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This is the first and largest prospective, multicenter, active, population-based surveillance study of the epidemiology of Mycoplasma pneumoniae among outpatient children with mild respiratory tract infections (RTIs) during the COVID-19 pandemic. Nationwide measures like strict face mask wearing and restrictions on population movement implemented to prevent the spread of COVID-19 might also effectively prevent the spread of M. pneumoniae .

A novel type of nanosilica-supported ultraviolet absorber (SiO 2 -N-0) was successfully prepared by chemically grafting 2,4-dihydroxybenzophenone (UV-0) onto the surface of nanosilica (SiO 2 ) with the aid of a coupling agent via a solgel method, which was confirmed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. SiO 2 -N-0 was then incorporated into poly(butylene adipate-co-terephthalate) (PBAT) to fabricate biodegradable composite film with a casting method. As expected, SiO 2 -N-0 was homogeneously dispersed in PBAT matrix, leading to higher mechanical strength and lower water vapor transmission of PBAT/SiO 2 -N-0 film than those of PBAT/SiO 2 /UV-0 film. More importantly, because of its low migration and volatility, SiO 2 -N-0 endowed PBAT film with excellent aging resistance under ultraviolet radiation than did the corresponding low molecular ultraviolet absorber UV-0. Taken together, these results suggest that thus prepared PBAT/SiO 2 -N-0 composite film may find many applications, especially as biodegradable agricultural mulch film.

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