For example, systems can use {TAIL ~ feedstock materials}, such as cellulosic and lignocellulosic materials and starchy or sugary materials, to produce ethanol and butanol, e.g., by {HEAD ~ fermentation} 
For example , systems can use { TAIL ~ feedstock materials } , such as cellulosic and lignocellulosic materials and starchy or sugary materials , to produce ethanol and butanol , e.g. , by { HEAD ~ fermentation }
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD