Vietnam Journal of Science, Technology and Engineering

8-10

Authors: Thi Thuy Dung Phung, Thu Thuy Truong, Thanh Luan Nguyen, Tran Ha Nguyen

Donor-acceptor compounds have been receiving increased attention lately, especially in opto-electronic applications. In this work, a novel compound named triazine-furan, comprised of a triazine acceptor moiety and a furan donor side group, was designed and synthesised for the first time. The influences of temperature and the feeding proportion of cyanuric chloride to furfurylamine were investigated to optimise the reaction yield and purification process. The synthesised compound was characterised using thin-layer chromatography (TLC), Fourier-transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance (1H-NMR) spectroscopy.

17-22

Authors: Thu Huong Nguyen*, Thanh Long Ngo, Huu Quang Nguyen

Honey is known as a natural sweetener agent with high nutritional value and health benefits, especially premium honey because of its desirable flavour and medicinal properties. Because of this, honey has been a target of adulteration through the mixing of low-quality honey and mislabelling of the honey’s origin. The aim of this research considers the potential of using mineral and physicochemical data to authenticate the origin of honey. To this end, 40 samples of 8 botanica collected from 18 different regions of Vietnam were analysed for its metal contents (Na, K, Mg, Ca, Al, Cu, Fe, Mn, Zn, Pb, Cd, Ni, Cr, Co, As, Hg) and physicochemical parameters (pH and electrical conductivity). The data were processed by multivariate analysis, which allowed the classification of honey according to its botanical origin.

24-29

Authors: Ngoc Lan Pham*, Van Boi Luu, Thi Tuyet Mai Phan, Thi Son Nguyen

Methacrylic acid was esterified with four alcohols: 1-decanol, 1-dodecanol, 1-tetradecanol, and 1-cetanol. Afterwards, the obtained monomers were copolymerized with maleic anhydride. The synthesized monomers and copolymers were characterized by 1H-NMR (Nuclear magnetic resonance) and Fourier transform infrared (FTIR) spectroscopy. The ability of the obtained copolymers to reduce the pour point of waste cooking oil-based biodiesel was investigated. The results showed that the polymer additive with the alkyl chain C14H29- demonstrated the best flow improvement performance. At a concentration of 1000 ppm, this polymer additive reduced the pour point of waste cooking oil-based biodiesel from 12 to 5oC.In this study,the effect of alkyl chain length, molecular weight, as well as the concentration of the additives on the pour point of biodiesel was also discussed.

36-41

Authors: Thanh Khiem Nguyen*, Hong Son Trinh, Gia Anh Pham, Ham Hoi Nguyen, Trung Nghia Bui, Manh Thau Cao, Quang Nghia Nguyen, Viet Khai Ninh, Tuan Hiep Luong, Tien Quyet Nguyen

Since 2010, 49 cases of liver transplants from brain-dead donors were performed at Viet Duc University Hospital. This study is a descriptive cross-section cohort study with a combined analysis of retrospective and prospective occurrences of a series of cases of liver procurement from brain-dead donors in Viet Duc University Hospital from March 2010 to March 2020. The results of this study showed several features: the average age of the brain-dead donors was 29.8±10.9 (18-69), donors were mostly male (7.17/1, 87.8%), and the main cause of brain death was head trauma. Clinically, 40.8 and 63.3% of the subjects were hypothermic and diagnosed with diabetes insipidus, however, the subjects were all well resuscitated before procurement. Therefore, haemodynamic indices and temperatures were maintained at stable levels and there was no statistically significant difference. In subclinical aspects, haemoglobin and platelet levels decreased significantly but remained within the target criteria during resuscitation while blood sodium levels increased significantly during resuscitation when compared with levels at the time of admission (p<0.001) thus corresponding to diabetes insipidus. In general, 44.90% of donors were within the ideal standard, and in the extended standard group, the highest rate was electrolyte disorders (32.65%). In conclusion, there are many variations in clinical and paraclinical body signs as well as homeostasis in the brain-dead donors. Of these signs, the most prominent were changes in haemodynamics, temperature, urine output, complete blood count, blood clotting, and blood sodium levels. These are all factors that are included in the criteria to consider the selection of a liver donor.

