Tạp chí Khoa học Trường Đại học Sư phạm Hà Nội: Khoa học Tự nhiên
Tạp chí của Trường Đại học Sư phạm Hà Nội
RETRIEVAL OF PM2.5 CONCENTRATIONS USING MODIS-DERIVED AEROSOL OPTICAL DEPTH IN HO CHI MINH CITY, VIETNAM
Air pollution characterized by fine particulate matter (PM2.5) has emerged as a critical environmental problem in Vietnam, particularly within densely populated metropolitan areas like Ho Chi Minh city. The integration of remote sensing (RS) and geographical information systems (GIS) offers a robust framework for monitoring PM2.5 due to its extensive spatial coverage, high temporal resolution, and cost-effectiveness. This study estimates ground-level PM2.5 concentrations by establishing a correlation between in-situ measurements from six monitoring stations and Aerosol Optical Depth (AOD) values retrieved from MODIS satellite imagery. The spatial, temporal, and seasonal dynamics of PM2.5 in Ho Chi Minh city during the 2020 – 2025 period. Results indicate that the highest concentrations are concentrated in central urban districts, averaging 24.0 μg/m³. During the rainy season, the average of PM2.5 concentration drops to 14.4 μg/m³. This seasonal reduction is primarily attributed to enhanced atmospheric dispersion and the wet deposition (rainwash). Overall, the study demonstrates that utilizing satellite-derived AOD provides a more comprehensive spatial understanding of PM2.5 distribution, thereby supporting evidence-based air quality management and sustainable urban planning.
Nguyen Van Manh, Nguyen Dai Long, Hoang Thi Thu Ha and Luong Thi Kim Cuc
SPATIOTEMPORAL CHARACTERISTICS AND TRENDS OF HEAT EXTREMES IN LAO CAI PROVINCE, VIETNAM
Heat extremes are among the most significant manifestations of climate change, posing increasing risks to human health, agriculture, and socio-economic activities. This study analyzes the characteristics and long-term trends of heat extremes in the Lao Cai region, northern Vietnam, over the period 1975 - 2024 using daily maximum temperature data from meteorological observation stations. The occurrences of hot days and heat waves were identified based on thresholdbased indices and consecutive-day criteria. The results reveal a clear intensification of heat extremes, with significant increases in the frequency, intensity, and duration of hot days and heat waves, particularly in low-elevation areas. In contrast, stations located at elevations above 900 m experience minimum hot days, indicating a strong influence of topography on the spatial distribution of thermal extremes. Heat extremes exhibit strong seasonality, occurring mainly during the warm season from May to September. These findings demonstrate that mountainous regions such as Lao Cai are increasingly affected by extreme heat and provide a crucial scientific basis for heat risk assessment and climate adaptation planning.
Dao Ngoc Hung, Tran Bich Diep, Ly Thuy Nga, Bui Thi Hong Tuyet and Cu Thi Phuong
RAINFALL VARIABILITY AND EXTREME PRECIPITATION EVENTS UNDER CLIMATE CHANGE: A CASE STUDY IN PHU THO PROVINCE, VIETNAM
This study investigates rainfall variability in Phu Tho province, Vietnam, focusing on total annual rainfall, the frequency of heavy rainfall days (≥ 50 mm/day), and very heavy rainfall days (≥ 100 mm/day), alongside rainy season characteristics using daily rainfall data from 1995 to 2024. Trends and variability in rainfall were analyzed using statistical methods, including the Mann–Kendall test and Sen’s slope estimator. The results indicate that trends in total annual rainfall are generally weak and spatio-temporal heterogeneity. In contrast, distinct climate change signals are evident in the intensification of rainfall and extreme weather patterns. Heavy and very heavy rainfall events contribute a disproportionately large share of total annual rainfall, particularly in mountainous terrain, despite their relatively low frequency. Furthermore, changes in rainy season duration remain limited, suggesting that recent climate impacts are primarily manifested through increased rainfall intensity rather than shifts in seasonality. These findings underscore the escalating significance of extreme rainfall events for disaster risk management and climate change adaptation in Phu Tho province.
