Search Results (2,128)

Photocatalysis is a process in which a material utilizes light energy to degrade contaminants through oxidation reactions that decompose impurities upon contact with its surface. Titanium dioxide is one of the most widely used semiconductor materials due to its abundance, chemical stability, and non-toxicity. However, its relatively wide bandgap restricts its photocatalytic activity to the ultraviolet region of the solar spectrum, limiting its overall efficiency under natural sunlight. The incorporation of copper nanoparticles into the TiO₂ matrix enhances light absorption by extending its activity into the visible range, thereby improving its energy conversion efficiency. In this study, undoped and Cu-doped TiO₂ powders were synthesized using the mechanochemical method. The characteristics of the prepared photocatalyst material were determined by XRD, SEM, absorbance, and chemical analysis. XRD analysis showed the formation of TiO₂ in its anatase and rutile phases. Sphere-like shapes with a size of 100 nm were inferred from SEM images. The photocatalytic tests revealed that the Cu-doped TiO₂ nanoparticles exhibited high photocatalytic activity in degrading contaminated water. This enhancement can be attributed to the formation of oxygen vacancies, which promote the photodegradation of organic compounds. Full article

The synthesis of enantiomerically pure chiral β-nitroalcohols is a crucial objective in asymmetric catalysis. In order to efficiently obtain such chiral products, we developed a series of thermoresponsive, oxazoline–copper catalysts (Cu^II-PN_xFe_yO_z) via sequential reversible addition–fragmentation chain transfer (RAFT) polymerization. These catalysts can self-assemble in water into single-chain nanoparticles (SCNPs) with biomimetic behavior, in which intramolecular hydrophobic and metal-coordination interactions generate a confined hydrophobic cavity. Comprehensive characterization by FT-IR, TEM, DLS, CD, CA, and ICP analysis confirmed the nanostructure and composition. When applied to the aqueous-phase asymmetric Henry reaction between nitromethane and 4-nitrobenzaldehyde, the optimal catalyst (2.0 mol%) achieved a quantitative yield (96%) with excellent enantioselectivity (up to 99%) within 12 h. Furthermore, the thermosensitive poly(N-isopropylacrylamide, NIPAAm) block enabled facile catalyst recovery through temperature-induced precipitation above its lower critical solution temperature (LCST). This work presents an efficient and recyclable biomimetic catalytic system, offering a novel strategy for designing sustainable chiral catalysts for green organic synthesis. Full article

Heavy metals (HMs) and metal-oxide nanoparticles (NPs) frequently co-occur in freshwater systems, yet their combined effects on microbial predators remain poorly understood. Here, the freshwater ciliate Coleps hirtus was used to evaluate the cytotoxicity of single and binary mixtures of HMs (Cd, Cu, Zn) and NPs (ZnO, CuO, TiO₂, SiO₂), and to characterize associated antioxidant responses. Acute toxicity was assessed after 24 h by estimating LC₂₀ and LC₅₀ values, while mixture toxicity for Cd + Zn and Cd + ZnO was analyzed using the Toxic Unit approach and the MixTOX framework. Non-enzymatic (TPC, DPPH, HRSA) and enzymatic (CAT, GST, GPx, SOD) antioxidants were quantified as sublethal biomarkers at concentrations below lethal thresholds. HMs were markedly more toxic than NPs, with a toxicity ranking of Cu > Cd >> Zn, whereas NPs followed ZnO > CuO >> TiO₂ >> SiO₂. Cd + Zn mixtures showed predominantly antagonistic or non-interactive effects, while Cd + ZnO mixtures exhibited strong synergistic toxicity with a non-linear dependence on mixture composition, as supported by MixTox modeling. Exposure to HMs and NPs induced significant and often coordinated changes in antioxidant biomarkers, with binary mixtures eliciting stronger responses than single contaminants. Together, these findings indicate that mixture composition strongly influences both toxicity outcomes and oxidative stress responses in C. hirtus. The combination of clear, mixture-dependent toxicity patterns and robust oxidative stress responses makes C. hirtus a promising bioindicator for freshwater environments impacted by HMs and NPs. Full article

Three sizes of copper nanoparticles (1.7 nm, 2.8 nm, 3.4 nm) were synthesized using N902 as a surface-modifying ligand and diesel as the solvent. These nanoparticles were incorporated into biodiesel at volume fractions ranging from 0.005% to 0.20%, and their impacts on the lubrication performance, combustion characteristics, and thermal behavior of biodiesel were systematically investigated. The results indicated that the addition of copper nanoparticles significantly reduced the friction coefficient and wear scar diameter. Specifically, the 1.7 nm Cu nanoparticle sample achieved the most remarkable friction-reducing and anti-wear effects, with the friction coefficient and wear scar diameter decreasing by 16.07% and 20.1%, respectively. The combustion heat value of biodiesel showed a “first increase and then decrease” trend with the increase in nanoparticle addition, with the most significant improvement observed at an addition level of 0.01%. Among the three particle sizes, the 2.8 nm Cu nanoparticle sample effectively promoted the pyrolysis of biodiesel, while the 1.7 nm Cu nanoparticle sample exhibited optimal performance in reducing the oxidation induction time (OIT) and achieving complete combustion—characterized by lower CO emissions and minimal O₂ residue after combustion. Overall, the incorporation of copper nanoparticles realizes a synergistic enhancement, where lubricity improvement and combustion promotion occur concurrently, reflected by reduced OIT, lower CO emissions, and lower O₂ residue. Full article

This study examined the effects of applying silver nanoparticles (AgNPs; 0, 5 and 10 mg L⁻¹) in a hydroponic system for seven days on growth parameters and on nutrient and phytohormone concentrations in two tomato cultivars, Vengador and Rio Grande. The results indicated that AgNPs at concentrations of 5 and 10 mg L⁻¹ did not change leaf number, stem length, or fresh/dry biomass weight. In leaves of Vengador, P and K concentrations decreased, while Mg and S increased in response to AgNPs. In stems and roots, both P and K decreased. Zn concentrations increased in leaves, Mn in stems and roots. In leaves of Rio Grande, K, Mg, S, Cu and Mn concentrations increased, while P decreased in AgNP-treated plants, as compared to the control. In stems, N, S and Mn concentrations increased, but P, K, Ca, Mg and B decreased. In roots, P, K, Ca, Mg, Cu, Zn, Mn and B decreased, whereas S increased. Silver was only detected in roots of plants treated with AgNPs in both cultivars under study. In leaves of Rio Grande plants, kinetin concentrations decreased with AgNPs applications. In roots of Vengador, indole-acetic acid concentrations increased with 10 mg AgNP L⁻¹; in Rio Grande, roots exhibited an increased concentration of gibberellic acid and abscisic acid in plants exposed to 5 mg AgNP L⁻¹. The evidence retrieved from this work unveils the impact of metal-based NMs on the modulation of nutrient and phytohormone concentrations in a so important food crop such as tomato. Full article

This present study epitomises the fabrication of Cu-15%WC-X%Gr (X = 0, 3, 6, 9, 12) hybrid composites through a microwave sintering process. The synthesised composites were evaluated for hardness and compression strength as per ASTM standards. The composite corresponding to Cu-15%WC-9%Gr shows the optimal compression strength of 395 MPa. Based on this, the composite corresponding to the maximum compression strength was selected for subsequent wear investigations under dry, oil, and SiC nanofluid lubrication conditions. The SiC nanofluids were prepared by dispersing 1 wt% SiC, 1.5 wt% SiC, and 2 wt% SiC nanoparticles in soluble oils. Increasing the nanoparticle content enhanced both the thermal conductivity and zeta potential, indicating an improved heat transfer and dispersion stability. The wear test under different lubricating regimes demonstrates that the lubricating type had a pronounced influence on the wear rate and C.O.F. The minimum rate of wear of 0.0235 mm³/m and C.O.F. of 0.28 were achieved for the 2 wt% SiC nanofluid lubrication. The worn surfaces under dry and oil-lubricated regimes revealed prominent microcracks and delamination wear. In contrast, surfaces tested under nanofluid lubrication exhibited smoother grooves with minimal surface damage and an absence of microcracking. Full article

In metal cutting industries, optimizing the thermal conductivity and viscosity of vegetable oil-based cutting fluids is critical for ensuring efficient heat dissipation, effective lubrication, and sustainability, directly influencing tool life and machining performance. This study presents a comprehensive experimental analysis employing statistical methods, particularly Taguchi’s Design of Experiments, to evaluate the thermal conductivity and viscosity of Pongamia pinnata, sunflower, and coconut oil incorporated with Silicon Dioxide (SiO₂), Hexagonal Boron Nitride (hBN), and Cupric Oxide (CuO) nanoparticles across different emulsion ratios and nanoparticle volume fractions. The results revealed that Pongamia pinnata oil containing 0.5 (Vol.%) SiO₂ nanoparticles at an emulsion ratio of 1:7 achieved the maximum thermal conductivity, measured at 0.637 W/mK. Additionally, the results revealed that Pongamia pinnata oil at an emulsion ratio of 1:13 exhibited the highest viscosity of 1.33 mPa·S, confirming that both the type of cutting oil and the emulsion ratio are the primary factors influencing viscosity. Further, the ANOVA analysis for thermal conductivity and viscosity highlights that the type of cutting fluid is the dominant factor, accounting for 90.58% of the total variance in thermal conductivity and 70.47% in viscosity, each with a highly significant p-value of 0.00, underscoring its decisive impact on the stability of both properties. Overall, this research offers important guidance for the selection and formulation of vegetable oil-based emulsions with nanoparticle additives. The results support the development of advanced nano lubricants with enhanced performance, catering to the increasing requirements of diverse industrial applications. Full article

Photocatalytic reduction of CO₂ into value-added chemicals offers a sustainable route to mitigate greenhouse gas emissions while producing renewable fuels. However, conventional TiO₂-based systems suffer from limited visible-light activity and inefficient reactor configurations. Here, we developed electrospun polyacrylonitrile (PAN) membranes embedded with TiO₂-Cu₂O heterojunction nanoparticles and integrated them into a custom crossflow photocatalytic membrane reactor. The reactor employed bifacial illumination using a solar simulator (front) and a xenon/mercury lamp (back), each calibrated to 1 Sun (100 mW·cm⁻²). Membrane morphology was characterized by SEM, and chemical composition was confirmed by XPS. Photocatalytic performance was evaluated in CO₂-saturated 0.5 M potassium bicarbonate solution under continuous flow. The PAN/ TiO₂-Cu₂O membrane exhibited a methanol production rate of approximately 300 μmol·g⁻¹·h⁻¹ under dual-light illumination, outperforming single illumination, PAN-TiO₂, and PAN controls. Enhanced activity is attributed to extended visible-light absorption, improved charge separation at the TiO₂-Cu₂O heterojunction, and optimized photon flux through bifacial illumination. The electrospun architecture provided high surface area and porosity, facilitating CO₂ adsorption and catalyst dispersion. Combining heterojunction engineering with bifacial reactor design significantly improves solar-driven CO₂ conversion. This approach offers a scalable pathway for integrating photocatalysis and membrane technology into sustainable fuel synthesis. Full article

Gold nanoparticles (Au-NP) are frequently used as model nanomaterials to study nanoparticle behavior in plants due to their analytical detectability and negligible natural background in plant tissues. However, the feasibility of visualizing the spatial distribution of foliar-applied Au-NP at low exposure levels using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) remains insufficiently explored. In this study, commercially sourced Au-NP were applied to lentil leaves (Lens culinaris var. Beluga) at a low concentration of 0.5 mg·L⁻¹ using a controlled leaf submersion approach. Leaves were sampled at 1 h, 24 h, and 96 h post-exposure and analyzed by LA-ICP-MS imaging to assess time-dependent changes in gold-associated spatial signals, and to compare elemental distribution patterns with non-exposed controls. Untreated control leaves showed no detectable gold at any sampling time point, confirming negligible native Au background. In treated leaves, LA-ICP-MS imaging revealed an initially localized Au hotspot at 1 h, followed by progressive Au redistribution toward the leaf margins and petiole region by 24 h and 96 h. Gold signals persisted over the full 96 h period, indicating stable association of Au-NP with leaf tissue. Comparative elemental mapping of Ca, Mg, K, P, Fe, Zn, and Cu showed no persistent differences in spatial distribution patterns between treated and control leaves as detectable by LA-ICP-MS. This study demonstrates the feasibility of LA-ICP-MS imaging for visualizing the deposition and temporal spatial redistribution of low-dose foliar-applied nanoparticles in intact leaves. The results provide a methodological reference for future hypothesis-driven studies that apply nanoparticles under more controlled conditions, include increased replication, and combine multiple analytical techniques. Full article

The synthesis, in particular the industrial production, of pharmaceuticals requires a broad arsenal of synthetic reactions capable of selectively forming specific structural motifs and assembling smaller building blocks into complex molecules. The Chan–Evans–Lam cross-coupling reaction, which forms a bond between a N-nucleophile and an aryl group from a boronic acid, catalysed by copper salts, is a typical example of this synthetic route. Considering the toxicity of copper and the stringent regulatory limits for its residues in final pharmaceutical products, a heterogeneous catalytic approach offers a viable alternative for this transformation. In this work, we present a simply and reproducibly synthesized catalyst based on copper nanoparticles supported on reduced graphene oxide (Cu-rGO), with high efficiency in a model Chan–Lam reaction involving benzimidazole and aniline derivatives with substituted boronic acids. Full article

This study addresses the critical need for advanced biomedical materials that possess both potent antimicrobial properties and high biocompatibility to prevent device-related infections and promote healing. To this end, we demonstrate the successful development and comprehensive characterization of functional composite materials based on a photopolymerizable acrylate resin modified with laser-ablated copper nanoparticles (Cu NPs). The synthesized Cu NPs exhibited a monomodal size distribution with a peak at 47 nm, a high zeta potential of −33 mV, and a spherical morphology. Incorporation of Cu NPs into the polymer matrix via Masked Stereolithography (MSLA) enabled the fabrication of complex structures that maintained high surface quality and optical transparency after polishing. Modification of photopolymer resin with Cu NPs significantly increased the strength of the resulting products and caused dose-dependent formation of reactive oxygen species (ROS). The resulting composite materials exhibited strong antibacterial activity against E. coli. Crucially, despite their potent antimicrobial efficacy, the materials showed no cytotoxicity towards human fibroblast cultures. These results highlight the potential of these composites for a new generation of biomedical applications, such as implantable devices and wound coatings, which combine programmable antimicrobial activity with high biocompatibility. Full article

Herein, we propose a simple and cost-effective method for fabricating moderate-sensitivity surface-enhanced Raman scattering (SERS) substrates using Cu-plasma polymer fluorocarbon (Cu-PPFC) nanocomposite films fabricated through RF sputtering. The use of a composite target composed of carbon nanotube (CNT), Cu, and polytetrafluoroethylene (PTFE) powders (5:60–80:35–15 wt%) offers the advantage of the simple fabrication of moderate-sensitivity SERS substrates with a single cathode compared to co-sputtering. X-ray photoelectron spectroscopy (XPS) revealed that the film surface was partially composed of metallic Cu with Cu-F bonds and Cu–O bonds, confirming the coexistence of the conducting and plasmon-active domains. UV-VIS spectroscopy revealed a distinct absorption peak at approximately 680 nm, indicating the excitation of localized surface plasmon resonances in the Cu nanoclusters embedded in the plasma polymer fluorocarbon (PPFC) matrix. Atomic force microscopy and grazing incidence small-angle X-ray scattering analyses confirmed that the Cu nanoparticles were uniformly distributed with interparticle distances of 20–35 nm. The Cu-PPFC nanocomposite film with the highest Cu content (80 wt%) exhibited a Raman enhancement factor of 2.18 × 10⁴ for rhodamine 6G, demonstrating its potential as a moderate-sensitivity SERS substrate. Finite-difference time-domain (FDTD) simulations confirmed the strong electromagnetic field localization at the Cu-Cu nanogaps separated by the PPFC matrix, corroborating the experimentally observed SERS enhancement. These results suggest that a Cu-PPFC nanocomposite film, easily fabricated using a composite target, provides an efficient and scalable route for fabricating reproducible, inexpensive, and moderate-sensitivity SERS substrates suitable for practical sensing applications. Full article

Ni-based catalysts have been extensively investigated for lignin hydrogenation; however, they often exhibit limited phenol selectivity and poor catalytic stability. To address these challenges, we introduced Cu as a promoter, resulting in the development of NiCu/ZSM-5 catalysts with significantly enhanced phenol selectivity and durability. Characterization studies revealed that Cu species form an alloy structure with Ni, which effectively suppresses the sintering of Ni nanoparticles during the catalytic process, thereby maintaining consistent performance over multiple reaction cycles. Furthermore, the Cu-Ni alloy demonstrated improved hydrogen activation capability while reducing overall H₂ uptake, leading to a marked increase in phenol selectivity compared to the Cu-free Ni/ZSM-5 catalyst. As a result, the Ni₁Cu₁/ZSM-5 (Ni/Cu molar ratio = 1:1) catalyst achieved a lignin conversion of 69.8% and a phenol selectivity of 84.4%, with negligible performance degradation over 8 cycles. The strategy presented in this work may offer an effective approach for enhancing the performance of industrial catalysts in lignin upgrading processes. Full article

Drugs and drug candidate compounds commonly suffer from poor solubility and permeability. One promising strategy to mediate these drawbacks is use of novel solvents, such as deep eutectic compositions. The present research aims to determine the applicability of this approach for therapeutic metal complexes on the example of [Cu(Fur)₂(Phen)] (Fur = furoate-anion, Phen = 1,10-phenantroline) and [Cu(Fur)₂(Neoc)(H₂O)] (Fur = furoate-anion, Neoc = 2,9-dimetyl-1,10-phenanthroline) with molar weight of appx. 500 Da. Interaction of the metal complexes with the deep eutectic solvent (DES) reline was studied using electron paramagnetic resonance (EPR). Minimal inhibitory concentrations of the complexes dissolved in DES and dimethyl sulfoxide (DMSO) were determined and found to be equivalent in both solvents. That is, use of reline as a solvent did not alter the functional properties of the metal complexes. Changes in the transdermal permeation of the complexes in DMSO and DES were assessed using a Franz diffusion cell. It was discovered that depending on the structure of the complex, the permeability might either increase (from 15 to 30%) or decrease (from 13 to 8%) with changes in the solvent, and this can be used to develop dosing strategies. Therapeutic eutectogels were successfully produced by impregnating SiO₂ nanoparticles with the metal complex solution in DES, facilitating convenient topical application. Full article

This investigation has yielded a remarkably efficient metallic catalyst. Copper (Cu), cobalt (Co), and nickel (Ni) nanoparticles were concurrently deposited onto micron-sized aluminum (µAl) through a displacement reaction, resulting in the formation of [nCu+nCo+nNi]/µAl composites. The interfacial layer of the nanocomposite facilitates the creation of efficient oxygen transport pathways, significantly augmenting thermal release. In the context of the ADN/AP oxidizer, the [nCu+nCo+nNi]/µAl configuration demonstrates a substantial synergistic catalytic effect, reducing its thermal decomposition temperature by an impressive 104.1 °C. Combustion experiments have corroborated that this composite markedly enhances flame intensity, combustion temperature, and the burning rate of the ADN/AP system. The underlying thermal-oxidative mechanism was elucidated through comprehensive thermal analysis of the composite both prior to and following a heat treatment at 1100 °C. Moreover, through an integration of thermal analysis and combustion experiments, the catalytic mechanism of [nCu+nCo+nNi]/µAl on the thermolysis of ADN/AP was elucidated, and a plausible reaction pathway under thermal stimulation was proposed (e.g., ${\mathrm{NH}}_4{\mathrm{ClO}}_4+{{\mathrm{NH}}_4\mathrm{N}({\mathrm{NO}}_2)}_2\stackrel{\mathrm{Cu},\mathrm{Co},\mathrm{Ni}}{\to }{\mathrm{N}}_2+{\mathrm{H}}_2\mathrm{O}+\mathrm{HCl}+{\mathrm{O}}_2+\left[\mathrm{O}\right]$). The developed nanocomposite significantly enhances the performance of oxidizers, presenting considerable potential for a wide array of applications in solid propellants. Full article