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A review on porous biodegradable metals for hard tissue scaffolds can be found in Ref.. A theoretical study of topological design of polymeric scaffolds considering the effect of biodegradation was conducted by Chen .
 machanical property: porous; material: biodegradable metals; biomedical: hard tissue scaffolds; material: be; concept or principle: theoretical; engineering feature: topological design; engineering feature: polymeric scaffolds
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 machanical property: porous; material: biodegradable metals; biomedical: hard tissue scaffolds; material: be; concept or principle: theoretical; engineering feature: topological design; engineering feature: polymeric scaffolds