International Journal of Mechanical and Materials Engineering最新文献

The bleaching properties of locally acid-activated Anfoega kaolin clays have been studied to investigate their applicability as a substitute for the expensive imported acid-activated bleaching clays used in vegetable oil refinery industries in Ghana. The clay was characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrophotometer, and scanning electron microscopy (SEM). The bleaching properties of the clay were investigated by varying the clay dosage, acid concentration, and bleaching temperature. Activation of the Anfoega kaolin clay at 100 °C and 2.5 h with constant stirring was found to be optimum conditions of temperature and contact time, respectively. The clay/acid ratio was found not to significantly affect the clay properties. Palm oil was used to investigate the bleaching performance of the activated clay samples. When the oil was bleached at 90 °C for 30 min using 10% wt/vol of oil, clay activated with 2 mol/L H₂SO₄, the bleaching performance obtained was up to 94.54%. Response surface plot methodology revealed that the optimal bleaching conditions were achieved with a clay dosage of 10 g, a temperature range of 70 to 120 °C, and a bleaching duration of 60 min resulting in a bleaching efficiency of 81%.

Marine corrosion is a critical subject that holds substantial importance from multiple perspectives, including engineering design, structural safety, and economic sustainability. The harsh marine environment presents unique challenges, as the interaction between steel structures and corrosive elements can lead to significant degradation over time, impacting the performance, reliability, and longevity of critical infrastructure. Understanding the mechanisms and effects of marine corrosion is essential for optimizing design strategies, ensuring safety, and reducing unnecessary costs associated with over-engineering or premature failures. This study seeks to contribute to this understanding by comprehensively reviewing and synthesizing the current body of knowledge available in the literature. It examines the key factors influencing corrosion in marine environments, such as salinity, temperature, and biofouling, and explores their specific effects on steel structures commonly used in marine applications. Additionally, the study highlights the importance of field monitoring techniques, providing an overview of methodologies used to observe and measure corrosion rates in real-world conditions. These techniques are crucial for capturing the dynamic and complex nature of marine corrosion processes and for developing realistic models to predict long-term impacts.

This study explores the synthesis of SiO₂ nanoparticles using Agave distillate as a natural capping, reducing, and stabilizing agent and investigates their application in methylene blue (MB) dye removal from water. The synthesized nanoparticles demonstrated significant adsorption of MB without the need for UV light, highlighting their suitability for sustainable water treatment. Structural characterization through X-ray diffraction (XRD) confirmed an amorphous silica structure, with a peak at 2θ = 24°, consistent with high-purity SiO₂. Transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) further verified the nanoparticles’ morphology and purity, showing only silicon and oxygen elements. Adsorption tests revealed an increase in MB adsorption efficiency with higher SiO₂ dosages: 10 mg, 50 mg, and 100 mg of nanoparticles resulted in 28%, 49%, and 86% adsorption within 5 min, respectively. This efficiency is largely due to the electrostatic attraction between the negatively charged SiO₂ surface and the cationic MB molecules, facilitating adsorption and subsequent adsorption. By using Agave distillate in the synthesis process, this approach avoids hazardous chemicals, supporting eco-friendly practices. The findings underscore the potential of SiO₂ nanoparticles for sustainable water treatment applications that are both effective and environmentally benign.

This study examines the electrochemical performance of nickel-modified glassy carbon electrodes (GCEs) deposited from ionic liquid, typically ethaline, (Ni_IL/GC) and aqueous solutions (Ni_AQ/GC) for glucose oxidation. SEM analysis shows a fine-grained, nanostructured morphology with microcracks in the ionic liquid-deposited film. EDX confirms high nickel content (44.6%) and surface oxidation (6.8%). XRD indicates face-centered cubic nickel and nickel oxides with an average nanoparticle size of 33 nm. Cyclic voltammetry reveals Ni_IL/GC exhibits superior electron transfer and catalytic activity towards glucose oxidation, with sharper oxidation peaks and a 100 mV cathodic shift compared to Ni_AQ/GC. Nyquist plots show lower impedance for Ni_IL/GC, signifying improved charge transfer efficiency. Tafel analysis shows a lower slope (30 mV/decade) for Ni_IL/GC, indicating faster glucose oxidation kinetics. The Ni_IL/GC electrode also demonstrates superior stability with minimal degradation during long-term cycling. These results highlight Ni_IL/GC’s enhanced electrochemical properties and stability, making it promising for glucose sensing and electrocatalytic applications.

