Search Results (360)

In this study, we prepared a magnetic University of Oslo-66 (UiO-66) composite material, Fe₃O₄@SiO₂@UiO-66, and applied it as an adsorbent for the effective removal of benzoic acid from wastewater. The resulting magnetic MOF composite retained the structural and property characteristics of MOFs, along with magnetic separation capabilities, allowing for swift recovery from water through external magnetic fields. A potential synergistic effect between magnetic particles and UiO-66 was observed, leading to enhanced benzoic acid adsorption. The adsorption capacity per Zr₆ cluster unit in Fe₃O₄@SiO₂@UiO-66 measured 569.5 g/mol, surpassing that of UiO-66 by more than 26%. We conducted investigations into adsorption properties as a function of initial concentration, contact time, and pH values. The adsorption of magnetic UiO-66 composites was well described by pseudo-second-order and Langmuir models, indicating predominant chemisorption on the homogeneous surface. Thermodynamic studies of adsorption revealed a spontaneous exothermic process. Furthermore, we analyzed possible mechanisms of benzoic acid adsorption, highlighting the contributions of electrostatic interactions, coordination interactions, and π–π stacking interactions. Magnetic UiO-66 exhibited remarkable adsorption capacity, along with reliable regeneration performance and convenient magnetic separation capabilities, making it an exceptional adsorbent for industrial applications in the removal of benzoic acid. Full article

With increasing rail traffic intensity, reliable detection of shallow subsurface rail damage is essential for operational safety. This critical narrative review evaluates non-destructive testing technologies relevant to defects whose active crack front or principal scattering zone lies within the upper approximately 0.5–10 mm of the rail, while treating the 10–15 mm range as a transition to deeper-defect verification. Magnetic flux leakage, magnetic particle inspection, visual inspection, eddy current testing, and conventional ultrasonic testing are first examined as screening or confirmatory comparators. The review then focuses on four ultrasonic surface-wave excitation routes—contact piezoelectric, active air-coupled, electromagnetic acoustic, and laser ultrasonic—and distinguishes source-specific laboratory capability from demonstrated field evidence. Because the cited studies use different defect geometries, rail conditions, sensor configurations, speeds, and decision criteria, their numerical values are reported as source-conditioned evidence rather than as a normalized ranking. An engineering decision matrix links defect depth and size, inspection speed, surface condition, and noise environment to a recommended screening–confirmation workflow. The synthesis identifies contact piezoelectric UT/PAUT as the most mature quantitative confirmation route, while EMAT, air-coupled UT, and laser UT retain method-specific advantages but require stronger natural-defect and in-service validation. Full article

Retained water associated with water-locking can restrict gas production in heterogeneous tight sandstones, and the activity and phase stability of many surfactant treatments are reduced under high-temperature, high-salinity (HTHS) conditions. In this study, a composite surfactant formulation, CSF-1, designed to lower gas–brine capillary resistance and adjust sandstone wettability under representative reservoir constraints, is reported. Its performance was evaluated using thermal aging, surface tension and contact angle measurements, geochemical compatibility tests, laser diffraction, SEM/EDS, and core flooding combined with stagewise low-field nuclear magnetic resonance (LF-NMR). CSF-1 remained macroscopically homogeneous after aging at 170 °C in 188.314 g/L hypersaline brine and retained low gas–brine surface tension when measured at 25 °C after aging. In core flooding tests, CSF-1 increased the apparent gas permeability from 0.203 to 0.388 mD relative to the SFW-saturated water-locked state, corresponding to a 91.1% improvement. One- and two-dimensional NMR measurements provided comparative relaxation domain evidence that CSF-1 promoted the removal and redistribution of relatively mobile and weakly restricted fluid signals and reduced residual signal clustering. The shortest T₂ relaxation domains were less affected. The absence of replicate core flooding and associated LF-NMR runs, together with the non-equivalent Ref-S comparison, precludes a statistically rigorous cross-agent performance ranking. These results support the laboratory water-locking mitigation potential under the tested conditions, without implying calibrated pore-size-resolved removal or field-scale confirmation. Full article

