Acoustic cavitation, characterized by the nucleation, growth, and collapse of cavitation bubbles under ultrasound irradiation, is a fundamental mechanism for therapeutic ultrasound, including high intensity focused ultrasound therapy and sonodynamic therapy (SDT). In this study, a hierarchical acoustic signal analysis was carried out to systematically evaluate how engineered silica nanoparticles (SiO2 NPs) regulate cavitation onset, bubble growth, and oscillation stability. Specifically, cavitation thresholds were determined using the third harmonic signal, and calibrated to acoustic intensity (ISPTA) to assess clinical safety. Our results demonstrate that nanoparticles facilitate bubble nucleation in a size-dependent manner, with maximal enhancement observed at ∼ 100 nm under 840 kHz ultrasound sonication. Structurally, hollow mesoporous silica nanoparticles (HMSNs) induced the most intense cavitation with the lowest threshold of 0.56 W/cm2, significantly below the FDA safety limit (3 W/cm2). Furthermore, we propose a unified concave-convex curvature theory to elucidate these phenomena: hydrophobic modifications and hollow architectures create effective concave interfaces that stabilize gas nuclei, drastically lowering the nucleation barrier compared to convex hydrophilic spheres. These findings provide quantitative mechanistic insights into nanoparticle-mediated cavitation and establish key design principles for ultrasound-responsive nanoplatforms that enable effective therapy within clinically safe energy levels.
Efficient operation of light-to-pressure transducers and flexible fabrication on demand are key factors for the use of photoacoustic devices in various biomedical disciplines. Graphene layers can be grown at wafer scale and transferred to any surface geometry, providing a versatile approach for the development of photoacoustic emitters with a large and nearly uniform thermal interface. Here we report the picosecond excitation of a photoacoustic emitter consisting of a large-area, 10-layer graphene grown by chemical vapour deposition and encapsulated with a polydimethylsiloxane. The theoretical and experimental studies address the generation of broadband ultrasounds upon excitation with nanosecond and picosecond laser pulses, showing how the multilayer graphene can serve as an ultrafast nanoheater to drive efficient expansion of the adjacent polymer layer in the picosecond regime. The picosecond excitation results in a sharper acoustic waveform, and the pressure evolution time is twice as short with a 30 ps excitation as with a 6 ns pulse, thus satisfying the thermal and stress confinement conditions, while energy loss occurs with nanosecond excitation. We experimentally observed that the 10-layer graphene/polydimethylsiloxane generates a high-frequency photoacoustic wave with a bandwidth of about 110 MHz at −6 dB, increasing to 250 MHz at −20 dB, due to stress confinement, increased thermal interface, and ultrafast dynamics. The peak pressure of 0.85 MPa in 3.4 nm thick graphene multilayers (∼20 % absorption of 40 mJ cm–2) is remarkably high, demonstrating its potential as a photoacoustic material and the advantages of combining picosecond excitation with large-area graphene in wave transmission technologies.
Sargassum fusiforme is a medicinal and edible species present in China, Korea, and Japan, and its phlorotannins are considered valuable bioactive components. Response surface methodology (RSM) and a support vector machine integrated with a genetic algorithm (SVM–GA) were used in this study to optimize ultrasonic-assisted extraction (UAE) of S. fusiforme phlorotannins (SFP), to compare its efficiency with convenient water bath extraction and ultrasonic-assisted enzymatic extraction, and to conduct pilot-scale experiments. Furthermore, this study explored the effect of ultrasound treatment on the adsorption and desorption efficiency of SFP using macroporous resins. The findings indicated that the optimization performance of the SVM–GA model was superior to that of RSM, and the following optimal UAE conditions were identified: 75 min extraction time, 70 ℃ extraction temperature, 20 mL/g liquid–solid ratio, 30% ethanol concentration, and 320 W ultrasonic power. Under these conditions, a total phlorotannin content of 0.52 ± 0.021 mg phloroglucinol equivalents/g and a total phenolic content of 3.42 ± 0.071 mg gallic acid equivalents/g were obtained. Macroporous adsorption resin purification experiments revealed that HPD600 was one of the most effective resins for SFP purification. At the selected ultrasonic intensity of 65 W, ultrasound enhanced the adsorption and desorption capacities of SFP on HPD600 resin owing to increased hydrogen bond formation on the resin surface and surface roughness. Furthermore, the adsorption of SFP could be well described using the pseudo-second-order model and the Freundlich model. Conventional shaking-assisted HPD600-purified sample (SFP-SA) and ultrasonic-assisted HPD600-purified sample (SFP-UA) were selected to investigate the antioxidant and anti-neuroinflammatory activities. In addition, a total of 8 types of phlorotannin tentatively identified by ultra-performance liquid chromatography–quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS). This method is expected to be effective for extracting and purifying SFP, and the findings highlight its promising antioxidant and anti-neuroinflammatory properties, suggesting broad applications across the functional food industry.
