Synthesis, Structure, and Membrane Activity of New Glycyrrhetic Acid Derivatives

Derivatives of 3-O-acetyl-18-H-glycyrrhetic acid were synthesized. Their structures and membrane activities were studied.     

Zeeman effect in the luminescence spectra of terbium-yttrium-aluminum garnet

The Zeeman effect is investigated in the green luminescence band corresponding to the 4f→4f radiative transition ⁵D₄ → ⁷F₅ of Tb ³⁺ ions in Tb _0.2 Y _2.8 A _l5 O ₁₂ terbium-yttrium-aluminum garnet at the temperature T = 85 K. It is demonstrated that an external field causes not only the Zeeman shifts of the resonant frequencies of radiative transitions in the luminescence spectra but also changes in the emission line intensities caused by modification of the optical transition probabilities in the σ₋ and σ₊ opposite circular polarization states. Special features of field dependences of the Zeeman effect for the emission lines are qualitatively explained based on the results of numerical energy spectrum calculations for the ⁵D₄ and ⁷F₅ multiplets of the Tb ³⁺ ion in yttrium-aluminum garnet in the geometry of the longitudinal and transverse Zeeman effects. The possibility of nonequilibrium population of sublevels of the (Γ₁, Γ₄) quasi-doublet state of the ⁵D₄ multiplet with energy of ∼20585 cm⁻¹ is demonstrated in an external magnetic field. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 38–45, June, 2008.     

On new two-dimensional structures produced on the Si (111) and Si (100) surface upon molecular-beam epitaxy of cobalt and silicon

Highly perfect epitaxial heterostructure CoSi₂ films have been grown on the surface of Si (111) and Si (100) single crystals by the method of molecular-beam epitaxy. The optimal regimes of the film growth with different thicknesses have been determined. It has been shown that short-term annealing of epitaxial films at T = 900–950 K leads to the formation of new CoSi₂/Si(111)-2 × 2 and CoSi₂/Si(100)−2 × 4 superstructures.     

Optimization of Temperature Dependence of Heteronanolaser Threshold Current with Account for the Thickness and Dielectric Properties of the Heterostructure Waveguide Nano-Layer Material

Russian Physics Journal - An exact problem of the electromagnetic wave propagation in a multilayer heteronanostructure with complex values of the dielectric constant (permittivity) is solved. The...     

Effect of the transformation of the magnetic structure of a FeBO<Subscript>3</Subscript>:Mg crystal on its magnetooptical anisotropy

The field dependence of the magnetic linear birefringence (MLB) in easy-plane weak FeBO₃:Mg ferromagnet has been investigated. It is found that MLB nonmonotonically (stepwise) tends to a constant value with an increase in magnetic field at low temperatures. This feature of MLB in FeBO₃:Mg is related to the transformation of the crystal magnetic structure during magnetization.     

Rate of convergence of discretization methods for the wave equation with generalized solutions

Exact difference scheme operators are applied to construct a method of lines scheme and a difference scheme for a multidimensional hyperbolic equation. An accuracy bound compatible with the smoothness of the solution of the differential problem is defined for the method of lines and the grid method. The accuracy of the two schemes is established in the sense of this definition. A computational experiment shows that the lower accuracy of the method of lines and the grid method for the hyperbolic equation compared with the accuracy bounds for elliptic and parabolic equations is attributable to the specific features of the hyperbolic equations.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 57, pp. 26–33, 1985.     

On Goursat and Dirichlet problems for one equation of the third order

We study the problem of the unique solvability of Goursat and Dirichlet problems for one partial differential equation of the third order. We construct a Riemann function for a linear third-order equation with a hyperbolic operator in the principal part, study some properties of the Riemann function, and then use them to prove theorems on the existence and uniqueness of a solution of the problems indicated. Translated from Neliniini Kolyvannya, Vol. 11, No. 3, pp. 305–315, July–September, 2008.