If the generation of the nucleation rate faster, and crystal nucleusformation, growth speed is slow, it generated more cell number, grain is fine.
如果晶核的生成速度较快，而晶核生成后的成长速度较慢，则生成的晶核数目较多，晶粒较细。
2
Nicknamed the Southern Pinwheel, M83 is undergoing more rapid star formation than our own Milky Way galaxy, especially in its nucleus.
绰号“南方风车”的M83正在经历比我们银河系更快的恒星形成过程，特别是在它的核心。
3
Just as a snowflake requires a nucleus to spur the formation of its intricate crystal structure - a catalyst was required to spur the formation of the desired community.