Search Results (698)

This study explores how variations in mechanical alloying time and sintering temperature influence the microstructure, mechanical properties, and corrosion resistance of MnAlCuFeTi high-entropy alloys (HEAs). The MnAlCuFeTi alloy was produced by means of mechanical alloying for 5, 10, 15, and 20 h. Afterward, the alloy samples were sintered at two different temperatures: 550 °C and 650 °C. Structural properties were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). Analysis of grain sizes, calculated using the Scherrer formula from SEM images, confirmed that grain size had decreased to the nanostructured regime and that microstructural homogeneity had improved. Corrosion behavior was evaluated using polarization curves, corrosion current density (I_corr), and corrosion rate measurements. The results show that increasing the mechanical alloying time reduces the alloy’s grain size, thereby improving its mechanical and corrosion resistance. At a sintering temperature of 550 °C, I_corr and corrosion rate decrease with increasing grinding time, whereas at 650 °C, although high temperatures accelerate diffusion processes and increase phase homogeneity, they weaken corrosion resistance. These findings emphasize the importance of balancing alloying time and sintering temperature to optimize performance in high-corrosion-resistant HEA applications. Full article

Elemental migration and enrichment are important processes influencing tea plant growth and the assembly of rhizosphere bacterial communities within the rock–soil–plant continuum. This study explores how soil parent materials (granite, quartz schist, and sericite schist) are potentially associated with these processes and their observed associations with the elemental composition of tea leaves. Exploratory statistical analyses revealed distinct, lithology-specific biogeochemical patterns that serve as a foundation for hypothesis generation. In granite soils, chlorite correlated with the mobility of Cr, Pb, Cu, Ni, Mg, and Na, coinciding with shifts in the relative abundances of Verrucomicrobia, Armatimonadetes, and Chloroflexi. In quartz schist, kaolinite exhibited notable correlations with the dynamics of Pb, Cr, Ni, Zn, and As, which were statistically linked to Planctomycetes, Proteobacteria, and Acidobacteria. Complex mineral–microbe interactions were observed in sericite schist soils, where clay minerals (e.g., chlorite, illite) were closely associated with the migration of multiple elements (Pb, K, Ca, Cd, As, Al, Fe, Zn), paralleling structural variations in communities of Actinobacteria, Planctomycetes, Chloroflexi, and Proteobacteria. Potassium (K), calcium (Ca), and manganese (Mn) showed bioaccumulation tendencies in tea leaves across all lithologies, with an enrichment capacity order of Ca > K > Mn > Mg > Na > Al. Exploratory Classification and Regression Tree (CART) analysis suggested that the migration of K, Ca, Cu, Zn, and Hg corresponded most closely with their soil concentrations. Manganese (Mn) exhibited a mineral-associated trend, with kaolinite content as a potential correlate, while cadmium (Cd) migration was statistically linked to the relative abundance of Armatimonadetes. These findings highlight potential candidate relationships between mineralogy, microbes, and elemental mobility rather than confirming causal mechanisms, emphasizing the need for further validation in larger or experimental datasets. Full article

A Cu-containing FeCrMnNiAl multi-principal element alloy was processed by laser-based and electron beam-based powder bed fusion (PBF-LB/M and PBF-EB/M) to investigate processing–microstructure–property relationships. In focus were alloy variants with a relatively high Cu content. Two PBF-LB/M scan strategies, employing a Gaussian beam with and without a re-scan with a laser featuring a flat-top profile, were compared to PBF-EB/M processing, followed by heat-treatments between 300 °C and 1000 °C. The phase constitution, elemental partitioning and grain boundary characteristics were analyzed by X-ray diffraction, electron backscatter diffraction and energy-dispersive X-ray spectroscopy. Mechanical behavior was assessed by hardness and tensile testing. Both manufacturing routes promoted the evolution of stable multi-phase microstructures composed of face-centered-cubic (FCC)- and body-centered-cubic (BCC)-type phases across all heat-treatment conditions. PBF-LB/M processing resulted in finer, dendritic microstructures and suppressed formation of a Cu-rich FCC phase due to higher cooling rates, whereas PBF-EB/M promoted the evolution of Cu-rich FCC segregates and equiaxed grain morphologies. Heat-treatment above 700 °C led to recrystallization, accompanied by an increase of the FCC phase fraction, grain coarsening, and recovery. At lower heat-treatment temperatures, the changes in microstructure are different. Here, it is assumed that small, non-clustered Cu-rich precipitates formed at the grain and sub-grain boundaries, although this assumption is only based on the assessment of the mechanical properties. The size of these precipitates is below the resolution limit of the techniques applied for analysis in the present work. Additional structures seen within the Cu-rich areas of PBF-EB/M-manufactured samples treated at lower temperatures also seem to have an influence on the hardness and yield strength. All of the conditions investigated exhibited pronounced brittleness, limiting reliable tensile property evaluation and indicating the need for further optimization of processing strategies and microstructural control for high-Cu-fraction-containing multi-principal element alloys. Full article

