HNUE Journal of Science: Journal of Natural Sciences
HNUE Journal of Science: Natural Sciences (HNUE JoNS) has the international standard series number ISSN: 2354-1059, publish original research in natural sciences and engineering including mathematics, biology, chemistry, informatics, geographics and physics. This journal is indexed by the State Council for Professor of Vietnam for publications in Biology , Geography, Physics and Chemistry as 0.75/1.0 points, and 0.5/1.0 points for publications in Mathematics and Information Technology. HNUE JoNS publishes quarterly in March, June, September and December.
THE \(e^−e^+\) PRODUCTION VIA \(\gamma\gamma\) COLLISION IN THE RANDALL-SUNDRUM MODEL AT THE ILC
Taking into account the 125 GeV Higgs boson and radion propagators, we investigate the e−e+ production via \(\gamma\gamma\) collision in the Randall-Sundrum model at International Linear Collider (ILC). The observable cross-sections are calculated for the diphoton collision. The cross-sections are evaluated with dependence on the collision energy \(\sqrt{s}\), the polarization of electron and positron beams.
PRODUCTION OF HIGGS IN TWO PHOTON COLLISION
The Higgs production was studied using the Randall-Sundrum model from photon-photon collision. The independent parameters in the Randall-Sundrum model: the vacuum expectation value of the radionfield \(\Lambda_\phi\), the radion mass \(m_\phi\), the Higgs mass \(m_h\) and ξ must be specified to fix the state mixing parameters. The total cross-section has been evaluated as the function of the parameters \(\Lambda_\phi\), ξ, the collision energy \(\sqrt{s}\) and the result shows the advantageous direction to observe the Higgs boson.
Higgs production, photon collision, Randall-Sundrum model
\(e^+e^−\) \(\rightarrow\) hh AND \(e^+e^−\) \(\rightarrow\) ɸh COLLISION IN THE RANDALL-SUNDRUM MODEL
Although the Standard Model (SM) describes successfully almost all existing experimental data, the model suffers from many theoretical drawbacks. Some models have been suggested that involve extra dimensions. One models which can solve the hierarchy problem is the Randall-Sundrum model (RSM). The RSM involves two three-branes bounding a slice of 5D compact anti-de Sitter. Gravity is localized in the hidden brane while the SM fields are supposed to be localized in the visible brane. The fluctuations for the size of the extra dimension are characterized by the scalar component of a matric called the radion (ɸ). The phenomenological similarity and the mixing potential of the radion and the Higgs boson warrant detailling to distinguish them at colliders. We study e+e−\(\rightarrow\)hh and e+e− \(\rightarrow\) ɸh collisions in RSM.
Higgs boson, potential mixing, Randall-Sundrum model
Copyright (c) 2026 Journal of Science Natural Science
APPROXIMATELY COHEN–MACAULAY PROPERTY OF EDGE-WEIGHTED CYCLES
In this paper, we investigate the approximately Cohen-Macaulay property of edge ideals associated with edge-weighted graphs. Our main result establishes that the edge ideal I(Cn,w) of an edge-weighted cycle graph of order n is approximately Cohen-Macaulay if and only if n = 3 or n = 5. The proof heavily relies on the algebraic properties of sequentially Cohen-Macaulay modules, Woodroofe graphs, and Goto’s characterization of approximately Cohen-Macaulay rings.
approximately Cohen–Macaulay, edge-weighted graph, Woodroofe graph
SPECTRAL FLUCTUATION ANALYSIS REVEALS VARIATIONIN CICADA ADVERTISEMENT-SONG STRUCTURES
Understanding song structure is a fundamental step in any bioacoustic study because it provides a basis for interpreting signal production and behavioral function. Previously, an analytical framework based on spectral fluctuation analysis of peak frequency and amplitude was proposed, considering peak frequency as a species-specific signal perceived by females. In this study, advertisement songs of three cicada species with varying structural complexity, Cryptotympana atrata, Graptopsaltria nigrofuscata, and Meimuna opalifera, were analyzed to evaluate the applicability of this framework. Spectral fluctuations were examined using the strucchange package in R, and generalized linear regression models were fitted between peak frequency and root-mean-square amplitude to identify structural breakpoints. The results showed that songs of C. atrata were primarily divided into two non-repetitive parts, whereas G. nigrofuscata produced songs comprising five distinct segments. In M. opalifera, advertisement songs consisted of five sequential parts, each containing multiple frequency- and amplitude-modulated echemes. These findings demonstrate the robustness of the proposed approach in identifying song structures across species with different levels of complexity and provide an informative foundation for subsequent bioacoustic and behavioral studies.
