Search Results (100)

S355NL structural steel is extensively employed in bridges, ships, and power station equipment owing to its excellent tensile strength, weldability, and low-temperature toughness. However, pronounced fluctuations in its Charpy impact energy at low temperatures significantly compromise the reliability and service life of critical components. In this study, vacuum-induction-melted ingots of S355NL steel containing 0–0.086 wt.% rare earth cerium were prepared. The effects of Ce on microstructures, inclusions, and impact toughness were systematically investigated using optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and Charpy V-notch testing. The results indicate that appropriate Ce additions (0.0011–0.0049 wt.%) refine the average grain size from 5.27 μm to 4.88 μm, reduce the pearlite interlamellar spacing from 204 nm to 169 nm, and promote the transformation of large-size Al₂O₃-MnS composite inclusions into fine, spherical, Ce-rich oxysulfides. Charpy V-notch tests at –50 °C reveal that 0.0011 wt.% Ce enhances both longitudinal (269.7 J) and transverse (257.4 J) absorbed energies while minimizing anisotropy (E_t/E_l  =  1.01). Conversely, excessive Ce addition (0.086 wt.%) leads to coarse inclusions and deteriorates impact performance. These findings establish an optimal Ce window (0.0011–0.0049 wt.%) for microstructural and inclusion engineering to enhance the low-temperature impact toughness of S355NL steel. Full article

Progressive research on reducing engine emissions is highly valued due to the emissions’ significant environmental and health impacts. This comprehensive comparative study examines the catalytic efficiency of manganese (Mn) and cerium silica (Ce-Si) synthesis catalyst-based molds in a diesel engine using a selective catalytic reduction (SCR) technique with diesel and diesel–plastic oil blend (DPB) (B50). In addition to Fourier transform infrared spectroscopy (FTIR) studies, X-ray diffraction (XRD), scanning electron microscopy (SEM), and the Brunauer–Emmett–Teller (BET) method are utilized to characterize the produced molds before and after exhaust gas passes. The Ce-Si-based mold demonstrates superior redox capacity, better adsorption capacity, and better thermal stability, attributed to enhanced oxygen storage and structural integrity compared to the Mn-based mold. Under minimum load conditions, nitrogen oxide (NO) reduction efficiency peaks at 80.70% for the Ce-Si-based mold in the SCR treatment with DPB fuel. Additionally, significant reductions of 86.84%, 65.75%, and 88.88% in hydrocarbon (HC), carbon monoxide (CO), and smoke emissions, respectively, are achieved in the SCR treatment under optimized conditions. Despite a wide temperature range, Ce-Si-based mold promotes high surface area and superior gas diffusion properties. Overall, the Ce-Si-based mold provides efficient emission control in diesel engines, which paves a path for developing better environmental sustainability. The outcomes contribute to advancing environmental sustainability by supporting the achievement of SDGs 7, 11, and 13. Full article

Wound healing is a complex biological process that benefits from advanced biomaterials capable of modulating inflammation and promoting tissue regeneration. In this study, cerium oxide nanoparticles (CeO₂NPs) were green-synthesized using Hemerocallis citrina extract, which served as both a reducing and stabilizing agent. The CeO₂NPs exhibited a spherical morphology, a face-centered cubic crystalline structure, and an average size of 9.39 nm, as confirmed by UV-Vis spectroscopy, FTIR, XRD, and TEM analyses. These nanoparticles demonstrated no cytotoxicity and promoted fibroblast migration, while significantly suppressing the production of inflammatory mediators (TNF-α, IL-6, iNOS, NO, and ROS) in LPS-stimulated RAW264.7 macrophages. Gene expression analysis indicated M2 macrophage polarization, with upregulation of Arg-1, IL-10, IL-4, and TGF-β. Aligned polycaprolactone/polylactic acid (PCL/PLA) nanofibers embedded with CeO₂NPs were fabricated using electrospinning. The composite nanofibers exhibited desirable physicochemical properties, including porosity, mechanical strength, swelling behavior, and sustained cerium ions release. In a rat full-thickness wound model, the CeO₂ nanofiber-treated group showed a 22% enhancement in wound closure compared to the control on day 11. Histological evaluation revealed reduced inflammation, enhanced granulation tissue, neovascularization, and increased collagen deposition. These results highlight the therapeutic potential of CeO₂-incorporated nanofiber scaffolds for accelerated wound repair and inflammation modulation. Full article

