Search Results (4,980)

The development of anisotropic gold nanostructures supporting localized surface plasmon (LSP) resonances in the near-infrared (NIR) biological window is of great interest for diagnostic and therapeutic nanotechnologies. Here, we report gold open-shell nanoparticles (AuOSNs), a symmetry-broken nanoshell architecture exhibiting strong NIR surface-enhanced Raman scattering (SERS) activity. AuOSNs were fabricated via a surfactant-free strategy combining bottom-up silica sphere assembly with a simple top-down gold deposition process, without using highly cytotoxic surfactants such as cetyltrimethylammonium bromide (CTAB). Boundary element method (BEM) simulations revealed that the asymmetric open-shell geometry induces NIR LSP resonances with pronounced electromagnetic field localization near the opening edges, depending on excitation configuration. Consistent with these predictions, extinction spectra of AuOSNs dispersed in water showed an LSP resonance peak at ~793 nm, close to the 785 nm excitation wavelength for SERS. In aqueous dispersion, AuOSNs modified with 4-mercaptobenzoic acid (4-MBA) exhibited strong SERS activity with enhancement factors of ~10⁶. Furthermore, polyethylene glycol (PEG)-modified MBA/AuOSNs showed negligible cytotoxicity in vitro. SERS imaging confirmed that PEG/MBA/AuOSNs enable visualization of HeLa cells via characteristic MBA SERS signals. These results demonstrate that surfactant-free AuOSNs provide a biocompatible platform for NIR-excited SERS sensing and cellular imaging, highlighting their potential in plasmonic bioimaging applications. Full article

Dynamic wireless power transfer (DWPT) systems for in-motion electric vehicle (EV) charging often suffer from unstable power delivery due to spatial variations in magnetic coupling caused by vehicle misalignment. This study presents a stabilization-oriented DWPT design methodology that prioritizes minimizing spatial variations of mutual inductance rather than maximizing peak coupling under perfect alignment. A ferrite-backed double-D coil configuration is analyzed and refined using three-dimensional finite-element electromagnetic modeling integrated with circuit-level co-simulation to evaluate coupling behavior, magnetic field homogeneity, and power transfer efficiency under realistic dynamic misalignment conditions. The proposed design achieves a coupling coefficient of 0.50–0.55 under aligned conditions and exhibits smooth, predictable degradation for lateral offsets up to 40–50 mm. Quantitative analysis demonstrates a low spatial coupling gradient of approximately 0.001 mm⁻¹, indicating that abrupt coupling transitions are effectively suppressed during vehicle motion. The system attains a maximum power transfer efficiency of 84.37% at an 80 mm air gap, while maintaining stable performance under both lateral and vertical displacement. Comparative evaluation shows improved misalignment tolerance and coupling stability relative to conventional double-D configurations. The results demonstrate that electromagnetic field shaping focused on coupling smoothness is an effective and practical strategy for reliable dynamic wireless charging of electric vehicles. Full article

