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41.
We consider the possibility of the existence of media in acoustics that are similar in several effects to the widely discussed electrodynamic left-handed media. The density and compressibility of a medium are shown to be the mechanical analogues of negative permittivity and permeability. We discuss the physical meaning of their negativity and mechanical models with such properties. To identify the effects related to the sign of the density and compressibility, we have performed our analysis based on linearized hydrodynamic equations instead of the wave equation or the Helmholtz equation. We have obtained an analogue of the Lippmann—Schwinger equation and constructed a theory of wave scattering by inhomogeneities in a medium with arbitrary values and signs of the density and compressibility. Our numerical simulations have revealed all of the expected effects. We consider the questions concerning the fulfillment of the causality principle and its consequences generalized to the case of negative media in the form of a connection between the damping and dispersion of waves. 相似文献
42.
O. D. Rumyantseva V. A. Burov A. L. Konyushkin N. A. Sharapov 《Acoustical Physics》2009,55(4-5):613-629
Ways for increasing the information value of practical methods of acoustic tomography are considered. A simple method for increasing the resolution of a 2D acoustic tomograph in the direction perpendicular to the tomography plane due to transducer inclination is proposed. An algorithm for separate reconstruction of refraction, density, and absorption components of the scatterer in the case of incomplete scattering data at three frequencies is proposed. The possibility of estimation of the character of frequency dependence of the absorption coefficient as an additional diagnostic parameter is demonstrated. 相似文献
43.
O. N. Burov A. V. Gulevskaya A. F. Pozharskii 《Chemistry of Heterocyclic Compounds》2009,45(4):475-482
The oxidative alkylamination of 2-methyl-3(2H)-cinnolinone by secondary alkylamines in the presence of KMnO4 leads to the smooth formation of the expected 4-alkylamino-2-methyl-3(2H)-cinnolinones. The analogous reaction with primary
alkylamines is accompanied by the partial or complete N-dealkylation of the entering alkylamino group depending on the temperature.
*Dedicated with gratitude to an outstanding heterocyclic chemist, Prof. Henk van der Plas on the occasion of his eightieth
jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 602-611, April, 2009. 相似文献
44.
S. G. Bondarenko V. V. Burov S. A. Yurev 《Physics of Particles and Nuclei Letters》2018,15(4):417-421
In the paper the covariant kernel of the nucleon-nucleon interaction of particles with scalar propagators is analyzed. The Bethe–Salpeter equation for the T matrix is considered in the rank-one separable kernel. The parameters of the kernel for the specific partial-wave channels explicitly connect with the observables low energy scattering parameters and phase shifts, deuteron binding energy. Covariant separable kernels for the partial-wave channels with total angular momentum J = 0 (1S0, 3P0) and J =1 (3S1 ? 3D1, 1P1, 3P1) are constructed. 相似文献
45.
46.
47.
A. P. Mitev V. L. Strashilov J. I. Burov 《Applied Physics A: Materials Science & Processing》1991,52(6):369-372
A method for direct measurement of the temperature coefficients of the velocities of bulk acoustic waves propagating along arbitrary directions in crystal planes is described. It represents a specific version of the Schaefer-Bergmann acoustooptic diffraction in which the effect of the temperature is precisely compensated by biasing the acoustic frequency. The method is equally applicable to the determination of other kinds of velocity coefficients. 相似文献
48.
49.
Dmitrii Yu. Vandyshev Oleg N. Burov Anton V. Lisovin Daria A. Mangusheva Mikhail A. Potapov Tatiana N. Ilyinova Khidmet S. Shikhaliev Athina Geronikaki Domenico Spinelli 《Molecules (Basel, Switzerland)》2022,27(10)
A new effective method for the synthesis of imidazo[1,5-b]pyridazines derivatives (yields = 68–89%) by the interaction of 1,2-diamino-4-phenylimidazole with DMAD, in methanol and in the presence of a catalytic amount of acetic acid, is proposed. The course of reaction has been examined by classical organic methods, HPLC-MS analysis, and quantum-chemical calculations. 相似文献
50.
The B3LYP/6-31G** quantum chemical method was used to study the mechanism of the oxidative alkylamination of diazinones taking 1,3,6-trimethylpyrimido[4,5-d]pyrimidine-2,4,7(1H,3H,6H)-trione (lumazinone) as an example. The first limiting step of this reaction included a nucleophilic addition of alkylamine with the formation of the σH-adduct, which was oxidized by potassium permanganate in the second step. The alkylamination step proceeded in the associates formed by the lumazinone dimer and several alkylamine molecules involved in both the nucleophilic attack and the bifunctional catalysis of the process. The correlation of the Parr indices with the experimental data was studied for a number of diazinones. 相似文献