Fibre production can be conducted using a variety of techniques, including electrospinning and electroblowing. These techniques require strict control of different parameters, such as the voltage, presence of fillers, viscosity, and airflow rate (for electroblowing). At the end of the process, fibres with different morphologies are obtained. Poly-1,1-difluoroethene (PVDF) is a polymer with excellent potential for fibre applications due to its properties, including good piezoelectricity, biocompatibility, and pyroelectricity. These attributes make PVDF suitable for biomedical applications. Other applications include conventional and hybrid nanogenerators, sensors, and potentially future green energy sources. To achieve a high production rate of fibres, parameter control must be sufficient to obtain fibres with the required characteristics at the spinning process. In this study, Ca(NO₃)₂·4H₂O and triethyl phosphate (TEP) were used as precursors at the hydroxyapatite (HAp) production within a polymeric solution to increase the PVDF fibre production rate and change morphology. The analysis techniques of X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy mechanical tensile test, and viscosity analysis were employed to observe the effect of the HAp precursor solution on the fibre’s final properties. The addition of 5% and 10% of the solution containing these two precursors dissolved in ethanol (EtOH) increased the fibre diameter from 0.2 µm (without precursors) to 1.1 µm (5% of precursors) and 1.6 µm (10% of precursors). Additionally, the distribution of fibres on the collector became more uniform, suggesting a change in the fibre's electrical charge. These results demonstrate improved control of PVDF fibre production using a solution tailored for biomaterial purposes.

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The electrochemical reduction of carbon dioxide (CO₂R) into value-added products represents a promising approach for mitigating greenhouse gas emissions. However, the substantial overpotential required for CO₂ reduction constrains its practical applications. In this study, we present a novel catalyst comprising silver nanoparticles (AgNPs) anchored on cysteamine-functionalized reduced graphene oxide aerogel (rGOA/AgNPs) to enhance CO₂R in aqueous solutions. Cysteamine acts as a pivotal linker, covalently attaching AgNPs to rGOA through its thiol group, thereby improving catalyst stability and facilitating the formation of the *COOH intermediate, as corroborated by density functional theory (DFT) calculations. The high surface area of rGOA (51.43 m² g⁻¹) and its mesoporous structure significantly enhance CO₂ adsorption, while cysteamine fortifies the chemisorption of intermediates. These findings elucidate the synergistic effect of cysteamine-anchored AgNPs and rGOA, establishing an efficient electrocatalyst for sustainable CO₂ conversion. Cyclic voltammetry demonstrates that rGOA/AgNPs can reduce CO₂ to CO at -0.43 V (pH 7) and -1.29 V (pH 3) relative to Ag/AgCl/KCl(sat'd). In contrast, CO₂ reduction is not observed on the surfaces of Ag, AgNPs, or rGO electrodes within the tested potential range. Furthermore, calculations suggest a two-electron transfer process (n = 2), indicating a high selectivity for CO production.

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In this study, the wear properties of three different composite formulations (T1, T2, and T3), which are highly important for aeronautical applications, are examined. The structural approach from Taguchi (L27 experimental design) is employed. To analyze the critical performance parameters, cf, such as specific wear rate (SWR) and frictional force (Ff), the Taguchi Signal-to-noise ratio approach is used. The input variables compound, applied load, rotating Speed, and sliding distance reveal significant correlations between the observed results. The optimal parameter combination of 5% composition, 15 N applied force, 160 rpm rotating Speed, and 41 M Sliding distance Showed subtle interactions that enhanced the wear resistance of the composite materials. The application of ANN-based predictions in this Study achieved an impressive accuracy of 99.72% in correlating predicted results with actual testing outcomes. This achievement facilitates the swift refinement of composite materials to meet the demanding standards of aerospace applications. This research plays a significant role in improving wear analysis and prediction methods while also fostering the development of specialized composites that offer enhanced reliability, performance, and durability for aeronautical purposes.

