Vietnam Journal of Science and Technology
Tạp chí của Bộ Khoa học và Công nghệ
Knowledge and self-care practices among patients with post-stroke hemiplegia at the Traditional Medicine Hospital of the Ministry of Public Security in 2025
Stroke is a clinical syndrome characterised by the sudden onset of focal neurological deficits, typically lasting more than 24 hours or leading to death within 24 hours. Currently, stroke is the leading cause of disability in adults, often resulting in significant sequelae; however, in-depth studies on the knowledge and self-care practices of patients with post-stroke hemiplegia in Vietnam remain limited. The study aimed to describe the knowledge and self-care practices of patients with post-stroke hemiplegia treated at the Traditional Medicine Hospital of the Ministry of Public Security in 2025. The results showed that patients with acute post-stroke hemiplegia had relatively good knowledge but poor self-care practices: Patients aged under 60 years were 4.09 times more likely to have correct knowledge about stroke than those aged over 60 years; patients with at least intermediate-level education or higher were 3.49 times more likely to have correct knowledge than those with upper secondary education or lower; patients with more than two stroke episodes were 4.60 times more likely to have incorrect self-care practices than those experiencing their first stroke; patients with insufficient knowledge had a 9.30-fold higher risk of incorrect self-care practices than those with adequate knowledge.
Nutritional status of students aged 11-14 years at six lower secondary schools in Nha Be district, Ho Chi Minh city in 2024
Objective: To evaluate the nutritional status of students aged 11-14 years at six lower secondary schools in Nha Be district, Ho Chi Minh city, in 2024 (before the administrative merger). Methods: A cross-sectional descriptive study was conducted among students aged 11-14 years. Anthropometric measurements were performed to evaluate the nutritional status of children based on the World Health Organisation (WHO) 2007 growth reference Z-scores for children and adolescents aged 10 to 19 years. Results: The prevalence of stunting was low at 1.84%, with severe stunting accounting for only 0.21%. Wasting was also rare, with an overall prevalence of 2.2%. In contrast, the prevalence of overweight and obesity was high, at 45.7 and 22.2%, respectively. The prevalence of overweight was similar in boys (41.6%) and girls (41.4%). However, the prevalence of obesity in boys (28.3%) was more than twice that in girls (13.5%) (p<0.05). The heightfor-age Z-score distribution demonstrated a rightward shift, although the peak remained lower than the WHO growth reference, particularly among male students. In contrast, the BMI-for-age Z-score distribution showed a pronounced rightward shift for both boys and girls, with values exceeding the WHO reference.
Optimisation of the bio-heavy oil production process from crude cashew nut shell liquid
The article focuses on optimising the process, enhancing the production efficiency of bio-heavy oil from crude cashew nut shell liquid using a system of equipment lines and organic acid catalysts in order to mitigate the emission of polluting gases to the environment. After determining the optimal catalyst-to-cashew oil solution ratio at the laboratory scale, the process was tested at the pilot scale. The product oil samples were characterised with the following parameters: calorific value determined according to ASTM D240-19 exceeding 9,000 cal/kg, impurity content per ASTM D473-22 below 0.01%, and ash content per ASTM D482-19 below 0.1%. However, the water content determined according to ASTM D6304-20 remained relatively high, at about 0.5%. The preliminary results show the potential to create bio-oil products with low impurity levels and a calorific value that meets current fuel-oil standards while potentially reducing sulfur oxides (SOx) emissions, which can be mixed at appropriate ratios for use in marine engines or in boilers at thermal power plants or industrial facilities.
Research on fabrication and properties of silica/phenolic and carbon/phenolic composites
The article presents the technology for manufacturing silica/phenolic (SP) and carbon/phenolic (CP) composite materials using compression molding. SP and CP composite materials are fabricated from fiber sheets (silica or carbon) on a phenolic resin matrix, where the phenolic resin matrix mixture is prepared in a furfural solvent in the presence of urotropin curing agent and AIBN initiator. The experimental results indicate that the studied materials exhibit low density, high stiffness, and high compressive strength. In particular, to evaluate heat resistance and erosion behaviour, thermogravimetric analysis (TGA) and combustion testing in a solid composite propellant motor were conducted. The mass loss of SP and CP composite materials at temperatures up to 800°C was 34.7 and 33.7%, respectively. When tested in a solid composite propellant motor using SP and CP materials as the nozzle throat insert, the erosion rates of SP and CP materials were 0.552 and 0.348 mm/s, respectively. Therefore, SP and CP composite materials exhibit high mechanical properties, good heat resistance, and erosion resistance under severe conditions.
