Vietnam Journal of Science, Technology and Engineering - C

A new design of a fall detection system integrating landmark identification and deep learning techniques

Tri Nhut Do* — 2026-03-15

This article introduces an innovative system that integrates landmark identification with deep learning to enhance fall detection accuracy and reliability. By utilising advanced computer vision techniques, such as MediaPipe for spatial recognition, the system effectively differentiates between routine movements and actual falls. The integration of landmarks with a deep learning prediction algorithm minimises false alarms, ensuring timely responses to genuine falls. Comprehensive experimentation underscores the system’s versatility across various scenarios, emphasising its potential to improve safety and independence for older adults. The training process demonstrates a steady increase in accuracy, stabilising by the 40th cycle, while error rates decline significantly during the initial cycles. Real-time experiments, involving both male and female participants aged 8 to 50, recorded a remarkable 95% detection rate of falls, showcasing the system’s effectiveness and promising future applications in elder care and smart health monitoring environments.

Bismuth doping enhances the thermoelectric power of ZnO thin films via structural distortion modulation

2026-03-15

The global energy conservation and pollution crisis is compelling the industry to seek methods for harvesting and conserving energy. Microfabrication methods of zinc oxide (ZnO) thin films also play a crucial role in affecting thermoelectric (TE) performance. This study investigates the TE properties of ZnO and Bi-doped ZnO thin films fabricated via radio-frequency (RF) magnetron sputtering. The incorporation of Bi into the ZnO lattice was systematically analysed to determine its impact on residual stress and electrical performance. Structural analysis confirms that Bi doping caused stress relaxation, reducing compressive stress from -1.00 to -0.36 GPa. Complementary insights from micro-Raman spectroscopy revealed Raman shifts, indicating an increase in defectrelated modes, specifically an intensified peak at 560 cm-1 associated with oxygen vacancy formation. The electrical conductivity of Bi-doped ZnO film reached 776.3 S/cm at 773 K, which was fourfold higher than that of pure ZnO. This enhancement in electrical conductivity played a key role in improving the power factor (PF) of TE materials. The power factor for the Bi-doped ZnO film was enhanced to 463.8 μW/mK2 at 773 K compared to pristine ZnO (314.8 μW/mK2) under the same conditions.

A broadband low-resolution spectrograph: SpectrumMate LR

Nguyen Duc Nguyen — 2026-03-15

spectrograph specifically tailored for use with small telescopes. SpectrumMate LR is designed to offer affordable and accessible spectroscopic capabilities for amateur astronomers, students, and educators, responding to the growing demand for versatile instrumentation in non-professional and educational settings. Employing a 300-grooves-per-millimetre diffraction grating together with 80 mm focal-length collimator and objective lenses, the system is optimised to analyse light across the entire visible spectrum. These optical parameters allow users to classify stars by spectral type, estimate stellar effective temperatures, and verify the transmission characteristics of astronomical filters. Laboratory and on-sky tests demonstrate SpectrumMate LR’s ability to record accurate,
well-calibrated spectral data, validating its efficacy when observing a variety of both celestial and terrestrial light sources. Because all components are commercially available and assembly procedures are straightforward, the instrument fills an important niche for cost-effective spectroscopy, empowering a broader community to engage in detailed observational astronomy. By lowering financial and technical barriers, SpectrumMate LR promotes hands-on learning, encourages citizen-science contributions, and provides a practical pathway for schools, small observatories, and enthusiast clubs to expand their research and outreach activities. As a result, SpectrumMate LR stands out as an exemplary tool for introductory spectroscopy courses worldwide today.

