Search Results (13,525)

Multifunctional manipulation of optical fields with multiple degrees of freedom is essential for integrated photonic systems, yet achieving coordinated and independent control of polarization and phase remains challenging. Here, we propose a polarization-tunable multifocal metalens enabled by a bilayer metasurface with integrated polarization rotation. By introducing the interlayer rotation angle difference as an additional degree of freedom, a rigorous theoretical framework is established, revealing that the transmitted polarization undergoes a deterministic rotation equal to twice the interlayer rotation difference while preserving its ellipticity. Under circularly polarized incidence, the polarization state remains unchanged, with only geometric phase modulation induced. This mechanism enables a continuous and predictable mapping between input and output polarization states. By further incorporating an independent propagation phase via selected nanopillars, polarization and phase can be engineered independently within a unified framework. Based on this strategy, a polarization-tunable multifocal metalens is numerically demonstrated, generating multiple focal spots with distinct and switchable polarization states at predefined positions. The polarization state at each focus can be tuned solely by varying the incident polarization angle, without modifying the device structure. This work provides a versatile and physically intuitive strategy for multifunctional metasurface design and integrated photonic applications. Full article

The theory of partially coherent image formation in dark-field and phase-contrast microscopy is presented. Explicit expressions and three-dimensional plots of the transmission cross-coefficient for different imaging modes are given. These include central and oblique internal dark field, annular dark field, phase contrast, differential phase contrast using semicircular or quadrant condenser pupils, and differential interference contrast. Explicit expressions are given for the image intensity for pure-phase objects consisting of a single-object spatial frequency or combinations of object frequencies. Full article

Although amorphous calcium phosphate (ACP) has been extensively employed as a biomaterial in dental and orthopedic fields, its exploration for environmental applications—particularly in potentially toxic element remediation—remains notably limited in the scientific literature. This study reports the rational design of a multifunctional adsorbent by integrating sodium citrate-stabilized ACP (Cit-ACP) nanoparticles into calcium-crosslinked sodium alginate (SA) hydrogel beads for selective Cu²⁺ sequestration from aqueous systems. Comprehensive sorption assessments revealed that equilibrium uptake aligned with the Freundlich isotherm (indicating heterogeneous surface interactions), while kinetic profiles adhered to pseudo-second-order behavior, characteristic of chemisorption-driven processes. Under optimized operational parameters (pH 5.0, 45 °C), the Cit-ACP/SA composite attained an exceptional maximum adsorption amount of 307.76 mg/g. Thermodynamic analysis further confirmed the spontaneity (ΔG° < 0) and endothermic nature (ΔH° > 0) of the process. Multi-technique characterization (XPS, FTIR, XRD, pH trajectory) elucidated a dual-mode adsorption mechanism: (i) ion exchange between aqueous Cu²⁺ and structural Ca²⁺ within both the alginate matrix and ACP framework; and (ii) in situ surface precipitation yielding copper-substituted hydroxyapatite. Owing to its facile aqueous-phase synthesis, superior adsorption performance, biodegradability, macroscopic bead morphology enabling rapid separation, and robust selectivity in complex matrices, the Cit-ACP/SA composite presents a sustainable, scalable, and eco-compatible platform for practical remediation of copper-contaminated wastewater. Full article

Polymer microsphere flooding is an effective enhanced oil recovery (EOR) technology. Its primary mechanism is characterized by a dynamic cycle of “migration, plugging, breakthrough, and remigration”, which enables effective in-depth profile control and selective plugging. However, constructing accurate mathematical models and obtaining stable numerical solutions for this process remain challenging. Based on the black-oil framework, a three-phase, five-component mathematical model is developed for water-microsphere dispersed system, including oil, gas, water phases and two microsphere components (pre-swollen and post-swollen), and accounting for swelling kinetics, adsorption, and water phase permeability reduction. The model is numerically solved using a fully implicit finite-difference scheme, and validated by numerical tests and a field-scale application. The numerical simulation results demonstrated an overall agreement rate of approximately 85% with experimental data. Mechanistic comparisons indicated that polymer microsphere flooding significantly improves sweep efficiency and oil recovery. Field-scale application further showed that polymer microsphere flooding, compared with conventional water flooding, increases the recovery factor by 3.49 percentage points, reduces the maximum water cut by about 9.34 percentage points, and raises the average daily oil production rate over the entire development period by 7.5 m³. The proposed model can provide theoretical basis for the field application of polymer microsphere flooding for in-depth profile control. Full article

Metal accumulation in cacao (Theobroma cacao L.) cultivation represents an important agronomic and food-safety concern, particularly in acidic tropical soils where cadmium (Cd) and other trace metals can become bioavailable and translocate to plant tissues. Green magnetic nanomaterials offer a potential strategy for reducing metal mobility in agricultural substrates, but their performance depends on surface chemistry, dose, and plant genotype. In this study, we synthesized and evaluated MCRES, defined here as a maghemite–Citrus reticulata extract system, a biofunctionalized γ-Fe₂O₃-based nanosystem prepared by coupling iron oxide nanoparticles (NPs) with a 3% (w/v) Citrus reticulata peel extract. The objective was to determine whether citrus-mediated biofunctionalization could produce a scalable magnetic nanoamendment capable of modifying Cd and naturally occurring Ni partitioning in cacao seedlings. MCRES was recovered magnetically and dried, yielding 8.44 g of product from 10 g of precursor. Rietveld analysis performed in X ray diffractograms confirmed phase-pure cubic γ-Fe₂O₃ with a lattice parameter of 0.8332 nm, a crystallite size of 11.3(1) nm, and satisfactory refinement quality (χ² ≈ 1.34). Transmission electron microscope images showed quasi-spherical NPs with a log-normal size distribution centered at 7.5 nm. Magnetic measurements showed superparamagnetic-like behavior at 300 K, high saturation magnetization values of 62 emu g⁻¹ at 300 K and 71 emu g⁻¹ at 5 K, and elevated effective anisotropy values obtained from the Law of Approach to Saturation fitting. MCRES was applied at 0, 1, 2, 4, and 6 g pot⁻¹ to cacao seedlings containing Cd-amended Ultisol with naturally occurring Ni. Plant responses were genotype and dose dependent: TSH-1188 genotype showed limited dose sensitivity for most biometric variables, whereas ICS-95 genotype showed significant dose effects, with maximum growth at the 2 g pot⁻¹ treatment. Metal-partitioning results indicated that Cd remained comparatively mobile toward shoots, whereas Ni was preferentially retained in roots. In TSH-1188 genotype, the Ni translocation factor decreased from 3.07 in the control to 0.85–1.00 at higher MCRES doses. Compared with previous work on non-biofunctionalized nanomaghemite, these results suggest that citrus-mediated biofunctionalization produces a distinct Cd/Ni partitioning response. Overall, MCRES is recommended as a promising nursery-scale green nanoamendment for reducing metal mobility in cacao cultivation, but its agronomic use should be optimized according to genotype and dose. Future work should include side-by-side comparisons with unfunctionalized γ-Fe₂O₃, Citrus reticulata extract alone, and non-contaminated controls under field conditions to validate its long-term effectiveness and environmental safety. Full article

Double-wall drill pipe reverse circulation drilling is expected to alleviate cutting-transport difficulties and the high risk of lost circulation during the shallow-section drilling of ultra-deep wells. Based on wellbore hydraulics theory and a transient solid–liquid two-phase flow model in the wellbore, considering the flow path transition effect at the reverse circulation converter near the bit, a corrected pressure loss method for the inner pipe accounting for cuttings influence is proposed, and a correlation for calculating the converter pressure loss is derived. A wellbore pressure calculation model for reverse circulation drilling using a double-wall drill pipe is then established. Furthermore, the influencing factors are investigated through sensitivity analysis, and a pump pressure selection chart is developed. Field-case calculations indicate that, under identical operating conditions, the bottomhole pressure in double-wall drill pipe reverse circulation drilling is reduced by approximately 6.31 MPa compared with conventional drilling. For shallow sections (well depth of about 1200 m) under flow rates of 20–40 L/s and drilling-fluid densities of 1200–1400 kg/m³, the maximum total circulating wellbore pressure loss, after incorporating surface flowline pressure losses, is approximately 10.91 MPa. In this case, a single pump can satisfy the circulation requirement, demonstrating the advantages of simplified equipment configuration and improved field adaptability for shallow-section operations. The proposed model and charts can provide a reference for parameter optimization and pressure-control design in double-wall drill pipe reverse circulation drilling. Full article

