Ion selectivity of temperature-induced and electric field induced pores in dipalmitoylphosphatidylcholine vesicles

Biochemistry ◽  
1985 ◽  
Vol 24 (12) ◽  
pp. 2884-2888 ◽  
Author(s):  
E. Mostafa El-Mashak ◽  
Tian Yow Tsong
Keyword(s):  
Electric Field ◽  
Ion Selectivity

scholarly journals Ion transport through a nanoporous C2N membrane: the effect of electric field and layer number

RSC Advances ◽  
2018 ◽  
Vol 8 (64) ◽  
pp. 36705-36711 ◽  
Author(s):  
You-sheng Yu ◽  
Lu-yi Huang ◽  
Xiang Lu ◽  
Hong-ming Ding
Keyword(s):  
Electric Field ◽  
Ion Transport ◽  
Molecular Dynamic ◽  
Ion Selectivity ◽  
Water Desalination ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations ◽  
Layer Number

Using all-atom molecular dynamic simulations, we show that a monolayer C2N membrane possesses higher permeability and excellent ion selectivity, and that multilayer C2N membranes have promising potential for water desalination.

Migration of ion-exchange particles driven by a uniform electric field

2010 ◽  
Vol 655 ◽  
pp. 105-121 ◽  
Author(s):  
EHUD YARIV
Keyword(s):  
Zeta Potential ◽  
Electric Field ◽  
Boundary Conditions ◽  
Salt Concentration ◽  
Ion Selectivity ◽  
Particle Surface ◽  
Dirichlet Condition ◽  
Transport Processes ◽  
Electrokinetic Flow ◽  
Particle Boundary

A cation-selective conducting particle is suspended in an electrolyte solution and is exposed to a uniformly applied electric field. The electrokinetic transport processes are described in a closed mathematical model, consisting of differential equations, representing the physical transport in the electrolyte, and boundary conditions, representing the physicochemical conditions on the particle boundary and at large distances away from it. Solving this mathematical problem would in principle provide the electrokinetic flow about the particle and its concomitant velocity relative to the otherwise quiescent fluid.Using matched asymptotic expansions, this problem is analysed in the thin-Debye-layer limit. A macroscale description is extracted, whereby effective boundary conditions represent appropriate asymptotic matching with the Debye-scale fields. This description significantly differs from that corresponding to a chemically inert particle. Thus, ion selectivity on the particle surface results in a macroscale salt concentration polarization, whereby the electric potential is rendered non-harmonic. Moreover, the uniform Dirichlet condition governing this potential on the particle surface is transformed into a non-uniform Dirichlet condition on the macroscale particle boundary. The Dukhin–Derjaguin slip formula still holds, but with a non-uniform zeta potential that depends, through the cation-exchange kinetics, upon the salt concentration and electric field distributions. For weak fields, an approximate solution is obtained as a perturbation to a reference state. The linearized solution corresponds to a uniform zeta potential; it predicts a particle velocity which is proportional to the applied field. The associated electrokinetic flow is driven by two different agents, electric field and salinity gradients, which are of comparable magnitude. Accordingly, this flow differs significantly from that occurring in electrophoresis of chemically inert particles.

scholarly journals Heavy Metals Nanofiltration Using Nanotube and Electric Field by Molecular Dynamics

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Tiago da Silva Arouche ◽  
Rosely Maria dos Santos Cavaleiro ◽  
Phelipe Seiichi Martins Tanoue ◽  
Tais Sousa de Sa Pereira ◽  
Tarciso Andrade Filho ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Boron Nitride ◽  
Electric Field ◽  
Metal Ions ◽  
External Electric Field ◽  
Ion Selectivity ◽  
Intermolecular Forces ◽  
Water Molecules ◽  
The Impact

