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Ultrasonics sonochemistry
Butterworth Heinemann
Ultrasonics sonochemistry

Butterworth Heinemann

1350-4177

Ultrasonics sonochemistry/Journal Ultrasonics sonochemistrySCICCRISTPEI
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    Ultrasound irradiation alters the spatial structure and improves the antioxidant activity of the yellow tea polysaccharide

    Wang, HaisongChen, JinranRen, PengfeiZhang, Yiwen...
    11页
    查看更多>>摘要：In this study, the impact of ultrasound irradiation on the structural characteristics and antioxidant properties of yellow tea polysaccharides with different molecular weights (Mw) were investigated. Native yellow tea polysaccharide containing YTPS-3N, YTPS-5N and YTPS-7N were prepared through precipitation with ethanol at various concentrations of 30%, 50%, and 70%, respectively, and irradiated with high intensity ultrasound (20 kHz) for 55 min to yield yellow tea polysaccharide including YTPS-3U, YTPS-5U and YTPS-7U. The molecular weight (Mw) of YTPS-3N (from 37.7 to 15.1 kDa) and YTPS-5N (from 14.6 to 5.2 kDa) sharply decreased upon ultrasound irradiation, coincidentally particle size (Zavg) was also significantly reduced for YTPS-3N (40%), YTPS-5N (48%) and YTPS-7N (54%). The high-performance liquid chromatography and Fourier transforminfrared spectroscopy analysis revealed a partial degradation of native yellow tea polysaccharide treated with ultrasound, though the monosaccharide composition was not altered. Furthermore, changes in morphology and the breakdown of native yellow tea polysaccharide upon irradiation was confirmed with the circular dichroism spectrum, atomic force and scanning electron microscopy. As a consequence, irradiation of yellow tea polysaccharide increased free radical scavenging activity with YTPS-7U exhibiting the highest levels of 2, 2-diphenyl1-picrylhydrazyl free radical, superoxide and hydroxyl radicals scavenging activity. These results suggest that the alteration of the spatial structure of yellow tea polysaccharide can enhance its antioxidant activity which is an important property for functional foods or medicines.
      原文链接:
    • NSTL
    • Elsevier

    Sonocatalytic degradation of EDTA in the presence of Ti and Ti@TiO2 nanoparticles

    El Hakim, SaraChave, TonyNikitenko, Sergey I.
    7页
    查看更多>>摘要：The sonocatalytic degradation of EDTA (C-0 = 5 10(-3) M) in aqueous solutions was studied under 345 kHz (P-ac = 0.25 W mL(-1)) ultrasound at 22-51 degrees C, Ar/20%O-2, Ar or air, and in the presence of metallic titanium (Ti-0) or core-shell Ti@TiO2 nanoparticles (NPs). Ti@TiO2 NPs have been obtained using simultaneous action of hydrothermal conditions (100-214 degrees C, autogenic pressure P = 1.0-19.0 bar) and 20 kHz ultrasound, called sonohydrothermal (SHT) treatment, on Ti-0 NPs in pure water. Ti-0 is composed of quasi-spherical particles (30-150 nm) of metallic titanium coated with a metastable titanium suboxide Ti3O. SHT treatment at 150-214 degrees C leads to the oxidation of Ti3O and partial oxidation of Ti-0 and formation of nanocrystalline shell (10-20 nm) composed of TiO2 anatase. It was found that Ti-0 NPs do not exhibit catalytic activity in the absence of ultrasound. Moreover, Ti-0 NPs remain inactive under ultrasound in the absence of oxygen. However, significant acceleration of EDTA degradation was achieved during sonication in the presence of Ti-0 NPs and Ar/ 20%O-2 gas mixture. Coating of Ti-0 with TiO2 nanocrystalline shell reduces sonocatalytic activity. Pristine TiO2 anatase nanoparticles do not show a sonocatalytic activity in studied system. Suggested mechanism of EDTA sonocatalytic degradation involves two reaction pathways: (i) sonochemical oxidation of EDTA by OH center dot/HO2 center dot radicals in solution and (ii) EDTA oxidation at the surface of Ti-0 NPs in the presence of oxygen activated by cavitation event. Ultrasonic activation most probably occurs due to the local heating of Ti-0/O-2 species at cavitation bubble/solution interface.
      原文链接:
    • NSTL
    • Elsevier

    Nondestructive monitoring, kinetics and antimicrobial properties of ultrasound technology applied for surface decontamination of bacterial foodborne pathogen in pork

    Bonah, ErnestHuang, XingyiYang HongyingAheto, Joshua Harrington...
    11页
    查看更多>>摘要：In this study, electronic nose (E-nose) and Hyperspectral Imaging (HSI) was employed for nondestructive monitoring of ultrasound efficiency (20KHZ) in the inactivation of Salmonella Typhimurium, and Escherichia coli in inoculated pork samples treated for 10, 20 and 30 min.
      原文链接:
    • NSTL
    • Elsevier

    Ultrasound freeze-thawing style pretreatment to improve the efficiency of the vacuum freeze-drying of okra (Abelmoschus esculentus (L.) Moench) and the quality characteristics of the dried product

