Search Results (8,872)

Enhanced Giant Magneto-Impedance (GMI) effects of composite materials play a crucial role in producing devices with a good soft magnetic property. To improve this soft magnetic property, graphene is introduced to increase the conductivity of composite materials. However, the quality of graphene layers restricts the enhancement of GMI effects. There are few reports on the direct growth of graphene on Fe_73.5Si_13.5B₉Cu₁Nb₃ (FINEMET). In this paper, the composite ribbons of FINEMET coated with as-grown graphene are prepared by chemical vapor deposition (CVD), which is much better than previous results obtained by methods such as the transfer method or electroless plating in quality. The Ni layer, with good magnetic conductivity, is induced to the FINEMET as an auxiliary layer by the magnetron sputtering method for high-quality graphene-layer growth due to its high carbon dissolution rate. The results show that the growth temperature of the as-grown graphene layer on the FINEMET with the best GMI ratio could reach as high as 560 °C. Moreover, it was found that an Ni layer thickness of 300 nm has a crucial impact on GMI, with the maximum ratio reaching 76.8%, which is 1.9 times that of an initial bare FINEMET ribbon (39.7%). As a result, the direct growth of graphene layers on FINEMET ribbons by the CVD method is a promising way to light GMI-based devices. Full article

Excessive stress disrupts cardiac homeostasis via complex and multifactorial mechanisms, resulting in cardiac dysfunction, cardiovascular disease, or even sudden cardiac death, yet the underlying molecular mechanisms remain poorly understood. Accordingly, we aimed to elucidate how stress induces calcium dysregulation and contributes to cardiac dysfunction and injury through the nuclear receptor subfamily 3 group c member 1 (NR3C1)/Glomulin (GLMN)/FK506-binding protein 12.6 (FKBP12.6) signaling pathway. Using mouse models of acute and chronic restraint stress, we observed that stress-exposed mice exhibited reduced left ventricular ejection fraction, ventricular wall thickening, elevated serum and myocardial cTnI levels, along with pathological features of myocardial ischemia and hypoxia, through morphological, functional, and hormonal assessments. Using transmission electron microscopy and Western blotting, we found that stress disrupted mitochondrial quality control in cardiomyocytes, evidenced by progressive mitochondrial swelling, cristae rupture, decreased expression of fusion proteins (MFN1/OPA1) and biogenesis regulator PGC-1α, along with aberrant accumulation of fission protein (FIS1) and autophagy marker LC3. At the cellular level, ChIP-qPCR and siRNA knockdown confirmed that stress activates the glucocorticoid receptor NR3C1 to repress its downstream target GLMN, thereby preventing FKBP12.6 ubiquitination and degradation, resulting in calcium leakage and overload, which ultimately impairs mitochondrial quality control and damages cardiomyocytes. In conclusion, our findings reveal that stress induces myocardial damage through NR3C1/GLMN-mediated FKBP12.6 ubiquitination, disrupting calcium homeostasis and mitochondrial quality control, and lay a theoretical foundation for dissecting the intricate molecular network of stress-induced cardiomyopathy. Full article

During the roasting, leaching, and electrodeposition of zinc ores, lead–silver residues are produced. These residues contain valuable metals (Pb, Zn, and Ag) and toxic metals (Cd and As). In this study, a pyrometallurgical process is proposed for treating Pb-Ag residues, consisting of drying, roasting, and reduction steps to recover valuable metals, such as silver in a metallic Pb phase, while converting the waste into an environmentally friendly slag. First, the Pb-Ag residue is dried at 100 °C, then roasted at 700 °C, and finally reduced at a high temperature, with Na₂CO₃ as a flux and CaSi as a reducing agent, rather than carbon-based reducing agents (carbon or carbon monoxide), to minimize greenhouse gas production. The effects of the reduction temperature and the mass of the reducing agent were investigated on a laboratory scale. The metallic phase and slag obtained in the reduction step were characterized by their chemical composition and mineralogy via chemical analysis, X-ray diffraction, and SEM-EDS. The results showed that silver and lead formed a metallic phase, and that silver content decreased from 1700 ppm in the Pb-Ag residue to 32 ppm in the final slag at 1300 °C. The Pb-Ag residue and final slag were leached with an aqueous acetic acid solution to evaluate their chemical stability. Full article

