Search Results (890)

Medicarpin, a natural pterocarpan phytoalexin, contributes to tree defense against microbial decay, particularly from the aggressive white-rot fungus Trametes versicolor, an ASTM standard for wood durability testing. To improve upon the inhibitory effect of medicarpin against this fungus (150 mg/L), eleven derivatives were synthesized and evaluated. The acetylated analog demonstrated superior activity, achieving complete growth inhibition at 100 mg/L. To establish a structure–activity relationship, molecular docking was performed on the copper cluster on fungal laccase, the primary oxidative enzyme of T. versicolor. The acetylated derivative bound the T1 copper site with a more favorable free energy (−8.5 kcal/mol) than the parent compound, exhibiting enhanced stabilizing interactions and a binding pose anchored closer to the trinuclear copper cluster (TNC). These results were corroborated by 80 ns molecular dynamics simulations, confirming complex stability and the persistence of key interactions. This study demonstrates that targeted chemical modification of natural phytoalexins can significantly improve their antifungal potency. The superior performance of the acetylated medicarpin derivative, linked to optimized binding at the laccase active site, establishes a clear structure–activity relationship and highlights the potential of such engineered compounds as leads for next-generation, bio-inspired wood preservatives. Full article

This study aims to investigate the influence of clay mineral content on the rheological properties and long-term deformation stability of clays, and to establish a unified model capable of quantitatively describing the nonlinear rheological behavior of clays with different mineral compositions. Direct shear rheological tests were conducted on specimens prepared with different mixing ratios of bentonite, kaolin, and quartz. Combined with micro-mechanism analysis, the controlling factors of clay rheological behavior were explored. The experimental results show that the creep stress threshold, elastic viscosity, and average plastic viscosity decrease significantly with increasing clay mineral content. The rheological deformation exhibits distinct nonlinear characteristics, and clay mineral content plays a controlling role in the rheological behavior. Based on experimental and mechanistic analysis, a unified rheological model was established, which reflects the material origin of rheology and captures nonlinear rheological characteristics. This model can predict the entire time-history mechanical behavior of clays with different mineral compositions across the three stages of instantaneous deformation, decay rheology, and steady-state rheology under different shear stress levels using a single set of parameters. Validation was performed through direct shear rheological tests under 50 working conditions for five types of clay specimens, demonstrating good consistency between the model calculations and experimental results. The unified rheological model reveals the material origin and physical essence of clay rheology, demonstrates high universality, and advances the understanding of the influence of mineral composition on rheology from the current phenomenological qualitative description to quantitative calculation for the first time, significantly enhancing its engineering application value. This provides a more reliable tool for predicting long-term deformation and assessing the stability of clay foundations. Full article

Owing to the synergistic effect of cationic and anionic charge compensation, Li-rich layered oxide cathodes stand as the most promising candidates for next-generation high-energy-density Li-ion batteries. However, the unstable oxygen redox process triggers irreversible oxygen release and structural degradation of the layered framework, which further destabilizes the Li-O-Li configuration and leads to severe performance decay. In this work, a layered/spinel heterostructure coupled with a stabilized Li-O-vacancy configuration is successfully constructed in a Li-rich layered oxide cathode. This design enables outstanding structural and electrochemical stability, delivering an initial discharge capacity of 232 mAh g⁻¹ with a Coulombic efficiency of 90.5%. Moreover, the cathode retains 86.5% of its capacity after 100 cycles. The proposed structural design strategy offers a new pathway toward high-performance Li-rich layered oxide cathodes. Full article

