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Further investigations of the oxygen content showed a high oxygen content of 570 ppm homogeneously distributed inside the specimens potentially limiting the strength of the matrix itself .
 material: oxygen; material: oxygen; machanical property: strength
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: oxygen, oxygen, strength 
Answer:
 material: oxygen; material: oxygen; machanical property: strength