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排序方式: 共有683条查询结果,搜索用时 31 毫秒
31.
D. V. Antonov G. V. Kuznetsov P. A. Strizhak 《Journal of Engineering Thermophysics》2016,25(3):337-351
Characteristic temperatures and concentrations of a vapor–gas mixture in a wake of water droplets moving through combustion products (initial temperature 1170 K) were determined using the Ansys Fluent mathematical modeling package. We investigated two variants of motion: motion of two droplets (with sizes from 1 mm to 3 mm), consecutive and parallel, and motion of five staggered droplets. The influence of the relative position of droplets and also of distances between them (varied from 0.01 mm to 5 mm) on temperatures and concentrations of water vapor was established. The distances determine the relation between the evaporation areas and the total volume occupied by a droplet aggregate in the gas medium. The results of modeling for conditions that take into account vaporization on the droplet surface at average constant values of evaporation rate and also with consideration of the change in the latter, depending on the droplet temperature field, are compared. We determined conditions under which the modeling results are comparable for the assumption of a constant vaporization rate and with regard to the dependence of the latter on temperature. The earlier hypothesis on formation of a buffer vapor layer (“thermal protection”) around a droplet, which decreases the thermal flow from the external gas medium, was validated. 相似文献
32.
E. V. Kudryashova I. M. Deygen K. V. Sukhoverkov L. Yu. Filatova N. L. Klyachko A. M. Vorobei O. I. Pokrovskiy K. B. Ustinovich O. O. Parenago E. N. Antonov A. G. Dunaev L. I. Krotova V. K. Popov A. M. Egorov 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(8):1201-1210
The process of micronization of levofloxacin (LF, an antibacterial agent of the fluoroquinolone group) by the supercritical antisolvent precipitation technique (SAS) was investigated. It was shown that LF particles of different sizes (from 1 to 10 μm) and of various morphologies (from thin plates to elongated parallelepipeds) can be produced depending on the type of solvent used for conducting micronization. Investigation of the micronized LF preparations using the methods of IR-Fourier spectroscopy, Raman scattering, and circular dichroism showed that the LF micronization caused neither changes in its chemical structure nor racemization. Micronization of LF significantly affects the rate of its dissolution in model systems exhibiting effects dependent on the type of the solvent used for micronization. For example, the highest rate of dissolution at pH 4 was observed for LF preparations micronized with the help of chlorohydrocarbons. It was shown that the rate of dissolution of all micronized LF preparations was higher by 15–30% in comparison with the initial LF, which likely was related to the changes in the degree of crystallinity/amorphousness, as well as of morphologies of microparticles formed in the SAS process. 相似文献
33.
D. A. Antonov D. O. Filatov A. V. Zenkevich Yu. Yu. Lebedinskii 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(1):56-58
The tunneling of electrons through Au nanoc lusters formed by pulsed laser deposition in a SiO2 thin film on a Si substrate has been investigated by combined scanning/atomic force microscopy (STM/AFM). Conducting Pt-coated Si cantilevers were used. The feedback was maintained via the AFM channel, and the current-voltage (I-V) characteristics of the tunnel contact between the AFM probe and the n +-Si substrate through a =4-nm-thick SiO2 film with Au nanoclusters =2 nm in diameter were measured simultaneously. The current image of the structure contained areas of increased current (tunnel-current channels) 2–15 nm in size, related to tunneling of electrons through Au nanoclusters in SiO2. The I-V characteristics recorded in the tunnel-current channels exhibit specific features related to the Coulomb blockade of electron tunneling through Au nanoclusters. 相似文献
34.
Kholupenko E. E. Krassilchtchikov A. M. Badmaev D. V. Bogdanov A. A. Tuboltsev Yu. V. Chichagov Yu. V. Antonov A. S. Kuleshov D. O. Khil’kevich E. M. 《Technical Physics》2020,65(6):886-895
Technical Physics - Source and noise signals in a new camera of the TAIGA-IACT Cherenkov γ-ray telescope based on silicon photomultipliers (SiPM) have been simulated. It is shown that... 相似文献
35.
K. R. Karimov A. I. Anfinogenov Ya. B. Chernov V. V. Chebykin A. A. Pankratov B. D. Antonov 《Russian Journal of Applied Chemistry》2010,83(10):1804-1810
Possibility of producing zinc-aluminide coatings by thermal diffusion impregnation of steels under mechanical activation of
the surface of samples in a rotating reactor was analyzed. 相似文献
36.
It is demonstrated that laser irradiation causes formation of complicated fractal structures (classical dendrites) on a steel surface. The distribution of dendrites over the irradiated region can be controlled using variations in the profile of the incident laser beam. Electron microscopy is used to evaluate the size distributions of dendrites and the surface distribution density. 相似文献
37.
D. O. Filatov D. A. Antonov S. Yu. Zubkov A. V. Nezhdanov A. I. Mashin 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(1):12-16
The morphology, electronic structure, and optical properties of self-assembled silicon nanostructures grown on the surface
of Highly Oriented Pyrolytic Graphite (HOPG) by molecular beam epitaxy were studied by ultra high vacuum (UHV) scanning tunneling
microscopy (STM) and X-ray photoemission spectroscopy (XPS) in situ, and by Raman spectroscopy ex situ. At coverages of less
than 1 monolayer (ML), the formation of monolayered silicon nanoislands with an atomic structure similar to that of graphene
was observed. 相似文献
38.
39.
Natalia V. Vorontsova Galina S. Bystrova Dmitrii Yu. Antonov Anna V. Vologzhanina Ivan A. Godovikov Michail M. Il’in 《Tetrahedron: Asymmetry》2010,21(6):731-738
New planar-chiral hydroxycarbonyl [2.2]paracyclophane derivatives, 4-acetyl-13-bromo-5-hydroxy[2.2]paracyclophane (Br-АНРС, 63%) and 4-benzoyl-13-bromo-5-hydroxy[2.2]paracyclophane (Br-BHPC, 53%), were synthesized and reacted with the enantiomers of α-phenylethylamine to form corresponding Schiff bases, 12-bromo-4-hydroxy-5[1-(1-phenyl-ethylimino)-ethyl]-[2.2]paracyclophane and 12-bromo-4-hydroxy-5[1-(1-phenyl-ethylimino)-(phenyl)methylen-[2.2]paracyclophane. The diastereomers of the imines were resolved and their absolute configurations and consequently the corresponding configurations of the enantiomers of Br-АНРС were determined by X-ray diffraction. Enantiomerically pure Schiff bases were applied as ligands to form catalysts for the enantioselective addition reaction of diethylzinc with benzaldehyde where 1-phenylpropanol was obtained with 77–91% ee. 相似文献
40.
A. Yu. Antonov N. V. Egorov L. C. Chao 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(5):826-832
The problem of determining the coefficient of electron transmission through the potential barrier at the metal-vacuum interface
is considered. The temperature dependence of the thermofield’s current density is studied using methods of mathematical modeling.
The problem is reduced to the solution of a system of algebraic equations. It is shown that regularization of the solution
of the problem is required. The results demonstrate that the coefficient of electron transmission can be determined in principle. 相似文献