20300
In the search for improving the performance of drug eluting stent ( DES ) various developments are in progress worldwide including use of carrier free DES , use of biodegradable polymers , biodegradable stents etc .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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