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Although the material mixing degree of bonding interface is obviously improved at the advancing side ( AS ) interface of the nugget zone ( NZ ) by using the convex featured pin or the pin with three concave arc grooves , the material mixing degree at the retreating side ( RS ) interface of the NZ is always insufficient .
 material: material; concept or principle: bonding; material: AS; concept or principle: interface; concept or principle: arc; material: material; concept or principle: interface
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:
 material: material; concept or principle: bonding; material: AS; concept or principle: interface; concept or principle: arc; material: material; concept or principle: interface