The dominance of inexpensive ferrites and high-performance rare-earth-based magnets on the global market causes a significant performance gap between these materials. Fe${}_2$P-based materials are promising rare-earth-free candidates to bridge this gap, offering high magnetization and uniaxial anisotropy. In this study, density functional theory was employed to systematically analyze the influence of Si and Co substitution on the phase stabilities of such Fe${}_{2-y}$Co${}_y$P${}_{1-x}$Si${}_x$ compounds. At 0 K, Si substitution destabilizes the compounds; however, this trend is reversed at elevated temperatures, where Si significantly enhances phase stability. In contrast, Co substitution reduces competition energies at 0 K but promotes instability with increasing temperature. For quaternary Fe${}_{2-y}$Co${}_y$P${}_{1-x}$Si${}_x$ compounds, the combined presence of Si and Co leads to a pronounced expansion of the stability range of the hexagonal crystal structure, in reasonable agreement with available experimental observations. Starting from temperatures above 1000 K, several quaternary compounds exhibit negative competition energies, indicating thermodynamic stability. Among all investigated compositions, Fe${}_{1.84}$Co${}_{0.16}$P${}_{0.84}$Si${}_{0.16}$ stands out, combining particularly low competition energies with a previously reported mean-field Curie temperature of 557 K and a high magnetic hardness factor. These results identify Fe${}_{1.84}$Co${}_{0.16}$P${}_{0.84}$Si${}_{0.16}$ as a highly promising rare-earth-lean hard magnetic material for future applications. Full article

Background/Objectives: Although creatine monohydrate is widely recognized as an effective ergogenic aid in strength and power sports, its role in endurance and mixed-sport disciplines remains less clearly established. This scoping review aimed to map the current evidence regarding the effects of creatine supplementation on performance, recovery-related outcomes, and body composition in endurance and mixed-sport contexts. Methods: A scoping review of randomized controlled trials published between 1996 and 2025 was conducted. Eligible studies evaluated creatine supplementation in endurance and mixed-sport contexts, including both sport-specific and broader exercise populations when the exercise protocol, testing model, or outcomes were relevant to endurance or mixed-sport performance, recovery, or body composition. A total of 38 studies met the inclusion criteria. Outcomes were categorized into exercise performance, biochemical markers related to recovery and exercise stress, and body composition parameters. Results: Creatine supplementation was most often associated with reported favorable changes in repeated-sprint performance and high-intensity power output, particularly during intermittent, sprint-based, or power-endurance tasks. Several studies reported favorable changes in sprint performance, peak power, or total work output relative to placebo or baseline values in cycling, swimming, rowing, and canoeing/kayaking protocols, although findings were not uniform across studies and not all favorable within-group changes were placebo-superior. Some studies also reported favorable changes in end-phase sprint capacity during prolonged exercise. Findings related to recovery were less consistent. Selected studies reported reductions in inflammatory markers, including C-reactive protein (CRP) and tumor necrosis factor α (TNF-α), whereas markers of muscle damage showed mixed responses. Most supplementation protocols involved a 5–7-day loading phase of 20 g/day, occasionally followed by a maintenance dose of 2–5 g/day. Small increases in total body mass were commonly observed, while evidence regarding fat-free mass and aerobic outcomes remained limited or inconsistent. Conclusions: Current evidence suggests that creatine supplementation may be most relevant in selected endurance and mixed-sport contexts involving repeated high-intensity efforts, sprint finishes, or power-endurance demands, rather than for endurance performance broadly. In contrast, evidence for recovery-related biochemical responses, body composition changes, and aerobic adaptations remains equivocal. Further well-controlled, sport- or context-specific, and field-based studies are needed to better clarify the role of creatine in endurance and mixed-sport exercise. Full article

Research on trauma in autistic individuals has proliferated in recent years. This scoping review aims to (1) provide a comprehensive overview of the literature on trauma and autism, (2) identify and synthesize key themes, and (3) highlight gaps to inform future research. Following Arksey and O’Malley’s (2005) methodological framework and the PRISMA-ScR guideline and checklist (Tricco et al. 2018), we included articles published after 2000 in French or English that explicitly addressed trauma in autistic individuals. Four databases were searched: PsycINFO, Medline, ERIC, and Web of Science. A two-phase selection process yielded 199 eligible studies. Descriptive analyses and collaborative theme development were conducted to map the field. Findings show that most studies were published between 2018 and 2024, with the United States contributing the largest proportion. Four major themes were identified: (1) the relationship between autism and trauma, including prevalence, vulnerability, and consequences; (2) trauma-related symptoms and clinical manifestations; (3) assessment practices; and (4) intervention strategies. This review offers a critical synthesis of current knowledge, emphasizing the need for approaches that use broader definitions of trauma and reflect the diversity and lived experiences of autistic individuals. It also identifies significant methodological and conceptual gaps, calling for future research that addresses subgroup diversity and promotes equitable, trauma-informed practices for autistic individuals. Full article

