HNUE Journal of Science: Natural Sciences (HNUEJS.NS) 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. HNUEJS.NS publishes quarterly in March, June, September and December.
SELF-DIFFUSION OF BCC INTERSTITIAL ALLOY FeSi
In this work, we present analytical formulations for self-diffusion parameters, namely the activation energy, pre-exponential factor, and self-diffusion coefficient as functions of temperature, pressure, interstitial atom concentration, and strain in a BCC interstitial binary alloy, derived using the statistical moment method (SMM). These theoretical models are utilized to perform numerical simulations for the FeSi alloy. The computed SMM values for FeSi are compared with those obtained for pure Fe. The SMM results for Fe show strong consistency with existing experimental measurements and alternative computational data. The additional SMM findings are novel and offer predictions that can guide future experimental investigations.
FeSi, self-diffusion, activation energy, pre-exponential factor, self-diffusion coefficient
Copyright (c) 2025 Journal of Science Natural Science
OPTIMAL PARTICLE SIZE OF Ag3PO4 PHOTOCATALYSTS ACHIEVED BY pH-CONTROLLED SYNTHESIS
Silver orthophosphate (Ag3PO4, APO) was synthesized by a simple co-precipitation method using AgNO3 and K2HPO4.3H2O as precursors. The pH of the precursor solution was adjusted by adding a HNO3 solution (0.5 M), which effectively controlled the particle size without altering the crystal structure. The samples in this work were prepared as APO–xH, where x represents the volume (mL) of HNO₃ added (0, 0.5, 1.0, 1.5, 2.0, and 2.5 mL). The particle size decreased systematically from ~450 nm (APO–0H) to ~150 nm (APO–2.5H). APO–1.5H, with an average size of ~250 nm, represented the “optimal size,” achieving complete degradation of 10 ppm Rhodamine B within 14 minutes under visible light irradiation from a 50 W compact fluorescent lamp, twice as fast as pristine APO. In preliminary cycling performed only on the reference APO–0H sample, the RhB degradation efficiency decreased to ~30% by the fifth cycle under visible-light irradiation. These findings confirm that the optimal photocatalytic activity of Ag3PO4 does not originate solely from increased surface area but from a balance between particle size, morphology, and structural stability. This work provides a simple approach to tailor Ag3PO4 for efficient visible-light-driven water treatment.
photocatalytic, silver phosphate, particle size
PRELIMINARY STUDY OF SPECIES COMPOSITION AND DISTRIBUTION OF BEETLES (INSECTA: COLEOPTERA) IN DU GIA COMMUNE, DU GIA NATIONAL PARK - DONG VAN KARST PLATEAU, TUYEN QUANG PROVINCE
This study investigated the species composition and distribution of beetles across three habitats in Du Gia commune, located within Du Gia National Park - Dong Van Karst Plateau, Tuyen Quang Province. The study employed a direct survey of beetles across three habitats, conducted over three sampling periods. A total of 39 beetle species, belonging to 10 families and 33 genera, were recorded. The family Coccinellidae contained the highest number of taxa, with 13 species (33.33%) and 10 genera (30.30%). Three families, Phalacridae, Ptinidae, and Scarabaeidae, had the lowest number, each with one species (2.56%) and one genus (3.03%). The distribution of beetle species varied among habitats. The natural forest habitat supported the highest diversity, with 38 species (97.45%) recorded; followed by the grassland and shrub habitat on the mountainside with 34 species (87.18%); and the agricultural land and fruit tree habitat with 24 species (61.52%). The composition of beetle species also varied across survey phases. Phase 1 (October 2024) yielded the highest species richness, with 39 species recorded (100%); Phase 2 (January 2025) with 21 species (53.85%); and Phase 3 (March 2025) with 35 species (89.74%).
species composition, distribution, beetles, Du Gia commune, Du Gia National Park - Dong Van Karst Plateau, Tuyen Quang
ASSESSMENT OF METEOROLOGICAL DROUGHT SEVERITY IN THE FORMER HA GIANG PROVINCE, NORTHERN VIETNAM
The former Ha Giang Province in Northeastern Vietnam, characterized by complex mountainous terrain and climatic variability, is prone to drought. This study assesses meteorological drought severity using the aridity index (K) and monthly drought frequency (P), derived from meteorological data (1960–2024) collected at 18 meteorological, hydrological, and rainfall stations across the study area. Results show that monthly K values ranged from 0.1 to 3.1, peaking in February, while annual averages ranged from 0.1 to 0.5. Based on P, drought severity was classified into three levels: mild, moderate, and severe, with the highest frequencies in December and April. These findings provide a scientific basis to support disaster prevention and drought mitigation efforts in the region.
