Search Results (22,633)

Photocatalysis is a promising strategy for the treatment of dangerous chemical pollutants in the ocean. In this work, a stable copper-based photocatalyst, i.e., {[Cu(BPA)₂]·2I₃}_n (1, BPA = 4,4′-bipyridinium-N-pentanoic acid), exhibited excellent degradation performance in dye pollutant in seawater. According to the structural analysis, this photocatalyst consists of 1-D cationic [Cu(BPA)₂]_n²ⁿ⁺ infinite chain and two I³⁻ polyiodide anions. In the [Cu(BPA)₂]_n²ⁿ⁺ chain, the distorted CuO₄N₂ octahedra are bridged by asymmetric viologen ligand (BPA), which result in a 1-D ladder-shaped chain. Strong C–H···O/I hydrogen bonds contribute to the formation of a 2-D layer along bc-plane, in which I³⁻ anions are stacked among the cationic chains. The strong adsorption from ultraviolet to visible regions together with its high charge separation efficiency implies its usage as excellent visible-light-driven catalysis. Interestingly, good photocatalytic performance for the degradation of Rhodamine B (RhB) in seawater can be observed by using this hybrid as photocatalyst. In detail, 90.6% degradation ratio of RhB can be achieved in 150 min under visible light, which was monitored on a UV–Vis spectrum. This work could pave the way for new ocean pollutant treatments for shipping accidents. Full article

This study reported the development of a novel Al-Si-Mg-based composite reinforced by micron-sized Cu-Mn binary solid solution phases and submicron-sized α-Al(Mn,Fe)Si dispersoids. The Cu-Mn binary solid solution phases were added to the melt in the form of an Al-3%CuMn master alloy, whereas α-Al(Mn,Fe)Si dispersoids were obtained via heat treatment. The microstructure analysis confirmed the presence of micron-sized Cu-Mn binary, eutectic Mg₂Si, and Al₁₅(FeMn)₃Si₂ intermetallic phases, submicron-sized α-Al(Mn,Fe)Si dispersoids, and nano-sized precipitates in the Al-based composite. At room temperature, tensile results represented a yield strength of 287 MPa and a tensile strength of 306 MPa, with an elongation of 17%. Moreover, the Al-based composite maintained a yield strength of 277 MPa up to 250 °C, with a slight increase in elongation. The composite also exhibited excellent high-temperature high-cycle fatigue properties and showed a high-cycle fatigue limit of 140 MPa at 130 °C, which is ~2.3 times higher than that of the commercial A319 alloy. A fractography study revealed that the secondary particles hindered the movement of dislocations, thus delaying crack initiation under cyclic loading at high temperatures. Additionally, Cu-Mn binary solid solutions and Al₁₅(FeMn)₃Si₂ phases were found to be effective in reducing the crack propagation rate by hindering the movement of the propagated crack. Full article

A key goal when managing copper alloy heritage is preventing “bronze disease,” which damages surface detail and may disintegrate objects by oxidation and hydrolysis of nantokite (CuCl), forming voluminous copper trihydroxychlorides (Cu₂(OH)₃Cl). The success of mitigation strategies is difficult to evaluate due to the complexity of copper alloy corrosion profiles, limitations in non-destructive analytical methods and incomplete understanding of the corrosion mechanisms and reactions involved in bronze disease. Without better understanding, it is impossible to design truly effective solutions for the safe storage and display of archaeological copper alloys. Advancing current understanding, this paper examines oxidation and hydrolysis of CuCl using oxygen consumption, Fourier transform infrared spectroscopy and Raman spectroscopy, recognised as the basis of bronze disease. Variables potentially affecting bronze disease processes are evaluated, including relative humidity (RH) (15–80%RH at 20 °C) and the presence of metallic copper with CuCl and their respective ratios. Results confirm that these variables influence the reaction mechanisms and kinetics of bronze disease. The rate of oxidation and hydrolysis of CuCl accelerates with RH, and its effect is quantified. The presence of copper is shown to be important for producing bronze disease; it facilitates a cyclic reaction forming Cu₂(OH)₃Cl, increases its formation rate at lower RH than by hydrolysis of CuCl alone and prevents formation of soluble chloride compounds. The formation of Cu₂(OH)₃Cl without counteracting copper ions is shown to promote formation of CuCl₂ and CuCl₂·2H₂O, accelerating bronze disease. This new understanding is used to better quantify risk of bronze disease as a function of RH, providing a more quantitative tool for managing preservation of archaeological copper alloy collections. Full article

