Search Results (23,654)

Mine tailings management poses a major challenge, with up to 99% of the mined material remaining as finely ground residues. This study analyzes a SERNAGEOMIN database from 653 Chilean tailing deposits using a multivariate framework that integrates completeness assessments, descriptive statistics, and hierarchical clustering on log-transformed and standardized chemical concentrations of 56 elements in order to identify dominant geochemical patterns. This study aims to provide an integrated and systematic interpretation of the Chilean database, the most comprehensive public dataset on mine tailings in Chile. The results reveal four distinct geochemical profiles: (i) silicate copper tailings, rich in Cu and associated with a SiO₂-Al₂O₃ matrix; (ii) Zn-Pb-Cd-As polymetallic tailings, with the highest concentrations of heavy metals and rare earth elements (REEs), representing both high environmental risk and potential economic value; (iii) carbonate-matrix tailings (CaCO₃ and limestone), characterized by high CaO and loss of calcination (LOI) but low trace metal contents, suggesting buffering potential against acid mine drainage (AMD); and (iv) clay-rich tailings (kaolin and Au-Cu-Au), marked by high Al₂O₃ and anomalous Co enrichments, indicating unexploited potential for critical metal recovery. These profiles support applications such as their use as source signatures in receptor models and the classification of tailing deposits lacking geochemical information. Full article

The increasing atmospheric concentration of CO₂ is a major contributor to global climate change, underscoring the urgent need for effective strategies to convert CO₂ into value-added products. In this sense, a composite was successfully synthesized by combining clinoptilolite zeolite (CZ) with varying amounts of copper oxide (CuO-1% and 10%) for CO₂ photoreduction. The composites were characterized using insightful techniques, including XRD, nitrogen physisorption, DRS, and SEM. The results confirmed the incorporation and dispersion of CuO within the CZ support. The XRD analysis revealed characteristic crystalline CuO peaks. Despite the low surface area (<15 m²·g⁻¹) and macroporous nature of the samples, EDS imaging revealed an effective and homogeneous dispersion of CuO, indicating efficient surface distribution. UV–Vis diffuse reflectance spectroscopy revealed band gap energies of 3.30 eV (CZ), 3.38 eV (1%-CuO/CZ), and 1.75 eV (10%-CuO/CZ), highlighting the pronounced electronic changes resulting from CuO incorporation. Photocatalytic tests conducted under UVC irradiation (λ = 254 nm) revealed that 10%-CuO/CZ exhibited the highest CO and CH₄ production, 35 µmol·g⁻¹ and 3.6 µmol·g⁻¹, respectively. The composite also delivered the highest CO productivity (5.91 µmol·g⁻¹·h⁻¹), approximately 3.5 times that of pristine CZ, in addition to achieving the highest CH₄ productivity (0.60 µmol·g⁻¹·h⁻¹). Furthermore, turnover frequency (TOF) analysis normalized per Cu site revealed that CuO incorporation not only enhances total productivity but also improves the intrinsic catalytic efficiency of the active copper centers. Overall, the synthesized composites demonstrate promising potential for CO₂ photoreduction, driven by synergistic structural, electronic, and morphological features. Full article

The paper presents the experimental results of applying a novel protective coating made from Mn_1.7Cu_1.3-xFe_xO₄, compared to commercial spinels Mn_1.5Co_1.5O₄ and MnCo₂O₄, as a key component responsible for preventing chromium diffusion and slowing the increase in area-specific resistance (ASR) in solid oxide fuel cells (SOFCs). The layers of selected materials were deposited on Crofer 22APU steel by electrophoretic deposition (EPD) on small samples and by roll painting on full-scale interconnects. The coatings were evaluated by measuring the ASR of small samples for short and long runs (1000 h), as well as real-scale interconnects assembled in a SOFC stack composed of three cells, measuring 11 × 11 cm², which operated for 1000 h at 670 °C. The collected data on the electrochemical performance of the stack allowed for estimation of the degradation rates of all the repeating units, revealing benefits from using (Mn,Cu,Fe)₃O₄ as a coating. The results are compared to the literature reports. Post-mortem analysis by the SEM-EDS technique allowed for investigation of Cr diffusion levels. Full article

