Macromolecular metal complexes with transition-metal ions: Structure of a polymer and efficiency of complexation

A quantitative method of estimating the efficiency of formation of macromolecular metal complexes of carboxyl-containing (co)polymers with transition-metal ions in dilute solutions was developed. This method is based on the luminescence quenching of luminescently labeled macromolecules by transition-metal ions. With the use of this method, the effect of the chemical (including isomeric) structure of carboxyl-containing (co)polymers and external conditions on the stability of macromolecular metal complexes based on copper, nickel, and silver ions was assessed. With consideration for the data obtained, a targeted variation in the functional characteristics of macromolecular metal complexes may be accomplished.     

Hole-electron mechanism of F-H pair generation in RbCl crystals with impurity electron traps

Production of F, Cl ₃ ⁻ , Ag⁰, and Tl⁰ centers in RbCl:Ag and RbCl:Tl crystals by photons having energies ranging from 5 to 10 eV has been studied at 295 and 180 K. It is shown that creation of near-impurity excitations is accompanied by formation of F centers localized in the vicinity of Ag⁺ and Tl⁺ ions. F centers are produced in direct optical generation of self-trapped excitons. In addition to the well-known mechanism of F-H pair production in nonradiative recombination of electrons with self-trapped holes, a hole-electron process has been revealed for the first time to operate in RbCl:Ag having deep electron traps. By this mechanism, F-H pairs appear in the following sequence of stages: thermally stimulated unfreezing of hopping diffusion of self-trapped holes (V _K centers), tunneling electron transfer from Ag⁰ to the approaching V _K centers, and subsequent nonradiative decay of triplet self-trapped excitons near Ag⁺ ions. Fiz. Tverd. Tela (St. Petersburg) 40, 1238–1245 (July 1998)     

Tangential Slot Gas Film Cooling. Comparison of Calculation and Experiment

A method of calculating of the boundary layer in liquid rocket engine (LRE) nozzles, developed by the authors and based on a differential three-parameter turbulence model, is tested using the known experimental data for the boundary layer on a plate in zero-pressure-gradient flow with tangential gas injection. Over a wide range of both bulk flow and injected gas parameters and for variable slot geometry, the calculations for both integral and local flow and heat transfer characteristics satisfactorily agree with experiment. The study has made it possible to obtain the governing parameters which significantly affect the gas film effectiveness.     

Thermal convection in a cylindrical enclosure with intense internal heat generation in the presence of a longitudinal magnetic field

Steady convection in a gaseous medium with intense heat generation is considered without making use of the Boussinesq approximation. The effect on convection of the thermal boundary conditions at the walls of the enclosure is investigated, together with the influence of a longitudinal magnetic field which is effective when the medium is strongly heated and becomes electrically conducting.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.3, pp. 11–18, May–June, 1992.The authors are grateful to the participants in the G. A. Lyubimov seminar for discussing their work.     

Mixing of wakes in a longitudinal magnetic field

The results of measuring the velocity profiles in the initial section of mixing of turbulent wakes of an electrically conducting fluid in a longitudinal magnetic field are presented. It is shown that the magnetic field has a substantial effect on the jet; it narrows the width of the mixing zone and increases the length of the initial section in comparison with the case of the absence of a magnetic field. The results obtained indicate that the velocity profiles in the mixing layer during flow in a longitudinal magnetic field are self-preserving. The function taking into account the effect of the magnetic field in the expression for eddy stresses is determined on the basis of the experimental data. The width of the mixing zone during flow of wakes in the initial section in a longitudinal magnetic field was calculated with the use of the dependence obtained for . The calculation results are compared with experimental data.Moscow. Translated from Izvestiya Akademii Nauk SSSR. Mekhanika Zhidkosti i Gaza, No. 5, pp. 33–44, September–October, 1972.     

Supersonic boundary layer on a plate. Comparison of calculation and experiment

For verifying the method of calculating the boundary layer in liquid rocket engine (LRE) nozzles developed by the authors on the basis of a differential three-parameter turbulence model, the boundary layer on a plate in a zero-gradient flow is calculated. Over a wide range of variation of the free-stream Mach number, the temperature factor, and the Reynolds number, based on the momentum thickness of the boundary layer, the calculation agrees satisfactorily with the known experimental data, with respect to both integral and local flow and heat transfer characteristics. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 6, pp. 64–78, November–December, 1998. The work received financial support from the Russian Foundation for Basic Research (project No.96-012-00260).     

Fast Intrinsic Emissions of Wide-Gap Oxides Under Electron Irradiation

The emission spectra have been measured in the range of 1.6–9.0eV under irradiation of wide-gap oxides by single electron pulses (3 ns, 300kV). A fast (τ < 3 ns) continuous and temperature-independent emission, connected mainly with the transitions of hot holes between the levels of the valence band of oxides, can be separated in these spectra at 300–600 K, when the inertial emissions (5–7eV) of localized excitations undergo a strong thermal quenching. It is suggested that a drastic decrease of the intensity of this so-called hole intraband luminescence (IBL) in a short-wavelength spectral region is caused by the lowering of the density of states at the edges of the valence band and, therefore, supplies information on the width of an anion valence band E^v. The drastic decrease of the IBL intensity takes place at 6.4–8.6eV in BaMgAl₁₀O₁₇, SrAl₂O₄, MgAl₄O₇, MgO and BeO, that agrees satisfactorily with the values of E^v in these systems obtained by other methods.     

Tangential Slot Film Cooling in a Nozzle. Comparison of Calculation and Experiment

To test a method of calculating the boundary layer in liquid rocket engine (LRE) nozzles, developed by the authors and based on a differential three-parameter model of turbulence, nozzle flow with tangential-slot coolant injection in subsonic part of the nozzle is studied numerically. The effect of nozzle flow acceleration on the turbulence parameters and the dependence of the gas film effectiveness on the nozzle-inlet turbulence intensity are investigated. The numerical results are compared with available experimental data.