scholarly journals Numerical Simulation of Electric Field Distribution around an Instrumented Total Hip Stem

2021 ◽  
Vol 11 (15) ◽  
pp. 6677
Author(s):  
Ulf Zimmermann ◽  
Cathérine Ebner ◽  
Yukun Su ◽  
Thomas Bender ◽  
Yogesh Deepak Bansod ◽  
...  
Keyword(s):  
Electric Field ◽  
Bone Tissue ◽  
Electric Fields ◽  
Total Joint Replacement ◽  
Standard Procedure ◽  
Experimental Investigations ◽  
Clinical Issue ◽  
Total Hip ◽  
Electric Potentials ◽  
Hip Stems

Presently, total joint replacement (TJR) is a standard procedure in orthopedic surgery. Adequate osseointegration of the implant components still remains a clinical issue. However, active stimulation of bone tissue to enhance bone ongrowth at the implant surfaces has not been widely investigated so far. For the last several years, invasive electromagnetically induced osseotherapy has been employed in clinical practice, e.g., for the treatment of avascular necrosis, femoral neck fractures, and pseudarthrosis. In the present study, the approach of exploiting the electric stimulation effect was transferred to the field of TJR. Therefore, a commercially available total hip stem was instrumented with an electrode on its surface in order to generate an electric field supporting the regeneration of the surrounding bone tissue. The objective was to conduct numerical simulations validated by experimental investigations as a proof of concept for an instrumented electro-stimulative total hip stem. The results revealed that the calculated electric field around a total hip stem fulfills the requirements to stimulate adjacent bone tissue when using clinically applied electric voltages. The derived numerical and experimental data of electric potentials and corresponding electric fields are encouraging for the implementation of active electrical stimulation in uncemented total hip stems to enhance their osseointegration.

scholarly journals Penetration of the electric fields of the geomagnetic sudden commencement over the globe as observed with the HF Doppler sounders and magnetometers

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Takashi Kikuchi ◽  
Jaroslav Chum ◽  
Ichiro Tomizawa ◽  
Kumiko K. Hashimoto ◽  
Keisuke Hosokawa ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Sudden Commencement ◽  
Ionospheric Currents ◽  
Republic Of China ◽  
F Region ◽  
Electric And Magnetic Fields ◽  
Magnetometer Data ◽  
Electric Potentials ◽  
Geomagnetic Sudden Commencement

AbstractUsing the HF Doppler sounders at middle and low latitudes (Prague, Czech Republic; Tucuman, Argentina; Zhongli, Republic of China, and Sugadaira, Japan), we observed the electric fields of the geomagnetic sudden commencement (SC) propagating near-instantaneously (within 10 s) over the globe. We found that the electric fields of the preliminary impulse (PI) and main impulse (MI) of the SC are in opposite direction to each other and that the PI and MI electric fields are directed from the dusk to dawn and dawn to dusk, respectively, manifesting the nature of the curl-free potential electric field. We further found that the onset and peak of the PI electric field are simultaneous on the day and nightsides (0545, 1250, 1345 MLT) within the resolution of 10 s. With the magnetometer data, we confirmed the near-instantaneous development of the ionospheric currents from high latitudes to the equator and estimated the location of the field-aligned currents that supply the ionospheric currents. The global simultaneity of the electric and magnetic fields does not require the contribution of the magnetohydrodynamic waves in the magnetosphere nor in the F-region ionosphere. The global simultaneity and day–night asymmetry of the electric fields are explained with the ionospheric electric potentials transmitted at the speed of light by the TM0 mode waves in the Earth-ionosphere waveguide.

scholarly journals Experimental Investigations on Electric-Field-Induced Crystallization in Erythritol

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5110
Author(s):  
Jean-Luc Dauvergne ◽  
Artem Nikulin ◽  
Stefania Doppiu ◽  
Elena Palomo del Barrio
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Phase Change Materials ◽  
Second Step ◽  
Experimental Investigations ◽  
Experimental Configuration ◽  
Literature Reviews ◽  
Attractive Option ◽  
Thermal Energy Storage Systems ◽  
Induced Crystallization

