Vietnam Journal of Science, Technology and Engineering

8-12

Authors: Danh Duc Ha*, Thi Oanh Nguyen

The herbicide propanil has been widely applied in Vietnam and around the world to control weeds. In this study, Acinetobacter baumannii DT isolated from soil was used to determine propanil degradation. Degradation experiments were carried out with condensed cells at 109 CFU/ml with both free and immobilized forms of the bacteria. Propanil degradation rates by bacteria immobilized in alginate were higher than those of free cells at the same concentrations. The degradation curve as a function of concentration fit well to the degradation kinetics described by the Edwards model with a maximum degradation of 0.034±0.003 mM/h for free cells and 0.053±0.005 mM/h for immobilized cells. Moreover, the immobilized bacteria could tolerate higher propanil concentrations and degrade propanil in a well-known herbicide more effectively compared to the freely suspended bacteria. These results demonstrate that A. baumannii DT immobilized in alginate is suitable for degradation of propanil in herbicides.

19-23

Authors: Thi Thu Ha Nguyen, Thi Tu Anh Le, Thanh Tra Nguyen, The Son Ninh*

A phytochemical investigation on the ethanolic (EtOH) extract of the Vietnamese Curcuma longa (C. longa) rhizomes has led to the isolation of four curcuminoids including curcumin (1), demethoxycurcumin (2), bisdemethoxycurcumin (3), and cyclocurcumin (4). The chemical structure of compounds 1-4 was elucidated by Nuclear magnetic resonance (NMR) and Mass spectrometry (MS) spectral data. Based on High-performance liquid chromatography (HPLC) quantitative analysis, the amounts of three major compounds 1-3 in the C. longa extract were calculated and reached 7.215±0.101, 3.927±0.031, and 2.255±0.049 mg/g, respectively. Curcuminoids 1-4 have induced IC50 values of 9.23-14.6 μg/ml in a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay as compared with that of the positive control resveratrol (IC50 11.5 μg/ml). Compounds 1-4 with IC50 values ranging between 8.7-15.54 μg/ml were better than the positive control acarbose (IC50 169.14 μg/ml) in α-glucosidase inhibitory examination. In addition, the EtOH extract and compounds 1-4 were also responsible for inhibitions against enzyme acetylcholinesterase and four cancer cell lines including including epidermoid carcinoma (KB), hepatocellular carcinoma (HepG2), lung cancer (SK-LU-1), and breast cancer (MCF7).

29-37

Authors: Cuong Mai Bui, Thinh Xuan Ho

The flow of a thixotropic Bingham material past a rotating cylinder is studied under a wide range of Reynolds and Bingham numbers, thixotropic parameters, and rotational speeds. A microstructure transition of the material involving breakdown and recovery processes is modeled using a kinetic equation, and the Bingham- Papanastasiou model is employed to represent shear stress-strain rate relations. Results show that the material’s structural state at equilibrium depends greatly on the rotational speed and the thixotropic parameters. A layer around the cylinder resembling a Newtonian fluid is observed, in which the microstructure is almost completely broken, the yield stress is negligibly small, and the apparent viscosity approximates that of the Newtonian fluid. The thickness of this Newtonian-like layer varies with the rotational speed and the Reynolds number, but more significantly with the former than with the latter. In addition, the lift and moment coefficients increase with the rotational speed. These values are found to be close to those of the Newtonian fluid as well as of an equivalent non-thixotropic Bingham fluid. Many other aspects of the flow such as the flow pattern, the unyielded zones, and strain rate distribution are presented and discussed

44-48

Authors: Khoa Mai Trong, Phuong Pham Cam, Luan Nguyen Duc, Hung Nguyen Quang, Phuong Dao Manh, Thai Pham Van

To assess the effectiveness of radiosurgery with a rotating gamma system (RGS) for paediatric brain tumours and arteriovenous malformation (AVM), this work was carried out on 123 patients with brain tumours or AVM received radiosurgery at Bach Mai hospital. The median dose was 13 Gy from a range of 8 to 20 Gy. Endpoints include the effects of increased intracranial pressure, seizures, hemiplegia, and tumour size on the syndrome. Results exhibited that the percentages of patients with complete response, partial response, and disease progression out of 59 patients with headache accounted for 11.9, 69.5, and 18.6%, respectively. Of the 20 patients with seizures, 30% had complete response, 65% partial response, and 5% stable disease. Regarding brain tumour size, 9 months after treatment, those with complete response, partial response, stable disease, and disease progression made up 18.7, 50.4, 14.6, and 16.3% of the total patients, respectively. There was no statistically significant effect of radiation dose on the results. This study showed a high percentage of children with brain tumours and AVM undergoing radiosurgery with a RGS had symptomatic responses after treatment.

