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Microhardness measurements and tensile tests were done to assess the effect of the hull-bulk strategy on the mechanical properties .
 concept or principle: Microhardness; process characterization: tensile tests; concept or principle: mechanical properties
Given options, please tell me the categories of all the listed entity words.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} 
 Entities: Microhardness, tensile tests, mechanical properties 
Answer:
 concept or principle: Microhardness; process characterization: tensile tests; concept or principle: mechanical properties