Search Results (1,020)

Low carbon, low cost and sustainability are important development trends of ultra-high-performance concrete (UHPC). In this study, municipal solid waste incineration bottom ash (MSWIBA) was used to replace 5%, 10%, 20% and 30% of quartz sand (QS), respectively, and the effect of the MSWIBA substitution rate on the workability, wet packing density, mechanical properties, shrinkage, resistance to chloride ion corrosion, and resistance to sulfate corrosion of UHPC was studied. The mechanism analysis was carried out by combining X-ray diffraction (XRD), thermogravimetric analysis (TG), and scanning electron microscopy (SEM) tests, and UHPC heavy metal leaching tests, environmental impact assessment, and economic analysis were conducted. Results show that the active silicon and aluminum components in MSWIBA reacted with cement hydration products to optimize the matrix density. MSWIBA has an internal curing effect, which is beneficial for reducing the shrinkage of UHPC. When the MSWIBA replacement rate is 10%, the 28-day compressive strength of MSWIBA-UHPC is 128.7 MPa, which is equivalent to the benchmark group. The fluidity, corrosion resistance and heavy metal leaching all meet the requirements. The energy consumption, carbon emissions and costs are reduced by 0.22%, 2.30% and 6.67%, respectively. The research results can provide a reference for the development of ecological UHPC with economic, low-carbon and environmental benefits, as well as the harmless disposal and resource utilization of hazardous wastes such as MSWIBA. Full article

An integrative approach combining network pharmacology, molecular docking, and cellular assays was used to elucidate the potential mechanisms by which the n-butanol extract of Biebersteinia heterostemon ameliorates type 2 diabetes mellitus (T2DM). Chemical constituents of the n-butanol extract were identified via ultra-high-performance liquid chromatography coupled with Q-Exactive Orbitrap mass spectrometry. Active compounds and T2DM-related targets were retrieved from public databases, and intersecting targets were identified. Protein–protein interaction (PPI) networks were constructed using the STRING database, while Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed via the DAVID database. A comprehensive “drug–compound–target–disease–pathway” network was established, and molecular docking was conducted to evaluate binding affinities of key compounds to core targets. Functional validation was performed in insulin-resistant cell models. Network pharmacology analysis identified 37 active constituents within the extract and 222 overlapping targets associated with T2DM. GO enrichment indicated involvement in protein phosphorylation, MAPK cascade activation, and negative regulation of apoptosis. Key signaling pathways included PI3K/AKT and lipid and atherosclerosis pathways. Molecular docking revealed strong binding affinities (binding energies ≤ −9.3 kcal·mol⁻¹) between core compounds—such as cheilanthifoline, glabridin, acetylcorynoline, skullcapflavone II, liquiritigenin, and dinatin—and pivotal targets including GAPDH, AKT1, TNF, SRC, EGFR, and PPARγ. In vitro experiments demonstrated that the extract significantly enhanced glucose uptake and glycogen synthesis in insulin-resistant cells, while suppressing oxidative stress and the expression of pro-inflammatory mediators such as TNF-α, MMP9, and IL-6. Collectively, B. heterostemon shows potential as an effective intervention for T2DM by targeting key molecular pathways, improving insulin sensitivity, and mitigating oxidative stress and inflammation in insulin-resistant cells. Full article

This study introduces an innovative approach to addressing the plastic shrinkage of ultra-high-performance concrete (UHPC) using an azodicarbonamide (ADC) expansive agent. The influence of ADC on the workability, mechanical properties, and plastic shrinkage of UHPC were systematically investigated. The findings reveal that the addition of ADC generates a substantial number of bubbles within the UHPC slurry, thereby reducing internal frictional resistance and cohesion of the mixture. Consequently, the fluidity and setting time of UHPC were enhanced to varying degrees with increasing ADC content. However, the introduction of these bubbles also reduced the density, leading to a noticeable decline in both compressive and flexural strength, particularly at later stages. Notably, ADC effectively mitigated early shrinkage and increased the vertical expansion rate within the first 24 h. When the ADC dosage ranged from 0.04% to 0.1%, the UHPC remained in an expanded state within 24 h, with a notable difference in expansion rate exceeding 0.02% from 3 to 24 h. Microstructural and pore structure analysis revealed that the ADC generated considerable gas during the mixing process, forming numerous micropores within the UHPC matrix. These dispersed pores contributed to reduced compactness of the UHPC hydrates, resulting in increased pore area, porosity, and average pore diameter. Full article

