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Fiasconaro A, Díez-Señorans G, Falo F. End-pulled polymer translocation through a many-body flexible pore. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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2
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Bayati P, Nourhani A. Memory effects in spiral diffusion of rotary self-propellers. Phys Rev E 2022; 105:024606. [PMID: 35291178 DOI: 10.1103/physreve.105.024606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 02/02/2022] [Indexed: 06/14/2023]
Abstract
The coupling of deterministic rotary motion and stochastic orientational diffusion of a self-propeller leads to a spiral trajectory of the expected displacement. We extend our former analysis of spiral diffusion [Phys. Rev. E 94, 030601(R) (2016)10.1103/PhysRevE.94.030601] in the white-noise limit to a more realistic scenario of stochastic noise with Gaussian memory and orientational fluctuations driven by an Ornstein-Uhlenbeck process. A variety of dynamical regimes including crossovers from ballistic to diffusive to ballistic in the angular dynamics are determined by the inertial timescale, orientational diffusivity, and angular speed.
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Affiliation(s)
- Parvin Bayati
- Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA
- Université Paris-Saclay, CNRS, Le Laboratoire de Physique Théorique et Modèles Statistiques, 91405 Orsay, France
| | - Amir Nourhani
- Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA
- Biomimicry Research and Innovation Center, University of Akron, Akron, Ohio 44325, USA
- Departments of Biology, Mathematics, and Chemical, Biomolecular, and Corrosion Engineering, University of Akron, Akron, Ohio 44325, USA
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3
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Song Y, Ning L. Transport of coupled particles in rough ratchet driven by Lévy noise. CHAOS (WOODBURY, N.Y.) 2021; 31:033104. [PMID: 33810744 DOI: 10.1063/5.0027116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 02/10/2021] [Indexed: 06/12/2023]
Abstract
This paper studies the transport of coupled particles in a tilted rough ratchet potential. The relationship between particles transport and roughness, noise intensity, external force, coupling strength, and free length is explored numerically by calculating the average velocity of coupled particles. Related investigations have found that rough potential can accelerate the process of crossing the barrier by increasing the particles velocity compared with smooth potential. It is based on the fact that the roughness on the potential surface is like a "ladder," which helps particles climb up and blocks them from sliding down. Moreover, superimposing an appropriate external force on the coupled particles or strengthening the Lévy noise leads to the particles velocity to increase. It is worth emphasizing that when the external force is selected properly, an optimal roughness can be found to maximize the particles velocity. For a given roughness, an optimal coupling coefficient is discovered to match the maximum velocity. And once the coupling coefficient is greater than the optimal value, the particles velocity drops sharply to zero. Furthermore, our results also indicate that choosing an appropriate free length between particles can also speed up transport.
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Affiliation(s)
- Yao Song
- School of Mathematics and Information Science, Shaanxi Normal University, Xi'an 710119, People's Republic of China
| | - Lijuan Ning
- School of Mathematics and Information Science, Shaanxi Normal University, Xi'an 710119, People's Republic of China
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4
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Hou R, Wang N, Bao W, Wang Z. Polymer-Based Accurate Positioning: An Exact Worm-like-Chain Study. ACS OMEGA 2018; 3:14318-14326. [PMID: 31458122 PMCID: PMC6644801 DOI: 10.1021/acsomega.8b01448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 10/18/2018] [Indexed: 06/10/2023]
Abstract
Precise positioning of molecular objects from one location to another is important for nanomanipulation and is also involved in molecular motors. Here, we study single-polymer-based positioning on the basis of the exact solution to the realistic three-dimensional worm-like-chain (WLC) model. The results suggest the possibility of a surprisingly accurate flyfishing-like positioning in which tilting one end of a flexible short polymer enables positioning of the other diffusing end to a distant location within an error of ∼1 nm. This offers a new mechanism for designing molecular positioning devices. The flyfishing effect (and reverse process) likely plays a role in biological molecular motors and may be used to improve speed of artificial counterparts. To facilitate these applications, a new force-extension formula is obtained from the exact WLC solution. This formula has an improved accuracy over the widely used Marko-Siggia formula for stretched polymers and is valid for compressed polymers too. The new formula is useful in analysis of single-molecule stretching experiments and in estimating intramolecular forces of molecular motors, especially those involving both stretched and compressed polymer components.
