Search Results (2,569)

Oxidative desulfurization (ODS) is a promising alternative to conventional desulfurization methods because it operates under relatively mild conditions. Mixing-assisted oxidative desulfurization (MAOD), a variant of ODS, uses high-shear mixing to improve mass transfer between immiscible phases, enhancing sulfur conversion efficiency. This study reviews recent developments in MAOD for the removal of dibenzothiophene (DBT) and benzothiophene (BT) through a research matrix synthesizing the current literature. MAOD has demonstrated excellent performance, achieving up to 100% sulfur conversion in both model and real fuels, with DBT consistently showing higher conversion than BT. Response Surface Methodology (RSM) was commonly applied for process optimization, identifying typical operating conditions of 40–70 °C, 30 min reaction time, and 10,000 rpm as sufficient for complete sulfur conversion. The choice of oxidant and catalyst system strongly influences process efficiency, with polyoxometalates and hydrogen peroxide frequently achieving 100% conversion. Sustainable oxidants, including Fe(VI) and Mn(IV) derived from wastewater treatment sludge, have also shown promising results. However, the inability of model fuels to fully represent real fuel complexity and the limited use of RSM designs beyond Box–Behnken and Face-Centered Central Composite Designs highlight areas for future research. Overall, MAOD is a developing but highly promising desulfurization technology. Full article

Based on comparative experiments conducted on conventional Portland cement (OPC) systems, ferraluminate cement (FAC) systems, and FAC–fly ash (FA) composite systems, this study systematically investigates the ion evolution in pore solutions and the transformation of hydration products, as well as the compositional and microstructural evolution of the passive film formed on steel reinforcement surfaces under simulated pore solution conditions and natural passivation conditions. The results show that: ① FAC and FA-mixed systems produce different product types from OPC in the early stage (mainly AFt/AFm, C–(A)–S–H), thereby altering the pH and the evolution of the main ion concentration in the pore solution. ② An appropriate amount of FA (10%) refines the pore structure through pozzolanic reaction, enhances low-frequency electrochemical impedance, and facilitates the evolution of the steel passive film toward a more favorable composition; however, excessive incorporation (20%) induces a “dilution effect” and reduces the early-age densification rate, which is ultimately detrimental to long-term corrosion resistance. ③ The passive film exhibits a characteristic chemical gradient evolution, comprising an outer Fe³⁺-enriched phase and an inner Fe²⁺-enriched phase. Its thickness and the Fe²⁺/Fe³⁺ ratio are significantly influenced by the chemical environment of the pore solution (pH, SO₄²⁻, Al³⁺, Fe³⁺, etc.), which plays a decisive role in the protective efficiency of the steel reinforcement. These findings establish the intrinsic relationship between pore solution chemistry, hydration product evolution, and passive film development, providing new mechanistic insight into the passivation behavior of reinforcing steel in FAC–FA systems. Based on these findings, key guidelines for the proportioning and microstructural–electrochemical design of ferroaluminate cement are proposed, providing scientific support for the durability-oriented application of FAC–based materials in aggressive environments. It should be noted that the beneficial effect of incorporating 10 wt.% FA is limited to the optimization of FAC–based systems and should not be interpreted as indicating superior overall corrosion resistance compared with OPC. Full article

