Search Results (123)

Quercetin, one of the most abundant flavonoids in nature, has attracted the attention of many researchers due to its chemical and biological properties. A series of metal–quercetin complexes (Cu²⁺, Co²⁺, Zn²⁺, Sn²⁺, Al³⁺, Cd²⁺ and Mg²⁺) were synthesized and systematically characterized by Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy (UV–Vis) and nuclear magnetic resonance (NMR). These analyses confirmed that the complexes predominantly form through coordination with the 4-carbonyl group and adjacent phenolic hydroxyls. This induces measurable shifts in the ν(C=O), ν(O–H), and π→π* transition bands relative to free quercetin. The antioxidant capacity of the complexes was evaluated using 2,2-Diphenyl-1-Picrylhydrazyl (DPPH^•) radical scavenging method, 2,2′-Azinobis(3-Ethylbenzothiazoline-6-Sulfonic Acid) (ABTS^•)⁺ radical activity, and Ferric Reducing Antioxidant Power (FRAP) assay. Several complexes exhibited higher radical scavenging efficiency than quercetin, with inhibition percentages exceeding 80% in the DPPH^• and ABTS^•+ assays. Others showed reduced activity due to the masking of redox-active hydroxyl groups during metal coordination. FRAP results corroborated these trends, indicating metal-dependent modulation of reducing power. Antimicrobial evaluation revealed that selected complexes were more active than free quercetin, particularly against Staphylococcus aureus and Candida spp., with minimum inhibitory concentrations (MICs) ranging from 75–250 μg mL⁻¹. Overall, metal complexation significantly alters the electronic structure and biological behavior of quercetin, highlighting the potential of metal–flavonoid complexes as multifunctional antioxidants and antimicrobials. Full article

The Xinqiao Cu-S polymetallic deposit is located in the Tongling ore concentration area of the Middle-Lower Yangtze River metallogenic belt. The orebodies consist of skarn orebodies and stratiform sulfide orebodies, but the genetic link between them remains controversial. In this study, magnetite was used as a proxy to systematically constrain the hydrothermal evolution from the intrusion to the contact zone and further to the stratiform orebodies. A representative drill hole (E603) was logged, and samples were systematically collected from the Jitou pluton outward to the contact zone. Composite samples from the 8–28 m interval were crushed and prepared as resin mounts for integrated TIMA automated mineralogy, BSE textural observation, and in situ LA-ICP-MS trace element analysis. Five types of magnetite (Mt1 to Mt5) were systematically identified. Mt1 occurs as inclusions within feldspar in the quartz monzodiorite. It exhibits typical magmatic magnetite characteristics and contains grid-like ilmenite exsolution, indicating crystallization during the late magmatic stage. Mt2 is distributed in the interstices of magmatic minerals, commonly showing hematitization and replacement of ilmenite exsolution lamellae by titanite. Its trace element geochemistry displays magmatic–hydrothermal transitional features. Mt3–Mt5 in the skarn and stratiform orebodies are paragenetic with retrograde alteration minerals (e.g., epidote, chlorite, and actinolite) and sulfides, and are characterized by low Ti, Al, and V contents and high Mg, Mn, and Sn contents, indicating a hydrothermal origin. From Mt3 to Mt5, (Ti + V) and (Al + Mn) decrease, while Zn and Mn increase, accompanied by a decrease in the (Si + Al)/(Mg + Mn) ratio. This reflects a trend of decreasing fluid temperature and progressively enhanced wall-rock buffering. The Mg-in-magnetite geothermometer yields relatively consistent results for Mt1–Mt3, but anomalously high temperatures for Mt4–Mt5. This suggests that the elevated Mg activity in the fluid, caused by reaction with carbonate wall rocks, can significantly influence the calculated temperatures. Therefore, this geothermometer should be used cautiously for magnetite in the outer skarn zone and interpreted in combination with other temperature constraints. The textures, paragenetic mineral assemblages, and trace element characteristics of magnetite collectively reveal a continuous mineralization process linking the skarn and stratiform orebodies at Xinqiao, providing robust mineralogical and geochemical evidence for the contribution of Yanshanian magmatic–hydrothermal activity to the stratiform mineralization. Full article

