External Electromagnetic Field Research Articles

THE RESONANT RESPONSE OF STRONGLY COUPLED NANORODS TO THE ELECTROMAGNETIC WAVE

The electromagnetic response of closely spaced nanorod dimers can be controlled via the modification of the nanoparticles interaction, caused by electron tunneling between them. The optical response to an intense external electromagnetic field of a system composed of two gold 230 nm long rods surrounded by air and separated by a gap of width 0.5 nm was analyzed. Using finite element method-based numerical simulations we show that the electron tunneling, taking place due to the extraordinary enhancement of the electromagnetic field inside the nanogap, results in the change of the nanoantenna coupling from the capacitive to the conductive one. As a result, the absorption-to-scattering ratio of the dimer significantly changes. Particularly, the scattering cross-section decreases by about three times, whereas the normalized absorption rises from about 12 to 18 with noticeably broadening of the spectral line.

Quantum Simulation of Molecular Response Properties in the NISQ Era.

Accurate modeling of the response of molecular systems to an external electromagnetic field is challenging on classical computers, especially in the regime of strong electronic correlation. In this article, we develop a quantum linear response (qLR) theory to calculate molecular response properties on near-term quantum computers. Inspired by the recently developed variants of the quantum counterpart of equation of motion (qEOM) theory, the qLR formalism employs "killer condition" satisfying excitation operator manifolds that offer a number of theoretical advantages along with reduced quantum resource requirements. We also used the qEOM framework in this work to calculate the state-specific response properties. Further, through noiseless quantum simulations, we show that response properties calculated using the qLR approach are more accurate than the ones obtained from the classical coupled-cluster-based linear response models due to the improved quality of the ground-state wave function obtained using the ADAPT-VQE algorithm.

Well-matched PANI@FePO4@FeSi hybrid composite with excellent microwave absorption property

PANI@FePO4@FeSi composites were prepared by one-pot synthesis. The PANI@FePO4 coating layer can effectively enhance magnetic loss, dielectric losses, and improve impedance matching by reduce the skin effect. The optimized reflection loss (RL) of the composites is −54 dB at 15.76 GHz with the absorption bandwidth (RL<−10 dB) of 2.7 GHz (14.3−17 GHz).Density functional theory (DFT) and ANSYS High-Frequency Structure Simulator (HFSS) analysis results suggest that destruction of local microstructural symmetry and inducing additional electric dipoles at the interface of each component. The density of state (DOS) of p orbital near the Fermi level decreases. Thus, dipole oscillation and polarization loss get enhanced under the external electromagnetic field. This work provides an avenue for designing new microwave absorbers.

Periodontitis: causes, conditions of occurrence and prevention

OBJECTIVE. Analyze the causes and conditions for chronic generalized periodontitis, study means of preventive health care through individual oral hygiene.&#x0D; MATERIALS AND METHODS. The study analyzed the scientific literature, devoted to casual factors and conditions of developing chronic generalized periodontitis, its influence on the health of the body and as well as the role of oral hygiene in preventing its onset and progression. Articles in leading domestic dental peer-reviewed publications along with data sources from Pubmed over the past 5 years were analyzed.&#x0D; RESULTS. The literature analysis found that majority of authors acknowledge microbial biofilm microbiota of the oral cavity as the leading etiological factor of periodontitis; such factors as poor oral hygiene, endogenous and exogenous erythrocyte sorption overload, the impact of physical environmental factors – external electromagnetic fields and vibrations affect the progression of the disease. Meanwhile, measures of professional oral hygiene и normalization of individual oral hygiene allows to significantly reduce the risk of emerging and progressing chronic generalized periodontitis.&#x0D; DISCUSSION. By category visits patients, suffering from CGP, were distributed as follows: 61,6 ± 0,7 % people – retirees of Russian Defense Ministry, 16,5 ± 0,5 % people – family members of military men and retired of RDM, 16,3 ± 0,5 % – military men, attached to the dentistry clinic of RDM military units and institutions, 5,7 ± 0,3 % – RMD cadets. Means of individual oral hygiene, relevant for the prevention of periodontitis, include about 15 items. Part of them are classified as traditional, and the proper application of some of them requires additional training, including in the framework of special medical training during hygiene education work and health promotion. The authors came to a conclusion about the expediency of increasing the number of dentists to intensify the prevention of dental caries and periodontal diseases among military men through professionally monitored oral hygiene.&#x0D; CONCLUSION. The high prevalence and intensity of dental system diseases among military men shows the relevance of regular sanitation of their oral cavity. Systematic implementation of individual oral hygiene measures decreases the number of bacteria in the mouth, prevents the development of severe overall body response to inflammation, contributes to a significant reduction in the number of exacerbation of concomitant somatic diseases that improves overall health and people’s quality of life. Professionally monitored oral hygiene, oral hygiene education and motivation for applying modern hygiene products are considered as the basis of oral disease prevention.

