3230
It is proposed that the superior mechanical properties obtained for polymers printed under low pressure conditions , may be due to a combination of two factors .
 concept or principle: mechanical properties; material: polymers; concept or principle: pressure; material: be
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: mechanical properties, polymers, pressure, be 
Answer:
 concept or principle: mechanical properties; material: polymers; concept or principle: pressure; material: be