Search Results (6,201)

AlCrFeNi-based high-entropy alloys (HEAs) have attracted considerable interest owing to their adjustable phase constitution and attractive mechanical performance. In this study, AlCr_1.6Fe_xNi_(3.2−x)Si_0.2 HEAs (x = 1.0–2.0) were fabricated by vacuum arc melting to systematically evaluate the influence of the Fe/Ni ratio on phase evolution, microstructural characteristics, and mechanical behavior. The results indicate that, with increasing Fe content, the phase constitution gradually changes from BCC+B2+σ to BCC+B2. Correspondingly, the microstructure evolves from floral and cellular eutectic morphologies to branch-like BCC-rich regions with inter-branch/intercellular eutectic constituents. At the same time, the Vickers hardness decreases from 584.1 HV to 365.7 HV as the Fe content increases. Compression results show a gradual reduction in alloy strength, whereas the deformation ability is noticeably improved. Fracture surface analysis further reveals that the alloys with x ≤ 1.4 exhibit typical brittle fracture features, while those with x ≥ 1.6 display incomplete fracture and enhanced plastic deformation. These results clarify the relationship among Fe/Ni ratio, phase constitution, microstructural evolution, and mechanical properties in AlCrFeNiSi-based HEAs. Full article

Electric motors that use neodymium–iron–boron (Nd–Fe–B) magnets are at the forefront of global efforts to reduce greenhouse gas emissions. However, a major problem associated with these motors is thermal demagnetization driven by eddy current (EC) losses in the magnets; the relatively low electrical resistivity of Nd–Fe–B magnets means that the magnetic fields in the motor generate considerable EC losses. In this study, Nd–Fe–B magnets with 0–20 wt% Si additives were produced through hot pressing to investigate the effects of Si addition on magnetic properties and electrical resistivity. Small amounts of Si significantly increased electrical resistivity without negatively affecting the magnetic properties. The high coercivity of the Nd–Fe–B magnets, 12.5 kOe, did not decrease even in the presence of up to 15 wt% Si content. The electrical resistivity of Nd–Fe–B magnets increased monotonically as the Si content increased, from 1.43 μΩm for pure Nd–Fe–B magnets to 8.17 μΩm with 20% Si. As the electrical resistivity increased, the associated EC losses decreased; the estimated EC losses were halved with the addition of ~8 wt% Si, and further decreased to one-third through the addition of ~12 wt% Si, while simultaneously maintaining high coercivity. Full article

The increasing use of silver nanoparticles (AgNPs) as nanoagrochemicals raises important environmental and toxicological considerations of their usage. AgNPs influence soil microbiome functioning, which regulates essential nutrient availability. However, their effects on key chemical soil health indicators remain unclear, with existing studies limited to concentrations ≥10-fold above predicted environmental levels. The aim of the work was to evaluate the effect of AgNPs at a realistic concentration of 10 μg/kg on the principal chemical soil health indicators, including acidity, redox potential, electrical conductivity, contents of NPK, and soil organic carbon (SOC). In addition, dissolved organic carbon and nitrogen (DOC and DON) and water-extractable elements (Al, Ca, Fe, K, Mg, Na, P, S, and Si) were also examined. The laboratory experiment was carried out for 3 months on Retisol, Chernozem, and Solonetz. AgNPs stabilised with carboxymethylcellulose (AgNP-CMC) or polyvinylpyrrolidone (AgNP-PVP) were used. AgNP-induced changes exhibited non-monotonic patterns, peaking at 2–3 months of incubation. A statistically significant effect observed across all soils following AgNPs application included only increased water-extractable Fe. In addition, AgNPs increased nitrate content 1.1–1.4-fold in Retisol and Chernozem, while available phosphorus increased 1.4-fold in Solonetz. However, changes were transient, indicating no pronounced long-term impact on soil properties. Partial Least Square (PLS) analysis revealed that chemical soil health indicators and water-extractable elements do not reliably discriminate between control soils and soils amended with AgNPs. Although our study shows that AgNPs had neither markedly negative nor positive effects on chemical soil health indicators or water-extractable element contents, future research should prioritise field trials. Model experiments under optimised microbial activity conditions limit direct extrapolation to field scenarios. Full article