AlSi10Mg has been one of the most studied and employed aluminum alloys for additive manufacturing via laser powder-bed fusion (L-PBF). The optimization of manufacturing parameters is important for reducing internal defects, including porosity and inadequate surface finishes. In addition, heat treatments, such as T6, are often applied to this alloy, but they degrade the characteristic microstructure obtained via L-PBF additive manufacturing—the fine cellular structures—which may, in turn, detrimentally affect the material’s properties. In this context, a new alternative to this treatment, direct aging (DA), has shown promise in improving the mechanical properties of AlSi10Mg parts produced via L-PBF, since it preserves the cellular microstructure, precipitating silicon-rich nanoparticles within the cells. Understanding how different temperatures and heat treatment times influence the microstructure and, consequently, the properties remains a field to be explored in order to optimize the treatment conditions and achieve better mechanical properties. Thus, the objective of this study was to evaluate the influence of manufacturing parameters and heat treatments on the microstructure and mechanical properties of AlSi10Mg alloy. The optimized manufacturing conditions were 300 W power, 800 mm/s scan speed, 30 µm layer thickness, and an argon atmosphere, which led to lower porosity and better finishing. Samples were heat-treated via DA at 150 °C and 170 °C for different times, as well as undergoing a T6 treatment (solution at 520 °C followed by aging at 150 °C and 170 °C). Initially, the aging curves show higher hardness values for the direct aging condition, compared to the T6 and as-built conditions, reaching a peak hardness of 195 HV for 6h of direct aging. In this way, it was followed with microstructural characterization, which demonstrated that DA maintained the fine cell microstructure of L-PBF and promoted the precipitation of Si nanoparticles, which certainly contributed to the increase in hardness compared to T6, which promoted a structure with coarser precipitates. DA at 170 °C for 6 h increased the tensile strength to 430 MPa, compared to the as-built condition, with a slight loss of ductility. Full article

This research explores the effect of a composite support of SiO₂ and Al₂O₃ with Fe and Co incorporated as catalysts for Fischer–Tropsch synthesis (FTS) using a 3D-printed stainless steel (SS) microchannel microreactor. Two mesoporous catalysts, FeCo/SiO₂Al₂O₃ and Co/SiO₂Al₂O₃, were synthesized via a one-pot (OP) method and extensively characterized using N₂ physisorption, XRD, SEM, TEM, H₂-TPR, TGA-DSC, FTIR, and XPS. H₂-TPR results revealed that the synthesis method significantly affected the reducibility of metal oxides, thereby influencing the formation of active FTS sites. SEM-EDS and TEM further revealed a well-defined hexagonal matrix with a porous surface morphology and uniform metal ion distribution. FTS reactions, carried out in the 200–350 °C temperature range at 20 bar with a H₂/CO molar ratio of 2:1, exhibited the highest activity for FeCo/SiO₂Al₂O₃, with up to 80% CO conversion. Long-term stability was evaluated by monitoring the catalyst performance for 30 h on stream at 320 °C under identical reaction conditions. The catalyst was initially active for the methanation reaction for up to 15 h, after which the selectivity for CH₄ declined. Correspondingly, the C₄⁺ selectivity increased after 15 h of time-on-stream, indicating a shift in the product distribution toward longer-chain hydrocarbons. This trend suggests that the catalyst undergoes gradual activation or restructuring under reaction conditions, which enhances chain growth over time. The increase in C₄⁺ products may be attributed to the stabilization of the active sites and suppression of methane or light hydrocarbon formation. Full article

Fire retardancy and thermal management are critical for energy-efficient, fire-safe buildings. Natural wood, a mainstream construction material, possesses inherent advantages but lacks such dual functionality. Silicified wood was fabricated via multi-cycle silicification of native wood, where SiO₂ uniformly infiltrates and fills the lumens. The treated wood material displays an improved limiting oxygen index (LOI) from 21.9% to 36.0%, and delayed ignition from 15 s to 50 s, compared to untreated wood. It demonstrates a low thermal conductivity of 0.074 W·m⁻¹·K⁻¹, showing enhanced emissivity. When heated on a 75 °C hot plate, the silicified wood surface reaches ~50 °C after 5 s, versus ~60 °C for native wood. These enhancements collectively improve thermal management performance, achieving insulation through reduced thermal conduction and passive cooling via optimized infrared regulation. Ultimate tensile stress remains nearly unchanged post-treatment, while toughness is significantly improved. This work advances wood as a sustainable building material, with promising potential for fire-safe, energy-efficient construction applications. Full article