Critical factors driving changes in construction projects: Evidence from Vietnam
Construction projects in Vietnam tend to encounter challenges related to changes during the construction phase. It is particularly challenging to identify the root cause of these changes. This study focuses on pinpointing and analysing critical factors leading to project changes, thereby reducing investment efficiency. Drawing from extensive literature and expert insights, the study has identified 38 primary factors causing project changes within the Vietnamese context. These factors were ranked according to their frequency (FI), severity (SI), and importance (IMP.I) indices. The results indicate that “Inconsistent rules and standards” emerged as the top-ranked external factor, while “Poor, erroneous or incomplete drawings” stood out as the highest-ranked internal factor. In general, these key internal and external factors are likely to occur and exert influence on construction projects. The study primarily contributes to enriching the theoretical foundation enabling managers to navigate changes during construction project implementation.
Development of an SMT-based SHM device and optimisation of vibration data transmission packets
Mount Technology (SMT) with the aim of improving system stability, compactness, and practical applicability. The device integrates an accelerometer sensor, a microcontroller, and a wireless communication module, enabling the acquisition and transmission of structural vibration data to a central station for structural monitoring and condition analysis. Considering the characteristics of vibration data and the constraints of low-power wireless communication, this study focuses on investigating and optimising the data packet structure, particularly the relationship between the number of measurement samples per packet, the number of transmitted packets, and transmission reliability. Experimental investigations were conducted under multiple sampling configurations to evaluate the impact of different data packetisation strategies on transmission performance and measurement data integrity. The results demonstrate that optimising the data packet structure significantly improves communication efficiency, reduces the risk of data loss, and meets the requirements for vibration monitoring in low-cost wireless SHM applications.
Isolation and selection of probiotic lactic acid bacteria from naturally fermented milk
This study aimed to isolate and evaluate probiotic lactic acid bacteria (LAB) strains from naturally fermented cow’s milk in Thai Nguyen. From five collected milk samples, five LAB strains were isolated and had their biological characteristics evaluated. All strains were capable of producing lactic acid under in vitro culture conditions. Among them, strain LAB-TNSC-29 showcased outstanding performance, with high lactic acid production (2.96 mg/100 ml), strong survival under low-pH conditions (3.23 log CFU/ml), and notable probiotic properties, including inhibition of pathogenic bacteria (Escherichia coli, Streptococcus gallinarum, and Staphylococcus aureus) and co-aggregation with E. coli at 48.35%. Analysis of the 16S rRNA gene sequence (1483 bp) revealed that this strain shared 99.39% sequence similarity with Lactobacillus acidophilus CIP 76.13T. Simultaneously, the phylogenetic tree revealed that strain LAB-TNSC-29 belongs to the genus of Lactobacillus and forms a monophyletic clade with Lactobacillus acidophilus CIP 76.13T. Therefore, LABTNSC-29 was identified as Lactobacillus acidophilus LAB-TNSC-29, holding strong potential for application in the production of probiotic formulations.
Analysis of genetic diversity among strawberry (Fragaria spp.) genotypes using RAPD molecular markers
The strawberry plant (Fragaria spp.) is a crop of high economic, nutritional, and medicinal value. Strawberry fruits are rich in vitamin C and antioxidants and are widely favoured in both local and international markets. The objective of this research was to determine the genetic diversity, relationships, and similarity coefficients among some strawberry cultivars using molecular markers of Random Amplified Polymorphic DNA (RAPD). 13 strawberry cultivar samples were collected from the GoodSeed tissue culture laboratory, Da Lat. DNA from leaf samples was extracted by DNeasy® Plant Pro (Qiagen, the Netherlands) and amplified with 10 RAPD markers (OPA16, OPA17, OPA20, OPG09, OPG11, OPG14, OPG18, OPK01, OPK02, OPK03). A dendrogram was constructed using NTSYSpc 2.1 software based on the Unweighted Pair Group Method with Arithmetic Mean (UPGMA). The results showed that 10 RAPD markers generated a total of 138 bands, of which 113 were polymorphic (81.79%). Primer OPA20 showed the highest polymorphism rate (100%), while OPK03 showed the lowest (64.23%). Genetic distance coefficients ranged from 0.11 to 0.47, with an average value of 0.29. Cluster analysis using UPGMA in NTSYSpc 2.1 software classified the cultivars into five distinct groups, reflecting the level of genetic diversity among them and providing a valuable basis for strawberry conservation and breeding programmes in the future.
