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
1 Diamond is the ultimate abrasive, Graphite is a very good lubricant. 2  Diamond is transparent, Graphite is opaque. 3  Diamond crystallizes in the Isometric system and graphite crystallizes in the hexagonal system. 4  Somewhat of a surprise is that at surface temperatures and pressures, Graphite is the stable form of carbon.