Effect of ultrasound treatment on solubility and foaming properties of whey protein suspensions

We have used short laser pulses to generate transient vapor nanobubbles around plasmonic nanoparticles. The photothermal, mechanical, and optical properties of such bubbles were found to be different from those of plasmonic nanoparticle and vapor bubbles, as well. This phenomenon was considered as a new complex nanosystem—plasmonic nanobubble (PNB). Mechanical and optical scattering properties of PNB depended upon the nanoparticle surface and heat capacity, clusterization state, and the optical pulse length. The generation of the PNB required much higher laser pulse fluence thresholds than the explosive boiling level and was characterized by the relatively high lower threshold of the minimal size (lifetime) of PNB. Optical scattering by PNB and its diameter (measured as the lifetime) has been varied with the fluence of laser pulse, and this has demonstrated the tunable nature of PNB.

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Plasmonic nanobubbles as transient vapor nanobubbles generated around plasmonic nanoparticles.

Effect of ultrasound treatment on particle size and molecular weight of whey proteins

The ability of ultrasound to produce highly controlled tissue erosion was investigated. This study is motivated by the need to develop a noninvasive procedure to perforate the neonatal atrial septum as the first step in treatment of hypoplastic left heart syndrome. A total of 232 holes were generated in 40 pieces of excised porcine atrial wall by a 788 kHz single-element transducer. The effects of various parameters [e.g., pulse repetition frequency (PRF), pulse duration (PD), and gas content of liquid] on the erosion rate and energy efficiency were explored. An Isppa of 9000 W/cm/sup 2/, PDs of 3, 6, 12, and 24 cycles; PRFs between 1.34 kHz and 66.7 kHz; and gas saturation of 40-55% and 79-85% were used. The results show that very short pulses delivered at certain PRFs could maximize the erosion rate and energy efficiency. We show that well-defined perforations can be precisely located in the atrial wall through the controlled ultrasound tissue erosion (CUTE) process. A preliminary in vivo experiment was conducted on a canine subject, and the atrial septum was perforated using CUTE.

/pdf/controlled-ultrasound-tissue-erosion-75nuguzmqd.pdf

Controlled ultrasound tissue erosion

The conversion of lignocellulosic biomass for biofuels and biorefinery applications is limited due to the cost of pretreatment to separate or access the biomass’s three main usable components, cellulose, hemicellulose, and lignin. After pretreatment, each component may be utilized via chemical conversion, hydrolysis, and/or fermentation. In this review we aim first, to identify the current status-quo of knowledge of the parametric effects of ultrasound, second, to evaluate the potential of ultrasound as a pretreatment and fractionation method of lignocellulose, and last, to identify the challenges that this technology faces. Ultrasound produces chemical and physical effects which were both found to augment the pretreatment of lignocellulose via delignification and surface erosion. The magnitudes of these effects are altered when the ultrasonic field is influenced by parameters such as solvent, ultrasonic frequency, and reactor geometry and type. Therefore, the implementation of ultrasound for the pretreat...

Effect of Ultrasound on Lignocellulosic Biomass as a Pretreatment for Biorefinery and Biofuel Applications

Sonochemiluminescence (SCL) of luminol due to a single bubble is studied through spectral measurement. No SCL was observed from a stable single bubble that emitted high-intensity sonoluminescence (SL). In contrast, SCL was observed under conditions of an unstable dancing bubble, where a bubble grows and ejects tiny bubbles, making it "dance" by counteraction. Furthermore, SCL was observed from dancing bubbles even when SL was not observed, depending on the dissolved gas content. The instability of bubble collapse is the key parameter governing SCL.

Single-bubble sonochemiluminescence in aqueous luminol solutions.

Influence of bubble clustering on multibubble sonoluminescence.

Decrease in luminous intensity of multibubble sonoluminescence (MBSL) at excessive ultrasonic intensity is studied in connection with the behavior of cavitation bubbles. The intensity of MBSL from aerated distilled water in a rectangular vessel with six transducers, in which a standing wave field was established, was measured while the voltage applied to the transducers was increased. The corresponding change in the distribution of cavitation bubbles in the field was observed. The distributions of bubbles were compared with those of MBSL using an intesified charge-coupled device (ICCD) camera, and the bubble motion was observed with a high-speed camera. It is clarified that the expulsion of bubbles from the pressure antinode in the field is responsible for the decrease in MBSL intensity at high ultrasonic intensity. The expulsion is caused by the primary Bjerknes force which changes from an attractive force to a repulsive one depending on pressure amplitude and bubble radius, assisted by coalescence of bubbles due to the secondary Bjerknes force.

https://iopscience.iop.org/article/10.1143/JJAP.40.3856/pdf

Quenching Mechanism of Multibubble Sonoluminescence at Excessive Sound Pressure

The difference in threshold between sonoluminescence (SL) and sonochemical luminescence (SCL) has been investigated. The intensity of both SL from distilled water and SCL from a luminol solution in a rectangular glass cell was measured while changing the driving frequency and voltage applied to the transducer. The second hamonic component of the sound-pressure waveform was also measured simultaneously. The results show that the thresholds in sound pressure become higher for cavitation, SCL and SL in this order. As the dissolved gas in a liquid decreases, the SCL intensity decreases but the SL intensity increases. For a constant quantity of dissolved gas, as the liquid temperature becomes higher, the SCL intensity increases but the SL intensity decreases. In the case of air-saturated liquids, the difference in threshold between SCL and SL becomes larger as the liquid temperature increases. The dependence of the ratio of SCL to SL on temperature is similar to that of vapor pressure.

Shin-ichi Hatanaka

Papers

Single-bubble sonochemiluminescence in aqueous luminol solutions.

Influence of bubble clustering on multibubble sonoluminescence.

Quenching Mechanism of Multibubble Sonoluminescence at Excessive Sound Pressure

Difference in Threshold between Sono- and Sonochemical Luminescence

Multibubble sonoluminescence enhancement by fluid flow