meteorological drought, Ha Giang, aridity index (K), monthly drought frequency (P)
THE THERMODYNAMIC CONTACT ANGLE IN THE PREWETTING PHASE OF A BINARY BOSE-EINSTEIN CONDENSATE MIXTURE
To investigate the prewetting state of a Bose-Einstein condensate (BEC) mixture adsorbed on an optical hard wall at zero temperature, we consider a system in which condensate 1 coexists with condensate 2 with the chemical potential held fixed. Using the double parabola approximation (DPA) and solving the coupled Gross-Pitaevskii equations, we derive an analytical expression for the thermodynamic contact angle based on Youngs equation. Although the resulting formula is not algebraically simple, it reveals that complete wetting can occur before the bulk coexistence point is reached, indicating the presence of a continuous (second-order) prewetting transition. Our findings are in agreement with theoretical predictions in the literature and emphasize that the wetting film thickness grows smoothly without a discontinuous jump. This work provides useful guidance for the design of experiments aimed at observing wetting phenomena in Bose-Einstein condensates.
Bose-Einstein condensate, Gross-Pitaevskii theory, Prewetting phase transition, Thermodynamic contact angle
ULTIMATE BOUNDS OF RAPIDLY TIME-VARYING SYSTEMS: AN AVERAGING APPROACH
This paper addresses the problem of state bounding for rapidly time-varying linear systems with bounded disturbances. Based on an averaging method and Lyapunov scheme, we derive an explicit bound on the time-scale parameter for which an explicit form of asymptotic bound of solutions is obtained. An application in fast switching systems is presented to illustrate the effectiveness of the analysis results.
ultimate bounds, rapidly time-varying systems, averaging method
NEW DISTRIBUTIONAL RECORDS AND ACOUSTIC IDENTIFICATION OF HIPPOSIDERID BATS (CHIROPTERA: HIPPOSIDERIDAE) FROM SON LA AND LANG SON PROVINCES, NORTHERN VIETNAM
Son La and Lang Son provinces exemplify the characteristic natural conditions of Vietnam’s northwestern and northeastern regions, respectively. Defined by heterogeneous topography, diverse forest ecosystems, and extensive karst cave systems, these provinces constitute critical habitats supporting rich bat faunas, including species of conservation concern. However, local bat populations are increasingly threatened by illegal hunting, rapid urbanization, wind farm development, and other human activities. To assess the current diversity and conservation status of bats, which have been affected by these factors, we conducted intensive field surveys across representative habitats in Son La and Lang Son provinces with a focus on the family Hipposideridae. Six hipposiderid species were recorded during the surveys: Aselliscus stoliczkanus, Hipposideros armiger, H. cineraceus, H. gentilis, H. khaokhouayensis, and H. poutensis. They are distinct in morphological and acoustic characteristics. Among these, H. khaokhouayensis is globally rare and threatened, being listed as Endangered in Vietnam’s Red Data Book and as Vulnerable on the IUCN Red List of Threatened Species. It was recorded exclusively in Son La province, whereas the remaining five species were captured in both provinces. This study presents the first comprehensive comparative dataset on the echolocation calls of all six hipposiderid species recorded in the study areas, along with new distribution records of H. khaokhouayensis in northwestern Vietnam. These findings provide valuable insights into the regional diversity of Hipposideridae and establish a critical baseline for future taxonomic, ecological, conservation, and long-term monitoring research.
biodiversity, conservation, distribution, echolocation, Hipposideridae
BIVARIATE POLYNOMIAL INTERPOLATION BASED ON LINE INTEGRALS
We study bivariate polynomial interpolation based on line integrals over line segments connecting two points on two fixed straight lines in the plane. We provide a characterization of the sets of segments that uniquely determine the interpolation polynomial. We also construct illustrative examples for specific cases.
