Ultrasonics Sonochemistry最新文献

Blue honeysuckle (Lonicera caerulea L.) serves as a significant reservoir of polyphenol compounds. This impact of ultrasonication processing on the bioaccessibility of blue honeysuckle fruit puree during in vitro digestion was evaluated. The polyphenol compounds, antioxidant capacity and antiproliferative activity were measured, with a particular focus on determining the total proanthocyanidin content of the puree during digestion. The results revealed that the U300 W treatment significantly increased antioxidant content and enhanced the stability of antioxidant capacity, leading to stronger antiproliferative activity. A total of 33 compounds, including 14 phenolic acids, 5 flavanols, 1 flavanol-3-ol, 1 flavanone alcohol, 3 flavanones, 1 flavanone, and 8 non- polyphenols were found in both untreated and ultrasonicated puree during in vitro digestion. The untreated puree contained 22 compounds, while the ultrasonicated puree contained 33. Compared to untreated samples, ultrasonicated samples contained significantly higher levels of loganic acid, dihydrokaempferol, kaempferol derivatives, and plantagoside. Except for vanillic acid, citric acid, protocatechuic acid, and luteolin-4'-O-glucoside, the polyphenols showed a decreasing trend during oral-gastric-small intestinal-colon digestion. The U500 W ultrasonicated fruit puree exhibited the strongest antiproliferative activity. Overall, the results demonstrated that ultrasonication has the potential to enhance the bioaccessibility of antioxidant compounds and the antiproliferative activity of blue honeysuckle fruit puree.

A convenient and efficient method for undergraduate student experiments involves the one-pot synthesis of phenytoin from benzoin. This method utilized ultrasonic irradiation in the presence of basic catalyst at room temperature and atmospheric pressure, resulting in shortened reaction times, good yields, and excellent reproducibility. By employing a low-cost ultrasonic cleaner for ultrasonic irradiation in student experiments, the need for expensive equipment investment during the teaching process can be minimized. Consequently, this approach is suitable for widespread promotion and application in undergraduate education.

Ceramic coatings containing two-dimensional materials (2D materials) provide effective protection for light alloys during wear, significantly improving their anti-friction performance. MoS₂ has proven highly effective in enhancing the anti-friction performance of ceramic coatings, particularly when synthesized via plasma electrolytic oxidation (PEO). However, dislocation pinning due to the incoherent interfaces in MoS₂/TiO₂ coatings tends to cause localized stress concentrations and brittle fracture, requiring effectively improve nanomechanical properties by optimizing interface design. To address these issues, this study used ultrasonic-assisted PEO to disperse graphene oxide (GO), which provided more possibility for in-situ synthesis MoS₂, ultimately resulting in MoS₂ with modified interlayer spacing. The change in interlayer spacing induced dislocation evolution at incoherent interface, leading to dual interface formation. At MoS₂ (0.534 nm)/TiO₂ interface: dislocation dipoles evolve to create considerable distortion, facilitating releasing shear stresses and inhibiting crack propagations. This process is followed by dislocation annihilation, keeping to stable interfacial bonding. Additionally, the others form strong dislocation pinning to obstruct dislocation slip and enhancing deformation resistance at MoS₂ (0.227 nm)/TiO₂ interface. The combined effects of dual interfacial enhancements resulted in a 90.0 % reduction in friction coefficients of the MoS₂/GO/TiO₂ coating compared to the traditional ceramic coating. This facile technique provides a new strategy to fabricate self-lubricating ceramic coatings on light alloys, while the introduction of ultrasound during PEO offers valuable guidance for applying ultrasound in the synthesis of 2D materials.

