International Journal of Mechanical and Materials Engineering最新文献

This study explores the optical properties of polyethylene oxide (PEO) modified with natural dye extracted from hollyhock (HH) flowers. This study is a green chemistry approach to reduce the optical band gap of PEO polymer. The UV-vis analysis of the HH dye demonstrated absorption spanning from UV to visible regions of the electromagnetic spectrum. Fourier transform infrared spectroscopy (FTIR) analysis identified significant transmittance bands linked to the OH, NH, and C = O functional groups of HH dye. The shifts and intensity changes in FTIR bands of the doped PEO indicate interactions between PEO and HH dye functional groups. A shift was observed in the absorption edge from 5.6 eV for clean PEO to 2.6 eV for dye-doped film. The addition of HH dye resulted in an increase in the optical dielectric constant, suggesting a rise in the localized density of energy states within the forbidden band separating the valence bands (VBs) and conduction bands (CBs). The refractive index of doped PEO was found to be 1.73 which is greater than that of pure PEO (1.27). The optical band gap determination based on Tauc’s model was found to decrease from 5.3 eV for pure PEO to 2.4 eV for dye-doped PEO film. The study identified the dominant type of electron transition, a complex topic in condensed matter physics involving electrons crossing the band gap.

Additive manufacturing (AM), commonly known as 3D printing, has revolutionized the manufacturing landscape by enabling layer-by-layer fabrication of complex geometries from digital models. This paper provides a comprehensive overview of the evolution, current capabilities, and future directions of AM. Beginning with the historical rise of AM, it explores and compares its major technological categories, including material extrusion, vat photopolymerization, powder bed fusion, and directed energy deposition. Each technology is discussed with regard to standard classifications and operational mechanisms. It further examines the crucial role of material properties and selection, emphasizing how polymers, metals, ceramics, and composites influence mechanical performance and application suitability. The paper investigates the deployment of AM across industries such as aerospace, biomedical, automotive, construction, and consumer goods, highlighting transformative applications. Despite its benefits, AM faces challenges such as anisotropic mechanical properties, limited material diversity, high energy consumption, and scalability constraints. Recent advancements leveraging machine learning (ML) or (AI) integration are discussed, particularly in process monitoring, defect prediction, and print quality optimization. ML-integrated process optimization techniques are shown to enhance part performance and production efficiency. Additionally, this study compares AM with subtractive manufacturing (SM), focusing on material utilization, energy efficiency, and production flexibility. A life cycle assessment (LCA) is conducted to evaluate the environmental and economic impacts of AM technologies. Market analysis indicates substantial global growth of the AM industry, fueled by technological maturation and increasing demand for customized solutions. Finally, it projects future research directions, including the development of multi-material printing, integration of AI-driven adaptive systems, sustainable material innovations, and the role of AM in decentralized manufacturing. This holistic analysis affirms AM’s pivotal role in reshaping the future of manufacturing with enhanced sustainability, precision, and design freedom. Overall, this review offers a big-picture view of AM where it stands today and how it’s paving the way for a more innovative, sustainable, and flexible future in manufacturing.

1xxx-series aluminum alloys are widely utilized in heat exchangers. During brazing, heat exchanger components are exposed to a short period of high temperature, which may trigger recrystallization and abnormal grain growth, ultimately compromising their mechanical properties. This study investigates the impact of Sc and Zr microalloying on the microstructure stability of hot deformed 1xxx alloys subjected to post-deformation annealing from 500 to 575 °C for 1 h to simulate brazing-type processes. Four alloys were studied: namely 1xxx base, Al-0.07Sc, Al-0.07Sc-0.10Zr and Al-0.19Sc-0.15Zr alloys. Annealing at 500 °C led to complete recrystallization in the base alloy, while higher annealing temperatures promoted abnormal grain growth. The Al-0.07Sc alloy resisted recrystallization at 500 °C but was fully recrystallized by 550 °C. In contrast, the Al-0.07Sc-0.10Zr alloy retained its grain stability up to 550 °C owing to the presence of stable Al₃(Sc,Zr) precipitates; however, partial recrystallization occurred at 575 °C. The Al-0.19Sc-0.15Zr alloy preserved most of deformed microstructure even after annealing at 575 °C. It showed the highest recrystallization resistance among the four alloys studied owing to its highest number density and finest size of Al₃(Sc,Zr) precipitates, which suggests that this alloy can be applied in even more extreme conditions including brazing temperatures above 575 °C.

