Electromagnetic Field Research Articles

Simultaneous Occurrence of Electromagnetic and Quasi‐Electrostatic Magnetosonic Waves

AbstractMagnetosonic (MS) waves usually manifest as electromagnetic fluctuations, while quasi‐electrostatic magnetosonic (QEMS) waves have been recently reported. Here we present an intriguing coexistence of low harmonic electromagnetic magnetosonic (EMMS) waves and QEMS waves within the same band. Ion Bernstein instabilities are calculated based on the observed proton distribution. Effective growth rates can occur in the first‐fourth harmonic bands with a broad wave number range when the wave normal angle is sufficiently large. In each harmonic band, the MS waves would transform from electromagnetic to electrostatic as the wave number increases. This study reveals that the simultaneous occurrence of EMMS and QEMS arises from the expansive excitation range of MS waves in ‐space, thereby implying the potential resonant interactions between MS and particles in a broad energy spectrum.

Investigation of long-range plasmonic field effects in Au@SiO2 nanostructures using p-nitrophenol reduction

As an emerging field, plasmonic photocatalysis has gradually garnered attention from researchers. It is generally accepted that localized surface plasmonic resonance (LSPR) in noble metallic nanostructures enhances photocatalysis through the induction of a long-range plasmonic field. Furthermore, nanostructures in close proximity can enhance the electromagnetic (EM) field via plasmonic coupling, which also contributes to improved photocatalytic activity. In this study, core-shell nanostructures composed of Au nanorods (AuNRs) with pinhole-free SiO2 shells (pf-AuNRs@SiO2) are synthesized as non-contact, long-range photocatalysts. By tuning the aspect ratios (ARs) of the AuNRs to match the LSPR peaks with the wavelength of the irradiation light source, an optimized photocatalytic effect was achieved in the reduction of p-nitrophenol (p-NP). Additionally, by comparing shell thicknesses of 5 nm and 10 nm, it was observed that the 5 nm thickness exhibited superior catalytic efficiency. This enhancement is attributed to the thinner shell allowing reactants to be placed within a stronger plasmonic field.

MOFs-derived copper selenides nanoparticles implanted in carbon matrix for broadband electromagnetic wave absorption

Selenide-based functional composites materials demonstrated tunable dielectric properties and heterogeneous interface design, which has been widely studied in electromagnetic (EM) wave absorption field. Herein, Metal-organic frameworks (MOFs) derived carbon coating copper selenide (Cu2-XSe@C) composites were successfully fabricated by using the Cu-MOFs as precursor. After reacting with the gaseous Se in the selenization annealing process, the metal host was converted into the Cu2-XSe nanoparticles, where embodied in the carbon matrix transformed from the organic linker. Based on the tunning dielectric property and building heterogeneous interface, MOFs-derived Cu2-XSe@C composites displayed outstanding EM wave absorption performance. Though the conduction loss, interfacial and dipole polarization behaviors, the minimum reflection loss (RLmin) value of Cu2-XSe@C-600 composites reached to −74.3 dB at 11.7 GHz when the thickness is 2.0 mm. The efficient absorption bandwidth (EAB) can be regulated via controlling the applied thickness. When the thickness is 2.3 mm, above-mentioned Cu2-XSe@C-600 got the broadest absorption performance with the EAB of 5.5 GHz from the 7.7–13.2 GHz, covering the whole X-band. Therefore, MOFs-derived selenide-based composites shed a new design strategy for constructing broadband EM wave absorption, especially in radar stealth applications.

Could prayer’s info-energy restore the distorted informational field in the extracellular space of cancerous tissue?

