Studies on the sonic degradation of deoxyribonucleic acid

T7 DNA was partially degraded by x-rays, DNAase, and sonic irradiation. The molecular weight distributions were calculated from sedimentation velocity studies on the resulting preparations. Comparison with the theoretical curve derived by Montroll and Simha showed that the first two degradative methods act grossly at random, whereas sonication is a non-random process resulting in the preferential halving of the DNA molecules in solution.

Functional effects of focused ultrasound on mammalian nerves

Differential blocking of conduction in mammalian nerve fibers has been produced by irradiation of the whole nerve with focused ultrasound. The smallest (C) fibers are the most sensitive; the largest (A-alpha) fibers are the least vulnerable. Fully reversible blocking can be obtained with carefully graded doses of ultrasound.