Electromagnetic Field Intensity Research Articles

Mechanisms of 1s Double-Core-Hole Excitation and Decay in Neon

The formation and decay of double-core-hole (DCH) states of the neon ion irradiated by an intense electromagnetic x-ray field are studied theoretically. In the present research DCH formation is the result of sequential absorption of two photons with the creation of an intermediate ion. Detailed calculations of the partial decays and probabilities of shake-ups at the atomic and ionic ionization stages are presented. The angular distribution of photoelectrons corresponding to various residual ionic states are calculated. Specifically, we predict the lack of any photoelectrons corresponding to the residual ionic state 1s12s22pnmpn′2Sf+1D in the direction of the electric field polarization. Dynamical competition between single-core-hole state decay and excitation is analyzed and pulse parameters corresponding to various dynamical regimes are found.

Performance improvement approaches for optical fiber SPR sensors and their sensing applications

Optical fiber surface plasmon resonance (SPR) sensors point toward promising application potential in the fields of biomarker detection, food allergen screening, and environmental monitoring due to their unique advantages. This review outlines approaches in improving the fiber SPR sensing performance, e.g., sensitivity, detection accuracy, reliability, cross-sensitivity, selectivity, convenience and efficiency, and corresponding sensing applications. The sensing principles of SPR sensors, especially the performance indicators and their influencing factors, have been introduced. Current technologies for improving the fiber SPR performance and their application scenarios are then reviewed from the aspects of fiber substrate, intrinsic layer (metal layer), and surface nanomaterial modification. Reasonable design of the substrate can strengthen the evanescent electromagnetic field and realize the multi-parameter sensing, and can introduce the in situ sensing self-compensation, which allows corrections for errors induced by temperature fluctuation, non-specific binding, and external disturbances. The change of the intrinsic layer can adjust the column number, the penetration depth, and the propagation distance of surface plasmon polaritons. This can thereby promote the capability of sensors to detect the large-size analytes and can reduce the full width at half-maximum of SPR curves. The modification of various-dimensionality nanomaterials on the sensor surfaces can heighten the overlap integral of the electromagnetic field intensity in the analyte region and can strengthen interactions between plasmons and excitons as well as interactions between analyte molecules and metal surfaces. Moreover, future directions of fiber SPR sensors are prospected based on the important and challenging problems in the development of fiber SPR sensors.

Assessing Plasmonic Nanoprobes in Electromagnetic Field Enhancement for SERS Detection of Biomarkers.

The exploration of the plasmonic field enhancement of nanoprobes consisting of gold and magnetic core@gold shell nanoparticles has found increasing application for the development of surface-enhanced Raman spectroscopy (SERS)-based biosensors. The understanding of factors controlling the electromagnetic field enhancement, as a result of the plasmonic field enhancement of the nanoprobes in SERS biosensing applications, is critical for the design and preparation of the optimal nanoprobes. This report describes findings from theoretical calculations of the electromagnetic field intensity of dimer models of gold and magnetic core@gold shell nanoparticles in immunoassay SERS detection of biomarkers. The electromagnetic field intensities for a series of dimeric nanoprobes with antibody–antigen–antibody binding defined interparticle distances were examined in terms of nanoparticle sizes, core–shell sizes, and interparticle spacing. The results reveal that the electromagnetic field enhancement not only depended on the nanoparticle size and the relative core size and shell thicknesses of the magnetic core@shell nanoparticles but also strongly on the interparticle spacing. Some of the dependencies are also compared with experimental data from SERS detection of selected cancer biomarkers, showing good agreement. The findings have implications for the design and optimization of functional nanoprobes for SERS-based biosensors.

A Super-Boosted Hybrid Plasmonic Upconversion Process for Photodetection at 1550nm Wavelength.

