226 Destructive Effects of High Intensity Ultrasound /I2 : 4 



4. Cellular Fragilities and Resonances 



Biological cells such as protozoans, bacteria, algae, yeast, white blood 

 cells, and red blood cells are destroyed in cavitating acoustic fields. 



(a) 



(b) 

 Figure 2. (a) Electron photomicrographs of Saccharomyces 

 cerevisiae, unexposed cells illustrated on left. Cells exposed to 

 9 kc magnetostriction oscillator, illustrated on the right, show 

 fragmented cells, some in which end has been broken, and some 

 intact cells exhibiting marked irregularity in density, (b) Electron 

 photomicrographs of Escherichia coli, strain B. Unexposed cells 

 illustrated on left. Cells exposed to sound field, illustrated on 

 the right, show increased debris and fragmented cells. After 

 H. Kinsloe, E. Ackerman, and J. J. Reid, "Exposure of 

 Microorganisms to Measured Sound Fields," J. Bacteriology 68: 

 373 (1954). 



The rate of destruction can be altered by a number of physical factors. 

 Anything tending to decrease or suppress cavitation tends to protect the 