The genus Hyotissa (family Gryphaeidae) comprises ecologically and economically important marine bivalves, yet their molecular biology remains poorly characterized. This study presents de novo transcriptome sequencing of three Hyotissa species—H. sinensis, H. inaequivalvis, and Hyotissa sp.—to systematically identify and characterize the superoxide dismutase (SOD) gene family, a crucial component of the antioxidant defense system. We identified 46 SOD genes, including both Cu/Zn-SOD and Fe/Mn-SOD types, which exhibited considerable variation in molecular properties, domain architecture, and potential phosphorylation sites. Phylogenetic analysis revealed both evolutionary conservation and diversification of SODs across species. Notably, we identified homologs of two specialized SOD types: Dominin, which showed mutations in metal-binding sites suggestive of functional divergence, and copper-only SOD repeat proteins (CSRPs), which retained copper-binding residues but lost zinc-binding capacity. These findings suggest that the SOD family in Hyotissa has undergone significant functional diversification, potentially as an adaptive response to their high-oxygen, high-ultraviolet reef habitats. This study provides foundational transcriptomic resources for Hyotissa and offers new insights into the evolution and environmental adaptation of SOD genes in marine bivalves. Full article

The depletion of natural resources remains a major global challenge, emphasizing the need to develop sustainable processes that enable both metal recovery and waste recycling. This study investigates the leaching of valuable metals from lead smelting slag using methanesulfonic acid (MSA), a biodegradable and environmentally benign reagent. Batch experiments were performed under different MSA concentrations (0.35–1.4 M) and temperatures (22–80 °C). Metal dissolution increased nearly linearly with acid concentration up to 1 M, with maximum recoveries after 60 min of 85% Zn, 64% Pb, 75% Cu, and 68% Fe. Copper dissolution was governed by the oxidation of Cu₂S, while Fe leaching was affected by pH variations that promoted re-precipitation. Kinetic modeling indicated mixed chemical–diffusion control mechanisms, with activation energies of 22.6 kJ mol⁻¹ for Zn and 31–33 kJ mol⁻¹ for Pb, Cu, and Fe. Beyond efficient metal extraction, the process generated a leach residue with reduced concentrations of base metals and a mineralogical composition dominated by stable calcium-silicate phases, improving its potential suitability for reuse in construction or mining backfill applications. Overall, methanesulfonic acid proved to be an effective and sustainable lixiviant, combining high metal recovery with the generation of recyclable slag, thereby contributing to circular metallurgical practices. Full article

Background: 8-Quinolinol and its derivatives are drawing significant attention across various disciplines due to their remarkable versatility. These compounds are well-known for their exceptional chelating ability, forming stable metal complexes via their nitrogen and oxygen electron donor atoms. This main characteristic determines their broad utility. Biological activity can also be explained by the chelating capacity, which allows 8-quinolinol to bind to essential metal ions such as Fe, Zn, Cu, and others. This chelation disrupts metal-dependent biological processes in target cells or organisms, leading to a range of effects, including antimicrobial, anticancer, antifungal, and neuroprotective activities. On the other hand, the biological activity of pyrazole derivatives is attributed to their heterocyclic structure, which allows for interactions with biological targets that can lead to enzyme inhibition, receptor antagonism, radical scavenging, and other effects. Objective: This work aimed to synthesize and characterize novel diazene compounds derived from 8-quinolinol or 2-methyl-8-quinolinol and pyrazole amines, and to evaluate their antimicrobial and anticancer activities. Methods: The compounds have been synthesized by coupling diazonium salts obtained from the diazotization of heterocyclic amines with 8-quinolinol and its derivative, 2-methyl-8-quinolinol. The careful selection of reaction conditions enabled the synthesis of high-purity products. The compounds were characterized by 1D and 2D NMR, FT-IR spectroscopy, UV-Vis spectroscopy, and LC-HRMS analysis. The biological activity of the newly synthesized compounds was evaluated following the protocols of EU-OPENSCREEN, a European Research Infrastructure Consortium (ERIC) initiative dedicated to supporting early drug discovery. Results: By combining diazonium salts obtained from 3-methyl-1H-pyrazol-5-amine and ethyl 5-amino-3-methyl-1H-pyrazole-4-carboxylate with the aforementioned coupling agents, four novel 8-quinolinol derivatives were synthesized. The further hydrolysis of the ethoxy carbonyl functional group allowed its conversion to a carboxylic functional group, thus expanding the series of new compounds to six members. Several compounds from the series have proven to be biologically active against several human pathogenic microorganisms and the Hep-G2 cancer cell line. Conclusions: The combination of two well-known biologically active scaffolds through a classic diazo coupling reaction allowed the synthesis of novel biologically active compounds, which showed promising results as possible antifungal and anticancer agents. These results represent a foundation for future studies, which will include a broader biological screening and in vivo studies. Full article

