Spectral/target activity of short lived radio isotope in pulsed plasma accelerator.
Accelerated deuteron spectra from magnetic spectrometry and graphite bombardment by such deuterons were used to produce short-lived radionuclides in NX2 plasma focus. The experiments show one order of magnitude difference between the activity generated by these techniques. The average activity of NX2 is 5.2 kBq and the highest activity for the best shot is about 40 kBq.
Neutron Yield Scaling With Inductance in Plasma Focus
Neutron yield is enhanced by reduction of the short-circuit plasma focus inductance L<sub>0</sub>, which in turn increases the pinch current I<sub>pinch</sub>. Numerical experiments are carried out to optimize the neutron production using the Lee model on small plasma focus devices (several kilojoules), such as UNU/ICTP PFF, NX2, and LDiana. The maximum neutron yield is obtained for each L<sub>0</sub> with a combination of gas pressure as well as anode length and radius (Y<sub>n</sub> versus z<sub>0</sub>, p<sub>0</sub> and a at fixed L<sub>0</sub>). The numerical experiments confirm the limitation effect of I<sub>pinch</sub>, and suggest an optimum L<sub>0</sub> in the range of 10-20 nH. Finally, the neutron yield is scaled with system inductance.
Thermal stability of reconstituted collagen fibrils. Shrinkage characteristics upon in vitro maturation
Thermal stability measured as area shrinkage without tension during heating was determined for membranes of collagen fibrils reconstituted from solutions of highly purified rat skin collagens. Shrinkage in per cent of area at 25 degrees C and shrinkage temperature were quantitated in a standardized way and determined as a function of in vitro maturation time for 11 to 104 days after aggregation for the collagen membranes. Similar to reports on intact rat skin, shrinkage temperature remained constant and shrinkage per cent declined with a rate decreasing with time during maturation. Solubility in water at 80 degrees C for 2 hours was 95-96% and remained unchanged for the maturation time (about 2 months) studied. The decreased shrinkage reflecting a lower degree of collapse is ascribed to an increasing thermal stability of the membranes during maturation. Development of heat-stable bonds in the reconstituted collagen fibrils is taken up to be amenable to this increased stability. Similarity in changes of shrinkage characteristics during in vivo and in vitro maturation indicates that maturation changes in reconstituted collagen fibrils reflect those occurring in intact collagen during in vivo aging.