A super-boosted hybrid plasmonic upconversion (UC) architecture comprising a hierarchical plasmonic upconversion (HPU) film and a polymeric microlens array (MLA) film is proposed for efficient photodetection at a wavelength of 1550nm. Plasmonic metasurfaces and Au core-satellite nanoassembly (CSNA) films can strongly induce a more effective plasmonic effect by providing numerous hot spots in an intense local electromagnetic field up to wavelengths exceeding 1550nm. Hence, significant UC emission enhancement is realized via the amplified plasmonic coupling of an HPU film comprising an Au CSNA and UC nanoparticles. Furthermore, an MLA polymer film is synergistically coupled with the HPU film, thereby focusing the incident near-infrared light in the micrometer region, including the plasmonic nanostructure area. Consequently, the plasmonic effect super-boosted by microfocusing the incident light, significantly lowers the detectable power limit of a device, resulting in superior sensitivity and responsivity at weak excitation powers. Finally, a triple-cation perovskite-based photodetector coupled with the hybrid plasmonic UC film exhibits the excellent values of responsivity and detectivity of 9.80AW-1 and 8.22×1012 Jones at a weak power density of ≈0.03mWcm-2 , respectively, demonstrating that the device performance is enhanced by more than 104 magnitudes over a reference sample.

Study of the effects of ultra-low intensity electromagnetic fields on biological objects

The object of research is the efficiency of exposure to electromagnetic field (EMF) of ultra-low intensity on biological objects, which is formed by a generator of broadband radiation. The principle of action of the generator is based on formation of electromagnetic radiation induced by periodic pulsed gas discharge in coaxial system of electrodes, which is loaded on a dielectric rod antenna. The method of selection of signals and corresponding equipment, which energy characteristics of radiation correspond to the criterion of non-thermal influence on bioobjects, is developed for obtaining a comparative assessment of influence bioefficiency. The proposed new method for processing experimental data using statistical calculations that meet the requirements for the processing and interpretation of the results. The seeds of wheat and interaction of millimeter range electromagnetic oscillations with bone marrow cells of rats were used as biological objects for investigating the effect of millimeter range electromagnetic oscillations. A biosensory effect was obtained when exposed to broadband radiation of ultra-low intensity, compared to the control sample. A change in the properties of the seeds, in particular, heat resistance, is observed. According to the experimental data, seeds turn out to be less susceptible to heat as a result of their pretreatment with EMF. The biological response is observed to depend on the frequency and time of irradiation. Also, the dependence of the decrease in the number of dead cells on the time of EMF irradiation was experimentally proved. The equation of dependence of selective average proportion of dead cells in rat bone marrow on irradiation time was calculated. Biosensory effect of exposure to broadband ultra-low intensity EMF of the developed emitter was revealed. It was established and statistically proved that the minimum time with the maximum positive effect of exposure to electromagnetic radiation of millimeter range on bone marrow cells of rats is 30 minutes, compared with an unirradiated sample. The results make it possible to evaluate the positive effect of electromagnetic oscillations on biological objects and propose the results of studies for practical use in the development of medical systems.

Novel 60 GHz Band Spatial Synthetic Exposure Setup to Investigate Biological Effects of 5G and Beyond Wireless Systems on Human Body.

The global spread of 5th generation (5G) wireless systems causes some concern about health effects of millimeter waves (MMW). To investigate biological effects of local exposure to 5G-MMW on human body, a novel 60 GHz band exposure setup was developed, and its performance was validated. A spatial synthetic beam-type exposure setup using two dielectric lens antennas was proposed to achieve high intensity 60 GHz irradiation to the target area of human skin. Variety distributions and intensities of electromagnetic fields at the exposed area, which is modified by incident angles of the combined beams, were simulated using finite-difference time-domain methods. The exposure performance we estimated was verified by temperature elevations of surface in a physical arm-shaped silicone phantom during the MMW exposure. The interference fringes generated in the exposed area due to the combined two-directional beam radiations were observed both in the simulation and in the phantom experiment but eliminated by applying an orthogonalizing polarized feeding structure. Under these exposure conditions, the local temperature changes, which could evoke warmth sensations, were obtained at the target area of the human forearm skin, which means the achievement of exposure performance we intended.

