen Prof. Dr. Chao Chen Dr. Yunhui Yang Prof. Dr. Congyang Wang 《Angewandte Chemie (International ed. in English)》2023,62(6):e202215963
Earth-abundant transition metal catalysis has emerged as an important alternative to noble transition metal catalysis in hydrogenation reactions. However, there has been no Earth-abundant transition metal catalyzed hydrogenation of thioamides reported so far, presumably due to the poisoning of catalysts by sulfur-containing molecules. Herein, we described the first manganese-catalyzed hydrogenative desulfurization of thioamides to amines or imines. The key to success is the use of MnBr(CO)5 instead of commonly-employed pincer-manganese catalysts, together with simple NEt3 and CuBr. This protocol features excellent selectivity on sole cleavage of the C=S bond of thioamides, in contrast to the only known Ru-catalyzed hydrogenation of thioamides, and unprecedented chemo-selectivity tolerating vulnerable functional groups such as nitrile, ketone, aldehyde, ester, sulfone, nitro, olefin, alkyne and heterocycle, which are usually susceptible to common hydride-type reductive protocols. 相似文献
32.
S. P. Savin V. V. Lyahov V. M. Neshchadim E. Amata J. L. Rauch V. P. Silin V. Yu. Popov V. P. Budaev S. I. Klimov A. A. Skalsky L. A. Legen J. Blecki 《Bulletin of the Lebedev Physics Institute》2017,44(4):99-105
The theory of charged current sheets is compared with plasma data of Prognoz-8, Interball-1, Polar, and Cluster satellites. The possibility of momentum and energy transfer into the magnetosphere, irrespective of magnetic field line reconnection, as a specific dynamo effect, is shown. This relates statistical properties of the turbulent boundary layers with the character of the transfer through thin boundaries. 相似文献
33.
It is demonstrated that a chain of fast vortices produces a peak in the current–voltage characteristic of an annular Josephson junction coupled to a waveguide. 相似文献
34.
The energy spectrum of a new-type quantumwell composed of gapless graphenes with identical work functions and different Fermi velocities is investigated. Symmetric and asymmetric quantum wells are considered. In a symmetric well, there is always at least one bound state. In an asymmetric well, a bound state appears, beginning at a certain finite momentum. A possibility of appearance of boundary states is investigated. 相似文献
35.
36.
Variational methods have been successfully used in modelling thin liquid films in numerous theoretical studies of wettability.
In this article, the variational model of the disjoining pressure is extended to the general case of a two-dimensional solid
surface. The Helmholtz free energy functional depends both on the disjoining pressure isotherm and on the shape of the solid
surface. The augmented Young–Laplace equation (AYLE) is a nonlinear second-order partial differential equation. A number of
solutions describing wetting films on spherical grains have been obtained. In the case of cylindrical films, the phase portrait
technique describes the entire variety of mathematically feasible solutions. It turns out that a periodic solution, which
would describe wave-like wetting films, does not satisfy Jacobi’s condition of the classical calculus of variations. Therefore,
such a solution is nonphysical. The roughness of the solid surface significantly affects liquid film stability. AYLE solutions
suggest that film rupture is more likely at a location where the pore-wall surface is most exposed into the pore space, and
the curvature is positive. 相似文献
37.
An Asymptotic Model of Seismic Reflection from a Permeable Layer 总被引:1,自引:0,他引:1
Analysis of compression wave propagation in a poroelastic medium predicts a peak of reflection from a high-permeability layer
in the low-frequency end of the spectrum. An explicit formula expresses the resonant frequency through the elastic moduli
of the solid skeleton, the permeability of the reservoir rock, the fluid viscosity and compressibility, and the reservoir
thickness. This result is obtained through a low-frequency asymptotic analysis of Biot’s model of poroelasticity. A review
of the derivation of the main equations from the Hooke’s law, momentum and mass balance equations, and Darcy’s law suggests
an alternative new physical interpretation of some coefficients of the classical poroelasticity. The velocity of wave propagation,
the attenuation factor, and the wave number are expressed in the form of power series with respect to a small dimensionless
parameter. The absolute value of this parameter is equal to the product of the kinematic reservoir fluid mobility and the
wave frequency. Retaining only the leading terms of the series leads to explicit and relatively simple expressions for the
reflection and transmission coefficients for a planar wave crossing an interface between two permeable media, as well as wave
reflection from a thin highly permeable layer (a lens). Practical applications of the obtained asymptotic formulae are seismic
modeling, inversion, and attribute analysis. 相似文献
38.
A series of 2,3-disubstituted thiazolidin-4-ones containing 4-hydroxy-3,5-di(tert-butyl)phenyl groups has been synthesized. For preparation of these sterically hindered compounds the condensation of thioglycolic acid with azomethines — derivatives of 4-hydroxy-3,5-di(tert-butyl)benzaldehyde was used.I. M. Gubkin Russian State University for Petroleum and Gas, Moscow 117917. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 256–260, February, 2000. 相似文献
39.
40.
In this paper, we model water injection through a growing vertical hydrofracture penetrating a low-permeability reservoir. The results are useful in oilfield waterflood applications and in liquid waste disposal through reinjection. Using Duhamel's principle, we extend the Gordeyev and Entov (1997) self-similar 2D solution of pressure diffusion from a growing fracture to the case of variable injection pressure. The flow of water injected into a low-permeability rock is almost perpendicular to the fracture for a time sufficiently long to be of practical interest. We revisit Carter's model of 1D fluid injection (Howard and Fast, 1957) and extend it to the case of variable injection pressure. We express the cumulative injection through the injection pressure and effective fracture area. Maintaining fluid injection above a reasonable minimal value leads inevitably to fracture growth regardless of the injector design and the injection policy. The average rate of fracture growth can be predicted from early injection. A smart injection controller that can prevent rapid fracture growth is needed. 相似文献