Nanocrystalline soft magnetic composites (NSMCs) have met the requirements of emerging power applications with high conversion efficiency and a wide operating temperature range. However, owing to the evolving design concepts of power magnetic devices, the comprehensive electromagnetic performance of NSMCs should be further improved to broaden their applications. This review presents the typical applications and the advantageous scenarios of Finemet-based NSMCs fabricated from flaky powders. The state of the art and industrialization status of NSMCs for power magnetic devices are summarized. Based on the latest research findings, this review discusses feasible strategies for Finemet-based NSMCs concerning powder selection, insulation coating, powder densification, and heat treatment. Furthermore, the challenges and opportunities in the future development of low-loss Finemet-based NSMCs with a wide temperature range are highlighted.
Infrared-radar compatible stealth materials are essential for enhancing the survivability of military platforms, yet electromagnetic (EM) crosstalk between infrared and radar stealth remains a critical challenge. Herein, a multilayer compatible-stealth metamaterial was developed using Al/PDMS and TiB2/PDMS composites. The constituent layers and patterned structures were fabricated by imprinting, followed by mold-assisted interlayer alignment. The effects of different compatible-stealth transition layers (CSTLs) on radar wave absorption (RAWA) and the associated interlayer transmission and EM compatibility mechanisms were systematically investigated. The optimized structure employed TiB2/PDMS as both the radar-stealth dielectric layer (RSDL) and patterned layer (RSPL), while Al/PDMS served as both the CSTL and infrared-stealth layer (ISL). The metamaterial exhibited average emissivities of 0.36 and 0.47 in the 3-5 and 8-14 m atmospheric windows, respectively. At a total thickness of 12.00 mm, it achieved an effective absorption bandwidth (EAB) of 12.94 GHz for reflection loss below −5.00 dB and a minimum reflection loss (RLmin) of −30.46 dB at 10.11 GHz. Experimental validation further yielded an EAB of 12.58 GHz (RL < −5.00 dB) and an RLmin of −16.31 dB, showing good agreement with the simulated broadband absorption behavior. The excellent compatible-stealth performance arises from the metal-like infrared reflectivity of Al/PDMS, its smooth impedance-gradient transition for radar waves (RAWs), and the resulting suppression of interlayer EM coupling. RAW dissipation is further enhanced by macroscopic resonant losses, conduction loss, interfacial and dipolar polarization, and defect-induced polarization relaxation. This work provides a viable strategy for reconciling infrared and radar stealth performance.
With the rapid advancement of modern communication technology, the issue of electromagnetic interference has become increasingly severe. The pervasive electromagnetic waves in the air not only disrupt the operation of electronic devices but also pose significant risks to human health. Microwaves, as a crucial category of electromagnetic waves, are widely utilized in fields such as telecommunications, commerce, military, aerospace, and aviation. Microwave-absorbing materials play a vital role in mitigating electromagnetic interference by converting incident microwaves into thermal energy and dissipating them. Among these materials, carbonyl iron powder (CIP) stands out as a key microwave absorber. This article outlines the synthesis and flattening process of CIP and focuses on various research efforts concerning flaky CIP (FCIP) as a microwave-absorbing material. It discusses how characteristics such as microstructure, thickness, and filling ratio of FCIP influence its electromagnetic parameters and absorption performance. Additionally, the article explores the changes in microwave absorption properties when FCIP is combined with oxides, carbon-based materials, metallic materials, polymers, and other substances through methods like surface coating modification, mixing modification, or structural design. Finally, future prospects for the development of FCIP are presented.
Zinc oxide (ZnO) is an extensively explored photocatalyst whose practical application is constrained by rapid charge recombination and limited visible-light absorption. Biomass-derived carbon quantum dots (CQDs) have arisen as sustainable co-catalysts that enhance interfacial charge transfer, visible-light harvesting, and reactive oxygen species generation, while concurrently converting agricultural and food-processing waste. This review critically evaluates biomass-derived CQD/ZnO composites and introduces three analytical frameworks to improve mechanistic interpretation, reporting quality, and sustainability assessment. A comparative analysis reveals widespread under-characterisation across the literature, including limited reporting of quantum yield, fluorescence lifetime, mineralisation endpoints, ROS validation, and Zn leaching behaviour. Although hydrothermal synthesis dominates because of its simplicity and compatibility with biomass, substantial variation exists in process energy demand and mechanistic rigour. Nitrogen-doped CQD systems demonstrate enhanced electronic performance but also present unresolved trade-offs between photocatalytic efficiency and the credibility of green synthesis. Overall, this review argues that the principal limitation in biomass-derived CQD/ZnO composite systems is no longer material discovery itself, but the absence of standardised, mechanism-resolved reporting practices required for reliable cross-study benchmarking and reproducible interpretation.