Auricularia auricula-judae is a widely cultivated mushroom species known for its edible and medicinal properties. Polysaccharides have been the focus of research because of their potential bioactivities; nonetheless, the structural complexity and molecular weight have hindered a complete understanding of their bioactivities. In this study, AP-1 polysaccharide was isolated from A. auricula-judae and subjected to ultrasonic degradation at different time points to improve their anti-inflammatory effects. The results showed that when AP-1 was degraded for 9 min (AP-2) and 20 min (AP-3), the NO inhibition rate was significantly increased in LPS-stimulated RAW 264.7 cells. The structural and physiochemical properties of native and degraded polysaccharides were analyzed, and it was found that the degradation process significantly reduced molecular weight and altered the particle size, viscosity, crystallinity, and helical structure. Furthermore, native and degraded polysaccharides (AP-1, AP-2, and AP-3) anti-inflammatory effects were investigated in the DSS-induced colitis mouse model. Degraded polysaccharides resulted in significant improvements, including recovery from weight loss, reduced disease activity, shortened colon length, and decreased inflammation, while AP-3 showed the most promising effects. Gut microbiota 16S rRNA sequencing revealed that AP-3 potentially increases healthy gut microbiota and inhibits unhealthy gut microbiota. Overall, this study demonstrates that ultrasonic degradation could be a great technique to modify polysaccharides’ MW and physiochemical properties to improve anti-inflammatory and gut microbiota regulatory effects.
Meththa Ranasinghe, Constantinos Stathopoulos, Balan Sundarakani
et al.
In the present study, non-conventional and green technology (ultrasonication) was utilized to recover bioactive compounds from the small, medium and large sized defatted date seed powder (DDSP) particles. Bioactive compounds recovered from DDSP and the remaining fiber-rich residue were incorporated as functional ingredient in the biscuit dough to enhance the functionality and the quality characteristics of the dough and biscuit. The polyphenolic extract and 2.5 %, 5 % and 7.5 % substitution levels of fiber-rich extraction residue were incorporated in formulations followed by investigating the effect on rheological, physical and microstructural properties of dough and biscuit. Loss and storage moduli, G’’ and G’, respectively, of dough increased with decreasing particle size and increasing substitution level while tan δ decreased with increasing substitution level of fiber-rich extraction residue. The smallest particles at 7.5 % substitution level resulted in the lowest creep strain value in dough. Hardness of the dough and biscuit increased with decreasing particle size and increasing substitution level of the residue. The 7.5 % substitution level of the smallest particle size resulted in the darkest dough and biscuit. Spread ratio and diameter of the biscuit decreased with increasing substitution level of the residue. The smallest diameter of 50.61 mm and spread ratio of 8.36 was observed in the biscuits substituted with the largest particle size with 7.5 % substitution level. Microstructural images of dough and biscuit revealed that the continuity of the gluten network was disrupted by the incorporation of the fiber-rich extraction residue. This study provided valuable insights into extracting bioactive components from date by-products using green ultrasonication technique and utilizing such compounds to improve functional attributes of bakery products, as a sustainable approach for valorizing date by-products.
