Mössbauer emission spectroscopy of grain boundaries in poly- and nanocrystalline niobium

Grain boundaries in polycrystalline Nb, prepared by cold rolling with subsequent recrystallization annealing, and nanocrystalline Nb, obtained by high-pressure torsion, have been studied by ^119m Sn Mössbauer spectroscopy and the data obtained have been compared.     

Antiknock properties of furfural derivatives

Preparative amounts of furfuryl alcohol ethers and furfural acetals were prepared from renewable vegetable raw materials. The blending reseach octane numbers of mixing of furan derivatives in straight-run gasoline were estimated: butyl furfuryl ether, 97.8 ± 7; propyl furfuryl ether, 112 ± 6; furfural diethyl acetal, 105 ± 6, furfural ethylene glycol acetal, 108 ± 7; furfurylamine, 194 ± 4. These results demonstrate prospects for using furan derivatives as available biofuels.     

Generalized solutions of the kundt class for the einstein equations with the cosmological constant

Vacuum solutions of type III and N in the Kundt class are completely known (W. Kundt, Z. Phys., No. 163, 77 (1961)). In this paper, we present two classes of solutions for the case of the Einstein vacuum equations with cosmological constant Λ. Each class of solutions is characterized by the fact that the wave 2-surface is a space of constant curvature withK=6Λ andK=2Λ. Kazan State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 81–84, October, 1996.