Polynomial interpolation, Mean-value interpolation, Line integral
SYNTHESIS, STRUCTURAL STUDIES AND ACETYLCHOLINESTERASE INHIBITION ACTIVITY OF SOME (E)-2-METHOXY-3-NITRO-4-(3-OXO-3-ARYLPROP-1-EN-1-YL)PHENYL ACETATES
A semi-synthetic process from vanillin (isolated from vanilla) was developed to obtain new esters with potential inhibitory activity against the acetylcholinesterase (AchE.). 2-Nitrovanillin was synthesized from vanillin by esterification, nitration, and hydrolysis reactions. Four chalcones were synthesized by acid-catalyzed condensation reaction of 2-nitrovanillin and methyl aryl ketone. The identity of 2-nitrovanillin and four chalcones was confirmed by thin-layer chromatography compared with the known compounds. Subsequent esterification of the chalcones with acetic anhydride yielded four new derivatives of (E)-2-methoxy-3-nitro-4-(3-oxo-3-(aryl)prop-1-en-1-yl)phenyl acetate. The structures of the four new compounds were elucidated by 1H NMR and 13C NMR spectra. The four compounds were evaluated for their inhibitory activity against AChE. and three of them exhibited significant activity.
vanillin, chalcone, acetate, acetylcholinesterase
ASSESSING SOIL EROSION SEVERITY IN TEMPORAL AND SPATIAL PATTERN: A CASE STUDY IN THE PLEIKU PLATEAU, GIA LAI PROVINCE
Soil erosion is one of the major causes of land degradation and negatively impacts the soil environment in the world. There are two approaches to assessing soil erosion severity (SES) in terms of the decline of soil productivity in a given area: (1) classifying actual soil loss according to erosion risk classes, and (2) comparing actual soil loss to soil loss tolerance to classify erosion severity. This paper aims to explore changes in SES during 2005–2015 in the Pleiku Plateau, Gia Lai province, Vietnam, as a case study for comparing the two approaches. Regarding actual soil erosion, the average soil erosion rate declined by 0.16 ton/ha/year in the plateau terrain and increased by 0.02 ton/ha/year in the mountain relief. During 2005-2015, the low erosion risk area decreased by 6,302 ha, while the remaining erosion risk classes increased. With respect to soil erosion severity, the tolerable and moderate soil erosion acreages reduced by about 671.8 ha and 2,266.7 ha, respectively, and the high and severe ones increased; however, the severe soil erosion areas grew drastically. The differences between the two approaches come from consideration of the soil loss tolerance in assessing soil erosion severity. Thus, in order to assess SES for a region, comparing actual soil loss to soil loss tolerance provides SES indices that reflect the soil erosion problem, rather than only classifying actual soil loss. The findings are of enormous significance for environmental management, especially in addressing soil degradation.
soil erosion, severity, tolerance, changes, land cover, Pleiku
RESEARCH ON THE TECHNOLOGICAL PARAMETERS OF ORANGE RAKIA PRODUCTION
This research aims to identify the technological parameters involved in the production of rakia from Ha Giang oranges. The fermentation must was prepared by adding the disinfectant and antioxidant K2S2O5 at a concentration of 150 mg/L to ensure the sterility and stability of the orange juice for the subsequent fermentation stage. Using the native yeast strain Saccharomyces cerevisiae HB2 isolated from oranges, the factors influencing the fermentation process were determined, including fermentation temperature of 30oC, initial total soluble solids after adding sugar of 20°Bx, initial yeast cell density of 8.5 x 106 CFU/mL, and pH of 4.1. At the pilot scale of 5 liters, after fractional distillation and the removal of 3% ethanol from the head and 3% from the tail fractions, the resulting heart fraction had an alcohol concentration of 53% vol. After dilution to a final alcohol concentration of 35% vol by distilled water, the finished rakia had a characteristic orange aroma. The sensory score achieved was 18.16, which is in the ‘good’ category.
fermentation process, fermentation factor, orange juice, native yeast, rakia
EZMATH: DEVELOPING DIGITAL METHODS, A WEBSITE-BASED APPROACH TO SUPPORT TEACHING MATH WITH FIRST-GRADE VIETNAMESE CHILDREN WITH DYSCALCULIA
Dyscalculia is a term used to describe specific learning disabilities related to understanding numbers that affect the ability of children of all ages to understand, learn, and perform mathematics and number-based calculations. Estimates of the prevalence of dyscalculia range from 3% to 6% of the population, indicating the need for timely support solutions for teaching mathematics to students with mathematical difficulties. Therefore, the general objective of this study is to develop a digital tool in the form of an interactive learning website that provides many features and flexibility for children with dyscalculia. The solution was surveyed with 73 people working in and researching education for children with dyscalculia. The results show that the proposed solution is initially assessed to be appropriate and to offer an opportunity for developing a potential learning method to support children with dyscalculia.