53-61

Authors: Tin Dai Luong, An Tran-My Le, Nhan Thien Vo, Thi Hiep Nguyen

Hydrogel materials have attracted extensive research over the last few decades, especially in tissue engineering, due its many comparable properties with native tissue. This study proposes a new approach to hydrogel fabrication that combines oxidized alginate (OA) into N,O-carboxymethyl chitosan (NOCC) and an oxidized hyaluronan-based hydrogel system employing low cost, domestically sourced chitosan and alginate. Hydrogel fabrication parameters including component ratio and hydrogel concentration were studied. Fourier transform infrared spectroscopy (FT-IR) analysis was applied to confirm the chemical structure of the modified materials. Fabricated hydrogel samples were assessed by cross-sectional surface morphology, equilibrium swelling degree, and in vitro degradation behaviour. The results revealed NOCC and oxidized hyaluronic acid (OHA)-OA component contributions toward hydrogel properties, a threshold of raising total polymer content within the network, and a comparison with previous formulations using unmodified alginate. Using low cost domestic resources is a promising way to reduce fabrication expenses, and further work should be performed to evaluate the potential of this cost-effective hydrogel for the tissue engineering field.

69-75

Authors: Lam Quang Nguyen, Hoang Minh Anh An, Vu Quang Thinh Tran, Phuc Hoang Anh Le, Van Luan Tran, Mai Thao Le, Trong Kien Nguyen, Thi Thanh Huong Ha

Cognition is one of the most vital brain functions, which ranges from assisting students in recalling what they have been taught to assisting us in concentrating while accomplishing chores. Nowadays, many jobs require advanced cognitive abilities, particularly among high school and university students. As a result, preserving or improving our cognitive abilities has become necessary in modern society. Alpha-wave music, which targets the brain frequency range from 8 to 12 Hz, is a promising approach to boosting cognitive performance. The purpose of this study is to evaluate the immediate, short term, or long term effects of alpha wave music on the cognitive performance and brain activity of students. In an online experiment, two groups of students were recruited and randomized into control and experimental groups. The experimental group was required to listen to alpha music for two weeks (here called the intervention). Participants from both groups will have their cognitive performance assessed before, immediately after, and two weeks following the intervention. In the immediate effect experiment, another group of participants have their alpha relative power evaluated while performing different tasks. The results of the online experiment revealed that feedback from participants listening to alpha music are mostly positive, while the response time of cognitive tasks indicated an improvement trend (p<0.05). The positive potential of alpha music was also confirmed with the immediate effect study where the alpha power was higher during alpha music exposure than during the remaining sessions. In conclusion, this study provided preliminary evidence to support the implementation of alpha music intervention to improve the cognitive function of students.

82-89

Authors: Thi Hoa Tran, Boris Fabres, Ngoc Ha Hoang, Hoai Le Tran

While the tourism and hospitality sectors in Vietnam have been rapidly developing, the increasing consumption of natural resources and production of associated waste, especially in coastal and island sites, threaten these marine areas with pollution. This study provides data on solid waste from 10 hotels in three coastal provinces of Vietnam, namely, Hai Phong, Quang Nam and Phu Yen. The results indicated significant percentages and volumes of organic waste especially from large-scale hotels with in-house food services like restaurants and bars. The proportions of organic and recyclable solid waste from all three surveyed cities ranged between 35-84% and 10-27%, respectively. Plastic waste accounted for a relatively high proportion of solid waste ranging from 27 to 60% total solid waste by volume and from 7 to 30% by weight. In particular, PET plastic made up the highest proportion of solid waste in Cat Ba town (52.41%) and Tuy Hoa city (39.81%) while single-layer plastic accounted for the highest proportion (29.55%) in Hoi An city. Plastic waste from food packaging, related to the cultural habits of guests that bring instant food items during their stay, was identified as an important issue, which reflects a valuable but presently wasted potential resource. These quantities of hotel solid waste can be recovered and provide additional environmental and health benefits to the community by not being dumped, landfilled, or openly burned.

