Supression of cubic phase formation in DOPC/Chol 1:1 mixtures by increase of the lipid/water ratio. (A) Cooling scan of a DOPC/Chol 1:1 mixture, 50% (w/v) in PBS, showing almost complete recovery of the Lα phase from the HII phase, accompanied by a small amount of Ia3d cubic phase. Scan rate 5°C/min. (B) Effect of the lipid content on the cubic phase formation in DOPC/Chol 1:1 mixtures in PBS. Diffraction patterns recorded at 20°C after a heating-cooling scan 20-95-20°C: (a) 10% (w/v), Im3m 48.0 nm; (b) 30% (w/v), Pn3m 28.8 nm; (c) 50% (w/v), Ia3d 36.8 nm.