Search Results (1,792)

It is challenging to handle heavy-metal-rich plants that grow in contaminated soil. The role of heavy metals in biomass on the physicochemical structure and electrochemical properties of their derived carbon has not been considered in previous research. In this study, Cu-ion hybrid nanoporous carbon (CHNC) is prepared from Cu content-contaminated biomass through subcritical hydrocharization (HTC) coupling pyrolytic activation processes. The CHNCs are used as advanced electrode material for energy storage applications, exhibiting an impressively ultrahigh capacitance of 562 F g⁻¹ at a current density of 1 A g⁻¹ (CHNC-700-4-25), excellent energy density of 26.15 W h kg⁻¹, and only 7.59% capacitance loss after enduring 10,000 cycles at a current density of 10 A g⁻¹, making CHNCs rank in the forefront of previously known carbon-based supercapacitor materials. These comprehensive characterizations demonstrate that copper ions introduce new electrochemically active sites and enhance the conductivity and charge transport performance of the electrode material, elevating the specific capacitance of CHNC from 463 to 562 F g⁻¹. These findings offer valuable insights into the effective energy storage application of heavy-metal-contaminated biomass wastes. Full article

Li-ion batteries are at risk of explosions caused by fires, primarily because of the high energy density of Li ions, which raises the temperature. Battery cases are typically made of plastic, aluminum, or SAF30400. Although plastic and aluminum aid weight reduction, their strength and melting points are low. SAF30400 offers excellent strength and corrosion resistance but suffers from work hardening and low high-temperature strength at 700 °C. Additionally, Ni used for plating has a low current density of 25% international copper alloy standard (ICAS). SAF2507 is suitable for use as a Li-ion battery case material because of its excellent strength and corrosion resistance. However, the heterogeneous microstructure of SAF2507 after casting and processing decreases the corrosion resistance, so it requires solution heat treatment. To address these issues, in this study, SAF2507 (780 MPa, 30%) is solution heat-treated at 1100 °C after casting and coated with Ag (ICAS 108.4%) using physical vapor deposition (PVD). Ag is applied at five different thicknesses: 0.5, 1.0, 1.5, 2.0, and 2.5 μm. The surface conditions and electrochemical properties are then examined for each coating thickness. The results indicate that the PVD-coated surface forms a uniform Ag layer, with electrical conductivity increasing from 1.9% ICAS to 72.3% ICAS depending on the Ag coating thickness. This enhancement in conductivity can improve Li-ion battery safety on charge and use. This result is expected to aid the development of advanced Li-ion battery systems in the future. Full article

Although commonly appreciated for their anti-oxidative and neuroprotective properties, flavonoids can also exhibit pro-oxidative activity, potentially reducing cell survival, particularly in the presence of metal ions. Disrupted copper homeostasis is a known contributor to neuronal dysfunction through oxidative stress induction. This study investigated the effects of myricitrin (1–20 μg/mL) on copper-induced toxicity (0.5 mM CuSO₄) in the neuroblastoma SH-SY5Y cell line. At non-toxic concentrations, myricitrin exacerbated copper’s toxic effects. The myricitrin-induced decrease in survival was accompanied with increased reactive oxygen species (ROS) production, reduced superoxide dismutase activity, and a lower GSH/GSSG ratio. In combination with copper, myricitrin also activated caspase-3/7, promoted nuclear chromatin changes, and compromised membrane integrity. At the protein level, myricitrin upregulated p53 and PUMA expression. The toxic effects of myricitrin were alleviated by the p38 inhibitor SB203580, the intracellular calcium chelator BAPTA-AM, and the NMDA receptor blocker MK-801, highlighting the significant role of the ROS/p53/p38 axis in cell death and the critical involvement of calcium ions in apoptosis induction. The atomic force microscopy was used to assess the surface morphology and nanomechanical properties of SH-SY5Y cells, revealing changes following myricitrin treatment. This research highlights the toxic potential of myricitrin and emphasizes the need for caution when considering flavonoid supplementation in conditions with elevated copper levels. Full article

