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During the building process , the scanning by either a laser or an electron beam may cause the instabilities of the melt pool , resulting in increased porosity and high surface roughness .
 process characterization: building process; concept or principle: scanning; enabling technology: laser; concept or principle: electron beam; material: melt pool; machanical property: porosity; machanical property: surface roughness
Please list all entity words in the text that fit the category.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} 
Answer:
 process characterization: building process; concept or principle: scanning; enabling technology: laser; concept or principle: electron beam; material: melt pool; machanical property: porosity; machanical property: surface roughness