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In this work , a micromechanical model for MatEx parts is developed to describe bulk part behavior that incorporates void fraction , road morphology , and bonding between and within layers .
 concept or principle: model; concept or principle: void fraction; concept or principle: morphology; concept or principle: bonding
Given options, please tell me the categories of all the listed entity words.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} 
 Entities: model, void fraction, morphology, bonding 
Answer:
 concept or principle: model; concept or principle: void fraction; concept or principle: morphology; concept or principle: bonding