This article explains for the first time how stress (negative emotions or just negative thinking) causes cancer or chronic disease of the genetically inherited weak organ. For the first time, it is explained why for some individuals stress leads to chronic disease of the genetically inherited weak organ, while for other individuals it leads to cancer of the genetically inherited weak organ. It is believed to be with genetic predisposition, but for the first time this article explains what this means. 1/ Stress causes chronic disease of genetically inherited weak organ when the integrating energy within the cell is weak. This makes the cellular biorhythms of the genetically-inherited weak organ weakly integrated and easily disintegrated by stress, which by causing delays disorders the biorhythms, and results in chronic disease. 2/ Stress causes cancer of the genetically inherited weak organ, when the integrating energy between the cells is weak. When the weak extracellular energy is farther weakened by stress, at critically low energy stacked-coin formations appear between the cells, which disconnect the cells. The disconnected cells start to multiply fast as they would do in the case of cut wound, to heal the wound fast. However, in the case of wound the cells are ruled where to go by the current of regrowth. In the case of cancer, they multiply senselessly, which is called malignancy. Since both energies - within the cells and in the extracellular space - are informational nonlinear electromagnetic fields (NEMFs) and prayer is information, prayer should be able to influence the cellular organization in the case of chronic diseases, and the extracellular formations in the case of cancer.

Ball-in-hole 3D nanoarchitectonics based on nanoporous Au film: Ultrasensitive, highly reliable, and reusable plasmonic platform

Hotspots have a locally enhanced electromagnetic field, effectively created by nanogaps in plasmonic metal nanostructures. The formation of uniform nanogaps, smaller than a few nanometers, allows for the detection of analytes at low concentrations and ensures reliable measurements across entire surface-enhanced Raman scattering (SERS) substrates. Despite the demand for SERS substrates in recent optical sensing applications, challenges remain in developing new techniques to maximize the number and optimize the size of nanogaps on large-area substrates. To address this issue, this study introduces a new ball-in-hole technique based on metal nanoarchitecture utilizing 3D nanoporous gold film (NPGF) and 0D gold nanoparticles (AuNPs). Using the ball-in-hole technique, 23 nm AuNPs are placed within the ∼ 28 nm mesopores of the metal film, creating uniform nanogaps of just a few nanometers that ensure consistent SERS signals across a large substrate area due to effective hotspots. The 23nmNP@NPGF substrate exhibited an enhancement factor (EF) of 1014 for 4-aminophenol (4-ATP), enabling detection at the attomole level. Moreover, the substrate retained its performance after five washing and reuse cycles, demonstrating excellent recyclability Finally, the substrate successfully detected femtomolar concentrations of key neurotransmitters like dopamine and glutamate, without requiring Raman reporters. This study presents a promising strategy for constructing metal nanoarchitectures with numerous hotspots, offering new possibilities for developing more efficient SERS substrates.

Characteristics and optimization strategy of microwave thermal regeneration of spent activated carbon based on a multi-physical field model

Microwave thermal regeneration is an efficient and low-consumption way to recycle spent activated carbon. However, traditional experimental approaches are difficult to analyze the electromagnetic field distribution in the microwave cavity, heat and mass transfer process of adsorbates, and optimization of the microwave reactor. Therefore, in this work, a multi-phase porous media model coupled with electromagnetism, heat and mass transfer is established to study the characteristics of microwave thermal regeneration procedure and to propose an optimization strategy for the microwave reactor. The results showed that the absorption of microwave by the sample can be strengthened by adjusting the width to height ratio of the waveguide. The optimal waveguide size (width: length = 80 mm: 10 mm) increased the microwave utilization efficiency from 65.4 % to 98.5 %. In addition, the combination of rotary and intermittent microwave heating significantly optimized the temperature uniformity in both lateral and vertical directions and reduced the microwave heating time. The combined microwave heating time was reduced from the initial 136 s to 80 s, saving 41 % of energy consumption. The temperature difference of the sample was also reduced from the initial 536 K to 191 K, and the covariance COVT decreased from 0.52 to 0.24. The results provide a valuable technical guideline for the optimization of the microwave reactor in order to improve the regeneration efficiency and the quality of the regenerated carbon.

Super-Resolution Surface-Enhanced Raman Scattering: Perspectives on the Past, Present, and Future.