Accurate assessment of shale wettability is crucial for optimizing fracturing design and enhancing shale gas recovery. However, conventional evaluation methods are often unreliable due to shale’s complex mineral composition and heterogeneous pore structure. This study investigated marine shale from the Sichuan Basin by establishing a multi-scale research framework that integrates macro-scale spontaneous imbibition evolution, micro-scale dynamic video observation, and interfacial property characterization. Using techniques including X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and deep-field microscopy, we investigated the water distribution patterns and imbibition mechanisms. The results indicate that the mixed-wettability characteristics of shale are governed by the synergistic effects of mineral composition and pore structure. Specifically, hydrophilic surfaces facilitate stable adsorbed water film formation via hydrogen bonding and van der Waals forces, whereas hydrophobic surfaces inhibit water spreading. At the macro-scale, a distinctive “water ring” was observed immediately upon immersion. This phenomenon reveals a physical correlation between the mass per unit length of the water ring and the contact angle at the gas–solid–liquid interface. Based on this correlation, an innovative standard curve method was developed to evaluate rock wettability. This method allows for the inversion of the apparent contact angle by simply measuring the mass per unit length of the water ring, thereby overcoming the limitations of traditional optical methods that are constrained by surface roughness and pore structure. Consequently, a logical chain of “wettability → occurrence characteristics → imbibition patterns” was established. This work provides new insights and theoretical support for understanding fluid dynamics and optimizing fracturing fluids in unconventional reservoirs. Full article

Conventional water treatment relies on sequential flocculation and disinfection, which inflates infrastructure costs and heightens the risk of disinfection byproduct formation. Here, we report a magnetic lignin-based flocculant (LS-DMC-AM@Fe₃O₄) that integrates flocculation, sterilization, and rapid magnetic separation within a single material. The composite was synthesized by thermally initiated graft copolymerization of methacryloyloxyethyl trimethylammonium chloride (DMC) and acrylamide (AM) onto sodium lignosulfonate (LS), followed by incorporation of Fe₃O₄ nanoparticles (NPs) at 15 wt% loading; the product exhibited a saturation magnetization of 12.8 emu g⁻¹. LS-DMC-AM@Fe₃O₄ achieved 98.2% kaolin turbidity removal at 1 mg L⁻¹ and 98.6% E. coli removal at 8 mg L⁻¹, and displayed a markedly broader effective dosage window than its non-magnetic analog. We attribute this broadened window to Fe₃O₄-enhanced membrane disruption, which liberates anionic intracellular contents that buffer excess cationic charge and thereby suppress restabilization. The bactericidal efficiency reached 90% at 18 mg L⁻¹, 1.6-fold higher than LS-DMC-AM, governed by a synergistic dual mechanism: quaternary ammonium contact-killing coupled with Fe₃O₄ NP-induced intracellular reactive oxygen species (ROS) accumulation. Under an external magnetic field, flocs underwent rapid phase separation and displayed enhanced shear-regrowth capacity (E. coli floc recovery factor: 53% vs. 26%); Fe₃O₄ NPs were recovered at >95% efficiency over two cycles. Despite higher unit production costs, LS-DMC-AM@Fe₃O₄ delivers competitive per-unit-volume treatment economics through its ultralow effective dosage and magnetic seed recyclability. These results establish a viable strategy for engineering multifunctional, recyclable flocculants from industrial lignin waste. Full article

Petrophysical characterization of rocks is essential for the reliable interpretation of gravity and magnetic fields in ore districts where sedimentary, volcanogenic, and intrusive rocks occur in complex structural relationships. This study uses a database comprising 643 bulk-density determinations and 650 magnetic-susceptibility determinations obtained from drill-core and hand-specimen samples from the southeastern part of the Sarysu–Teniz uplift, Central Kazakhstan. In this study, these measurements are presented and interpreted in an aggregated form by the main lithostratigraphic and lithological groups; for each group, the number of determinations, weighted-average values, and diagnostic petrophysical characteristics are reported. The unit-level weighted-average density values range from 2.14 to 2.73 g/cm³, whereas mean magnetic-susceptibility values vary from 0 to 913 × 10⁻⁵ SI. Carbonate-dominated units, including limestones, marls, dolomites, and dolomitized limestones, are non-magnetic to practically non-magnetic, mostly at 0–14 × 10⁻⁵ SI. The highest values are recorded in andesite-basalts and quartz syenite porphyries, reaching 766–913 × 10⁻⁵ SI; granodiorites have an average value of approximately 452 × 10⁻⁵ SI. Density values partly overlap between sedimentary and intrusive rocks, especially within the interval range of 2.48–2.66 g/cm³, whereas magnetic susceptibility provides a more reliable criterion for distinguishing carbonate host rocks from magnetite-bearing magmatic assemblages. The combined density–magnetic susceptibility framework indicates that exploration targeting should prioritize bodies with elevated magnetic susceptibility or sharp magnetic gradients, especially where χ > 450 × 10⁻⁵ SI, provided that these features coincide with faults, lithological contacts, practically non-magnetic carbonate host rocks, and independent geochemical evidence or known mineral occurrences. Consequently, magnetic anomalies are interpreted as indirect structural–lithological indicators rather than as direct evidence of ore bodies. Full article