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Affiliation(s)
- Ruizheng Hou
- Department
of Applied Physics, School of Science, and Institute of Quantum Optics
and Quantum Information, Xi’an Jiaotong
University, Xi’an, Shaan Xi 710049, China
| | - Nan Wang
- Department of Mathematics and NUS Graduate
School for Integrative Sciences
and Engineering, National University of
Singapore, 119076, Singapore
| | - Weizhu Bao
- Department of Mathematics and NUS Graduate
School for Integrative Sciences
and Engineering, National University of
Singapore, 119076, Singapore
| | - Zhisong Wang
- Department of Mathematics and NUS Graduate
School for Integrative Sciences
and Engineering, National University of
Singapore, 119076, Singapore
- Department
of Physics, National University of Singapore, 117542, Singapore
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5
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Chiang YH, Tsai SL, Tee SR, Nair OL, Loh IY, Liu MH, Wang ZS. Inchworm bipedal nanowalker. NANOSCALE 2018; 10:9199-9211. [PMID: 29726566 DOI: 10.1039/c7nr09724g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Nanowalkers take either inchworm (IW) or hand-over-hand (HOH) gait. The IW nanowalkers are advantageous over HOH ones in force generation, processivity and high-density integration, though both gaits occur in intracellular nanowalkers from biology. Artificial IW nanowalkers have been realized or proposed, but all rely on different 'head' and 'tail' to gain an adventitious direction. Here we report an inherently unidirectional IW nanowalker that is a biped with two identical legs (i.e., indistinguishable 'head' and 'tail'). This walker is made of DNA, and driven by a light-powered G-quadruplex engine. The directional inchworm motion is confirmed by operating the walker on a DNA duplex track that is designed to show a distinctive fluorescence pattern for IW walkers as compared to HOH ones. Interestingly, this walker exhibits stride-controlled IW-to-HOH gait switch and direction reversal when the track's periodic binding sites have wider and wider separation. The results altogether present an integrated mechanism for implementing nanowalkers of different gaits and directions on molecular tracks, optical potentials or even solid-state surfaces.
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Affiliation(s)
- Y H Chiang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542.
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6
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Abstract
In this work we study the assisted translocation of a polymer across a membrane nanopore, inside which a molecular motor exerts a force fuelled by the hydrolysis of ATP molecules. In our model the motor switches to its active state for a fixed amount of time, while it waits for an ATP molecule which triggers the motor, during an exponentially distributed time lapse. The polymer is modelled as a beads-springs chain with both excluded volume and bending contributions, and moves in a stochastic three dimensional environment modelled with a Langevin dynamics at a fixed temperature. The resulting dynamics shows a Michaelis-Menten translocation velocity that depends on the chain flexibility. The scaling behavior of the mean translocation time with the polymer length for different bending values is also investigated.
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7
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McDermott D, Olson Reichhardt CJ, Reichhardt C. Collective ratchet effects and reversals for active matter particles on quasi-one-dimensional asymmetric substrates. SOFT MATTER 2016; 12:8606-8615. [PMID: 27714306 DOI: 10.1039/c6sm01394e] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Using computer simulations, we study a two-dimensional system of sterically interacting self-mobile run-and-tumble disk-shaped particles with an underlying periodic quasi-one-dimensional asymmetric substrate, and show that a rich variety of collective active ratchet behaviors arise as a function of particle density, activity, substrate period, and the maximum force exerted by the substrate. The net dc drift, or ratchet transport flux, is nonmonotonic since it increases with increased activity but is diminished by the onset of self-clustering of the active particles. Increasing the particle density decreases the ratchet transport flux for shallow substrates but increases the ratchet transport flux for deep substrates due to collective hopping events. At the highest particle densities, the ratchet motion is destroyed by a self-jamming effect. We show that it is possible to realize reversals of the direction of the net dc drift in the deep substrate limit when multiple rows of active particles can be confined in each substrate minimum, permitting emergent particle-like excitations to appear that experience an inverted effective substrate potential. We map out a phase diagram of the forward and reverse ratchet effects as a function of the particle density, activity, and substrate properties.
