High-intensity Ultrasonic Waves Research Articles

Ultrasound assisted-viscosifying of kappa carrageenan without heating

The objective of this study was to evaluate viscosifying power of ultrasound waves on kappa carrageenan dispersions in water without using heat. After ultrasound treatment rheological characteristics of κ-carrageenan dispersions in water were evaluated at 45 °C. Shear stress-shear rate and viscosity curves clearly indicated sharp increases in viscosity and consistency coefficient (k) of ultrasound treated dispersions with ultrasonication time up to a certain level (1–2 min). All ultrasonicated dispersions showed shear thinning flow behavior. Prolonged exposure of κ-carrageenan dispersions to high-intensity ultrasonic waves produced a permanent reduction in viscosity, intrinsic viscosity and also relative molecular weight. Addition of KCl after ultrasonication was more effective in increasing viscosity compared to KCl addition prior to ultrasound treatment. Power ultrasound showed high potentials in solving some of traditional limitations related to solubility of hot water soluble biopolymers and may offer food and pharmaceuticals industries more options to benefit from a wider range of biopolymers.

Analysis of Temperature Field in a High-Intensity Ultrasonic Chamber

High-intensity ultrasonic vibration in narrow resonators creates various thermal effects, which has turned it in recent years into a promising new technology in ultrasonic power determination, as well as ultrasonic diagnostic and miniaturized thermoacoustic refrigerators. As a new type of thermoacoustic engine, miniature thermoacoustic device research is still in its infancy. The thermal effects in these engines are partly studied by assuming that the mean temperature in these machines does not change. In view of the aforementioned, complete calculations related to the generation, propagation, and temperature stabilization processes of high-intensity ultrasonic waves in a duct were performed, with the intention of providing a comprehensive view of the thermal processes in linear and nonlinear ultrasonic chambers. The mean temperature distributions and the related acoustic streaming patterns were predicted to vary with the increasing driving amplitude. A weak shock wave was generated in the large-amplitude cases. The integrated effects of the hysteresis loss, acoustic streaming, and weak shock led to dramatic variations of the heat flux transferred between the fluid and the isothermal walls in different amplitude acoustic fields. The results could guide the arrangement of measurement points in the determination of ultrasonic power, and they are significant for improving the efficiency of thermoacoustic devices.

Effect of Ultrasonic Treatment on Microstructure and Mechanical Property of <i>In Situ</i> Al/2TiB Particulate Composites

Al/2TiB2in-situ composite was fabricated using salt-melt reaction method. Subsequently, it was re-melted and treated with high intensity ultrasonic waves for various time intervals. Substantial reduction in TiB2 particle size down to ~ 300 nm along with significant improvement in dispersion is achieved with the aid of ultrasonic treatment. Ultrasonic treatment has resulted significant increase in hardness of Al/2TiB2in-situ composite.

Lithium niobate ultrasonic transducer design for Enhanced Oil Recovery

Due to the strong piezoelectric effect possessed by lithium niobate, a new idea that uses lithium niobate to design high-power ultrasonic transducer for Enhanced Oil Recovery technology is proposed. The purpose of this paper is to lay the foundation for the further research and development of high-power ultrasonic oil production technique. The main contents of this paper are as follows: firstly, structure design technique and application of a new high-power ultrasonic transducer are introduced; secondly, the experiment for reducing the viscosity of super heavy oil by this transducer is done, the optimum ultrasonic parameters for reducing the viscosity of super heavy oil are given. Experimental results show that heavy large molecules in super heavy oil can be cracked into light hydrocarbon substances under strong cavitation effect caused by high-intensity ultrasonic wave. Experiment proves that it is indeed feasible to design high-power ultrasonic transducer for ultrasonic oil production technology using lithium niobate.

High-intensity focused ultrasound for noninvasive body contouring: current perspectives

Noninvasive devices for fat reduction have become increasingly popular over the past decade. High-intensity focused ultrasound (HIFU), already in use for nearly half a century for the noninvasive treatment of tumors, has only recently been evaluated as a method for the selective ablation of adipose tissue. HIFU works by focusing high-intensity ultrasonic waves at the level of the subcutaneous adipose tissue, causing focal coagulative necrosis with contraction and thickening of adjacent collagen bundles while sparing the overlying tissue. Several studies reveal the safety and efficacy of HIFU for fat reduction in the abdomen and flanks. These studies show a consistent reduction in the abdominal circumference of at least 2 cm after a single treat- ment. Adverse events are limited to mild, transient procedural and postprocedural discomfort, erythema, bruising, and edema. HIFU is a safe and effective method for focal fat reduction.

