Crystal structure of high-manganese tinzenite from the Falotta deposit in Switzerland

The crystal structure of the natural high-manganese tinzenite of the axinite group has been refined. Using precision X-ray diffraction data, the fine details of the “isomorphous ratios” for atoms occupying the cationic positions were revealed. The final structural formula of the mineral is determined as (Mn_0.88Mg_0.03Fe_0.09)(Ca_0.925Mn_0.075) (Ca_0.495Mn_0.505)(Al_0.9Fe_0.1)(Al_0.98Fe_0.02)[BSi₄O₁₅](OH). Examination of the isomorphous ratios provided the refinement of the classification of the axinite group.     

Flow of a viscous fluid in an annular gap with intensive blowing from the walls

Self-similar solutions are obtained in [1, 2] to the Navier-Stokes equations in gaps with completely porous boundaries and with Reynolds number tending to infinity. Approximate asymptotic solutions are also known for the Navier-Stokes equations for plane and annular gaps in the neighborhood of the line of spreading of the flow [3, 4]. A number of authors [5–8] have discovered and studied the effect of increase in the stability of a laminar flow regime in channels of the type considered and a significant increase in the Reynolds number of the transition from the laminar regime to the turbulent in comparison with the flow in a pipe with impermeable walls. In the present study a numerical solution is given to the system of Navier-Stokes equations for plane and annular gaps with a single porous boundary in the neighborhood of the line of spreading of the flow on a section in which the values of the local Reynolds number definitely do not exceed the critical values [5–8]. Generalized dependences are obtained for the coefficients of friction and heat transfer on the impermeable boundary. A comparison is made between the solutions so obtained and the exact solutions to the boundary layer equations.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 21–24, January–February, 1987.     

Generation of perturbations by a localized vibrator in the boundary layer of a nonswept wing

Origination and development of perturbations generated by a threedimensional vibrating surface in the boundary layer on an airfoil with a zero slip angle is experimentally studied. Surface vibrations were generated by a Mylar membrane. It is shown that highamplitude vibrations of a threedimensional surface lead to simultaneous formation of two types of perturbations in the boundary layer: quasistationary streamwise structures and wave packets accompanying them. The presence of regions with favorable and adverse pressure gradients does not exert a significant effect on evolution of streamwise structures but leads first to attenuation and then to amplification of wave packets.     

Electrolytic palladium deposits: Dependence of adsorption properties and texture on the deposition potential

Specific features of the copper and oxygen adsorption on electrolytic palladium deposits obtained from chloride solutions at different deposition potentials are considered. It is shown that, in sulfuric acid solutions, the palladium dissolution, which accompanies the oxygen adsorption, obscures the adsorption behavior of the deposits with respect to oxygen. Assumptions are made about the predominant crystallographic orientation (100) of the surface of some palladium deposits being dependent on the deposition potential and about the presence of regions whose adsorption properties are anomalous with respect to copper. The assumptions are based on a comparative analysis of the copper adsorption data and X-ray diffraction patterns. In addition to sites of crystalline palladium, the deposits are found to have disordered areas as well. Dedicated to the ninetieth anniversary of Ya.M. Kolotyrkin’s birth.     

Reaction of N-methylpyrrolidone with 3-chlorophenyl isocyanate

Russian Journal of General Chemistry - 3-Chlorophenyl isocyanate forms molecular complex with N-methylpyrrolidone.