To address the capacity decay of NCM811 caused by microcracks and cation disorder during cycling, La, Al, and F tri-doped micron-sized single-crystal NCM811 material with a LiNbO₃ coating was synthesized via a facile co-solvent method. Using a mixed glucose–urea thermal solution as the reaction medium, metal salts were incorporated, followed by step-wise sintering, ball-milling, heat treatment, and wet-chemical coating. This approach enables atomic-level precursor mixing and ensures homogeneous element distribution. La³⁺ enlarges the lithium layer spacing to enhance ion diffusion and Al³⁺ suppresses Ni³⁺ reduction to Ni²⁺, mitigating cation mixing and improving conductivity, while F⁻ stabilizes the crystal structure via its strong electronegativity. The LiNbO₃ coating protects the interface from electrolyte attack, and the single-crystal morphology effectively suppresses microcracking. Compared to unmodified single-crystal NCM811 prepared identically, the modified material exhibits reduced cation disorder, improved crystallinity, and superior thermal stability. Electrochemical tests in half-cells with 1 M LiPF₆/(EC/EMC/DMC) electrolyte (2.8–4.3 V) show an initial discharge capacity of 208.32 mAh/g at 0.1 C and 194.05 mAh/g at 1 C. After 200 cycles at 1 C, the capacity retention remains at 92.21%, exceeding the market average. Rate performance is also notably enhanced, with the 5 C discharge capacity increasing from 141.12 mAh/g (unmodified) to 166.81 mAh/g, demonstrating improved kinetics and structural stability. Full article

Water level fluctuations in reservoir areas subject bank slopes to intense wet–dry cycles (WDCs), compromising rock mass stability. This study investigates the macro–meso damage evolution of yellow sandstone from the Wudongde Reservoir. Specimens subjected to 0–20 WDCs were analyzed using nuclear magnetic resonance (NMR) alongside Brazilian splitting, uniaxial, and triaxial compression tests. Results indicate that porosity increases linearly with WDC, rising from 6.12% to 17.61% after 20 cycles, driven by the transformation of micropores into macropores. Macroscopic mechanical parameters, particularly tensile strength and cohesion, exhibit significant exponential and sharp decay, respectively, while the internal friction angle remains relatively stable. Notably, increasing confining pressure effectively mitigates WDC-induced deterioration by inhibiting microcrack propagation. The damage mechanism is primarily attributed to the dissolution of clay binder and uneven mineral swelling/shrinkage, whereas the rigid mineral skeleton remains largely intact. These findings provide a theoretical basis for quantifying rock damage and predicting slope stability in complex hydrological environments. Full article

This paper proposes an impulsive SIRQ model for the analysis of computer network resilience against malware propagation and distributed denial-of-service (DDoS) attacks. The model extends classical epidemic frameworks by combining the continuous-time dynamics of malicious object spreading with discrete control actions corresponding to mass updates, node isolation, and access control policies. A qualitative analysis of the resulting system of impulsive differential equations is performed. The basic reproduction number ${\mathcal{R}}_0$, identified as a threshold parameter characterizing the intensity of attack propagation, and sufficient conditions for the global asymptotic stability of the infection-free state are established. It is shown that, under periodic impulsive control, the infection-free state can be stabilized with respect to the target population coordinates even when ${\mathcal{R}}_0>1$. An exponential decay estimate for the total active threat is derived, guaranteeing the asymptotic extinction of the infected and quarantined node populations. The proposed approach provides quantitative criteria for the effectiveness of impulsive cyber defense strategies and offers a theoretical foundation for the design of adaptive multi-layer protection systems for critical information infrastructures. Practical interpretation of the results illustrates the dependence of the critical impulsive control period on the model parameters and demonstrates the applicability of the approach to cybersecurity strategy design. Full article

