“…We are interested in the classical problem of finding sufficient conditions for weak solutions of (1.1) such that they become regular. J. Serrin [10,11] is the pioneer in this direction, and later on, Fabes, Jones and Riviere [4], Giga [5], Sohr [14], Struwe [15] and Takahashi [16] extended and improved Serrin's regularity criterion. They showed that if u is a Leray-Hopf weak solution (see Definition 1.1) of (1.1) belonging to Serrin's class,…”