The covalence is performed by a bi-polar link: when walking, the ants are in a chain where the back, polar a, of an ant is followed by the head, polar b, of the next ant.    From Wordnik.com.  [PhysOrg.com - latest science and technology news stories] Reference

In addition, new concepts of binding site covalence, estimation of pathway distance and organism specificity were taken into account to identify the best synthetic pathway.    From Wordnik.com.  [BioMed Central - Latest articles] Reference