In biomass pellet combustion, the formation of ash layers on particle surfaces severely hinders combustion reactions and heat transfer, while the key parameters governing particle motion behavior and ash pre-separation in rotating cone burners remain insufficiently understood. To address these challenges and to optimize particle mixing and ash separation performance, this study adopts a combined numerical approach. The discrete element method (DEM) coupled with the Hertz–Mindlin (no-slip) contact model is employed to simulate particle motion and mixing dynamics, while a separate cold-state computational fluid dynamics (CFD) model based on the Realizable k-ε turbulence model and the discrete phase model (DPM) with Rosin–Rammler particle size distribution is established to investigate ash separation mechanisms. The Lacey mixing index is used to quantify mixing uniformity, and grid independence verification is performed to ensure numerical reliability. Key findings reveal that the rolling regime (rotational speed: 1.7–11 r/min), a uniform particle size of 25 mm, and a cone inclination angle of 45° collectively optimize particle mixing. Rotational speed is identified as the dominant factor affecting mixing effectiveness. Furthermore, an optimal secondary-to-primary air ratio of approximately 7:3 (within the tested range) balances enhanced centrifugal separation with flow field stability by mitigating backflow and excessive turbulence. This work not only fills the knowledge gap regarding the coupled effects of operational and structural parameters on particle behavior in rotating cone burners but also provides novel, quantitative guidance for the rational design and parameter tuning of such burners to improve combustion efficiency and operational stability. Full article

Injecting CO₂ into gas reservoirs is a crucial approach for enhancing natural gas recovery and achieving CO₂ geological storage, where the gas–gas diffusion behavior between CO₂ and CH₄ directly influences gas mixing efficiency. Direct observation of the spatiotemporal evolution of concentration fields during diffusion remains insufficient. In this study, a gas–gas diffusion experimental system capable of multi-time and multi-space stratified sampling within a high-temperature high-pressure PVT cell was established based on real reservoir fluid compositions. Non-equilibrium diffusion experiments were conducted under different pressures, different initial CO₂ mole fractions, and different diffusion times. A diffusion model was developed according to Fick’s second law. The results suggest that the gas column can be divided into a natural gas zone, a transition zone, and a CO₂ zone by the dimensionless concentration gradient threshold. At 5 MPa, the transition zone width expands rapidly within the first 4 h (dimensionless width increases from 0 to 0.6902), after which growth slows. Increasing pressure significantly inhibits diffusion, reducing transition zone width and prolonging equilibration time. Rising initial CO₂ concentration also suppresses diffusion mixing, particularly in the later stage. Component profile analysis confirms that, under high pressures and high CO₂ concentrations, the diffusion flux across the interface is weakened. Compared to CH₄, the diffusion equilibration time of CO₂ is shorter and more sensitive to pressure changes. The obtained diffusion coefficients (CH₄: 2.92 × 10⁻⁸ to 4.79 × 10⁻⁸ m²/s; CO₂: 3.91 × 10⁻⁸ to 6.08 × 10⁻⁸ m²/s) are on the order of 10⁻⁸ m²/s, consistent with bulk-phase PVT literature data, validating the reliability of the experimental method and inversion model. This study lays an experimental foundation for predicting multi-component gas mass transfer under conditions of CO₂-enhanced gas recovery and CO₂ geological storage. Full article

