A Method for determining safe concentrations of chloride ions in pitting corrosion of steels in nitrate media

Features of how pitting corrosion develops on steels in nitrate-chloride media are analyzed, and the disadvantages of certain well-known electrochemical methods used to determine safe ratios of components under such conditions are found. A principally new approach to determining these parameters is proposed, based on the induction of intense pitting in definitely aggressive media with subsequent suppression of this process by continuously dilution of the solution or by gradual addition of an inhibitor. Equations are obtained for determining safe component concentrations depending on the volume of solution passing through the cell. Using the proposed method, safe ratios of components are determined for 12Kh18N10T chromium-nickel steel at chloride ion concentrations within 0.02–2.0 M. Original Russian Text ? V.P. Razygraev, M.V. Lebedeva, I.I. Korchak, 2008, published in Korroziya: Materialy, Zashchita, 2007, No. 8, pp. 42–47.     

Unified Method for Evaluating the Strength Properties of the Bottom Parts of High-Pressure Hydraulic Cylinders

Strength of Materials - It is established that the bottom parts of hydraulic cylinders are bearing elements, in which the control valves are built-in, as a result of which their design is...     

Oxidation of methane in a wide range of pressures and effect of inert gases

The analysis of methane oxidation in a wide range of pressures (0.05–10 atm) demonstrates that the efficiency of CH₃ radicals recombination is of great importance for high selectivity of C₂ hydrocarbons formation. The relative efficiency of different “colliders” assisting the stabilization of exited C₂H*₆ molecules increases in the series: solid surface> Ar> He. The increase of the overall reaction rate upon increasing pressure of the inert gases in the case of catalysts having a higher surface area and more developed pore structure is likely due to the contribution of the surface-induced chain reaction in the volume of pores.     

Selective role for beta-protein kinase C in signaling for O-2 generation but not degranulation or adherence in differentiated HL60 cells

A role for protein kinase C (PKC) isotypes is implicated in the activation of phagocytic cell functions. An antisense approach was used to selectively deplete beta-PKC, both betaI- and betaII-PKC, but not alpha-PKC, delta-PKC, or zeta-PKC in HL60 cells differentiated to a neutrophil-like phenotype (dHL60 cells). Depletion of beta-PKC in dHL60 cells elicited selective inhibition of O-2 generation triggered by fMet-Leu-Phe, immune complexes, or phorbol myristate acetate, an activator of PKC. In contrast, neither ligand-elicited beta-glucuronidase (azurophil granule) release nor adherence to fibronectin was inhibited by beta-PKC depletion. Ligand-induced phosphorylation of a subset of proteins was reduced in beta-PKC-depleted dHL60 cells. Phosphorylation of p47(phox) and translocation of p47(phox) to the membrane are essential for activation of the NADPH oxidase and generation of O-2. beta-PKC depletion had no effect on the level of p47(phox) in dHL60 cells but did significantly decrease ligand-induced phosphorylation of this protein. Furthermore, translocation of p47(phox) to the membrane in response to phorbol myristate acetate or fMet-Leu-Phe was reduced in beta-PKC-depleted cells. These results indicate that beta-PKC is essential for signaling for O-2 generation but not cell adherence or azurophil degranulation. Depletion of beta-PKC inhibited ligand-induced phosphorylation of p47(phox), translocation of p47(phox) to the membrane, and activation of O-2 generation.     

Oxidative coupling of methane with participation of oxide catalyst lattice oxygen

Redox properties of the supported Li₂O/MgO, K₂O/Al₂O₃ and PbO/Al₂O₃ catalysts are studied. New mechanism of the catalyst re-oxidation is suggested. Re-oxidation of the catalyst in the course of steady-state reaction can proceed as an oxidative dehydrogenation of surface OH groups.     

Cu,Co, Ag-Containing Pillared Clays as Catalysts for the Selective Reduction of NOx by Hydrocarbons in an Excess of Oxygen

Thermally stable Al- and Zr-PILC loaded with copper and cobalt cations and silver nanoparticles were synthesized. The structural and surface features of these nanosystems were studied and compared with those of bulk analogs – partially stabilized ZrO₂ loaded with the same active components. Specificity of the catalytic properties of nanocomposites in SCR of NO _x by propane, propylene and decane in the excess of oxygen appears to be determined both by distribution of active components on the catalytic surface and degree of their interaction with supports. Formation of ads.-NO _x , nitroxyl-hydrocarbon C _x H _y NO₂ and isocyanate NCO intermediates was observed by ESR and IR spectroscopy in situ.     

Emission properties of thin-film alloys of immiscible components

Results of the investigation of emissive properties of Ba₄₇W₅₃, Ba₅₉Ni₄₁, and Ba₃₃Ni₆₇ (at %) alloys obtained by ion-plasma sputtering of composite targets are presented. It has been found that after vaporquenching, the elemental pairs Ba and Ni and Ba and W that are immiscible in the liquid state form alloys with a mosaic structure consisting of alternate microregions of different elements. Such a structure with alloy components W or Ni (having a high electron density) and Ba (with a low work function φ) produces regions of variable electron density and work function on its surface. This makes it possible to obtain high values of the density of the electron-emission current using these alloys.     

Carbon dioxide reforming of alcohols on porous membrane catalyst systems

The features of the carbon dioxide reforming of ethanol and an ethanol-glycerol mixture to synthesis gas in the presence of porous membrane catalyst systems have been studied. It has been shown that the CO₂ reforming of alcohols in open pores of ceramic membranes modified with nanosized active palladiumcontaining components proceeds at a higher rate as compared to that in a conventional fixed-bed flow reactor charged with a catalyst of similar composition.     

The H2 role in the synergistic phenomenon in selective NO x reduction by propane over a mechanical mixture of oxide catalysts

The synergistic phenomenon observed in NO _x selective reduction by propane over the mechanical mixture of commercial NTK and Ni-Cr-oxide catalysts is explained by the distinctions in the reaction mechanism over the individual mixture components. Hydrogen formed over Ni-Cr-oxide catalyst in propane oxidation significantly increases the rate of interaction between surface nitrate and acetate complexes. Besides, there is an additional input made by the route of NO _x reduction over NTK in the presence of H₂.     

The influence of additives and their concentration on the selectivity of catalysts based on heteropoly compounds in the reaction of propane oxidation

The catalytic properties and X-ray phase structure of molybdophosphoric heteropoly acid modified with Sb, W, and Nb ions have been studied in the reaction of propane oxidation. The additive of Nb ions increases the total activity of catalyst and its selectivity to acrolein and acrylic acid and decreases the selectivity to propylene. The concentration of Nb ions in samples is varied from 0.025 to 1 mol %. The concentration of Nb ions at a level of 0.025–0.1 mol % has the most profound effect on the reaction selectivity and the yield of mild oxidation products. The reaction selectivity depends on both the concentration of added niobium and the reaction conditions. The growth in the reaction temperature increases the conversion and selectivity to acrolein and reduces the selectivity to acrylic acid and propylene. The use of reaction mixture with higher propane concentrations decreases sharply the selectivity to acrolein. The obtained data can be explained by the possibility of the rearrangement of Nb ions between the cationic and anionic sublattices of heteropoly acids and by the change in the ratio between the acrolein and acrylic acid formation rates. The development and application of heteropoly compounds modified with niobium permits to increase the yield of target products in the partial propane oxidation.