Heavy metal contamination in the world is increasing the impact on the environment and human life. Currently, carbon nanotubes and boron are some possible ideals for the nanofiltration of heavy metals due to the property of ion selectivity, optimized by the applications of the surface and the application of an external electric field. In this work, molecular dynamic was used to transport water with heavy metals under the force exerted by the electric field action inside nanotubes. This external electric field generates a propelling electrical force to expel only water molecules and retain ions. These metal ions were retained to pass through only water molecules, under constant temperature and pressure, for a time of 100 ps under the action of electric fields with values from 10-8 to 10-1 au. Each of the metallic contaminants evaluated (Pb2+, Cd2+, Fe2+, Zn2+, Hg2+) was subjected to molecular test simulations in the water. It was found that the measurement of the intensity of the electric field increased or the percentage of filtered water reduced (in both nanotubes), in which the intramolecular and intermolecular forces intensified by the action of the electric field contribute to retain the heavy metal ions due to the evanescent effect. The best results for nanofiltration in carbon and boron nanotubes occur under the field 10-8 au. Since the filtration in the boron nitride nanotubes, a small difference in the percentage of filtered water for the boron nitride nanotube was the most effective (90 to 98%) in relation to the carbon nanotube (80 to 90%). The greater hydrophobicity and thermal stability of boron nanotubes are some of the factors that contributed to this result.

scholarly journals Intrinsic versus extrinsic voltage sensitivity of blocker interaction with an ion channel pore

2010 ◽  
Vol 135 (2) ◽  
pp. 149-167 ◽  
Author(s):  
Juan Ramón Martínez-François ◽  
Zhe Lu
Keyword(s):  
Electric Field ◽  
Voltage Dependence ◽  
Ion Selectivity ◽  
Systematic Investigation ◽  
Selectivity Filter ◽  
Voltage Sensitivity ◽  
Channel Block ◽  
Boltzmann Function ◽  
Voltage Dependent ◽  
Gated Channel

Many physiological and synthetic agents act by occluding the ion conduction pore of ion channels. A hallmark of charged blockers is that their apparent affinity for the pore usually varies with membrane voltage. Two models have been proposed to explain this voltage sensitivity. One model assumes that the charged blocker itself directly senses the transmembrane electric field, i.e., that blocker binding is intrinsically voltage dependent. In the alternative model, the blocker does not directly interact with the electric field; instead, blocker binding acquires voltage dependence solely through the concurrent movement of permeant ions across the field. This latter model may better explain voltage dependence of channel block by large organic compounds that are too bulky to fit into the narrow (usually ion-selective) part of the pore where the electric field is steep. To date, no systematic investigation has been performed to distinguish between these voltage-dependent mechanisms of channel block. The most fundamental characteristic of the extrinsic mechanism, i.e., that block can be rendered voltage independent, remains to be established and formally analyzed for the case of organic blockers. Here, we observe that the voltage dependence of block of a cyclic nucleotide–gated channel by a series of intracellular quaternary ammonium blockers, which are too bulky to traverse the narrow ion selectivity filter, gradually vanishes with extreme depolarization, a predicted feature of the extrinsic voltage dependence model. In contrast, the voltage dependence of block by an amine blocker, which has a smaller “diameter” and can therefore penetrate into the selectivity filter, follows a Boltzmann function, a predicted feature of the intrinsic voltage dependence model. Additionally, a blocker generates (at least) two blocked states, which, if related serially, may preclude meaningful application of a commonly used approach for investigating channel gating, namely, inferring the properties of the activation gate from the kinetics of channel block.

Electric Field-Responsive Nanopores with Ion Selectivity: Controlling Based on Transport Resistance

2016 ◽  
Vol 39 (5) ◽  
pp. 993-997 ◽  
Author(s):  
Yudan Zhu ◽  
Yang Ruan ◽  
Ximing Wu ◽  
Xiaohua Lu ◽  
Yumeng Zhang ◽  
...  
Keyword(s):  
Electric Field ◽  
Ion Selectivity

scholarly journals The Selective Transport of Ions in Charged Nanopore with Combined Multi-Physics Fields

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7012
Author(s):  
Pengfei Ma ◽  
Jianxiang Zheng ◽  
Danting Zhao ◽  
Wenjie Zhang ◽  
Gonghao Lu ◽  
...  
Keyword(s):  
Electric Field ◽  
High Performance ◽  
Ion Selectivity ◽  
Chemical Separation ◽  
Hydraulic Pressure ◽  
Selectivity Ratio ◽  
Separation Effect ◽  
Selective Transport ◽  
Depth Analysis ◽  
Transport Of Ions