Low-temperature operation of lithium-ion batteries (LIBs) is severely limited by sluggish Li⁺ transport, aggravated interfacial polarization, and structural degradation of layered oxide cathodes. Herein, a multifunctional Li₂O-B₂O₃-Li₂SO₄ composite coating, denoted as LBLS, was constructed on LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) through a simple wet-mixing/calcination strategy. Structural and surface characterizations confirm that the LBLS-derived layer is successfully introduced onto NCM622 while the layered α-NaFeO₂ framework is well preserved. Benefiting from the regulated surface chemistry and improved interfacial kinetics, NCM622@LBLS exhibits significantly enhanced electrochemical performance, especially under subzero conditions. At −20 °C, the charge-transfer resistance decreases from 160 Ω for pristine NCM622 to 110 Ω after LBLS modification. Moreover, after 500 cycles at −20 °C, NCM622@LBLS maintains 101.57 mAh g⁻¹ with a capacity retention of 80.60%, which compares favorably with representative coated NCM622 cathodes evaluated under comparable subzero conditions. In situ XRD reveals suppressed lattice breathing, while ex situ EIS, DRT and GITT confirm reduced interfacial polarization and faster Li⁺ diffusion. Depth-profiling XPS further demonstrates that LBLS promotes an inorganic-reinforced CEI containing Li–O, B–O/B–F, and SO_x-containing species, thereby stabilizing the cathode/electrolyte interface during low-temperature cycling. Full article

Efficient removal of tetracycline (TC) from antibiotic-contaminated wastewater remains a significant challenge. In this study, a nitrogen-doped carbon modified cobalt ferrite (C@CoFe₂O₄, CF) composite was synthesized via a one-step hydrothermal method, and its adsorption–catalysis dual-function performance was systematically evaluated. Structural characterization revealed that CoFe₂O₄ nanoparticles were locally encapsulated by an N-doped carbonaceous layer, providing a high specific surface area and abundant nitrogen-containing active sites. Under optimized conditions, the CF-3/PMS system achieved 93.44% TC removal within 45 min, while CF-3 exhibited a maximum adsorption capacity of 486.5 mg·g⁻¹. Radical quenching experiments suggested that singlet oxygen (¹O₂) and superoxide radicals (O₂•⁻) played major roles in TC oxidation, while sulfate radicals (SO₄•⁻) and hydroxyl radicals (HO•) also contributed, indicating the coexistence of radical and non-radical oxidation pathways. TC adsorption was driven by surface complexation, π–π electron donor–acceptor interactions, and hydrogen bonding. The enhanced TC removal performance may arise from the cooperative contributions of N-containing carbon sites, accessible Co/Fe-containing regions, and interfacial electronic interactions, which promote TC enrichment and PMS-mediated oxidation. This work provides a promising strategy for designing bifunctional materials for antibiotic wastewater treatment. Full article

To realize the remanufacturing of cast iron components, a WC-reinforced Fe-based composite powder was designed, and the WC/Fe-based composite coating was deposited on the HT250 substrate by laser cladding. The melting and dissolution mechanism of WC ceramic particles were investigated, and their influences on the microstructure, phase, microhardness, and wear resistance of the composite coatings were systematically analyzed. The results show that the WC/Fe-based composite coating achieves good metallurgical bonding with the HT250 substrate and possesses excellent forming quality. The incorporated WC particles can effectively optimize the microstructural morphology, acting as heterogeneous nucleation sites and inhibiting grain growth. As WC content increases, the grain size within the composite coating gradually refines. Moreover, partially melted WC particles release tungsten (W) and carbon (C) elements into the molten pool, promoting the in-situ generation of new hard phases, including W₂C and Fe₆W₆C. These newly formed phases, together with the residual unmelted WC particles, contribute a dispersion strengthening effect and improve the properties of the composite coatings. This effect becomes more pronounced with higher WC content. Notably, the composite coating with 20% WC exhibits a microhardness over twice that of the HT250 substrate, while its wear rate is only one-sixth that of the substrate and its corrosion resistance is much higher than that of the HT250 substrate. Full article

