Study Of Field Effects Research Articles

Comparative study of magnetic field effect on fast plasma flow of heavy and light species investigated by spectroscopic measurement

To understand the effects of magnetic fields on the propagating plasma flows of heavy and light ion species, a laboratory-scale experiment was conducted using a pulsed-power discharge. The plasma drift velocity and electron temperature were estimated by time-of-flight and line-pair methods, respectively, using spectroscopic measurements. Ion current waveforms were measured using an ion collector. When a magnetic field was applied, the plasma drift velocity decreased and the electron temperature increased in both heavy and light plasmas. The magnetic Reynolds number, pressure balance between the plasma and magnetic field, and ion current waveforms show that heavy plasma has a high possibility of deforming the magnetic field and generating accelerated ions through interaction with the magnetic field.

Theoretical Study of External Electric Field Effect on the Chemisorption of a Spherical Semiconducting Quantum-dot on Graphene

Theoretical Study of External Electric Field Effect on the Chemisorption of a Spherical Semiconducting Quantum-dot on Graphene

Comparative study of low magnetic field effects in finger-finger and finger-split gate single electron pumps

Single Electron Pump (SEP) devices that can deliver single electrons at high frequencies are fabricated using two different gate geometries. The pump quantum dot (QD) can be defined either using two finger gates where the pump operates in what is known as the conventional pumping regime (CPR), or alternatively, the QD can be designed with the use of a single finger gate and split gate, where the pump operates in the long pumping regime (LPR). Here we investigate pump-maps produced in both the CPR and LPR under the effects of a low magnetic field (1 T to −1 T) and observe both the evolution of the pump-map and pump accuracy. Measurements were carried out in a cryogen free dilution refrigeration system with the use of a superconducting magnetic. Clear discrepancies between the behaviour of current in the different regimes can be seen indicating a fundamental difference in the operation of the pumps in the two different pumping regimes.

Using equivalence tests in higher tier studies of honey bees under the revised EFSA Bee Guidance-How?

The proposed use of equivalence tests instead of difference tests in the revised guidance on the risk assessment of plant protection products for bees is a reasonable approach given an adverse effect was observed in the lower tier studies, using the hypothesis that there is a risk as the null hypothesis places the burden to prove the opposite on the other side. However, some uncertainties regarding the application of equivalence tests in field studies are discussed in the present study. Here, we compare equivalence and difference testing methods using a control dataset of a honey bee field effect study conducted in northern Germany in 2014. Half of the 48 colonies were assigned to a hypothetical test item group, and the colony strength data were analyzed using t-tests, a generalized linear mixed model (GLMM), and the corresponding equivalence tests. The data reflected the natural variability of honey bee colonies, with initially approximately 12 000 adult bees. Although the t-test and GLMM confirmed that 24 + 24 colonies are sufficient to show "no adverse effect," the equivalence tests of the t-test and GLMM were not able to reject the null hypothesis and classified at least some of the assessments as "high risk," indicating a power that was too low. Based on this, different operating options to reduce the variability are discussed. One possible option, which may provide a more realistic application of equivalence to avoid false high risk, is to consider the lower confidence interval of the control as a baseline and use GLMMs. With this option, we demonstrate a relatively acceptable probability to prove that no high risk for initially similar groups can be achieved. Further studies with different numbers of colonies are still needed to develop and validate the suggested approach. Integr Environ Assess Manag 2024;20:1496-1503. © 2024 SETAC.

Numerical Study of Chemical Reaction and Magnetic Field Effects on MHD Boundary Layer Flow over a Flat Plate

This investigation explores the combined effects of magnetic fields and chemical reactions on the movement of a boundary layer toward a flat plate. The study considers the influence of viscous dissipation on the energy distribution. By utilizing partial differential equations (PDEs), the flow phenomenon is modeled. Through the application of suitable similarity transformations, the system of PDEs is transformed into a system of total differential equations. These modified equations are then solved using the spectral homotopy analysis method (SHAM), which incorporates the combination of the CSCM and HAM procedures. The analysis reveals that magnetohydrodynamic (MHD) fluxes generate a Lorentz force, and a higher magnetic parameter intensifies this effect, resulting in a flattened velocity profile. Furthermore, the velocity profile improves with an increase in the chemical interaction variable. The study also shows that as the Eckert number increases, the ambient temperature of the dense dissipative fluid rises. The findings have potential applications in various engineering fields, such as petroleum pipeline flow improvement. The spectral homotopy method used in this study offers a numerical solution for analyzing the problem. The results contribute to the understanding of heat and mass transfer phenomena and can guide future research in this area.

