Search Results (725)

In this study, manual welding electrodes with varying niobium (Nb) contents (0, 0.05, and 0.1 wt%) were developed for 960 MPa grade low-alloy high-strength steel, and deposited metals were produced through multilayer multipass welding. Microstructural characterization and mechanical testing were performed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and a universal testing machine to investigate the influence of Nb content and elucidate the strengthening mechanisms. The results demonstrate that under identical welding conditions, multipass thermal cycles induced a primary microstructural transformation from martensite to tempered martensite in all deposited metals, which predominantly comprised tempered martensite with minor fractions of bainite and second-phase particles. Increasing Nb content led to significant grain refinement. The second-phase particles exhibited sizes of 0.158 μm, 0.176 μm, and 0.168 μm, respectively, with volume fractions of 5.69%, 5.82%, and 5.90%. Nb addition substantially enhanced hardness and strength while causing a noticeable reduction in low-temperature impact toughness, though the values remained within acceptable limits. The deposited metal containing 0.05 wt% Nb exhibited optimal comprehensive mechanical properties, with a hardness of 386.7 HV, tensile strength of 1060 MPa, yield strength of 962 MPa, and Charpy impact energies of 41.95 J and 33.17 J at −40 °C and −60 °C, respectively. Theoretical calculations revealed that the dislocation strengthening contribution in martensite increased from 526 MPa to 600 MPa with increasing Nb content, representing the dominant strengthening mechanism, while grain refinement strengthening increased from 135.5 MPa to 157.6 MPa. Full article

M-type hexaferrites are widely used in magnetic applications, and tailoring their properties via aliovalent substitution requires a detailed understanding of charge compensation and cation distribution. In this work, Mg²⁺/M⁴⁺ (M = Zr, Hf) co-substituted BaFe₁₂O₁₉ was synthesized via Na₂CO₃ flux and comprehensively characterized by wavelength-dispersive X-ray spectroscopy, powder and single-crystal X-ray diffraction, Rietveld refinement, X-ray absorption near-edge structure, and magnetic measurements. Increasing substitution levels x, y in BaFe_12−x−yMg_xM_yO₁₉ result in increasing lattice parameters and decreasing the room-temperature magnetic parameters saturation magnetization, remanence, and coercivity, while remanence and coercivity increase at low temperatures. Secondary phases form for nominal substitution ≥ 1. Zr⁴⁺ and Hf⁴⁺ preferentially occupy the 4f₂ site, whereas Mg²⁺ is distributed over multiple sites, as indicated by polyhedral volume analysis. Wavelength-dispersive X-ray spectroscopy confirms homogeneous elemental distribution within individual crystals but reveals significant variation in substitution levels within batches. The maximum degree of substitution for the tetravalent metals was y ≈ 1.2–1.7, with lower Mg incorporation of x ≈ 0.9–1.1. Charge compensation was found to be partially achieved via vacancy formation, while minor Fe²⁺ contributions cannot be excluded. Full article

The global transition toward green energy has increased demand for metals and intensified the need for sustainable supply sources. Tellurium (Te), an essential metal for photovoltaics technology, is produced primarily as a by-product of copper refinery slimes treatment. This study conducts a life-cycle assessment (LCA) study of Te production to investigate the effect of environmental impact allocation choices on LCA results in multi-product metal systems. A cradle-to-gate LCA model of the Te product system was developed in SimaPro v9.5.0.1 software by combining industrial data, Ecoinvent v3.7.1 datasets, and literature information. Environmental impacts were quantified using the ReCiPe v1.04 Midpoint method for a functional unit of 1 kg of refined Te. The product system’s multi-functionality was investigated using mass and economic allocation and a system sub-division method. Sensitivity analyses examined the effects of the Te concentration in anode slimes and their recovery efficiency on impact estimates. The results show that mass allocation assigns higher burdens to Te than economic allocation does. System sub-division yields significantly lower impacts than allocation procedures by attributing burdens only to Te-specific recovery processes. Higher Te grades and improved recovery efficiencies markedly reduced impact estimates. These findings demonstrate the importance of allocation choices on the LCA of by-product metals. Full article