Biocompatible coatings are widely employed in dental applications to enhance the biofunctionality of metallic implants exposed to the aggressive oral environment. Among them, hydroxyapatite (HAp)-based and carbide-reinforced coatings have been explored due to their favorable mechanical and biological performance. In this study, Cr₃C_-20(Ni20Cr)-20HAp-XSi coatings were deposited using the high-velocity oxy-fuel (HVOF) technique. The coatings were applied onto commercially pure titanium substrates, with the silicon content varied between X = 0, 5, 10, and 20 wt%. To evaluate the coatings’ corrosion resistance, electrochemical techniques such as potentiodynamic polarization curves, linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), and open circuit potential (OCP) were employed. Artificial saliva was used as the corrosive medium at 37 °C for 168 h. The feasibility of producing carbide-HAp-Si coatings with excellent corrosion resistance and cytocompatibility via HVOF was demonstrated here, although some of the tested coatings (20 wt% Si) showed reduced electrochemical stability, attributed to faster dissolution processes and associated with a thinner coating layer, as confirmed by SEM analyses. X-ray diffraction (XRD) analyses revealed the formation of new phases in the coatings during thermal spraying, including Cr₂O₃ and Cr₇C₃. Additionally, MTT assays using 3T3-L1 fibroblasts showed no significant cytotoxic effects after 24 and 72 h of exposure to some of the coatings, confirming their biocompatibility for potential dental applications. Full article

With the increasing demand for high-performance ceramic guideways in precision industries, accurate flatness measurement of large-scale, rough ceramic surfaces remains challenging. This paper proposes a novel method combining oblique-incidence laser interferometry and sub-aperture stitching to overcome limitations of conventional techniques. The oblique-incidence approach enhances interference signal strength on low-reflectivity surfaces, while stitching integrates high-resolution sub-aperture measurements for full-surface characterization. Numerical simulations validated the method’s feasibility, showing consistent reconstruction of surfaces with flatness values of 1–20 μm. Experimental validation on a 1050 mm × 130 mm SiC guideway achieved a full-surface measurement with PV 2.76 μm and RMS 0.59 μm, demonstrating high agreement with traditional methods in polished regions. The technique enabled quick monitoring of a 39-h lapping process, converging flatness from 13.97 μm to 2.76 μm, proving its efficacy for in-process feedback in ultra-precision manufacturing. Full article

The paper presents the results of the influence of SiC dopant, annealing temperature, and annealing time on the morphology of MgB₂ material in superconducting wires. The results of measurements of critical temperature (T_c), irreversible magnetic field (B_irr), resistance in the normal state (R_n), and transport critical current density (J_ct) at the temperature range from 15 K to 30 K are presented. The MgB₂ material is characterized by the presence of two specific regions. The first region with high density, excess Mg, and rectangular MgB₂ grains is located outside the voids surrounding them. The second region occurs inside the ceramic core, away from voids, and its chemical composition corresponds to a stoichiometric Mg to B ratio (1:2), and it is characterized by the presence of spherical grains and lower material density. A higher amount of SiC admixtures (6 at.%) causes an increase in the first region surface area. This kind of structure observation in MgB₂ superconducting wires has never been reported previously. The transport measurements showed that higher SiC dopant leads to lower J_ct at higher temperatures and high magnetic fields. The studies showed that the point-dominant mechanism and the first region allow for obtaining high J_ct at 30 K. Full article

Silicon carbide (SiC) ceramics have gained significant attention in advanced engineering applications because of their superior mechanical properties, resistance to wear and corrosion, and thermal stability. However, the precision machining of these materials is extremely challenging because of their intrinsic hardness and brittleness. Wire Electrical Discharge Machining (WEDM) has become increasingly popular as a viable technique for processing SiC ceramics because of its ability to produce intricate geometries and high-quality surface finishes. In this review paper, a comprehensive overview of WEDM technology applied to SiC ceramics is presented, emphasizing the influence of process parameters, wire materials, and dielectric fluids on cutting efficiency and quality. This research explores recent experimental findings related to Wire Electrical Discharge Machining (WEDM) and highlights the challenges in reducing material damage. It also presents strategies to improve machining performance. Additionally, potential future directions are discussed, providing a roadmap for further research and the application of WEDM in processing silicon carbide (SiC) and its variants, including solid silicon carbide (SSiC) and silicon-infiltrated silicon carbide (SiSiC). Full article