Numerical study of an acoustic field effect on boundary layer transition mechanism

The laminar-to-turbulent transition mechanism is fundamentally important for the concepts aiming at reducing CO2 emissions and noise pollution. This research is focused on understanding the acoustic excitation effect on the transition mechanism with a laminar separation bubble. The transition over the suction side of the NACA 0012 airfoil at an angle of attack of 2 degrees and Reynolds number of 2 × 105 with zero free-stream turbulence intensity is considered. The investigation is performed based on three flow cases obtained for a smooth and wavy surface modified airfoils using the large-eddy simulation method. The acoustic excitation is controlled by keeping or removing a naturally occurring acoustic feedback loop by introducing surface waviness on the airfoil’s pressure side. The flow solution for the standard NACA 0012 airfoil provides the acoustic excitation case, whereas the airfoil with the wavy surface on the pressure side provides the case without acoustic excitation. The results confirm that a shorter separation bubble and earlier laminar-to-turbulent transition can be triggered in response to the acoustic excitation. Furthermore, the coupling of the acoustic field and hydrodynamic instabilities is investigated. Finally, it is shown by referring to experimental data that the Kelvin-Helmholtz instabilities inside the separation bubble are amplified by the acoustic excitation.

Enormous electroresistance and field effect studies on LaMnO3–δ / La0.7Ca0.3MnO3 / LaAlO3 manganite – manganite composite structure

Field effect configuration (FEC) coupled field effect studies (FES) is one of the prime requisites for the development of spintronic based logic and memory devices having better sensitivities for external perturbations specifically while scaling down the technology. In this communication, LaMnO3–δ / La0.7Ca0.3MnO3 / LaAlO3 (LMO / LCMO / LAO) manganite – manganite composite structure was successfully fabricated using cost effective chemical solution deposition (CSD) method. FEC coupled FES have been performed across the electrically polarizable LMO layer and LCMO conducting channel. Enormous room temperature colossal electroresistance (CER) has been acquired ∼ 7000 % under 2 MV/cm forward biased control electric field and ∼ 8.5 × 105 % under 0.9 MV/cm reverse biased control electric field. Elegant modifications in the resistive behavior have been understood on the bases of charge carrier density alterations, interface modifications, phase separation, Mott–type phase transformation and formation–break down of depletion region across the manganite – manganite composite structure.

Thermodynamic Study of the Electric Field Effect on Liquid-Vapor Mixture at Equilibrium: An Analysis on a Water-Ethanol Mixture.

In this paper, the effect of electric fields on phase equilibria through polarization is investigated. A relation is derived for the chemical potential of a system, where the electric field is localized over a liquid phase mixture in equilibrium with a vapor phase mixture. This relation is then applied to a water-ethanol mixture to explore the effect of polarization-based electric fields on the liquid phase composition. It is observed that the quadratic dependence on electric field strength produces little effect below field strengths of approx. 10 MV/m. However, above this field strength, the mole fraction of water in the liquid phase grows rapidly, increasing by a factor of 8 for a water vapor phase fraction of 0.2 and a field strength of 500 MV/m, which approaches the dielectric breakdown strength of water. Nonetheless, this field strength could be achievable with microfluidic experimental setups.

Radiomic and deep learning characterization of breast parenchyma on full field digital mammograms and specimen radiographs: a pilot study of a potential cancer field effect.

