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This paper investigates the spreading characteristics of droplets when deposited on fibrous substrates , under conditions relevant to 3D printing of aligned FrSCs .
 concept or principle: investigates; concept or principle: droplets; machanical property: fibrous; manufacturing process: 3D printing
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, droplets, fibrous, 3D printing 
Answer:
 concept or principle: investigates; concept or principle: droplets; machanical property: fibrous; manufacturing process: 3D printing