10-15

Authors: Nam Trung Tran*, Thi Minh Huong Pham, Tan Lam Nguyen

Considering its superior photocatalytic activity and excellent chemical stability, titanium dioxide (TiO2) is an excellent candidate for photoelectrochemical (PEC) hydrogen production. Besides, many challenges exist ahead of improving the photoresponse of TiO2 to visible light while maintaining high photocatalytic activity. Herein, the authors report recent efforts to improve the visible light PEC activity of TiO2 nanorods by in-situ doping with various iron (Fe) concentrations using a hydrothermal method. The influences of Fe doping concentrations on the morphological and structural properties of TiO2 nanorods were investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. Furthermore, this work demonstrates that Fe doping could improve the PEC activity of TiO2 nanorods under visible light irradiation. The authors achieve a remarkable enhancement in the photocurrent density, as high as 2.9 mA/cm2 at an applied voltage of 0.5 V, for the sample synthesised with an Fe doping concentration of 10 mM. These results reveal that Fe-doped TiO 2 nanorods can serve as ideal materials for PEC applications.

21-27

Authors: Tien Cong Nguyen*, Duc Dung Pham, Thi Minh Dinh Tran, Thi Thuy Linh Bui

Five new derivatives of N-(4-oxo-2-thioxothiazolidin-3-yl)-2-((3-aryl-4-oxo-3,4-dihydroquinazolin-2-yl)thio) acetamides have been synthesized successfully through a four-step process from anthranilic acid and aryl isothiocyanates as starting materials. The total yields ranged from 29 to 31% and these structures were determined by IR, 1H-NMR, 13C-NMR, and HR-MS spectra.

34-41

Authors: Suong V. Hoa*, Daniel I. Rosca

This paper presents an application of 4D printing of composites (4DPC) to make composite structures of complex geometries without the need for complex moulds. This application is illustrated through the formations of the letters V, i, e, t, n, a, and m, which form the word Vietnam. In the procedure, laminates made of carbon/epoxy prepregs are laid on a flat mould. The deposition of the prepregs on the flat mould is done using an automated fibre placement machine (AFP), which can be considered as a large size 3D printer. For a smaller structure, the prepreg deposition can be accomplished using an AFP machine or by hand lay-up. Upon curing and cooling to room temperature, the laminate transforms itself from a flat configuration to the shape of the intended letter, except for the letter V. The mechanism that enables this transformation relies on the anisotropy of the laminate. This method has many potential applications, particularly in the delivery of bulky three-dimensional structures to remote locations.

50-53

Authors: Thi Loan Pham*, Xiao Jian Zhuang, Thi Hoai Thu Nguyen, Phan Anh Nguyen, Duy Thanh Trinh

After almost 30 years and many projects investigated all over the world, the full potential that 3D printing technology can bring to the construction industry has yet to be realised. There are many challenges that face the application of 3D printing technology to the construction field. Among these challenges, mixture proportion design is crucial for the preparation of 3D printing concrete. Therefore, this study focuses on mix proportion design approaches and tests, which access some rheological properties of the fresh mortar. Because they are highly practical and convenient in construction, materials including cement, fly ash, and natural sand were selected for mixing proportion analysis. Slump-flow tests, V-funnel tests, and buildability tests were also employed in this study. This first analysis on the mixture proportion and method to evaluate rheological properties of 3D printing mortar can be considered a reference and orientation to develop 3D printing technology in Vietnam.

