商丘师范学院

In an era of accelerating globalization and frequent cross-cultural contact, willingness to communicate (WTC) in a second language is widely recognized as a critical predictor of successful language acquisition. To deepen the understanding of cultural influences on the formation of language-related behaviors, this study examines how Chinese learners of Korean as a Foreign Language (KFL) perceive the coolness of Korean popular music (K-POP) culture and how such perceptions influence their WTC in Korean. Grounded in Perceived Coolness Theory and Attachment Theory, the study proposes a structural model incorporating four dimensions—Perceived Subculture, Perceived Attractiveness, Perceived Utility, and Perceived Originality—and introduces emotional attachment as a mediating variable to uncover the psychological mechanisms linking cultural perception to communicative behavior. Structural equation modeling using partial least squares (PLS-SEM) was conducted on survey data from 360 Chinese KFL learners recruited online via Wenjuanxing. The analysis employed 5000 bootstrap samples to test the measurement and structural models, including bias-corrected confidence intervals for mediation effects. All four dimensions of perceived K-POP coolness significantly predicted emotional attachment, which in turn strongly enhanced willingness to communicate (WTC) in Korean. Emotional attachment mediated the relationships between perceived coolness and WTC. These findings offer concrete guidance for KFL instructors and curriculum designers: selecting K-POP materials high in attractiveness, subcultural appeal, and language-learning utility, and explicitly linking them to noticing activities can strengthen learners’ emotional investment and oral participation.

To improve crop mapping in complex agricultural regions for food security, this study develops a seasonal monitoring framework, treating the growing seasons as independent classification tasks based on specific temporal windows, in Henan Province, China, using 2023 Sentinel imagery. It employs separate feature sets for summer-harvested (winter wheat) and autumn-harvested crops (maize, rice, peanut, soybean), using an XGBoost algorithm for classification and a SHAP model to overcome the black-box nature of the algorithm and identify key phenological markers. The framework demonstrated high effectiveness, achieving cross-validation consistency rates of 85.18% for winter wheat and 90.08% for maize. The resulting maps show that a winter wheat-summer maize rotation is the predominant cropping pattern in the province. The study also found that driving factors for classification differ by season: winter wheat identification depends on unique phenological signals (e.g., March NIR), whereas autumn crops are distinguished by a dual mechanism of macro-geographical latitude and specific spectral indices. This research confirms the strategy's robustness for fine-scale mapping.

Anode-free sodium batteries (AFSBs) with near-theoretical energy density hold great promise for next-generation sustainable energy storage systems. However, their practical implementation is impeded by the low operating rate threshold (<1 milliampere per square centimeter) and poor cycling stability, owing to dendritic sodium (Na) growth. Here, a high-rate and durable AFSB is successfully realized via a spatially anion-confined electrolyte strategy. Specifically, positively charged nanoparticles are introduced into the electrolyte to selectively anchor anions, generating localized contact ion pair-dominated solvation to facilitate rapid Na+ desolvation at electrode interface and form an anion-derived solid electrolyte interphase. Meanwhile, rapid ion transport in the bulk electrolyte is maintained by the solvent-separated ion pair solvation structure in the nanoparticle periphery. These factors conjointly enable flat and dense Na deposition at high current densities. Consequently, an energy-type Na(Ni1/3Fe1/3Mn1/3)O2||Al full cell exhibits an energy density of 415.6 watt-hour per kilogramcathode+anode even at 1 C (2.1 milliamperes per square centimeter) with 70.2% capacity retention over 400 cycles. A power-type Na3V2(PO4)3||Al cell achieves a trebled operation current density compared to the state-of-the-art AFSBs, exhibiting an unprecedented 5-C rate (3.8 milliamperes per square centimeter) with 70.0% capacity retention over 1400 cycles. This strategy presents a potentially universal approach for high-rate alkali metal batteries.

Recent studies have shown that N-heterocyclic carbenes (NHCs) can serve as C1 synthons beyond their conventional roles as ligands and organocatalysts, enabling scalable single-carbon atom transfer to alpha,beta-unsaturated amides. In this theoretical investigation, we explore the mechanistic origin and chemoselectivity associated with the dual reactivity of NHCs as C1 synthons versus organocatalysts when N-arylacrylamides are used as the substrate. Chemoselectivity-determining transition states are identified, including the concerted C-N bond cleavage with proton transfer transition state in the C1 synthon pathway and the catalyst regeneration transition state in the organocatalyst pathway. Computational analyses indicate a positive correlation between the electron-withdrawing properties of NHC substituents and their selectivity toward the C1 synthon pathway. Moreover, steric repulsion in the concerted C-N bond cleavage with proton transfer transition state disfavors the C1 synthon pathway, thereby resulting in chemoselectivity reversal. Based on these mechanistic insights, we propose two strategies to promote the conversion from the organocatalyst pathway to the C1 synthon pathway: (i) catalyst structural modification to reduce steric repulsion and (ii) replacement of the base with tert-butoxide. These findings provide a fundamental understanding and design principles for modulating NHC-mediated single-carbon atom transfer reactions, thereby expanding the synthetic utility of NHCs as C1 synthons in organic synthesis.

The extraction of ultra-thick coal seams (>20 m) poses significant mechanical and safety challenges due to complex, nonlinear deformation and failure of the overlying strata. Using the Huating Coalfield as a representative case, this study investigates the spatiotemporal evolution of fracture propagation and overburden failure mechanisms in ultra-thick seams (26 m) mined by a two-stage large-height top-coal caving method (LHTCM). An integrated approach combining large-scale physical modeling, UDEC 2D discrete-element simulation, digital image correlation (DIC), and fractal analysis is employed, with quantitative cross-validation between experimental and numerical results. The results show that overburden deformation follows a stage-dependent hierarchical failure process. During Stage I (pressure-relief mining), primary fractures initiate and propagate upward through deep-beam rupture and cantilever instability, forming the main fracture skeleton. Stage II (top-coal caving) mainly reactivates and compacts this pre-existing fractured structure, producing step-like subsidence and final recompaction rather than continuous generation of new fracture networks. Quantitatively, the fractured zone height increases from around 22 m to 60 m, while the fracture fractal dimension rises from 2.22 to 2.66, indicating enhanced fracture connectivity with a tendency toward saturation in later stages. The mechanical evolution of the roof is governed by the sequential transformation of deep beam, cantilever beam, and three-hinged arch (voussoir beam) structures, whose instability controls fracture migration and overburden collapse. Stress redistribution and concentration in key strata regulate crack coalescence and failure timing, reflected by periodic support-load fluctuations. A fracture boundary morphology model describing the fractured zone as an elliptic paraboloid is proposed to link maximum fracture height with mining height and recovery rate. Spatial analysis further identifies central and right zones as disaster-prone areas with higher crack density and fractal dimension. These findings provide mechanistic insight and quantitative indicators for predicting strata failure and optimizing roof control in ultra-thick seam mining.