Effect of specific non-pharmaceutical intervention policies on SARS-CoV-2 transmission in the counties of the United States.

Non-pharmaceutical interventions (NPIs) remain the only widely available tool for controlling the ongoing SARS-CoV-2 pandemic. We estimated weekly values of the effective basic reproductive number (Reff) using a mechanistic metapopulation model and associated these with county-level characteristics and NPIs in the United States (US). Interventions that included school and leisure activities closure and nursing home visiting bans were all associated with a median Reff below 1 when combined with either stay at home orders (median Reff 0.97, 95% confidence interval (CI) 0.58-1.39) or face masks (median Reff 0.97, 95% CI 0.58-1.39). While direct causal effects of interventions remain unclear, our results suggest that relaxation of some NPIs will need to be counterbalanced by continuation and/or implementation of others.

Solid-State Thermolytic Epimerization and Polymerization of (+)-Catechin and (-)-Epicatechin Proceed through Quinone Methide Intermediates.

A mechanism involving a quinone methide intermediate is proposed for the thermally driven epimerization and polymerization reactions of solid-state catechin and epicatechin. Epimerization of catechin to epicatechin maximized after heating at 180 degrees C for 30 min (0.76:1, epicatechin/catechin ratio), whereas maximum epicatechin to catechin epimerization occurred after heating at 250 degrees C for 2 min at a ratio of 1.34:1 (catechin/epicatechin). These results imply that the conversion of epicatechin to catechin is the thermodynamically favored process. Conversion to nonepimerized products was optimal (99%) after 8 min at 220 degrees C for catechin and after 2 min at 265 degrees C for epicatechin (99.8%). Pyrocatechol was identified by HPLC as a degradation product in both catechin and epicatechin. Heating catechin at 220 degrees C for 8 min produced a 5-fold increase in chromatographic peak area at 450 nm, indicative of quinone methide formation that was thermally stable over time and degraded in the presence of sodium borohydride.