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For instance , by adding elements such as Y , Sr , Zn , Zr and Ca , Mg alloys were shown to have much lower degradation rates in comparison with pure Mg .
 material: elements; material: as; material: Sr; material: Zn; material: Zr; material: Ca; material: Mg alloys; process characterization: degradation rates; material: pure Mg
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:
 material: elements; material: as; material: Sr; material: Zn; material: Zr; material: Ca; material: Mg alloys; process characterization: degradation rates; material: pure Mg