Influence of 50 Hz electromagnetic frequency on oxidative stress and morphological characteristics in mosquito-borne filariasis Culex pipiens

• The larvae of Culex pipiens were exposed to EMF frequency (50 Hz). • The biochemical and morphological changes in Culex pipiens were estimated. • The larval body weight and total protein in EMF treated groups were significantly decreased compared to control. • Antioxidant enzymes activity in EMF treated groups were decreased significantly compared to the control. • Both 500 & 1000 mT caused distinct malformations to the larval body parts. The electromagnetic field (EMF) is a vital issue in research, but its use as an alternative technique for insect management is still in its beginnings. The study aimed to evaluate the effects of exposure to the electromagnetic field on the biochemical analysis and morphological characteristics in Culex pipiens . Therefore, the third instar larvae were exposed to EMF frequency (50 Hz) at different intensities (250, 500, 1000 mT) for 1 h during four successive days. After end exposure to EMF, the biochemical analysis, oxidative stress parameters, body weight, and morphological features were investigated. The results showed that larval body weight and total protein content were decreased significantly in all treated groups compared to controls. The total lipid content significantly decreased at 500 & 1000 mT exposure, while the treatment group exposed to EMF at 250 mT was not statistically different compared to control. At a high intensity of EMF 1000 mT all oxidative stress parameters; catalase (CAT) and Glutathione S-transferase (GST) activity and lipid peroxidation level (MDA) were decreased significantly compared to the control. On the other hand, at a low intensity (250 mT), CAT and GST activity was significantly increased, while MDA content was not statistically changed. Scanning electron microscopy showed that both 500 & 1000 mT caused distinct malformations to the larval body parts, mouthparts, thorax and abdomen with last abdominal structures. In conclusion, the results demonstrated that EMF exposure is a considerable stress factor that affects oxidative state and morphological features in mosquitoes and give hope that EMF will be used as an alternative method for Culex pipiens vector control.

Plasmonic Core-Shell-Satellites with Abundant Electromagnetic Hotspots for Highly Sensitive and Reproducible SERS Detection.

In this work, we develop a Ag@Al2O3@Ag plasmonic core–shell–satellite (PCSS) to achieve highly sensitive and reproducible surface-enhanced Raman spectroscopy (SERS) detection of probe molecules. To fabricate PCSS nanostructures, we employ a simple hierarchical dewetting process of Ag films coupled with an atomic layer deposition (ALD) method for the Al2O3 shell. Compared to bare Ag nanoparticles, several advantages of fabricating PCSS nanostructures are discovered, including high surface roughness, high density of nanogaps between Ag core and Ag satellites, and nanogaps between adjacent Ag satellites. Finite-difference time-domain (FDTD) simulations of the PCSS nanostructure confirm an enhancement in the electromagnetic field intensity (hotspots) in the nanogap between the Ag core and the satellite generated by the Al2O3 shell, due to the strong core–satellite plasmonic coupling. The as-prepared PCSS-based SERS substrate demonstrates an enhancement factor (EF) of 1.7 × 107 and relative standard deviation (RSD) of ~7%, endowing our SERS platform with highly sensitive and reproducible detection of R6G molecules. We think that this method provides a simple approach for the fabrication of PCSS by a solid-state technique and a basis for developing a highly SERS-active substrate for practical applications.

Novel and non-invasive brain-computer interface-based stimulation device using frequency tuned electromagnetic fields to significantly reduce disability following sub-acute ischemic stroke: A pilot randomized controlled trial

Background: Exposure of the central nervous system to extremely low frequency and low intensity electromagnetic fields (ELF-EMF) increases plasticity-related processes, with associated clinical improvements. Aim: The purpose of this RCT was to explore the benefit of BrainQ’s novel and non-invasive stimulation device which uses frequency-tuned ELF-EMF treatment (BQ) to reduce general disability and improve upper extremity motor function (UEMF) in subacute ischemic stroke. Methods: Study was planned for n=50, but was discontinued due to COVID-19 at n=25. Participants were randomized to receive 40 minutes of BQ (active or sham) 5 days/week, for 8 weeks, with 10 minutes of PT. BQ uses brain-computer interface-based machine learning algorithms to extract motor-related spectral features in EEG for use as treatment frequencies, and is delivered via a wearable and portable device. Results: Primary endpoint: Fugl-Meyer Assessment – Upper Extremity improved significantly (and sooner) in the treatment group versus sham at W4 (23.2±3.91 vs. 9.9±3.2;13.6 points greater than sham p=0.0070) and after 8 weeks of treatment (31.5±2.97 vs. 23.1±4.99;p=0.0611). Secondary endpoints: Most strikingly, and as a major clinical indication of reduced disability, mRS, at W9 the treatment group showed a mean improvement of 2.5±0.18 points versus 1.3±0.16 points in the sham group (p=0.0005), i.e., a mean of 1.2 points higher than that of the sham group. Significant improvements were also observed in the ARAT–Pinch subscale (W9: p=0.0082), BBT (W6: p=0.0169;W9: p<0.0001), and NIHSS (W9: p=0.0340). Conclusion: BQ treatment significantly reduces general disability and improves UEMF in subacute ischemic stroke across multiple metrics. A pivotal study is planned, with an explicit motivation of moving toward home use, for a more patient-centric approach. Keywords: Brain computer interface, Non-invasive brain stimulation, Neurological recovery, Stroke