Study on extracellular production of cordycepin and pentostatin by Cordyceps militaris under liquid surface fermentation
Cordyceps militaris is widely used in traditional medicine and as a food source. This fungus is capable of producing cordycepin and pentostatin, two bioactive compounds with antimicrobial, immunomodulatory, and cytotoxic activities against cancer cells. However, C. militaris is predominantly produced in the form of fruiting bodies for use as raw material. Recently, liquid-state surface fermentation has shown considerable potential for enhancing extracellular metabolite production in fungi. This study selected three C. militaris strains (HL8, BN25.2, and TN25.1) with high extracellular production of cordycepin and pentostatin. All three strains demonstrated stable extracellular production of cordycepin and pentostatin over five consecutive generations. Furthermore, the study identified suitable conditions for surface liquid-state fermentation of C. militaris, including the use of white LED light, a fermentation medium containing glucose as the carbon source and tryptone as the nitrogen source, an initial pH of 6, and a fermentation duration of 45 days. Under the suitable fermentation conditions, the average extracellular production of cordycepin by strains HL8, BN25.2, and TN25.1 reached 1220, 1415, and 1225 mg/l, respectively, while pentostatin production reached 45.6, 35.6, and 37.6 mg/l fermentation broth. The fermentation broth represents a promising source of raw material for the development of food and pharmaceutical products.
Study on vascular grafts characteristics supporting endothelial cell attachment under flow culture conditions
Endothelial cells form the innermost vascular layer, regulating blood coagulation and vascular physiology. Therefore, culturing and investigating the interaction of vascular grafts and endothelial cells provide insight into their potential applications in vascular transplantation. In this study, a bioreactor system was established to enable flow culture conditions. The flow rate was appropriately adjusted to maintain a closed and sterile culture environment. Under simulated flow conditions, endothelial cells were circulated using a bioreactor, and cell viability and attachment were evaluated on the graft surface. The vascular grafts showcased the ability to support endothelial cell attachment. Under flow culture conditions, the calcein staining images also addressed endothelial cell adhesion on vascular grafts after 72-hour culture. The vascular grafts were also demonstrated to support the adhesion of endothelial cells in in vitro culture. The flow culture system is suitable for cellular studies, thereby enabling prediction of potential endothelialisation effects following vascular graft implantation in vivo.
Identification of dioxin/furan compounds in sediments collected from the Dai Bai bronze casting village, Bac Ninh province
This study aims to determine several dioxin compounds in sediment samples collected from the wastewater channel and wastewater pond of the Dai Bai bronze casting village (Gia Binh commune, Bac Ninh province). Dioxin/furan compounds were extracted and analysed using high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS, Thermo, USA) combined with a DFS Thermo Trace 1310 high-resolution mass spectrometer (Thermo, USA). The total concentrations of dioxin/furan in sediment samples ranged from 8.340 to 98.600 ng/kg d.w (mean: 41.290 ng/kg d.w), with the toxic equivalent (TEQ) concentrations ranging from 0.319 to 6.990 ng TEQ/kg d.w (mean: 2.39 ng TEQ/kg d.w), which did not exceed the thresholds specified in the National Technical Regulation on Sediment Quality (QCVN 43:2017/BTNMT). However, dioxin/furan are persistent organic compounds capable of bioaccumulation in the environment, affecting the growth and development of flora and fauna in surrounding areas and posing potential risks to human health. Therefore, the relevant authorities need to issue appropriate sanctions and measures to monitor and manage the activities of bronze casting villages, thereby minimising emissions and the generation of dioxin/furan compounds that may adversely affect the ecological environment and human health.
Synthesis and characterisation of ZnAl-LDH by co-precipitation
Two-dimensional layered double hydroxides (LDHs) have attracted considerable interest due to their potential applications in energy storage, catalysis, sensing, electronics, and environmental treatment. In this study, zincaluminum layered double hydroxides (ZnAl-LDHs) were synthesised using a simple co-precipitation method involving zinc and aluminum precursors. The effects of the Zn²⁺/Al³⁺ molar ratio and the pH value of the reaction solution on the structural and morphological characteristics of ZnAl-LDH were investigated. Fourier transform infrared (FTIR) spectroscopy confirmed the presence of characteristic hydroxyl and carbonate groups in the layered structure. X-ray diffraction (XRD) analysis revealed characteristic diffraction peaks of the ZnAl-LDH phase with high crystallinity. Scanning electron microscopy (SEM) demonstrated flake-like layered structures and threedimensional coral-like clustered morphologies. Energy-dispersive X-ray spectroscopy (EDX) further verified the presence of Zn and Al with an appropriate molar ratio, consistent with the theoretical model of ZnAl-LDH. The results provide a basis for the design and development of LDH materials with diverse compositions and structures to meet increasing industrial and environmental demands.
Thi Hong Cao, Thi Thom Nguyen*, Thi Nam Pham, Dai Lam Tran
Enhancing the accuracy of conveyor belt weighing systems using Median and Exponential Moving Average filters in load cell signal processing
The belt weighing system plays a vital role in industrial production lines such as mineral mining, thermal power plants, cement manufacturing, and bulk material processing. Its main function is to measure the mass of material being continuously conveyed, enabling businesses to monitor throughput, optimise production processes, and maintain the quality of the output products. This article presents a signal filtering method that combines the Median filter and the Exponential Moving Average (EMA) filter to improve the stability and accuracy of load cell signals in conveyor belt weighing systems. The system is implemented on an STM32H743ZIT microcontroller platform, featuring an integrated 24-bit ADC and the FreeRTOS real-time operating system. The signal is processed using a seven-point Median filter followed by an EMA filter with a smoothing factor α=0.3, prior to calibration and flow calculation. Experimental results from a real-world industrial conveyor line demonstrate that the proposed method reduces impulse noise by over 68%, decreases signal standard deviation by more than 62%, maintains latency at approximately 104 ms, and keeps mass measurement error below ±1.2%. These results verify the feasibility and high efficiency of the proposed approach in harsh industrial environments with significant noise interference.
Structure, aboveground biomass and biodiversity of selected natural forest states in the ecological restoration zone of the Hon Ba Natural Reserve
The ecological restoration zone of Hon Ba Nature Reserve covers approximately 9,553.5 hectares and comprises a variety of characteristic evergreen broadleaf forest states. A field survey was conducted using temporary standard plots (1,000 m2, 33.3x30.0 m) established in typical forest states of the study area to determine several forest characteristics, including forest structure, biomass, and biodiversity. The results indicated that the distribution of trees by diameter class (n/D1.3) and height class (n/Hvn) was similar among forest states, exhibiting a concentration in small diameter and height classes. Standing volume ranged from 36.7 to 221.7 m³/ha, while biomass ranged from 30.16 to 247.54 tonnes/ha. The total number of forest tree species observed in the forest states ranged from 12 to 36, of which 6 to 10 species had high ecological significance. The study area exhibited a notable decline in stand density, volume, species richness, and biodiversity index in comparison to general regional levels. This suggests that the study area has confronted considerable challenges pertaining to forest restoration and development, particularly with regard to the recovery rates of forest states distributed within the ecological restoration zone.
Hoàng Thanh Sơn, Lương Văn Dũng, Nguyễn Văn Tuấn
Sustainability evaluation of an integrated ecological system for dragon fruit cultivation using emergy accounting
This study aims to evaluate the sustainability of an integrated ecological system for dragon fruit cultivation by farming households. A closed ecological system based on material and energy circulation was proposed and implemented for dragon fruit farming households, utilising waste from dragon fruit biomass combined with livestock waste to generate valuable new products. In addition, emergy accounting analysis was applied for sustainability evaluation of an integrated ecological system. The results show that the emergy yield ratio (EYR) of the system is 0.99, indicating that no free environmental resource can be obtained for each unit of input invested in the integrated system. The emergy loading ratio (ELR) of the system is 0.35, which indicates a relatively low environmental loading, with renewable inputs outweighing non-renewable ones. Furthermore, the environmental sustainability index (EmSI) of the integrated system is 2.8, which is higher than that of conventional agricultural systems.
Thi Thien Kim Ho, Thanh Hung Nguyen, Thanh Hai Le, Thi Hieu Tran, Thi Phuong Thao Nguyen, Trung Kien Tran*
Development of an in vitro regeneration system for genetic transformation in peanut variety L27 (Arachis hypogaea L.)
Arachis hypogaea L. has high nutritional value for human health; however, its proteins are highly allergenic, and the levels of essential sulfur-containing amino acids are relatively low. Moreover, peanut yield and nutritional value are adversely affected by abiotic stresses, including drought, extreme temperatures, salinity, flooding, and elevated CO2 concentrations. This study aimed to develop an efficient regeneration system for Agrobacterium-mediated genetic transformation to enhance stress tolerance and improve seed quality in peanuts. The results indicated that the most effective seed sterilisation was achieved using 0.1% mercury(II) chloride (HgCl2) for a total of 9 minutes (5 minutes for the first treatment and 4 minutes for the second treatment). The optimal shoot tip regeneration was observed at 1.5 mg/l benzylaminopurine (BAP), while cotyledon axil explants showed the best response at 2.0 mg/l BAP. Multiple shoot induction from cotyledon axil explants was most successful with a combination of 2.0 mg/l BAP and 0.7 mg/l α-naphthaleneacetic acid (α-NAA), producing an average of 4.43 shoots per explant. In contrast, apical shoot tips did not induce multiple shoot formation. The highest rooting efficiency was achieved with 0.7 mg/l α-NAA, resulting in an average of 8.32 roots per shoot. Kanamycin selection was effective at 75 mg/l during shoot regeneration and 50 mg/l during rooting.