Intentional high-power electromagnetic (EM) interference poses a serious threat to sensitive electronic systems and often manifests as ultra-wideband (UWB) sub- and nanosecond pulses. Metallic shielding enclosures with technological apertures are commonly used for protection; however, apertures enable electromagnetic coupling into the enclosure and limit shielding performance. While most existing studies focus on transient disturbances with durations exceeding the enclosure transit time, this work addresses an ultrashort high-power subnanosecond UWB plane-wave pulse whose duration is significantly shorter than the enclosure transit time, a regime that remains insufficiently explored. A time-domain numerical analysis is performed for a low-profile rectangular metallic enclosure with a front-wall aperture, focusing on internal EM field evolution, internal pulse formation, and polarization-dependent shielding effectiveness. Three-dimensional full-wave simulations were carried out using CST Microwave Studio over a 90 ns observation window. The results show that the incident pulse excites primary subnanosecond EM waves inside the enclosure, which subsequently generate secondary waves through multiple reflections from the enclosure walls. Their interaction produces complex, long-lasting, time-varying internal field patterns. Although attenuated, the resulting internal subnanosecond pulses repeatedly traverse the enclosure interior, forming a pulse train-like sequence that may pose a cumulative electromagnetic threat to internal electronics. A key contribution of this work is the quantification of time-dependent local shielding effectiveness for both electric and magnetic fields, derived directly from the internal pulse train-like series obtained in the time domain. The concept of local, time-dependent shielding effectiveness provides physical insight that cannot be obtained from a single globally averaged SE value. In the case of ultrashort electromagnetic pulse excitation, the internal field response of an enclosure is strongly non-stationary and highly non-uniform in space, with local field maxima occurring at specific times and locations despite good average shielding performance. Time-dependent local SE enables identification of worst-case temporal conditions, repeated high-amplitude internal exposures, and critical regions inside the enclosure where shielding is significantly weaker than suggested by global metrics. Therefore, while conventional SE remains useful as a summary measurand, local time-dependent SE is essential for assessing the actual electromagnetic risk to sensitive electronics under ultrashort pulse disturbances. In addition, a global shielding effectiveness metric mapped over selected enclosure cross-sections is introduced to enable rapid visual assessment of shielding performance. The analysis demonstrates a strong dependence of internal wave propagation, internal pulse formation, and both local and global shielding effectiveness on the polarization of the incident subnanosecond EM pulse. These findings provide new physical insight into aperture coupling and shielding behavior in the ultrashort-pulse regime and offer practical guidance for the assessment and design of compact shielding enclosures exposed to high-power UWB EM threats. Full article

Measuring water motion is essential for oceanography, coastal engineering, and marine environmental monitoring. A wide range of sensing technologies is used to quantify water velocity, wave motion, and flow dynamics, each suited to specific spatial and temporal scales. This paper presents a comprehensive review of modern sensor technologies for marine flow measurement, covering mechanical, electromagnetic, pressure-based, acoustic, optical, MEMS-based, inertial, Lagrangian, and remote-sensing approaches. The operating principles, strengths, and limitations of each technology are examined alongside their suitability for different environments and deployment platforms, including moorings, buoys, vessels, autonomous underwater vehicles, and drifters. Special attention is given to rapidly advancing fields such as MEMS flow sensors, multi-sensor fusion, and hybrid systems that combine inertial, acoustic, and optical data. Applications range from high-resolution turbulence measurements to large-scale current mapping and wave characterization. Remaining challenges include biofouling, performance degradation in energetic shallow waters, uncertainties in indirect velocity estimation, and long-term calibration stability. By synthesizing the state of the art across sensing modalities, this review provides a unified perspective on current technological capabilities and identifies key trends shaping the future of marine flow measurement. Full article

To address the low application accuracy and poor spreading uniformity of conventional lime spreaders, an electromagnetic vibration-assisted variable-rate lime spreader integrating a shaftless screw metering mechanism was developed. The overall configuration and operating principle are presented. Considering the physicochemical characteristics of lime powder, including fine particle size, strong drift tendency, and poor flowability, a shaftless screw metering unit was designed to improve discharge stability and metering accuracy. To enhance dispersion uniformity, a vertical electromagnetic vibration device was developed, and its key parameters were determined through a theoretical analysis of vibration frequency and amplitude. In addition, the structure and kinematic parameters of the spreading disc were optimized by analyzing particle trajectories and outlet distribution patterns. A closed-loop feedback control strategy was implemented to enable precise variable-rate application. Static bench tests demonstrated a metering accuracy of 96.42%, and the dispersion uniformity was at least 84.14% at an electromagnetic vibration frequency of 10 to 18 Hz. Field evaluations further showed that the coefficient of variation for transverse uniformity was no more than 17.88%, while the maximum coefficient of variation for longitudinal stability was 18.09%. These results indicate that the proposed spreader satisfies the operational requirements for accurate and uniform variable-rate application of lime powder. Full article

