Equivalence of sessile droplet dynamics under periodic and steady electric fields

AbstractThe electrohydrodynamics of a sessile droplet under the influence of periodic and steady electric fields in microgravity conditions is theoretically investigated using an inertial lubrication model. Previous studies have revealed that a freely suspended spherical droplet with unequal conductivity and permittivity ratios exhibits distinct dynamics under periodic and equivalent steady forcing in the root mean-square sense. However, it is unclear when (if at all) such distinct dynamics occur for periodic and equivalent steady forcing in the case of sessile droplets. The equivalence between periodic and steady forcing is shown to be governed by the interfacial charge buildup, which further depends on the competition between the charge relaxation and forcing timescales. A circulation-deformation map is introduced for the sessile droplet that acts as a guideline to achieve electric field-induced wetting or dewetting as the case may be. We also demonstrate that a droplet may be rendered either more or less wetting solely by tuning the forcing frequency.

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Effects of an Electric Field on the Conformational Transition of the Protein: Pulsed and Oscillating Electric Fields with Different Frequencies

Polymers ◽

10.3390/polym14010123 ◽

2021 ◽

Vol 14 (1) ◽

pp. 123

Author(s):

Qun Zhang ◽

Dongqing Shao ◽

Peng Xu ◽

Zhouting Jiang

Keyword(s):

Dipole Moment ◽

Secondary Structure ◽

Electric Field ◽

Root Mean Square ◽

Structure Analysis ◽

Electric Fields ◽

Conformational Changes ◽

Pulsed Electric Field ◽

Mean Square ◽

Secondary Structure Analysis

The effect of pulsed and oscillating electric fields with different frequencies on the conformational properties of all-α proteins was investigated by molecular dynamics simulations. The root mean square deviation, the root mean square fluctuation, the dipole moment distribution, and the secondary structure analysis were used to assess the protein samples’ structural characteristics. In the simulation, we found that the higher frequency of the electric field influences the rapid response to the secondary structural transitions. However, the conformational changes measured by RMSD are diminished by applying the electrical field with a higher frequency. During the dipole moment analysis, we found that the magnitude and frequency of the dipole moment was directly related to the strength and frequency of the external electric field. In terms of the type of electric fields, we found that the average values of RMSD and RMSF of whole molecular protein are larger when the protein is exposed in the pulsed electric field. Concerning the typical sample 1BBL, the secondary structure analysis showed that two alpha-helix segments both transit to turns or random coils almost simultaneously when it is exposed in a pulsed electric field. Meanwhile, two segments present the different characteristic times when the transition occurs in the condition of an oscillating electric field. This study also demonstrated that the protein with fewer charged residues or more residues in forming α-helical structures display the higher conformational stability. These conclusions, achieved using MD simulations, provide a theoretical understanding of the effect of the frequency and expression form of external electric fields on the conformational changes of the all-α proteins with charged residues and the guidance for anticipative applications.

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Deformation of an encapsulated bubble in steady and oscillatory electric fields

Journal of Fluid Mechanics ◽

10.1017/jfm.2018.170 ◽

2018 ◽

Vol 844 ◽

pp. 567-596 ◽

Cited By ~ 1

Author(s):

Yunqiao Liu ◽

Dongdong He ◽

Xiaobo Gong ◽

Huaxiong Huang

Keyword(s):

Electric Field ◽

Electric Fields ◽

Equilibrium Shape ◽

Bubble Surface ◽

Axisymmetric Deformation ◽

Uniform Electric Field ◽

Bending Rigidity ◽

Shape Oscillation ◽

Leaky Dielectric Model ◽

Interfacial Charge

In this paper, we investigate the dynamics of an encapsulated bubble in steady and oscillatory electric fields theoretically, based on a leaky dielectric model. On the bubble surface, an applied electric field generates a Maxwell stress, in addition to hydrodynamic traction and membrane mechanical stress. Our model also includes the effect of interfacial charge due to the jump of the current and the stretching of the interface. We focus on the axisymmetric deformation of the encapsulated bubble induced by the electric field and carry out our analysis using Legendre polynomials. In our first example, the encapsulating membrane is modelled as a nearly incompressible interface with bending rigidity. Under a steady uniform electric field, the encapsulated bubble resumes an elongated equilibrium shape, dominated by the second- and fourth-order shape modes. The deformed shape agrees well with experimental observations reported in the literature. Our model reveals that the interfacial charge distribution is determined by the magnitude of the shape modes, as well as the permittivity and conductivity of the external and internal fluids. The effects of the electric field on the natural frequency of the oscillating bubble are also shown. For our second example, we considered a bubble encapsulated with a hyperelastic membrane with bending rigidity, subject to an oscillatory electric field. We show that the bubble can modulate its oscillating frequency and reach a stable shape oscillation at an appreciable amplitude.