High-entropy boride (HEB) ceramics combine ultra-high melting points, superior hardness, and compositional tunability, enabling service in extreme environments; however, difficult densification and limited fracture toughness still constrain their aerospace applications. In this study, metallic Ta was introduced into high-entropy (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)B₂ as both a sintering aid and a toughening phase. Bulk HEB-Ta composites were fabricated by spark plasma sintering to investigate the effect of Ta content on densification behavior, microstructure, mechanical properties, and high-temperature oxidation resistance. The results show that an appropriate amount of Ta markedly promotes densification; at 10 vol% Ta, the open porosity reaches a minimum of 0.15%. Hardness and fracture toughness exhibit an increase-then-decrease trend with Ta content, attaining maxima at 15 vol% Ta (20.79 ± 0.17 GPa and 4.31 ± 0.12 MPa·, respectively). During oxidation at 800–1400 °C, the extent of oxidation increases with temperature, yet the composite with 10 vol% Ta shows the best oxidation resistance. This improvement arises from the formation of a viscous, protective Ta₂O₅-B₂O₃ glassy layer that effectively suppresses oxygen diffusion and enhances high-temperature stability. Overall, incorporating metallic Ta is an effective route to improve the manufacturability and service durability of HEB ceramics, providing a composition guideline and a mechanistic basis for simultaneously enhancing densification, toughness, and oxidation resistance. Full article

Beta-gallium oxide (β-Ga₂O₃) is a semiconductor with an ultra-wide bandgap, high optical transparency, and excellent electrical properties, which can be finely tuned for a wide range of electronic devices. This study optimized the process conditions for fabricating β-Ga₂O₃ thin films with desired electrical characteristics. β-Ga₂O₃ films were deposited on (100) Si substrates via RF magnetron sputtering with varying O₂ flow rates and post-annealed at temperatures ranging from 600 °C to 800 °C. The structural and electrical properties of the films were analyzed using X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), and Hall effect measurements. The XRD results confirmed the formation of nanocrystalline β-Ga₂O₃, with variations in peak intensities and shifts observed based on O₂ flow rates. The films exhibited carrier concentrations exceeding 5 × 10²² cm⁻³, mobilities ranging from 50 to 115 cm²/Vs, and resistivity around 1 × 10⁻⁶ Ω⋅cm. This study demonstrates that the electrical properties of β-Ga₂O₃ thin films can be modulated during the deposition and post-annealing processes. The ability to control these properties underscores the potential of β-Ga₂O₃ for advanced applications in high-performance high-power devices and optoelectronic devices such as deep ultraviolet photodetectors. Full article

Thrust vectoring technology significantly improves the manoeuvrability and environmental adaptability of unmanned aerial vehicles by dynamically regulating the direction and magnitude of thrust. In this paper, the principles and applications of mechanical thrust vectoring technology, fluidic thrust vectoring technology and the distributed electric propulsion system are systematically reviewed. It is shown that the mechanical vector nozzle can achieve high-precision control but has structural burdens, the fluidic thrust vectoring technology improves the response speed through the design of no moving parts but is accompanied by the loss of thrust, and the distributed electric propulsion system improves the hovering efficiency compared with the traditional helicopter. Addressing multi-physics coupling and non-linear control challenges in unmanned aerial vehicles, this paper elucidates the disturbance compensation advantages of self-disturbance rejection control technology and the optimal path generation capabilities of an enhanced path planning algorithm. These two approaches offer complementary technical benefits: the former ensures stable flight attitude, while the latter optimises flight trajectory efficiency. Through case studies such as the Skate demonstrator, the practical value of these technologies in enhancing UAV manoeuvrability and adaptability is further demonstrated. However, thermal management in extreme environments, energy efficiency and lack of standards are still bottlenecks in engineering. In the future, breakthroughs in high-temperature-resistant materials and intelligent control architectures are needed to promote the development of UAVs towards ultra-autonomous operation. This paper provides a systematic reference for the theory and application of thrust vectoring technology. Full article

