Search Results (242)

The rapid advancement of information technology and pervasive use of electronic devices has exacerbated electromagnetic radiation pollution and interference, driving the demand for lightweight, flexible, and high-efficiency electromagnetic shielding materials in materials research. As a high-performance elastomer, thermoplastic polyurethane (TPU) possesses excellent elasticity, wear resistance, oil resistance and processability, making it promising for flexible electronics and wearable devices. However, pure TPU is electrically insulating and exhibits nearly no electromagnetic shielding capability, which requires conductive filler incorporation for functional modification. Herein, ternary TPU/MWCNT/BiFeO₃ composites were fabricated via solution blending and hot pressing, using multi-walled carbon nanotubes (MWCNTs) and bismuth ferrite (BiFeO₃) as conductive and dielectric fillers within the TPU matrix. The effects of filler content on the microstructure, thermal stability, mechanical properties and electromagnetic shielding performance of composites, together with the relevant mechanisms, were systematically studied. For the ternary TPU/MWCNT/BiFeO₃ system, the introduction of BiFeO₃ continuously increases the char residue rate of the composites to 16.01%, while accelerating the reaction process during the main thermal decomposition stage. The mechanical properties gradually deteriorate with the increase in BiFeO₃ content, and the composite with 5 wt% BiFeO₃ almost loses its elastomeric characteristics. The electromagnetic shielding effectiveness (SE) presents a trend of initial increase and subsequent decrease. The composite with 3 wt% BiFeO₃ exhibits the optimal shielding performance, with a 24.7% enhancement in total SE compared with the reference TPU/MWCNT composite containing 1% MWCNT. This improvement is attributed to the interfacial polarization and dipole polarization induced by the appropriate amount of BiFeO₃, which effectively strengthen the electromagnetic wave absorption loss capacity of the composites. Full article

With rapid development of 5G/6G communication and high-power electronic devices, electromagnetic interference (EMI) shielding textiles are urgently required to mitigate electromagnetic pollution. Traditional metallic shielding suffered from heavy weight, poor corrosion resistance, and secondary electromagnetic reflection, while continuous basalt fibers (CBFs) exhibit excellent mechanical strength, lightweightness, thermal/chemical resistance, and electrical insulation, which makes CBFs ideal substrates for EMI devices. Herein, a multifunctional waterborne polyurethane (WPU) sizing agent (coating emulsion) integrated with Mn-Zn spinel ferrite was developed for in situ lubrication on the as-spun CBFs. The composite sizing agents consisted of a WPU matrix, water-soluble epoxy, mineral oil lubricant, CTAB surfactant, KH-570 coupling agent, and micro-sized Mn-Zn ferrites. Characterizations including particle size distribution, thermogravimetric analysis, water contact angle (WCA), water absorption, FTIR, XRD, and SEM were conducted to verify uniform anchoring of ferrites on the CBF surfaces. Increasing ferrite dosages induced slight particle aggregation, elevated surface hydrophobicity (WCA = 42.4° → 99.43°), and reduced water absorption (65% → 35%), which greatly improved the moisture resistance of the CBFs. The X-band EMI shielding tests revealed that the total shielding effectiveness (SET) of modified CBF fabrics increased from 0.11 dB (pristine fiber without ferrite) to 58.57 dB at a loading of 8.0 g/L ferrite. The absorption loss (SEA) dominated the shielding performance over reflection loss (SER). The low-to-moderate contents (1.5–3.0 g/L) of ferrite achieved ultra-high absorption, while higher ferrite loading (5.0–8.0 g/L) intensified the impedance mismatch and enhanced surface reflection. This work establishes a scalable fabrication of absorption-prioritized lightweight CBF shielding, which provides a feasible pathway for flexible EMI shielding textiles. Full article

The rapid development of wireless communication technologies and electronic devices has intensified electromagnetic interference (EMI) pollution, creating an urgent demand for lightweight and efficient shielding materials. In this work, RSF/PVA/MXene composite aerogels with ordered lamellar structures were fabricated by directional freeze-drying. Directional freeze-drying generated an ordered lamellar architecture, while RSF and PVA facilitated the homogeneous distribution of MXene nanosheets within the aerogel framework. Among the investigated samples, RPM-60 exhibited the maximum shielding effectiveness at 12.4 GHz, corresponding to a shielding efficiency of 99.45%, demonstrating the favorable MXene content for efficient EMI shielding at this frequency. The enhanced shielding performance was mainly attributed to the ordered lamellar structure, which promoted multiple internal reflections, together with conductive loss and interfacial/dipole polarization induced by MXene. These results demonstrate the potential of RSF/PVA/MXene composite aerogels as lightweight bio-based EMI shielding materials. Full article