Cemented carbides are essential in applications requiring exceptional hardness and wear resistance. However, the reliance on cobalt as a binder raises concerns related to cost, supply security, and health. High-entropy alloys (HEAs) are promising cobalt-free binders offering favorable mechanical properties and potential grain-growth control. This work presents a new approach for the development of Co-free WC-based cemented carbide employing an HEA binder designed through CALPHAD-guided simulations. An optimized composition corresponding to Al5Cr5Cu10Fe35Mn10Ni35 (at%) alloy is predicted to be FCC-dominant with minimal σ-phase formation and good compatibility with WC. A preliminary batch of powder of the proposed binder was produced by blending elemental powders, arc remelting, and ultrasonic atomization, yielding predominantly spherical particles with a dendritic microstructure. WC–HEA composites (WC–12 wt% HEA) were then prepared by ball milling, pressing, vacuum sintering, and sinter-HIP for a first evaluation of the microstructure and achievable hardness. The microstructure exhibited residual porosity without significant WC grain coarsening. XRD analyses showed the dominant presence of WC, along with FCC and M₃W₃C phases (M mainly Fe and Mn), indicating thermal interaction between the binder and WC. Despite these effects, the composite achieved a hardness of 1913 HV and retained a fine WC grain size (0.86 μm). The proposed design approach allowed the definition of a promising Co-free binder composition based on HEA with the expected microstructure, which will need further evaluation, especially aimed at investigating toughness properties as a function of the WC content. Full article

As a new generation of structural materials, Fe-Mn-Al-C lightweight steels with low density, high strength, and excellent strength-toughness properties have shown significant application potential in fields such as transportation, aerospace, and energy equipment. In the present work, the effects of Mo alloying and annealing processes on the microstructural evolution and mechanical properties of Fe-18Mn-8Al-1C-3Cu lightweight steel are investigated. Due to the addition of Mo, the recrystallization temperature is significantly increased, and the recrystallization process is delayed. The fine and dispersed Mo₆C precipitated phases can effectively impede dislocation movements and pin the grain boundaries, hindering recrystallization and grain growth. After annealing at 900 °C, the yield and tensile strengths of the Mo-alloyed steel were enhanced, achieving 1181 MPa and 1345 MPa, respectively, while maintaining an elongation of 24%, thus exhibiting excellent comprehensive performance. Quantitative analysis of strengthening mechanisms confirmed that the strength enhancement primarily resulted from the synergistic contributions of grain refinement strengthening (~152 MPa), solid solution strengthening (44 MPa), dislocation strengthening (131.6 MPa), and Mo₆C precipitation strengthening (52.23 MPa). Through Mo alloying and annealing process optimization, a high-strength, ductile lightweight steel was successfully developed, providing theoretical foundations and technical pathways for its application in high-performance structural materials. Full article