The objective of this experimental study was to develop a method to induce crystallization of sugar alcohols using an electric field for its future implementation in latent heat thermal energy storage systems. To better understand the mechanisms behind this approach, the first step of this work was dedicated to the replication, continuation, and consolidation of promising results on erythritol reported by another research group. In the second step, a second experimental configuration, previously used to electrically control the supercooling of other phase change materials, was tested with the same sugar alcohol. For both configurations, the influence of the type of current (DC and AC at different frequencies), its amplitude, and time of exposure were studied. However, none of these tests allowed influencing the crystallization of erythritol. Even if surprising at first glance, the difficulty in reproducing experiments and interpreting the results is not new in the field of electric-field-induced crystallization, as shown in particular by the abundant literature reviews concerning water. Currently, to the best of our knowledge, we consider that electric fields could be an attractive option to initiate and accelerate the crystallization of erythritol, but this solution must be considered with caution.

Tuning the Electric Field Response of MOFs by Rotatable Dipolar Linkers

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.

scholarly journals Meta-Deflectors Made of Dielectric Nanohole Arrays with Anti-Damage Potential

Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 107
Author(s):  
Haichao Yu ◽  
Feng Tang ◽  
Jingjun Wu ◽  
Zao Yi ◽  
Xin Ye ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Laser Cutting ◽  
High Complexity ◽  
Damage Potential ◽  
Optical Components ◽  
Nanohole Arrays ◽  
Intense Light ◽  
Polarization Of Light ◽  
Air Hole

In intense-light systems, the traditional discrete optical components lead to high complexity and high cost. Metasurfaces, which have received increasing attention due to the ability to locally manipulate the amplitude, phase, and polarization of light, are promising for addressing this issue. In the study, a metasurface-based reflective deflector is investigated which is composed of silicon nanohole arrays that confine the strongest electric field in the air zone. Subsequently, the in-air electric field does not interact with the silicon material directly, attenuating the optothermal effect that causes laser damage. The highest reflectance of nanoholes can be above 99% while the strongest electric fields are tuned into the air zone. One presentative deflector is designed based on these nanoholes with in-air-hole field confinement and anti-damage potential. The 1st order of the meta-deflector has the highest reflectance of 55.74%, and the reflectance sum of all the orders of the meta-deflector is 92.38%. The optothermal simulations show that the meta-deflector can theoretically handle a maximum laser density of 0.24 W/µm2. The study provides an approach to improving the anti-damage property of the reflective phase-control metasurfaces for intense-light systems, which can be exploited in many applications, such as laser scalpels, laser cutting devices, etc.

scholarly journals Integrating flexible electronics for pulsed electric field delivery in a vascularized 3D glioblastoma model

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Marie C. Lefevre ◽  
Gerwin Dijk ◽  
Attila Kaszas ◽  
Martin Baca ◽  
David Moreau ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Flexible Electronics ◽  
Soft Tissues ◽  
Multiphoton Microscopy ◽  
Membrane Integrity ◽  
Tumor Model ◽  
Pulsed Electric Fields ◽  
In Ovo ◽  
Cell Membrane Integrity

AbstractGlioblastoma is a highly aggressive brain tumor, very invasive and thus difficult to eradicate with standard oncology therapies. Bioelectric treatments based on pulsed electric fields have proven to be a successful method to treat cancerous tissues. However, they rely on stiff electrodes, which cause acute and chronic injuries, especially in soft tissues like the brain. Here we demonstrate the feasibility of delivering pulsed electric fields with flexible electronics using an in ovo vascularized tumor model. We show with fluorescence widefield and multiphoton microscopy that pulsed electric fields induce vasoconstriction of blood vessels and evoke calcium signals in vascularized glioblastoma spheroids stably expressing a genetically encoded fluorescence reporter. Simulations of the electric field delivery are compared with the measured influence of electric field effects on cell membrane integrity in exposed tumor cells. Our results confirm the feasibility of flexible electronics as a means of delivering intense pulsed electric fields to tumors in an intravital 3D vascularized model of human glioblastoma.

scholarly journals Electro-Optic Control of Lithium Niobate Bulk Whispering Gallery Resonators: Analysis of the Distribution of Externally Applied Electric Fields