The increasing demand for sustainable and lightweight furniture systems has driven interest in additively manufactured polymer components as alternatives to conventional metal hardware. However, their performance at the functional assembly level under standardized loading conditions remains insufficiently explored. This study evaluates the feasibility of replacing metal drawer slides with fused deposition modeling (FDM)-based polymer alternatives fabricated from polylactic acid (PLA) and polyethylene terephthalate glycol (PETG). Unlike previous studies focused on material-level characterization, this work investigates fully functional drawer slide assemblies integrated into medium-density fiberboard (MDF) systems, enabling component-level assessment under realistic conditions. Specimens were designed in SolidWorks and fabricated under controlled printing parameters. Commercial metal slides were used as benchmarks. Mechanical performance was tested according to BS EN standards, and deformation was measured at multiple points. Statistical analysis included ANOVA, Tukey HSD, and t-tests at a 95% confidence level. Results showed significant differences among materials (p < 0.05). Metal slides exhibited the highest stiffness and minimal deformation. PLA showed stable performance with minor surface degradation, while PETG demonstrated lower dimensional stability and premature failure due to higher compliance. Overall, PLA-based FDM components offer a cost-effective alternative for non-heavy-duty applications, whereas PETG requires further optimization. The study bridges additive manufacturing and real-world furniture component performance under standardized testing. Full article

Phytoremediation is a sustainable approach for the remediation of heavy metal–contaminated soils; however, the management of contaminated biomass generated during this process remains an insufficiently addressed challenge. Such biomass constitutes a secondary waste stream that may release mobile pollutants and pose environmental risks. In this study, an integrated ecotoxicological assessment framework was applied to evaluate phytoremediation-derived biomass and its transformation products obtained via pyrolysis. Two types of woody biomass with different heavy metal contents and their corresponding biochars produced at 700 °C were investigated. A multitrophic battery of bioassays combining direct exposure assays using terrestrial organisms (higher plants, Eisenia fetida, and soil microbial activity) with leachate-based assays using aquatic organisms (Lemna minor, Daphnia magna, and Aliivibrio fischeri) was applied. Untreated biomass exhibited high to extreme toxicity in aquatic systems (toxic units, TU >100) and significant phytotoxic effects. Pyrolysis substantially reduced contaminant mobility and ecotoxicity of leachates, resulting in lower toxicity (TU typically <15) and no significant effects on plant growth, earthworm survival, or soil microbial functional diversity. Residual toxicity was linked to elevated pH and trace amounts of thermally generated organic substances. These results demonstrate that pyrolysis effectively reduces the environmental risk of contaminated biomass and supports the use of multitrophic ecotoxicological testing for safe waste valorization within circular economy strategies. Full article

The Heilongtai–Maogudui (HM) mafic intrusions are exposed in the southern margin of the North China Craton (SNCC), which are contemporaneous with a variety of strategic metal/non-metal minerals (niobium, uranium, and high-purity quartz) and magmatic hydrothermal REE deposits. New geochronology and geochemistry of these intrusions are examined and interpreted to decipher their petrogenesis and tectonic settings. Zircon LA–ICP–MS data formed a concordant cluster, yielding a mean ²⁰⁶Pb/²³⁸U age of 397.5 ± 3.5 Ma, which is interpreted as an Early Devonian crystallization age. The HM mafic intrusions have similar whole-rock geochemical compositions, containing 48.94–51.51 wt% SiO₂, 1.26–1.61 wt% TiO₂, 5.96–7.13 wt% MgO, and 11.00–12.48 wt% FeO_t. The total alkali contents range from 1.61 wt% to 3.53 wt%, with Mg^# values of 47.23–52.30. The petrographic and geochemical results suggest the fractional crystallization of mainly olivine, clinopyroxene, and minor Fe–Ti oxide in the mafic intrusions. Being of tholeiitic composition, these mafic rocks display relatively flat rare earth element (REE) and trace element patterns, which are similar to those of the normal mid-ocean ridge basalt (N–MORB) and the enriched mid-ocean ridge basalt (E–MORB). The HM mafic intrusions are proposed to originate in the continental extensional environment through 5–10% partial melting of the depleted spinel asthenosphere mantle source. This is attributed to the gravitational delamination of the lithospheric mantle and the upwelling of the hot asthenosphere, marking the end of the Paleozoic Proto–Tethyan orogenic cycle. The Paleozoic strategic mineral deposits are proposed to have formed under this specific tectonic regime. Full article

