Enhancing Hot Air Drying Efficiency through Electrostatic Field-Ultrasonic Coupling Pretreatment.

The drying of compact and biologically active materials presents significant challenges. In this study, we propose using electrostatic field-ultrasonic coupling pretreatment to enhance the drying efficiency of ginkgo fruits. We designed and constructed an experimental device to investigate the effects of ultrasonic power, pretreatment time, hot air drying temperature, and electrostatic field voltage on the moisture content of the fruits. We used the response surface methodology to identify optimal process conditions and further explored the kinetic model for the moisture content of the fruits under the pretreatment. The results showed that the optimal process parameters for electrostatic-ultrasound pretreatment and the drying of ginkgo fruits were: an electrostatic field voltage of 11.252 kV, an ultrasound power of 590.074 W, a pretreatment time of 32.799 min, and a hot air drying temperature of 85 °C. Under the optimized process conditions, the correlation between the moisture content of ginkgo fruits and the two-term drying kinetics model was the highest. After electrostatic-ultrasound coupling pretreatment, the drying rate of ginkgo fruits was significantly improved during hot air drying.

Dynamics of nonspherical bubble in compressible liquid under the coupling effect of ultrasound and electrostatic field.

A model for a nonspherical bubble in a compressible liquid under the coupling effect of ultrasound and electrostatic field was developed in this study. The following assumptions are made: (1) the bubble undergoes adiabatic oscillation; (2) the gravity of the liquid is negligible; (3) the bubble is insulating. If the speed of sound approaches infinity (c→∞), the equation set is reduced to the equation set for an incompressible liquid. We found that, under ultrasonic irradiation coupled with electric stress, a nonspherical bubble cannot oscillate steadily in the liquid. The bubble is bound to collapse during several cycles. The presence of electric stress reduces the surface tension at the bubble wall, which produces a larger maximum bubble-radius during the rarefaction cycle and a smaller minimum bubble-radius during the compression cycle. Consequently, during the collapse, both the gas pressure and the temperature in the bubble center increase substantially, if the bubble is exposed to both ultrasound and electrostatic field instead of ultrasound alone. In addition, the cavitation threshold of the bubble within an electrostatic field decreases significantly, compared to the bubble without an electrostatic field. In general, bubble cavitation occurs more easily and violently in the liquid after the introduction of an electrostatic field.

Ultrasound-synergized electrostatic field extraction of total flavonoids from Hemerocallis citrina baroni.

The total flavonoids from Hemerocallis citrina baroni are regarded as a green and natural health care product with many beneficial impacts on human health. In this study, ultrasound-synergized electrostatic field extraction (UEE) of the total flavonoids (TF) from H. citrina was investigated. Significant independent variables of the extraction, including the electrostatic field, ultrasonic power, ethanol concentration and extraction time, were optimized using the Box-Behnken (BB) method, and the optimal extraction conditions were obtained by response surface methodology (RSM). The extraction yield using UEE was compared with the yields obtained using only ultrasound extraction (UE) and water bath extraction (WE), using a UV-vis spectrophotometer. The best extraction yield of 1.536% using UEE was achieved under the following optimal conditions: electrostatic field of 7kV, ultrasonic power of 500W, ethanol concentration of 70% and extraction time of 20min. The optimal solid-liquid ratio (1:25g/mL) and extraction temperature (55°C) were determined by single factor experiments. Compared to other extraction methods, UEE not only increases the extraction yield of TF but also exhibits an excellent antioxidant activity in assays of the scavenging capacity for DPPH, hydroxyl and superoxide anion radicals. The availability of the UEE method can be supported by the ultrasonic cavitation effect, which plays the most important role in the UEE method. The electrostatic field can be regarded as a random disturbance for sonication, which can strengthen the cavitation effect and increase the cavitation yield. Moreover, the amount of iodine release in potassium iodide solution well validated the synergetic effect between the ultrasound and electrostatic field.

Ligusticum chuanxiong prevents ovariectomy-induced liver and vascular damage in rats.

Post-menopause, there is an increase in body weight, visceral adiposity, and risk of developing non-alcoholic fatty liver disease (NAFLD), which leads to various cardiovascular diseases (CVDs). Some natural products have proven useful for counteracting the detrimental effects of menopause. The rhizome of Ligusticum chuanxiong Hort. (LC) is a well-known medicinal herb widely used in Chinese communities for the treatment of CVDs. The hepatic and vascular protective effects of LC ethanolic extract under postmenopausal conditions were investigated on ovariectomized (OVX) rats supplemented with or without LC ethanolic extract (600 mg/kg body weight/day, p.o.) or 17ß-estradiol (1 mg/kg body weight/day, p.o.) for 12 weeks. The current findings demonstrated that consumption of LC ethanolic extract could reduce the body weight gain, improve serum lipid profile (lowering low density lipoprotein cholesterol but raising high density lipoprotein cholesterol), combat NAFLD, and protect vascular endothelium in the OVX rats. The beneficial effects of LC may be associated with its antioxidant or vasorelaxant compounds, which enhance the levels of hepatic antioxidant enzymes and up-regulate endothelial nitric oxide synthase mRNA expression, respectively. Taken together, LC may be a promising natural supplement for postmenopausal women to prevent NAFLD and CVDs.

[Comparison on extraction of volatile oils from Lithospermum erythrorhizon by different methods].

OBJECTIVE: To extract the volatile oils from Lithospermum erythrorhizon via ultrasound-enhanced sub-critical water extraction (USWE) and compare with ultrasound-enhanced solvent extraction (USE) and steam distillation extraction (SD). METHODS: The extraction yield of the volatile oils, the containing components of extract, the effect of scanvenging activities on free radical DPPH and reducing activities as well as the inhibitory on escherichia coli and staphylococcus aureus were investigated. RESULTS: The extraction yield of volatile oils by USWE, USE and SD were 2.39%, 1.93% and 0.62%, respectively, the extracts by three methods all contained six major components, but the extracts by SD and USE contained more impurities. The inhibitory effect on escherichia coli and staphylococcus aureus of the extract by SD and its reducing action were the best,but those by USWE were the worst. CONCLUSION: the extraction yield of volatile oils by USWE is the highest, and it contains less impurities based on the worst in reducing power and inhibitory effects.