Precision nano-fertilization offers transformative potential for sustainable improvement of grape quality, yet the underlying molecular mechanisms remain poorly understood. Here, we investigated the effects of foliar-applied nano zero-valent iron (nZVI) and potassium dihydrogen phosphate (KH₂PO₄), in combination, on berry quality and secondary metabolic reprogramming in Vitis vinifera cv. Marselan. The combined nZVI/KH₂PO₄ treatment improved photosynthetic capacity, Fe/P co-accumulation, and berry quality traits including soluble solid content, sugar–acid ratio, and phenolic and aroma metabolite profiles. Crucially, integrated transcriptomic and metabolomic profiling identified 631 differentially expressed genes and 838 differentially accumulated metabolites, converging on flavonoid biosynthesis and glutathione metabolism as the dominant regulatory axes. Correlation network analysis pinpointed five hub regulatory genes—VvHCT, VvFLS1, VvLAR1/2, VvUGT88F5, and VvODC—as central orchestrators of nanomaterial-driven metabolic reprogramming: VvHCT and VvFLS1 coordinately redirected carbon flux toward hydroxycinnamic acid conjugates and flavonol accumulation, while VvLAR1/2 governed proanthocyanidin polymerization, and VvUGT88F5 modulated glycosylation-dependent metabolite stabilization. Notably, VvODC linked polyamine metabolism to glutathione-mediated stress buffering, revealing a previously uncharacterized crosstalk between nano-iron signaling and antioxidant reprogramming. These findings establish a mechanistic framework in which nZVI and KH₂PO₄ synergistically remodel the secondary metabolome through discrete yet interconnected transcriptional nodes, providing molecular targets for nano-enabled precision viticulture and broader applications of engineered nanomaterials in high-value crop improvement. Full article

Ceramic production technology is a key indicator of craft specialization and social differentiation in Late Neolithic societies of the Central Plains. This study investigates Longshan-period pottery excavated from three representative sites, Niumugang, Zhoulonggang, and Shigudui in western Shangqiu, Henan Province. A suite of archaeometric techniques, including X-ray fluorescence (XRF), infrared spectroscopy (IR), X-ray diffraction (XRD), differential thermal analysis (DTA), and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM–EDS), was employed to systematically examine the chemical composition, mineralogical phases, thermal behavior, and microstructural characteristics of the pottery assemblages. The results reveal statistically significant differences (p < 0.05) in the contents of major ceramic-forming oxides (SiO₂, Al₂O₃, Fe₂O₃, CaO, etc.) among the three sites. Pottery from the Shigudui site exhibits the narrowest range of compositional variation, whereas that from the Zhoulonggang site shows moderate dispersion. In contrast, pottery from the Niumugang site displays the widest compositional range. Mineralogical analyses indicate that pottery from all three sites is primarily composed of quartz, mica, and mullite. Notably, the high degree of mineralogical homogeneity observed in the Shigudui assemblage reflects a well-controlled and technologically mature firing process. Microstructural observations further demonstrate that pottery from the Shigudui site is characterized by uniformly dense fabrics, functionally differentiated vessels from the Zhoulonggang site exhibit clear technological stratification, and black pottery from the Niumugang site shows highly compact microstructures. These technological patterns closely correspond to differences in vessel assemblages and indicate varying levels of craft specialization and production control. Together, the results provide archaeometric evidence for the differentiation of settlement hierarchy and the development of specialized handicraft production during the Longshan period, contributing to a deeper understanding of regional technological interaction and social processes within the Longshan cultural sphere of the Central Plains. Full article

Calcium carbide slag is a highly alkaline solid waste generated during acetylene production, but its long-term accumulation causes land occupation and persistent environmental risks such as soil alkalinization and water pollution. To support circular economy and carbon emission reduction goals, in this study, we develop an integrated physical decontamination–mineralization process combining calcination, magnetic separation, sedimentation, and CO₂ mineralization. After calcination, magnetic separation, and 8 h of gravity sedimentation, the removal efficiency of Si reaches about 67% (residual Si content reduces to 0.43%), while those of Fe and Al are 75.4% and 74.2%, respectively. The purified calcium-rich slurry is then used for CO₂ mineralization. Under a solid-to-liquid ratio of 10% and a CO₂ flow rate of 0.4 L/min, CO₂ is fixed as carbonate solids, yielding calcite-type CaCO₃ with 97.88% ± 0.35% purity. This process is centered on physical separation and uses no acids, alkalis, or ammonium salts, avoiding secondary pollution while achieving waste valorization and permanent CO₂ sequestration. In this study, we provide a scalable, low-impact pathway for alkaline solid waste valorization and carbon emission reduction, contributing to sustainable consumption and production (SDG 12) and climate action (SDG 13). Full article

