Ultrasound Power Level Research Articles

Application of High Intensity Ultrasound to a Zero‐trans Shortening During Temperature Cycling at Different Cooling Rates

AbstractThe objective of this work was to evaluate the effect of high intensity ultrasound (HIU) on the physical properties of a commercial shortening crystallized at a constant temperature and during temperature cycling at two different cooling rates (0.5 and 1 °C/min). Different ultrasound power levels and different durations were evaluated during crystallization at a constant temperature and the best conditions were used to evaluate the effect of HIU during temperature cycling. The physical properties tested were crystal microstructure, viscoelasticity, and melting profile. Results show that HIU is more efficient at changing crystal microstructure when used at 20 °C using a 1/2″ tip. No difference was found on the microstructure of the crystals formed when different durations of ultrasound exposure were tested. A significant increase (p < 0.05) was observed in the storage modulus (G′) of the lipid exposed to temperature fluctuations with the use of HIU. The G′ values increased from 662.6 ± 176.8 Pa (no HIU applied) to 3,365.5 ± 426.4 Pa (with HIU applied, 0.5 °C/min) and from 354.4 ± 49.7 Pa (no HIU applied) to 1,249.0 ± 19.8 Pa (with HIU applied, 1 °C/min).

Effect of power ultrasound pretreatment on peptidic profiles and angiotensin converting enzyme inhibition of milk protein concentrate hydrolysates

The use of power ultrasound as a pretreatment to enhance the hydrolysis of milk protein concentrate (MPC) and subsequent angiotensin converting enzyme (ACE) inhibitory activity has been studied. Liquid chromatography was used to analyse peptide profiles of Neutrase-derived MPC hydrolysates after pretreatment at 0, 1, 3, 5 and 8 min at an ultrasound power level of 800 W. The peptide profiles indicated an increase in number of peptides when ultrasound pretreatment was applied. There was also an increase in the degree of hydrolysis of MPC hydrolysates. The profiles indicated that new small peptides in ultrasound pretreated samples (1-5 min) which were not present in the control samples and 8 min pretreated samples, could be responsible for increased ACE inhibitory activity. These small peptides were digested in the 8 min pretreated samples. Ultrasound pretreatment of MPC increases the ACE inhibitory activity of the hydrolysates because of the production of new small peptides. This can be used as a means to derive potent ACE inhibitory peptides at industrial scale in complex protein sources.

Study and optimization of the ultrasound-enhanced cleaning of an ultrafiltration ceramic membrane through a combined experimental–statistical approach

Membrane fouling is one of the main drawbacks of ultrafiltration technology during the treatment of dye-containing effluents. Therefore, the optimization of the membrane cleaning procedure is essential to improve the overall efficiency. In this work, a study of the factors affecting the ultrasound-assisted cleaning of an ultrafiltration ceramic membrane fouled by dye particles was carried out. The effect of transmembrane pressure (0.5, 1.5, 2.5bar), cross-flow velocity (1, 2, 3ms−1), ultrasound power level (40%, 70%, 100%) and ultrasound frequency mode (37, 80kHz and mixed wave) on the cleaning efficiency was evaluated. The lowest frequency showed better results, although the best cleaning performance was obtained using the mixed wave mode.A Box–Behnken Design was used to find the optimal conditions for the cleaning procedure through a response surface study. The optimal operating conditions leading to the maximum cleaning efficiency predicted (32.19%) were found to be 1.1bar, 3ms−1 and 100% of power level.Finally, the optimized response was compared to the efficiency of a chemical cleaning with NaOH solution, with and without the use of ultrasound. By using NaOH, cleaning efficiency nearly triples, and it improves up to 25% by adding ultrasound.

Effect of Ultrasound Pretreatment on Vacuum Drying of Chinese Catalpa Wood

Ultrasound pretreatment of wood prior to drying was examined as a method to increase the effective water diffusivity, reduce drying time, and improve product quality of Chinese Catalpa wood. Pretreatment tests were carried out at three pretreatment durations, three absolute pressure levels, and three ultrasonic intensities. All specimens were then dried at 60°C and the absolute pressure level of 0.02 MPa to determine the effects of pretreatment parameters on vacuum drying characteristics. A microscopic analysis was carried out to visualize the formation of microchannels and view any other changes to wood tissue structure that occurred. Results showed that ultrasound pretreatment prior to vacuum drying enhances the effective water diffusivity; the higher the ultrasound power level, the longer the pretreatment time, and the lower the absolute pressure, the shorter is the drying time. Ultrasound creates micro channels within the tissue of wood during pretreatment. However, the pretreatment time should not be too long when the ultrasound is high.