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 298
Author(s):  
Yannick Minet ◽  
Hans Zappe ◽  
Ingo Breunig ◽  
Karsten Buse
Keyword(s):  
Lithium Niobate ◽  
Electric Field ◽  
Electric Fields ◽  
Frequency Comb ◽  
Parametric Oscillation ◽  
Pockels Effect ◽  
Optical Mode ◽  
Cylindrical Resonator ◽  
Whispering Gallery ◽  
Electro Optic

Whispering gallery resonators made out of lithium niobate allow for optical parametric oscillation and frequency comb generation employing the outstanding second-order nonlinear-optical properties of this material. An important knob to tune and control these processes is, e.g., the linear electro-optic effect, the Pockels effect via externally applied electric fields. Due to the shape of the resonators a precise prediction of the electric field strength that affects the optical mode is non-trivial. Here, we study the average strength of the electric field in z-direction in the region of the optical mode for different configurations and geometries of lithium niobate whispering gallery resonators with the help of the finite element method. We find that in some configurations almost 100% is present in the cavity compared to the ideal case of a cylindrical resonator. Even in the case of a few-mode resonator with a very thin rim we find a strength of 90%. Our results give useful design considerations for future arrangements that may benefit from the strong electro-optic effect in bulk whispering gallery resonators made out of lithium niobate.

scholarly journals Implications of component size and calibration error on digital templating for total hip arthroplasty. A visual matrix from a simple mathematical model

2021 ◽  
Author(s):  
Christoph Kolja Boese ◽  
Tim Rolvien ◽  
Matthias Trost ◽  
Michael Frink ◽  
Jan Hubert ◽  
...  
Keyword(s):  
Total Hip Arthroplasty ◽  
Hip Arthroplasty ◽  
Standard Procedure ◽  
Calibration Error ◽  
Optimal Size ◽  
Linear Calibration ◽  
Component Size ◽  
Digital Templating ◽  
Total Hip ◽  
Implant Size

Abstract Objective Preoperative digital templating is a standard procedure in total hip arthroplasty. Deviations between template size and final implant size may result from inaccurate calibration, templating as well as intraoperative decisions. So far, the explicit effect of calibration errors on templating has not been addressed adequately. Materials and Methods A mathematical simulation of calibration errors up to ± 24% was applied to the templating of acetabular cups (38 to 72 mm diameter). The effect of calibration errors on template component size as deviation from optimal size was calculated. Results The relationship between calibration error and component size deviation is inverse and linear. Calibration errors have a more pronounced effect on larger component sizes. Calibration errors of 2–6% result in templating errors of up to two component sizes. Common errors of up to 12% may result in templating errors of 3–4 sizes for common implant sizes. A tabular matrix visualizes the effect. Conclusion Calibration errors play a significant role in component size selection during digital templating. Orthopedic surgeons should be aware of this effect and try to identify and address this source of error.

scholarly journals Double layers in the downward current region of the aurora

2003 ◽  
Vol 10 (1/2) ◽  
pp. 45-52 ◽  
Author(s):  
R. E. Ergun ◽  
L. Andersson ◽  
C. W. Carlson ◽  
D. L. Newman ◽  
M. V. Goldman
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Phase Space ◽  
Electric Field ◽  
Electric Fields ◽  
Double Layers ◽  
Parallel Electric Field ◽  
Electrostatic Waves ◽  
Current Region ◽  
Decisive Evidence

Abstract. Direct observations of magnetic-field-aligned (parallel) electric fields in the downward current region of the aurora provide decisive evidence of naturally occurring double layers. We report measurements of parallel electric fields, electron fluxes and ion fluxes related to double layers that are responsible for particle acceleration. The observations suggest that parallel electric fields organize into a structure of three distinct, narrowly-confined regions along the magnetic field (B). In the "ramp" region, the measured parallel electric field forms a nearly-monotonic potential ramp that is localized to ~ 10 Debye lengths along B. The ramp is moving parallel to B at the ion acoustic speed (vs) and in the same direction as the accelerated electrons. On the high-potential side of the ramp, in the "beam" region, an unstable electron beam is seen for roughly another 10 Debye lengths along B. The electron beam is rapidly stabilized by intense electrostatic waves and nonlinear structures interpreted as electron phase-space holes. The "wave" region is physically separated from the ramp by the beam region. Numerical simulations reproduce a similar ramp structure, beam region, electrostatic turbulence region and plasma characteristics as seen in the observations. These results suggest that large double layers can account for the parallel electric field in the downward current region and that intense electrostatic turbulence rapidly stabilizes the accelerated electron distributions. These results also demonstrate that parallel electric fields are directly associated with the generation of large-amplitude electron phase-space holes and plasma waves.

