Atmospheric pressure plasma jet (APPJ) is a promising technique for the sterilization of pathogenic microorganisms in an ambient environment. In this work, a helium-APPJ was generated by double dielectric barrier discharge and applied to the sterilization of model microorganism in air and water. Discharge characteristics (including waveform and frequency of applied voltage), jet properties (such as feed gas flow rate, jet length, thermal effect, and optic emission spectra), and sterilization performance (in terms of clear/sterilized area, size of plaques, and sterilization efficiency) were investigated. Homogeneous helium plasma jet was generated in an energy-efficient way (18 kHz, 6 kV, 0.08 W) with a 19 mm jet and limited heating. The He-APPJ achieved good sterilization performances within very short treatment time (as short as 30 s). For surface sterilization, the area of clear zone and size of the plaque were 1809 mm2 and 48 mm, respectively, within 5 min treatment. For water sterilization, 99.8% sterilization efficiency was achieved within 5 min treatment. The optic emission spectra suggest that active species such as excited molecules, ions, and radicals were produced in the He-APPJ. The as-produced active species played important roles in the sterilization process.
Microorganisms are widely distributed in the living environment of human, animals and plants. Some of the microorganisms are harmful for their pathogenic effects. Non-thermal plasma technology, especially, the atmospheric pressure plasma jet, is considered to be one of the promising technologies for sterilization. This work proposes a double-dielectric barrier discharge reactor for Ar plasma jet generation. Charteristics of discharge and temperature thermogram of plasma jet are investigated by the means of U-P curve and infrared image, respectively. Performance of the plasma jet is evaluated by surface and water sterilization. The results show that, Ar plasma jet is generated stable with double-dielectric barrier discharge. The length of plasma jet increases as the applied voltage, frequency or gas flow increased, but the plasma jet generation can be restricted in high frequency or gas flow. For E. coli in the water and surface, high sterilization efficiency is observed for a short time treatment by Ar plasma jet.
A solid phase extraction combined with UHPLC-MS/MS method has been developed and validated for determination of GRg1, GRe, GRb1 and NR1 in cosmetic products.
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