Travelling-Wave Dipolophoresis: Levitation and Electrorotation of Janus Nanoparticles

Touvia Miloh; Jacob Nagler

doi:10.3390/mi12020114

Travelling-Wave Dipolophoresis: Levitation and Electrorotation of Janus Nanoparticles

Micromachines ◽

10.3390/mi12020114 ◽

2021 ◽

Vol 12 (2) ◽

pp. 114

Author(s):

Touvia Miloh ◽

Jacob Nagler

Keyword(s):

Theoretical Study ◽

Weak Field ◽

Travelling Wave ◽

Janus Particles ◽

Time Harmonic ◽

Janus Nanoparticles ◽

Polarizable Particle ◽

Analytic Expressions ◽

Angular Velocities ◽

Freely Suspended

We present a theoretical study of the hydrodynamic and electrokinetic response of both metallic spherical polarized colloids as well as metallodielectic Janus particles, which are subjected to an arbitrary non-uniform ambient electric field (DC or AC forcing). The analysis is based on employing the linearized ‘standard’ model (Poisson–Nernst–Planck formulation) and on the assumptions of a ‘weak’ field and small Debye scale. In particular, we consider cases of linear and helical time-harmonic travelling-wave excitations and provide explicit expressions for the resulting dielectrophoretic and induced-charge electrophoretic forces and moments, exerted on freely suspended particles. The new analytic expressions thus derived for the linear and angular velocities of the initially uncharged polarizable particle are compared against some available solutions. We also analyze the levitation problem (including stability) of metallic and Janus particles placed in a cylindrical (insulating or conducting) pore near a powered electrode.

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Mobility Enhancement in Square Quantum Wells: Symmetric Modulation of the Envelop Wave Function

Communications in Physics ◽

10.15625/0868-3166/20/3/2212 ◽

2010 ◽

Vol 20 (3) ◽

pp. 193

Author(s):

Doan Nhat Quang ◽

Nguyen Huyen Tung ◽

Nguyen Trung Hong ◽

Tran Thi Hai

Keyword(s):

Experimental Data ◽

Wave Function ◽

Low Temperature ◽

Quantum Wells ◽

Quantum Transport ◽

Variational Approach ◽

Theoretical Study ◽

Recent Experimental Data ◽

Carrier Distribution ◽

Analytic Expressions

We present a theoretical study of the effects from symmetric modulation of the envelop wave function on quantum transport in square quantum wells (QWs). Within the variational approach we obtain analytic expressions for the carrier distribution and their scattering in symmetric two-side doped square QWs. Roughness-induced scattering are found significantly weaker than those in the asymmetric one-side doped counterpart. Thus, we propose symmetric modulation of the wave function as an efficient method for enhancement of the roughness-limited QW mobility. Our theory is able to well reproduce the recent experimental data about low-temperature transport of electrons and holes in two-side doped square QWs, e.g., the mobility dependence on the channel width, which have not been explained so far.

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Rayleigh wave motions in an orthotropic half-space under time-harmonic loadings: A theoretical study

Applied Mathematical Modelling ◽

10.1016/j.apm.2020.06.006 ◽

2020 ◽

Vol 87 ◽

pp. 171-179

Author(s):

Duy Kien Dao ◽

VanTrung Ngo ◽

Haidang Phan ◽

Chi Vinh Pham ◽

Jaesun Lee ◽

...

Keyword(s):

Rayleigh Wave ◽

Half Space ◽

Theoretical Study ◽

Time Harmonic

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A theoretical study of a possible model of paramagnetic alums at low temperatures

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1940.0086 ◽

1940 ◽

Vol 176 (965) ◽

pp. 203-213 ◽

Cited By ~ 20

Keyword(s):

