Application of ultrasound as pretreatment for extraction of podophyllotoxin from rhizomes of Podophyllum peltatum

The effect of high-power ultrasound pretreatment on the extraction of podophyllotoxin from Podophyllum peltatum was investigated. Direct sonication by an ultrasound probe horn was applied at 24 kHz and a number of factors were investigated: particle size (0.18-0.6 mm), type of solvent (0-100% aqueous ethanol), ultrasonic treatment time (2-40 min), and power of ultrasound (0-100% power intensity, maximum power: 78 W). The optimal condition of ultrasound was achieved with 0.425-0.6 mm particle size, 10 min sonication time, 35 W ultrasound power, and water as the medium. There was no obvious degradation of podophyllotoxin with ultrasound under the applied conditions, and an improvement in extractability was observed. The SEM microscopic structure change of treated samples disclosed the effect of ultrasound on the tissue cells. The increased pore volume and surface area after ultrasonic treatment also confirmed the positive effect of ultrasound pretreatment on the extraction yield of podophyllotoxin from the plant cells.     

Physical and chemical effects of ultrasound vibration on polymer melt in extrusion

The physical and chemical effects of ultrasound on polypropylene (PP) melts in extrusion were investigated. By applying ultrasound vibration to the entrance of the die, apparent pressure and viscosity of PP can be obviously decreased under the appropriate ultrasound power. Ultrasound has both physical and chemical effects on the polymer melt. In our study with specific polymer and ultrasound system, we determined that the chemical effect makes up 35–40% of the total effect of ultrasound on the apparent viscosity reduction of PP melts at most of the studied intensities. The physical effect plays a more important role in the ultrasound-applied extrusion than the chemical effect. This chemical effect is an irreversible and permanent change in molecule weight and the molecular-weight distribution due to ultrasound. As the ultrasound intensity increases, the molecular weight of PP reduces and its molecular-weight distribution becomes narrower; the orientation of PP molecules along the flow direction reduces (in melt state) and the crystallinity of PP samples (in solid state) decreases by applying the ultrasound vibration. Ultrasound vibration increases the motion of molecular chains and makes them more disorder; it also affects the relaxation process of polymer melts by shortening the relaxation time of chain segments, leading to weakening the elastic effect and decreasing the extruding swell ratios. All the factors discussed above reduce the non-Newtonian flow characteristics of the polymer melt and result in the viscosity drop of the polymer melt in extrusion.     

In vitro effects of ultrasound with different energies on the conduction properties of neural tissue

The effect of ultrasound at various energy levels on the conduction properties of neural tissue is explored in this in vitro study. Excised sciatic nerves from the bullfrog were used for experiments. The nerves were stimulated by 3.5 MHz continuous wave ultrasound at 1, 2, and 3 W for 5 min. The peak-to-peak amplitude of the electrically evoked compound action potential (CAP) and the conduction velocity (CV) were measured in the nerves before and during ultrasound stimulation. The CV of the nerves increased by 5-20% for ultrasound stimulations at 1-3 W. The CAP amplitude increased by 8% during stimulation with 1 W ultrasound, and progressively decreased for 2 and 3 W ultrasound. This indicates that the effect of lower energy ultrasound increases both the CV and the CAP amplitude and that the reduction in the CAP amplitude for higher energy ultrasound is associated largely with ultrasonic thermal effects.     

Evaluation of activity of a commercial amylase under ultrasound-assisted irradiation

The main objective of this work was to evaluate the effects of ultrasound irradiation on the activity of a commercial amylase. A central composite design was carried out to assess the effects of temperature and pH on the enzyme activity in the presence and absence of ultrasound irradiation. The activation energy, the influence of treatment time as well as the substrate concentration on enzyme activity were also determined in the presence and absence of ultrasound irradiation. The results demonstrated that the effect of temperature was less pronounced in the presence of ultrasound, resulting in a decreasing of about 80% in the activation energy in comparison with the value obtained in the absence. The enzyme showed activities about 3 times higher for temperatures up to 40 °C in the presence of ultrasound. The pH negatively affected the activity in the presence of ultrasound, whereas in the absence a positive effect was verified. The ultrasound irradiation is a promising technology to be used in enzymatic reaction due to its positive effects on enzyme activity.     