Basic study of an estimation method for fire damage within concrete sample using high-intensity ultrasonic waves and optical equipment

After a fire in a concrete building, concrete walls may need to be entirely or partially repaired depending on the size of the fire. If the building is to be repaired, it is necessary to determine the extent and cost of the work. To do so, a method is needed for determining the level of fire damage within concrete walls, particularly along the depth direction. In a previous work, we have investigated a noncontact, nondestructive method using high-intensity aerial ultrasonic waves and optical equipment to detect the level of fire damage on the concrete surface, and we have demonstrated the feasibility of obtaining such information. Yet it is also important to determine the level of fire damage within concrete sample, particularly along the depth direction, in order to determine the extent of necessary repairs. In this study, we examined a new noncontact, minimally destructive method for estimating the level of fire damage within concrete sample. The results show that the level of fire damage could be determined along the depth direction.

1P2-32 Basic study of an estimation method for fire damage within concrete using high-intensity ultrasonic waves and optical equipment(Poster Session)

1P2-32 Basic study of an estimation method for fire damage within concrete using high-intensity ultrasonic waves and optical equipment(Poster Session)

초음파 캐비테이션에 의한 기포군에서의 음향특성 변화관찰

Ultrasonic cavitation is a physical phenomenon that generates and collapses microbubbles in media (mainly fluids) under conditions of strong ultrasonic irradiation. In this study, changes in the ultrasonic acoustic characteristics of bubble clouds in relation to ultrasonic irradiation were observed by the quantitative evaluation of cavitation yields. Concave-type single ultrasonic transducers with center frequencies of 500 kHz and 1.1 MHz were used to produce cavitation, and 2.25 MHz interference ultrasonic waves that would traverse any bubble clouds generated were used to analyze the cavitation. The parameters used for the evaluation of cavitation yields (changes in the center frequency, attenuation characteristics, and the propagation time of penetrating waves) were analyzed in relation to the cavitation-generating conditions (irradiation intensity, excitation signal, and center frequency). On the basis of these results, correlations between the changes in the center frequency and irradiation intensity were identified. Although the correlation coefficient was low, notable changes were observed in the center frequency under certain irradiation conditions. Attenuation trends in the interference ultrasonic waves showed high correlations with all the irradiation conditions, and it was noted that these trends were not affected by the forms of cavitation generated. No differences in the propagation time were observed among different irradiation conditions. These findings suggest that bubble yields can be quantitatively evaluated effectively by evaluating the diverse irradiation conditions and that such a quantitative evaluation could be used to study the basic cavitation phenomenon occurring in high-intensity ultrasonic wave treatment.

Releasing Dye Encapsulated in Proteinaceous Microspheres on Conductive Fabrics by Electric Current

The current paper reports on the relase properties of conductive fabrics coated with proteinaceous microspheres containing a dye. The release of the dye was achieved by passing an electric current through the fabric. The conductivity of the polyester fibers resulted from nanosilver (Ag NPs) coated on the surface of these fibers. Both types of coatings (nanosilver coating and the coating of the proteinaceous microspheres) were performed using high-intensity ultrasonic waves. Two different types of dyes, hydrophilic RBBR (Remazol Brilliant Blue R) and hydrophobic ORO (Oil Red O), were encapsulated inside the microspheres (attached to the surface of polyester) and then released by applying an electric current. The Proteinaceous Microsphere (PM)-coated conductive fabrics could be used in medicine for drug release. The encapsulated dye can be replaced with a drug that could be released from the surface of fabrics by applying a low voltage.

Effect of Ultrasonic Wave Irradiation Sequence in Microhollow Production Produced by Bubble Cavitation

Sonoporation, which makes micropores through a cell membrane by bubble cavitation, improves the efficacy in ultrasonic wave drug delivery systems. However, the effects of bubble cavitation are affected largely by bubble condition, such as bubble density and bubble aggregation, just before the irradiation of a high-intensity ultrasonic wave. Aiming at preparing a specific bubble condition in bubble cavitation, a method which uses the frequency modulation of a pumping ultrasonic wave was proposed. In this paper, the effects of the ultrasonic wave irradiation sequence are evaluated under different flow velocities and bubble densities. The spatial correlation between microbubble clouds produced by the pumping ultrasonic wave and the microhollows produced by the bubble cloud cavitation is also discussed.

Effect of Ultrasonic Wave Irradiation Sequence in Microhollow Production Produced by Bubble Cavitation

Sonoporation, which makes micropores through a cell membrane by bubble cavitation, improves the efficacy in ultrasonic wave drug delivery systems. However, the effects of bubble cavitation are affected largely by bubble condition, such as bubble density and bubble aggregation, just before the irradiation of a high-intensity ultrasonic wave. Aiming at preparing a specific bubble condition in bubble cavitation, a method which uses the frequency modulation of a pumping ultrasonic wave was proposed. In this paper, the effects of the ultrasonic wave irradiation sequence are evaluated under different flow velocities and bubble densities. The spatial correlation between microbubble clouds produced by the pumping ultrasonic wave and the microhollows produced by the bubble cloud cavitation is also discussed.