In this paper, the spontaneous polarization of the Pb(Fe0.5Nb0.5)O3 (PFN) multiferroic compound is determined by using the Geometrical Polarization Approach (GPA), a semi-empirical method to obtain spontaneous polarization from refined crystallographic data. Two distinct unit cells were analyzed: a conventional tetragonal unit cell (P4mm) with statistical Fe/Nb occupancy at the perovskite B-site, and an expanded supercell composed of eight stacked unit cells refined in the triclinic P1 space group, allowing an explicit description of Fe and Nb atomic positions within the supercell. While both approaches yield comparable Rietveld refinement quality, the conventional unit cell significantly underestimated the spontaneous polarization (∼2.3 μC/cm2). In contrast, the supercell revealed distinct local polarization contributions from Fe and Nb. The global polarization calculated from the supercell structure (∼2.9 μC/cm2) differs from that obtained using the statistically averaged conventional cell, indicating the importance of the structural details in the polarization determination. Electron-density mapping further revealed distinct local electronic environments around Fe and Nb, suggesting different dipole asymmetries that are consistent with their different polarization contributions. These results support the GPA as an effective tool to resolve intrinsic structural polarization features in chemically disordered perovskites and offer insights into the structure–property relationships in multifunctional ferroelectric materials.
The indiscriminate cross-sensitivity of noble-metal-functionalized metal oxide semiconductor sensors poses a significant challenge for precise ammonia (NH3) detection in complex industrial environments. This study presents an approach to develop a highly selective sensor architecture by incorporating a dense amorphous tantalum pentoxide (Ta2O5) permselective overlayer onto an Ag-Pt co-decorated SnO2 thin film. The pristine Ag-Pt/SnO2 sensor demonstrates exceptional sensitivity owing to synergistic chemical and electrical sensitization. However, its performance is severely compromised by interference from hydrogen (H2), resulting in a response dominated by surface reactions. By optimizing the thickness of the Ta2O5 layer deposited by reactive DC magnetron sputtering, a 50 nm thick permselective overlayer significantly reduces the hydrogen and acetone permeability, while allowing a sufficient ammonia permeability. Unlike conventional sieving, it blocks large acetone molecules via steric hindrance and suppresses the diffusion of non-polar H2 through the high tortuosity of the dense amorphous network. In contrast, the transport of NH3 is facilitated by Lewis acid-base interaction with the oxide matrix, allowing it to permeate efficiently. As a result, the modified sensor demonstrates a robust ammonia response (S = 394 at 250 °C) with an exceptional selectivity ratio (SNH3/SH2 = 28.5), effectively resolving the cross-sensitivity issue and significantly reducing the risk of false alarm. This study establishes a foundation for creating interference-resistant sensor platforms based on dense amorphous permselective membranes.
A comprehensive quantum transport study of three functionalized MXene monolayers—Ti3C2O2, Sc3C2F2, and Zr3C2O2—is performed using a tight-binding model within the non-equilibrium Green's function (NEGF) formalism. Zigzag graphene electrodes are incorporated via the Sancho–Rubio method for semi-infinite leads. Our comparative analysis reveals distinct transport regimes. Ti3C2O2 exhibits a prominent negative differential resistance (NDR) between 0.7 and 1.1 V, which is strongly correlated with the bias-induced suppression of the Ti-dz2 orbital contribution near the Fermi level. In contrast, Zr3C2O2 shows conventional semiconducting behavior with monotonic current increase, while Sc3C2F2 displays limited conductivity due to its wider electronic gap. Temperature-dependent calculations confirm the robustness of NDR in Ti3C2O2 at room temperature. These findings establish a structure–property relationship for MXene-based nanoelectronics, demonstrating how transition metal selection enables tailored transport characteristics ranging from NDR to conventional semiconducting behavior.
