Transport performance of feedback-coupled Brownian ratchets with closed-loop control strategy

2015 ◽  
Vol 29 (12) ◽  
pp. 1550069
Author(s):  
T. F. Gao ◽  
L. F. Wang ◽  
R. Z. Huang ◽  
Z. G. Zheng
Keyword(s):  
Diffusion Coefficient ◽  
External Force ◽  
Average Velocity ◽  
Thermal Noise ◽  
Periodic Force ◽  
Average Diffusion Coefficient ◽  
Brownian Particles ◽  
Average Diffusion ◽  
Time Periodic ◽  
Ratchet Potential

The transport performance of two feedback-coupled Brownian particles, which are subjected to the external force, the unbiased time-periodic force and thermal noise, is investigated in the double-well ratchet potential. The average velocity, the average diffusion coefficient and the Pe number are calculated, respectively. The results demonstrate that the transport characteristic of Brownian particles is different under the action of two factors of unbiased time-periodic force, amplitude and frequency. The former factor induces the increase of the average velocity and the average diffusion coefficient with the decrease of thermal noise intensity within certain limits, whereas the latter makes the average velocity decrease in the transport of coupled particles. Moreover, it is found there is an optimal value of the driving frequency at which the Pe number reaches its maximum. Remarkably, it is shown that the current reversal can be achieved by increasing the external force, and the directed transport can be enhanced by varying the structure of the ratchet potential and the intensity of noise.

scholarly journals Effect of Modification on the Fluid Diffusion Coefficient in Silica Nanochannels

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4030
Author(s):  
Gengbiao Chen ◽  
Zhiwen Liu
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Surface Effect ◽  
Bulk Water ◽  
Self Diffusion ◽  
Average Diffusion Coefficient ◽  
Average Diffusion ◽  
Chain Lengths ◽  
Fluid Diffusion ◽  
Self Diffusion Coefficient

The diffusion behavior of fluid water in nanochannels with hydroxylation of silica gel and silanization of different modified chain lengths was simulated by the equilibrium molecular dynamics method. The diffusion coefficient of fluid water was calculated by the Einstein method and the Green–Kubo method, so as to analyze the change rule between the modification degree of nanochannels and the diffusion coefficient of fluid water. The results showed that the diffusion coefficient of fluid water increased with the length of the modified chain. The average diffusion coefficient of fluid water in the hydroxylated nanochannels was 8.01% of the bulk water diffusion coefficient, and the diffusion coefficients of fluid water in the –(CH2)3CH3, –(CH2)7CH3, and –(CH2)11CH3 nanochannels were 44.10%, 49.72%, and 53.80% of the diffusion coefficients of bulk water, respectively. In the above four wall characteristic models, the diffusion coefficients in the z direction were smaller than those in the other directions. However, with an increase in the silylation degree, the increased self-diffusion coefficient due to the surface effect could basically offset the decreased self-diffusion coefficient owing to the scale effect. In the four nanochannels, when the local diffusion coefficient of fluid water was in the range of 8 Å close to the wall, Dz was greater than Dxy, and beyond the range of 8 Å of the wall, the Dz was smaller than Dxy.

Molten Slag Structure and Diffusion Coefficients of Cr3+ and Si4+ during Micro-Carbon Cr-Fe Alloy Production

2011 ◽  
Vol 79 ◽  
pp. 77-82
Author(s):  
Yi Min ◽  
Jian Huang ◽  
Cheng Jun Liu ◽  
Mao Fa Jiang
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Molten Slag ◽  
Optimization Method ◽  
Structure Theory ◽  
Average Diffusion Coefficient ◽  
Slag Structure ◽  
Initial Stage ◽  
Silicate Structure ◽  
Average Diffusion

Based on the silicate structure theory, the molten slag structure and the existential state of and during micro-carbon Cr-Fe alloy production process were analysised, and then their diffusion coefficients were calculated. The results showed that, during the initial stage, the average diffusion coeffecient of and is close to the , the reaction process is controlled by the diffusion of () and corporately, during the later stage, the diffusion coefficient of is less than average diffusion coefficient of and , the controlling step is the diffusion of . According to the evolution of diffusion coefficient, molten slag composition optimization method was advised to increase the diffusion ability of and for enhancing the reaction efficiency and the recovery rate of chromium.

