植物水分在异质成核时冰点的计算

QUANTITATIVE RESULTS FOR ICE POINT OF WATER IN PLANT BY ANALYSIS OF HETEROGENEOUS NUCLEATION

应用热力学原理定量分析了植物水分异质成核的结冰机理：植物体微小空腔内的水分在结冰时，腔壁起着凝结核的作用，即存在异质成核结冰过程．水分异质成核的温度（即冰点） Ｔ与球形腔半径 Ｒ及冰水对墙壁的浸润性能的差异（用接触角θ表示）之间符合函数关系 Ｔ＝ Ｔ（ Ｒ，ｃｏｓθ）．对于每一个ｃｏｓθ值，当 Ｒ取某一确定值 Ｒ时，冰点达到最低值 Ｔｍ ｉｎ， Ｔｍ ｉｎ可达－ ３６ ℃．

The ice point of water in winter hardy plant by thermodynamic theory of heterogeneous nucleation is investigated quantitatively.When water in a small cavity of plant is frozen,the wall of the cavity can condense the nucleus.This freezing process is called heterogeneous nucleation.The nucleating temperature(i.e.ice point) T is determined by cavity radius R and contact angle θ which denotes surface wetting properties of the wall of the cavity.The relation between the T and R,θ can be showed by the function T=T(R, cos θ ).When θ is given,there is a certain cavity radius R * which can determine the lowest ice point T min ,the T min can be -36 ℃.