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To ensure an effective biological bond between Ti alloy implants and surrounding bones , surface modification is essential to improve the conductivity of bones or the bioactivity of titanium .
 application: Ti alloy implants; manufacturing process: surface modification; machanical property: conductivity; machanical property: bioactivity; material: titanium
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:
 application: Ti alloy implants; manufacturing process: surface modification; machanical property: conductivity; machanical property: bioactivity; material: titanium