Thus, for area-normalized kinetics of NPs that cannot be melted, the dominant uncertainties result from ignorance of the NP shapes, rather than the uncertainties in M, Q, or T NP . Nonetheless, for many surface reactions at high or ultra-high temperatures, no absolute rate data is available, and having even reasonably close upper limits on the rates is quite valuable. Furthermore, one of the more interesting aspects of the single NP kinetics measurements is the ability to observe the evolution of the kinetics in response to changes in NP surface structure during reactions, with rates often changing by several orders of magnitude. For this purpose, a factor of ~2 uncertainty in the area-normalized kinetics has little effect on the ability to follow the relationship between evolving surface structure and reactivity.