Figure 1.

Schematic cross section through one defect in the smectic phase of DMPC/DHPC bicelles. Bicelles consist of DMPC-rich (light shaded) bilayer regions edged with DHPC-rich (dark shaded) curved regions. The defects correspond to either gaps between adjacent bicelle disks or toroidal perforations in bicellar lamellae. Diffusants smaller than the defect dimensions can diffuse freely whereas larger diffusants are hindered. The NMR diffusion experiment is arranged such that the component of the molecular diffusion tensor parallel to the direction of the transverse defect axis, D_‖, is measured exclusively.