Compact carbonate stones are widely used in architectural heritage for their aesthetic value and cultural significance, yet their long-term durability in saline environments remains insufficiently understood, particularly when assessed using standard salt crystallization tests developed primarily for porous lithotypes. This study investigates salt-induced deterioration in Portoro limestone, a compact ornamental carbonate extensively employed in historic architecture, considering four commercial varieties representative of heritage applications. Salt crystallization tests were performed using saturated sodium sulphate (Na₂SO₄) and sodium chloride (NaCl) solutions following the relevant European standard procedure, with the protocol extended to 45 cycles to capture delayed deterioration processes. Both untreated specimens and samples subjected to controlled thermal pre-conditioning at 300 °C and 500 °C were tested to activate latent microstructural weaknesses. Material decay was assessed through mass variation, porosity changes, surface observations, Leeb rebound hardness and ultrasonic pulse velocity measurements. Results demonstrate that deterioration is primarily controlled by salt type and microstructural characteristics rather than by total porosity. Sodium sulphate induced severe internal damage and abrupt structural failure associated with mirabilite crystallization, often following a prolonged phase of apparent stability. In contrast, sodium chloride causes mainly superficial effects with negligible mechanical impact. Thermal pre-conditioning accelerated damage development, while non-destructive techniques revealed internal deterioration well before visible damage occurred. These findings indicate that standard crystallization tests may be inadequate for low-porosity stones and that extended-cycle approaches provide a more reliable framework for durability assessment in saline environments. Full article

Rhizopus oryzae lipase (ROL) is a key enzyme involved in olive oil spoilage and acts as a virulence factor in fungal infections. Natural lipophilic lipase inhibitors are crucial for mitigating economic losses resulting from lipid degradation in stored or decaying olive fruits. This study evaluated a series of enzymatically synthesized piperate esters with varying alkyl chain lengths (butyryl, C4; octyl, C8; dodecyl, C12) for their inhibitory effects on ROL activity. Octyl piperate (C8) demonstrated the highest potency, with IC₅₀ values of 0.05 mg/mL using methods B and C or 0.25 mg/mL using method A. Molecular docking indicated that C8 achieved the most favorable predicted binding energy (Gscore: –11.134 kcal/mol), primarily through hydrophobic interactions (Val329, Ala212, Phe209) and hydrogen bonds with oxyanion hole residues (Ser268, Thr206, Gln241). Molecular dynamics simulations confirmed that C8 maintained stable binding and stabilized the catalytic residues. In comparison, C4 exhibited weaker interactions, and the longer C12 chain induced conformational instability and steric hindrance. These results establish a parabolic structure–activity relationship, identifying the octyl chain (C8) as optimal for ROL inhibition among the tested derivatives. The rational design of lipophilic, biodegradable lipase inhibitors thus positions octyl piperate as a promising candidate for extending olive storage and shelf life, and as a scaffold for developing natural antifungal agents targeting virulent R. oryzae strains. Full article

Accurately forecasting the risk matrix and constructing a well-controlled portfolio based on these forecasts is the core objective of effective asset allocation. This paper takes the Chinese stock market as the research object, employing multiple machine learning algorithms to systematically compare the predictive performance of the Financial Stress (FS) indicator and the Economic Policy Uncertainty (EPU) index in sectoral risk management. The forecast results are subsequently applied to portfolio construction and optimization. The findings indicate that, in terms of predictive dimensions, EPU demonstrates strong performance in short-term forecasts, but its explanatory power decays rapidly as the forecasting horizon extends. In contrast, the FS factor achieves forecasting accuracy that is significantly superior to both the EPU factor and traditional price series across all time horizons, exhibiting robust long-memory characteristics and cross-period stability. At the portfolio application level, the minimum variance strategy constructed based on FS forecasts effectively reduces out-of-sample portfolio variance, achieving superior risk control performance compared to strategies based on EPU factor forecasts. This result reveals the differentiated mechanisms of the two factor types: EPU acts as a driving force for short-term risk structure reshaping, while financial stress serves as the core variable driving the evolution of long-term risk structures. Machine learning methods provide an effective technical pathway for capturing these complex nonlinear relationships. The research conclusions offer new empirical evidence for investors to optimize asset allocation decisions and for regulatory authorities to improve risk monitoring systems. Full article