Dao Ngoc Hung, Tran My Hang, Cu Thi Phuong, Trinh Thi Diu and Nguyen Khac Anh
ANTIOXIDANT ACTIVITY AND SELECTED METABOLIC EFFECTS OF ETHANOL EXTRACT FROM MANGOSTEEN (Garcinia mangostana L.) PERICARP IN HIGH-FAT DIET–INDUCED MICE: AN IN VITRO AND IN VIVO STUDY
Mangosteen (Garcinia mangostana L.) pericarp is a rich source of polyphenolic xanthones and other bioactive compounds with potential antioxidant and metabolic regulatory properties. This study investigated the in vitro antioxidant activity and selected in vivo metabolic effects of ethanol extract from mangosteen pericarp. Mangosteen pericarp collected from Lam Dong province was extracted with 60% ethanol. The extract was characterized for total phenolic content by the Folin–Ciocalteu method. Antioxidant capacity was evaluated using the DPPH radical scavenging assay. For the in vivo study, male white mice (Mus musculus) were divided into four groups: a regular diet (RD), a high-fat diet (HFD), an HFD with extract at 300 mg/kg, and an HFD with extract at 400 mg/kg. Liver weight, spleen weight, and fasting blood glucose levels were measured after 8 weeks. The extract exhibited a high total phenolic content (200.16 ± 17.71 mg gallic acid equivalents/g extract) and showed dose-dependent DPPH radical scavenging activity with a half maximal inhibitory concentration (IC50) value of 118.87 ± 13.56 μg/mL, indicating a moderate but reproducible antioxidant capacity. In vivo, the HFD group showed significantly increased blood glucose levels (10.38 ± 3.54 mmol/L) compared to RD controls (7.57 ± 3.45 mmol/L). Treatment with the extract at 400 mg/kg significantly reduced glucose levels (5.16 ± 0.93 mmol/L, p < 0.05) compared to the HFD group. The extract at 300 mg/kg showed intermediate effects (9.89 ± 2.77 mmol/L). No statistically significant differences were observed in liver or spleen weights among the groups. In summary, the mangosteen pericarp ethanol extract is rich in phenolics, exhibits moderate antioxidant activity in vitro, and demonstrates dose-dependent protective effects against HFD-induced hyperglycemia. While the in vivo metabolic assessment was limited to selected endpoints, these findings provide preliminary evidence supporting the potential of the mangosteen pericarp extract for further investigation in diet-induced metabolic dysfunction models.
Nguyen Thi Hien, Le Thi Tuoi, Tran Thu Ngan and Nguyen Thi Hong Hanh
SPECIES COMPOSITION AND DISTRIBUTION OF LEAFHOPPERS (HEMIPTERA: AUCHENORRHYNCHA: CICADELLIDAE) IN XUAN SON NATIONAL PARK, PHU THO PROVINCE
The species composition and distribution characteristics of leafhoppers (Hemiptera: Cicadellidae) were investigated in Xuan Son National Park, Phu Tho Province. Direct surveys were conducted across three distinct habitats (natural forest, plantation forest, and grassland-shrub) over four sampling periods corresponding to the four seasons of the year. A total of 36 species belonging to 19 genera, 11 tribes, and 6 subfamilies were recorded. The abundance of leafhopper species in Xuan Son National Park fluctuated seasonally, decreasing from summer to winter and recovering in spring; nevertheless, species evenness remained consistently high and stable (J' > 0.80), suggesting a relatively undisturbed ecosystem. Species diversity also varied by habitat: natural forest exhibited the highest diversity (H’ = 2.95; S = 27 species, 75.0%), while plantation forest, despite fewer species, maintained high diversity and balance (H’ = 2.95; S = 22; 61.1%; J’ = 0.95). In contrast, the grasslandshrub habitat showed the lowest diversity and significant imbalance (H’ = 2.36; S = 20; 55.6%; J’ = 0.79). However, species composition across the three habitats was highly similar. Representative species were identified as follows: 11 species were recorded in all three habitats, 11 in two habitats, and 14 were unique to a single habitat.
Nguyen Thi Thu Huong, Christopher H. Dietrich and Bui Minh Hong
HUMAN-MACAQUE INTERACTIONS ON SON TRA PENINSULA, DA NANG CITY: MANAGEMENT IMPLICATIONS FOR SUSTAINABLE COEXISTENCE
This study examines the dynamics of human-macaque interactions on the Son Tra Peninsula, focusing on the influence of visitor and primate characteristics. Statistical analysis revealed that interaction distances predominantly ranged between 2 and 3 meters, suggesting a high degree of habituation within the population. A critical disparity was observed between visitor groups, as domestic visitors provisioned macaques with anthropogenic food significantly more frequently than international visitors (χ2 =22.123, p < 0.001). Among the primates, immature macaques were identified as the most active and bold age group, consistently displaying higher interaction intensity than adults or infants (F = 67.75, p < 0.05). Spatial analysis confirmed that Troop 8 and Troop 3 are the most habituated groups, often engaging in high-intensity proximity behaviors. These findings highlight the urgent need for demographic-specific management interventions to mitigate the risks of disease transmission and primate dependency on anthropogenic food.
