Search Results (4,895)

Hybrid-electric propulsion and alternative energy carriers are being considered to mitigate the climate impact of short-range regional aviation. Within this framework, the HERA (Hybrid Electric Regional Architecture) project investigates advanced propulsion architectures for a next-generation 72 passenger regional platform. This work presents a cradle-to-grave Life Cycle Assessment of two HERA reference configurations and compares them with a conventional 70 passenger turboprop representative of current service aircraft. The analysis focuses on lithium–sulphur batteries, proton exchange membrane fuel cells, liquid hydrogen storage tanks, and electric motors. The assessment is implemented through a parametric LCA tool supported by a detailed Life Cycle Inventory based on Ecoinvent v3.8 and evaluated using ReCiPe 2016 midpoint indicators. The system boundary includes raw material extraction, manufacturing and assembly, operation under defined mission profiles, maintenance with component replacement, and End-of-Life (EoL) treatment. Results show that the operational phase remains the main driver of climate change impacts, exceeding 95% of total CO₂ equivalent emissions across configurations. The battery-based hybrid reduces fuel consumption but increases manufacturing and maintenance burdens. The fuel cell configuration shows a more balanced life cycle profile, with platinum identified as a critical hotspot. Full article

The crystal structure regulation of Ti₃O₅ by Al₂O₃ doping and its effect on the optical properties of TiO₂ films prepared by electron beam evaporation were systematically studied. Ti₃O₅ coating materials with different Al₂O₃ doping contents (0–50 at%) were prepared by vacuum melting, and the corresponding TiO₂ films were deposited on K9 glass substrates via electron beam vacuum evaporation. The phase structure, phase transition temperature, chemical composition and optical properties of the materials and films were characterized by XRD, DSC, EDS, XPS, UV-Vis and AFM. Results show that Al₂O₃ doping induces the phase transition of Ti₃O₅ from a room-temperature stable β-phase to a high-temperature stable λ-phase, with complete transition at 5 at% doping. Al³⁺ with a smaller ionic radius causes lattice contraction and local distortion of Ti₃O₅, enabling stabilization at room temperature of the λ-phase. For TiO₂ films, 12.5 at% doping is the optimal state with the stable composition transfer under this condition. With the increase in Al₂O₃ doping content, the refractive index and extinction coefficient of TiO₂ films decrease continuously, while the optical band gap and surface roughness show an increasing trend. The changes in optical properties are mainly ascribed to the low refractive index of Al₂O₃, lattice compressive strain effect and oxygen vacancy passivation induced by Al³⁺. This study clarifies the regulation effect of Al₂O₃ doping on Ti₃O₅ phase transition and TiO₂ film optical properties, and provides theoretical basis and experimental reference for the doping modification of TiO₂ films and their practical applications in consumer electronics and optical filter devices. Full article

The particle size of aggregate is a key factor affecting the mechanical properties and deformation capacity of cemented gangue filling body. In this study, coal gangue with a particle size range of (0.05, 20) mm was sieved into six groups of aggregate particles. Based on the Talbot gradation theory, cubic specimens with gradation indices n = 0.3, 0.4, 0.5, 0.6, and 0.7 were prepared for acoustic emission (AE) monitoring tests. The microstructure of the filling body was analyzed, and the failure characteristics and damage evolution laws of the cemented gangue filling body with different gradation indices were explored. The results show that the compressive strength reaches its maximum when n = 0.5. As the gradation index increases, the compressive strength of the specimens first increases and then decreases, and the specimens shift from primarily experiencing cleavage failure to shear failure. The curve of cumulative AE ringing count shows a bimodal distribution pattern, with both surge points and fracture points coexisting. The surge points can be regarded as precursor signals of backfill failure. The spatiotemporal evolution of AE events exhibits complex phased changes. An excessively small gradation index tends to form micropores and striped microcracks, reducing the compactness of the microstructure. An excessively large gradation index can lead to the formation of penetrative weak channels. A reasonable gradation index enables the mutual interlocking of aggregate particles, constructing a stable three-dimensional spatial skeleton structure. The dynamic trend of damage in the filling body can be captured based on AE analysis, and reverse guidance can be provided for parameter optimization of Talbot gradation, achieving a dynamic closed loop of “gradation design-AE monitoring-damage assessment-parameter optimization”. This not only enriches the application scenarios of acoustic emission analysis in graded materials, but also provides a new research approach and technical method for gradation design and safety assessment in scenarios where particle sizes are missing in practical engineering. Full article

