液態氮表面存在一層蒸氣會減低冷凍下降速度
slush nitrogen 可減少vapor &下降液態氮溫度-196->-210度

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4404302/
The fast heat transfer through the thin microcapillary walls in our study was further augmented by the use of slush nitrogen, which reduced the vaporization16 at the interface between micro-capillary and the cryogenic immersion media24.