dyscalculia, learning disabilities, support, inclusive education
THE PHYSICAL ORIGIN OF FIDELITY ENHANCEMENT IN THE TELEPORTATION PROTOCOL OF AN ARBITRARY TWO-QUBIT STATE UNDER AMPLITUDE-DAMPING NOISE ENVIRONMENT
A new analytical expression for the average quantum fidelity of a teleportation protocol for an arbitrary two-qubit state transmitted through an amplitude-damping noise environment has been established. This expression shows that the average fidelity depends not only on the purity measure and the bipartite entanglement measure of each parallel state forming the quantum channel, but also on the multipartite entanglement measure. This entanglement is generated between the qubits of each parallel state when they interact independently with the amplitude-damping environment. Based on this analytical relation, the physical mechanism for enhancing the teleportation protocol’s average quantum fidelity under two distinct amplitude-damping noise scenarios has been elucidated.
amplitude-damping noise, optimal averaged fidelity, entanglement measure, purity measure, multipartite entanglement
ASSESSMENT OF DROUGHT IN THE SOUTHERN SUB-REGION OF THE RED RIVER DELTA FOR AGRICULTURAL DEVELOPMENT
The southern sub-region of the Red River Delta possesses favorable natural conditions for agricultural development and plays an important role in the country’s agricultural output. Nevertheless, this region is highly vulnerable to natural disasters, particularly droughts, which pose significant challenges to agricultural productivity. This study applies a combination of statistical and spatial analysis methods to examine drought characteristics in the Southern Subregion of the Red River Delta. The research methodology included: (i) calculation of the K drought index, (ii) estimation of drought and extreme drought frequency, (iii) application of simple linear regression analysis, and (iv) interpolation using the Inverse Distance Weighting (IDW) method. Monthly precipitation and evapotranspiration data from 1991 to 2020 were utilized. The results show that droughts occurred in almost all months, except August and September, with the most severe events concentrated in December, January, and February. Although the region is relatively homogeneous, spatial variations are apparent. Ha Nam Province consistently recorded the lowest drought severity across all indicators, including drought frequency, extreme drought frequency, and the annual drought index. In contrast, a prominent elongated zone (or “trough”) with a high frequency of severe drought months is evident in the spatial distribution maps. Additionally, a drought tongue with increasing severity extends from Ha Nam in a northeast–southwest direction toward Van Ly (Nam Dinh). These findings provide critical insights for disaster risk reduction and serve as a scientific basis for agricultural planning and sustainable development in the region.
natural disasters, drought, K drought index, drought frequency, dry seasons, Red River Delta
THE FIRST EVALUATION OF TYROSINASE AND ELASTASE INHIBITORY ACTIVITIES OF GRAYANANE-TYPE DITERPENOIDS ISOLATED
From the methanol extract of the aerial parts of Rhododendron brachycarpum, five grayanane-type diterpenoids were isolated. These grayanane-type diterpenoids were elucidated by detailed analyses of NMR and MS data and identified as grayanoside B (1), rhodomoside A (2), piersformoside B (3), grayanotoxin III (4), and grayanotoxin I (5), based on comparison with previously reported spectral data. All compounds were evaluated for inhibitory activity against tyrosinase and elastase. The results revealed that the compounds 1-5 exhibited weak tyrosinase inhibitory activity, whereas compounds 1, 3, and 4 showed strong elastase inhibition, with inhibition rates of 71.78%, 71.11%, and 85.19%, respectively, at a concentration of 1mM. This study represents the first report of the anti-tyrosinase and anti-elastase activities of grayane-type diterpenoids isolated from R. brachycarpum.