Nguyen Vinh Thanh, Ha Thang Long, Pham Bich Thuy, Vu Tra My, Tran Huu Vy and Nguyen Thi Ngan
PREDICTING THE POPULATION TREND OF THE RHESUS MACAQUE (Macaca mulatta) AT SON TRA PENINSULA, DA NANG CITY
The Rhesus macaque (Macaca mulatta) population at Son Tra Peninsula, Da Nang city, is experiencing conflicts with both residents and tourists, manifested in aggressive foraging behaviors and frequent incursions into residential areas. This study evaluated whether the rhesus macaque population on the Son Tra Peninsula has approached the carrying capacity of the habitat and assessed its projected trajectory under different snaring scenarios. In this study, a transect survey method was used to estimate the number of individuals in the macaque troops and the total number of individuals in the entire Son Tra Peninsula area. The age and sex structure of the troops was also recorded using this method. Population size, age–sex structure, group composition, and relevant ecological and demographic parameters were entered into Vortex 10 to simulate population trajectories over the next 50 to 100 years. The results show that under current conditions, with a total of 1487 individuals observed, the Rhesus macaque population in Son Tra has the potential to increase to approximately 1922 individuals. If the rate of illegal snaring consistently exceeds 10% of the total population at that time, the population size will begin to decline and gradually become extinct within 100 years.
Nguyen Vinh Than, Nguyen Tuan Anh, Nguyen Dinh Duy and Nguyen Van Linh
NEW RECORDS AND CONSERVATION STATUS OF BATS (MAMMALIA: CHIROPTERA) IN LANG SON UNESCO GLOBAL GEOPARK, NORTHEASTERN VIETNAM
Lang Son UNESCO Global Geopark contains extensive karst landscapes, large cave systems, and diverse vegetation types that provide highly suitable habitats for bat species. This study updated the bat species composition of the geopark through nine field surveys conducted between February 2022 and July 2025 and through a review of relevant literature. A total of 26 species belonging to 14 genera and 7 families were recorded during the surveys, including five species first recorded for the geopark. When combined with previous records, the bat fauna of the geopark currently comprises at least 41 species representing 20 genera and 8 families. Of these, 12 species are listed in the 2024 Red Data Book of Vietnam, and six species are classified as Near Threatened, Vulnerable, or Endangered in the IUCN Red List of Threatened Species, indicating national and global conservation importance. In addition, the taxonomic status of nine species is updated in accordance with recent systematic revisions. These results provide a robust baseline for future research, long-term monitoring, and conservation planning, particularly for species of high conservation priority.
RECOGNIZING AND UNDERSTANDING AMERICAN SIGN LANGUAGE USING DEEP LEARNING AND MEDIAPIPE
Sign language serves as the primary medium of expression serves as the primary medium of expression for deaf and hard-of-hearing individuals. However, interpersonal interaction remains challenging, as they primarily rely on sign language to express their thoughts. To address this issue, this study proposes an automated sign language recognition and interpretation framework, integrating static and dynamic recognition components. Specifically, a Convolutional Neural Network (CNN) is employed for static gesture classification, while a hybrid CNN- Long Short-Term Memory (CNN-LSTM) architecture is utilized to capture the spatiotemporal features of dynamic signs. Furthermore, MediaPipe is leveraged for robust landmark localization to enhance feature extraction. The American Sign Language (ASL) dataset used in this research ensures diversity in sign representation, including variations in hand shapes, positions, and movements. The proposed models achieved high accuracy, with the CNN model reaching 93.1% and the CNN-LSTM model achieving 94.1% on test datasets, confirming their effectiveness in ASL recognition tasks.
Nguyen Tu Anh, Luong Thai Le, Tran Trung Hieu, Nguyen Thi Lan Huong and Nguyen Thien Minh
MACHINE LEARNING ACCELERATED PROPERTY PREDICTION AND SCREENING OF STABLE LITHIUM-BASED BATTERY MATERIALS
Rapid screening of battery materials is critical to meeting the growing demand for high-performance energy-storage solutions. In this study, we employ a data-driven approach to evaluate and characterize stable lithium-containing compounds with potential applications in next-generation batteries. We retrieved a dataset of 1,846 stable lithium-based materials from the Materials Project database using the mp-api. By leveraging the matminer library, we generated a comprehensive set of composition-based and structure-based features, including elemental- property and density descriptors. A Random Forest Regressor was trained to predict the band gap of these materials, a key electronic property that determines their suitability as electrolytes or electrodes. The model achieved a mean coefficient of determination (????2) of 0.77 ± 0.04 and a mean absolute error (MAE) of 0.48 ± 0.05 eV across 10-fold cross-validation, demonstrating robust predictive capability. Featureimportance analysis revealed that electronegativity and Mendeleev number are the most significant predictors of band-gap energy. These findings underscore the effectiveness of machine learning in accelerating property prediction for battery materials and provide a pathway to more efficient experimental targeting.
