469378.fig.004a
(a)
469378.fig.004b
(b)
469378.fig.004c
(c)
469378.fig.004d
(d)
Figure 4: Scanning electron micrographs of the untreated (a) and NMMO treated pinewood powder for 1 h (b), 3 h (c), and 15 h (d). The magnifications were ×5000 (series 2) and ×1000 (series 1) except for (d1) which is ×2000. The arrows show the fiber bundle (green), opened cell wall (red), pores to the inside of biomass (orange), and condensation of cellulose (yellow). The cell wall pits are shown by red circles.