spectral fluctuation analysis, advertisement song, cicada
FIRST RECORD OF JUMPING SPIDER Colyttus yiwui (Lin & Li, 2020) (Salticidae) FROM VIETNAM
The jumping spider Colyttus yiwui Lin & Li, 2020 (Araneae: Salticidae) is reported for the first time from Vietnam. Specimens, including both males and females, were collected through hand-picking from understorey vegetation in Son La Province, northwestern Vietnam, during fieldwork conducted in 2024 and 2025. The study provides detailed morphological descriptions, measurements, and illustrations of the genital structures for both sexes. The general morphology and genital structures of the specimens are consistent with the original description from Yunnan, China. This record extends the known distribution range of Colyttus yiwui southward from China to Vietnam, contributing new data on the Salticidae fauna of the Indochina region.
Vietnam, new record, taxonomy, Araneae, Salticidae, Colyttus yiwui
THE EFFECT OF POLYANILINE ON THE CHARACTERIZATION OF ALGINATE/CARRAGEENAN/POLYANILINE FILM LOADED WITH LOVASTATIN
Lovastatin (Lov), a potent inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, has limited clinical utility because of its poor aqueous solubility and suboptimal pharmacokinetics, characterized by low oral bioavailability (<5%) and a short elimination half-life. To overcome these limitations, a novel pH-responsive drug delivery system was developed by integrating the conductive polymer polyaniline (PANi) into a natural biopolymer matrix of sodium alginate (Alg) and κ-carrageenan (Carr). A series of Lov-loaded alginate/carrageenan/polyaniline/lovastatin (ACPL) biocomposite films containing different PANi content (3–15% w/w) were prepared by in situ oxidative polymerization and solvent casting. Structural and thermal characterization through Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy, and differential scanning calorimetry confirmed that lovastatin was successfully stabilized within the ternary matrix through an intermolecular network of hydrogen bonding and van der Waals interactions, effectively preserving its chemical integrity while disrupting its crystalline lattice. Morphological analysis revealed that the incorporation of PANi significantly refined the drug's particle size from a micro-scale (10–60 μm) to a sub-micron dispersion (0.05–0.20 μm), with the ACPL5–alginate/carrageenan/polyaniline/lovastatin formulation, incorporating 5% polyaniline relative to the alginate/carrageenan polymer matrix, exhibiting the most homogeneous distribution. In vitro release studies demonstrated superior site-specific performance; all formulations provided robust gastric protection at pH 2.0 (release <10%), while ACPL5 achieved a near-quantitative sustained release of 97.53% at pH 7.4 within 30 h. These results demonstrate that the Alg/Carr/PANi composite, particularly at a 5% PANi loading, is a highly effective vehicle for modulating release kinetics and potentially enhancing the therapeutic efficacy of hydrophobic statins.
alginate/carrageenan/PANi, lovastatin, biocomposites, drug delivery
DYNAMIC EQUATIONS WITH TIME-VARYING DELAY ON TIME SCALES
This paper investigates dynamic delay equations on time scales. Due to the lack of a well-defined subtraction, the formulation of delay equations in this setting is nontrivial. We first introduce a suitable representation of delay dynamic equations on time scales. We then prove the existence and uniqueness of solutions, as well as the uniform exponential stability for Δ-dynamic delay equations via Lyapunov direct method. The obtained results extend existing works and provide verifiable conditions in the framework of time scale calculus.
