This study presents an experimental investigation into the influence of a step on the detachment characteristics of a supersonic Coanda jet. A parametric analysis was conducted by systematically varying the Coanda surface radius, jet outlet height and step height. Flow morphology was captured using high-speed schlieren and shadowgraph visualisation, while the critical nozzle pressure ratio ($\textit{NPR}$) for jet detachment was precisely measured with pressure transducers. For the baseline configuration without a step, the detachment $\textit{NPR}$ (denoted $\textit{NPR}$d) was predicted by a macroscopic mechanical model balancing centrifugal force and the radial pressure gradient, confirming a power-law relationship with the geometric ratio. The introduction of a step revealed a novel ‘step stall’ phenomenon: while increasing the step height initially enhances attachment and raises $\textit{NPR}$d by simplifying wave structures and suppressing separation bubbles, a further increase beyond a critical optimal value causes a sharp drop in performance. This optimal step height, which maximises the detachment $\textit{NPR}$, is shown to have a linear relationship with the normalised Coanda radius. The phenomenon is explained by the ineffective wall–jet interaction when an excessive step height prevents the jet’s core from being effectively ‘grabbed’ by the curved surface. These findings provide critical insights and practical design guidelines for optimising the Coanda effect in advanced flow control applications.

Methanol- and ethylene glycol-grafted kaolinite were prepared via a stepwise intercalation–grafting strategy using dimethyl sulfoxide-intercalated kaolinite as an intermediate, with the aim of elucidating the structural differences between the two grafted products and clarifying the role of interlayer water. The products were systematically characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR), elemental analysis (CHNS) and thermogravimetry–differential scanning calorimetry (TG–DSC). Compared with methoxy-modified kaolinite, the ethylene glycol-grafted kaolinite exhibited enhanced structural ordering, greater organic loading and improved thermal stability. The covalently grafted ethylene glycol molecules adopt a trans configuration in the interlayers of kaolinite, accompanied by a minute fraction of non-bonded ethylene glycol molecules and some amount of interlayer water molecules. Although the confined water in both systems originated from condensation reaction, it probably played opposite roles: it facilitated the ethylene glycol grafting while hindering that for methanol.

The Endangered Great Bustard Otis tarda dybowskii utilises the agricultural landscapes of Cangzhou, North China Plain, for its overwintering period. However, their daytime habitat utilisation and diurnal behavioural rhythms remained undocumented. Employing 205 presence records collected over three winters (2019–2022) and 1,254 minutes of continuous video footage in 2022, our study reveals that birds used low-stature crop cover: 56.6% of locations were in winter wheat fields and 38.1% in maize stubble, while fallow land accounted for only 5.4%. From continuous focal-group video sampling, foraging (44.7%) and resting (standing 30.4%, lying 8.7%) dominated the daytime activity budget. Behaviour varied significantly among five two-hour blocks (07:30–17:30): resting peaked at 07:30–09:30, and foraging remained active in the evening (15:30–17:30), when flocks generally entered a large-scale and rapid foraging state. Based on these patterns, we propose a practical management approach that prioritises maintaining low-stature winter croplands and implementing seasonal, low-conflict disturbance reduction around repeatedly used fields, with emergency-only supplementary feeding during extreme snow/ice events. Embedding such measures into local agri-environment policy may help secure key overwintering habitat for Great Bustards and other farmland-dependent migratory birds.

Virtual reality (VR) is a transformative technology for studying language processing and learning. It offers realistic and naturalistic environments while maintaining experimental control, supporting the exploration of social and sensorimotor cues that have often been overlooked in traditional psycholinguistic research. It can also be integrated with behavioral and neurocognitive measures to examine how learning processes influence learning outcomes. These VR characteristics have brought new opportunities and contributed to the expansion of theoretical frameworks on language processing and learning. Through reviewing recent empirical findings, we establish VR as a novel methodology for investigating how embodied and social experiences shape language processing and learning. We emphasize that realizing this potential fully requires real-time multimodal tracking of learning processes, systematic examination of individual differences and development of richer virtual environments and VR-suitable assessment tasks. This review provides methodological insights for future VR research on the neurocognitive bases of language processing and learning.

