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