Treatment with high intensity focused ultrasound: Secrets revealed

For many decades open surgery remained the only way available for local control of body tumors. In order to decrease the patients' morbidity and mortality several image guided minimally invasive procedures have been adopted. High intensity focused ultrasound (HIFU) is an extracorporeal non invasive method for tumor ablation. High intensity ultrasonic waves can be focused to a focal point resulting in lethal elevation of the temperature at the target site with consequent damage of the tumoral cells. The advances in HIFU technology during the past two decades expanded the HIFU applications to include ablation of both benign and malignant tumors with different treatment strategies being implemented for each type. The aim of this review is to introduce the reader to the details of the treatment process including pretreatment preparation, treatment planning, different ablation strategies, patients' after care as well as the follow up regimens for the most common HIFU applications.

Effect of Pretrapping of Microbubbles in Sonoporation Using N-Isopropylacrylamide Gel Flow Channel Phantom

It is considered that sonoporation, which produces small pores through a cell membrane, is a sophisticated tool for improving the efficacy of ultrasonic-wave-irradiated drug delivery systems. However, neither the precise mechanism of pore production nor the optimum conditions of insonation have been clarified yet. In this study, the microscopic observation of micron size hollows produced on the wall of an optical transparent gel by bubble cavitation is performed in order to evaluate sonoporation. As a gel phantom, we adopted N-isopropylacrylamide (NIPA) gel, which has almost the same acoustic properties as soft tissue and is optically transparent below the metastasis temperature. Using the gel phantom, the effect of the pretrapping of microbubbles, which is carried out immediately before irradiating a high-intensity ultrasonic wave to prepare the bubble conditions required for sonoporation, is evaluated.

Experimental study of defoaming by air-borne power ultrasonic technology

Foam is a dispersion of gas in a liquid in which the distances between the gas bubbles are very small. Foams are frequently generated in the manufacture of many products as result from the aeration and agitation of liquids, from the vaporization of the liquid and also from biological or chemical reactions. Foams are generally an unwanted product in industrial processes because they cause difficulties in process control and in equipment operation. The most efficient conventional method for defoaming is the use of chemical agents but they contaminate the product. High-intensity ultrasonic waves offer a clean procedure to break foam bubbles. The potential use of ultrasound for foam breaking that was known since many years has been recently reinforced by the application of a new type of ultrasonic defoamer based on the stepped-plate high-power transducers to generate air-borne ultrasound. This defoamer has been successfully applied in several industrial problems such as the control of excess foam produced during the filling operation of bottles and cans on high-speed canning lines and in fermenting vessels and other reactors of great dimensions.The treatment of such industrial problems requires the proper characterization and quantification of the main parameters involved in the mechanisms of the defoaming effect. This paper deals with an experimental study about the separate influence of such parameters with the aim of improving the application of the stepped-plate power ultrasonic generators for the production of the defoaming action on industrial processes

Microbubble Trapping by Nonlinear Bubble Oscillation Using Pumping Wave

Microbubble manipulation by acoustic radiation force may play an important role in future drug delivery systems, because the required bubble manipulations, such as bubble trapping at the desired position and payload release by bubble destruction using a high-intensity ultrasonic wave, are controlled by ultrasonic waves. In this paper, a novel method of microbubble trapping by bubble nonlinear oscillation is proposed. Two ultrasonic waves, which have a harmonic frequency relation, are used in order to generate the force for trapping bubbles. The first wave is a pumping wave, which has a relatively high sound pressure. This wave is used for inducing the nonlinear oscillation of bubbles. The second wave is a control wave, whose frequency is set to be the harmonic frequency of the nonlinear bubble oscillation. The pressure gradient of the control wave in conjunction with the harmonic component of nonlinear oscillation generates the Bjerknes force applied to bubbles. This force forms multiple traps with a narrow separation for bubbles, which flow into the cross area of the two ultrasonic waves.

