Airborne viruses represent a potentially significant health threat. However, only recently have researchers begun to characterize the size and infectivity of viral bioaerosols in the nanoscale size range. There are limitations in the generation of test viral aerosols and the ability to sample with acceptable efficiency. Reported here is use of a laminar-flow water condensation method to efficiently sample nanoscale bioaerosols to sizes well below 100 nm. We used MS2 bacteriophage in water to provide an aerosol with particles sizes from 300 nm down to 45 nm for sampling by both an all-glass impinger (4 mm; AGI-4) and the water condensation bioaerosol sampler. We demonstrated the existence of infectious viral particles below 100 nm and a higher collection efficiency by the water condensation sampler compared to the AGI-4 at nanoscale sizes. For example, the water condensation bioaerosol sampler that collected particles at 45 nm in diameter had 20 times more infective virions per collected particle compared to the AGI-4. However, when we corrected the AGI-4 data for particle size-dependent collection efficiency, the results were similar. We also used quantitative reverse transcription polymerase chain reaction, along with culturing for infectivity to determine the percent infectivity of the aerosol by particle size. Finally, we used a simple calculation to determine that a large fraction of sub-100 nm particles did not contain infectious virus because of the low titer concentration of virus in the Collison fluid.
As our students’ consumption of internet memes through social media increases, a critical perspective toward these memes becomes increasingly important. Memes present teachers with a powerful and relevant way to approach critical analysis and discussion in the 21st‐century classroom. In this article, the authors present a framework for incorporating critical discussion and creation of memes into classrooms. Harnessing the power and prevalence of memes, the authors explore how internet memes can be used as a vehicle for critically engaging students. When they understand the characteristics that make memes an effective vector of cultural transmission, students can more critically recognize, consume, and produce these tools for humor and social and political critique.
2017) Longterm viable bioaerosol sampling using a temperature-and humidity-controlled filtration apparatus, a laboratory investigation using culturable E.coli., Aerosol Science and Technology, 51:5, 576-586, ABSTRACT Sampling for culturable (e.g., viable) aerosolized microbes (bioaerosols) is a useful means to provide information for public health monitoring and studies. However, it is challenging to maintain microbe culturability when sampling at high flow rates (>12 L/min) and extended periods of time (4 h). We developed a first-generation, viable bioaerosol collection system (VBCS) utilizing temperature (T) and relative humidity (RH)-conditioned filtration at a flow rate of 25 L/min. A twostage system of tube-in-shell Nafion TM exchange units provides cooling to 10 C and RH conditioning to 80-95%. Aerosol particles are collected on a polyurethane nanofiber filter providing a physical collection efficiency of >95% for sizes 0.06-10 mm. The T and RH conditions at the collection filter are maintained, despite changes to ambient conditions. The initial testing of the VBCS was done under indoor, laboratory conditions with aerosolized, vegetative E. coli. A scenario of a 30-min challenge of bioaerosol followed by continued sampling of clean air for various times was used to judge culturability maintenance under extended-term sampling. An initial loss of culturability upon collection onto the filter was observed; 23 § 13% relative to 4-mm all-glass impinger. However once collected, 98% of culturability was maintained for an additional 4.5 h of sampling. An exponential decay in culturability was observed from 8 h to 15 h of sampling. Also, 24h cold storage of the filters collected was studied. The VBCS is based on the use of dry filter cassettes, needs minimal maintenance, and preserves culturability of vegetative bacteria for >4 h.
EDITOR
Tiina Reponen
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