59-64

Authors: Van Thieu Ha*, Huu Tung Trinh

Eosinophilic gastroenteritis (EGE) is a digestive disorder in children and adults that is characterised by eosinophilic infiltration in the stomach and intestine. Depending on the dominant layer of infiltration, this disorder is classified into three types, namely, mucosal, muscularis, and subserosa. Subserosa clinical presentation usually begins with ascites and is sometimes associated with symptoms of intestinal obstruction. Ascites is characterised by marked eosinophilia in ascitic fluid. EGE with ascites simulating appendicitis and peritonitis is rare in paediatric patients. This publication aims to report a case series of EGE with clinical features, treatment responses, and a review of the current strategies in the management of eosinophilic ascites.

69-75

Authors: Thi Thu Hang Ta, Bao Kim Nguyen, Thi Hong Khanh Do, Thanh Tung Bui*

The COVID-19 pandemic causing acute respiratory syndrome is a significant public health problem. Drugs that can treat this disease are currently a high priority. The SARS-CoV-2 spike protein and human ACE2 enzyme receptor, which both play important roles in virus entry into the host cell, are promising therapeutic targets for inhibiting viral infection. This research evaluates the potential of chalcone compounds to inhibit the spike proteins and ACE2 enzymes through molecular docking in silico approaches. Based on the ChemFaces database, we collected 92 chalcone compounds. These compounds were further docked to target the active sites of spike protein and human ACE2. After comparing the binding energies of the 92 compounds to artemisinin, ribavirin, and lopinavir, which have inhibitory activity to these protein targets of SARS-CoV-2, we chose 20 out of the 92 compounds that had a higher ability to inhibit the protein targets than the reference inhibitors. Next, five phytochemical compounds with the best binding energy were selected, which included flavanomarein, sarcandrone B, sarcandrone A, calyxin H, and sieboldin. Then, Lipinski’s 5 rule was used to evaluate the druglike properties of these compounds. Predictive ADME/tox filtering tests were also applied to the top docked compounds. The results suggest that sarcandrone B has good pharmacokinetic properties, which should be further explored as an anti-SARS-CoV-2. To confirm these findings, experimental studies are recommended.

82-85

Authors: Yen Hoang Luu, Thai Hong Pham*, Hong Minh Bui, Jérôme Constant

A taxonomic study on the genus Macrosemia from Vietnam in which a new species Macrosemia sapaensis sp. nov. is described. This species was collected from Lao Cai province in north Vietnam. Information on the distribution, photos of an adult, and illustrations of the male genitalia are provided for the new species. Based on the male characteristics, we provide a key to the genus Macrosemia Kato, 1925 (Hemiptera: Cicadidae) of Vietnam.

95-98

Authors: Khon Huynh

Fibronectin is an abundant and ubiquitous extracellular matrix component that regulates a wide range of cell functions by directly interacting with cell surface integrin receptors. In a prior study, we observed that fibronectin can accelerate the autologous cellular repopulation of implanted decellularized grafts, enhancing their adhesion capacity and biocompatibility, through fibronectin fibrillogenesis. The supportive effect of deposited fibronectin was shown to be dissimilar in different regions of implanted decellularized grafts. This led us to question whether there is any difference in conformation of fibronectin deposited on the luminal and adventitial surfaces of decellularized aortic conduits after implantation. In this study, we doubly labelled fibronectin with a fluorescent resonance energy transfer (FRET) pair and use this to analyse differences in conformational changes of adsorbed fibronectin at different sites of the decellularized aortic conduits.

9-13

Authors: Phuong Hue Luu, Phuong Hue Tran, Hoang Van Nguyen, An Le Bao Phan, Oanh Hoang Nguyen, Man Van Tran, Phung My Loan Le, Thanh Duy Vo*