In recent decades, due to the rapid development and application of wireless communication, flexible electronics, and smart devices, electromagnetic interference (EMI) and radiation pollution have been intensified, creating an urgent demand for efficient EMI shielding materials. Carbon nanostructures such as graphene and carbon nanotubes are considered promising candidates due to their excellent properties, such as high electrical conductivity, low density, large specific surface area, and flexibility. This work reports our recent results in the design and testing of polymer nanocomposites with irradiated hybrid carbon nanostructure (graphene/multi-walled carbon nanotubes) used as EMI shielding materials. Five representative composites with varying filler loadings (AH of 15% and AM1 of 20 wt%), thicknesses (0.208–0.48 mm), and e-beam irradiation doses (from 50 to 400 kGy) were systematically characterized using SEM, FTIR, TGA/DSC, and vector network analyzer (VNA) measurements in the S-band (2.65–3.90 GHz). The effects of different e-beam irradiation doses and hybrid carbon contents on conductive network construction, interface engineering, and porous or layered structures on EMI shielding performance are discussed. Experimental results show that all studied composites exhibited strong absorption-dominant behavior (SE_A), while the multiple reflection component (SE_M) was found to be negligible. Both filler loading and sample thickness significantly enhanced shielding performance, with a pronounced synergistic interaction observed between these parameters. A quadratic Response Surface Methodology (RSM) model was developed to correlate the total shielding effectiveness (SE_T) with thickness and filler content, yielding high predictive accuracy (R² > 0.96). The model enables efficient optimization of composite design for targeted shielding levels. Full article

The expansion of wireless infrastructure has made anthropogenic non-ionizing electromagnetic fields (EMFs)—commonly described in public discourse as “electrosmog” or electromagnetic pollution—a pervasive feature of digitalized environments. This study examines how 81 pre-service science teachers in Türkiye conceptualized EMF-related sources, perceived risks, mitigation measures, and responsibility. A multi-source qualitative design combined inductive content analysis of nine open-ended questionnaire items with a document-informed deductive mapping based on authoritative EMF-exposure and risk-governance documents. The integrated framework distinguished diagnostic and risk-appraisal capacity, receiver–pathway–source intervention levels, governance and collective capacity, and responsibility attribution. Within a questionnaire primarily oriented toward awareness and daily-life action, responses concentrated strongly on receiver-level behavioral adaptation and attributed responsibility mainly to individuals and households. Source-level controls, monitoring, compliance, institutional responsibility, and evidence-based risk communication were not spontaneously articulated. Because these dimensions were not directly prompted, the findings do not establish a governance-literacy deficit; they define the boundaries of the mitigation repertoire elicited and generate a hypothesis for future research using explicit institutional and governance-oriented prompts. The study’s contribution lies in applying an integrated exposure-management and responsibility-attribution framework to an understudied teacher-education population and identifying curriculum needs concerning evidence appraisal, multilevel responsibility, and uncertainty-sensitive risk communication. Full article

The development of lightweight multifunctional materials integrating electromagnetic interference (EMI) shielding, Joule heating and flame retardancy is highly demanded for advanced electronics and aerospace systems. Herein, we fabricate graphene/Fe₃O₄@hollow glass microsphere (G/Fe₃O₄@HGM) composite foam with an ultralow density of 0.36 g/cm⁻³. The porous structure synergizes graphene’s conductivity, Fe₃O₄’s magnetism and HGM’s low thermal conductivity to optimize impedance matching. The foam delivers absorption-dominated EMI shielding with a maximum X-band shielding effectiveness (SE) of 60.1 dB and an average absorption coefficient of 0.56, which effectively suppresses secondary electromagnetic reflection pollution. The composite exhibits stable voltage-controllable Joule heating: the 25 wt% Fe₃O₄@HGM sample reaches 91.3 °C at 16 V, enabling rapid de-icing within 200 s and stable thermal maintenance at −20 °C. Flame tests confirm no combustion or structural collapse under open flame. This work provides a simple fabrication strategy for lightweight multifunctional materials applicable to aerospace stealth, electronic thermal management and anti-icing systems. Full article