This review presents a current understanding of the relationship between the structure of multicomponent metallic melts and the processes of amorphization and nanocrystallization. Particular attention is paid to the thermal-temporal treatment (TTT) of melts as a precision method for monitoring the nonequilibrium state of the liquid phase, the relaxation kinetics of cluster associations, and liquid–liquid transitions (LLT). The mechanisms by which precrystallization melt treatment affects the homogeneity of the amorphous precursor, the size of nanograins (7–15 nm), the phase composition (Fe₃Si, Fe₂B), and the resulting magnetic characteristics of toroidal cores (μ_max > 600,000, H_c < 0.5 A/m) are investigated. Based on an analysis of structural models of metallic melts (cybotactic, quasicrystalline, and quasichemical), it is shown that critical temperatures, viscosity hysteresis, and oscillatory relaxation serve as indicators of melt equilibrium. It is noted that the optimized TTT protocols combined with controlled annealing at 542–572 °C enable the formation of Fe₃Si nanograins with exceptional magnetic softness. The results open the possibility of discussing the prospects for integrating TTT with in situ diagnostics, CALPHAD modeling, and the potential of machine learning for the design of next-generation soft magnetic nanomaterials with tailored frequency characteristics for high-frequency power electronics and their use in electromagnetic shielding. Full article

The manuscript aims to analyze the properties of gray cast iron EN GJL-250 as a function of the charge composition with an emphasis on microhardness and indentation size effect (ISE). Three compositions of cast iron were used: cast iron A as traditionally produced cast iron, B and C as inoculated and overheated cast iron micro-alloyed with FeTi70. The authors used the cutting method to assess residual stresses in castings with a stress grid designed according to Sipp. The specimens from thick and thin bars of the grid, after determination of residual stresses, were used for uniaxial tensile tests, measurement of the hardness (HBW, HV, and Vickers microhardness), metallographic, and fractographic analysis. Results of microhardness were used for the determination of ISE indices, and “true hardness” was calculated. The effect of composition has a statistically significant effect (single ANOVA; specimens from thick and thin bars are considered together) only for Meyer index n, and in the case of thick bars, also for HBW and HV. Full article

This study investigates the design, microstructure, and performance profile of a novel composite coating combining a high-entropy alloy (HEA) matrix with cermet reinforcement. A 50wt.%CoCrFeMnNi_0.8V–50wt.% Cr₃C₂-Ni₈₀Cr₂₀ powder mixture was successfully deposited onto steel substrates via high-velocity oxy-fuel (HVOF) thermal spraying. Microstructural analysis revealed a highly dense, well-bonded coating architecture (450–500 μm thick) where partially melted, spherical HEA splats were uniformly surrounded by the Cr₃C₂-Ni₈₀Cr₂₀ phase. X-ray diffraction confirmed a complex multiphase evolution consisting of FCC, BCC, and σ-NiCr phases driven by the rapid solidification inherent to the HVOF process. Tribological evaluations via ball-on-disc testing demonstrated that incorporating the Cr₃C₂-Ni₈₀Cr₂₀ reinforcement significantly improves wear resistance compared to the monolithic HEA coating. The composite’s wear behavior is governed by a synergistic mechanism: the ductile HEA matrix accommodates plastic deformation, while the harder carbide particles enhance load-bearing capacity, transitioning from adhesive wear to mild third-body abrasion and protective tribo-oxidation. Conversely, electrochemical testing in a 3.5 wt.% NaCl solution showed that the composite coating exhibits higher corrosion current densities (10.53 × 10⁻⁶ A/cm²) and more active corrosion potentials than the pure HEA matrix. This behavior is attributed to localized micro-galvanic cells forming at the heterogeneous interfaces between the different phases, alongside chloride-induced destabilization of the surface oxide film. Overall, the novel composite coating offers a compelling, sustainable alternative for surface engineering applications requiring a balanced trade-off between mechanical toughness and acceptable environmental durability. This behavior is also verified by the comparison with previous results dealing with monolithic CoCrFeMnNi_0.8V and 75wt.%CoCrFeMnNi_0.8V–25wt.% Cr₃C₂-Ni₈₀Cr₂₀ thermal sprayed coatings, where it is evident that the increase of the reinforcing phase leads to an optimum combination of properties. Full article