Magnetic Field ◽

Low Temperatures ◽

Theoretical Study ◽

Spontaneous Magnetization ◽

Critical Value ◽

Transition Curve ◽

Thin Specimen ◽

First Order ◽

Freely Suspended ◽

Line Of Critical Points

An attempt is made to examine theoretically the properties of paramagnetic alums at low temperatures. The model taken is a lattice of freely suspended magnets, all interactions except purely magnetic being neglected. Even with this simplification it is impossible at present to make rigorous calculations of the partition function, either on classical or quantum lines. A simple model is proposed, which is really a generalization of the Bragg - Williams theory enabling one to take account of the effect of a magnetic field. The few configurations whose energies are known are used to fix arbitrary constants in the expression assumed for the energy. The theory predicts that the state of lowest energy is either a spontaneously magnetized, state for a long thin specimen, or a state in which alternate rows of magnets point in opposite directions for a sphere, spontaneous magnetization appearing in an ellipsoid with an eccentricity greater than a certain critical value. The transition curve bounding the region in which the antiparallel state is stable consists partly of a line of Curie points corresponding to transitions of the second, order, passing smoothly into a line of critical points corresponding to a transition of the first order. The effect of shape on the magnetic properties of the specimen seems to be experimentally verified, but the rough nature of the theory prevents it being more than qualitative.

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Snakes mimic earthworms: propulsion using rectilinear travelling waves

Journal of The Royal Society Interface ◽

10.1098/rsif.2013.0188 ◽

2013 ◽

Vol 10 (84) ◽

pp. 20130188 ◽

Cited By ~ 31

Author(s):

Hamidreza Marvi ◽

Jacob Bridges ◽

David L. Hu

Keyword(s):

Theoretical Study ◽

Travelling Waves ◽

Vertical Motion ◽

Muscular Contraction ◽

Travelling Wave ◽

Wave Frequency ◽

One Dimensional ◽

Anatomical Constraints ◽

Local Body ◽

Body Lifting

In rectilinear locomotion, snakes propel themselves using unidirectional travelling waves of muscular contraction, in a style similar to earthworms. In this combined experimental and theoretical study, we film rectilinear locomotion of three species of snakes, including red-tailed boa constrictors, Dumeril's boas and Gaboon vipers. The kinematics of a snake's extension–contraction travelling wave are characterized by wave frequency, amplitude and speed. We find wave frequency increases with increasing body size, an opposite trend than that for legged animals. We predict body speed with 73–97% accuracy using a mathematical model of a one-dimensional n -linked crawler that uses friction as the dominant propulsive force. We apply our model to show snakes have optimal wave frequencies: higher values increase Froude number causing the snake to slip; smaller values decrease thrust and so body speed. Other choices of kinematic variables, such as wave amplitude, are suboptimal and appear to be limited by anatomical constraints. Our model also shows that local body lifting increases a snake's speed by 31 per cent, demonstrating that rectilinear locomotion benefits from vertical motion similar to walking.

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Suppressing Flutter Vibrations by Parametric Inertia Excitation

Journal of Applied Mechanics ◽

10.1115/1.3063631 ◽

2009 ◽

Vol 76 (3) ◽

Cited By ~ 5

Author(s):

Fadi Dohnal ◽

Aleš Tondl

Keyword(s):

Parametric Excitation ◽

Theoretical Study ◽

Open Loop ◽

Elastic Instability ◽

Excitation Mechanism ◽

Combination Frequency ◽

Concentrated Mass ◽

Time Harmonic ◽

Flow Induced Vibrations ◽

First Time

A theoretical study of a slender engineering structure with lateral and angular deflections is investigated under the action of flow-induced vibrations. This aero-elastic instability excites and couples the system’s bending and torsion modes. Semiactive means due to open-loop parametric excitation are introduced to stabilize this self-excitation mechanism. The parametric excitation mechanism is modeled by time-harmonic variation in the concentrated mass and/or moment of inertia. The conditions for full suppression of the self-excited vibrations are determined analytically and compared with numerical results of an example system. For the first time, example systems are presented for which parametric antiresonance is established at the parametric combination frequency of the sum type.