We numerically investigate the propulsion of a two-dimensional compliant membrane executing prescribed harmonic heave in the near wake of a stationary circular cylinder at Reynolds number $\textit{Re}=3000$. Using a partitioned high-fidelity fluid–structure interaction solver with nonlinear iterative force correction, we map the coupled response over $A^* \in [0.05,0.5]$ and $f^* \in [0.1,0.6]$, where $A^*$ is dimensionless flapping amplitude and $f^*$ is dimensionless flapping frequency. The parameter sweep reveals a sharp transition in the force maps from weakly forced, wake-following behaviour to a high-performance regime in which cycle-averaged lift and lift-to-drag increase abruptly. This transition coincides with intermittent exposure of the membrane to higher-momentum fluid and a pronounced amplification of deformation. A frequency-resolved analysis, combined with a body-frame Fourier mode decomposition of the flow, identifies four distinct flapping states, namely a wake-dominated state, two flapping-dominated states associated with lift reduction and lift gain and a two-way lock-in state. In the latter, vortex shedding locks onto the imposed actuation, while the first fluid-loaded structural mode approaches the actuation frequency, producing selective amplification of low-order deformation. The resulting curvature-induced camber intensifies leading-edge suction and increases the cross-membrane pressure difference, establishing feedback that reorganises upstream shedding. Motivated by these mechanisms, we derive scaling relations for the cycle-averaged lift, drag and power that separate quasi-steady motion, added-mass effects, curvature-induced contributions, wake-momentum deficit and transverse shear. For the present reference compliance, the scaling clarifies how flexibility is detrimental when the membrane remains fully immersed within the wake core, yet beneficial when intermittent wake exposure permits passive camber amplification to offset momentum deficit with limited drag penalty. These results provide a mechanistic framework for the present reference-compliance configuration and identify how wake exposure, imposed heaving and membrane response combine to produce two-way lock-in.

Vortex-induced vibration forever (VIVF) is classically associated with a single elastically mounted cylinder, for which oscillations persist at infinite reduced velocity when the mass ratio ($m^*$) falls below a critical value ($m_{cr}^*$). The existence and characteristics of such permanent vibration under unsteady wake conditions remain unclear. This study investigates the vibration response of an extreme-light cylinder placed in the wake of an upstream fixed cylinder without restoring forces, with particular emphasis on the existence and variation of a critical mass ratio $m_{cr}^*$ with the spacing ratio ($L/D$). The Reynolds number is set to 60, the mass ratio $m^*$ ranges from 0.2 to 14 and the spacing ratio $L/D$ ranges from 1.1 to 6.0. Three vibration regimes are identified in the $(L/D,\, m^*)$ parameter space: non-vibration (NV), limited-range vibration (LRV) and infinite-range vibration (IRV). A critical mass ratio $m_{cr}^*$ emerges at the LRV–NV boundary, where the vibration amplitude continuously diminishes to zero as $m^*$ approaches $m_{cr}^*$, in contrast to the abrupt transition observed in single-cylinder VIVF; this extinction coincides with the disappearance of the second-order flow mode. Furthermore, $m_{cr}^*$ is governed by the spacing ratio relative to the vortex formation length $L_{\!f}/D$ of a stationary cylinder: when $L/D \lt L_{\!f}/D$, $m_{cr}^*$ increases with $L/D$, whereas for $L/D \gt L_{\!f}/D$, it decreases with further increase in $L/D$. In contrast, within the IRV regime the flow maintains persistent co-shedding behaviour and no critical mass ratio is observed within the investigated $m^*$ range, indicating that wake interference reshapes the stability boundary of the system.

Exhumation-induced stress triggers natural hydraulic fracturing, governing fluid overpressure limits in deeply buried strata. In the Sichuan Basin (South China), the geomechanical response of Lower Cambrian shale to multi-phase differential exhumation remains poorly quantified. We integrated apatite and zircon thermochronology, vitrinite reflectance, residual stratal thickness, and Skempton’s poroelastic model to reconstruct the exhumation and pore pressure history of the Qiongzhusi Formation. Results reveal a four-stage, northwestward-migrating exhumation since the Cretaceous, featuring severe uplift (3000–4000 m) along basin margins and the Weiyuan anticline, versus moderate uplift (2000–2500 m) in the Ziyang intra-basin area. This differential exhumation halted thermal evolution, establishing a spatial thermal maturity distribution (VR = 3.2%–4.0%) and a lower boundary at ∼5500 m, below which graphitization degrades rock properties. Crucially, differential exhumation magnitude and varying initial pore pressures at maximum burial (∼7000 m) governed stress trajectories during uplift. Driven by higher initial pressure, the moderately exhumed Ziyang area reached the natural fracturing threshold at 4100 m, significantly deeper than the heavily exhumed Weiyuan area (3250 m). These critical failure depths mechanistically define the upper limits for overpressure preservation, demonstrating that differential exhumation and poroelastic relaxation fundamentally control the vertical boundaries of overpressured shale compartments.

