Search Results (23,052)

Efficient detection of heavy metal ions in complex marine environments is essential to the safety of marine organisms and human beings. This study developed a novel screen-printed-electrode (SPE) electrochemical sensor for rapid on-site determination of typical heavy metal ions such as Cu²⁺, Pb²⁺, Cd²⁺, and Hg²⁺ in seawater. The sensor employs a three-electrode system, with the working electrode modified with a composite of metal–organic framework-derived carbon (MOF-C) and multiwalled carbon nanotubes (MWCNTs), thereby significantly enhancing detection sensitivity and selectivity. By optimizing square-wave anodic stripping voltammetry (SWASV) parameters, detection limits of 0.83, 0.40, 1.05, and 0.30 μM for the detection of Cu²⁺, Pb²⁺, Cd²⁺, and Hg²⁺ ions were achieved. In mixed-ion detection, excellent peak separation and strong resistance to interferences were demonstrated. Experimental results demonstrate that the sensor exhibits good linear response, excellent interference resistance, and high practicality, providing a new approach for rapid on-site determination of heavy metal pollution in marine environments. Full article

Surface plasmon resonance (SPR)-based optical fibre sensors have transformed label-free biosensing; however, single-interface evanescent field interactions continue to limit their sensitivity. This study presents a novel π-configuration optical fibre-based surface plasmon resonance sensor that greatly increases sensitivity by enabling dual plasmonic excitation on two symmetrically polished surfaces coated with optimized metallic thin films (Ag, Au, or Cu). We show, using finite element method simulations in COMSOL Multiphysics v6.3, that the π-configuration increases the interaction volume between the analyte and guided light, resulting in an enhanced sensitivity of 3300 nm/RIU for silver at refractive index (RI) 1.37–1.38, which is a 120% improvement over traditional D-shaped sensors (1500 nm/RIU). The maximum field norm for the π-configuration sensor is approximately 1.4 times greater than the maximum observed for the D-shaped SPR sensor at an analyte RI of 1.38. The sensor’s performance is evaluated using full-width half-maximum, wavelength sensitivity, and wavelength interrogation metrics. For the π-configuration sensor at an analyte RI of 1.38, the values of the FWHM, figure of merit, detection accuracy, and confinement loss were 36 nm, 94.29 RIU⁻¹, 0.94, and 38.5 dB/cm, respectively. The results obtained are purely simulated using COMSOL. With the support of electric field confinement analysis, a thorough theoretical framework describes the crucial coupling regime that causes ultra-high sensitivity at low RI. This design provides new opportunities for environmental monitoring, low-abundance biomarker screening, and early-stage virus detection, where it is necessary to resolve minute RI changes with high precision. Full article

Mangrove ecosystems play a critical role in sequestering heavy metals pollutants, yet the dynamics of heavy metals accumulation during mixed litter decomposition remain poorly understood. This study investigated the seasonal and species-specific variations in heavy metals accumulation during the decomposition of Kandelia obovata (KO) and Avicennia marina (AM) leaf litter mixtures in a subtropical mangrove forest in the Jiulong River Estuary, Fujian, China. Using the litterbag technique, we monitored eight heavy metals (V, Cr, Ni, Cu, Zn, As, Se, Cd) across three mixing ratios (KO:AM = 1:2, 1:1, 2:1) in summer and winter. Results revealed that V concentrations were influenced by both season and litter ratio, with higher KO proportions enhancing V accumulation in summer but reducing it in winter. In contrast, Cr, Ni, Cu, As, Se, and Cd were primarily regulated by litter ratios: KO-dominated mixtures promoted Cr and Ni accumulation, while AM-dominated mixtures favored Cu, As, Se, and Cd. Zn exhibited the highest variability and was unaffected by season or ratio. Total organic carbon (TOC) and carbon/metal (C/M) ratios significantly correlated with reduced bioavailability of most heavy metals, whereas total nitrogen (TN) and C/N ratios showed no consistent relationship. The heavy metals accumulation index (MAI) indicated higher accumulation in summer than in winter, with the highest MAI observed in the KO:AM = 2:1 treatment group during summer (MAI = 1.36), whereas winter decomposition slowed accumulation rates. These findings highlight the dual regulatory roles of species composition and environmental factors in mangrove heavy metals cycling, offering critical insights for ecological risk assessment and contaminated soil remediation strategies in coastal ecosystems. Full article

