The effectiveness factor is widely used to account for the interaction between pore diffusion and reactions on pore walls in porous catalytic pellets and solid fuel particles. The effectiveness factor is defined as the ratio of the reaction rate actually observed to the reaction rate calculated if the surface reactant concentration persisted throughout the interior of the particle, i.e., no rea...

In PNAS, Jahan et al. (1) describe a new role for the ubiquitin-specific protease 12 (USP12) deubiquitinase in T-cell receptor (TCR) signaling. Among other findings, the authors report that USP12 is exported from the nucleus to the cytosol upon TCR activation. Although the experimental evidence they provide is consistent with this model, I believe that some of their results would require a more...