dynamic delay equation, uniform stability, exponential stability, Lipschitz condition; Lyapunov function
PREPARATION AND CHARACTERIZATION OF POLYCAPROLACTONE MICROPARTICLES LOADING CERIUM(III) NITRATE
This study reports the fabrication of cerium(III) nitrate-loaded polycaprolactone (PCL) microparticles via a water-in-oil-in-water (W/O/W) double emulsion method, utilizing Sapindus saponaria L. extract as a natural, eco-friendly surfactant. The salt-to-polymer ratio significantly influenced the encapsulation process, with the PC75 formulation achieving an optimal encapsulation efficiency of 26.83%. Dynamic light scattering and zeta potential measurements showed that the microparticles (PC50 and PC75) possessed nanoscale dimensions (280–310 nm) and high colloidal stability (zeta potential < -30 mV). FESEM and EDX characterizations revealed a spherical morphology with a core-shell architecture, while FTIR and XRD analyses verified that the cerium nitrate was successfully embedded within the PCL matrix without altering the polymer's semicrystalline structure. These results demonstrate that the synthesized PCL microparticles, stabilized by a plant-derived surfactant, serve as promising candidates for the development of sustainable, controlled-release additives in anti-corrosion coating applications.
polycaprolactone, cerium (III) inhibitor, microparticles
STRUCTURAL PROPERTIES AND CRYSTALLIZATION OF DENSIFIED BORON SILICON NITRIDE: INSIGHTS FROM MOLECULAR DYNAMICS SIMULATION
We used molecular dynamics (MD) simulations to investigate the structural properties of boron silicon nitride (B-Si-N) under high pressure. The B-Si-N sample was cooled from 5000 K to 300 K at a constant pressure of 60 GPa. At 4000 K and 3500 K, the structure remained disordered. As the sample was cooled, a phase transition occurred between 3500 K and 3000 K. Common-neighbor analysis (CNA) showed that nitrogen atoms in the Si-N-rich region began to form crystalline clusters with face-centered cubic (FCC) and hexagonal close-packed (HCP) arrangements. Most clusters adopted FCC-like local ordering of nitrogen atoms, whereas a smaller fraction exhibited HCP ordering. The crystallization mechanism is discussed in detail.
molecular dynamics, B-Si-N, crystallization, structural properties
CHARACTERIZATION OF THE NUTRITIONAL COMPOSITION, PH, AND COLOUR ATTRIBUTES OF KING ORANGE (Citrus sinensis) JUICE FROM DIFFERENT CULTIVATION REGIONS IN VIETNAM
In Vietnam, king oranges are cultivated throughout the country, especially in the Tuyen Quang, Bac Ninh, Phu Tho, Lang Son, Vinh Long, and Dong Thap provinces, occupying large cultivation areas and contributing substantially to national production. Therefore, the objective of this study is to determine the nutritional composition, pH, and colour indexes of king orange juice in different cultivating regions, in order to provide a scientific basis for developing a process for industrial scale bottling and long-term preservation of king orange juice, which is essential and has high scientific and practical significance. The process involved several steps, extracting and collecting the juice from king oranges, then using physicochemical, biochemical, and sensory analysis methods to determine several nutritional indicators, pH levels, and the colour of the king orange juice. The research results showed that the Tuyen Quang king orange juice had higher soluble solids, total sugar content, vitamin C content, vitamin A content, and pH value than other orange juices. Specifically, king orange juice from Tuyen Quang exhibited a soluble solid of content of 10.93 ± 0.9 (oBx), a total sugar content is 10.39 ± 0.8 (g/100mL), a vitamin C content is 14.36 ± 0.4 (μg/100mL), a vitamin A content is 53.16 ± 1.2 (mg/100mL), a protein content is 1.32 ± 0.3 (g/100mL) and a pH value is 4.3 ± 0.2. Among the six king orange juices evaluated, the Tuyen Quang king orange juice had a brighter, more characteristic, and more attractive yellow colour than the other samples. These results suggest that soil conditions, weather, climate, and growing conditions also affect the nutritional components and colour of king orange juice.