In this study, we aimed to evaluate the effect of sulfolane (SL) as a co-solvent in conventional carbonate-based electrolytes and its compatibility with a LiMn2O4 (LMO) cathode. The amount of SL was varied from 10 to 50 vol.% in an EC-DMC mixture (1:1 vol. ratio) within a 1.0-M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. The thermal properties of the electrolytes were studied using thermogravimetric analysis (TGA). Solvent flammability was measured via self-extinguishing time (SET) and ignition time indexes while viscosity was gauged by the Ostwald method. Ionic conductivity was evaluated by electrochemical impedance spectroscopy (EIS). Electrochemical techniques such as cyclic voltammetry (CV) and galvanostatic cycling with potential limitation (GCPL) were carried out to evaluate battery performance with the selected electrolytes. The results indicated that an increasing proportion of SL leads to an enhancement of the thermal and oxidation stability of the electrolytes. At 20-vol.% SL and below, the as-synthesized electrolytes exhibited a high ionic conductivity of 7.45 mS.cm-1 (25oC) and enabled LMO to deliver a specific capacity of 103 mAh.g-1 with a capacity retention of 92% after 20 cycles at C/10 rate. Due to such favourable properties, SL can be used as a co-solvent in EC-DMC systems to enhance the safety of lithium-ion batteries under high voltage conditions.

20-26

Authors: Thi Minh Thu Tran*, Thanh Binh Nguyen, Peter Winterhalter, Gerold Jerz

Opuntia stricta var. dillenii and Atriplex hortensis var. rubra, two plant species with abundant betalain and flavonoid content, were studied by high performance countercurrent chromatography (HPCCC) coupled with ESI-MS/MS in an off-line detection process. Both CCC runs used tert.-butyl-methyl-ether/n-butanol/acetonitrile/water 1% trifluoroacetic acid (v/v/v/v, 2:2:1:5) as a biphasic solvent system within an elution-extrusion mode. The resulting fractions were scanned by an off-line sequential injection to ESI-MS/MS approach. The separation of Opuntia stricta var. dillenii extract showed a partial isolation of principal betalains (betanin) from their derivatives (betanidin, phyllocactin, feruloyl-betanin, betaxanthin), degraded products (hydroxyl-neobetanin, mono decarboxy-betanins), and flavonoid glycosides (isorhamnetin-rutinoside, kaempferol-rutinoside). In case of Atriplex hortensis var. rubra, this study confirmed the coexistence of several flavonoids (quercetin-O-malonyl glucoside, kaempferol-O-malonyl glucoside) and generated few pure pigment fractions (celosianin II) for structural elucidation.

33-38

Authors: Tien Manh Hoang*, Thi Thanh Nguyen

Lung cancer is the leading cause of cancer death globally. Non-small cell lung cancer (NSCLC) constitutes more than 80% of all lung cancers, and patients with distant metastasis have much higher mortality. The survival times of NSCLC patients with metastasis have been reported in early studies, however, it remains unclear whether there are variations or patterns in survival times of patients with different metastases. Therefore, we assessed risk factors for distant metastases and the effects of different organ metastasis on overall survival (OS) in patients with NSCLC. Methods: demographics and clinical data of NSCLC patients with and without distant metastasis were collected from the Surveillance, Epidemiology, and End Result (SEER) database between 2010 and 2016. We investigated risk factors for distant metastasis patients and compared the difference in OS of NSCLC patients with different metastatic sites. Results: a total of 3849 patients diagnosed with NSCLC were screened from the SEER database with 41% (1577) of the patients having distant metastasis. During the follow-up period, 3221 (83.7%) patients died and, of all the deceased patients, 2935 (88.4%) died of lung cancer while only 286 (11.6%) died from other diseases or causes. The occurrence of distant metastasis was closely related to the patient’s age, primary tumour site, tumour grade, T stage, N stage, surgery of primary site, radiation therapy, and chemotherapy (p<0.05). Compared to patients without metastasis, whose median OS was 13 months, the median OS of patients with metastasis was 6 months (lung), 5 months (liver), 5 months (bone), 4 months (brain), and 3 months (multiple organs). Conclusions: distant metastasis indicates a poor prognosis in NSCLC patients. There were significant differences in the prognosis of different metastatic sites and the order of their OS from high to low was: no metastasis > lung metastasis, liver metastasis, bone metastasis > brain metastasis, multiple organ metastasis

43-48

Authors: Hai Trieu Ly, Vu Khanh Trang Le, Van Minh Le, Cong Sanh Phan, Chau Tuan Vo, Minh Ly Nguyen, Thi Anh Dao Phan*