Effect of transplanting density and chemical fertiliser application rate on the growth and yield of Huong Thanh 10 rice variety in Thanh Hoa province
This study aimed to determine appropriate transplanting densities and chemical fertiliser rates for the Huong Thanh 10 rice variety in Thanh Hoa province. The experiment was conducted during the Spring and Summer crops of 2024 using a split-plot design with three replications. The main plot factor was the fertiliser rate per hectare with N:P2O5:K2O ratios. In the Spring crop, the treatments were P1: 80:70:60 kg/ha, P2: 90:80:70 kg/ha, P3: 100:90:80 kg/ha, and P4:110:100:90 kg/ha. In the Summer crop, the treatments were P1: 70:60:50 kg/ha, P2: 80:70:60 kg/ha, P3: 90:80:70 kg/ha, and P4: 100:90:80 kg/ha. The subplot factor was transplanting density: M1: 30 hills/m², M2: 40 hills/m², and M3: 50 hills/m². The results showed that growth duration, maximum number of tillers, number of filled grains per panicle, and 1,000-grain weight were the highest at a transplanting density of 30 hills/m² with fertiliser treatment P3. The highest actual yield was recorded in the M2P3 treatment, reaching 6.8 tonnes/ha in the Spring crop and 4.6 tonnes/ha in the Summer crop. This corresponded to a transplanting density of 40 hills/m² and fertiliser rates of 100 kg N + 90 kg P2O5 + 80 kg K2O per hectare in the Spring crop, and 90 kg N + 80 kg P2O5 + 70 kg K2O per hectare in the Summer crop.
Adherence to HIV pre-exposure prophylaxis among men who have sex with men in Thanh Hoa province
Objectives: To describe adherence to HIV pre-exposure prophylaxis among men who have sex with men (MSM) in Thanh Hoa province in 2024. Methods: A cross-sectional study was conducted among 374 men aged 16 years and older who had sex with men and were using HIV pre-exposure prophylaxis (PrEP) services from April 2024 to June 2024. Results showed that 21.2% of MSM had used PrEP for 12 months or longer. Among them, 87.2% of MSM used PrEP in combination with condom use during sexual intercourse; 2.9% of MSM reported forgetting to take their PrEP medication in the past month. Among those who missed doses, 81.8% forgot to take their medication for 1- 7 days, and 18.2% for more than 7 days. Common reminder methods included setting alarms (90.9%) and scheduling medication times (72.7%). When experiencing side effects, 91.4% of MSM reported them to PrEP clinic staff. Conclusions: Adherence-related practices still require strengthening in some areas. Therefore, communication interventions should be strengthened to ensure sustainable PrEP use among MSM.
Assess the effectiveness of the “Neonatal resuscitation” training programme at hospitals in Ha Nam province
This study aimed to evaluate the effectiveness of the “Neonatal resuscitation” training programme at hospitals in Ha Nam province (before the administrative merger), focusing on the improvement of healthcare professionals’ knowledge and practical skills and the reduction in neonatal morbidity and mortality rates. A before-and-after in terventional study was conducted on 317 neonates (≤30 days old) in critical condition who were treated at hospitals in Ha Nam province from June 2023 to June 2024. Additionally, 116 healthcare professionals (including doctors, nurses, and midwives) participated in the training programme and were assessed after training during the same period. After the training programme, the rates of neonatal deterioration and mortality decreased (from 2.3 to 0.9% and from 0.7 to 0.6%, respectively), along with a marked reduction in referrals to the National Children’s Hospital (from 16.9 to 8.2%). Although theoretical knowledge among healthcare professionals improved, further enhancement of practical skills is needed. The “Neonatal resuscitation” training programme proved effective in improving the quality of neonatal care in Ha Nam province. However, continued training programmes and regular supervision are essential to ensure sustainable improvement in healthcare professionals’ practical skills.