COLLECTIVE EXCITATIONS OF A BOSE-EINSTEIN CONDENSATE TRAPPED IN A TWO-CHANNEL POTENTIAL
In this paper, we investigate the collective excitations of an attractively interacting Bose–Einstein condensate confined in a two-channel potential. Using the Bogoliubov approximation, we derive the Bogoliubov–de Gennes equations and determine the excitation spectrum numerically. Two distinct modes are identified: the well-known Josephson mode, associated with periodic inter-channel tunneling, and a novel antisymmetric translational mode, describing out-of-phase oscillations of the condensate center of mass. Unlike conventional dipole oscillations, the latter arises from the interplay between inter-channel coupling and attractive nonlinearity and does not follow the Kohn theorem. We then employ the variational approximation to describe the condensate dynamics under these excitations and to extract the corresponding mode frequencies. The results are further validated by real-time simulations of the governing Gross–Pitaevskii equations, showing good agreement between analytical and numerical approaches.
PROPER HOLOMORPHIC MAPS AND B−REGULAR DOMAINS IN Cn
We begin by proving that B-regularity is preserved under proper holomorphic mappings of domains. We next investigate B-regularity in the setting of bounded Reinhardt domains in Cn. These results together demonstrate that B-regularity can be carried from well-understood Reinhardt model domains to more complicated domains via explicit proper holomorphic maps.
GLOBAL ATTRACTOR FOR A CLASS OF REACTION-DIFFUSION SYSTEMS
We study the initial boundary value problem for a class of reaction-diffusion systems in bounded smooth domains, where one equation has a small diffusion coefficient δ > 0, and also the corresponding limit system is formally obtained when δ = 0. We prove the existence of global attractor Aδ for the dynamical system generated by the system in both cases δ > 0 and δ = 0. Moreover, the upper semicontinuity of the global attractor Aδ at δ = 0 is also investigated.
ON CONVEX COMBINATIONS OF GRAZING LINEAR MODES FOR 2-DEGREE-OF-FREEDOM VIBRO-IMPACT SYSTEMS WITH 1:2 RESONANCE
Grazing periodic orbits in vibro-impact mechanical systems are known to generate nonlinear normal modes. In the absence of internal resonance, many of the essential dynamical features already appear in two-degree-of-freedom (2-dof) mass–spring chains. In this note, we focus on such a system under the simplest internal resonance condition. Two grazing linear modes, denoted as GLOM1 and GLOM2, associated with the first and the second linear modes, play a key role.We will show that the grazing linear orbit generating one-impact-per-period (1IPP) solutions is neither GLOM1 nor GLOM2, but rather a convex combination of the two. This leads to the introduction of the set GLOc = [GLOM1, GLOM2] of grazing linear orbits. For all GLOc except the endpoint modes, the free-flight time to impact admits a particularly simple structure, providing a convenient framework for the future study of the nonlinear behavior of such grazing linear orbits.
GEOHERITAGE VALUES OF THE TRANSBOUNDARY WORLD HERITAGE OF PHONG NHA-KE BANG NATIONAL PARK AND HIN NAM NO NATIONAL PARK
Located on the same karst plateau, Phong Nha - Ke Bang and Hin Nam No National Parks have common characteristics of karst geology, geomorphology, and hydrology. Using a geoheritage approach with field surveys, laboratory analyses, document synthesis, and comparative analysis, the geoheritage’s outstanding universal values of Phong Nha - Ke Bang - Hin Nam No have been clarified and supplemented. These values include a long geological and geomorphological evolution from the Middle Cambrian to the Quaternary; the world's largest area of pristine humid tropical karst, featuring a diversity in both surface and subsurface landforms with many global and regional records; and Triassic - Middle Jurassic paleokarst in the form of buried surfaces and filled fissures and caves, a new outstanding universal value unrepresented in the current World Heritage sites.
Mai Thanh Tan, Vu Thi Minh Nguyet and Tran Thi Thuy Van
CHARACTERISTICS OF THE LANDSCAPE CLASSIFICATION SYSTEM OF COMMUNES: CHO RA, BA BE, PHUC LOC, THUONG MINH AND DONG PHUC, THAI NGUYEN PROVINCE
The paper builds a landscape classification system to clarify the characteristics of landscape units in the communes of Cho Ra, Ba Be, Phuc Loc, Thuong Minh, and Dong Phuc, Thai Nguyen province. The diversity and spatial differentiation of the landscape of the area are shown through the model diagram of the landscape classification system; four landscape component maps and landscape (synthesis) maps of the five communes at the same scale of 1:50,000. The landscape units of the area are arranged into a system of seven levels, including one landscape system, one landscape subsystem, one landscape type, three landscape classes, five landscape subclasses, six landscape classes, and one hundred and nineteen types of landscape. The research results provide a database for studies on the use of landscapes for local purposes and a basis to help managers develop planning, orientation for use, and conservation of the landscape here in a reasonable and sustainable way.
