Propagation of magnetoelastic shear waves across layers in a periodically layered medium

The paper is concerned with magnetoelastic shear waves propagating in regularly layered magnetostrictive media at a right angle to the layer interfaces __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 6, pp. 54–60, June 2006.     

Enthalpies of formation of radicals and the mass spectra of the products of tetrafluoroethylene polymerization in acetone

The mass spectra of the dissociative electron-impact ionization products of telomers formed upon the radiation-chemical telomerization of tetrafluoroethylene in acetone were measured over the range of m/z from 1 to 204. The most intense bands at m/z = 43, 51, and 57 were attributed to the CH₃CO⁺, CF₂H⁺ and CH₃COCH₂⁺ cations—the main dissociation products of the H(C₂F₄) _n CH₂COCH₃ telomers. The telomer composition was consistent with a radical telomerization mechanism, in which chain growth and chain transfer are due to the formation of the CH₃COCH₂^· radical. Based on published data supplemented with quantum-chemical calculations, the enthalpies of formation of the radicals R(CF₂) _n (n = 2–8; R = H, CH₃, CH₃CO, and CH₃COCH₂) were tabulated. The formation of telomers with the same terminal groups is consistent with thermodynamic data and a polymerization mechanism in which the chain growth reaction is diffusion-limited and the chain transfer reaction is activated hydrogen-atom transfer.     

Crystal structure and magnetic properties of Ce7Ni5±xGe3±xIn6 and Pr7Ni5±xGe3±xIn6

The indides Ce₇Ni_5±xGe_3±xIn₆ and Pr₇Ni_5±xGe_3±xIn₆ were synthesized from the elements by arc-melting of the components. Single crystals were grown via special annealing sequences. Both structures were solved from X-ray single crystal diffraction data: new structure type, P6/m, Z=1, a=11.385(2), c=4.212(1) Å, wR₂=0.0640, 634F² values, 25 variables for Ce₇Ni_4.73Ge_3.27In₆ and a=11.355(6), c=4.183(2) Å, wR₂=0.0539, 563F² values, 25 variables for Pr₇Ni_4.96Ge_3.04In₆. Both indides show homogeneity ranges through Ni/Ge mixing (M sites). This new structure type can be derived from the AlB₂ structure type by a substitution of the Al and B atoms by CeM₁₂ and NiIn₆Ce₃ polyhedra (tricapped trigonal prism). Magnetic susceptibility measurements on a polycrystalline sample of Ce₇Ni₅Ge₃In₆ indicated Curie-Weiss like paramagnetic behavior down to 1.71 K with the effective magnetic moment slightly reduced in relation to the value expected for trivalent cerium ions. No magnetic ordering is evident.     

Dynamical chaos and stochastic mechanism of high-energy negatively charged particle deflection by bent crystals

Deflection of high-energy negatively charged particles in straight and bent crystals through multiple scattering by crystal atomic strings was considered for the case in which the initial angle between the particle momentum and one of the main crystallographic axes was approximately four critical angles of axial channeling. It was shown that in a bent crystal with a small crystal thickness, when the crystal bend was less than the beam incidence angle, the beam deflected in the direction opposite to the direction of the crystal bend. At larger crystal thicknesses, the large part of the beam starts to deflect in the direction of the crystal bend. In addition, there is a group of particles that follow the crystal axis bend in the angular region of approximately the critical angle of axial channeling with respect to the current direction of the crystal axis. It was shown that in all of these deflection processes, the periodicity of the location of atomic strings in the crystal does not influence the angular distributions of scattered particles. This fact is connected with the effect of dynamical chaos in particle motion in the periodical field of bent crystal atomic strings. It was also shown that observed in a recent CERN experiment effect of beam deflection, when the angle between the initial particle momentum and the crystal axis was approximately four critical angles of axial channeling, is due to peculiarities of the stochastic multiple scattering of particles by bent crystal atomic strings. These peculiarities are connected with the effect of dynamical chaos in particle motion in crystals.     

Oxidation of 6-methyl-2,4-dioxypyrimidine with selenious acid

The yield orotic aldehyde at the oxidation of 6-methyl-2,4-dihydroxypyrimidine was found to increase when selenious acid is used as an oxidizer. A comparative analysis of 6-methyl-2,4-dioxypyrimidine oxidation with selenium dioxide and selenious acid was performed using the ab initio quantum chemical method in the 6-31G** basis.     

Diels-alder reactions with cyclic sulfones: X. Synthesis of 4-carbamoyl- and 4-hydrazido-substituted hexahydro-1-benzothiophene S,S-dioxides

Reactions of spiro[1-benzothiophene-4,5′-[1,3]dioxane]-4′,6′-diones with various amines led to the formation of 4-carbamoylhexahydrobenzo[b]thiophene-4-carboxylic acid 1,1-dioxides or their decarboxylation products, depending on the conditions. Hydrazinolysis of the spiro adducts in DMF gave the corresponding monohydrazides. The structure of 4-carbamoyl-7-methyl-5-phenyl-2,3,3a,4,5,6-hexahydro-1-benzothiophene-4-carboxylic acid 1,1-dioxide was proved by X-ray analysis.     

Coherent effect in the radiation of relativistic electrons in the field of bent atomic crystallographic planes

The effect of the intense monochromatic radiation arising when relativistic electrons intersect periodically bent atomic crystallographic planes in a crystal is predicted. This effect is independent of the channeling of the particles in the crystal and is possible for relativistic positrons and electrons.     

On shapes of body waves in periodically inhomogeneous, magnetostrictive, dielectric materials

The shapes of shear body waves in periodically inhomogeneous, magnetostrictive, dielectric media are studied with emphasis on the partial (elastic and magnetostrictive) wave motions coupled to produce magnetoelastic waves __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 7, pp. 57–63, July 2006.