Thi Quynh Nga Nguyen, Thi Nga Phan, Thi Hoa Quach, Lan Huong Chu, Thi Huyen Trang Vuong, Thi Hong Le, Huy Phu Nguyen
Evaluation of cervical lymph node metastasis in tonsil cancer at Cho Ray Hospital (2019-2024)
Objective: To evaluate the rate of cervical lymph node metastasis in tonsil cancer at Cho Ray Hospital from 2019 to 2024. Subjects and methods: Patients who were diagnosed with tonsil cancer through pathological examination and treated at the Department of Otorhinolaryngology, Cho Ray Hospital, from June 2019 to June 2024 were included in the study. Results and discussion: The majority of patients were aged between 40 and 60 years (70.8%). The maleto-female ratio was 3.8/1. The most common functional symptom was pain at the tumour site (66.7%), followed by dysphagia and cervical lymphadenopathy, which accounted for 50.0 and 33.3%, respectively. Tumours were located on the right side in 54.2% of cases and on the left side in the remaining patients. The disease was associated with risk factors including alcohol consumption, smoking, and betel chewing. Pathological results indicated that squamous cell carcinoma of the tonsil was typically localised to one side. Regarding lymph node metastasis, our study showed that 70.8% of patients presented with cervical lymph node metastasis, whereas 29.2% had no metastatic lymph nodes. Conclusion: Tumours were predominantly staged as T1 and T2 (87.5%). The rate of lymph node metastasis was 40% in T1, 75% in T2, and 100% in T3, suggesting a greater incidence of metastasis in advanced stages.
Electrochemical detection of chloramphenicol residues in milk samples using a working electrode modified with Fe3O4 superparamagnetic nanoparticles
Antibiotic residues in food, particularly in agricultural and aquaculture products, have become a serious issue requiring effective solutions in Vietnam. This problem is largely attributed to the excessive use of antibiotics in livestock farming, which not only poses risks to public health but also negatively affects the reputation and commercial value of exported products. In this context, electrochemical sensors have been recognised as a potential technological solution due to their advantages, including simple fabrication, low analytical cost, quick response, and high sensitivity and selectivity. In this study, Fe3O4 superparamagnetic nanoparticles, characterised by high electron conductivity, low toxicity, good biocompatibility, and strong adsorption capacity for organic compounds such as antibiotics, were used to modify the working electrode of commercial C110 electrochemical sensors (Metrohm, Switzerland) in order to enhance the electrochemical signal and improve sensor sensitivity. The results showed that the electrochemical sensor detected chloramphenicol (CAP) in phosphate buffer solution (PBS) with a low limit of detection (LOD) of 0.06 μM, a relative standard deviation (RSD) of below 5%, and a recovery rate of 94.77%. The sensor was applied for the rapid determination of CAP residues in milk samples at a concentration of 1 μM, achieving recovery rates of 95-109% and a relative standard deviation of 2.14%. These promising findings serve as a foundation for further research to develop label-free, portable electrochemical sensors for on-site analysis, contributing to food safety monitoring and the protection of consumer health in Vietnam.
Van Dinh Tran, Van Khanh Nguyen, Truong An Nguyen,Doan Phuc Le, Thi Minh Hong Nguyen*
Preparation of a hydroxyapatite-supported titanium oxide via the hydrothermal method for photocatalytic degradation of textile dyes
In this study, the HAP-based adsorbent and photocatalytic materials, including hydroxyapatite synthesised from Ca(NO3)2 and NH4H2PO4 precursors and titanium oxide-immobilised HAP (TiO2/HAP) derived from TiCl3, were produced using a hydrothermal method. The obtained materials were characterised by several techniques: X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX), and surface charge determination via zeta potential measurements. The adsorption and photocatalytic performances of the materials were evaluated through degradation experiments of methylene blue (MB), alizarin yellow G (AYG), and indigo dye (XHT - textile dye collected from household-scale traditional weaving villages), with dye concentrations before and after treatment determined by UV-Vis spectrophotometry. Characterisation results indicated that titanium oxide was successfully immobilised and uniformly dispersed within the HAP matrix, and the particles exhibited good stability in the dispersion medium. The TiO2/HAP composite exhibited photocatalytic oxidation and degradation efficiencies exceeding 90% for all tested dyes after three hours of UV irradiation. This highlights the potential application of TiO2/HAP composite materials in the photocatalytic treatment of dye pollutants.
Hoang Minh Luong, Thi Hang Pham, Xuan Hoan Nguyen*
Synthesis and characterisation of PbO2-SnO2 composite on a stainless steel substrate
A PbO2-SnO2 composite was successfully synthesised by cyclic voltammetry (CV) on stainless steel (SS) substrate in an electrolyte containing 0.5 M Pb(NO3)2, 0.1 M HNO3, 0.05 M Cu(NO3)2, 0.1 M C2H6O2, and SnO2 with concentrations ranging from 500 to 2500 mg/l. This composite exhibited the best electrochemical properties when the SnO2 concentration in the solution was 1500 mg/l. The surface morphology and elemental composition of the composite were determined by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX). The electrochemical properties of the SS/PbO2-SnO2 electrode were investigated in 0.5 M H2SO4 using CV and potentiodynamic polarisation I-E methods. The obtained SS/PbO2-SnO2 composite electrode was used as an anode for the electrochemical removal of methyl orange (MO) from aqueous solution under suitable conditions with different treatment times. The removal efficiency of MO was high, exceeding 90% after 30 minutes of treatment. The kinetics of MO removal followed a first-order reaction model with a linearity of R2=0.9736.
