27150
In a previous paper ( Part I ) , we examined the possibility that fluctuations in potential energy E and particle mobility mu associated with this ' dynamic heterogeneity ' might offer information about the scale of collective motion in glassy materials based on molecular dynamics simulations of the glassy interfacial region of Ni nanoparticles ( NPs ) at elevated temperatures .
 Ni
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Ni