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Dec 1986

Volume 80, Issue S1, pp. S1-S128

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back to top Session K. Biological Response to Vibration II and Physical Acoustics II: Physical Mechanisms of Biological Effects of Sound and Vibration, Part 2
Contributed Papers
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Acoustic cavitation generated by an extracorporeal shockwave lithotripter (A)

Lawrence A. Crum, Mary Dyson, Andrew J. Coleman, and John E. Saunders

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S24-S24 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Evidence is presented of acoustic cavitation generated by a Dornier extracorporeal shockwave lithotripter. Using x‐ray film, thin aluminum sheets, and relatively thick metal plates as targets, evidence of liquid jet impacts associated with cavitation bubble collapse was observed. The jet impact was violent enough to puncture thin foils and deform metal plates. Furthermore, numerous jet impacts were generated over a volume greater than 200 cm3. It is likely that such violent cavitation will also occur in tissue, and observed biological effects, e.g., renal calculus disintegration and tissue trauma, may be related to cavitation damage. [Work supported in part by the ONR, NIH, NSF, and the Fulbright Commission.]
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Sonoluminescence produced by steady cavitation (A)

D. F. Gaitan

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S24-S24 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Sonoluminescence (SL) is generally attributed to the radiative recombination of hydroxyl free radicals produced by the high temperatures and pressures associated with cavitation bubble collapse. Therapeutic ultrasound systems are known to produce large numbers of free radicals in water and biological fluids and thus present a possible health risk. In an examination of light produced by acoustic standing wave configurations at various frequencies ranging from 20 kHz–1 MHz, steady light emissions have been observed from the cavitation field indicative of violent bubble pulsation rather than cavity collapse. In many cases, multiple flashes occur each cycle, always maintaining a fixed phase with respect to the driving acoustic pressure. This “steady” cavitation is attributed to violent bubble pulsation, and an explanation of this phenomenon will be attempted in terms of numerical studies of bubble dynamics. [Work supported in part by the ONR and the NIH.]
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Transient pulsations of cavitation bubbles (A)

H. G. Flynn and Charles C. Church

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S24-S24 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Transient behavior of small gas bubbles in a liquid set into violent motion by ultrasonic pressure waves is of interest because of widespread use of microsecond pulses in diagnostic ultrasound. Such pulses contain only a few pressure cycles and the transient pulsations of bubbles set in motion by such pulses would determine the bubble‐ultrasound interaction. A computer study has been made to obtain a global representation of the pulsation amplitudes R(t) of small gas bubbles (nulcei) in water during the first few cycles of a cw ultrasonic pressure. One objective was to obtain a better understanding of cavitation phenomena where many nuclei with initial radii from 0.1 to 20 μm are set in motion at pressures ranging from 0.5–5 bars and at frequencies from 0.5–10 MHz. Results allowed construction of surfaces showing the relative bubble amplitude R/Rn, as a function of Rn, and of the time t/TA, where TA is the acoustic period. One finding is that, in the range of peak pressures found in diagnostic pulses, transient cavities would be generated during the first pressure cycle from nuclei with initial radii as small as a few microns (μm). [Research supported by NIH.]
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Direct observation of the forced radial oscillations of single cavitation bubbles (A)

R. G. Holt

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S24-S24 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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The radial response of a bubble in a liquid subject to an acoustic field has long been the object of considerable interest [see, for example, W. Lauterborn, J. Acoust. Soc. Am. 59, 283–293 (1976); B. E. Noltingk and E. A. Neppiras, Proc. Phys. Soc. London Ser. B 63, 674 (1950)]. However, the most often generated graph in these theoretical and numerical studies, the radius‐time (R‐T) curve, has never been experimentally observed until now. The first direct observation of the R‐T response of a single bubble will be presented. The measurements were made on a bubble “levitated” [M. Strasberg, J. Acoust. Soc. Am. 33, 359 (1961)] near the antinode of an acoustic stationary wave by digitizing the output of a photodiode monitoring the intensity of laser light scattered by the bubble. Comparisons will be made with the results of some recent numerical models. [Research supported by ONR.]
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The effect of nonlinear distortion of biomedical ultrasound on acoustic cavitation (A)

