Since the heat flow of C30d in DMPC could not be measured during the isothermal crystallization itself, we varied the duration of the isothermal step between 1 and 60 minutes. Then, we heated the samples again and compared the heat capacities and transition enthalpies upon melting for various crystallization durations. Figure shows the effect of variable crystallization time on the heat capacities during melting for bulk and mixed C30d. Similar to the heating/cooling runs shown in Figure , mixing of C30d with DMPC results in a third peak upon melting. Interestingly, if shorter crystallization times are used, this additional peak is also observed in bulk C30d (at 57.9-58.0 • C). For both samples, the intensity of this peak decreases with crystallization time. Simultaneously, the peak at approx. 59 • C increases in intensity. This observation confirms that the additional peak corresponds to the melting of an intermediate crystal phase which is formed during the transition from the rotator to the lowtemperature crystal phase. To our knowledge, C30 is not known to have multiple crystal phases , and we did not see any indication of an additional transition in the stan-dard DSC cooling runs (Figure ). However, Alamo et al. previously explained a similar observation in C 168 H 338 by a crystal-thickening process . Indeed, it was proposed that n-alkanes as short as C25 may first crystallize with nonaligned chain ends , effectively reducing the crystal thickness until the crystal-perfecting process is complete. Such thin crystals would be expected to melt at lower temperatures, possibly explaining the additional peak. Irrespective of its nature, this intermediate crystal form seems to be stabilized in DMPC membranes.