Sentence:  Moreover , after concentration using negative pressure <WSD>dialysis</WSD> , agglutinin activity could sometimes be detected in the region designated 2a ( donors P. J. , D. A. , and J. F. , Fig. 1 ) . 
Meaning of the word marked with <WSD> tags:  separation of substances in solution by means of their unequal diffusion through semipermeable membranes