The luminescent properties of cerium-doped barium aluminate (BaAl₂O₄) samples with varying Ce concentrations (0–1.1 mol%) prepared either in an air or nitrogen-reduced atmosphere are presented. This work provides the first detailed comparison of the material’s structural, luminescent, and chromatic properties at different doping levels and thermal treatments. X-ray diffraction analysis confirmed the hexagonal crystal structure of barium aluminate. Samples treated in an air atmosphere exhibited crystallite sizes of 58.5 nm for undoped samples and 45.7 nm for doped samples. In contrast, those treated under nitrogen showed smaller crystallite sizes, i.e., 39.8 nm for undoped and 42.3 nm for doped samples, respectively. XPS analysis indicated that the nitrogen-reduced atmosphere minimized Ce oxidation, favoring the presence of Ce³⁺. The bandgap values of the material were 4.0 eV and 5.6 eV for the air and for the nitrogen atmosphere, respectively. Photoluminescence spectra showed maxima at 357 nm (air) and 386 nm (nitrogen), attributed to 4f-5d transitions of Ce. The samples under air atmosphere showed longer lifetimes values (0.94 ns) compared to those in a nitrogen atmosphere (0.40 ns). These results suggest that thermal treatment in an air atmosphere promoted better structural order and higher photoluminescence efficiency, while treatment in a nitrogen-reduced atmosphere increased defect formation, shortening the lifetime. Chromaticity coordinate analysis showed that the cerium ion dopant influenced the blueish emission color in both samples. Full article

Delayed or non-healing of bone defects in an aging, multi-morbid population is still a medical challenge. Current replacement materials, like autografts, are limited. Thus, artificial substitutes from biodegradable polymers and bioactive glasses (BGs) are promising alternatives. Here, novel cerium-doped mesoporous BG microparticles (Ce-MBGs) with different cerium content were included in photocrosslinkable, methacrylated gelatin (GelMA) for promoting cellular functions of human mesenchymal stem cells (hBMSCs). The composites were studied for intrinsic morphology and Ce-MBGs distribution by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). They were gravimetrically analyzed for swelling and stability, compressive modulus via Microsquisher^® and bioactivity by Fluitest^® calcium assay and inductively coupled plasma-optical emission spectrometry (ICP-OES), also determining silicon and cerium ion release. Finally, seeding, proliferation, and differentiation of hBMSCs was investigated. Ce-MBGs were evenly distributed within composites. The latter displayed a concentration-dependent but cerium-independent decrease in swelling, while mechanical properties were comparable. A MBG type-dependent bioactivity was shown, while an enhanced osteogenic differentiation of hBMSCs was achieved for Ce-MBG-composites and related to different ion release profiles. These findings show their strong potential in promoting bone regeneration. Still, future work is required, e.g., analyzing the expression of osteogenic genes, providing further evidence for the composites’ osteogenic effect. Full article

The present study focuses on investigating the evolution of phase transformations in the Mg-Ni-Ce system under the influence of mechanical synthesis (MS) and spark plasma sintering (SPS). Magnesium powder mixtures with different nickel and cerium contents (Mg-3%Ni-2%Ce, Mg-7%Ni-3%Ce, and Mg-10%Ni-5%Ce) were mechanically activated along with various grinding parameters. The X-ray phase analysis (XRD) has shown the successive stages of the phase formation in the MS process: from the initial components to the formation of intermetallic compounds of Mg₂Ni, Mg₁₂Ni₆, and CeMg₃. An increase in the intensity of mechanical treatment facilitated the accelerated destruction of the crystal lattice, the generation of defects, and the formation of new phases, as evidenced by the broadening and reduction in the intensity of Mg diffraction peaks. The subsequent SPS stage promoted the completion of phase transformations, structural stabilization, and the formation of a dense, multicomponent microstructure with a uniform distribution of intermetallic compounds. The observed average crystallite sizes ranged from 20 to 70 nm, depending on the processing conditions. The research results demonstrate the possibility of targeted control over the phase composition, opening new opportunities for the development of highly efficient hydrogen-absorbing alloys. Full article

