WAXS measurements were performed on two samples of C20 in DPPC (10 and 25 vol% of n-alkane), and a DPPC reference sample. Additional water was added to the samples subjected to WAXS, resulting in a final lipid concentration of about 150 mg ml . The dispersions were vortexed and filled into borosilicate glass capillaries (from Hilgenberg (Maisfeld, Germany); 1 mm outer diameter and 0.01 mm thickness). The experimental setup is described in detail in our previous publication and is not repeated here . Scattering profiles were measured at 22 • C and corrected for background, transmission and sample geometry. The scattering intensities were angular-averaged and plotted versus the scattering vector q before normalization with respect to concentration and sample volume.