To address the limitations of the traditional cross-scanning method in absolute calibration of weather radars using metal spheres, including insufficient spatial coverage, limited target acquisition efficiency, and echo underestimation in inter-range bins, this study proposes a sector scanning field calibration method. In this approach, standard metal spheres are suspended from UAVs, and a three-dimensional scanning volume around their theoretical positions is constructed to enable high-density echo sampling. By applying drive backlash correction, quadratic Gaussian surface fitting, and three-dimensional ellipsoid model inversion, key radar parameters can be retrieved. Experimental results show that the improved sector scanning method enhances automation, accuracy, and robustness in field environments and minor target drifts. The experiments were conducted under low-wind and low-clutter conditions. The average calibration error of antenna pointing is 0.08°, the average error of echo intensity calibration is 0.3 dB, the average beamwidth error is 0.07°, the range resolution is 6.6 m, and the average radial ranging error is 14 m. These results indicate that the proposed method can meet the main calibration requirements of weather radars in the present experiments. Full article

Protein phosphatase PPM1A plays a critical role in cellular signaling by dephosphorylating key regulatory proteins. According to experimental data, the enzyme requires either Mn²⁺ or Mg²⁺ bound in the active center(s), hence its catalytic activity strongly depends on the chelated metal ions. In this study, the metal ion selectivity of PPM1A is investigated using DFT calculations on active site constructs of bi- and trinuclear metal centers and protein ligands from the first and second metal coordination shells. Binuclear Mn-Mn and trinuclear Mn-Mn-Mn sites show poor resistance to substitution by biogenic Fe²⁺ and Zn²⁺, with Gibbs energies of the Mn²⁺ → Fe²⁺/Zn²⁺ exchange being consistently negative in both the gas phase and condensed media. In contrast, Mg-Mg and Mg-Mg-Mg centers are substantially more robust, with a thermodynamically unfavorable Mg²⁺ → Fe²⁺/Zn²⁺ substitution—except in the case of the Mg-Mg-Zn complex. The primary factors governing this metal competition in the modeled structures are the nature of the competing cation and the solvation properties of its aqua complexes, while solvent exposure of the binding site and the number of metal cations in the catalytic center exert a comparatively minor effect. Overall, these findings demonstrate that Mg²⁺-loaded active sites offer considerably greater protection against biogenic metal displacement than their Mn²⁺ counterparts, thus shedding light on the metalloprotein stability and enzyme fidelity of PPM1A. Full article

Hydronephrosis caused by malignant ureteral obstruction or radiotherapy-induced ureteral stenosis is a frequent complication in patients with cervical cancer. Effective management requires continuous urinary drainage, which can be achieved either internally through ureteral stent placement or externally via percutaneous nephrostomy. Among available devices, the Allium^TM fully covered nitinol mesh ureteral stent is designed to treat ureteral or urethral strictures while allowing safe and easy removal. However, serious complications have been reported, including uretero-enteric, uretero-arterial, and uretero-vaginal fistulas, pseudoaneurysm, ureteral perforation and sepsis. We report the case of a 44-year-old woman diagnosed in 2020 with stage IIIC1 cervical cancer (FIGO classification) who underwent surgery followed by adjuvant radiotherapy. In 2021, a right metallic ureteral stent was placed to treat ureteral obstruction. Two years later, she presented with right lumbar pain, and abdominal ultrasonography revealed grade III right hydronephrosis. CT scan demonstrated migration of the metallic ureteral stent into the rectal wall. Endoscopic extraction of the migrated stent was successfully performed via colonoscopy. Retrograde pyelography and CT imaging confirmed the presence of a recto-ureteral fistula. A 6 Ch/26 cm double-J ureteral stent was subsequently placed with good positioning and drainage. At the six-month follow-up, replacement of the double-J stent was performed. Imaging studies showed only minor residual hydronephrosis. Although metallic ureteral stents are effective for managing malignant ureteral obstruction, particularly in complex oncologic cases, they are not free of severe complications. The risk appears increased in patients who have undergone radiotherapy, emphasizing the need for careful monitoring and long term follow-up. Full article

This paper presents the geochemical characterisation of Penha-type ceramics, one of the most iconic prehistoric ceramics in Western Iberia. Penha pottery was a widespread material expression in Late Neolithic communities who displayed significant socio-cultural transformation before the advent of the Metal Ages. Samples (108) from seven archaeological sites in Galicia (NW Spain) were analysed by XRD, FTIR-ATR and ICP-MS to determine their mineral, molecular and elemental composition, respectively. The results indicate that most vessels are compositionally consistent with local geological sources, whether mafic or felsic, pointing to strong intra-site production. The use of raw materials seems to have been selective, and there are minor discordances and mixed compositions in almost all sites. The selected methods were effective in determining temper composition, while FTIR-ATR was also informative of clay transformations due to firing. The firing conditions were generally low-temperature (600–900 °C) with relatively short times (<5 h), compatible with simple kiln technology. Archaeometric evidence suggests two scales of mobility: predominant local mobility and limited long-distance exchange (coastal/inland). The geochemical characterisation reveals that individual communities seem to have developed their own customised recipes for pottery production using a profound knowledge of available local resources. Full article

