Influence of screw dislocations on the orientation of a sheared lamellar phase

We have investigated the role of screw dislocations defects in a lyotropic lamellar phase of the mixed DMPC/C12E5/water system using microscopy and scattering techniques. Several of the usual shear-induced orientations of the lamellar phase were observed as a function of temperature and shear rate. It is suggested that the corresponding dynamical transitions are consistent with a variation in size of the defects.