Simulation of the structural,electronic, and magnetic properties of Fe<Subscript>3</Subscript>C<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>B<Subscript>x</Subscript> borocementites

The structural, electronic, and magnetic properties and the enthalpy of formation of iron borocementites Fe₃C_1?x B_x (x= 0, 0.25, 0.50, 0.75, 1.00) are analyzed using ab initio calculations in the framework of the electron density functional theory. It is found that the unit cell parameter a of the orthorhombic lattice increases linearly and the parameters b and c decrease as the boron concentration increases. The density of states at the Fermi level changes only slightly, and the main variations in the band structure occur in the region of the bottom of the valence bands. The magnetic moment of the iron atoms and the total magnetization and stability of the Fe₃C_1?x B_x phases increase linearly with an increase in the boron concentration.     

The Influence of Signal Polarization on Quantum Bit Error Rate for Subcarrier Wave Quantum Key Distribution Protocol

In this paper, we consider the influence of a divergence of polarization of a quantum signal transmitted through an optical fiber channel on the quantum bit error rate of the subcarrier wave quantum key distribution protocol. Firstly, we investigate the dependence of the optical power of the signal on the modulation indices’ difference after the second phase modulation of the signal. Then we consider the Liouville equation with regard to relaxation in order to develop expressions of the dynamics of the Stokes parameters. As a result, we propose a model that describes quantum bit error rate for the subcarrier wave quantum key distribution depending on the characteristics of the optical fiber. Finally, we propose several methods for minimizing quantum bit error rate.     

New Blood Coagulation Factor XIIa Inhibitors: Molecular Modeling,Synthesis, and Experimental Confirmation

In the modern world, complications caused by disorders in the blood coagulation system are found in almost all areas of medicine. Thus, the development of new, more advanced drugs that can prevent pathological conditions without disrupting normal hemostasis is an urgent task. The blood coagulation factor XIIa is one of the most promising therapeutic targets for the development of anticoagulants based on its inhibitors. The initial stage of drug development is directly related to computational methods of searching for a lead compound. In this study, docking followed by quantum chemical calculations was used to search for noncovalent low-molecular-weight factor XIIa inhibitors in a focused library of druglike compounds. As a result of the study, four low-molecular-weight compounds were experimentally confirmed as factor XIIa inhibitors. Selectivity testing revealed that two of the identified factor XIIa inhibitors were selective over the coagulation factors Xa and XIa.     

α-Acetylene Hydrosilanes as Hydrosilylating Agents for Terminal Arylacetylenes

The hydrosilylation of a number of acetylenes RCCH (R, R' = Ph, CH₂OPh, CH₂SPh) with -ethynylhydrosilanes Me₂SiHCHCR' in the presence of H₂PtCl₆ was investigated. The addition did not occur regioselectively, but was stereospecific and afforded a mixture of - and trans--adducts. The replacement of phenyl substituent by phenoxymethyl both in the molecule of ethynylsilane and the acetylene substrate resulted in growing proportion of the -adduct in the reaction mixture up to 10-60%.     

Conformational isomerism of 1,2-diformyl-, diacetyl-, and di(trifluoroacetyl) hydrazines and their methyl analogs

Conclusion The PMR method was used to determine the conformations of the 1,2-diformyl-, diacetyl-, and di(trifluoroacetyl)hydrazines and their 1-methyl and 1,2-dimethyl analogs. The effect of the structure and the medium, on the population of the conformers was discussed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1428–1430, June, 1982.     

Dependence of the composition of the products of thermal fragmentation of thiacyanine dyes on the length of their polymethine chain

The pathways of thermal fragmentation of thiacyanine dyes with different lengths of the external polymethine chain were investigated. The results of thermolysis of the thiacyanines are compared with the results of quantum-chemical calculations of their molecules.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 188–192, February, 1982.