Charles C. Church

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S24-S24 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Previous theoretical studies of acoustic cavitation postulated as the driving pressure a Gaussian pulse, a sine wave within a Gaussian envelope, or a pure‐tone sine wave. In this study, the harmonic components of a distorted sine wave are calculated following the method of Blackstock [J. Acoust. Soc. Am. 39, 1019–1026 (1966)]. The magnitudes of these harmonics are attenuated as a function of frequency and distance from the transducer and are summed using a constant phase shift. This produces a waveform quite similar to those seen in the laboratory. Distorted waves produced at 1, 3, 5, and 10 MHz are used to derive Cramer's equations for nonlinear bubble dynamics [Cavitation and Inhomogeneities in Underwater Acoustics, edited by W. Lauterborn (Springer, New York, 1980), pp. 54–63]. Typical bubble radius versus time curves and transient cavitation thresholds (R/Rn, > 2.0) are shown. Due to the shifting of energy from the fundamental to the harmonics and to attenuation, these thresholds are generally higher than for pure sine waves. [Work supported by NIH.]
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Thresholds for eavitation produced in water by pulsed ultrasound (A)

Anthony A. Atchley, Leon A. Frizzell, and Robert E. Apfel

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S25-S25 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Initial results of an experimental investigation of transient cavitation produced by pulsed ultrasound are presented. Water is irradiated with a focused transducer and the subsequent cavitation detected acoustically by a second transducer. The detection technique relies upon the scattering of the irradiation field by the bubble cloud associated with the transient cavitation. A novel feature of the experimental apparatus is a system with which potential cavitation nuclei can be passed directly through the focal region of the irradiation transducer. The threshold for transient cavitation was measured for 1‐ and 2.25‐MHz pulses having durations from a few cycles to 500 μs and repetition frequencies from 50 to 5000 Hz. The data are consistent with, but extend, those of Crum and Fowlkes [Nature 319, 52–54 (1986)] in which sonoluminescence emission was used as the cavitation criterion. The results of the experiment are discussed with regards to the predictions of present theories, in particular, that of Apfel [IEEE UFFC 33, No. 2, 139–142 (1986)]. [Work supported by NIH. AAA acknowledges the support of the F. V. Hunt Postdoctoral Fellowship.]
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Enhancement of protein synthesis by neuroblastoma cells exposed to ultrasound cavitation (A)

Peter D. Edmonds, Pepi Ross, and Ruth M. Yamawaki

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S25-S25 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Enhancement of the cavitational effect of iodine release from sodium iodide solution during repetitive 1‐MHz tone burst excitation of the solution of a rotating test tube has been reported. [V. Ciaravino, H. G. Flynn, and M. W. Miller, Ultrasound Med. Biol. 7, 159–166 (1981)]. This enhancement was attributed to concurrent operation of two mechanisms: depletion of small nuclei from the cw mode size distribution generated during a tone burst, and survival from the previous tone burst of small nuclei lying in the same size range that is depleted in the cw mode. Twenty‐four hours after exposing C1300 neuroblatoma cells (N2A) in rotating tubes to 1‐MHz ultrasound tone bursts [1:1, durations from 6 to 600 ms; 3.4 W/cm2 spatial peak, burst average intensity, and 5 min total treatment duration (on + off periods)] at 37°C, enhancement of protein synthesis compared to control cells was observed. Protein synthesis was measured by uptake of 3H‐leucine. The similarity between results observed for cavitation‐stimulated iodine release and cellular protein synthesis is highly suggestive of cavitation as the cause for this biological effect. [Work supported by PHS.]
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