This article presents a newly excavated Iron Age IIA cult room from Tel Lachish (Sanctuary BBE4) and examines its significance for the study of the organization of religious practice, situating this case within the broader corpus of Iron Age I–IIA local sanctuaries in Judah and the southern Levant. The evidence suggests that early Iron Age ritual practice was organized primarily at the level of extended kin groups, materialized in modest intramural cult rooms embedded within residential neighborhoods. These spaces reflect decentralized forms of religious authority, contrasting with the temple-centered ritual systems of the Bronze Age and with the increasing centralization of cult and religious authority in later phases of the Iron Age. By situating the Lachish evidence within a broader diachronic and regional framework, the study explores changing relationships between household ritual practices, kin-based social organization, and the development of state-level religious institutions in early Judah. Full article

The Late Jurassic–Early Cretaceous Oloy complex was formed in the setting of convergence between the Chukotka microcontinent and the Kolyma–Omolon margin. Its evolution reflects the closure of the South Anyui Ocean, with controversial timing estimates. This study emphasizes the integration of lithological data with magmatic and metallogenic information to reconstruct geodynamic processes. The article presents the results of detailed petrographic and geochemical studies, Sm-Nd isotope analyses, and U-Pb dating of detrital zircons from Kimmeridgian–Lower Hauterivian volcaniclastic and epiclastic sandstones. Petrographic studies and U-Pb dating of detrital zircons identified the main sources at different stages and the amount of synchronous pyroclastic material. Isotope-geochemical investigations suggest a young undifferentiated arc provenance for Kimmeridgian deposits, whereas Tithonian–Valanginian sediments accumulated due to the erosion of more differentiated igneous rocks and input of clastic material from the continent. New data on changes in sedimentation environments and provenance enabled the tracing of the evolution of the Oloy arc. In the Kimmeridgian, the Oloy island arc existed on a heterogeneous basement, with south-dipping subduction towards the Kolyma–Omolon margin. During the Late Tithonian, the arc accreted and magmatic activity continued in the active margin setting. Collision initiated in the latter half of the Berriasian, reaching its active phase in the Valanginian time. Full article

Reducing and managing emissions of mine waters and the minerals dissolved in them, and above all, using these wastes as resources, is an important element of sustainable development in regions undergoing a gradual phase-out of fossil fuel extraction. This article examines selected aspects of mine water management and the mineral substances contained therein, using the Polish hard coal mining industry as a case study, providing valuable insights for both Poland and other mining regions reducing raw material extraction regarding the sustainability of social water demand, mining sector restructuring, and Sustainable Development Goals (SDGs). In Poland, underground hard coal mining remains a significant source of mine water and mineral salt emissions. Mine waters, discharged into the catchments of major rivers (approximately 200 million m³ per year) along with their dissolved mineral compounds (approximately 1.5 million Mg per year), have repeatedly contributed to serious environmental disruptions, e.g., the phenomena of so-called “fish kill”. This study analyzes both the scale of emissions and the economic utilization of mineralized mine waters discharged to the surface by underground hard coal mining in Poland. Key processes and potential causes for the observed increase in environmental burdens are discussed. Furthermore, the paper presents a current statistical assessment of the trends and scale of emission changes, which can serve as a basis for environmental management decision-making amidst the decarbonization of the economy. Utilizing potential water resources and mineral compounds from mine waters for internal use or within circular economy applications can reduce environmental pressure, support compliance with sustainable development policies, and mitigate long-term impacts on post-mining regions. Full article

