Search Results (248)

Seafood contamination by heavy metals is a growing public health concern, particularly in regions like Tunisia where seafood is a major dietary component. This study assessed concentrations of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in the muscle tissue of the red shrimp Parapenaeus longirostris, collected in 2023 from four coastal regions: Bizerte, Monastir, Kerkennah, and Gabes. Metal analysis was conducted using flame atomic absorption spectroscopy. This species was chosen due to its ecological and economic importance. The study sites were chosen based on their differing levels of industrial, urban, and agricultural influence, providing a representative overview of regional contamination patterns. Mean concentrations were 1.04 µg/g for Zn, 0.59 µg/g for Cu, 1.56 µg/g for Pb, and 0.21 µg/g for Cd (dry weight). Pb was the most prevalent metal across sites. Statistically significant variation was observed only for Cu (p = 0.0334). All metal concentrations were below international safety limits set by FAO/WHO and the European Union. Compared to similar studies, the levels reported were similar or slightly lower. Human health risk was evaluated using target hazard quotient (THQ), hazard index (HI), and cancer risk (CR) values. For adults, THQ ranged from 5.44 × 10⁻⁶ to 8.43 × 10⁻⁴, while for children it ranged from 2.40 × 10⁻⁵ to 3.72 × 10⁻³. HI values were also well below 1, indicating negligible non-carcinogenic risk. CR values for Cd and Pb in both adults and children fell within the acceptable risk range (10⁻⁶ to <10⁻⁴), suggesting no significant carcinogenic concern. This study provides the first field-based dataset on metal contamination in P. longirostris from Tunisia, contributing valuable insights for seafood safety monitoring and public health protection. Full article

Aircraft, as electromagnetically complex targets, have radar cross-sections (RCSs) that are influenced by various factors, with the inlet duct being a critical component that often serves as a primary source of electromagnetic scattering, significantly impacting the scattering characteristics. In light of the conflict between aerodynamic performance and electromagnetic characteristics in the design of aircraft engine inlet grilles, this paper proposes a metasurface radar-absorbing inlet grille (RIG) solution based on a NACA symmetric airfoil. The RIG adopts a sandwich structure consisting of a polyethylene terephthalate (PET) dielectric substrate, a copper zigzag metal strip array, and an indium tin oxide (ITO) resistive film. By leveraging the principles of surface plasmon polaritons, electromagnetic wave absorption can be achieved. To enhance the design efficiency, a multi-objective Bayesian optimization framework driven by the expected hypervolume improvement (EHVI) is constructed. The results show that, compared with a conventional rectangular cross-section grille, an airfoil-shaped grille under the same constraints will reduce both aerodynamic losses and the absorption bandwidth. After 100-step EHVI–Bayesian optimization, the optimized balanced model attains a 57.79% reduction in aerodynamic loss relative to the rectangular-shaped grille, while its absorption bandwidth increases by 111.99%. The RCS exhibits a reduction of over 8.77 dBsm in the high-frequency band. These results confirm that the proposed optimization design process can effectively balance the conflict between aerodynamic performance and stealth performance for RIGs, reducing the signal strength of aircraft engine inlets. Full article

The study of the impact of anthropogenic and natural pollution on living organisms has become a major social issue. In this context, the objective of this work is to assess the use of the polychaete annelid Hediste diversicolor as a bioindicator organism for the quality of the marine environment. The concentration of four heavy metals (lead, copper, zinc, and cadmium) was determined in natural populations of H. diversicolor captured from four locations along the Tunisian coast using atomic absorption spectroscopy. Concentration ranges (µg/g dry weight) across all sites were as follows: Cd (0.12–0.43), Cu (3.80–6.45), Zn (18.35–42.78), and Pb (22.64–63.91). Statistical analysis confirmed significant spatial variation (Pb: F = 12.15, p < 0.001; Zn: F = 3.32, p = 0.04; Cd: F = 48.66, p < 0.001; Cu: F = 9.08, p < 0.001), with peak Pb in Bizerte and Cu in Sfax. These results highlight the influence of local environmental factors, such as industrial and urban pollution on metal accumulation in Hediste diversicolor. In this study, the accumulation of the analyzed elements in the tissues of H. diversicolor follows an increasing order as follows: Cd < Cu < Zn < Pb. Additionally, lead metal concentrations were higher than those of cadmium, zinc, and copper for all four studied locations. To our knowledge, this is the first study in Tunisia to assess heavy metal accumulation in H. diversicolor. The recorded levels were similar to, or lower than, those reported in other studies worldwide. These findings underscore the potential of H. diversicolor as a sensitive and effective bioindicator for monitoring coastal contamination and guiding environmental management strategies in Tunisia. Full article

