A METHOD PROVING THE UNIQUENESS OF THE LIMIT CYCLE OF THE QUADRATIC SYSTEM

ＡＭＥＴＨＯＤＰＲＯＶＩＮＧＴＨＥＵＮＩＱＵＥＮＥＳＳＯＦＴＨＥＬＩＭＩＴ　ＣＹＣＬＥＯＦＴＨＥＱＵＡＤＲＡＴＩＣＳＹＳＴＥＭＸｕＳｉｌｉｎ（徐思林）（ＱｉｎｇｄａｏＵｎｉｖｅｒｓｉｔｙ，青岛大学，邮编：２６６０７１）ＺｈｕＹｕｇｅｎ（朱豫根）（Ｎａ...     

Synthesis of 2,5-disubstituted 1,3,4-oxadiazoles containing benzothiazolylthiol grouping

A series of 2,5-substituted 1,3,4-oxadiazoles containing 2-benzothiazolylthiomethyl grouping has been synthesized by condensing derivatives of (2-benzothiazolylthio)acetic acid with imino ester hydrochlorides and hydrazides of carboxylic acids, by the cyclodehydration of N-acyl-N-(2-benzothiazolylthioacetyl)hydrazines under the action of POCl, and also by the reaction of 2-mercaptobenzothiazole with 2-chloromethyl-1,3,4-oxadiazoles in the presence of sodium methylate.I. M. Gubkin Russian State University for Petroleum and Gas, Moscow 117917. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 249–255, February, 2000.     

由分子的价电子总数判断中心原子轨道杂化方式的方法

提出了由分子的价电子总数判断中心原子轨道杂化方式的方法,探讨了该方法的理论依据,分析、归纳出了等电子分子系列中原子轨道杂化方式的周期性变化规律。     

Alkylation of 3‐Phenyl‐1H‐pyrazolo[4,3‐c] quinoline: Theoretical Analysis of Regioselectivity

The interaction of 3‐phenyl‐1H‐pyrazolo[4.3‐c]quinoline with alkylating agents in the presence of NaH leads mainly to N1‐substituted derivatives. The regioselectivity of the reaction has been studied using AM1 semi‐empirical calculations in the isolated molecule approximation.     

含氧光敏引发体系的研究——Ⅵ.二苯酮/三乙胺体系引发光聚合过程中的再次引发效应

过去,作者曾发表了多种光敏引发体系引发烯类单体光聚合的工作,在研究2,2-二甲氧基苯乙酮在氧存在下引发甲基丙烯酸甲酯光聚合时,结合在聚合物链端的引发剂碎片具有光化学活性,在光聚合反应中产生高分子自由基,发生再次聚合,出现高分子量     

Transverse zero-sound waves in two-component Fermi liquid

The spectra of transverse zero-sound waves in a two-component degenerate Fermi liquid were studied. The ranges of the existence of two and one waves were determined depending on the liquid interaction parameters.     

A Variational Model of Disjoining Pressure: Liquid Film on a Nonplanar Surface

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.     

An Asymptotic Model of Seismic Reflection from a Permeable Layer

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.     

Interference scheme with transverse shift of beams for remote precision monitoring of parameters of optical elements

In this paper, we present a new interference scheme with transverse shift of beams for remote monitoring of parameters of optical elements. The results of studying the measurement accuracy are given and the main noise sources of the presented scheme are considered. The advantages of this scheme are the high accuracy (the experimentally realized accuracy is higher than λ/3000, where λ is the wavelength of the sounding radiation), high speed allowing us to study nonstationary processes, and selectivity ensuring the study of a given surface by using other optical elements of the scheme. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 7, pp. 638–648, July 2007.     

Radionuclide Sources 57Co and 119mSn for Industrial Application of the Mössbauer Effect

Technical and resonance parameters of ⁵⁷Co and ^119mSn Mössbauer sources and some examples of their science and industrial applications are presented.