Evaluation of a Novel Solid-State Method for Determining the Acoustic Power Generated by Physiotherapy Ultrasound Transducers

Abstract A new secondary method of determining ultrasound power is presented based on the pyroelectricity of a thin membrane of the piezoelectric polymer, polyvinylidene fluoride (PVDF). In operation, the membrane is backed by a polyurethane-based rubber material that is extremely attenuating to ultrasound, resulting in the majority of the acoustic power applied to the PVDF being absorbed within a short distance of the membrane-backing interface. The resulting rapid heating leads to a pyroelectric voltage being generated across the electrodes of the sensor that, under appropriate conditions, is related to the rate of change of temperature with respect to time. For times immediately after changes in transducer excitation (switching either ON or OFF), the change in the pyroelectric voltage is proportional to the delivered ultrasound power level. This paper describes a systematic evaluation of the measurement concept applied at physiotherapy frequencies and power levels, investigating key aspects such as repeatability, linearity and sensitivity. The research demonstrates the way that heating of the backing material affects the sensor performance, but outlines the potential of the method as a reproducible, rapid, solid-state method of determining power, requiring calibration using a known ultrasound power source. (E-mail: bajram.zeqiri@npl.co.uk)

Influence of the power level of an ultra-sonic system on dental cavity preparation

The aim of this study was to evaluate the shape of dental cavities made with the CVDentus system using different ultrasound power levels. One standard cavity was made on the buccal aspect of 15 bovine incisors with a CVDentus cylindrical bur (82142). The sample was divided into three groups: G1-ultrasound with power II; G2-ultrasound with power III; and G3-ultrasound with power IV. A standardizing device was used to obtain standardized preparations and ultrasound was applied during one minute in each dental preparation. The cavities were sectioned in the middle, allowing observation of the cavity's profile with a magnifying glass, and width and depth measurement using the Leica Qwin program. The Kruskal-Wallis (p<0.05) and Dunn statistical analyses demonstrated differences between the dental cavity shapes when powers III and IV were used. However, the cavities that were made with power III presented dimensions similar to those of the bur used for preparation. We concluded that the power recommended by the manufacturer (III) is the most adequate for use with the CVDentus system.

Alteration of free radical development by ophthalmic viscosurgical devices in phacoemulsification

To determine the effect of ophthalmic viscosurgical devices (OVDs) and irrigation/aspiration (I/A) settings on free radical development during phacoemulsification. Department of Ophthalmology, Nippon Medical School, Tokyo, Japan. Free radicals were detected by the electron spin resonance (ESR) spin-trap method. After a spin-trapping agent, 5,5-dimethyl-1-pyrroline N-oxide 1%, was mixed with the irrigating solution, phacoemulsification simulation was performed in an eye model at 100% ultrasound power levels for 10, 20, and 30 seconds. A high I/A setting (35 mL/min with 250 mm Hg vacuum) and a low I/A setting (15 mL/min with 60 mm Hg vacuum) were used in combination with no OVD, sodium hyaluronate 1% (Healon), sodium hyaluronate 2.3% (Healon5), sodium hyaluronate 3%-chondroitin sulfate 4% (Viscoat), or sodium hyaluronate 1% (Opegan). Immediately after phacoemulsification, the solution in the anterior chamber was collected and signals from the spin adduct were measured using an ESR spectrometer. With the low setting, all OVDs significantly suppressed the signals for up to 20 seconds. At 30 seconds, the signals were still significantly smaller in all OVD groups, except Healon, than those in the no-OVD. With the high setting, the effect was not significant in the Healon and Opegan groups at 10 seconds; by 20 seconds and after, only Viscoat showed significant suppression. Free radical development in phacoemulsification can be altered by OVD properties and I/A settings. To reduce oxidative stress to the corneal endothelium, attention should be paid to the retention of OVDs in the anterior chamber during phacoemulsification.

The influence of ultrasound power on multibubble sonoluminescence intensity from aqueous solutions containing surface active solutes

Water soluble surface active solutes have been found to affect the intensity of multibubble sonoluminescence (MBSL) in aqueous solutions. For example, the presence of charged surfactants enhances the MBSL intensity relative to that observed from pure water, whereas the presence of volatile surface active solutes decreases the MBSL intensity in reference to pure water [J. Phys. Chem. B 101, 10845 (1997)]. Further investigations on how ultrasound power influences the effect of surface active solutes on MBSL intensity have shown that ultrasound power plays an important role in governing the above mentioned effects. The relative enhancement in MBSL intensity by charged surfactants has been found to vary with changes in ultrasound power level; the relative enhancement decreases with an increase in the ultrasound power level. Also, the extent of MBSL quenching by alcohols has been found to increase with an increase in the applied ultrasound power level; no SL quenching at lower power levels and &amp;gt;80% SL quenching at higher power levels have been observed. The influence of ultrasound power on the population of ‘‘active’’ bubbles and the cavitation bubble temperature, in aqueous solutions containing surface active solutes, will be discussed in order to rationalize the observed experimental data.

Observation on the integrity of the blood-brain barrier after microbubble destruction by diagnostic transcranial color-coded sonography.