The unique powder-pack boriding technique using an open retort with boriding medium was applied for the first time in order to produce boride layers on K190 ledeburitic chromium steel manufactured using powder metallurgy. The processes were carried out using the commercial Durborid^®G powder mixture at 1173 K, 1223 K, and 1273 K for 3 h, 6 h, and 9 h. As a result of the boriding of the high-carbon and high-chromium substrate, three zones were revealed in the produced surface layers: the outer FeB zone, the inner Fe₂B zone, and the transition zone, with increased carbon content. The total thickness of the boride layers (FeB + Fe₂B) ranged from 14.13 µm at the lowest temperature and shortest time to 65.49 µm at the highest temperature and longest duration. Increasing the temperature and extending the boriding time resulted in a deeper FeB zone as well as a thicker total layer (FeB + Fe₂B). The growth kinetics of the produced layers on the surface of K190 steel were analyzed for the first time using the mean diffusion coefficient model. The thicknesses of the FeB zone and the total layer (FeB + Fe₂B) were determined. The activation energies of boron for the FeB and Fe₂B phases calculated in this work are comparable with other results for the powder-pack boriding of high-carbon tool steels. As a consequence of the high chromium content in K190 steel, chromium borides were observed in the boride zones, which increased the hardness of the surface layer. The highest temperature used resulted in the formation of vanadium borides. The presence of the transition zone with an increased carbon concentration and a high percentage of carbides resulted from the movement of carbon atoms toward the core by the advancing boron diffusion front. The parameters of boriding (temperature and time) as well as the presence of alloying elements in the substrate material influenced the microhardness of the boride layers. Full article

Tribocorrosion is one of the main degradation mechanisms affecting metallic components exposed simultaneously to mechanical wear and electrochemical corrosion. In this work, the influence of the Nb/Ti ratio on the tribocorrosion behavior of Fe–Cr–Mo–Nb–Ti multicomponent alloys produced by vacuum arc melting was investigated. The alloys were designed through systematic variations in the relative contents of niobium and titanium to assess their effect on electrochemical stability, wear resistance, and surface degradation. Electrochemical behavior was evaluated by potentiodynamic polarization in a 3.5 wt.% NaCl solution, while tribological and tribocorrosion tests were conducted using a ball-on-disk configuration under controlled conditions. Post-test surface analysis was performed using stereomicroscopy combined with digital image processing, enabling three-dimensional topographical reconstruction of the wear tracks and extraction of quantitative parameters including groove depth, pile-up height, wear track width, and surface roughness. The results demonstrate that the Nb/Ti ratio significantly influences both electrochemical and tribological responses. The alloy with the highest Nb/Ti ratio exhibited the best overall performance, showing the lowest corrosion current density (5.37 × 10⁻⁸ A/cm²) under static conditions and the lowest wear rate (1.32 mm³/mm²·year), together with the least severe surface degradation, characterized by a groove depth of approximately 7.8 µm and minimal pile-up formation. A progressive deterioration in performance was observed as the Nb/Ti ratio decreased, with the lowest-ratio compositions presenting higher wear severity and surface instability. The AISI 316L reference material exhibited intermediate performance across all evaluated parameters. Overall, increasing the Nb/Ti ratio enhances passive film stability, reduces plastic deformation, and mitigates material removal under tribocorrosion conditions. The incorporation of three-dimensional surface analysis provides a more robust evaluation of wear mechanisms, supporting the design of multicomponent alloys with improved resistance to combined mechanical and electrochemical degradation in aggressive environments. Full article

A one-pot strategy was developed for preparing a chitosan/Mg–Fe layered double hydroxide (LDH) composite by alkaline coprecipitation from an acidic chitosan solution containing Mg(II) and Fe(III) precursors, avoiding separate LDH synthesis and subsequent incorporation into chitosan. X-ray diffraction confirmed LDH formation within the chitosan matrix, and ICP analysis indicated an LDH-equivalent content of approximately 4.1 wt.% on an anhydrous basis. The composite exhibited enhanced chromate adsorption compared with both starting components. The experimental plateau adsorption capacity reached 137.4 mg/g, exceeding those of chitosan (92.2 mg/g) and Mg–Fe LDH (53.5 mg/g). Nonlinear isotherm fitting showed that Mg–Fe LDH was better described by the Freundlich model, whereas chitosan and the composite were better described by the Langmuir model. The kinetic behavior followed the pseudo-second-order equation, while Weber–Morris analysis indicated multistep uptake involving surface interaction and diffusion-related processes. In simulated groundwater containing chloride, bicarbonate, and sulfate, the composite removed 82% of Cr(VI) at 1.0 g/L. It also retained complete chromate uptake over five sorption/desorption cycles, although desorption efficiency decreased from 97.3% to 90.3%. A limitation of this study is that performance was evaluated mainly in batch systems and simplified simulated groundwater; validation with real contaminated waters and dynamic flow conditions is still required. Full article

