超声诱导对家蝇幼虫基因组DNA影响的谱学研究

超声诱导3日龄家蝇幼虫后提取对照和处理组的基因组DNA,利用紫外光谱、荧光光谱、红外光谱、核磁共振谱对其结构进行分析,并利用PCR对基因组中attacin基因的3′端序列进行测序比较。结果表明,超声诱导能够影响家蝇幼虫基因组DNA的二级结构和碱基堆积状态,进而在DNA复制时造成碱基错配最终导致DNA序列发生改变,但是超声诱导对DNA的化学基团和化学键没有明显的影响。     

Ultrasound-assisted Maillard reaction of ovalbumin/xylose: The enhancement of functional properties and its mechanism

This study aims to optimize the ultrasound treatment conditions for enhancing the degree of glycation (DG) of ovalbumin (OVA)-xylose conjugates through Maillard reaction and investigate the correlation between DG and functional properties affected by structural changes. The structural and functional properties of classical heating OVA, glycated OVA, ultrasonic treated OVA, and ultrasound-assisted glycated OVA were investigated to explore the interaction mechanism of ultrasound treatment on foaming and emulsifying properties improvement. Results indicated that the ultrasound assistance increased free sulfhydryl content, surface hydrophobicity and particle size of OVA-xylose conjugates, and thus enhancing the surface properties, which were strongly linear correlated with DG under different glycation parameters (pH, xylose/OVA ratio, heating time). Additionally, circular dichroism spectroscopy analysis revealed that ultrasound promoted the conversion of α-helices to β-sheets and unfolded structures, which was consistent with the formation of short amyloid-like aggregates that observed by atomic force microscopy phenomenon. Overall, our study provides new insights into the effects of ultrasound treatment on Maillard-induced protein functional properties enhancement, which may be a new strategy to tune the DG and functionality of protein-saccharide grafts during ultrasound processing.     

Contribution of ultrasound and slightly acid electrolytic water combination on inactivating Rhizopus stolonifer in sweet potato

Effects of ultrasound (US, 300, 400, and 500 W) and slightly acidic electrolyzed water (SAEW, 10, 30, and 50 mg/L) combination on inactivating Rhizopus stolonifer in sweet potato tuberous roots (TRs) were investigated. US at 300, 400, and 500 W simultaneous SAEW with available chlorine concentration of 50 mg/L at 40 and 55 °C for 10 min significantly inhibited colony diameters (from 90.00 to 6.00–71.62 mm) and spores germination (p < 0.05). US + SAEW treatment could destroy cell membrane integrity and lead to the leakage of nucleic acids and proteins (p < 0.05). Scanning and transmission electron microscopy results showed that US + SAEW treatment could damage ultrastructure of R. stolonifer, resulted in severe cell-wall pitting, completely disrupted into debris, apparent separation of plasma wall, massive vacuoles space, and indistinct intracellular organelles. US500 + SAEW50 treatment at 40 and 55 °C increased cell membrane permeability, and decreased mitochondrial membrane potential of R. stolonifer. In addition, US500 + SAEW50 at 40 °C and US300 + SAEW50 at 55 °C controlled R. stolonifer growth in sweet potato TRs during 20 days of storage, suggesting effective inhibition on the infection of R. stolonifer. Therefore, US + SAEW treatment could be a new efficient alternative method for storing and preserving sweet potato TRs.     

EPR and NMR study of molecular components mobility and organization in goat milk under ultrasound treatment

The effect of ultrasound treatment on molecular mobility and organization of the main components in raw goat milk was studied by EPR and NMR spectroscopies. NMR relaxation studies showed an increase in the spin–lattice T₁ and spin–spin T₂ relaxation times in goat milk products (cream, anhydrous fat) and change in the diffusion of proton-containing molecules during ultrasound treatment. The diffusion became more uniform and could be rather accurately approximated by one effective diffusion coefficient D_eff, which indicates homogenization of goat milk components, dispersion of globular and supermicellar formations under sonication. EPR studies have shown that molecular mobility and organization of hydrophobic regions in goat milk are similar to those observed in micellar formations of surfactants with a hydrocarbon chain length C12–C16. Ultrasound treatment did not affect submicellar and protein globule organization. Free radicals arising under ultrasound impact of milk reacted quickly with components of goat milk (triglycerides, proteins, fatty acids) and were not observed by spin trapping method.     

A rapid ultrasound-promoted Horner–Wadsworth–Emmons reaction for the preparation of ferrocene derivatives. Application to ferrocene-modified ITO electrodes

The Horner–Wadsworth–Emmons reaction of ferrocenecarboxaldehyde with various phosphonate-stabilized carbanions has been performed under ultrasound irradiation. The reaction time at ambient temperature was considerably shortened (5–15 min) compared to nonsonicated conditions requiring often refluxing for 6–24 h. Control of the reaction time can be achieved by tuning the base strength in different solvents. This method was successfully applied to the preparation of various 2-substituted vinylferrocenes. The as-prepared (E)-2-ferrocenylvinylphosphonic acid was used to modify ITO electrodes to form redox-active functionalized ITO electrodes which have been characterized by means of electrochemical techniques.     

Ultrasound-assisted biomass valorization to industrial interesting products: state-of-the-art,perspectives and challenges

Nowadays, the application of ultrasound (US) energy for assisting the lignocellulosic biomass and waste materials conversion into value-added products has dramatically increased. In this sense, this review covers theoretical aspects, promising applications, challenges and perspectives about US and its use for biomass treatment. The combination of US energy with a suitable reaction time, temperature and solvent contributes to the destruction of recalcitrant lignin structure, allowing the products to be used in thermochemical and biological process. The main mechanisms related to US propagation and impact on the fragmentation of lignocellulosic materials, selectivity, and yield of conversion treatments are discussed. Moreover, the synergistic effects between US and alternative green solvents with the perspective of industrial applications are investigated. The present survey analysed the last ten years of literature, studying challenges and perspectives of US application in biorefinery. We were aiming to highlight value-added products and some new areas of research.     