The growing level of pharmaceutical pollution in aquatic resources is becoming a significant complex environmental problem. Among these, norfloxacin, a broad-spectrum fluoroquinolone antibiotic characterized by high persistence, is especially concerning because of its low biodegradation rate. It is widely accepted that visible light-driven photocatalytic processes represent a promising technique in terms of degrading such pollutants, while a thorough understanding of charge carrier dynamics is essential for the rational design and development of highly efficient catalysts. In this work, a NiWO4/PANI/MXene nanocomposite photocatalyst is fabricated and evaluated for the removal of norfloxacin (NOR) under visible light illumination. The impact of several reaction parameters, including norfloxacin concentration, the amount of catalyst and solution pH, was thoroughly studied. The synthesised nanocomposite NiWO4/PANI/MXene showed significantly higher removal efficiency of (86.81%) than the individual components, such as NiWO4 (60.80%), MXene (66.48%) and PANI (48.07%), demonstrating the synergistic effect of the ternary hybrid structure. Maximum removal was achieved at pH 6.0, where favourable electrostatic interactions between the catalyst and NOR molecules enhanced both adsorption and photocatalytic activity. Moreover, radical scavenging studies revealed that hydroxyl (•OH) and superoxide (•O2−) radicals were the dominant reactive species for NOR degradation. These findings highlight the high potential of NiWO4/PANI/MXene as an advanced photocatalyst for NOR remediation and provide valuable insights for the rational design of multifunctional photocatalysts for wastewater treatment.
This review critically evaluates additive manufacturing routes for neodymium–iron–boron (NdFeB) permanent magnets by benchmarking remanence and energy density to explain how processing variables and inherent manufacturing constraints limit magnetic performance relative to conventional sintered and bonded magnets. Reported remanence values for additively manufactured NdFeB magnets generally fall between 0.6 and 1.0 T. Among the available routes, material extrusion (MEX) currently represents the most competitive additive manufacturing pathway for bonded NdFeB magnets, although remanence remains below sintered anisotropic grades (1.4 to 1.5 T). By contrast, laser-based routes such as selective laser melting offer significant geometric flexibility but are effectively limited by the absence of demonstrated magnetic texture, while selective laser sintering and binder jetting remain constrained by intrinsic porosity. For non-laser-based routes, magnetic performance is largely determined by feedstock design, including NdFeB filler fraction, magnetic alignment strategies, and post-processing treatments. Overall, additive manufacturing can reproduce the performance of commercial anisotropic bonded NdFeB magnets, with the highest remanence achieved through MEX routes with magnetic texture. These insights guide the development of advanced magnetic materials and functional devices enabled by additive manufacturing for high-performance traction motors, as well as sensors and actuators in wearable and biomedical devices.
Triboelectric nanogenerators (TENGs) has emerged as an effective approach for harvesting ambient mechanical energy for powering small electronic devices and self-powered sensing systems. Among various triboelectric materials, poly(vinylidene fluoride) (PVDF) has gained significant attention due to its combined piezoelectric and ferroelectric properties, which are strongly governed by its crystalline phase. In particular, the electroactive β-phase plays a crucial role in enhancing charge generation and improving device performance. However, the dominance of non-polar α-phase in conventionally processed PVDF remains a major limitation for achieving high triboelectric output. Recent efforts have focused on inducing β-phase formation through advanced processing techniques and material modifications. Among these, electrospinning have emerged as a powerful strategy for promoting dipole alignment and tailoring fiber morphology, thereby facilitating enhanced electroactive phase formation. In addition, the incorporation of functional nanofillers including metal oxides, carbon-based nanomaterials (NMs), and polymer blends have shown significant influence on phase transformation, dielectric properties, and charge trapping behavior of PVDF systems. Despite these advancements, understanding the interplay between processing methods, polymorphic phase evolution, and resulting triboelectric performance remains limited. This review addresses this gap by providing a critical analysis of electrospun PVDF-based TENGs, with a particular focus on β-phase engineering through nanofiller incorporation. Furthermore, recent developments in applications such as wearable electronics, biomedical monitoring, and self-powered sensors are summarized. Finally, key challenges and future research directions are outlined to guide the design of high-performance and scalable PVDF-based triboelectric energy harvesting systems.