The present study was aimed to determine the effect of ultrasound pretreatment and different drying methods viz sun drying, solar drying, cabinet drying, vacuum drying, microwave assisted drying and freeze drying on physicochemical, phytochemical activity, rehydration ratio and drying time of the purslane. The purslane was ultrasonicated for 15, 30, 45 and 60 min following by drying. The ultrasound pretreatment (60 min) combined with freeze drying retained the highest antioxidants (95.59 %), phenolic content (7.85 mgGAE/100 g), total carotenoid content (99.74 mg/100 g), ascorbic acid (399.94 mg/100 g) and rehydration ratio (6.80). Moreover, the same combination revealed higher L and a* values when compared with other drying methods. However, the purslane pretreated with ultrasonication for 60 min and then dried via microwave took less time for drying. This study suggests that Ultrasound pretreatment (60 min) followed by freeze drying is recommended for preserving the nutritional and functional properties of purslane. It could be scaled up for commercial applications in the functional food and nutraceutical industries, where high-quality preservation is crucial.

This paper explores the effect of ultrasound (US) assisted plasma-activated water (PAW) or deionized water (DW) pretreatment combined with electrohydrodynamics (EHD) on the drying of yam. The activity characteristics of four pretreatments (plasma activated water combined with ultrasound (PAW + US), plasma activated water (PAW), deionized water combined with ultrasound (DW + US), and deionized water (DW) (control)) and their effects on drying characteristics, rehydration rate, color, reducing sugars, total phenols, infrared spectra, and volatile compositions of yam under EHD drying process were investigated. The results showed that the media pretreaded by ultrasound (US) combined with plasma-activated water (PAW) has lower media of pH (53.84 % lower than that of US + DW), higher nitrite ion concentration (311 times over US + DW), higher oxidation reduction potential (50.58 % higher than that of US + DW), and higher electrical conductivity (99.29 times over US + DW). And ultrasonic pretreatment (US) combined with plasma-activated water (PAW) drying resulted in faster drying, better rehydration rate, higher brightness L * (18.35 % higher than that of US + DW) and whiteness (1.1 % higher than that of US + DW), and retention of more reducing sugars (10.96 % higher than that of US + DW) and total phenols (14.04 % higher than that of US + DW), and a higher variety and content of volatile components. This provides an experimental and theoretical basis for the application of ultrasonic (US) combined with plasma-activated water (PAW) pretreatment to electrohydrodynamic drying.

This study presents an experimental investigation of the influence of MB concentration on the resonance frequency of lipid-coated microbubbles (MBs). Expanding on theoretical models and numerical simulations from previous research, this work experimentally investigates the effect of MB size on the rate of resonance frequency increase with concentration, a phenomenon observed across MBs with two different lipid compositions: propylene glycol (PG) and propylene glycol and glycerol (PGG). Employing a custom-designed ultrasound attenuation measurement setup, we measured the frequency-dependent attenuation of MBs, isolating MBs based on size to generate distinct monodisperse sub-populations for analysis. The resonance frequency of MBs was determined by identifying the attenuation peak in the broadband attenuation ultrasound attenuation measurements. Our experimental findings confirm that larger MBs (≈2.1μm) demonstrate a more significant shift in resonance frequency (≈ 5 MHz, ≈ 40%) as a function of MB concentration. In contrast, smaller MBs (≈1.3μm) show a minor shift in the resonant frequency (≈ 1.8 MHz, ≈ 8%), underlining the importance of size in determining acoustic behavior compared to changes in the lipid shell properties. Additionally, we observed that resonance frequency increase with concentration reaching a saturation point at higher concentrations. This plateau occurs at higher concentrations for larger MBs (≈2.1μm), while smaller MBs (≈1.6μm and ≈1.3μm) reach this saturation point at lower concentrations. Furthermore, the study highlights the small effect of bubble-bubble interactions on the resonance frequency of MB populations, particularly at lower MB concentrations and for smaller MBs. This insight is important for applications utilizing MB clusters, such as contrast-enhanced ultrasound imaging and MB-mediated therapies. While both size and lipid shell composition influence resonance frequency, MB size has a more significant effect. In conclusion, our findings affirm the need to consider both MB size and concentration when utilizing MBs for clinical and industrial ultrasonic applications.

