Enhancement of ultrasonic cavitation yield by multi-frequency sonication

We study the overdamped version of two coupled anharmonic oscillators under the influence of both low-and high-frequency forces respectively and a Gaussian noise term added to one of the two state variables of the system. The dynamics of the system is first studied in the presence of both forces separately without noise. In the presence of only one of the forces, no resonance behaviour is observed, however, hysteresis happens there. Then the influence of the high-frequency force in the presence of a low-frequency, i.e. biharmonic forcing, is studied. Vibrational resonance is found to occur when the amplitude of the high-frequency force is varied. The resonance curve resembles a stochastic resonance-like curve. It is maximum at the value of g at which the orbit lies in one well during one half of the drive cycle of the low-frequency force and in the other for the remaining half cycle. Vibrational resonance is characterized using the response amplitude and mean residence time. We show the occurrence of stochastic resonance behaviour in the overdamped system by replacing the high-frequency force by Gaussian noise. Similarities and differences between both types of resonance are presented.

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“…Practical importance especially in medicine of a high-frequency force has been reported [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Vibrational and stochastic resonances in two coupled overdamped anharmonic oscillators

Gandhimathi

Rajasekar

Kurths³

2006

Physics Letters A

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“…The CD spectra of zein (0.2 mg/mL in 60% ethanol) were assessed at a wavelength range of 190-250 nm with a Jasco J-715 CD spectropolarimeter (Jasco Corp., Tokyo, Japan) using a quartz cuvette with a 10-mm optical path length under nitrogen flux at a temperature of 25 ∘ C, scanning rate of 50 nm/min, and bandwidth of 1.0 nm. The content of the protein secondary structure was calculated from the far-UV CD spectra using the DICHROWEB procedure [18][19][20][21][22].…”

Section: Circular Dichroism (Cd)mentioning

confidence: 99%

Effects of Different Working Modes of Ultrasound on Structural Characteristics of Zein and ACE Inhibitory Activity of Hydrolysates

Ren

Zhang

Liang

et al. 2017

Journal of Food Quality

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Ultrasound was used as a new technology to pretreat protein prior to proteolysis to improve enzymolysis efficiency. The effects of different working modes of ultrasound on the angiotensin I-converting enzyme (ACE) inhibitory activity of zein hydrolysates and the structural characteristics of zein were investigated. The solubility, surface hydrophobicity ( 0 ), ultraviolet-visible (UV-Vis) spectra, intrinsic fluorescence spectra, and circular dichroism (CD) spectra of zein pretreated with ultrasound were determined. All ultrasound pretreatments significantly improved the ACE inhibitory activity of zein hydrolysates ( < 0.05). The highest ACE inhibitory activity, representing an increase of 99.21% over the control, was obtained with dual sweeping frequency ultrasound of 33 ± 2 and 68 ± 2 kHz. The effects of single sweeping frequency and dual fixed frequency ultrasound were stronger than those of single fixed frequency ultrasound for improving the ACE inhibitory activity of zein. Structural changes in zein were induced by ultrasound, as confirmed by changes in the solubility, 0 , UV-Vis spectra, intrinsic fluorescence spectra, and CD spectra of zein, and these were consistent with the corresponding ACE inhibitory activities of zein hydrolysates. Thus, ultrasound working mode and frequency have significant effects on the structure of zein and the ACE inhibitory activity of zein hydrolysates.

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“…A comparison of two studies, Entezari and Kruus (1996) performed at 20 and 900 kHz and Seymour et al (1997) at 640 kHz, showed a higher cavitation yield at sonication frequency of 640 kHz compared to 20 and 900 kHz. Furthermore, a study by Feng et al (2002) reported that when using the low MHz frequency range, the lower the frequency used, the higher the cavitation yield. They observed that the sound intensity of low MHz frequency ultrasound is above 6 W cm -2 , and the cavitation yield of the combined irradiation (0.87 MHz and 28 kHz) is more than 1.6 times of that of combined irradiation using a higher MHz frequency (1.7 MHz and 28 kHz).…”

Section: Effect Of Sonication Frequencymentioning

confidence: 99%

Towards the development of cavitation technology for upgrading bitumen: Viscosity change and chemical cavitation yield measurements

Kirpalani

Mohapatra

2017

Pet. Sci.

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Among the different methods used for reducing viscosity of bitumen, acoustic cavitation during sonication is well recognised. Several chemical methods were used to detect the production of reactive species such as hydroxyl radicals and hydrogen peroxide during acoustic cavitation processes. However, quantification of cavitation yield in sonochemical systems is generally limited to low frequencies and has not been applied to bitumen processing. An empirical determination of the cavitation yield in midto high-frequency range (378, 574, 850, 992, and 1173 kHz) was carried out by measuring the amount of iodine liberated from the oxidation of potassium iodide (KI). Further, cavitation yield and the effects of different sonic operating conditions such as power input (16.67%-83.33%) and solute concentration on cavitation yield were carried out in KI solution and sodium carboxymethyl cellulose-water mixture to obtain benchmark changes in rheology and chemistry using these two model fluids. The findings were then applied to bitumen upgrading through sonication. Through this study, it was found that the chemical cavitation yield peaked with a sonication frequency of 574 kHz. It was also found that cavitation yield and viscosity change were correlated directly in bitumen and a 38% lower bitumen viscosity could be obtained by acoustic cavitation.

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Enhancement of ultrasonic cavitation yield by multi-frequency sonication

Cited by 259 publications

References 8 publications

Vibrational and stochastic resonances in two coupled overdamped anharmonic oscillators

Vibrational and stochastic resonances in two coupled overdamped anharmonic oscillators

Effects of Different Working Modes of Ultrasound on Structural Characteristics of Zein and ACE Inhibitory Activity of Hydrolysates

Towards the development of cavitation technology for upgrading bitumen: Viscosity change and chemical cavitation yield measurements

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