High-precision phase compensation in digital holographic microscopy via a Shack-Hartmann wavefront sensor in a telecentric configuration

Pham Duc Tuan, Vu Thanh Tung*, Phan Dinh Tuan — 2026-03-15

Digital holographic microscopy (DHM) enables the reconstruction of three-dimensional surface profiles with nanometre-scale axial resolution. However, measurement accuracy may be compromised by phase distortions arising from the spherical aberration of the microscope objective lens and by imperfections in other optical components. In this study, we propose a method that combines a Shack-Hartmann wavefront sensor (SH-WFS) with a reference - mirror arrangement, integrated within a telecentric optical system for phase compensation. This hybrid approach, which melds physical calibration with digital correction, simultaneously reduces both global and local system errors. Consequently, it achieves precise phase correction without complex manual adjustments and maintains high stability when switching between samples. Experiments were conducted using surface-roughness standards with arithmetic mean surface roughness values (Sa) of 20.3 and 11.6 nm, measured using a ZeGage™ Pro surface-scanning device. The results showed good agreement with the reference values provided by the ZeGage™ Pro, thereby confirming the effectiveness of the proposed method. Overall, this technique markedly improves measurement accuracy in DHM and underpins the development of highly automated measurement systems, offering promising applications in precision optics.

Estimation of radiation exposure to family members of I-131-treated patients in Tanzania using PHITS simulations

Penina George Mbago*, Innocent Jimmy Lugendo — 2026-03-15

Radiation therapy using Iodine-131 (I-131) is a widely employed treatment for thyroid disorders; however, it poses potential radiation risks to patient caregivers due to gamma emissions from treated patients. This study estimates the radiation doses received by family members of patients undergoing I-131 therapy in Tanzania, where cultural practices and living conditions complicate adherence to international safety guidelines. Using the Particle and Heavy Ion Transport Code System (PHITS), exposure scenarios during hospitalisation and post-discharge phases were modelled, accounting for proximity, activity levels, and caregiver-patient interactions. These models were used to quantify the radiation exposure to family members of patients treated with I-131 in Tanzania. Results indicate that family members assisting dependent patients during hospitalisation received doses of 1.53, 2.33, and 2.99 mSv for 3700, 5550, and 7400 MBq, respectively. These doses are below the 5 mSv per episode limit but exceeding the 1 mSv annual public dose limit recommended by the International Commission on Radiological Protection (ICRP). Post-hospitalisation, the doses decreased significantly, with the highest exposure caused by close-contact activities. Meanwhile, transportation scenarios showed the exposure to be less than 1 mSv/year for short durations. Nevertheless, strict adherence to maintaining a one-metre distance and minimising the duration of close contact is emphasised. These findings provide critical insights for maintaining public health while ensuring effective thyroid cancer treatment.

Investigating the preparation of oxime derivatives of azacrown ethers containing piperidine-4-one heterocycles under microwave irradiation

Tung H. To* — 2026-03-15

The use of multi-component reactions to simultaneously synthesise crown ethers and nitrogen-containing heterocycles is a synthetic approach that has attracted significant interest. With nitrogen heterocycles embedded in their structures, azacrown ethers can participate in various reactions to modify their structures for diverse applications. Herein, the preparation of azacrown ethers containing the piperidine heterocycle, based on a modified Petrenko-Kritschenko condition, is reported. The oximation of azacrown compounds was investigated under conventional reflux conditions and microwave irradiation at different temperatures. Physicochemical analyses, including 1HNMR, 13CNMR, and HRMS, were employed to elucidate the structures of the synthesised compounds. The experimental data demonstrated that microwave irradiation is an effective approach for oximation, reducing the reaction time to 20 minutes at 80°C and affording high yields (89-92%).