Esterases catalyze the hydrolysis and transesterification of short-chain fatty acid esters, and microbial esterases are used in the production of biofuels, cosmetics, food, and pharmaceuticals. The soil strain Bacillus paralicheniformis T7 secretes enzymes with esterase activity; however, many bacterial enzymes remain insufficiently studied. Therefore, this study aimed to identify and characterize novel GDSL esterases produced by B. paralicheniformis. Protein mass spectrometry, combined with proteomics and genomics, identified genes encoding two GDSL esterases, which were cloned into the pET-28c(+) vector. The resulting proteins were obtained in Escherichia coli BL21(DE3) as the recombinant esterases rEST-24 and rEST-28. These recombinant GDSL esterases showed maximum activity at 40 °C and pH 7.0. Moreover, Ca²⁺, Zn²⁺, Cu²⁺, and Fe²⁺ ions inhibited their activity, and rEST-28 was resistant to the detergents Tween-20, Tween-80, and Triton X-100. High-yield esterase activity was detected in bacteria cultured on feather medium and nutrient broth, and submerged fermentation of the B. paralicheniformis T7 strain on feather medium enabled the production of an esterase extract exhibiting activity of 17,618 ± 610 U/g. These results suggest that the B. paralicheniformis T7 strain can produce esterases and shows promising potential for application in technologies that degrade fatty acid esters using hydrolytic enzymes. 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

The objective of this research was to investigate how injectable trace minerals and vitamins influence the mineral and vitamin status, hematological parameters, antioxidant capacity, metabolic profile, and performance of Nellore calves during the pre-weaning phase. A total of 38 grazing Nellore male calves with access to creep feeding were randomly assigned to two treatments: injectable supplementation of saline solution (saline; n = 19) or injectable supplementation of trace minerals (copper, manganese, zinc, and selenium) and vitamins (A and E) (ITMV; n = 19), administered on days 75 and 150 of the calves’ age. The injectable supplementation did not affect (p > 0.05) body weight, average daily gain, body measurements, or carcass measurements throughout the experimental period from 75 to 218 days (7 days before weaning) of age. However, ITMV-treated calves showed higher (p ≤ 0.05) liver concentrations of Cu and Se on day 195 than saline calves. Higher plasma concentrations of Cu (days 195 and 218) and Se (days 135, 195, and 218) were observed for ITMV calves compared to the saline group. Furthermore, the ITMV group showed greater (p ≤ 0.05) glutathione peroxidase activity, higher red blood cell count, hemoglobin, and hematocrit levels, and a lower neutrophil/lymphocyte ratio (p = 0.04). In the metabolic profile, only a day effect was observed (p ≤ 0.05). In conclusion, the injectable supplementation of trace minerals and vitamins in suckling Nellore calves improved copper and selenium status and optimized antioxidant capacity and hematological parameters, in addition to modulating the immune response towards a less inflammatory state, although it did not affect performance or the metabolic profile. Full article

The coexistence of Cu in copper sulfate electrolyte significantly affects the microstructure and performance of the copper foil. So far, there has been little quantitative analysis of Cu⁺ in the electrolyte during the copper foil production process. This paper fabricated a 2,2′-Biquinoline (BIQ) modified expanded graphite (EG) electrode electrochemical sensor for the selective determination of Cu⁺. EG, with its large specific surface area and excellent adsorption and electrochemical properties, significantly enhances analytical sensitivity. Additionally, BIQ’s specific coordination with Cu⁺ improves the sensor’s rapid and effective quantification of Cu⁺ in the electrolytic copper foil electrolyte. The linear equation of this sensor is I = 0.03769 + 0.29997 × c (R² = 0.9989), with a detection limit of 8 μg/L (S/N = 3). The BIQ-modified EG electrode has good selectivity for Cu⁺, with a recovery rate for cuprous ions of 101.00% to 105.00% under the coexistence of 10,000 times Cu²⁺, and an RSD of less than 2%. This sensor’s efficient, sensitive, and selective detection of Cu⁺ can be an effective method to improve the quality of electrolytic copper foil products. Full article

