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21.
22.
In this paper, shrinking via the vacancy mechanism of a hollow mono-atomic nanosphere is described. Using Gibbs–Thomson boundary conditions, an exact solution is obtained for the kinetic equation in quasi steady-state at the linear approximation. Collapse time as a function of the geometrical size of a hollow nanosphere is found. An extension to hollow binary alloy nanospheres is also made. Previous Monte Carlo simulations of this problem are discussed. 相似文献
23.
24.
N.A. Babushkina L.M. Belova E.A. Chistotina O.Yu. Gorbenko A.R. Kaul B. Güttler K.I. Kugel 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(3):409-415
The effect of
16
O
→
18
O isotope substitution on electrical resistivity, magnetoresistance, and ac magnetic susceptibility was studied for La0.35Pr0.35Ca0.3MnO3 epitaxial thin films deposited onto LaAlO3 and SrTiO3 substrates. For the films on LaAlO3, the isotope substitution resulted in the reversible transition from a metal-like to insulating state. The applied magnetic
field ( H
≥ 2
T) transformed the sample with 18O back to the metallic state. The films on SrTiO3 remained metallic at low temperatures for both 16O and 18O, but the shift of the resistivity peak corresponding to onset of metallic state exceeded 63 K after
16
O
→
18
O substitution. The temperature dependence of both resistivity and magnetic susceptibility was characterized by hysteresis,
especially pronounced in the case of the films on LaAlO3. Such a behavior gives certain indications of the phase separation characteristic of interplay between ferromagnetism and
charge ordering.
Received 11 February 2000 and Received in final form 13 September 2000 相似文献
25.
A. B. Maidina A. B. Belova A. V. Levashov N. L. Klyachko 《Moscow University Chemistry Bulletin》2008,63(2):108-110
This work studies safflower oil hydrolysis catalyzed by Candida rugosa lipase as a function of temperature in an oil-in-water emulsion stabilized by the surfactant sodium deoxycholate. The choice of temperature for this reaction is dictated by the effects of temperature not only on the catalytic activity and stability of the enzyme but also on the state of the reaction medium (emulsion), whose quality substantially affects both the kinetic parameters of lipase and the product (linoleic acid) yield. For example, although the highest initial rate of the enzymatic reaction is observed at 40°C and the enzyme is virtually not inactivated during incubation (45°C), the highest reaction yield is observed at 30°C and decreases upon temperature elevation because of a change in the emulsion quality. 相似文献
26.
An ab initio study of the structure of Mn(thd)2, Fe(thd)2, and Co(thd)2 complexes in different electronic states is carried out. Quantum chemical calculations are performed using the PC GAMESS
program with relativistic effective core pseudopotentials and Gaussian valence triple-zeta basis sets. Calculation methods:
DFT/ROB3LYP and CASSCF followed by the inclusion of dynamic electron correlation through multiconfiguration quasi-degenerate
second order perturbation theory (MCQDPT2). All three complexes are shown to have a low-spin electronic ground state with
a planar structure of the bicyclic fragment at D
2h
molecular symmetry. The M—O bond is mainly ionic, and M(thd)2 molecules can be considered as an M2+ cation coordinated by two negatively charged bidentate ligands. 相似文献
27.
N. D. Pismenskaya V. V. Nikonenko E. I. Belova G. Yu. Lopatkova Ph. Sistat G. Pourcelly K. Larshe 《Russian Journal of Electrochemistry》2007,43(3):307-327
Mechanisms responsible for the overlimiting ion transfer in membranes systems are discussed. The overlimiting transfer is shown to be due largely to the action of four effects coupled with the concentration polarization of the system. Two of these are connected with the water dissociation near the membrane/solution interface: the emergence of additional charge carriers (ions H+ or OH?) in the depleted solution layer and the exaltation of transfer of salt counterions. The latter effect is connected with the perturbation of electric field caused by the water dissociation products. The other two effects are two versions of coupled convection, which leads to partial destruction of the depleted diffusion layer. These include gravitational convection and electroconvection. The former is caused by the emergence of the solution’s density gradient. The latter develops via a mechanism of electroosmotic slip. In this work, methods of voltammetry and chronopotentiometry and pH measurements are used to study the transfer of ions through homogeneous membranes Nafion-117 and AMX as a function of the concentration of sodium chloride solutions in the underlimiting and overlimiting current regimes. In a 0.1 M NaCl solution, gravitational convection makes a considerable contribution to the transfer of salt ions near the membrane surface in intensive current regimes. The influence of this effect on the electrochemical behavior of membrane systems weakens with the solution dilution and with increasing relative transfer of the H+ and OH? ions that are generated at the membrane/solution interface. In conditions where gravitational convection is suppressed and the water dissociation near the membrane/solution interface is not great, the major contribution to the overlimiting growth of current is made by electroconvection. Topics for discussion in the paper include the mutual influence of effects on one another, in particular, the effect the rate of generation of the H+ and OH? ions exerts on the gravitational convection and electroconvection and the reasons for the different behavior of cation-and anion-exchange membranes in intensive current regimes. 相似文献
28.
Gulyaev V. I. Lugovoi P. Z. Solov'ev I. L. Belova M. A. 《International Applied Mechanics》2002,38(9):1131-1137
Consideration is given to bifurcation problems for thin-walled spherical shells in simple and compound rotation. Similarities and differences in the formulations of such problems and techniques for their solution are pointed out. In both cases, the buckling mode is described by the first circumferential harmonic. An analysis is made of how the bifurcations of a shell depend on its geometry. 相似文献
29.
V. I. Gulyaev P. Z. Lugovoi M. A. Belova I. L. Solov’ev 《International Applied Mechanics》2006,42(6):692-698
The quasistatic stability of a rotating drillstring under longitudinal force and torque is analyzed. Constitutive equations
are derived, and a technique to solve them is proposed. It is shown that the buckling mode of the drillstring is helical within
a section subjected to compressive forces
__________
Translated from Prikladnaya Mekhanika, Vol. 42, No. 6, pp. 101–109, June 2006. 相似文献
30.
M. S. Belova D. G. Korovina V. N. Tsygankov A. B. Varava I. P. Savchenkova O. A. Legon’kova 《Polymer Science Series D》2017,10(4):357-360
This paper considers the evaluation of the biosafety of cyanoacrylate adhesive in vitro on human multipotent mesenchymal stem cells. This adhesive is intended for medical use, in particular, for X-ray and endovascular interventions. A toxicity study was carried out in a culture of multipotent mesenchymal stem cells isolated from human subcutaneous fat. As a result of the work, the concentration of cyanoacrylate adhesive in lipiodol was chosen, which has the lowest toxicity. 相似文献