Search Results (167)

Background/Objectives: In this study, nanoemulsions containing Thymus vulgaris (TV) and Rosmarinus officinalis (RO) essential oils (EOs) were prepared and characterized, and their antibacterial, antifungal, and antibiofilm activities were evaluated against some oral pathogens. Methods: Three nanoemulsions containing 5% TV-EO (F1), 5% RO-EO (F2), and a combination of 2.5% TV-EO and 2.5% RO-EO (F3) were prepared by emulsification followed by high-speed homogenization. Results: Gas chromatography–mass spectrometry coupled with flame ionization detection (GC-MS-FID) analysis revealed linalool (79.51%) as the major constituent of TV-EO and eucalyptol (58.13%), together with camphor (10.80%), as the predominant compounds of RO-EO. All nanoemulsions exhibited nanosized droplets, low polydispersity index (PDI) values (<0.3), and moderate to high colloidal stability. Transmission electron microscopy (TEM) analysis revealed predominantly spherical droplets in all formulations (F1–F3). All formulations exhibited antimicrobial activity against Streptococcus mutans, Lactobacillus acidophilus, Enterococcus faecalis, and Candida albicans. Among the tested formulations, F2 showed the strongest antibacterial activity, whereas F3 exhibited the highest antibiofilm activity against mature S. mutans biofilms, achieving approximately 80% inhibition, comparable to chlorhexidine (CHX). Although F3 possessed the smallest droplet size, its antimicrobial activity was lower than that of F2, suggesting that biological activity was influenced not only by droplet size but also by EO composition. Conclusions: These findings demonstrate the potential of TV-EO and RO-EO nanoemulsions as promising natural alternatives for mouthwash formulations and highlight the importance of EO composition in determining antimicrobial and antibiofilm efficacy. Full article

Hierarchical zeolites have emerged as an effective strategy to mitigate diffusional limitations and catalyst deactivation during the catalytic cracking of heavy feedstocks. However, conventional alkaline desilication often lacks selectivity, leading to partial loss of crystallinity and unfavorable alterations in acidic properties. In this work, microwave-assisted desilication is explored as an alternative route to engineer hierarchical Y zeolites with improved structural control and catalytic performance. A systematic comparison between conventional and microwave-assisted treatments was carried out using a 0.20 mol L⁻¹ NaOH solution, followed by hydrothermal stabilization. The resulting materials were comprehensively characterized by X-ray diffraction, nitrogen physisorption, scanning electron microscopy, ICP–OES, and pyridine-adsorbed FTIR. Catalytic performance was evaluated in the cracking of nitrogen-containing vacuum gas oil under microactivity test conditions representative of FCC operation. Microwave-assisted desilication promotes a more homogeneous development of mesoporosity, yielding higher mesopore volumes and larger pore diameters while preserving a greater fraction of the FAU crystalline structure and Brønsted acidity compared to conventional treatment. These features translate into enhanced catalytic behavior, including higher and more stable conversions, increased gasoline selectivity (up to 63 wt%), and significantly reduced coke yields. In addition, spectroscopic and thermal analyses reveal that coke formed on the microwave-treated zeolite is less condensed and more readily oxidizable, indicating a reduced propensity for irreversible deactivation. Finally, the results demonstrate that the mode of energy input during desilication plays a critical role in dictating the balance between pore architecture and acidity, ultimately governing catalytic performance. Microwave-assisted desilication emerges as an efficient strategy for designing hierarchical Y zeolites with improved accessibility, selectivity, and resistance to deactivation under severe FCC conditions. Full article

