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This work investigates the feasibility of a binderless , extrusion-based additive manufacturing approach to fabricate alumina ( Al2O3 ) parts from nanopowder .
 concept or principle: investigates; concept or principle: feasibility; manufacturing process: additive manufacturing; manufacturing process: fabricate; material: alumina; material: Al2O3
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, feasibility, additive manufacturing, fabricate, alumina, Al2O3 
Answer:
 concept or principle: investigates; concept or principle: feasibility; manufacturing process: additive manufacturing; manufacturing process: fabricate; material: alumina; material: Al2O3