Effect of ultrasound on sodium arsenate induction time and crystallization property during solution crystallization processes

The effect of ultrasound vibrations on the cooling crystallization of sodium arsenate in supersaturated solutions was investigated. In particular, the effects of ultrasound vibrations on induction time and crystal size distribution were studied using a laser-based apparatus with relative supersaturation ranging from 1.3 to 1.8. The results show that ultrasound vibrations have a significant effect on reducing induction time and crystal size distribution. The application of ultrasound vibrations to the system resulted in a small change in surface tension; however, the induction time and crystal size significantly decreased. The mean size of sodium arsenate crystals decreased from 398.87 ± 3.27 to 168.68 ± 2.07 μm, as the ultrasound power increases from 26 to 130 W. Ultrasound vibrations significantly reduced the induction time in a highly supersaturated solution compared to that in a low supersaturated solution.     

Ultrasound-stimulated increase in the electron diffusion length in p-Si crystals

The effect of ultrasound on the diffusion length of minority charge carriers in dislocation-free p-Si is investigated in the frequency range 0.8–5.5 MHz. The diffusion length is measured by the surface photovoltage method. It is found that the diffusion length reversibly increases (by a factor of two at a sound intensity of 3 W/cm²) in response to ultrasound. The dependences of the diffusion length on the ultrasound amplitude and the kinetic characteristics upon switching on and switching off the ultrasound are analyzed. The phenomena observed are explained within the proposed model of transformation of recombination centers under the effect of ultrasound.     

Low-intensity ultrasound enhances the antimicrobial activity of neutral peptide TGH2 against Escherichia coli

In recent years, foodborne diseases caused by Escherichia coli are a major threat to the food industry and consumers. Antimicrobial peptides (AMPs) and ultrasound both have good inhibitory effects on E. coli. In this work, the mechanism of action and synergistic effect of an in silico predicted AMP, designated as TGH2 (AEFLREKLGDKCTDRHV), from the C-terminal sequence of Tegillarca granosa hemoglobin, combined with low-intensity ultrasound was explored. The minimal inhibitory concentration (MIC) of TGH2 on E. coli decreased by 4-fold to 31.25 μg/mL under 0.3 W/cm² ultrasound treatment, while the time kill curve analysis showed that low-intensity ultrasound combined with peptide TGH2 had an enhanced synergistic bactericidal effect after 0.5 h. The permeability on E. coli cell membrane increased progressively during combined treatment with peptide TGH2 and low-intensity ultrasound, resulting in the leakage of intracellular solutes, as shown by transmission electron microscopy (TEM). Structural analysis using circular dichroism (CD) revealed that peptide TGH2 has an α-helical structure, showing a slight untwisting effect under 0.3 W/cm² ultrasound treatment for 0.5 h. The findings here provide new insight into the potential application of ultrasound and AMPs combination in food preservation.     

超声在植物学领域的应用

本文综述了超声在植物学研究和实践中的应用。研究涉及超声提取和分析植物体内的各种成份，超声导致的空化作用及其对植物体的影响，以及超声对植物染色体的影响等；应用超声可以分散、破碎细咆；超声还具清洁作用。在植物领域中超声的应用主要是利用了超声的空化作用、机械作用和热效应。     

On ultrasound waves guided by bones with coupled soft tissues: A mechanism study and in vitro calibration

The influence of soft tissues coupled with cortical bones on precision of quantitative ultrasound (QUS) has been an issue in the clinical bone assessment in conjunction with the use of ultrasound. In this study, the effect arising from soft tissues on propagation characteristics of guided ultrasound waves in bones was investigated using tubular Sawbones phantoms covered with a layer of mimicked soft tissue of different thicknesses and elastic moduli, and an in vitro porcine femur in terms of the axial transmission measurement. Results revealed that presence of soft tissues can exert significant influence on the propagation of ultrasound waves in bones, leading to reduced propagation velocities and attenuated wave magnitudes compared with the counterparts in a free bone in the absence of soft tissues. However such an effect is not phenomenally dependent on the variations in thickness and elastic modulus of the coupled soft tissues, making it possible to compensate for the coupling effect regardless of the difference in properties of the soft tissues. Based on an in vitro calibration, this study proposed quantitative compensation for the effect of soft tissues on ultrasound waves in bones, facilitating development of high-precision QUS.     