Critical metals such as gallium and germanium are strategic mineral resources widely used in advanced technology, including semiconductors and solar cells. These metals are recovered as by-products from the processing of Zn–Pb and bauxite ores. In China, the Sichuan–Yunnan–Guizhou (SYG) region is abundant in Zn–Pb and bauxite ore deposits, such as the Huize Zn–Pb–Ge deposit and the Wuchuan–Zheng’an–Daozhen (WZD) area Al–Ga deposit. Although previous studies have proposed models to explain the enrichment mechanisms of critical metals in this area, the metal sources of these deposits remain controversial. In this study, samples were collected from the Paleoproterozoic Kunyang Group to the Permian Emeishan basalts, and the metal sources of these deposits were traced by comparing the Pb isotopic ratios and Zn/Cd ratios of potential source rocks and deposits. The findings indicate: (1) The Pb isotopic compositions of most samples are relatively homogeneous, but certain differences exist among strata from different geological periods. (2) The metal sources of the Yunnan and Guizhou bauxite may both have been controlled by the underlying carbonate rocks, but the specific source horizons differ significantly between the two regions. (3) Based on the Pb isotopic compositions of regional strata and Zn–Pb deposits, it appears that the regional basement and sedimentary cover likely contributed significantly to the ore-forming metals, whereas the Emeishan basalts may have played a relatively minor role. However, due to the complex lithology and substantial thickness of the basement and cover strata in the SYG region, there may be issues of sampling inadequacy. Nonetheless, this study provides important foundational data and insights for tracing the metal sources of deposits in this region using Pb isotopes and Zn/Cd ratios. Full article

The coexistence of microplastics (MPs) and heavy metals (Cd, Pb) in agricultural soils has become a global environmental and ecological risk. In this study, a pot experiment was conducted to investigate the effects of different concentrations of polyethylene (PE) microplastics and combined Cd/Pb contamination on the growth and development, heavy metal accumulation, and antioxidant system of tobacco (Nicotiana tabacum L. cv. Yunyan 87). The results showed that low-dose PE and low concentrations of heavy metals had minor impacts on tobacco growth and the antioxidant system; in contrast, high-dose PE and elevated heavy metal treatments markedly induced increases in malondialdehyde content (MDA) and enhanced the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Under co-contaminated conditions, the addition of low-dose PE reduced the translocation capacity of heavy metals, alleviated heavy metal-induced oxidative stress responses, and promoted tobacco growth. Conversely, high-dose PE promoted the translocation of Cd into tobacco plants and increased Cd contents in tobacco leaves, leading to marked decreases in soluble protein and soluble sugar contents, and causing severe reductions in plant height, number of functional leaves, and biomass. Structural equation modeling (SEM) analysis revealed that the direct effect of PE on tobacco growth was not significant; instead, it primarily acted as a regulatory factor, exerting either promotional or inhibitory effects on tobacco growth at different doses. The impact of Cd/Pb on tobacco growth appeared to involve two potential pathways. On the one hand, Cd/Pb induced direct toxicity through their accumulation within tobacco tissues. On the other hand, they exerted indirect regulation primarily by modulating the activities of the tobacco antioxidant system. Full article

Glitter is a distinctive and largely overlooked form of primary microplastic. Unlike more commonly studied microplastics, glitter particles are typically flat, highly reflective, multi-layered, and are composed of polymers such as polyethylene terephthalate, polyvinyl chloride with metallic coatings and a wide range of additives. In response to regulatory restrictions on intentionally added microplastics and increasing consumer demand, “eco-friendly” alternatives based on modified regenerated cellulose, cellulose nanocrystals, or mica have been introduced, although their environmental safety remains insufficiently characterized. This review synthesizes current knowledge on the environmental occurrence and ecotoxicological effects of both conventional and biodegradable glitters. A systematic literature search in Scopus identified 15 peer-reviewed experimental studies meeting predefined inclusion criteria. Evidence spans a wide range of taxa, including bacteria (i.e., Aliivibrio fischeri), microalgae and cyanobacteria (i.e., Phaeodactylum tricornutum, Raphidocelis subcapitata, Microcystis aeruginosa), aquatic plants (i.e., Lemna minor, Egeria densa), marine and freshwater invertebrates as crustaceans (i.e., Daphnia magna), bivalves (i.e., Mytilus galloprovincialis), sea urchins (i.e., Paracentrotus lividus), brine shrimp (Artemia sp.) and terrestrial soil fauna (Eisenia fetida, Folsomia candida). Results indicate that glitter cannot be treated as a uniform stressor: biological responses vary markedly with particle size, shape, colour, polymer type, additive composition, and weathering time, and leachates often exert stronger effects than intact particles. Reported impacts include impaired photosynthesis and growth, oxidative stress, developmental abnormalities, altered energy metabolism, and reduced reproduction. Substantial gaps remain regarding environmental concentrations, ageing processes, mixture effects, and long-term ecological consequences, particularly for biodegradable glitters. Addressing these gaps will require realistic exposure scenarios, mesocosm and field studies, and integrated chemical–biological approaches to support robust risk assessment and safer material design. Full article

