Vietnam Journal of Science, Technology and Engineering

3-8

Authors: R.S. Omar*, S. Hashim, S.K. Ghoshal

This paper reports on the synthesis and characterisation of Dy2O3-doped magnesium borate (MB) glasses containing different modifiers, lithium, calcium, and sodium oxides. Glasses composed of (70-z)B2O3-20Li2O; CaO; Na2O-10MgO-zDy2O3 (where 0.05≤z≤0.7 mol%) were prepared using the melt-quenching method. X-ray diffraction (XRD) pattern of the as-quenched samples verified their amorphous character. Differential thermal analysis (DTA) confirmed excellent glass-forming ability and thermal stability in the range of 0.60-0.67 and 0.18-0.82, respectively. The energy dispersive X-ray (EDX) spectra verified the precise elemental traces in the studied glasses. Furthermore, MB glasses doped with 0.1 mol% of Dy2O3 and modified with lithium oxide were found to have the best soft tissue equivalence (Zeff≈8.13). In short, the proposed MB glass system doped with dysprosium ions (Dy3+) was established as effective for accurate radiation detection in emergency situations.

12-15

Authors: Van Kieu Nguyen, Thuc Huy Duong*

This study entails a continuation of the phytochemical study regarding the lichen Usnea baileyi collected in Lam Dong province. Eight compounds, 8'-O-methylprotocetraric acid (1), protocetraric acid (2), virensic acid (3), subvirensic acid (4), barbatic acid (5), diffractaic acid (6), 4-O-demethylbabartic acid (7), and atranorin (8), were isolated using various chromatographic methods. Their chemical structures were elucidated through spectroscopic analysis as well as through a comparison of their data with that in the literature.

25-32

Authors: Thanh-Truc Nguyen, Minh-Vy Huynh, Thanh-Hai Le, Thi-Thu-Hien Pham*

Breast cancer is a well-known health issue that has been a major focus for healthcare professionals for quite some time. Still, the most common noninvasive diagnostic tool - mammography - results in a high false positive rate along with risks of exposure to radiation. These disadvantages are magnified and become more severe when screenings are done repeatedly. To tackle this problem, we introduce a novel framework for uncomplicated diagnosis of breast cancer. Our method utilizes the analytical technique of Mueller matrix decomposition and Stokes vector polarimetry from a polarized light system consisting of a helium-neon laser (wavelength of 632.5 nm), a quarter-wave plate, polarizers, and a Stokes polarimeter. Thus, this technique introduces no radiation. We extracted nine optical parameters of a breast cancer cell line - BT474 - and determined the relationshipand separation power of these parameters to cancerous cells and healthy cells. Specifically, the samples were designed as a two-dimensional cellular model of malignant breast tumours that combined a range of four cell densities - 104, 105, 106, and 107 cells - per an area of 9 cm2.Nine optical parameters - orientation angle of linear birefringence (α), retardance or linear birefringence (β), optical rotation angle or circular birefringence (γ), orientation angle of linear dichroism (θd), linear dichroism (D), circular dichroism (R), degrees of linear depolarization (e1 and e2), and degree of circular depolarization (e3) - were extracted from a total of 40 samples using the polarized light system. The results revealed the positive correlations between three cell densities (104, 105, and 106) and the orientation angle of linear birefringence (R2 = 0.8038), linear birefringence (R2 = 0.8627), and linear dichroism (R2 = 0.9662). Meanwhile, both the orientation angle of linear dichroism and circular dichroism illustrated the negative correlation with that range of cell densities with R2 = 0.9983 and 0.9447, respectively. This proves that the optical parameters measured demonstrate significant association with the cells’ characteristics and thus, the proposed method could pave the way for an accessible diagnosis of breast cancer

40-44

Authors: Dao Thi Anh Phan*, Nga Kieu Thy Vo, Huy Minh Tran, Phan Thi Cam Bui

Changes in melanosis, microbiology, and fat oxidation in Pacific white shrimps (Litopenaeus vannamei) when treated with Houttuynia cordata extract (designated E-DC) were monitored during cold storage for seven days at 20C. Whole shrimps treated with E-DC solution (0.025%, w/v) revealed slow growth of total aerobic microorganisms, Enterobacteriaceae and Pseudomonas aeruginosa, throughout cold storage in comparison to the control sample treated by water (p<0.05). The changes in pH, grey value, and TBARS value (thiobarbituric acid reactive substances) of shrimp samples treated with 0.025% E-DC solution were lower than those of control samples (p<0.05) and not different significantly in comparison to the 1.25% (w/v) sodium metabisulfite (SMS) samples (p>0.05). These results suggested the potential of using natural compounds from vegetable extraction as a safe and effective alternative for commercial chemical-derived preservatives in shrimp storage.

