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Herein it is shown , how the melt pool surface oxidation can be significantly reduced by the change of the carrier gas type , by a reduced carrier gas flow rate and by minor changes in the powder nozzle design .
 melt pool, oxidation, be, gas, gas flow rate, powder, nozzle, design
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:
 melt pool, oxidation, be, gas, gas flow rate, powder, nozzle, design