Super-resolution surface-enhanced Raman scattering (SERS) allows researchers to overcome the resolution limit of far field optical microscopy and peer into electromagnetic hot spots with nanoscale resolution. By localizing the signal from single (or few) molecules on the surface of plasmonic nanoparticle aggregates, relationships between the spatial origin of the SERS signal, local electromagnetic field enhancements, and SERS intensity can be determined. This Perspective describes the successes and challenges of super-resolution SERS, from the earliest mapping of single-molecule SERS hot spots to the current state-of-the-art, while highlighting open questions and future opportunities to advance the field. Comparisons with fluorescence-based super-resolution imaging are discussed to help frame the unique challenges associated with performing SERS in the super-resolution regime.

Thermally Stable Oxide-Capsulated Metal Nanoparticles Structure for Strong Metal-Support Interaction via Ultrafast Laser Plasmonic Nanowelding.

Strong metal-support interaction (SMSI) has drawn much attention in heterogeneous catalysts due to its stable and excellent catalytic efficiency. However, construction of high-performance oxide-capsulated metal nanostructures meets great challenge in materials thermodynamic compatibility. In this work, dynamically controlled formation of oxide-capsulated metal nanoparticles (NPs) structures is demonstrated by ultrafast laser plasmonic nanowelding. Under the strong localized electromagnetic field interaction, metal (Au) NPs are dragged by an optical force toward oxide NPs (TiO2). Intense energy is simultaneously injected into this heterojunction area, where TiO2 is precisely ablated. With the embedding of metal into oxide, optical force on Au gradually turned from attractive to repulsive due to the varied metal-dielectric environment. Meanwhile, local ablated oxides are redeposited on Au NP. Upon the whole coverage of metal NP, the implantation behavior of metal NP is stopped, resulting in a controlled metal-oxide eccentric structure with capsulated oxide layer thickness ≈0.72-1.30nm. These oxide-capsulated metal NPs structures can preserve their configurations even after thermal annealing in air at 600°C for 10min. This ultrafast laser plasmonic nanowelding can also extend to oxide-capsulated metal nanostructure fabrication with broad materials combinations (e.g., Au/ZnO, Au/MgO, etc.), which shows great potential in designing/constructing nanoscale high-performance catalysts.

Footwear for Diabetics – Structural and Material Elements for the Prevention and Alleviation of Foot Lessions

Abstract Diabetic foot syndrome is a syndrome of specific conditions affecting the foot. It is a complication of diabetes. It occurs in 12–25% of patients with diabetes. Untreated, it leads to irreversible deformities and necrosis of the foot, often resulting in amputation. In this study the statistics and consequences of diabetic foot syndrome are described. Patients with diabetes need to take care of their lower limbs. Proper footwear can prevent foot wounds. Available solutions for the prevention and treatment of diabetic foot syndrome are presented herein: footwear, insoles and requirements for footwear materials. Appropriate equipment for a person with diabetes, especially one who has been diagnosed with diabetic foot syndrome or is at risk of such a condition, includes footwear and replaceable insoles. The parameters of footwear, insoles and footwear materials that are most optimal for patients with diabetes and diabetic foot syndrome were defined. The effect of a pulsed electromagnetic field and pulsed ultrasound on diabetic foot problems was evaluated.

Automatic Extraction of VLF Constant‐Frequency Electromagnetic Wave Frequency Based on an Improved Vgg16‐Unet

AbstractConstant Frequency Electromagnetic Waves (CFEWs) refer to electromagnetic waves with a constant frequency. Man‐made CFEWs are mainly used in wireless communication, scientific research, global navigation and positioning systems, and military radar. CFEWs exhibit horizontal line characteristics higher than the background on spectrograms. In this study, we focus on Very Low Frequency (VLF) waveform data and power spectral data collected by the China Seismo‐Electromagnetic Satellite (CSES) Electromagnetic Field Detector (EFD). We utilize deep learning techniques to construct an improved Vgg16‐Unet model for automatically detecting horizontal lines on time‐frequency spectrogram and extracting their frequencies. First, we transform waveform data into time‐frequency spectrogram with a duration of 2 s using Short‐Time Fourier Transform. Then, we manually label horizontal lines on the time‐frequency spectrogram using the Labelme tool to establish the dataset. Next, we establish and improve the Vgg16‐Unet deep learning model. Finally, we train and test the model using the dataset. Statistical experimental results show that the error rate of line detection is 0, indicating high reliability of the model, with fewer parameters and fast computation speed suitable for practical applications. Not only do we detect lines through the model, but we also obtain their frequencies. Additionally, in batch‐generated power spectrogram of CFEWs, we discover some unstable phenomena such as frequency shifts and fluctuations, which contribute to understanding the propagation mechanism of CFEWs in the ionosphere and improving the accuracy of related systems.

