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The paper investigates the microstructure and grain of the printed articles to confirm the roots of the observed planar isotropic properties .
 concept or principle: investigates; concept or principle: microstructure; concept or principle: grain; machanical property: isotropic
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: investigates, microstructure, grain, isotropic 
Answer:
 concept or principle: investigates; concept or principle: microstructure; concept or principle: grain; machanical property: isotropic