ABSTRACT
We use a machine learning algorithm combining information from the NASA GEOS composition forecast (GEOS-CF) model and surface observations of nitrogen dioxide (NO2) and ozone (O3) at more than 5,000 observation sites to assess the impact of COVID-19 restrictions on surface air quality in 46 countries. Our methodology removes the compounding impacts of meteorology, seasonality and atmospheric chemistry on air pollution, thus allowing for a quantitative estimate of the change in surface air quality following COVID-19 containment measures. Compared to GEOS-CF model predictions that do not include emission reductions related to COVID-19 restrictions, surface observations show a drop in surface NO2 of up to 60% after the implementation of lockdowns. Average NO2 concentrations between February 2020 to June 2020 were 18% lower than business as usual. The earliest and strongest declines are observed over China, followed by Europe and the US. While NO2 concentrations over China recovered within 2 months, the recovery has been slower over Europe and the US. The impact of COVID-19 restrictions on O3 is complicated by non-linear atmospheric chemistry. Locally, O3 can show a short-term increase of up to 50% as a result of the decrease in NO2, which leads to a reduction in night time titration. However, this effect is offset by a decrease in photochemical production during the day. Our results indicate that these two competing processes resulted in a net zero change in average surface ozone during the first 5 months of the pandemic. The results also indicate that the reduced photochemical production becomes increasingly important over time. Our analysis is based on surface observations and model simulations available in near real-time, and we will present an up-to-date view of the short and medium-term impacts of COVID-19 restrictions on air quality around the world.
ABSTRACT
Background Iron is an essential nutrient in biology where, serving in cofactors of diverse enzymes, it enables one-electron oxidation and reduction processes. Access to iron is thus a key driver of proliferative disease and the oncogene MYC has been found to alter iron homeostasis so as to produce an augmented pool of intracellular Fe(II). We recently developed a new drug delivery approach inspired by the Fe(II)-dependent pharmacology of the antimalarial agents artemisinins and arterolane. Our preliminary in vitro and in vivo data suggest that prostate cancer is highly amenable to therapy and imaging using Fe(II)-sensitive reagents. Targeting soluble ferrous iron represents an entirely novel approach to image and treat prostate cancer.
ABSTRACT
The forced move to online learning in the arrival and persistence of the COVID-19 pandemic underscored the present lack of models for fully online general chemistry laboratory courses. While there exist a fair number of simulation platforms, video libraries, and one-off virtual experiments, a lack of complete general chemistry lab online courses necessitated the development of such an experience. By leveraging freely available simulations and videos, we were able to design two synchronous online delivery lab courses in the summer of 2020. Herein, the courses are described with accompanying analysis probing student perceptions of their experiences. ©