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Using a similar density-based optimization method , scaffolds with elastic tensors similar to those of natural bones were designed ; and the performance of these scaffolds in subsequent tissue ingrowth was investigated .
 concept or principle: optimization; engineering feature: scaffolds; concept or principle: elastic tensors; engineering feature: designed; concept or principle: performance; 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: optimization; engineering feature: scaffolds; concept or principle: elastic tensors; engineering feature: designed; concept or principle: performance; engineering feature: scaffolds