This work aims to enhance the stability of the Mg/Al₃Y interface through first-principles investigations of low-cost dopants. Density functional theory calculations were employed to systematically examine the bulk properties of Mg and Al₃Y, as well as the structural stability, electronic characteristics, and alloying element effects at the Mg(0001)/Al₃Y(0001) interface. The calculated lattice parameters, elastic moduli, and phonon spectra demonstrate that both Mg and Al₃Y are dynamically stable. Owing to the similar hexagonal symmetry and a small lattice mismatch (~1.27%), a low-strain semi-coherent Mg(0001)/(2 × 2)Al₃Y(0001) interface can be constructed. Three representative interfacial stacking configurations (OT, MT, and HCP) were examined, among which the MT configuration exhibits significantly higher work of adhesion, indicating superior interfacial stability. Differential charge density and density of states analyses reveal pronounced charge transfer from Mg to Al/Y atoms and strong orbital hybridization, particularly involving Y-d states, which underpins the enhanced interfacial bonding. Furthermore, the segregation behavior and adhesion enhancement effects of typical alloying elements (Si, Ca, Ti, Mn, Cu, Zn, Zr, and Sn) were systematically evaluated. The results show that Mg-side interfacial sites, especially Mg₂ and Mg₃, are thermodynamically favored for segregation, with Zr and Ti exhibiting the strongest segregation tendency and the most significant improvement in interfacial adhesion. These findings provide fundamental insights into interfacial strengthening mechanisms and offer guidance for the alloy design of high-performance Mg-based composites. Full article

The presence of trace and toxic elements in milk and dairy products is an important food safety issue, as contamination can occur along the dairy supply chain and may be influenced by animal species, production system, and processing conditions. This study aimed to investigate and compare the multi-elemental composition of milk and selected dairy products obtained from organic, conventional, and commercial production systems in north-western Romania. A total of 307 samples, including raw milk from different animal species (cow, goat, buffalo, donkey) as well as yogurt, cheese, and mozzarella, were collected from farms and retail outlets. Samples were subjected to standardized microwave-assisted acid digestion and analyzed for toxic and essential elements (Pb, Cd, Hg, As, Cr, Ni, Al, Sn, Cu, and Zn) using inductively coupled plasma mass spectrometry (ICP–MS), with quality assurance ensured through certified reference materials and proficiency testing. The results indicated low concentrations of toxic metals across all dairy matrices, with Pb ranging from 0.0047 to 0.0117 mg/kg, Cd from 0.0008 to 0.0011 mg/kg, and As from 0.0007 to 0.0664 mg/kg, depending on animal species and production system. Mercury was consistently below the limit of detection in all datasets (LCD = 100%). Essential and transition elements were systematically quantified, occurring within expected ranges (Al: 0.021–0.264 mg/kg; Cu: 0.078–0.270 mg/kg; Zn: 3.245–7.963 mg/kg; Sn ≈ 0.0030–0.0035 mg/kg). All toxic element concentrations were below the maximum limits established by European Union legislation. Variations in elemental profiles were observed between animal species and production systems, with organic cow milk showing the most homogeneous composition. All toxic element concentrations were below the maximum limits established by European Union legislation. Overall, the findings confirm the safety of the analyzed dairy products and emphasize the relevance of multi-elemental monitoring as a practical tool for dairy supply chain surveillance and risk assessment. Full article

