| Description |
The nanometer is the range of forces and extensions typically involved in many bio-molecular reactions where high energy bonds are hydrolyzed and the energy released is subsequently used to perform mechanical work in a rather efficient way. Scientists are building bio-motors with dimensions of less than 100 nm. Work values typically encountered in such reactions (highly irreversible and nonlinear with feed-forward and feed-back agents) are of the order of a few kBT units (kJ mol-1). Velocities in mechanical displacements and transport vary from very slow motions to the fastest cases occurring in the range 1–10 Ångstrom/ps (km/s, the typical value of sound velocity in “molecular” or “lattice” wires).
The processes by which such bio-motors utilize the chemical energy to perform mechanical work are based on either power stroke generation and/or a Brownian ratchet mechanism (rectification of thermal fluctuations from a surrounding heat bath and taking advantage of large and rare fluctuations). Indeed, as a system’s dimensions decrease, fluctuations away from equilibrium begin to dominate its behavior. The contribution of fluctuations and the equation of state tend to depend on the type of statistical ensemble, a new recently started line of thought in statistical mechanics.
Bio-molecular motors are finding applications as nano-machines, e.g. used as molecule-sized robots that work in molecular factories where small, but intricate structures are made on tiny assembly lines. Bio-molecular motors could form the basis of bottom-up approaches for constructing, active structuring and maintenance at the nano-meter scale. Bottom-up nano-mechanics, nano-chemistry and nano-technology deal with how to control the formation and two-and three-dimensional assembly of molecular scale building blocks into well defined meso- and macroscopic structures.
Capillary action is very prominent in nano-channels, nano-drops, etc, due to the large surface to volume ratio. Mesoscopic surface (DLVO) forces permit to properly describe three-phase contact angle, surfaces with variable wetting characteristics, etc.
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