Heterocycles with a Bridged Nitrogen Atom. 13. An Anomalous Example of the Sulfonating Action of Dimethyl Sulfate During an Attempt at the Methylation of 5-Aminoindolizine. Crystal Structure of Methyl 5-Morpholyl-2-(p-nitrophenyl)indolizine-1-sulfonate

The reaction of 5-morpholino-2-(p-nitrophenyl)indolizine with dimethyl sulfate gives the sulfonation product - methyl 5-morpholyl-2-(p-nitrophenyl)indolizine-1-sulfonate. Its structure was proved by X-ray crystallographic analysis.     

Formation of Hydrogen-Bonding Adduct between 1-Phyenyl-2-Amino Pyrimidine and Vaniline,C17H13N3O2

The adduct compound was prepared by condensation of equimolar quantities of analar vaniline and 1-phenyl-2-amino pyrimidine in absolute ethyl alcohol. Prismatic crystals were obtained with the crystallographic data: a = 12.901 (6), b = 19.297 (9), c = 6.828 (3) Å, γ = 102.67 (2)°, V = 1657.9 ų, Z = 4, F.W. = 291.31, D_x = 1.17 g/cm³, space group P2/n, R = 0.038 and R_w = 0.036. The intensity data were collected on an Enraf Nonius CAD-4 computer controlled diffractometer using MoKα radiation. The structure was solved by direct method and refined by full matrix least-squares using anisotropic temperature factor of all atoms, except for hydrogen ones, which were treated isotropically. A full discussion was given to explain: a) the occurrence of the condensation process between the OH-group of vaniline and the heterocyclic N-atom in position 5 of the pyrimidine cycle and b) why this condensation does not take place between the amino-group of the pyrimidine compound and the aldehydic group of vaniline to give a Schiff base.     

Crystal structure and properties of [OsO<Subscript>2</Subscript>(NH<Subscript>3</Subscript>)<Subscript>4</Subscript>]SO<Subscript>4</Subscript> · H<Subscript>2</Subscript>O

The structure of a single crystal of tetraammindioxoosmium(VI) sulfate [OsO₂(NH₃)₄]SO₄ · H₂O, which is synthesized by the reaction of K₂[OsO₂(OH)₄] with (NH₄)₂SO₄ in an aqueous solution, is investigated using X-ray diffraction analysis. The compound crystallizes in the monoclinic crystal system, space group P2₁/c, a = 13.102(2) Å, b = 6.158(3) Å, c = 11.866(2) Å, β = 98.13(2)°, and Z = 4. The [OsO₂(NH₃)₄]SO₄ · H₂O compound has an island structure. Two crystallographically independent osmium atoms are situated at the centers of symmetry, and their octahedral coordination includes two oxygen atoms and four nitrogen atoms of the ammonia molecules. In both octahedra, the osmyl group is linear. The Os-O distances in the octahedra are identical within the standard deviations [Os(1)-O, 1.762(2) Å; Os(2)-O, 1.769(2) Å]. The Os-N bond lengths vary from 2.082(3) to 2.101(3) Å. The cationic complexes, SO₄ groups, and water molecules are linked via the system of hydrogen bonds. The assignment of the absorption bands in the IR spectrum of the compound synthesized is performed, and its thermal behavior in air is studied.     

Construction of an Explicit Basis for Rules Admissible in Modal System S4

We find an explicit basis for all admissible rules of the modal logic S4. Our basis consists of an infinite sequence of rules which have compact and simple, readable form and depend on increasing set of variables. This gives a basis for all quasi‐identities valid in the free modal algebra ℱ_S4(ω) of countable rank.     

Crystal Structure of 1-(2-Pyridylmethyl)-2,4,6-Triphenyl-Pyridinium Perchlorate

The crystals of 1-(2-pyridymethyl)-2,4,6-triphenylpyridinium perchlorate are monoclinic, space group P 2₁/b. The unit cell parameters are a = 18.941(5), b = 19.502(6), c = 15.135(5),y = 115.99°(2), Z = 8, d₀ = 1.31(3), d_x = 1.319 g/cm³. The structure has been determined by direct methods and refined by block diagonal least squares to R₀ = 0.08 for 2520 reflections. The phenyl rings in both molecules (I) and (II) are planar. These rings are twisted with respect to the central pyridyl rings.     

High-Rate Microwave Sintering of Ceramics on the Basis of Barium and Strontium Titanates

Radiophysics and Quantum Electronics - Using the method of sintering by microwave heating at a rate of 10–100°C/min to a temperature of 1250 °C without isothermal hold, we obtain...     

A Family of K3 Surfaces and Towers of Algebraic Curves over Finite Fields

Mathematical Notes -     

The Influence of Submicron Particles of Coal Concentrate on the Conditions of Aerosol Synthesis of Carbon Nanotubes

Russian Physics Journal -     

Cosmic chiral vortices

The review is devoted to cosmic chiral vortices (strings) and their possible role in the evolution of the early Universe. An exact cylindrically-symmetric solution to Einstein equations was obtained within the SU(2) sigma model for a configuration with a topological charge of the degree type. The linearized stability of the solution with respect to radial perturbations is proven by Lyapunov’s direct method. The metric found corresponds to the conical type with an angular deficiency proportional to the topological charge or the linear mass density of the vortex. The ray deflection angle close to the angular deficiency (the gravitational lens effect) was determined by direct integration of geodesic equations for the light ray orthogonal to the vortex. A gauge generalization of the model was considered involving the axially symmetric Yang-Mills field. In the approximation of the large topological charge, a solution with proper longitudinal magnetic field was obtained and the effect of a decrease in the vortex energy was found. The effect of closing the string was also considered in the approximation of the large closure radius. To this end, the toroidal moment of a closed string was calculated and an energy correction caused by the Skyrme term.     

Explosion-type chain fracture reaction during the formation of a complete spall damage zone

Some aspects of the available experimental results on the spall fracture of steel and duralumin sample caused by the explosion of a sheet HE charge are discussed. In particular, the location of the damage zone is considered based on the condition that the density of deformation energy is larger than the density of energy of formation new surfaces upon continuity break. The localization of the complete damage zone is determined by the threshold values the induction time and tensile stress. No dynamic branch of longevity associated with spall fractures is observed at times shorter than 10⁻⁷ s.