colour, different cultivating regions, king orange juice, nutritional components
COMPOSITION OPERATORS ON PLURIHARMONIC HARDY SPACES ON THE UNIT BIDISC
In this paper, we study composition operators induced by holomorphic maps Φ = (ϕ, ψ) : \(\mathbb{D}\)\(\rightarrow\)\(\mathbb{D}\)2 acting from the pluriharmonic Hardy space \(H_h^2(\mathbb{D}\)2) into \(H_h^2(\mathbb{D}\)2). Using a structural decomposition of pluriharmonic functions on the bidisc into holomorphic and anti-holomorphic parts, we reduce the underlying problem to estimates on classical holomorphic Hardy spaces. These results extend the corresponding holomorphic theory to the pluriharmonic Hardy setting on the bidisc.
composition operators, Hardy spaces, analytic functions, pluriharmonic functions
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.
Reaction-diffusion system, limit system, Global attractor, upper-semicontinuity
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 threshold-based 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.
heat extremes; hot days; heat waves; daily maximum temperature;climate trends; Lao Cai province
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.
Collective excitations, Gross-Pitaevskii equation, Bogoliubov - de Gennes equation, Variational approximation
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.
unilateral contact, Grazing linear mode, free flight time, internal resonances
DISTRIBUTION OF BMI-FOR-AGE Z-SCORES BY SEX AND GRADE AMONG STUDENTS AT DAI DONG PRIMARY SCHOOL, NGHE AN PROVINCE IN 2025
The double burden of malnutrition is an emerging public health challenge in rural Vietnam. The body mass index (BMI)-for-age Z-score (BAZ), based on the WHO 2007 growth reference, provides a continuous metric for nutritional assessment in school-age children. Analyzing BAZ according to school grade is particularly informative because school grade reflects children's cumulative educational and nutritional environments; however, such analyses have remained limited in the Vietnamese literature. This study aimed to describe the distribution characteristics of BAZ and to evaluate differences according to sex and school grade among primary school students at Dai Dong Primary School, Nghe An Province, in 2025. A cross-sectional study was conducted among 887 students (458 boys and 429 girls). BAZ values were calculated using WHO AnthroPlus version 1.0.4. Since BAZ was not normally distributed, non-parametric tests were applied. The results showed that overall median BAZ was −0.356 (interquartile range: −1.109 to 0.643), significantly below the WHO reference median of 0 (p < 0.001). The double burden of malnutrition was evident with 19.2% of students classified as overweight or obese, and 6.5% classified as wasted. Boys had significantly higher BAZ values than girls (−0.223 vs. −0.463; p = 0.020) and a nearly threefold higher prevalence of obesity (10.9% vs. 3.7%; p < 0.001). Significant differences in BAZ were observed across school grades (p = 0.041), with Grade 3 having the highest median BAZ (−0.104), which corresponded to the highest prevalence of overweight/obesity (22.4%). In contrast, the prevalence of wasting increased significantly from Grade 1 (6.3%) to Grade 5 (10.3%) and was highest in Grades 4 and 5 (10.7 and 10.3%, respectively; χ² = 20.33, p < 0.001). A double burden of malnutrition exists in this rural primary school population. Grade 3 exhibited the highest burden of overweight/obesity, while upper grades (4–5) showed a marked increase in wasting, underscoring the need for grade-specific nutritional surveillance and targeted interventions.
BMI-for-age Z-score, double burden of malnutrition, primary school children, sex differences, Nghe An
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.
plurisubharmonic function, B-regular domains, Reinhardt domain
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 (R2) 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. Feature- importance 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.
machine learning, battery materials, lithium, band-gap prediction, materials informatics
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.
human-macaque interactions, Macaca mulatta, provision, Son Tra, Da Nang
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 100years. 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 exceeds10% of the total population at that time, the population size will begin to decline and gradually become extinct within 100 years.