This investigation examines the decline in breaking performance observed in 550 kV high-speed circuit breakers, tracing the cause to insufficient coordination between the operating mechanism and the arc-extinguishing chamber. It proposes a coordinated adjustment of the buffer strategy mechanism and the structural parameters of the arc-extinguishing chamber, revealing their interaction under high-speed opening conditions. To address the impact loads and unstable airflow field during the mechanism’s high-speed opening, the buffer strategy was revised by increasing the gaps in the first four steps by 0.3 mm and 0.5 mm in two respective optimization schemes. Set the step size to 3 mm, and assign a decrease of zero for each of the final three steps. A 1 mm gap reduces the pressure drop near the end of the opening phase. The axial airflow velocity and the breaking performance were compared at the moment of 1 ms before current zero for three nozzle throat lengths (L_u): 22 mm, 27 mm, and 32 mm. Nozzle throat length has a clear effect on the main parameters of short-arc quenching. With a 27 mm throat length, the measured values remain relatively high. The proposed length scheme achieves a balanced trade-off between the airflow velocity distribution and the efficiency of arc cooling. Downstream of the nozzle, the axial airflow velocity is 18% higher than in the 32 mm scheme, and the pressure decays 22% more slowly than in the 22 mm scheme. This improves heat removal from the arc and shortens the short-arc phase to under 6 ms. Prototype tests provided by the manufacturer indicate that the circuit breaker with a 27 mm nozzle throat can achieve a minimum arcing time of approximately 6 ms, which is consistent with the simulation prediction. Full article

The three-phase region of Mo₃Si-Mo₅Si₃-Mo₅SiB₂(MoSiB) exhibits excellent high-temperature oxidation resistance and is considered a highly promising high-temperature structural material. However, the presence of porous structures significantly increases the surface area exposed to oxidation. Metallic porous materials often suffer from inadequate corrosion resistance and insufficient high-temperature oxidation resistance, whereas ceramic porous materials are plagued by high brittleness. Intermetallic compounds offer a combination of the advantages of both metals and ceramics. Nevertheless, the high-temperature oxidation behavior of porous MoSiB has not yet been systematically elucidated. The study systematically investigates the effect of pore structure on the high-temperature oxidation behavior of porous MoSiB at 1000 °C and 1300 °C, with a focus on oxidation kinetics, phase evolution, surface and cross-sectional morphology and underlying oxidation mechanisms. The effects of porosity and temperature on the oxidation process are also analyzed. The results indicate that at 1000 °C, the material exhibits uniform oxidation, with lower porosity contributing to better oxidation resistance. At 1300 °C, oxidation is limited to the surface layer, where low-viscosity SiO₂(B) rapidly seals the pores to form a dense protective layer. This research reveals the high-temperature oxidation mechanism and phase evolution of porous MoSiB, providing a theoretical foundation for its application in high-temperature structural fields. Full article

Railway traction power supply systems (TPSSs) are evolving from passive grid-fed infrastructures into active energy systems with local photovoltaic (PV) generation capacity, energy storage systems (ESSs), and converter-based regulation. Unlike conventional microgrids, TPSSs feature single-phase, highly dynamic traction loads; short-duration regenerative braking bursts; and strict constraints on voltage quality, stability, and protection. These characteristics make the energy management of distributed PV-storage-integrated TPSSs a distinct research problem. This review examines the field from three coupled perspectives: supply architecture, power electronic interfaces, and energy management strategies. First, representative integration architectures are classified into substation-side, wayside-distributed, and hybrid multi-port schemes. Second, converter interfaces and flexible traction substations are analyzed as the enabling layer for coordinated control of PV, ESS, the utility grid, and traction feeders. Third, major energy management strategies, including rule-based, optimization-based, hierarchical multi-timescale, and uncertainty-aware methods, are compared. The review further discusses power quality, stability, protection, and battery degradation constraints that shape practical deployments. Finally, research gaps and future directions are identified to further the development of more robust, railway-specific, and implementation-oriented PV-storage energy management. Full article

At present, constructing discrete chaotic systems with unique characteristics and chaos has become a focal topic in the field of nonlinear research. This paper presents a new framework for designing multi-cavity chaotic maps in polar coordinates. It constructs the basic chaotic map through nonlinear curves (such as Lotus curve, rose curves, and star curves) and generates multi-cavity attractors based on modular arithmetic. The nonlinear curves introduce complex deformations in the angular and radial components, while modular arithmetic serves as a folding mechanism to confine the dynamics to a specific range. The combined effect of these two elements forms multiple clearly separated chaotic cavities in the phase space. The number, size, shape, and chaotic characteristics of the cavities can be flexibly controlled by parameters. However, the introduction of fractional-order difference operators will disrupt the multi-chamber structure and make the system more complex. Furthermore, a data-hiding scheme based on the cavities is developed: the cavities act as natural isolation containers to embed information bits, and the chaotic dynamics provide encryption and confusion mechanisms. Experiments show that the designed chaotic map has high complexity and rich bifurcation behaviors; the data-hiding scheme performs well in terms of embedding capacity and security. Full article