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A slotted roller is used to refine the microstructure and enhance tensile strength in the longitudinal direction by supporting external force .
 engineering feature: slotted roller; concept or principle: microstructure; machanical property: tensile strength; concept or principle: force
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:
 engineering feature: slotted roller; concept or principle: microstructure; machanical property: tensile strength; concept or principle: force