Chang Z H, Baust J G
Center for Cryobiological Research, State University of New York, Binghamton 13901.
J Microsc. 1991 Mar;161(Pt 3):435-44. doi: 10.1111/j.1365-2818.1991.tb03101.x.
A thermophysical model is established to analyse the influence of pre-cooling of a biological specimen in the cold gas layer associated with spray-freezing techniques. The basic principles governing the process of pre-cooling are provided. It is concluded that pre-cooling is one of the major limiting steps in attaining an overall ultra-rapid cooling rate. Pre-cooling has a substantial influence on the nature of the final frozen specimens. In order completely to avoid crystallization before entry into the liquid cryogen and maximize the overall cooling rate of the specimen, precautions should be taken to control the height of the gaseous layer and the size of the specimen. The probability of the specimen being frozen in the cold gaseous layer is reduced by increasing the entry speed. The effectiveness, however, becomes less marked at speeds greater than 10 m s. In order to minimize the risk of misinterpreting the measured cooling rate, it is necessary to specify the pre-cooling conditions. The pre-cooling effect is much more evident in liquid helium than in cryogens such as propane, ethane, Freon 12, 13 and 22.
建立了一个热物理模型，以分析与喷雾冷冻技术相关的冷气体层中生物样本预冷的影响。给出了预冷过程的基本原理。得出结论：预冷是实现整体超快速冷却速率的主要限制步骤之一。预冷对最终冷冻样本的性质有重大影响。为了在进入液态制冷剂之前完全避免结晶并使样本的整体冷却速率最大化，应采取措施控制气体层的高度和样本的尺寸。通过提高进入速度可以降低样本在冷气体层中冻结的概率。然而，当速度大于10米/秒时，这种效果就不那么明显了。为了将误判测量冷却速率的风险降至最低，有必要明确预冷条件。预冷效果在液氦中比在丙烷、乙烷、氟利昂12、13和22等制冷剂中更为明显。