Heavy metal contamination of surface waters poses serious environmental and public health concerns, particularly in industrialized river basins. This study presents an integrated assessment of heavy metal pollution and associated human health risks in the Nilüfer Stream (Bursa, Türkiye) based on a five-year monitoring dataset (2020–2024). Seasonal water samples collected from 15 stations along the main stream and its tributaries were analyzed for total concentrations of As, Al, B, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. Pollution levels were evaluated using the Heavy Metal Pollution Index (HPI), Heavy Metal Evaluation Index (HEI), and Degree of Contamination (Cd), while non-carcinogenic and carcinogenic health risks for adults and children were assessed via ingestion exposure following USEPA guidelines. Mean concentrations of Al, Fe, Mn, As, and Ni exceeded international drinking water guideline values, indicating significant contamination within the basin. All indices classified the Nilüfer Stream as severely polluted (HPI = 274.32; HEI = 49.59; Cd = 49.59), with higher values during summer and autumn due to reduced dilution. Principal component analysis revealed strong associations among Al, Fe, Mn, Ni, Cr, and Cu, suggesting a common origin likely related to cumulative anthropogenic inputs, while arsenic exhibited a distinct pattern linked to toxicological risk. Health risk assessment showed that the hazard index exceeded safe thresholds for both age groups, with children being more vulnerable. Arsenic and nickel were the main contributors to both non-carcinogenic and carcinogenic risks, with arsenic posing an unacceptable lifetime cancer risk. Overall, the results indicate severe cumulative heavy metal pollution and associated health risks, highlighting the need for continuous monitoring, effective pollution control, and integrated river basin management. Full article

The antimicrobial activity of multicomponent, magnetron-sputtered glass coatings was evaluated against phytopathogenic fungi (Botrytis cinerea, Fusarium oxysporum, Cladosporium fulvum, Alternaria solani) and the chromista Phytophthora infestans, with Aspergillus fumigatus included as a model opportunistic pathogen. Fourteen Cu-based multicomponent coatings were deposited on glass using multi-alloy targets composed of Sn, Zn, Al, Ni, Fe, Ti, Mn, Nb, or Co in two high-transmittance variants (≥85% and ≥88%). Antimicrobial activity was assessed in two assays: (A) spore survival after 24–72 h contact, and (B) hyphal growth over 7 days following coating exposure under light and dark conditions. Spore viability decreased after incubation on high-Cu coatings, which showed inhibition for most strains, particularly B. cinerea, F. oxysporum, and P. infestans. The effects on spore germination were independent of the direct transmittance value of the coated glass. Hyphal growth was generally less affected by a high Cu content for most strains. Hyphal growth of F. oxysporum, C. fulvum, A. solani and B. cinerea was reduced by up to 30% on selected multicomponent coatings. For most strains, hyphal growth showed no inhibition after light incubation on coatings. However, light-dependent effects were observed for A. solani, A. fumigatus and P. infestans, while B. cinerea and C. fulvum showed reduced sensitivity during the first two days. High-Cu coatings were most effective at inhibiting spore germination, whereas hyphal growth on multicomponent coatings may respond to different ions. Therefore, high-Cu, two-component coatings may be recommended for practical greenhouse applications. Full article

The elemental composition of the vitreous humor may reflect physiological and pathological processes occurring in the eye. The objective of this study was to provide a complex multielemental analysis of human vitreous humor. Vitreous humor samples (n = 57) were collected post-mortem during autopsies. Inductively coupled plasma mass spectrometry (ICP-MS) was employed to quantify micro-, trace-, ultra-trace, and toxic elements. The study showed the occurrence of elements at the ppm (Na, K, P, Ca, Mg), ppb (Al, Rb, Zn, Fe, Sr, Cu), and ppt (Ce, La, Nd, Tb) levels. Hierarchical clustering using Ward’s method and k-means analysis revealed four distinct clusters, including two major clusters representing the baseline macro- and microelement profile characteristic for the studied population. Correlations between elements revealed statistically significant (p < 0.05) positive and negative correlations between elements with (I) chemical similarity Ce-La, Cs-Rb, Rb-K, Ca-P, Zn-Cu, and Cs-K; (II) a possible common environmental origin, Cd-P, and Rb-P; (III) involvement in similar biological processes as K-P; and (iv) a common geochemical origin and similar biological functions, i.e., Se-Zn. The study identified several quantitative trends in the demographic and medical characteristics of the participants. Alcohol users had significantly higher Zn concentrations than non-alcohol users; women had significantly higher Ca concentrations than men; higher BMI correlated positively with Cs and negatively with Be and Cr levels; and Cu, Sb, Cd, Se, and Ca concentrations increased with age. The presence of several toxic and potentially toxic elements was identified in the vitreous body: Al (>10 ppb); Cd, Cr, Pb, Ni, Mn; and Ba (<10 ppb); As, Hg, Sb, Tl, Bi, Be (<1 ppb). The study showed that, within a given geographic region, the accumulation profiles of toxic metals are quite homogeneous, indicating common sources of exposure. Full article

