Fig. 2

Transmission electron microscopic analysis of ultrafine particles (UFPs). a, b Non-stained transmission electron microscopy (TEM) images of ultrafine particles and its particle set showed general appearances of ultrafine particle; images showed the presence of various size and shaped particles. Collected ultrafine particle set showed the smallest particle was 9 × 13 nm in length and width (left top) while the largest sized particle was 52 × 53 nm in length and width (right bottom). Majority of the particles appeared to have diameter smaller than 50 nm. Scale bars: a 100 nm, b 50 nm