The dark current remains the primary limiting factor in the performance of Quantum Dot Infrared Photodetectors (QDIPs), particularly for operation at elevated temperatures. In this work, we present a comprehensive physical model for the dark current transport in InAs/GaAs QDIPs incorporating an Al0.3Ga0.7As current blocking layer. The model integrates the emission-capture framework with a rigorous WKB approximation for field-assisted tunneling in spherical quantum dot geometry. We validate the analytical formulation against experimental data at room temperature (T=290 K), achieving excellent agreement with a logarithmic root-mean-square error of 0.217. A comparative architectural analysis reveals that the inclusion of the heterointerface blocking layer suppresses the dark current by approximately six orders of magnitude compared to standard designs, providing a quantitative theoretical basis for the device’s room-temperature functionality. Furthermore, we perform a Monte Carlo uncertainty quantification to assess manufacturing tolerances, demonstrating that the device performance is robust against quantum dot size fluctuations but highly sensitive to barrier composition variations. These findings establish design guidelines for optimizing high-temperature infrared sensors, predicting a detectivity enhancement of three orders of magnitude with moderate cooling to 200 K.
To enhance the hydrophilicity, mechanical properties, and biological performance of PCL/30S48P4 composite scaffolds, in this study, three enhanced composite scaffolds (PCL-COOH/30S48P4, PCL/30S48P4/10CS, and PCL/30S48P4@20CS) were successfully fabricated using DIW technology based on distinct strategies including PCL carboxylation, chitosan (CS) doping, and dual-printhead alternating printing, and their surface characteristics, physico-mechanical properties, bioactivity, and in vitro biocompatibility were systematically evaluated. The results demonstrated that all three modification strategies enhanced the PCL/30S48P4 composite scaffolds to varying degrees. Due to the introduction of hydrophilic groups, the three enhanced composite scaffolds exhibited lower water contact angles. Specifically, the contact angles of PCL/30S48P4/10CS and PCL/30S48P4@20CS decreased to 72.28 ± 2.79° and 69.56 ± 3.38°, respectively, falling within the optimal range for cell adhesion (35° ∼ 80°). Meanwhile, the compressive strengths of the three enhanced scaffolds reached 6.12 ± 0.25 MPa, 8.06 ± 0.33 MPa, and 7.13 ± 0.19 MPa, representing increases of 11.48%, 46.81%, and 29.33%, respectively, compared with the pristine scaffold. In vitro SBF immersion tests revealed continuous deposition of HCA on the scaffold surfaces, indicating favorable mineralization activity. Furthermore, in vitro biocompatibility evaluation showed that PCL/30S48P4/10CS exhibited superior cell viability and ALP activity relative to the other groups. In summary, among these scaffolds, PCL/30S48P4/10CS exhibits the optimal comprehensive performance and provides preliminary experimental evidence for further investigation of the scaffold as a candidate material for bone repair.
A hybrid aluminum matrix nanocomposite reinforced with AlMgB14 nanoparticles and graphite was successfully fabricated by mechanical milling followed by hot pressing. This study systematically investigates the individual and combined effects of AlMgB14 and graphite on the microstructure, mechanical properties, and tribological behavior of Al-based nanocomposites. The Al-5 wt.% AlMgB14-1 wt% graphite hybrid nanocomposite exhibited substantial improvements in hardness (105%), yield strength (147%), and compressive strength (127%) compared with pure Al. It also showed significant reductions in the coefficient of friction (73%), specific wear rate (88%), and surface roughness (77.5%). X-ray diffraction analysis revealed crystallite refinement and increased dislocation density after mechanical milling, while no reaction products were detected within the resolution limit of the XRD after hot pressing. The observed mechanical enhancement is qualitatively interpreted in terms of crystallite refinement, Orowan strengthening, increased dislocation density, and thermal expansion mismatch-induced strengthening, based on the experimental observations and well-established strengthening theories. The improved tribological performance is primarily associated with the increased hardness of the composites, suppression of severe plastic deformation, formation of a mechanically mixed layer (MML), and the solid-lubricating characteristics of graphite. Furthermore, the synergy index (SI) demonstrated that the hybrid reinforcement provides a genuine synergistic improvement in tribological performance while largely preserving the strengthening effect of AlMgB14. These findings demonstrate that the combined use of AlMgB14 nanoparticles and graphite offers a promising strategy for developing lightweight aluminum matrix nanocomposites with balanced mechanical and tribological properties for wear-resistant engineering applications.
