Search Results (1,608)

The brittleness of 18-karat purple gold originates from the AuAl₂ intermetallic compound. This study investigates the microstructural modification of the AuAl₂ intermetallic compound by adding silicon (Si) and cobalt (Co) and by rapid solidification in copper molds. The samples with alloy additions from a traditional investment casting were compared with copper mold casting for grain boundary characteristics using SEM, EBSD, and TEM. SEM micrographs showed a reduction in grain size of copper mold casting from approximately within 150–200 μm to within 12–20 μm. EBSD showed a narrow grain size distribution in the Si–Co-modified alloy than in the Si-modified alloy, using the copper mold casting technique. TEM observations show that grain boundaries were closely packed, with ~80 nm-sized voids. XRD confirmed that all alloys retained the AuAl₂ intermetallic phase, with peak broadening in the modified and fast-cooling samples indicating crystallographic refinement. These results confirm that Si-Co additions with a fast cooling rate effectively refine the microstructure of the AuAl₂ intermetallic compound, making the alloy less brittle while preserving the purple gold color. Full article

Medicarpin, a natural pterocarpan phytoalexin, contributes to tree defense against microbial decay, particularly from the aggressive white-rot fungus Trametes versicolor, an ASTM standard for wood durability testing. To improve upon the inhibitory effect of medicarpin against this fungus (150 mg/L), eleven derivatives were synthesized and evaluated. The acetylated analog demonstrated superior activity, achieving complete growth inhibition at 100 mg/L. To establish a structure–activity relationship, molecular docking was performed on the copper cluster on fungal laccase, the primary oxidative enzyme of T. versicolor. The acetylated derivative bound the T1 copper site with a more favorable free energy (−8.5 kcal/mol) than the parent compound, exhibiting enhanced stabilizing interactions and a binding pose anchored closer to the trinuclear copper cluster (TNC). These results were corroborated by 80 ns molecular dynamics simulations, confirming complex stability and the persistence of key interactions. This study demonstrates that targeted chemical modification of natural phytoalexins can significantly improve their antifungal potency. The superior performance of the acetylated medicarpin derivative, linked to optimized binding at the laccase active site, establishes a clear structure–activity relationship and highlights the potential of such engineered compounds as leads for next-generation, bio-inspired wood preservatives. Full article

Adsorption is a promising solution to the presence of contaminants in water resources that involves the use of adsorbent materials, such as granular activated carbon (GAC) and nanoparticles like silver (Ag) and copper (Cu). However, the practical challenge of using pure GAC lies in its susceptibility to biofouling. This study aimed to develop a multifunctional GAC/AgCu nanocomposite to address the dual challenge of pharmaceutical contamination and bacterial activity of Escherichia coli. Characterization by SEM, XRF, XRD and FTIR confirmed the successful impregnation of nanoparticles. Kinetic studies showed that the pseudo-first-order model was more suitable for both caffeine and paracetamol contaminants. The Langmuir model provided the best fit for isotherms, achieving maximum adsorption capacities of 138.35 $\mathrm{m}\mathrm{g} {\mathrm{g}}^{-1}$ for caffeine and 92.21 $\mathrm{m}\mathrm{g} {\mathrm{g}}^{-1}$ for paracetamol. In antibacterial tests, GAC/AgCu achieved a bacterial reduction of over 97%, whereas pure GAC showed no inhibitory effect, confirming that the antimicrobial properties are derived from the Ag and Cu nanoparticles. These results highlight GAC/AgCu as a promising multifunctional material for the simultaneous removal of emerging pharmaceutical pollutants and biological contaminants, offering a solution to mitigate biofouling and enhance water treatment efficiency. Full article

Copper–organic compounds are being investigated as antitumor candidates. Besides their efficacy as cytotoxic agents alone, the oxidative potential of electrochemical Cu²⁺-to-Cu¹⁺ transition emerges as an attractive approach for elimination of tumor cells otherwise resistant to chemotherapy. To minimize side effects of the potent oxidative burst upon Cu(II) reduction, the metal cations should be delivered to the tumor site. Taking advantage of the ability of bisphosphonates to accumulate in the bone, we synthesized a Cu(II) complex of zoledronic acid (ZA), an FDA-approved drug for prevention of bone destruction. The CuZA complex obtained upon precipitation of ZA and different copper salts (sulfate, chloride or perchlorate) were structurally identical, consisting of two organic moieties coordinated by three metal cations. Combined treatment with water-soluble formulations of CuZA and cysteine triggered rapid death in human cell lines. This effect was achievable with non-toxic concentrations of CuZA and cysteine alone. Importantly, the K562 chronic myelogenous leukemia cells that demonstrated an attenuated response to the 3d generation Bcr-Abl tyrosine kinase inhibitor in the medium conditioned by bone marrow-derived fibroblasts, were readily killed by CuZA–cysteine combination. Thus, oxidative burst upon metal reduction in CuZA complexes emerges as a promising method of eradication of tumor cells in the bone microenvironment. Full article

Carnosine (or β-alanyl-L-histidine) is an endogenous compound playing very important roles in human organisms as antiglycation and antioxidant agents, and, in addition, helping to mitigate illnesses such as cancer and neurodegenerative diseases. Aiming to explore the chelating ability of carnosine, based on its coordinating possibilities, we started to investigate the metal complexes of essential copper(II), zinc(II), and iron(II) ions coordinated to this dipeptide. Different compounds were isolated in the solid state by adding stoichiometric amounts of metal salts to carnosine at controlled pH or under a controlled atmosphere, with the formation of mono-, bi- and polynuclear species. These complexes were subsequently characterized mainly by spectroscopic techniques (UV–Vis, IR, EPR), in addition to elemental analysis. A binuclear species was isolated with copper(II) and had its structure determined by X-ray diffraction, improving previously reported data in the literature. Two insoluble correlated trinuclear species were isolated with zinc(II) ions, using perchlorate or chloride as counter-ions. In the case of iron, a mononuclear species was verified with Fe(II) ions, obtained under an inert atmosphere. Further, the antioxidant properties of free carnosine and the copper–carnosine complex were verified by their scavenging activity toward the ABTS^•+ radical, using Trolox as a reference, showing significant activity. The carnosine–metal complexes were also tested as potential antineoplastic agents, in comparison to the free ligand, after 24 h of incubation at 37 °C, using malignant HeLa, SKMEL 28 and SKMEL 147, and non-tumor fibroblast cells. Results indicated neglected or poor anti-proliferative properties of these metal complexes, when compared to other similar compounds described in the literature. Full article

As a novel form of cell death, the discovery of cuproptosis presents significant opportunities and challenges for the field of cancer therapy. Notably, polyphenolic compounds have attracted considerable research attention for their ability to induce cuproptosis. These natural compounds not only exhibit marked anti-inflammatory and antioxidant properties, but their polyhydroxy structures also enable effective chelation and transport of copper ions. This provides novel insights into cuproptosis-mediated cancer therapy. Therefore, in this review, we systematically outline copper metabolism, the mechanisms of cuproptosis, and its association with cancer, while providing an in-depth discussion of the effects and mechanisms by which polyphenolic compounds act as copper ionophores to inhibit tumor growth and progression through the induction of cuproptosis. This review indicates the promising potential of polyphenolic compounds in the field of cancer therapy and provides a theoretical basis for therapeutic strategies based on cuproptosis. Full article

Environmental pollution caused by persistent chemical compounds, particularly heavy metals, poses a significant global challenge. Current strategies focus on eco-friendly and sustainable approaches, such as the application of microorganisms, to mitigate this issue. In this study, four strains of Bacillus and Pseudomonas were phylogenetically identified and assessed for their resistance to three heavy metals: copper (Cu), chromium (Cr), and cadmium (Cd) up to 500 µg/mL. Various tolerance mechanisms related to heavy metal resistance were elucidated, including salinity tolerance, antibiotic resistance, production of exopolysaccharides (EPS), and biosurfactant synthesis. The antifungal activities of these strains were evaluated against the fungal isolates Fusarium oxysporum fs. phaseoli (Fop) and Stemphylium botryosum (St-bt) using dual culture assays. Phylogenetic analysis revealed that three strains belong to the genus Bacillus, while one strain is classified under Pseudomonas. Additionally, these strains exhibited diverse mechanisms for heavy metal tolerance, including salinity tolerance (up to 600 mM), multi-antibiotic resistance (to imipenem, ampicillin, and sodium fusidate), and the production of viscous, slimy colonies indicative of EPS synthesis. Biosurfactant production led to a significant reduction in surface tension, ranging from 10.51 ± 3.87% to 82.89 ± 5.01%. The antifungal assays demonstrated that the strains effectively inhibited the mycelial growth of the fungal isolates, with inhibition percentages varying from 0% to 83.34 ± 2.22%. The strains characterized in this study exhibit considerable potential for application in the bioremediation of metal-contaminated soils and as biocontrol agents. Full article

Natural pasture, the primary feed source in sheep production, often provides insufficient levels of essential minerals and vitamins required for proper metabolic regulation during pregnancy and early development. This study aimed to analyze patent developments of mineral and vitamin complexes (MVCs) for pregnant ewes and lambs and to evaluate the biochemical and molecular relevance of their components based on scientific evidence. A search of the World Intellectual Property Organization (WIPO) database using the keywords “vitamins for sheep” and “minerals for sheep” identified 120 patents related to sheep feed additives, including 23 specifically formulated for pregnant ewes and lambs. Comparative analysis revealed that calcium, selenium, iron, copper, cobalt, sodium, manganese, zinc, and vitamins A, D, and E were the most frequently included components. These micronutrients play critical roles in enzymatic activity, regulation of gene expression, antioxidant defense systems, and mineral homeostasis. In particular, zinc and selenium function as structural and catalytic cofactors for antioxidant enzymes such as superoxide dismutase and glutathione peroxidase, while vitamins A and D regulate cellular differentiation and calcium–phosphorus metabolism through transcriptional control mechanisms. Additionally, functional additives, including amino acids and plant-derived bioactive compounds, contribute to improved mineral bioavailability and modulation of metabolic pathways. The analyzed formulations demonstrate a consistent focus on correcting mineral deficiencies, enhancing antioxidant protection, and supporting metabolic adaptation during pregnancy and early postnatal development. Overall, the findings indicate that modern MVCs are rationally formulated to improve mineral utilization, physiological stability, and reproductive outcomes, highlighting their critical role in optimizing maternal health and offspring viability in sheep production systems. Full article

This study investigates the potential of Quercus robur leaves as a bio-coagulant for the removal of heavy metal ions, including zinc (II), iron (III), copper (II), and chromium (VI), from water. The Quercus robur leaves were used in two forms: Quercus robur powder (QRP) and Quercus robur extract (QRE). The extract was prepared using distilled water to extract the active compounds responsible for coagulation, such as proteins, polysaccharides, and total phenolics. The QRP was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and zeta potential analysis to identify the active functional groups, surface morphology, crystallinity, and surface charge, all of which are key factors influencing its performance in the coagulation–flocculation process. In this work, the Response Surface Methodology (RSM)-based Central Composite Design (CCD), with two factors (bio-coagulant dosage and initial metal concentration), was used examine the effects of each factor and their interaction, while the responses were zinc (II) removal, iron (III) removal, copper (II) removal, and chromium (VI). The results revealed high removal efficiency for these metal ions, reaching up to 100% for all metal ions treated with QRP and QRE. The quality of the model predictions was evaluated using analysis of variance (ANOVA). For all metal ions, the R² (≥97%), R² adjusted (≥95%), and p-values (<0.05), indicating an excellent model accuracy. These results show that bio-coagulants (QRP and QRE) based a Quercus robur leaves are a promising, effective, and reliable option for removing heavy metal ions from water, and that the models developed can be used to optimize the coagulation-flocculation process. Full article

Copper is an essential element for living organisms, being a cofactor for numerous enzymes or proteins involved in oxidation-reduction reactions, intervening in numerous metabolic processes. In recent decades, complex copper combinations have consolidated their position in medicinal chemistry, which is manifested by the increasing number of compounds that have demonstrated their efficacy following in vitro or in vivo testing. While attempting to mimic the DNA-metal complex interactions typical of cisplatin, most studies of the mechanisms of action of copper complexes continue to consider DNA as the main biological target. Starting from this, studies are focused on understanding in detail how copper complexes manage to destroy tumor cells, and this has led to the discovery of a wide range of such mechanisms of antitumor action. In this review we present the main mechanisms of action of copper complexes discovered in recent decades, from the most well-known (production of ROS following the reaction with DNA) to the newest (cuproptosis). Research into understanding the mechanisms of action of copper complexes continues to be a topic of great interest in developing new potential antitumor agents. Full article

Antimicrobial resistance (AMR) threatens global health, particularly through the rise of multidrug-resistant tuberculosis (MDR-TB) and other critical bacterial infections such as methicillin-resistant Staphylococcus aureus (MRSA). Rifamycins remain frontline antibiotics but are increasingly undermined by resistance. Here, we introduce a click-enabled platform for the synthesis of C8-functionalized rifamycins, which can be converted in a single additional step into efficacious 3′-hydroxy-5′-aminobenzoxazinorifamycins (bxRifs) and enzymatically into 25-deacetylated rifamycins (deAcRifs), providing access to novel antibacterial scaffolds that expand beyond the scope of traditional C8 modifications. Accordingly, we establish a modular strategy for late-stage analog development of the complex natural product rifamycin S, wherein azido and alkyne functionalities are installed via tailored core chemistry and converted into 1,2,3-triazoles through copper(I)-catalyzed click chemistry. Another key feature of this work is the development of systematic HPLC purification methods, enabling the isolation of analytically pure compounds despite structural complexity. The resulting analogs exhibit distinct antibacterial profiles, notably against Gram-positive bacteria including MRSA and Streptococcus mutans, informing structure–activity relationships and offering a foundation for further optimization. This approach supports the rapid diversification of rifamycin scaffolds to combat the escalating threat of AMR, while also establishing a foundation for future discovery through bioorthogonal applications. Full article

Welding copper (Cu) and aluminum (Al) is highly demanded for lightweight and cost-effective manufacturing. However, it faces significant challenges. First, substantial differences in physical properties may lead to high residual stresses and distortion. Second, brittle intermetallic compounds (IMCs) readily form at the interface, severely compromising the joint’s mechanical properties and electrical conductivity. Third, the native oxide film on Al impedes effective wetting and bonding. Therefore, effective control over the interfacial microstructure of the welded joint is essential. This review provides a critical analysis and comparison of several typical welding techniques, including laser welding (LW), friction stir welding (FSW), ultrasonic welding (UW), brazing and soldering, and welding–brazing. These analyses focus on their process characteristics, joint microstructures, and corresponding formation mechanisms. Furthermore, this review synthesizes key strategies for enhancing joint quality, including process parameter optimization, introduction of functional interlayers, and external assistance, aimed at optimizing joint microstructure and minimizing defects. Based on the analysis, this work provides comparative insights into process selection and microstructure control, and highlights future directions: advancing novel methods such as magnetic pulse welding and transient liquid phase bonding; developing intelligent real-time process control to suppress brittle IMCs and associated defects; promoting sustainable practices and establishing standardized performance evaluation; and systematically investigating long-term reliability to support the industrial application of robust Cu/Al joints. Full article

This study investigates the influence of highly thermally conductive coatings on the combustion thresholds of a TC4 titanium alloy, aiming to address the flame-retardant protection requirements for titanium alloys. The findings reveal that, in terms of combustion thermodynamics, as the thickness of the copper coating increases from 100 μm to 300 μm, the critical ignition power rises by 125–170 W compared to the substrate (235 W). Additionally, the critical oxygen pressure increases by 0.21–0.51 MPa relative to the substrate (0.03 MPa), and the ignition temperature is elevated by 119–184 K above that of the substrate (848.80 K). This phenomenon is primarily due to the high thermal diffusivity of copper. Increased coating thickness further enhances heat dissipation, significantly suppressing the local heat accumulation rate and thereby improving the coating’s combustion resistance. In terms of combustion kinetics, under fixed experimental conditions, the copper coating extends the ignition delay time by 0.670 s and reduces the combustion propagation rate by approximately 21% compared to the substrate (26.772 mm/s). The post-combustion microstructural analysis indicates that during the reaction process, the copper coating forms a TiCu₂Al-type intermetallic compound (Ti_0.5Al_0.5)Cu. This structure exerts an “anchoring” effect on the substrate material, decreases the Ti/O reaction efficiency, and consequently achieves effective flame retardancy. These findings inform the subsequent design and optimization of copper-based abradable coatings with enhanced combustion resistance. Full article

To identify fungicide lead compounds with novel scaffolds and high efficacy, 33 novel bacillamide–acylhydrazone derivatives were successfully designed and synthesized by using a molecular hybridization strategy. The bioassay results showed that most of the target compounds exhibited promising inhibitory activity against B. cinerea. Among them, compound BAD-15 displayed the most potent antifungal activity with an EC₅₀ value of 6.725 μg/mL. Furthermore, preliminary SAR analysis revealed that the R group in hydrazine fragments exerts a significant influence on antifungal potency. Studying the molecular mechanism by morphological observation and transcriptome analyses revealed that BAD-15 may inhibit the activity of copper ion transmembrane transporters, leading to disrupted copper ion homeostasis and subsequent suppression of fungal growth. The present work indicates that bacillamide–acylhydrazone has potential as a novel scaffold for the development of fungicides, and compound BAD-15 may serve as a potential lead compound for the further development of novel fungicides. Full article

One of the many applications of metal–organic frameworks (MOFs) is their use as adsorbents for removing emerging contaminants, such as ciprofloxacin (CIP), a fluoroquinolone-class antibiotic, from aqueous environments. We selected the copper-based MOF HKUST-1 and coupled it with TiO₂, then immobilized the composite on glass beads (TiO₂/HKUST-1@GB) to produce a reusable photocatalyst. The immobilization of the composite on glass beads improved the structural strength as well as the reusability of the photocatalyst. Together, these properties pave the way for scale-up for commercial applications in continuous-flow water treatment systems. Herein, we used XRD, FTIR, and SEM to characterize the immobilized catalyst and assess its structural, morphological, and optical properties. Photocatalytic experiments showed 98% degradation in 45 min under UV irradiation at pH 6 and a CIP concentration of 200 μgL⁻¹. The TiO₂/HKUST-1@GB composite showed higher degradation compared to pristine TiO₂ and HKUST-1 due to enhanced charge–carrier separation and synergistic interfacial effects. The reusability of the composite over five cycles was observed, with high stability and negligible Cu and Ti leaching, indicating promising environmental performance. Thus, TiO₂/HKUST-1@GB provides an efficient and sustainable approach for removing ciprofloxacin from aqueous solutions. The degradation performance, reusability, and ability to work simultaneously in adsorption and photocatalytic processes make TiO₂/HKUST-1@GB a promising candidate for the advanced treatment of aqueous-phase antimicrobial compounds such as ciprofloxacin. Full article