Dinh Hoang Duong, Ngo Thi Hai Yen, Do Van Thanh, Kieu Van Hoan, Nguyen Van Manh and Vu Thi Thu Thuy
EFFECT OF ULTRASOUND TREATMENT COMBINED WITH SODIUM HYDROGEN SULFITE ON THE QUALITY OF POSTHARVEST LONGAN FRUIT
Longan is one of the fruits with a high economic value in Vietnam and is grown in both Northern and Southern provinces. However, the quality of longan fruits deteriorates quickly after harvest. The study aimed to combine ultrasound (US) treatment with a sodium hydrogen sulfite (SHS) solution as the wave transmission medium to reduce color changes and maintain the quality of longan fruit during storage at 25 ℃. Longan fruit was treated with US at a frequency of 192 kHz combined with SHS solutions at concentrations of 0.25% and 0.5% (w/v) for 1.5, 2.5, and 5.0 minutes. The results showed that the 0.5% SHS + US 1.5 min treatment effectively delayed color change of longan peel and reduced weight loss of the fruit, but did not affect the edible quality, including total titratable acidity and soluble solid content (oBrix), while maintaining vitamin C, total phenolic content, and antioxidant activity of longan fruit, compared to the control during 8 days of storage at 25 ℃. These results suggest that ultrasound treatment combined with sodium hydrogen sulfite can be potentially used for the preservation of longan fruit.
Nguyen Trung Truc, Huynh Khanh Thi, Duong Thi Cam Nhung
EATING BEHAVIORS ASSOCIATED WITH THINNESS AMONG 9 TO 12-YEAROLD STUDENTS AT 915 GIA SANG PRIMARY AND SECONDARY SCHOOL, THAI NGUYEN CITY: A DECISION TREE ANALYSIS
Thinness is a persistent but understudied form of undernutrition among school-aged children in Vietnam, especially in peri-urban settings. This study focused on students aged 9 – 12 at Gia Sang Primary and Secondary School in Thai Nguyen, aiming to identify key eating behavior patterns associated with thinness using decision tree analysis as a data-driven approach for nutritional risk classification. A cross-sectional study was conducted with 157 students at Gia Sang Primary and Secondary School in Thai Nguyen, Vietnam. Nutritional status was assessed using body mass index-for-age Z-scores in accordance with WHO (2007) standards. Eating behaviors were measured using the validated Children’s Eating Behavior Questionnaire (CEBQ), comprising eight behavioral subscales. Anthropometric data were collected following standardized procedures. Pearson correlation analysis, logistic regression, and decision tree modeling were applied to examine associations and classify thinness risk. Results showed that 14.0% of participants were classified as thin and 11.5% as overweight, reflecting the double burden of malnutrition. Logistic regression analysis indicated that Satiety Responsiveness (SR) and Slowness in Eating (SE) were significant predictors of thinness (P < 0.05). More notably, decision tree analysis revealed distinct high-risk profiles: children with high Desire for Drinks (DD ≥ 3.8) and low SR (< 2.4) had an 80% probability of being thin, while those with low DD combined with low Food Fussiness (FF), Emotional Overeating (EOE) scores, and SE had a 62% probability. These findings highlight the added value of decision tree modeling in capturing complex interactions among eating behaviors associated with thinness. They also suggest the potential of using behavioral screening tools like the CEBQ for early identification of nutritional risk and for informing targeted, behaviorally tailored interventions within school-based health programs.