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Affiliation(s)
- Danielle McDermott
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. and Department of Physics, Wabash College, Crawfordsville, Indiana 47933, USA
| | | | - Charles Reichhardt
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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8
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Mortazavi F, Habibi M, Nedaaee Oskoee E. Translocation of a granular chain in a horizontally vibrated saw-tooth channel. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2016; 39:93. [PMID: 27761780 DOI: 10.1140/epje/i2016-16093-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 09/27/2016] [Indexed: 06/06/2023]
Abstract
We study the translocation mechanism of a granular chain in a horizontally vibrated saw-tooth channel using MD simulations and macro-scale experiments and show that the translocation speed is independent of the chain length as long as the chain length is larger than the spatial period of the saw-tooth. With the help of simulation, we explore the effect of geometry of the container and frequency and amplitude of vibration as well as chain flexibility on the chain drift speed. We observe that the most efficient transport is achieved when one of the channel walls is shifted with respect to the other wall by an amount equal to half the spatial period of the saw-tooth. We define a persistence length for the chain and show that the translocation speed depends on the ratio of persistence length over the spatial period of the saw-tooth. The optimum translocation occurs when this ratio is about 0.4. We also determine the optimum saw-tooth angle for the translocation of the chain as well as the optimum distance between the two walls. Some properties of this system are similar to those of polymer systems.
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Affiliation(s)
- Fariba Mortazavi
- Institute for Advanced Studies in Basic Sciences, Gava Zang, 45195-159, Zanjan, Iran
| | - Mehdi Habibi
- Institute for Advanced Studies in Basic Sciences, Gava Zang, 45195-159, Zanjan, Iran.
- Van der Waals-Zeeman Institute, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands.
| | - Ehsan Nedaaee Oskoee
- Institute for Advanced Studies in Basic Sciences, Gava Zang, 45195-159, Zanjan, Iran
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9
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Mondal D, Muthukumar M. Ratchet rectification effect on the translocation of a flexible polyelectrolyte chain. J Chem Phys 2016; 145:084906. [PMID: 27586945 PMCID: PMC5001978 DOI: 10.1063/1.4961505] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/10/2016] [Indexed: 12/20/2022] Open
Abstract
We report a three dimensional Langevin dynamics simulation of a uniformly charged flexible polyelectrolyte chain, translocating through an asymmetric narrow channel with periodically varying cross sections under the influence of a periodic external electric field. When reflection symmetry of the channel is broken, a rectification effect is observed with a favored direction for the chain translocation. For a given volume of the channel unit and polymer length, the rectification occurs below a threshold frequency of the external periodic driving force. We have also observed that the extent of the rectification varies non-monotonically with increasing molecular weight and the strength of geometric asymmetry of the channel. Observed non-monotonicity of the rectification performance has been interpreted in terms of a competition between two effects arising from the channel asymmetry and change in conformational entropy. An analytical model is presented with predictions consistent with the simulation results.
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Affiliation(s)
- Debasish Mondal
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - M Muthukumar
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
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10
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Li J, Shklyaev OE, Li T, Liu W, Shum H, Rozen I, Balazs AC, Wang J. Self-Propelled Nanomotors Autonomously Seek and Repair Cracks. NANO LETTERS 2015; 15:7077-7085. [PMID: 26383602 DOI: 10.1021/acs.nanolett.5b03140] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Biological self-healing involves the autonomous localization of healing agents at the site of damage. Herein, we design and characterize a synthetic repair system where self-propelled nanomotors autonomously seek and localize at microscopic cracks and thus mimic salient features of biological wound healing. We demonstrate that these chemically powered catalytic nanomotors, composed of conductive Au/Pt spherical Janus particles, can autonomously detect and repair microscopic mechanical defects to restore the electrical conductivity of broken electronic pathways. This repair mechanism capitalizes on energetic wells and obstacles formed by surface cracks, which dramatically alter the nanomotor dynamics and trigger their localization at the defects. By developing models for self-propelled Janus nanomotors on a cracked surface, we simulate the systems' dynamics over a range of particle speeds and densities to verify the process by which the nanomotors autonomously localize and accumulate at the cracks. We take advantage of this localization to demonstrate that the nanomotors can form conductive "patches" to repair scratched electrodes and restore the conductive pathway. Such a nanomotor-based repair system represents an important step toward the realization of biomimetic nanosystems that can autonomously sense and respond to environmental changes, a development that potentially can be expanded to a wide range of applications, from self-healing electronics to targeted drug delivery.