Zinc oxide (ZnO) nanomaterials have emerged as promising candidates for gas sensing applications due to their high sensitivity, fast response–recovery cycles, thermal and chemical stability, and low fabrication cost. However, the performance of pristine ZnO remains limited by high operating temperatures, poor selectivity, and suboptimal detection at low gas concentrations. To address these limitations, significant research efforts have focused on dopant incorporation and polymer hybridization. This review summarizes recent advances in dopant engineering using elements such as Al, Ga, Mg, In, Sn, and transition metals (Co, Ni, Cu), which modulate ZnO’s crystal structure, defect density, carrier concentration, and surface activity—resulting in enhanced gas adsorption and electron transport. Furthermore, ZnO–polymer nanocomposites (e.g., with polyaniline, polypyrrole, PEG, and chitosan) exhibit improved flexibility, surface functionality, and room-temperature responsiveness due to the presence of active functional groups and tunable porosity. The synergistic combination of dopants and polymers facilitates enhanced charge transfer, increased surface area, and stronger gas–molecule interactions. Where applicable, sol–gel-based studies are explicitly highlighted and contrasted with non-sol–gel routes to show how synthesis controls defect chemistry, morphology, and sensing metrics. This review provides a comprehensive understanding of the structure–function relationships in doped ZnO and ZnO–polymer hybrids and offers guidelines for the rational design of next-generation, low-power, and selective gas sensors for environmental and industrial applications. Full article

The aim of this study is to determine the spatial distribution of geochemical anomalies of selected potential toxic elements in the soils of the river basins in the Northeastern Caucasus—specifically the Ulluchay, Sulak, and Sunzha Rivers. A concentration of 25 chemical elements was measured using inductively coupled plasma mass spectrometry (ICP-MS). Petrogenic elements commonly found in the Earth’s crust (Al, Na, Ca, Fe, Mg) showed high concentrations (Na up to 306,600.70 mg/kg). Conversely, concentrations of Ag, Cd, Sn, Sb, and Te at many sampling sites were extremely low, falling below the detection limits of analytical instruments. The geochemical indicators Cf (contamination factor) and Igeo (geoaccumulation index) indicate that the regional characteristics of the territory, such as lithological conditions, hydrochemical schedules, and the history of geological development of the territory, affect the concentration of elements. Anomalous concentrations were found for seven elements (Ba, Na, Zn, Ag, Li, Sc, As), whereas no anomalies were identified for Be, Mg, Al, Mn, Fe, Co, Ni, Cu, Pb, Te, and Cs. For the most part (8 of 10), the sampling sites with anomalous chemical element content are located in the basin of the Sunzha River. Two sites with anomalous chemical element content have been identified in the Sulak River Basin. Anomalous values in the Sulak River Basin are noted for two chemical elements—Ba and Na. Natural features such as geological structure, parent rock composition, vertical climatic zonation, and landscape diversity play a major role in forming geochemical anomalies. The role of anthropogenic factors increases in localized areas near settlements, industrial facilities, and roads. The spatial distribution of geochemical anomalies must be considered in agricultural management, the use of water sources for drinking supply, the development of tourist routes, and comprehensive spatial planning. Full article

Background: Foods containing nutraceuticals from the mineral element group are being developed to compensate for the problem of deficiency in billions of people around the world. This research focuses on essential elements of patented cereal-based mixtures to complement the deficiencies of these elements and, at the same time, assesses their safety in terms of toxic elements in the human diet. Methods: The mineral and trace element contents in the mixtures were determined using the ICP-MS method with a subsequent evaluation of the contributions of the mixtures to the essential and toxic reference values based on dietary intakes and exposures for adults at 60, 80 and 100 kg of adult body weight and a portion size of 50 g. The potential health risk was evaluated using a metal pollution index. Results: The concentrations of minerals and trace elements in the cereal-based mixtures analyzed were as follows: K (up to 4150 µg/g) ≥ P > Mg > Ca > Na > Fe > Zn > Mn > Cu > Al > Ba (up to 4.40 µg/g) > Sr (up to 480 ng/g) ≥ Ti ≥ Ni > Ce ≥ Co > As ≥ Cs > Ag ≥ Li > Se > Be > Cr > Tl > Pb ≥ Hg > Ho > Cd > Sn (up to 1.12 ng/g). The mixtures contribute significantly to the reference values for Mn, Cu, Zn, Fe, and P for adults. Individual dietary exposure values of toxic elements for adults weighing 60 kg decrease in this order: Al (10.1 µg/kg bw/day) > Ni (362 ng/kg bw/day) > As ≥ Pb > Ag > Hg > Cd > and Sn (0.93 ng/kg bw/day). Conclusions: In terms of Regulation (EU) No 1924/2006 of the European Parliament and of the Council on nutrition and health claims made on foods, the cereal-based mixtures could be labelled “source of” Mn, Cu, Zn, Fe, and P when their contributions to the reference values exceeded 15%; in addition, “low sodium/salt” or “very low sodium/salt” can be applied. The mixtures contribute insignificantly to the toxic reference values of Al, Sn, Hg, Cd, Ni, and Ag, and the exposure values of Pb for developmental neurotoxicity, nephrotoxicity, and cardiovascular effects were considered safe. Regarding the metal pollution index of mixtures, there is no concern for potential health effects. Cereal-based mixtures are suitable for use in the food industry as a potential source of beneficial micronutrients for the human diet, although bioaccessible studies should not be neglected. Full article

