18095
We further hypothesize that it is not necessary to have accumulation of many cracks to produce an AFF , just one that progresses - one that is not stopped by bone ' s several protective mechanisms and is allowed to penetrate through a homogeneous environment .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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