The selective transport of ions in nanopores attracts broad interest due to their potential applications in chemical separation, ion filtration, seawater desalination, and energy conversion. The ion selectivity based on the ion dehydration and steric hindrance is still limited by the very similar diameter between different hydrated ions. The selectivity can only separate specific ion species, lacking a general separation effect. Herein, we report the highly ionic selective transport in charged nanopore through the combination of hydraulic pressure and electric field. Based on the coupled Poisson–Nernst–Planck (PNP) and Navier–Stokes (NS) equations, the calculation results suggest that the coupling of hydraulic pressure and electric field can significantly enhance the ion selectivity compared to the results under the single driven force of hydraulic pressure or electric field. Different from the material-property-based ion selective transport, this method endows the general separation effect between different kinds of ions. Through the appropriate combination of hydraulic pressure and electric field, an extremely high selectivity ratio can be achieved. Further in-depth analysis reveals the influence of nanopore diameter, surface charge density and ionic strength on the selectivity ratio. These findings provide a potential route for high-performance ionic selective transport and separation in nanofluidic systems.

How an electric field can modulate the metal ion selectivity of protein binding sites: insights from DFT/PCM calculations

2018 ◽  
Vol 20 (38) ◽  
pp. 24633-24640 ◽  
Author(s):  
Todor Dudev ◽  
Sonia Ilieva ◽  
Lyudmila Doudeva
Keyword(s):  
Electric Field ◽  
Protein Binding ◽  
Binding Site ◽  
Binding Sites ◽  
Metal Ion ◽  
Ion Selectivity ◽  
Protein Binding Site ◽  
Protein Binding Sites ◽  
Metal Selectivity ◽  
Metal Ion Selectivity

An electric field (internal or external) is a potent force that can modulate the metal selectivity of a protein binding site.

Resolution in photoelectron microscopy

1991 ◽  
Vol 49 ◽  
pp. 458-459
Author(s):  
G. F. Rempfer
Keyword(s):  
Electron Microscopy ◽  
Electric Field ◽  
Ultraviolet Light ◽  
Uniform Field ◽  
Virtual Image ◽  
Lens System ◽  
Photoemission Electron Microscopy ◽  
Planar Electrode ◽  
Electron Lens ◽  
Photoemission Electron

In photoelectron microscopy (PEM), also called photoemission electron microscopy (PEEM), the image is formed by electrons which have been liberated from the specimen by ultraviolet light. The electrons are accelerated by an electric field before being imaged by an electron lens system. The specimen is supported on a planar electrode (or the electrode itself may be the specimen), and the accelerating field is applied between the specimen, which serves as the cathode, and an anode. The accelerating field is essentially uniform except for microfields near the surface of the specimen and a diverging field near the anode aperture. The uniform field forms a virtual image of the specimen (virtual specimen) at unit lateral magnification, approximately twice as far from the anode as is the specimen. The diverging field at the anode aperture in turn forms a virtual image of the virtual specimen at magnification 2/3, at a distance from the anode of 4/3 the specimen distance. This demagnified virtual image is the object for the objective stage of the lens system.

Field-assisted ionization theory for microscopists

1994 ◽  
Vol 52 ◽  
pp. 820-821
Author(s):  
Patrick P. Camus
Keyword(s):  
Electric Field ◽  
Electron Tunneling ◽  
Ionization Probability ◽  
Critical Distance ◽  
Tunneling Probability ◽  
Field Ionization ◽  
Radius Of Curvature ◽  
Field Evaporation ◽  
A Value ◽  
Ion Emission

The theory of field ion emission is the study of electron tunneling probability enhanced by the application of a high electric field. At subnanometer distances and kilovolt potentials, the probability of tunneling of electrons increases markedly. Field ionization of gas atoms produce atomic resolution images of the surface of the specimen, while field evaporation of surface atoms sections the specimen. Details of emission theory may be found in monographs.Field ionization (FI) is the phenomena whereby an electric field assists in the ionization of gas atoms via tunneling. The tunneling probability is a maximum at a critical distance above the surface,xc, Fig. 1. Energy is required to ionize the gas atom at xc, I, but at a value reduced by the appliedelectric field, xcFe, while energy is recovered by placing the electron in the specimen, φ. The highest ionization probability occurs for those regions on the specimen that have the highest local electric field. Those atoms which protrude from the average surfacehave the smallest radius of curvature, the highest field and therefore produce the highest ionizationprobability and brightest spots on the imaging screen, Fig. 2. This technique is called field ion microscopy (FIM).

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