The development of biosynthesized and cost-efficient nanomedicine is a promising strategy in cancer therapeutics. Herein, we have synthesized highly potent silver nanoparticles (AgNPs) using methanolic and ethanolic extracts of Citrus medica fruit, unraveling the significance of different solvents. Fourier transform infrared spectroscopy confirmed the occurrence of secondary metabolites on the synthesized AgNPs’ surface. The Zetasizer analysis showed no significant particle-size differences between both solvents-based-synthesized AgNPs; however, zeta potential showed significant differences in the particle surface charge. The high-resolution transmission electron microscopy confirmed a predominantly spherical morphology of AgNPs. Notably, AgNPs synthesized from ethanolic extracts exhibited smaller sizes (5–7 nm) and a more uniform distribution compared to their methanolic counterparts. The X-ray diffraction demonstrated a polycrystalline nature with a face-centered cubic structure. Functional assays showed a significant increase in the anticancer efficacy of ethanolic extract-derived AgNPs against the breast cancer cells (MCF-7 and MDA-MB-231), accompanied by extensive DNA fragmentation and enhanced induction of apoptosis. Mechanistically, both methanolic and ethanolic AgNPs induce upregulation of pro-apoptotic gene expression (e.g., TP53, BAX, and CYCS) and downregulation of anti-apoptotic gene (e.g., BCL2). The flow cytometry analysis showed a substantial increase of the ethanolic extract-based AgNPs in the late-stage apoptotic cells, which was further confirmed by morphological changes in treated MCF-7 cells. This study reveals the pivotal influence of the selection of solvent on the synthesis and anticancer potency of AgNPs, significantly impacting their ability to induce apoptosis in MCF-7 cells. Our findings introduce a novel strategy for optimizing green-synthesized AgNPs-based therapies, offering promising avenues for advancing nanoparticle-driven cancer treatments and potentially transforming future therapeutic approaches in oncology.

Graphical Abstract

Schematic representation of AgNPs synthesized from methanolic or ethanolic extract of Citrus medica fruit and evaluations of their anticancer efficacy against MCF-7 cell lines.

The non-magnetic semiconducting GeO₂ monolayer is a potential candidate for gas sensing and hydrogen storage applications due to its large surface-to-volume ratio compared to the bulk materials and changing band gap for the adsorption of hydrogen molecules. In this work, the interaction of hydrogen molecule (H₂) with GeO₂ monolayer has been investigated using van der Waals density functional theory (vdW-DFT); the adsorption and surface diffusion energies of H₂ molecule have been calculated at different adsorption positions on the GeO₂ monolayer by applying revPBE-vdW functional. It has also been found that repulsion between two nearby H₂ molecules limits, how many H₂ molecules can fit inside one-unit cell of GeO₂ monolayer. The time evolution of the surface coverage, the number of adsorptions, diffusions, and desorption have been calculated by the Kinetic Monte Carlo (KMC) simulation code. To clarify the nature of the adsorption behaviour, Bader charge analysis, electron localization function (ELF), density of states (DOS) and band structure properties have been scrutinized.

This study presents a comprehensive evaluation of sustainable turning of AISI 316L stainless steel using Minimum Quantity Lubrication (MQL) with an eco-friendly castor oil-based nanofluid containing 0.5 wt% Al₂O₃ nanoparticles with an average size of 30 nm. The effects of cutting speed (164–370 m/min), depth of cut (0.25–0.75 mm), and lubrication method (dry, conventional soluble oil, and nanofluid) on surface roughness were analyzed using a Taguchi L9 orthogonal array. The optimal parameters 370 m/min speed, 0.5 mm depth, and nanofluid achieved a minimum surface roughness (Ra) of 0.532 µm. ANOVA revealed coolant type as the most influential factor, contributing 60.57% to surface quality variance. Novelty lies in the integration of a biodegradable Al₂O₃-castor oil nanofluid with finite element modelling and its application to AISI 316L, a widely used biomedical alloy. DEFORM-3D simulations validated experimental trends, with predicted cutting forces and tool-chip interface temperatures deviating by less than 8% from measured values, confirming strong correlation. This dual approach underscores the nanofluid’s superior tribological performance and affirms its role as a green alternative for high-precision, low-carbon machining aligned with Industry 4.0 goals.