Cu-SSZ-13, the most widely used catalyst in diesel selective catalytic reduction (SCR) systems, often suffers severe deactivation, including hydrothermal aging and ash poisoning. In comparison with traditional impregnation in laboratory work, a more realistic solid-state diffusion method was employed to simulate K₂SO₄ poisoning on a commercial Cu-SSZ-13 catalyst with high aluminum and copper contents. Hydrothermal aging at 650 °C alone induces severe framework dealumination and transformation of isolated Cu²⁺ ions to copper aluminate (CuAlO_x) species. K₂SO₄ poisoning alone is more prone to detached Cu²⁺ ions and aluminum terminal hydroxyl group to form CuSO₄ and Al₂(SO₄)₃. The presence of water vapor during K₂SO₄ poisoning dramatically reduces SCR activity by accelerating the ion-exchange between K⁺ and Cu²⁺ and zeolite dealumination. These synergistic effects promote extensive detachment of active Cu species, resulting in the formation of predominating inert sulfates, along with a small amount of CuO_x clusters. These findings are expected to provide a theoretical basis for designing catalysts with enhanced resistance to both hydrothermal aging and ash poisoning in diesel aftertreatment applications. Full article

Rapid industrialization and urbanization have drawn increasing attention to the problem of agricultural potentially toxic element (PTE) pollution. Identifying priority control sources and elements through risk-based quantification of farmland PTE pollution sources is pivotal for effective soil pollution prevention and control. By investigating agriculture fields in Pengzhou, China, the pollution sources of soil PTEs (Cr, Cu, Ni, Zn, Pb, Cd, Hg, and As) were identified and quantified by a positive matrix factorization (PMF) receptor model, and their ecological and human health risks were quantitatively assessed by combining risk exposure with source profiles. The results revealed that point percentages of soil Zn, Cr, Ni, Cu, and Cd concentrations exceeding their corresponding environmental risk screening values were 0.98%, 2.94%, 16.67%, 5.88%, and 80.39%, respectively. The soil PTEs originated from atmospheric deposition, industrial emission, farming activities, and natural sources, which accounted for 22.73%, 39.94%, 24.43%, and 12.90%, respectively. Ecological and human health risk assessments showed that Cd contributed the most to ecological risk, whereas Cr posed the greatest human health exposure risk. Source-oriented risk assessment indicated that agricultural activities predominantly contributed to ecological risk, while industrial emissions primarily affected human health. These findings indicated that the source contributing most to soil PTE concentrations may not necessarily pose the greatest risk. Overall, agricultural and industrial sources, along with Cd and Cr, were identified as priority targets for control. Policies promoting scientific use of fertilizers and pesticides in the agricultural sector, along with technological upgrades and emission controls in the industrial sector, should be implemented to mitigate exposure risks and promote sustainable soil health. Full article

This study examines the joining characteristics of Cu foil stacks to lead tabs using green-laser welding in the main-welding step of a sequential welding process for lithium-ion pouch cells. The influence of lap configuration, line and wobble seam strategies, and process parameters was systematically investigated in terms of bead morphology, mechanical performance, metallurgical characteristics, and electrical resistance. Under the present line-welding parameter window (2.0 kW, 100–200 mm/s), humping, pinholes, and porosity were observed, particularly in the upper lead-tab configuration, which is attributed to melt-pool/keyhole instability under the applied conditions. Wobble welding effectively suppressed these defects in the foil-stack configuration by promoting stable melt flow and efficient bubble expulsion. Mechanical tests revealed that the wobble-based seam strategy achieved a maximum tensile–shear load of approximately 1.28 kN at a wobble amplitude of 0.8 mm. Fracture analysis confirmed a transition from seam-type interfacial failure in line welding to ductile tearing in the heat-affected zone with wobble welding. In electrical performance, wobble welding reduced resistance to as low as 45 µΩ at a wobble amplitude of 1.2 mm, while line welding yielded higher and scattered values. These results should be interpreted as the combined outcome of the wobble-based seam strategy (beam oscillation together with overlapped stitch welding at a lower travel speed) under the present processing windows. A strictly matched A/B comparison at identical linear energy density and seam layout will be investigated in future work to isolate the effect of oscillation. Full article

