Acidity is an important aerosol property, as it impacts numerous physicochemical properties. However, models either neglect to include aerosol acidity, or have not been robustly tested for various environments. We show that the atmosphere is generally acidic, and models miss this important feature.

Endoperoxidase NvfI catalyzes the incorporation of “three” oxygen atoms, including an endoperoxide and a hydroxyl group, into its substrate asnovolin A, in a single enzyme turnover reaction through a different mechanism from those of previously characterized endoperoxidases.

Ring expansion to “grow” larger N-heterocycles often uses cycloaddition of strained aza-rings with π-bonds. Here, we report a formal cross-dimerization between three-membered aza-heterocycles and 3- and 4-membered-ring ketones, providing a straightforward means of assembling diverse N-heterocycles.