With increasingly stringent requirements for wear resistance and reliability of functional coatings for heavily loaded friction units, a relevant challenge in materials science is to establish the relationships between the parameters of reactive pulsed magnetron sputtering and the tribo-mechanical properties of TiN/CrN multilayer systems. In this study, TiN/CrN multilayer coatings were deposited by reactive pulsed magnetron sputtering using separate titanium and chromium targets. The effect of the nitrogen flow rate (0.20–0.36 L/h) during chromium sputtering on the structure, phase composition, and mechanical and tribological properties of the coatings was investigated at a fixed nitrogen flow rate of 0.08 L/h for titanium. SEM, EDS, and XRD showed that increasing the nitrogen flow rate leads to a non-monotonic change in coating thickness (2.0–2.6 µm), caused by the transition of the chromium target from the metallic to the poisoned sputtering mode. At low N₂ flow rates, a subnitride Cr₂N phase forms in the structure, whereas at the optimal flow rate of 0.32 L/h the coating consists of stable TiN, CrN, and (Cr_0.5Ti_0.5)N phases. The coating nanohardness was 20–23 GPa and the Young’s modulus was 250–300 GPa. The best tribological performance was achieved at a nitrogen flow rate of 0.32 L/h, coefficient of friction μ ≈ 0.5 and a minimum wear rate of 1 × 10⁻⁵ mm³/(m·N), which correlates with the highest H³/E² value. It is shown that independent control of the CrN layer stoichiometry using separate targets can affect the tribo-mechanical properties of the TiN/CrN multilayer system. Full article

Freeze–thaw damage significantly reduces the performance and durability of airport pavements in cold regions. Traditional assessment methods, such as the F300 freeze–thaw test, are time-consuming and hinder rapid optimisation of mix design. In addition, previous studies have mostly relied on long-term laboratory testing and have evaluated phase-change concrete (PCC) independently, without considering synergistic effects. These approaches lack fast, synergy-aware predictive capability and interpretable tools for mix proportion design, resulting in a gap between laboratory research and practical engineering applications. To address this issue, this study proposes an intelligent and explainable framework for predicting freeze–thaw damage and guiding mix design of steel fibre-reinforced phase-change concrete (SF–PCC). A boundary-controlled experimental programme was first conducted, varying steel fibre (SF) content from 0 to 1.2% and phase-change material (PCM) content from 0 to 12% under fixed mixture conditions. The freeze–thaw test results were recorded sequentially and used to construct a supervised learning dataset. Then, an XGBoost model was developed to predict two key durability indicators: relative dynamic modulus of elasticity (RDEM) and mass loss. SHAP (SHapley Additive exPlanations) analysis was further applied to quantify feature importance and interaction effects. The model achieved high predictive accuracy (R² = 0.9938 for mass loss and R² = 0.9935 for RDEM) under controlled experimental conditions. After 300 freeze–thaw cycles, the reference mix exhibited an RDEM of 61.2%, while optimised configurations showed improved performance. The economical design (9% PCM + 0.9% SF) achieved an RDEM of 66.8%, and the high-performance design (12% PCM + 1.2% SF) reached 72.6%. These results demonstrate that the proposed framework can effectively enhance durability and support rapid preliminary decision-making. The framework significantly accelerates freeze–thaw performance evaluation by enabling near-instant prediction and serves as an efficient supplementary tool for mix design optimisation alongside conventional laboratory testing. It also provides interpretable, data-driven insights for the design of freeze–thaw-resistant airport pavement concrete in cold regions. Full article