This study aimed to compare the contents of copper (Cu), zinc (Zn), magnesium (Mg), and iron (Fe) in healthy liver tissue from deceased liver donors (DGs), in cirrhotic tissue from patients without (CIR) or with hepatocellular carcinoma (CIR-HCC) and in HCC tissue from the latter patients. Liver tissue samples were obtained from cirrhotic liver transplant recipients, with (n = 14) and without HCC (n = 14), and from DGs (n = 18). In patients with HCC, both cirrhotic and tumor tissue was collected. The tissue metal content was measured using atomic absorption spectrometry. The Cu content of DG tissue was significantly lower than that of CIR-HCC and HCC tissue but not CIR tissue. The tissue Zn and Mg contents were significantly higher in DG tissue than in CIR, CIR-HCC, and HCC tissues. No difference was observed for Fe. The Cu/Zn ratio progressively increased in DG, CIR, CIR-HCC, and HCC tissues. The increased Cu content in cirrhotic and tumor tissue of HCC patients and the fact that the latter had the highest value for the Cu/Zn ratio indirectly suggest the potential role of these metals in hepatocarcinogenesis. These findings support a pathophysiological basis for further experimental studies to investigate the potential therapeutic implications of pharmacological agents targeting metal homeostasis in this malignancy. Full article

This study demonstrated the successful recovery of zinc, lead, and copper collective concentrates from historical metal-bearing mine tailings (sulfide–polymetallic ore with a composition of 7.38% Zn, 1.45% Pb, and 0.49% Cu) using froth flotation techniques, which were originally developed during uranium ore mining. Froth flotation techniques were used to justify suitability for recovering metals. The effects of a dosage of the foaming agent Polyethylene glycol (PEG 600) at 50 and 100 g t⁻¹, collector types Aerophine 3418A (AERO), Danafloat 067 (DF), and potassium ethyl xanthate (KEX) at 50 and 80 g t⁻¹, and a suspension density of 300 and 500 g L⁻¹ on froth flotation collective concentrates were investigated. The final collective concentrate achieved recoveries exceeding 91% for lead (Pb), 88% for copper (Cu), and 87% for zinc (Zn). The obtained concentrates were analyzed using Atomic Absorption Spectroscopy (AAS) and X-ray Fluorescence Spectrometry (XRF), while selected samples were further examined via Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS). The resulting sulfide concentrates can subsequently be treated using suitable hydrometallurgical techniques. The application of these concentrates in metal production would help reduce the environmental burden of mining activities. Full article

Eugenol-based azo dyes illustrate how bio-sourced compounds like eugenol can be transformed through synthetic processes into functional and colorful compounds. The main purpose of the present work was to develop new responsive colorimetric sensors for metal cations based on eugenol-derived azo compounds. The incorporation of the azo group into the eugenol framework allows for strong electronic interactions with metal cations, leading to distinct color changes observable to the naked eye. These azo-eugenol dyes exhibit shifts in their UV-Vis absorption spectra upon complexation with metal cations such as copper (Cu²⁺) and lead (Pb²⁺), making them effective sensors for environmental and analytical applications. The eugenol-based azo dyes were subjected to photophysical studies to understand selectivity, response time, and stability in relation to metal cations, which will be a starting point for the monitoring of toxic metal contaminants in aqueous environments. Full article

