The formation of free radicals OH and H in a naturally air-saturated aqueous solution exposed to therapeutic CW ultrasound at a frequency of 820 kHz has been confirmed by using spin trapping 5, 5-dimethyl-1-pyrroline-...The formation of free radicals OH and H in a naturally air-saturated aqueous solution exposed to therapeutic CW ultrasound at a frequency of 820 kHz has been confirmed by using spin trapping 5, 5-dimethyl-1-pyrroline-1-oxide ( DMPO ) and electron spin resonance ( ESR) technique . It is suggested that these radicals are formed due to the high temperature and pressure produced by the ultrasonic transient cavitation. The transient cavitation threshold is found at 0. 537-0.632W/cm2 under a sonication time of 3 minutes .With increasing sound intensity the yield of free radicals OH raises rapidly at the intensity ranging from 1-2W/ cm2, and no longer increase is observed at above 3W/cm2. The sound intensity (Ⅰ) dependence of the yield of OH(D) can be approximately described by a regression equation: D = 8.1(I1/2 -Ic1/2 )1/2 where Ic=0. 667W/ cm2 . Under a fixing sound intensity the yield of OH increases monotonously with the sonication time.展开更多
基金The project is supported by Natural Science Foundation of China
文摘The formation of free radicals OH and H in a naturally air-saturated aqueous solution exposed to therapeutic CW ultrasound at a frequency of 820 kHz has been confirmed by using spin trapping 5, 5-dimethyl-1-pyrroline-1-oxide ( DMPO ) and electron spin resonance ( ESR) technique . It is suggested that these radicals are formed due to the high temperature and pressure produced by the ultrasonic transient cavitation. The transient cavitation threshold is found at 0. 537-0.632W/cm2 under a sonication time of 3 minutes .With increasing sound intensity the yield of free radicals OH raises rapidly at the intensity ranging from 1-2W/ cm2, and no longer increase is observed at above 3W/cm2. The sound intensity (Ⅰ) dependence of the yield of OH(D) can be approximately described by a regression equation: D = 8.1(I1/2 -Ic1/2 )1/2 where Ic=0. 667W/ cm2 . Under a fixing sound intensity the yield of OH increases monotonously with the sonication time.