This paper reviews tab-to-busbar interconnections in lithium-ion battery packs, focusing on resistance welding (RW), laser beam welding (LBW), and ultrasonic welding (USW). The functional roles of tabs and busbars and typical material choices (Al-, Cu-, and Ni-plated Cu) are outlined. Subsequently, the processes are compared in terms of heat input, interfacial metallurgy, electrical resistance, mechanical robustness, and manufacturability. USW, as a solid-state method, suppresses porosity and limits Al-Cu intermetallic growth, but is sensitive to thickness, stack geometry, and tool wear. LBW enables high-speed, automated production with precise energy delivery, yet requires careful control to mitigate spatter, porosity, and brittle IMCs in dissimilar joints. RW remains cost-effective and flexible but can suffer from electrode wear and variability with highly conductive stacks. This review also summarizes the effect of the busbar material (Al versus Cu) and thickness on the connection resistance and temperature increase under a high current. No single process is universally superior, and the selection should match the stack-up, reliability targets, and production constraints. This paper aims to provide an overview of recent and conventional research trends for each welding method and to introduce selected non-traditional approaches, thereby presenting a range of viable options for future applications. Full article

Fluoxetine and carbamazepine are widely prescribed psychotropic drugs, yet few studies have quantified metal(loid) impurities in these medicines, which may pose health risks to patients. This study aimed to determine concentrations of As, Cd, Cr, Cu, Fe, K, Mg, Mn, P, Pb, Se, and Zn in brand, similar, and generic samples of fluoxetine and carbamazepine marketed in Campo Grande, Brazil. Drug samples were purchased from local pharmacies, digested with acid, and analyzed by Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES). Results showed that arsenic was detected only in fluoxetine samples, with concentrations ranging from 0.068 to 0.217 mg/kg, all below national and international limits. Phosphorus presented the highest levels, especially in fluoxetine, reaching up to 14,000 mg/kg, and up to 93 mg/kg in carbamazepine. Other elements such as Fe (0.07–3.03 mg/kg), Mg (0.21–259 mg/kg), K (up to 45 mg/kg), Se (up to 1.5 mg/kg), and Zn (up to 4.2 mg/kg) were also quantified, while Cd, Cr, Cu, and Pb were below detection limits. The hazard index (HI) exceeded 1 for all carbamazepine samples and for one brand, two similar, and three generic fluoxetine samples, indicating that the intake of these medications may pose potential health concerns. These findings underscore the need for stricter monitoring of metal(loid) impurities in psychotropic drugs to protect patient safety and ensure regulatory compliance. Full article

Oxidation is a critical factor contributing to material wear and the degradation of conductive performance during current-carrying tribological processes. The present study investigated the composite oxidation mechanisms that occurred during current-carrying rolling in mixed atmospheres containing O₂ and H₂O vapor. The results obtained in a dry N₂/O₂ mixture, humid N₂, and humid N₂/O₂ mixture indicated that the oxidation mechanisms on current-carrying rolling surfaces involved thermal oxidation, tribo-oxidation, and anodic oxidation. XPS analysis confirmed that the primary oxidation product was CuO. Conductive atomic force microscopy (C-AFM) revealed that surface oxidation caused a significant reduction in conductive α-spots, leading to an increase in contact resistance. Contact resistance exhibited a quasi-linear relationship with the surface CuO content. Contact angle measurements and adhesion tests showed that the enhanced hydrophilicity of the oxidized surface and the resulting high adhesion contributed to an increase in the macroscopic friction coefficient. In humid N₂/O₂ with 50% relative humidity (RH), the friction coefficient rapidly exceeded 0.8 when the O₂ content surpassed 25%. Wear morphology analysis demonstrated that this abrupt increase in the friction coefficient induced fatigue wear on the surface. Overall, the present study elucidated the composite oxidation mechanisms during current-carrying rolling and clarified the pathways through which oxidation affected current-carrying tribological performance. These findings may contribute to improved failure analysis and the safe, reliable operation of electrical contact pairs. Full article

