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