scholarly journals Translocation of a Polymer through a Crowded Channel under Electrical Force

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Tingting Sun ◽  
Yunxin Gen ◽  
Hujun Xie ◽  
Zhouting Jiang ◽  
Zhiyong Yang
Keyword(s):  
Field Strength ◽  
Shape Factor ◽  
Cylindrical Channel ◽  
Protein Translocation ◽  
Scaling Exponent ◽  
Scaling Relation ◽  
Maximum Value ◽  
Translocation Time ◽  
Dynamics Simulations ◽  
Number Of Segments

The translocation of a polymer chain through a crowded cylindrical channel is studied using the Langevin dynamics simulations. The influences of the field strength F, the chain length N, and the crowding extent ρ on the translocation time are evaluated, respectively. Scaling relation τ~F-α is observed. With the crowding extent ρ increasing, the scaling exponent α becomes large. It is found that, for noncrowded channel, translocation probability drops when the field strength becomes large. However, for high-crowded channel, it is the opposite. Moreover, the translocation time and the average translocation time for all segments both have exponential growth with the crowding extent. The investigation of shape factor δ shows maximum value with increasing of the number of segments outside s. At last, the number of segments inside channel Nin in the process of translocation is calculated and a peak is observed. All the information from the study may benefit protein translocation.

scholarly journals Structure evolution of suspensions under time-dependent electric or magnetic field

2021 ◽  
Author(s):  
Konstantinos Manikas ◽  
Markus Hütter ◽  
Patrick D. Anderson
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Brownian Dynamics ◽  
Thermal Fluctuations ◽  
Time Dependent ◽  
Structure Evolution ◽  
Strength Increase ◽  
Large Rotation ◽  
Dynamics Simulations ◽  
Brownian Dynamics Simulations

AbstractThe effect of time-dependent external fields on the structures formed by particles with induced dipoles dispersed in a viscous fluid is investigated by means of Brownian Dynamics simulations. The physical effects accounted for are thermal fluctuations, dipole-dipole and excluded volume interactions. The emerging structures are characterised in terms of particle clusters (orientation, size, anisotropy and percolation) and network structure. The strength of the external field is increased in one direction and then kept constant for a certain amount of time, with the structure formation being influenced by the slope of the field-strength increase. This effect can be partially rationalized by inhomogeneous time re-scaling with respect to the field strength, however, the presence of thermal fluctuations makes the scaling at low field strength inappropriate. After the re-scaling, one can observe that the lower the slope of the field increase, the more network-like and the thicker the structure is. In the second part of the study the field is also rotated instantaneously by a certain angle, and the effect of this transition on the structure is studied. For small rotation angles ($$\theta \le 20^{{\circ }}$$ θ ≤ 20 ∘ ) the clusters rotate but stay largely intact, while for large rotation angles ($$\theta \ge 80^{{\circ }}$$ θ ≥ 80 ∘ ) the structure disintegrates and then reforms, due to the nature of the interactions (parallel dipoles with perpendicular inter-particle vector repel each other). For intermediate angles ($$20<\theta <80^{{\circ }}$$ 20 < θ < 80 ∘ ), it seems that, during rotation, the structure is altered towards a more network-like state, as a result of cluster fusion (larger clusters). The details provided in this paper concern an electric field, however, all results can be projected into the case of a magnetic field and paramagnetic particles.

scholarly journals Microstructure formation and macroscopic dynamics of ferrofluid emulsion in rotating magnetic field

2018 ◽  
Vol 185 ◽  
pp. 09004 ◽  
Author(s):  
Anastasia Kolesnikova ◽  
Arthur Zakinyan ◽  
Yuri Dikansky
Keyword(s):  
Magnetic Field ◽  
Molecular Dynamics ◽  
Field Strength ◽  
Molecular Dynamics Simulations ◽  
Time Evolution ◽  
Formation Process ◽  
Rotating Magnetic Field ◽  
Microstructure Formation ◽  
Water Emulsion ◽  
Dynamics Simulations