Research on the in vitro propagation of Dendrobium moschatum Buch.-Ham. ex Sw.
To determine the optimal culture conditions for the in vitro propagation of Dendrobium moschatum Buch.-Ham. ex Sw., a rare orchid species facing a high risk of extinction, the study evaluated the effects of plant growth regulators (GA3, BAP, TDZ, NAA) and activated charcoal on key developmental stages, including seed germination, shoot regeneration, and root induction prior to plantlet formation. All experiments were conducted under laboratory conditions. The results showed that Murashige & Skoog (MS) medium, supplemented with 3% sucrose and 5 g/l agar and adjusted to pH 5.8±0.1, produced the highest germination rate (89.67%). During the shoot regeneration stage, 3.0 mg/l BAP significantly promoted shoot formation, producing 4.25 shoots per explant. During the rooting stage, medium supplemented with 0.2 mg/l NAA and 2.0 g/l activated charcoal resulted in the highest rooting efficiency. The findings contribute to the optimisation of the in vitro propagation protocol for Dendrobium moschatum and support the conservation and development of this valuable orchid genetic resource.
Phuong Thu Pham2*, Thi Tuyet Nhung Nguyen, Thi Thu Hien Phan, Thi Thuong Vu
Quality control standards for stem cell culture and stem cell banking
Establishing quality control standards in stem cell culture facilities and stem cell banks plays a pivotal role in ensuring the safety, efficacy, and clinical applicability of stem cell-based therapies. This regulatory framework requires strict criteria, including cell origin, biological characteristics, purity, viability, differentiation potential, genomic stability, periodic quality assessments, and complete documentation for traceability. Stem cell culture facilities and stem cell banks must comply with Good Manufacturing Practice (GMP) and Good Tissue Practice (GTP) to minimise contamination risks and maintain optimal culture conditions. Additionally, biomedical ethics, donor screening procedures, and compliance with international regulatory standards (FDA, EMA) are essential for guaranteeing the quality of stem cell products. This article presents detailed quality control standards for stem cell culture and banking. Particular emphasis is placed on basic standards concerning facilities, cell authentication, cell counting and viability assessment, and microbiological safety evaluation.
Phuoc Vinh Nguyen, Thi Kim Ly Bui, Van Kien Vu
Effect of glycidyl methacrylate compatibiliser and montmorillonite reinforcement on the properties and morphology of PBAT/PLA blends
A polymer blend based on polybutylene adipate terephthalate and polylactic acid (PBAT/PLA) with enhanced mechanical properties was successfully fabricated by melt mixing in a twin-screw extruder using glycidyl methacrylate (GMA) as a compatibiliser and montmorillonite clay (MMT) as a reinforcement. The properties of the blend were characterised by a series of methods including ATR-FTIR spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and mechanical testing. The results showed that the PBAT/PLA blend with a weight ratio of 40/60 exhibited optimal mechanical properties. In addition, the GMA-based compatibiliser increased the compatibility of the PBAT/PLA blend through reactions between epoxy groups and the terminal COOH and OH groups of the polymer chains. The study also confirmed that the combined use of a GMA-based compatibiliser and clay improved the mechanical strength, thermal stability and structural stability of the materials. The PBAT/PLA/compatibiliser/clay blend with a mass ratio of 40/60/10/20 exhibited a tensile strength of 30.06 MPa, an elongation at break of 70.38%, and a tensile modulus of 1568 MPa. These results indicate significant potential for the production of environmentally friendly packaging and disposable food containers.