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Affiliation(s)
- Jinxing Li
- Department of Nanoengineering, University of California San Diego , La Jolla, California 92093, United States
| | - Oleg E Shklyaev
- Department of Chemical Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States
| | - Tianlong Li
- Department of Nanoengineering, University of California San Diego , La Jolla, California 92093, United States
| | - Wenjuan Liu
- Department of Nanoengineering, University of California San Diego , La Jolla, California 92093, United States
| | - Henry Shum
- Department of Chemical Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States
| | - Isaac Rozen
- Department of Nanoengineering, University of California San Diego , La Jolla, California 92093, United States
| | - Anna C Balazs
- Department of Chemical Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States
| | - Joseph Wang
- Department of Nanoengineering, University of California San Diego , La Jolla, California 92093, United States
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11
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Fiasconaro A, Mazo JJ, Falo F. Active polymer translocation in the three-dimensional domain. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:022113. [PMID: 25768464 DOI: 10.1103/physreve.91.022113] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Indexed: 06/04/2023]
Abstract
In this work we study the translocation process of a polymer through a nanochannel where a time dependent force is acting. Two conceptually different types of driving are used: a deterministic sinusoidal one and a random telegraph noise force. The mean translocation time presents interesting resonant minima as a function of the frequency of the external driving. For the computed sizes, the translocation time scales with the polymer length according to a power law with the same exponent for almost all the frequencies of the two driving forces. The dependence of the translocation time with the polymer rigidity, which accounts for the persistence length of the molecule, shows a different low frequency dependence for the two drivings.
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Affiliation(s)
- A Fiasconaro
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain
- Instituto de Ciencia de Materiales de Aragón, C.S.I.C.-Universidad de Zaragoza, 50009 Zaragoza, Spain
- School of Mathematical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - J J Mazo
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain
- Instituto de Ciencia de Materiales de Aragón, C.S.I.C.-Universidad de Zaragoza, 50009 Zaragoza, Spain
| | - F Falo
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain
- Instituto de Biocomputación y Física de Sistemas Complejos, Universidad de Zaragoza, 50018 Zaragoza, Spain
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12
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Chen K, Chou YC, To K. Force generation by granular chains moving randomly on periodic ratchet plates. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:012711. [PMID: 23410363 DOI: 10.1103/physreve.87.012711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 12/07/2012] [Indexed: 06/01/2023]
Abstract
A variation of the Brownian ratchet mechanism for the force generated by the combination of the random motion and the ratchet structure is proposed and simulated with granular chains moving randomly on periodic ratchet plates. The present mechanism differs from the flashing ratchet model of the kinesin-microtubule molecular motor. When the bead chain bounces against the periodic ratchet, the chain as a whole will gain an impulse in the direction of the long side (the side with smaller slope). The observed behaviors of the simulating system, including (i) the force-velocity relation, (ii) the stall force as a function of the number of chains, (iii) the increase of velocity with the excitation, and (iv) the appearance of steps at low velocity and its distribution function, are similar to the corresponding ones of the kinesin-microtubule system.
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Affiliation(s)
- KuanHua Chen
- Department of Physics, National Tsing Hua University, Hsinchu, Taiwan, Republic of China
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13
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Fendrik AJ, Romanelli L, Reale MV. Currents in defective coupled ratchets. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:041149. [PMID: 22680459 DOI: 10.1103/physreve.85.041149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 03/20/2012] [Indexed: 06/01/2023]
Abstract
Transport phenomena in a one-dimensional system of interacting particles is studied. This system is embedded in a periodic and left-right asymmetric potential driven by a force periodic in time and space. When the density (number of particles per site) is an integer, directional current of the particles is collective; that is, it involves the whole system since all the sites are equivalents. On the other hand, when the system has a defect, a new localized or noncollective current appears due to the migration of defects from one site to another. We show here how this "defective" (defects generated) current can be controlled by white noise.
