782 research outputs found
Stokes efficiency of molecular motors with inertia
AbstractA molecular motor utilizes chemical free energy to generate a unidirectional motion in a viscous media. The stochastic motion of a motor is governed by a Langevin equation coupled to the chemical occupancy state. The change of chemical occupancy state is governed by a discrete Markov process. The Stokes efficiency was introduced to measure how “efficiently” the motor uses chemical free energy to drive through the surrounding fluid. For the overdamping case where the effect of inertia is ignored, it was proved that the Stokes efficiency is bounded by 100% [H. Wang, G. Oster, The Stokes efficiency for molecular motors and its applications, Europhysics Letters 57 (2002) 134–140]. Here we present a proof for the general case
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Laser Polishing of Silica Rods
Lasers have been widely used in surface modification. In this research a CO2 continuous
wave laser has been used to polish the slot surface of the silica rods. The strong absorption of the
lO.6 um C02 radiation by the silica surface promotes the softening of a very thin layer of material
that flows under the action of surface tension. As a result, a mirror smooth glassy surface has been
formed which decreases the surface roughness without any substantial change in the surface
geometries. The effect of laser to surface inclination angle on the requisite power requirement was
assessed experimentally and theoretically. With laser beam scanning controlled by a computer aided design (CAD) database without specific tooling or human intervention, reliability and
reproducibility of this process have been greatly improved compared to conventional fire polishing.
The potential use of laser polishing as a post-processing step for freeform-fabricated parts is very
promising.Mechanical Engineerin
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