Vietnam Journal of Science, Technology and Engineering

3-7

Authors: Thi To Yen Nguyen, Phung Anh Nguyen,Thi Thuy Van Nguyen,Tri Nguyen, Ky Phuong Ha Huynh*

In this work, the efficiency of a material prepared from red mud and rice husk ash (ZRM), in Cr(VI) absorption, without the use of acid to neutralize raw red mud (RM), was examined. The physico-chemical characteristics of the obtained material weredetermined by several methods, including BET nitrogen adsorption, XRD, SEM, and TEM. ZRM was employed in the adsorption of Cr(VI) in solution at 25oC with a Cr(VI) concentration of 20 ppm.The results showed that the nano particles of material were formed within the size range of 30-50 nm, and that the specific surface area of the material was 70.76 m2/g. The conditions of the adsorption process (i.e., the initial pH of the solution, the stirring rate, and the material content) were seen to significantly affect the efficiency of Cr(VI) adsorption at the material’s surface. The optimum conditions for Cr(VI) adsorption via ZRM were determined as pH=2, a stirring rate of 300 rpm, and a material content of 10 g/l. With these conditions, the maximum adsorption capacity for Cr(VI) in a solution of ZRM was found to be 23.32 mg/g.

15-18

Authors: Thien-Trong-Nguyen Le, Thanh-Dat Dinh, Dinh-Dai Nguyen, Thi-My-Chi Vo, Thanh-Son Dao*

Metal contamination and pollution are of human and environmental concern Phytoremediation is one of the suitable high-efficiency means to treat metal pollution. This study aims to observe the responses of Pisum sativum L. in its early life stage to three metals, arsenic (As), copper (Cu) and lead (Pb) in laboratory conditions. Seeds of P. sativum were treated with water containing 0, 50, and 500 μg/l of these metals over a period of 7 days. The results show that the germination of seeds is similar for the control and metal treatments, ranging from 90-100% after 4 days of watering. Shoot development of the seeds exposed to the metals and the control were not significantly different, except that the samples which had undergone the treatment with 500 μg Pb/l had longer shoots. Our results evidence a high capacity for metal tolerance in this plant in the early stages of its life. Therefore, P. sativum may be a promising candidate for the phytoremediation of metal contamination and pollution.

25-30

Authors: Nho Thuan Nguyen*, Vu Nguyen Doan, Ha Le Bao Tran

In recent years, three-dimensional (3D) in vitro tumor models have become more common in cancer research across the world. Selecting scaffolds, seeding cells into the scaffolds, and culturing them are pivotal for the morphologies and proliferation of cancer cell lines. Therefore, this experience has developed a 3D tumor model based on co-culturing MCF-7 cells and fibroblasts (3:1) into gelatin-alginate scaffolds (3x3x5 mm3). Quantity, proliferation, and morphologies of tumors were evaluated through cell yield on a scaffold, enzymatic assay, cell number, hematoxylin and eosin stains (H&E), and scanning electron microscope (SEM). The results indicate that the complex of MCF-7 cell lines and fibroblasts in scaffolds proliferated and increased in terms of cell mass number and cell mass size. Their morphologies align with those of the in vivo figures demonstrated previously. This research facilitates new opportunities for the study of cancer biology and drug screening in Vietnam.

39-44

Authors: Van Tho Le*, Van Tu Nguyen, Ngoc Diem My Tran, Damin Lee, Won Kim, Van Son Dang, Doan Dang Phan, Duc Thien Luong

Brachyuran crabs are the most diverse group of crustaceans. They are found in most marine habitats such as coral reefs, sandy beaches, rocky beaches, mangroves, and seagrass meadows. In this study, we investigated the species composition of brachyuran crabs at 10 sampling locations belonging to three habitats (mangrove forest, artificial dykes, sandy beaches) at Duyen Hai town on August (rainy season) and December (dry season) in 2017. We found that there were 22 species belonging to 10 genera of six families present in the research area. The Ocypodidae family is the most abundant, with 45.5% of the species, following by the Grapsidae (22.7%), Sesarmidae (13.6%), Portunidae (9.1%), Matutidae (4.5%), and Xanthidae (4.5%). The densities of brachyuran crabs ranged from 2.0±1.1 (inds/m2) to 17.2±4.3 (inds/m2). The mangrove forest habitat showed a greater diversity of species than the sandy beach and artificial dyke habitat. The rainy season supported greater diversity than the dry season.