Use of ultrasound as a pre-treatment for vacuum cooling process of cooked broiler breasts

In this study, ultrasound application at two different frequencies (37 or 80 kHz) and durations (15 or 30 min) was used as a pre-treatment for raw broiler breasts, and its effect on cooling, color, textural and sensory characteristics of cooked broiler breasts during vacuum cooling process was determined. The anterior and posterior parts of broiler breast halves were carefully removed, and these parts with a 20 mm width were named as the regions A and B, respectively. Both regions were vacuum-packed and pre-treated by ultrasound, followed by oven-cooking in aluminum foils, and cooling time, weight loss and temperature distribution characteristics were determined. Besides sensory and textural properties, the effect of the ultrasound pre-treatment on the pH, dry matter and ash contents and color (CIELAB) values of cooked breasts was determined. During vacuum cooling, ultrasound pre-treatment significantly reduced cooling time required to cool cooked broiler breasts from 85 °C to 12.5 °C, and the lowest values for the regions A and B were obtained for the 30 min ultrasound pre-treatment at 37 kHz as 12.72 and 14.61 min, respectively (p < 0.05). The cooling losses of breasts from the regions A and B were 12.64 and 11.61%, respectively. In comparison to immersion pre-treatment, increasing the frequency and duration of ultrasound pre-treatment generally decreased cooking loss values for both A and B regions while cooling loss increased. Instrumental hardness values of breast samples for the 15 min ultrasound pre-treatment decreased while they increased with the 30 min pre-treatment (p < 0.05) at both frequencies. The redness values (a*) increased by ultrasound pre-treatment while the highest value was found for a 30 min pre-treatment at 80 kHz for both regions. Sensory hardness (on a 14.5 cm scale) results indicated that the highest value (9.33) was determined for a 30 min ultrasound pre-treatment at 37 kHz while the ultrasound pre-treatment at 37 kHz for 15 min had no negative effect on hardness compared to control samples (p > 0.05). In conclusion, ultrasound pre-treatment can be successfully used for the vacuum cooling process of broiler breasts for the reduction of cooling time, and a 30 min ultrasound pre-treatment at 37 kHz can provide relatively superior cooling characteristics.     

The effect of ultrasound treatment on the interaction of brine with pork meat proteins

The objective of the study is to elucidate the effect of ultrasound treated salt solution on curing of pork meat. The interactions of salt (NaCl) solutions of 3 and 25% with the proteins of pork meat are studied. High intensity ultrasound operating at 20 kHz was used. The differential scanning calorimetry (DSC), NMR spin-spin relaxation time, unfrozen water and water diffusion coefficient measurements were carried out in meat cured with ultrasound treated and untreated salt solutions. The effect of ultrasonication was most evident from measured spin-spin relaxation times T₂₁, the rate of chemical exchange of water protons k and the amount of unfrozen water W_unf in the meat. The measured diffusion coefficient of water D_w in meat cured with ultrasound treated and control salt solution did not show significant difference. The nuclear magnetic resonance (NMR) relaxation data, differential scanning calorimetry (DSC) and the diffusion coefficient data reliably show that the possible action of ultrasound to salt solution was manifested on the first 2 days of the experiment with a 3% salt solution.     

Quality properties of pre- and post-rigor beef muscle after interventions with high frequency ultrasound

The delivery of a consistent quality product to the consumer is vitally important for the food industry. The aim of this study was to investigate the potential for using high frequency ultrasound applied to pre- and post-rigor beef muscle on the metabolism and subsequent quality. High frequency ultrasound (600 kHz at 48 kPa and 65 kPa acoustic pressure) applied to post-rigor beef striploin steaks resulted in no significant effect on the texture (peak force value) of cooked steaks as measured by a Tenderometer. There was no added benefit of ultrasound treatment above that of the normal ageing process after ageing of the steaks for 7 days at 4 °C. Ultrasound treatment of post-rigor beef steaks resulted in a darkening of fresh steaks but after ageing for 7 days at 4 °C, the ultrasound-treated steaks were similar in colour to that of the aged, untreated steaks. High frequency ultrasound (2 MHz at 48 kPa acoustic pressure) applied to pre-rigor beef neck muscle had no effect on the pH, but the calculated exhaustion factor suggested that there was some effect on metabolism and actin-myosin interaction. However, the resultant texture of cooked, ultrasound-treated muscle was lower in tenderness compared to the control sample. After ageing for 3 weeks at 0 °C, the ultrasound-treated samples had the same peak force value as the control. High frequency ultrasound had no significant effect on the colour parameters of pre-rigor beef neck muscle. This proof-of-concept study showed no effect of ultrasound on quality but did indicate that the application of high frequency ultrasound to pre-rigor beef muscle shows potential for modifying ATP turnover and further investigation is warranted.     

