Cryopreservation of biological materials often depends on the rapid removal of water from the material to be preserved. Researchers have long preserved cells and tissues in a vitrified state by suspending them in cryoprotectant liquids before immersing them in liquid nitrogen. Vitrification keeps cells meta-bolically dormant and helps avoid the formation of ice crystals, which could damage cells. To determine the factors that drive vitrification, Young Song et al. (pp. 4596-4600) studied the physical phenomena that occur when a droplet of the cryoprotectant 1,2-propanediol plummets into liquid nitrogen. When ejected into liquid nitrogen, the droplet rises to the surface, buoyed by a vapor cloud generated by the evaporation of the surrounding liquid nitrogen.
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