The health impacts of atmospheric fine particulate matter (PM_2.5) in plateau regions have attracted concerns, along with local population growth and rapid urbanization. This study collected PM_2.5 samples at summer and winter in Xining, a city located in the northeastern Tibetan Plateau. The chemical composition of PM_2.5 and its cytotoxicity on human lung epithelial cells (A549) are characterized, and composition–cytotoxicity correlation is discussed. The toxic mechanisms of PM_2.5 in different seasons were further investigated through metabolomic analysis using high-resolution mass spectrometry. The average PM_2.5 mass concentration in Xining during winter was 2.10 times higher than that during summer. The carbonaceous components in PM_2.5 were dominated by OC, while the main water-soluble ions were SO₄²⁻, NO₃⁻, and NH₄⁺, with Mg, Al, Fe, and Ca also present in high concentrations in metal elements. LDH and ROS emerged as the most PM_2.5-affected toxicity indices in summer (34.59 ± 4.86 ng/L, 1.19× control) and winter (8.62 ± 1.25 ng/mL, 1.77× control), respectively. OC, Cl⁻, F⁻, Sn, Cr, SO₄²⁻, Pb, Zn, Mg, NO₃⁻, and NH₄⁺ may synergistically exacerbate oxidative stress and inflammatory responses on A549 cells in Xining. Furthermore, glutathione metabolism, amino acid metabolism, and sphingolipid metabolism were identified as key pathways influencing cellular oxidation and inflammation. Thimonacic, 9-(2,3-dihydroxypropoxy)-9-oxononanoic acid, and hypoxanthine were common metabolites in both seasons. Our findings greatly enhance the understanding of health risks associated with PM_2.5 in the plateau city. Full article

This study systematically examines the influence of Zn addition (≤0.6 wt.%) on the microstructure and mechanical properties of Mg-2Al-0.8Sn-0.5Ca (wt.%) alloys. Minor Zn alloying marginally increases secondary phase fraction in as-cast alloys, with complete Zn dissolution achieved after solution treatment and asymmetric severe shear extrusion. Extruded alloys exhibit non-monotonic strength evolution with Zn content, peaking at 0.2 wt.% Zn (yield strength ≈ 235.1 MPa, ultimate tensile strength ≈ 289.2 MPa), while elongation reaches 16.1%. This strength enhancement originates from synergistic grain boundary, solid-solution, and dislocation strengthening mechanisms. These results demonstrate Zn’s critical role in optimizing the strength-ductility balance of rare-earth-free magnesium alloys. Full article

The separation of particles smaller than 1 µm either by composition or by size is still a challenge. For the separation of SiO₂ and SnO₂, the creation of a selective separation feature and the specific adsorption of salts and surfactants were investigated. The adsorption of various salts, e.g., AlCl₃, ZnCl₂, MnCl₂ and MgCl₂ were therefore analyzed, and the necessary concentration for the charge reversal of the material was determined. It was noticed that the investigated materials differ in their isoelectric point (IEP) and therefore in their adsorption behavior because only ZnCl₂ and MgCl₂ are suitable for a charge reversal of both metal oxides. The phase transfer of the pure material at different pH values with ZnCl₂ or MgCl₂ and sodium dodecyl sulfate (SDS) revealed that the adsorption behavior of the particle has an influence on the phase transfer. As a result, the phase transfer of SiO₂ is pH dependent, whereas the phase transfer of SnO₂ operates over a wider pH range. This allowed the separation of SiO₂ and SnO₂ to be controlled by the salt and surfactant concentration as well as pH. The separation of SiO₂ and SnO₂ was investigated for various parameters such as salt and surfactant concentration, particle concentration and composition of the mixture. Also, pH 8, where a selective phase transfer for SiO₂ occurs, and pH 6, where the greatest difference between the materials exists, were also investigated. By comparing the parameters, it was found that the combination of ZnCl₂/SDS and MgCl₂/SDS enables a selective separation of the materials. Furthermore, it was also found that the concentration of SDS has a significant effect on the separation, as the formation of a bilayer structure is important for the separation, and therefore, higher SDS concentrations are required at higher particle concentrations to increase the separation efficiency. Full article

