glass vial. The film was hydrated with an aqueous buffer (typically 50 mM Tris, pH 7.5) by a combination of vortexing and bath sonication. Additional components such as salt (NaCl), or MgCl2 were included in the hydration buffer. The resulting lipid dispersion was loaded into capillaries (Quartz capillaries from Hampton Research having the following specifications: length -80 mm, outer diameter -1.5 mm, wall thickness -0.01 mm) and placed in a custom designed temperature-controlled capillary holder. Temperature was raised typically in steps of 10 °C over the range 10-90 °C. About 20 min was allowed at each temperature before collection of data. Typically, 20 consecutive 1 s scans were taken and averaged. Lipid phases were identified from the ratios of q-values of the Bragg peaks.