ABSTRACT
The COVID-19 pandemic forced many Colleges and Universities across the globe to deliver education online. This online switch was abrupt and challenging for both students and instructors. Here we summarize the challenges faced in the United States at the University of Illinois at Chicago (UIC) College of Engineering during online teaching in Spring 2020 as a result of the COVID-19 pandemic and provide recommendations for the online delivery of classes. To understand the challenges faced, surveys were administered to UIC engineering students (N = 580) and instructors (N = 93). Two student focus groups were also convened (N = 56, N = 40). After the shift to online education, UIC students wanted to be on campus but not if that posed a risk to their or their family's health. Students also perceived lower quality of education after the shift. UIC College of Engineering instructors felt mostly prepared to transition online but were concerned about student learning assessment methods. Most instructors felt their classes went well and, if their classes were online in Fall 2020, planned to teach them with at least some amount of asynchronous delivery. Whenever possible, we recommend a blended approach to online teaching, offering the flexibility of asynchronous content with the engagement of a synchronous class. Other specific recommendations for lab classes, fostering a sense of student community, and student learning assessment are provided to address concerns and challenges as indicated by those surveyed. Given the unknown future epidemiological changes and willingness or the ability of students and instructors to return to campus, it is prudent to prepare for online learning in a COVID-19 world. We provide definitions, examples, considerations, and suggestions to assist in the online delivery of classes to guide and assist in this preparation.
ABSTRACT
Throughout 2020 and beyond, the entire world has observed a continuous increase in the infectious spread of the novel coronavirus (SARS-CoV-2) otherwise known as COVID-19. The high transmission of this airborne virus has raised countless concerns regarding safety measures employed in the working conditions for medical professionals. Specifically, those who perform treatment procedures on patients which intrinsically create mists of fine airborne droplets, i.e., perfect vectors for this and other viruses to spread. The present study focuses on understanding the splatter produced due to a common dentistry technique to remove plaque buildup on teeth. This technique uses a high-speed dentistry instrument, e.g., a Cavitron ultrasonic scaler, to scrape along the surface of a patient's teeth. This detailed understanding of the velocity and the trajectory of the droplets generated by the splatter will aid in the development of hygiene mechanisms to guarantee the safety of those performing these procedures and people in clinics or hospitals. Optical flow tracking velocimetry (OFTV) method was employed to obtain droplet velocity and trajectory in a two-dimensional plane. Multiple data collection planes were taken in different orientations around a model of adult mandibular teeth. This technique provided pseudo-three-dimensional velocity information for the droplets within the splatter developed from this high-speed dental instrument. These results indicated that within the three-dimensional splatter produced there were high velocities (1-2 m/s) observed directly below the intersection point between the front teeth and the scaler. The splatter formed a cone-shape structure that propagated 10-15 mm away from the location of the scaler tip. From the droplet trajectories, it was observed that high velocity isolated droplets propagate away from the bulk of the splatter. It is these droplets which are concerning for health safety to those performing the medical procedures. Using a shadowgraphy technique, we further characterize the individual droplets' size and their individual velocity. We then compare these results to previously published distributions. The obtained data can be used as a first step to further examine flow and transport of droplets in clinics/dental offices.
ABSTRACT
The persisting outbreak of SARS-CoV-2 has posed an enormous threat to global health. The sustained human-to-human transmission of SARS-CoV-2 via respiratory droplets makes the medical procedures around the perioral area vulnerable to the spread of the disease. Such procedures include the ultrasonic dental cleaning method, which occurs within the oral cavity and involves cavitation-induced sprays, thus increasing the risk of pathogen transmission via advection. To understand the associated health and safety risks for patients and clinicians, it is critical to understand the flow pattern of the spray cloud around the operating region, the size and velocity distribution of the emitted droplets, and the extent of fluid dispersion until ultimate deposit on surfaces or escape through air vents. In this work, the droplet size and velocity distributions of the spray emerging from the tip of a free-standing common ultrasonic dental cleaning device were characterized via high-speed imaging. Deionized water and 1.5% and 3% aqueous hydrogen peroxide (H2O2) solutions were used as working fluids, with the H2O2-an established oxidizing agent-intended to curb the survival of virus released in aerosols generated from dental procedures. The measurements reveal that the presence of H2O2 in the working fluid increases the mean droplet size and ejection velocity. Detailed computational fluid dynamic simulations with multiphase flow models reveal benefits of adding small amounts of H2O2 in the feed stream of the ultrasonic cleaner; this practice causes larger droplets with shorter residence times inside the clinic before settling down or escaping through air vents. The results suggest optimal benefits (in terms of fluid spread) of adding 1.5% H2O2 in the feed stream during dental procedures involving ultrasonic tools. The present findings are not specific to the COVID-19 pandemic but should also apply to future outbreaks caused by airborne droplet transmission.