Dynamic fermion flavor mixing through transition dipole moments

In this paper, we show that Majorana neutrino flavor mixing can be driven by transition dipole moments in the presence of external electromagnetic fields. We demonstrate the sensitivity of the rotation mixing matrix to strong fields obtaining dynamical mass eigenstates in the two-flavor model. The three-flavor case, and extensions to the quark sector, is introduced.

Geometric post-Newtonian description of massive spin-half particles in curved spacetime

We consider the Dirac equation coupled to an external electromagnetic field in curved four-dimensional spacetime with a given timelike worldline γ representing a classical clock. We use generalised Fermi normal coordinates in a tubular neighbourhood of γ and expand the Dirac equation up to, and including, the second order in the dimensionless parameter given by the ratio of the geodesic distance to the radii defined by spacetime curvature, linear acceleration of γ, and angular velocity of rotation of the employed spatial reference frame along γ. With respect to the time measured by the clock γ, we compute the Dirac Hamiltonian to that order. On top of this ‘weak-gravity’ expansion we then perform a post-Newtonian expansion up to, and including, the second order of , corresponding to a ‘slow-velocity’ expansion with respect to γ. As a result of these combined expansions we give the weak-gravity post-Newtonian expression for the Pauli Hamiltonian of a spin-half particle in an external electromagnetic field. This extends and partially corrects recent results from the literature, which we discuss and compare in some detail.

Optical analogs of pair production and annihilation in binary waveguide arrays with a linearly shifted straight section

We systematically investigate the optical analogs of the e−e+ pair production and annihilation phenomena which can take place simultaneously in a binary waveguide array having a linearly shifted straight section sandwiched between two straight sections. These two processes can be realized by the beam splitting in the linearly shifted straight section which performs the function of an external vector potential with a rectangular form in time in quantum electrodynamics (QED) which is different from two widely used concepts based on an external time-varying electromagnetic field, or an external ultrastrong time-independent potential barrier in space as in the Schwinger mechanism. We show that the numerical results for annihilation and pair production probabilities based on the simulations of beam propagation in binary waveguide arrays in the low-power regime are in very good agreement with the theoretical results. We also reveal that with certain requirements, the proposed discrete model quantitatively mimics the two processes as well as the continuous model of the genuine Dirac equation in free space in QED. We also show that the nonlinearity in the high-power regime can reduce these two effects.

Cavity-mediated thermal control of metal-to-insulator transition in 1T-TaS2.

Placing quantum materials into optical cavities provides a unique platform for controlling quantum cooperative properties of matter, by both weak and strong light-matter coupling1,2. Here we report experimental evidence of reversible cavity control of a metal-to-insulator phase transition in a correlated solid-state material. We embed the charge density wave material 1T-TaS2 into cryogenic tunable terahertz cavities3 and show that a switch between conductive and insulating behaviours, associated with a large change in the sample temperature, is obtained by mechanically tuning the distance between the cavity mirrors and their alignment. The large thermal modification observed is indicative of a Purcell-like scenario in which the spectral profile of the cavity modifies the energy exchange between the material and the external electromagnetic field. Our findings provide opportunities for controlling the thermodynamics and macroscopic transport properties of quantum materials by engineering their electromagnetic environment.

Phase synchronization under mixed synapse between two heterogeneous functional neurons

Nervous system contacts and regulates the various systems and organs of the body by encoding and transmitting information, so it becomes important to explore the synaptic connections between neurons. In this study, two functional neurons are obtained by embedding Josephson junction and memristor in the FHN neuron circuit, and then based on Helmholtz’s theorem their Hamilton energies are calculated and investigated when coupled channel is awakened. There are weak but stable and orderly electromagnetic fields around human tissues and organs due to the transmembrane flow of ions, and their equilibrium state is easily disturbed and destroyed by the external electromagnetic fields, which should be considered when neuron model are investigated. Thus, an induction coil and a charge-controlled memristor (CCM) are used to perceive magnetic and electric fields respectively to couple the two function neurons, then mixed synapse is activated and synaptic plasticity is detect by parameter modulation and energy exchange. It is found that energy is continuously pumped along the coupling channel even if the synaptic connection is increased further, and two different functional neurons can only achieve quasi-phase synchronization or phase lock. However, the coupling strength threshold for achieving quasi-phase synchronization is lowered under hybrid synapses, and the possible mechanism may be that the addition of induction coil and CCM can induce time-varying electric and magnetic fields, which in turn facilitate the energy exchange in the coupled system. This study not only helps us to reveal the synchronization phenomenon of certain neurons observed in experiments, but also to explain the occurrence of pathological synchronization in the nervous system.