Pt-Fe alloys with abundant inclusions are from the Camumbi River placer deposit, Ecuador. They are derived from unknown Alaskan–Uralian-type intrusion(s) within the Late Cretaceous Naranjal accreted terrane. Compositions of our previously documented chilled silicate glass inclusions are increasingly fractioned from hydrous ferrobasalt to rhyolite in terms of TAS (total alkalis vs. silica). Their liquid lines of descent change from tholeiitic to the calc-alkaline magma series. Here, we document seven exceptional rare composite inclusion parageneses of Cu–PGM (platinum-group mineral) sulfides, each coexisting with and exsolved from related coexisting, fractionated silicate glass (melt). Differentiation is dominated by fractional crystallization in PGM bulk compositions from tholeiitic silicate melts at the highest T (temperature): ~1018 °C. Silicate glass inclusions following the lower T calc-alkaline trend coexist with sulfide PGM parageneses that were likely differentiated, in terms of Pt-Rh-Pd and BMs (base metals), by incongruent melting due to decompression and S-degassing at ~983–830 °C. S-saturated sulfide melts become S-undersaturated below 845 °C. The calculated temperatures are for silicate glass. Pt-rich braggite shows increasing fractionation towards Pd-rich vysotskite within one inclusion paragenesis. A late braggite–vysotskite fractionation trend shows decreasing minor base metals (BMs). Thiospinels are dominated by cuprorhodsite. Minor thiospinels indicate Fe and then strong Ni enrichment at the lowest T. Decompression exsolutions, deflation, and the partial melting of some sulfide inclusion parageneses support rapid ascent to higher crustal levels within a deep-sourced cumulate intrusion. Full article

Humic acids (HAs) are widely used as adsorbents or carriers, yet they still lack oxygenic functional groups under certain conditions. Modification via catalytic oxidation under mild conditions is an ideal method to increase the oxygenic functional groups in HAs—if simple catalyst separation could be realized. Here, we report the use of CuO nanoparticles supported by Fe₃O₄ magnetic nanospheres as magnetic catalytic systems (MCSs) that could catalyze HA modification via Fenton oxidation. These MCSs can be easily magnetically separated from the products. The content of carboxyl groups increased from 2.45% to 10.47% after reaction, while the yield of modified HAs remained approximately 100%. These results indicate that oxidation with MCSs could be a potential method for HA modification. Full article

Al-Ni alloys have a unique set of properties including high conductivity, high fluidity, good thermal stability, and reasonable strength. These properties are also needed for effective braze fillers, a novel application for Al-Ni alloys. A Cu substrate was reacted with pure liquid Al, and the resulting microstructure upon solidification was observed and analysed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). This diffusion couple was compared with the diffusion couple between liquid eutectic Al-3at.%Ni and a Cu substrate. Several phases unique to the solidified liquid in the Al-Ni/Cu diffusion couple were observed, such as Al₇Cu₄Ni (τ), Al₃(Cu, Ni)₂, and Al₃Ni. These microstructures were compared with a mathematical model based on Fick’s second law, as well as calculation of phase diagram (CALPHAD) modelling. The approximate calculated concentration profile of Cu in the liquid phase was validated against the microstructural observations and proved effective to explain the observed microstructural features. Liquid Al-3at.%Ni was found to limit the growth of the brittle Al₂Cu (θ) phase during solidification by limiting Cu solubility in the liquid phase, which would be beneficial for use in dissimilar joints between Al and Cu. Full article