Normal concrete exhibits poor resistance to chloride penetration, often leading to reinforcement corrosion and premature structural failure. In contrast, ultra-high-performance concrete (UHPC) demonstrates superior resistance to corrosion caused by chloride salts. The chloride diffusion behaviour of UHPC was investigated via long-term immersion (LTI) and rapid chloride migration (RCM) tests. Additionally, this study presents the first development of a time-dependent diffusion model for UHPC under chloride corrosion, as well as the proposal of a performance-based design method for calculating the protective layer thickness. Results show that the incorporation of steel fibers reduced the chloride diffusion coefficient ($D$) by 37.9%. The free chloride content (FCC) in UHPC increased by 92.0% at 2 mm after 300 d of the action of LTI. $D$ decreased by up to 91.0%, whereas the surface chloride concentration ($C_{\mathrm{s}}$) increased by up to 92.5% under the action of LTI. The time-dependent models of $D$ and $C_{\mathrm{s}}$ followed power and logarithmic functions, respectively. An increase in UHPC surface temperature, relative humidity, and tensile stress ratio significantly diminishes the chloride resistance of UHPC. The minimum UHPC protective layer thicknesses required for UHPC-HPC composite beams with design service lives of 100 years, 150 years, and 200 years are 30 mm, 37 mm, and 43 mm, respectively. Full article

Silica fiber-reinforced silica aerogel (SFRSA) has low dielectric constant, light weight and high temperature resistance characteristics, making it one of the preferred materials for heat-resistant absorptive layers on the surfaces of high-speed aircraft. However, due to its ultra-high porosity, poor rigidity, and sensitivity to organic solvents, existing machining and chemical etching processes struggle to achieve patterned preparation of metallic layers on aerogel substrates. In order to address this issue, the present study employs femtosecond laser etching of the metal layer on the SFRSA surface. Orthogonal experiments were conducted to analyze the impact of different laser process parameters on the etching quality. With straightness as the primary factor, the optimal process parameters obtained were a laser power set to 2.15 W, a laser etching speed of 200 mm/s, and a laser etching time of 9. This achieved an etching width of 26.16 μm, a heat-affected zone of 39.16 μm, and straightness of 7.9 μm. Finally, Raman spectroscopy was used to study laser-ablated samples; thermogravimetric analysis (TGA) and Pyrolysis-Gas Chromatography–Mass Spectrometry analysis (Py-GC-MS) were employed to investigate the changes in the metal layer at high temperatures. A compositional analysis was conducted, revealing a decrease in carbon content within the etched region following laser ablation. The production of CO₂ gas and surface oxidation indicated that laser etching primarily operates via a photothermal mechanism. Full article

Fractured tight sandstone reservoirs pose challenges for gas development due to low matrix porosity and permeability, complex pore structures, and pervasive fractures. This study focuses on the Bashijiqike Formation in the Keshen Gas Field, Kuqa Depression, aiming to clarify the geological controls on reservoir quality. Lithofacies, diagenetic facies, and fracture facies were systematically classified by core analyses, thin sections, scanning electron microscopy (SEM), cathodoluminescence (CL), X-ray diffraction (XRD), grain size analyses, mercury intrusion capillary pressure (MICP), well logs and resistivity imaging logging (FMI). Their impacts on porosity, permeability and gas productivity were quantitatively assessed. A ternary reservoir quality assessment model was established by coupling these three factors. Results show that five lithofacies, four diagenetic facies, and four fracture facies jointly control reservoir performance. The high-energy gravelly sandstone facies exhibit an average porosity of 6.0% and average permeability of 0.066 mD, while the fine-grained sandstone shows poor properties due to compaction and clay content. Unstable component dissolution facies enhance secondary porosity to 6.0% and permeability to 0.093 mD. Reticulate and conjugate fracture patterns correspond to gas production rates two to five times higher than those with single fractures. These findings support targeted reservoir classification and improved development strategies for ultra-deep tight gas reservoirs. Full article