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Affiliation(s)
- A J Fendrik
- Instituto de Ciencias, Universidad Nacional de General Sarmiento-J.M. Gutierrez 1150, 1613 Los Polvorines, Buenos Aires, Argentina.
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Kauttonen J, Merikoski J. Single-layer metal-on-metal islands driven by strong time-dependent forces. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:011107. [PMID: 22400512 DOI: 10.1103/physreve.85.011107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Revised: 12/05/2011] [Indexed: 05/31/2023]
Abstract
Nonlinear transport properties of single-layer metal-on-metal islands driven with strong static and time-dependent forces are studied. We apply a semiempirical lattice model and use master-equation and kinetic Monte Carlo simulation methods to compute observables such as the velocity and the diffusion coefficient. Two types of time-dependent driving are considered: a pulsed rotated field and an alternating field with a zero net force (electrophoretic ratchet). Small islands up to 12 atoms were studied in detail with the master-equation method and larger ones with simulations. Results are presented mainly for a parametrization of Cu on Cu(001) surface, which has been the main system of interest in several previous studies. The main results are that the pulsed field can increase the current in both diagonal and axis direction when compared to static field, and there exists a current inversion in the electrophoretic ratchet. Both of these phenomena are a consequence of the coupling of the internal dynamics of the island with its transport. In addition to the previously discovered "magic size"effect for islands in equilibrium, a strong odd-even effect was found for islands driven far out of equilibrium. Master-equation computations revealed nonmonotonous behavior for the leading relaxation constant and effective Arrhenius parameters. Using cycle optimization methods, typical island transport mechanisms are identified for small islands.
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Affiliation(s)
- Janne Kauttonen
- Department of Physics, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland.
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15
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Samii L, Blab GA, Bromley EHC, Linke H, Curmi PMG, Zuckermann MJ, Forde NR. Time-dependent motor properties of multipedal molecular spiders. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:031111. [PMID: 22060332 DOI: 10.1103/physreve.84.031111] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 06/13/2011] [Indexed: 05/31/2023]
Abstract
Molecular spiders are synthetic biomolecular walkers that use the asymmetry resulting from cleavage of their tracks to bias the direction of their stepping motion. Using Monte Carlo simulations that implement the Gillespie algorithm, we investigate the dependence of the biased motion of molecular spiders, along with binding time and processivity, on tunable experimental parameters, such as number of legs, span between the legs, and unbinding rate of a leg from a substrate site. We find that an increase in the number of legs increases the spiders' processivity and binding time but not their mean velocity. However, we can increase the mean velocity of spiders with simultaneous tuning of the span and the unbinding rate of a spider leg from a substrate site. To study the efficiency of molecular spiders, we introduce a time-dependent expression for the thermodynamic efficiency of a molecular motor, allowing us to account for the behavior of spider populations as a function of time. Based on this definition, we find that spiders exhibit transient motor function over time scales of many hours and have a maximum efficiency on the order of 1%, weak compared to other types of molecular motors.
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Affiliation(s)
- Laleh Samii
- Department of Physics, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada
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16
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Efremov A, Wang Z. Maximum directionality and systematic classification of molecular motors. Phys Chem Chem Phys 2011; 13:5159-70. [DOI: 10.1039/c0cp02519d] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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17
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Polson JM, Bylhouwer B, Zuckermann MJ, Horton AJ, Scott WM. Dynamics of a polymer in a Brownian ratchet. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:051931. [PMID: 21230524 DOI: 10.1103/physreve.82.051931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 09/29/2010] [Indexed: 05/30/2023]
Abstract
We have used Brownian dynamics simulations to study the dynamics of a bead-and-spring polymer subject to a flashing ratchet potential. To elucidate the role of hydrodynamic (HD) interactions, simulations were carried out for the cases where HD interactions are present and when they are absent. The average speed of the polymer and its conformational properties were examined upon variation in the polymer length, N, and the ratchet spatial period, L. Two distinct dynamical regimes were evident. In the low-N/high-L regime, the velocity decreases with increasing N, and center-of-mass diffusion is a key part of the motional mechanism. By contrast, in the high-N /low-L regime, the velocity is insensitive to variation in N, and motion is achieved via the coupling of internal modes to the cycling of the ratchet potential. The location of the regimes is correlated with the average conformational state of the polymer. Incorporating HD interactions increases the average polymer velocity for all polymer lengths and ratchet spatial periods considered. The dynamical behavior of polymers in the low-N/high-L regime can be understood using simple a theoretical model that yields quantitatively reasonable predictions of the polymer velocity.