In this study, HC420LA steel plates joined by gas metal arc welding (MAG), manual laser welding (ML), and robotic laser welding (RL) were comparatively examined under heat input (HI) levels obtained from an active production line exhibiting weld defects. The effect of HI and welding method on mechanical properties, microstructural evolution, phase characteristics, and weld integrity was evaluated using tensile and hardness tests, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Weld imperfections were evaluated according to ISO 5817:2023(E) for MAG welds and BS EN ISO 13919-1:2019 for laser welds, and the corresponding quality levels were determined. The highest tensile strength (568 MPa) and elongation (23%) were achieved in RL welds at the lowest HI value (0.108 kJ/mm), with fracture occurring outside the weld region, indicating superior joint integrity and mechanical compatibility with the base metal. In contrast, MAG and ML welds exhibited a non-linear relationship between HI and ductility and tensile strength. ML welds showed higher hardness and reduced ductility due to the formation of harder transformation products, while MAG welds demonstrated a non-linear response associated with heat-affected zone (HAZ) coarsening. Heterogeneous phase distribution XRD analysis confirmed the presence of α-Fe-based phases and secondary alloyed structures, while EDS analyses revealed a relatively homogeneous distribution of the principal alloying elements within the weld regions and provided supporting evidence for the Mn₃O₄ oxide phase identified in the RL welds. SEM observations further demonstrated distinct microstructural transitions across the fusion zone (FZ) and HAZ, reflecting the influence of the welding process and heat input on weld evolution. The assessment of weld imperfections according to the relevant ISO standards showed that ML and RL welds satisfied Quality Level B, whereas MAG welds exhibited quality levels ranging from B to D, depending on the evaluated imperfection. These results indicate that equivalent HI values do not guarantee comparable weld quality or mechanical performance across different welding processes. The study provides insight into the relationship between heat input, weld quality, microstructural evolution, phase constitution, and mechanical performance in HSLA steels. Full article

The Shaximiao Formation in the Sichuan Basin possesses favorable exploration potential for unconventional oil and gas, whereas systematic studies on the genetic mechanism of its tight sandstone reservoirs remain insufficient. In this study, tight sandstones of the study area were comprehensively investigated through multiple analytical methods, including thin section observation, scanning electron microscopy, cathodoluminescence, electron probe microanalysis, fluid inclusion testing, and reservoir physical property measurement. The Shaximiao Formation belongs to typical low-permeability tight reservoirs, which are predominantly composed of lithic arkose, followed by feldspathic litharenite and arkose. A variety of authigenic minerals are widely developed in the reservoirs, including laumontite, calcite, quartz overgrowth, feldspar overgrowth, and clay minerals. The main reservoir spaces consist of primary pores, feldspar dissolution pores, and laumontite dissolution pores. The reservoirs have reached middle diagenetic stage A. A full set of diagenetic events can be identified in the study interval. These processes consist of gypsum cementation, chlorite cementation, feldspar dissolution, quartz overgrowth, kaolinite precipitation, laumontite cementation and dissolution, carbonate cementation, and pyrite cementation. Synthetic analysis of microscopic inclusion occurrences, homogenization temperature, and salinity data reveals that the Shaximiao Formation experienced three successive charging episodes of three different fluid endmembers, namely indigenous formation brine, organic acid fluid, and low-salinity surface-derived fluid. These multiphase mixed fluids sequentially altered authigenic minerals and pore spaces under variable open–closed diagenetic systems. The diagenetic system evolved progressively from an early closed environment dominated by laumontite precipitation to a middle–late semi-open-to-open environment dominated by calcite and siliceous cementation. Differential fluid migration controls diagenetic processes and the spatial distribution of cements, which fundamentally accounts for the strong heterogeneity of the reservoirs. Three types of diagenetic environments are classified in the study area, namely compaction-dominated, cementation-dominated, and dissolution-dominated environments, which jointly control the diagenetic assemblages and physical property evolution of the reservoirs. Compaction acts as the primary pore-reducing factor, causing a total porosity loss of 23.34%. Dissolution of feldspar and laumontite serves as the major pore-enhancing process, increasing the porosity by 5.26% and 4.32%, respectively. The mudstone and carbonate rock fragments in western Sichuan provide essential materials for calcite cementation, while intermediate-acid pyroclastics and plagioclase albitization collectively promote laumontite enrichment. The infiltration of meteoric freshwater and the upward migration of organic acids along faults induce feldspar dissolution, further resulting in the formation of kaolinite and quartz overgrowths. The brackish diagenetic environment under arid climatic conditions facilitates the development of early gypsum, which is finally transformed into anhydrite through burial dehydration. Full article