In this study, a statistical analysis of results reported in the literature was conducted through a 2ⁿ experimental design on the synthesis of bifunctional catalysts used in the production of lighter fuels, aiming for optimization while considering factors such as support (bentonite and vermiculite), acidity modifier (zirconium and cerium), metal (tungsten and molybdenum), metal content (5% and 10%), promoter (nickel and cobalt), and heteropolyacids (tungstophosphoric acid and molybdophosphoric acid), identifying their influence on textural properties and catalytic performance. Regarding the textural properties, vermiculite proved to be the most favorable support due to its high porosity. It was also established that the implemented metals impart positive characteristics to the catalysts due to their various properties; however, incorporating large amounts led to an adverse effect by clogging the pores. Catalytic performance was analyzed in isomerization and cracking reactions, which were enhanced by the use of cerium due to the presence of Brønsted acid sites and molybdenum for its stability. In this way, the statistical analysis conducted in this study was crucial for identifying the influence of key factors on the textural properties and catalytic performance of bifunctional catalysts. Using a 2ⁿ experimental design allowed for a systematic evaluation of variables reported in the literature, such as support, acidity modifiers, metals, metal content, promoters, and heteropolyacids. Full article

A low-grade uranium-gold polymetallic ore is associated with many rare elements, such as beryllium (Be), zirconium (Zr), thorium (Th), and cerium (Ce). It has potential development and utilization value. In order to improve the development and utilization rate of a low-grade uranium-gold polymetallic ore, beryllium (Be) in low-grade uranium-gold polymetallic ore was extracted by a combined method of (NH)₂SO₄ and Al₂(SO₄)₃. The effects of different concentrations of (NH₄)₂SO₄ solution on the leaching of beryllium (Be) in low-grade uranium-gold polymetallic ore with different particle sizes after sieving were studied; microstructure and physicochemical analyses were carried out. The leaching mechanism of beryllium (Be) was revealed. The experimental results showed that when the low-grade uranium-gold polymetallic ore in (NH)₂SO₄ solution is 6 g/L and Al₂(SO₄)₃ is 3 g/L, the particle size of the ore sample is 0.01 mm, the concentration of beryllium (Be) in the leaching solution reaches 0.521 mg/L after 3 days of leaching, the concentration of beryllium (Be) in the leaching solution of the sample without Al₂(SO₄)₃ solution is 0.007 mg/L, and the leaching rate of beryllium (Be) reaches 98.6%. SEM and XRD analyses showed that the silicate composition in the sample after leaching was obviously destroyed compared with the control group when the (NH)₂SO₄ solution was 6 g/L, which increased the contact area on the surface of the ore sample and promoted the leaching of beryllium (Be) in the uranium ore sample. The research results lay a theoretical foundation for the development and extraction of beryllium (Be) associated with low-grade uranium-gold polymetallic ore. Full article

To enhance the mechanical characteristics and corrosion resistance of bridge steel, three distinct groups of test steels with varying Ce contents were formulated. The objective was to investigate the influence of rare earth Ce on the microstructure, impact performance, and corrosion resistance of bridge steel. The addition of rare earth elements improves both the impact performance and the corrosion resistance of bridge steels. The present research systematically examines the impact of cerium (Ce) incorporation on the structural and impact performance of bridge construction steels, with particular emphasis on elucidating the fundamental mechanisms governing these modifications. This investigation establishes a comprehensive theoretical framework that facilitates the advancement of next-generation rare earth-enhanced high-performance steel alloys specifically designed for bridge engineering applications. The investigation reveals that rare-earth elements exert a significant influence on microstructural refinement, leading to the diminution of grain size. Additionally, these elements catalyze the modification of inclusion morphology in the test steel, transitioning from an irregular form to a spherical one, with a concomitant decrease in inclusion size. The tested steel with a rare earth mass fraction of 0.0025 wt.% has the best impact performance and the lowest corrosion rate. The impact performance improved by 7.37% compared with the experimental steel without the addition of rare earth elements. The incorporation of rare earth elements has been observed to promote the accumulation of Cu in the rust layer, which contributes to the improved stability of the layer. Concurrently, it has been noted that, for equivalent periods of corrosion exposure, there is a positive correlation between the arc radius of bulk resistance and the incremental levels of rare earth Ce. Full article

