How many as can you find in:
Facing shortages of personal protective equipment, some clinicians have advocated the use of barrier enclosures (typically mounted over the head, with and without suction) to contain aerosol emissions from coronavirus disease 2019 (COVID-19) patients. There is however little evidence for its usefulness. To test the effectiveness of such a device, we built a manikin that can expire micron-sized aerosols at flow rates close to physiological conditions. We then placed the manikin inside the enclosure and used a laser sheet to visualize the aerosol leaking out. We show that with sufficient suction, it is possible to effectively contain aerosol from the manikin even at high flow rates (up to 60 L min−1) of oxygen, reducing aerosol exposure outside the enclosure by 99%. In contrast, a passive barrier without suction only reduces aerosol exposure by 60%.
Ngee Ann Polytechnic and Ng Teng Fong general Hospital have filed a patent submission for the barrier enclosure design.
We are grateful to the Agency for Science, Technology and Research for providing financial support under A*CRUSE funding.
Change the structure of the paper. Extra information on methods.

user
The total number of "a"s in that passage is sixty-five.
assistant