Chemical composition and antioxidant activity of the fruit essential oil of Xanthium strumarium L. cultivated in Hai Duong province, Vietnam

Dang-Minh-Chanh Nguyen — 2026-03-15

Xanthium strumarium L., a species in the Asteraceae family, is well known for its use in traditional medicine. This study aimed to identify the chemical composition and evaluate the antioxidant activity of the essential oil (EO) extracted from the fruits of X. strumarium collected in Hai Duong province, Vietnam. The EO was obtained via steam distillation and analysed using gas chromatography-mass spectrometry (GC-MS). The results revealed 15 major compounds accounting for 93.88% of the total oil content. The dominant constituents included m-tolualdehyde (12.11%), 1,2-benzenedimethanol (11.87%), p-tolualdehyde (9.94%), caryophyllene oxide (9.28%), and endo-borneol (8.91%). The major chemical groups were oxygenated sesquiterpenes (26.79%) and aromatic compounds (39.72%). The antioxidant activity of the EO was assessed using three methods: ferricyanide reducing power, 2,2-diphenyl-1-picrylhydrazyl (DPPH), and 2,2’-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. The EO demonstrated strong radical scavenging activity, comparable to ascorbic acid, with IC50 values of 22.8 μg/ml (DPPH) and 22.1 μg/ml (ABTS). These findings indicate that the fruit EO of X. strumarium possesses a rich chemical profile and significant antioxidant potential, suggesting promising applications in pharmaceuticals and functional foods.

Isolation and structural elucidation of xanthone derivatives from the pericarp of Garcinia mangostana L.

Nguyen Thi Hien — 2026-03-15

In Vietnam, Garcinia mangostana L. is commonly referred to as “Mang Cut” in Vietnamese, renowned not only as the “queen of fruits” but also for its various medicinal properties, particularly the shell of the mangosteen fruit. In traditional medicine, the shell of G. mangostana has long been employed to treat infections, diarrhoea, dysentery, and inflammation. Previous studies have shown that it possesses a variety of bioactive properties, including antibacterial,
antifungal, anti-allergic, anti-inflammatory, anti-tumour, and antiviral effects, attributed to xanthones. In our research, a phytochemical analysis of the ethyl acetate extract from the shell of G. mangostana led to the identification of several compounds, including garcinone C (1), garcinone D (2), bannaxanthone A (3), 8-deoxygartanin (4), and mangostanol (5). Their structures were elucidated through a comprehensive examination of ESIMS, 1D, and 2D NMR spectroscopic data. This study reports for the first time of bannaxanthone A (3) being isolated from this plant. These findings contribute to our understanding of G. mangostana and highlight its potential as a valuable herbal resource that may provide secondary compounds for the treatment of non-communicable diseases in the future.

Preparation of preservative product for Xuong Com Vang longan based on chitosan and the oligochitosan-iodine complex

Du Duy Bui*, Tho Phuoc Tran, Tuan Nghiem Anh Le, Giang Ngoc Doan — 2026-03-15

Longan (Dimocarpus longan Lour.) is a tropical fruit characterised by a short shelf life, which necessitates the application of postharvest preservation methods to reduce losses during distribution and consumption. A preservation mixture based on chitosan (CS) and the oligochitosan-iodine (OC-I2) complex was developed and evaluated for postharvest application in longan fruit storage. Ultraviolet-visible spectroscopy, X-ray diffraction, and Fouriertransform infrared spectroscopy confirmed that 2% H2O2 hydrolysis broke the β-1,4 glycosidic bond of CS without altering the OC structure. OC formed a complex with I2 through -NH2 and -OH groups. The chitosan-(oligochitosan-iodine) (CS-(OC-I2)) mixture at 9.00-22.5 g/l extended the shelf life of Xuong Com Vang longan fruits from 5 days (control) to 15-20 days at room temperature. Treated fruits showed reduced respiration rates, microbial density, weight loss, total soluble solids, browning index, and disease index, while maintaining greater fruit hardness and stabilising total soluble solids. These results indicate that the CS-(OC-I2) mixture is a promising preservative for longan and potentially other fruits, with the capacity to reduce postharvest losses during storage and distribution.

