Nucleophile-induced transformations of 1,2,4-triazines. 3. Anrorc constriction of the ring in the reaction of 6-aryl-3-dimethylamino-1,2,4-triazine 4-oxides with KCN

Reaction of 6-aryl-3-dimethylamino-1,2,4-triazine 4-oxides with KCN results in constriction of the heterocycle and formation of 3-amino-5-aryl-4-nitrosopyrazoles. Several methods including labelled K¹³C¹⁵N are used to demonstrate that the reaction proceeds through the ANRORC mechanism. Dedicated to Professor Henk van der Plas on his 70th birthday. For No. 2, see [1]. Urals State Technical University, Ekaterinburg 620002, Russia; e-mail: mike@htf.ustu.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 532–535, April, 1999.     

The effect of parametrically excited spin waves on the dispersion and damping of magnetostatic surface waves in ferrite films

This paper describes an experimental study of variations of the dispersion and damping of magnetostatic surface waves in ferrite films, caused by three-and four-magnon interactions with parametric spin waves excited by an auxiliary surface magnetostatic pump wave with frequency f _p. The variations in the dispersion and damping were identified, respectively, with variations Δk″ in the real part and Δk′ in the imaginary part of the wave number of the surface magnetostatic wave. The Δk″ and Δk′ values were determined from the ratio of the changes of the phase increment Δφ and the amplitude increment ΔA of the surface magnetostatic wave to the length L of the nonequilibrium section of the film, where the parametric spin waves exist. It is found that, when three-magnon decay processes are allowed for the pump wave and the surface magnetostatic probe wave, the probe wave can substantially alter the distribution of the parametric spin waves in the film. Zh. éksp. Teor. Fiz. 115, 318–332 (January 1999)     

Barkhausen effect in stepped motion of a plane domain boundary in gadolinium molybdate

Barkhausen pulses generated in stepped motion of a single plane domain boundary (PDB) are investigated experimentally in single-crystalline wafers of the extrinsic ferroelastic ferroelectric gadolinium molybdate containing artificial pinning centers of the “field inhomogeneity” type near the edges of the sample. Two scenarios of the evolution of a PDB in interaction with “defects” are proposed on the basis of analyzing the shape of the pulses in a linearly increasing field: small changes of the pulse shape in a weak field and the generation of wedge domains in a strong field. The proposed mechanism of PDB motion due to the generation of steps near the edge of the sample and their longitudinal motion provides a means for explaining the experimentally observed linear field dependence of the PDB velocity and for determining the velocity of the steps. Fiz. Tverd. Tela (St. Petersburg) 41, 301–305 (February 1999)     

Event horizon as alternative to cosmological singularity

The general relativistic equations for a homogeneous istoropic metric of the most general form are considered. It is concluded that an event horizon is a possible alternative to a cosmological singularity for “usual” matter. This conclusion is illustrated by the case of a flat spatial universe.     

The special features of phase equilibria in α-pinene-water binary mixtures in the sub- and supercritical states

Phase equilibria in α-pinene-water binary mixtures under sub-and supercritical conditions were studied by thermodynamic modeling. The compositions and boiling points of three-phase heteroazeotropic mixtures were calculated as functions of pressure. The T and p regions of the existence of liquid-liquid and vapor-liquid two-phase mixtures were determined. The T _cmix and p _cmix critical curve coordinates depending on mixture composition were found. The T _cmix curve exhibited an anomaly in the form of a minimum. The T _Az-p _Az heteroazeotropic line ended at the minimum point of the critical curve.     

Study of the whispering gallery effect on a spherical surface in the hard X-ray region

The whispering gallery effect in the hard X-ray region (0.15–0.3 nm) has been theoretically and experimentally investigated using a concave spherical mirror with a 25-cm radius of curvature and a diameter of 6 cm. A spherical mirror finds and captures the rays incident on its surface in the whispering gallery mode; there is no need to perform an exact alignment of the mirror with respect to the incident X-ray beam in order to observe the effect. To analyze the experimental data, we used the ray tracing method. It is shown that the results of the experiment and computer simulation are in good agreement.     

Vilsmeier Formylation of Hydrazones and Semicarbazones Derived from Alkyl, Benzyl, and Cycloalkyl Methyl Ketones

Formylation of ten accessible phenylhydrazones and semicarbazones derived from alkyl, benzyl, and cycloalkyl methyl ketones with the complex of POCl₃ with dimethylformamide was studied. Depending on the electronic and steric structure of the substrates, the reaction yields 1-phenyl- or 1-unsubstituted 3,4-dialkyl-, 3-alkyl-4-aryl-, or 3-alkyl-4-formylpyrazoles. These compounds can be readily oxidized into the corresponding carboxylic acids.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 3, 2005, pp. 448–452.Original Russian Text Copyright © 2005 by Lebedev, Lebedeva, Sheludyakov, Kovaleva, Ustinova, Kozhevnikov.     

Search for Θ+(1540) in exclusive proton-induced reaction p + C(N) \to \Theta ^ + \bar \kappa ^0 + C(N) at the energy of 70 GeV

A search for narrow Θ⁺(1540), a candidate for a pentaquark baryon with positive strangeness, has been performed in an exclusive proton-induced reaction $p + C(N) \to \Theta ^ + \bar \kappa ^0 + C(N)$ on carbon nuclei or quasifree nucleons at $E_{beam} = 70GeV(\sqrt s = 11.5GeV)$ studying nK ⁺, pK _S ⁰ , and pK _L ⁰ decay channels of Θ⁺(1540) in four different final states of the $\Theta ^ + \bar K^0 $ system. In order to assess the quality of the identification of the final states with neutron or K _L ⁰ , we reconstructed Λ(1520) → nK _S ⁰ and ? → K _L ⁰ K _S ⁰ decays in the calibration reactions p + C(N) → Λ (1520)K ⁺+C(N) and p+C(N) → p?+C(N). We found no evidence for a narrow pentaquark peak in any of the studied final states and decay channels. Assuming that the production characteristics of the $\Theta ^ + \bar K^0 $ system are not drastically different from those of the Λ(1520)K ⁺ and p? systems, we established upper limits on the cross-section ratios $\sigma (\Theta ^ + \bar K^0 )/\sigma (\Lambda (1520)K^ + ) < 0.02$ and $\sigma (\Theta ^ + \bar K^0 )/\sigma (p\phi ) < 0.15$ at 90% C.L. and a preliminary upper limit for the forward-hemisphere cross section $\sigma (\Theta ^ + \bar K^0 )$ nb/nucleon.     

An anomalous -ω interference in the reaction ee → 3π

It is shown that in the π⁺π⁻ meson mass-spectrum in the reaction e⁺e⁻ → π⁺π⁻π⁰ at 2E > 1 GeV one should expect the anomalously large effect of the -ω interference. It can be used as a tool for the elucidation of the details of the e⁺e⁻ → Vπ reaction dynamics and as the additional possibility for the determination of the electromagnetic -ω mixing parameters.