noun, Biology. 1. an orientation of an organism to an external stimulus, as light, especially by growth rather than by movement. Origin of tropism. 1895-1900. First recorded in 1895-1900; independent use of -tropism. Related forms. tropismatic.
Friction on as-grown graphene (Fig. 1c) is ultra-low and rather uniform with its magnitude close to the previous reports4. In contrast, friction on graphene after ï¬uorination becomes
Thus, we can now clearly identify friction strength and friction coefficient of graphene, resulting in an equivalent critical pressure induced by adhesion of p C =Ï C /f=3.3 GPa. The other used parameters are E 1 =E 2 =1109 GPa, A 1 =A 2 =bh and the shear modulus is from MD simulations, Fig. 3; thus, from Eq.