Dong Thap University

Accurate and timely agricultural mapping is essential for supporting sustainable agricultural development, resource management, and food security. Despite its importance, Vietnam lacks detailed and consistent large-scale agricultural maps. In this study, we produced the first national-scale agricultural map of Vietnam for 2024 using a UNet++ deep learning architecture that integrates multi-temporal Sentinel-1 and Sentinel-2 imagery with Global-30 DEM data. The resulting product includes 15 land-cover categories, eight of which represent the most popular agricultural types in Vietnam. We further evaluate the model’s transferability by applying the 2024 trained model to generate a corresponding map for 2020. The approach achieves overall classification accuracies of 83.01%±1.37% (2020) and 80.09%±0.76% (2024). To address class imbalance within the training dataset, we introduced an adaptive weight combined loss function that automatically adjusts the weight of dice loss and cross-entropy loss within a combined loss function during the model training process.

The genus Ussurohelcon Belokobylskij is recorded for the first time from Vietnam with six new species described and fully illustrated: Ussurohelconhatinh Long, sp. nov., U.hagiang Long, sp. nov., U.mellicentralis Long, sp. nov., U.mocchau Long & van Achterberg, sp. nov., U.similis Long, sp. nov. and U.tuyenquang Long, sp. nov. Comparative morphological characters of Ussurohelcon species are discussed and a key to Oriental species is also provided.

<title>Abstract</title> Chlorpyrifos is a widely used pesticide worldwide, and its residues are commonly found in water, soil, sediments, and fruits. This study isolated two mixed pure cultures of chlorpyrifos-degrading bacteria. Mixture 1 included <italic>Bacillus subtilis</italic> CP1 and <italic>Cupriavidus</italic> sp. CP2 isolated from soil, which degraded under aerobic conditions. Mixture 2 consisted of <italic>Pseudomonas aeruginosa</italic> CP3, <italic>Bacteroides</italic> sp. CP4, and <italic>Dehalococcoides mccartyi</italic> CP5 isolated from sediment degrading chlorpyrifos under anaerobic conditions. The mixed cultures 1 and 2 completely utilized the insecticide at 50 mg/L as a sole carbon source within 2 and 5 days, respectively. Moreover, mixed culture 1 could utilize 3,5,6-trichloro-2-pyridinol as a sole carbon and nitrogen source. During the degradation of chlorpyrifos, two metabolites, 3,5,6-trichloro-2-pyridinol and di-ethylthiophosphate, were produced by both mixed cultures. 5,6-Dihydro-2(1H)-pyridinone and 3,6-dihydroxypyridine-2,5-dione were also metabolites during the degradation by <italic>Bacillus subtilis</italic> CP1 and <italic>Cupriavidus</italic> CP2, respectively. Meanwhile, 5,6-dichloro-2-pyridinol, 2-pyridinol and fumaric acid were produced during the degradation by the mixed culture 2. The In vitro degradation of pesticides in collected soil and sediment enhanced with the inoculation of target degrading bacteria under both aerobic and anaerobic conditions. This study elucidates the mechanism of chlorpyrifos degradation by two bacterial mixtures, and the differences between in vitro and ex situ degradation.

Water quality monitoring is crucial for assessing water quality and identifying sources of water pollutants. This study assessed the surface water quality in Dak Lak province, Vietnam using multivariate statistical techniques. Pearson correlation, water quality index (WQI), principal component analysis (PCA), and cluster analysis (CA) were determined based on various physical, chemical, and biological indicators. The study found that BOD5 concentrations exceeded permissible limits in 80% of river water samples and 36% of lake water samples. Meanwhile, all samples met the allowable limits for N-NO3–. The assessment revealed that surface water pollution in the region is due to both natural and human activities. TSS mainly originated from natural processes or mineral exploitation, while BOD5 and COD were primarily from domestic or waste treatment. N-NO2–, N-NO3–, N-NH4+, o-PO43– were traced back to domestic and industrial wastewater, and coliforms were from domestic and non-human sources. Water samples from areas with high population density had lower WQI values than areas surrounded by agriculture fields and sparse populations. Finally, the study noted that water flow with high pollutant concentrations during the rainy season. These findings are expected to provide valuable insights into surface water pollution in Dak Lak province.