52-58

Authors: Thi Kieu Oanh Pham, Van Cuong Pham, Thi Thuy Lai, Duc Long Tran, Thanh Thuy To*

The teleost fish medaka (Oryzias latipes) is currently used by laboratories worldwide as a model for many human diseases, including bone diseases. Our research group focuses on a medaka model for osteoporosis. To characterize the bone indexes of diseased animals, the bone development indexes of healthy wild-type fish are required for comparative analysis. Thus, this study examined the developmental and bone development indexes of wild-type medaka larvae at 11 and 16 days of age, the two developmental stages selected for the analysis of diseased patterns in osteoporosis-induced animals. The assessed parameters included the total body length of live larvae, number of caudal fin rays, vertebrae, and neural and hemal arches, as well as the total areas of mineralized vertebrae and lengths of mineralized arches. The obtained data are important for subsequent studies on bones using this fish model

66-70

Authors: Nguyen Van Thuan, Ngo Thi Thanh Thuy, Nguyen Hong Hai, Nguyen Cong Nguyen, Xuan-Thanh Bui*

Human urine is known as the excreta with a high concentration of nitrogen and phosphorus, causing eutrophicationin water bodies. In this study, human urine was used to feed microalgae (Chlorella vulgaris) in a membrane photobioreactor (MPBR) at various microalgae retention times (MRTs) and hydraulic retention time (HRT) of 2 days to evaluate its biomass production. The results indicate that MPBR was operated under MRT of 2 to 5 days and HRT of 2 days, which performed the optimum condition with biomass productivity from 146.43±8.52 to 151.93±15.05 mg.l-1.day. Moreover, the MPBR using the urine as a nutrient source demonstrated the high performance in biomass production and strong growth of microalgae.

78-81

Authors: Danh Quan Le, Thi Thuy Pham*, Hoang Giang Pham, Manh Khai Nguyen

This paper evaluates the adsorption capacity of iron-rich adsorbent to remove arsenic from groundwater in decentralised water supply treatment; a pilot-scale with a capacity of 5 m3/day has been investigated at Cu Da Nursery School in Hanoi city, in which the concentration of arsenic in groundwater is abnormally high (175-400 μg/l). The pilot system was designed to include a series of processes, such as aeration, sedimentation, sand filtration, and adsorption, using the iron-rich adsorbent and activated carbon from coconut shells. The pilot system was tested with three operated modes. The results demonstrate that the treatment efficiency of the overall treatment processes was significantly higher than that of the traditional treatment system used by local people. After aeration, sedimentation, and sand filtration, the water quality was discovered to respond substantially in reducing iron by over 96% (from 8-12 mg/l to less than 0.3 mg/l) arsenic by 55 to 60%, but after iron-rich adsorbent, the concentration of arsenic decreased to less than 10 μg/l, which fulfills Vietnam National technical regulations concerning drinking water quality

89-94

Authors: Xuan Hien Nguyen*, Xuan Trinh Nguyen, Hong Hanh Nguyen, Thanh Thuy Tran, Duc Quyen Le

This research utilizes the disaster risk concept developed by the Intergovernmental Panel on Climate Change (IPCC) to determine and assess the storm surge risk in aquaculture in the coastal area from Quang Ninh to Ninh Binh province. The results indicated that the highest level of risk occurred in Thai Thuy district (Thai Binh province) and Quang Yen town (Quang Ninh province). The second highest level or risks occurred in Tien Hai district (Thai Binh province), Mong Cai city and Hai Ha district (Quang Ninh province). The lowest level of risk transpires in Uong Bi city (Quang Ninh province) and Kien An district (Hai Phong city). The results provide a scientific basis to support local government in establishing proactive response plans to storm surges, reduce and prevent storm surge damage to aquaculture, assist policy making and establish suitable development priorities for the coastal areas in the Northern region

3-8

Authors: Thi Thu Huong Tran, Thi Tuyet Mai Phan*, Van Boi Luu, Ngoc Lan Pham

This research illustrates the results of a study on the synthesis of maleic anhydride-vinyl acetate copolymers (MAVA) with the monomer molar ratio of 1:1 by the radical polymerisation method in which benzoyl per-oxide was used as a catalyst. The structure and compo-sition of MAVA were characterised by FTIR, 1H-NMR and 13C-NMR spectra. The molecular weight of the co-polymers was determined by the viscosity method. The copolymers were then modified by the esterification reaction with hexadecanol - a long alkyl chain alcohol. The modified copolymer products (MAVAC) were used as additives to improve the cold flow properties of palm oil-based biodiesel through pour point temperature measurement according to standard ASTM-D97 and dynamic viscosity according to ASTM D445-97. The re-sults showed that the MAVAC additives with the comb-shape structure at the concentration of 1000 ppm could decrease the pour point temperature of palm oil-based biodiesel by 5.5oC and dynamic viscosity by 0.17 cPs.

