Elucidating the radical scavenging mechanisms of bioactive natural products is essential for understanding their antioxidant performance under different physiological conditions. In this work, the antioxidant activity of epicoccone B (EB) was comprehensively explored in aqueous and pentylethanoate using a quantum chemical framework. Thermodynamic analysis indicates that EB possesses multiple reactive hydroxyl sites with distinct roles depending on the medium. In water, low proton affinity values, particularly at the O8–H position, favor the SPLET pathway, while the relatively low ionization energy supports the contribution of electron transfer processes. Kinetic results further demonstrate that the overall antioxidant activity is dominated by the SET mechanism of deprotonated species, yielding a high rate constant of 1.91 × 10⁶ M⁻1 s⁻1. Notably, this value is significantly higher than that of Trolox and comparable to or greater than several well-known antioxidants such as gallic acid and dopamine, highlighting the strong radical scavenging capacity of EB. In contrast, in pentylethanoate, increased PA and IP values suppress ionic mechanisms, and the reaction proceeds mainly via formal hydrogen atom transfer, with the O7–H bond identified as the most active site. Gibbs free energy calculations confirm that hydrogen transfer is thermodynamically preferred, particularly at the O1 position, and that reactivity decreases in less polar environments. These findings reveal a pronounced solvent-dependent antioxidant behavior and suggest that EB is significantly more effective in polar media. All computations were carried out using density functional theory at the M06-2X/6–311 + + G(d,p) level. Fully optimized geometries and vibrational frequency calculations were performed to ensure true minima and to obtain thermodynamic properties in both aqueous and pentylethanoate environments via an SMD implicit solvation model. Frontier thermodynamic parameters, including bond dissociation energies (BDEs), proton affinities (PAs), and ionization energies (IPs), were calculated to assess the feasibility of the fHAT, SPLET, and SETPT mechanisms. The acid–base behavior of EB was evaluated through pKa calculations to determine species distribution under physiological conditions. Reaction kinetics toward the HOO• radical were investigated using the QM-ORSA approach to obtain activation free energies, rate constants, and pathway contributions. All calculations were performed using the Gaussian 09 software package.
Taiwan's diverse land cover provides an excellent testbed for validating satellite and ground-based aerosol optical depth (AOD) measurements. This study validates MODIS (AQUA and TERRA) Level 2 AOD products against AEronet RObotic NETwork (AERONET) measurements across Taiwan during during 2018–2022 for model training, with independent temporal validation using 2023–2024 observations. We developed an Artificial Neural Network (ANN) model incorporating meteorological indicators, land cover characteristics, and temporal patterns to improve AOD retrievals in areas with and without ground-based observations. The ANN model demonstrated strong performance with determination coefficients (R²) of 0.95 and 0.94 for TERRA and AQUA respectively, and root-mean-square errors (RMSE) of 0.05 and 0.07. Additionally, we implemented a novel Land Cover Learning (LCL) framework that enables cross-validation between different AERONET sites based on similar environmental characteristics, effectively addressing spatial gaps in AOD data. The LCL framework achieved 91% of cross-validated retrievals within the expected error bounds, demonstrating effective gap-filling over the 31,500 km² reconstructed domain. This approach demonstrates potential for application in other regions with similar geographical diversity and limited ground-based monitoring networks.
Landslides are a major geo-environmental hazard in Vietnam’s midland and mountainous regions, further intensified by land-use pressures and climate change. This study investigated the influence of forest cover on landslide susceptibility in Cau River Watershed. A forest status map was constructed using inventory and field data by the K-Nearest Neighbors (KNN) algorithm, while landslide susceptibility was modeled using historical events and nine conditioning factors through a hybrid machine learning approach integrating Random Forest (RF), Multilayer Perceptron (MLP) and KNN. The proposed hybrid model achieved an overall accuracy of 85.33%, demonstrating its robustness in susceptibility prediction. Results indicated that natural and native-species forests significantly reduce landslide density and susceptibility relative to non-forested areas and exotic plantations. These findings highlight the critical role of forest structure and species composition in stabilizing slopes. The study provides evidence-based insights to guide adaptive land management, forest policy, and regional strategies for climate resilience and sustainable development.
During a survey of myxosporean parasites in freshwater fishes from northern Vietnam conducted between 2018 and 2026, myxospores were observed in the gallbladder of Cranoglanis bouderius (Siluriformes: Cranoglanididae). The parasite was detected in two of 35 examined hosts (5.7%). Mature myxospores are fusiform, measuring 11.1-12.7 μm long, 5.1-5.6 μm wide, and 4.5-4.9 μm thick. The myxospores consist of two valves joined along a sutural line, each valve bearing 7-8 longitudinal grooves. Two equal-sized pyriform polar capsules are located at opposite ends of the myxospore, measuring 3.0-3.9 μm long by 2.3-3.4 μm wide, each containing a polar tubule with 4-5 coils. Molecular analysis based on SSU rDNA sequence data revealed that the present species is genetically distinct from other myxosporean species with available sequence data. The combination of morphological features and molecular evidence supports the description of Myxidium hangae n. sp. This study represents the first record and description of a species of Myxidium from the fish fauna of Vietnam and contributes to current knowledge of myxosporean diversity in Southeast Asia.
The Krong Ana Rice Certification Mark is an important intellectual property asset that contributes to enhancing product value and promoting the development of the rice sector in Dak Lak Province. However, the implementation of the two-tier local government system from July 1, 2025, has significantly altered the management structure of the certification mark, as the district-level authority that previously served as the managing entity no longer exists. This study aims to analyze the current management status of the Krong Ana Rice Certification Mark under the new administrative framework, identify emerging governance gaps, and propose an appropriate management model. The study employs document analysis, semi-structured interviews, and expert consultations involving 46 stakeholders, including local government officials, cooperatives, enterprises, rice-producing households, and experts from three communes within the Krong Ana rice production area. The findings indicate that while the administrative restructuring has not affected the legal validity of the certification mark, it has created several governance challenges, including the absence of a unified coordination mechanism across the production area, difficulties in granting and supervising the use of the certification mark, limitations in quality control, and weak inter-communal coordination. Based on these findings, the study proposes an inter-communal management model organized around production areas and value chains to ensure the effective utilization and sustainable development of the Krong Ana Rice Certification Mark within the new local government structure.