P92 martensitic heat-resistant steel is widely used in ultra-supercritical (USC) thermal power units due to its excellent creep resistance and high-temperature strength. However, prolonged exposure to high temperatures induces significant microstructural degradation, compromising mechanical properties and operational safety. This study investigates the evolution of microstructure and mechanical properties in P92 steel extracted from main steam pipelines after service durations of 30,000 h, 47,000 h, 56,000 h, 70,000 h, and 93,000 h. Comparative analyses of impact toughness, tensile strength, and creep strength were conducted and advanced characterization of SEM and TEM was used to investigate the microstructural evolution. The results reveal a progressive decline in mechanical properties with increasing service time. Specifically, impact toughness decreased by approximately 66.8%, room-temperature tensile strength reduced by 9.62%, and high-temperature tensile strength at 610 °C declined by 31.6%. Notably, the 10⁵ hour creep rupture strength exhibited a 10.4% decrease compared to as-received material. This decline is attributed to microstructural changes including precipitate coarsening, martensite lath boundary degradation, dislocation reconfiguration, and severe grain coarsening. The coarsening of precipitates weakens their bonding with the matrix, while the widening of martensite laths reduces resistance to crack propagation and dislocation movement, jointly contributing to strength deterioration. Full article

Anti-resonant hollow-core fibers (AR-HCFs) are emerging as highly promising candidates for high-power laser transmission and low-loss optical communication. Despite their advantages, issues such as scattering loss and core-mode instability remain significant obstacles for their practical implementation. In this study, we propose a novel hybrid fiber structure, the nano-core plus node-free anti-resonant hollow-core fiber (NPNANF), which integrates a solid, high-index nano-core within a six-tube node-free anti-resonant cladding. This hybrid design effectively enhances optical confinement while minimizing scattering losses, without relying solely on anti-resonant guidance. Numerical simulations employing the beam propagation method (BPM) and finite element analysis (FEA) demonstrate that an optimal nano-core diameter of 600 nm leads to a remarkable reduction in transmission loss to 0.025 dB/km at 1550 nm, representing a 99.8% decrease compared to conventional NANF designs. A comprehensive loss model is developed, incorporating contributions from confinement, scattering, and absorption losses in both the hollow cladding and the solid core. Parametric studies further illustrate the tunability of the fiber’s design for various high-performance applications. The proposed NPNANF achieves an ultra-low transmission loss of 0.025 dB/km, representing a >99.8% reduction compared to conventional NANF, while confining more than 92% of optical power within the nano-core. Its resistance to bending loss, strong modal stability, and balance between hollow-core and solid-core guidance highlight the advantages of NPNANF for long-haul optical communication and high-power photonics. Full article

This review summarizes recent advances in multifunctional metamaterials (MF-MMs) for electromagnetic (EM) wave absorption. MF-MMs overcome the key limitations of conventional absorbers—such as narrow bandwidth, limited functionality, and poor environmental adaptability—offering enhanced protection against EM security threats in radar, aerospace, and defense applications. This review focuses on an integrated structure-material-function co-design strategy, highlighting advances in three-dimensional (3D) lattice architectures, composite laminates, conformal geometries, bio-inspired topologies, and metasurfaces. When synergized with multicomponent composites, these structural innovations enable the co-regulation of impedance matching and EM loss mechanisms (dielectric, magnetic, and resistive dissipation), thereby achieving broadband absorption and enhanced multifunctionality. Key findings demonstrate that 3D lattice structures enhance mechanical load-bearing capacity by up to 935% while enabling low-frequency broadband absorption. Composite laminates achieve breakthroughs in ultra-broadband coverage (1.26–40 GHz), subwavelength thickness (<5 mm), and high flexural strength (>23 MPa). Bio-inspired topologies provide wide-incident-angle absorption with bandwidths up to 31.64 GHz. Metasurfaces facilitate multiphysics functional integration. Despite the significant potential of MF-MMs in resolving broadband stealth and multifunctional synergy challenges via EM wave absorption, their practical application is constrained by several limitations: limited dynamic tunability, incomplete multiphysics coupling mechanisms, insufficient adaptability to extreme environments, and difficulties in scalable manufacturing and reliability assurance. Future research should prioritize intelligent dynamic response, deeper integration of multiphysics functionalities, and performance optimization under extreme conditions. Full article