Successful establishment of resource-efficient perennial crops that can thrive and produce economically viable yields under metal stress conditions requires a clear understanding of macronutrient uptake and metal detoxification regulation mechanisms particularly during crop establishment period. Therefore, this study aimed to evaluate the partitioning of macronutrients and metals in miscanthus and switchgrass grown on metal-contaminated soils, and to evaluate the effect of biostimulant treatments on early crop establishment and biomass productivity. Field trials were conducted with two perennial C₄ grasses, miscanthus (Miscanthus lutarioriparius) and switchgrass (Panicum virgatum L.), under three treatments: control (CK), humic acid (HA), and humic acid combined with microbial inoculants (HAM). At final growth stages, agronomic traits, biomass quality, and macronutrient (N, P, K) and metal (Cd, Cr, Pb, Cu, Zn) contents were analyzed. To investigate metal and macronutrient partitioning dynamics, samples were collected from October to December. The HAM treatment significantly enhanced biomass yield and morphological parameters in both species, particularly in miscanthus. Both HA and HAM improved cellulose and hemicellulose while reducing the lignin content, thereby improving biomass quality. For both crops, roots served as the primary organ for metal accumulation across growth stages. In miscanthus roots from October to December, the proportions of Cd, Cr, and Pb increased (10.5%, 10.8%, 13.6%), while Zn and Cu decreased (6.5%, 11.6%). Over the same period, Pb increased slightly (4.4%), but Cd, Cr, and Cu declined (26%, 1.9%, 12.9%) in switchgrass roots. Coupling and principal component analyses revealed weak macronutrient–metal synchronization in both miscanthus and switchgrass across growth stages. Full article

Two crystalline complexes, (2,2′-bipyridine)Cu(CH₃COO)₂·5H₂O (3) and (2,2′-bipyridine)Cu(CH₃COO)₂·CH₃CN (4), have been isolated and characterized by low-temperature single-crystal X-ray diffraction experiments. Crystals of phase 3 were studied previously at room temperature (296 K) under conditions leading to rapid desolvation and less distinct characterization of the waters of crystallization. With our redetermination of 3 at 100(2) K, we present a detailed description of ribbon-like structure formed by water molecules in crystals of (2,2′-bipyridine)Cu(CH₃COO)₂·5H₂O. Acetate oxygens are linked by hydrogen-bonding to two inequivalent waters separated by 4.72 Å; the other three water molecules are trapped in polymeric ribbons of anticooperative hydrogen-bonded six-membered rings fused with cooperative hydrogen-bonded four-rings. Water oxygens of the fused ring ribbons associate only with other water oxygens, and this water structure has a local density and pair distribution function which resembles that of liquid water. Crystals of 4 are monoclinic, with acetonitrile of solvation unassociated with the complex. In both 3 and 4, bipyridine planes interleave through π-aryl stacking. Full article

