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In this study , an innovative method , electrically-assisted ultrasonic nanocrystal surface modification ( EA-UNSM ) was introduced to process 3D-printed Ti-6Al-4V samples .
 manufacturing process: surface modification; concept or principle: process; manufacturing process: 3D-printed; concept or principle: samples
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: surface modification, process, 3D-printed, samples 
Answer:
 manufacturing process: surface modification; concept or principle: process; manufacturing process: 3D-printed; concept or principle: samples