    Xu, XinZhang, LeiFeng, YabinZhou, Cunshan...
    11页
    查看更多>>摘要：Vacuum freeze-drying is a new and high technology on agricultural product dehydrating dry, but it faces the high cost problem caused by high energy consumption. This study investigated the effect of ultrasound (US), freeze-thawing (including the freeze-air thawing (AT), freeze-water thawing (WT), freeze-ultrasound thawing (UST), and freeze-air ultrasound thawing (AT + US)) pretreatments on the vacuum freeze-drying efficiency and the quality of dried okra. The results indicated that the application of ultrasound and different freeze-thawing pretreatments reduced the drying time by 25.0%-62.50% and the total energy consumption was 24.28%-62.35% less. The AT pretreatment reduced the time by of okra slices by 62.50% and the total energy consumption was 62.35% less. The significant decrease in drying time was due to a change in the microstructure caused by pretreatment. Besides, the okra pretreated with the US retained most of the quality characteristics (flavor, color, hardness, and frangibility) among all methods, while, AT + US had the most changeable characteristics in quality, which is deprecated in our study. The okra pretreated with the US and AT, separately, had the best dry matter content loss (9.008%, 5.602%), lower chlorophyll degradation (5.05%, 5.44% less), and higher contents of total phenolics, total flavonoids, and pectin, with strong antioxidant capacity, compared to other methods. The pretreatments did not have a large effect on the functional groups and the structure of pectin, but slightly affected the viscosity. It can be concluded that AT and US pretreatment methods are better than others.
      原文链接:
    • NSTL
    • Elsevier

    Acoustic vibrational resonance in a Rayleigh-Plesset bubble oscillator

    McClintock, P. V. E.Omoteso, K. A.Roy-Layinde, T. O.Laoye, J. A....
    18页
    查看更多>>摘要：The phenomenon of vibrational resonance (VR) has been investigated in a Rayleigh-Plesset oscillator for a gas bubble oscillating in an incompressible liquid while driven by a dual-frequency force consisting of high-frequency, amplitude-modulated, weak, acoustic waves. The complex equation of the Rayleigh-Plesset bubble oscillator model was expressed as the dynamics of a classical particle in a potential well of the Lienard type, thus allowing us to use both numerical and analytic approaches to investigate the occurrence of VR. We provide clear evidence that an acoustically-driven bubble oscillates in a time-dependent single or double-well potential whose properties are determined by the density of the liquid and its surface tension. We show both theoretically and numerically that, besides the VR effect facilitated by the variation of the parameters on which the high-frequency depends, amplitude modulation, the properties of the liquid in which the gas bubble oscillates contribute significantly to the occurrence of VR. In addition, we discuss the observation of multiple resonances and their origin for the double-well case, as well as their connection to the low frequency, weak, acoustic force field.
      原文链接:
    • NSTL
    • Elsevier

    Experimental investigation of flow boiling heat transfer enhancement under ultrasound fields in a minichannel heat sink

    Yu, FanLuo, XiaopingHe, BolinXiao, Jian...
    16页
    查看更多>>摘要：Ultrasound is considered to be an effective active heat transfer enhancement method, which is widely used in various fields. But there is no clear understanding of flow boiling heat transfer characteristics in micro/minichannels under ultrasonic field since the studies related are limited up to now. In this paper, a novel minichannel heat exchanger with two ultrasonic transducers inside the inlet and outlet plenum respectively is designed to experimentally investigate the impacts of ultrasound on flow boiling heat transfer enhancement in a minichannel heat sink. Flow visualization analyses reveal that ultrasound can promote rapid bubble motion, bubble detachment from heating wall surface and thereby new bubble generation, and decrease the length of confined bubble. Furthermore, the flow boiling experiments are initiated employing working fluid R141b at different ultrasonic parameters (e.g., frequency, power, angle of radiation) and heat flux under three types of ultrasound excitations: no ultrasound (NU), single inlet ultrasound (IU), inlet and outlet ultrasound (IOU). The results indicate that ultrasound has obvious augmentation effects on flow boiling heat transfer even though the intensification effects will be limited with the heat flux increases. The higher ultrasonic power, the lower ultrasonic frequency and the higher ultrasonic radiation angle, the better intensification efficiency. The maximum enhancement ratio of have in the saturated boiling section reaches 1.88 at 50 W, 23 kHz and 45 degrees under the experimental conditions. This study will be beneficial for future applications of ultrasound on flow boiling heat transfer in micro/mini-channels.
      原文链接:
    • NSTL
    • Elsevier

    Ultrasound assisted extraction (UAE) of bioactive compounds from fruit and vegetable processing by-products: A review