Ester collectors have rapidly developed into the main flotation collectors for copper sulfide minerals since they were developed. In this study, the collecting performance of four collectors, O-isopropyl-N-ethyl thionocarbamate ester (IPETC), 3-pentyl xanthate acrylate ester (PXA), O-isobutyl-N-allyl-thionocarbamate (IBALTC), and O-isobutyl-N-isobutoxycarbonyl-thionocarbamate (IBIBCTC), was investigated through microflotation tests, microcalorimetric measurements, and quantum chemical calculations. The results of the microflotation tests show that IBALTC and IPETC have stronger collecting abilities than IBIBCTC and PXA; the order of collecting ability is IBALTC > IPETC > IBIBCTC > PXA. The microcalorimetry test also shows that the adsorption heat of the former two is higher. Quantum chemical calculations show the energy difference between the HOMOs of the collector and the LUMOs of minerals. The electrostatic potential extremum around S atom and the first ionization potential of IPETC and IBALTC are similar and were smaller than IBIBCTC and PXA, which shows that the collecting ability of the former two is similar and stronger than the latter two. Among the collectors, the S atom polarizability, electrophilic, and nucleophilic attack index of IBALTC are the largest, indicating that its electronic deformation capability and nucleophilic properties are the strongest, which results in the strongest coordination interaction with the copper ions in copper sulfide minerals and thus the highest collecting ability. The S atom polarizability, electrophilic, and nucleophilic attack index of PXA are the smallest, indicating that its electronic deformation capability and nucleophilicity are the weakest, and its collecting ability is the weakest. The coordination between collector and mineral surface was analyzed theoretically. The research results are of great help to the design and development of ester collectors. Full article

Cyclic voltammetry (CV) can be applied as a reliable method for the determination of chloride ions in a range from several to a couple hundred (about 200) ppm. Since the standard potential of chloride ion/gaseous chlorine is 1.36 V vs. normal hydrogen electrode (NHE), the efficient oxidation of Cl⁻ ion occurs at very positive electrode potentials, usually higher than +1.7 V vs. NHE. It is possible to observe this phenomenon only at noble-metal or inert carbon electrodes. Many other solutes, usually organic compounds, are often oxidized at this potential. This is the reason why the determination of Cl⁻ content directly from an increase in the oxidation current is not reliable and could lead to overestimated values. However, gaseous chlorine, generated at a positive potential dissolve in the analyzed solution, could be reduced in the reverse scan of a cyclic voltammetric curve. Optimization of the experimental procedure using statistical tools enables the development of an improved method for the direct quantification of chloride ions in acid copper electroplating baths. Under the proposed experimental conditions, the calibration curve (Cl₂ voltammetric reduction current vs. chloride ions concentration) is represented by the linear model for the concentration of chlorides ranging from 10 to 200 mg/dm³. The developed method for analyzing chloride ions in an acid sulfate electroplating copper bath has many unique properties. It is fast; the time of a single analysis is less than 20 min. In automatic mode, it can be repeated up to 50 times a day. The method does not require processing of the sample of the analyzed bath before measurement. As a result, no additional chemical reagents are used, and the test sample can be returned to the plating bath. Full article

In this work, within the framework of a self-consistent model of arc discharge, a simulation of plasma parameters in a mixture of argon and methane was carried out, taking into account the evaporation of the electrode material in the case of a refractory and non-refractory cathode. It is shown that in the case of a refractory tungsten cathode, almost the same methane conversion rate is observed, leading to similar values in the density of the main methane conversion products (C, C₂, H) at different values of the discharge current density. However, with an increase in the current density, the evaporation rate of copper atoms from the anode increases, and a jump in the I–V characteristic is observed, caused by a change in the plasma-forming ion. This is due to the lower ionization energy of copper atoms compared to argon atoms. In this mode, an increase in metal–carbon nanoparticles is expected. It is shown that, in the case of a cathode made of non-refractory copper, the discharge characteristics and the component composition of the plasma depend on the field enhancement factor near the cathode surface. It is demonstrated that increasing the field enhancement factor leads to more efficient thermal field emission, lowering the cathode’s surface temperature and the gas temperature in the discharge gap. This leads to the fact that, in the arc discharge mode with a cathode made of non-refractory copper, the dominant types of particles from which the synthesis of a nanostructure can begin are, in descending order, copper atoms (Cu), carbon clusters (C₂), and carbon atoms (C). Full article

