Solution polymerizations of epoxytetrahydrophthalic anhydride and its utilization in various epoxy systems

Solution polymerization of epoxytetrahydrophthalic anhydride (ETHPA) has been thoroughly studied by using numerous solvents and catalysts. Products have been obtained in high yields, particularly when triethanolamine was the catalyst. This suggests that this catalyst should be considered for further applications utilizing ETHPA. However, the solution polymerization method cannot be used alone to define the effects of various catalysts on standard nonsolvated resin systems, because polymerization is greatly affected not only by the addition of solvent but also by the type of solvent. In addition, the action of the catalyst seems to depend greatly upon what solvent is employed. The reason for this dependence has not been established. The effects of the addition and reaction of ETHPA with commercial epoxy resin formulations have been investigated by means of heat distortion tests and differential thermal analyses. In most cases, although a moderate improvement was found in the thermal properties of the resins, occasional excellent results were obtained. A 10°C. increase in HDT is observed with a 2 wt.-% addition of ETHPA for bisphenol A epoxy resin–bicyclic anhydride mixture. The degree of elevation of T_g and HDT with the addition of ETHPA obviously depends not only on the composition of the resin system but also on its cure temperature. A good correlation occurs between heat-distortion temperatures and glass transition temperatures. Some few anomalous data, however, are found which point to the fact that further investigation is required before HDT and T_g can be interchanged without prior evidence of a definite relationship.     

Flash pyrolysis of Australian coals: Effects of pre-oxidation and of oxygen in the inlet gases on formation of agglomerated material

Addition of oxygen to nitrogen in the inlet gas during flash pyrolysis at 600 °C reduced the amount of char agglomerate formed from a relatively strongly caking Liddell seam coal and a weakly caking Millmerran seam coal. The reduction of agglomeration was significant over the entire ranges of variables used, viz, oxygen concentrations in the inlet gas of 2.62–10.5% (v/v) and oxygen to coal ratios of 0.02–0.12 (wt/wt). Pre-oxidation at 400 °C with solids residence times below 2 s, inlet concentrations of oxygen up to 10.5% and oxygen to coal ratios up to 0.10 (wt/wt) also effectively reduced agglomeration of Liddell coal. In terms of minimizing the oxygen requirement to obtain essentially nonagglomerating solids, the preferred method was found to be pre-oxidation followed by oxidative pyrolysis. The reduction of agglomeration by oxygen appears to be due to a combination of the extent of coal oxidation and the extents of polymerization and chemical condensation of the coal structure.     

Effect of recombinant cytokines on leucocytes and physiological changes in bovine mammary glands during early involution

We examined the effects of administering recombinant bovine cytokines to non-lactating dairy cows and measured mammary gland leucocytes and the involution process. After the final milking, groups of cows were given an intramammary infusion of cytokine in two quarters. These cytokines were recombinant bovine interleukin-2 (rbolL-2) (2 x 10(5) units, n = 6), recombinant bovine granulocyte-macrophage colony stimulating factor (rboGM-CSF) (500 microg, n = 4) and recombinant bovine interleukin-1beta (rbolL-1beta) (10 microg, n = 10). Each animal also received an infusion of phosphate-buffered saline (PBS) in the other two quarters as controls. The rbolL-2 and rboGM-CSF were produced in a yeast expression system, while rbolL-1beta was produced in Escherichia coli. Leucocyte numbers, bactericidal activity of leucocytes, and concentrations of citrate and lactoferrin in quarter secretion samples were monitored after infusion of cytokine or PBS. Infusion of rbolL-2 had minimal effect on leucocyte numbers and concentrations of citrate and lactoferrin. Both rboGM-CSF and rbolL-1beta induced a rapid increase in the number of neutrophils and macrophages compared with control PBS quarters. Concentrations of lactoferrin in secretions were increased by rboGM-CSF and rbolL-1beta compared with control PBS quarters. In addition, infusion of glands with rbolL-1beta lowered the citrate:lactoferrin molar ratio compared with PBS control quarters. The results indicate that intramammary infusion of either rboGM-CSF or rbolL-1beta at cessation of milking immediately increased the number of phagocytic cells in the gland. These cytokines, in particular rbolL-1beta, also increased the rate of mammary gland involution during the early dry period.     

The decerebrate human: associative learning

Phasic changes in cardiac reactivity to innocuous stimuli, presented in a sensory disparity paradigm, were used to evaluate habituation and learning processes in five decerebrate subjects. Three subjects showed systematic changes over trials in the pattern of cardiac response to simple auditory or visual stimuli, indicative of habituation. In addition, tests for associative learning were given after repeated presentations of two paired stimuli. The appearance of a marked cardiac orienting response, to the unpredictable omission of the second stimulus, documented the development of a conditioned association in these same three subjects. One additional subject failed to show a consistent pattern of response to the stimuli, and another demonstrated a consistent response which was not subject to habituation. Overall, these findings support the view that learning processes are not solely the product of the cerebral hemispheres, but reflect general integrative features of the human neuraxis.