scholarly journals Clarifications on the Behavior of Alternative Gases to SF6 in Divergent Electric Field Distributions under AC Voltage

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1065
Author(s):  
Houssem Eddine Nechmi ◽  
Michail Michelarakis ◽  
Abderrahmane (Manu) Haddad ◽  
Gordon Wilson
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Partial Discharge ◽  
Mean Value ◽  
Electrode System ◽  
Polarity Reversal ◽  
Buffer Gas ◽  
Co2 Gas ◽  
Breakdown Mechanism ◽  
Positive Cycle

Negative and positive partial discharge inception voltages and breakdown measurements are reported in a needle-plane electrode system as a function of pressure under AC voltage for natural gases (N2, CO2, and O2/CO2), pure NovecTM gases (C4F7N and C5F10O) and NovecTM in different natural gas admixtures. For compressed 4% C4F7N–96% CO2 and 6% C5F10O–12% O2–82% CO2 gas mixtures, the positive-streamer mode is identified as the breakdown mechanism. Breakdown and negative partial discharge inception voltages of 6% C5F10O–12% O2–82% CO2 are higher than those of 4% C4F7N–96% CO2. At 8.8 bar abs, the breakdown voltage of 6% C5F10O–12% O2–82% CO2 is equal to that of 12.77% O2–87.23% CO2 (buffer gas). Synergism in negative partial discharge inception voltage/electric field fits with the mean value and the sum of each partial pressure individually component for a 20% C4F7N–80% CO2 and 6% C5F10O–12% O2–82% CO2, respectively. In 9% C4F7N–91% CO2, the comparison of partial discharge inception electric fields is Emax (CO2) = Emax(C4F7N), and Emax (12.77% O2–87.23% CO2) = Emax(C5F10O) in 19% C5F10O–81%(12.77% O2–87.23% CO2). Polarity reversal occurs under AC voltage when the breakdown polarity changes from negative to positive cycle. Polarity reversal electric field EPR was quantified. Fitting results show that EPR (CO2) = EPR(9% C4F7N–91% CO2) and EPR(SF6) = EPR (22% C4F7N–78% CO2). EPR (4% C4F7N–96% CO2) = EPR (12.77% O2–87.23% CO2) and EPR (6% C5F10O–12% O2–82% CO2) < EPR (4% C4F7N–96% CO2) < EPR (CO2).

scholarly journals Tuning Single-Molecule Conductance by Controlled Electric Field-Induced trans-to-cis Isomerisation

2021 ◽  
Vol 11 (8) ◽  
pp. 3317
Author(s):  
C.S. Quintans ◽  
Denis Andrienko ◽  
Katrin F. Domke ◽  
Daniel Aravena ◽  
Sangho Koo ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Single Molecule ◽  
Quantum Interference ◽  
Single Molecule Level ◽  
Wet Chemical Synthesis ◽  
Single Molecule Junctions ◽  
Tunnelling Microscopy ◽  
The Difference

External electric fields (EEFs) have proven to be very efficient in catalysing chemical reactions, even those inaccessible via wet-chemical synthesis. At the single-molecule level, oriented EEFs have been successfully used to promote in situ single-molecule reactions in the absence of chemical catalysts. Here, we elucidate the effect of an EEFs on the structure and conductance of a molecular junction. Employing scanning tunnelling microscopy break junction (STM-BJ) experiments, we form and electrically characterize single-molecule junctions of two tetramethyl carotene isomers. Two discrete conductance signatures show up more prominently at low and high applied voltages which are univocally ascribed to the trans and cis isomers of the carotenoid, respectively. The difference in conductance between both cis-/trans- isomers is in concordance with previous predictions considering π-quantum interference due to the presence of a single gauche defect in the trans isomer. Electronic structure calculations suggest that the electric field polarizes the molecule and mixes the excited states. The mixed states have a (spectroscopically) allowed transition and, therefore, can both promote the cis-isomerization of the molecule and participate in electron transport. Our work opens new routes for the in situ control of isomerisation reactions in single-molecule contacts.

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