One of the most popular food supplements among the Canary population for the treatment of insomnia and mild anxiety is Valeriana officinalis L. (valerian), whose organ of use is the root. However, this plant is susceptible to the accumulation of certain metals, and a daily multi-dose treatment may be a dosage indication/regimen as multidose therapy. Therefore, there is an interest in determining its content of metals (Cd, Pb, Al, Cr, Cu, Li, Ni, Sr, Mo, Zn, Co, Fe, B, Mn, V, Ba, K, Na, Mg, Ca) to establish the possible toxicological risk of its consumption. The concentrations were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) in a total of 23 samples (8 fragmented, 7 crushed, 8 pulverized). The Cd limit set by the European Pharmacopoeia (0.1 mg/kg) is more than doubled in six samples. The results showed that Pinisan (0.11 mg/kg), the EnRelax^® pill (0.12 mg/kg), the EnRelax^® infuser (0.13 mg/kg), Kneipp (0.15 mg/kg), Milvus (0.16 mg/kg) and one of the market samples (0.23 mg/kg) all exceed this parameter. However, the use of valerian root as a herbal plant or food supplement at therapeutic doses and in all studied dosages does not pose a toxicological risk based on the Estimated Daily Intake (EDI) of metals. Full article

Clementine, mandarin, and orange peels, which are usually discarded, can serve as promising, sustainable dietary supplements with beneficial compositions, as demonstrated in this study. Citrus peels are low in ash, fat, and protein, but high in moisture, fibre, sugar, and polyunsaturated fatty acids (PUFAs) (up to 60%). They contain high levels of omega-3 and omega-6 fatty acids, up to 30% each, making them a good health-promoting source, as shown by the values of nutritional indices as follows: PUFA/saturated fatty acid (SFA) (1.94 to 2.30), monounsaturated fatty acid (MUFA)/SFA (0.39 to 0.84), and PUFA/MUFA (2.37 to 5.82). Essential macro elements (K > Ca > Mg > S > P > Na) and trace elements (Fe > Zn > Mn > Cu > Cr > Mo > Co > Se) are unevenly distributed among the peels, along with non-essential elements, with Al (37 to 51 mg/kg) and Sr (17 to 30 mg/kg) predominating. Rare elements in food, such as V and W, are found up to 41 and 79 µg/kg respectively, followed by Nb > Ga > Y > Ge (5 to 11 µg/kg). Although citrus peels have a nutrient-dense composition, their monitoring must be ensured before inclusion in the common diet, particularly regarding non-essential elements, as for most of them the reference doses are not established and they could be harmful to human health. Full article

We have investigated the major- and trace-element composition of hydrothermal pyrite, magnetite, and Ti-magnetite, and of the principal Cu-minerals chalcopyrite and chalcocite, to constrain ore-forming processes in the northeastern Saveh district (central Urumieh–Dokhtar magmatic arc, Iran). Our data provide new constraints on the magmatic–hydrothermal evolution and subsequent hydrothermal–supergene modification of the ore system. Ti-magnetites hosted in monzodioritic intrusions are enriched in Ti–V–Al, plot below the magnetite–ulvöspinel join and record high crystallization temperatures (<500 °C) under relatively low oxygen fugacity. By contrast, magnetite from silica-rich hydrothermal veins is Fe-rich with very low TiO₂; it formed at intermediate temperatures (~200–300 °C) under higher fO₂ and is markedly depleted in Ti and V compared with the intrusive oxides. Textures and oxide systematics (Al + Mn vs. Ti + V; V/Ti–Fe) document repeated hydrothermal pulses, Fe²⁺ leaching and element redistribution during cooling and fluid–rock interaction. Geochemical trends indicate progressive evolution from a magmatic fluid to later meteoric water overprint, with increasing As contents reflecting cooling and mixing with meteoric waters. Vertical elemental zoning suggests that most samples represent mid- to deep-level sections of the epithermal system. Elevated Cu contents (up to 0.95 wt.%) highlight pyrite as a significant Cu host. Co/Ni ratios between 1 and 10 further corroborate a magmatic–hydrothermal origin. Chalcopyrite is the principal economic Cu carrier at Northeast Saveh. Replacement follows a temperature- and fluid-controlled pathway (chalcopyrite → covellite → chalcocite). At lower temperatures (<~200 °C) replacement proceeds more slowly, producing chalcocite/digenite under prolonged reaction conditions. Chalcocite commonly occurs as thin replacement rims and fracture fills that concentrate remobilized copper. Collectively, the investigated oxide and sulfide proxies provide robust discriminants for separating magmatic versus hydrothermal domains and for vectoring toward higher-temperature feeders and zones of remobilized copper. Full article