Diffusion of Water in the Wheat Grain: Nuclear Magnetic Resonance and Radioisotopic Methods Provide Complementary Information

1990 ◽  
Vol 17 (2) ◽  
pp. 107 ◽  
Author(s):  
CF Jenner ◽  
GP Jones
Keyword(s):  
Diffusion Coefficient ◽  
Tritiated Water ◽  
Free Water ◽  
Wheat Grain ◽  
Freezing And Thawing ◽  
Complementary Information ◽  
Average Diffusion Coefficient ◽  
Average Diffusion ◽  
Polymeric Component ◽  
Developing Grains

Diffusion of water within developing grains of wheat has been evaluated by two independent methods: by kinetic analysis of the movement of tritiated water (THO) through the grain, and by n.m.r. procedures. Both methods provided different but complementary information. Movement of THO basipetally through grains attached to the ear was faster than diffusion could explain, and a reversal of the gradient of THO at the base of the grain also could not be accounted for by diffusion. These observations are adduced as evidence for recirculation of water within the grain. The average diffusion coefficient measured by both methods indicated that the diffusive motion of water was substantially hindered. Freezing and thawing resulted in an increase in diffusion but did not increase diffusion to values expected of free water. Starch, the major polymeric component of the grain, was not responsible for the residual reduction in diffusion coefficient in frozen and thawed tissue.

Modeling the Diffusion Mechanism and the Reaction Kinetics for the Photocatalytic Degradation of Acid Red 151 Aqueous Solutions by ZnO: Comparison of Linear and Non-Linear Methods

2007 ◽  
Vol 10 (2) ◽  
Author(s):  
K. Vasanth Kumar ◽  
K. Porkodi
Keyword(s):  
Aqueous Solution ◽  
Diffusion Coefficient ◽  
Aqueous Solutions ◽  
Photocatalytic Degradation ◽  
Reaction Kinetics ◽  
Diffusion Mechanism ◽  
Batch Processes ◽  
Average Diffusion Coefficient ◽  
Diffusion Controlled ◽  
Average Diffusion

AbstractBatch processes were carried out for the photocatalytic degradation of Acid Red 151 from its aqueous solution using ZnO catalyst at different initial dye concentrations. The process was found to be diffusion controlled for the first 15-20 minutes (before irradiation) with an average diffusion coefficient of 6.759 × 10

Monitoring human parvovirus B19 virus-like particles and antibody complexes in solution by fluorescence correlation spectroscopy

2004 ◽  
Vol 385 (1) ◽  
pp. 87-93 ◽  
Author(s):  
J. Toivola ◽  
P. O. Michel ◽  
L. Gilbert ◽  
T. Lahtinen ◽  
V. Marjomäki ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Serum Sample ◽  
Acute Phase ◽  
Fluorescence Correlation Spectroscopy ◽  
Parvovirus B19 ◽  
Correlation Spectroscopy ◽  
Human Parvovirus B19 ◽  
Fluorescence Correlation ◽  
Average Diffusion Coefficient ◽  
Average Diffusion

AbstractFluorescence correlation spectroscopy (FCS) was used in monitoring human parvovirus B19 virus-like particle (VLP) antibody complexes from acute phase and pastimmunity serum samples. The Oregon Green 488-labeled VLPs gave an average diffusion coefficient of 1.7x10exp-7 cm(2)s(-1) with an apparent hydrodynamic radius of 14 nm. After incubation of the fluorescent VLPs with an acute phase serum sample, the mobility information obtained from the fluorescence intensity fluctuation by autocorrelation analysis showed an average diffusion coefficient of 1.5x10exp-8 cm(2)s(-1), corresponding to an average radius of 157 nm. In contrast, incubation of the fluorescent VLPs with a pastimmunity serum sample gave an average diffusion coefficient of 3.5x10exp-8 cm(2)s(-1) and a radius of 69 nm. A control serum devoid of B19 antibodies caused a change in the diffusion coefficient from 1.7x10exp-7 to 1.6x10exp-7 cm(2)s(-1), which is much smaller than that observed with acute phase or pastimmunity sera. Thus, VLP-antibody complexes with different diffusion coefficients could be identified for the acute phase and pastimmunity sera. FCS measurement of VLPimmune complexes could be useful in distinguishing between antibodies present in acute phase or past-immunity sera as well as in titration of the VLPs.

scholarly journals Analysis of Transport Properties of the Randomly Moving Electrons in Metals