52-56

Authors: Tien Sang Trieu*, Van Khoa Tran, Ha My Nguyen, Thi Thu Ha Nguyen, Quang Tung Le, Minh Ngoc Phung, Minh Quang Diep, Huong Ly Vu

Bacterial vaginosis (BV) is one of the most common vaginal infections in women of reproductive age. If not treated promptly, the disease can lead to serious complications affecting the fertility and long-term health of women. Research on BV requires effort from a variety of disciplines and its treatment can only be determined by coordinated actions in research and treatment. Currently, BV diagnostic methods are often based on culture techniques and Gram staining. However, molecular biology research is developing and has proved to more advantageous for identifying key pathogens. Combining both methods, we conducted a study to develop a diagnostic procedure using multiplex polymerase chain reaction (M-PCR) for simultaneous and accurate detection of the bacterial species that cause BV, incurring minimal costs and time for testing.

61-70

Authors: Hoang-Dung Tran*, Thanh-Tri Do, Tuan-Loc Le, Minh-Ly Tran Nguyen, Cong-Hoat Pham, Michael Melkonian

The green microalga, Haematococcus pluvialis, is currently cultivated for natural astaxanthin in suspended systems. Immobilised cultivation in a twin-layer (TL) porous substrate bioreactor is a potential revolution in microalgal biotechnology worldwide. For the first time in Vietnam, small-scale (0.05 m2) and large-scale (2 m2) biofilm-based photobioreactor systems arranged at an angle of 150 were successfully designed, assembled, and operated; the temperature, humidity, air, and light conditions for H. pluvialiscultivation were successfully controlled. Studies were conducted of both systems to determine theoptimal storage time of algae after harvest from suspension before inoculation into the TL system, carbon dioxide supply method, light intensity, and initial cell density. In the 0.05 m2 and 2 m2 systems, dry biomass productivity reached 12 g m-2 d-1 (3% astaxanthin content in the dry biomass) and 11.25 g m-2 d-1 (2.8% astaxanthin) after 10 days of cultivation. The 2 m2biofilm-based photobioreactor system provides many advantages in scaling up astaxanthin production from H. pluvialis.

77-80

Authors: Nguyen Van Thang, Le Ngoc Cau*, Makoto Kato, Satoshi Sugimoto

This paper presents a multi-criteria assessment approach for the prioritisation of low-carbon technologies for the waste sector in order to enable the implementation of Vietnam’s nationally determined contributions (NDCs) in terms of the Paris Agreement. A four-step approach is developed for assessing and prioritising low-carbon technologies for the waste sector using this approach. A set of five criteria and indicators are defined for multi-criteria assessment. Based on mitigation options defined in the NDCs, a shortlist of 26 technological options are defined. The multi-criteria assessment and prioritisation is conducted based on the shortlist. The assessment results in eight prioritised low-carbon technologies. Of the eight technologies prioritised, semi-aerobic landfill, which is a low cost and relatively simpler technology than the other technologies evaluated and can contribute to greenhouse gas emission reduction, is given the highest priority. The technical, financial, and social and environmental feasibility of each of the technologies evaluated is presented.

90-96

Authors: Ngoc Diep Nguyen1, Thi Le Hang Tran, Van Der Heiden Dion, Diep Anh Tuan Dinh, Pham Dang Tri Van*

The research was conducted to assess the feasibility of the installation of a rainwater harvesting system for households facing difficulties in using tap water and groundwater for domestic purposes in a coastal area of the Vietnamese Mekong delta - the case study of the Vinh Chau town, Soc Trang province. Direct household interviews and literature review were executed to comprehend the current state of domestic water consumption. According to the research results, Vinh Chau was among the towns seeing moderate rainfall in the delta (~ 1,776 mm/year), and rainwater was used frequently by the local people. However, local households did not employ proper harvesting techniques, hence the harvested rainwater did not meet the required quality for domestic use. Additionally, difficulties in using tap water, groundwater, and surface water were notable. The quality of tap water was not suitable for household consumption because of the presence of aluminum, and the price was high relative to the household’s income. Salinization of surface and groundwater, as well as degradation in quantity of ground water, made water of acceptable quality scarce. The research results also indicated that the use of rainwater harvested by a proper system demonstrated a higher cost efficiency than that of other water resources. Therefore, the installation of a rainwater harvesting system for water supply should be encouraged in order to provide a safe and efficient alternative water source for domestic use, and to contribute to the relief of domestic water-related issues and pressure on groundwater extraction in the study area