Iron-exchanged bentonites derived from a natural montmorillonite-rich clay (Taganskoe deposit, Kazakhstan) were prepared through a simple aqueous ion-exchange route using Fe(II) or Fe(III) inorganic salt precursors, yielding final Fe contents of ca. 5–7 wt.%, while preserving the smectite layered framework. A mild thermal treatment under air was applied to tune iron coordination without triggering major structural collapse. The resulting materials were characterized by ED-XRF, PXRD, FE-SEM/EDX, DLS/ζ-potential and DR UV–Vis–NIR spectroscopy, revealing predominantly exchanged Fe species with a limited fraction of surface iron-oxide clusters, whose contribution increases after activation. Structure–reactivity relationships were probed under mild conditions in liquid-phase ethyl acetate using dimethyl methylphosphonate (DMMP) and 2-chloroethyl ethyl sulfide (2-CEES) as organophosphorus and organosulfur hazardous chemicals and chemical warfare agent simulants, respectively. Fe(III)-bentonite enabled very fast DMMP removal (ca. 93% within 0.5 h) with a remarkable improved performance with respect to Fe(II)-bentonite and the pristine mineral clay. For 2-CEES, the presence of H₂O₂ markedly enhanced oxidation on Fe-containing clays, reaching quantitative abatement within 24 h (up to >90%), with strong retention of oxidized sulfur products by the clay matrix. These results highlight Fe-exchanged natural bentonites as robust, cheap and multifunctional adsorption/catalytic solids for decontamination and water-treatment applications. Full article

Metallic glasses can be transformed into nanocrystalline–amorphous alloys via controlled crystallisation with fast nucleation and slow grain growth. This can be achieved either through appropriate chemical composition of amorphous precursors or by applying ultra-rapid annealing (URA). Typically, heating between preheated copper blocks is used to ensure the URA conditions. In this work, ribbons were heated by an electric current flowing along their length, and the temperature was monitored using pyrometers. The investigated alloys were Fe_86-xNi_xB₁₄ (at. %), where x = 4, 6 or 10. Properly adjusted isothermal annealing at 380–410 °C for 1–20 s induced crystallisation, with the nanocrystalline bcc-Fe(Ni) phase occupying 0–55% of the volume. With increasing annealing time, the coercive field increased from 9 A/m in the amorphous state to 25 A/m and 17 A/m for x = 4 and x = 10, respectively. Transmission electron microscopy confirmed that samples annealed at higher temperatures for shorter times exhibited smaller grain sizes compared to those annealed at lower temperatures for longer times, which resulted in improved magnetic softness. An increase in nickel content reduced coercivity, improved ductility, and offered a wider window for the choice of annealing temperature. Full article

Hot-press forming (HPF) steel is a promising lightweight material for automotive applications but suffers from oxidation and reduced corrosion due to high-temperature processing. Aluminized coatings, particularly Al-10Si, are widely used to mitigate this issue. However, HPF heat treatment can create brittle alloy layers with cracks, compromising retention and increasing corrosion risk. This study investigated the effects of Sr addition on the microstructure and corrosion resistance of Al-Si-coated HPF steel. Al-Si and Al-Si-Sr coatings were applied to steel substrates and subjected to heat treatment to produce heat-treated (HT) Al-Si and HT Al-Si-Sr samples. Sr addition refined and spheroidized eutectic Si particles, improved coating homogeneity, and mitigated vertical crack formation in the Al-Fe-Si intermetallic layer. The resulting dense, crack-free alloy layer effectively shielded the Fe substrate from corrosion. After heat treatment, Sr facilitated the formation of a fine lamellar microstructure and a dense, continuous oxide film, enhancing coating retention and sustaining barrier protection. These improvements significantly delayed corrosion propagation into the Fe substrate. Corrosion resistance was evaluated using salt-spray tests (ASTM B117), potentiodynamic polarization, and electrochemical impedance spectroscopy in 3.5 wt.% NaCl solutions. Microstructural analyses revealed that even minimal Sr content (0.05%) considerably enhanced the performance of Al-Si coatings, demonstrating industrial applicability. This study highlights the potential of Sr-added Al-Si coatings in addressing the demand for lightweight and corrosion-resistant materials in the automotive industry, offering a viable solution for high-performance and environmentally sustainable applications. Full article

