scholarly journals Deformation but not migration and rotation – a model study on vesicle biomechanics in a uniform DC electric field

2016 ◽  
Vol 3 (1) ◽  
pp. 18
Author(s):  
Hui Ye ◽  
Austen Curcuru
Keyword(s):  
Cell Membrane ◽  
Electric Field ◽  
Electric Fields ◽  
Radial Pressure ◽  
Biological Properties ◽  
Phospholipid Bilayer ◽  
Biological Cell ◽  
Biological Cells ◽  
Giant Vesicles ◽  
Dc Electric Field

Background: Biological cells migrate, deform and rotate in various types of electric fields, which have significant impact on the normal cellular physiology. To investigate electrically-induced deformation, researchers have used artificial giant vesicles that mimic the phospholipid bilayer cell membrane. Containing primarily the neutral molecule phosphatidylcholine, these vesicles deformed under evenly distributed, strong direct current (DC) electric fields. Interestingly, they did not migrate or rotate. A biophysical mechanism underlying the kinematic differences between the biological cells and the vesicles under electric stimulation has not been worked out. Methods: We modeled the vesicle as a leaky, dielectric sphere and computed the surface pressure, rotation torques and translation forces applied on the vesicle by a DC electric field. We compared these measurements with those in a biological cell that contains non-zero, intrinsic charges (carried by the functional groups on the membrane). Results: For both the vesicle and the cell, the electrically-induced charges interacted with the local electric field to generate radial pressure for deformation. However, due to the symmetrical distribution of both the charges and the electric field on the vesicle/cell surface, the electric field could not generate net translation force or rotational torques. For a biological cell, the intrinsic charges carried by the cell membrane could account for its migration and rotation in a DC electric field. Conclusions: Results from this work suggests an interesting control diagram of cellular kinematics and movements by the electric field: cell deformation and migration can be manipulated by directly targeting different charged groups on the membrane. Fate of the cell in an electric field depends not only on the delicately controlled field parameters, but also on the biological properties of the cell.

scholarly journals Meteor plasma trails: effects of external electric field

2009 ◽  
Vol 27 (1) ◽  
pp. 279-296 ◽  
Author(s):  
Y. S. Dimant ◽  
M. M. Oppenheim ◽  
G. M. Milikh
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Electrostatic Interaction ◽  
Geomagnetic Field ◽  
Dense Plasma ◽  
Dc Electric Field ◽  
E Region ◽  
Flow Through ◽  
Short Circuits ◽  
Meteor Plasma

Abstract. Meteoroids traversing the E-region ionosphere leave behind extended columns of elevated ionization known as the meteor plasma trails. To accurately interpret radar signals from trails and use them for diagnostics, one needs to model plasma processes associated with their structure and evolution. This paper describes a 3-D quantitative theory of the electrostatic interaction between a dense plasma trail, the ionosphere, and a DC electric field driven by an external dynamo. A simplified water-bag model of the meteor plasma shows that the highly conducting trail efficiently short-circuits the ionosphere and creates a vast region of currents that flow through and around the trail. We predict that the trail can induce electric fields reaching a few V/m, both perpendicular and parallel to the geomagnetic field. The former may drive plasma instabilities, while the latter may lead to strong heating of ionospheric electrons. We discuss physical and observational implications of these processes.

scholarly journals Effect of input voltage frequency on the distribution of electrical stresses on the cell surface based on single-cell dielectrophoresis analysis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kia Dastani ◽  
Mahdi Moghimi Zand ◽  
Hanie Kavand ◽  
Reza Javidi ◽  
Amin Hadi ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Cell Surface ◽  
Electric Field ◽  
Single Cell ◽  
Electric Fields ◽  
Applied Electric Field ◽  
Structural Changes ◽  
Cell Deformation ◽  
Cell Permeabilization ◽  
Immersed Interface Method

AbstractElectroporation is defined as cell membrane permeabilization under the application of electric fields. The mechanism of hydrophilic pore formation is not yet well understood. When cells are exposed to electric fields, electrical stresses act on their surfaces. These electrical stresses play a crucial role in cell membrane structural changes, which lead to cell permeabilization. These electrical stresses depend on the dielectric properties of the cell, buffer solution, and the applied electric field characteristics. In the current study, the effect of electric field frequency on the electrical stresses distribution on the cell surface and cell deformation is numerically and experimentally investigated. As previous studies were mostly focused on the effect of electric fields on a group of cells, the present study focused on the behavior of a single cell exposed to an electric field. To accomplish this, the effect of cells on electrostatic potential distribution and electric field must be considered. To do this, Fast immersed interface method (IIM) was used to discretize the governing quasi-electrostatic equations. Numerical results confirmed the accuracy of fast IIM in satisfying the internal electrical boundary conditions on the cell surface. Finally, experimental results showed the effect of applied electric field on cell deformation at different frequencies.

Effect of Microstructure on Lifetime Performance of Barium Titanate Ceramics Under DC and AC Electric Fields

2010 ◽  
Author(s):  
Jay Shieh
Keyword(s):  
Fatigue Strength ◽  
Barium Titanate ◽  
Electric Field ◽  
Electric Fields ◽  
Time To Failure ◽  
Electrical Loading ◽  
Ac Electric Fields ◽  
Lifetime Performance ◽  
Weibull Statistical Analysis ◽  
Dc Electric Field

Bulk barium titanate (BaTiO3 ) ceramic specimens with bimodal microstructures are prepared and their dielectric and fatigue strengths are investigated under an alternating current (AC) electric field and a direct current (DC) electric field. It is found that under AC electrical loading, both the dielectric and fatigue strengths decrease with increasing amount of coarse abnormal grains. The scatter of the AC fatigue strength is characterized with the Weibull statistics. The extent of scatter of the AC fatigue strength data correlates strongly with the size distribution of the coarse grains. Such correlation is resulted from the presence of intrinsic defects within the microstructure. For DC electrical loading, the time to failure of the specimens with coarse abnormal grains is significantly shorter than the lifetimes of the specimens with only small normal grains. It is found that under a DC electric field of 6 MVm−1, the BaTiO3 specimens would fail within 200 h when abnormal grains are present in the microstructure. However, the lifetimes of the specimens containing abnormal grains vary significantly from one to another. The Weibull statistical analysis indicates that the amount of abnormal grains has little influence on the lifetime performance of bulk BaTiO3 ceramics under large DC electric fields. In most of the failed BaTiO3 specimens under DC electrical loading, regardless of their lifetimes, large through-thickness round holes with recrystallization features are present. A mixed failure mode consisting of avalanche and thermal breakdowns is proposed for the failed specimens.

Modeling of Nanoparticle-Mediated Electric Field Enhancement Inside Biological Cells Exposed to AC Electric Fields

2009 ◽  
Vol 48 (8) ◽  
pp. 087001 ◽  
Author(s):  
Pawan K. Tiwari ◽  
Sung Kil Kang ◽  
Gon Jun Kim ◽  
Jun Choi ◽  
A.-A. H. Mohamed ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Field Enhancement ◽  
Biological Cells ◽  
Electric Field Enhancement ◽  
Ac Electric Fields

The Effect of Growth, Migration and Bacterial Cellulose Synthesis of Gluconacetobacter xylinus in Presence of Direct Current Electric Field Condition

2012 ◽  
Vol 550-553 ◽  
pp. 1108-1113 ◽  
Author(s):  
Lin Yan ◽  
Shi Ru Jia ◽  
Xin Tong Zheng ◽  
Cheng Zhong ◽  
Miao Liu ◽  
...  
Keyword(s):  
Electric Field ◽  
Bacterial Cellulose ◽  
Electric Fields ◽  
Direct Current ◽  
Cellulose Fiber ◽  
Sem Analysis ◽  
Cellulose Synthesis ◽  
Gluconacetobacter Xylinus ◽  
Growth State ◽  
Dc Electric Field

In this study, the movement and orientation of bacteria cells were controlled by direct current(DC) electric fields, result in altering alignment of bacterial cellulose nanofiber and further changing the 3-dimensional network structure of bacterial cellulose. A modified swarm plate assay was performed to investigate the migration of Gluconacetobacter xylinus cells which exposed in DC electric field. It suggested that the cells moved toward to negative pole and with the increasement of the electric field strength the velocity will also increase. The SEM analysis demonstrated that the cellulose fiber bundles which synthesized at 1V/cm have lager diameter and a trend toward one direction. Meanwhile the growth state of G.xylinus in the presence of DC electric field was also being observed.

