Synthesis and characterization of {Fe2CuO} clusters as precursors for nanosized catalytic system for Biginelli reaction

The novel μ₃-oxo-bridged heterotrinuclear iron(III)-copper(II) trichloroacetates of the composition [Fe₂CuO(CCl₃COO)₆(THF)₃] (1a) and [Fe₂CuO(CCl₃COO)₆(4-DMAP)₃] (1b) have been synthesized and characterized by X-ray crystallography, IR and Mossbauer spectroscopy. These clusters were used as precursors for the synthesis of the nanosized catalytic system (～5–6 nm of γ-Fe₂O₃/CuO), which works as an efficient organic phase catalyst (～0.02 mol%) in a one-pot three component Biginelli synthesis.     

Phase Equilibria in the Nd ― Re ― B System

Powder Metallurgy and Metal Ceramics - XRD has been applied to component interaction in the Nd ― Re ― B system. Isothermal sections have been constructed for the phase diagram at...     

Sintered Antifriction Materials for Use at Elevated Temperatures

The mechanical and antifriction properties of three types of new materials were investigated. These were based on powder scrap of steel R6M5, nickel, and the powder metallurgy nickel alloy ÉP975. The metallographic structures of the new materials were studied. It was shown that the developed materials can be successfully used in friction units operating at 500, 700, and 900°C, respectively.     

Synthesis and gas permeation parameters of metathesis polytricyclononenes with pendant Me3E‐groups (E = C,Si, Ge)

Metathesis polytricyclononenes were synthesized via ROMP polymerization in the presence of the 1‐st generation Grubbs catalyst and their gas‐transport properties were studied for the first time. The aim of this work was to evaluate the influence of Me₃E‐groups (E = C, Si, Ge) on gas permeation parameters of ROMP materials. New metathesis poly(3‐tert‐butyltricyclononene‐7) and poly(3‐trimethylgermyltricyclononene‐7) were obtained with high yields (up to 95%) and high‐molecular weights (M_w～3–7×10⁵ g mol^?1). The glass transition temperatures of the ROMP polytricyclononenes with Me₃E‐groups decreased when E was changed from C to Si and then to Ge. It was shown that the polytricyclononene containing Me₃Si‐groups has the highest gas permeability while the polytricyclononene containing Me₃C‐substituents has the lowest gas permeability. In addition, the gas permeation parameters were estimated for ROMP Me₃Si‐ and Me₃Ge‐substituted polytricyclonona‐3,7‐dienes. So the influence of the second double bond in the monomer units on the permeability of the polymers obtained was studied. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41395.     

Kinetics and mechanism of low-temperature ozone decomposition by Co-ions adsorbed on silica

Kinetics and mechanism of low-temperature ozone ((5–50) × 10⁻³ mol/m³ in the gas–air mixture) decomposition by Co-catalysts supported on silica have been studied. Co-ions adsorbed on silica react with surface oxygen species, thus resulting in an active catalyst. Low concentrations of Co-ions form a monolayer on the surface. Their specific catalytic activity remained constant, but sharply decreased at higher concentrations due to a formation of polynuclear Co-complexes. Ozone decomposition may occur either as a stoichiometric or catalytic process, depending on the ozone and catalyst concentrations. The turnover number increases with ozone concentration reaching a saturation point. It also increases with Co-concentration in the beginning, but drops at a concentration >1 × 10⁻⁴ mol/g. The mechanism of the reaction is discussed.     

Eigen electromagnetic oscillations in the waveguide-dielectric resonator with two-layer filling

The method of the solution problem on the eigen oscillations spectrum of electromagnetic field in the waveguide-dielectric resonator with the two-layer dielectric element was presented. The numerical calculations of the resonance frequencies for theHE ₁₁₁-,E ₀₁₁- andH ₀₁₁-oscillations types in the investigated structure were performed. The calculation results were correlated with experimental data.     

Angular diagram of broadband emission of millimeter-sized water droplets exposed to gigawatt femtosecond laser pulses

We report on the experiments on the interaction of gigawatt femtosecond laser pulses with suspended millimeter-sized water droplets. The transparent droplets experienced laser-induced breakdown and explosive boiling up and emitted a broadband radiation. This radiation covers the spectral range from 450 to 1100?nm and consists of the spectrum of laser pulse scattered and transformed by the droplet due to self-phase modulation and plasma emission produced in water during photoionization. The droplet emission spectrum showed remarkable broadening at all viewing angles and is maximal in the direction of the laser exit from the droplet. The enlargement of the droplet results in additional spectral spreading of the emitted radiation. The depth and amount of laser pulse spectral self-transformations upon propagation through the water droplet are simulated by means of numerical calculations.     

Numerical investigation of deformation localization and crack formation in elastic brittle-plastic materials

Localized deformation band formation and crack generation in elastic brittle-plastic materials were simulated numerically in various loading conditions. Cracking patterns for a specimen with a failed inclusion and for a damaged layer of a geomedium in shear, as well as for a sandstone specimen in compression, were obtained. To describe deformation, a complex approach was used. According to this approach, in the course of plastic deformation damages are accumulated and govern bulk plastic deformation. Due to damage accumulation, strength decreases and material degradation occurs, while macrocrack opening and material fracture take place only under the action of tensile stresses.