Low strain rate plasticity of continuously cast carbon steels

By a special plastometric method, the straightening operation of a vertically cast strand of two carbon steels was simulated. The temperature dependence of the low strain rate plasticity of both the steels examined is analogous although caused by very different reasons. As to the plain carbon steel, the amount of ferrite and its location is of prime importance, whereas in the case of eutectoid steel various modes of fracture and the influence of temperature on the relative plasticity of type II MnS inclusions are influencial. To avoid transverse cracking, it seems to be suitable to keep the strand at a rather high temperature (above 900 °C). Temperature cycling seems to be fundamental as to the structural changes taking place in the strand (grain size refining, ferrite fraction if any), whereas analogous influences of straining are more or less inexpressive. Of course, the results obtained are of quality only since the practical and laboratory conditions differ significantly. The knowledge obtained could be applied in regulating the intensity of strand cooling with the aim of lowering the waste portion and improving the surface quality of worked products.     

Fluorescent staining with bromocresol purple: A rapid method for determining yeast cell dead count developed as an assay of killer toxin activity

A method is described for detecting yeast cells with plasma membrane damage, based on cell staining with bromocresol purple (BCP) which has a convenient fluorescence after entering the cells at pH below 5·2. The method was used to determine the activity of Saccharomyces cerevisiae pore-forming killer toxin K1 in commonly used lethal units. The BCP test is rapid and as precise as the plating test.     

Reaction of glycidyl benzoate with acid in the presence of tertiary amines as the catalyst

The reaction of epoxides with carboxylic acids catalysed by tertiary amines has been discussed. The mechanism of the reaction has been deduced and confirmed, using experimental results, on the example of the reaction of glycidyl benzoate with benzoic acid in xylene, catalysed by benzyldimethylamine. The reaction occurs via a combined ionic mechanism as well as via a complex formation, thus explaining the abnormal dependence of the reaction constant on the dielectric constant of the milieu and the found non-integer orders of reaction with respect to the amine and to the acid.     

Theory of porous electrodes—XII. The negative plate of the lead-acid battery

Partial differential equations describing the transport of mass and electricity in the pores of the negative electrode of a lead-acid battery were derived. The theory is based on exact transport equations and on the assumption that the electrode potential is governed by the Nernst equation. Volume changes in both phases are taken into account. Numerical solutions depend on the product of electrode thickness times current density and on the initial porosity. Differences between the negative and positive plates are discussed.     

Curing of epoxy resins with amines

Summary Using determination of the critical molar ratio of functional groups necessary for gel formation with amino groups in excess, network formation was investigated in the reaction of diglycidyl ether of Bisphenol A (DGEBA) and nitrogen-containing epoxy resins — diglycidylaniline and N,N,N,N-tetraglycidyl-4,4-diaminodiphenylmethane with aromatic or aliphatic amines. It was found that in the case of nitrogen-containing epoxides the crosslinking is accompanied by pronounced cyclization, unlike in systems with DGEBA. Gelation depends on the relative reactivity of the primary and secondary hydrogen atom of the amino group. In the case of nitrogen-containing polyepoxides, the dependence of reactivities of adjacent glycidyl groups is also operative.     

A comparative study of a fluidised bed reactor and a gas lift loop reactor for the IBE process: Part I. Reactor design and scale down approach

For the continuous production of isopropanol-butanol mixtures by immobilised Clostridium spp. (the IBE process) two reactor types were studied: a fluidised bed reactor with liquid recycling (FBR) and an external loop gas lift reactor (GLR). A large scale design (50–65 m³) was made for both reactors. A regime analysis, by evaluating the time constants for e.g. mixing and conversion, identified the ruling regime. Via the scale down approach two representative model reactors were developed: a 10 dm³ FBR reactor (H/D=25, D=0.08 m) and a 15 dm³ external loop GLR (H/D = 12.5, D_r=D_d=0.08 m). For both reactors the hydrodynamical behaviour and the total reactor performance were studied and are described in parts II and III of this study.     

Einfluß der Desoxidation mit Metallen der seltenen Erden auf die Erscheinungsform nichtmetallischer Einschlüsse und die mechanischen Eigenschaften warmfester Chrom-Molybdän-Vanadin-Stahlgußsorten

Desoxidation vonChrom-Molybdän-Vanadin-Stahlgußsorten mit 0,12 bis 0,20%C, 0,25 bis 0,50% Si, 0,50 bis 1,00%Mn, 1,00 bis 1,50%Cr, 0,40 bis 1,10% Mo, 0,10 bis 0,70% V und bis zu 0,70 %W durch Zugabe allein von Aluminium oder einer Eisen-Cer-Legierung sowie durch gleichzeitige Zugabe von Aluminium und einer Eisen-Silicium-Cer-Legierung. Menge und Gestalt der nichtmetallischen Einschlüsse in Abhängigkeit von der zugegebenen Menge an Metallen der seltenen Erden. Änderung der mechanischen Eigenschaften in Abhängigkeit vom Cergehalt im Stahl.