This study synthesized nano-sized ZrB2 ceramic particles via the melt-in-situ reaction method using an Al-Si-Mg alloy as the matrix. Results indicate that uniformly dispersed nano-ZrB2 particles were successfully produced at 850 °C with a ZrB2 content of 2 wt.%. Following T6 heat treatment, the composite exhibited significantly improved mechanical properties: tensile strength, yield strength, elongation, and Quality Index (Q) reached 240.36 MPa, 179.81 MPa, 11.87%, and 401.53 MPa, respectively, representing increases of 51.1%, 75.7%, 53.2%, and 37.3% over the base alloy. The Vickers hardness also increased from 64.5 HV to 115.5 HV, enabling the alloy to exhibit both excellent strength and ductility.AC-TEM microstructural analysis revealed that appropriately sized in-situ-grown nanoparticles induced lattice distortions near ZrB2/Al interfaces and promoted dislocation accumulation near eutectic Si regions. DSC analysis showed that the addition of ZrB2 elevated the characteristic phase transformation temperatures, while the microstructural refinement and multi-mechanism strengthening collectively contributed to the improved mechanical properties. Microstructural observations revealed clean interfaces between the Al matrix and ZrB2 particles, with no discernible reaction layers. Geometric phase analysis indicated that some non-congruent interfaces were prone to high dislocation density, leading to localized lattice distortion. Furthermore, the introduction of ZrB2 particles does not alter the growth orientation of eutectic Si particles, and no significant lattice rotation of Si atoms was observed at the interfaces. A reference estimation based on the Hall-Petch relationship indicates that grain refinement is one of the contributing factors to the mechanical property enhancement, although the overall strengthening arises from multiple mechanisms including Orowan strengthening, dislocation strengthening, and grain refinement. This discovery provides an effective approach for designing high-performance aluminum alloys and alleviating the long-standing strength-ductility trade-off in metallic materials, while serving as a meaningful extension and inspiration to existing relevant research concepts.
A symmetric loaded square-ring graphene metasurface absorber is numerically investigated for broadband terahertz (THz) absorption. The unit cell comprises a patterned graphene resonator placed on a polyimide spacer and backed by a continuous Au ground plane. Graphene is modeled as a frequency-dependent surface-impedance sheet governed by chemical potential, relaxation time, and temperature. At μc=1.0 eV, τ=0.1 ps, and T=300 K, the absorber reaches 99.89% absorptance at 2.90 THz and maintains absorptance above 90% over a 1.37 THz bandwidth, corresponding to a fractional bandwidth of 47.2%. Impedance retrieval, field distributions, surface-current paths, power-loss distributions, and quantitative material-loss analysis show that the broadband response arises from the combined effects of the loaded graphene current path, dielectric spacing, resonator-ground coupling, and graphene loss. Chemical potential mainly controls the absorption level and bandwidth. Treating μc=1.0 eV and μc=0.4 eV as the ON and OFF states, respectively, gives a modulation depth of 49.2% at 2.90 THz. Polarization-angle and oblique-incidence analyses show a similar response up to 60∘ transverse-electric (TE) and transverse-magnetic (TM) incidence, while the maximum polarization-conversion ratio remains below 5%. A stricter adaptive-mesh test and a separate time-domain simulation give closely matched absorption spectra. The graphene surface-impedance implementation and intraband approximation are checked against analytical impedance and full finite-temperature Kubo calculations. The electromagnetic loading introduced by a 0.1μm ion-gel layer and a continuous zero-thickness graphene top gate is also examined. A 100-case coupled Latin-hypercube analysis includes graphene-conductivity reduction, edge disorder, and spacer-thickness variation. The results remain numerical predictions because contacts, finite bias routing, spatial carrier-density variation, and measured fabrication-error distributions are not included.