Leachates from electronic waste, slag dusts generated during the processing of electronic waste, sweeping jewelry, and municipal solid-waste incineration residues contain a myriad of base metals, such as aluminum (Al: 10–2000 mg/L), copper (Cu: 10–1000 mg/L), iron (Fe: 10–500 mg/L), nickel (Ni: 0.1–500 mg/L), lead (Pb: 1–500 mg/L), tin (Sn: 1–100 mg/L), and zinc (Zn: 5–500 mg/L), which are present at much higher quantities than Au (0.01–10 mg/L), which raises several drawbacks to the efficient recycling of Au with high purity using hydrometallurgical strategies. The aim of this work was to study the efficiency and selectivity of two strong basic anion exchange (DOW^TM XZ-91419.00 and Purogold^TM A194) resins to recover Au from a chloride multi-metal solution containing these metals. For both resins, the adsorption kinetic and equilibrium parameters for Au(III), determined at 1.12 mol/L HCl, Eh = 1.1 V, and 25 °C, proceeded according to a pseudo-second order and a Langmuir isotherm (qmax was 0.94 and 1.70 mmol/g for DOW^TM XZ-91419.00 and Purogold^TM A194 resins, respectively), respectively. Continuous adsorption experiments of Au (48 µmol/L; 2.0%) from a chloride multi-metal solution evidenced high Au retention capacity and selectivity to Au over Al, Cu, Fe, Ni, and Zn but low selectivity to Au over Ag and Sn for both resins. Concentrated (>3.3 mmol/L) and pure (>94%) Au eluates were obtained for both resins. Full article

Houpoea officinalis (H. officinalis) flowers are rich in a spectrum of bioactive compounds and mineral nutrients. The availability and balance of mineral elements directly impact the morphogenesis of flower organs, which play pivotal roles in various physiological and biochemical processes that drive flower development. However, relatively little is known about the changes in mineral elements composition that occur during flower development in H. officinalis. The objective of this study is to analyze the variations of 22 mineral elements contents in pistil, stamens, and petals of H. officinalis flower at four development stages. The amount of mineral elements (Na, Mg, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Sn, Al, Ti, Ga, Cd, Ba, Tl, Pb, and Bi) in these samples was determined using atomic absorption spectroscopy and inductively coupled plasma mass spectrometry. Results showed that H. officinalis flowers are rich in macroelements such as potassium (K, 25.80–48.06 mg/g) and calcium (Ca, 17.27–31.00 mg/g), as well as microelements like zinc (Zn, 445.17–1553.16 μg/g) and iron (Fe, 324.27–622.31 μg/g). Notably, the pistil part is found to harbor a more significant concentration of mineral elements during the early developmental stages of flowers. Correlation analysis and PCA have effectively exposed a pronounced association between the accumulation patterns of mineral elements in H. officinalis flowers and their corresponding developmental stages and organs. These findings will provide more detailed information about the accumulation and distribution of mineral elements in H. officinalis flowers at different development stages and organs, which help to encourage researchers to enhance the flower quality for human consumption. Full article