Generation of long homogeneous plasma channels with high power long-wave IR pulsed Bessel beams.

Long-wave multi-joule ultrashort laser pulses are predicted to confine highly uniform electromagnetic energy and field intensities while sustaining high density uniform plasmas within nonlinear Bessel zones under extreme driving conditions in contrast to near-IR sources. This opens up novel applications in laser wakefield generation, radiofrequency/microwave guiding, and lightning control.

Medical and geographical determinants of oncopathology in the population

The aim: to study the permanent risk factor of oncopathology in order to determine its medical and geographical features and assess their impact on oncopathology of the population of Zaporizhzhia region. Materials and methods. By means of spatial and geographical, as well as analytical and statistical methods, territories were medically and statistically differentiated, with the assessment of the natural environment quality. Epidemiological study of malignant neoplasms was conducted retrospectively for the period of 2004–2015, in accordance with the International Classification of Diseases ICD-10. Determination of environmental impact on oncopathology was performed using the attributive fraction. Results. Geoactive space is characterized by a variety of natural and climatic conditions of lithosphere, hydrosphere and landscapes. The main physical and geographical objects of the Zaporizhzhia region (Ukrainian Crystal Shield, the Dnipro, the Sea of Azov) form six zones, which differ in the diversity of system-forming elements. Specific features of discontinuous disturbances of the lithosphere of the Ukrainian crystal shield are abnormally high electrical conductivity of the earth’s crust, intense electromagnetic fields, high concentration of radon in aquifers, and streams of high-energy fluids. Conclusions. The highest geopathogenic impact is manifested in the fault zone of the Ukrainian crystal shield. The highest values of the attributive fraction of malignant neoplasms were registered in this zone among the whole population (26.8 %), among the adult population (25.4 %) and the able-bodied population (32.7 %). The oncopathological potential of natural conditions was least manifested in the valley of the Dnipro breakthrough and the Azov Upland, where the attributive fraction for almost all indicators did not exceed 8.2 %.

Pulsed Magnetic Fields Cause hes1 and hsa-Circ-0068530 Expression Changes in Gastric Cancer Cell Line and Human Normal Fibroblast Cell Line

Background: In recent years, the relationship between cancer cells and electromagnetic radiation has received much attention. Objectives: The present study aimed to evaluate the effects of different intensities of electromagnetic fields on gastric cancer cell lines (AGS). Methods: After preparing AGS and Hu02 (normal) cell lines, they were exposed to magnetic flux densities of 0.25, 0.5, 1, and 2 millitesla (mT) for 18 h. The cell viability was studied by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The expression levels of hes1 and hsa-circ-0068530 RNAs were studied by the quantitative Real-time-PCR technique. Results: The inhibition of gastric cancer cell line growth was observed under the influence of electromagnetic fields at different intensities. However, they did not affect the viability of normal cells. A sharp increase in the expression of hes1 and hsa-circ-0068530 genes was observed in normal cells exposed to 2 mT electromagnetic fields. Conclusions: In general, it can be concluded that the effect of electromagnetic fields on gastric cancer cells depends on their intensity. Magnetic flux densities of 0.25 and 0.5 mT had anti-cancer effects and magnetic flux density of 2 mT showed carcinogenic effects.