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Cellular Processes Involved in Jurkat Cells Exposed to Nanosecond Pulsed Electric Field

International Journal of Molecular Sciences ◽

10.3390/ijms20235847 ◽

2019 ◽

Vol 20 (23) ◽

pp. 5847

Author(s):

Huijuan Li ◽

Shibin Liu ◽

Xue Yang ◽

Yongqian Du ◽

Jiezhang Luo ◽

...

Keyword(s):

Molecular Dynamics ◽

Electric Field ◽

Root Mean Square ◽

Pulsed Electric Field ◽

Jurkat Cells ◽

Mean Square ◽

Hub Genes ◽

Cellular Processes ◽

Nanosecond Pulsed Electric Field ◽

Hub Proteins

Recently, nanosecond pulsed electric field (nsPEF) has been considered as a new tool for tumor therapy, but its molecular mechanism of function remains to be fully elucidated. Here, we explored the cellular processes of Jurkat cells exposed to nanosecond pulsed electric field. Differentially expressed genes (DEGs) were acquired from the GEO2R, followed by analysis with a series of bioinformatics tools. Subsequently, 3D protein models of hub genes were modeled by Modeller 9.21 and Rosetta 3.9. Then, a 100 ns molecular dynamics simulation for each hub protein was performed with GROMACS 2018.2. Finally, three kinds of nsPEF voltages (0.01, 0.05, and 0.5 mV/mm) were used to simulate the molecular dynamics of hub proteins for 100 ns. A total of 1769 DEGs and eight hub genes were obtained. Molecular dynamic analysis, including root mean square deviation (RMSD), root mean square fluctuation (RMSF), and the Rg, demonstrated that the 3D structure of hub proteins was built, and the structural characteristics of hub proteins under different nsPEFs were acquired. In conclusion, we explored the effect of nsPEF on Jurkat cell signaling pathway from the perspective of molecular informatics, which will be helpful in understanding the complex effects of nsPEF on acute T-cell leukemia Jurkat cells.

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QUANTUM COHERENCE OF SUPERLATTICES IN TRIANGLE-WAVE ELECTRIC FIELDS

International Journal of Modern Physics B ◽

10.1142/s0217979200000054 ◽

2000 ◽

Vol 14 (01) ◽

pp. 41-49 ◽

Cited By ~ 5

Author(s):

HAI-FENG LIU ◽

XIAN-GENG ZHAO

Keyword(s):

Electric Field ◽

Exact Solutions ◽

Electric Fields ◽

Quantum Coherence ◽

Mean Square Displacement ◽

Initial Distribution ◽

Coherent Motion ◽

Mean Square ◽

Long Period ◽

The Mean

The problem of coherent motion of an electron in a long period superlattice driven by a triangle-wave electric field is studied. Exact solutions for the amplitude propagators, the field-induced polarization, the mean-square displacement, and the quasienergy spectrum of any initial distribution and long-range hopping coupling are obtained generally. Total collapse of the quasienergy spectrum is found to take place at certain field parameters, which leads to the transition between localization and delocalization. The transport property of the system is also investigated.

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Dynamics Behaviors of Droplet on Hydrophobic Surfaces Driven by Electric Field

Micromachines ◽

10.3390/mi10110778 ◽

2019 ◽

Vol 10 (11) ◽

pp. 778 ◽

Cited By ~ 1

Author(s):

Jie Liu ◽

Sheng Liu

Keyword(s):