Hall-effect sensors are pervasive in magnetic-field measurement applications, including current sensing and position detection, owing to their excellent compatibility with standard CMOS processes. However, the inherent offset and temperature drift of silicon-based Hall elements remain a paramount obstacle to achieve high precision. This paper presents a fully integrated angle sensor chip that addresses this challenge. Implemented in a 0.35 μm CMOS process, the sensor incorporates four cross-shaped Hall elements arranged in an orthogonal array as a non-contact Hall-permanent magnet configuration, which enables absolute angular encoding across a full 0–360° range. Experimental characterisation demonstrates a low noise floor of 0.087° (3σ), validating the effectiveness of the proposed architecture for high-accuracy angular measurement. Full article

Ferrofluid sealing is an important non-contact sealing technology for ultra-high vacuum (UHV) equipment, but its reliability is affected by more than pressure-bearing capacity alone. This review shows that carrier-liquid evaporation, material outgassing, thermal degradation, magnetic-field distortion, and liquid-ring instability are the main factors limiting UHV ferrofluid seals. Multiphysics simulation and parametric optimization remain the most mature tools for analyzing magnetic-field distribution, pressure resistance, temperature rise, and structural deformation. Data-driven condition identification improves failure monitoring, whereas physics-informed neural networks, topology optimization, and multi-objective optimization are still emerging methods for low-sample prediction and collaborative design. Future studies should focus on low-vapor-pressure ferrofluids, bake-out compatibility, thermal management, lifetime prediction, and integrated model–data design frameworks. Full article

Non-contact magnetic sensing technology is widely adopted in transmission line online monitoring scenarios including current measurement and fault location for its non-contact measurement capability, strong environmental robustness and low deployment cost. However, existing magnetic-sensing-based galloping monitoring methods suffer from two critical limitations: no theoretical guidance is provided for sensor placement, and a high false detection rate is observed under current fluctuation conditions. To address these issues, a novel transmission line galloping monitoring method based on spatial magnetic field distribution features is proposed in this paper. A conductor galloping-power frequency magnetic field coupling model is first established to derive the optimal magnetic sensor array arrangement strategy. Subsequently, a galloping detection algorithm fusing multi-node frequency-domain features and phase difference information is proposed to eliminate current fluctuation induced false detection. Simulations conducted based on actual 500 kV transmission line parameters and verification tests carried out on a scaled-down laboratory platform confirm that reliable galloping detection can be realized by the proposed method under both current low-frequency oscillation and random fluctuation scenarios. With advantages of non-contact deployment, high anti-interference performance and detection accuracy, the proposed method has promising application potential in engineering-oriented high-voltage transmission line monitoring. Full article

Magnetic gears offer an energy-efficient alternative to conventional mechanical gears through magnetic fields rather than physical contact. A non-contact operation eliminates frictional losses, mitigates wear, and reduces vibration, noise and maintenance requirements. In recent years, the development of magnetic gear technologies has accelerated, driven by advances in materials, innovative gear topologies, and emerging applications. This paper presents a comprehensive review of magnetic gear technologies with particular emphasis on their applications in battery electric vehicles and hybrid electric vehicles. First, the development of magnetic gears is reviewed from early converted magnetic analogues of mechanical gears to high-performance field-modulated variable gear designs. The review subsequently examines the use of magnetic gears in electric vehicle applications, including magnetic geared in-wheel motors, traction modules, and magnetic gears in hybrid electric vehicles, such as magnetic variable gears for hybrid vehicle applications, magnetic geared electric variable transmissions and power-splitting devices. The review also discusses novel and less-established MG applications before examining the challenges limiting their widespread adoption in EV and HEV drivetrains. Full article

This paper investigates the magnetization reversal processes in spring-exchange magnetic composites featuring irregular, dendritic structures. A disorder-based cluster Monte Carlo method combined with a Diffusion-Limited Aggregation (DLA) algorithm was used to model a fractal-like soft magnetic phase (Fe) embedded in a high-coercivity hard matrix (Fe-Nb-B-Dy). A multiparameter analysis was performed by varying the soft phase volume fraction (10–30%), intergrain exchange coupling via contact bridges (25–100%), system scale factors (1–20), surface-to-volume anisotropy ratios (K_S/K_V = 1–20), and the degree of random anisotropy contribution (RAC = 0–100%). The simulations reveal that highly branched fractal structures enhance the interfacial contact area, which accelerates the nucleation of domain reversal driven by the soft phase, paradoxically lowering the overall coercivity compared to compact morphologies. Furthermore, a lack of easy magnetization axis coherent alignment triggers a cascading reversal mechanism through local “weak links”, severely degrading the coercive field from approximately 4.2 T to below 0.4 T in extreme cases (at 30% Fe, 25% coupling and high K_S/K_V ratio). These findings suggest potentially the most important factors and their impact that should be taken into account in the design and optimization of next-generation powder-sintered permanent magnets. Full article