In this work, assembled ZnO/ZnCo2O4 heterostructure nanosheets (ZnO/ZCO) were successfully synthesized through a rapid one-step microwave-assisted hydrothermal method. The ZnO/ZnCo2O4 sample features an ordered assembly of nanocrystals with a size of 30 nm forming two dimensional (2D) nanosheets, and ZnO-ZnCo2O4 heterojunctions are uniformly distributed. The physicochemical properties of ZnO/ZCO heterostructures were systematically studied by combining experiments and density functional theory (DFT) calculation. The heterojunction configuration of ZnO and ZnCo2O4 produced an interfacial charge redistribution and strong electronic interaction, resulting in the enhanced electrocatalytic performance towards ofloxacin (OFL). Consequently, the ZnO/ZnCo2O4 heterostructure nanosheet-based electrochemical sensor possessed an outstanding sensing performance in the detection of OFL with a high electrochemical sensitivity of 1.97 µA µM−1 cm−2. In addition, the proposed sensor was successfully applied for the detection of OFL in tap and lake water with recovery rates of 97.0–99.2%. The study demonstrates the potential of spinel oxide-based electrochemical sensors for rapid and cost-effective detection of antibiotic residues, providing an effective solution for water quality safety monitoring.

Students at Vinh Trach High School in rural An Giang province have faced persistent difficulties in developing English speaking skills, largely due to limited exposure to communicative practice. This study examined the effects of oral communicative activities on the speaking development of 44 eleventh-grade students through a 12-week classroom intervention. A mixed-methods design was employed, integrating a quasi-experimental pretest and posttest speaking assessment with a survey questionnaire and semi-structured interviews. Quantitative findings showed a significant improvement in students’ speaking performance, and strong reliability across questionnaire items. Qualitative results indicated that students viewed activities such as role plays, discussions, and interviews positively, noting gains in confidence and fluency. However, students expressed challenges related to limited vocabulary, pronunciation difficulties, and fear of making mistakes. The study not only validates oral communicative activities effectively build fluency and confidence, but also highlights the importance of supportive, student-centered communicative teaching to reduce anxiety and promote meaningful oral interaction in rural learning contexts. These insights offer valuable guidance for teachers, school leaders, and future research aiming to improve English speaking instruction in similar rural contexts.

This study employed a simple hydrolysis method to synthesize two novel nanocomposites: ZnO/g-C3N4 (ZCN) and TiO2/g-C3N4 (TCN). Characterization results confirmed the successful integration of ZnO and TiO2 nanoparticles onto g-C3N4 nanosheets, resulting in enhanced optical absorption in the visible light region. Both synthesized ZCN and TCN composites exhibited higher photocatalytic degradation efficiency of the antibiotic doxycycline under visible light irradiation compared to their individual component materials. This enhancement is attributed to the formation of heterojunction between TiO2 or ZnO and porous g-C3N4, which improves electron-hole pair separation and reduces recombination. The photocatalytic degradation kinetics of doxycycline using ZCN and TCN followed a pseudo-first-order model, with both catalysts demonstrating operational stability and effectiveness in antibiotic photodegradation.

Background:Mental health issues have gained increased attention globally in recent years, especially since the onset of the COVID-19 pandemic. This study estimated the prevalence of mental health problems, including depression, anxiety, and stress, and identified the determinants associated with the levels of mental health problems among Vietnamese undergraduate students across various academic disciplines.Materials and Methods:A cross-sectional study was conducted at three educational institutions in southern Vietnam. A structured questionnaire including questions about personal characteristics, family background, academic-related aspects, and the 21-item Depression Anxiety and Stress Scale (DASS-21) was used to assess self-reported symptoms of depression, anxiety, and stress among undergraduate students. Linear regression models were used to identify the factors associated with the DASS-21 scores among undergraduate students.Results:Of the 572 participants, 191 (33.4%) experienced depression, 271 (47.4%) reported anxiety, and 162 (28.3%) suffered from stress. Significant heterogeneity in depression, anxiety, and stress was observed among undergraduates within the same academic disciplines, with all intracluster correlation coefficients (ICCs) ≤0.053. Increased risks of mental health issues were linked to a lack of regular exercise (β = 2.15, P = .037, ref: frequently doing exercise), dissatisfaction with family affection (β = 8.42, P = .023, ref: satisfaction with family relationship), financial control from family (β = 8.00, P < .001, ref: without financial control), dissatisfaction with academic mentorship (β =16.08, P < .001, ref: satisfaction with mentorship), and personal studying performance pressure (β = 4.33, P = .018, ref: without personal studying performance pressure).Discussion and Conclusion:The study findings provided important insights into the high prevalence and key determinants of mental health symptoms among undergraduate students, which may inform the design of future interventions and support programs in Vietnam.