The widespread use and long-term exposure of humans to micro- and nano-plastics (MNPs) drives a significant need to comprehensively understand their health impacts. MNPs have now been definitively detected in a multitude of environmental, as well as human biological samples, confirming that they do in fact enter and accumulate in the human body. However, there are still significant challenges when it comes to understanding the interaction between MNPs and human physiology. The complex combinations of particle size, shape, and chemical composition – including polymer type and additives/contaminants – and how such combinations interact with a multitude of human biological environments, makes it difficult to determine clear and precise exposure-effect relationships. Furthermore, in light of growing research showing that the identification and quantification of MNPs in vivo may have been inaccurate due to strong background signals, calls for the development and implementation of additional technologies have been emerging. In response to this, we have been exploring the possibility of utilizing magnetic nanoparticles (often in combination with fluorescent detection) to shed further light on the spatial and temporal detection of MNPs. Over the past two decades, a battery of novel technologies, that permit detection with breadth, depth, detail and completeness never explored before – have been developed, offering track-and-trace information at macro-, micro- and nano- perspectives. This review (i) provides the current status of prevalence of micro- and nano- plastics in the environment and in living organisms, (ii) gives an overview of the physiological negative impact on humans, (iii) summarizes the current detection and quantification methodologies along with the challenges and blind spots, and (iv) proposes novel techniques and instrumentation using magnetic nanoparticles that will provide unprecedented spatial- and temporal- resolution of the whereabouts of MNPs. It is our hope that through this, the MNP community will continue to have fruitful discussions on how best to attack the current problems.
Development of bioceramic coatings on metallic implants (Ti-6Al-4V) with superior bone bonding ability and corrosion resistance is crucial in the field of biomedicine. The incorporation of ferrites such as cobalt ferrite into hydroxyapatite (HA) helps in achieving efficient nanocomposites that could be employed for magnetic hyperthermia applications. This work focusses on the fabrication of cobalt ferrite-hydroxyapatite composite coatings using an economical spin-coating method by varying the coating parameters and the studies were performed on the coatings. The produced coatings were characterized using XRD, FT-IR and SEM analysis. The wettability studies were done by measuring its contact angle, where the coatings exhibited hydrophilic behavior. The Vickers microhardness test was carried out to determine its mechanical properties and the coatings exhibited good hardness owing to their uniform nature. The bacterial growth restriction behavior of the coatings was conducted using two microorganisms (Escherichia coli and Staphylococcus aureus) and the number of viable bacterial colonies was measured. The coatings revealed good anti-bacterial activity and was higher for E. coli when compared to S.aureus. The biomineralization studies were performed and excellent bone-like apatite formation was observed on the coatings. The biocompatibility was assessed using L929 fibroblast cell lines and the cell viability was found to be higher for coatings unlike metal substrate. Early-late apoptosis of cells was identified using fluorescence staining (AO/EB) assay. The heating ability of the coatings were determined and the optimized coating was taken for in-vitro hyperthermia studies using human osteosarcoma (MG-63) cell lines, where the cell viability of the coatings declined significantly indicating cell death after hyperthermia treatment. Apoptosis and necrosis of the cells was analyzed using Propidium Iodide staining. The electrochemical behavior of the coatings was observed by immersing in SBF solution using polarization and impedance studies in order to determine its corrosion resistance. According to these studies, the developed multifunctional coating can perform as a potential biomaterial in orthopedic applications.
High-entropy alloy/graphene composites (HEA/Gr) have broad application prospects in advanced engineering fields due to their excellent mechanical properties, including high strength, hardness, and wear resistance. However, the underlying strengthening mechanisms remain insufficiently understood, limiting the precise regulation of material structures and further enhancement of performance. In this study, molecular dynamics simulations are employed to systematically investigate the effects of embedding different numbers of Gr layers on the nanoindentation mechanical behavior of FeNiCrCoCu HEA composites under various indenter radii. The results indicate that for different indenter radii, HEA/Gr composites exhibit higher indentation loads and hardness values than pure HEA. The introduction of Gr markedly enhances the load-bearing capacity and deformation resistance of the material, while suppressing dislocation nucleation and propagation and effectively alleviating local stress concentrations. When additional Gr layers are introduced, the strengthening effect gradually diminishes, along with an increase in local crystal defects such as stacking faults, thereby exacerbating localized structural damage. In HEA/Gr composites, dislocation transmission leads to the formation of prismatic dislocation loops and stacking fault tetrahedra, which facilitate plastic deformation. The prismatic dislocation loops can recover upon unloading, whereas residual defects induce permanent damage. These findings deepen the understanding of the micromechanical mechanisms in HEA/Gr composites and provide important guidance for the design and process optimization of next-generation structural materials in key industries such as aerospace and high-end manufacturing.