In women with biopsy-proven breast cancer, histologically normal areas of the parenchyma have shown molecular similarity to the tumor, supporting a potential cancer field effect. The purpose of this work was to investigate relationships of human-engineered radiomic and deep learning features between regions across the breast in mammographic parenchymal patterns and specimen radiographs. This study included mammograms from 74 patients with at least 1 identified malignant tumor, of whom 32 also possessed intraoperative radiographs of mastectomy specimens. Mammograms were acquired with a Hologic system and specimen radiographs were acquired with a Fujifilm imaging system. All images were retrospectively collected under an Institutional Review Board-approved protocol. Regions of interest (ROI) of were selected from three regions: within the identified tumor, near to the tumor, and far from the tumor. Radiographic texture analysis was used to extract 45 radiomic features and transfer learning was used to extract 20 deep learning features in each region. Kendall's Tau-b and Pearson correlation tests were performed to assess relationships between features in each region. Statistically significant correlations in select subgroups of features with tumor, near to the tumor, and far from the tumor ROI regions were identified in both mammograms and specimen radiographs. Intensity-based features were found to show significant correlations with ROI regions across both modalities. Results support our hypothesis of a potential cancer field effect, accessible radiographically, across tumor and non-tumor regions, thus indicating the potential for computerized analysis of mammographic parenchymal patterns to predict breast cancer risk.

Interplanetary Magnetic Field By Controls the Magnetopause Location

AbstractWe present a statistical study of interplanetary magnetic field (IMF) effects on the magnetopause location based on nearly 15,000 magnetopause crossings identified in the THEMIS A‐E, Magion 4, Geotail, and Interball‐1 satellite data. In order to exclude the dominant controlling role of the solar wind dynamic pressure, differences between observed and empirical model magnetopause distances are analyzed. We find that the magnetopause distance is significantly controlled by the IMF clock angle, not considered in the used empirical models. Furthermore, during very low Alfvén Mach numbers (MA < 4), IMF By component can induce a considerable dawn‐dusk asymmetry of the magnetopause shape. The magnetopause distance is found to be larger in the direction of the IMF vector, that is, not only the magnitude but also the orientation of the IMF By component is eventually important. The obtained results are qualitatively consistent with a magnetohydrodynamic model run at the Community Coordinated Modeling Center.

Manipulation of New Fluorescent Magnetic Nanoparticles with an Electromagnetic Needle, Allowed Determining the Viscosity of the Cytoplasm of M-HeLa Cells.

Magnetic nanoparticles (MNPs) have recently begun to be actively used in biomedicine applications, for example, for targeted drug delivery, in tissue engineering, and in magnetic resonance imaging. The study of the magnetic field effect on MNPs internalized into living cells is of particular importance since it allows a non-invasive influence on cellular activity. There is data stating the possibility to manipulate and control individual MNPs utilizing the local magnetic field gradient created by electromagnetic needles (EN). The present work aimed to demonstrate the methodological and technical approach for manipulating the local magnetic field gradient, generated by EN, novel luminescent MNPs internalized in HeLa cancer cells. The controlling of the magnetic field intensity and estimation of the attractive force of EN was demonstrated. Both designs of EN and their main characteristics are also described. Depending on the distance and applied voltage, the attractive force ENs ranged from 0.056 ± 0.002 to 37.85 ± 3.40 pN. As a practical application of the presented, the evaluation of viscous properties of the HeLa cell's cytoplasm, based on the measurement of the movement rate of MNPs inside cells under impact of a known magnetic force, was carried out; the viscosity was 1.45 ± 0.04 Pa·s.

Direct Z-scheme GaSe/ZrS2 heterojunction for overall water splitting

In this paper, a novel GaSe/ZrS2 heterojunction is designed and systematically studied. The monolayers in this heterojunction can be easily fabricated and the heterojunction has good stability. More importantly, electronic structures, band alignment, differential charge density and the built-in electric field show that it is a direct Z-scheme photocatalyst that can not only effectively separate photogenerated carriers but also improve the redox ability of carriers. The mobility of the electrons in this heterostructure is as large as 1450.38 cm2V−1s−1 (same magnitude order of black phosphorene) along the zigzag direction, which is beneficial to photocatalytic performance. The band alignment shows that GaSe/ZrS2 is suitable for overall water splitting and the splitting can happen spontaneously. Moreover, GaSe/ZrS2 heterojunction has excellent absorption coefficients (higher than 105cm−1) in both visible and ultraviolet ranges which is very beneficial to photocatalytic overall water splitting. The study of electric field and biaxial strain effects on GaSe/ZrS2 heterojunction show that the light absorption coefficients of GaSe/ZrS2 heterojunction can be obviously further improved by applying biaxial strain. Our work shows that GaSe/ZrS2 heterojunction is a promising photocatalysts for overall water splitting.

