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In addition , the electrostatic repulsion between AFM tip and sample can alter the mechanical stiffness measured by AFM up to ~ 60 % ( from ~ 0 . 8 to 1 . 3 N / m ) . These findings indicate that the mechanical response of membranes and proteins and probably of other biomolecular systems should be determined at different loading rates to fully understand their properties .
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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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