Application of ultrasound treatment in chicken gizzards tenderization: Effects on muscle fiber and connective tissue

The tenderizing effect of different ultrasound treatments on the characteristics of muscle fibers and connective tissue of chicken gizzard was investigated. It could be concluded that the shear force and muscle fiber diameter of the sample treated with ultrasound for 500 W/30 min were decreased by 27.1% and 26.2%, respectively, while the myofibril fragmentation index (MFI) was increased by 238.1% than the control. More importantly, the contents of hydroxylysine pyridinoline and lysine pyridinoline of the samples treated with ultrasound for 500 W/30 min were 23.1% and 40.5% lower than those of the control. Tenderizing effect of 500 W/30 min sample on thermal stability was verified from the decrease in transition temperature (Tmax) (10.7%) and enthalpy (ΔH) (21.7%) of collage compared with the control. In general, proper ultrasound treatment could effectively improve the tenderness of gizzard, and 500 W/30 min had the best tenderization effect. Therefore, the treatment of ultrasound was considered as a promising and efficient technique in meat processing, especially for the meat tenderization.     

我国超声波疗法的新进展

本文通过对第二届全国超声治疗学术会议论文的综合介绍，展示了我国超声波治疗方面的近期实验研究工作：不同频率超声波的透入、低频超声对小分子通过半透膜的影响、超声波治疗实验性家犬脑出血的疗效、颅骨对超声波的吸收率、超声波对组织硬结作用的动物实验、超声波对细菌的作用等．文章还报道了临床应用方面所取得的新进展．     

Ultrasound for low temperature dyeing of wool with acid dye

The possibility of reducing the temperature of conventional wool dyeing with an acid levelling dye using ultrasound was studied in order to reach exhaustion values comparable to those obtained with the standard procedure at 98 °C, obtaining dyed samples of good quality. The aim was to develop a laboratory method that could be transferred at industrial level, reducing both the energy consumption and fiber damage caused by the prolonged exposure to high temperature without the use of polluting auxiliary agents.Dyeings of wool fabrics were carried out in the temperature range between 60 °C and 80 °C using either mechanical or ultrasound agitation of the bath and coupling the two methods to compare the results. For each dyeing, the exhaustion curves of the dye bath were determined and the better results of dyeing kinetics were obtained with ultrasound coupled with mechanical stirring. Hence the corresponding half dyeing times, absorption rate constants according to Cegarra-Puente modified equation and ultrasonic efficiency were calculated in comparison with mechanical stirring alone. In the presence of ultrasound the absorption rate constants increased by at least 50%, at each temperature, confirming the synergic effect of sonication on the dyeing kinetics. Moreover the apparent activation energies were also evaluated and the positive effect of ultrasound was ascribed to the pre-exponential factor of the Arrhenius equation. It was also shown that the effect of ultrasound at 60 °C was just on the dye bath, practically unaffecting the wool fiber surface, as confirmed by the results of SEM analysis.Finally, fastness tests to rubbing and domestic laundering yielded good values for samples dyed in ultrasound assisted process even at the lower temperature. These results suggest the possibility, thanks to the use of ultrasound, to obtain a well equalized dyeing on wool working yet at 60 °C, a temperature process strongly lower than 98 °C, currently used in industry, which damages the mechanical properties of the fibers.     

流体控制方程的超声空化泡动力学模拟*

本文基于流体动力学控制方程和VOF模型,在FLUENT 14.5软件环境下对超声空化泡进行数值模拟。首先研究了超声空化泡一个周期内的形态变化,并且利用空化泡形态变化的最大面积、最小面积、膨胀时间、收缩时间等数值结果分析超声参数对空化效果的影响。同时探究了双频超声作用下空化泡运动的变化,计算结果表明:在其他条件相同的情况下,在1~5MPa范围内,超声声压幅值为3MPa时空化效果最好;当超声频率大于20kHz时,空化效果随着超声频率的增大而降低。对于频率相同的双频超声,较声压幅值为其两倍的单频超声有更好的空化效果;对于频率不同的双频超声,空化效果受到频率差的影响。     

Application of ultrasound technology in the drying of food products

This study presents a state-of-the-art overview on the application of ultrasound technology in the drying of food products, including the ultrasound pre-treatment and ultrasound assisted drying. The effect of main parameters and ultrasound technology on the drying kinetics and food quality were discussed. Inconsistencies were pointed out and analyzed in detail. Results showed that for ultrasound pre-treatment, the food products may lose or gain water and increase of ultrasonic parameters (sonication time, amplitude and ultrasound power) promoted the water loss or water gain. When ultrasound technology was applied prior to drying, an increase in drying kinetics was always observed, though some different results were also presented. For ultrasound assisted drying, the ultrasound power always gave a positive effect on the drying process, however, the magnitude of ultrasound improvement was largely dependent on the process variables, such as air velocity, air temperature, microwave power and vacuum pressure, etc. The application of ultrasound technology will somehow affect the food quality, including the physical and chemical ones. Generally, the ultrasound application can decrease the water activity, improve the product color and reduce the nutrient loss.     