Diamond is becoming an increasingly popular substrate material in the semiconductor industry due to its high thermal conductivity and wide forbidden band characteristics. With the development of high-power electronic devices, the demand for large-area single-crystal diamond films is also dramatically increasing. Microwave plasma chemical vapor deposition (MPCVD) technology is the dominant method for producing high-quality diamond films due to its advantages of high controllability, fast deposition rate, and low contamination. Despite the excellent performance of MPCVD reactors in various aspects, the question of how to increase the plasma size while improving its homogeneity remains a challenge for device design and optimization. This paper proposes a method to expand the geometrical sizes of the TM₀₁-mode MPCVD reactor while maintaining the mode’s axisymmetric homogeneity. The size-enlarged TM₀₁-mode MPCVD reactor was first designed and optimized with electromagnetic simulations. A multiphysics model that accounted for the microwave field, hydrogen gas discharge, and energy conservation was proposed to evaluate the performance of the MPCVD reactor afterwards. The results demonstrate that the size-enlarged MPCVD reactor can generate a plasma sphere with a diameter of 4 inches while still maintaining TM₀₁-mode single-mode transmission, either with or without plasma. Its outstanding robustness and adaptability underlie excellent potential for large-area diamond thin-film deposition. Full article

Urban environments face heightened seismic risks due to dense infrastructure and population concentration. Traditional seismic methods often face significant practical limitations in cities due to space constraints, traffic disruption, and acoustic noise, necessitating reliable alternative geophysical approaches for fault screening. This study evaluates the efficacy and practical utility of the opposing-coils transient electromagnetic method (OCTEM) as an effective alternative to conventional seismic techniques for detecting shallow-fault-like resistivity signatures under complex urban electromagnetic noise. By employing dual coaxial coils with opposing currents, the OCTEM suppresses primary-field interference, enabling high-resolution imaging of subsurface structures at depths of 0–200 m. A case study in Tiancheng Chengyuan, Cangzhou City, China, demonstrates the OCTEM’s capability to reliably delineate stratigraphic interfaces and resistivity anomalies under challenging electromagnetic background conditions. Field data exhibited a mean square relative error of 4.01%, validating its data quality and measurement stability. The survey successfully identified stratigraphic continuity and localized heterogeneity features within the investigation zone. These results establish the OCTEM as a robust and efficient tool for urban fault screening, particularly in environments where traditional high-resolution seismic methods are impractical or economically unfeasible. Full article

The Schumann resonance (SR) signal has attracted much attention as a potential earthquake precursor indicator. To enable rapid identification of these signals from massive volumes of China Seismo-Electromagnetic Satellite (CSES) data, this paper presents a machine learning-based image recognition algorithm. Firstly, the Ultra-Low Frequency (ULF) band power spectrum data of the ionospheric electric field was standardized to enhance the visual contrast of the signal and generate a spectrogram. A small-image dataset with standardized image size and labeled positive and negative samples was constructed by cropping the original images. High-dimensional features of the image were extracted using the deep convolutional neural network VGG16 algorithm, combined with the support vector machine (SVM) algorithm to classify whether the high-dimensional data contains SR signals. The sliding window recognition algorithm is designed to process large-format power spectrum images. The results showed that this VGG16-SVM hybrid model achieved an accuracy of 95.00% on the independent small-image test set, which was superior to both pure SVM and pure VGG16 models. On the large-format image prediction set, the overall accuracy of the model is 81.48%, and the SR physical properties of the recognition signal are verified through frequency statistics. The hybrid model was applied to the SR detection and recognition of the Yangbi earthquake in Yunnan, China, and achieved ideal results. This indicates that the proposed VGG16-SVM hybrid model can quickly and effectively identify SR signals in CSES data, which has important practical value for automated electromagnetic signal analysis in seismic research. Full article

