6535
In the case of multi-track deposition , surface pore defects were more likely to occur on the last track due to the gravity-driven flow effect that is determined by the track path and overlap .
 deposition, surface, pore, defects, overlap
Please list all entity words in the text that fit the category. Output format is "word1, 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} 
Answer:
 deposition, surface, pore, defects, overlap