Electric-field effects on methane coflow flames aboard the international space station (ISS): ACME E-FIELD flames

This work describes the preparatory and initial measurements of diffusion flames under the influence of an electric field aboard the International Space Station (ISS), as part of the Advanced Combustion via Microgravity Experiments (ACME) project. Intended as the foundation publication for the experimental effort, the work comprehensively includes the space experiment methods, the capabilities of the ACME insert, experiment procedures, data, and limitations and constraints. The measurements presented include images and ion currents of small diffusion flames of methane (in air), subjected to a ramping electric field in microgravity. While there have been prior microgravity studies of Electric Field Effects on Laminar Diffusion Flames (E-FIELD Flames) using a drop tower, the current measurements represent the first mapping of the effects of an ion-driven wind on flame behavior under an electric field in the absence of the confounding influences of buoyancy. The paper describes the challenges of remote measurement and manipulation of flames on the ISS and presents preliminary results from the first set of coflow flames. The on-orbit tests began in March 2018 using the modular ACME hardware within the ISS’ Combustion Integrated Rack (CIR) and were completed in the same year November. The results show that the flame is most compact at saturation while the measured voltage-current characteristic (VCC) curve demonstrates parabolic behavior after saturation which differs from observations in 1 g on Earth.

Theoretical calculations on Landé g-factors and quadratic Zeeman shift coefficients of nsnp clock states in Mg and Cd optical lattice clocks

The study of magnetic field effects on the clock transition of Mg and Cd optical lattice clocks is scarce. In this work, the hyperfine-induced Landé g-factors and quadratic Zeeman shift coefficients of the nsnp clock states for 111,113Cd and 25Mg were calculated by using the multi-configuration Dirac–Hartree–Fock theory. To obtain accurate values of these parameters, the impact of electron correlations and furthermore the Breit interaction and quantum electrodynamical effects on the Zeeman and hyperfine interaction matrix elements, and energy separations were investigated in detail. We also estimated the contributions from perturbing states to the Landé g-factors and quadratic Zeeman shift coefficients concerned so as to truncate the summation over the perturbing states without loss of accuracy. Our calculations provide important data for estimating the first- and second-order Zeeman shifts of the clock transition for the Cd and Mg optical lattice clocks.

Field effects in electron-irradiated GaP LEDs

The paper presents the results of the study of field effects in non-irradiated and irradiated by electrons (E = 2 MeV, F = 8.2∙1016 cm–2) gallium phosphide (GaP) light emitting diodes (LEDs) under reverse bias. The avalanche multiplication of charge carriers and tunneling breakdown in the space charge region has been considered. An increase of breakdown voltage after electron irradiation has been revealed. The effects of the annealing of non-irradiated and irradiated diodes in the temperature range of 20 to 500 °C have been analyzed.

Nanoscale studies of electric field effects on monolayer 1T\u2032-WTe2

Monolayer 1 T′-WTe2 is a quantum spin Hall insulator with a gapped 2D-bulk and gapless helical edge states persisting to temperatures ~100 K. Despite the far-ranging interest, the magnitude of the bulk gap, the effect of gating on the 2D-band structure, as well the role interactions are not established. In this work we use STM spectroscopy to measure the intrinsic bulk gap of monolayer 1 T′-WTe2 and show that gate induced electric fields cause large changes of the gap magnitude. Our first-principles DFT-derived tight-binding model reveal that a combination of spatial localization of the conduction and valance bands and Rashba-like spin-orbit coupling leads to a gating induced spin-splitting of the 2D-bulk bands in the tens of meV, thereby reducing the band gap. Our work explains the large sensitivity of the band structure to electric fields and suggests a new avenue for realizing proximity induced non-trivial superconductivity in monolayer 1 T′-WTe2.