Fe-based amorphous microwires were studied to examine the effect of partial surface nanocrystallization on their magnetic and electrical properties. Controlled annealing was used to induce nanocrystallization within the surface layer of the metallic core. The giant magnetoimpedance (GMI) was found to increase up to 150% compared to the as-cast microwires, which correlates with variations in the electromagnetic skin depth. Magnetic force microscopy (MFM) revealed a pronounced transformation of the magnetic domain structure: inclined and zigzag domains evolved into a ring domain configuration with radially oriented magnetization. This transformation of the domain structure occurred within the same magnetic field range where the maximum impedance response was observed. These results show a strong coupling between surface nanostructuring, domain configuration, and magnetoimpedance behavior, providing insights for optimizing Fe-based microwires for use in high-sensitivity magnetic and mechanical sensors. Full article

Terahertz (THz)-based metasurface biosensors have garnered considerable interest owing to their strong electromagnetic (EM) resonance-based sensing methods. Nonetheless, the majority of published designs exhibit constrained optical transparency and angular sensitivity, hence limiting their integration with optoelectronic systems and reducing sensing reliability at oblique angles. This study introduces a graphene-based optically transparent terahertz metasurface that demonstrates wide-angle stability for biosensing applications to address these challenges. The proposed metasurface utilizes a patterned graphene resonator integrated with an optically transparent silicon dioxide (SiO₂) dielectric substrate and a conductive indium–tin–oxide (ITO) ground configuration, enabling efficient THz absorption at the resonant frequency while maintaining optical transparency. Due to its structural symmetry, the suggested structure exhibits polarization insensitivity and angular stability up to 60° for both transverse electric (TE) and transverse magnetic (TM) modes. Furthermore, the comprehensive operating mechanism is explained by impedance matching theory, surface current distribution, and analysis of electric field distributions. A thorough numerical analysis of the proposed metasurface was conducted by incorporating analytes with varying refractive indices using CST Microwave Studio, demonstrating its effective sensing capabilities, with a sensitivity of 0.69 THz/RIU and a quality factor of 24.67. A comparative examination with existing designs reveals that the proposed device, due to its optical transparency, angular stability, and high sensitivity, demonstrates significant potential for terahertz biosensing applications. Full article

This paper presents a systematic numerical investigation of a hybrid plasmonic–photonic Panda-ring antenna with an embedded gold grating, designed to enable efficient dual-mode radiation for optical and terahertz communication systems. The proposed structure integrates high-Q whispering-gallery mode (WGM) confinement in a multi-ring dielectric resonator with plasmonic out-coupling at the metal–dielectric interface, allowing controlled conversion of resonantly stored photonic energy into free-space radiation. The electromagnetic behavior is analyzed through a hierarchical structural evolution, progressing from a linear silicon waveguide to single-ring, add–drop, and Panda-ring resonator configurations. Gold is modeled using a dispersive Drude formulation with complex permittivity to accurately capture frequency-dependent plasmonic response at 1.55 µm. Power redistribution within the resonator system is described using coupled-mode theory, with coupling and loss parameters evaluated consistently from full-wave numerical simulations. Full-wave simulations using OptiFDTD and CST Studio Suite demonstrate that purely photonic resonators exhibit strong WGM confinement but negligible radiation, while plasmonic gratings alone suffer from low efficiency due to the absence of coherent photonic excitation. In contrast, the proposed hybrid Panda-ring antenna achieves stable and directive far-field radiation under WGM excitation, with a realized gain of approximately 8.05 dBi at 193.5 THz. The performance enhancement originates from synergistic hybrid SPP–WGM coupling, establishing a WGM-driven radiation mechanism suitable for Li-Fi and terahertz wireless applications. Full article

This paper mainly conducts research on the electrode distribution of the multi-electrode electromagnetic flow measurement system. Through simulation work, the weight function of the area to which the electrodes on the pipeline cross-section belong with respect to the potential difference is roughly obtained. Moreover, by comparing the simulation data with the actual experimental data, the correctness of the simulation work is verified. Tikhonov regularization is utilized to inversely solve the average velocity of the electrode area, and the TR-CNN algorithm is established to refine the velocity field of the pipeline cross-section in question. It mainly introduces the influence of different electrode placement methods on the potential difference. The results show that it has a relatively small impact on the velocity distribution of the fluid cross-section before flowing through the elbow, and the potential difference is highly sensitive to the velocity in the area where the magnetic induction coil and the electrodes are relatively close. The Pitot tube is used to conduct verification measurements on the fluid velocity field in the pipeline. The results indicate that as the measurement points are farther away from the elbow, the “skewing” phenomenon of the fluid flow velocity gradually weakens. In terms of prediction performance, the mean square error (MSE) of the cross-section error is approximately 0.015, and the mean absolute error (MAE) is about 0.095. These error indicators jointly demonstrate that the system has a relatively high measurement accuracy in practical applications. Full article