Survey of species composition in the Asteraceae family with value as animal feed in Chieng Ngan commune, Son La city, Son La province

Thi Lien Vu*, Di Xay Van Son Thong, Duc Toan Vu, Thi Thanh Ha Hoang — 2026-03-15

This study investigates the species composition and ethnobotanical value of Asteraceae family plants used as livestock feed in Chieng Ngan commune, Son La city, Son La province (prior to the administrative merge). Fieldwork was conducted from July 2023 to May 2024 using ethnobotanical methods, including participatory observation, semistructured interviews, and focus group discussions with 150 local informants from the Thai ethnic group. A total of 44 plant species used for livestock feed were recorded, representing 34 genera. Leaves were the most commonly utilised plant part. All 44 species were used to feed goats; 33 species were used for buffaloes and cattle, and 15 species for pigs. Nine Asteraceae species had a use value (UV) index of ≥0.90. Two species were also employed in traditional remedies for livestock. The life forms of Asteraceae species were classified as follows: SB=31.82% Hp+29.55% Th+15.91%
Ch+15.91% Hm+6.82% Na. The majority of species originated from tropical Asia (77.27%), with additional floristic elements identified. Asteraceae species were found across diverse habitats, including farming areas and grasslands (28 species), shrublands (24 species), limestone forests (19 species), secondary forests (17 species), and home gardens and fields (11 species). These findings highlight the significance of traditional knowledge in livestock feeding practices
and underscore the potential of Asteraceae plants as valuable feed resources in local agroecosystems.

Natural dishwashing liquid from fermented grapefruit peel solution

Hong Nguyen Pham, Si Hung Ho, Thi Huong Len Le, Thi Minh Xuan Nguyen* — 2026-03-15

The release of significant amounts of chemical detergents into the environment due to human activities raises concerns regarding environmental issues and human health. This study investigates the development of an eco-friendly dishwashing liquid derived from a fermented grapefruit peel solution, aiming to reduce organic waste and promote sustainable cleaning alternatives. The formulation involves fermenting a mixture of three parts grapefruit peel, one part brown sugar, and ten parts water in a sealed container for one month. The resulting solution effectively removes 89.2% of lard from plastic surfaces, eliminates 96.6% of bacteria, and produces foam comparable to that of commercial dishwashing liquids. Although no hydrolytic enzyme activity was detected using the well diffusion agar method with the respective substrates, the detergent effect of the fermentation broth likely arises from organic acids and biosurfactants, rather than from hydrolytic enzymes. The pH value of fermentation fluid decreased to 3 to 4.5 from the initial neutral pH. Consumer feedback highlights its potential as a safe, skin-friendly, and environmentally sustainable substitute for synthetic cleaners, contributing to broader environmental conservation efforts.

Factors associated with quality of life among non-small cell lung cancer patients treated with first-line targeted therapy in Vietnam: A study using the EORTC QLQ-C30 scale

Chinh Van Nguyen*, Linh Dieu Hoang, Huong Thi Thanh Tran, Kiet Tuan Pham Huy — 2026-03-15

A cross-sectional study was conducted using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30) scale to measure the quality of life (QoL) of 310 nonsmall cell lung cancer (NSCLC) patients with EGFR mutations receiving first-line targeted therapy at the Vietnam National Cancer Hospital from October 2022 to December 2023. A Tobit regression model was employed to identify factors associated with the QoL of NSCLC patients. The global health status of NSCLC patients was rated at 62.88 points, with financial difficulties scoring 51.08 points. Among the functional scales, physical functioning scored the highest at 85.72 points, followed by role functioning (79.57), cognitive functioning (78.66), social functioning
(71.72), and emotional functioning, which scored the lowest at 65.83 points. Regarding the symptom scales, insomnia scored the highest at 35.48 points, followed by fatigue (31.33), pain (25.11), diarrhoea (23.33), appetite loss (17.1), and dyspnoea, which scored the lowest at 4.62 points. Factors such as low income, residing in rural areas, and experiencing fatigue symptoms have a detrimental effect on the QoL of NSCLC patients. Improving fatigue symptoms, supporting income for low-income patients, and offering financial assistance, such as providing complimentary bus tickets and meals at the hospital, can alleviate financial strain and prolong the duration of support for NSCLC patients.

