{HEAD ~ Specificity} means {TAIL ~ the ability} of the membrane to selectively bind or filter certain species from complex mixtures 
{ HEAD ~ Specificity } means { TAIL ~ the ability } of the membrane to selectively bind or filter certain species from complex mixtures
HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH