Urabe, T.Asher, S. A.Pershan, Peter2013-03-011981Urabe, T., S. A. Asher, and Peter S. Pershan. 1981. Hydration of single crystals of dipalmitoylphosphatidylcholine. Proceedings of the National Academy of Sciences 78(8): 4941-4945.0027-8424http://nrs.harvard.edu/urn-3:HUL.InstRepos:10361922Optical birefringence and x-ray measurements are reported for single crystals \((0.5 mm \times 2 mm \times 5 \mu m)\) of dipalmitoylphosphatidylcholine as a function of temperature and relative humidity. Large single crystals grown in \(CHCl_3\)/acetone at a low water concentration undergo an irreversible phase transformation at \(20^{\circ}C\) and 70% relative humidity or at \(60^{\circ}C\) and 65% relative humidity. After this transformation occurs, the crystals can be made to undergo a reversible transformation into and out of the \(L_{\alpha}\) phase. The x-ray-determined mosaic spread in the hydrated crystal is less than \(\approx 0.04^{\circ}\) both above and below the main transition.en-USJournal Article2014-10-2210.1073/pnas.78.8.4941