This study provides a rigorous analysis of the phase stability, mechanical behavior, and surface integrity of a non-equiatomic (FeCoNiCr)₈₅Ga₁₅ high-entropy alloy (HEA). By transitioning from the conventional equiatomic design to a gallium-doped 3d-transition metal matrix, we explore the interplay between lattice distortion and phase separation. Synthesized via vacuum arc melting, the as-cast alloy exhibits a non-homogeneous dendritic morphology consisting of a Cr-Fe-Co rich face-centered cubic (FCC) matrix and Ni-Ga rich body-centered cubic (BCC) interdendritic regions. While global thermodynamic criteria (δ = 3.65, ΔH_mix = −9.28 kJ/mol, and Ω = 2.23) favor single-phase solid solution stability, the Valence Electron Concentration (VEC = 7.46) precisely forecasts this dual-phase structure. Following low-temperature annealing at 250 °C for 24 h, high lattice strain energy drives a significant morphological transformation where the continuous interdendritic network resolves into discrete, phase-separated B2/BCC “islands”. Mechanical and tribological characterizations reveal that this low-temperature thermal activation triggers precipitate hardening; the macro-hardness increases from 146 ± 11 HB to 153 ± 7.5 HB and the micro-hardness rises from 186 ± 4 HV_0.5 to 206 ± 17.5 HV_0.5, yielding enhanced resistance to oxidation-delamination wear. However, electrochemical evaluation in a 3.5 wt.% NaCl solution highlights a fundamental trade-off: the formation of localized galvanic micro-cells between the phase-separated islands and the matrix causes the corrosion current density (i_corr) to increase from ≈10⁻⁹ A/cm² in the as-cast state to ≈10⁻⁶ A/cm² post-heat treatment, accompanied by a heightened susceptibility to localized pitting. These findings elucidate the primary role of electronic structure and minor p-block additions in regulating the lifecycle performance of transition metal HEAs under extreme conditions. Full article

The separation of copper and arsenic from spent copper electrolyte plays a pivotal role in electrolyte recirculation and arsenic-bearing solid hazardous waste minimization. In this study, the deep copper removal process in high arsenic and low copper spent copper electrolyte by gas–liquid sulfidation is studied. Thermodynamic analysis indicates that under strongly acidic conditions, regulating the oxidation-reduction potential enables the selective precipitation of Cu²⁺ as CuS while inhibiting the formation of As₂S₃. The influence of hydrogen sulfide excess coefficient and gas–liquid sulfidation temperature on copper and arsenic co-precipitation behavior is investigated. Under the optimal gas–liquid sulfidation conditions with the sulfide excess coefficient of 47 and gas–liquid sulfidation for 60 min at 328.15 K, the copper concentration can be reduced from 0.312 g/L to 1.25 mg/L, while arsenic co-precipitation can be effectively suppressed. The copper gas–liquid sulfidation process is chemical reaction and diffusion mix controlled with an activation energy of 33.47 kJ/mol, while arsenic sulfidation is chemical reaction controlled with an activation energy of 51.22 kJ/mol. The copper–arsenic co-precipitated sludge predominantly consists of As₂S₃, CuS, and Cu₂S. Arsenic precipitation involves a multi-step process: As(V) is first reduced to As(III) and subsequently sulfurized. However, the majority of cupric ions are directly precipitated as sulfides, whereas a minor fraction is firstly reduced by hydrogen sulfide and subsequently precipitated. The present study clarifies the intrinsic mechanism and external regulatory factors for the gas–liquid sulfidation deep copper removal process, providing a theoretical basis for optimizing sulfidation processes to synergistically achieve valuable metal recovery and arsenic pollution control. Full article