To investigate alteration of the blood-brain barrier from ultrasonic contrast agent destruction by diagnostic transcranial color-coded sonography using gadolinium-enhanced magnetic resonance imaging. Healthy male volunteers received 10 mL (400 mg/dL) of Levovist (SH U 508A; Schering AG, Berlin, Germany; n = 6) or 3 mL of Optison (FS069; Mallinckrodt Inc, St Louis, MO; n = 4) followed by 0.3 mmol/kg magnetic resonance imaging contrast agent (Magnevist; Schering) intravenously. Then transcranial color-coded sonography was performed with a conventional color duplex sonographic system, which insonated the brain in a slightly angulated axial plane with temporal average intensity of less than 700 mW/cm2 or acoustic pressure amplitude of less than 2.69 MPa, attenuated by the temporal bone. Before, immediately after, and 2 hours after insonation, T1-weighted axial magnetic resonance imaging was performed. All magnetic resonance images were individually assessed, and T1 signal intensities were measured in 2 regions of interest in both hemispheres at the 3 time points. No focal contrast enhancement or damage to the brain and no significant difference between T1 signal intensities in the right and left brain regions could be detected during early or late phases when either ultrasonic contrast agent was used. This bioeffects study gives further evidence of the safety of ultrasonic destruction of Levovist and Optison microbubbles by diagnostic transcranial color-coded sonography. However, more subtle local effects may have been missed by gadolinium-enhanced magnetic resonance imaging. Studies on diagnostic contrast-enhanced transcranial color-coded sonography as well as microbubble-based drug delivery strategies should consider ultrasonic contrast agent microbubble characteristics and concentration as well as ultrasound transmission power levels.

Ultrasound Exposure Enhances the Biological Action of Interferon in the Liver

Although interferon (IFN) α and β are currently recognized as the most effective agents for treating patients with chronic hepatitis B and C, they are well known to cause various adverse effects. To reduce the dose of IFN necessary for treatment, we tried enhancing the effects of IFN in the liver by ultrasound exposure. Percutaneous insonation in mouse liver following IFN- β injection with the ultrasound power level used at clinical diagnosis enhanced the IFN- β -induced increase of 2',5'-oligoadenylate synthetase (2-5AS) levels in the liver. This enhancement of the 2-5AS level was dependent on the duration as well as on the timing of insonation after the IFN- β injection. In contrast, liver insonation did not enhance 2-5AS levels in the lung or spleen, and moreover, it did not alter tissue distribution of injected IFN. Thus, the combination of IFN- β administration and subsequent liver insonation appears to be a promising method for enhancing the antiviral activity of IFN specifically in the liver, enabling a reduction in the dose necessary for treatment.

Assessment of a biuret method without concentration step for total protein determination in cerebrospinal fluid

To make better use of cod head (Gadus macrocephalus), a by-product of fish processing, the effects of ultrasound pretreatment on the enzymatic properties and volatile compounds of cod head enzymatic hydrolysates were investigated. The results demonstrated that ultrasound pretreatment at 150–600 W had a positive effect cod head enzymatic hydrolysates. The soluble peptides content of the enzymatic hydrolysates reached the highest value of 5.31 ± 0.16 mg/mL at the ultrasound power level of 450 W, and the content of peptide molecules < 3-kDa was up to 93.96%. The type and relative content of volatile compounds, especially aldehydes, alcohols, and ketones, also increased with the increase the ultrasound power. The electronic tongue results indicated that ultrasound pretreatment reduced bitterness and astringency. The electronic nose results indicated that the hydrogen- and alkane-containing odor components in the hydrolyzed liquid after ultrasound pretreatment differed significantly from conventional enzymatic hydrolysates. In conclusion, ultrasound pretreatment may be applicable as a suitable technology to assist enzymatic hydrolysis of the cod head, and as such, promote the utilization of fish by-products.

The High Temperature Treatment of Trinitrotoluene (TNT) and Cyclotrimethylene-Trinitramine (RDX) with Ozone and Ultrasound

Abstract This paper summarizes the results of research on the treatment of synthetically prepared aqueous solutions of trinitrotoluene (TNT) and cyclotrimethylene–trinitramine (RDX) in the weight ratio 70%/30% representing a typical munitions wastewater, by a combination of ozone and ultrasound. A parametric study investigated the relationship among the variables: (1) initial solution pH (5.84 → 10.0); (2) ultrasound power level (5 → 50 watts at 852.0 to 863.0 kHz);(3) ultrasound frequency level (60.6 → 1,007.0 kHz); (4) solution concentration (70/30 mg/l TNT/RDX solutions volumetrically diluted with distilled water in the ratios 1/0, 1/1, 1/3); (5) reaction temperature (25 → 59°C). Removal rates of both TNT and TOC increased directly with increases in reaction temperature and initial solution pH. Likewise, increased sound power level produced enhanced system kinetic responses; however, these were attributed to reaction mass temperature increases. Ultrasound was found to inhibit reaction kinetics at high ...