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
Solid Lubricants / Dry Lubrication Graphite and molybdenum disulfide (MoS2) are the predominant materials used as solid lubricant. In the form of dry powder these materials are effective lubricant additives due to their lamellar structure. The lamellas orient parallel to the surface in the direction of motion.elf lubricating composites: Solid lubricants as PTFE, graphite, MoS 2 and some other anti friction and anti wear additives are often compounded in polymers and all kind of sintered materials. MoS 2 for example is compounded in materials for sleeve bearings, elastomere O-rings, carbon brushes etc.