The impact of milling process parameters on the physicochemical properties of waste plum stones was investigated to enable their further utilization as a functional material. The experiments were conducted using a planetary ball mill, with variations in milling duration (1–3 h), the ball-to-powder ratio (bpr) (10:1 and 20:1), and the rotation speed (250 and 500 rpm). Transformations of material in a function of process parameters were assessed by XRD, FTIR, and SEM analysis, revealing differences in particle size distribution, functional group composition, and surface morphology. Optimization of milling process parameters was focused on promoting fine particle formation and surface activation without causing significant material degradation. The best result was achieved with the PS-M10 sample, processed at a speed of 500 rpm and a bpr of 20:1 during a short milling time of 1 h. The milled sample demonstrated promising potential for further applications, particularly for heavy metal ion (Pb²⁺ and Cu²⁺) removal from aqueous solutions through adsorption. Full article

Metallic nanolaminates generally show ultra-high strength but low ductility due to their vulnerability to shear instability during deformation. Herein, we report the simultaneous enhancement in hardness (by 11.9%) and suppression of shear instability in a 10 nm Cu/Zr nanolaminate, achieved by introducing a nanoscale Cu₆₃Zr₃₇ amorphous interfacial layer (AIL) between the crystalline Cu and Zr layers via magnetron sputtering. The effect of AIL and its thickness (h) (h = 2, 5, and 10 nm) on the hardness and shear instability behavior was explored using nano- and micro-indentation tests. An abnormal increase in hardness occurs at h = 2 nm when h is decreased from 10 to 2 nm, deviating from the prediction of the rule of mixtures. This abnormal strengthening is attributed to thinner AIL, which induces an increased density of crystalline/amorphous interfaces, thereby generating a pronounced interface strengthening effect. The micro-indentation results show that shear banding was suppressed in the nanolaminate with AIL, as evidenced by fewer shear bands as compared to its homogeneous counterpart. This enhanced resistance to shear instability may originate from the crystalline/amorphous interface that provides more sites for dislocation nucleation, emission, and annihilation. Furthermore, two distinct shear banding modes were observed in the nanolaminate with AIL; i.e., a cutting-like shear banding emerged at h = 10 nm, whereas a kinking-like shear banding occurred at h = 2 nm. The potential mechanism of the AIL-thickness-dependent shear banding was analyzed based on the crack propagation model of the Griffith criterion. This study provides a comprehensive insight into the strengthening and tunable shear instability of super-nano metallic laminates by AIL. Full article

Legacy sulfur smelting has left behind complex contamination landscapes, yet the spatial structuring of microbial risks and adaptation strategies across soil profiles remains insufficiently understood. Microbial risk genes, including those conferring resistance to antibiotic resistance (ARGs), biocide and metal resistance (BRGs/MRGs), and virulence (VFGs), are increasingly recognized as co-selected under heavy metal stress, posing both ecological and public health concerns. In this study, we integrated geochemical analyses with metagenomic sequencing and functional annotation to jointly characterize the vertical (0–7 m) and horizontal (~2 km) distribution of heavy metals/metalloids, microbial communities, and functional risk genes at a historic smelting site in Zhenxiong, Yunnan. Heavy metals and metalloids such as arsenic (As), chromium (Cr), copper (Cu), and lead (Pb) showed clear accumulation with depth, while significantly lower concentrations were observed in both upstream and downstream locations, revealing persistent vertical and horizontal pollution gradients. Correspondingly, resistance and virulence genes were co-enriched at contaminated sites, suggesting potential co-selection under prolonged stress. LEfSe analysis revealed distinct ecological patterns: vertically, upper layers were dominated by nutrient-cycling and mildly stress-tolerant taxa, while deeper layers favored metal-resistant, oligotrophic, and potentially pathogenic microorganisms; horizontally, beneficial and diverse microbes characterized low-contamination zones, whereas heavily polluted areas were dominated by resistant and stress-adapted genera. These findings provide new insights into microbial resilience and ecological risk under long-term smelting stress. Full article

This study aims to evaluate the feasibility of using the mussel as a bioindicator for the rapid detection of heavy metal (such as Cd, Pb, Hg, Ni, Cr, Cu, As, and Zn) fluctuations in aquatic environments and the sensitivity of the bioaccumulation of heavy metals in muscle tissues over time. The seasonal bioaccumulation patterns of heavy metals within Asian green mussels (Perna viridis), from Vietnamese coastal waters of Hai Phong were investigated using inductively coupled plasma mass spectrometry (ICP-MS). Additionally, the health risks from the consumption of P. viridis by local people were assessed. Mussels of varying sizes were sampled on a monthly basis between March (dry season) and July 2024 (wet season). The results revealed that the hepatopancreas had substantially higher concentrations of metals at all times relative to their corresponding muscle tissues, confirming its appropriateness as a bioindicator organ. The concentrations of heavy metals in mussels were recorded as significantly lower than the guideline levels, except for arsenic (As). Zinc (Zn) showed the highest concentrations, while mercury (Hg) had the lowest concentrations. There were strong seasonal and monthly differences, with peak levels of Pb, Cr, and As during the dry season, and high levels of Cs and Cu during the rainy season. It was found that the condition index, physiological factors, and shell size all had major impacts on the absorption of specific heavy metals. It was indicated that Pb, Cr, As, Cs, and Cu bioaccumulation are both biologically and environmentally responsive and can be used as proxies for environmental contamination, while the accumulation of these metals correlated with biological traits (shell length, weight, and CI), which is useful in modeling efforts. Health risk assessments using target hazard quotients (THQs) and the total hazard index (THI) identified Pb in the hepatopancreas as a primary contributor to the non-carcinogenic risk (THQ > 1), particularly during the dry season. The findings revealed the suitability of P. viridis, particularly hepatopancreatic tissue, as a short-term biomonitoring tool for detecting spikes and rapid fluctuations of certain heavy metals and assessing related human health risks in coastal aquatic systems. Full article

This study comprehensively evaluates heavy metal (HM) contamination and associated health risks in 31 groundwater samples from Wadi Al-Hamd, northwest Saudi Arabia. Cd, Pb, Zn, As, Cr, Cu, Ba, and Ni showed variable concentrations, some elements approaching WHO guideline values in localized samples. The analyzed HMs showed variable concentrations, with As reaching 5.02 µg/L (50% of WHO guideline) in sample M27. The heavy metal pollution index (HPI) ranged from 0.15 (M29) to 10.07 (M27), with values below 15 indicating low pollution overall, while the metal index (MI) ranged from 0.022 (M29) to 0.621 (M27), all below the threshold of 1 for safe water, indicating geogenic enrichment, particularly in arsenic and nickel. Principal component analysis identified three PCs explaining 73.58% of total variance, with PC1 (35.50%) dominated by Zn-Cu-Ni (geogenic weathering) and PC2 (23.62%) by As-Cd (redox-driven dissolution). Health risk assessment via chronic daily intake (CDI), hazard quotient (HQ), and hazard index (HI) models confirmed negligible non-carcinogenic risks (HI < 1) for both adults and children, though children exhibited 1.5–2 times higher exposure. The highest HQ values were observed for As (HQoral-child: 0.365 in M27), approaching but not exceeding safety thresholds. Dermal exposure contributed minimally (<1% of total risk). The average lifetime carcinogenic risk (LCR) due to exposure to arsenic through drinking water aligns with the US EPA’s acceptable risk range of 1 × 10⁻⁶ to 1 × 10⁻⁴ (average 1.18 × 10⁻⁵ for adults, 2.06 × 10⁻⁵ for children). These findings align with regional studies, but highlight localized As high values for few samples. The study underscores the dominance of natural weathering in HM release and provides a framework for targeted groundwater management in arid regions. Full article

The mineral chalcopyrite (CuFeS₂) is inherently resistant to conventional leaching techniques, necessitating the intensification of the leaching process to achieve efficient metal recovery. Microwave-assisted leaching, combined with the application of a suitable oxidizing agent, presents a viable approach to enhancing the dissolution rate of metals in solutions. The objective of this study is to investigate the effect of microwave irradiation on the leaching behavior of chalcopyrite concentrate in a hydrochloric acid (HCl) medium, employing deep-sea polymetallic nodules (DSP) as the oxidizing agent. The influence of acid concentration and microwave power on copper extraction efficiency was examined. Optimal copper extraction was observed at an HCl concentration of 5 M and a microwave power of 750 W. The results indicate that DSP nodules serve as a more effective oxidizing agent than pyrolusite in acidic oxidative microwave-assisted leaching of chalcopyrite, particularly in terms of copper recovery. Analytical techniques employed for the characterization of leach residues and solutions included Atomic Absorption Spectroscopy (AAS) and Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive X-ray Spectroscopy (EDS). Full article

Although skarn-type deposits represent significant hosts for Co resources, the distribution patterns and enrichment mechanisms of associated Co resources within these deposits have not been systematically investigated. This study summarizes relevant data on Co resources from representative skarn-type deposits in China to comparatively reveal the grade and reserve characteristics, spatiotemporal distribution patterns, and coupled enrichment mechanisms of Co across three principal skarn mineralization subtypes: iron-, copper-, and lead–zinc polymetallic-dominated deposits. Studies demonstrate that Fe-dominated skarn-type cobalt deposits exhibit widespread distribution, high Co grades (100–2000 ppm), and abundant Co reserves (4000–32,000 t), demonstrating significantly superior Co resource potential compared to Cu-dominated (Co grades: 20–200 ppm, Co reserves: 3000–10,000 t) and Pb-Zn polymetallic-dominated (Co grades: 140–853 ppm, Co reserves: approximately 3000 t) subtypes. In these skarn-type cobalt deposits, cobalt is mainly hosted in sulfide minerals. Influenced by tectonic settings, magmatic activity, and hydrothermal fluid evolution, associated Co resources in these skarn-type deposits exhibit both regional zonation and stage-specific differential enrichment patterns. In the formation of skarn-type cobalt deposits, mantle-derived magmas play a critical role in the pre-enrichment of Co. The injection of mafic magmas, assimilation of evaporite sequences, and the dissolution–reprecipitation mechanism of hydrothermal fluids collectively promote the re-enrichment of Co during magmatic evolution. These findings provide a theoretical foundation for targeted exploration, sustainable development, and comprehensive utilization of associated Co resources in skarn-type deposits. Full article

This study examines the influence of key technological parameters—marking speed, raster step (Δx), pulse duration, power density, and effective energy—on the laser marking of copper using Yb-doped fiber and CuBr MOPA lasers. Two experimental setups were used: the fiber laser, with 100 ns and 200 ns pulses, and the CuBr laser with 30 ns pulses. Marking speed ranged from 10 to 80 mm/s, with raster steps from 3 to 20 µm for the fiber laser and 3 to 27 µm for the CuBr laser. The study compares different pulse durations and evaluates the impact of laser wavelength on the marking process. Optimal effective energy ranges were identified: 17.4–43.1 kJ/cm² for the Yb-doped fiber laser and 9.90–43.1 kJ/cm² for the CuBr laser. The originality of this work lies in its direct comparison of Yb-doped fiber and CuBr MOPA lasers for copper marking, alongside the simultaneous optimization of multiple parameters. The study provides novel guidelines for high-contrast copper marking, a material with known laser-processing challenges. The identified optimal energy ranges and process parameters can significantly improve the efficiency and quality of industrial copper marking applications. Full article

The fragile ecological environment of the Qinghai–Tibet Plateau (QTP) is significantly affected by human activities. This study employed a self-organizing map (SOM) for cluster analysis and positive matrix factorization (PMF) to trace the source of potentially toxic elements (PTEs) in the surface water of rivers. The results revealed that the average concentration of PTEs in the rivers was generally low. However, at some sampling points, especially in areas near the Qarhan Salt Lake, the content of Cu, Hg, and Ni were high. The water quality index (WQI), contamination factor (CF), and modified contamination index (mCd) identified good water quality, while potential Ni in the Quanji and Golmud River basins were the primary contaminants of concern. The potential ecological risk index (PERI) showed a low ecological risk. The SOM yielded four clusters of water PTEs, including Hg, Cu-Ni, Pb-Cd-Zn, and As. PMF model further revealed PTE sources, with industrial sources (39.73%) as the primary anthropogenic factor, followed by natural weathering (33.44%), vehicle emissions (21.52%), and atmospheric deposition (5.31%). This study laid the foundation for the ecological monitoring of rivers on the QTP and provided a reference for balancing industrial development and ecological protection in Qarhan Salt Lake areas. Full article