Duong Thi Anh Dao, Nguyen Thi Hong Hanh, Pham Thao Linh, Le Thi Tuyet, Nguyen Thi Trung Thu, Nguyen Thi Bich Ngoc, Nguyen Phuc Hung, Le Ngoc Hoan and Do Thi Nhu Trang
EFFECTS OF ALCOHOL-SOLUBLE COMPONENTS IN SOYMILK RESIDUE ON PLASMA LIPID LEVELS, LIPID DIGESTION AND BODY WEIGHT GAIN IN SWISS MICE
The present study was conducted to examine the effects of alcoholsoluble components (alcohol extract, AE) in soymilk residue (SR) on body weight gain, plasma lipid levels, and lipid digestion in Swiss mice. Aqueous ethanol was used to extract the SR, afterwhich the residue and the supernatant were separated. The supernatant was then dried to produce the AE. Four experimental diets were formulated and designated as CD (control diet), CD+AE20 (CD supplemented with 20 g AE/kg), CD+AE40 (CD supplemented with 40 g AE/kg), and CD+AE60 (CD supplemented with 60 g AE/kg). Six mice (with an initial body weight of 24 g) were distributed into each of eight cages, with two replicate cages per dietary treatment. The experimental mice were fed with the test diets ad libitum for 4 weeks. The results showed that the final body weights of mice fed with AEsupplemented diets were lower than those fed with the control diet, while no differences in feed intake were found among the treatments. Moreover, the AE significantly reduced body weight gain with significant differences observed in mice receiving AE supplementation levels of 40 and 60 g/kg. The mice fed with AE-supplemented diets exhibited lower plasma concentrations of total cholesterol, low-density lipoprotein, and triglyceride as well as lower intestinal total bile acid level and lipase activity, but higher lipid content in feces, compared with those fed with the control diet. These findings indicated that the AE in SR negatively affected the lipid digestion process, therefore reducing plasma cholesterol levels and body weight gain in Swiss mice.
Dao Ngoc Anh, Nguyen Manh Duc and Nguyen Phuc Hung
COMPARATIVE ASSESSMENT OF SOIL PROPERTIES IN ORGANIC, CONVENTIONAL, AND ABANDONED VEGETABLE CULTIVATION SYSTEMS IN VEGETABLE-GROWING AREAS OF HANOI
The application of fertilizers and agrochemicals in crop cultivation can significantly affect the physicochemical properties and nutrient composition of vegetable soils. In this study, soil samples were collected from eighteen vegetable fields managed under organic farming, conventional farming, and abandoned land-use systems across four specialized vegetable-producing communes in southern Hanoi. Results indicated that the cultivated soils were mainly loamy and sandy loam soils, both suitable for vegetable production. Physical, chemical, and nutrient parameters varied among cultivation systems. Organic farming soils showed the best quality in terms of physicochemical properties, organic matter content, and macro- and micronutrient contents. Conventional farming soils contained higher concentrations of macro- and micronutrients compared to abandoned fields, but exhibited lower organic matter content. Organic farming soils have BD: 1.08 g/cm3, PD: 2.62 g/cm3, OC: 1.34%, N: 0.12%, P2O5: 0.21%, K2O: 0.95, CEC: 13.07 cmol/kg of air-dried soil. Conventional farming soils exhibited BD: 1.18 g/cm3, PD: 2.47 g/cm3, OC: 1.09%, N: 0.10%, P2O5: 0.35%, K2O: 0.74, CEC: 11.87 cmol/kg of air-dried soil. The cultivation of organic vegetables not only ensures a safe and health-promoting food supply for humans but also contributes to environmental protection and the improvement of soil quality. This practice represents a sustainable approach to soil utilization and should be actively promoted for wider adoption.
MORPHOLOGICAL AND ANATOMICAL ADAPTATIONS OF THE TUBER FOR PARASITISM IN THREE SPECIES OF Balanophora J.R. Forst. et G. Forst. FROM MU CANG CHAI, YEN BAI
The genus Balanophora J.R. Forst. et G. Forst. (Balanophoraceae) includes obligate holoparasitic plants that lack chlorophyll and are completely dependent on their hosts for water and nutrients. This study investigates the morphological and anatomical characteristics of the tuber in three Balanophora species (B. fungosa, B. laxiflora, and B. harlandii) collected from Mu Cang Chai, Yen Bai, Vietnam. Detailed observations were conducted to describe the structural adaptations related to parasitism, focusing on the organization of the tuber and the development of composite bundles that form the host–parasite interface. The results reveal that the tuber functions as a highly specialized parasitic organ, consisting of an outer cortex, matrix parenchyma, parasite vascular bundles, and composite bundles. The composite bundles play a pivotal role in resource exchange between the host and the parasite, with transfer cells facilitating efficient nutrient absorption. These findings provide new insights into the structural and functional adaptations of Balanophora, contributing to a better understanding of the evolutionary strategies of holoparasitic plants.
