Key structures in the synthesis of steroid antitumor agents. Methods for upbuilding the 17β-pregnane side chain of 3-methoxy-19-norpregna-1,3,5(10)-trien-20-ones with and without an additional 16α,17α-carbocycle

Russian Chemical Bulletin - Methods for extending the side chain of 20-oxopregnanes were summarized. The possibilities of alkylation of 3-methoxy-19-norpregna-1,3,5(10)-trien-20-one and its...     

Magnetic Moments,Electronic Structure,and Optical Spectroscopy of Cobalt-Based Intermetallic Compounds YCo3, Y2Co7, and LaCo5

Journal of Experimental and Theoretical Physics - We report on the results of analysis of magnetic properties and electronic structure, which were obtained by self-consistent ab initio...     

Oscillatory processes at phase boundaries in zone refining with a temperature gradient in a stationary temperature field

A study is made of the effect of the threshold of kinetic processes on the character of motion of the phase boundaries in a crystal-melt. Numerical results are presented and an analysis made of the conditions under which oscillations arise in the rate of growth of epitaxial layers.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 68–72, March, 1995.     

A method for solving nonlinear equations

A direct method for solving constant coefficient nonlinear evolutional problems of mathematical physics extending the Hirota method to the case of degeneracy of k-parameter is described. An application of this method to the problem of finding the solutions describing coupled states in φ⁴-theory with damping is considered.     

Thermochemistry of AII(VUO6)2 · nH2O Compounds (AII = Mn, Fe, Co, Ni, Cu, Zn, Cd)

Standard enthalpies of formation of uranovanadates of 3(4)d transition metals at 298.15 K were determined. The isobaric heat capacity of Co(VUO₆)₂ · 4H₂O was measured. The standard Gibbs functions of formation of the compounds were calculated on the basis of these data using approximate methods of absolute entropy calculation. The thermochemical characteristics of the synthesis and dehydration of uranovanadates were considered.     

Reaction of hexylsilane with N-substituted allylamine and allyl chloride

Reactions of allyldiethylamine and allylbis(trimethylsiyl)amine with hexylsilane are studied. The former reaction involves hydrogen evolution and Si-Si bond formation. The contribution of hydrosilylation is insignificant. Substituent exchange between the nitrogen and silicon atoms in the silane is found. In the reaction with allylbis(trimethylsilyl)amine, no evolution of hydrogen is observed, and hydrosilylation takes place. With allyl chloride, hydrosylilation, reduction, and Si-Si bond formation are observed. Quantumchemical calculations for the reactions with diethylallylamine and allylbis(trimethylsilyl)amine were carried out at the PM3, B3LYP/6-31G**, and B3LYP/LanL2DZ levels to show that these reactions all are thermodynamically allowed, and the difference in the behavior of the amines is explained by kinetic and conformational factors.     

Modifying the Structure of Multiwalled Carbon Nanotubes with Continuous and Pulsed Ion Beams

Physics of the Solid State - Changes in the local atomic and electronic structure and the chemical state of the surface of multiwalled carbon nanotubes (MWCNTs) irradiated with continuous and...     

Dynamics of the Surface Morphology of a Tungsten Foil under Load

Physics of the Solid State - The dynamics of changes in the surface morphology of recrystallized tungsten foil under the action of uniaxial tension was studied in situ by the methods of low-energy...     

Isomorphism and phase diagram of the Pb5(PO4)3Cl-Pb5(VO4)3Cl system

Compounds of composition Pb₅(P _x V_1−x O₄)₃Cl (0 ≤ x ≤ 1), which are synthetic analogues of minerals pyromorphite, vanadinite, and endlichite, were synthesized for the first time by high-temperature solid-phase reactions. X-ray diffraction and IR spectroscopy were used to determine the structure of the compounds and revealed complete miscibility in the solid phase of the Pb₅(PO₄)₃Cl-Pb₅(VO₄)₃Cl binary system. Adiabatic reaction calorimetry was used to determine standard enthalpies of mixing and formation and showed that the regular solutions model is applicable to the Pb₅(PO₄)₃Cl-Pb₅(VO₄)₃Cl system. Differential thermal analysis in tandem with high-temperature X-ray diffraction was used to study the phase diagram and characterize phase transitions.