The disordered cubic structure of Ca7Co3Ga5O18

The new mixed oxide having composition close to Ca₇Co₃Ga₅O₁₈ was synthesized from CaCO₃, Co₃O₄ and Ga₂O₃ at 1150 °C in air and studied by neutron and synchrotron X-ray powder diffraction, selected-area electron diffraction and high-resolution electron microscopy. The structure was refined, using time-of-flight (TOF) neutron powder diffraction data, in space group F432, with and Z=8, to R_F=0.7%. It is considerably disordered, with four different tetrahedral sites randomly occupied by Co and Ga atoms at a ratio of 1:2. The tetrahedra form a disordered (Co_1/3Ga_2/3)O₂ 3D-framework inside which isolated CoO₆ octahedra, surrounded by 8 Ca atoms, are located. The structure is related to the ordered structure of Ca₁₄Al₁₀Zn₆O₃₅. Electron diffraction patterns confirmed the symmetry and unit cell and revealed no diffuse scattering. High-resolution electron microscopy images showed the absence of extended structural defects.     

Measurements of π+p,K+p and pp elastic scattering)

The paper presents the results on differential cross sections for elastic scattering of 7⁺-, K⁺-mesons and protons on protons in the 4-momentum transfer squared range 0·08 ¦t¦ 1·0 (GeV/c)² and incident particle momentum of 29 and 43 GeV/c for pions and kaons and 29, 43, 50 and 65 GeV/c for protons. The measurements were taken with the spectrometer Sigma, installed in the positive beam of the IHEP accelerator.Presented by F. A. Yotch at the Symposium on Hadron-Hadron Scattering at High Energies, Liblice, Czechoslovakia, June 16–21, 1975.The authors would like to express their gratitude to A. A.Logunov, Yu. D.Prokoshkin, L. D.Soloviev and V. A.Yarba for their support of this experiment. We are indebted to CERN Administration for giving us a permission to use a part of equipment of the CIBS spectrometer and to W.Kienzle for useful discussions.     

Remote activation of capsules containing Ag nanoparticles and IR dye by laser light

We present a novel method for remote release of an encapsulated material from polyelectrolyte capsules based on laser light illumination. Two different components were introduced in the polyelectrolyte shells of PAH/PSS capsules-either Ag nanoparticles or IR dye-to induce absorption of light. Under laser illumination the capsules containing Ag nanoparticles or IR dye were deformed or cut, thus providing a venue for remote release of encapsulated materials. The experiments were conducted with a low-power near-infrared continuous-wave laser diode.     

Polyelectrolyte multilayer capsules as vehicles with tunable permeability

This review is devoted to a novel type of polymer micro- and nanocapsules. The shell of the capsule is fabricated by alternate adsorption of oppositely charged polyelectrolytes (PEs) onto the surface of colloidal particles. Cores of different nature (organic or inorganic) with size varied from 0.1 to 10 mum can be used for templating such PE capsules. The shell thickness can be tuned in nanometer range by assembling of defined number of PE layers. The permeability of capsules depends on the pH, ionic strength, solvent, polymer composition, and shell thickness; it can be controlled and varied over wide range of substances regarding their molecular weight and charge. Including functional polymers into capsule wall, such as weak PEs or thermosensitive polymers, makes the capsule permeability sensitive to correspondent external stimuli. Permeability of the capsules is of essential interest in diverse areas related to exploitation of systems with controlled and sustained release properties. The envisaged applications of such capsules/vesicles cover biotechnology, medicine, catalysis, food industry, etc.     

Derived equivalence of symmetric special biserial algebras

The Brauer complex of a symmetric SB-algebra is introduced. The so-far known invariants of the stable and derived equivalence of symmetric SB-algebras are stated in terms of the Brauer complex. In particular, the genus of the Brauer complex turns out to be invariant under derived equivalence. Transformations of Brauer complexes that preserve the class of derived equivalence are studied. The SB-algebras with Brauer complex of genus 0 are classified. Bibliography: 7 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 343, 2007, pp. 5–32.     

Hydrogen-bromate flow battery: can one reach both high bromate utilization and specific power?

Journal of Solid State Electrochemistry - Hydrogen-bromate flow battery is a promising hybrid current source for air-deficient environment that functions by electrocatalyzed reactions of hydrogen...     

Diffusion in a tube consisting of alternating wide and narrow sections

The problem of the diffusion of particles in a tube consisting of identical units, each composed of a wide and narrow section is solved. With an approach based on reducing the problem to a one-dimensional, the statistics of times of particle transition between adjacent sections is determined, which is a detailed characteristic of the diffusion process. An expression for the effective diffusion coefficient D _ef , defining the slow-down of transport due to variations of the tube profile, is derived. It is shown that D _ef behaves monotonically with increasing length of both the narrow and wide sections. The predictions of analytical formulas are in good agreement with the results of computer simulation performed by the Brownian dynamics method.     

A Mixture of Phospho-, Vanadium-, and Molybdo-Heteropolyacids as a Promising Cathode Redox-Mediator for Hybrid Hydrogen–Air Fuel Cells

Russian Journal of Electrochemistry - Hydrogen–air fuel cell is one of the promising types of chemical power sources, it has a variety of applications. However, utilization of the cathodic...     

Crystal structure and properties of the Na1−x Ru2O4 phase

Sodium ruthenium(III,IV) oxide Na_1−x Ru₂O₄ was synthesized by the solid state reaction of Na₂CO₃ and RuO₂ in inert atmosphere and characterized by X-ray powder diffraction, electron diffraction, and high-resolution transmission electron microscopy. The compound crystallizes in the CaFe₂O₄-type structure (space group Pnma, Z = 4, a = 9.2641(7) Å, b = 2.8249(3) Å, c = 11.1496(7) Å). Double rutile-like chains of the RuO₆ octahedra form a three-dimensional framework, whose tunnels contain sodium cations. The structure contains two crystallographically independent sites of ruthenium atoms randomly occupied by the Ru^III and Ru^IV cations. The superstructure with the doubled b parameter found for one of the samples under study using electron diffraction is caused, probably, by ordering of the Ru cations in the rutile-like chains. The Na_{1− x} Ru₂O₄ compound exhibits temperature-independent paramagnetism with χ₀ = 1.9·10⁻⁴ cm³ (mole of Ru⁻¹). Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1655–1660, October, 2006.