Transverse and longitudinal coupling of LSPPs in isolated triangular Al–SiO2–Al hybrid nanoplates for generation of local electromagnetic fields with enhanced intensity and increased decay time

Achieving a large enhancement of local electromagnetic fields in the ultraviolet waveband is desirable for some applications such as surface-enhanced Raman scattering and surface-enhanced fluorescence. In addition, it is more significant for some applications such as plasmon-enhanced harmonic generation to enhance the intensity of local electromagnetic fields and increase their decay time at the same time. In this paper, using the finite-difference time-domain method, we numerically demonstrate that using the linearly polarized light with a wavelength of 325 nm as the illumination light, an isolated triangular Al–SiO2–Al hybrid nanoplate with optimized geometric parameters can produce a local electric field enhanced by a factor of about 108 at one of its top apexes, and produce two local electric fields enhanced by a factor of about 150 at two transverse dielectric/metal interfaces of one of its longitudinal side edges. Moreover, we also numerically demonstrate that the decay time of enhanced local electric fields produced by the isolated triangular Al–SiO2–Al hybrid nanoplate is about 1.6 times as large as that of enhanced local electric fields produced by an isolated triangular Al nanoplate. These unique properties of the isolated triangular Al–SiO2–Al hybrid nanoplate arise because of both the transverse coupling and the longitudinal coupling of localized surface plasmon polaritons in this structure. Our findings make triangular Al–SiO2–Al hybrid nanoplates very promising for application in many fields such as surface-enhanced Raman scattering and plasmon-enhanced harmonic generation.

Multiarchitecture-Based Plasmonic-Coupled Emission Employing Gold Nanoparticles: An Efficient Fluorescence Modulation and Biosensing Platform.

Surface plasmon-coupled emission (SPCE) is an efficient surface-enhanced fluorescence method based on the near-field coupling process of surface plasmons and fluorophores. Based on this, we developed multiple coupling structures for an SPCE system by introducing gold nanoparticles (AuNPs) with different architectures by adjusting different modification methods and configurations. By assembling AuNPs on a gold substrate through electrostatic adsorption and spin-coating, 40- and 55-fold enhancements were obtained compared to free space (FS) emission, respectively. After theoretical simulations and the optimization of experimental conditions, a novel "hot-spot" plasmonic structure, an intense electromagnetic field within the system, plasmonic properties, and the coupled process were found to be mainly responsible for the diverse enhancement effects observed. For the spin-coating deposition method, new enhancing systems with high efficiency can be easily built without complex modification. Additionally, the subsequent detection system based on the uniform modification of AuNPs through electrostatic adsorption is convenient to establish with high sensitivity and stability, which can broaden the application of SPCE in both fluorescence-based sensing and imaging. This AuNP-enhanced SPCE using an electrostatic adsorption method was designed as an immunosensor to prove feasibility.

Plasmonic-Silver Sorets and Dielectric-Nd2O3 nanorods for Ultrasensitive Photonic Crystal-Coupled Emission

Nanocavities forms the basis for plasmon-enhanced luminescence-based sensing technologies. Although surface plasmon-coupled emission platform has progressed with interdisciplinary applications, detrimental Ohmic losses in them hamper luminescence enhancement. An analogous micro-photonic platform, photonic crystal-coupled emission platform overcomes these limitations with Purcell–enhanced luminescence augmentation. Ag soret colloids presenting interfacial nanovoids offered amplified emission enhancements while coupling with Bloch surface waves in one-dimensional photonic crystal. A highly desirable synergistic approach with the use of plasmonic-silver nanoassembly (soret) and dielectric, high refractive index, Nd2O3 ‘Huygen’ sources (efficient forward light scatterers) have been comprehensively studied with added understanding from numerical calculations. A judicious synergy of metal and dielectric plasmonics with photonic crystal interface is demonstrated with new biophysicochemical insights. Fluorescence enhancements, directional and polarized emission obtained in excess of 1200-fold was utilized for attomolar sensing of xenobiotic Rhodamine B dye in integrated cavity ‘hotspots’ due to amplified electromagnetic field intensity.