Rhododendron brachycarpum, grayanane-type diterpenoids, tyrosinase, elastase enzymes
INVESTIGATION OF THE PROPERTIES AND ENHANCED PHOTOCATALYTIC ACTIVITY OF Bi₂WO₆/g-C₃N₄ COMPOSITE MATERIALS
Bi₂WO₆/g-C₃N₄ composite materials with varying g-C3N4 weight fractions (5%, 10%, 15% and 20%) were successfully synthesized using a combined microwave-hydrothermal method. The structural, morphological, and optical properties of the composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis absorption spectroscopy, and photoluminescence (PL) spectroscopy. Photocatalytic performance was evaluated by the degradation of Rhodamine B (RhB) under simulated sunlight, employing a cutoff filter to eliminate wavelengths below 400 nm. The incorporation of g-C3N4 into Bi₂WO₆ was found to significantly modify its morphology and enhance its optical absorption. All composite samples exhibited superior photocatalytic activity compared to pure Bi₂WO₆, with the 10 wt% g-C3N4 composite achieving the highest degradation rate, approximately seven times that of pristine Bi₂WO₆. This enhancement is primarily attributed to the formation of a Z-scheme heterojunction between Bi₂WO₆ and g-C3N4, which promotes efficient charge separation and suppresses electron-hole recombination via electron trap centers.
composite materials, photocatalytic activity, hydrothermal method, semiconductor, heterojunction
STUDY ON THE SYNTHESIS OF g-C₃N₄/LaFeCuO₃ HYBRID MATERIALS FOR THE DEGRADATION OF CIPROFLOXACIN
In this study, the photocatalysts g-C₃N₄, LaFeCuO₃, and the composite 10%g-C₃N₄/LaFeCuO₃ were prepared using a combination of sol-gel, pyrolysis, and ultrasonic-assisted synthesis methods.Their surface characteristics, including the crystal structure, elemental composition, morphology, optical absorption, and electron-hole recombination, were investigated through XRD, EDX, FE-SEM, UV-vis DRS, and photoluminescence (PL) spectroscopy. The role of ammonium persulfate agent (APS) in the degradation of ciprofloxacin (CIP) under light irradiation in the absence of photocatalysts was also examined. Results indicated that APS generated highly oxidative radicals (SO₄•⁻ and •OH), contributing significantly to the degradation of CIP. The optimal APS volume was 0.8 mL of 0.25M APS, achieving 82.35% CIP degradation after 180 minutes. In the presence of both APS and photocatalysts, LaFeCuO₃, g-C₃N₄, and 10%g-C₃N₄/LaFeCuO₃ materials achieved degradation efficiencies of 81.78%, 78.61%, and 96.3%, respectively, under the same experimental conditions, specifically, a CIP concentration of 20 ppm, photocatalyst loading of 1.5 g/L, and solution pH of 4.6. This improvement is attributed to the enhanced formation of free radicals facilitated by the presence of the photocatalysts.
g-C₃N₄/LaFeCuO₃ composite, persulfate activation, ciprofloxacin degradation
ON STABILIZATION OF DISCRETE-TIME 2-D SYSTEMS IN ROESSER MODEL
This paper focuses on the stabilization problem of discrete 2-D linear systems described by the Roesser model. A tractable stability condition in terms of linear matrix inequalities is first reformulated. Then, two controller design schemes are developed to formulate stabilization conditions via state-feedback controllers (SFCs) and event-triggered controllers (ETCs). Numerical examples with simulations are given to illustrate the effectiveness of the design conditions.
2-D systems, Roesser model, event-triggered control
A FIXED POINT THEOREM APPROACH TO GENERALIZED HALANAY INEQUALITIES
In this paper, we aim to reformulate a generalized Halanay inequality. A new approach using fixed point theorems for contraction mappings is presented. The obtained estimation can be utilized in various problems for nonlinear time-delay systems such as stability, dissipativity analysis and control design.
Halanay inequalities, exponential stability, fixed point theorem
EFFECTS OF MUTATIONS AT POSITION 161 ON FLUORESCENCE LOSS IN mCHERRY
mCherry is among the most widely used red fluorescent proteins in advanced imaging techniques. However, recent studies have revealed that mCherry and its variants are susceptible to spontaneous degradation, leading to a gradual loss of fluorescence over time. In this study, six mCherry variants were engineered, each featuring a single amino acid mutation at position 161, to investigate the role of this residue in mCherry fluorescence stability. Spectroscopic analysis demonstrated that these substitutions had variable effects on fluorescence retention. Notably, the substitution of Ile161 with Ser, Thr, and Gly resulted in a pronounced loss of fluorescence, whereas replacement with Ala, Val, and Cys produced milder effects. These findings underscore the critical role of residue 161 in chromophore stability in red fluorescent proteins, offering valuable suggestions for designing more stable mCherry variants. Furthermore, preliminary crystallization trials identified promising conditions for future optimization and structural studies, which may elucidate the molecular basis of substitution influence at position 161 on fluorescence stability in mCherry variants.