Sound absorption is important for room acoustics and remediation of noise. Acoustic metamaterials have recently emerged as one of the most promising platforms for sound absorption. However, the working bandwidth is severely limited because of the strong dispersion in the spectrum caused by local resonance. Utilizing the coupling effect among resonators can improve the absorbers' performance, but the requirement of collecting coupling effects among all resonators, not only the nearest-neighbor coupling, makes the system too complex to explore analytically. This Letter describes deep learning based acoustic metamaterials for achieving broadband sound absorption with no visible oscillation in a targeted frequency band. We numerically and experimentally achieve an average absorption coefficient larger than 97% within the ultra-broadband extending from 860 to 8000 Hz, proving the validity of the deep learning based acoustic metamaterials. The excellent ultra-broadband and near-perfect absorption performance allows the absorber for versatile applications in noise-control engineering and room acoustics. Our work also reveals the significance of modulating coupling effects among resonators, and the deep learning approach may blaze a trail in the design strategy of acoustic functional devices.
To investigate the energy partitioning up to the fourth oscillation of a millimeter-scale spherical cavitation bubble induced by laser, we used nanosecond laser pulses to generate highly spherical cavitation bubbles and shadowgraphs to measure the radius-time curve. Using the extended Gilmore model and considering the continuous condensation of the vapor in the bubble, the time evolution of the bubble radius, bubble wall velocity, and pressure in the bubble is calculated till the 4th oscillation. Using Kirkwood-Bethe hypothesis, the evolution of velocity and pressure of shock wave at the optical breakdown, the first and second collapses are calculated. The shock wave energy at the breakdown and bubble collapse is directly calculated by numerical method. We found the simulated radius-time curve fits well with experimental data for the first four oscillations. The energy partition at the breakdown is the same as that in previous studies, the ratio of shock wave energy to bubble energy is about 2:1. In the first collapse and the second collapse, the ratio of shock wave energy to bubble energy is 14.54:1 and 2.81:1 respectively. In the third and fourth collapses, the ratio is less, namely than 1.5:1 and 0.42:1 respectively. The formation mechanism of the shock wave at the collapse is analyzed. The breakdown shock wave is mainly driven by the expansion of the supercritical liquid resulting from the thermalization of the energy of the free electrons in the plasma, and the collapse shock wave is mainly driven by the compressed liquid around the bubble.
“Schroeder diffuser” is a classical design, proposed over 40 years ago, for artificially creating optimal and predictable sound diffuse reflection. It has been widely adopted in architectural acoustics, and it has also shown substantial potential in noise control, ultrasound imaging, microparticle manipulation et al. The conventional Schroeder diffuser, however, has a considerable thickness on the order of one wavelength, severely impeding its applications for low-frequency sound. In this paper, a new class of ultrathin and planar Schroeder diffusers are proposed based on the concept of an acoustic metasurface. Both numerical and experimental results demonstrate satisfactory sound diffuse reflection produced from the metasurface-based Schroeder diffuser despite it being approximately 1 order of magnitude thinner than the conventional one. The proposed design not only offers promising building blocks with great potential to profoundly impact architectural acoustics and related fields, but it also constitutes a major step towards real-world applications of acoustic metasurfaces. DOI:https://doi.org/10.1103/PhysRevX.7.021034 Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Published by the American Physical Society
Existing approaches to reducing the low-frequency noise exposure of dwellings are not always sufficient. This study investigated the significance of dwelling layout design for low-frequency noise control. The sound distribution in six typical Chinese dwelling layouts was analysed using in-situ measurements under steady-state noise of various low frequencies. The results showed that among two-bedroom dwelling layouts, the overall average noise reduction varied considerably (6 dB). The noise reduction for room levels (number of rooms sound crosses) 1–2 and 2–3 varies by 5 and 3 dB, respectively, and the noise reduction at door openings varies by 5 dB. A model to approximate the low-frequency noise reduction of a layout was developed using the polyline distance from the noise source and the number of walls the polyline has to cross, which were clearly shown to influence low-frequency noise reduction and seem to be the strongest investigated factors.