"Rotation of Simple Organic Systems Can Be Induced by Low Intensity Electromagnetic Fields"

"Rotation of Simple Organic Systems Can Be Induced by Low Intensity Electromagnetic Fields"

Abundant Firing Patterns in a Memristive Morris–Lecar Neuron Model

Improving the neuron model and studying its electrical activities according to the real biophysical environment are significant in human cognitive brain activity and neural behavior. The complex transmembrane motion of ions on the neuronal cell membrane can establish time-varying electromagnetic fields and affect the transition firing patterns of neurons. In this paper, a threshold memristor is used to describe the electromagnetic induction and magnetic field effects of neuron cell membrane ion exchange to improve the neuron model, and a memristive Morris–Lecar (mM–L) neuron model is proposed. Numerical simulation confirms that different intensities of electromagnetic fields can produce distinct pattern transitions in electrical activities of the neuron, such as periodic bursting, periodic spiking, chaotic bursting. From the perspective of neuron’s interspike interval (ISI), the ISIs bifurcation in the multiparameter planes, ISIs firing periods, the variance of ISIs and other methods are used to find the trend of the mM–L neuron firing pattern transition. Finally, based on the 4D nonlinear differential equation of the mM–L neuron model, the complete electronic implementation of the model is designed. The output of the designed circuit is consistent with the theoretical prediction, which is extremely useful for studying the dynamics of a single neuron.

Power Frequency Еlectromagnetic Fields of Electrical Installations in Buildings

Introduction: All components of the power supply system are sources of electric and magnetic fields of industrial frequency of 50 Hz, both posing risks to human health. Estimation of predicted magnetic field levels from switchboards and transformers inside buildings is challenging and implies the importance of full-scale measurements of electromagnetic fields from built-in electrical equipment. Objectives: To establish the levels of 50 Hz electromagnetic fields during operation of built-in electrical installations in industrial, public, and residential premises. Materials and methods: We studied 50 Hz electromagnetic fields generated by electrical installations located in buildings. EMF levels were measured near transformers, switchboards, and switchgear. The electromagnetic situation in the rooms above the electrical equipment was investigated. The assessment of EMF levels was carried out in accordance with the current hygienic standards. Results: The intensity of electric fields near the equipment and in the surveyed premises was significantly lower than that of magnetic fields. The excess of maximum permissible levels at workplaces of operators servicing EMF sources in residential buildings was not detected. In the rooms of public buildings located above electrical installations, measured values of magnetic field induction ranged from 0.18 to 31 µT. The intensity of magnetic fields depended on the current load and the distance from EMF sources. Discussion: Electromagnetic field intensity depends on specifications of equipment, current loads, and distances from the sources of electromagnetic fields. Induction of 50 Hz magnetic fields in adjacent rooms may exceed hygienic standards set for residential and public buildings. Additional adverse factors include instability of magnetic fields caused by current load changes and significant magnetic field gradients in premises.

Arrangement of Micro Dielectric Particles With Vector Vortex Beam Generated by Dual-Helical Dielectric Cone

Optical vortex is of great value in optical trapping, manipulating, and arranging. Here, we propose a dual-helical dielectric cone to generate a dual-vortex beam which can be used to manipulate and arrange dielectric microparticles in three-dimensional space. With the finite-difference time-domain simulation, we calculate the electromagnetic field intensity distribution, phase, and Poynting vector during the propagation of the dual-vortex beam, the optical force and optical torque on the microparticles in the range of dual-vortex beam is also considered. In the experiment, we use the phase mask projected on spatial light modulator to generate a dual-vortex beam, which can trap, manipulate, and arrange the fluorescent microparticles to a specific and stable shape, which is consistent with the results of our simulation calculations. The dual-vortex beam generated by the dual-helical dielectric cone provides a feasible method three-dimensional optical manipulation, which is significant in biophotonical researches.

Quantum Electrodynamics vacuum polarization solver

The self-consistent modeling of vacuum polarization due to virtual electron-positron fluctuations is of relevance for many near term experiments associated with high intensity radiation sources and represents a milestone in describing scenarios of extreme energy density. We present a generalized finite-difference time-domain solver that can incorporate the modifications to Maxwell’s equations due to vacuum polarization. Our multidimensional solver reproduced in one-dimensional configurations the results for which an analytic treatment is possible, yielding vacuum harmonic generation and birefringence. The solver has also been tested for two-dimensional scenarios where finite laser beam spot sizes must be taken into account. We employ this solver to explore different types of laser configurations that can be relevant for future planned experiments aiming to detect quantum vacuum dynamics at ultra-high electromagnetic field intensities.