Fabrication of a High-Performance and Reusable Planar Face Mask in Response to the COVID-19 Pandemic

The coronavirus disease 2019(COVID-19)pandemic has caused a surge in demand for face masks,with the massive consumption of masks leading to an increase in resource-related and environmental con-cerns.In this work,we fabricated meltblown polypropylene(mb-PP)-based high-performance planar face masks and investigated the effects of six commonly used disinfection methods and various mask-wearing periods on the reusability of these masks.The results show that,after three cycles of treatment using hot water at 70℃ for 30 min,which is one of the most scalable,user-friendly methods for viral disinfection,the particle filtration efficiency(PFE)of the mask remained almost unchanged.After mask wearing for 24 h and subsequent disinfection using the same treatment procedures,the PFE decreased to 91.3%;the average number of bacterial and fungal colonies was assessed to be 9.2 and 51.6 colony-forming units per gram(CFU∙g^(-1)),respectively;and coliform and pyogenic bacteria were not detected.Both the PFE and the microbial indicators are well above the standard for reusable masks after disinfection.Schlieren pho-tography was then used to assess the capabilities of used and disinfected masks during use;it showed that the masks exhibit a high performance in suppressing the spread of breathed air.

Simultaneous saccharification and fermentation of sweet potato powder for the production of ethanol under conditions of very high gravity

Due to its merits of drought tolerance and high yield,sweet potatoes are widely considered as a potential alterative feedstock for bioethanol production.Very high gravity(VHG)technology is an effective strategy for improving the efficiency of ethanol fermentation from starch materials.However,this technology has rarely been applied to sweet potatoes because of the high viscosity of their liquid mash.To overcome this problem,cellulase was added to reduce the high viscosity,and the optimal dosage and treatment time were 8 U/g(sweet potato powder)and 1 h,respectively.After pretreatment by cellulase,the viscosity of the VHG sweet potato mash(containing 284.2 g/L of carbohydrates)was reduced by 81%.After liquefaction and simultaneous saccharification and fer-mentation(SSF),thefinal ethanol concentration reached 15.5%(v/v),and the total sugar conversion and ethanol yields were 96.5%and 87.8%,respectively.