Thi Nguyet Anh Tuong*, Huong Thi Hoang, Hoang Linh Doan, Tien Dat Nguyen, Thi Thao Nghiem, Ngoc Diep Nguyen, Thao Yen Linh Dang, Van Huong Doan, Xuan Quang Chu
Effects of drying method on chemical composition and physicochemical properties of Spirulina platensis
The drying method affects the physical state, structure and chemical composition of Spirulina platensis, particularly its colour-related compounds exhibiting antioxidant activity. This study provides guidance on using drying methods to enhance the value chain of Spirulina. The results of the study demonstrated that the chemical composition and other physicochemical properties of Spirulina platensis were the least affected by freeze-drying at 30oC, followed by heat pump drying at 50oC, whereas hot-air drying at 50oC had the greatest impact. Within the scope of the study, hot-air-dried Spirulina platensis exhibited the highest peroxide value and the fastest sedimentation rate in water. Among the used methods in this study, freeze-drying is the most suitable method to retain secondary metabolites such as phycocyanin in Spirulina platensis. However, heat pump drying can be effectively used as an alternative to freeze-drying to reduce production costs while maintaining the application value of Spirulina platensis, provided that antioxidant activity is not the primary concern compared with colour or nutritional value.
Determination of methanol in gasoline using liquid-liquid extraction and gas chromatography-flame ionisation detector (GC-FID)
The concentration of methanol in gasoline was determined using liquid-liquid extraction and gas chromatographyflame ionisation detector (GC-FID). Methanol was transferred into the aqueous phase by liquid-liquid extraction before being separated on a Restek Rtx-Wax column and detected using a flame ionisation detector (FID). Gas chromatographic conditions, including column temperature programme, split ratio, and carrier gas flow rate, were investigated and selected to meet the requirement for methanol analysis. The methanol concentration in gasoline showed good linearity over the range of 3.96-7920 mg/l, with R²>0.99. The method detection limit (MDL) and method quantification limit (MQL) were 1.49 and 4.96 mg/l, respectively. The method precision, expressed as RSD, ranged from 1,49 to 4,96. The extraction recovery of methanol in gasoline ranged from 92.4 to 98.6%. The results indicated that the developed method meets accuracy requirements and is suitable for the determination of methanol in gasoline samples.
Thi Huong Thao Hoang*, Thi Phuong Thao Mai, Ngoc Hai Khuat
Chế tạo và nghiên cứu tính chất quang của vật liệu MgGa2O4 pha tạp Cr3+
Far-red light-emitting diodes (LEDs) have attracted increasing attention due to their positive effects on plant growth. When plants are exposed to far-red light, phytochrome far-red (PFR) absorbs the radiation and is converted into phytochrome red (PR), thereby stimulating plant growth. In this study, a far-red-emitting MgGa2O4:Cr³⁺ phosphor was synthesised using a thermal diffusion method. X-ray diffraction (XRD) analysis confirmed that at a calcination temperature of 1400°C, the material forms a single phase with good crystalline quality. Field-emission scanning electron microscopy (FESEM) images showed that the material possesses relatively large grains, ranging from 1 to 3 μm in size. Photoluminescence excitation (PLE) spectra revealed strong visible-light absorption, with two prominent peaks at approximately 415 and 574 nm. When excited at 415 nm, the material exhibited intense red emission, peaking at 707 nm, corresponding to the ²E→4A2 transition. Furthermore, an LED experiment using this material in combination with a 430 nm LED chip was successfully conducted. These findings indicate that Cr³⁺-doped MgGa2O4 is a promising candidate for far-red light-emitting LEDs in agricultural lighting applications.
Anh Tuyet Nguyen, Hong Dang Vu, Viet Hung Tran, Thi Hao Dung Duong, Mai Chi Ngo, Van Quang Nguyen*
Innovation of the pocket attachment sewing process through research, design, and fabrication of a semi-automatic jig-fixture-template system for the Juki AMS-221EN/2516 programmable sewing machine
Pocket facing attachment in veston/jacket production is commonly performed on single-needle sewing machines. During sewing, operators must manually fold and continuously hold the facing edge to ensure stitch-line accuracy, while retrieving and arranging semi-finished parts after sewing. These manual operations increase the sewing cycle time and lead to quality variation. This study proposes an innovative pocket-facing sewing process on the Juki AMS-221EN/2516 programmable sewing machine using a semi-automatic jig-fixture-template system. The system integrates a pneumatic edge-folding and clamping mechanism controlled by a PLC using a cycle-state control scheme synchronised with the sewing motion, and automatically retrieves and arranges semi-finished parts after sewing; consequently, interlocks are clearly managed and operational reliability is improved under repeated operation. Production trials were conducted 30 times over 30 days (4 hours per trial; n=30 for each method). Results show that the mean cycle time decreased from 11.9±0.7 s/part to 8.3±0.5 s/part (-30.3%; Welch’s t-test, p<0.001), corresponding to an output increase from 1212 to 1739 parts per 4 hours (+43.5%). The topstitch line became more stable and less dependent on operator skill due to the elimination of manual edge holding.
Xuan Hiep Hoang, Sy An Nguyen*, Van Lam Nguyen, Xuan Chu Do, Thi Hoan Duong