Portable X-ray fluorescence (pXRF) is increasingly used as a rapid and cost-effective technique for soil analysis; however, its comparability with laboratory-based methods remains uncertain. This study aimed to evaluate the applicability of pXRF for determining the concentrations of six elements (K, Ca, Fe, Pb, Mn, and Zn) in agricultural soils classified as Albic Luvisols with a loamy sand texture. A total of 96 dried, ground soil samples from a long-term fertilization experiment were analyzed using pXRF and compared with inductively coupled plasma mass spectrometry (ICP-MS) following aqua regia digestion. Association and agreement between methods were assessed using correlation analysis, Deming regression, Lin’s concordance correlation coefficient (CCC), and Bland–Altman analysis. Substantial differences were observed between the two methods. The mean pXRF/ICP-MS ratios were approximately 25 for K, 4.0 for Ca, 1.43 for Fe, 1.41 for Mn, 1.21 for Pb, and 1.06 for Zn. The observed discrepancies are attributed to methodological factors. In particular, ICP-MS after aqua regia digestion represents pseudo-total concentrations, whereas pXRF measures total solid-phase content. Bland–Altman analysis revealed substantial systematic differences between methods. The largest biases were observed for K (−13,110 mg kg⁻¹) and Ca (−2904 mg kg⁻¹), indicating differences spanning several orders of magnitude. Smaller biases were found for Fe (−1179 mg kg⁻¹), Mn (−50.0 mg kg⁻¹), Pb (−2.37 mg kg⁻¹), and Zn (−1.30 mg kg⁻¹). The limits of agreement were particularly wide for K and Ca, whereas Zn exhibited the narrowest range. CCC values confirmed poor agreement for most elements (0.00049–0.36), with Zn showing the highest concordance (0.89). Overall, in the study condition, Zn demonstrated the best agreement between methods. Moreover, the results highlight that correlation-based metrics alone are insufficient for comparing methods and should be complemented by agreement-based approaches. Full article

This work investigated the effect of yttrium addition on the pre-oxidation behavior of Fe–25Ni–20Cr–4Al–1Nb–1Mn–1.5Si-based alloys at 1000 °C in a 4% H₂ + 0.2% CH₄ + Ar + 0.25% H₂O atmosphere. The oxidation resistance and oxide scale adhesion were evaluated through cyclic oxidation tests and micro-scratch measurements. Results show that the Y-free alloy formed a discontinuous oxide layer, whereas all Y-containing alloys formed a continuous and dense Al₂O₃ scale. Incorporating 0.2 wt.% Y increased the work of adhesion by approximately 7 to 9 times relative to the Y-free sample, indicating a pronounced interfacial strengthening effect. The role of yttrium content and oxygen partial pressure in promoting alumina-scale formation was discussed based on thermodynamic considerations and microstructural evidence. Full article

The search for a healthy diet has increased the consumption of kale, a vegetable recognized for its high nutritional value, mineral content, and antioxidant properties. Phosphorus is an essential nutrient in this context, acting in energy transfer and root development, which favors productivity and product quality. This study evaluated the effect of two phosphorus sources, bone meal (BM) and thermophosphate Yoorin^® (TY), and five phosphorus (P₂O₅) doses (0, 160, 320, 480, and 640 kg ha⁻¹) on kale yield and quality. The experiment used a randomized complete block design with four replications and ten treatments in a 2 × 5 factorial arrangement in a protected environment over a cycle of 155 days after transplanting. Marketable yield with BM reached an estimated maximum of 1.54 kg plant⁻¹ at 525 kg ha⁻¹ P₂O₅ (54% over control), while TY showed a linear increase up to 1.57 kg plant⁻¹ (59%). Photosynthetic pigments, antioxidant activity, ascorbic acid, and total phenolic compounds fitted quadratic models, with gains of up to 36%, 73%, 51%, and 57%, respectively. Contents of P, K, Ca, and Fe increased significantly with P doses, with Fe gains reaching 110–180%. Phosphate fertilization with BM, a renewable P source, increases kale yield and nutritional quality, highlighting its potential for organic farming systems. Full article