Cao Hoang Tuan, Luong Van Dung, Nguyen Dao Cam Tu, Tran Thuy Linh, Tran Vu Kim Anh and Bui Thu Ha
REMARKABLE RECORDS OF MAMMALS AND CONSERVATION STATUS OF Sundasciurus hippurus AND Macaca fascicularis FROM U MINH HA NATIONAL PARK, SOUTHERN VIETNAM
U Minh Ha is one of the most prominent national parks in southern Vietnam; however, its mammalian fauna remains poorly studied. To address this gap, we conducted a field survey using camera traps and direct transect observations between June and July 2024. The survey yielded photographic records of eight confirmed species (Tupaia belangeri, Macaca fascicularis, Rattus tanezumi, Sundasciurus hippurus, Prionailurus bengalensis, Lutra sumatrana, Paradoxurus hermaphroditus, and Sus scrofa) representing eight genera, eight families, and five orders. Among these, M. fascicularis and L. sumatrana are listed as Endangered, and S. hippurus as Near Threatened on the IUCN Red List. Notably, M. fascicularis and S. hippurus were frequently recorded throughout the park, while L. sumatrana was documented only twice. Other mammalian taxa, such as bats, were also observed but excluded from the present study pending further taxonomic and conservation assessment. This study provides valuable records supported by verified photographs for all eight documented mammal species, offering robust confirmation of their presence in U Minh Ha National Park. Overall, our findings underscore the park’s importance as a potential hotspot for future research on mammalian diversity and broader biodiversity, with particular relevance to ecological patterns, species distribution, and conservation efforts in Vietnam and the wider Southeast Asian region.
Vu Dinh Thong, Nguyen Van Viet, Pham Van Nha, Vo Trong Tai, Nguyen Hoang Thien, Nguyen Khanh Luong, Nguyen Tan Truyen, Tran Quoc Khai, Ngo Khang Duy, Nguyen Thanh Luong, Le Thi My Thanh and Hoang Trung Thanh
MORPHOLOGICAL AND PHASE EVOLUTION OF COBALT SULFIDE ON CARBON CLOTH VIA CONTROLLED HYDROTHERMAL SYNTHESIS FOR HIGH-PERFORMANCE FLEXIBLE SUPERCAPACITORS
Cobalt sulfide nanoparticles were successfully synthesized on carbon cloth (CC) via a one-step hydrothermal method, with varying precursor ratios, hydrothermal temperatures, and hydrothermal times. The crystalline structure, morphology, and composition of the as-prepared CoS were analyzed using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM, and energy-dispersive X-ray spectroscopy (EDS). Structural analyses confirmed the formation of the hexagonal phase of CoS. Electrochemical measurements revealed that the CoS electrode, prepared with a Co:S ratio of 1:2 at 160 oC for 15 h, exhibited the highest specific capacitance of 424 F g-1 at a current density of 1 A g-1 and 350 F g-1 at a current density of 5 A g-1. Moreover, the electrode also demonstrated excellent cycling stability, retaining approximately 90 % of its initial specific capacitance after 1000 charge-discharge cycles at a current density of 2 A g-1. These results highlight a facile, cost-effective, easy-to-implement, and efficient method for utilizing cobalt sulfide-based electrodes for flexible supercapacitor applications.
Nguyen Dinh Hung, Dang Van Cu, Le Quang Huy, Luong Thi Thu Thuy and Le Van Khu
CHARACTERIZATION OF A CHITOSAN/POLYANILINE FILM LOADED WITH LOVASTATIN
This research aims to address these challenges by dispersing the drug within both a single biopolymer matrix (chitosan) and a dual biopolymer matrix (chitosan/polyaniline). The results indicated that, among the single-matrix chitosan/lovastatin (CsL) samples, the CsL10 CsL10 exhibits the most favorable drugrelease behavior over 30 h, achieving a cumulative release of 96% in simulated intestinal fluid (pH 7.4) while providing effective drug protection of 10.5% in simulated gastric fluid (pH 2.0). These findings suggest a promising platform for further development. Building upon this direction, the study was extended to incorporate polyaniline to enable live-function monitoring and tissue stimulation. The results showed that the chitosan/polyaniline/lovastatin (CsPL) samples met the initial expectations, with the CsPL7 sample exhibiting drug release rates of 92.23% and 18.58% in the simulated intestinal and gastric environments, respectively. Analytical techniques, including FT-IR, FESEM, DSC, and UV-Vis, were employed to gain a deeper understanding of the interactions between the polymer components and the drug substance.
Nguyen Dang Dat, Vu Thi Huong and Vu Quoc Trung
DENSITY FUNCTIONAL THEORY APPROACH IN INVESTIGATING STRUCTURAL AND ELECTRONIC PROPERTIES OF BISMUTH-BASED PHOTOCATALYSTS
Utilizing Density Functional Theory (DFT) as the computational method, we aimed to gain insights into the structural and electronic characteristics of Bibased photocatalysts, particularly bismuth tungstate and bismuth molybdate. Both materials exhibit an orthorhombic structure and belong to the space group Pca21 under certain conditions. The exchange-correlation functional used throughout the study was the Perdew-Burke-Ernzerhof (PBE) functional within the generalized gradient approximation (GGA), enabling detailed analyses of their crystal structure, electronic band structure, density of states, and charge density. The electronic properties of both photocatalysts exhibit similar features as expected from the similarities in crystal structure. Notably, bismuth molybdate has a narrower band gap than bismuth tungstate, attributed to the atomic size difference between molybdenum and tungsten. The results confirm their semiconductor nature, highlighting their potential for sustainable-energy photocatalytic applications.