The Jinchuan Cu–Ni sulfide deposit, one of only two ultra-large magmatic Ni–Cu–PGE deposits in Eurasia, is hosted in a small ultramafic intrusion at the southwestern margin of the Alxa block, North China Craton, and contains over five million tonnes of nickel. Previous studies suggest that its formation is linked to large-scale deep magmatic processes, but direct evidence from the mantle source region has been limited. Using P-wave seismic tomography, we imaged the crust and mantle beneath the Qilian–Longshoushan area, revealing a deep low-velocity anomaly at ~400 km depth, interpreted as residual mantle plume material. This anomaly spatially corresponds to the Jinchuan deposit, representing a long-term material and heat supply pathway for ore formation. A high-velocity anomaly at ~200 km depth, likely related to Indian plate subduction, influenced the Cenozoic tectonic evolution of the Longshoushan region. These results integrate geophysical, geochemical, and geological evidence, highlighting how deep mantle dynamics and associated magmatic activity controlled the supply of material to the Jinchuan Cu–Ni deposit and contributed to its formation. Full article

Exploring the pollution characteristics and ecological risks of urbanization on lakes in urban fringe areas has guiding significance for the control and scientific management of heavy metal pollution in lakes in urban fringe areas. Taking the West Lake in Kaifeng city as an example, the samples of the sediments and surface water of the lake were collected, and the contents of heavy metals (As, Cd, Cr, Cu, Ni, Pb, and Zn) were measured, assessing the degree and ecological risk of heavy metal pollution using the Geo-Accumulation Index (I_geo) and Potential Ecological Risk Index methods (RI); and the sources of pollution were identified. The results show that the heavy metal concentrations in the surface water of the West Lake in Kaifeng city are generally low; average concentrations of Cd, Cu, Zn, Cr, Ni, Pb, and As in sediments are 3.120, 1.810, 1.700, 1.540, 1.000, 0.990, and 0.430 times higher than the background value of fluvo-aquic soil, respectively. The sequence of the average I_geo from high to low is Cd (1.020) > Cu (0.220) > Zn (0.160) > Cr (0.000) > Pb (−0.610) > Ni (−0.640) > As (−1.850). Among them, contaminations with Pb are classed as moderately polluted; As pollution is relatively light, while other heavy metals are unpolluted. The average Potential Ecological Risk Coefficient (E) values for seven heavy metals are Cd (93.500) > Cu (9.040) > Ni (4.990) > Pb (4.950) > As (4.290) > Cr (3.080) > Zn (1.700). Cd is at a considerable potential ecological risk, while other heavy metals are at low ecological risks. Heavy metal pollution in sediment of West Lake in Kaifeng mainly comes from traffic activities such as yacht machinery wear and gasoline burning. The research findings provide a scientific foundation for developing effective mitigation strategies against heavy metal contamination in peri-urban lacustrine ecosystems. Full article

Trace metal (TM) concentrations and carcinogenic risk were determined in ninety-two edible samples of the triggerfish Balistes spp. from the RAMSAR site 1826 San Ignacio-Navachiste-Macapule Lagoon Complex (NAV). The acid digestion method and an atomic absorption spectrophotometer were used to determine TM concentrations. Calibration curves were carried out using TORT-3 reference materials. The blank and certified reference materials were treated using the same procedure as a sample. TM sequence was Zn > Fe > Mn > Cu = Pb > Ni > Cd, and a correlation (p = 0.0169) between size and concentrations was found. No correlation (p = 0.079) was found between weight and concentrations, or sampling sites and the concentrations. The highest concentrations were found during the summer, followed by the spring and winter of 2017, while the lowest was found in the winter of 2018. The Zn was significantly higher in summer-17. The Target Hazard Quotient (THQ) was <1 for Pb, Ni, Cd, Fe, Zn, and Cu, and 1.39 for Mn. Cd and Pb resulted in carcinogenic potential (CsFo < 1) with a very low probability. The TM concentrations and bioaccumulation in triggerfish showed no consumption risk, due to its omnivorous diet, and trophic transfer rates were described for aquatic food webs. Full article