Degradation and in situ reaction of polyolefin elastomers in the melt state induced by ultrasonic irradiation

AbstractThe degradation and in situ reaction with polystyrene (PS) of polyolefin elastomers in the melt state induced through high intensity ultrasonic wave were investigated. The effects of initial molecular weight of polyolefin elastomers, irradiation time, ultrasonic intensity, as well as reaction temperature on the ultrasonic degradation of polyolefin elastomers melt were studied using a “static” ultrasonic vibration system. The results show that the degradation occurs mostly at the tip of the ultrasonic probe, and little or no degradation was observed at the distance of 5 mm or greater from the tip of the probe. The intrinsic viscosity [η] of polyolefin elastomers near the tip of ultrasound probe significantly decreases with irradiation time in the first 100 s and tends toward a limiting value for all samples. The degradation rates increased with an increase in ultrasonic intensity and decrease in reaction temperature. The ultrasonic degradation kinetics of polyolefin elastomers in melt state follows the equation: [η]t = [η]∞ + Ae−kt. The fitting results by this equation accord well with the experimental data. The feasible ultrasonic degradation mechanism is proposed based on the viscoelastic characteristic of polymer melt. FTIR analysis confirms that the copolymer forms under ultrasonic irradiation for PS/POE mixtures and in situ reaction of polymer in melt state can be induced by ultrasonic irradiation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Continuous extrusion of long-chain-branched polypropylene/clay nanocomposites with high-intensity ultrasonic waves

A continuous extrusion processing method with high-intensity ultrasonic waves was developed to make a long-chain-branched polypropylene/clay nanocomposite. A multifunctional agent was used to enhance and control the recombination reaction during sonification. The ultrasonic waves induced chain scission and created reactive macromolecules of polypropylene successfully in the continuous extrusion process without any peroxide. The rheological property measurements confirmed that the modified polypropylene had a nonlinear branched structure. Another purpose of dosing high-intensity ultrasonic waves was to enhance nano-scale dispersion during melt mixing of polypropylene and clay. The sonication during processing led to enhanced breakup of the clay agglomerates and reduction in size of the dispersed phase. The observed clay was in the intercalated state without any compatibilizer. The fine dispersion of clay was also quite effective in reducing the end pressure losses in capillary dies and, as a result, significantly improved the extrudate appearance during processing.

Yeast Cell Trapping In Ultrasonic Wave Field Using Ultrasonic Contrast Agent

Microobject manipulation using ultrasonic waves is expected to play important roles in constructing future drug or gene delivery systems. The acoustic radiation force, which is applied to microobjects, traps the objects at the desired position. A microjet, which is produced by bubble explosion under high-intensity ultrasonic waves, creates microholes through the cell membrane (sonoporation), which is considered as a sophisticated method of improving the doses of drugs or genes injected into a tissue. Aiming at increasing the trapping force in micro bubble manipulation using ultrasonic waves, we have proposed a novel method based on the self-organization of microbubbles. This method uses seed bubbles in order to trap the target bubbles. In this study, the proposed method is applied to yeast cell trapping using ultrasonic waves. An ultrasonic wave contrast agent (Levovist; Shering A.G., Germany) is used as a seed bubble. It is shown that the number of trapped yeast cells depends on the preparation of the yeast cells. In order to evaluate the result, two additional experiments are carried out by changing the internal gas of the seed bubbles and by using bubbles with a polymer shell.

In‐situ ultrasonic compatibilization of unvulcanized and dynamically vulcanized PP/EPDM blends

AbstractDynamically vulcanized PP/EPDM blends were treated by high‐intensity ultrasonic waves during extrusion. These blends were compared with unvulcanized PP/EPDM blends that were treated by ultrasound during extrusion and then dynamically vulcanized. Die pressure and power consumption were measured. The effects of different gap sizes, ratio of components, and number of ultrasonic horns were investigated. The rheological properties, morphology and mechanical properties of the blends with and without ultrasonic treatment were compared. The results obtained indicated that ultrasonic treatment induced thermo‐mechanical degradation, causing enhanced molecular transport and chemical reactions at the interfaces, thus leading to in‐situ compatibilization, which is evident by the morphological and mechanical property studies. Processing conditions were established for enhanced in‐situ compatibilization of the PP/EPDM blends that were either originally dynamically vulcanized and then ultrasonically treated or first treated and then dynamically vulcanized. Polym. Eng. Sci. 44:2019–2028, 2004. © 2004 Society of Plastics Engineers.

Inactivation of Escherichia coli by ultrasonic irradiation

Ultrasonic inactivation of Escherichia coli XL1-Blue has been investigated by high-intensity ultrasonic waves from horn type sonicator (27.5 kHz) utilizing the “squeeze-film effect”. The amplitude of the vibration face contacting the sample solution was used as an indication of the ultrasonic power intensity. The inactivation of the E. coli cells by ultrasonic irradiation shows pseudo first-order behavior. The inactivation rate constant gradually increased with increasing amplitude of the vibration face and showed rapid increase above 3 μm (p–p). In contrast, the H 2O 2 formation was not observed below 3 μm (p–p), indicating that the ultrasonic shock wave might be more important than indirect effect of OH radicals formed by ultrasonic cavitation in this system. The optimal thickness of the squeeze film was determined as 2 mm for the E. coli inactivation. More than 99% of E. coli cells was inactivated within 180-s sonication at the amplitude of 3 μm (p–p) and 2 mm of the thickness of the squeeze film.