Nanoparticles are essential for energy storage, catalysis, and medical applications, emphasizing their accurate chemical characterization. However, atom probe tomography (APT) of nanoparticles sandwiched at the interface between an encapsulating film and a substrate poses difficulties. Poor adhesion at the film-substrate interface can cause specimen fracture during APT, while impurities may introduce additional peaks in the mass spectra. We demonstrate preparing APT specimens with strong adhesion between nanoparticles and film/substrate matrices for successful analysis. Copper nanoparticles were encapsulated at the interface between nickel film and cobalt substrate using electrodeposition. Cobalt and nickel were chosen to match their evaporation fields with copper, minimizing peak overlaps and aiding nanoparticle localization. Copper nanoparticles were deposited via magnetron sputter inert gas condensation with varying deposition times to yield suitable surface coverages, followed by encapsulation with the nickel film. In-plane and cross-plane APT specimens were prepared by femtosecond laser ablation and focused ion beam milling. Longer deposition times resulted in agglomerated nanoparticles as well as pores and voids, causing poor adhesion and specimen failure. In contrast, shorter deposition times provided sufficient surface coverage, ensuring strong adhesion and reducing void formation. This study emphasizes controlled surface coverage for reliable APT analysis, offering insights into nanoparticle chemistry. Full article

Microplastics (MPs) are emerging pollutants of global concern, while heavy metals such as copper ions (Cu²⁺) are longstanding environmental contaminants with well-documented toxicity. This study investigates the independent and combined effects of polystyrene microplastics (PS-MPs) and Cu on the physiological and biochemical responses of rice seedlings (Oryza sativa L.), a key staple crop. Hydroponic experiments were conducted under four treatment conditions: control (CK), PS-MPs (50 mg·L⁻¹), Cu (20 mg·L⁻¹ Cu²⁺), and a combined PS-MPs + Cu treatment. The results showed that PS-MPs had a slight stimulatory effect on root elongation, while Cu exposure mildly inhibited root growth. However, the combined treatment (PS-MPs + Cu) demonstrated no significant synergistic or additive toxicity on growth parameters such as root, stem, and leaf lengths or biomass (fresh and dry weights). Both PS-MPs and Cu significantly reduced peroxidase (POD) activity in root, stem, and leaf, indicating oxidative stress and disrupted antioxidant defenses. Notably, in the combined treatment, PS-MPs mitigated Cu toxicity by adsorbing Cu²⁺ ions, reducing their bioavailability, and limiting Cu accumulation in rice tissues. These findings reveal a complex interaction between MPs and heavy metals in agricultural systems. While PS-MPs can alleviate Cu toxicity by reducing its bioavailability, they also compromise antioxidant activity, potentially affecting plant resilience to stress. This study provides a foundation for understanding the combined effects of MPs and heavy metals, emphasizing the need for further research into their long-term environmental and agronomic impacts. Full article

The multielement pyrochlore of the composition Bi_1.57Mn_1/3Cr_1/3Cu_1/3Nb₂O_9−Δ (sp. gr. Fd-3m:2, 10.4724 Å) containing transition element atoms—chromium, manganese and copper in equimolar amounts—was synthesized for the first time using the solid-phase reaction method. The microstructure of the ceramics is grainless and has low porosity. The sample is characterized by reflection in the red (705 nm) color region. The band gap for the direct allowed transition in the sample is 1.68 eV. The parameters of the Bi5d, Nb3d, Сr2p, Mn2p, and Cu2p X-ray photoelectron spectroscopy (XPS) spectra for the mixed pyrochlore are compared with the parameters of transition element oxides. For the complex pyrochlore, a characteristic shift in the Bi4f and Nb3d spectra to the region of lower energies by 0.15 and 0.60 eV, respectively, is observed. According to the XPS Cu2p and Mn2p spectra of pyrochlore, copper, and manganese cations are in a mixed charge state; they mainly have an effective charge of +2/+3, and the Cr2p spectrum is a superposition of the spectra of chromium ions in the charge state of +3, +4, +6. At 24 °С, the permittivity of the sample in the frequency range (10⁴–10⁶ Hz) weakly depends on the frequency and is equal to ~100, the dielectric loss tangent is 0.017. The activation energy of conductivity is equal to 0.41 eV. The specific electrical conductivity of Bi_1.57Cr_1/3Cu_1/3Mn_1/3Nb₂O_9−Δ increases with the temperature increasing from 1.8 × 10⁻⁵ Ohm⁻¹·m⁻¹ (24 °С) to 0.1 Ohm⁻¹·m⁻¹ (330 °С). Nyquist curves for the sample are modeled by equivalent electrical circuits. Full article

