Effect of Longitudinal Diffusion on the Charging Current of Fluid Dielectrics during Their Flow in a Channel

The effect of the entrance part of a channel on the relaxation length of the charging current is studied for the flow of fluid dielectrics with a small admixture of ions in a cylindrical channel.     

Oxidation Reactions of Azines. 10. Synthesis, Structure, and Oxodihydroxylation of 3-Hydroxymethyl-1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine

It has been established that oxidation of a mixture of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and dicyanomethane or formaldehyde with manganese dioxide gives 3-hydroxymethyl-1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, the structure of which was confirmed by X-ray structural analysis. Some oxidative conversions by potassium permanganate of the product formed and its esters have been studied. These included lactamization, aromatization, and oxodihydroxylation.     

Determining a 'safe' high-mass limit in matrix-assisted laser desorption/ionisation time-of-flight mass spectra of coal derived materials with reference to instrument noise

Three methods for determining a 'safe' estimate for high-mass limits of MALDI spectra of coal derived liquids were explored, using a sample of coal-tar pitch and its pyridine-insoluble fraction. Co-addition of increasing numbers of single-shot spectra (10, 30, 50 and 100 pulses) showed visually observable reductions in noise levels, consistent with robust and statistically meaningful signals. Three separate types of post-acquisition calculation were used to identify high-mass limits of the spectra. (i) A literature method indicated high-mass limits similar to those observed visually-as a shift from baseline at the highest masses, nearly 350 000 u for the coal tar pitch and about 390 000 u for its pyridine insoluble fraction. (ii) Comparing instrument signal with pre-selected multiples of the standard deviation, upper mass estimates of between 40-60 000 u for the coal-tar pitch and about 95 000 u for its pyridine-insoluble fraction were found. (iii) Calculation of the slope was used to identify 'lift-off' of the spectrum from baseline. The angle between the smoothed spectrum and the baseline was matched to a pre-selected value (e.g. 0.5 degrees and 1 degrees ). However, the arbitrary specification of the key parameter did not establish this last method on a firm basis. The choice of a criterion for estimating high-mass limits of MALDI spectra remains a semi-quantitative procedure; a reasonably conservative high-mass limit may be estimated by comparison of signal with five times the standard deviation. However, evaluation of size exclusion chromatograms of the present samples using polystyrene standards suggests that molecular mass distributions of pitch samples arrived at by MALDI mass spectrometry are, at least partly, determined by the limitations of available instruments. Copyright 1999 John Wiley & Sons, Ltd.     

The effect of the acceleration of a wedge on the position of the center of pressure with hypersonic velocities

Analytical dependences are obtained for calculating the position of the center of pressure at a thin wedge, with its acceleration with hypersonic velocities in a perfect gas, in the whole range of the hypersonic similarity parameter 0=1.4, in the whole range of K, does not exceed 0.04 SL (S is the Strouhal number; L is the length of the wedge); with K1, there is no shift at all. The results of parametric calculations are given.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 167–170, November–December, 1975.     

Cooperative interactions of metal nanoparticles in the ion-exchange matrix with oxygen dissolved in water

The kinetics of the reduction of molecular oxygen dissolved in water with nanocomposites consisting of an ion-exchange matrix and copper nanoparticles deposited in it in various amounts was studied. As the metal content in the polymer increased, the amount of reduced oxygen initially increased and then reached the limiting value. At a certain metal content, ionization of individual particles with formation of metal counterions changes to the oxidation of particles assembly giving layers of oxide products. The mechanism changes at the percolation threshold of the electron conductivity of the nanocomposite and determines the maximum amount of absorbed oxygen.     

Biomorphic control in problem on active suppression of vibrations

An approach that makes it possible the control elastic objects with a variable number of feedbacks is considered. An algorithm for synthesizing the control based on the spectral expansion is constructed for a distributed object. The advantages of the approach suggested are analyzed. Based on the example of a simply supported beam under the action of a harmonic exciting moment, it is shown that biomorphic control enables a reduction in the number of feedback loops by several times without reducing the quality of vibration suppression. The sensitivity of the method to the accuracy of determining the object model parameters is studied.     

Oxidizing Reactions of Azines. 8. One-reactor Oxidation of 4-Aryl- and 4-Methyl-1,2,3,6-tetrahydropyridines to 1-Formylamino-substituted Alkan-3-ones

One-reactor oxidation by potassium permanganate has been carried out for a series of 4-aryl- and 4-methyl-1,2,3,6-tetrahydropyridines to give 1-formylamino-substituted 3-arylpropan-3-ones and butan-3-ones. The effect has been studied of the nature of the substrate, the temperature, and interphase transfer catalysts on the yield of amino alkanone. It is proposed that the reaction proceeds through the intermediate formation of 3,4-dihydroxypiperidin-2-ones which then undergo oxidative decyclization with elimination of one carbon atom.     

Numerical investigation of flow of a viscous reacting gas past blunt bodies

Numerical solution of the Navier—Stokes equations is used to estimate the limits of applicability of simplified models used to describe the laminar nonequillbrium flow of a viscous multicomponent reacting gas past blunt bodies moving at hypersonic velocity in air.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 19–23, September–October, 1982.