This research presents a novel methodology to classify copper tailings according to their potential as alkali-activated materials (AAMs) for construction applications. The methodology includes geochemical and mineralogical characterization via QEMSCAN and X-ray fluorescence, with mechanical performance evaluation through compressive strength test (UCS). A three-phase diagram based on Al₂O₃, Fe₂O₃, and CaO-MgO-K₂O is proposed for a fast screening of copper tailing potential to be used as a construction material. In this paper, three copper tailings were chosen to test the methodology, and a set of five samples for each tailing have been geopolymerized for testing. Copper tailing samples were mixed with 0, 2.5, 5, 7.5 and 10% by mass of Ordinary Portland Cement (OPC) to evaluate the effect on performance when a chemical co-activator is used to improve material reactivity. Compressive strength testing was applied on 2 cm³ cubes after 28 days of curing at 60 °C, yielding values from 6 to 26.1 MPa. The best performing sample featured a Si/Al ≅ 3 ratio and a mineralogy with significant presence of reactive species such as plagioclase and K-feldspar (≅42%). In contrast, high levels of Fe₂O₃ (≥12%), clay (≥7%), and pyrite (≥4%) were associated with reduced mechanical performance. Full article

Image protection in privacy-sensitive domains, such as healthcare and military, exposes critical limitations in existing secret image sharing (SIS) schemes, including cumbersome shadow management, coarse-grained access control, and an inefficient storage-speed trade-off, which limits SIS in practical scenarios. Thus, this paper proposes two SIS schemes to address the above issues: the hierarchical control sharing scheme with Gaussian blur (HCSS-GB) and the image bit expansion-based sharing scheme (IBESS). For scenarios with limited storage space, HCSS-GB employs Gaussian blur to generate gradient-blurred cover images and integrates a controllable sharing model to produce meaningful shadow images without pixel expansion based on Shamir’s secret sharing. Furthermore, to accommodate real-time application scenarios, IBESS employs bit expansion to combine the high bits of generated shadow images with those of blurred carrier images, enhancing operational efficiency at the cost of increased storage overhead. Experimental results demonstrate that both schemes achieve lossless recovery (with PSNR of ∞, MSE of 0, and SSIM of 1), validating their reliability. Specifically, HCSS-GB maintains a 1:1 storage ratio with the original image, making it highly suitable for storage-constrained environments; IBESS exhibits exceptional efficiency, with sharing time as low as 2.1 s under the $(7,8)$ threshold, ideal for real-time tasks. Comparative analyses further show that using carrier images with high standard deviation contrast ($C_{\sigma }$) and Laplacian-based sharpness ($S_L$) significantly enhances shadow distinguishability, strengthening the effectiveness of hierarchical access control. Both schemes provide valuable solutions for secure image sharing and efficient shadow management, with their validity and practicality confirmed by experimental data. Full article

Poly (3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) stands out as a renowned commercial conducting polymer composite, boasting extensive and promising applications in the realm of film electronics. In this study, we have made a concerted effort to overcome the inherent drawbacks of PEDOT:PSS films (especially, high moisture absorption, mechanical damage vulnerability, insufficient substrate adhesion ability, etc.) by uniformly blending them with polydimethylsiloxane polyurea (PDMS-PUa) and silica (SiO₂) nanoparticles through a feasible mechanical stirring process, which effectively harnesses the intermolecular interactions, as well as the morphological and structural characteristics, among the various components. The Si−O bonds within PDMS-PUa and the −CH₃ groups attached to Si atoms significantly enhance the hydrophobicity of the composite film (as evidenced by a water contact angle of 132.89° under optimized component ratios). Meanwhile, SiO₂ microscopically modifies the surface morphology, resulting in increased surface roughness. This composite film not only maintains high conductivity (1.21 S/cm, in contrast to 0.83 S/cm for the PEDOT:PSS film) but also preserves its hydrophobicity and electrical properties under rigorous conditions, including high-temperature exposure (60–200 °C), ultraviolet (UV) aging (365.0 nm, 1.32 mW/cm²), and abradability testing (2000 CW abrasive paper, drag force of approximately 0.98 N, 40 cycles). Furthermore, the film demonstrates enhanced resistance to both acidic (1 mol/L, 24 h) and alkaline (1 mol/L, 24 h) environments, along with excellent self-cleaning and de-icing capabilities (−6 °C), and satisfactory adhesion (Level 2). Notably, the dried composite film can be re-dispersed into a solution with the aid of isopropanol through simple magnetic stirring, and the sequentially coated films also exhibit good surface hydrophobicity (136.49°), equivalent to that of the pristine film. This research aims to overcome the intrinsic performance drawbacks of PEDOT:PSS-based materials, enabling them to meet the demands of complex application scenarios in the field of organic electronics while endowing them with multifunctionality. Full article

