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11.
T. A. Labutin A. M. Popov S. M. Zaytsev I. A. Cal’ko N. B. Zorov 《Optics and Spectroscopy》2016,120(3):339-344
Features of electromagnetically induced transparency (EIT) in potassium vapors at the D1 line of the 39K isotope are studied. EIT resonances with a subnatural width of 3.5 MHz have been recorded upon excitation by two independent narrow-band diode lasers in a 1-cm-long cell filled with a natural mixture of potassium isotopes and buffer gas. The splitting of EIT resonances in potassium vapors in longitudinal and transverse magnetic fields has been studied for the first time. The splitted components also have a subnatural width. The smallness of the coupling factor of the hyperfine structure in 39K atoms leads to a transition to the Paschen—Back regime at relatively weaker magnetic fields than in the case of Cs, Rb, and Na atoms. Practical applications of the phenomena under study are noted. The theoretical model well explains the experiment. 相似文献
12.
V. F. Kopiev M. Yu. Zaytsev V. I. Vorontsov S. A. Karabasov V. A. Anikin 《Acoustical Physics》2017,63(6):686-698
The aeroacoustic characteristics of a helicopter rotor are calculated by a new method, to assess its applicability in assessing rotor performance in hovering. Direct solution of the Euler equations in a noninertial coordinate system is used to calculate the near-field flow around the spinning rotor. The far-field noise field is calculated by the Ffowcs Williams–Hawkings (FW–H) method using permeable control surfaces that include the blade. For a multiblade rotor, the signal obtained is duplicated and shifted in phase for each successive blade. By that means, the spectral characteristics of the far-field noise may be obtained. To determine the integral aerodynamic characteristics of the rotor, software is written to calculate the thrust and torque characteristics from the near-field flow solution. The results of numerical simulation are compared with experimental acoustic and aerodynamic data for a large-scale model of a helicopter main rotor in an open test facility. Two- and four-blade configurations of the rotor are considered, in different hover conditions. The proposed method satisfactorily predicts the aerodynamic characteristics of the blades in such conditions and gives good estimates for the first harmonics of the noise. That permits the practical use of the proposed method, not only for hovering but also for forward flight. 相似文献
13.
V. F. Kopiev I. V. Khramtsov M. Yu. Zaytsev E. S. Cherenkova O. Yu. Kustov V. V. Palchikovskiy 《Acoustical Physics》2018,64(4):503-510
A technique for studying the aeroacoustic parameters of vortex rings with various diameters in an anechoic chamber is developed. The motion trajectories of vortex rings produced by a piston generator with nozzles with various exit diameters are studied. Spectral analysis of the noise of vortex rings for various distances from nozzles with various diameters is carried out. For the first time, the dependences of the fundamental radiation frequency on the time of a ring’s motion are obtained in dimensionless form. The data on noise from turbulent vortex rings confirm the conclusion that sound from rings with different diameters and velocities is emitted by the same mechanism. 相似文献
14.
S. Yu. Zaytsev P. E. Plyusnin E. M. Slavinskaya Yu. V. Shubin 《Journal of nanoparticle research》2017,19(11):367
Colloidal suspensions of AuxPd1-x nanoalloys were prepared via hydrazine co-reduction of [AuCl4]? and [PdCl4]2? complex anions in aqueous solution. High molecular weight polymeric compounds polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and cryptoionic surfactants (AF-6 and AF-12 neonols, Triton X-100) were used as surface capping agents. Nanoparticles prepared under different experimental conditions were immobilized on γ-Al2O3 supports. The removal of the capping agents from the surface of the active particles was achieved through calcination of samples in oxidative atmosphere (air, 500 °C). This pretreatment of the catalysts significantly enhances their performance. Powder XRD, TEM, and EDX were employed to characterize the structure, size, and composition of the AuxPd1-x/γ-Al2O3 catalysts. The immobilized particles consist of uniformly mixed alloys having multi-domain face-centered cubic structure with typical crystallite size of 3–6 nm. The activity of the prepared samples was examined with temperature-programmed CO oxidation reaction (TP-CO+O2). Triton X-100 surfactant is superior in a number of parameters. Among all AuxPd1-x/γ-Al2O3 catalysts tested, the one stabilized with Triton X-100 (0.4%Au-0.2%Pd@Triton X-100) was found to have the highest activity for conversion of CO into CO2. 相似文献
15.
V. Ch. Zhukovsky V. D. Krevchik M. B. Semenov R. V. Zaytsev D. O. Filatov P. V. Krevchik A. A. Bukharaev 《Moscow University Physics Bulletin》2014,69(4):340-348
Experimental results on the visualization of the density of states in InAs/GaSa(001) quantum dots that were obtained by tunnel atomic-force microscopy in an ultrahigh vacuum are presented. A one-dimensional (1D) model of dissipative quantum tunneling is proposed for describing experimental current-voltage characteristics of a tunnel contact between an atomic force microscope probe and the surface of InAs/GaAs (001) quantum dots. It was found that the influence of two local modes of the wide-band matrix on the probability of 1D dissipative tunneling leads to the appearance of several randomly spaced peaks in the field dependence. It was shown that the theoretical dependence agrees qualitatively with experimental the current-voltage characteristic of the atomic force microscope tip and the surface of InAs/GaAs(001) quantum dots. 相似文献
16.
F. I. Zubkov V. P. Zaytsev I. K. Airiyan V. D. Golubev E. S. Puzikova E. A. Sorokina E. V. Nikitina A. V. Varlamov 《Russian Chemical Bulletin》2012,61(3):600-605
1-Oxo-3a,6-epoxyisoindolones oxidized with potassium permanganate to give 4,5-dihydroxy-3a,6-epoxyisoindolones, while oxidation with peroxyformic acid or 3-chloroperoxybenzoic acid yielded 2,6a-epoxyoxirano[e]isoindolones. Oxidation proceeded with selective formation of exo-cis-adducts. 相似文献
17.
Alexander A. Voronov Kseniia A. Alekseeva Elena A. Ryzhkova Vladimir V. Zarubaev Anastasia V. Galochkina Vladimir P. Zaytsev Mahesh S. Majik Santosh G. Tilve Atash V. Gurbanov Fedor I. Zubkov 《Tetrahedron letters》2018,59(12):1108-1111
The reaction between readily accessible N-aryl-3-phenylallylamines and maleic anhydride led to unexpected products – polysubstituted hydrogenated benzo[f]isoindole-4-carboxylic acids. This transformation proceeds through a previously unknown sequence of steps: N-acylation of the allylamine with maleic anhydride, intramolecular Diels-Alder reaction of the vinylarene in the intermediate N-maleamide, and Alder-ene reaction of the products of the previous two steps. Selected benzo[f]isoindoles displayed antiviral activity. 相似文献
18.
We describe the Galois closure of the Garcia–Stichtenoth tower and prove that it is optimal. 相似文献
19.
Acoustical Physics - An experimental study of noise reduction methods has been carried out for realistic small-scale (1 : 10) models of aircraft landing gear based on two ideas:... 相似文献