Search Results (461)

Two-component dental materials are commonly used by the dentist for various applications (cementation of indirect restorations, filling of a cavity without layering, etc.). These materials are cured by redox polymerization. The (hydro)peroxide/thiourea/copper salt redox initiator system is well established and can be found in a wide range of commercially available dental materials. The thiourea is a key component of the initiator system. This study explores the influence of the nature of the thiourea reducing agent on the reactivity and efficiency of redox initiator systems. In this work, six different thiourea structures were investigated, in combination with copper(II) acetylacetonate and cumene hydroperoxide (CHP), to understand their impact on polymerization kinetics and mechanical properties of methacrylate-based materials. Various experimental techniques, including mass spectrometry (MS) and spectroscopic analyses, were employed to elucidate the underlying mechanisms governing these redox systems. The results highlight that thiourea plays a dual role, acting both as a reducing agent and as a ligand in copper complexes, affecting radical generation and polymerization efficiency. Structural modifications of thiourea significantly influence the initiation process, demonstrating that reactivity is governed by a combination of factors rather than a single property. Self-cure dental flowable composites exhibiting excellent flexural strength (>100 MPa) and modulus (>6000 MPa) were obtained using hexanoyl thiourea, N-benzoylthiourea, or 1-(pyridin-2-yl)thiourea as a reducing agent. The adjustment of the Cu(acac)₂ enables to properly set the working time in the range of 100 to 200 s. These findings provide valuable insights into the design of the next generation of redox initiating systems for mild and safe polymerization conditions. Full article

The eight new copper(II), nickel(II), zinc(II), and iron(III) coordination compounds [Cu(L)Cl]₂ (1), [Cu(L)Br]₂ (2), [Cu(L)(NO₃)]₂ (3), [Cu(phen)(L)]NO₃ (4), [Ni(HL)₂](NO₃)₂·H₂O (5), [Ni(HL)₂]Cl₂ (6), [Zn(L)₂]·0.125H₂O (7), and [Fe(L)₂]Cl (8), where HL stands for 2-benzoylpyridine 4-allylthiosemicarbazone, were synthesized and characterized. ¹H, ¹³C NMR, and FTIR spectroscopies were used for characterization of the HL thiosemicarbazone. The elemental analysis, the FTIR spectroscopy, and the study of molar electrical conductivity were used for characterization of the coordination compounds 1–8. Also, the crystal structures of HL, its salts ([H₂L]Cl; [H₂L]NO₃), and complexes 1, 3, 5, 7, and 8 were determined using single-crystal X-ray diffraction analysis. Complexes 5, 7, 8 have mononuclear structures, while copper(II) complexes 1 and 3 have a dimeric structure with the sulfur atoms of the thiosemicarbazone ligand bridging two copper atoms together. Thiosemicarbazone HL and the complexes manifest antibacterial and antifungal activities. The studied substances are more active towards Gram-negative bacteria than towards Gram-positive bacteria and fungi. Complex 1 is the most active one towards Gram-positive bacteria and C. albicans, while the introduction of 1,10-phenanthroline into the inner sphere enhances the activity towards Gram-negative bacteria. Thiosemicarbazone and complexes 6 and 7 manifest antiradical activity that exceeds the activity of Trolox. HL and complex 1 manifest antiproliferative activity towards HL-60 cancer cells which exceeds the activity of their analogs with 2-formyl-/2-acetylpyridine 4-allylthiosemicarbazone. Full article

Copper-based substances have historically been shown to exhibit antimicrobial properties, but the mechanisms by which they interact with bacterial biofilms in pipeline systems remain unclear. This study investigates the effects of copper sulfate and copper nitrate on the growth, biofilm formation, and antibiotic resistance profiles of Escherichia coli and Enterococcus faecalis. Across a wide concentration range (0.00005–100 mg/mL), both salts demonstrated strong antimicrobial activity at higher concentrations, while sublethal levels produced more nuanced effects. Higher concentrations exhibited potent antimicrobial activity, while sublethal concentrations paradoxically enhanced biofilm resistance, particularly in E. faecalis. Growth kinetic assays and spectroscopic analysis were used to better understand how copper interacts with microbes on a biochemical and physical level. Surprisingly, prolonged exposure to sublethal copper concentrations altered the antibiogram profiles of E. faecalis, developing resistance to ceftazidime. The findings confirm the bimodal activity of copper salts as antimicrobial and biofilm-controlling agents, highlighting the critical need for precise concentration optimization in wastewater treatment. This current study contributes to the collective knowledge pool of metal–microbe interactions, shedding light on selecting materials for industrial and environmental applications. Full article

Microplastics (MPs) have emerged as pervasive environmental contaminants due to their widespread presence across various ecosystems, including their use in single-use plastic food ware and table salt dispensers. This issue coincides with the presence of heavy metals in water sources in Doha, Qatar. Fourier Transform Infrared (FTIR) analysis revealed that the plastic plate and spoon were composed of polyolefin, with the spoon exhibiting additional peaks that indicated oxidation or the presence of additives. Thermogravimetric Analysis (TGA) revealed that the spoon exhibited higher thermal stability, retaining approximately 10% of its mass at 700 °C, than the plate, which retained 2%, indicating the presence of complex additives or contamination. MPs in food-grade salt samples were verified through filtration and Fourier Transform Infrared (FTIR) Spectroscopy, identifying polymers such as polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). These MPs likely stem from exposure to packaging or environmental contaminants. FTIR spectra confirmed the integrity of the polymers after treatment. Inductively Coupled Plasma–Optical Emission Spectroscopy (ICP-OES) analysis revealed varying levels of heavy metals in bottled and tap water, with notable findings including detectable arsenic and lead in both, higher calcium and magnesium in bottled water, and the presence of copper present in tap water only, highlighting potential health and infrastructure-related concerns. These results highlight the possible risks associated with exposure to MPs and heavy metals from everyday products and water sources, underscoring the need for enhanced regulatory oversight and safer material choices to ensure protection. Full article

This study investigates the influence of salt (NaCl) and, separately, frother (α-terpineol) on flotation of copper-bearing shale. It was shown, as expected, that increasing concentration of either NaCl or α-terpineol improves both ultimate shale recovery and the kinetics of flotation, except for very high frother concentrations, which lead to a drop in flotation. It appears that the relationship between the first-order flotation rate constant and ultimate recovery for both applied reagents follows the same pattern regardless of the different mechanisms of NaCl and frother action. Full article

This study develops a one-pot anodic templating electrodeposition strategy using dual-cation-crosslinking and interpenetrating networks, coupled with pulsed electrical signals, to fabricate a vessel-mimetic multilayered tubular hydrogel. Typically, the anodic electrodeposition is performed in a mixture of sodium alginate (SA) and carboxymethyl chitosan (CMC), with the ethylenediaminetetraacetic acid calcium disodium salt hydrate (EDTA·Na₂Ca) incorporated to provide a secondary ionic crosslinker (i.e., Ca²⁺) and modulate the cascade reaction diffusion process. The copper wire electrodes serve as templates for electrochemical oxidation and enable a copper ion (i.e., Cu²⁺)-induced tubular hydrogel coating formation, while pulsed electric fields regulate layer-by-layer deposition. The dual-cation-crosslinked interpenetrating hydrogels (CMC/SA-Cu/Ca) exhibit rapid growth rates and tailored mechanical strength, along with excellent antibacterial performance. By integrating the unique pulsed electro-fabrication with biomimetic self-assembly, this study addresses challenges in vessel-mimicking structural complexity and mechanical compatibility. The approach enables scalable production of customizable multilayered hydrogels for artificial vessel grafts, smart wound dressings, and bioengineered organ interfaces, demonstrating broad biomedical potential. Full article

Hypochlorous acid solutions are used as effective disinfectants in many settings, including operating rooms and other hospital environments. During and after the COVID-19 pandemic, their use increased significantly, and this work stems from that development. In fact, despite their undoubtedly excellent properties, these solutions can constitute a very aggressive system for a variety of different materials that are very common in those environments. Materials that can be subject to corrosion include steels, copper-based alloys, and components in electronic devices. This work aims to investigate the responses of these materials to long but intermittent exposures to HClO disinfectant solutions. It consists of a compatibility test, performed on several reference materials with HClO used as a surface disinfectant, connected with NaCl’s eventual presence/deposition over them. To perform the investigations in a manner consistent with the duration of compatible laboratory analyses, the samples were immersed in electrolytically prepared HClO solutions for 750 h, which is a duration considered equivalent to normal exposure to disinfectant aerosols over 3 years. Analyzing the large amount of experimental data gathered yielded interesting results. Where the exposure of non-metallic materials or steel did not lead to compatibility issues, bare metals showed degradation due to salt deposition. This article summarizes the morphological studies, i.e., a huge experimental work conducted at the ENEA IMPACT lab in Bologna and part of the PhD work of the corresponding author. Full article

The aim of this study is to determine the characteristics of the chemical and mineral composition of sediment layers in a technogenic settling pond. This pond is located on urban land in Berezniki (Perm Krai, Russia), outside the territory of operating industrial facilities, and contains alkaline saline industrial wastes. The origin of this waste was related to sludge from the Solvay soda production process, which had been deposited in this pond over a long period of time. However, along with the soda waste, the pond also received wastewater from other industries. As a result, the accumulated sediment is characterized by variation in morphological properties both in depth and laterally. Five undisturbed columns were taken to study the composition of the accumulated sediment. The obtained samples were analyzed by X-ray diffraction (XRD), synchronous thermal analysis (STA), and X-ray fluorescence (XRF) analysis. The results showed that the mineral composition of bottom sediments in each layer of all studied columns is characterized by the predominance of calcite precipitated from wastewater. Along with calcite, due to the presence of magnesium and sodium in the solution, other carbonates precipitated—dolomite and soda (natron), as well as complex transitional carbonate phases (northupite and trona). Together with carbonate minerals, the chloride salts halite and sylvin, sulfate minerals gypsum and bassanite, and pyrite and nugget sulfur were established. The group of terrigenous mineral components is represented by quartz, feldspars, and aluminosilicates. The chemical composition of sediments in the upper part of the section generally corresponds to the mineral composition. In the lower sediment layers, the role of amorphous phase and non-mineral compounds increased, which was determined by the results of thermal analysis. The content of heavy metals and metalloids also increases in the middle and lower sediment layers. When categorized according to the Igeo value, an excessive degree of contamination (class 6) was observed in all investigated columns for copper content (Igeo 5.2–6.1). Chromium content corresponds to class 5 (Igeo 4.1–4.6), antimony to class 4 (Igeo 3.0–4.0), and lead, arsenic, and vanadium to classes 2 and 3 (moderately polluted and highly polluted). The data obtained on variations in the mineral and chemical composition of sediments represent the initial information for the selection of methods of accumulated waste management. Full article

For various applications, particularly in battery technology, there is a significant demand for uniform, high-quality lithium or lithium-coated materials. The use of electrodeposition techniques to obtain such materials has not proven practical or economical due to the low solubility of most lithium salts in suitable solvents. In this study, we propose efficient lithium electrodeposition processes and baths that can be operated at low temperatures and relatively low costs. We utilized organic solvents such as dimethyl acetamide (DMA), dimethylforamide (DMF), and dimethyl sulfoxide (DMSO), as well as a mixture of DMSO and ionic liquid [1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide BMIMTFSI]. Lithium salts such as LiCl, Li₂CO₃, and LiNO₃ were tested. Lithium metal was deposited on copper substrates at different temperatures and selected current densities within an argon-filled glovebox using a DC power source or a PARSTAT-4000A potentiostat. Cyclic voltammetry (CV) was employed to determine and compare the deposition processes. The obtained deposits were analyzed through visual inspection (photography) and scanning electron microscopy (SEM). Chemical analysis (ICP-OES) and XRD confirmed the presence of lithium and occasionally lithium hydroxide in the deposits. The best results were achieved with the deposition of lithium from DMSO-LiNO₃ and DMSO-BMIMTFSI-LiNO₃ systems. Full article

This study prepared epoxy–clay nanocomposites (ECNs) by incorporating organophilic clays modified with either non-redox cetyltrimethylammonium bromide (CTAB) or redox-active aniline pentamer (AP), then compared their anticorrosion performance on metal substrates in saline environments. The test solution contained 2 wt% alkaline copper quaternary (ACQ) wood preservatives. Cold-rolled steel (CRS) panels coated with the ECNs were evaluated via electrochemical impedance spectroscopy (EIS) in saline media both with and without ACQ. For CRS coated with unmodified epoxy, the Nyquist plot showed impedance dropping from 255 kΩ to 121 kΩ upon adding 2 wt% ACQ—indicating that Cu²⁺ ions accelerate iron oxidation. Introducing 1 wt% CTAB–clay into the epoxy increased impedance from 121 kΩ to 271 kΩ, while 1 wt% AP–clay raised it to 702 kΩ. This improvement arises because the organophilic clay platelets create a more tortuous path for Cu²⁺ and O₂ diffusion, as confirmed by ICP–MS measurements of Cu²⁺ after EIS and oxygen permeability tests (GPA), thereby slowing iron oxidation. Moreover, ECN coatings containing AP–clay outperformed those with CTAB–clay in corrosion resistance, suggesting that AP not only enhances platelet dispersion but also promotes formation of a dense, passive metal oxide layer at the coating–metal interface, as shown by TEM, GPA, and XRD analyses. Finally, accelerated salt-spray exposure following ASTM B-117 yielded corrosion behavior consistent with the EIS results. Full article

To overcome the low efficiency, high cost and less environmentally friendly limitations in existing textile wastewater disposal technology, an innovative approach of cation exchange membrane electrolysis coupled with magnesium salt precipitation (CEM-MSP) was implemented. This method simultaneously achieved the high-efficiency adsorption decolorization of dyes and the recovery of lye. The results indicated that cation exchange membrane electrolysis with MgSO₄ added to the anode chamber (CEM-EA) exhibited excellent decolorization performance on DB86 dye and achieved low residual Mg²⁺ concentration. Furthermore, the adsorption mechanism of Mg(OH)₂ on DB86 was systematically investigated. The adsorption process fitted with the first-order kinetic, where the adsorption of DB86 by Mg(OH)₂ was dominated by electrostatic attraction. Detailed comparison of the four systems demonstrated that CEM-EA was superior to the single magnesium addition method (85.24%) or the stand-alone membrane electrolysis method (10.36%), with 99% decolorization efficiency. In comparison to the cation exchange membrane electrolysis with MgSO₄ added to the cathode chamber (CEM-EC), the CEM-EA could diminish the Mg²⁺ concentration in the effluent to facilitate the lye recovery while guaranteeing the decolorization efficiency. In addition, the DB86 adsorption behavior during the formation of Mg(OH)₂ in the cathode chamber was investigated. The Mg(OH)₂ particles were relatively dense copper-blue agglomerates with a thin lamellar layer on the surface. Notably, only slight mass contamination was observed on the cation exchange membrane (CEM) surface after multiple cycles. Minor CEM contamination illustrated the stable treatment efficiency of the CEM-EA after several cycles. This study constructed a novel approach integrating membrane electrolysis with magnesium salt precipitation, delivering valuable technical solutions for textile wastewater disposal. Full article

In response to the performance requirements of ship conductive rings in the coupled environment of high salt spray, high humidity, and mechanical wear in the ocean, a Cu-TiC composite coating was prepared on the surface of 7075 aluminum alloy by using the high-speed laser cladding (HLC) technology. The influence laws of the scanning speed (86.4–149.7 mm/s) on the microstructure, tribological properties, and corrosion resistance of the coating were explored. The results show that the scanning speed significantly changes the phase composition and grain morphology of the coating by regulating the thermodynamic behavior of the molten pool. At a low scanning speed (86.4 mm/s), the CuAl₂ phase is dominant, and the grains are mainly columnar crystals. As the scanning speed increases to 149.7 mm/s, the accelerated cooling rate promotes an increase in the proportion of Cu₂Al₃ phase, refines the grains to a coexisting structure of equiaxed crystals and cellular crystals, and improves the uniformity of TiC particle distribution. Tribological property analysis shows that the high scanning speed (149.7 mm/s) coating has a 17.9% lower wear rate than the substrate due to grain refinement and TiC interface strengthening. The wear mechanism is mainly abrasive wear and adhesive wear, accompanied by slight oxidative wear. Electrochemical tests show that the corrosion current density of the high-speed cladding coating is as low as 7.36 × 10⁻⁷ A·cm⁻², and the polarization resistance reaches 23,813 Ω·cm². The improvement in corrosion resistance is attributed to the formation of a dense passivation film and the blocking of the Cl diffusion path. The coating with a scanning speed of 149.7 mm/s exhibits optimal wear-resistant and corrosion-resistant synergistic performance and is suitable for the surface strengthening of conductive rings in extreme marine environments. This research provides theoretical support for the process performance regulation and engineering application of copper-based composite coatings. Full article

Critical-size bone defects do not heal spontaneously and require external support, making bone regeneration a central challenge in tissue engineering. Polymeric/ceramic composite scaffolds offer a promising approach to mimic the structural and biological properties of bone. In this study, we aimed to evaluate the effect of different doping oxides in bioactive glass (BG) on the performance of polycaprolactone (PCL)-based composite scaffolds for bone tissue engineering applications. Composite scaffolds were fabricated using solvent casting, hot pressing, and salt-leaching techniques, combining PCL with 25 wt% of BG or doped BG containing 4 mol% of tantalum, zinc, magnesium, or niobium oxides, and 1 mol% of copper oxide. The scaffolds were characterized in terms of morphology, mechanical properties, and in vitro biological performance. All scaffolds exhibited a highly porous, interconnected structure. Mechanical compression tests indicated that elastic modulus increased with ceramic content, while doping had no measurable effect. Cytotoxicity assays confirmed biocompatibility across all scaffolds. Among the tested materials, the Zn-doped BG/PCL scaffold uniquely supported cell adhesion and proliferation and significantly enhanced alkaline phosphatase (ALP) activity—an early marker of osteogenic differentiation—alongside the Nb-doped scaffold. These results highlight the Zn-doped BG/PCL composite as a promising candidate for bone regeneration applications. Full article

Li-ion battery recycling is growing with better tech and eco-awareness. Explosions are possible during battery recycling due to their residual voltage. Proper battery discharge is vital to successful recycling. The goal of this study was to investigate a new method for discharging cylindrical batteries, utilizing a saltwater solution and copper conductors and analyzing the impact of both direct and indirect contact between the copper and the battery. A key variable impacting the discharge process was inconsistent spacing between the battery and the copper conductor. In the gap, the saltwater, functioning as an electrolyte solution, created an electrical short circuit, thus causing faster discharge. Because the battery was not in contact with the copper conductor during the discharge process, corrosion of the battery cap and valve occurred, leading to the battery’s anode and cathode elements dissolving into the solution. However, a near-total voltage drop of 99% was observed in the battery, indicating that it was almost completely discharged. Upon making contact with the copper strip during its discharge cycle, the battery exhibited no signs of corrosion. This report details the battery discharge process, encompassing an analysis of the electrochemical reaction, schematic diagrams, and a chemical analysis of the discharge precipitate. Full article

Antibiotic resistance is a problem repeatedly reported by health authorities. Metalloantibiotics, i.e., biologically active compounds containing one or more metal ions, can be an important resource in the fight against bacteria and fungi. Here, we report the results obtained with a panel of copper(II), nickel(II) and zinc(II) complexes with thiosemicarbazone, semicarbazone and acylhydrazone ligands on Staphylococcus aureus, Escherichia coli and Candida albicans, taken as model systems of human pathogens. To increase the solubility in water, the sulfonic group was introduced on some of the ligands, isolating them as sodium salts (NaH₂L4-NaH₂L7). Complexes 1–14 were isolated, fully characterized and the X-ray structures of 11, 12 and 13 were obtained. While all the ligands have no antimicrobial activity, the copper(II) complexes 1 and 4 and the nickel(II) complex 2, obtained from thiosemicarbazone ligands, showed good activity, in particular against S. aureus; these complexes were investigated in depth, calculating their respective IC₅₀ values (4.2 μM, 3.5 μM and 61.8 μM, respectively). It should be noted that nickel(II) complex 2 does not show hemolytic activity and has a favorable SI value. While all the copper(II) complexes completely degraded the plasmid DNA in presence of H₂O₂, nickel(II) complex 2 cleaved the plasmid DNA leading to the formation of the relaxed nicked conformation, thus suggesting a different mechanism of action. Full article