6661
This has been attributed to the modification of powder surface by removing a moisture skin during the drying process , which prevents the formation of deleterious oxide and hydroxide during SLM .
 powder, drying, oxide, hydroxide, SLM
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:
 powder, drying, oxide, hydroxide, SLM