With the rapid construction of new power systems characterized by high renewable energy penetration, high power electronics integration, and high voltage levels, the insulation reliability of critical power equipment—including cable accessories, gas-insulated switchgear (GIS), and power electronic modules—faces unprecedented challenges. Field grading materials (FGM), as core functional media for adaptive electric field homogenization and insulation failure prevention, have emerged as a research hotspot spanning materials science, electrical engineering, and polymer engineering. Starting from the current research status of FGM, this review systematically summarizes filler optimization strategies, covering single fillers, hybrid fillers, trace co-fillers, and structural modification approaches. The applications of FGM in transmission cables, GIS, high-voltage electrical machines, and wide-bandgap power electronic modules are then elaborated in detail. Emphasis is placed on performance enhancement routes of FGM, particularly thermal conductivity improvement via constructing three-dimensional thermally conductive networks and intelligent early warning based on thermochromic materials. Finally, the existing bottlenecks of FGM are analyzed in terms of material stability, multi-physical field coupling adaptation, and engineering industrialization. Future development trends are prospected toward high-performance, multifunctional, intelligent, and engineering-oriented FGM. This review aims to provide theoretical references and technical support for the design and application of advanced FGM in new power systems. Full article

This study provides a rigorous analysis of the phase stability, mechanical behavior, and surface integrity of a non-equiatomic (FeCoNiCr)₈₅Ga₁₅ high-entropy alloy (HEA). By transitioning from the conventional equiatomic design to a gallium-doped 3d-transition metal matrix, we explore the interplay between lattice distortion and phase separation. Synthesized via vacuum arc melting, the as-cast alloy exhibits a non-homogeneous dendritic morphology consisting of a Cr-Fe-Co rich face-centered cubic (FCC) matrix and Ni-Ga rich body-centered cubic (BCC) interdendritic regions. While global thermodynamic criteria (δ = 3.65, ΔH_mix = −9.28 kJ/mol, and Ω = 2.23) favor single-phase solid solution stability, the Valence Electron Concentration (VEC = 7.46) precisely forecasts this dual-phase structure. Following low-temperature annealing at 250 °C for 24 h, high lattice strain energy drives a significant morphological transformation where the continuous interdendritic network resolves into discrete, phase-separated B2/BCC “islands”. Mechanical and tribological characterizations reveal that this low-temperature thermal activation triggers precipitate hardening; the macro-hardness increases from 146 ± 11 HB to 153 ± 7.5 HB and the micro-hardness rises from 186 ± 4 HV_0.5 to 206 ± 17.5 HV_0.5, yielding enhanced resistance to oxidation-delamination wear. However, electrochemical evaluation in a 3.5 wt.% NaCl solution highlights a fundamental trade-off: the formation of localized galvanic micro-cells between the phase-separated islands and the matrix causes the corrosion current density (i_corr) to increase from ≈10⁻⁹ A/cm² in the as-cast state to ≈10⁻⁶ A/cm² post-heat treatment, accompanied by a heightened susceptibility to localized pitting. These findings elucidate the primary role of electronic structure and minor p-block additions in regulating the lifecycle performance of transition metal HEAs under extreme conditions. Full article

The scalable production of high-quality nanoparticles is a significant challenge for advancing nanotechnology applications. This research introduces a continuous-flow liquid-plasma discharge reactor for the synthesis of silver nanoparticles at room temperature and atmospheric pressure, utilizing D-xylose as a dual-function reducing and stabilizing agent. The reactor effectively generated uniform xylose-capped silver nanoparticles (X-Ag NPs). Optimal conditions were established utilizing argon gas at a 1:100 molar ratio of Ag precursor to D-xylose, resulting in spherical X-Ag NPs with an average size of 16.89 nm, a zeta potential of −38.87 mV, and a polydispersity index of 0.22. The formation and properties of X-Ag NPs were confirmed through characterization techniques including UV-Vis spectroscopy, dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). The findings demonstrate that uniform particle nucleation and growth occurred due to the homogeneous distribution of high-energy electrons and reactive gas species produced in the plasma phase. This environmentally sustainable, continuous-flow method shows considerable promise for the industrial-scale production of biomass-derived silver nanoparticles. Full article

