The effect of coolant loss on current leads for superconducting magnets

In this paper, we have examined the recovery of current leads for superconducting magnets after loss of coolant. It is found that if a lead is without cooling for longer than a time τ_max, thermal runaway can be prevented by an increase in cooling or a decrease in current through the lead. It is evident that designing a lead away from its optimal values can make the lead significantly less susceptible to problems of thermal runaway.     

Safety of single large oral doses of guanethidine

The cardiovascular effects of single 100-mg doses of guanethidine were assessed in hypertensive patients by measurement of arterial pressure, heart rate, and systolic time intervals. In the 3-hr period following a dose there was no evidence of an inotropic effect. Therefore, large doses of guanethidine as required for the guanethidine loading regimen would seem to be safe even in patients in whom inotropic effects of released catecholamines would be contraindicated.     

Influence of nonequilibrium second-phase particles formed during solidification upon the mechanical behavior of an aluminum alloy

The mechanical behavior of a wrought high strength aluminum alloy is examined as a function of the concentration of second-phase microconstituents. These second-phase particles are located in grain boundaries and interdendritic sites. Their concentration was varied by thermal-mechanical processing. In the areas of strengths, ductility, crack toughness, fatigue, and stress corrosion cracking, empirical results are presented and discussed. Observations are made on changes in the anisotropic character of this category of material with lower concentrations of second phases. Formerly Research Advisor, Frankford Arsenal. This paper is based on an invited talk presented at a symposium on Homogenization of Alloys, sponsored by the IMD Heat Treatment Committee, and held on May 11,1970, at the spring meeting of The Metallurgical Society of AIME, in Las Vegas, Nev.     

A proposed system whereby a (colcemid-induced) S2 phase is responsible for the tetraploidy found in cultured human amniotic fluid cells

The results of this study, using cultured amniotic fluid cells (AFC) and colcemid, together with results of several other investigators who worked with colcemid and DNA synthesis, have led to the proposal of a hypothesis suggesting a mechanism by which tetraploidy may be induced. Data from this study of 24,455 mitotic spreads indicate increased concentrations of colcemid, as well as extended exposure times, results in a higher incidence of tetraploidy in cultured AFC, with no concomitant increase in the unexposed control cells.     

The kinetics of the gaseous extraction of gallium from mica

The gaseous reduction of gallium in white mica has been studied using natural gas as the reducing gas. From a study at three temperatures, the initial extraction was observed to be linear with time and independent of particle size. The results suggest that delamination of the mica lattice is important. The measured activation energy for the loss of gallium from the white mica is 184 × 21 kJ mol^?1.