Superradiance and superradiance without inversion of a thin layer of three-level atoms: The consideration of the sample extent

The effect of the sample extent in the process of superradiance and superradiance without population inversion of a thin (L ≤ λ) layer of three-level atoms (Λ-configuration of working transitions) is investigated. The limits of applicability of the spatially homogeneous approximation are determined. The consideration of the extent is shown to introduce new effects into the kinetics of populations and the field.     

Synthesis of N-acetyllactosamine based branched hexasaccharide

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Equations of transonic flows of relaxing mixtures

Transonic flows of chemically active gas mixtures whose composition is defined by an arbitrary number of reactions are considered. Conditions ensuring a closeness of the frozen and equilibrium velocities of sound are imposed on the equations of state. An approximate system of equations for vectors of particle velocity and completeness of reactions is obtained as a result of an asymptotic analysis of the system of Euler equations and the equations of chemical reactions associated with them. This system reduces to two equations containing only components of the particle velocity; the order of one of them equals the number of reactions increased by one, while the second equation expresses the nonvorticity condition of the stream. Various limit cases dependent on the magnitude of eigenvalues of the relaxation matrix are pointed out.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 139–148, July–August, 1977.     

Formation of recirculation zones in the boundary layer on a moving surface

A study is made of the region of free interaction of a supersonic boundary layer on a moving surface formed by a weak shock wave impinging on it from without. In the equations of motion, allowance is made for the contribution of the pressure induced by the growth in the displacement thickness of jets passing near the surface. The results are given of the numerical solution of the corresponding nonlinear problem, and the basic structure of the recirculation zones is discussed. It is noted that there are regimes in which the main recirculation zone is accompanied by an additional eddy formation with circulation in the opposite direction. In contrast to a boundary layer on a fixed body, the points at which the streamlines separate are not on the wall but within the flow.Translated from Izvestiya Akademii Nauk SSSR, Meklianika Zhidkosti i Gaza, No. 5, pp. 3–10, September–October, 1980.     

Complex phase behavior of the system of particles with smooth potential with repulsive shoulder and attractive well

We report a detailed simulation study of the phase behavior of core-softened system with attractive well. Different repulsive shoulder widths and attractive well depths are considered which allows to monitor the influence of repulsive and attractive forces on the phase diagram of the system. Thermodynamic anomalies in the systems are also studied. It is shown that the diffusion anomaly is stabilized by small attraction.     

Complexation of water-soluble polymers and photosensitizer

Water-soluble polymers poly-N-methacryloyloxyethyl-N,N,N-trimethylammonium methyl sulfate and poly(methacrylic acid) are found on the basis of spectral, thermophysical, structural, and morphological studies to form stable complexes with Photodithazine photosensitizer.     

Optical Characteristics of Pyrolytic Carbon in the Vicinity of the <Emphasis Type="Italic">E</Emphasis><Subscript><Emphasis Type="Italic">1u</Emphasis></Subscript> Vibrational Mode Calculated within the Framework of the Effective-Medium Model

Spectral optical constants of pyrolytic carbon in the region of activity of the E_1u vibrational mode are calculated within the framework of the effective-medium approach in the Bruggeman approximation. It is demonstrated that the number, position, half-width, and relative intensity of the selective-absorption bands in the IR absorption spectrum of pyrolytic carbon are the independent of porosity of the original absorbing object.