5592
They were then characterized using micro-computed x-ray tomography , metallographic sample examination , and optical and stylus profilometry for surface topography .
 x-ray tomography, sample, optical, stylus, surface topography
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:
 x-ray tomography, sample, optical, stylus, surface topography