Sonoprecipitation dispersion of ZnO nanoparticles over graphene oxide used in photocatalytic degradation of methylene blue in aqueous solution: Influence of irradiation time and power

In this paper, ZnO/Graphene Oxide (ZnO/GO) is synthesized via ultrasound assisted precipitation method and the effect of power and ultrasound time irradiation is studied on photocatalyst properties. The synthesized samples are used for methylene blue (MB) degradation as an organic water pollutant. Physicochemical properties of the samples are investigated by XRD, FESEM, EDX, BET-BJH, FTIR and DRS techniques. Moreover, pH_pzc of the sample with the best performance is calculated to study the effect of acidity on the photocatalyst efficiency in photocatalytic process. Ultrasound has a positive effect on photocatalyst performance that is because of its effect on distribution of particles and semiconductor band gap, but it has no effect on photostability of the nanocomposite. Sonication has modified distribution of particles by enhancing the active sites for oxidation process. Making structural gaps by ultrasound irradiation increases available surface area which has a similar effect on photocatalyst performance. Graphene oxide as electron collector and transporter prevents electron-hole recombination and it can be an acceptable reason for enhancement at photocatalyst performance. Finally, some of operational parameters such as pH, photocatalyst loading and dye concentration are investigated.     

Effects of multi-frequency power ultrasound on the enzymolysis and structural characteristics of corn gluten meal

The aim of this study was to investigate the effect of multi-frequency power ultrasound (sweeping frequency and pulsed ultrasound (SFPU) and sequential dual frequency ultrasound (SDFU)) on the enzymolysis of corn gluten meal (CGM) and on the structures of the major protein fractions (zein, glutelin) of CGM. The results showed that multi-frequency power ultrasound pretreatments improved significantly (P < 0.05) the degree of hydrolysis and conversion rate of CGM. The changes in UV–Vis spectra, fluorescence emission spectra, surface hydrophobicity (H₀), and the content of SH and SS groups indicated unfolding of zein and glutelin by ultrasound. The circular dichroism analysis showed that both pretreatments decreased α-helix and increased β-sheet of glutelin. The SFPU pretreatment had little impact on the secondary structure of zein, while the SDFU increased the α-helix and decreased the β-sheet remarkably. Scanning electron microscope indicated that both pretreatments destroyed the microstructures of glutelin and CGM, reduced the particle size of zein despite that the SDFU induced aggregation was observed. In conclusion, multi-frequency power ultrasound pretreatment is an efficient method in protein proteolysis due to its sonochemistry effect on the molecular conformation as well as on the microstructure of protein.     

Investigation of the effect of power ultrasound on the nucleation of water during freezing of agar gel samples in tubing vials

Nucleation, as an important stage of freezing process, can be induced by the irradiation of power ultrasound. In this study, the effect of irradiation temperature (−2 °C, −3 °C, −4 °C and −5 °C), irradiation duration (0 s, 1 s, 3 s, 5 s, 10 s or 15 s) and ultrasound intensity (0.07 W cm⁻², 0.14 W cm⁻², 0.25 W cm⁻², 0.35 W cm⁻² and 0.42 W cm⁻²) on the dynamic nucleation of ice in agar gel samples was studied. The samples were frozen in an ethylene glycol-water mixture (−20 °C) in an ultrasonic bath system after putting them into tubing vials. Results indicated that ultrasound irradiation is able to initiate nucleation at different supercooled temperatures (from −5 °C to −2 °C) in agar gel if optimum intensity and duration of ultrasound were chosen. Evaluation of the effect of 0.25 W cm⁻² ultrasound intensity and different durations of ultrasound application on agar gels showed that 1 s was not long enough to induce nucleation, 3 s induced the nucleation repeatedly but longer irradiation durations resulted in the generation of heat and therefore nucleation was postponed. Investigation of the effect of ultrasound intensity revealed that higher intensities of ultrasound were effective when a shorter period of irradiation was used, while lower intensities only resulted in nucleation when a longer irradiation time was applied. In addition to this, higher intensities were not effective at longer irradiation times due to the heat generated in the samples by the heating effect of ultrasound. In conclusion, the use of ultrasound as a means to control the crystallization process offers promising application in freezing of solid foods, however, optimum conditions should be selected.