Nguyen Huyen Nhung and Tran Phan Thuy Linh
MICROSATELLITE HYBRID STRUCTURE USING ALUMINUM 7075-T6 AND CFRP FOR IMPROVED LAUNCH PERFORMANCE SURVIVABILITY
This study presents the structural design and simulation of a 50 kg-class microsatellite developed for compatibility with the JAXA Epsilon launch vehicle. A hybrid architecture combining Aluminum 7075-T6 and Carbon Fiber Reinforced Polymer (CFRP) was employed to meet stringent mass, stiffness, and vibration requirements. The final structure, measuring 480 × 488 × 550 mm, achieved a total mass of 45 kg, falling within the required launch envelope. Finite element simulations were conducted using ANSYS 2024R2 to evaluate modal, sine-sweep, random vibration, and shock responses under launch-induced conditions. The first three natural frequencies, 118.99 Hz (X-axis), 123.77 Hz (Y-axis), and 240.42 Hz (Z-axis), surpassed the required thresholds, avoiding resonance with vehicle-induced excitations. Vibration analyses confirmed that peak acceleration responses remained within safe operational margins, with sine-sweep, random vibration, and shock responses showing no modal amplification. Component-level stress simulations revealed von Mises stress values well below material limits across all critical subsystems. These results validate the structural integrity and dynamic survivability of the hybrid microsatellite, demonstrating its readiness for spaceflight.
Nguyen Thuy Linh, Nguyen Cong Thai, Le Xuan Huy and To Anh Duc
BUILDING A VIETNAMESE MATH CHATBOT BASED ON RAG AND LLM: SYSTEM DESIGN, IMPLEMENTATION AND EXPERIMENTAL EVALUATION
In recent years, large language models (LLM) and Retrieval-Augmented Generation (RAG) techniques have opened up new opportunities for the development of intelligent learning assistant systems. Nevertheless, the direct application of LLMs to Vietnamese Mathematics still has several limitations, including the illusion effect, a lack of knowledge base, failures to adhere to the Vietnamese education curricula, and difficulty in proceessing complex-related image issues. This paper presents the design, implementation, and experimental evaluation of a Vietnamese Mathematics Chatbot system based on the RAG architecture combined with LLM. The system comprises: (i) a pineline for collecting and standardizing Mathematics data from textbooks, exam questions and reference materials; (ii) a Milvus vector database to store embeddings generated by the BGE-m3 model; (iii) a multi-task pipeline coordinated by LangGraph; (iv) the inference component uses the Qwen3-VL-8B model implemented via vLLM; and (v) the WebUI user interface supports multimodal queries (text + image). Experimental results show that the system competently delivers detailed solutions, maintains the conversation flow, and significantly mitigates hallucination compared to pure LLM. The system also demonstrates potential for application in teaching and learning Mathematics, especially in situations requiring accurate knowledge retrieval and step-by-step explanations. These results suggest directions towards developing specialized learning assistants within the context of Vietnamese education.
DIFFERENTIAL VARIATIONAL INEQUALITIES VIA THE EXTENDED LASALLE’S INVARIANCE PRINCIPLE APPROACH
In this work, we establish an extended LaSalle’s invariance for a class of nonautonomous differential inclusions in Euclidean spaces. We also give sufficient conditions for the stability of an equilibrium of differential variational inequalities. Special cases as linear complementarity problems, based on LaSalle’s invariance in both autonomous and non-autonomous cases, are also studied in this paper.
OPTIMAL ATTENUATION CONTROL OF 2-D POSITIVE ROESSER SYSTEMS WITH BOUNDED DISTURBANCES
In this paper, performance analysis and controller design problems subject to an optimal attenuation level are studied for 2-D positive systems with bounded input disturbances. First, some novel comparison techniques for state estimations subject to peak values of external disturbances are presented to derive a characterization for l∞-induced norm of the input-output operator. Then, we derive the necessary and sufficient linear programming (LP) conditions for obtaining a controller gain of an l∞-induced performance with a prescribed attenuation level. Numerical examples are given to illustrate the effectiveness of the proposed method.
ROOTS OF COMPLEX HARMONIC POLYNOMIALS IN ONE VARIABLE
In this paper, we establish some bounds on the moduli of the zeros of complex harmonic polynomials in one variable. We also present explicit examples that illustrate these results. Our findings contribute to a deeper understanding of zeros of complex harmonic polynomials in one variable.