In silico identification of potential anti-monkeypox virus agents from Hypericum sampsonii

Phuoc Huynh — 2026-03-15

Monkeypox (Mpox), an emerging zoonotic infectious disease caused by the monkeypox virus (MPXV), has become an escalating global health threat. A wave of outbreaks began in 2022 and continued into 2024. Currently, no vaccines or FDA-approved specific treatments exist for MPXV, making the discovery of effective antiviral drugs crucial. The A48R protein, a thymidylate kinase (TK), is recognised as a promising target for MPXV drug development due to its distinctive active site structure compared with the human homolog. Hypericum sampsonii Hance, a traditional medicinal herb from the Guttiferae family, has demonstrated various biological activities, including antiviral properties. By leveraging the natural compounds derived from H. sampsonii, this study aimed to identify potential inhibitors of the MPXV-TK protein. Molecular docking and dynamics simulations revealed two compounds, LTS0126561 and LTS0259892, with strong affinity for the TK active site. In silico pharmacokinetic and toxicological assessments indicated that both compounds are suitable candidates for oral drug development. These identified compounds provide a basis for developing antiviral agents against MPXV and other Orthopoxviruses. However, further experimental validation of these lead compounds is required to confirm their predicted antiviral activities.

Microplastics in Vietnamese seafood and potential human exposure: A mini-review

Trung-Hau Nguyen — 2026-03-15

In this article, we review the occurrence and characteristics of microplastics (MPs) in marine organisms used as food (seafood) from Vietnam and assess the consumers’ health risks related to MPs-contaminated seafood. Twentyone marine species of fish, shrimp, and bivalves were reported to accumulate MPs in their tissues, with the highest abundance in fish (Decapterus maruadsi, 87 items/individual) and the lowest abundance in hard clam (Meretrix lyrata, 0.25 items/individual). The mean values of MPs abundance (items/g wet weight - ww) were 2.44, 0.73, and 0.85 in fish, shrimp, and bivalves, respectively. Fibre was the most common shape of MPs, but fragmented MPs were also observed in the tissues of marine organisms, and beads were only found in shrimp. Various MPs colours and more than ten MPs polymers were noted in the seafood. The estimated daily intake of microplastics (pEDI) was low (<1) based on the consumption of each seafood group, but it became high (>1) when pooled for all seafood. The total MPs that one person can ingest from seafood could be up to 22,876 items annually. Further quantitative studies of MPs in other kinds of food, spices, drinks, and air in Vietnam are necessary for a comprehensive assessment of human health risks associated with MPs exposure.

Evaluation of the alpha-glucosidase and alpha-amylase inhibitory potential of Costus speciosus (J. Koenig) Sm. aerial parts from Vietnam

Oanh Hoang Hua* — 2026-03-15

This study aimed to evaluate the inhibitory activity of α-glucosidase and α-amylase enzymes using aqueous and 40% ethanol extracts from the aerial parts of Costus speciosus harvested in Binh Phuoc province, tested in vitro. The enzyme inhibition activity was measured using α-amylase from porcine pancreas and α-glucosidase from Saccharomyces cerevisiae. Results showed that both the aqueous extract and the ethanol extract from the aerial parts of Costus speciosus showed significant α-glucosidase inhibition, with IC50 values of 18.51 and 77.25 μg/ml, respectively. Both extracts demonstrated lower IC50 values compared to the positive control, acarbose (IC50=122.20 μg/ml). For α-amylase inhibition, the aqueous extract and ethanol extract exhibited relatively low inhibition rates of 3.79 and 3.12%, respectively, compared to acarbose, which had an IC50 of 50 μg/ml for α-amylase inhibition. The study demonstrated that the aqueous and ethanol extracts of the Costus speciosus aerial parts exhibited in vitro inhibitory effects on α-glucosidase. However, the extracts showed poor inhibitory effects on α-amylase activity. These findings provide additional scientific evidence supporting its potential use in Vietnam for its hypoglycaemic properties.