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Because in - air micro - PIXE analysis can determine the two - dimensional localization and content of particles in tissue , we can clarify the relationship between inhaled particles and diseases based on such analysis and the immunohistochemical expression of disease - related proteins .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
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