High-strength low-alloy (HSLA) steels have garnered significant attention owing to their widespread applications across various industries, with weldability being a particularly critical aspect. However, the impact toughness of the coarse-grained heat-affected zone (CGHAZ) remains a notable challenge under high-heat-input welding conditions. Despite existing research acknowledging the beneficial effects of micro-alloying elements on steel properties, there are still numerous uncertainties and controversies regarding the specific influence of these elements on the microstructure and impact toughness of the CGHAZ under specific welding conditions. To address this issue, this study presents a comprehensive review of the impact of common micro-alloying elements on the microstructure and toughness of the CGHAZ during high-heat-input welding. The results indicate that elements such as cerium, magnesium, titanium, vanadium, nitrogen, and boron significantly improve the toughness of the CGHAZ by promoting intragranular nucleation of acicular ferrite and inhibiting the coarsening of austenite grains. In contrast, the addition of elements such as aluminum and niobium adversely affect the toughness of the CGHAZ. These findings offer crucial theoretical guidance and experimental evidence for further optimizing the welding performance of HSLA steels and enhancing the impact toughness of the CGHAZ. Full article

Cerium-doped hexagonal lamellar hydrotalcite was prepared via the hydrothermal method and applied to epoxy resin (EP) composites. The characterization results of cerium-doped hydrotalcite showed that the interlayer spacing of hydrotalcite increased with an increase in the cerium doping amount, and an appropriate amount of cerium doping will not destroy the layered structure of hydrotalcite. This study also determined the best cerium doping ratio. The combustion performance of the composite was studied using thermogravimetric infrared analysis, smoke density test, and limiting oxygen index (LOI). The results showed that the addition of cerium-doped hydrotalcite reduced the amount of smoke and the escape of hydrocarbons during the combustion and decomposition of epoxy resin. The main flame-retardant mechanism was that the addition of cerium-doped Mg-Al hydrotalcite promoted the formation of a dense protective layer on the surface of the composite to inhibit the escape of combustible substances, so as to achieve the purpose of a flame retardant and smoke suppression. Full article

Each year, the number of cases of strokes and deaths due to this is increasing around the world. This could be due to work stress, lifestyles, unhealthy food habits, and several other reasons. Currently, there are several traditional methods like thrombolysis and mechanical thrombectomy for managing strokes. The current approach has several limitations, like delayed diagnosis, limited therapeutic delivery, and risks of secondary injuries. So, there is a need for some effective and reliable methods for the management of strokes, which could help in early diagnosis followed by the treatment of strokes. Nanotechnology has played an immense role in managing strokes, and recently, it has emerged as a transformative solution offering innovative diagnostic tools and therapeutic strategies. Nanoparticles (NPs) belonging to several classes, including metallic (metallic and metal oxide), organic (lipids, liposome), and carbon, can cross the blood–brain barrier and may exhibit immense potential for managing various strokes. Moreover, these NPs have exhibited promise in improving imaging specificity and therapeutic delivery by precise drug delivery and real-time monitoring of treatment efficacy. Nanomaterials like cerium oxide (CeO₂) and liposome-encapsulated agents have neuroprotective properties that reduce oxidative stress and promote neuroregeneration. In the present article, the authors have emphasized the significant advancements in the nanomedicine management of stroke, including NPs-based drug delivery systems, neuroprotective and neuroregenerative therapies, and multimodal imaging advancements. Full article

