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 hardest mineral known to man, Graphite is one of the softest. 2  Diamond is an excellent electrical insulator, Graphite is a good conductor of electricity. 3  Diamond is the ultimate abrasive, Graphite is a very good lubricant.