fluorescent proteins, mCherry, chromophore degradation, and crystal structures
PREPARATION AND CHARACTERIZATION OF CARRAGEENAN/ LOVASTATIN BIOMATERIALS
Carrageenan is a natural, gel-forming polysaccharide widely used in pharmaceutical applications due to its biocompatibility and mucoadhesive properties. This study aimed to develop carrageenan/lovastatin (CAR/Lov) composite biomaterials, evaluate their potential to enhance the solubility of lovastatin (Lov), and investigate their controlled drug release behavior. The prepared CAR/Lov samples were characterized by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) to examine the interaction between carrageenan and lovastatin and to assess the dispersion of the drug within the polymer matrix. The results indicated that the incorporation of lovastatin into the carrageenan matrix did not alter the chemical structure of the drug; however, it significantly improved its solubility and modulated its release profile. Among the tested samples, the CL15 formulation, with a Lov/CAR ratio of 1:15, demonstrated the most efficient drug release under simulated intestinal fluid (pH 7.4), achieving a release rate of 86.57%. In contrast, the release at pH 2.0 (simulating gastric conditions) was lower (33.57%). These findings highlight the potential of the CAR/Lov system for pH-responsive drug delivery, offering promising applications in the development of lipid-lowering drug formulations.
carrageenan, lovastatin, drug release, solubility, polymer gel system
STRUCTURE AND LUMINESCENCE OF Bi2Zr2O7:Eu3+,Tb3+ RED PHOSPHORS FOR WHITE LIGHT-EMITTING DIODES
In this study, Eu3+ and Tb3+ co-doped Bi2Zr2O7 (BZO) pyrochlore phosphors were successfully synthesized via a combustion method at 600°C. The crystal structure, elemental composition, morphology, luminescent characteristics, and energy transfer behavior were systematically investigated. Powder X-ray diffraction (XRD) analysis confirmed that all synthesized samples exhibited a pure single-phase pyrochlore structure, with Eu3+ and Tb3+ ions efficiently incorporated into the host lattice. Under blue light excitation at 466 nm, BZO:Eu3+,Tb3+ phosphors exhibited relatively strong red emission. Efficient energy transfer from Tb³⁺ to Eu³⁺ was observed, leading to a significant enhancement in red luminescence. Furthermore, the obtained phosphors demonstrated color purities approaching 90%. These results suggest that Tb3+ ions effectively act as sensitizers to Eu3+, and the new kinds of BZO:Eu3+,Tb3+ phosphors hold great potential for application in blue-excited white light-emitting diodes (WLEDs).
Bi\(_2\)Zr\(_2\)O\(_7\), energy transfer, Eu\(^3\)\(^+\) and Tb\(^3\)\(^+\), luminescence, red phosphor
CONSTITUENTS AND ANTIBACTERIAL ABILITY OF WATER BUG (Lethocerus indicus Lep.) ESSENTIAL OILS
The water bug, Lethocerus indicus Lep., is an aquatic insect commonly found in deep rice fields, lakes, ponds, and rivers in Vietnam. In this study, male specimens were collected from fields, ditches, ponds, and lakes in Dai Cuong commune, Ung Hoa district, Hanoi, Vietnam. The objective of this study is to determine the constituents and antibacterial properties of the essential oil extracted from L. indicus. Gas chromatography–mass spectrometry (GC-MS) analysis identified fifteen major components, primarily hydrocarbons and oxygenated hydrocarbons. In which, specifically, the essential oil comprised 12.41% monoterpenes, 25.12% sesquiterpenes, 21.98% alcohols, 1.79% aldehydes, and 36.63% esters. In particular, (E)-2-hexenol-acetate was the predominant component, accounting for 36.63%, and is believed to contribute to the characteristic aroma of the essential oil. The antibacterial activity of the essential oil was evaluated against six microorganisms: Staphylococcus aureus, Clostridium botulinum, Clostridium perfringens, Escherichia coli, Campylobacter jejuni, and Vibrio parahaemolyticus.