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Affiliation(s)
- James M Polson
- Department of Physics, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada C1A 4P3
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18
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19
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Fiasconaro A, Mazo JJ, Falo F. Translocation time of periodically forced polymer chains. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:031803. [PMID: 21230097 DOI: 10.1103/physreve.82.031803] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 07/05/2010] [Indexed: 05/30/2023]
Abstract
In this work we study the presence of both a minimum and clear oscillations in the frequency dependence of the translocation time of a polymer described as a unidimensional Rouse chain driven by a spatially localized oscillating linear potential. The observed oscillations of the mean translocation time arise from the synchronization between the very mean translocation time and the period of the external force. We have checked the robustness of the frequency value for the minimum translocation time by changing the damping parameter, finding a very simple relationship between this frequency and the correspondent translocation time. The translocation time as a function of the polymer length has been also evaluated, finding a precise L2 scaling. Furthermore, the role played by the thermal fluctuations described as a gaussian uncorrelated noise has been also investigated, and the analogies with the resonant activation phenomenon are commented.
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Affiliation(s)
- Alessandro Fiasconaro
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain.
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20
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Kauttonen J, Merikoski J. Characteristics of the polymer transport in ratchet systems. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:041112. [PMID: 20481682 DOI: 10.1103/physreve.81.041112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 03/25/2010] [Indexed: 05/29/2023]
Abstract
Molecules with complex internal structure in time-dependent periodic potentials are studied by using short Rubinstein-Duke model polymers as an example. We extend our earlier work on transport in stochastically varying potentials to cover also deterministic potential switching mechanisms, energetic efficiency, and nonuniform charge distributions. We also use currents in the nonequilibrium steady state to identify the dominating mechanisms that lead to polymer transportation and analyze the evolution of the macroscopic state (e.g., total and head-to-head lengths) of the polymers. Several numerical methods are used to solve the master equations and nonlinear optimization problems. The dominating transport mechanisms are found via graph optimization methods. The results show that small changes in the molecule structure and the environment variables can lead to large increases of the drift. The drift and the coherence can be amplified by using deterministic flashing potentials and customized polymer charge distributions. Identifying the dominating transport mechanism by graph analysis tools is found to give insight in how the molecule is transported by the ratchet effect.
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Affiliation(s)
- Janne Kauttonen
- Department of Physics, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland.
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Shi Y, Huang L, Brenner DW. Computational study of nanometer-scale self-propulsion enabled by asymmetric chemical catalysis. J Chem Phys 2009; 131:014705. [DOI: 10.1063/1.3153919] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Kenward M, Slater GW. Polymer deformation in Brownian ratchets: theory and molecular dynamics simulations. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:051806. [PMID: 19113148 DOI: 10.1103/physreve.78.051806] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Indexed: 05/27/2023]
Abstract
We examine polymers in the presence of an applied asymmetric sawtooth (ratchet) potential which is periodically switched on and off, using molecular dynamics (MD) simulations with an explicit Lennard-Jones solvent. We show that the distribution of the center of mass for a polymer in a ratchet is relatively wide for potential well depths U0 on the order of several kBT. The application of the ratchet potential also deforms the polymer chains. With increasing U0 the Flory exponent varies from that for a free three-dimensional (3D) chain, nu=35 (U0=0), to that corresponding to a 2D compressed (pancake-shaped) polymer with a value of nu=34 for moderate U0. This has the added effect of decreasing a polymer's diffusion coefficient from its 3D value D3D to that of a pancaked-shaped polymer moving parallel to its minor axis D2D. The result is that a polymer then has a time-dependent diffusion coefficient D(t) during the ratchet off time. We further show that this suggests a different method to operate a ratchet, where the off time of the ratchet, toff, is defined in terms of the relaxation time of the polymer, tauR. We also derive a modified version of the Bader ratchet model [Bader, Proc. Natl. Acad. Sci. U.S.A. 96, 13165 (1999)] which accounts for this deformation and we present a simple expression to describe the time dependent diffusion coefficient D(t). Using this model we then illustrate that polymer deformation can be used to modulate polymer migration in a ratchet potential.