First principles study of field effect device through van der Waals and lateral heterostructures of graphene, phosphorene and graphane

Chemical modification and vertical stacking of two-dimensional materials are promising techniques for new nanoelectronic devices. We present Density Functional Tight Binding (DFTB) calculations of a field-effect device, based on lateral and vertical heterostructures of 2D materials. The device consists of a phosphorene channel protected by graphene sheets, which work as contacts and are divided into the source and drain by local hydrogenation of graphene, which gives insulating graphane. In this device composed of only 3 layers, single sheets of graphene-graphane can work as both leads and oxide gate, while also acting as protective layers for a phosphorene channel. We show how for perfect vdW heterostructures of graphane/phosphorene/graphane and graphene/phosphorene/graphene the Schottky barrier is deeply influenced by normal electric fields, and we characterize electronic transport of such a device. Finally, we characterize phosphorene channel doping and defects, which, at very high densities in the transport direction, enables transport inside the phosphorene bandgap.

The study of heat flux and external electric field effects on carbon nanotube behavior as an atomic nano-pump

The study of heat flux and external electric field effects on carbon nanotube behavior as an atomic nano-pump

Numerical Study of Temperature and Electric Field Effects on the Total Optical Absorption Coefficient in the Presence of Optical Inter-Conduction-Subband Transitions in InGaN/GaN Single Parabolic Quantum Wells

In this paper, we theoretically investigate the total optical coefficient (TOAC) considering 1S-2P and 2S-2P conduction subband transitions in a single parabolic quantum well (SPQW) with an on-center hydrogen-like impurity. Within the framework of the effective-mass approximation, the Schrödinger equation is solved numerically to obtain the eigenvalues and their corresponding eigenvectors using the finite difference method. The calculations are performed for finite confinement potential height, taking into account the dielectric and effective mass mismatches between GaN and InGaN materials under the considered electric field and temperature effects. The temperature dependence of the effective mass, dielectric constant and band gap energy are obtained accordingly. On the one hand, the results show that a significant shift is produced with the variation of both the temperature and the intensity of the electric field. On the other hand, the absorption spectrum is shifted to lower energies with increasing both electric field strength and temperature. Moreover, its amplitude is enhanced with an increase in the intensity of the electric field, and show a slight drop with increasing temperature for the two optical transitions considered. The results show that such parameters can be used to adjust the optical properties of single parabolic Quantum Well for solar cell applications.

Thermal transport properties of Heisenberg antiferromagnet on honeycomb lattice: The effects of anisotropy

We study the thermal conductivity of a spin-1/2 two-dimensional anisotropic antiferromagnet on honeycomb lattice in the presence of antiferromagnetic long range ordering. The conductivity has been studied along zigzag direction. Next nearest neighbor exchange coupling has been added to the model Hamiltonian. The possible effects of spin–orbit coupling are investigated by adding Dzyaloshinskii–Moriya interaction to the model Hamiltonian. Such interaction creates anisotropic effects in the model Hamiltonian. The original antiferromagnetic model hamiltonian is mapped to a bosonic model via linear spin wave theory in the context of Holstein Primakoff transformations. The Green’s function approach is applied to obtain the energy spectrum of quasi-particle excitations responsible for thermal transport. We have found the temperature dependence of static thermal conductivity in the magnetic long range ordering phase for various next nearest neighbor coupling constant and anisotropy parameter. Furthermore we have studied the temperature dependence of the static thermal conductivity for various Dzyaloshinskii-Moriya interaction strength and next nearest neighbor coupling constants. Our results show that each curve for temperature dependence of thermal conductivity includes a peak so that the height of peak reduces with magnetic field however the temperature positions of peaks is independent of magnetic field value. Moreover the increase of anisotropic parameter leads to enhance thermal conductivity values. Also the next nearest neighbor coupling constant improves thermal conductivity of localized electrons on honeycomb structure . The exponential behavior for temperature dependence of thermal conductivity at low temperatures is the novel feature in thermal conductivity results. • Study of thermal conductivity of honeycomb lattics. • Study of anisotropic parameter on conductivity. • Study of magnetic field effects on conductivity.