antibacterial ability, constituents, essential oil, water bug
DIVERSITY OF GROUND-ACTIVE SPIDER COMMUNITY ACROSS DIFFERENT TROPICAL FOREST HABITATS AND CLIMATE CONDITIONS IN NORTHERN VIETNAM
A year-long survey of ground-active spiders was conducted in three typical tropical forest areas of Northern Vietnam, each characterized by distinct climatic conditions: Cuc Phuong National Park (CPNP, tropical monsoon climate of the Red River Delta), Tam Dao National Park (TDNP, high-elevation tropical monsoon climate), and Cat Ba National Park (CBNP, maritime climate). Four types of habitats were selected in each region: natural forest and disturbed forest (both with multi-layered vegetation structures), and shrubland and acacia plantation (both with simple-layer vegetation structures). Spiders were sampled using pitfall traps. Cursorial hunters and ground-level web builders were the dominant guilds in all study areas. Spider diversity was compared across the study areas. Cluster analysis showed that the species composition in the maritime climate area (CBNP) was significantly different from that in the other areas. Spider diversity was also compared between habitats with multi-layer vegetation structures (multi-LVS) and those with simple-layer vegetation structures (simple-LVS). Both species composition and spider abundance were higher in habitats with multi-LVS than those with simple-LVS. The results of this study highlight the importance of preserving natural ecological processes to conserve biodiversity in multi-VLS habitats and to aid in the restoration of biodiversity in simple-LVS habitats. Keywords: ground-active spiders, regional climate, Northern Vietnam.
ground-active spiders, regional climate, Northern Vietnam
EXISTENCE AND LONG-TIME BEHAVIOR OF SOLUTIONS TO A CLASS OF DOUBLY NONLINEAR PARABOLIC EQUATIONS INVOLVING WEIGHTED p-LAPLACIAN OPERATORS
In this paper, we study the existence, uniqueness, and long-time behavior of global weak solutions to a class of doubly nonlinear degenerate parabolic equations involving weighted p-Laplacian operators in bounded domains with homogeneous Dirichlet boundary conditions. The global existence and uniqueness of weak solutions are established by combining compactness arguments with the theory of monotone operators. Furthermore, we analyze the asymptotic dynamics of the system and prove the existence of a compact global attractor by employing the theory of global attractors in bi-spaces.
doubly nonlinear parabolic equations, weighted p-Laplacian operators, global solution, global attractor, asymptotic a priori estimate method, compactness method, monotonicity method
GLOBAL DISSIPATIVITY OF POSITIVE NEURAL NETWORKS WITH TIME-VARYING DELAYS
In this paper, the problems of positivity and dissipativity are investigated for a model of neural networks with time-varying delays. A novel approach based on comparison techniques via differential and integral inequalities is presented and utilized to derive testable conditions which ensure the existence and the global dissipativity of a unique positive equilibrium point. The derived conditions are formulated in terms of linear programming with M-matrix, providing a computationally efficient framework for analysis. A numerical example with simulations is provided to illustrate the theoretical results and demonstrate their practical applicability.
positive neural networks, dissipativity, time-varying delay, M-matrix
PREVALENCE OF MALNUTRITION AMONG PRESCHOOL CHILDREN: A CROSS-SECTIONAL STUDY AT THUONG LY KINDERGARTEN, HAI PHONG CITY, AND NGUYEN DU KINDERGARTEN, HA TINH CITY
This study evaluated the nutritional status of 474 children aged 3-5 years from Thuong Ly Kindergarten in Hai Phong City (n = 274; 132 boys, 142 girls) and Nguyen Du Kindergarten in Ha Tinh City (n = 200; 109 boys, 91 girls) using WHO growth standards and Anthro software. The findings reveal significant disparities in stunting, wasting, underweight, and overnutrition between provinces and genders. Nguyen Du Kindergarten exhibited alarmingly high rates of stunting (24.5%) and underweight (13.0%), with boys more affected (25.7% and 18.3%, respectively). In contrast, Thuong Ly Kindergarten had much lower rates of stunting (4.0%) and underweight (2.9%), though boys had slightly higher rates of wasting (6.0%) compared to girls (2.1%). Overnutrition was prevalent in both regions, particularly among boys. In Thuong Ly Kindergarten, the prevalence of overweight and obesity was 7.6% and 3.8% in boys, compared to 4.2% and 1.4% in girls, respectively. Similarly, in Nguyen Du Kindergarten, boys exhibited higher overweight (7.3%) and obesity rates (4.6%) compared to girls (5.5% and 1.1%, respectively). Overall, Nguyen Du Kindergarten demonstrated a greater burden of overnutrition (9.5%) compared to Thuong Ly Kindergarten (8.2%), with statistical significance (P = 0.049). These results highlight the double burden of malnutrition across regions, with Ha Tinh facing higher rates of both undernutrition and overnutrition. Effective, context-specific interventions tailored to local socio-economic and demographic contexts are essential to address these challenges and promote optimal growth and health outcomes in preschool children.
