Multiarc Generator
A multiarc generator, comprised of stacked metal contact disks, has been tested. Arc formation occurred in the gaps between each cylindrically shaped contact piece during 3-to 30-kA discharges through various stacked disk configurations. Severe current limiting was demonstrated by stacked disks whose axial length was less than their diameter. Current extinction time periods for discharges through the stacked disks were as much as 80 percent less than those measured for similar amplitude discharges through a solid metal rod. The energy dissipated per gap by arcing was calculated and found to increase as contact disk mass decreased. The i2dt action integral calculated for 3- to 12-kA discharges ranged from 53 A2s to 4210 A2s, respectively. The multiarc formation process is attributed to longitudinal electrodynamic forces separating the contact disks during current discharge.
CORRELATED X-RAY AND OPTICAL STREAK PHOTOGRAPHS OF EXPLODING WIRES,
Sequences of flash x-ray photographs of 70 nsec-duration obtained during the early expansion of copper, lead, and iron wires are correlated precisely in time with the electrical voltage pulse and optical streak photographs. Wire sizes were 10, 15, and 25 mil in diameter. The x-ray pictures show the onset and development of striations in each of these metals along the wire length during the fast resistance rise of the wire. The relatively smooth envelope of the radially expanding striations is compared with features of the optical streak pictures. Some of these optical pictures show a translucent radial cloud developing prior to the fast resistance rise, and a more opaque inner core which expands radially. Most of the striations in the x-ray pictures appear to be completely separated at the voltage maximum. After the voltage peak, the density of material appears to be greater further from the center. The observed behavior is discussed.
Evaluation of antioxidants by a rapid polarographic method
A simple, rapid, precise, and reproducible method and an adaptable apparatus for polarographic measurement of lipid peroxidation and antioxidant activity is described. This method measures antioxidant activity within a few min time as compared to the hours or days needed for several widely used methods. Peroxidation rates were measured for different lipids as a function of amount of lipid, and amount of biocatalyst. The method is applicable to the detection and measurement of the antioxidant effects exhibited by weak antioxidants and has been satisfactorily used for the measurement of the antioxidant activity of different concentrations of powerful antioxidants.