A high-speed in situ microscopic observation system developed for basic studies on mechanisms of sonoporation is introduced in this paper. The main part of the system is an inverted-type fluorescence ...microscope, and a high-speed camera of 20 MHz in a maximum framing rate was used to visualize the dynamics of cavitation bubbles that causes a sonoporation effect. Differential interference contrast and fluorescence techniques were used for sensitive visualization of cell changes during sonoporation. The system is also equipped with optical tweezers that can move a microbubble of several microns in size by using a donut-shaped light beam. In situ microscopic observation of sonoporation was carried out using a cell with a size- and position-controlled microbubble. The experimental results showed that the ability of cells to repair sonoporation-induced damage depends on their membrane tension, indicating the usefulness of the observation system as a basic tool for the investigation of sonoporation phenomena.
•Today’s magnetostrictive patch transducer technology is reviewed.•Applications for ultrasonic nondestructive testing in waveguides are reviewed.•The operating principle, analysis and design of the ...transducer are covered.•The transducers developed for plates, shafts and pipes are presented.•Tailored transducers for metamaterial and phonon crystal waveguide are illustrated.
A magnetostrictive patch transducer (MPT) is a transducer that exploits the magnetostrictive phenomena representing interactions between mechanical and magnetic fields in ferromagnetic materials. Since MPT technology was mainly developed and applied for nondestructive ultrasonic testing in waveguides such as pipes and plates, this paper will accordingly review advances of this technology in such a context. An MPT consists of a magnetic circuit composed of permanent magnets and coils, and a thin magnetostrictive patch that works as a sensing and actuating element which is bonded onto or coupled with a test waveguide. The configurations of the circuit and magnetostrictive patch therefore critically affect the performance of an MPT as well as the excited and measured wave modes in a waveguide. In this paper, a variety of state-of-the-art MPT configurations and their applications will be reviewed along with the working principle of this transducer type. The use of MPTs in wave experiments involving phononic crystals and elastic metamaterials is also briefly introduced.
•The two devices of UMT and UIT were assembled by the investigators.•The effects of five thawing methods on protein properties and moisture migration were studied.•UMT and UIT could maintain the ...quality of the red drum fillets better than controls.
The influence of ultrasonics combined with microwave thawing (UMT) and ultrasonics combined with far-infrared thawing (UIT) on the water migration and protein denaturation of red drum were studied. Five treatments were used: ultrasonics thawing (UT), microwave thawing (MT), far-infrared thawing (IT), UIT and UMT were used for thawing red drum filets. Moisture migration and protein aggregation were studied using nuclear magnetic resonance (NMR) and particle size, respectively. Raman spectra and fluorescence spectra were used to study the secondary and tertiary structure of protein. SEM was done to observe the fiber microstructure. The results showed that UMT and UIT can maintained protein stability more than other thawing methods and retained the fiber structure of the muscle. Besides, immobilized water in fiber bundles network also had no significant changes compared with fresh samples. Thus, ultrasonics combined with far infrared or microwave thawing were used to decrease protein denaturation and water migration during the thawing of Red drum fillets.
Purpose:
To build Monte Carlo (MC) models of two ultrasound (US) probes and to quantify the effect of beam attenuation due to the US probes for radiation therapy delivered under real‐time US image ...guidance.
Methods:
MC models of two Philips US probes, an X6‐1 matrix‐array transducer and a C5‐2 curved‐array transducer, were built based on their megavoltage (MV) CT images acquired in a Tomotherapy machine with a 3.5 MV beam in the EGSnrc, BEAMnrc, and DOSXYZnrc codes. Mass densities in the probes were assigned based on an electron density calibration phantom consisting of cylinders with mass densities between 0.2 and 8.0 g/cm3. Beam attenuation due to the US probes in horizontal (for both probes) and vertical (for the X6‐1 probe) orientation was measured in a solid water phantom for 6 and 15 MV (15 × 15) cm2 beams with a 2D ionization chamber array and radiographic films at 5 cm depth. The MC models of the US probes were validated by comparison of the measured dose distributions and dose distributions predicted by MC. Attenuation of depth dose in the (15 × 15) cm2 beams and small circular beams due to the presence of the probes was assessed by means of MC simulations.
Results:
The 3.5 MV CT number to mass density calibration curve was found to be linear with R2 > 0.99. The maximum mass densities in the X6‐1 and C5‐2 probes were found to be 4.8 and 5.2 g/cm3, respectively. Dose profile differences between MC simulations and measurements of less than 3% for US probes in horizontal orientation were found, with the exception of the penumbra region. The largest 6% dose difference was observed in dose profiles of the X6‐1 probe placed in vertical orientation, which was attributed to inadequate modeling of the probe cable. Gamma analysis of the simulated and measured doses showed that over 96% of measurement points passed the 3%/3 mm criteria for both probes placed in horizontal orientation and for the X6‐1 probe in vertical orientation. The X6‐1 probe in vertical orientation caused the highest attenuation of the 6 and 15 MV beams, which at 10 cm depth accounted for 33% and 43% decrease compared to the respective (15 × 15) cm2 open fields. The C5‐2 probe in horizontal orientation, on the other hand, caused a dose increase of 10% and 53% for the 6 and 15 MV beams, respectively, in the buildup region at 0.5 cm depth. For the X6‐1 probe in vertical orientation, the dose at 5 cm depth for the 3‐cm diameter 6 MV and 5‐cm diameter 15 MV beams was attenuated compared to the corresponding open fields to a greater degree by 65% and 43%, respectively.