Amidst rapid urbanization, fine particulate matter (PM_2.5) has emerged as a critical environmental challenge in China, posing substantial health risks due to its complex composition and diverse sources. This study provides a seasonally resolved analysis of PM_2.5 composition and multi-faceted toxicity in Hefei, a major Chinese manufacturing center. PM_2.5 samples collected across four seasons were chemically characterized for water-soluble ions, carbonaceous components, metals, and polycyclic aromatic hydrocarbons (PAHs) and derivatives. Their toxicological effects were evaluated through oxidative potential (OP), cytotoxicity, and reactive oxygen species (ROS) generation in the human bronchial epithelial cell line BEAS-2B. The results reveal significant seasonal variations in PM_2.5 concentration and composition. Winter exhibited the highest PM_2.5 levels (68.31 ± 17.12 μg/m³), with enrichment of secondary inorganic aerosols (SIAs), toxic metals (Pb, Cd, As), and high-molecular-weight PAHs. Spring showed elevated crustal elements (Al, Fe, Mn), while summer had the lowest pollutant concentrations. Toxicity assays reflected the following patterns: winter PM_2.5 demonstrated the highest OP (0.1423 ± 0.0368 nmol DTT/min/μg), strongest cytotoxicity (51.85% cell viability), and greatest ROS induction (2.28-fold increase). Statistical analyses identified distinct toxicity drivers: OP was associated with SIA (NO₃⁻, NH₄⁺) and redox-active metals (Cu, Zn); cytotoxicity correlated with toxic metals and PAHs; whereas ROS showed weaker compositional correlations. This integrated “composition–toxicity” assessment reveals that the elevated health risk in winter stems from a synergistic mix of secondary aerosols and combustion-derived toxicants, urging a shift toward component-specific, risk-based air quality management strategies. Full article

This study investigates the hydrometallurgical purification of the acidic leachate from spent LiCoO₂-based lithium batteries, focusing on the selective removal of Cu, Mn, and Ni while monitoring co-precipitation of Fe and Al and minimizing Co and Li losses. Thermodynamic modelling using HSC Chemistry 10 and Hydra/Medusa guided the design of precipitation conditions. The optimal Cu precipitation was achieved using Na₂S (Na₂S:Cu = 4:1, 20 °C, 5 min, 300 rpm), yielding > 99% removal. Mn was efficiently precipitated as MnO₂ using KMnO₄ (KMnO₄:Mn = 1:1, 20 °C, pH ≈ 2, 10–15 min, ≈97% efficiency). Ni was recovered as [Ni(DMG)₂] under DMG:Ni = 5:1, 80 °C, 15 min, pH ≈ 5, achieving ≈99% removal. Sequential 2 L experiments (precipitation order: Cu → Mn → Ni) validated the scalability of the process. Cu and Ni removal remained high (>95%), while Mn efficiency slightly decreased (≈91%) due to kinetic and redox inhomogeneity. No significant precipitation of Co and Li was observed, leaving them in solution and concentrating from 12.9 to 18.8 g·L⁻¹ and 2.71 to 3.50 g·L⁻¹, respectively, with total losses of <1%. The resulting CuS, MnO₂, and [Ni(DMG)₂] precipitates exhibited moderate purity (46–63%) but represented valuable secondary raw materials. Overall, sequential precipitation under optimized conditions demonstrates robust, selective removal of accompanying metals while concentrating Co and Li, providing an efficient and scalable route for LIBs leachate valorisation. Full article