This study explores the energy-harvesting performance of aluminum (Al)- and iron (Fe)-filled styrene–butadiene rubber (SBR) composites, with a focus on their mechanical durability and triboelectric properties. Comprehensive mechanical characterization—including tensile strength, elongation at break, fracture toughness, and elasticity—reveals that Fe-filled composites exhibit significantly enhanced reinforcement compared to Al-filled systems at equivalent filler loadings. Raman spectroscopy indicates that Fe atoms can coordinate with the benzene rings of SBR chains through stronger physicochemical bonding, a feature less present in Al-based composites. In addition to improved mechanical properties, Fe-filled composites demonstrate higher electrical conductivity and superior triboelectric energy-harvesting performance. Notably, the composite containing 15 vol% Fe under 1% cyclic compressive strain achieves a peak current density of 127.05 µA/m², a total generated charge of 5.01 nC, and a peak power density of 48.22 µW/m². These values represent substantial enhancements of 246%, 236%, and 2398%, respectively, compared to Al-filled counterparts. Cyclic energy-harvesting tests confirm stable performance with negligible degradation in output or mechanical integrity over repeated cycles. Rubber composite shows good humidity resistance in current and voltage outputs. Furthermore, a layer-by-layer triboelectric nanogenerator (TENG) based on the Fe-filled composite produces output signals of approximately ±1.0 µA and ±5 V under biomechanical hand patting. The superior performance of Fe-based composites is attributed to stronger filler–rubber interactions, likely facilitated by electrostatic interactions, which enhances interfacial charge transfer during mechanical deformation. Overall, Fe-filled SBR composites demonstrate strong potential for cost-effective, environmentally friendly, and durable self-powered energy-harvesting applications. Full article

Self-lubricating iron-based composites produced by powder metallurgy are promising materials for reducing friction and improving component durability under dry-sliding conditions. In this study, three composites reinforced with graphite and/or graphene oxide (Fe10%Gr, Fe10%GO, and Fe5%Gr5%GO) were fabricated to evaluate the influence of solid lubricants on densification, hardness, and tribological behavior. Powders were uniaxially compacted at 500 MPa and low-temperature-sintered at 880 °C under an argon atmosphere. The tribological performance was assessed by pin-on-disk tests against an AISI 52100 steel ball. Pure Fe exhibited the highest hardness (approximately 97 HV) and a final porosity of 17.5%, whereas the lubricant-containing composites showed porosities ranging from 17.3% to 22.8% and lower hardness values of 45–60 HV. Despite the reduction in hardness, all lubricant-containing compositions decreased the coefficient of friction relative to pure Fe (~0.33). Fe10%Gr and Fe5%Gr5%GO exhibited the lowest friction coefficients, reaching ~0.08 and ~0.05, respectively, while Fe10%GO showed the highest wear rate (~1.1 × 10⁻² mm³/Nm). Among the compositions studied, Fe5%Gr5%GO showed the best friction–wear balance among the self-lubricating formulations, combining low friction and moderate wear due to a surface synergy where graphite promotes continuous low-shear lubrication while GO promotes the formation of a more compact and resilient protective tribolayer. Full article

Accurate ocean wave sensing in polar and other low-temperature marine environments is of great significance for marine environmental observation, climate research, and navigation safety. However, conventional wave sensors rely on external power supplies and suffer from poor stability under low-temperature and high-salinity conditions, making long-term self-powered waves sensing a significant challenge. Herein, a highly stable composite eutectogel electrode is developed by integrating sodium lignosulfonate, Fe³⁺ crosslinking, Zn²⁺-carboxylate coordination interactions, and a choline chloride/urea deep eutectic solvent (DES). The DES effectively suppresses solvent crystallization and endows the gel with excellent low-temperature tolerance, while the synergistic effect of metal coordination and multiple non-covalent interactions constructs a robust ion-conducting network with enhanced structural stability. Furthermore, eutectogel-based composite electrode architecture is designed to improve electrical conductivity and charge collection efficiency, thereby enabling stable electrical output under harsh marine conditions. Based on the as-prepared eutectogel electrode, a self-powered solid–liquid triboelectric nanogenerator is fabricated for ocean wave-motion sensing. The device can detect the wave amplitude, with an accuracy of 0.2 cm, and sense the frequency of waves ranging from 0.2 Hz to 1.6 Hz. More importantly, the SL-TENG exhibits excellent environmental adaptability, operating reliably in 3.5 wt% simulated seawater and at 0 °C. The current retention ratio reaches approximately 91% at 0 °C, which is significantly higher than that of the hydrogel-based device (≈6%). The remarkably low-temperature and salt-tolerant performance originates from the stable ion-transport network and anti-freezing characteristics of the eutectogel electrode. This work provides an effective strategy for constructing environmentally resilient eutectogel-based triboelectric devices and offers a promising route toward self-powered wave sensing systems for long-term deployment in harsh marine environments. Full article

