Effect of reduction parameters on the particle size of tungsten monocarbide obtained from the blue tungsten oxide

Conclusions A study was made, using the methods of particle size analysis and metallographic examination, of the effects of temperature and bed thickness in the reduction of the blue tungsten oxide upon some properties of tungsten and tungsten monocarbide powders and sintered 6 wt.% Co hard alloys produced from the monocarbide powders. Quantitative results were obtained showing the relationship between these reduction parameters on the one hand and the particle size of the resultant powders and the physicomechanical properties of hard alloys on the other. It was established that the particle size grows with rise in reduction temperature and with increase in the thickness of the blue oxide bed.Translated from Poroshkovaya Metallurgiya, No. 11(143), pp. 102–107, November, 1974.     

Electron transport properties in GaAs at high electric fields

Electron distribution function, drift velocity, mean energy, valley population fractions and diffusion coefficient were calculated at high, up to 100 kV/cm, electric fields. Calculations were carried out by the Monte Carlo method. The three-valley model of GaAs conduction band was used. The obtained results were compared with the experimental data.     

A method for solving the n-dimensional convex hull problem

A method is presented for finding all vertices and all hyperplanes containing the faces of a convex polyhedron spanned by a given finite set X in Euclidean space Eⁿ. The present paper indicates how this method can be applied to the investigation of linear separability of two given finite sets X₁ and X₂ in Eⁿ. In the case of linear separability of these sets the proposed method makes it possible to find the separating hyperplane.     

Physico-Chemical Properties of Cobalt–Ruthenium (10% Co–0.5% Ru) Catalysts Supported on Binary Oxides 8.5%ZrO<Subscript>2</Subscript>/Support (SiO<Subscript>2</Subscript>, Al<Subscript>2</Subscript>O<Subscript>3</Subscript>, TiO<Subscript>2</Subscript>) for Fischer-Tropsch Synthesis

The promotion of Fischer-Tropsch catalysts 10%Co/Al₂O₃, 10%Co/SiO₂, 10%Co/TiO₂ by 0.5% Ru and the modification of supports by 8.5 wt% ZrO₂ have been studied. The following properties: catalyst specific surface area as well as reducibility and dispersion of metallic phase were studied by different techniques: BET, TPR, and H₂ chemisorption. The modification of supports by non-reducible ZrO₂, results in a decrease of cobalt oxide reduction on Al₂O₃ and TiO₂ but not on SiO₂ supports. Additionally the enhancement of cobalt dispersion was found for all catalysts with ZrO₂ modified supports. The impact of Ru promotion is likely due to the stabilization of applied supports, prevention or blockage of interaction between surface Co species and support and an increase in cobalt oxide reducibility to the catalytically active metallic cobalt phase.     

Antioxidant activity and free radical‐scavenging capacity of ethanolic extracts of thyme,oregano, and marjoram

Phenolic compounds were extracted from thyme (Thymus vulgaris L.), oregano (Origanum vulgare L.) and marjoram (Origanum majorana L.) with 95% ethanol. A number of antioxidant and radical‐scavenging capacity tests were performed on the prepared extracts using colorimetric assays and model system studies. Specifically, these included determining the content of total phenolics, antioxidant efficacy in a linoleic acid‐ferric thiocyanate model system, reducing power, scavenging effect on 2,2'‐diphenyl‐1‐picrylhydrazyl radical, and hydroxyl radical‐scavenging activity by electron paramagnetic resonance spectroscopy. Moreover, the efficacies of the prepared herb extracts were investigated in a real‐life food product: the stabilization of butter against oxidation.