Control engineering systems. Automatic machinery (General), Acoustics. Sound
Blade crack will cause severe mistuning of hard-coated blisks, which will lead to vibration localization. To identify crack mistuning and analyze influence factors, in this study, a mistuning identification method of blade cracks in hard-coated blisks is presented based on modified component mode mistuning reduced-order model, in which the hard-coated blisk with blade crack is decomposed into a substructure of tuned hard-coated blisk and a substructure of coated blade with cracks. Crack mistuning of each coated blade can be obtained by a single identification calculation. After verifying the rationality of this identification method, the influence factors of blade crack mistuning are analyzed. The influence factors include the crack location on the coated blade (cracks occurring only in coating or only in blade substrate or both in blade substrate and coating), crack length, crack position in the radial direction of the blisk, and modal data type of coated blisk used for mistuning identification calculation. The research results show that, with the increase of crack length, the mistuning of crack occurring only in the coating does not increase continuously but decreases firstly and then increases. For the first bending modes, the closer the blade crack is to the blade root, the larger the mistuning is. For the second bending modes, the blade crack located at the position of maximum modal displacement will produce large mistuning. For hard-coated blisk with blade crack, these crack mistuning variation rules are of great significance to the dynamic analysis and the determination of the crack location.
Control engineering systems. Automatic machinery (General), Acoustics. Sound
Whitney L. Coyle, Evangelina Y. Wong, Jack D. Gabriel
et al.
This study offers a metric to investigate transition times between articulated notes for reed instruments such as clarinets and bass clarinets. The method requires analysis of measurements of musician mouthpiece pressure. For this paper, the data were recorded using sensor-equipped mouthpieces made for the clarinet and bass clarinet. The method leads to a metric called the transition time (ΔT), which allows for comparing duration measured between notes for clarinets played in different musical contexts (dynamics, tempos, etc.) and playing regimes and between players.
The technique of sound insulation has a wide range of potential applications in environment noise control and architectural acoustics. The rapid development of acoustic artificial materials has provided alternative solutions to design sound insulation structures. However, the realization of single-layer planar structures with bidirectional acoustic insulation (BAI) and unidirectional acoustic insulation (UAI) still poses a challenge. Here, we report the theoretical and experimental realization of two types of single-layer phased array lenses which presents the characteristics of broadband BAI and multi-channel UAI. Both types of lenses consist of 12 mode-conversion phased units which are composed of two types of unit cells (I and II) with an opposite phase and a step waveguide. Based on the phase regulation, the designed phased unit can realize the mode conversion between the zero-order and first-order waves and asymmetric sound manipulation, which enables multi-functional sound insulations. Based on the desired theoretical phase profiles, two types of lenses with BAI and UAI are realized for the incidence of the zero-order wave, and their fractional bandwidths can reach about 0.28 and 0.37, respectively. More interestingly, the UAI effect can be reversed for the incidence of the first-order wave. The proposed lenses based on the mode-conversion phased units have the advantages of single-layer planar structure, multi-functional sound insulation, and broad bandwidth, which have wide application prospect.
The Aselliscus Stoliczkanus bat, studied here, has intricately shaped structures surrounding the nostrils. These structures are hypothesised to have influence on animals’ acoustic radiation patterns. Using micro-tomography scanning technique, a 3D digital model of the noseleaf is reconstructed and biosonar beam pattern is analysed using a finite element method based on the 3D noseleaf model. The present research focuses on the conspicuous furrows in noseleaf, and our analysis allows to conclude the followings: a) structural details in noseleaf of Aselliscus Stoliczkanus bat can produce acoustic effects even if it is not adjacent to the nostrils, b) the furrows possess frequency-selective characteristics, c) the furrows have the function to manipulate the direction and width of the outgoing ultrasound wave.