Oxygen nonstoichiometry and the thermodynamic and structural properties of double perovskites PrBaCo2 ? xCuxO5 + δ

The special features of the structure, electrophysical properties, and oxygen nonstoichiometry of new double perovskites PrBaCo_{2 − x} Cu _x O_{5 + δ} were studied. Within the homogeneity region with respect to copper 0 < x ≤ 1, solid solution samples had an orthorhombic structure (space group Pmmm) with the parameters a _p × 2a _p × 2a _p , where a _p ≈ 3.8 ?. The oxygen nonstoichiometry of PrBaCo_{2 − x} Cu _x O_{5 + δ} changes as the copper content increases approximately as δ ≈ 0.85 − x/2. The content of oxygen was measured by coulometric titration over wide temperature and oxygen pressure ranges. The partial thermodynamic functions of labile oxygen were calculated and the limits of the thermodynamic stability of the solid solution were established. Original Russian Text ? A.Yu. Suntsov, I.A. Leonidov, A.A. Markov, M.V. Patrakeev, Ya.N. Blinovskov, V.L. Kozhevnikov, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 5, pp. 954–960.     

Channeling of Neutrons in the Potential Well of a Planar Waveguide

The channeling of neutrons in a three-layer planar waveguide with a neutron-optical potential well is studied. Neutrons incident on a sample surface, which propagate in a middle layer and escape from the waveguide end in the form of a narrow divergent beam, are detected. The decay parameter of a neutron wave inside the waveguide is measured as a function of the potential well depth. Experimental results are compared with a theory.     

Methods for Probing Magnetic Films with Neutrons

We review various methods in the investigation of magnetic films with neutrons, including those based on the effects of Larmor precession, Zeeman spatial splitting of the beam, neutron spin resonance, and polarized neutron channeling. The underlying principles, examples of the investigated systems, specific features, applications, and perspectives of these methods are discussed.     

Investigations of Nonconventional Cross Sections of Gas-Discharge Lasers

Russian Physics Journal - Gains of lasers with regular polygon cross sections of tubes having curvilinear sections are considered. Calculations are performed for parabolic polygons, a triangle, and...     

KINETICS OF DYNAMIC HOLOGRAM RECORDING IN POLYMER FILMS WITH IMMOBILIZED BACTERIORHODOPSIN

Abstract
Polymer films with immobilized photosensitive membrane protein, bacteriorhodopsin (BR), were prepared and investigated. A sensitive holographic interferometer with phase modulated optical beams was used for investigation of kinetics of dynamic hologram recording in BR polymer films. It was found that phase hologram formation consisted of two quasi-exponential stages demonstrating existence of a diffusive process in obtained films. It was shown that the kinetics of a phase hologram recording by high intensity beams do not correlate with the exponential law. The applicability of BR polymer films as reversible photorefractive materials for dynamic holography and real-time interferometry was discussed.     

Kinetics of electron transfer between VIV and VV in heteropolyanions

Conclusions A study has been made of the kinetics and equilibrium of the reaction of electron transfer between V^IV and V^V in 12-series heteropolyanions and in the reaction of dissociation of V^IV from the HPA.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp, 2469–2472, November, 1984The authors wish to express their appreciation to V. N. Parmon for valuable comments.     

Study of the OZI selection rule in hadronic processes

In the experiments with LEPTON-F and SPHINX spectrometers the pion-induced charged exchange reactions π- + p → ? + n and π- + p → ω + n at Pπ-=32.5 GeV, as well as proton-induced diffractive reactions p + N → [p?] + N and p + N → [pω] + N at E _p =70 GeV were studied. The comparison of the cross-sections for ? and ω-production in these reactions is used for testing the OZI selection rule in hadronic processes. It has been demonstrated that in pion reactions the ratio of the yields of ? and ω-mesons R(?/ω) = (3 ± 1) · 10^?3 is in a good agreement with naive quark model prediction based on the mixing in vector meson nonet and on the OZI rule (R(?/ω)ozi = tg ²Δθ _V ? 4 · 10^?3). At the same time in proton reactions the effective ratio of ? and ω yields is ～ (4 ÷ 7) · 10^-2, i.e. a strong violation of the OZI rule is observed in proton-nucleon interactions. This violation can be in favor of possible existence of some exotic ss? component in the quark structure of protons.     

Acidity function of concentrated solutions of 12-tungstophosphoric acid

Conclusions The authors have measured the Hammett acidity functions H₀ of concentrated solutions of H₃PW₁₂O₄₀ in water, aqueous dioxane, and acetic acid. In these solvents the acidity of H₃PW₁₂O₄₀ is higher than those of sulfuric and hydrochloric acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 492–493, March, 1982.