Shagamite, KFe₁₁O₁₇ (IMA 2020-091) was discovered in the ferrite zone of gehlenite hornfels from the Hatrurim Complex exposed near Mt. Ye’elim, Hatrurim Basin, Israel. The mineral occurs in outer zones of gehlenite rock blocks that were heterogeneously altered by high-temperature (>1200 °C) ferritization. Ferritization was induced by K-bearing fluids or melts, generated as a by-product of late combustion processes. Shagamite crystallized from a thin melt that formed on the rock surface during cooling to approximately 800–900 °C. It is mainly associated with minerals of the magnetoplumbite group like barioferrite, Sr-analog of barioferrite, and gorerite but also with magnetite, maghemite, harmunite, devilliersite and K(Sr,Ca)Fe₂₃O₃₆ hexaferrite. Shagamite is a modular compound with a β-alumina-type structure (P6₃/mmc, a = 5.9327 (5), c = 23.782 (3) Å, γ = 120°, V = 724.91 (13) ų, Z = 2), and it is isostructural with diaoyudaoite, NaAl₁₁O₁₇, and kahlenbergite, KAl₁₁O₁₇. Its structure is also closely related, though non-isotypic, to those of the magnetoplumbite-group minerals. Shagamite is dark brown with a semi-metallic luster and forms platy crystals flattened on (001). Its mean empirical formula is: (K_1.00Ca_0.15Mn²⁺_0.05Na_0.04Rb_0.01)_Σ1.25(Fe_10.36Mn²⁺_0.15Al_0.14Mg_0.12Zn_0.10Ni_0.07Cu_0.03Cr³⁺_0.02Ti⁴⁺_0.01)_Σ11.00O₁₇. The Vickers microhardness VHN₂₅ = 507 kg/mm² corresponds to a Mohs hardness of ~5. The calculated density, based on the empirical formula and unit-cell parameters, is 4.12 g·cm⁻³. The main bands in the Raman spectrum of shagamite occur at 685 and 715 cm⁻¹ and are assigned to ν₁(FeO₄)⁵⁻ tetrahedral vibrations. Full article

Background: Gum Arabic (GA) is a natural polysaccharide widely recognized for its antioxidant and anti-inflammatory properties; however, its functional behavior as a biopolymeric gel and the mechanisms underlying its selective effects on cancer-related redox microenvironments remain insufficiently characterized. It is imperative to note that the interaction between its physicochemical properties and its biological activity in colorectal cancer remains to be fully clarified. Methods: This study aimed to evaluate the antineoplastic potential of GA in human colorectal cancer (CRC) cell lines (HT-29 and HCT-116) compared to normal fibroblasts (MRC-5) using the MTS assay. Oxidative stress-related molecular responses were assessed by quantitative PCR analysis of GPX4, GSTA2, CAT, NFKB, and SOD1 expression. In parallel, extracellular concentrations of key metal ions (Fe²⁺, Zn²⁺, Mn²⁺, Mg²⁺, Cu²⁺, and Al³⁺) were quantified following GA exposure. To establish its functional gel characteristics, rheological measurements were performed to assess viscosity and shear-dependent behavior, and USP-compliant in vitro kinetic studies were conducted to evaluate time-dependent release properties. Results: GA induced dose-dependent cytotoxicity in HT-29 and HCT-116 colorectal cancer cells, while MRC-5 fibroblasts exhibited comparatively higher viability across the tested concentration range, indicating reduced sensitivity in normal cells. Rheological analysis revealed concentration- and ion-dependent viscoelastic behavior, identifying a 10% (w/w) GA formulation as optimal due to its balanced low-shear viscosity and controlled shear-thinning properties. Kinetic studies demonstrated a defined, diffusion-governed release profile under physiologically relevant conditions. At the molecular level, significant upregulation of GPX4 and GSTA2 was observed in both cancer cell lines, whereas NFKB expression increased selectively in HT-29 cells, with no notable changes in CAT or SOD1 expression. Additionally, GA treatment resulted in marked increases in Fe²⁺, Zn²⁺, and Mn²⁺ levels, indicating modulation of the redox–ionic microenvironment. Conclusions: These findings demonstrate that GA functions as a natural, ion-responsive biopolymeric system with defined rheological and kinetic properties, capable of selectively targeting colorectal cancer cells through coordinated genetic and ionic regulation of oxidative stress. Collectively, the results position GA as a promising functional gel-based platform for future redox-modulated therapeutic strategies in colorectal cancer. Full article