This study focused on the synthesis of zinc oxide (ZnO) phytonanoparticles (PNPs) using Bonellia macrocarpa root extract and the evaluation of their cytotoxic activity in three cancer cell lines and the non-tumor control HaCaT cells. The PNPs were characterized using UV–Vis spectrophotometry, Fourier-transform infrared spectroscopy (FT-IR), particle analyzer, and scanning electron microscopy (SEM). The cytotoxic activity of ZnO PNPs was evaluated in the breast cancer cell lines MDA-MB-468, MDA-MB-231, and MCF-7. The results demonstrated a significant antiproliferative effect, particularly in the MDA-MB-468 cell line with an IC₅₀ of 34 ppm, along with increased selectivity for this cell line compared to the crude extract and the reference drug, doxorubicin. Furthermore, the PNPs also reduced both the formation and size of tumor cell colonies and suppressed cell migration in the MDA-MB-468 line. These effects indicate a significant impact on the growth and spread of cancer cells. Moreover, PNPs successfully internalized into the cancer cells and induced a significantly higher overproduction of reactive oxygen species (ROS) compared to doxorubicin and the crude extract from B. macrocarpa roots. Finally, PNPs were observed to induce apoptosis in MDA-MB-468 cells, suggesting activation of programmed cell death pathways. The synthesis of PNPs offers an alternative for obtaining nanoscale structures with significant potential to reduce the progression of breast cancer. This approach may complement and enhance existing therapies for this disease.

Neuropathic pain is chronic pain caused by damage or dysfunction of the nervous system. Pro-inflammatory factors and abnormal reactive oxygen species (ROS) production in the spinal cord play a key role in the occurrence and development of neuropathic pain. Current treatments for neuropathic pain have limited efficacy. In this study, we prepared a nano-enzyme functionalized and magnetically targeted cerium oxide multidrug system (FMCCC), which was able to be coated by microglial BV2 cells and effectively inhibited LPS-induced microglial inflammation, which resulted in the increase of inflammatory factors, oxidative stress, and reactive oxygen species (ROS) production. In a mouse model of chronic compression injury of the sciatic nerve, FMCCC significantly improved mechanical hyperalgesia, inhibited inflammatory factors and oxidative stress, and eliminated ROS. In summary, FMCCC can relieve neuropathic pain by promoting magnetic targeting to the nerve compression site, releasing neurotherapeutic drugs Cur and peptides, and eliminating ROS, oxidative stress, and inflammatory factors, which provides a new idea for the treatment of neuropathic pain.

The objective of this research is to enhance the mechanical characteristics of aluminum alloy welds by adjusting tungsten inert as (TIG) welding parameters. Different welding parameters, such as current (150, 170, and 190 amps), gas flow rate (10, 11, and 12 l/min), and filler rod diameter (1.6, 2.0, and 2.4 mm), were systematically analyzed using the TOPSIS technique used in industries like aerospace, automotive, and construction, where precise welding control ensures aluminum alloy reliability and performance. It engages in multiparameter optimization which systematically ranks welding parameters, helping identify key factors that enhance weld quality. The response parameters selected were ultimate tensile strength (UTS), Vickers hardness, and percentage of elongation. A total of 31 microhardness readings were obtained to assess hardness distribution across the welded joints. Analysis of the results indicated that the filler rod diameter significantly influenced all response parameters. Specifically, it had the highest impact on UTS, elongation, and hardness, with contribution percentages of 48.4%, 52.6%, and 51.41%, respectively. The gas flow rate and welding current also affected these properties but to a lesser extent. ANOVA results showed that the filler rod diameter was the most critical factor, with high F-values and low P-values for each response parameter. The study concludes that optimizing filler rod diameter can substantially improve weld quality, making it the most influential parameter in achieving desired mechanical properties in TIG welding of aluminum alloys.

The temperature uniformity of grain-oriented silicon steel coils during high-temperature annealing in bell-type furnaces critically influences the post-annealing product performance. In this study, experimental measurements of temperature values at representative points within the steel coil were combined with simulations to systematically investigate the temperature field distribution under different heating rates. The results indicate that the current heating scheme leads to a significant temperature difference between the inner ring and the peripheral area of the steel coil. To reduce this temperature difference, targeted optimization schemes have been developed to minimize the temperature differential between the coldest and hottest areas without compromising production efficiency. These optimizations aim to achieve a more uniform temperature distribution, thereby enhancing the overall performance of the final product.