Design, analysis, and optimization of PMSM for ultra-deep water pile hammer application

With the development of global deepwater oil and gas and offshore wind power resources, there is an increasing demand for ultra-deep water pile hammers (UDPH). In this paper, a permanent magnet synchronous motor (PMSM) with oil fill is proposed for UDPH on the basis of underwater 2500 m depth and 450 kJ impact energy requirements. First, the rated parameters of the PMSM are calculated based on the power required by hydraulic pumps, and then, the method of combining empirical formulas and path algorithms is used to complete the electromagnetic scheme design. Second, finite element analysis of the electromagnetic field is carried out by Maxwell under both no-load and load conditions to verify the rationality of the PMSM. Furthermore, aiming at improving efficiency and reducing cogging, parameter optimization is carried out by a robust parameter optimization design method, and the optimal parameter scheme of the PMSM is obtained. In addition, loss analysis and temperature field coupling calculations of the optimized PMSM are conducted to verify that the temperature of this motor can meet the requirements under different working conditions. Finally, a comparative analysis is conducted between the proposed PMSM and the three-phase asynchronous motor used in the underwater 2,500 m-450 kJ UDPH. The results indicate that the new PMSM introduced in this paper demonstrates significant advantages in terms of weight, volume, and efficiency; moreover, the new PMSM is reasonable and more suitable for UDPH. Therefore, the PMSM proposed in this paper is reasonable and can provide a theoretical basis for improving the traditional UDPH.

Multipolar Electromagnetic Emission of Newborn Magnetars

It is generally recognized that the electromagnetic multipolar emission from magnetars can be used to explain radiation from soft gamma repeaters or anomalous X-ray pulsars, but they have little impact on the spin-down of magnetars. We here present an analytical solution for the neutron star multipolar electromagnetic fields and their associated expected luminosities. We find that for newborn millisecond magnetars, the spin-down luminosity from higher multipolar components can match or even exceed that from the dipole component. Such high-intensity radiation will undoubtedly affect related astrophysical phenomena at the birth of a magnetar. We show that the spin-down luminosity from multipoles can well explain the majority of gamma-ray burst (GRB) afterglows, from the plateau starting at several hundred seconds until the normal decay phase lasting for many years. The fitted magnetar parameters for GRB afterglows are all typical values, with spins in the millisecond range and magnetic field strengths on the order of 1014–1015 G. Our results, in turn, provide support for the hypothesis that GRBs originate from the birth of magnetars with a period of a few milliseconds, thus deepening our understanding of the complex magnetic field structure and the equation of state of magnetars.

Relativistic beam loading, recoil-reduction, and residual-wake acceleration with a covariant retarded-potential integrator

An algorithm is demonstrated that performs first-principles tracking of relativistic charged-particles. A covariant approach is used which relies on retarded vector potentials for trajectory integration instead of performing electromagnetic field calculations. When accounting for retardation effects, the peak vector potential and corresponding Lorentz force in the direction of travel increase asymptotically for high-β particles. This produces a very strong field distribution at small angles from the particle’s direction of travel, which can result in considerable change in momentum when approaching a conducting or charged object. We study these dynamics using protons and electrons at relativistic energies passing through apertures in conducting surfaces, where substantial energy shifts are observed for particles passing within roughly 10μm of the aperture boundary.We also simulate breaking a test particle’s line of sight with a conductor or other charged body. After this instant, the test particle continues to accelerate due to residual fields, but no longer produces an opposing force on any charged or conducting object; thus any recoil on the enclosing structure is effectively reduced. In this test, a 1% energy gain is observed for an 85MeV electron traversing its reflected wake after having conducting plate in its path screened by a dielectric object.We then incorporate a micro-scale dielectric laser acceleration (DLA) device into our simulations. Compared with a 2 mm DLA on its own, we find a factor of two increase in energy gain when adding a series of conducting-surface choppers.