The ferrofluid-in-water emulsion has been produced and studied. The microstructure formation in a flat layer of such emulsion under the action of in-plane rotating magnetic field has been observed. Several microstructure types have been found such as chain-like aggregates, disc-like clusters, branching and space-occupying structures. The time evolution of the formation process has been analysed. The revealed microstructures have been computationally investigated by molecular dynamics simulations. The microstructure dynamics in ferrofluid emulsions manifests itself in macroscopic mechanical effects. We analysed the appearance of macroscopic torque on a ferrofluid emulsion sample in a rotating magnetic field. The value of the torque has been measured as a function of magnetic field strength and frequency.

scholarly journals Magnetic Field Instability of a Plasma in a Beam of Electromagnetic Radiation

1980 ◽  
Vol 35 (4) ◽  
pp. 461-463 ◽  
Author(s):  
O. M. Gradov ◽  
L. Stenflo
Keyword(s):  
Magnetic Field ◽  
Spatial Distribution ◽  
Magnetic Fields ◽  
Field Strength ◽  
Electromagnetic Radiation ◽  
Characteristic Time ◽  
Incident Radiation ◽  
Maximum Value ◽  
Quasi Stationary State ◽  
The Magnetic Field

Abstract A beam of electromagnetic radiation can generate magnetic fields in plasmas. It is shown that those fields grow significantly when the incident radiation is sufficiently strong. We obtain expressions for the characteristic time of the growth of the fields as well as for their spatial distribution and point out a possible mechanism, which can lead to the formation of a quasi-stationary state. The maximum value of the magnetic field strength is estimated

scholarly journals Characteristic mass-balance scaling with valley glacier size

1999 ◽  
Vol 45 (149) ◽  
pp. 17-21 ◽  
Author(s):  
David B. Bahr ◽  
Mark Dyurgerov
Keyword(s):  
Climate Change ◽  
Mass Balance ◽  
Scaling Exponent ◽  
Scaling Relation ◽  
Glacier Recession ◽  
Glacier Terminus ◽  
Valley Glacier ◽  
Glacier Length ◽  
The Impact ◽  
Characteristic Mass

AbstractPrevious work on the relation between glacier volume and area and on accumulation area ratios suggests that balance rates measured at the glacier terminus are not constant or random from glacier to glacier but instead scale with glacier length. Using mass-balance data from a collection of 68 valley and cirque glaciers, we show that the terminus mass-balance rate scales roughly linearly with surface area and scales with length raised to an exponent constrained to fall roughly between 0.5 and 2 with 1.7 preferred if a glacier’s length is dependent on the mass-balance conditions (rather than balance being dependent on length). When these exponents are used to predict valley-glacier volume–area scaling, the results are very close to empirical volume–area observations. Although the data are noisy and the proposed fits could be modified by improved observations, the scaling trend for terminus balance vs length remains clear. Although the exact value of the scaling exponent is not well determined, establishing the existence of this scaling relation will be important for studies of climate change and the impact of glacier recession on sea level.

scholarly journals Volume-area scaling for debris-covered glaciers

2020 ◽  
Vol 66 (259) ◽  
pp. 880-886
Author(s):  
Argha Banerjee
Keyword(s):  
Global Scale ◽  
Scaling Relations ◽  
Scaling Exponent ◽  
Scaling Relation ◽  
Model Simulations ◽  
Ice Volume ◽  
Himalayan Glaciers ◽  
Glacier Changes ◽  
Best Fit ◽  
The Himalaya

AbstractA volume-area scaling relation is commonly used to estimate glacier volume or its future changes on a global scale. The presence of an insulating supraglacial debris cover alters the mass-balance profile of a glacier, potentially modifying the scaling relation. Here, the nature of scaling relations for extensively debris-covered glaciers is investigated. Theoretical arguments suggest that the volume-area scaling exponent for these glaciers is ~7% smaller than that for clean glaciers. This is consistent with the results from flowline-model simulations of idealised glaciers, and the available data from the Himalaya. The best-fit scale factor for debris-covered Himalayan glaciers is ~60% larger compared to that for the clean ones, implying a significantly larger stored ice volume in a debris-covered glacier compared to a clean one having the same area. These results may help improve scaling-based estimates of glacier volume and future glacier changes in regions where debris-covered glaciers are abundant.

