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To obtain a simplified model , researchers usually assume that scaffolds are constructed of periodically-repeating unit cells along all directions and the architecture of the micro unit cells can distinctly define the macro properties of the scaffolds .
 concept or principle: model; engineering feature: scaffolds; concept or principle: unit cells; application: architecture; concept or principle: micro unit cells; engineering feature: macro; engineering feature: 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:
 concept or principle: model; engineering feature: scaffolds; concept or principle: unit cells; application: architecture; concept or principle: micro unit cells; engineering feature: macro; engineering feature: scaffolds