Figure 4From: Alkaline twin-screw extrusion pretreatment for fermentable sugar productionSEM images of untreated and pretreated corn stover before enzymatic hydrolysis. a, b: raw material; c, d: NaOH loading of 0.04Â g/g biomass and preservation time of 1Â h; e, f: NaOH loading of 0.06Â g/g biomass and preservation time of 1Â h.Back to article page