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Electrochemical analysis of bacterial cells exposed to Cu ( 2 + ) ions provides new insights into the mechanistic aspect of Cu ( 2 + ) ion reduction within the bacterial cell and indicates a strong link between the silver and copper resistance machinery of bacteria in the context of metal ion reduction .
 Chemical: Cu ( 2 + ); Chemical: Cu ( 2 + ); Chemical: silver; Chemical: copper
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: Cu ( 2 + ); Chemical: Cu ( 2 + ); Chemical: silver; Chemical: copper