The rapid advancement of high-performance computing has spurred growing demand for miniaturized, high-density, high-power, and highly reliable electronic packaging. Through-silicon via (TSV), as a pivotal technology enabling high-density integrated packaging, achieves vertical interconnection that reduces signal latency and power consumption while substantially improving system integration. However, inherent challenges persist due to coefficient of thermal expansion mismatches among heterogeneous materials in TSV and parasitic effects introduced by high-density TSV arrays, leading to critical concerns regarding thermomechanical reliability and signal integrity. This study focuses on TSV structures, investigating their thermomechanical reliability and electrical performance. First, the macro–micro model of 2.5D package structure was established to address cross-scale challenges based on Representative Volume Element (RVE) homogenization and sub-model technique. Then, an equivalent circuit model integrating transmission line network theory was developed and validated through full-wave electromagnetic simulations using S-parameter analysis to analyze signal transmission characteristics. Finally, by introducing an improved multi-objective grasshopper algorithm, the structural parameters of TSV are co-optimized using a genetic algorithm back propagation network (GA-BP) and an improved multi-objective grasshopper algorithm (IMOGOA) to enhance both thermomechanical reliability and electrical characteristics simultaneously. The proposed approach offers a practical and effective solution for improving the reliability and performance of high-density integrated packaging, providing valuable insights for future packaging design and optimization. Full article

Along with the growth in the production of metallurgical grade silicon and high-silicon ferrous alloys, there is a significant increase in the formation of microsilica, which is an ultra-fine technogenic waste. The direct application of microsilica in ore-thermal furnaces is hindered by low bulk density, poor gas permeability, and high dusting. This paper explores the thermophysical and microstructure properties of briquettes based on microsilica, which includes various types of carbonaceous reducing agents such as semi-coke and coal. For manufacturing, the liquid glass was used as the inorganic binder for the preparation of microsilica briquettes. The best variants were chosen based on strength tests carried out during preliminary studies. In the laboratory tests, the stability of the briquettes at elevated temperatures was evaluated. Samples were heated to 1000–1500 °C and subjected to impact testing. Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) was used to investigate the microstructure and local elemental distribution. It was revealed that the calcinated briquettes of the microsilica–semi-coke mixture have better thermal stability compared to the samples with coal and withstand the temperature range up to 1500 °C. The microstructure of the briquette from the microsilica-semi-coke mixture is characterized by the formation of a more uniform silicate matrix with the presence of a homogeneously distributed carbonaceous component. Coal-based samples show higher heterogeneity and porosity. Therefore, it can be stated that the selection of carbonaceous reductants is one of the key factors influencing the thermal stability of microsilica briquettes. Full article

This study compares the microstructural evolution and mechanical properties of TC4 (Ti-6Al-4V) titanium alloy joints welded by Tungsten Inert Gas (TIG) and laser processes, following a post-weld annealing treatment at 650 °C for 2 h. Distinct microstructures were obtained: the TIG-welded joint developed a heterogeneous mixture of short-rod α and lamellar β, while the laser-welded joint formed a more homogeneous equiaxed α structure with uniformly distributed β-phase nanoparticles. Electron backscatter diffraction (EBSD) results confirmed that the annealing treatment significantly weakened the strong welding-induced texture and disrupted the epitaxial growth mode of columnar grains. Mechanical testing demonstrated that annealing improved the strength-toughness balance, but the extent and mechanism differed between the two processes. For the TIG-welded joint, the ultimate tensile strength slightly decreased, while elongation and impact toughness increased by 18% and 10.4%, respectively. In contrast, the laser-welded joint maintained its original strength while achieving greater improvements in ductility and toughness, with elongation and impact toughness increasing by 20% and 15.2%, respectively. This divergence is attributed to insufficient recrystallization and the persistence of residual coarse grains, limiting the TIG joint’s performance. However, in the laser-welded joint, the pinning effect of β-phase nanoparticles and associated grain refinement enhanced ductility without compromising strength. Full article