Allium chinense G. Don waste (ACGD) has an abundance of polysaccharides (ACGDP). Therefore, in this study, a method for extraction of ACGDP from ACGD by ultrasonic-assisted hot water extraction (UAE) based on ultrasonic cleaning equipment was developed. It was compared with hot water extraction (HWE) in terms of efficiency, energy consumption, and carbon emissions. Then, the mechanism of efficient extraction of ACGDP by UAE was further investigated. Finally, the physicochemical properties and in vitro activity of ACGDP were evaluated. The results suggested that the optimal conditions of UAE were temperature 53 ℃, time 34 min, power 280 W, liquid-solid ratio 22 mL/g, and the yield of ACGDP was 30.08 ± 0.21 %. Compared with HWE, UAE yield was increased by 30.10 %, time was shortened by 71.50 %, energy consumption was reduced by 77.33 %, and CO₂ emission was reduced by 82.56 %. UAE can efficiently extract ACGDP by changing the composition of the cell wall, destroying the microstructure, and reducing the particle size. In addition, ACGDP had better thermal stability and antioxidant activity, and exhibited positive hypoglycemic activity. Overall, this study provided a theoretical basis and new insights into the efficient extraction mechanism of UAE and the high-value utilization of ACGD waste.

The effect of ultrasound and plasma pretreatment on freeze-dried kiwifruit crisps was investigated in this study. Using unpretreated kiwifruit as a control group (CG), the effects of ultrasound (US), plasma-activated water (PAW), ultrasound combined with plasma-activated water (UPAW), plasma-jet (PJ), and ultrasound combined with plasma-jet (UPJ) on the quality of vacuum freeze-dried kiwifruit were investigated. The results showed that all the pretreatments could change the microstructure of the crisps. The microstructure of dried kiwifruit after pretreatment showed more porous structures with different number and size compared to the CG group. The largest pore structure was observed in the UPAW group which had the highest crispness. The activity of water (Aw) of all pretreatment samples was significantly lower than the CG group (P < 0.05). In addition, the UPAW group had the lowest moisture content (4.85 %) and the highest rehydration ratio (288.03 %), indicating the better drying characteristics. Furthermore, the UPAW pretreatment sample showed good appearance with the highest brightness and the lowest color difference (ΔE). The total sugars and total phenolics of the UPAW pretreatment sample were mostly retained, and its flavor was the closest to the CG group. The combination of US and PAW promoted the formation of a larger cavity structure and improved the drying characteristics and physicochemical properties of dried kiwifruit crips. However, all the pretreatments resulted in a decrease in antioxidant capacity, with the least decreasing of the US group and the most decreasing of the UPAW group. Correlation analysis showed that the chlorophyll and vitamin C were the major antioxidants in dried kiwifruit crips. The mechanism of decrease in antioxidant activity of pretreatment, especially UPAW, should be discussed and the effective measure to reduce the change in chlorophyll and vitamin C should be taken in future research.

We investigate experimentally and numerically the interaction between a spherical cavitation bubble and a wall-bounded toroidal cavitation bubble. We demonstrate that shock wave focusing following toroidal bubble initiation induces the formation of micro-jets that pierce the spherical bubble in the torus-axis direction away from the surface, strongest in the anti-phase scenario. The velocity of micro-jets is determined by the initial standoff distance of the spherical bubble from the wall and thus from the toroidal bubble, with peak jet velocities approaching 1000m/s. The micro-jets are triggered by the complex interaction between the torus shock wave and the surface of the spherical bubble. Additionally, the formation of secondary cavitation appears to significantly enhance the micro-jets compared to scenarios without secondary cavitation. Following the formation of micro-jets, a subsequent broad jet pierces the spherical bubble, marking the onset of its collapse. After the collapse, we observe an amplified rebound phase resulting in a more than twofold increase of the bubble volume compared to the initial bubble.