Kinetic isotope effect during acid hydrogen exchange in σ-benzyl-π-cyclopentadienyliron dicarbonyl

Conclusions The kinetic isotope effect K_D/K_T was measured during acid hydrogen exchange in -C₅H₅-(CO)₂Fe--CH₂C₆H₅. The obtained K_D/K_T value testifies in support of the generality of the mechanisms of hydrogen exchange in the benzene ring of this complex and in other derivatives of the benzene series.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 221–222, January, 1979.     

Capabilities to improve corrosion resistance of fuel claddings by using powerful laser and plasma sources

The treatment conditions of fuel claddings of the E110 alloy by using powerful UV or IR laser radiation, which lead to the increase in the corrosion resistance at the high-temperature (T = 1100°C) oxidation simulating a loss-of-coolant accident, are determined. The possibility of the complete suppression of corrosion under these conditions by using pulsed laser deposition of a Cr layer is demonstrated. The behavior of protective coatings of Al, Al₂O₃, and Cr planted on steel EP823 by pulsed laser deposition, which is planned to be used in the BREST-OD-300, is studied. The methods of the almost complete suppression of corrosion in liquid lead to the temperature of 720°C are shown.     

Effect of the chemical structure of the polymer matrix on the properties of foam polyurethanes at low temperatures

The dependence of physical and mechanical properties of oligoether-based foam polyurethanes on the molecular mass (M_c) of polymer chains between the nodes of the polymer network and on the content of rigid segments in the polymer is investigated at 293 and 98K. The values of M_c at which the foam plastics have the best mechanical properties at low temperatures are determined. The content of rigid segments in the polymer at which foam polyurethanes have the best combination of the linear thermal expansion coefficient and mechanical properties in tension at a temperature of 98K is found.Latvian State Institute of Wood Chemistry, Riga, LV-1006, Latvia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 4, pp. 517–526, July–August, 1999.     

Investigation of convection in a horizontal cylindrical layer of a saturated porous medium

The structures of the convective motions and the nature of the heat transfer in a horizontal cylindrical layer are studied numerically for the Forchheimer model of a porous medium in the Boussinesq approximation. New asymmetric solutions of the equations of convection flow through a porous medium are found. Their development, domains of existence, and stability are investigated. One consists of a multivortex structure with asymmetric vortices in the near-polar region. Another asymmetric solution is realized at large Grashof numbers in the form of a convective plume deflected from the vertical. The threshold Grashof number of formation of the asymmetric motions depends on the Prandtl number and the cylindrical layer thickness.     

Reactivity of benzenetricarbonylchromium derivatives under conditions of dissociative ionization in the gas phase

The reactivity of benzenetricarbonylchromium derivatives under conditions of their fragmentation by electron impact was studied. The generalized structural and mass spectral characteristics formed on the basis of the information theory, molecular graph theory, and theory of absolute reaction rates were used to establish correlations between some of these characteristics.     

Instability of the motion of a liquid between two rotating spherical surfaces

A study has been made of the stability of the steady-state motion of a viscous incompressible liquid, arising in a thin spherical layer, when both spheres are rotating in the same direction at different angular velocities. For a ratio of the radii of the spheres r₂/r₁=1.10, 1.07, a stability curve is obtained which is analogous to the stability curve for the motion of a liquid between rotating cylinders.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 155–156, July–August, 1970.     

Analysis of methods of determining the interlaminar shear strength of composite materials

Conclusions The range of geometrical dimensions of a sample in which the values of the interlaminar shear strength determined by four of the five methods discussed are practically constant has been established. Good agreement is shown in the values of the characteristic being determined which are obtained by each of the four methods. It has been established that the experimental data obtained by the method of three-point deflection of short beams does not characterize their interlaminar shear strength. It is shown that the interlaminar shear strength of glass-plastic and the shear strength of the adhesive with which it is prepared are very similar in value.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 640–648, July–August, 1976.