Kinetic study of the hydrolysis of isocyanic acid in the gas phase

The hydrolysis of isocyanic acid in the gaseous phase has been investigated at temperatures between 553 and 613 K by mass spectrometry and evaluated to obtain the corresponding kinetic data. The reaction order and reaction constant have been determined. Finally, the influence of water on the catalysed formation of melamine from isocyanic acid under the operating conditions employed has been investigated in order to determine whether there is a need to try the process gas.     

Self-ignition and combustion of a water-fuel emulsion during its injection into heated air. II. Ignition delay time of M-40 fuel oil

We studied experimentally the influence of the degree of water emulsification ofM-40 mazut heated to the water boiling point on the self-ignition time with its pulsed high-pressure injection into heated air. It is shown that water addition does not change the chemistry of the reaction and heating the water-fuel emulsion leads to the disappearance of differences in the ignition character of the emulsion and the moisture-free fuel. It is confirmed that the features of selfignition are determined mostly by conditions of mixture formation. Indirect evidence is obtained that the dynamic tensile strength of the fluid strongly influences the primary dispersion of the jet during its outflow from the sprayer nozzle.Institute of Theoretical and Applied Mechanics, Novosibirsk 630090. Translated from Fizika Goreniya i Vzryva, Vol. 31, No. 4, pp. 20–25, July–August, 1995.     

Transient and dynamic average-value modeling of synchronous machinefed load-commutated converters

A new average-value model of a synchronous machine fed load-commutated converter is set forth in which the stator dynamics are combined with the DC link dynamics. This model is shown to he extremely accurate in predicting system transients and in predicting frequency-domain characteristics such as the impedance looking into the synchronous machine fed load-commutated converter. The model is verified against a detailed computer simulation and against a hardware test system, thus providing a three-way comparison. The proposed model is shown to be much more accurate than models in which the stator dynamics are neglected     

KGa-priderite and related compound for the selective reduction of nitrogen monoxide with propylene

The catalytic activity of KGa-priderite, K_1.6Ga_1.6Ti_6.4O₁₆, and its related compound KGa₈Ga₉Ti₁₅O₅₆ was investigated for the selective reduction of nitrogen monoxide (NO) with propylene (C₃H₆) in the presence of high oxygen concentrations. The KGa-priderite showed significant activity during this reaction, but the related compound showed only a little activity. These compounds are quite different from the conventional catalysts for NO_x selective reduction and are characterized by the fact that their properties are free from the effects of solid acidity and support metals. This difference was attributable to the NO desorption rate at the surface of these compounds. It has become clear that the KGa-priderite catalyst remarkably adsorbed NO, and it is suggested that the amount of NO adsorbed and the amount of catalytic activity are able to be increased by the design of priderite structure.     

Mathematical and experimental investigation of the self-propagating high-temperature synthesis (SHS) of TiAl3 and Ni3Al intermetallic compounds

One-dimensional mathematical modeling was used to describe the self-propagating high-temperature synthesis (SHS) process for preparing TiAl₃ and Ni₃Al intermetallics. The kinetic parameters (activation energies and pre-exponential factors) for the two compounds were obtained by matching experimental measurement and the numerical solution. The results thus obtained were compared with rate parameters obtained using different methods. The activation energy was 483 and 283 kJ mol^?1 for the formation of TiAl₃ and Ni₃Al, respectively. The temperature profiles calculated using the mathematical model were compared with experimental measurements for both aluminides which indicated reasonable agreement. Fine particle size and moderate preheating increase the SHS rates.     

Analysis of composite laminates with transverse cracks

The analysis of the behaviour of composite laminates with general balanced lay-up sequences and containing distributed transverse cracks is discussed and demonstrated in this paper. It is shown that a constitutive model of damage for composites, which has been successfully used to analyse the effects of uniformly distributed transverse cracks in cross-ply laminates, can be readily extended to the analysis of uniformly distributed transverse cracks in more general symmetric laminates. The further extension of the theory to non-uniformly distributed damage can be achieved by finite element analysis. It is shown that the finite element implementation of the theory is particularly simple since the contribution of the damage to the overall behaviour can be incorporated into the force vectors.     

New substrates of papain, based on the conserved sequence of natural inhibitors of the cystatin family

A discontinuous borate/formate buffer system is presented for horizontal polyacrylamide gel electrophoresis of DNA fragments. The resolution potential of the system could be altered by changing the total monomer concentration (5-9%T), the concentration of the crosslinker piperazine diacrylamide (2-5%CPDA), as well as the concentration of formate in the gel (40-120 mM), the leading ion of the buffer system. The separation of DNA fragments would be improved by increasing the migration distance from 22 to 28 cm. This discontinuous polyacrylamide gel electrophoresis system proved highly reproducible.