6218
Although the NPs show an almost free and ergodic diffusion , their lateral motion is subject to substantial drag at the membrane surface , which leads to systematically smaller diffusion coefficients than those obtained for lipids in the membrane through fluorescence recovery after photobleaching .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None