Through the looking glass of physics
Low density ice formation causes a volume expansion relative to liquid water. Numerical simulations show that freezing along the tube walls proceeds freezing in the center, producing a strongly curved ice front. This effect is prominent when the immersion speed is the highest. The separation between regions containing low density ice and well-frozen or vitrifi ed parts is considered to be best when the ice front is as fl at as possible. This can be achieved by alteration of the freezing parameters for each specific case within the Leica EM SPF program interface. During the immersion movement, the ice formation front inside the tube is always above the level of the cryogen surface. The distance of this ice front depends on the immersion speed.