Heavy metal soil pollution in urban areas is a critical environmental, public health, and sustainable living issue. The quantities of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in urban soils in Larissa, Greece, are evaluated in this study along with their risks to human health. A total of 198 surface soil samples were collected from green areas over a three-year period (2021–2023) and analyzed using atomic absorption spectrometry. The results show that Zn has the highest mean concentration (99.80 mg/kg in the summer), followed by Cu (57.33 mg/kg), Pb (48.60 mg/kg), and Cd (0.10 mg/kg). Seasonal variations revealed increased metal levels in the summer due to reduced soil moisture and atmospheric deposition. For assessing the level of pollution in Larissa’s urban areas, thematic maps were created. Using the United States Environmental Protection Agency (USEPA) risk assessment framework, model estimates indicated that ingestion was the dominant exposure route, with children predicted to experience higher non-carcinogenic risks than adults due to the model default exposure assumptions. The hazard quotient (HQ) for Pb in children with soil-pica disorder reached 6.79, exceeding the safe threshold (HQ = 1), indicating significant adverse health risks. Although average metal concentrations were within EU safety limits, the cumulative health risk assessment highlights the need for continuous monitoring and pollution mitigation strategies in urban environments. Full article

Cadmium (Cd) contamination in soil poses a serious threat to plant growth and productivity, while arbuscular mycorrhizal (AM) fungi play a vital role in enhancing plant growth, improving tolerance to heavy metals, and restoring polluted ecosystems. To enhance the tolerance of Astragalus sinicus to Cd stress, a pot experiment was conducted to investigate the effects of inoculation and copper (Cu) addition on growth, Cd accumulation, and translocation under Cd-stressed soil conditions. The results showed that Cd inhibited the root growth of A. sinicus, and AM fungi inoculation and Cu + AM significantly increased root biomass and root volume (p < 0.05). Under Cd stress, AM fungi inoculation reduced Cd concentration by 72.40% in the shoots, while it increased by 92.69% in the roots. Both AM fungi inoculation and Cu + AM enhanced Cd uptake in the roots, while inhibiting Cd translocation to the shoots. After the application of Cu and inoculation with AM fungi, the roots have a strong absorption and enrichment ability for Cd; the bioconcentration factor of Cd in the roots of A. sinicus reached 1018.59% and 366.08%, respectively. Cu + AM increased the enrichment of Cd in the roots and restricted its translocation to the shoots. Moreover, the combination of AM fungi inoculation and Cu addition significantly increased soluble sugar (by 77.29%) and proline contents (by 445.62%) and reduced CAT activity (by 74.67%) under Cd stress. In summary, both Cu addition and AM fungi inoculation promoted the growth of A. sinicus under Cd stress, improved its physiological metabolism, and reduced Cd content in the soil, with the combined Cu and AM fungi treatment showing the most significant effect. Full article

In this paper, we present the analysis of functional alloy samples containing metals aluminum (Al), copper (Cu), lead (Pb), silicon (Si), tin (Sn), and zinc (Zn) using a Q-switched Nd laser operating at a wavelength of 532 nm with a pulse duration of 5 ns. Nine pelletized alloy samples were prepared, each containing varying chemical concentrations (wt.%) of Al, Cu, Pb, Si, Sn, and Zn—elements commonly used in electrotechnical and thermal functional materials. The laser beam is focused on the target surface, and the resulting emission spectrum is captured within the temperature interval of $9.0\times {10}^3$ to $1.1\times {10}^4$ K using a set of compact Avantes spectrometers. Each spectrometer is equipped with a linear charged-coupled device (CCD) array set at a 2 μs gate delay for spectrum recording. The quantitative analysis was performed using calibration-free laser-induced breakdown spectroscopy (CF-LIBS) under the assumptions of optically thin plasma and self-absorption-free conditions, as well as local thermodynamic equilibrium (LTE). The net normalized integrated intensities of the selected emission lines were utilized for the analysis. The intensities were normalized by dividing the net integrated intensity of each line by that of the aluminum emission line (Al II) at 281.62 nm. The results obtained using CF-LIBS were compared with those from the laser ablation time-of-flight mass spectrometer (LA-TOF-MS), showing good agreement between the two techniques. Furthermore, a random forest technique (RFT) was employed using LIBS spectral data for sample classification. The RFT technique achieves the highest accuracy of ~98.89% using out-of-bag (OOB) estimation for grouping, while a 10-fold cross-validation technique, implemented for comparison, yields a mean accuracy of ~99.12%. The integrated use of LIBS, LA-TOF-MS, and machine learning (e.g., RFT) enables fast, preparation-free analysis and classification of functional metallic materials, highlighting the synergy between quantitative techniques and data-driven methods. Full article