Selective laser melting (SLM) can effectively suppress metallurgical defects inherent to conventional manufacturing; however, subsequent aging treatments essential for engineering applications introduce secondary precipitates that alter the electrochemical homogeneity of the matrix. The underlying mechanism by which such precipitation behavior governs corrosion resistance remains elusive. In this study, a Fe-30Mn-8Al-1.5C-2.5Ni steel was investigated to elucidate the corrosion morphology and electrochemical behavior of the as-built, 450 °C-aged, and 750 °C-aged specimens during immersion in a 3.5 wt.% NaCl solution. The results demonstrate that the inherent Mn microsegregation and high-density subgrain boundaries induced by SLM trigger preferential localized anodic dissolution on the surface of the as-built sample, culminating in the formation of a loose, porous manganese oxide product layer. Aging treatment at 450 °C induces extensive precipitation of κ-carbides within grain interiors and along grain boundaries, accompanied by localized depletion of Al and Mn at the phase interfaces. A pronounced micro-galvanic coupling established between the κ-carbides and the adjacent Al-depleted zones directly compromises the continuity of the passive film, thereby further deteriorating the corrosion resistance. In contrast, aging at 750 °C relieves the residual stress and eliminates the as-built elemental microsegregation. The resulting compositional homogenization of the matrix reduces the localized electrochemical driving force, which promotes a uniform reaction of Al at the surface to construct a continuous, compact Al-rich passive film, thereby sustaining the highest charge-transfer resistance during long-term immersion. This work elucidates the correlation among the intrinsic defects of SLM, aging-induced solute-depleted zones, κ-carbide precipitation, and localized micro-galvanic corrosion, providing a fundamental basis for tailoring the microstructure and corrosion resistance of additively manufactured lightweight steels. Full article

Selenium (Se) is a beneficial element that enhances plant antioxidant capacity, improves fruit quality, and contributes to the biofortification of horticultural crops. However, information regarding its effects on mineral nutrient balance and antioxidant metabolism in pomegranate remains limited. This study investigated the effects of foliar selenium (Se) application on fruit yield, mineral nutrient balance, antioxidant metabolism, and fruit quality of pomegranate (Punica granatum L.) cv. ‘Malas Saveh’ during the 2022 and 2023 growing seasons under orchard conditions in Iran. Trees were treated with sodium selenate at different concentrations using a randomized complete block design. In 2022, Se was applied at 0, 2, 4, and 6 mg L⁻¹, while in 2023, based on the results of the first-year screening phase, the concentration range was expanded to 0, 6, 8, and 10 mg L⁻¹ to further investigate plant responses to higher Se levels. Foliar Se application significantly increased fruit yield, fruit number, and Se accumulation in both leaves and fruits, confirming the effectiveness of Se biofortification. Selenium treatments also improved the nutritional composition of pomegranate fruits by increasing the concentrations of nitrogen (N), phosphorus (P), potassium (K), iron (Fe), and zinc (Zn), whereas manganese (Mn) concentrations declined, suggesting an antagonistic interaction between Se and Mn uptake. Significant improvements were observed in fruit quality traits, including soluble solids content, titratable acidity, vitamin C, total phenolics, anthocyanins, and antioxidant activity. The 6 mg L⁻¹ treatment in 2022 and the 8–10 mg L⁻¹ treatments in 2023 resulted in the most pronounced physiological and biochemical responses, with 10 mg L⁻¹ showing no further significant improvement for several key traits. Selenium application also enhanced the antioxidant defense system through increased activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), phenylalanine ammonia-lyase (PAL), and ascorbate peroxidase (APX), while reducing hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and membrane ion leakage. Principal component analysis further confirmed the strong positive association between higher Se concentrations and improved mineral and biochemical characteristics. Overall, foliar Se application effectively enhanced pomegranate productivity, nutritional quality, antioxidant capacity, and physiological performance, highlighting its potential as a sustainable agronomic practice for the production of high-quality Se-enriched fruits. Full article