Herein, we describe the preparation of poly(tetrafluoroethylene) (PTFE) materials, including a PTFE-coated magnetic stir bar and a PTFE vial, for the recycling of catalysts at the molar ppm level. Metal nanoparticles were consistently deposited onto the PTFE surface using straightforward and conventional techniques for nanoparticle formation. These metal nanoparticles deposits proved resistant to removal by simple washing methods. Upon reducing Pd(OAc)₂ with 4-methylphenylboronic acid in a 1.5 mol/L aqueous KOH solution at 90 °C for 1 h, nanoparticles approximately 100 nm in size, along with larger aggregates, were observed via SEM analysis of the PTFE-coated magnetic stir bar (8.0 mm × 1.5 mm). The reusability of the Pd nanoparticles-immobilized stir bar was suboptimal in Hiyama and Suzuki coupling reactions. However, the stir bar on which metal nanoparticles were sequentially deposited (Pd, Rh, and Pd) exhibited high recyclability over ten consecutive runs. Additionally, the PTFE vial, upon deposition of both Pd and Rh, was employed as a highly recyclable catalyst.

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Regarding nitrogen doping of TiO₂, there is now more information in the literature that points to the development of more photosensitive materials for photocatalytic applications. To develop better photocatalysts, pure and nitrogen-doped TiO₂ (TiO₂:N) nanoparticles have been synthesized and widely studied. First, the bandgap value of both semiconductors was determined, finding that doping with N atoms decreases the bandgap value relative to the pure material, allowing the doped semiconductor to be excited with visible light below 403 nm. An important property of N-doped TiO₂ is that it has on average a smaller crystal size (15.2 nm) and a greater BET surface area (79.6 m²/g) than the commercial photocatalyst Degussa P-25 (23 nm and 48.6 m²/g, respectively), a fact that influences having a greater availability of active sites as a photocatalyst. Doping of TiO₂ with N caused the (101) and (200) diffraction peaks to shift towards higher 2 (theta) values, which led to a slight decrease in the interplanar distances d₁₀₁ and d₂₀₀. After that, combining the experimental results obtained in this work and others already reported in the literature, it was possible to conclude N doping was achieved through a substitutional incorporation of N into the TiO₂ crystal structure rather than through an interstitial location. As an application of TiO₂ and TiO₂:N as photocatalysts, the treatment of the analgesic acetaminophen (ACT) in the aqueous phase was carried out by heterogeneous photocatalysis in a photocatalytic reactor using concentrated solar radiation. In comparison, the same degradation experiments were carried out but using the commercial photocatalyst Degussa P-25. The degradation percentages were as follows: the best were obtained with the TiO₂:N nanoparticles (90 and 95%), followed by pure TiO₂ (83 and 91%), and finally, those obtained with the Degussa P-25 photocatalyst (80 and 83%), all of them characterized by their COD and TOC, respectively.

Bio-additives, generally composed of alcohol or esters, are sustainable substances added to fuels to enhance their properties and reduce CO₂ emissions. In Mexico, there is a lack of regulations on bio-additive-gasoline mixture composition and effects this composition on the mechanical properties of the tanks is not clear. This study investigates the impact of the quantity of a bio-additive added to gasoline on metallic automotive and motorcycle tanks. Two experimental setups were developed: immersion tests in gasoline-bio-additive mixtures at varying concentrations of a sheet of automotive tanks, and exposure of motorcycle metallic tanks to ambient pressure–temperature conditions over 14 months. Corrosion signs and sediment accumulation appeared within 2 weeks, particularly in the 30% bio-additive mixture, pointing to compatibility issues. Characterization methods, including Raman spectroscopy, gas chromatography-mass spectrometry (GC–MS), Electron microscopy (SEM/EDS), and metallography, revealed methanol in the bio-additive composition. Methanol increases corrosion of the automotive sheets, also, it causes the removal of lead from the anticorrosion coating that covers the motorcycle tanks. This results, emphasize the compatibility challenges between bio-additives and all components of the metallic tanks.