Fig. 5  MPL measured by STEM. (a) STEM image showing fibrils with different masses per unit length. The boxes highlight 53-kDa/nm (lower left) and 27-kDa/nm (upper right) fibrils, respectively. Scale bar represents 57 nm. (b) Histogram showing the pooled data from 1030 STEM MPL measurements, with the component peaks fitted. Minor components in the samples with different morphologies may account for the smaller peaks at higher MPL.