Brochantite was precipitated using stoichiometric amounts of CuSO₄ and NaOH and characterized by scanning electron microscopy, specific surface area, thermogravimetric analysis, and zeta potential. Brochantite can be converted into paratacamite, basic copper bromide, and copper phthalate by shaking the powder with solutions containing excess corresponding anions. By contrast, attempts to convert brochantite into basic iodide, acetate, nitrate, or rhodanide in a similar way failed, that is, the powder after shaking with solutions containing excess corresponding anions still showed the powder X-ray diffraction pattern of brochantite. Successful ion exchange resulted in a decrease in the specific surface area by a factor of 10, but the specific surface area was unchanged when attempts to exchange the anion failed. Interestingly enough, paratacamite can also be converted into brochantite by shaking with solution containing excess sulfate. Brochantite and paratacamite obtained by precipitation and the salts obtained by ion exchange showed a negative zeta potential at pH > 9. Full article

The titanium dioxide (TiO₂) photocatalyst is an important semiconducting material that exhibits environmental purification functions when exposed to light. Elemental doping of TiO₂ is considered an important strategy to improve its photocatalytic activity. Herein, we have achieved the low-temperature, atmospheric-pressure synthesis of anatase TiO₂ particles with doping of 3d metals (Fe, Co, Ni and Cu) based on the liquid phase deposition technique. All products prepared by adding 3d metals were found to consist of TiO₂ crystals in the anatase phase with a fine protruding structure of about 40 nm on the surface, as was the case without the addition of metal ions. Iron and copper were observed to be incorporated at higher concentrations than cobalt and nickel, with an elemental addition of up to 4 at% and 1 at%, respectively, when 10 mM iron and copper nitrate were applied. Such doping efficiency could be explained by the difference in ionic radius and chemical stability. A narrowing of the optical band gap with doping elements was also observed, and it was found that optical sensitivity could be imparted down to the visible-light region of 2.4 eV (Fe: 4 at% addition). Furthermore, the 3d metal-doped TiO₂ demonstrated in this study was shown to exhibit photocatalytic methane degradation activity. The amount of methane degradation per unit area of the microparticles was twice as great when iron and copper were added, compared to the undoped counterpart. It has been demonstrated that the strategy of doping TiO₂ with 3d metal ions by low-temperature synthesis methods is effective in enhancing carrier dynamics and introducing surface active sites, thus increasing methane degradation activity. Full article

Based on the established neuroprotective properties of indole-based compounds and their significant potential as multi-targeted therapeutic agents, a series of synthetic indole–phenolic compounds was evaluated as multifunctional neuroprotectors. Each compound demonstrated metal-chelating properties, particularly in sequestering copper ions, with quantitative analysis revealing approximately 40% chelating activity across all the compounds. In cellular models, these hybrid compounds exhibited strong antioxidant and cytoprotective effects, countering reactive oxygen species (ROS) generated by the Aβ(25–35) peptide and its oxidative byproduct, hydrogen peroxide, as demonstrated by quantitative analysis showing on average a 25% increase in cell viability and a reduction in ROS levels to basal states. Further analysis using thioflavin T fluorescence assays, circular dichroism, and computational studies indicated that the synthesized derivatives effectively promoted the self-disaggregation of the Aβ(25–35) fragment. Taken together, these findings suggest a unique profile of neuroprotective actions for indole–phenolic derivatives, combining chelating, antioxidant, and anti-aggregation properties, which position them as promising compounds for the development of multifunctional agents in Alzheimer’s disease therapy. The methods used provide reliable in vitro data, although further in vivo validation and assessment of blood–brain barrier penetration are needed to confirm therapeutic efficacy and safety. Full article