Gas-filled discharge capillaries are widely used in the field of plasma-based particle accelerators, due to their compactness, cost-effectiveness and versatility for different applications. Technological improvement of such plasma sources is necessary to enable high energy gain acceleration at the meter scale, as required for next-generation particle colliders and light sources. Beam quality preservation within such an acceleration length involves accurate tuning of the plasma properties. In particular, precise tailoring of the plasma density distribution is required to control the emittance growth of particle bunches during the acceleration process. In this context, this paper presents a scalable and versatile approach for the design of meter-scale discharge capillaries, aimed at achieving fine tuning of the plasma density distribution, with the possibility of locally controlling the density profile by acting on the source geometry. Forty-centimeter-long capillaries are designed using numerical fluid dynamics simulations and tested in a dedicated plasma module. Different arrangements of the gas inlets are tested, with their number and diameter varied, to assess the effect of the capillary geometry on the plasma properties. Plasma density measurements show that a higher number of inlets with variable diameter along the plasma formation channel provides an enhancement in the homogeneity of the electron plasma density distribution. Longitudinal density plateaus are observed along most of the plasma channel length, with a center-to-end density uniformity of up to 80%. The experimental results highlight the proposed approach’s capability to modulate the longitudinal plasma density distribution by acting on the capillary geometry, thus providing uniform density profiles over the meter scale, as required for plasma-based acceleration experiments. Full article

The newly identified greisen-hosted Nb-Ta mineralization in the Qidashan iron deposit, Liaoning Province, China, offers a unique opportunity to explore how hydrothermal processes contribute to the enrichment of critical metals. In this study, an integrated analytical approach of petrographic observation and scanning electron microscopy–energy-dispersive spectrometer (SEM-EDS), electron probe microanalyzer (EPMA), and laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) U-Pb dating of columbite-group minerals (CGMs) were employed to systematically decipher the paragenetic sequence, micro-structure, elemental composition and mineralization age of CGMs, aiming at the genesis of greisen-hosted Nb-Ta mineralization. The mineralization is characterized by the abundant occurrence of CGMs. Three generations of CGMs and two mineralization stages are distinguished: stage I contains CGM Is and CGM IIs, with Nb₂O₅ ranging from 25.7 to 69.56 wt.% and Ta₂O₅ from 5.8 to 52.5 wt.%; stage II contains CGM IIIs, with Nb₂O₅ between 59.5 and 71.5 wt.% and Ta₂O₅ between 3.5 and 16.2 wt.%. CGM Is consist of euhedral, homogeneous crystals of more than 100 μm, exhibit low Ta/(Nb + Ta) ratios (0.05–0.06) and high Mn/(Fe + Mn) ratios (0.19–0.26), and belong to columbite-Fe. CGM IIs generally overgrow on CGM Is with hydrothermal overprinting textures, and show significant compositional gaps compared to CGM Is, exhibiting higher Ta/(Nb + Ta) ratios (0.13–0.55) and restricted Mn/(Fe + Mn) ratios (0.15–0.18), with some belonging to columbite-Fe and others to tantalite-Fe, which reveals a transition from magma to “hydrosilicate fluid”. CGM IIIs are mainly anhedral and homogeneous, with a grain size of less than 50 μm. However, some CGM IIIs overgrow on CGM IIs and/or CGM Is with patchy textures indicative of subsequent hydrothermal overprinting of hydrosilicate fluid, forming a coarse-grain size over 100 μm. CGM IIIs are characterized by lower Ta/(Nb + Ta) ratios (0.03–0.14) and variable Mn/(Fe + Mn) ratios (0.08–0.26), and they belong to columbite-Fe. LA-ICP-MS U-Pb dating yields weighted mean ²⁰⁶Pb/²³⁸U ages of 2646 ± 15 Ma for stage I and 2500 ± 28 Ma for stage II, indicating two-stage Nb-Ta mineralization. The early mineralization may correlate with the partial melting of volcanic–sedimentary rocks due to the geothermal anomalies associated with ~2.7 Ga submarine volcanism, and the late mineralization formed by the magmatic hydrothermal activities related to emplacement of the Qidashan granite in 2.5 Ga. We therefore propose that the two-stage greisen-hosted Nb-Ta mineralization probably widely occurred in these sedimentary–metamorphic iron deposits in the Anshan–Benxi area and even in the northern edge of the North China Craton, and it may provide new insights for evaluating the Nb-Ta resource potential in similar Algoma-type iron deposits globally. Full article

