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
In some ways, the properties of graphite are like those of diamond. Both compounds boil at 4827oC, for example. But graphite is also very different from diamond. Diamond (3.514 g/cm3) is much denser than graphite (2.26 g/cm3). Whereas diamond is the hardest substance known, graphite is one of the softest.