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These are the reduction in porosity of the printed part and the reduction in heat loss at the printed polymer surface , yielding enhanced bonding between the polymer layers .
 concept or principle: reduction; machanical property: porosity; concept or principle: reduction; concept or principle: heat; material: polymer; concept or principle: bonding; material: polymer
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: reduction, porosity, reduction, heat, polymer, bonding, polymer 
Answer:
 concept or principle: reduction; machanical property: porosity; concept or principle: reduction; concept or principle: heat; material: polymer; concept or principle: bonding; material: polymer