Microwave Detection, Disruption, and Inactivation of Microorganisms

This paper reviews three complex interactions between microwave energy and microorganisms (bacteria, fungi, and viruses). The first interaction comprises the detection of viruses within human blood using a 50-Ohm transmission-line vector net-analyzer (typically 0 to 10 dBm @ 2 to 8.5 GHz) where the blood is placed within a test chamber that acts as a non-50-Ohm discontinuity. The second interaction employs 1 to 6.5 W @ 8 to 26 GHz for microwave feed-horn illumination to inactivate microorganisms at an applied power density of 10 to 100 mW-2. The third interaction is within multi-mode microwave ovens, where microorganism cell membrane disruption occurs at a few 100 s of W @ 2.45 GHz and microorganism inactivation between 300 to 1800 W @ 2.45 GHz. Within the first microwave interaction, blood relaxation processes are examined. Whereas in the latter two microwave interactions, the following disruption, and inactivation mechanisms are examined: chemical cellular lysis and, microwave resonant absorption causing cell wall rupture, and thermodynamic analysis in terms of process energy budget and suspension energy density. In addition, oven-specific parameters are discussed.

To mask or not to mask:Modeling the potential for face mask use by the general public to curtail the COVID-19 pandemic

Face mask use by the general public for limiting the spread of the COVID-19 pandemic is controversial,though increasingly recommended,and the potential of this intervention is not well understood.We develop a compartmental model for assessing the communitywide impact of mask use by the general,asymptomatic public,a portion of which may be asymptomatically infectious.Model simulations,using data relevant to COVID-19 dynamics in the US states of New York and Washington,suggest that broad adoption of even relatively ineffective face masks may meaningfully reduce community transmission of COVID-19 and decrease peak hospitalizations and deaths.Moreover,mask use decreases the effective transmission rate in nearly linear proportion to the product of mask effectiveness(as a fraction of potentially infectious contacts blocked)and coverage rate(as a fraction of the general population),while the impact on epidemiologic outcomes(death,hospitalizations)is highly nonlinear,indicating masks could synergize with other nonpharmaceutical measures.Notably,masks are found to be useful with respect to both preventing illness in healthy persons and preventing asymptomatic transmission.Hypothetical mask adoption scenarios,for Washington and New York state,suggest that immediate near universal(80%)adoption of moderately(50%)effective masks could prevent on the order of 17e45%of projected deaths over two months in New York,while decreasing the peak daily death rate by 34e58%,absent other changes in epidemic dynamics.Even very weak masks(20%effective)can still be useful if the underlying transmission rate is relatively low or decreasing:InWashington,where baseline transmission is much less intense,80%adoption of such masks could reduce mortality by 24e65%(and peak deaths 15e69%),compared to 2e9%mortality reduction in New York(peak death reduction 9e18%).Our results suggest use of face masks by the general public is potentially of high value in curtailing community transmission and the burden of the pandemic.The community-wide benefits are likely to be greatest when face masks are used in conjunction with other non-pharmaceutical practices(such as social-distancing),and when adoption is nearly universal(nation-wide)and compliance is high.