Dormancy for hard seeds is caused by impermeability to water and gas and mechanical constraint of the seed coat. 硬实种子种皮透水透气性差和对胚生长的机械限制，引起种子休眠。
Hollow fiber membranes with good gas permeability can be obtained after the extraction of the paraffin oil and stretching to a small extension. 将石蜡油提取掉后稍加拉伸即可得到透气性很好的微孔中空纤维渗透膜。