Practices with medical cyclotrons to produce PET radiopharmaceuticals in Latin America represent a technological advance for the diagnosis and treatment of diseases such as cancer, but they involve occupational risks due to exposure to ionizing radiation. This study evaluates the perception of risk in 46 radiopharmacy service workers in 13 countries in the region (Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Ecuador, Mexico, Peru, Portugal, Dominican Republic and Venezuela), analyzing differences by gender and age. The questionnaire, validated by reliability analysis (Cronbach’s coefficient α > 0.7), was statistically analyzed with means, standard deviations (SD) and standard errors (SE), 95% confidence intervals (Student’s t-distribution), and coefficients of variation (CV) to assess the dispersion of each variable. The results reveal general underestimation in dimensions such as reversibility of consequences (SD = 0.7142, SE = 0.1053) and familiarity (SD = 0.8410, SE = 0.124), promoting complacency, while immediacy of consequences shows overestimation (SD = 0.9760, SE = 0.1439), amplifying anxiety. By gender, women tend to overestimate (e.g., immediacy = 2.5) and men underestimate (e.g., confidence = 1.78); by age, young people (26–45 years old) overestimate more than older people (≥46 years old). These deviations, with high QoL indicating heterogeneity, suggest interventions such as continuous training, real-time monitoring, and communication campaigns to balance perception. Practical recommendations include job rotations to reduce underestimation due to familiarity and simulations to mitigate emotional overestimation, which are aligned with IAEA regulations (GSR Part 3, SSG-46) to promote a sustainable safety culture. Full article

Titanium-based bulk metallic glasses (BMGs) offer high strength, lower stiffness than Ti-6Al-4V, and superior corrosion resistance, but conventional Ti glass-forming systems often contain toxic Ni, Be, or Cu. This work investigates five novel Ti-based alloys free of these elements—Ti₄₂Zr₃₅Si₅Co_12.5Sn_2.5Ta₃, Ti₄₂Zr₄₀Ta₃Si₁₅, Ti₆₀Nb₁₅Zr₁₀Si₁₅, Ti₃₉Zr₃₂Si₂₉, and Ti_65.5Fe_22.5Si₁₂—synthesized by arc melting and suction casting. Single-track laser remelting using a selective laser melting (SLM) system was performed to simulate additive manufacturing and examine microstructural evolution, cracking behavior, mechanical properties, and cytocompatibility. All alloys solidified into fully crystalline α/β-Ti matrices with Ti/Zr silicides; no amorphous structures were obtained. Laser remelting refined the microstructure but did not induce glass formation, consistent with the known limited glass-forming ability of Cu/Ni/Be-free Ti systems. Cracking was observed at low laser energies but crack density decreased as laser energy increased. Cracks were eliminated above ~0.4 J/mm for most alloys. Ti₄₂Zr₃₅Si₅Co_12.5Sn_2.5Ta₃ exhibited the lowest stiffness (~125 GPa), while Ti₆₀Nb₁₅Zr₁₀Si₁₅ showed the highest due to silicide precipitation. Cytotoxicity tests (ISO 10993-5) confirmed all alloys to be non-toxic, with some extracts even enhancing fibroblast proliferation. This rapid laser-remelting approach enables cost-effective screening of Ti-based glass-forming alloys for additive manufacturing. Ti–Zr–Ta–Si systems demonstrated the most promising properties for further testing using the powder bed method. Full article

(1) Background: Tobacco use constitutes a significant preventable cause of morbidity and mortality on a global scale. It contributes to cumulative exposure to carcinogenic and toxic heavy metals, including cadmium, lead, nickel, and copper. Collectively, these metals promote oxidative stress, multi-organ damage, and an increased risk of cancer, cardiovascular, respiratory, and renal diseases; (2) Methods: The research material comprised 119 tobacco samples. The concentrations of cadmium, lead, copper, and nickel in the samples were subsequently determined. A series of calculations were conducted in order to estimate the non-carcinogenic and carcinogenic health risks associated with the consumption of tobacco products under a variety of exposure scenarios; (3) Results: The concentrations of heavy metals in the tobacco samples ranged as follows, with mean values: Cd: 0.3–8.6 mg/kg (mean 1.0), Cu: 3.4–92.6 mg/kg (mean 12.3), Ni: 1.1–15.4 mg/kg (mean 3.4), and Pb: 0.2–1633.3 mg/kg (mean 46.5). A health risk assessment indicated that exposure through inhalation to cadmium Cd, Ni, and Pb, even in the minimal smoking scenario of one cigarette per day, consistently exceeded internationally established thresholds for carcinogenic risk; (4) Conclusions: The presence of high inter-brand variability and high-risk outliers underscores the necessity for enhanced regulation and monitoring of toxic metals in tobacco products. Full article