The Forced Bubble

Leighton, T.G.

doi:10.1016/b978-0-12-441920-9.50009-2

Cited by 417 publications

(721 citation statements)

References 143 publications

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“…To isolate different physical mechanisms of bubble activity, spectral energy was integrated within three frequency bands. The first band considered, consisting of the single frequency bin centered at the subharmonic frequency of 1.55 MHz, is sensitive to nonlinear bubble vibrations often associated with stable cavitation activity (Leighton 1994;Yang and Church 2005). Because of the highly narrow-band nature of the subharmonic oscillations and the high frequency resolution of the spectrum measurements, this single bin was sufficient to fully characterize the subharmonic emissions.…”

Section: Data Processingmentioning

confidence: 99%

“…Because of the highly narrow-band nature of the subharmonic oscillations and the high frequency resolution of the spectrum measurements, this single bin was sufficient to fully characterize the subharmonic emissions. The second band, covering frequencies 0.3-1.1 MHz, was chosen to characterize broadband emissions such as those resulting from inertial bubble collapse (Leighton 1994;Yang and Church 2005). This frequency band, well within the known range for acoustic emissions from inertial cavitation (Leighton 1994), was chosen for optimal detector sensitivity and convenience of data acquisition.…”

Section: Data Processingmentioning

confidence: 99%

“…The second band, covering frequencies 0.3-1.1 MHz, was chosen to characterize broadband emissions such as those resulting from inertial bubble collapse (Leighton 1994;Yang and Church 2005). This frequency band, well within the known range for acoustic emissions from inertial cavitation (Leighton 1994), was chosen for optimal detector sensitivity and convenience of data acquisition. The third band, ranging from 10-30 kHz (the three frequency bins of lowest nonzero center frequency), characterizes low-frequency emissions associated with tissue boiling (Osborne and Holland 1947;Ying 1973).…”

Section: Data Processingmentioning

confidence: 99%

See 2 more Smart Citations

Acoustic Emissions During 3.1 MHz Ultrasound Bulk Ablation In Vitro

Mast

Salgaonkar

Karunakaran

et al. 2008

Ultrasound in Medicine & Biology

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Acoustic emissions associated with cavitation and other bubble activity have previously been observed during ultrasound ablation experiments. Since detectable bubble activity may be related to temperature, tissue state, and sonication characteristics, these acoustic emissions are potentially useful for monitoring and control of ultrasound ablation. To investigate these relationships, ultrasound ablation experiments were performed with simultaneous measurements of acoustic emissions, tissue echogenicity, and tissue temperature, on fresh bovine liver. Ex vivo tissue was exposed to 0.9-3.3 s bursts of unfocused, continuous-wave, 3.10 MHz ultrasound from a miniaturized 32-element array, which performed B-scan imaging with the same piezoelectric elements during brief quiescent periods. Exposures employed pressure amplitudes of 0.8-1.4 MPa for exposure times of 6-20 min, sufficient to achieve significant thermal coagulation in all cases. Acoustic emissions received by a 1 MHz, unfocused passive cavitation detector, beamformed Aline signals acquired by the array, and tissue temperature detected by a needle thermocouple were sampled 0.3-1.1 times per second. Tissue echogenicity was quantified by the backscattered echo energy from a fixed region of interest within the treated zone. Acoustic emission levels were quantified from the spectra of signals measured by the passive cavitation detector, including subharmonic signal components at 1.55 MHz, broadband signal components within the band 0.3-1.1 MHz, and low-frequency components within the band 10-30 kHz. Tissue ablation rates, defined as the thermally ablated volumes per unit time, were assessed by quantitative analysis of digitally imaged, macroscopic tissue sections. Correlation analysis was performed among the averaged and time-dependent acoustic emissions in each band considered, B-mode tissue echogenicity, tissue temperature, and ablation rate. Ablation rate correlated significantly with broadband and low-frequency emissions, but was uncorrelated with subharmonic emissions. Subharmonic emissions were found to depend strongly on temperature in a nonlinear manner, with significant emissions occurring within different temperature ranges for each sonication amplitude. These results suggest potential roles for passive detection of acoustic emissions in guidance and control of bulk ultrasound ablation treatments.

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Section: Data Processingmentioning

confidence: 99%

Section: Data Processingmentioning

confidence: 99%

Section: Data Processingmentioning

confidence: 99%

See 1 more Smart Citation

Acoustic Emissions During 3.1 MHz Ultrasound Bulk Ablation In Vitro

Mast

Salgaonkar

Karunakaran

et al. 2008

Ultrasound in Medicine & Biology

View full text Add to dashboard Cite

show abstract

“…A small and thin-wall cell was used in order to minimise the influence of the presence of material (glass) with acoustic impedance different from the acoustic impedance of water (the acoustic impedance of glass is ca. 10-times larger than that of water [27,28] ). The cell was filled with water, so that the level in this immersed cell corresponded to the level of surrounding water.…”

Section: Experimental Verificationmentioning

confidence: 99%

Optimisation of 20 kHz sonoreactor geometry on the basis of numerical simulation of local ultrasonic intensity and qualitative comparison with experimental results

Klíma

Frías-Ferrer

González-Garcı́a

et al. 2007

Ultrasonics Sonochemistry

128

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The intensity distribution of the ultrasonic energy is, after the frequency, the most significant parameter to characterize ultrasonic fields in any sonochemical experiment.Whereas in the case of low intensity ultrasound the measurement of intensity and its distribution is well solved, in the case of high intensity (when cavitation takes place) the measurement is much more complicated. That is why the predicting the acoustic pressure distribution within the cell is desirable.A numerical solution of the wave equation gave the distribution of intensity within the cell. The calculations together with experimental verification have shown that the whole reactor behaves like a resonator and the energy distribution depends strongly on its shape.The agreement between computational simulations and experiments allowed optimisation of the shape of the sonochemical reactor. The optimal geometry resulted in a 2 strong increase in intensity along a large part of the cell. The advantages of such optimised geometry are (i) the ultrasonic power necessary for obtaining cavitation is low, (ii) low power delivered to the system results in only weak heating; consequently no cooling is necessary and (iii) the "active volume" is large, i.e. the fraction of the reactor volume with high intensity is large and is not limited to a vicinity close to the horn tip.

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“…The present reaction is an example of a three-phase system: the liquid phase (reagents in solvents), solid phase (atomized sodium), and the gas phase (dissolved gases in the liquid phase) [28]. Cavitation near extended liquid-solid interfaces is very different from cavitation in pure liquids [29]. Under the influence of ultrasound the bubble collapse becomes non-spherical near the surface of the solid atomized sodium, and near the surface of the vessel, and produces millions of high-speed liquid jets.…”

Section: Effect Of Ultrasound On the Reactionmentioning

confidence: 91%