Specific features of the unsteady combustion of planar Ti–2B–αCu samples

The modes of spin gasless combustion of plate- and disk-shaped Ti–2B–Cu samples are investigated using frame-by-frame filming. The combustion process takes place under unsteady conditions. An increase in the diameter of the reaction sample makes the pattern of movement of the reaction front more complicated.     

Evolution of a Non-Uniform Deformed State in the Structure of Zinc-Chalcogenide Cubic Crystals Doped by 3 d Ions

The real structure of bulk Zn1 – хМхSe (S) crystals of diluted magnetic semiconductors with М = V, Cr, Fe, Co, Ni 3d impurities is characterized by neutron diffraction. These impurities are known to greatly destabilize even the initial lattices of pure zinc chalcogenides. Data on the resulting non-uniform microstrain field induced by atomic displacements are obtained from the structural peaks along the tangential and radial directions on the above crystals within a dopant concentration range of 0.01 ≤ х ≤ 0.10. Additional nodes with q = (1/3 1/3 1/3) 2π/a (q is the wave vector and a is the cubic unit cell) emerging in the reciprocal lattice of the cubic structure are considered as evidence for a pre-transition to the fcc (face-centered cubic)–hcp (hexagonal close-packed) phase state, which implies transitions from the fcc lattice along an 8-ray non-Lifshitz star with the wave vector k5 = μ(b1 + b2 + b3), where b1, b2, b3 are the reciprocal lattice vectors and μ ≈ 1/3.     

Correction to: The effect of small silver inclusions on the palladium activity in formicacid oxidation reaction and corrosion stability

A PdAg deposit containing ~ 25 at.% Ag is obtained by the electrochemical codeposition from an aqueous solution of Pd and Ag sulfates (Au support, 0.5 M H₂SO₄). The deposit is characterized by means of various physical, physicochemical, and electrochemical methods. The PdAg deposit demonstrates the ~ 2 times higher specific activity (per the electrochemically active surface area (EASA) of Pd) in the formic acid oxidation reaction (FAOR) as compared with the individual Pd deposit prepared under the same conditions. The effect of silver additions on the palladium activity depends on many factors. The corrosion stability of PdAg is studied in 0.5 M H₂SO₄ solution based on the overall cyclic voltammograms (CVAs) and also on anodic and cathodic half-cycles in the region E = 0.3 − 1.25 V (vs. reversible hydrogen electrode (RHE)). The electrochemical estimates are compared with the results of direct analytical determination of dissolution products in solution after anodic polarization of deposits. The total amounts of Pd dissolved substantially increase with incorporation of Ag, which is associated, first of all, with the considerable increase in the EASA; at the same time, the specific dissolution of Pd also substantially increases. The possible factors determining the active dissolution of PdAg deposits are discussed; in particular, the specific mechanism of their dissolution via silver adatoms is proposed.

     

Pyrolysis of Polyurethanes. Process Features and Composition of Reaction Products

Russian Journal of Applied Chemistry - An increase in the production and consumption of polyurethane products used in heavy and light industry, in the construction industry, automotive, medicine,...     

The effect of silver ions electrolytically introduced into colloidal nanodiamond solution on its viscosity and thermal conductivity

Experimental data have been presented on the influence of silver on the viscosity and thermal conductivity of a dispersion of diamond nanoparticles. A stable dispersion (5 wt %) of detonation nanodiamond particles has been used in the experiments. Silver ions have been introduced electrolytically into the dispersion of diamond nanoparticles. Silver concentration was not higher than 0.05 wt %. It has been shown that the introduction of silver ions significantly affects the thermal conductivity and viscosity of the dispersion.     

Determination of explosive vapor concentrations with remote sampling in the control of objects

A procedure is proposed for the determination of the vapor concentration of 2,4,6-trinitrotoluene (TNT) in air at a level of 10^–16 g/cm³ in the control of objects for the presence of TNT. The procedure includes preconcentration of TNT vapors and gas chromatographic determination with a limit of TNT detection at a level of 0.08 ± 0.02 pg in a sample. The procedure was applied to the control objects in cells of typical automatic luggage locker with sampling through sampling air ducts. A measure of sample losses as the breakthrough of vapors through sampling air ducts and gas dynamic conditions for the reduction of vapor losses as the ratio of diffusion coefficient to the air duct flow rate were proposed. The time constant of the saturation of the sampling system with TNT vapors and the time constant of its cleaning were determined. It was shown that TNT vapors can be detected virtually satisfactorily near TNT-containing objects with sampling through long channels.     

Hybrid materials based on polymethylsilsesquioxanes containing Fe,Pt, and Fe–Pt metallic nanoparticles

New hybrid materials based on Pt, Fe, and Pt–Fe nanoparticles stabilized in a matrix of polymethylsilsesquioxane nanogel and ultrahigh molecular weight polyethylene (UHMWPE) were prepared. Metal vapor synthesis was used to produce mono- and bimetallic nanoparticles. It was shown that organosilicon nanogel effectively stabilizes Pt nanoparticles with an average size of 0.9 nm. Using the nanogel results in the formation of superparamagnetic Fe particles 3–5 nm in size that consist of ferromagnetic Fe⁰ core and antiferromagnetic shells of Fe oxides. It is established that using an organosilicon matrix in the formation of Pt-Fe/UHMWPE systems helps reduce the average particle size of Fe in the material from 6.5 to 4.5 nm and narrow their particle size distribution. The composition, magnetic and electronic characteristics of the nanocomposites are studied via transmission electron microscopy, X-ray photoelectron spectroscopy, Mössbauer spectroscopy, XANES, and EXAFS.     

Electrochemical oxidation of dyes on oxide lead anode with the involvement of active oxygen species

Kinetics and selectivity of oxidation of dyes (Methyl Orange and Chrome Dark Blue) on a lead dioxide (Pb/PbO₂) anode at various current densities, substrate concentrations, and pH values with the use of various active oxygen species was studied. It was shown that the electrochemical oxidation of dyes on the Pb/PbO₂ anode occurs rather effectively under the chosen conditions. The mineralization efficiency in 5 h was 51 to 89.5 and 93 to 100% for, respectively, Methyl Orange and Chrome Dark Blue, depending on the electrolysis conditions.