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
Nov 25, 2016. . an carbon atom in graphite does not form 4 covalent bonds but only three in a hexahedral bidimensional structure. The last electron can move on all the plane, together with the fourth electron of the other carbon atoms. These are the electrons responsible of conduction current of the graphite.