8159
Because of the strain in the Si layers suppressed by the primary multilayer structure , the long - term strength is preserved and the substantial fracture toughness is enhanced by the increasing numbers of effective grain boundaries and interfacial layers .
 Chemical: Si
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: Si