The development of radiation-protective materials with high resistance under reactor irradiation conditions is one of the urgent tasks in modern nuclear technologies. Ultra-high molecular weight polyethylene (UHMWPE) is considered a promising matrix material due to its high hydrogen content, low density, and strong chemical resistance. Composite samples were fabricated by flame formation and irradiated in the IVG-1M research reactor of the National Nuclear Center of the Republic of Kazakhstan. Their neutron absorption capacity, bending strength, and chemical resistance were measured before and after irradiation. The results show that H₃BO₃ provides the strongest contribution to the increase in the neutron absorption coefficient, with the maximum effect observed at 30% filler content. Reactor irradiation caused only a moderate reduction in the composites’ bending strength. Chemical resistance tests confirmed that UHMWPE-based composites with WC and PbO retain stability in aggressive environments, even after reactor exposure. Overall, UHMWPE-based composites containing boron and heavy-element fillers demonstrate strong potential as radiation-protective materials. Their design should account not only for neutron absorption efficiency but also for mechanical strength and chemical resistance under reactor operating conditions. Full article

A damping spacer rod is a key protective device in ultrahigh voltage transmission lines, which not only keeps the distance of split wires and limits the whipping and collision caused by the relative motion between sub-wires, but also inhibits the vibration of wires. This study aims to solve the problem of typical faults, such as loose wire clamps, that are prone to occur in damping isolation rods during long-term operation in ultra-high voltage transmission lines. Taking the spacer rod FGZ-450/34B as the object, a new high-pressure casting process for spacer rod frames is explored. The spacer rods were simulated by using the ABAQUS finite element software to predict the stress distribution and identify the dangerous sections. Based on this, the mold process was optimized to avoid die-casting defects. Meanwhile, mechanical property tests were carried out on the products produced by the two types of molds. The research finds that by optimizing the mold process, the die-casting quality of the dangerous section of the spacer rod can be effectively improved, and the best high-pressure die-casting scheme has been obtained through comparison. This research achievement provides technical support for enhancing the anti-vibration performance, anti-loosening reliability, short-circuit current thermal shock resistance, and anti-ultraviolet aging performance of damping isolation rods. It is of great significance for ensuring the stable operation of ultra-high voltage transmission lines and improving the production process level of damping isolation rods. Full article

Ultra-high molecular weight polyethylene (UHMWPE) is widely used in orthopedic and prosthetic applications due to its excellent wear resistance and biocompatibility. However, its high molecular weight presents significant challenges in terms of processing and formability, particularly at the micro scale. This study investigates the flowability characteristics of a new melt-processable UHMWPE in micro-disc geometries to evaluate its suitability for advanced prosthetic applications. Micro-injection molding experiments assessed the material’s behavior under various thermal conditions. The influence of parameters such as temperature, pressure, and disc dimensions has direct effects on the flow behavior of UHMWPE and was analyzed by simulation and experiments. Results indicate that while UHMWPE exhibits limited flow under conventional conditions, optimized processing parameters can enhance discs’ formability without compromising the material’s structural integrity, avoiding defects. These findings provide critical insights for the microfabrication of UHMWPE thin components in next-generation prosthetic devices, enabling improved design precision and functional performance. Full article