Electronic States of Cobalt Ions in EuBaCo2O5 + δ Layered Cobaltites

JETP Letters - The oxygen K-edge X-ray absorption spectra in EuBaCo2O5.52 ± 0.02 and EuBaCo2O5.24 ± 0.02 cobaltites are measured at temperatures of 300 and 440 K, which are below and...     

Wall-crossing invariants: from quantum mechanics to knots

Journal of Experimental and Theoretical Physics - We offer a pedestrian-level review of the wall-crossing invariants. The story begins from the scattering theory in quantum mechanics where the...     

Electrophilic isomerization of substituted perfluorocyclopropanes under the effect of SbF5

Perfluoro(alkoxycyclopropanes) are isomerized on heating in the presence of SbF₅ into perfluoro(2-alkoxypropylenes), while perfluoro(alkylcyclopropanes) are isomerized into the corresponding internal fluoroolefins under the effect of SbF₅.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1844–1851, August, 1990.     

Relative stability of 1-substituted perfluoromethallyl cations according to19F NMR data

Conclusions The relative stability of perfluoromethallyl cations substituted at the 1 position decreases, depending on the substituent, in the following series: OMe > I > Br > Cl > F.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1054–1057, May, 1986.The authors wish to express their gratitude to Yu. V. Zeifman and S. A. Postovoi for providing the samples of 1-bromo- and 1-iodoperfluoroisobutylenes.     

Reactions of highly electrophilic polyfluorocarbonyl compounds with primary arylamines

C-Hydroxyalkylation of primary arylamines by highly electrophilic polyfluorocarbonyl compounds results from the direct reaction of the initial reagents and is competitively inhibited by equilibrium N-hydroxyalkylation. The presence of steric hindrances to the formation of N-hydroxyalkylation products and an increase in the ring C-nucleophilicity facilitate the C-hydroxyalkylation reaction.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 383–389, February, 1990.     

On the absence of local solutions of several evolutionary problems

We consider the existence problem for local (with respect to time) solutions of quasilinear evolutionary partial differential equations and inequalities with singular coefficients and initial conditions. We obtain sufficient conditions for instantaneous blow-up of solutions and show that the results thus obtained cannot be improved in the function class under study.     

Blow-up of solutions of some nonlinear wave equations

We analyze the problem of blow-up of global solutions of a semilinear wave equation with a potential and with a possible degeneration at infinity for nonnegative initial data with compact support. By using the nonlinear capacity method, we prove the theorem on the nonexistence of such a solution for a subcritical and the critical nonlinearity exponent.     

Erratum to: Several Articles in JETP Letters Published Online First

JETP Letters - An Erratum to this paper has been published: https://doi.org/10.1134/S0021364022330013