Conclusions:
MC models of two US probes used for real‐time image guidance during radiotherapy have been built. Due to the high beam attenuation of the US probes, the authors generally recommend avoiding delivery of treatment beams that intersect the probe. However, the presented MC models can be effectively integrated into US‐guided radiotherapy treatment planning in cases for which beam avoidance is not practical due to anatomy geometry.
•Starch aqueous solutions were treated by ultrasound for different periods of time.•The ultrasonic treatment led to decrease in viscosity and starch chain scission.•Starch nanoparticles (SNPs) were ...prepared through nanoprecipitation.•The ultrasonic treatment gave the SNPs smaller size and narrower size distribution.•Ultrasonic treatment can be used to overcome the shortcomings of nanoprecipitation.
The purpose of this work was to develop an approach to produce size controlled starch nanoparticles (SNPs), via precipitation with high efficiency and low cost. High concentration starch aqueous pastes (up to 5wt.%) were treated by ultrasound. Viscosity measurements and size exclusion chromatography characterization revealed that, after 30min ultrasonic treatment, viscosity of the starch pastes decreased two orders of magnitude and the weight average molecular weight of the starch decreased from 8.4×107 to 2.7×106g/mol. Dynamic light scattering measurements and scanning electron microscopy observations showed that the SNPs prepared from the starch pastes with ultrasonic treatments were smaller (∼75nm) and more uniform. Moreover, SNPs could be obtained using less non-solvents. X-ray diffraction results indicated that effect of the ultrasonic treatment on crystalline structure of the SNPs was negligible. Ultrasound can be utilized to prepare smaller SNPs through nanoprecipitation with higher efficiency and lower cost.
Coated microbubbles, unlike tissue are able to scatter sound subharmonically. Therefore, the subharmonic behavior of coated microbubbles can be used to enhance the contrast in ultrasound contrast ...imaging. Theoretically, a threshold amplitude of the driving pressure can be calculated above which subharmonic oscillations of microbubbles are initiated. Interestingly, earlier experimental studies on coated microbubbles demonstrated that the threshold for these bubbles is much lower than predicted by the traditional linear viscoelastic shell models. This paper presents an experimental study on the subharmonic behavior of differently sized individual phospholipid coated microbubbles. The radial subharmonic response of the microbubbles was recorded with the Brandaris ultra high-speed camera as a function of both the amplitude and the frequency of the driving pulse. Threshold pressures for subharmonic generation as low as 5 kPa were found near a driving frequency equal to twice the resonance frequency of the bubble. An explanation for this low threshold pressure is provided by the shell buckling model proposed by Marmottant et al. J. Acoust. Soc. Am. 118, 3499-3505 (2005). It is shown that the change in the elasticity of the bubble shell as a function of bubble radius as proposed in this model, enhances the subharmonic behavior of the microbubbles.
In this study, a novel heterogeneous ultrasonic (US)-enhanced sludge biochar (SBC) activated periodate (PI) system was established and explored for the rapid removal of levofloxacin in the aqueous ...environment. This study focused on the mechanisms of US-enhanced SBC co-activation of PI for levofloxacin degradation. The results indicated that US and SBC exhibited a remarkable synergistic reinforcing activation effect on PI compared to single PI activation systems. The SBC/US/PI system achieved approximately 95% of levofloxacin removal, 51.5% of TOC removal, and 22% of dechlorination rate within 60 min with virtually no heavy metals released into the water matrix. In addition, the acute ecotoxicity of the solutions treated with the SBC/US/PI system was substantially reduced. The presence of IO3•, •OH, 1O2 and O2•- were identified in the SBC/US/PI system using quenching experiments and EPR technology while •OH and 1O2 were the predominant reactive species. Mechanistic studies have suggested that the cavitation effect of ultrasonic improved the dispersion and mass transfer efficiency of SBC and accelerated the desorption process of SBC. Possible pathways of levofloxacin degradation were proposed. This study provides a novel and promising strategy for the efficient removal of emerging contaminants such as antibiotics from the water matrix.
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•Ultrasonic markedly enhances the activation effect of sludge biochar on periodate.•SBC/US/PI system can remove LVF efficiently under a broad pH range.•SBC/US/PI system exhibits outstanding reusability without notable metal leaching.•Possible mechanisms and degradation pathways of LVF degradation were proposed.
Purpose:
The purpose of this study was to investigate the ability and efficacy of inducing sonoporation in a clinical setting, using commercially available technology, to increase the patients’ ...quality of life and extend the low Eastern Cooperative Oncology Group performance grade; as a result increasing the overall survival in patients with pancreatic adenocarcinoma.
Methods:
Patients were treated using a customized configuration of a commercial clinical ultrasound scanner over a time period of 31.5 min following standard chemotherapy treatment with gemcitabine. SonoVue® ultrasound contrast agent was injected intravascularly during the treatment with the aim to induce sonoporation.
Results:
Using the authors’ custom acoustic settings, the authors’ patients were able to undergo an increased number of treatment cycles; from an average of 9 cycles, to an average of 16 cycles when comparing to a historical control group of 80 patients. In two out of five patients treated, the maximum tumor diameter was temporally decreased to 80 ± 5% and permanently to 70 ± 5% of their original size, while the other patients showed reduced growth. The authors also explain and characterize the settings and acoustic output obtained from a commercial clinical scanner used for combined ultrasound microbubble and chemotherapy treatment.
Conclusions:
It is possible to combine ultrasound, microbubbles, and chemotherapy in a clinical setting using commercially available clinical ultrasound scanners to increase the number of treatment cycles, prolonging the quality of life in patients with pancreatic adenocarcinoma compared to chemotherapy alone.
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