Migration of99Tc in unsaturated Chinese loess under artificial rainfall condition: anin situtest

The migration of99Tc in unsaturated Chinese loess under artificial rainfall condition was investigatedin situ. Water suckers were buried at different depths under the bottom of an experimental pit of 2 m × 2 m × 1 m (deep). Quartz containing3H and99Tc was introduced into the experimental pit to an area of 40 cm × 40 cm and the pit was backfilled to a thickness of 30 cm. An artificial rainfall of 5 mm/h was applied to the experimental pit 4 h a day for 3 months. Moisture water samples were sucked with the help of a vacuum pumping system and the activity of3H and99Tc in the samples was determined. Breakthrough curves of3H and99Tc indicated that99Tc was slightly retarded. The calculated average apparent distribution coefficient of99Tc in the medium was (1.98±0.42)×10-2ml/g.

Diffusion of99Tc in granite: A small scale laboratory simulation experiment

The diffusion of99Tc in granite was investigated with small-sized diffusion cells, composed of a radioactive source solution cell and a sampling cell. Water in the two cells was kept at the same level. 1 ml aliquots were taken from the sampling cells daily during the first 50 days, then at intervals of several days, and measured via liquid scintillation counting. The experimental results indicate that the diffusion of99Tc and3H in granite follows the one-dimensional diffusion equation when diffusion time is long enough (>100 days). The calculated average diffusion coefficient of99Tc (1.4×10-12m2/s) is about one half of that of3H (3.2×10-12m2/s).

Regenerative changes in median nerve defects using various rabbit skeletal muscles

We examined the morphological changes of median nerve regeneration which situated to pass through degenerative latissimus dorsi and brachial triceps muscles in rabbits. Morphological observation was performed at 7, 14, 28, 45, 60 and 180 days after the creation of defect of the bilateral median nerves. Regenerative nerve fibers were observed in the residual tubes of left degenerative muscle bridges. In this respect the regenerative effect of the latissimus dorsi was better than that of the brachial triceps. These results suggest that regular and longer muscle fibers as those of latissimus dorsi may contribute to the effective regeneration of nerve.