Biochar is a stabilised, carbon-rich material created when biomass is heated to temperatures usually between 450 and 550 °C, under low-oxygen concentrations. This study evaluated the effectiveness of sawdust, cocoa pod ash and rice husk biochars in remediating metal-contaminated paddy soil in Nobewam, Ghana. Biochar was applied 21 days before cultivating the rice for 120 days, followed by soil sampling and rice harvesting for metals and physicochemical analyses. Compared to the untreated soils, biochar treatments exhibited an enhancement in soil quality, characterised by an increase in pH of 1.01–1.20 units, an increase in available phosphorus (P) concentration of 6.76–13.05 mg/kg soil and an increase in soil total nitrogen (N), and organic carbon (OC) concentration, ranging from 0.02% to 0.12%. Variabilities in electrical conductivity and effective cation exchange capacity were observed among the treated soils. Concentrations of potentially toxic metals (arsenic, cadmium, copper, mercury, lead and zinc) in paddy soils and rice analysed by atomic absorption spectroscopy showed significant differences (p < 0.05) among the sampled soils. The concentrations of arsenic and lead in all soil samples exceeded the Canadian Council of Ministers of the Environment soil quality guideline for agricultural soils, with untreated soils having the highest levels among all the soils. Cadmium had a potential ecological risk index > 2000 and a geoaccumulation index above 5, indicating pollution in all samples. In contrast, arsenic and mercury contamination were only found in the untreated soils. Among the tested treatments, rice husk and its combinations, particularly with cocoa pod ash, showed significant efficacy in reducing metal concentrations in the soils. The potential non-carcinogenic human health risks associated with the consumption of rice grown in biochar-treated soils were lower for all the metals compared to the control samples. Future research should focus on long-term field studies to validate these findings and explore the underlying mechanisms governing metal immobilization in paddy fields. Full article

A series of porphyrinoids fused to highly electron-withdrawing bis(thiadiazolo)benzene units have been prepared and spectroscopically characterized. These structures have modified chromophores and exhibit large bathochromic shifts. The nickel(II), copper(II) and zinc complexes of a bis(thiadiazolo)benzoporphyrin were prepared, and these showed strong absorptions above 600 nm that shifted to longer wavelengths with increasing atomic number for the coordinated metal cations. Although the investigated porphyrinoids were poorly soluble, proton NMR data could be obtained, and these demonstrated that the structures possess global aromatic character. This was confirmed with nucleus-independent chemical shift (NICS) calculations and anisotropy of induced current density (AICD) plots. The AICD plots also demonstrate that the fused heterocyclic unit is disconnected from the porphyrinoid π-system, and in this respect, it differs from phenanthroline-fused porphyrinoids as it shows the presence of extended conjugation pathways. Full article

Photocatalytic H₂ production is one of the most promising approaches for sustainable energy. The literature presents a plethora of carefully designed systems aimed at harnessing solar energy and converting it into chemical energy. However, the main drawback of the reported photocatalysts is their stability. Thus, the development of a cost-effective and stable photocatalyst, suitable for real-world applications remains a challenge. An ideal photocatalyst for H₂ production must possess appropriate band-edge energy positions, an effective sacrificial agent, and a suitable cocatalyst. Among the various photocatalysts studied, TiO₂ stands out due to its stability, abundance, and non-toxicity. However, its efficiency in the visible spectrum is limited by its wide bandgap. Metal doping is an effective strategy to enhance electron–hole separation and improve light absorption efficiency, thereby boosting H₂ synthesis. Common metal cocatalysts used as TiO₂ dopants include platinum (Pt), gold (Au), copper (Cu), nickel (Ni), cobalt (Co), ruthenium (Ru), iron (Fe), and silver (Ag), as well as bimetallic combinations such as Ni-Fe, Ni-Cu, Nb-Ta, and Ni-Pt. In all cases, doped TiO₂ exhibits higher H₂ production performance compared to undoped TiO₂, as metals provide additional reaction sites and enhance charge separation. The use of bimetallic dopants further optimizes the hydrogen evolution reaction. Additionally, porphyrins, with their strong visible light absorption and efficient electron transfer properties, have demonstrated potential in TiO₂ photocatalysis. Their incorporation expands the photocatalyst’s light absorption range into the visible spectrum, enhancing H₂ production efficiency. This review paper explores the principles and advancements in metal- and porphyrin-doped TiO₂ photocatalysts, highlighting their potential for sustainable hydrogen production. Full article

