I know table salt is white, but that is because you have power and you have multiple surfaces scattering, but a large crystal of sodium chloride is clear and colorless.

我知道食用盐是白色的，但这是因为你让它成了粉末,因为有了多个散射面，但是一个大的氯化钠晶体,是无色透明的。

麻省理工公开课 - 固态化学导论课程节选

The powder you could ship anywhere, and reconstitute it onsite, and then it gets injected.

你可以把粉末运送到任何地方,就地恢复活性,并将其注射到人体内

耶鲁公开课 - 生物医学工程探索课程节选

And then they found that they could freeze-dry this preparation of virus, and freeze-drying to lower the temperature, freeze it, then extract out all the water, so you're left with a powder, basically a powdered form of the virus, that could be shipped all over the world, and then reconstituted by adding water to it.

研究者们发现可以冷冻干燥这些病毒制剂,冷冻干燥就是就是降低温度,冷冻病毒,然后提取出所有水份,然后就剩下一些粉末,这主要是粉末状的病毒,这样就能将它运往全世界,并可以通过加水来恢复病毒的活性

耶鲁公开课 - 生物医学工程探索课程节选