Geogenic processes and human activities are both major causes of soil pollution. Soils can get toxic transition metals from the materials they are formed from, but most pollution comes from industrial and farming activities. The presence of these transition metals in soil can be shown through changes in chemical, biochemical, and microbial properties, as well as how plants react. This research aims to remove transition metals like chromium (Cr), manganese (Mn), iron (Fe), zinc (Zn), tungsten (W), and cadmium (Cd) from soil using a boron nitride (BN) nanocage. The electromagnetic and thermodynamic properties of these metals when trapped in BN were studied using materials modeling. The metals are captured through chemisorption. The research looked at how Cr, Mn, Fe, Zn, W, and Cd are trapped by BN to detect soil metal cations. BN was designed in the presence of these transition metals. The covalent characteristics of these complexes show similar energy levels and a view of the partial density of states between the p states of boron and nitrogen in BN and the d states of Cr, Mn, Fe, Zn, W, and Cd in B(X)N complexes. Also, nuclear magnetic resonance (NMR) analysis showed clear peaks around Cr, Mn, Fe, Zn, W, and Cd when they were trapped in BN during atomic detection and removal from soil, although there were some variations in chemical shielding for isotropic and anisotropic tensors. Based on these results, the ability of BN (as an atom sensor) to adsorb toxic metals, metalloids, and nonmetals is ordered as: Cd > Zn > Fe > Cr > Mn ≈ W. This article suggests that elements absorbed by BN could be used to develop and improve the optoelectronic properties of BN, helping to create photoelectric devices for soil cleaning. Full article

With the pervasive deployment of 5G communication systems and electronic devices, electromagnetic (EM) pollution has emerged as a critical environmental concern. Due to their wide availability, low cost, and ease of acquisition, biomass materials have been widely used in the preparation of electromagnetic wave absorption materials. Compared with traditional in situ impregnation methods, this study first employs chemical reagents to reduce the lignin content within balsa wood, thereby opening more pores and enhancing the loading capacity of iron salts. Subsequently, magnetic Fe₃O₄ particles are synthesized in situ, enabling the fabrication of magnetic wood-based composites. Compared with the non-impregnated pure carbonized samples, the reflection loss value of the samples with magnetic particles increased to −42.37 dB, corresponding to a matching thickness of 1.5 mm. This is much better than the −8.79 dB of the pure carbonized samples, and is attributed to multiple loss mechanisms. In addition, modern physical and chemical analysis instruments such as SEM, TEM, XRD, XPS, and Raman were used to characterize the physical and chemical changes of the materials. Finally, its applications in aerospace and thermal response were identified. Full article

Electromagnetic interference (EMI) shielding materials are critical for reducing EMI pollution and enhancing information security. This study presents a systematic comparison of silver-plated copper (Cu@Ag; flake-like morphology; the average particle size D50 = 20.1 μm) and silver-plated aluminium (Al@Ag; spherical morphology; D50 = 47.5 μm) fillers with distinct morphologies incorporated into silicone rubber matrices via Rheomixer blending, open-mill compounding, and peroxide vulcanisation. This work aims to elucidate how filler morphology and multilayer sandwich architecture govern shielding efficiency and related material properties. The flake-like Cu@Ag fillers demonstrated superior low-loading performance. Due to their high aspect ratio and enhanced interfacial contact, Cu@Ag composites reached a critical loading for practical EMI shielding performance at 150 phr. In contrast, spherical Al@Ag fillers required a higher loading of 200 phr to achieve the same effect. Both composites achieved EMI shielding effectiveness exceeding 90 dB at 250 phr filler loading across the X-band frequency range (8.2–12.4 GHz). Innovatively, sandwich-structured composites were fabricated by combining Cu@Ag and Al@Ag layers through co-vulcanization, achieving approximately 110 dB shielding effectiveness, which is a ~33% improvement over single-layer composites at equivalent filler loading (200 phr). Analysis of the shielding mechanisms reveals that this enhancement results from multiple electromagnetic wave interactions, including increased reflection losses at morphologically distinct layer interfaces and enhanced absorption through conductivity gradients. This work demonstrates that a rational combination of flake-like and spherical fillers with contrasting morphologies and conductivity characteristics in multilayer architectures provides a powerful strategy for developing high-performance flexible EMI shielding materials. Full article