During the cold metal transfer (CMT) arc additive manufacturing process of steel/copper bimetallic materials, interfacial penetration cracks have been observed due to the significant differences in thermal and physical properties between steel and copper. To mitigate the occurrence of these penetration cracks and enhance the interfacial elemental diffusion at the steel/copper junction, this study aims to fabricate high-performance steel/copper bimetallic materials with a uniform microstructure using CMT arc additive manufacturing techniques. A reciprocating additive sequence was adopted, with steel deposited first, followed by copper. Four different interlayer compositions, Cu-Ni, Fe-Ni, Cu-Cr, and Ni-Cr, were applied to the steel surface before the deposition of aluminum bronze. These interlayers served as a transition between the steel and copper materials. The manufacturing process then continued with the deposition of aluminum bronze to achieve the desired bimetallic structure. After the addition of interlayers, all four sets of samples exhibited excellent macroscopic formability, with clear and smooth interlayer contours and no visible cracks or collapse defects at the junction interfaces. The mechanical properties of the composite walls were enhanced following the addition of the interlayers, with an increase in tensile strength observed across the samples. The sample with the Fe-Ni interlayer showed the most significant improvement, with a 52% increase in impact energy absorption. Furthermore, the sample with the Fe-Ni interlayer demonstrated a higher average hardness level than the other groups, which was associated with the distribution and content of the iron-rich phase and the β′ phase. Full article

In China, soil contamination by heavy metals is a widespread issue, with substantial increases in lead(Pb), cadmium(Cd), copper(Cu), and zinc(Zn) levels observed across various regions. Particularly, the concentrations of Pb and Cd significantly exceed their natural background levels. P-ATPases, a group of proteins, utilize energy from ATP hydrolysis to support the transmembrane movement of metal ions. This group encompasses several Heavy Metal Associated Transporter (HMA) ATPases. Studies on hyperaccumulators have shown the critical role of HMAs in the movement and reduction in Zn and Cd toxicity in plant systems. This research identifies a protein encoded by the SpHMA gene from Sedum plumbizincicola, a species noted for aiding Zn/Cd hyperaccumulators, which enhances tolerance to Cd and Zn. We detail a protein encoded by SpH/A within the HMA family that enhances Cd tolerance. Real-time fluorescence quantification (RT-PCR) indicates that SpHMA3 expression in Arabidopsis thaliana and Zea mays KN5585 correlates with high Cd tolerance, linked to Cd accumulation in Zea mays. In addition, homozygous Arabidopsis thaliana AtHMA3 mutants exhibited increased Cd sensitivity compared to the wild type (WT). Notably, plants of Arabidopsis thaliana and maize overexpressing SpHMA3 showed enhanced Cd stress tolerance compared to WT. Enhanced Cd accumulation in tissues was observed when SpHMA3 was overexpressed, as revealed by subcellular distribution analysis. We propose that SpHMA3 augments maize tolerance to Cd and Zn stresses through enhanced cellular uptake and translocation of Cd ions. This investigation clarifies the gene function of SpHMA3 in Cd and Zn stress response, offering insights for enhancing heavy metal absorption traits in maize varieties and phytoremediation methods for soils contaminated with heavy metals. Full article

This paper analyzes the current state of water quality detection equipment and, based on the demand for portable water quality detection systems that are on-site, rapid, accurate, cost-effective, and capable of multi-parameter measurements using spectral analysis, represents the future development direction of water quality detection. By focusing on indicators of heavy metal ion water pollution, this study aims to achieve the “rapid and accurate detection of water quality using spectral analysis” and emphasizes key technologies such as “visible absorption spectroscopy in photoelectric detection technology and spectral analysis”, “spectral denoising methods”, and “Convolutional Neural Network (CNN) modeling and deployment”. A novel combined denoising method integrating Ensemble Empirical Mode Decomposition (EEMD) and Singular Value Decomposition (SVD) is developed and applied for the first time in spectral water quality detection to improve accuracy. The system uses a ZYNQ-based spectral analysis platform to detect heavy metal ion concentrations, enhancing detection speed. Comparative tests with copper ion standard solutions against Chinese national standards show good accuracy and reproducibility. The developed EEMD-SVD method demonstrates superior denoising effectiveness in processing actual spectral data within the water quality detection system. Full article