The size {HEAD ~ D} of {TAIL ~ the current path} is 0.5 to 10 nm, and typically 1 to 6 nm 
The size { HEAD ~ D } of { TAIL ~ the current path } is 0.5 to 10 nm , and typically 1 to 6 nm
OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH