Search Results (129)

The current work aims to enhance the structural, optical, photocatalytic, and cytotoxic properties of CuO NPs at varied rGO concentrations of 5% and 10%. In the present work, a one-step hydrothermal method was successfully applied to prepare rGO/CuO NCs at different concentrations of RGO. The novelty of this work was to enhance the structural, optical, photocatalytic, and cytotoxic properties of CuO using the addition of rGO sheets. XRD, TEM, SEM-EDX, XPS, FTIR, UV-vis, PL, and DLS techniques were used to characterize the prepared samples. XRD data confirmed the formation of the monoclinic phase of CuO with a decrease in crystallite size, from 21.14 nm for CuO to 16.94 nm for the 10% rGO/CuO NCs nanocomposite. SEM and TEM images verified the uniform anchoring and excellent dispersion of CuO nanoparticles on the rGO sheets, and the EDX spectra showed the presence of Cu, O, and C elements in the obtained rGO/CuO NCs. DLS measurements showed that the hydrodynamic radius dropped from 69.98 ± 17.81 nm for CuO to 51.72 ± 10.48 nm for 10% rGO/CuO NCs. The zeta potential values remained negative for all samples, ranging from −20.50 ± 8.69 mV for CuO to −25.60 ± 9.08 mV for 10% rGO/CuO NCs, suggesting enhanced colloidal stability with rGO incorporation. Furthermore, FTIR and XPS analyses confirmed that Cu–O–C bonding formed between CuO and rGO. UV-Vis analysis revealed a redshift in the absorption edges as rGO content increased, reducing the band gap from 3.65 eV to 3.60 eV. Additionally, PL spectra showed a marked reduction in emission intensity due to a decrease in the recombination rate between electron (e⁻)–holes (h⁺) pairs. The CuO/(10%)rGO NCs showed the best photocatalytic performance with a 93.56% degradation of methylene blue (MB) after 120 min under UV irradiation, and followed pseudo-first-order kinetics with k = 0.0203 min⁻¹. Cytotoxicity studies on HT1080 cells showed a dose-dependent decrease in viability. 10% rGO/CuO NCs exhibited the highest cytotoxicity effect, resulting in 58% and 50% viability at 1.4 mg/mL, respectively. The presented results showed that the presence of rGO in CuO NPs played a role in enhancing the structural stability, charge mobility, and biological reactivity of Cu NPs. This study highlighted that the rGO/CuO NCs are a promising multi-functional material for environmental and biomedical applications. Full article

In this study, the characterization of some bioactive content of exopolysaccharide (EPS) extracted from Pediococcus ethanolidurans isolated with Smilax excelsa L. from conventionally produced pickles were investigated. Background: Although this study is the main study involving the characterization of EPS obtained from Pediococcus ethanolidurans, it is important because it has determined a natural polysaccharide that can be used in different fields in the industry. According to the obtained results, sugar analysis by GC-MS revealed that EPS consisted of glucose (7.59%), mannose (41.96%), fructose (16.98%), arabinose (3.15%) and rhamnose (30.30%). From the thermal behavior determined by differential scanning calorimetry (DSC), it was concluded that it should not be heated close to 250 °C. At the same time, according to the thermogram obtained as a result of X-ray diffraction (XRD) analysis, it was found to have a crystalline structure. EPS, which reached 73.844% efficiency, showed antibacterial activity against Listeria monocytogenes, Staphylococcus aureus and Escherichia coli, while 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) scavenging activity was detected at 0.24 mM. It also has remarkable results, seen in cytotoxicity analysis against healthy HT-29 cells, demonstrating that it has proliferative activity as high as %125 In short, Pediococcus ethanolidurans was found to be a novel EPS producer with impressive properties. Full article

Cemented Paste Backfill (CPB) is a technique that utilizes mine tailings, mining-process water, and a binder, typically Ordinary Portland Cement (OPC), to backfill the opening created in underground mining. However, the use of cement in CPB increases operational costs and has adverse environmental effects. To mitigate these effects, eco-friendly natural pozzolan can be used as a partial replacement for OPC, thereby reducing its consumption and environmental impact. The volcanic region of western Saudi Arabia contains extensive deposits of Saudi natural pozzolan (SNP), which is a promising candidate for this purpose. This study evaluates the mechanical performance of CPB under four scenarios: a control mixture (CTRL), a mixture with untreated SNP (UT), and mixtures with activated SNP, specifically heat-treated (HT) and mechanically treated (MT). Each scenario was tested at replacement levels of 5%, 10%, 15%, and 20% of OPC. The performance was assessed using Uniaxial Compressive Strength (UCS) with Elastic Modulus (E), Ultrasonic Pulse Velocity (UPV), and Indirect Tensile Strength (ITS/Brazilian) tests. The results indicate that the HT scenario at a 5% replacement level delivered the highest performance, slightly outperforming the MT scenario. Both activated scenarios (HT and MT) significantly surpassed the untreated mixture (UT). Overall, the HT scenario proved to be the most effective among all CPB mixtures tested. XRD diffractogram analysis supported HT as the material with the highest strength performance due to the occurrence of more strength phases than other CPB materials, including Alite, Quartz, and Calcite. While UCS and UPV showed a positive correlation across all CPB materials, the relationship between UPV and the modulus of elasticity (E) demonstrated a low correlation. The findings suggest that using activated SNP materials can enhance CPB sustainability by lowering cement demand, stabilizing operating costs, and reducing environmental impacts. Full article

Background: Piper nigrum L. (PNL) is a rich source of piperine, a bioactive alkaloid with pharmaceutical, cosmetic, nutritional supplement, and agricultural applications, yet efficient and sustainable extraction methods remain underexplored. Methods: This study compared ultrasonic bath extraction (UBE) and ultrasonic probe extraction (UPE) using natural deep eutectic solvents (NADES) for isolating piperine from PNL fruits. Six NADES formulations were screened, with NADES-5 (choline chloride:glycerin:urea, 1:1:1) showing superior performance. Response surface methodology with a Box–Behnken design optimized extraction parameters, including liquid-to-solid ratio, extraction time, temperature, and water content, for both UBE and UPE. Results: Optimized UPE consistently outperformed UBE, yielding 49.97 mg/g of piperine versus 25.67 mg/g under identical NADES conditions. Comprehensive characterization using TLC, HPTLC, UV, FTIR, Raman, HPLC, NMR, XRD, SEM, and EDX confirmed the successful isolation and structural integrity of piperine, with samples obtained via UPE exhibiting higher purity (98.7% vs. 95.2%) and enhanced crystallinity. In vitro cytotoxicity assays demonstrated that piperine extracted by UPE showed stronger activity against C2C12 myoblasts (IC₅₀: 24.3 μg/mL vs. 40.6 μg/mL) and greater anticancer effects in MCF-7 and HT-29 cells compared to piperine extracted by UBE. Antioxidant evaluation via DPPH, ABTS, FRAP, and TAC assays, along with intracellular reactive oxygen and nitrogen species suppression in THP-1 and RAW 264.7 macrophages, further confirmed the superior biological potential of the UPE-derived piperine sample. Conclusions: These findings indicate that UPE using NADES is a sustainable approach for high-yield piperine extraction with enhanced purity and bioactivity, supporting its potential for pharmaceutical applications. Full article

The aim was to optimize a series of aluminosilicate glasses for the synthesis of leucite glass-ceramics (GC) for dental applications. Appen predictive models were used to design a series of aluminosilicate glasses to control optical, thermal and mechanical properties. Glasses were produced using melt quenching methods, annealed and processed into powders and further heat-treated and milled to produce GC powders. Glasses/GCs were characterized using dilatometry, HTXRD, SEM and ²⁷Al MAS-NMR and GCs tested using biaxial flexural strength (BFS) for comparison to commercial leucite GC products. The results indicated good prediction to experimental measurement correlations (for coefficient of thermal expansion, refractive index and density) and provided evidence of leucite GCs’ optimization compared to commercial products. This included significant BFS and Weibull m increases, improved microstructural control and designed translucency, meeting the demands for strong, esthetic and durable single-tooth restorations. The simple predictive approach, combined with complementary characterization techniques, allowed structure–property relations of aluminosilicate glasses/glass-ceramics to be understood, and may find similar applications in other glass systems beyond dentistry. Full article

The mechanical and microstructural properties of monolithic zirconia ceramics are significant factors for their long-term clinical performance. This study aims to investigate the effects of hydrothermal aging on these properties for the 3Y-TZP, 4Y-TZP, and 5Y-TZP formulations. Specimens were prepared from 3 different zirconia blocks: 3Y-TZP (HT), 4Y-TZP (ST), and 5Y-TZP (XT). Half of the specimens were aged in an autoclave (134 °C, 2 bar, 5 h) while the others remained as controls. Three-point flexural strength, Vickers hardness, and surface roughness tests, as well as XRD, AFM, and SEM/EDS analysis, were performed. The material type significantly affected the flexural strength, Vickers hardness, and surface roughness. Aging did not significantly affect the flexural strength or surface roughness but reduced the Vickers hardness in the 3Y-TZP sample. The 3Y-TZP and 5Y-TZP samples displayed the highest and lowest flexural strength, respectively. In the non-aged groups, 3Y-TZP and 5Y-TZP exhibited higher hardness than 4Y-TZP, and after aging, 3Y-TZP displayed the lowest hardness. Further, 5Y-TZP showed the highest surface roughness before and after aging. XRD revealed an increased monoclinic phase in the aged 3Y-TZP and 4Y-TZP. No monoclinic phase was observed in 5Y-TZP. According to AFM measurements, aging led to a smoother surface in 3Y-TZP but increased roughness in 4Y-TZP and 5Y-TZP. SEM/EDS revealed changes in the elemental compositions following aging. According to the results of this study, different material formulations affect the mechanical behavior and microstructural properties of monolithic zirconia ceramics. Further, hydrothermal aging displayed effects on the Vickers hardness and phase transformations. Full article

The efficient resource utilization of industrial solid wastes, such as ground granulated blast-furnace slag (GGBS) and coal gangue (CG), is essential for sustainable development. However, their activation commonly depends on expensive and corrosive chemical alkalis. This study proposes a solution by developing a fully waste-based cementitious material using calcium carbide slag (CS), another industrial residue, as an eco-friendly alkaline activator for the GGBS-CG system. The influence of CS dosage (0–20 wt%) on hydration evolution and mechanical properties was examined using uniaxial compression testing, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results indicated that a CS dosage of 10 wt% yielded the highest compressive strength, reaching 10.13 MPa—a 16.5% improvement compared to the 20 wt% group. This enhancement is ascribed to the formation of hydrotalcite (HT) and calcium silicate hydrate (C-(A)-S-H) gel, which densify the microstructure. In contrast, higher CS contents led to a passivation effect that restrained further reaction. This work offers a practical and theoretical basis for the development of low-carbon, multi-waste cementitious materials and presents a promising strategy for large-scale valorization of industrial solid wastes. Full article

Titanium silicalite-1 (TS-1) is an effective catalyst, but its limited pore size restricts the access of bulky substrates such as α-pinene. In our previous studies, a TS-1 catalyst with a Si/Ti molar ratio of 20:1 demonstrated high activity in α-pinene oxidation but suffered from diffusion limitations. To overcome this drawback, four new titanium silicate catalysts were synthesized using the reference TS-1 as the parent material (TS-1 catalyst with the Si/Ti molar ratio of 20:1). MTS-1_1 and MTS-1_2 were prepared via a co-templating method, while HTS-1_1 and HTS-1_2 were obtained through post-synthetic recrystallization using triethylamine (method I) or sulfuric acid followed by triethylamine (method II). All catalysts were characterized by UV–Vis, FTIR, XRD, SEM, EDXRF, and nitrogen sorption, and their activity was tested in solvent-free oxidation of α-pinene using molecular oxygen. The influence of temperature, catalyst content, and reaction time on the conversion of α-pinene and the selectivities of the main products was investigated. All modified materials exhibited higher catalytic activity than the reference TS-1 material. HTS-1_2 showed the best results, achieving the conversion of α-pinene of 21 mol% and the selectivity of transformation to α-pinene oxide of 35 mol%. Verbenol and verbenone were also formed as valuable oxygenated products. The developed catalysts enable a green and efficient transformation of renewable α-pinene into high-value derivatives. Full article

The phase equilibria of the Si-C-Cu ternary system at 700 °C and 810 °C were experimentally investigated for the first time. Fifteen key alloys were prepared via powder metallurgy and analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Isothermal sections were constructed based on the identified equilibrium phases. At 700 °C, eight single-phase regions and six three-phase regions—(C)+(Cu)+hcp, (C)+hcp+γ-Cu₃₃Si₇, (C)+γ-Cu₃₃Si₇+SiC, γ-Cu₃₃Si₇+SiC+ε-Cu₁₅Si₄, SiC+ε-Cu₁₅Si₄+η-Cu₃Si(ht), and SiC+(Si)+η-Cu₃Si(ht)—were determined. At 810 °C, nine single-phase regions and seven three-phase regions were identified. The solubility of C and Si/Cu in the various phases was quantified and found to be significantly higher at 810 °C compared to 700 °C. Key differences include the presence of the bcc (β) and liquid phases at 810 °C. The results demonstrate that higher temperatures promote increased mutual solubility and reaction tendencies among Cu, C, and Si. Motivated by these findings, the influence of vacuum hot pressing parameters on SiC-fiber-reinforced Cu composites (SiC_f/Cu) was investigated. The optimal processing condition (1050 °C, 60 MPa, 90 min) yielded a high bending strength of 998.61 MPa, attributed to enhanced diffusion and interfacial bonding facilitated by the high-temperature phase equilibria. This work provides essential fundamental data for understanding interactions and guiding processing in SiC-reinforced Cu composites. Full article

This study presents a novel, eco-friendly synthesis route for zinc oxide (ZnO) nanoparticles using cladode extracts of Hylocereus undatus acting simultaneously as reducing and improving agents, in alignment with green chemistry principles. The synthesis involved the reaction of zinc sulfate heptahydrate with the plant extract, with the medium pH adjusted using sodium hydroxide (NaOH), followed by calcination at 300 °C, 400 °C, and 500 °C, and then by a washing step to enhance purity. Comprehensive characterization was performed using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrical impedance spectroscopy to investigate the structural, morphological, and dielectric properties of the nanoparticles. The sample calcined at 400 °C, followed by washing (HT400W), exhibits highly crystalline ZnO nanoparticles with a predominant wurtzite structure (93.15 wt% ZnO) and minimal impurities (6.85 wt% Na₂SO₄). SEM analysis indicated a flake-like morphology with nanoscale features (50–100 nm), while Raman spectroscopy confirmed enhanced crystallinity and purity post-washing. Additionally, the HT400W sample exhibited a dielectric constant (ε′) of 16.96 and a low loss tangent (tan δ) of 0.14 at 1 MHz, suggesting superior energy efficiency for high-frequency applications. This green synthesis approach not only eliminates hazardous reagents but also delivers ZnO nanoparticles with good dielectric performance. Furthermore, this work demonstrates the efficacy of a sustainable biotemplate, offering an environmentally friendly approach for synthesizing ZnO nanoparticles with tailored physicochemical properties. Full article

The functional performance of magnesium hydroxide (Mg(OH)₂) is intrinsically governed by its crystallographic morphology. Herein, we demonstrate an electrochemical deposition strategy to synthesize Mg(OH)₂ from abandoned MgCl₂ resources in salt lakes, achieving simultaneous waste valorization and morphology control. Systematic investigations were conducted on the effects of polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) as surfactants on electrochemical parameters (cell voltage, pH, current efficiency, and energy consumption) and morphological evolution (XRD, SEM, and laser particle size analysis). Results show that the cell voltage and pH increased proportionally with surfactant concentration, with a current efficiency of 93.86% and an optimal energy consumption of 4.15 kW h·t⁻¹ at an optimal PVP concentration of 6 g·L⁻¹. PEG addition exhibited a similar trend in process parameter modulation. Morphological evolution analysis revealed that appropriate PEG dosage promoted the transformation of irregular Mg(OH)₂ flakes into near-spherical platelets, accompanied by a measurable increase in particle size. This work establishes structure–property relationships between surfactant molecular design and Mg(OH)₂ crystallization, providing theoretical support for the controllable electrochemical preparation of magnesium hydroxide with different morphologies. Furthermore, it opens up a novel and innovative technical pathway to promote the high-value utilization of abandoned magnesium resources in salt lakes. Full article

A critical barrier to the clinical translation of biodegradable magnesium (Mg)-based materials lies in their rapid degradation rate in physiological environment, which leads to premature structural failure and compromised cytocompatibility. Micro-arc oxidation (MAO) coatings offer preliminary corrosion mitigation for Mg alloys, while their inherent structural porosity compromises long-term durability in physiological environment. To address this limitation, we developed a hierarchical coating system consisting of a dense Mg(OH)₂ interlayer (MAO/HT) superimposed on the MAO-treated substrate, followed by a functional polydopamine (PDA) topcoat to create a MAO/HT/PDA composite architecture. The surface characteristics and crystalline structures of these coatings were systematically characterized using field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The corrosion resistance and interfacsial stability in physiological environment were quantitatively assessed through electrochemical analyses and long-term immersion tests in simulated body fluid (SBF). The cytocompatibility of the coatings was assessed by directly culturing osteoblast on the coated samples. The results reveal that the Mg(OH)₂ film possesses a bulk-like structure and effectively seals the micro-pores of the MAO coating. The current density of MAO/HT/PDA sample decreases by two orders of magnitude compared to that of MAO sample, indicating excellent corrosion resistance. The PDA layer not only acts as a strong barrier to improve the corrosion performance of the coating but also helps maintain the stability of the coating, thus delaying coating destruction in SBF. Moreover, the osteoblast culture results suggest that the MAO/HT/PDA coating promotes cell spread and proliferation noticeably compared to both the MAO and MAO/HT coatings. This study provides compelling evidence that the Mg(OH)₂/PDA composite coating is biodegradable and offers outstanding protection for micro-arc oxidized magnesium. As a result, it holds great promise for significant applications in the field of orthopedic medicine. Full article

In this study, praseodymium-doped cobalt ferrite nanoparticles (CoFe_2−yPr_yO₄, y = 0–0.2) were synthesized via sol-gel auto-combustion and systematically characterized to assess their structural, morphological, magnetic, and biological properties. X-ray diffraction (XRD) confirmed single-phase cubic cobalt ferrite formation for samples with y ≤ 0.05 and the emergence of a secondary orthorhombic PrFeO₃ phase at higher dopant concentrations. FTIR spectroscopy identified characteristic metal–oxygen vibrations and revealed a progressive shift of absorption bands with increasing praseodymium (Pr) content. Vibrating sample magnetometry (VSM) demonstrated a gradual decline in saturation (Ms) and remanent (Mr) magnetization with Pr doping, an effect further intensified by cyclodextrin surface coating. TEM analyses revealed a particle size increase correlated with dopant level, while SEM images displayed a porous morphology typical of combustion-synthesized ferrites. In vitro cell viability assays showed minimal toxicity in normal human keratinocytes (HaCaT), while significant antiproliferative activity was observed against human cancer cell lines A375 (melanoma), MCF-7 (breast adenocarcinoma), and HT-29 (colorectal adenocarcinoma), particularly in Pr 6-CD and Pr 7-CD samples. These findings suggest that Pr substitution and cyclodextrin coating can effectively modulate the physicochemical and anticancer properties of cobalt ferrite nanoparticles, making them promising candidates for future biomedical applications. Full article

Mg-Al hydrotalcite (HT), comprising Mg²⁺ and Al³⁺ as layered hydroxide cations, was synthesized via a hydrothermal process at 200 °C. The HT was evaluated as a carrier, and subsequently, palladium was immobilized on the surface of the hydrotalcite (HT/NC), resulting in the development of an innovative biomass-based palladium catalyst. The catalyst underwent analysis by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). It exhibited remarkable catalytic efficiency and superior activity as a catalyst in the Suzuki–Miyaura coupling reaction in water. The catalyst was recyclable without a decline in activity and could be utilized more than 10 times, with exceptional yield. Furthermore, the commercially accessible anticancer drug Elacestrant can be readily produced using this protocol. Full article

This study presents the integration and evaluation of commercially available gas diffusion electrodes (GDEs), specifically designed for high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) within membrane electrode assemblies (MEA) for electrochemical hydrogen pump/compressor applications (EHP/C). Using Nafion 117 as a solid polymer electrolyte, the MEAs were analyzed for cell efficiency, hydrogen evolution, and hydrogen oxidation reactions (HER and HOR) under differential pressure up to 16 bar and a temperature ranging from 20 °C to 60 °C. Key properties of the GDEs, such as electrode thickness and conductivity, were investigated. The catalytic layer was characterized via XRD and EDX analyses to assess its surface and bulk composition. Additionally, the effects of increasing MEA’s geometric size (from 1 cm² to 5 cm²) and hydrogen crossover phenomena on the efficiency were examined in a single-cell setup. Electrochemical performance tests conducted in a single electrochemical hydrogen pump/compressor cell under hydrogen flow rates from 36.6 Ml·min⁻¹·cm⁻² to 51.3 mL·min⁻¹ cm⁻² at atmospheric pressure provided insights into the optimal operational parameters. For a double-stage application, the MEAs demonstrated enhanced current densities, achieving up to 0.6 A·cm⁻² at room temperature with further increases to 1 A·cm⁻² at elevated temperatures. These results corroborated the single-cell data, highlighting potential improvements in system efficiency and a reduction in adverse effects. The work underscores the potential of HT-PEMFC-based GDEs for the integration of MEAs applicable to advanced hydrogen compression technologies. Full article