Oxidative dehydrogenation of 2,3,5-trimethyl-1,4-hydroquinone in the presence of titanium dioxide hydrogel

Liquid-phase oxidative dehydrogenation of 2,3,5-trimethyl-1,4-hydroquinone in the presence of titanium dioxide hydrogel was studied by a kinetic method. Associative interactions between the substrate, oxidant, and gel were detected by voltammetry and ESR and IR spectroscopy.Russian Foundation for Basic Researc

Thermal properties and structure of cast carbon-containing invar and superinvar alloys after two-stage annealing

The effect of carbon content on thermal properties of cast superinvar alloys subjected to two-stage annealing is studied. It is shown that carbon improves the casting properties of the alloys but raises the temperature coefficient of linear expansion (CTLE). Two-stage high-temperature annealing makes it possible to remove carbon from the solid solution and to transfer it into graphite, which is accompanied by decrease in the CTLE. © 2013 Springer Science+Business Media New York

Measuring angular coordinates in Unmanned Aerial Vehicles (UAVs) positioning systems and developing a new phase-metric method for goniometric control of UAVs

For the safe operation of Unmanned Aerial Vehicles (UAVs), an effective Automatic Control System (ACS) is necessary, which for successful operation requires high accuracy of the initial information about the UAV’s position in space. Based on the analysis of the shortcomings of the known orientation systems, a phase-metric method of goniometric (angular) control based on accelerometric and gyroscopic transducers for positioning the UAV is proposed, which has a higher accuracy and a wider range of measurement angles. The conducted study showed that in a wide range of rotation angles from 10 to 90 degrees, the root mean square error (RMS) of the results of calculating the rotation angle using the phase-metric method is 8,78 times less than the RMS of the results of calculating the rotation angle using the arctangent function. Reducing the error determines the effectiveness of the proposed method in UAV control systems

The activity of element dioxides in liquid-phase oxidation of 2,3,5-trimethyl-1,4-hydroquinone

The influence of silicon, tin, and titanium dioxide hydrogels on liquid-phase oxidative dehydrogenation of 2,3,5-trimethyl-1,4-hydroquinone in an aqueous-methanolic solution was studied by the method of initial reaction rates. The introduction of the gels inhibited the reaction, whereas Cu2+-containing gels accelerated it. The formation of Cu2+ compounds of various types in the gel phases was studied by EPR spectroscopy. The reactivities of these compounds were estimated

Structure and catalytic properties of a Cu 2+-containing hydrogel of zirconium dioxide

The distribution of Cu 2+ ions in ZrO 2 and sulfated ZrO 2 hydrogel phases was studied by EPR spectroscopy and voltammetry. The formation of the following three types of copper structures was observed: mononuclear Cu 2+ complexes (A), magnetic associates (B), and Cu 2+ compounds (C) that gave no EPR signals under the conditions used in the spectroscopic measurements. The specific catalytic activity of various Cu 2+ compounds in the liquid-phase reaction of 2,3,5-trimethyl-1,4- hydroquinone oxidation was determined. The copper complexes C were found to exhibit the highest catalytic activity