The achievements of regenerative medicine are based on methods of controlling stem cell division and differentiation. Electromagnetic fields stimulate cell differentiation by means of affecting calcium channels and cellular signaling. However, only a small part of the mechanisms underlying electromagnetic field effect on cells has been studied. The prospect of their use in tissue engineering as an addition or alternative to biochemical effects becomes clear in the course of numerous experiments. Electromagnetic stimulation enhances the effect of biochemical differentiation inducers and can cause the secretion of exosomes of special properties, which may serve as a therapeutic tool. For example, it has been shown that EMFs at 15 Hz and 2 mT increased the expression of chondrogenic differentiation markers SOX9 and COL2 in human bone-marrow MSCs by up to 3-fold (based on Parate et al.). Optimizing EMF parameters (e.g., 15–50 Hz, 1–2 mT) for specific cells and pathologies remains a key challenge of the studies in the field of tissue engineering. This review describes the electromagnetic field effect on the chondrogenic and osteogenic differentiation of MSCs of various origins, which is important for the musculoskeletal tissue recovery, as well as on inflammatory diseases in model animals. Full article

Microwave sintering technology is widely regarded as one of the most promising construction techniques for in situ resource utilization in lunar bases due to its high energy efficiency and unique heating mechanism. However, the extremely low-temperature environment on the lunar surface creates a transient temperature gradient of over a thousand degrees Celsius between the sintered body’s surface and its interior. This temperature difference induces significant thermal stress during the cooling process, leading to macroscopic surface cracks and even structural failure, which severely limits the engineering feasibility of this technology. To evaluate the surface integrity of lunar in situ sintered bodies and determine the safe processing window for microwave sintering, this study develops a multiphysics computational model that couples electromagnetic, thermal, and stress fields. The results show that when the cooling rate is below 15 °C/min, the surface stress remains below the material’s tensile strength threshold, effectively preventing crack formation. However, at a cooling rate of 16 °C/min, the surface stress exceeds this threshold, leading to crack initiation. Further analysis reveals that the cooling rate significantly affects the microstructure, with slow cooling maintaining a dense structure, while fast cooling promotes the formation of microcracks, particularly in regions with low Si/Al content. This study provides a reference for the microwave sintering process of lunar regolith and proposes a strategy of controlling the cooling rate below 15 °C/min. Full article

Electromagnetic shielding (EMS) materials play an important role in modern technology and industry, especially in electronic equipment, communication technology, military applications and so on. With the continuous progress of technologies and the increasing demands for functional materials, EMS materials are expanding towards flexibility and being lightweight. Recently, metal–organic frameworks (MOFs) have garnered significant attention in the EMS field due to their unique structure and adjustable properties. In this paper, alloy-based porous nanospheres (CCZ-C) were fabricated by heat-treatment using CoCuZn-MOFs as precursors, and then electrospun CCZ-C/PVDF nanofiber membranes (NFMs) were prepared in a large-quantity by blending them with PVDF. Afterwards, a hierarchical porous structured NFM (MPPA) was obtained by loading a highly conductive Ag nanolayer on the surface of CCZ-C/PVDF nanofibers using pDA as a binder. By adjusting the CCZ-C content, it was determined that the EMS performance of MPPA was highest when the CCZ-C content was 2 wt.%, with an average SSE of 12,017.01 dB·cm²·g⁻¹. This was because the hierarchical porous structure formed by adding an appropriate amount of CCZ-C further improved the electromagnetic attenuation and impedance matching of MPPA. Full article