16255
Parallel channel structures are introduced into the bulk hydrogels by uniaxial freezing , providing stable , and uniform porosity suitable for cell invasion ( pore diameters of 5 - 15 micro m ) .
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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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