Résumé
Face masks act as air filters that collect droplets and aerosols, and they are widely used to prevent infectious diseases, such as COVID-19. Herein, we present a numerical simulation model to understand the collection behavior of aerosols containing submicron-sized droplets inside a realistic microstructure of commercially available face masks. Three-dimensional image analysis by x-ray computed tomography is used to obtain the microstructures of two types of commercial face masks, and the aerosol permeation behavior in the obtained microstructures is investigated with a numerical method coupled with computational fluid dynamics and a discrete phase model. To describe the complex geometry of the actual fibers, a wall boundary model is used, in which the immersed boundary method is used for the fluid phase, and the signed distance function is used to determine the contact between the droplet and fiber surface. Six different face-mask domains are prepared, and the pressure drop and droplet collection efficiency are calculated for two different droplet diameters. The face-mask microstructure with the relatively larger pore, penetrating the main flow direction, shows a high quality factor. A few droplets approach the pore accompanied by fluid flow and fibers collect them near the pore. To verify the effect of the pore on the collection behavior, six different model face-mask domains of variable pore sizes were created. Additionally, droplet collection near the pore is observed in the model face-mask domains. Specific pore-sized model masks performed better than those without, suggesting that the large pore may enhance performance.
Résumé
Background: Because the worldwide spread of coronavirus disease 2019 has forced a moratorium on student sports activity in Japan, reports on its impact on sports injuries are limited given its novelty. This study aimed to determine the characteristics and gender differences of injuries in adolescent athletes after returning to sport following restriction of club activities due to the coronavirus pandemic. Methods: An online retrospective questionnaire was distributed to 500 adolescent athletes who belong to school sports clubs in Japan from March 1–19, 2021. An anonymous questionnaire was created before and after the restriction of sports activities following the declaration of the first state of emergency of the COVID-19 pandemic in Japan. Subsequently, 258 valid responses were obtained, and injury-related characteristics were compared between injured and non-injured athletes after returning to sports and between genders for injured athletes. There were no differences in the body areas of sports injuries between males and females. Result: We found that injury experience before club activity restriction was significantly associated with injury after returning to sports (p < 0.001). Moreover, practice time increased before and after the restriction in the injury group (p = 0.038). The injury rate was higher in females (p < 0.024), and the trauma rate was higher among males (p = 0.016). There were no differences in the body areas of sports injuries between males and females. Conclusions: Our results provide gender-differentiated ideas and suggestions as they relate to injury prevention once in adolescent athletes returning to sports after the coronavirus disease 2019 induced restriction of club activities. We show the need for injury rehabilitation and practice time control in adolescent athletes in the coronavirus disease 2019 setting.
Résumé
We have been facing the COVID-19 pandemic that has imposed significant stress on hospitals and health care providers since the end of 2019, when the SARS-CoV-2 was identified in Wuhan, China. According to the guidelines of the Japanese Society of Gastroenterological Endoscopy released in March 2020, we have taken measures such as postponing non-urgent endoscopies, preparing a vinyl sheet at the reception desk to protect both the patients and receptionists, and stratifying the patient's risk of being infected with COVID-19 before the procedure. In addition, we found that there is a shortage of personal protective equipment (PPE). In this paper, we introduce the current situation at our endoscopy unit and efforts including making an alternative longsleeve plastic gown to deal with the shortage of PPE.