2019 ◽  
Vol 26 (2) ◽  
pp. 147-153
Author(s):  
Villius PALENSKIS ◽  
Evaras ŽITKEVIČIUS
Keyword(s):  
Diffusion Coefficient ◽  
Relaxation Time ◽  
Free Path ◽  
Mean Free Path ◽  
Periodic Lattice ◽  
Simple Method ◽  
Temperature Range ◽  
Average Diffusion Coefficient ◽  
Average Diffusion ◽  
Average Relaxation Time

In this critical analysis on the base of randomly moving (RM) electrons, presented the resistivity dependence on temperature for elemental metals both above and below the Debye’s temperatures. There also are presented the general relationships for estimation of the average diffusion coefficient, the average velocity, mean free path and average relaxation time of RM electrons on the Fermi surface at mentioned temperature range. It is shown that the scattering of RM electrons mainly is due to electronic defects associated with distortion of the periodic potential distribution in the periodic lattice, and accounting the exchange of the thermal energies between phonon and RM electron. The calculation results of resistivity dependence on temperature in the temperature range from 1 K to 900 K are demonstrated for Au and W and compared with the experimental data. There also is presented the simple method for determination of the basic kinetic characteristic dependences on temperature only from the resistivity dependence on temperature. It is at first time determined for Au and W the temperature dependences of the mean free path, average diffusion coefficient, average relaxation time of RM electrons from 1 K to 900 K.

Transport and efficiency of Brownian particles in confined narrow channels with a periodic driving force

2015 ◽  
Vol 29 (05) ◽  
pp. 1550026 ◽  
Author(s):  
Rang Wang ◽  
Jia-Ning Zhou ◽  
Xue-Mei Liu ◽  
Hua Xiao
Keyword(s):  
External Force ◽  
Driving Force ◽  
Average Velocity ◽  
Static Load ◽  
Narrow Channel ◽  
Load Force ◽  
Narrow Channels ◽  
Brownian Particles ◽  
Peaked Function ◽  
External Driving

Transport and efficiency of over-damped Brownian particles moving in a confined narrow channel is investigated in the presence of an oscillating force and a static load force. It is found that the average velocity increases monotonously with the unbiased external driving force, while the efficiency can be a peaked function of unbiased external force, which indicates that the unbiased external force can facilitate the efficiency of energy transformation. Moreover, the average velocity and the efficiency demonstrate complex behaviors due to the consideration of Stokes efficiency.

DIRECTED MOTION INDUCED BY SHIFTING RATCHET

2000 ◽  
Vol 14 (24) ◽  
pp. 2609-2616 ◽  
Author(s):  
YUXIAO LI ◽  
XIZHEN WU ◽  
YIZHONG ZHUO
Keyword(s):  
Driving Force ◽  
Transition Rate ◽  
Average Velocity ◽  
Thermal Noise ◽  
Periodic Potential ◽  
Directed Motion ◽  
Brownian Particles

The motion of Brownian particles in a spatial asymmetric periodic potential is considered. In the absence of any external macroscopic driving force, when the potential transits stochastically between two configurations which are shifted by a distance relative to each other, directed motion can be induced. The dependence of the average velocity on the transition rate, the strength of thermal noise and the shift distance between the two configurations of potential are analyzed. The efficiency of the system is evaluated.

scholarly journals Diffusivity of Carbon Dioxide through the Skin and Flesh of `Russet Burbank' Potato Tubers

1994 ◽  
Vol 119 (4) ◽  
pp. 742-746 ◽  
Author(s):  
Aref A. Abdul-Baki ◽  
Theophanes Solomos
Keyword(s):  
Diffusion Coefficient ◽  
Russet Burbank Potato ◽  
Storage Conditions ◽  
Gas Diffusion ◽  
Russet Burbank ◽  
Aerobic Respiration ◽  
Potato Tubers ◽  
Average Diffusion Coefficient ◽  
Average Diffusion ◽  
Main Barrier

The diffusion coefficient of CO2 in `Russet Burbank' potato (Solanum tuberosum L.) tubers was determined under steady-state conditions at 10 and 27C. The data showed that the skin is the main barrier to gas diffusion, with an average diffusion coefficient of 6.57 × 10-7 and 7.61 × 10-7 cm·s-1 at 10 and 27C, respectively. The flesh also presents an appreciable barrier to gas diffusion. The average diffusion coefficient of CO2 in the flesh was 2.00 × 10-4 and 2.24 × 10-4 cm·s-1 at 10 and 27C, respectively. Under regular storage conditions, the tuber is well aerated and the concentration of O2 at the center of the tuber is sufficient to maintain aerobic respiration.

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