Kinetics of redox processes in manganese oxides

The redox processes in ceramic and powder samples of α-Mn₂O₃ (kurnakite) and β-Mn₃O₄ (hausmannite) have been studied in the temperature range 20–1000°C. The results demonstrate that the conversion of α-Mn₂O₃ to β-Mn₃O₄ in the binary system Mn-O is essentially irreversible, even if there are nucleation centers in the form of the higher oxide α-Mn₂O₃ during the oxidation of hausmannite. It is shown that the high reactivity of hausmannite ground in a WC mill is not due to a mechanochemical effect. Grinding-induced contamination has a significant effect on the oxidation behavior of the system: the impurities incorporated into the sample during grinding in a mill favor complete (WC contamination) or partial (Fe contamination) conversion of hausmannite to kurnakite. Hausmannite contaminated with tungsten carbide oxidizes by a catalytic mechanism. In the case of Fe impurities, oxidation follows a solid-state mechanism, through the formation of restricted Fe_xMn_2?x O₃ solid solutions.     

Fe substitution for Mn in Rhombohedral La0.8Sr0.2Mn1−xFexO3 — the Structural,Magnetic, and Magnetocaloric Properties

Journal of Superconductivity and Novel Magnetism - The effect of Fe doping on the structural, magnetic, and magnetocaloric properties was studied on La0.8Sr0.2Mn1?xFexO3...     

Provision of the required wear resistance criteria of heavy-duty gas turbine engine parts based on the control of the cutting conditions

A method for determining the wear resistance of parts has been presented based on the systematization of the modular source data bank, the evaluation of the surface layer quality parameters, the cutting accuracy, and the cutting conditions. As a result of the study, the calculated dependences have been obtained in terms of the determination of the optimal part cutting modes in relation to the provision of the target surface wear resistance parameters.     

UVS112—A gene involved in excision repair of yeast

In this study we show that the previously described uvs112 (uvs12) mutation blocks one of the steps of the excision repair pathway. The properties of this mutation permit the assignment of the UVS112 gene to the RAD3 epistasis group. It was established that the uvs112 mutation caused a 2·5-fold reduction in the number of recombinants produced by conversion and also significantly increased the frequency of mitotic crossing-over in interplasmid recombination. Tetrad analysis placed the UVS112 gene on the left arm of chromosome IX, approximately 20 cM from HIS5. The analysis of mitotic recombination revealed that UVS112 lies between HIS6 and HIS5, and is an allele of the RAD25 gene.     

Porous thin-walled corundum products manufactured by pressure slip-casting

Conclusions A technology was developed for the manufacture of thin-walled (wall thickness 2–4 mm) porous corundum products with a reduced thermal conductivity.The products are pressure-cast from slips of corundum powder of particles smaller than 40 and fired at 1580°C. It was confirmed that the addition of 10% ZrO₂ to the starting materials results in an increase of the thermal-shock resistance of the products.Translated from Ogneupory, No. 2, pp. 42–47, February, 1978.     

Cytological parameters of buccal epithelium for the diagnosis of functional state of man

The past twenty years have seen dramatic growth and consolidation in DHMO and PPO segments of the dental benefits industry. Purchasers and patients are becoming more vocal in their demands, primarily for controlling costs. It is predicted that emerging trends will include greater emphasis on quality (and its relationship to cost) and on dental practice management companies. It is less clear what role organized dentistry will play in these changes.     

Robot Stamping System for Compressor Blades in Gas-Turbine Engines

Russian Engineering Research - The development and practical introduction of a robot hot-stamping system for compressor blades in gas-turbine engines is discussed. The benefits of this system are...     

Temperature Selection in the Preheating of Blanks for the Stamping of Large Wide-Chord Fan Blades

Russian Engineering Research - A new approach to the stamping of large wide-chord compressor blades is considered. Analysis of the constraints on the preheating of the blanks permits practical...