The carbon isotopic compositions (δ13C and Δ14C) of dissolved inorganic carbon (DIC) in water samples are influenced by various storage conditions, but the extent and mechanisms of these changes remain unclear. In this study, we systematically evaluated the effects of storage temperature, pretreatment (filtration and addition of mercuric chloride, HgCl2), and container material (glass vs. plastic) on δ13CDIC and Δ14CDIC. The δ13CDIC values in samples preserved with HgCl2 exhibited the smallest variation (δ13CDICmax−δ13CDICmin ranging from 0.7‰ to 1.0‰), followed by those stored under refrigeration (∼4°C; variations of 1.3‰ to 1.4‰). These storage conditions also effectively constrained variations in Δ14CDIC over storage periods of up to 60 days in polyethylene terephthalate (PET) bottles. In contrast, comparisons with glass bottles, combined with analysis of PET-derived compounds and associated enzymatic activity, indicated that the degradation of PET-derived compounds provided a plausible explanation for the observed radiocarbon depletion. For long-term storage (>110 days), isotopic fractionation was primarily governed by exchange between DIC and atmospheric CO2, attributable to the permeability of PET bottles. This study provides a quantitative, mechanism-based assessment of storage-induced effects on δ13CDIC and Δ14CDIC, offering practical guidance for minimizing storage-induced uncertainty in carbon isotopic studies.

Environmental constitutionalism refers to the growing constitutional recognition of the environment. Given the diverse designs of constitutional environmental provisions across the world, environmental constitutionalism is construed broadly to reflect both rights and non-rights provisions related to environmental protection. The constitutional entrenchment of environmental rights is the most common expression of environmental constitutionalism. Yet, such a purely rights-based approach ignores the distinctive constitutional design formulated as non-rights directive principles. Central to this debate is the perceived appropriateness, or inappropriateness, of treatment by courts of directive principles as if they are judicially enforceable rights. By exploring the limitations of this twofold division of environmental constitutionalism into conventional rights and directive principles, this article argues that such an approach positions the enforcement of environmental constitutionalism into the binaries of courts versus legislatures. However, environmental constitutionalism should be repositioned towards a collaborative model, the achievement of which requires interactive dynamics among the legislature, the executive, and the judiciary. Through a relational perception of separation of powers, this article offers an innovative understanding of environmental constitutionalism by integrating environmental governance with the values of constitutional collaboration, within which shared responsibility for enforcement is placed among the separated powers.

Passive exoskeletons offer several advantages, including lightweight design, simple structure, and inherent energy efficiency. Most existing passive exoskeletons rely on clutch mechanisms to control spring-based energy storage and release, typically focusing only on recovering biomechanical energy during the stance phase of gait. In this study, we propose and analyze a lightweight passive ankle exoskeleton capable of harvesting and releasing energy during both the stance and swing phases of walking. The device aims to enhance gait assistance while maintaining structural simplicity and minimizing weight. By integrating the optimal stiffness ratio between the stance and swing phases, derived from musculoskeletal model simulations, with previously established optimal stance-phase stiffness parameters, we determined a suitable stiffness coefficient for the swing-phase spring. To validate the design, we conducted comparative experiments on participants walking with exoskeletons configured with different stiffness coefficients. Spatiotemporal parameters, metabolic energy cost, and muscle activation patterns were analyzed to evaluate performance. The results demonstrate that the proposed exoskeleton effectively reduces Soleus muscle activation while increasing tibialis anterior activity, leading to a 6.84% reduction in walking energy cost compared to a nonassistive condition. Furthermore, energy recovery during the swing phase alone contributes an additional 1.67% reduction in energy expenditure, improving overall walking efficiency. The proposed design also eliminates complex clutch components, significantly simplifying manufacturing and reducing costs, thereby enhancing the applicability of passive exoskeletons in daily mobility and rehabilitation scenarios.