This study screened phytochemicals to determine their total polyphenols content (TPC) by Folin-Ciocalteu reagents and to evaluate antioxidant activity using DPPH scavenging, ABTS cation decolorization, and reducing power assays of various extracts of Symplocos cochinchinensis leaves. A correlation between TPC and antioxidant activity was analysed by Pearson’s method. The results indicated that S. cochinchinensisleaves contained triterpenoids, alkaloids, anthraglycosides, flavonoids, anthocyanosides, proanthocyanidins, polyphenols, tannins, saponins, polyuronics, and reducing agents. All extracts had antioxidant properties with the ethyl acetate fraction exhibiting the highest antioxidant capacity, which had the lowest IC50 in DPPH (83.33 μg/ml), an ABTS of 46.21 μg/ml, and EC50 of 69.10 μg/ml in reducing power. There was a significant negative correlation between the TPC in S. cochinchinensis leaf extracts and their IC50 and EC50 values of antioxidant activity. It was suggested that S. cochinchinensis leaves have a great potential for antioxidant activity based on its high total polyphenol content and potential for use as a traditional treatment

53-62

Authors: Thai Phuong Thao Nguyen, Phuong Hien Le, Thi-Hiep Nguyen*

Xanthan gum (XG) is recognised as one of the most popular natural polymers extensively used today due to its biode-gradable and biocompatible properties, and, therefore, XG can be used to produce hydrogels with other polymers to expand its uses. However, at present, there has not been much research on preparing injectable hydrogels from XG. Moreover, up to now, there are only a limited number of review articles related to this topic. This review will provide a well-organised and somewhat extensive presentation of previous studies that have been executed on injectable hydrogels from XG. Also, applications have been using XG to fabricate injectable hydrogels such as cartilage tissue engineering, bone tissue engineering, delivery system, and bioink will be reviewed.

72-77

Authors: Yen-Nhi Ha Nguyen, Long Binh Vong, Hong-Anh Pham, Dang-Quan Nguyen, Phan Ngoc Uyen Phuong, Huu-Phuong Mai, Nhu-Thuy Trinh*

Type 2 diabetic patients have an increased risk of developing serious long-term complications such as cardiovascular disease, retinopathy, nephropathy, neuropathy, diabetic foot, and osteoporosis. However, the correlation between hyperglycaemia and osteoporosis has not yet been fully clarified. In this research, we investigated the effect of different high D-glucose concentrations (25, 50, and 100 mM) on osteogenic differentiation of human non-diabetic and diabetic adipose tissue-derived mesenchymal stem cells (nAT-MSCs and dAT-MSCs). The differentiated cells were qualified by Alizarin Red S staining and quantified by measuring the absorbance at 482 nm. The expressions of osteogenic master genes were examined by quantitative reverse transcription polymerase chain reaction (qRT-PCR) methods. Interestingly, the osteogenic differentiation and the expression of osteogenic-specific genes (Runx-2 and ALP) decreased with an increase of D-glucose concentration. Our work contributes to the understanding of the relationship between hyperglycaemia and osteoporosis and support the role of stem cells in developing new medicine or therapeutic treatment for preventing diabetic complications

85-89

Authors: Huy Toan Do*, Thanh Binh Nguyen, Tuan Minh Ly

Tidal energy is a renewable energy source produced by the rise and fall of ocean tides. Tidal energy can be exploited using a special type of generator that converts tidal energy into electricity. Tidal power generation has the potential to open up many prospects for energy field and minimize carbon dioxide emissions that cause the greenhouse effect. To evaluate the possibility of tidal power, it is necessary to have documents and data on average annual tidal amplitude, tidal regime, and main tidal waves in the study area. To calculate the tidal power potential for the east coast of Vietnam, this article applies the calculation formula of tidal power energy by Russian scientist L.B. Bernstein. The annual mean tidal amplitude and the K1, O1, and M2 wave amplitude data at nearly 2000 calculation points along the coast of Vietnam were extracted from the TPOX8-Atlas harmonic constant set. Research results showed that Vietnam has great potential for tidal energy along the Hai Phong - Quang Ninh coastal area and the southeast region with a prospective 41.6 GWh/km2/y.

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.

