用于快速冷却生物样本的冷冻剂的相对效率。

The relative efficiency of cryogens used for plunge-cooling biological specimens.

作者信息

Ryan K P, Purse D H, Robinson S G, Wood J W

出版信息

J Microsc. 1987 Jan;145(Pt 1):89-96. doi: 10.1111/j.1365-2818.1987.tb01318.x.

DOI:10.1111/j.1365-2818.1987.tb01318.x

Abstract

Coolants used for freezing biological specimens were tested for cooling performance in the continuous plunge mode. Results from bare thermocouples showed that ethane cooled faster than propane or a propane:pentane mixture, even when warmed to 25 K above its freezing point. Propane coolants were more efficient than Freon 22 and the slowest cooling occurred in boiling liquid nitrogen. Hydrated gelatin specimens showed similar results with ethane cooling about 33% faster than propane. Epoxy resin specimens cooled faster than hydrated gelatin specimens of similar size. Hydrated and resin specimens cooled over increasing distances as plunge velocity increased. A bare thermocouple, however, cooled over a constant distance when plunged above a critical velocity. This phenomenon may reflect vapour formation and its suppression at high plunge velocities. The rate of cooling in hydrated specimens is shown to have an absolute limit and cannot be modelled by bare thermocouples or resin specimens.

摘要

对用于冷冻生物样本的冷却剂在连续浸入模式下的冷却性能进行了测试。裸热电偶的测试结果表明，即使乙烷被加热到高于其凝固点25 K，其冷却速度仍比丙烷或丙烷 - 戊烷混合物快。丙烷冷却剂比氟利昂22更高效，而冷却最慢的是沸腾的液氮。水合明胶样本显示出类似的结果，乙烷冷却速度比丙烷快约33%。环氧树脂样本比相同尺寸的水合明胶样本冷却得更快。随着浸入速度的增加，水合样本和树脂样本在增加的距离上冷却。然而，当裸热电偶以高于临界速度浸入时，它在恒定距离上冷却。这种现象可能反映了蒸汽的形成及其在高浸入速度下的抑制。水合样本中的冷却速率显示有一个绝对极限，并且不能用裸热电偶或树脂样本进行建模。