The contamination of water by heavy metals poses an escalating risk to human health and the environment, underscoring the critical need for efficient removal methods to secure safe water resources. This study evaluated the performance of four cationic exchange materials (labeled “PS—DVB”, “PA—DVB”, “TFSA”, and “OGL”) in removing or harvesting metals such as copper, silver, lead, cobalt, and nickel from aqueous solutions, several of which are precious and/or classified as Critical Raw Materials (CRMs) due to their economic importance and supply risk. The objective was to screen and benchmark the four ion exchange materials for water treatment applications by investigating their metal sequestration capacities. Experiments were conducted using synthetic solutions with controlled metal concentrations, analyzed through ICP-OES, and supported by kinetic modeling. The adsorption capacities (qe) obtained experimentally were compared with those predicted by pseudo-first-order and pseudo-second-order models. This methodology enables high precision and reproducibility, validating its applicability for assessing ion exchange performance. The results indicated that PS—DVB and PA—DVB resins proved to be of “wide range”, exhibiting high efficacy for most of the metals tested, including CRM-designated ones, and suggesting their suitability for water purification. Additionally, the second-life Nafion-based “TFSA” material demonstrated commendable performance, highlighting its potential as a viable and technologically advanced alternative in water treatment. Lastly, the lignin-based material, “OGL”, representing the most innovative and sustainability apt option, offered relevant performance only in selected cases. The significant differences in performance among the resins underscore the impact of structural and compositional factors on adsorption efficiency. This study offers valuable insights for investigating and selecting new sustainable materials for treating contaminated water, opening new pathways for targeted and optimized solutions in environmental remediation. Full article

Cataracts are diseases characterized by the opacity of the ocular lens and the subsequent deterioration of vision. Metal ions are one of the factors that have been reported to induce crystallin aggregation. For HγS crystallin, several equivalent ratios of Cu(II) promote protein aggregation. However, reports on zinc are contradictory. To characterize the process of metal ion binding and subsequent HγS crystallin aggregation, we performed dynamic light scattering, turbidimetry, isothermal titration calorimetry, fluorescence, and nuclear magnetic resonance experiments. The data show that both metal ions have multiple binding sites and promote aggregation. Zinc interacts mainly with the N-terminal domain, inducing small conformational changes, while copper interacts with both domains and induces unfolding, exposing the tryptophan residues to the solvent. Our work provides insight into the mechanisms of metal-induced aggregation at one of the lowest doses that appreciably promote aggregation over time. Full article

Gold nanoclusters (AuNCs) have been widely investigated because of their unique photoluminescence properties. However, the applications of AuNCs are limited by their poor stability and relatively low fluorescence. In the present work, we developed nanocomposites (L-Cys-AuNCs@ZIF-8) with high fluorescence and stability, which were constructed by encapsulating the water-dispersible L-Cys-AuNCs into a ZIF-8 via Zn²⁺-triggered growth strategy without high temperature and pressure. The maximum emission wavelength of the L-Cys-AuNCs@ZIF-8 composite was at 868 nm, and the fluorescence intensity of L-Cys-AuNCs@ZIF-8 was nearly nine-fold compared with L-Cys-AuNCs without the ZIF-8 package. The mechanism investigation by fluorescence spectroscopy and X-ray photoelectron spectroscopy showed that L-Cys-AuNCs@ZIF-8 impeded ligand rotation, induced energy dissipation, and diminished the self-quenching effect, attributing to the spatial distribution of L-Cys-AuNCs. Based on the high fluorescence efficiency of L-Cys-AuNCs@ZIF-8, a “signal off” detective platform was proposed with copper ions as a model analyte, achieving a sensitive detection limit of Cu²⁺ at 16.7 nM. The quenching mechanism was confirmed, showing that the structure of the L-Cys-AuNCs@ZIF-8 nanocomposites was collapsed by the addition of Cu²⁺. Attributing to the strong adsorption ability between copper ions and pyridyl nitrogen, the as-prepared L-Cys-AuNCs@ZIF-8 was shown to accumulate Cu²⁺, and the Zn²⁺ in ZIF-8 was replaced by Cu²⁺. Full article