5599
In the mechanically ground sample , hardness increased nearly two-fold up to 75 μm beneath the sample ’ s surface , and X-ray diffraction indicated an in-plane compressive stress , grain refinement , and micro-strain on the mechanically ground sample .
 concept or principle: sample; machanical property: hardness; concept or principle: sample; material: s; process characterization: X-ray diffraction; machanical property: compressive stress; process characterization: grain refinement; concept or principle: sample
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: sample, hardness, sample, s, X-ray diffraction, compressive stress, grain refinement, sample 
Answer:
 concept or principle: sample; machanical property: hardness; concept or principle: sample; material: s; process characterization: X-ray diffraction; machanical property: compressive stress; process characterization: grain refinement; concept or principle: sample