The greenhouse gas CH₄ is more potent than CO_2, although both these gases are solely responsible for global warming. The efficient catalytic conversion of CH₄ into hydrogen-rich syngas, which also demonstrates economic viability, can deplete the concentration of CH₄. This study examines the partial oxidation of methane (POM) prepared by the wetness impregnation process using 5% Ni supported over DSZ95 (93.3% ZrO₂ + 6.7% Sc₂O₃) and promoted with 1% Ga (gallium), 1% Sr (strontium), and 1% Ce (cerium). These catalysts are characterized by surface area porosity, X-ray diffraction, FT-Infrared spectroscopy, Raman infrared spectroscopy, temperature programmed reduction, CO₂ temperature-programmed techniques, desorption techniques, thermogravimetry, and transmission electron microscopy. The characterization results demonstrate that Ni is appropriate for the POM because of its crystalline structure, improved metal support contact, and increased thermal stability with Sr, Ce, and Ga promoters. The synthesized catalyst 5Ni+1Ga-DSZ95 maintained stability for 240 min on stream during the POM at 700 °C. Adding a 1% Ga promoter and active metal Ni to the DSZ95 improved the CH₄ conversion from 70.00% to 75.90% and raised the H₂ yield from 69.21% to 74.80%, while maintaining the reactants’ stoichiometric ratio of (CH₄:O₂ = 2:1). The 5Ni+1Ga-DSZ95 catalyst is superior to the other catalysts, given its rich catalyst surface, strong metal support interaction, high surface area and low amount of carbon deposit. The high H₂/CO ratio (>2.6) and H₂ yield close to 75% indicate that 5Ni+1Ga-DSZ95 is a potent industrial catalyst for hydrogen-rich syngas production through partial oxidation of methane. Full article

Calcium halide-based fluids are often used in drilling and completion operations due to their high density, clay inhibition and low solid content. However, there is a lack of thickeners to promote gel strength, which improves the fluid’s capacity to carry and suspend cuttings. To solve this problem, the branched polymer (hereafter abbreviated as PAD-B) was prepared by the copolymerization of N,N-dimethylacrylamide (DMAM) and 2-acrylamide-2-methylpropane sulfonic acid (AMPS), using polyethylenimine as a branching agent and cerium ammonium nitrate as the initiator. Compared with linear polymer (PAD-L), PAD-B has better shear strength at the same low viscosity. The experimental results indicated that the increase in shear strength of PAD-B is due to the interactions between branched PAD-B molecules, which lead to the formation of a network structure. The effect of calcium chloride (CaCl₂) on the rheological performance of PAD-B was investigated at 25 °C and 50 °C. Compared with PAD-L, PAD-B shows better thermal stability and calcium resistance. Its high gel strength provides technical support for addressing issues such as low yield point, gel strength and difficulty in controlling the rheological parameters of calcium halide-based fluids during the drilling and completion of complex wells. Full article

Sintering flue gas contains significant amounts of harmful gases, such as carbon monoxide and nitrogen oxides (NO_x), which pose severe threats to the ecological environment and human health. Selective catalytic reduction (SCR) technology is widely employed for the removal of nitrogen oxides, with copper-cerium-based bimetallic catalysts and their derivatives demonstrating excellent catalytic efficiency in SCR reactions, primarily due to the significant synergistic effect between copper and cerium. This paper summarizes the main factors affecting the catalytic performance of Cu-Ce-based bimetallic catalysts and their derivatives in the selective catalytic reduction of ammonia and carbon monoxide. Key considerations include various preparation methods, doping of active components, and the effects of loading catalysts on different supports. This paper also analyzes the influence of surface oxygen vacancies, redox capacity, acidity, and specific surface area on catalytic performance. Additionally, the anti-poisoning performance and reaction mechanisms of the catalysts are discussed. Finally, the paper proposes strategies for designing high-activity and high-stability catalysts, considering the development prospects and challenges of Cu-Ce-based bimetallic catalysts and their derivatives, with the aim of providing theoretical guidance for optimizing Cu-Ce-based catalysts and promoting their industrial applications. Full article