    Kumar, KshitizSrivastav, ShivmurtiSharanagat, Vijay Singh
    11页
    查看更多>>摘要：Growing fruit and vegetable processing industries generates a huge amount of by-products in the form of seed, skin, pomace, and rind containing a substantial quantity of bioactive compounds such as polysaccharides, polyphenols, carotenoids, and dietary fiber. These processing wastes are considered to be of negligible value compared to the processed fruit or vegetable due to lack of sustainable extraction technique. Conventional extraction has certain limitations in terms of time, energy, and solvent requirements. Ultrasound assisted extraction (UAE) can extract bioactive components in very less time, at low temperature, with lesser energy and solvent requirement. UAE as a non-thermal extraction technique is better equipped to retain the functionality of the bioactive compounds. However, the variables associated with UAE such as frequency, power, duty cycle, temperature, time, solvent type, liquid-solid ratio needs to be understood and optimized for each by-product. This article provides a review of mechanism, concept, factor affecting extraction of bioactive compounds with particular focus on fruit and vegetable by-products.
      原文链接:
    • NSTL
    • Elsevier

    The Gilmore-NASG model to predict single-bubble cavitation in compressible liquids

    Denner, Fabian
    6页
    查看更多>>摘要：The Gilmore model is combined with the Noble-Abel-stiffened-gas (NASG) equation of state to yield a simple model to predict the expansion and collapse of spherical bubbles based on real gas thermodynamics. The NASG equation of state resolves the temperature inaccuracy associated with the commonly employed Tait equation of state for liquids and, thus, can provide a consistent description of compressible and thermal effects of the bubble content and the surrounding liquid during cavitation. After a detailed derivation of the proposed Gilmore-NASG model, the differences between the classical Gilmore-Tait model and the proposed model are highlighted with results of single-bubble cavitation related to bubble collapse and driven by an acoustic excitation in frequency and amplitude regimes relevant to sonoluminescence, high-intensity focused ultrasound and shock wave lithotripsy. Especially for rapidly and violently collapsing bubbles, substantial differences in the bubble behaviour can be observed between the proposed Gilmore-NASG model and the classical Gilmore-Tait model. The ability of the Gilmore-NASG model to simultaneously predict reliable pressure and temperature values in gas, vapour and liquid, makes the proposed model particularly attractive for sonochemistry and biomedical applications.
      原文链接:
    • NSTL
    • Elsevier

    Flow-mode water treatment under simultaneous hydrodynamic cavitation and plasma

    Abramov, Vladimir O.Abramova, Anna V.Cravotto, GiancarloNikonov, Roman V....
    9页
    查看更多>>摘要：Over the last two decades, the scientific community and industry have made huge efforts to develop environmental protection technologies. In particular, the scarcity of drinking water has prompted the investigation of several physico-chemical treatments, and synergistic effects have been observed in hyphenated techniques. Herein, we report the first example of water treatment under simultaneous hydrodynamic cavitation and plasma discharge with the intense generation of radicals, UV light, shock waves and charged particles. This highly reactive environment is well suited to the bulk treatment of polluted water (i.e. E. coli disinfection and organic pollutant degradation). We have developed a new prototype and have efficiently applied this hybrid technology to water disinfection and the complete degradation of methanol in water with the aim of demonstrating its scalability. We have analyzed the mechanisms of water disinfection under the abovementioned conditions and verified them by measuring cavitation noise spectra and plasma emission spectra. We have also used the degradation of textile dyes and methanol solutions as an indicator for the formation of radicals.
      原文链接:
    • NSTL
    • Elsevier

    Effects of sonication on the in vitro digestibility and structural properties of buckwheat protein isolates

    Jin, JianOkagu, Ogadimma D.Yagoub, Abu ElGasim AhmedUdenigwe, Chibuike C....
    9页
    查看更多>>摘要：The present work investigated the effects of sonication at different amplitudes and durations on the in vitro digestibility of buckwheat protein isolates (BPIs). The conformation, particle size and microstructures of the BPIs were also studied to explicate the possible mechanisms of the sonication-induced changes. The results showed that sonication conditions of 20 kHz, pulsed on-time 10 s, off-time 5 s, amplitude of 60% and duration of 10 min (SA6T10) improved the digestibility of BPIs from 41.4% (control) to 58.2%. The tertiary structure analysis showed that sonication exposed the hydrophobic core buried inside the protein molecules and broke the intramolecular crosslinks, based on the increase in the surface hydrophobicity and intrinsic fluorescence and the decrease in the disulphide content. The secondary structure analysis showed that SA6T10 decreased the content of beta-turn and beta-sheet by 40.9% and 22.4%, respectively, and increased the content of anti-parallel beta-sheet, random coil, and alpha-helix by 40.9%, 30.6%, and 25.5%, respectively. The particle size of the control BPIs (427.7 +/- 76.7 nm) increased to 2130.8 +/- 356.2 nm in the SA6T10 sonicated sample with a corresponding decrease in the polydispersity index from 0.97 +/- 0.04 to 0.51 +/- 0.13. Moreover, scanning electron microscopy indicated that sonication broke the macroparticles into smaller fragments and changed the surface state of the proteins. Taken together, sonication has proven to be a promising approach for improving the digestibility of buckwheat proteins, which can be explored as a source of plant-based alternative protein for food applications.
      原文链接:
    • NSTL
    • Elsevier