Assessing The Risk Associated with Simultaneous Exposure To Mobile Communication Signals Within 900–2500 MHz in Nigeria

2020 ◽  
Author(s):  
B O Ayinmode ◽  
I P Farai
Keyword(s):  
Ionizing Radiation ◽  
Field Strength ◽  
Electric Field ◽  
Mobile Communication ◽  
Base Station ◽  
Simultaneous Exposure ◽  
Communication Signals ◽  
Frequency Bands ◽  
Maximum Value ◽  
Total Electric Field

Abstract In this study, the total exposure due to signals within GSM 900, GSM 1800, CDMA-1900 and 3G-2100 frequency bands at 200 m from the foot of 120, 100 and 80 base station masts in the Nigerian cities of Lagos, Ibadan and Abuja, respectively, was assessed. A calibrated hand-held spectrum analyser was used to measure the level of power (in dBm) of each signal within the mobile frequency bands. The exposure quotient associated with the combine electric field strengths from the various frequency bands in each city was estimated. The maximum value of total electric field strength at each point in Lagos, Ibadan and Abuja was 0.83 V/m, 0.53 V/m and 1.63 V/m, respectively. This study shows that the exposure quotient due to the simultaneous exposure to the four bands of mobile communication signals in each city is far less than one, as recommend by International Commission on Non-Ionizing Radiation Protection.

scholarly journals Non-Gaussian, transiently anomalous and ergodic self-diffusion of flexible dumbbells in crowded two-dimensional environments: coupled translational and rotational motions

2021 ◽  
Author(s):  
Kolja Klett ◽  
Andrey G Cherstvy ◽  
Jaeoh Shin ◽  
Igor M Sokolov ◽  
Ralf Metzler
Keyword(s):  
Relative Motion ◽  
Center Of Mass ◽  
Scaling Exponent ◽  
Two Dimensional ◽  
Particle Structure ◽  
Self Diffusion ◽  
Experimental Systems ◽  
Long Time ◽  
Non Gaussian ◽  
Dynamics Simulations

We employ Langevin-dynamics simulations to unveil non-Brownian and non-Gaussian center-of-mass self-diffusion of massive flexible dumbbell-shaped particles in crowded two-dimensional solutions. We also study the intra-dumbbell dynamics due to the relative motion of the two constituent elastically-coupled disks. Our main focus is on effects of the crowding fraction φ and the particle structure on the diffusion characteristics. We evaluate the time-averaged mean-squared displacement (TAMSD), the displacement probability-density function (PDF) and the displacement autocorrelation function (ACF) of the dimers. For the TAMSD at highly crowded conditions of dumbbells, e.g., we observe a transition from the short-time ballistic behavior, via an intermediate subdiffusive regime, to long-time Brownian-like spreading dynamics. The crowded system of dimers exhibits two distinct diffusion regimes distinguished by the scaling exponent of the TAMSD, the dependence of the diffusivity on φ, and the features of the displacement-ACF. We attribute these regimes to a crowding-induced transition from a viscous to a viscoelastic diffusion medium upon growing φ. We also analyze the relative motion in the dimers, finding that larger φ suppress their vibrations and yield strongly non-Gaussian PDFs of rotational displacements. For the diffusion coefficients D(φ) of translational and rotational motion of the dumbbells an exponential decay with φ for weak and a power-law D(φ) ∝ (φ - φ*)2.4 for strong crowding is found. A comparison of simulation results with theoretical predictions for D(φ) is discussed and some relevant experimental systems are overviewed.

scholarly journals Correlation Length in Concentrated Electrolytes: Insights from All-Atom Molecular Dynamics Simulations

