Erodible device comprising surfactant for modifying the rate of {HEAD ~ erosion} of {TAIL ~ the device} 
of
Erodible device comprising surfactant for modifying the rate of { HEAD ~ erosion } of { TAIL ~ the device }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL