COVID-19 belongs to a typical class of viruses that predominantly affects the human respiratory system, thereby proving to be fatal to many. The virus, along with other air pollutant particulates poses a severe threat to the human respiratory organs. Since the most common transmission mode is respiratory fomites and aerosol particulates, it is necessary to prevent their ingression through a mask. The primary use of masks is to prevent aerial particulates. This paper reveals the development of masks with air filters coated with functionalized graphene (fG) mounted on a 3D-printed facial mask replica. The fused deposition modeling (FDM) process is used for fabricating the facial mask replica. fG associated with nanosheets has an additional adsorbing capacity with a high surface area to volume ratio. fG coat is used over a polypropylene (PP) cloth through a dip coating method to enhance the antiviral and antimicrobial properties. The quality of fG is investigated through Raman spectroscopy and other characterization techniques such as SEM, XRD, and FTIR were used for visual interpretation of distributions of fG on a polypropylene (PP) fabric. Fabricated fG coated MB filters show 98.2 % of bacterial filtration efficiency with 1.10 mbar of breathing resistance. The efficacy of the fG coated filter is tested against SARS-CoV-2 viral particles, which shows a complete arrest of viral transmission at the fG coated layer.
The existence of a 'Hillert regime' in 3D normal grain growth, where the grain size distributions (GSDs) at different time-steps match the Hillert distribution during parabolic grain growth, is investigated for different initial GSDs using large-scale phase-field simulations. The short-lived 'Hillert regime' was present in the early-stage only in few cases.The GSDs obtained at a later-stage for all cases are: self-similar over long period; independent of the initial GSDs; and wider than the Hillert distribution. Also, the topological properties in the 'Hillert regime' were different from that in the later-stage self-similar regime.
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