This study aims to build a spatial model for selecting the optimal site for a radio astronomy observatory in southern Jordan. Geographic Information Systems (GISs) and Multi-Criteria Decision Analysis (MCDA)-based methodology were used in this study to develop a spatial model for choosing the best location for a radio astronomy observatory in southern Jordan. The criteria were weighted using a hybrid framework that combined the Analytic Hierarchy Process (AHP) and the entropy method to account for the actual spatial diversity of the data, in addition to expert judgment. The study assesses site suitability by considering several environmental and logistical factors that mitigate radio frequency interference (RFI), including elevation, cloud cover, artificial light pollution, and accessibility. A final map highlighting the optimal areas for radio astronomy observatories in southern Jordan has been created. The study methodology started with MCDA, and was followed by several stages, including visual evaluation, overlay analysis, establishment of 500 m buffer zones, extraction of the “Very High Suitability” class, and conversion to a transparent vector layer that is free from urban overlap and electromagnetic interference. The results show that the majority of large observatories (10 km²; equivalent to ≥10,000,000 m²) are located in Aqaba and Ma’an, which offer natural isolation and wide expanses ideal for global projects. Medium observatories (0.5–10 km²; equivalent to 500,000–10,000,000 m²) were generally identified at a reasonable cost in Ma’an and Aqaba, with the possibility of radio surveillance and infrastructure expansion. Many small observatories (0.01–0.5 km²; equivalent to 10,000–500,000 m²) were constructed near academic institutions, providing viable, easily accessible places for university research with little regulatory restraints. This research contributes to national astronomy infrastructure planning and serves as a model for other countries experiencing dry or semi-arid climates. It also offers decision-makers a useful spatial database. Full article

With the rapid development of communication technologies, electromagnetic pollution has become increasingly serious, driving the urgent demand for high-performance low-frequency microwave absorbers. This work focuses on Nd-Fe-C powders prepared by high-energy ball milling, aiming to explore low-cost, mass-producible absorbing materials with excellent low-frequency microwave absorption performance. The Nd_10.2Fe_84.6C_5.2 alloy was synthesized via arc melting, and its powders were subsequently fabricated by high-energy ball milling for different milling durations. X-ray diffraction, scanning electron microscopy, and vector network analysis were employed to investigate the effect of high-energy ball milling on the microwave absorption properties of the Nd_10.2Fe_84.6C_5.2 alloy. As the ball milling time increased, the particle size decreased, and the minimum reflection loss shifted to a lower frequency. Additionally, increasing the thickness of the absorbing coating also moved the minimum reflection loss toward the low-frequency region. The Nd_10.2Fe_84.6C_5.2 alloy after 12 h of ball milling had good performance in the C (4.0–8.0 GHz) band when the coating thickness was in the range from 1.4 to 2.2 mm. A minimum reflection loss of −19.2 dB was achieved at 5.2 GHz, and the effective absorption bandwidth (RL < −10 dB, corresponding to a microwave absorption efficiency of 90%) reached 1.8 GHz at a matching thickness of 2.2 mm. Full article

Magnetic graphene composites have emerged as a frontier material platform, offering designable properties and multifunctional integration across environmental, biomedical, electromagnetic, and energy applications. Despite extensive research, a coherent knowledge framework that systematically connects synthesis, structure, property, and application remains lacking. This review addresses this gap by establishing an integrated “synthesis–structure–property–application” design paradigm. We first propose a four-tier evolutionary framework for synthesis strategies, tracing the progression from modular in-situ assembly, substrate-guided single-component in-situ formation, and synchronous in-situ formation to molecular-scale precursor co-conversion. This framework reveals the causative relationships between synthesis pathways and microstructures, and culminates in an application-oriented synthesis decision-making tool that enables rational strategy selection. Building on this synthesis foundation, we systematically analyze three core structural regulation strategies—interface engineering, defect and doping engineering, and hierarchical structure construction—demonstrating how they function as synergistic “control knobs” for tailoring composite properties. Through detailed case studies across four application domains, we quantitatively show how targeted structural design drives performance breakthroughs: enabling high-capacity and selective pollutant removal in environmental remediation; constructing intelligent theranostic platforms in biomedicine; reconciling the “thin, lightweight, broadband, and strong” paradox in electromagnetic interference (EMI) shielding; and ensuring long-cycle stability of high-capacity electrodes in energy storage. Finally, we summarize the paradigm shift from “functional combination” to “performance synergy” and outline future directions, including dynamic intelligent systems, sustainable manufacturing, and data-driven design. This review provides a systematic theoretical framework and practical roadmap for the rational design and on-demand fabrication of MGCs, marking the field’s transition from empirical exploration toward predictive, design-driven science. Full article