Concatenation of Two Different Integrable Systems is Not Integrable

Aims/Objectives: Nonlinear, completely integrable Hamiltonian systems representing charged particle motion in external electromagnetic fields hold promise for models of novel intensity frontier particle accelerators. The main reason is the combination of large regions of stable orbits with damping of collective instabilities by conservative relaxation. Intensity frontier particle accelerators are essential for discovery science in particle and nuclear physics, and a host of industrial and security applications.Study Design: Mathematical proof.Methodology: Tools of Hamiltonian dynamics and differential geometry.Results: Realistic system lattices include additional sections or inserts that themselves may be integrable (such as linear optics, phase trombones, thin lenses, kicks, etc.). However, in general the full system fails to remain integrable.Conclusion: The non-integrability proof is presented and some consequences of integrability failure are explored.

Innovative technologies for strengthening of internal surfaces of suspension parts of heavy-loaded machines by laser and high-frequency induction methods

In the article innovative methods of surface hardening of internal surfaces of machine parts by laser and highfrequency induction heating are presented. The relevance of applying the methods of laser and induction hardening for the internal surfaces of heavily loaded parts of quarry equipment is proved. The results of modeling and calculation of thermal and electromagnetic fields under the influence of an external electromagnetic field and laser radiation beams are presented. The original design of a complex of equipment for processing the internal surfaces of suspension parts by external electromagnetic field is described. The optimal designs of inductors with magnetic circuits made of various materials are shown. The study of the structure and properties obtained on the internal surfaces of heavily loaded suspension parts of cars, line of the BelAZ company, treated according to the optimal modes of surface induction exposure is given. The developed original technology and equipment of laser surface hardening, which makes it possible to increase the wear resistance of heavily loaded parts, is described. Data on the implementation of research results at JSC “BELAZ” – the Management Company of the Holding “BELAZ-HOLDING” for processing a wide range of heavily loaded suspension parts are given.

Investigation of the influence of external factors on the operation of a fiber-optic dielectric temperature sensor

The article presents the design and test results of a fiber-optic dielectric temperature sensor intended for use under the influence of external electromagnetic field and aggressive environment.

Collecting the energy of the electromagnetic fields over the infrared band based on the metastructures

Predicated on the surface plasmon polariton, this study proposes the metastructures (MSs) constructed from copper and general dielectric films. The MSs are specifically designed to gather electromagnetic (EM) wave energy over the infrared band on the surface. Evidence illustrates that, when EM waves impinge the surface of the MSs, there is a significant surge in surface energy density, confirmed to be a staggering 2022.90 times higher than that of the ancillary EM waves. This substantial multiplication owes its genesis to the enhanced impedance matching between the MSs and free space. Furthermore, the MSs demonstrate the ability to accurately determine refractive indices ranging from 1 to 1.39, as well as measure hydrogen density spanning from 0 g/cm3 to 0.13 g/cm3. This is achieved through the assessment of absorption peak locations, the intensity of absorption, and the field enhancement factor (FEF) at the peak. The subtle absorption peak experiences a shift in alignment with the changes in refractive indices. The relationship between the peak position and the refractive index demonstrates an exceptional degree of linearity, achieving the R2 value of 1. The values of Q, Sλc, and FOM average at 1437, 1.24 μm·RIU−1, and 682.38 RIU−1, respectively. The study also examines the effects of the incident angle of the external electromagnetic (EM) field and the number of dielectric films. Within a limited range of incident angles, an increase in the angle results in a shift of the absorption peak towards shorter wavelengths. The number of films plays a role in modifying the absorption intensity and the field enhancement factor (FEF) at the peaks. The proposed MSs offer improved energy harvesting capabilities from the surface EM fields. They can also be employed for refractive index detection. Besides, the field enhancement phenomenon provides valuable insights into the adsorption and storage of the hydrogen.

