The Brauer group of a noncomplete real algebraic surface

The Brauer group of a noncomplete real algebraic surface is calculated. The calculations make use of equivariant cohomology. The resulting formula is similar to the formula for a complete surface, but the proof is substantially different. Translated fromMatematicheskie Zametki, Vol. 67, No. 3, pp. 355–359, March, 2000.     

Picard and Lefschetz numbers of real algebraic surfaces

Two Picard numbers and two Lefschetz numbers are defined for a real algebraic surface. They are similar to the Picard number and the Lefschetz number of a complex algebraic surface. For these numbers, some estimates and relations in the form of inequalities are proved.Translated fromMatematicheskie Zametki, Vol. 63, No. 6, pp. 847–852, June, 1998.     

Study of the inf luence of the alkyl ester group in (S)-valinates on diastereoselectivity of their condensation with N-acetylphenylalanine by the mixed anhydride method

The dynamic kinetic resolution in the synthesis of alkyl N-acetylphenylalanyl (S)-valinates was studied by the mixed anhydride method. The structure of the ester group of the amino component appeared to exert no substantial effect on the diastereoselectivity of the reaction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 892–894, May, 2006.     

Synthesis of stereoisomers of 2,4-diaminoglutaric and 2,5-diaminoadipic acids

Stereoisomers of 2,4-diaminoglutaric and 2,5-diaminoadipic acids were synthesized from glutamic and 2-aminoadipic acids, respectively. The stereochemistry of the products was established by¹H NMR spectroscopy and X-ray analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 333–337, February, 1997.     

On theta characteristics of real algebraic curves

Real theta characteristics of a real algebraic curve are studied. The numbers of even and odd real theta characteristics are calculated. These numbers depend on the topological characteristics of the curve only.     

Multiplicities in84Kr interactions in emulsion at 800–950 MeV/nucleon

Inelastic interactions induced by⁸⁴Kr nuclei at 800–950 MeV/nucleon have been studied using a high angular resolution emulsion detector. Data on multiplicities of the produced particles, projectile and target fragments are shown. Comparisons with cascade calculations have been performed.We thank to Swedish Research Council for Natural Sciences for the financial support. Scanning and measurements performed by E.G. Broomé and V. Kopljar are acknowledged.     

Charge transport in proximity-effect SNcNS constrictions

Josephson and quasiparticle currents in SNcNS contacts are calculated for the regimes of ballistic constriction “c”. The relation between the current and electronic densities of states in NS proximity bilayer is found. The effect of the proximity N layer on the Andreev and normal reflections of electrons at the constriction is studied. Excess current at large voltages and subharmonic structure at low bias are analyzed as a function of material parameters of N and S and transparency of the NS interface. The appearance of new series of subharmonic peaks due to two-gap structure in the density of states of proximity NS electrodes is demonstrated. The relation between excess and critical currents is analyzed. The model is relevant for SNS junctions of constricted geometry which is realized in S-2DEG-S and step-edge highT _c SNS contacts.     

Interaction of Cyclic Schiff's Bases with 2-Methylthiopyrimidine-4,6-dione Enol Acetate. Synthesis of 5-(2-Acetyl-6,7-dimethoxy-1,2,3,4-tetrahydro-1-isoquinolyl)-6-hydroxy-2-methylthio-1,4-dihydro-4-pyrimidinones

5-(2-Acetyl-1,2,3,4-tetrahydro-1-isoquinolyl)-6-hydroxy-2-methylthio-1,4-dihydro-4-pyrimidinones have been obtained by the interaction of 3,4-dihydroisoquinolines with 2-methylthio-4-oxo-1,4-dihydro-6-pyrimidinyl acetate. It was shown that N,O-methyl derivatives are formed in interaction of the obtained products with diazomethane.