If the strain exceeds the tolerable limit, the Si-O-Si linkage can break easily at high temperature and lead to the creation of positive and negative charges on silicon and oxygen atoms, respectively.

如果张力超过耐受极限，硅氧烷键就很易在高温下发生断裂并在硅和氧原子上分别形成正负电荷。

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The current tolerable upper limit of vitamin D intake is 50 mcg (2, 000 IU) per day.

CNN: How much vitamin D should someone over 55 take?

The latest RDAs of vitamin D increased to 600 IU for adults up to the age of 70 and 800 IU for adults older than 70, and the tolerable upper limit increased from 2, 000 to 4, 000 IU per day for adults.

CNN: How much vitamin D do I need?