Effects of ultrasonic treatment on color,carotenoid content,enzyme activity,rheological properties,and microstructure of pumpkin juice during storage

Freshly squeezed pumpkin juice (Cucurbita moschata D.) was sonicated at various power levels at a constant frequency of 25 kHz and a treatment time of 10 min. Samples were stored in the dark for 0, 4, 8, and 12 days at 4 °C and were subsequently analyzed. The combined effects of power level and storage period on color parameters, carotenoid content, particle size distribution, cloud value, rheological characteristics, and microstructure were investigated. The results showed ultrasonic-treated samples had little effect on carotenoid content, cloud value, particle size distribution, and polydispersity during storage compared to those of the untreated samples. The L^⁎, a^⁎, b^⁎, and C* values decreased significantly during 8–12 days of storage, resulting in a significant increase in ΔE, especially 400 W/10 min-treated samples. Meanwhile, the enzyme activity and rheological properties increased significantly on storage days 8–12. However, the microstructure of all samples did not change significantly during storage. Based on these results, during the storage period, the physical and chemical properties of 400 W/10 min-ultrasonic treated pumpkin juice were retained more than those in the untreated pumpkin juice. Therefore, ultrasonic treatment has broad application prospects in preserving bioactive substances and physicochemical properties and improving the storage life of fresh pumpkin juice.     

Ultrasound-assisted fabrication of Ti3C2Tx MXene toward enhanced energy storage performance

Ti₃C₂Tx MXenes are normally fabricated by removal of main group element from the corresponding transition metal carbides, and they have been actively studied due to their superior energy storage performance. However, the low efficiency in removal of main group element (named as chemical etching) has significantly limited the application of MXene or MXene-related materials. Herein, we demonstrated an ultrasound-assisted approach to synthesize Ti₃C₂Tx MXene material by using Ti₃AlC₂ as the precursor. The experimental results indicate that the efficiency of chemical etching of Ti₃AlC₂ was dramatically promoted by ultrasound. The etching time was greatly shortened to 8 h while typically 24 h is sufficient in dilute hydrofluoric acid. Particularly, the high etching efficiency was achieved by using 2% hydrofluoric acid under the aid of ultrasound, which is lower in concentration than those reported in the previous literature. The specific capacitance of the 8 h sonicated sample is 155F/g, which is much higher than that of the un-sonicated sample prepared under the same experimental conditions. Additionally, the specific capacitance retention of the prepared 8 h sonicated sample was 97.5% after 20,000 cycles of charging/discharging, exhibiting an outstanding energy storage stability compared with the materials reported in previous literatures. It was proposed that removal of AlF₃ from the surface of the etched particles was significantly promoted and the hydrogen bonds between the terminations of two different adjacent layers were broken by the acoustic cavitation effect of ultrasound.     

Osmotic dehydration and convective drying of kiwifruit (Actinidia deliciosa) – The influence of ultrasound on process kinetics and product quality

The aim of this study was to assess the impact of ultrasound on two subsequent processes – initial osmotic dehydration and convective drying of kiwifruit (Actinidia deliciosa). The effect of ultrasound (at a frequency of 25 kHz) was assessed both in terms of process kinetics and product quality. During the study, three different osmotic agents were used – erythritol, sorbitol, and sucrose – in an aqueous solution at a concentration of 50% (w/w). The essential kinetic parameters were analyzed – water loss and increase of dry matter during osmotic dehydration, and evolution of moisture content and temperature of samples during convective drying (drying curves). Product quality was assessed on the basis of color, water activity, and content of relevant bioactive components – polyphenols and carotenoids. It was found that the application of ultrasound during osmotic dehydration resulted in higher water loss and solid gain. This surely results from the phenomena occurring during the propagation of the elastic waves in the liquid medium (mainly related to cavitation) and enhancement of the mass transfer. The use of ultrasound during convective drying also had a positive effect on the kinetics of this process. In most cases, during the ultrasonically assisted drying operations, a significant increase in drying rate was observed, leading to a reduction in drying time. This may be due to the intensification of both heat and mass transfer as a result of the mechanical and thermal effects of ultrasound. The assessment of product quality showed that the use of sugar alcohols was a good alternative to sucrose, and ultrasound-assisted convective drying increased the retention of valuable carotenoids and polyphenols. Moreover, in all dried kiwifruit slices, water activity was below 0.6, which can guarantee the microbiological stability of the tested samples.     

Simulations of a full sonoreactor accounting for cavitation

In spite of the increasing interest in ultrasound processing applications, industrial scale-up remains limited, in particular by the unavailability of predictive computer tools. In this study, using a previously published model of cavitating liquids implementable as a non-linear Helmholtz equation, it is shown that a full sonoreactor can be modelled and simulated. The model includes the full transducer and the vibrations of the vessel walls, using the physics of elastic solids and piezo-electricity. The control-loop used by the generator to set the optimal frequency is also accounted for. Apart from the geometry, the unique input of the model is the current feeding the transducer whereas the dissipated electrical power, transducer complex impedance and working frequency are available as outputs. The model is put to the test against experiments realized in different geometries, varying either the input current or the transducer immersion depth. Despite the overestimation of the power dissipated in the liquid, the evolution of the acoustic load in both cases is reasonably well reproduced by simulation, which partially validates the method used.