This article describes the mineralogical and geochemical features of the Marsyaty Mn–Fe sedimentary deposit in the Northern Urals (Russia). Oolitic ironstones of the deposit are localized in the Cenomanian coastal sandstones. Manganese ores (carbonate and carbonate–oxide types) lies within the Lower Paleocene siliciclastic sediments and are separated from the oolitic ironstone (iron oxide and iron carbonate types) by a polymictic gravelite bed. Authigenic Fe³⁺ oxyhydroxides (goethite and ferrihydrite), chamosite/berthierine and late siderite predominate in the ironstones; kaolinite, apatite, perhamite, calcite and dolomite are minor constituents. Rhodochrosite and rancieite are the major minerals of the manganese ore; Mn-dominated phyllosilicates (parsettensite? and caryopilite?) are rare. Both ore types contain authigenic glauconite, montmorillonite, sulfides (sphalerite/wurtzite, galena, and pyrite), gibbsite/boehmite and REE phosphates. Both ore types contain detrital quartz, ilmenite, zircon, monazite, epidote, titanite, muscovite and feldspars. The δ¹³C_carb value (VPDB) varies from −18.5 to −23.3 in both ironstone types and from −10.0 to −41.0 ‰ in the manganese ore. The negative C isotopic composition and numerous organic remains indicate the involvement of microbial processes in the formation of both types of carbonate ores. The Fe and Mn ores belong to one transgression–regression sedimentation cycle and formed consecutively during the evolution of the West Siberian basin. A unique feature of the Marsyaty deposit includes two ore formation stages within a limited area and over a relatively short geological period: the accumulation of (i) oolitic ironstones enriched in Mn first and then (ii) manganese ores only. Full article

Ti₃C₂T_x MXene is an attractive conductive scaffold for lithium-ion battery anodes owing to its two-dimensional structure, hydrophilic surface chemistry, and tunable interlayer spacing; however, pristine MXene generally exhibits moderate lithium-storage capacity and suffers from restacking-induced loss of accessible active sites. In this study, Ti₃C₂T_x MXene@ZnO composites were prepared by growing ZnO on Ti₃C₂T_x MXene nanosheets with controlled growth times of 1, 2, and 3 h. The materials were characterized by FE-SEM, XRD, and N₂ adsorption–desorption measurements, and their electrochemical performance was evaluated in CR2032-type half-cells. Structural analyses showed that MZ-2h exhibited a more uniform distribution of ZnO particles, increased MXene interlayer spacing, and the highest BET surface area (42.77 m² g⁻¹) and total pore volume (0.1027 cm³ g⁻¹), whereas excessive ZnO growth for 3 h caused particle aggregation and reduced pore accessibility. Electrochemical measurements showed that MZ-2h delivered the best rate capability, maintaining 182.4 mAh g⁻¹ at 0.2 C and 48.0 mAh g⁻¹ at 5 C, together with the highest second-cycle Coulombic efficiency of 88.4%. These results demonstrate that controlling ZnO growth time is an effective strategy for balancing ZnO-derived lithium-storage contribution, particle dispersion, pore accessibility, and the MXene-based framework in Ti₃C₂T_x MXene-based hybrid anodes. Full article