Endovascular Nonthermal Irreversible Electroporation: A Finite Element Analysis

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Elad Maor ◽  
Boris Rubinsky
Keyword(s):  
Finite Element ◽  
Electric Field ◽  
Electric Fields ◽  
Joule Heating ◽  
Arterial Wall ◽  
Thermal Damage ◽  
Irreversible Electroporation ◽  
Phospholipid Bilayer ◽  
Tissue Ablation ◽  
Nonthermal Irreversible Electroporation

Tissue ablation finds an increasing use in modern medicine. Nonthermal irreversible electroporation (NTIRE) is a biophysical phenomenon and an emerging novel tissue ablation modality, in which electric fields are applied in a pulsed mode to produce nanoscale defects to the cell membrane phospholipid bilayer, in such a way that Joule heating is minimized and thermal damage to other molecules in the treated volume is reduced while the cells die. Here we present a two-dimensional transient finite element model to simulate the electric field and thermal damage to the arterial wall due to an endovascular NTIRE novel device. The electric field was used to calculate the Joule heating effect, and a transient solution of the temperature is presented using the Pennes bioheat equation. This is followed by a kinetic model of the thermal damage based on the Arrhenius formulation and calculation of the Henriques and Moritz thermal damage integral. The analysis shows that the endovascular application of 90, 100 μs pulses with a potential difference of 600 V can induce electric fields of 1000 V/cm and above across the entire arterial wall, which are sufficient for irreversible electroporation. The temperature in the arterial wall reached a maximum of 66.7°C with a pulse frequency of 4 Hz. Thermal damage integral showed that this protocol will thermally damage less than 2% of the molecules around the electrodes. In conclusion, endovascular NTIRE is possible. Our study sets the theoretical basis for further preclinical and clinical trials with endovascular NTIRE.

Derivation of radial electric fields using kinetic theory in tokamak

2013 ◽  
Vol 79 (5) ◽  
pp. 513-517
Author(s):  
K. NOORI ◽  
P. KHORSHID ◽  
M. AFSARI
Keyword(s):  
Kinetic Theory ◽  
Electric Field ◽  
Electric Fields ◽  
Driving Forces ◽  
Radial Electric Field ◽  
Radial Pressure ◽  
Momentum Balance ◽  
Balance Equations ◽  
Radial Pressure Gradient ◽  
Poloidal Rotation

AbstractIn the current study, radial electric field with fluid equations has been calculated. The calculation started with kinetic theory, Boltzmann and momentum balance equations were derived, the negligible terms compared with others were eliminated, and the radial electric field expression in steady state was derived. As mentioned in previous researches, this expression includes all types of particles such as electrons, ions, and neutrals. The consequence of this solution reveals that three major driving forces contribute in radial electric field: radial pressure gradient, poloidal rotation, and toroidal rotation; rotational terms mean Lorentz force. Therefore, radial electric field and plasma rotation are connected through the radial momentum balance.

scholarly journals Compact Electro-Permeabilization System for Controlled Treatment of Biological Cells and Cell Medium Conductivity Change Measurement

2014 ◽  
Vol 14 (5) ◽  
pp. 279-284 ◽  
Author(s):  
Vitalij Novickij ◽  
Audrius Grainys ◽  
Jurij Novickij ◽  
Sonata Tolvaisiene ◽  
Svetlana Markovskaja
Keyword(s):  
Experimental Data ◽  
Cell Membrane ◽  
Electric Field ◽  
Ion Concentration ◽  
Biological Cells ◽  
Conductivity Change ◽  
Controlled Treatment ◽  
Concentration Changes ◽  
Cell Medium ◽  
Medium Conductivity

Abstract Subjection of biological cells to high intensity pulsed electric field results in the permeabilization of the cell membrane. Measurement of the electrical conductivity change allows an analysis of the dynamics of the process, determination of the permeabilization thresholds, and ion efflux influence. In this work a compact electro-permeabilization system for controlled treatment of biological cells is presented. The system is capable of delivering 5 μs - 5 ms repetitive square wave electric field pulses with amplitude up to 1 kV. Evaluation of the cell medium conductivity change is implemented in the setup, allowing indirect measurement of the ion concentration changes occurring due to the cell membrane permeabilization. The simulation model using SPICE and the experimental data of the proposed system are presented in this work. Experimental data with biological cells is also overviewed

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