A specific cavitation phenomenon occurs inside the stems of trees. The internal pressure in tree conduits can drop down to significant negative values, which causes the nucleation of bubbles. The bubbles exhibit high-frequency oscillations just after their nucleation. In the present study, this phenomenon is modeled by taking into account acoustic waves produced by bubble oscillations. A dispersion equation is derived, which is then used to calculate the resonance frequency and the attenuation coefficient of the bubble oscillations. Radiation damping is found to be predominant in comparison with viscous damping, except for very small bubbles. A typical number of oscillation cycles before the complete damping of the oscillation is found to be of the order of 10, as observed for cavitation bubbles in biomimetic synthetic trees.
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http://dx.doi.org/10.1103/PhysRevE.95.053104 | DOI Listing |
ACS Mater Au
January 2025
Department of Biomedical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel.
Gas bubbles, commonly used in medical ultrasound (US), witness advancements with nanobubbles (NB), providing improved capabilities over microbubbles (MB). NBs offer enhanced penetration into capillaries and the ability to extravasate into tumors following systemic injection, alongside prolonged circulation and persistent acoustic contrast. Low-frequency insonation (<1 MHz) with NBs holds great potential in inducing significant bioeffects, making the monitoring of their acoustic response critical to achieving therapeutic goals.
View Article and Find Full Text PDFJ Colloid Interface Sci
December 2024
Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Italy.
Hypothesis: Bubbles oscillating near a free surface are common across numerous systems. Thin liquid films (TLFs) formed between an oscillating bubble and a free surface can exhibit distinct morphological features influenced by interfacial properties, evaporation, and deformation history. We hypothesize that a continuous film presence throughout oscillation results in a wimple morphology, whereas intermittent film presence leads to a dimple formation.
View Article and Find Full Text PDFMicrosyst Nanoeng
December 2024
ECE Department, University of Alberta, 9211-116 St. NW, Edmonton, T6G 1H9, AB, Canada.
Optomechanical sensors provide a platform for probing acoustic/vibrational properties at the micro-scale. Here, we used cavity optomechanical sensors to interrogate the acoustic environment of adjacent air bubbles in water. We report experimental observations of the volume acoustic modes of these bubbles, including both the fundamental Minnaert breathing mode and a family of higher-order modes extending into the megahertz frequency range.
View Article and Find Full Text PDFUltrasonics
December 2024
Department of Biomedical Engineering, School of Life Health Information Science and Engineering, Chongqing University of Posts and Telecommunications, Chongqing, People's Republic of China; Postdoctoral Workstation of Chongqing General Hospital, Chongqing, People's Republic of China. Electronic address:
Submicron ultrasound contrast agents hold great potential to extend the bubble-mediated theranostics beyond the vasculature, but their acoustic response and the interaction effects between them remain poorly understood. This study set out to numerically examine the interaction effects on the subharmonic oscillations of nanobubbles and the resultant acoustic emissions under subharmonic resonance conditions. Results showed that a negative correlation between bubble size and subharmonic resonance frequency is readily obtained from the radius response curves.
View Article and Find Full Text PDFUltrason Sonochem
January 2025
School of Marine Science and Technology, Northwestern Polytechnical University, Xi'an, 710072, Shaanxi, China.
The dynamics of acoustic cavitation bubbles hold significant importance in ultrasonic cleaning, biomedicine, and chemistry. Utilizing an in-situ normal pressure bubble generation and observation system that was developed, this study examined the translational behavior of micrometer-scale normal pressure bubble pairs with initial radius ratio of 1:1 and 2:1 under ultrasonic field excitation. A velocity-distance curve was proposed to quantify the secondary Bjerknes forces during various interaction stages of the bubbles.
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