Introduction: Aquatic chemical pollution is among the most worrying threats to ecosystem health. There is an ever-increasing variety of pollutant substances detected across the source-to-sea continuum, causing loss of biodiversity and ecological disequilibrium. Achieving cleaner and healthier systems relies on carrying out sustained, cost-effective, diagnosis and aquatic effects monitoring, within the adaptive management cycle. The available methods are, however, cumbersome, which creates a clear need for innovative expeditious approaches for low-cost surveillance monitoring. In the last decade, Raman Spectroscopy (RS) has gained wide recognition for application to biological questions, for its ability to uncover the complexity of molecules and their interactions. Various fields, from pharmacology to disease diagnosis and prognosis, have suffered an innovation revolution through the application of RS. In this technique inelastic light scattering of a small part of photons of an incident electromagnetic monochromatic light beam (ranging from near-infrared to visible or ultraviolet) is caused by the molecular vibration of chemical bonds. This results in shifts in energy, which indicate discrete vibrational modes of polarisable molecules, providing qualitative and quantitative assessments of the chemical composition and molecular structure of the sample. The technique shows high sensitivity, no need for sample preparation and the possibility of use in non-invasive and label-free analysis. Objective: The aim of this work is to present and discuss evidence about the application of Raman Spectroscopy (RS) to environmental diagnosis and aquatic effect monitoring of pollution. Methodology: The technique was applied to different biological models, i.e., diatoms, zebrafish embryos and larvae and freshwater snails. Quality assessments with diatoms were tested in environmental monitoring, while assessments with other models were done upon exposure to metals and organic contaminants. Results and conclusions: The Raman spectra obtained from the samples analysed comprised bands detected within the 800 to 2000 cm⁻¹ wavenumber range. These were related to bond vibrations of carbohydrates, DNA phosphate groups, proteins or CH, NH and OH stretching in lipids and proteins. Data analysis using chemometric methods clearly distinguished pollutant exposure from control sites or treatments, pointing out the potential for surveyance monitoring. The next steps include the comparison with other sensitive methods (e.g., locomotion and avoidance behaviours, omics methods) to assess efficiency and bring further mechanistic understanding. Full article

As the core actuation component of intelligent precision spraying systems, the variable-rate nozzle is essential for achieving on-demand agricultural spraying; improving the use efficiency of water, fertilizers and pesticides; and reducing environmental pollution. This paper systematically reviews the development of agricultural variable-rate nozzles, from early mechanical profiling structures to modern intelligent control technologies based on Pulse Width Modulation (PWM). First, the existing variable-rate nozzles are classified into three major categories: electromagnetic-integrated type, centrifugal type, and variable-diameter type. A comparative analysis is conducted from three dimensions of working principle, performance characteristics and application scenarios, to delineate the respective advantages and limitations of each nozzle category. Second, the paper examines key technological advances in three areas: high-frequency solenoid valves, PWM control, and pressure and flow stabilization. It identifies the nonlinear response of solenoid valves, flow distortion under low duty cycles, and water hammer pressure fluctuation induced by high-speed switching as the three core technical bottlenecks at the current stage. Subsequently, the latest achievements and typical methodologies of variable-rate nozzles in structural design, simulation and experimental analysis are systematically reviewed, and their application performance in scenarios including field crops, orchards, protected agriculture and beyond are summarized. Finally, the remaining open issues in this field are put forward. It is suggested that future research should focus on key breakthroughs in the development of corrosion and wear-resistant high-frequency solenoid valves, the formation mechanism and suppression methods of pressure fluctuation, as well as adaptive algorithms based on machine learning or Model Predictive Control (MPC), to promote the leapfrog development of agricultural variable-rate nozzle technology from single variable control to multi-factor coupling optimization. All references cited in this paper are from articles published after the year 2000. Among them, the literature published in the last decade accounts for 86.6%, and literature published in the last five years accounts for 58.9%. Full article

High-performance electromagnetic wave absorption materials are desperately needed due to the growing serious electromagnetic interference and pollution issues brought on by the quick growth of modern electronic technology and wireless communication. This work uses the organic–inorganic hybrid perovskite MAPbBr_xI_3−x as a model system to address the problem of restricted loss mechanisms and the challenges in changing the absorption bandwidth of single-component wave-absorbing materials. It achieves systematic tuning of electromagnetic wave absorption performance, especially within the effective working frequency spectrum, through accurate halogen site engineering. According to the study, MAPbI₃ (MPI), MAPbBr_1.5I_1.5 (MPIB), and MAPbBr₃ (MPB), which were synthesized using the anti-solvent approach, all demonstrated exceptional microwave absorption capability, with maximum reflection loss values exceeding −37 dB, among which MPB achieves a remarkable value of −42.41 dB at 16.60 GHz. More significantly, this work shows a distinct structure-property relationship between the effective absorption peak frequency range of this series of materials and their band structure: the strongest absorption peak shows a regular blue shift as the material bandgap widens and the bromine content rises. This finding suggests that focused tailoring of the operating frequency band in wave-absorbing materials can be achieved by manipulating the band structure of perovskites by varying the halogen concentration. In addition to confirming the significant application potential of organic–inorganic hybrid perovskites in the field of microwave absorption, this study offers a novel research perspective and material template for precisely and programmably controlling the absorption frequency band of wave-absorbing materials based on their basic electronic structures. Full article