The application of silicon–carbon (Si/C) composite materials in lithium-ion batteries faces problems regarding volume expansion and surface defects. Although coating is a popular modification scheme in the market, the influence of carbon layer quality on the electrochemical performance of Si/C still needs to be studied. By comparing the carbon layers produced by solid-phase and liquid-phase coating methods, an innovative solid–liquid coating technology was proposed to prepare high-strength and high-stiffness carbon layers, and the effects of different coating processes on the physical, mechanical, and electrochemical properties of the materials were systematically studied. Through physical properties and electrochemical testing, it was found that the solid–liquid coating method (Si/C@Pitch+RGFQ) can form a carbon layer with the least defects and the highest density. Compared with solid-phase coating and liquid-phase coating, its specific surface area (SSA) and carbon increment are the lowest, and the surface carbon content and oxygen content are significantly reduced after solid–liquid coating. Mechanical performance tests show that the Young’s modulus of the carbon layer prepared by this method reaches 30.3 GPa, demonstrating excellent structural strength and elastic deformation ability. The first coulombic efficiency (ICE) of Si/C@Pitch+RGFQ reached 88.17%, the interface impedance (23.2 Ω) was the lowest, and the lithium-ion diffusion coefficient was significantly improved. At a rate of 0.1 C to 2 C, the capacity retention rate is excellent. After one hundred and a half-cell cycles, the remaining capacity is 1420.5 mAh/g, and the capacity retention rate reaches 92.4%. The full-cell test further proves that the material has a capacity retention rate of 82.3% and 81.3% after 1000 cycles at room temperature and high temperature (45 °C), respectively. At the same time, it has good rate performance and high-/low-temperature performance, demonstrating good commercial application potential. The research results provide a key basis for the optimized preparation of the surface carbon layer of Si/C composite materials and promote the practical application of high-performance silicon-based negative electrode materials. Full article

In the micro-EDM blind-hole machining of C_f-ZrB₂-SiC ceramics, defects such as bottom surface protrusion and machining fillets are often encountered. The implementation of an electrode-assisted oscillating device has proven effective in improving machining outcomes. To unravel the fundamental reasons behind the optimization enabled by this auxiliary oscillating device, this paper presents fluid simulation research, providing a quantitative comparison of the differences in machining gap flow field characteristics and debris motion behaviors under conditions with and without the assistance of the oscillating device. Firstly, this paper briefly describes the characteristics of C_f-ZrB₂-SiC discharge products and flow field deficiencies during conventional machining and introduces the working principle of electrode-assisted oscillation devices to establish the background and objectives of the simulation study. Subsequently, this research established simulation models for both conventional machining and oscillating machining based on actual processing conditions. CFD numerical simulations were conducted to compare flow field differences between conditions with and without auxiliary machining devices. The results demonstrate that, compared to conventional machining, electrode oscillation not only increases the maximum velocity of the working fluid by nearly 32% but also provides a larger debris accommodation space, effectively preventing secondary discharge. Regarding debris agglomeration, oscillating machining resolves the low-velocity zone issues present in conventional modes, increasing debris velocity from 0 mm/s to 7.5 mm/s and ensuring continuous debris motion. Furthermore, the DPM was used to analyze particle distribution and motion velocities, confirming that vortex effects form within the hole under oscillating conditions. These vortices effectively draw bottom debris outward, preventing local accumulation. Finally, from the perspective of debris distribution, the formation mechanisms of micro-hole morphology and the tool electrode wear patterns were explained. Full article