Enhanced densification and phase transformations during rapid microwave sintering of alumina – yttria-stabilized zirconia ceramics

Alumina – 7.5wt. % yttria-stabilized zirconia (YSZ) ceramic composites were sintered using 24GHz microwave heating at rates of 10 – 200°C/min with zero isothermal hold. The starting powders were nanophase η-Al2O3 and YSZ prepared by a laser evaporation method. The final densities of the sintered samples were up to 97.5% of the theoretical value. The samples exhibited rapid densification until transformation to the α-Al2O3 phase. The temperature of the densification rate peak (and hence of the phase transformation) decreased consistently with increasing microwave electromagnetic field intensity (varied by using different susceptor materials). The densification peak temperature difference between microwave and conventional sintering experiments exceeded 200 °C.

Effect of exposure to the electromagnetic waves emitted from cellular phone on the cerebellum and hippocampus of the adult male albino rats

Background The use of electromagnetic fields in daily life becomes more common, and it’s thought that these stimuli have an impact on various body cells and organs. Electromagnetic waves originate from several sources in our surroundings, such as radio antennae, TVs, wireless communication etc. One of the most prevalent sources of electromagnetic field induction is mobile phones. Aim To assess the effects of electromagnetic waves emitted from cellular phone on the cerebellum and hippocampus of the adult male albino rats. Materials and methods 40 male albino rats were exposed to cellular phones radiation. Rats were divided into three groups: control group (I): 20 adult male albino rats, experimental group (II): 10 rats constantly exposed to electromagnetic radiation (EMR) 2 h per day, 6 days a week, for 1 month and experimental group (III): 10 rats constantly exposed to EMR 2 h per day, 6 days a week, for two months. Then the rats were sacrificed and their cerebellum and hippocampus were stained and examined. Results Found that the intraneuronal neurofibrillary tangles in the neuronal cell body increased and that the EMR from cell phones produced a notable degeneration of cerebellar, hippocampus pyramidal, and granular neurons. Conclusions The neuronal damaging effect of EMR exposure can lead to hippocampus and cerebellar dysfunction.

Establishment of Multi-Physics coupling model and analysis on thermal stress and crack risk in directional growth of TiAl alloys under electromagnetic confinement

The electromagnetic confinement directional solidification (EMCDS) technique is an optimal method for preparing large-size and non-contamination directional TiAl alloy crystals. Despite its advantages, the high temperature gradient inherent to this process induces thermal stress within the ingot, which increases the risk of cracking. To address this challenge, an innovative Integrated Multi-Physics Coupling Model was established to map and study the thermal stress field during EMCDS in this study. It synchronized the computation of the electromagnetic field, temperature field, solute field, flow field, and stress field during the crystal growth of TiAl alloy, and its high accuracy was proved by the micro-indentation experiment. Our analysis reveals that transverse temperature differences are crucial in inducing thermal stresses, and identifies that hot cracks and cold cracks are prone to occur respectively at the area of radial 23R along the sample (X = 23R) and on the sample surface, which aligns with experimental observations impressively. This model can more accurately and efficiently optimize the process parameters of the EMCDS process to avoid cracks and promote its industrial application.

Identification of Sub-Fault Zone Using Magnetotelluric Inversion (Case Study: Ketaun Fault, Lemeu Village, Lebong Regency)

Lemeu Village, Lebong Regency, borders the Bukit Barisan Mountain range and is crossed by the Ketaun Fault, which causes a high level of seismic activity, so it is necessary to conduct research on the potential existence of the Ketaun sub-fault as one of the efforts to mitigate natural disasters such as earthquakes. The Magnetotelluric method utilises the earth's natural electromagnetic field, which is used to determine the distribution of resistivity in the subsurface using the ADU-07e Magnetotelluric tool with two horizontal electrical sensors (Ex, Ey) and three horizontal (Hx, Hy) and vertical (Hz) magnetic sensors and uses seven research points with an interval of 1 km. Data processing uses MAPROS software to convert data from the time domain to the frequency domain and ZONDMT2D to obtain subsurface resistivity values. The results obtained from this study are 2D magnetotelluric cross sections showing a zone with low resistivity values between research points P4 and P5 which is thought to be a new fault zone with resistivity values ranging from 1.3 – 6.1 Ωm from a depth of 2.5 km to a depth of 10 km. The zone is assumed to be a new fault that is a branch of the Ketaun fault.