The incorporation of supplementary cementitious materials (SCMs) is a key strategy for enhancing the performance and sustainability of cement-based systems. This research examines the mechanical behavior, microstructural evolution, and durability-related properties of cementitious materials incorporating waste glass powder (WGP) and metakaolin (MK) as partial replacements of Portland cement. Cement pastes were evaluated for compressive strength at 7 and 28 days, while microstructural analysis at 28 days employed gas adsorption and scanning electron microscopy (SEM). Based on the compressive strength performance of the cement pastes, ternary WGP–MK mortars were assessed for consistency, flexural and compressive strength, water absorption, and porosity at 28 and 60 days. Results indicate that MK accelerates early-age strength, whereas WGP enhances long-term performance and pore structure refinement. Binary and ternary systems exhibited reduced accessible pore volume, enhanced microstructural homogeneity, and lower water absorption with curing time. The findings demonstrate that WGP-MK blends support clinker reduction without compromising performance, advancing circular economy goals in construction. Full article

PrFeTiO₃ perovskite composite was synthesized, and its structural, morphological, chemical, and optical properties were comprehensively characterized. X-ray diffraction (XRD) and a selected area electron diffraction (SAED) confirm the formation of an orthorhombic distorted perovskite phase with no secondary impurities. Transmission electron microscope (TEM) observations show aggregated nanocrystalline domains, while EDS mapping reveals homogeneous cation distribution (Pr, Fe, Ti, O), confirming successful incorporation of Fe and Ti into the perovskite lattice. X-ray photoelectron spectroscopy (XPS) analysis identifies Pr³⁺, Fe³⁺, and Ti⁴⁺ as the dominant oxidation states, supporting charge-compensated B-site substitution. Optical analysis reveals a bandgap of ~2.0 eV, significantly narrower than pristine titanates, indicating enhanced visible-light absorption. This multi-modal characterization verifies the successful formation of PrFeTiO₃ and highlights its potential as a visible-light-active photocatalyst. Although PrTiO₃ showed little reactivity to visible light, PrFeTiO₃ showed excellent efficiency in visible light photocatalytic reactions. PrFeTiO₃ showed more than 20 times better performance than PrTiO₃ in the photodegradation of methylene blue in the liquid phase and formaldehyde in the gas phase. Furthermore, PrFeTiO₃ showed more than 95% superior bactericidal activity against the pathogenic bacterium Staphylococcus aureus than PrTiO₃. Its high photocatalytic efficiency can be attributed to its strong photosensitivity to visible light and small band gap energy. Full article

N₂O emissions exacerbate the greenhouse effect, urgently demanding advances in abatement technologies. Catalytic decomposition of N₂O over cobalt-based oxides with alkali metal promoters remains challenging because these catalysts are used in pelletized form, limiting their activity to a narrow outer-shell region due to internal diffusion limitations. However, research efforts continue to focus on enhancing Co–alkali metal contact on unsupported powder samples under inert conditions, even though, under industrial conditions, catalysts are exposed to inhibitory components of waste gases and N₂O, and the powder form is unsuitable for practical application. This study aims at testing N₂O decomposition over catalysts with a Co₃O₄-Cs active phase supported on a ceramic foam. For this purpose, we characterized these catalysts by H₂ temperature-programmed reduction, H₂O and NO temperature-programmed desorption, atomic absorption spectroscopy, and X-ray diffraction and assessed their catalytic performance under an inert-gas atmosphere and with O₂, water vapor, and NO to simulate industrial conditions. Using a pseudo-homogeneous, one-dimensional model of an ideal plug flow reactor in an isothermal regime, the simulation calculations for a full-scale catalytic reactor for N₂O abatement in waste gas from HNO₃ production were performed. The Cs₂CO₃ precursor significantly enhanced catalyst reducibility and electron transferability, increasing N₂O decomposition efficiency in inert gas, but its high hygroscopicity decreased resistance to water vapor and NO, overriding its advantages under industrial conditions. Conversely, glycerol-assisted impregnation enhanced catalyst performance regardless of Cs precursor. These foam-supported catalysts offered several other advantages, including lower pressure drop and lower active phase loading with matching catalytic activity. Based on our findings, depositing Cs₂CO₃ on ceramic foam through glycerol-assisted impregnation may facilitate catalytic N₂O decomposition at the industrial level and, therefore, promote environmental sustainability by reducing N₂O emissions. Full article