173625.fig.001a
(a)
173625.fig.001b
(b)
173625.fig.001c
(c)
173625.fig.001d
(d)
Figure 1: Transmission electron microscopy (TEM) images of nano-Fe0 (a), VA-nano-Fe0 (c), nano-Fe3O4 (b), and VA-nano-Fe3O4 (d).