Reconfigurable antennas play a central role in next-generation wireless communication systems by enabling dynamic adaptation of operating frequency, radiation pattern, and polarization. Tunable metasurfaces have emerged as a powerful and compact approach to antenna reconfiguration, allowing electromagnetic wave manipulation through engineered, planar structures whose properties can be dynamically controlled. By embedding active devices or tunable materials within metasurface unit cells, antenna characteristics can be modified without altering the antenna geometry. This review provides a comprehensive overview of reconfigurable antennas enabled by tunable metasurfaces. We adopt a functionality-based classification that focuses on operating frequency, radiation pattern, polarization, and multifunction reconfiguration. An overview of major tunability technologies, including PIN diodes, varactors, MEMS, graphene and two-dimensional materials, and liquid crystal (LC) or phase-change materials, is first presented. Subsequently, metasurface-based reconfiguration strategies are discussed and compared for each antenna functionality, highlighting design principles, practical trade-offs, and limitations. The review concludes with an assessment of challenges and future research directions relevant to next-generation wireless communications and beyond. Full article

Objective: This in vitro study aimed to compare the layer-matched color compatibility of three 3Y/4Y/5Y multilayer zirconia grades marketed in shade A2. Materials and Methods: Disc specimens (18 mm × 1.5 mm) were milled from pre-shaded multilayer zirconia blanks (Katana™ Multi-Layered Zirconia; Kuraray Noritake Dental Inc., Tokyo, Japan) in three grades: UTML (5Y), STML (4Y), and HTML (3Y). Twelve discs per grade were polished and measured on a neutral-gray background (Munsell N7) using a dental spectrophotometer (VITA Easyshade Advance 4.0; VITA Zahnfabrik, Bad Säckingen, Germany) at the incisal, middle, and cervical thirds. Color differences were calculated using CIEDE2000 (ΔE₀₀). Yttria content (wt%) was determined using EDS (JSM-7800F; JEOL Ltd., Tokyo, Japan), and phases were assessed using XRD (X’Pert PRO; Malvern Panalytical, Almelo, The Netherlands); microstructure and grain size were examined using FE-SEM after thermal etching. Statistics: A two-way mixed-design ANOVA with Bonferroni adjustment (α = 0.05) was conducted. Results: A significant incisal-to-cervical gradient was observed within each grade (p < 0.001), whereas layer-matched inter-material differences were small (all ΔE00 < 1.0), i.e., below the commonly accepted perceptibility threshold. EDS confirmed the expected stepwise decrease in Y₂O₃ from UTML to HTML, accompanied by corresponding changes in phase constitution and grain size. Conclusions: Despite compositional and microstructural differences, the three multilayer zirconia grades showed no clinically perceptible layer-matched color differences, supporting their combined use in extended rehabilitations while maintaining the natural-like color gradient across the multilayer blank. Full article

This study presents the results of research on the modification of gypsum with bio-waste to improve its thermal insulation properties and to evaluate the influence of the type and amount of the additive on the physical, mechanical, and microstructural properties of the composite. Various fractions of plant-based bio-waste were used in amounts ranging from 0.75 to 10% by weight. The thermal conductivity coefficient and thermal diffusivity were determined. Additionally, analyses of dimensional stability over time, visual appearance, and phase distribution uniformity were conducted. Mechanical tests included surface hardness measurements. In order to determine the material’s durability, water absorption and frost resistance tests were performed, and structural changes and properties after these cycles were analyzed. It was found that selecting the appropriate type and proportion of additive makes it possible to obtain composites with a favorable balance between thermal insulation, dimensional stability, and mechanical performance. The conducted research confirms the potential for effective use of bio-waste as a gypsum-modifying raw material, contributing to the development of sustainable building materials with a reduced environmental footprint and improved functional parameters. Full article

