Persistence of nonprotein seed amino acid s-(β-carboxyethyl)-cysteine in young leaves ofCalliandra rubescens Ecological implications

The insecticidal nonprotein amino acid S-(-carboxyethyl)-cysteine (S-CEC) is the major free amino acid in the seeds of severalCalliandra spp. where it accounts for up to 2.9 % of dry weight. Lesser amounts of other related S-containing amino acids and an array of nonprotein imino acids derived from pipecolic acid are other constituents. High concentrations of imino acids, which also show insecticidal activity, are maintained in the mature leaves, but sulfur compounds are lacking. In this study the disappearance of S-CEC from the germinating seeds and young seedlings ofC. rubescens was monitored over time. After 10 weeks, S-CEC continues to be found in high concentrations in the stems and new leaves. As young leaves mature, sulfur compounds quickly decrease in concentration. Traces of S-CEC are found in new leaves of plants up to nine months after germination. Whether high concentration of S-CEC in young leaves is due to transportation from the seed or de novo synthesis is unclear. The ecological implications are discussed.     

Obtaining high-alumina cement at the semiluksk refractories factory

Conclusions We demonstrate that it is, in principle, possible to obtain refractory high-alumina cement on industrial equipment at the Semiluksk refractories factory. Technological parameters were developed for preparing raw mixtures, pressing the green articles and firing in a tunnel kiln. It was established that the mass percentage of SiO₂ in the raw mixture should not exceed 1.5%. For industrial production of high-alumina cement in department No. 1 it is necessary to implement measures on the mechanization of the production process.Translated from Ogneupory, No. 5, pp. 26–28, May, 1986.     

Comparison between some empirical equations of state for polymers

Some commonly used empirical equations of state for polymers are considered: the Spencer-Gilmore equation with two and three adjustable parameters, the Whitaker-Griskey equation, and the Rehage-Breuer equation. Also, a new equation is proposed: the Inverse Volume equation. These equations are evaluated with regard to fitting experimental P-V-T data and agreement with experimental data on isothermal compressibility and thermal expansion coefficient. The adjustable parameters for each equation are determined with the help of Rosenbrock's optimum-seeking technique. Analysis of the residuals on specific volume for a variety of materials suggests that the Spencer-Gilmore equation with three adjustable parameters, the Rehage-Breuer and the Inverse Volume equations yield the smallest and most random residuals and thus the least systematic error. The same three equations mentioned above yield results in good agreement with experimental isothermal compressibility data. However, among all the equations considered in this study, the Inverse Volume equation yields the best agreement with experimental thermal expansion coefficient data. Furthermore, it is the only equation to correctly predict the rise in thermal expansion coefficient with increasing temperature.     

Polymer reactors and molecular weight distribution. VIII. A method of interpreting skewed GPC chromatograms

A new-method of interpreting GPC chromatograms which accounts for skewing and symmetrical axial dispersion has been developed. General relationships for a symmetrical axial dispersion correction and for a skewing correction are derived. The method has been verified experimentally for unimodal chromatograms and linear calibration curves over a wide range of GPC operating conditions, polymer molecular weights and polydispersities. Measurements of h and skewing factors were obtained by a once-through technique. The need for performing reverse flow experiments has been eliminated. Artificial oscillations in the corrected chromatogram due to step size (Method of Pierce-Armonas), and to number of terms in a polynomial expansion (Method of Tung and Method of Smith) are eliminated. The method has yet to be evaluated for nonlinear calibration curves and multi-modal distributions. However, suggestions for its application in these circumstances are presented.     

The chemistry of fast-curing phenolic adhesives. I

Certain low molecular weight, resinous polymers, such as those derived from phenol and formaldehyde, may be chemically modified with aromatic amines to produce other resins of physical properties similar to those of the original resins, but with chemical reactivity which is orders of magnitude faster than that of the unmodified resins. This means that while an ordinary phenolic adhesive cures in minutes at high temperature, a properly modified phenolic can be advanced in seconds at ambient conditions to a cured resin of strength and durability comparable to those of ordinary phenolic adhesives.     

Oxidation induction time correlations with radiation dose and antioxidant concentration in EPR and XLPE polymers

Oxidation induction time (OIT), as measured by differential scanning calorimetry, is useful in assessing the extent of degradation in polymeric materials. Values of OIT for typical EPR and XLPE polymer insulation materials used for electric cable insulation in nuclear power plants were measured as a function of both radiation dose and antioxidant concentration after accelerated aging. Irradiations were performed at the University of Virginia Cobalt Irradiation Facility. OIT was found to decrease exponentially with increasing radiation dose and with decreasing antioxidant concentration for both ethylene-propylene rubber (EPR) and cross-linked polyethylene (XLPE) insulations. It was determined experimentally that, when polymers are subjected to a constant radiation dose rate, antioxidant concentration decreases linearly with time, and it was shown that this variation is consistent with theoretical autoxidation kinetics. © 1993 John Wiley & Sons, Inc.     

Metal recovery in a pilot-scale rotating cylindrical wiper-blade electrode system

The performance of an experimental pilot-scale electrochemical reactor using a rotating cylindrical electrode equipped with wiper blades is described. Data obtained from monopolar depositing and bipolar stripping—depositing of copper from dilute aqueous electrolytes are presented and certain economic aspects of metal recovery are discussed.     

The anodic oxidation of methanol via continous electrode reactivation

The anodic oxidation of methanol in a rotating tripolar wiper blade cell has been studied to determine experimental condition required for continuous reactivation of the electrode surface. A plausible mechanism of the reactivated oxidation reaction is also presented.