Gyrokinetic linear simulation of feedback instability in dipole magnetosphere

We perform a novel linear simulation of the feedback instability by applying a gyrokinetic model to the magnetosphere, where the geomagnetic field is modeled by a dipole magnetic field. In order to avoid huge numerical calculation costs, the effect of the fluctuating mirror force is neglected. It is found that kinetic effects, such as the finite Larmor radius effect and the electron Landau damping, strongly stabilize the feedback instability and form a peak in the perpendicular wave number spectrum of the growth rate. During the linear growth, it is observed that electron free energy has a much larger value than the electromagnetic field perturbation energy. Since such large electron free energy may lead to electron heating and acceleration, it is important to understand its generation mechanism. Analyses based on the energy conservation reveal that the coupling of the non-uniformity of the equilibrium fields along the geomagnetic field and the fluctuating electron distribution gives rise to thermodynamic power generating the electron free energy. A fine velocity space structure around an average Alfvén velocity of the fluctuating electron distribution mainly contributes to drive the thermodynamic power.

Multifunctional conductive stem cell delivery hydrogel combined with low-frequency pulsed electromagnetic fields for spinal cord injury repair

Spinal cord injury (SCI) is a severe traumatic disease for which no satisfying treatment is available. The severe inflammatory reactions and poor endogenous regenerative capacity cause difficulty in functional recovery. Neural stem cells (NSCs) transplantation is currently a promising treatment for repairing SCI. However, there is a lack of effective ways to improve the survival rates of NSCs and promote the neuron differentiation rates of NSCs. Conductive hydrogel can mimic environment which is suitable for neurodevelopment. Low-frequency pulsed electromagnetic fields (LPEMFs) have the advantages of safety, non invasiveness, and tissue repair, making it a potential method of repairing SCI. In this study, an injectable, self-healing magnetic, and conductive hydrogel was synthesized to carry out NSCs with LPEMFs for repairing SCI. In vitro experiments, under the treatment of LPEMFs and conductive hydrogel, the microglia tend to polarize into M2 phenotype, rather than M1 phenotype. Meanwhile, NSCs tend to differentiate into neuronal direction. In SCI model, conductive hydrogel loaded with NSCs combined with LPEMFs can promote functional recovery, through reducing inflammation and promoting neuron differentiation of NSCs. This study provides a novel NSCs transplantation strategy combined with physical interventions for SCI treatment, which brings a new desire to repair SCI.

Numerical investigation of the late-time tails of the solutions of the Fackerell–Ipser equation

The late-time behaviour of the solutions of the Fackerell–Ipser equation (which is a wave equation for the spin-zero component of the electromagnetic field strength tensor) on the closure of the domain of outer communication of sub-extremal Kerr spacetime is studied numerically. Within the Kerr family, the case of Schwarzschild background is also considered. Horizon-penetrating compactified hyperboloidal coordinates are used, which allow the behaviour of the solutions to be observed at the event horizon and at future null infinity as well. For the initial data, pure multipole configurations that have compact support and are either stationary or non-stationary are taken. It is found that with such initial data the solutions of the Fackerell–Ipser equation converge at late times either to a known static solution (up to a constant factor) or to zero. As the limit is approached, the solutions exhibit a quasinormal ringdown and finally a power-law decay. The exponents characterizing the power-law decay of the spherical harmonic components of the field variable are extracted from the numerical data for various values of the parameters of the initial data, and based on the results a proposal for a Price’s law relevant to the Fackerell–Ipser equation is made. Certain conserved energy and angular momentum currents are used to verify the numerical implementation of the underlying mathematical model. In the construction of these currents a discrete symmetry of the Fackerell–Ipser equation, which is the product of an equatorial reflection and a complex conjugation, is also taken into account.