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Affiliation(s)
- Martin Kenward
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA.
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Symmetry based mechanism for hand-over-hand molecular motors. Biosystems 2008; 93:8-15. [DOI: 10.1016/j.biosystems.2008.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Revised: 04/10/2008] [Accepted: 04/17/2008] [Indexed: 11/23/2022]
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Kauttonen J, Merikoski J, Pulkkinen O. Polymer dynamics in time-dependent periodic potentials. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 77:061131. [PMID: 18643241 DOI: 10.1103/physreve.77.061131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Indexed: 05/26/2023]
Abstract
The dynamics of a discrete polymer in time-dependent external potentials is studied with the master equation approach. We consider both stochastic and deterministic switching mechanisms for the potential states and give the essential equations for computing the stationary-state properties of molecules with internal structure in time-dependent periodic potentials on a lattice. As an example, we consider standard and modified Rubinstein-Duke polymers and calculate their mean drift and effective diffusion coefficient in the two-state nonsymmetric flashing potential and symmetric traveling potential. Rich nonlinear behavior of these observables is found. By varying the polymer length, we find current inversions caused by the rebound effect that is only present for molecules with internal structure. These results depend strongly on the polymer type. We also notice increased transport coherence for longer polymers.
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Affiliation(s)
- Janne Kauttonen
- Department of Physics, University of Jyväskylä, PO Box 35, Jyväskylä, Finland.
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von Gehlen S, Evstigneev M, Reimann P. Dynamics of a dimer in a symmetric potential: ratchet effect generated by an internal degree of freedom. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 77:031136. [PMID: 18517358 DOI: 10.1103/physreve.77.031136] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Indexed: 05/26/2023]
Abstract
The one-dimensional dynamics of a dimer consisting of two harmonically coupled components is considered. The mutual distance between the dimer components plays the role of an internal degree of freedom. Both components are in contact with the same heat bath and are coupled to a spatially periodic, symmetric potential, whose amplitude is modulated periodically in time and whose coupling strength is different for the two components. In the absence of any external bias, a ratchet effect (directed transport) arises generically unless the mutual coupling of the dimer components tends to zero or infinity. In other words, the ratchet effect is generated by the internal degree of freedom. An accurate analytical approximation for the dimer's velocity and diffusion coefficient is obtained. The velocity of the system is maximized by adding an optimal amount of noise and by tuning the driving frequency to an optimal value. Furthermore, there exists an optimal coupling strength at which the velocity is the largest.
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Abstract
Inspired by the discovery of dimeric motor proteins capable of undergoing transportation in living cells, significant efforts have been expended recently to the fabrication of track-walking nanomotors possessing two foot-like components that each can bind or detach from an array of anchorage groups on the track in response to local events of reagent consumption. The central problem in fabricating bipedal nanomotors is how the motor as a whole can gain the synergic capacity of directional track-walking, given the fact that each pedal component alone often is incapable of any directional drift. Implemented bipedal motors to date solve this thermodynamically intricate problem by an intuitive strategy that requires a hetero-pedal motor, multiple anchorage species for the track, and multiple reagent species for motor operation. Here we performed realistic molecular mechanics calculations on molecule-scale models to identify a detailed molecular mechanism by which motor-level directionality arises from a homo-pedal motor along a minimally heterogeneous track. Optimally, the operation may be reduced to a random supply of a single species of reagents to allow the motor's autonomous functioning. The mechanism suggests a distinct class of fabrication targets of drastically reduced system requirements. Intriguingly, a defective form of the mechanism falls into the realm of the well known Brownian motor mechanism, yet distinct features emerge from the normal working of the mechanism.