Nutritional status, stunting, underweight, undernutrition, overnutrition, double burden of malnutrition
MAGNETIC FIELD AS A GROWTH ENHANCER: EVALUATING ITS POSITIVE IMPACTS ON AGRONOMIC CHARACTERISTICS OF MING ARALIA (Polyscias fruticosa)
This study investigated the effects of a magnetic field (MF) on agronomical and physiological characteristics of Ming aralia (Polyscias fruticosa) under hydroponic conditions. The evaluation focused on key root-related traits including root length, root hair density, fresh biomass, and dry biomass, as well as leaf-related traits such as leaf area, chlorophyll content, fresh and dry leaf biomass. Results revealed that MF exposure significantly enhanced root development, with treated plants showing a 21.5% increase in root length, a 48.2% improvement in root hair density, 24.8% and 36% higher fresh and dry root biomass, respectively, compared to the control group at day 50 of treatment. Similarly, leaf traits exhibited substantial improvements with MF treatment including a 20.2% increase in leaf area and a 20.4% enhancement in chlorophyll content by the end of the experiment. Fresh and dry leaf biomass of the treated group were also 25.2% and 28.1% higher, respectively, than those of the control group. These findings suggested that MF act as a biophysical stimulus, enhancing both morphological and physiological aspects of plant growth, likely by improving water and nutrient absorption, photosynthetic efficiency, and metabolic processes. The study highlights the potential of MF as a sustainable and effective tool to optimize plant development and productivity in controlled cultivation systems.
magnetic field, Ming Aralia, hydroponic, root, leaf
NEW DATA ON MICROPLASTICS IN THE SURFACE WATERS AND SEDIMENTS OF THE DAY RIVER ESTUARY, VIETNAM
The estuary is an intermediate zone that receives water from various sources before flowing into the sea. Over the past few decades, plastics from river estuaries have contributed significantly to marine pollution, raising serious concerns among scientists and authorities worldwide. However, data on plastic pollution in river estuarine regions remain scarce. In Vietnam, the Day River estuary is one of the largest river estuaries flowing into the sea. The results of the present study provide new data on the density, characteristics, and distribution of microplastics in both the surface water and sediments of the Day River estuary. This estuary is heavily polluted with microplastics, with an average density of 564 ± 551.6 microplastics/m³ in the water and 3,636.3 ± 750.6 microplastics/kg in the sediments. The most common microplastic sizes ranged from 300 to 1,000 μm. These microplastics exhibit a wide range of colors, which can be classified into eight distinct groups: black, blue, gray, green, purple, red, white, and yellow. Seven of these groups (black, blue, gray, green, purple, red, and white) were found in the sediments, while six groups (black, blue, purple, red, white, and yellow) were found in the surface waters. Among these, white and black microplastics were the most prevalent in both the surface waters and sediments of the study area. The study results contribute to a more comprehensive understanding of microplastic pollution in estuarine systems in Vietnam.
estuary, microplastics, pollution, sediment, water
IRIDOID GLUCOSIDES FROM Barleria lupulina LINDL.
Four iridoid glycosides, 6-O-trans-p-coumaroyl-8-O-acetylshanzhiside methyl ester (1), 6-O-p-methoxy-trans-cinnamoyl-8-O-acetylshanzhiside methyl ester (2), 6-O-cis-p-coumaroylshanzhiside methyl ester (3), and ipolamiide (4) have been purified and structurally elucidated from Barleria lupulina Lindl. (Acanthaceae) collected in Luang Namtha province, Laos. Compound 1, at a concentration of 128 μg/mL, inhibited the growth of the A549 cancer cell line by 31% and nitric oxide production in RAW 264.7 cells by 30%. This is the first report on the chemical constituents of Lao’s Barleria lupulina.
Barleria lupulina, iridoid glycoside, cytotoxicity, anti-inflammatory activity