Nonlinear optical properties of modified Möbius squared potential well: influence of electric and magnetic fields

ABSTRACT This work presents a numerical study on the electronic and optical properties of modified Möbius squared potential well in the presence of static electric and magnetic fields. The potential well is formed within GaAs/AlGaAs hetero structures. Schrödinger’s equation is solved within the framework of effective mass and envelope wave function approximations to get the wave functions and their corresponding energies of states. The optical absorption coefficients and relative refractive index changes are calculated via the expressions derived from the compact density matrix approach. The numerical results present strong blue shifts on the optical responses of modified Möbius squared potential well when the external electromagnetic fields are strengthening.

Electromagnetic-mechanical coupling analysis of high-temperature superconducting racetrack coil

The second-generation high-temperature superconducting (HTS) coated conductor has been recognized as one of the most promising materialsfor high field magnets due to its superior electromagnetic and mechanical performances. HTS racetrack coils wound with the coated conductors are an extensively used configuration in engineering applications, such as HTS machines and high-speed maglevs. In this paper, in order to analyze the electromagnetic and mechanical behaviors of HTS racetrack coils, a 3D coupled electromagnetic-mechanical model is used to consider the effect of coil deformation and the strain dependence of critical current. The effectiveness of the coupled model is validated by comparing the numerical results with experimental data in the literature. A numerical simulation of a 3D HTS racetrack coil subjected to an external electromagnetic field is carried out using coupled and uncoupled models. The results indicate that the structure deformation can reduce the penetration depth of the screening current, and the hoop stress and strain are mainly concentrated on the circular part of the racetrack coil. Afterwards, the influences of various parameters on the electromagnetic and mechanical responses of the HTS racetrack coil are also investigated.

Applicability of the 0–1 test for chaos in magnetized Kerr–Newman spacetimes

The dynamics of electrically neutral or charged particles around a magnetized Kerr–Newman black hole immersed in an external electromagnetic field can be described by a dimensionless Hamiltonian system. This Hamiltonian is given an appropriate time transformation, which allows for construction of explicit symplectic integrators. Selecting one of the integrators with good accuracy, long-term stabilized Hamiltonian error behavior and less computational cost, we employ the 0–1 binary test correlation method to distinguish between regular and chaotic dynamics of electrically neutral or charged particles. The correlation method is almost the same as the techniques of Poincaré map and fast Lyapunov indicators in identifying the regular and chaotic two cases. It can well describe the dependence of the transition from regularity to chaos on varying one or two dynamical parameters. From a statistical viewpoint, chaos occurs easily under some circumstances with an increase of the external magnetic field strength and the particle electric charge and energy or a decrease of the black hole spin and the particle angular momentum. A small change of the black hole electric charge does not very sensitively affect the dynamics of neutral particles. With the black hole electric charge increasing, positively charged particles do not easily yield chaotic motions, but negatively charged particles do. On the other hand, the effect of a small change of the black hole magnetic charge on the dynamical transition from order to chaos has no universal rule.

Regularization of electromagnetic field for self-force problem in de Sitter spacetime

The paper is concerned with the motion of a point electric charge in de Sitter spacetime. A point particle of mass m and charge q moving on a geodesic curve produces electromagnetic field that diverges at a particle’s position. The field is determined by the electromagnetic Green’s function by Higuchi and Lee (2008 Phys. Rev. D 78 084031). The self-force contains both divergent and finite terms, and the latter are responsible for the radiation reaction. Our derivation of an effective equations of motion is based on conservation laws corresponding to the group of isometry of de Sitter space. The Nöther quantities consist of particle’s individual characteristics and energy, momentum, and angular momentum carried by particle’s electromagnetic field. Following the Detweiler–Whiting concept that a charge’s motion should only be enforced by the regular component of its own field, we ignore the divergent terms in conservation laws. We assume that the divergencies are absorbed by particle’s individual characteristics within the renormalization procedure. Finite radiative terms together with kinematic particle’s characteristics constitute ten conserved quantities of closed particle plus field system. Their differential consequences yield the effective equations of motion of radiating charge in an external electromagnetic field and gravitation. Contributions to already renormalized particle’s four-momentum and its inertial mass originated from electromagnetic field and background gravity are also derived from ten balance equations.