Electric Field ◽

Electric Fields ◽

Substrate Surface ◽

Contact Angles ◽

Droplet Microfluidics ◽

Phase Field Method ◽

Sessile Droplet ◽

Hydrophobic Surfaces ◽

Droplet Motion ◽

Plate Electrode

Droplet microfluidic technology achieves precise manipulation of droplet behaviors by designing and controlling the flow and interaction of various incompatible fluids. The electric field provides a non-contact, pollution-free, designable and promising method for droplet microfluidics. Since the droplet behaviors in many industrial and biological applications occur on the contact surface and the properties of droplets and the surrounding environment are not consistent, it is essential to understand fundamentally the sessile droplet motion and deformation under various conditions. This paper reports a technique using the pin-plate electrode to generate non-uniform dielectrophoresis (DEP) force to control sessile droplets on hydrophobic surfaces. The electrohydrodynamics phenomena of the droplet motion and deformation are simulated using the phase-field method. It is found that the droplet moves along the substrate surface to the direction of higher electric field strength, and is accompanied with a certain offset displacement. In addition, the effect of pin electric potentials, surface contact angles and droplet volumes on the droplet motion and deformation are also studied and compared. The results show that higher potentials, more hydrophobic surfaces and larger droplet volumes exhibit greater droplet horizontal displacement and offset displacement. But for the droplet vertical displacement, it is found that during the first revert process, the release of the surface tension can make the droplet with low potentials, small contact angles or small droplet volumes span from negative to positive. These results will be helpful for future operations encountered in sessile droplets under non-uniform electric fields towards the droplet microfluidics applications.

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Critical heat flux enhancement in microgravity conditions coupling microstructured surfaces and electrostatic field

npj Microgravity ◽

10.1038/s41526-021-00167-3 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Alekos Ioannis Garivalis ◽

Giacomo Manfredini ◽

Giacomo Saccone ◽

Paolo Di Marco ◽

Artyom Kossolapov ◽

...

Keyword(s):

Heat Flux ◽

Electric Field ◽

Critical Heat Flux ◽

Electric Fields ◽

Parabolic Flight ◽

Dielectric Fluid ◽

Two Phase ◽

Microstructured Surfaces ◽

Microgravity Conditions ◽

Plain Surface

AbstractWe run pool boiling experiments with a dielectric fluid (FC-72) on Earth and on board an ESA parabolic flight aircraft able to cancel the effects of gravity, testing both highly wetting microstructured surfaces and plain surfaces and applying an external electric field that creates gravity-mimicking body forces. Our results reveal that microstructured surfaces, known to enhance the critical heat flux on Earth, are also useful in microgravity. An enhancement of the microgravity critical heat flux on a plain surface can also be obtained using the electric field. However, the best boiling performance is achieved when these techniques are used together. The effects created by microstructured surfaces and electric fields are synergistic. They enhance the critical heat flux in microgravity conditions up to 257 kW/m2, which is even higher than the value measured on Earth on a plain surface (i.e., 168 kW/m2). These results demonstrate the potential of this synergistic approach toward very compact and efficient two-phase heat transfer systems for microgravity applications.

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Supplemental Material for Examining the Reliability of Interval Level Data Using Root Mean Square Differences and Concordance Correlation Coefficients

Psychological Methods ◽

10.1037/a0023351.supp ◽

2011 ◽

Keyword(s):

Root Mean Square ◽

Correlation Coefficients ◽

Mean Square ◽

Concordance Correlation ◽

Level Data

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Tuning the Electric Field Response of MOFs by Rotatable Dipolar Linkers

10.26434/chemrxiv.8153198.v1 ◽

2019 ◽

Author(s):

Johannes P. Dürholt ◽

Babak Farhadi Jahromi ◽

Rochus Schmid

Keyword(s):

Electric Field ◽

Electric Fields ◽

Structural Changes ◽

Dielectric Behavior ◽

Two Dimensions ◽

Dielectric Constants ◽

Electric Response ◽

Dipole Strength ◽

Metal Organic ◽

Dynamics Simulations

Recently the possibility of using electric fields as a further stimulus to trigger structural changes in metal-organic frameworks (MOFs) has been investigated. In general, rotatable groups or other types of mechanical motion can be driven by electric fields. In this study we demonstrate how the electric response of MOFs can be tuned by adding rotatable dipolar linkers, generating a material that exhibits paralectric behavior in two dimensions and dielectric behavior in one dimension. The suitability of four different methods to compute the relative permittivity κ by means of molecular dynamics simulations was validated. The dependency of the permittivity on temperature T and dipole strength μ was determined. It was found that the herein investigated systems exhibit a high degree of tunability and substantially larger dielectric constants as expected for MOFs in general. The temperature dependency of κ obeys the Curie-Weiss law. In addition, the influence of dipolar linkers on the electric field induced breathing behavior was investigated. With increasing dipole moment, lower field strength are required to trigger the contraction. These investigations set the stage for an application of such systems as dielectric sensors, order-disorder ferroelectrics or any scenario where movable dipolar fragments respond to external electric fields.

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