Climate chambers enable repeatable indoor boundary conditions and are increasingly used to study multi-domain IEQ. However, thermal comfort and IAQ are still often evaluated separately, limiting evidence on their coupled behavior and potential trade-offs under different ventilation and air-cleaning strategies. The present study was carried out in the climate chamber located in the laboratory facilities of the University of Western Macedonia to quantify thermal comfort and IAQ simultaneously across different experimental scenarios that vary ventilation mode, heating operation, and occupancy. The results show a correlation between subjective and objective measurements, with the comfort temperature varying around 22.2 °C, as estimated by the Griffiths model, while ventilation mainly affects the stability of the thermal environment. CO₂ levels scaled with occupancy and ventilation rate, while PM removal was strongly strategy-dependent: after a controlled smoke event, mechanical ventilation plus air purification achieved the fastest decay and recovery toward near-background concentrations. Overall, this work represents a first step toward coupled IEQ research by jointly quantifying thermal comfort and IAQ in a climate chamber, enabling systematic comparison of ventilation strategies in terms of both perceived comfort and pollutant exposure. Full article

We present Hyperbolic Symmetric Hypermodular Neural Operators (ONHSH), a novel operator learning framework for solving partial differential equations (PDEs) in curved, anisotropic, and modularly structured domains. The architecture integrates three components: hyperbolic-symmetric activation kernels that adapt to non-Euclidean geometries, modular spectral smoothing informed by arithmetic regularity, and curvature-sensitive kernels based on anisotropic Besov theory. In its theoretical foundation, the Ramanujan–Santos–Sales Hypermodular Operator Theorem establishes minimax-optimal approximation rates and provides a spectral-topological interpretation through noncommutative Chern characters. These contributions unify harmonic analysis, approximation theory, and arithmetic topology into a single operator learning paradigm. In addition to theoretical advances, ONHSH achieves robust empirical results. Numerical experiments on thermal diffusion problems demonstrate superior accuracy and stability compared to Fourier Neural Operators and Geo-FNO. The method consistently resolves high-frequency modes, preserves geometric fidelity in curved domains, and maintains robust convergence in anisotropic regimes. Error decay rates closely match theoretical minimax predictions, while Voronovskaya-type expansions capture the tradeoffs between bias and spectral variance observed in practice. Notably, ONHSH kernels preserve Lorentz invariance, enabling accurate modeling of relativistic PDE dynamics. Overall, ONHSH combines rigorous theoretical guarantees with practical performance improvements, making it a versatile and geometry-adaptable framework for operator learning. By connecting harmonic analysis, spectral geometry, and machine learning, this work advances both the mathematical foundations and the empirical scope of PDE-based modeling in structured, curved, and arithmetically. Full article

One of the primary causes of casualties as a result of underground coal mine disasters is the generation of high concentrations of carbon monoxide (CO). In this study, a copper (Cu)–manganese (Mn)–tin (Sn) composite oxide catalyst was prepared using the co-precipitation method, and the effects of CO concentration (1–7%), reaction temperature (25–300 °C), and water poisoning degree (0–100%) on CO catalytic oxidation performance were systematically investigated using a dynamic activity testing system. The results demonstrated that within the CO concentration range of 1–7%, the catalyst was able to reduce the CO concentration to below 0.55% in a maximum of 248 s and maintain this level in a relatively stable state. Meanwhile, both the catalytic activity and maximum instantaneous reaction rate exhibited a linear increase with the rise in the CO concentration. Elevated temperature significantly shortened the equilibrium time and reduced the equilibrium concentration, achieving 99.99% elimination efficiency at 300 °C; however, catalyst activity decreased with increasing temperature due to adsorption step limitations. Water poisoning severely affected catalyst performance, with activity, elimination efficiency, and long-term stability exhibiting exponential decay as the water poisoning degree increased, with the most significant performance decline occurring in the 0–60% range. Based on the dynamic gas concentration analysis, the CO oxidation process with this catalyst exhibited characteristics consistent with the Mars–van Krevelen mechanism. These findings provide an experimental basis for evaluating the applicability of Sn-containing catalysts in extreme underground coal mine environments. Full article