Nickel hydroxide nanosequins (NHNS) were synthesized and then applied as an electrocatalyst for the oxidation and quantification of remdesivir (RDV). The NHNS were prepared by a one-pot and highly simple hydrothermal route and characterized by field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. The kinetics of the redox transition of Ni(III)/Ni(II) species in NHNS were electrochemically investigated in an alkaline solution, and the apparent rate constant and the the charge transfer coefficient were determined. Electrocatalytic oxidation of RDV on the NHNS surface was subsequently studied, and the involved kinetic parameters were extracted using cyclic voltammetry, steady-state polarization, and chronoamperometry. RDV underwent oxidation by the nickel oxyhydroxide species via an EC’ mechanism, and the rate constant, electron-transfer coefficient, and diffusion coefficient of RDV were determined. Based on the excellent electrocatalytic activity of NHNS for oxidation of RDV, an efficient, straightforward, time-saving, and sensitive amperometric method was developed for RDV analysis with a limit of detection of 0.30 μmol L-1 (0.18 μg mL-1). The NHNS-modified electrode was successfully applied to the direct analysis of RDV in human serum samples and pharmaceutical ampoules. As an electrocatalyst, NHNS highlighted advantages such as a simple synthesis route, outstanding catalytic performance, long-term stability, high sensitivity, and antifouling characteristics.
High-Entropy Alloys (HEAs) are next-generation materials, particularly find its application in hydrogen storage tank development. This study explores the variation in Fe (Fe35, Fe32.5, Fe20) and Mn (Mn5, Mn7.5, Mn20) elemental compositions' effect in HEAs. The alloys were developed with the help of Mechanical Alloying (MA) followed by vacuum sintering via Powder Metallurgy (PM) routes. The MA followed by the as-sintered HEAs samples and their crystal structure are the influential factors for additions of Fe and Mn elements. The variations in Fe and Mn elements do not affect crystal structural changes up to 30 h of MA. The 30 h of milled HEAs have developed the single-phase FCC structure compared to 10, 20, and 30 h of milling. In 30 h of milling, it refine particles from coarse to fine microstructure and also avoids the cold-weld of particles and agglomerations. Compared to Fe, Co, Ni, and Mn elements, the Cr elements were highly segregated at the grain boundary regions, confirmed by FESEM-EDS elemental mapping analysis. The effects of a similar atomic radius enhance the higher atomic diffusion and improve the as-sintered HEA density. The Electron Backscattered Diffraction (EBSD) analysis revealed that higher Fe addition refines the as-sintered HEAs and their grain boundaries. These grain boundaries were designed to increase the amount of HAGBs formation. The HAGBs follows 93%, 90%, and 83.8% for Fe35, Fe32.5, and Fe20. The higher HAGBs formation impedes dislocation motions and improves the alloy strengthening behavior. Residual stress analysis revealed that increasing the Fe content promoted the development of compressive residual stress in the as-sintered HEAs. The increased compressive residual stress suppresses crack initiation and delays crack propagation, thereby enhancing the mechanical integrity of the alloys. The tribological study focuses on wear and coefficient of friction under different loading conditions (10, 20, and 30 N). Results indicate increasing Fe35 content achieves a higher hardness of 145HV, lower residual stress of −484 MPa, sintered density of 7.88 g/cm3, higher resistance to wear of 1.8371 ⅹ 10−7 mm3/N-m, and maintains thermal stability up to 512 °C. These results highlight the importance of alloy's composition in tailoring material properties and suggest new avenue for HEA's development.
