There are several obvious points. Apart from the two diamond NPs, the initial EEO2 values were quite similar for all the NPs, clustering around 10 -3 Da/O2 collision. The time and mass dependences of EEO2 were quite different for each NP, however, indicating that evolution is strongly affected by the NP structure, which varies for the different feedstock materials, but also from NP-to-NP.