While there is enormous interest in studying oxide perovskites with stoichiometries based upon or derived from ABO₃, including oxygen-deficient compositions and organometallics, other closely related topologies have been overlooked. Hydroxyperovskites are such a group. Their structures are perovskite-like octahedral frameworks with vacant cavity A sites, and all oxygen atoms form hydroxyl groups. There are fifteen naturally occurring hydroxyperovskites and numerous synthetic analogues. There are two stoichiometries: BB′(OH)₆ and B(OH)₃. The former consist of alternating divalent and tetravalent cations (B = Mg, Ca, Mn²⁺, Fe²⁺, Co²⁺, Cu²⁺, Zn; B′ = Sn, Ge). B(OH)₃ structures have only trivalent cations (Al, Fe³⁺, Ga). The properties and behavior of solid solutions in hydroxyperovskites are largely unexplored. This article summarizes our current knowledge of the crystallography and crystal chemistry of hydroxyperovskites and suggests productive areas of research in relation to their potential as functional materials. It should be evident that much of the findings remains to be discovered. Full article

The interrelationships between the topological features, such as surface roughness deduced from atomic force microscopy (AFM), and wettability properties expressed by the contact angle of a water droplet on the surface of nanostructured wide bandgap oxide films prepared by spray pyrolysis are investigated for a wide range of compositions. A direct relationship between the surface roughness and the value of the contact angle was found for nanocomposite (In₂O₃)_1−x(MgO)_x, (In_1−xGa_x)₂O₃, and Zn_1−xMg_xO films, for which both the surface roughness and the contact angle increase with the increasing x-value. On the other hand, in ITO films doped with Ga, it was found that the surface roughness increases by increasing the Ga doping, while the contact angle decreases. Both the surface roughness and the contact angle proved to increase in Ga₂O₃ films when they were alloyed with Al₂O₃, similar to other nanocomposite films. An inverse relationship was revealed for a nanocomposite formed from Ga₂O₃ and SnO₂. The contact angle for a (Ga₂O₃)_0.75(SnO₂)_0.25 film was larger as compared to that of the Ga₂O₃ film, while the surface roughness was lower, similar to ITO films. The highest value of the contact angle equal to 128° was found for a (In₂O₃)_1−x(MgO)_x film with an x-value of 0.8, and the largest RMS roughness of 20 nm was showed by a Ga_1.75Al_0.25O₃ film. The optical properties of the prepared films were also analyzed from optical absorption spectroscopy, demonstrating their bandgap variation in the range of (4 to 4.85) eV, corresponding to the middle ultraviolet spectral range. Full article

Multivariate and statistical tool advancements help to assess potential pollution threats, their geochemical distribution, and the competition between natural and anthropogenic influences, particularly on sediment contamination with potentially toxic metals (PTMs). For this, riverine sediments from 25 locations along urban banksides of the River Ravi, Pakistan, were collected and analyzed to explore the distribution, pollution, ecological, and toxicity risk indices of PTMs like Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Sn, Sr, V, and Zn using Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES) technique. Additionally, techniques such as X-ray Diffraction (XRD) and Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy (SEM-EDS) were employed to investigate the mineralogical and morphological aspects. The results indicated that mean concentrations (mg kg⁻¹) of Cd (2.37), Cr (128), Hg (16.6), Pb (26.6), and Sb (2.44) were significantly higher than reference values given for upper continental crust (UCC) and world soil average (WSA), posing potential threats. Furthermore, the geochemical pollution indices showed that sediments were moderately polluted with Cd (I_geo = 2.37, EF = 12.1, and CF = 7.89) and extremely polluted with Hg (I_geo = 4.54, EF = 63.2, and CF = 41.41). Ecological and toxicity risks were calculated to be extremely high, using respective models, predominantly due to Hg (Er_i = 1656 and ITRI = 91.6). SEM-EDS illustrated the small extent of anthropogenic particles having predominant concentrations of Zn, Fe, Pb, and Sr. Multivariate statistical analyses revealed significant associations between the concentrations of PTMs and the sampling locations, highlighting the anthropogenic contributions linked to local land-use characteristics. The present study concludes that River Ravi sediments exhibit moderate levels of Cd and extreme pollution by Hg, both of which contribute highly to extreme ecological and toxicity risks, influenced by both natural and anthropogenic contributions. Full article