2019 ◽  
Author(s):  
Samuel Coles ◽  
Chanbum Park ◽  
Rohit Nikam ◽  
Matej Kanduč ◽  
Joachim Dzubiella ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Correlation Length ◽  
Salt Concentration ◽  
Scaling Law ◽  
Solvent Mixture ◽  
Scaling Exponent ◽  
Concentrated Electrolytes ◽  
Theoretical Predictions ◽  
Dynamics Simulations

<div><p>We study the correlations length of the charge-charge pair correlations in concentrated electrolyte solutions by means of all-atom, explicit-solvent molecular dynamics simulations. We investigate LiCl and NaI in water, which constitute highly soluble, prototypical salts for experiments, as well as two more complex, molecular electrolyte systems of lithium bis(trifluoromethane)sulfonimide (LiTFSI), commonly employed in electrochemical storage systems, in water and in an organic solvent mixture of dimethoxyethane (DME) and dioxolane (DOL). Our simulations support the recent experimental observations as well as theoretical predictions of a non-monotonic behavior of the correlation length with increasing salt concentration. We observe a Debye-Hückel like regime at low concentration, followed by a minimum reached when <i>d/λ<sub>D</sub></i> = 1, where <i>λ<sub>D</sub></i> is the Debye correlation length and d the effective ionic diameter, and an increasing correlation length with salt concentration in very concentrated electrolytes. As in the experiments, we find that the screening length in the concentrated regime follows a universal scaling law as a function <i>d/λ<sub>D</sub></i> for all studied salts. However, the scaling exponent is significantly lower than the experimentally measured one, and lies in the range of the theoretical predictions based on much simpler electrolyte models.</p> </div>

scholarly journals Translocation of structured biomolecule through a vibrating nanopore

2018 ◽  
Author(s):  
M. A. Shahzad
Keyword(s):  
Protein Transport ◽  
Protein Translocation ◽  
Intermediate Frequency ◽  
Global Maximum ◽  
Cylindrical Pore ◽  
Transport Dynamics ◽  
Frequency Regime ◽  
Translocation Time ◽  
Static Channel ◽  
Resonant Activation

ABSTRACTWe study the effect of fluctuating environment in protein transport dynamics. In particular, we investigate the translocation of a structured biomolecule (protein) across a temporally modulated nano-pore. We allow the radius of the cylindrical pore to oscillate harmonically with certain frequency and amplitude about an average radius. The protein is imported inside the pore whose dynamics is influences by the fluctuating nature of the pore. We investigate the dynamic and thermodynamical properties of the translocation process by revealing the statistics of translocation time as a function of the pulling inward force acting along the axis of the pore, and the frequency of the time dependent radius of the channel. We also examine the distribution of translocation time in the intermediate frequency regime. We observe that the shaking mechanism of pore leads to accelerate the translocation process as compared to the static channel that has a radius equal to the mean radius of oscillating pore. Moreover, the translocation time shows a global maximum as a function of frequency of the oscillating radius, hence revealing a resonant activation phenomenon in the dynamics of protein translocation.

scholarly journals Molecular Dynamics Simulations of Structural Changes for a Molten Ag54Cu1 Cluster during Cooling

2022 ◽  
Vol 2148 (1) ◽  
pp. 012005
Author(s):  
Zhijing Zhang
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Shape Factor ◽  
Structural Changes ◽  
Atomic Density ◽  
Atomic Position ◽  
Density Profiles ◽  
Temperature Regimes ◽  
Dynamics Simulations ◽  
Analytical Tools

Abstract Structural changes of an Ag54Cu1 cluster had been computationally studied by molecular dynamics approaches. Packing transition was demonstrated by analytical tools including potential energy, atomic density profiles, and shape factor as well as visually packing images. During the process of temperature decreasing, this cluster preferentially assumes icosahedral geometry. Copper atom usually has an atomic position inside a cluster. As temperature decreases, its position will change. Potential energy shows different temperature regimes in the structural transformation. Atomic density profile gives packing pattern in different region. Shape factor presents the morphology changes of this cluster.

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