8-14

Authors: Quoc Viet Bui, Thuy Vy Phan, Tien Khoa Le*

In this work, we proposed to combine oxalic acid and ferric ions in very low concentrations to create new, economic, and effective homogeneous photo-Fenton catalytic systems for the degradation of methylene blue. The effects of ferric concentration, H2C2O4 concentration, pH, and tert-butanol on the catalytic activity were also investigated. According to the experimental results, Fe3+ ions exhibited impressive catalytic performances in the presence of H2C2O4 at concentrations below type B (5.0 mg.l–1) from the Vietnam National Technical Regulation on Industrial Wastewater. Specifically, a ferric concentration of 3.0 mg.l–1, H2C2O4 concentration of 10–3 mol.l–1, and pH value of 3 were found to be the best conditions for MB degradation under UVA light. Furthermore, owing to a very low concentration of ferric ions, iron sludge formation can be avoided after wastewater treatment, which makes the photo-Fenton process suitable for practical applications.

18-23

Authors: Phan Minh Vuong*, Do Huu Duy Khoa, Phan Thanh Thao

Piroxicam is a bioactive compound classified as a non-steroidal anti-inflammatory drug (NSAID). However, its low solubility in water imposes a serious limitation for its application in the pharmaceutical industry. Using cyclodextrins to form complexes can enhance the dissolution rate, solubility, and bioavailability of piroxicam. In this study, piroxicam/β-cyclodextrin complexes are prepared in supercritical carbon dioxide (SC-CO2) in the solid state and the process was optimized using response surface methodology (RSM). UV-Vis spectroscopy, differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and dissolution profile in water were used to characterized the complex under optimized temperature, residence time, moisture, and ternary agent. Finally, the maximum reaction yield of the inclusion complex was predicted to be 95% at the optimal conditions of 266 bar, 136oC, 1.84:1 ratio of cyclodextrin:piroxicam, and 1.5:1 ratio of lysine:piroxicam. Large scale production of inclusion complexes can be developed from the results of this work on optimizing conditions.

35-41

Authors: Dang Giang Chau Nguyen*, Thi Lan Anh Tran, Thi Thanh Lam Tran, Thi My Duyen Ngo, Thai Long Hoang, Van Hop Nguyen, Kurt Kalcher

Pesticide dissipation on foods like vegetables, fruits, and cereals is one of the most concerning aspects in pesticide toxicology as it involves risks to human health and food safety. In light if this, a laboratory-scale study was conducted for two separate systems, green onions (Allium fistulosum) and mustard greens (Brassica juncea),in order to identify the dissipation of fipronil and cypermethrin, two commonly used insecticides, under a tropical climate. After the pesticide application, vegetable samples from these microcosms were collected each day for 7 days to measure fipronil and cypermethrin (n=3) residues. The analytical method was validated and showed repeatability and trueness. The decay equations fit well to first-order kinetics with a correlation coefficient of R2>0.93 and p<0.0005. The calculated half-life values of fipronil were 2.9 d for green onions and 3.2 d for mustard greens while those of cypermethrin were, respectively, 4.5 d and 3.2 d. To meet the maximum residue levels (MRL) of fipronil (0.02 mg/kg) and cypermethrin (0.7 mg/kg) on vegetables, the estimated pre-harvest intervals should be updated to 23 d and 7.5 d, respectively.

