Making ladle products using North Onezhsk bauxites

Conclusions It was found that the North-Onezhsk bauxites are promising raw materials for the production of highly resistant ladle bricks.We developed and mastered a technology in the BKO conditions for making ladle brick using these bauxites containing up to 6% iron oxides.In the lining of the steel ladles made with the use of bauxite chamotte, the bricks wear out 30–40% less than with ordinary ladle brick produced by BKO and the Chasov Yarsk Combine.Translated from Ogneupory, No. 8, pp. 4–9, August, 1980.     

The kinetics of rabbit muscle pyruvate kinase. Initial-velocity, substrate- and product-inhibition and isotopic-exchange studies of the reverse reaction

1. An assay, based on the transfer of label from [gamma-32P]ATP to [32P]phosphoenolpyruvate, suitable for a steady-state kinetic analysis of pyruvate kinase in the reverse direction (i.e. phosphoenolpyruvate synthesis), is described. 2. This assay was used in a kinetic investigation of the rabbit muscle enzyme including initial-rate and product-inhibition experiments, at a pH of 7.4 and constant concentrations of total K+ and free Mg2+. 3. These studies indicate that there is a random release of ADP and phosphoenolpyruvate from the enzyme and that there is a competitive substrate inhibition by ATP. Some of the results were suggestive that the rapid-equilibrium assumption, generally used for this enzyme was not valid. 4. Techniques were developed to measure the rate of isotopic exchange between all the substrate-product pairs. 5. By using these techniques the rates of isotopic exchange at chemical equilibrium were measured. The results indicate that this enzyme does not catalyse a truly rapid-equilibrium random mechanism, although in the forward reaction all initial-rate data obtained to date are consistent with this assumption.     

Responses of complex cells in the visual cortex of the cat as a function of the length of moving slits

(1) As a step towards specifying the spatial selectivity characteristics of complex cells with spatially periodic substructures, we have studied single cell responses to narrow slits of variable length moved across the receptive field in the preferred direction. In general, the length-response curves were linear over a considerable and sometimes full range until an optimal slit length was reached. (2) In those cells in which the rate of rise of the slit length-response functions decreased before the optimal length was reached, at least 3 factors contribute to the shape of the curve. First, the receptive field shapes of some complex cells are more ovoid or rounded than rectangular, and the summation of responses from excitatory zones of varying optimal lengths itself results in a nonlinear slit length-response function at long slit lengths. Second, central regions may contribute more to cell response than do more lateral regions along the length dimension. Third, a nonlinearity in the slit length-response curve may occur in the upper range of slit lengths as a saturation effect because discharge rates may reach 600/sec, which appears to be close to a limiting firing rate. (3) Some cells believed to be complex during preliminary receptive field testing showed weak inhibitory regions beyond the region of the optimal slit length. Many of these cells also displayed periodic average response histograms to moving slits. The extent and magnitude of the inhibition were variable from cell to cell. In terms of receptive field properties, these cells and 'regular' complex cells seem part of a continuum.     

Assessing the coking properties of concentrates in terms of the strength of the nonvolatile residue

The coking properties of coal concentrates are assessed on the basis of the strength of the nonvolatile residue.     

Dynamics and wear of fragments of a lower part of a fuel assembly with free fuel elements

A procedure and findings of investigations of the dynamic characteristics and the wear of fuel elements in the framework of the development of a perspective design of fuel elements without fastening in a lower support grid are presented. At the first phase of the work, natural vibration frequencies and the dynamic rigidity of fuel elements are determined in various design variants of lower spans. Resonance frequencies of spans of fuel elements are revealed by minimums of the dynamic rigidity. At the second phase, investigations of vibrational wear within contact of fuel elements with cells of spacer grids are performed on models of a lower part of a fuel assembly. Four embodiments of the lower part of the fuel assembly are investigated. As a result of the application of high vibrational loads, the wear of fuel element cans and grid cells is observed in more than a half of contact assembles of fuel elements with spacer grids. The most and least wear-resistant designs of the lower part of the fuel assembly are determined by results of tests.