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Hennig D, Fugmann S, Schimansky-Geier L, Hänggi P. Self-organized escape of oscillator chains in nonlinear potentials. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 76:041110. [PMID: 17994939 DOI: 10.1103/physreve.76.041110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Revised: 06/22/2007] [Indexed: 05/25/2023]
Abstract
We present the noise-free escape of a chain of linearly interacting units from a metastable state over a cubic on-site potential barrier. The underlying dynamics is conservative and purely deterministic. The mutual interplay between nonlinearity and harmonic interactions causes an initially uniform lattice state to become unstable, leading to an energy redistribution with strong localization. As a result, a spontaneously emerging localized mode grows into a critical nucleus. By surpassing this transition state, the nonlinear chain manages a self-organized, deterministic barrier crossing. Most strikingly, these noise-free, collective nonlinear escape events proceed generally by far faster than transitions assisted by thermal noise when the ratio between the average energy supplied per unit in the chain and the potential barrier energy assumes small values.
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Affiliation(s)
- D Hennig
- Institut für Physik, Humboldt-Universität Berlin, Newtonstrasse 15, D-12489 Berlin, Germany
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Li D, Fan D, Wang Z. General mechanism for inchworm nanoscale track walkers: Analytical theory and realistic simulation. J Chem Phys 2007; 126:245105. [PMID: 17614593 DOI: 10.1063/1.2746236] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Nanomotors capable of directed transportation along an unlimited linear track are being vigorously pursued both theoretically and experimentally. This study generalizes a previously proposed mechanism for nanoscale track walkers by explicitly treating key molecular details of the walker-track systems. An energy-diagram analysis identifies pathways of energy flow through the walker's movement cycle, and thereby enables us to develop an analytical theory for the track-walking mechanism. Realistic simulations of the walker's movement cycles are also conducted. The results show that the walker's directionality, run length, and speed depend critically on several key dimensional parameters of the walker-track systems. Most notably, the walker's performance as a function of the binding site interval of the track exhibits an oscillating pattern, which is accurately reproduced by the analytical theory. The wealth of nanocontrol mechanisms identified in the proposed track-walker systems not only provides a framework for optimizing performance of the walker, but also clarifies major requirements for future experimental implementation.
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Affiliation(s)
- Dan Li
- Institute of Modern Physics, Fudan University, Shanghai 200433, China
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Woo HJ. Analytical theory of the nonequilibrium spatial distribution of RNA polymerase translocations. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 74:011907. [PMID: 16907127 DOI: 10.1103/physreve.74.011907] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Indexed: 05/11/2023]
Abstract
A continuum Fokker-Planck model is considered for the RNA polymerase in the elongation phase, where the topology of a single free energy profile as a function of the translocation variable distinguishes the Brownian ratchet and power stroke mechanisms. The model yields a simple analytical stationary solution for arbitrary functional forms of the free energy. With the translocation potential of mean force estimated by the time-series data of the recent high-resolution single-molecule experiment [Abbondanzieri et al., Nature (London) 438, 460 (2005)], predictions of the model for the mechanical properties agree with experiments quantitatively with reasonable values of parameters. The evolution of the spatial distribution of translocation variable away from equilibrium with increasing nucleoside triphosphate concentration shows qualitatively different behavior in the two alternative scenarios, which could serve as an additional measurable signature of the underlying mechanism.
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Affiliation(s)
- Hyung-June Woo
- Department of Chemistry, University of Nevada, Reno, Nevada 89557, USA
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Craig EM, Zuckermann MJ, Linke H. Mechanical coupling in flashing ratchets. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:051106. [PMID: 16802917 DOI: 10.1103/physreve.73.051106] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Indexed: 05/10/2023]
Abstract
We consider the transport of rigid objects with internal structure in a flashing ratchet potential by investigating the overdamped behavior of a rodlike chain of evenly spaced point particles. In one dimension, analytical arguments show that the velocity can reverse direction multiple times in response to changing the size of the chain or the temperature of the heat bath. The physical reason is that the effective potential experienced by the mechanically coupled objects can have a different symmetry than that of individual objects. All analytical predictions are confirmed by Brownian dynamics simulations. These results may provide a route to simple, coarse-grained models of molecular motor transport that incorporate an object's size and rotational degrees of freedom into the mechanism of transport.
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Affiliation(s)
- Erin M Craig
- Materials Science Institute and Physics Department, University of Oregon, Eugene, Oregon 97405, USA
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