Diffractive optical elements with a trigonometric phase dependence on radius are considered. They allow the formation of multiple local light segments on the optical axis. The dependence of the focal distribution on the optical element parameters is studied analytically and numerically. It is shown that by varying the parameters, both the positions and relative magnitudes of the foci can be independently changed. A detailed comparison of a sinusoidal lens with a parabolic one is performed. Binarization of a sinusoidal lens leads to non-obvious effects: this process does not create new foci, but significantly changes the energy distribution between the foci. In particular, the intensity can increase at positions where the focal magnitude was very small before binarization. Moreover, the trigonometric elements have very interesting chromatic dispersion features: changing the wavelength leads to significant variations in the ratio of the focal energies, which is not typical of parabolic lenses. The obtained results are promising for the field of multiplexing optical information transmission channels, increasing the depth of focus, laser material processing and optical trapping. Full article

In this study, commercial Ospray-2507 super-duplex stainless steel powder was investigated for the first time as a potential metal support material for solid oxide cells. Initially, metal supports were fabricated and processed in air using various sintering profiles, followed by comprehensive mechanical, structural and electrochemical characterization. The optimal sintering condition was identified as 900 °C for 5 h. Subsequently, sintering under a H₂ atmosphere was explored, and its effects on the microstructural and functional properties of the metal supports were systematically to assessed to evaluate the influence of the sintering atmosphere on material performance. Although X-ray diffraction patterns showed no phase changes between the two sintering atmospheres, notable improvements were observed in mechanical, electrochemical, and microstructural properties under H₂ sintering. XPS spectra reveal that both air- and hydrogen-treated surfaces remain rich in chromium (Cr) and Manganese (Mn), which together dominate the surface and consequently attenuate the signal from the underlying iron. The thickness of the Cr- and Mn-based oxide layer decreases when sintering MS in H₂ atmosphere. Specifically, mechanical strength, as measured by three-point bending tests, increased by a factor of 12.5, and hardness rose from 500.3 to 523.5 HV. Furthermore, electrical conductivity also improved significantly, exhibiting an approximately 2.3–2.4 fold increase under H₂-sintered conditions. Full article

This paper presents a quantum system designed to generate random, phase-manipulated emissions. A key feature of the proposed system is its ability to create a controllable electromagnetic center. To achieve this, the architecture utilizes two synchronized sources positioned at distinct spatial locations. A method is introduced where Quantum-generated keys are used to form a random sequence in real time to control digital phase manipulators. A block diagram of a quantum system for generating random phase-manipulated emissions with a controllable electromagnetic center has been developed that enables control of the main operating frequency, the length of the additionally generated random sequences controlling the modulations, the frequencies and phases of the emissions, the period and start of phase manipulations, as well as the power of the signals emitted by each of the channels. This way ensures uniformity or a controllable difference in the signals emitted by the two sources of the system upon their arrival at a predetermined point in space. A laboratory prototype of the quantum system has been developed, and tests have been conducted to confirm the feasibility of the proposed method and block diagram. The proposed research refers to a case of phase manipulation of transmitted signals with a preset clock frequency. The theoretical and technical solutions presented in the material can also be used to create systems with randomly frequency-manipulated signals, as well as systems in which the manipulation periods change randomly, determined by random quantum keys generated in real time. Full article

Phase change thermal storage fibers with high latent heat have attracted significant attention in thermal management and heat storage. Through fiber encapsulation, shape-stable phase change materials can be prepared, thereby expanding their applications. In this study, electro-blown spinning was utilized to prepare phase change materials (PCM) using erythritol, with polyethylene oxide (PEO) as the carrier material. Coaxial thermal storage fibers encapsulating the phase change materials were prepared using polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP). The results indicate that the composite fibers have a smooth surface, uniform and smooth morphology, a maximum latent heat of 223.01 J/g, as well as excellent thermal stability. The coaxial fibers exhibit a distinct core–shell structure, with the coaxial fibers encapsulated with PVA as the shell material, demonstrating a high latent heat of 118.62 J/g, a residual rate of 93.81% after heating, and excellent thermal performance. The encapsulation efficiency is 53%, effectively addressing the issue of erythritol leakage. The research results provide valuable guidance for the efficient preparation of erythritol coaxial thermal storage fibers. Full article