48-55

Authors: Thi Lan Anh Luong*, Thu Lan Hoang, Minh Ngoc Nguyen, Ngoc Dung Nguyen

Microdeletions of Y chromosomes frequently occur in 3 subregions of the AZF, namely, AZFa, AZFb, and AZFc, with 6 basic STS marker sequences, which are sY84, sY86 (AZFa), sY127, sY134 (AZFb), and sY254, sY255 (AZFc). According to EAA/EMNQ guidelines, 11 additional AZFabc marker sequences should be used to determine the extent of the microdeletion in the AZF region of infertile men, which is known as 11 extended STSs. By applying mPCR, the authors develop an optimal detection procedure for the 6 basic STS and 11 extended STS using 3 multiplex PCR reactions. The first multiplex PCR reaction includes 6 basic STS plus the 2 control sequences sex-determining region Y (SRY) and zinc finger protein X/Y-linked (ZFX/Y). The second multiplex PCR reaction includes the 6 extended STS sY88, sY1182, sY105, sY121, sY1191, and sY1291 and the 2 control sequences SRY and ZFX/Y. The third multiplex PCR reaction includes the 5 extended STS sY153, sY160, sY82, sY143, and sY83 and the 2 control sequences SRY and ZFX/Y. Six basic primer sequences and eleven extended primer sequences are redesigned to simultaneously pair and amplify STS in the same multiplex reaction: set of 8 primers for 6 basic STS: 6 basic STS + 2 (SRY, ZFX/Y), 8 extension primers set E1: 6 extended STS + 2 (SRY, ZFX/Y), and 7 extension primers set E2: 5 extended STS + 2 (SRY, ZFX/Y). We successfully designed primer pairs with high specificity and stability and successfully amplified 6 basic STS and 11 extended STS, which ensures that the STSs have the correct sequence as recommended by EAA/EMQN and are consistent with the NCBI gene bank. This study has successfully developed a procedure to simultaneously detect 17 STSs, including 6 basic STSs and 11 extended STSs in the AZF region using 3 multiplex PCR reactions.

63-69

Authors: Van Thong Ngo*, Huu Hanh Tran, Chi Tao Phan

The green water dragons of Phu Quoc island, Vietnam have been given a VU rating (vulnerable) by the Vietnam red data book and the International Union for conservation of nature and natural resources. A description of the morphological characteristics and sequenced mitochondrial cytochrome oxidase subunit 1 COI gene was completed following a survey of thirty individuals from September 2018 to May 2019. Their body weights ranged from 115 to 850 g and their snout-vent length ranged from 120 to 280 mm. They were identified to have the highest similarity to the species Physignathus cocincinus by the barcode of life data system. Their COI gene sequence was compared to GenBank (KM272197.1) and the following alternations were found: C5483T, A5486C, C5537A, A5564G, A5591G, T5633C, G5684A, A5771G, A5849C, C5927T, T5942C, C5993T, G6002A, and A6020G. The neighbourjoining tree of their COI sequence divergence indicated a distance (compared to the same published species) from 2.3 to 2.8%. Thus, it might be possible that the green water dragons of Phu Quoc island are evolving into a specific subspecies. However, more green water dragon specimens from Phu Quoc should be sequenced to ensure a conclusion and further research into farming should be initiated to protect this vulnerable species.

78-84

Authors: Nguyen Phuong Tan Le, Nguyen Khoi Dao*

Climate change has directly and indirectly affected the livelihood of households that rely on climate conditions for their livelihood in the coastal areas of Vietnam. This study applied the livelihood vulnerability index (LVI) to assess the vulnerability of a household’s livelihood under the effect of climate change in one of the most highly vulnerable areas of Viet Nam - the Can Gio coastal district of Ho Chi Minh city. Based on a survey of 107 households within six communes and one town located in the Can Gio district, the LVI was calculated at both district and commune scales. The results reveal that the district of Can Gio is at a moderate vulnerability level (LVI=0.303), while the Ly Nhon commune (LVI=0.334) is the most vulnerable of the seven surveyed areas. Additionally, the aspects of livelihood strategies (0.516), socio-demographic profile (0.391), and food (0.385) are critical to the determination of the livelihood vulnerability of the seven surveyed communes.

92-96

Authors: An Trung Nguyen*, Thi Cam Ha Nguyen, Tien Thinh Lai, Hoang Giang Nguyen, Ha Vu, Thanh Long Nguyen

The radioactivity concentration of Cs-137 was determined in 826 soil samples collected from Hai Phong, Quang Ninh, and Lang Son. The residual levels of Cs-137 have also been assessed and compared with previous publications to obtain a trend in Cs-137 in the surface soil. The actual measured average of the residual level of Cs-137 in the soil samples collected in this study was 236±146 Bq/m2, while the value calculated using the publishedexperimental formula was 407±77 Bq/m2. The impact of Cs-137 deposition from the Fukushima nuclear accident (2011) in this area is confirmed to be negligible.