Carbon/inorganic hybrid composites have evolved from filler-reinforced materials into design platforms for coupled electromagnetic, thermal, sensing, environmental, protective and energy-related functions. Their distinctive value lies in the possibility of combining a conductive, polarizable or porous carbon phase with an inorganic phase that contributes dielectric, magnetic, catalytic, ionic, thermally conductive or barrier behavior. This review examines carbon/inorganic hybrid multifunctional composites from the viewpoint of structure–property relationships, with emphasis on interfacial design, percolation, anisotropy, hierarchical architecture, processing and metrology. Selected graphitic composite studies are discussed as case studies for broadband dielectric spectroscopy, microwave shielding, high-frequency contact metrology, thermal diffusivity analysis and impedance-monitored graphene filters; these case studies are integrated with the broader international literature on CNT and graphene polymer composites, MXene films and foams, graphene/metal oxide photocatalysts, boron nitride/carbon thermal networks, biochar–graphene adsorbents, smart coatings, sensors, supercapacitors and water remediation systems. The central argument is that credible multifunctionality requires more than measuring several properties on the same material. It requires simultaneous or service-relevant co-optimization under constraints of thickness, density, processability, aging, humidity, corrosive media, regeneration, toxicity, economic feasibility and scalable fabrication. The review concludes with design rules and reporting recommendations intended to help move the field from impressive property demonstrations toward application-ready hybrid material systems. Full article

Surface defects in additively manufactured internal channels limit their practical applications. Conventional post-processing methods suffer from limited accessibility and a tendency toward over-polishing, whereas magnetic abrasive finishing (MAF) offers high adaptability and precise process controllability. This study systematically investigates the material removal mechanisms in magnetic abrasive polishing and clarifies the distinctions and transitions between two-body and three-body wear modes. Based on these findings, a rolling removal model grounded in rough surface contact theory and a sliding removal model incorporating correction factors are established. Experiments were conducted on AlSi10Mg internal channels fabricated via selective laser melting (SLM) using a composite magnetic field polishing apparatus. The results verify the accuracy of the proposed models and demonstrate that the process effectively reduces surface defects and surface roughness. Although some deviations arise from model idealization and non-uniform magnetic field distribution, this study establishes a systematic theoretical framework for material removal in additively manufactured complex internal channels. Full article

Magnetically actuated catheters have attracted increasing attention for minimally invasive interventions because they enable remote, non-contact steering in confined and tortuous anatomical environments. However, integrating magnetic actuation, electroablation capability, and high structural compliance into a single soft catheter remains challenging. Here, we present a coaxially printed magnetically actuated electroablation catheter (MEC). The MEC is fabricated via a coaxial 3D printing process, combining a highly flexible PDMS outer sheath with a continuously deformable eutectic gallium–indium (eGaIn) conductive core, followed by the distal assembly of a magnetic ring and a copper electrode. This structural design preserves intrinsic mechanical flexibility while maintaining stable electrical conductivity under bending deformation. To achieve active catheter steering, an eight-axis electromagnetic actuation system was developed to generate controllable magnetic fields for tip deflection and guidance. The MEC exhibited effective navigation and manipulation in maze traversal and selective navigation within a 3D-printed vascular model. Furthermore, ex vivo porcine liver and in vivo rat liver electroablation experiments verified that the MEC could be magnetically navigated to designated sites for localized electroablation. This work provides a new strategy for precise, minimally invasive ablation of target tissues in confined and difficult-to-access anatomical environments. Full article

The presence of metals and microplastics in the water environment is a threat to the environment and human health. The development of analytical strategies to remove both pollutants simultaneously is very important. Iron-based adsorbents are environmentally friendly and have a high capacity to remove pollutants from the environment. In this work, Fe₃O₄ magnetic nanoparticles were applied to eliminate microplastic polyethylene from water and, because of the capacity of MPs to absorb metals, lead and arsenic were simultaneously removed in a single step. All experimental conditions were optimized to achieve the highest removal efficiency of the three pollutants. The optimal experimental parameters were 210 min of contact time at room temperature and pH 7 using Fe₃O₄ NPs as an adsorbent, achieving removal efficiencies of 98% of PE-MPs, 80% of Pb(II) and 96% of As(III). Although the adsorption steps occur sequentially—first the adsorption of Pb(II) and As(III) onto the surface of the PE-MPs, followed by the magnetic capture of the metal-loaded microplastics using Fe₃O₄ nanoparticles—the proposed methodology achieves the simultaneous removal of all three pollutants in a single magnetic separation step. The thermodynamics of the process were characterized, revealing a spontaneous Langmuir-type physisorption, and the adsorbents were characterized before and after the removal process by employing field-effect scanning electron microscopy and energy-dispersive X-ray spectroscopy. Full article