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Dynamics of the recuperative mechanical stepless vehicle’s drive

E3S Web of Conferences ◽

10.1051/e3sconf/202015701009 ◽

2020 ◽

Vol 157 ◽

pp. 01009

Author(s):

Sergey Hoodorozhkov ◽

Aleksandr Kozlenok

Keyword(s):

Mathematical Model ◽

Energy Storage ◽

Theoretical Study ◽

Nonlinear Differential Equations ◽

Transmission Efficiency ◽

Flywheel Energy Storage ◽

Adjustable Speed Drive ◽

Proposed Model ◽

Variable Transmission ◽

Angular Velocities

The article represents the results of a theoretical study into the operation of a mechanical stepless vehicle drive with the recuperation of braking energy and flywheel energy storage. This paper mainly focused on Adjustable-Speed Drive (ASD) as a part of the infinite ratio continuously variable transmission equipped with flywheel energy storage. To study the proposed transmission, the authors compiled a mathematical model in the form of a system of nonlinear differential equations. The proposed model allows you to determine and monitor the change in the angular velocities and angular accelerations of the rotating links of the transmission. The results of the work will be used to analyze the components of a stepless drive in order to optimize its components to reduce the response time and increase the transmission efficiency, which will lead to a reduction in mechanical losses during the movement of the proposed vehicle.

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AC Electrokinetics of Polarizable Tri-Axial Ellipsoidal Nano-Antennas and Quantum Dot Manipulation

Micromachines ◽

10.3390/mi10020083 ◽

2019 ◽

Vol 10 (2) ◽

pp. 83 ◽

Cited By ~ 1

Author(s):

Touvia Miloh

Keyword(s):

Electric Field ◽

Optical Tweezers ◽

Single Molecule ◽

Light Emission ◽

Weak Field ◽

Ac Electrokinetics ◽

Precise Position ◽

Stagnation Points ◽

Freely Suspended ◽

Induced Velocity

By realizing the advantages of using a tri-axial ellipsoidal nano-antenna (NA) surrounded by a solute for enhancing light emission of near-by dye molecules, we analyze the possibility of controlling and manipulating the location of quantum dots (similar to optical tweezers) placed near NA stagnation points, by means of prevalent AC electric forcing techniques. First, we consider the nonlinear electrokinetic problem of a freely suspended, uncharged, polarized ellipsoidal nanoparticle immersed in a symmetric unbounded electrolyte which is subjected to a uniform AC ambient electric field. Under the assumption of small Peclet and Reynolds numbers, thin Debye layer and ‘weak-field', we solve the corresponding electrostatic and hydrodynamic problems. Explicit expressions for the induced velocity, pressure, and vorticity fields in the solute are then found in terms of the Lamé functions by solving the non-homogeneous Stokes equation forced by the Coulombic density term. The particular axisymmetric quadrupole-type flow for a conducting sphere is also found as a limiting case. It is finally demonstrated that stable or equilibrium (saddle-like) positions of a single molecule can indeed be achieved near stagnation points, depending on the directions of the electric forcing and the induced hydrodynamic (electroosmotic) and dielectrophoretic dynamical effects. The precise position of a fluorophore next to an ellipsoidal NA, can thus be simply controlled by adjusting the frequency of the ambient AC electric field.

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Boundary-induced electrophoresis of uncharged conducting particles: remote wall approximations

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2008.0322 ◽

2008 ◽

Vol 465 (2103) ◽

pp. 709-723 ◽

Cited By ~ 14

Author(s):

Ehud Yariv

Keyword(s):

Asymptotic Approximation ◽

Large Particle ◽

Correction Term ◽

Uniform Electric Field ◽

Leading Order ◽

Electrokinetic Flow ◽

Dielectric Wall ◽

Particle Drift ◽

Polarizable Particle ◽

Freely Suspended

An initially uncharged ideally polarizable particle is freely suspended in an electrolyte solution in the vicinity of an uncharged dielectric wall. A uniform electric field is externally applied parallel to the wall, inflicting particle drift perpendicular to it. Assuming a thin Debye thickness, the electrokinetic flow is analysed for large particle–wall separations using reflection methods, thereby yielding an asymptotic approximation for the particle velocity. The leading-order correction term in that approximations stems from wall polarization.

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