Cannabinoids are of considerable current interest for use in pharmaceutical and non-medical consumer products. While there have been significant efforts to understand their chemical stability under ambient conditions, only sparse attention has been paid to characterising their photostability. Here, we present UVA (365 nm) and UVB (280 nm) photolysis measurements of eight representative cannabinoids, including natural compounds (THC, CBD, THCA, CBDA), metabolites (THC-COOH, THC-OH), and synthetic analogues (JWH-018, MDMB-FUBINACA). Measurements were performed using a novel online-electrospray mass spectrometry (MS) approach, where online photolysis of cannabinoid solutions was conducted with laser light-emitting diodes. MS detection was used to monitor precursor compound decay and photoproduct formation. Complementary results obtained via UV–Vis spectroscopy of photolysed cannabinoid solutions are also presented. For THC, CBD, THC-COOH, THC-OH, THCA and CBDA, significant photodegradation was observed with 280 nm photolysis, both through the appearance of photoproducts detected by MS and via time-dependent changes in the solution UV–Vis absorption profiles. In contrast, the synthetic cannabinoids (JWH-018 and MDMB-FUBINACA) showed negligible degradation with UVB photolysis, consistent with their relatively low absorbance propensity through the mid-UV region. No significant photodegradation was observed for UVA (365 nm) photolysis of any of the cannabinoids. The results presented here constitute the first directly comparable set of photolysis measurements for key phytocannabinoids. Full article

Erbium-165 (¹⁶⁵Er) is an Auger electron emitter with 7.2 electrons per decay and very few other emissions, making it an interesting candidate for Auger electron therapy. We present here a procedure for producing ¹⁶⁵Er by the ^natHo(p,n)¹⁶⁵Er nuclear reaction on a 16.5 MeV medical cyclotron. The target was prepared by pressing a Ho₂O₃:Al 1:1 (w/w) powder mixture on a Ag disc with a cylindrical depression in the center. With a 0.1 mm Nb foil in front, degrading the energy to 15 MeV, and water cooling at the back of the Ag disc, the target could withstand irradiation at currents up to 45 µA without showing any signs of damage. The beam tolerance of the target was also estimated by calculating the temperature and heat dissipation in the target via the numerical solution of the heat transport equations. For a 180 mg target, the production yield was 12.3 ± 1.9 MBq/µAh. The separation of two neighboring lanthanides is challenging, which led us to study the distribution coefficients for Er and Ho on commercially available LN2 resin for both HNO₃ and HCl eluents. Based on these values, we propose a purification procedure involving two successive LN2 columns for separating the ¹⁶⁵Er from Ho and Al, followed by a small TK221 column to concentrate the final eluate. No radionuclidic impurities were detected, and the chemical impurities found in the final formulation were traces of Ho, Er, Ca, Pb, and Fe. For three different chelators (DOTA, DTPA, and CHX-A″-DTPA), the effective molar activity of the final formulation was measured. The stability of the three complexes formed was also assessed upon incubation in mouse serum for 28 h. Full article

Accurate typhoon inflow characterization is essential for offshore wind turbine safety in typhoon-prone regions. This study presents a physics-informed WRF–TurbSim framework that reconstructs rotor-relevant, stage-aware inflow fields for Typhoon In-Fa (2021) by mapping mesoscale stability and turbulence diagnostics into a User-Defined von Kármán model. Spectral and coherence checks confirm consistency with the imposed constraints and show pronounced regime dependence: low-frequency coherence decay remains near IEC neutral behavior, whereas high-frequency decay weakens substantially during the stable eye stage. The results suggest that neutral coherence assumptions may be unreliable in strongly stable typhoon regimes, motivating stage-aware inflow characterization for engineering applications. Full article