2005 Fiscal Year Final Research Report Summary
Study on coupled ratchet models
| Project/Area Number |
16560051
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Engineering fundamentals
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| Research Institution | Kyoto University |
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Principal Investigator |
IGARASHI Akito Kyoto University, School of Informatics, Associate Professor, 情報学研究科, 助教授 (00115784)
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| Project Period (FY) |
2004 – 2005
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| Keywords | molecular motor / stochastic process / fluctuation / coupled system / segregation of particle / ratchet model / Brownian motion / molecular machine |
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| Research Abstract |
Coupled ratchet models are investigated in this project with computer simulation and theoretical consideration.
1. A ratchet model, Brownian motors (ratchets) with two-dimensional motion coupled mutually with linear strings, is simulated with computer. With lateral elastic force which is applied because of prevention against collapse of the system, the system moves steadily almost in a certain direction, which is the intrinsic one of each particle for many numbers of particles, although it performs zigzag motion for small numbers of particles. These results of particles' motion coincide with those of in vitro motility assay qualitatively. Another experimental result, that velocity of molecular motors increase with the myosin density and is saturated for high density, is reproduced, as the periodicity of ratchet potentials is changed. Moreover, energy efficiency of the system is calculated as a function of load.
2. Usually granular mixtures are segregated with a sieve. We segregate mixtures with the use of an oscillating ratchet mechanism. That is, a planar box with an asymmetric saw-tooth-shaped base is vibrated vertically, and particles are poured into the box, then the particles display directional net motion. Since the direction of the motion fundamentally depends on properties of particles and the shape of the base, we can construct a novel granular sieve if the two kinds of particles move with different speeds or to opposite directions respectively on the same ratchet base. With computer simulation for rigid disks in a two-dimensional container with a saw-tooth base, we show that nearly perfect segregation of particles can be obtained for an appropriate value of inclination of the base.
The results of this research are presented at two international conferences (Wien (2004) and Erice (2005)) and two domestic conferences. A paper is also published in Physical Review E in 2005.
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