Controlled‐NOT Gate Based on the Rydberg States of Surface Electrons

AbstractDue to the long coherence time and efficient manipulation, the surface electron (SE) provides a perfect 2D platform for quantum computation and quantum simulation. In this work, a theoretical scheme to realize the controlled‐NOT gate is proposed, where the two‐qubit system is encoded on the four‐level Rydberg structure of SE. The state transfer is achieved by a three‐level structure with an intermediate level. By simultaneously driving the SE with two external electromagnetic fields, the dark state in the electromagnetically induced transparency effect is exploited to suppress the population of the most dissipative state and increase the robustness against dissipation. The fidelity of the scheme is 0.9989 with experimentally achievable parameters.

Overview of the process technology for the preparation of ultrahigh purity indium required for the fabrication of indium phosphide related epitaxial structures based devices needed for advanced electronic applications

Indium, a rare metal, is created incidentally during the zinc refining process. When a zinc metal is produced, valuable elements, such as indium, are recovered and reused. The sulfide minerals, sphalerite, galena, and chalcopyrite, are all common hosts for indium metals. Indium metals of varying purities (from 99% to 99.9%) are used in many different commercial, other exclusive, specialty, dentistry, and research and development settings. In the production of indium phosphide and related select bulk single crystals, such as InP, InAs, InSb, etc., and select multilayered epitaxial material-systems based device structures, such as InGaAs/InP, InGaAsP/InP, etc., an ultrahigh purity (99.99999%) indium metal is used as one of the initial and primary input materials. light-emitting diodes, infrared detectors, lasers, and other components cannot be made without these device topologies. Triple junction solar cells made of GaInP, GaAs, and Ge with 40% conversion efficiency are being developed for use in space. Metal-organic and molecular beam epitaxial methods utilize trimethyl/triethyl-indium-epi-precursors, the high purity indium derivatives, as starting materials to develop and manufacture multilayered structures of InGaAs/InP, InGaAsP/InP, InGaN/InP AlInN, etc. The purpose of this review is to quickly touch on indium mineral sources, important uses for different indium metal grades, and the processes needed to refine, purify, and ultrahigh purify indium to higher purity levels using a zone refining–melting–leveling process, as well as impurity segregation considerations. The use of vacuum, inert gas environments, and an external electromagnetic field to efficiently segregate, levitate, stir, homogenize, and mix the molten zone/melt interface area (region) as well as purity analyses at ppb levels, class clean room, and packaging concepts were also discussed. This review also touched briefly on the use of ultrahigh purity indium in the preparation of TMIn, TEIn, and InCl precursors necessary for the growth of device structures by molecular beam, metal-organic vapor phase, atomic layer epitaxial, and chemical vapor deposition processes. Purifying and preparing polycrystalline indium to a type 7 N purity level as well as standardization and criticality testing for fine-tuning system parameters are essential parts of developing the purification process technology. It also highlights various compound semiconductors and epitaxial systems, such as high purity indium compounds, such as indium phosphide, for cutting-edge electronic applications. Material yield enhancement, impurity management (including C, O, N, and others), consistent results, impurity reduction (down to the ppb level), and class clean packaging are all active topics of research and development. There has been a rise in demand for ultrapure metals (7–10 N) with stringent purity criteria in the aerospace and defense sectors, where they are used in cutting-edge nanoelectronic applications. This literature review delves into these and related topics regarding the production of ultrahigh purity indium. The major objective of this review is to provide a concise summary of the research and development progress made toward the ultrahigh purity (7N-99.99999%) indium preparation and its epitaxial electronics application considerations as of the time of this writing.

Electromagnetic field and cardiovascular diseases: A state-of-the-art review of diagnostic, therapeutic, and predictive values.

Despite encouraging advances in early diagnosis and treatment, cardiovascular diseases (CVDs) remained a leading cause of morbidity and mortality worldwide. Increasing evidence has shown that the electromagnetic field (EMF) influences many biological processes, which has attracted much attention for its potential therapeutic and diagnostic modalities in multiple diseases, such as musculoskeletal disorders and neurodegenerative diseases. Nonionizing EMF has been studied as a therapeutic or diagnostic tool in CVDs. In this review, we summarize the current literature ranging from in vitro to clinical studies focusing on the therapeutic potential (external EMF) and diagnostic potential (internal EMF generated from the heart) of EMF in CVDs. First, we provided an overview of the therapeutic potential of EMF and associated mechanisms in the context of CVDs, including cardiac arrhythmia, myocardial ischemia, atherosclerosis, and hypertension. Furthermore, we investigated the diagnostic and predictive value of magnetocardiography in CVDs. Finally, we discussed the critical steps necessary to translate this promising approach into clinical practice.