47-54

Authors: Thanh Tung Bui*, Bao Kim Nguyen, Minh Ngoc Le, The Toan Nguyen, The Hai Pham

Objectives: the COVID-19 pandemic triggering acute respiratory syndrome has become a major global health concern. After one year into this pandemic, special therapies for COVID-19 remain an unprecedented challenge to mankind and finding drugs to treat this disease is extremely urgent. The SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) enzyme that regulates viral replication has been examined as a potential therapeutic target for the inhibition of SARS-CoV-2 infection. In this study, the authors evaluated the ability of RNA-dependent RNA polymerase drug inhibitors by using an in silico molecular docking model. Methods: the 3D structure of RdRp enzyme (PDB ID:6M71, resolution of 2.90 Å) was derived from the Protein Data Bank RCSB. The ligand structures were collected from DrugBank for the RdRp target. Molecular docking was done by AutoDock Vina software. Lipinski’s rule of five is used to compare compounds with drug-like and non-drug-like properties. Pharmacokinetic parameters of potential compounds were evaluated using the pkCSM tool. Results: based on the DrugBank database, we collected 192 antiviral molecules and compared them to remdesivir, which has inhibitory activity with this protein target. Results showed that 26 out of 192 compounds have a higher ability to inhibit the SARS-CoV-2 RdRp enzyme than remdesivir. Next, 6 drugs were selected by visually inspecting the docking results with focus on the main interaction between crucial residues at the binding site of the SARS-CoV-2 RdRp enzyme. For the visual inspection, the existence of polar interactions with ASP760 and ASP761 were utilised as the preference criterion. Finally, Lipinski’s rule of 5 criteria and absorption, distribution, metabolism, excretion and toxicity (ADMET) profile analysis suggested five drugs that have good pharmacokinetic properties. Conclusions: these drugs were dihydroergotamine, sofosbuvir, nilotinib, tipranavir, and darunavir and may be used as anti-SARS-CoV-2 agents.

62-65

Authors: Nguyen Thuan Thien Truong, The Hao Nguyen, Cong Chinh Bui, Thi Thu Hoai Nguyen

Vibrio parahaemolyticus is the main causative agent of acute hepatopancreatic necrosis disease (AHPND) in shrimp. This study aimed to investigate how shrimp extracts affect the growth and virulence of an AHPND-causative strain known as V. parahaemolyticus XN9. To this end, the bacteria was cultured in media containing 3% extract of each of five shrimp types and their growth kinetics were compared against that from bacteria grown in brain-heart infusion (BHI) media. Eight-hour growth curves were constructed using the plate-counting method. The activity of five extracellular enzymes that contribute to bacterial virulence was examined using the agar-based method. The results showed that V. parahaemolyticus XN9’s growth was strongly enhanced in all five shrimp extract media with the highest increase (25% greater than the BHI medium) found in the giant tiger prawn extract. Additionally, all the shrimp extracts boosted the extracellular enzymatic activity of V. parahaemolyticus XN9, although to different extents. In summary, the shrimp extracts, particularly that from the prawns, not only promoted the viability and growth of V. parahaemolyticus XN9 but also its extracellular enzymatic activities.

72-78

Authors: Vo Quoc Bao, Tran Thi Van*

Air quality in megacities has been a pressing concern of environmental managers and scientists for decades. Indeed, particulate matter (PM), especially PM2.5, is considered a dangerousparticle that is harmful to human health. The current sparse monitoring network in Ho Chi Minh city (HCMC) does not accurately reflect the spatial distribution of fine particles in ambient air. Therefore, this research examines the relationship between ground-based station data and aerosol optical depth (AOD) imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra/Aqua satellite to establish a PM2.5 distribution map of HCMC. PM2.5 concentration values monitored from two ground stations were collocated by time and space with Terra/MODIS AOD data from the period of 2016-2020. Pairs of values were checked for correlation and then fit to several regression functions. The most suitable function was chosen to simulate the quantified PM2.5distributions in the study area. A high correlation between PM2.5 concentrations and AOD at the wavelength of green light (R2=0.810) was found with a linear regression model. The results showed that the highest concentration of PM2.5 was in February, and the mean value was higher than QCVN 05:2013 (32.5 μg/m3compared with 25 μg/m3, annual mean). These results support the need for essential air quality monitoring in HCMC

86-94

Authors: Vu Thanh Tam, Nguyen Ngoc Ha*, Ho Van Thuy

The Vietnam Mekong delta (VMD) is a tide-dominated delta formed by the Mekong river system. The sediments are dominantly fine grained and were deposited in the receiving basin with slight inclination of pre-existing deposits in the East sea and gulf of Thailand. The VMD is homeland to about 18 million people that exploit about 4-6 million m3/day of groundwater mainly for domestic use. In recent years, significant groundwater depletion has been occurring in many parts of the VMD due to excessive pumping. Consequently, the VMD has become increasingly faced with serious land subsidence, salt groundwater intrusion, and contamination. Establishing a 3D hydrogeological solid model and database are sorely needed to achieve sustainable groundwater management, and to serve as a basis for further in-depth analyses to quantify contributions from the above-mentioned hazards to current hydrogeological conditions. Therefore, a 3D hydrogeological solid model and database were built based on more than 1000 well logs available from the VMD. An areal distribution of the Holocene, Pleistocene, Pliocene, and Late Miocene subsurfaces from this 3D hydrogeological solid model and database showed zones of tectonic depression and uplift from Early Miocene - Quaternary. Also, the resulting areal distribution aquitards and aquifers thicknesses gave hints of ground saltwater intrusion and contamination.