This study investigates the effects of polypropylene microplastics (PP-MPs) and copper (Cu), applied individually and in combination, on the growth (root and shoot length, fresh and dry biomass), peroxidase (POD) activity, and Cu accumulation of rice seedlings. A hydroponic experiment was conducted with four treatments: control (CK), PP, Cu, and PP+Cu. Exposure to PP-MPs slightly promoted seedling growth, whereas Cu markedly inhibited growth and induced chlorosis. Compared with Cu alone, co-exposure to PP-MPs and Cu (PP+Cu) partially improved shoot growth and alleviated Cu-induced suppression of shoot POD activity. In contrast, root POD activity showed the strongest reduction under PP+Cu (91.7% decrease), revealing a pronounced root–shoot divergence in antioxidant responses. Moreover, total Cu accumulation in seedlings increased by 12.3% in PP+Cu relative to Cu alone, implying that PP-MPs may influence Cu bioavailability and/or internal partitioning. However, Cu speciation and subcellular distribution were not quantified in this study and should be examined in future work. Overall, PP-MPs may simultaneously enhance Cu uptake while partially mitigating shoot-level toxicity, underscoring the complexity of microplastic–metal co-contamination in rice seedling systems. Full article

This study assesses the distribution of nutrients, trace elements, and heavy metals across different granulometric fractions of municipal solid waste (MSW) compost from three regions: Kaunas and Alytus (Lithuania) and Daugavpils (Latvia). Samples were collected from mechanical biological treatment plants (MBTPs) and fractionated into six different granulometric fractions (>5 mm, 5–2.5 mm, 2.5–1 mm, 1–0.5 mm, 0.5–0.2 mm, and <0.2 mm). Each fraction was subjected to physicochemical characterization. Macronutrients (Ca, K, Mg, P), trace elements (Al, As, Co, Fe, Mn, Mo), and heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) were analyzed using ICP-OES in triplicate. Results showed that essential nutrients and toxic metals were retained more in the finer fractions (<1 mm). In contrast, undesirable impurities, mainly glass, were retained in the coarse fractions across all the studied areas. All fractions in the compost samples of Kaunas, and coarse fractions (>5 mm, and 5–2.5 mm) of Alytus and Daugavpils are suitable to use as a soil amendment only if the undesirable impurities are removed to the acceptable limits in the coarse fractions. The fine fractions of Alytus have higher levels of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn), while Daugavpils showed higher levels of Cd, Cu, Ni, and Zn, exceeding the EU limits. Regarding physical fractionation, results showed that nutrients and heavy metals increased in the compost as particle size decreased. Our findings suggest that removing particle sizes < 1 mm and large impurities from the coarse fractions can enhance compost quality. Overall, particle-size fractionation can improve the consistency and safety of MBT-derived MSW compost for reuse in circular waste management systems. Full article

Contamination of drinking water by potentially toxic elements (PTEs) remains a critical public-health concern in Uganda. This systematic review compiled and harmonized quantitative concentrations (mg/L) for key PTEs, lead (Pb), cadmium (Cd), arsenic (As), chromium (Cr), mercury (Hg), copper (Cu), zinc (Zn), nickel (Ni), cobalt (Co), manganese (Mn), and iron (Fe), across various potable and informal water sources used for drinking, including municipal tap water, boreholes, protected and unprotected springs, wells, rainwater, packaged drinking water, rivers, lakes, and wetlands. A comprehensive search of different databases and key institutional repositories yielded 715 records; after screening and eligibility assessment, 161 studies met the inclusion criteria, and were retained for final synthesis. Reported PTE concentrations frequently exceeded WHO and UNBS drinking water guidelines, with Pb up to 8.2 mg/L, Cd up to 1.4 mg/L, As up to 25.2 mg/L, Cr up to 148 mg/L, Fe up to 67.3 mg/L, and Mn up to 3.75 mg/L, particularly in high-risk zones such as Rwakaiha Wetland, Kasese mining affected catchments, and Kampala’s urban springs and drainage corridors. These hotspots are largely influenced by mining activities, industrial discharges, agricultural runoff, and corrosion of aging water distribution infrastructure, while natural geological conditions contribute to elevated background Fe and Mn in several regions. The review highlights associated health implications, including neurological damage, renal impairment, and cancer risks from chronic exposure, and identifies gaps in regulatory enforcement and routine monitoring. It concludes with practical recommendations, including stricter effluent control, expansion of low-cost adsorption and filtration options at household and community level, and targeted upgrades to water-treatment and distribution systems to promote safe-water access and support Uganda’s progress toward Sustainable Development Goal 6. Full article