Macaca mulatta, Rhesus macaque, population trend, Vortex, Da Nang
USING PLANETSCOPE SATELLITE IMAGERY TO QUANTIFY SHORELINE AND SANDBAR DYNAMICS OF THE GAM RIVER SECTION FLOWING XUAN VAN COMMUNE, TUYEN QUANG PROVINCE
Shoreline and sandbar dynamics directly reflect the morpho-sedimentary equilibrium of fluvial systems. This study employs 3-m resolution PlanetScope satellite imagery integrated with Geographic Information Systems (GIS) to analyse shoreline and sandbar changes along the Gam River section flowing through Xuan Van commune, Tuyen Quang province, during the period 2015-2024. Shoreline and sandbar boundaries were delineated through visual interpretation and manual digitization of multi-temporal PlanetScope imagery in a GIS environment, enabling quantitative assessment of erosion, deposition, and channel migration during 2015-2024. The results indicate that during this ten-year period. The results indicate that during 2015-2019, shoreline displacement was limited (ranging from 10-80 m), with relatively balanced erosion and deposition processes, reflecting a stable morphological condition. From 2019 onward, the shoreline changed significantly, with several areas shifting by more than 300 m. The eroded area markedly surpasses the deposited area, indicating a clear trend toward morphological instability. These changes are closely associated with sandbar dynamics, the meandering river planform, and increasing anthropogenic pressures in the study area. The study confirms that PlanetScope imagery is an effective data source for detecting rapid, reach-scale riverine geomorphic changes and provides quantitative evidence to support river management and erosion mitigation strategies.
shoreline, sandbar, planetScope, remote sensing, geomorphic change
Quan trắc, quản lý các tài nguyên thiên nhiên phục vụ mục tiêu phát triển bền vững
ELECTRONIC PHASES OF THE IONIC HUBBARD MODEL WITH COULOMB DISORDER
We investigate the effects of Coulomb disorder on the half-filled ionic Hubbard model within the framework of dynamical mean-field theory (DMFT), using the equation-of-motion method as the impurity solver, combined with typical medium theory (TMT). In contrast to conventional disordered Hubbard models, the ionic Hubbard model contains a staggered ionic potential that introduces additional competition between band-insulating and correlation-driven insulating tendencies. We analyze how this ionic potential modifies the electronic phases induced by Coulomb disorder through the arithmetic and geometric averages of the local density of states. In the absence of disorder, the system exhibits metallic (M), Mott-insulating (MI), and band-insulating (BI) phases. When Coulomb disorder is introduced, Anderson-insulating (AI) behavior and localized states (LS) inside the Mott gap are also observed. In particular, the LS regime appears between the metallic and Mott-insulating phases at small ionic potentials, whereas the AI regime develops for sufficiently large values of the Coulomb interaction and ionic potential. Our results show that the interplay between ionic potential, electron correlation, and disorder substantially influences the localization behavior and insulating characteristics of the ionic Hubbard model.
Metal–insulator transitions, ionic Hubbard model, Coulomb disorder
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.
rainfall variability, climate change, extreme precipitation, disasterrisk reduction, Phu Tho province
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), a HFD with extract at 300 mg/kg, and a 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.
Garcinia mangostana, mangosteen pericarp, polyphenols, antioxidantactivity, high-fat diet
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 grassland-shrub 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.
Hemiptera, Cicadellidae, species composition, distribution, Xuan Son National Park
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 1600C 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 pproximately 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.
cobalt sulfide, carbon cloth, flexible supercapacitor
Copyright (c) 2025 Journal of Science Natural Science
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.
bat, biodiversity, conservation, monitoring, taxonomy
EFFECTS OF ALCOHOL-SOLUBLE COMPONENTS IN SOYMILK RESIDUE ON PLASMA LIPID LEVELS, LIPID DIGESTIONAND BODY WEIGHT GAIN IN SWISS MICE
The present study was conducted to examine the effects of alcohol-soluble 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 AE-supplemented 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.
alcohol-soluble components, soymilk residue, plasma cholesterol, lipid digestion, weight gain, mice
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.
Math Chatbot, generative artificial intelligence, RAG, large language models, Milvus, vLLM, LangGraph, mathematics education