13-18

Authors: Trinh Nguyet Tran, Huynh Xuan Phong, Bui Thi Thao Anh, Bui Hoang Dang Long, Nguyen Ngoc Thanh, and Ngo Thi Phuong Dung*

Acerola (Malpighia emarginata) vinegar is one kind of fruit vinegar produced using acetic acid fermented by acetic acid bacteria. In this study, Acetobacter senegalensis A28 was applied in acerola vinegar production at a high temperature. With 1.0% (v/v) of A. senegalensis A28 inoculum, the suitable conditions for production of acerola vinegar were determined to be pH 6.5, 20°Brix, 106 cells/ml, as well as 4.0% (v/v) of ethanol added to acerola juice. Moreover, a temperature of 35°C was found to be suitable for fermentation in both 100 ml and 2 litre working volumes. Total acid concentrations of 5.45% (w/v) and 4.90% (w/v), respectively, were achieved after 4 days of fermentation. Acid concentrations of 5.40% (w/v) and 4.70% (w/v) were obtained at 37°C after 5 days of fermentation in volumes of 100 ml and 2 litres, respectively. At pilot-scale fermentation of 20 litres at 37°C, acid concentration of 3.68% (w/v) was achieved after 5 days of fermentation.

26-32

Authors: Van Dang Tran*, Dong Tran, Marc Oudjene

Timber is highly anisotropic. It behaves differently in diverse directions. Tension and compression perpendicular to the grain present a low strength with respect to the ones parallel to the grain. To compensate for the lack, the self-tapping screw is an excellent choice for reinforcing the timber. This paper focuses on the notched timber beam with the experimental and numerical results. In the first part, the experimental results of the unreinforced notched beams and the screw reinforced notched beams under bending load will be presented. The second part describes a numerical study in which a 3D finite element (FE) model and a fast FE model of the notched beam reinforced by a self-tapping screw are realised. In particular, the fast FE model is simplified with the use of the screw’s model as a beam element having one translational degree of freedom. This model not only presents a good result in comparison with the experiment as well as the 3D FE model but also requires six times less computational times as compared to the 3D FE model.

37-41

Authors: Quoc Sinh Nguyen*, Chi Bao Nguyen, Thanh Long Le, Sy Vuong Ho, Thi Diem Huong Nguyen, Van Quoc Bao Vo, Van Toan Nguyen

Gamma(γ)-Aminobutyric acid (GABA), which provides a variety of health benefits, is an important bioactive component of tea (Camellia sinensis). A special tea product, GABA tea, contains high levels of γ-Aminobutyric acid which is produced by anaerobic fermentation. Tea fermentation is affected by a number of factors, including anaerobic conditions (vacuum, and the kind of gas used), temperature, and the duration of anaerobic fermentation. In this study, the levels of bioactive compounds in tea leaves produced by fermenting fresh tea leaves in nitrogen gas are investigated. The fermentation was conducted at different temperatures: room temperature (28±2), 35, and 40ºC; and for each temperature setting, the fermentation times were 6, 9, 12, and 15 hours. The results show that the GABA content increased significantly with fermentation temperature. The most appropriate temperature and time for the anaerobic fermentation to produce GABA and other bioactive compounds were, respectively, 40ºC and 9 hours. Under these conditions, GABA content reached the maximum value (202.77 mg/100 g of dry tea); that of total polyphenols was 22.30% of dry matter (DM); caffeine was 2.39% DM; and soluble solids were 36.25% DM.

48-54

Authors: Tran Thi Thuy Ha, Thai Thi Lam, Nguyen Thanh Huyen, Nguyen Xuan Canh*

To isolate and characterise free nitrogen-fixing bacteria, we collected randomly soil samples from different areas of Ha Noi. Nitrogen-fixing bacteria were isolated using Burk’s medium without nitrogen mineral supplement. The ammonia (NH4+) synthesis of these bacterial strains after biomass production was determined by means of Nessler reagent. Based on the results of isolation, we observed and evaluated colony and cellular morphology, pigment production, and metabolic activities of twenty-five isolates. Among the isolated bacteria, two bacterial strains (6.2 and 8.2) with high NH4+ concentration in the cultural medium were selected as the best strains for nitrogen-fixing ability. The optimal pH and temperature for their growth and nitrogen fixation are 7.0 and 30°C, respectively. Growth is best favored in the presence of sucrose. We sequenced the 16S rRNA gene of selected strains and compared the homology of them in GenBank using BLAST search. The result of the comparison shows that the 6.2 and 8.2 strains have 99% and 100% 16S rRNA-sequence similarity with Pseudomonas sp. and Bacillus sp., respectively

59-66

Authors: Hanh Dung Thai, Van-Tuan Tran*

The filamentous fungus Aspergillus oryzae, also named as the koji mold, is a preferred host for enzyme production due to its prominent secretion ability into the culture medium. Fungal laccases are widely used in different industrial processes, especially in removing environmental pollutants. Up till now, little was known about the roles of some laccase genes from the black mold Aspergillus niger. The McoD laccase gene from A. niger includes three exons interrupted by two short introns. The respective coding sequence of the gene is computationally predicted to encode a secreted laccase of 563 amino acids. In this study, a binary vector carrying the A. nigerMcoD gene was successfully constructed for heterologous expression in the edible fungus A. oryzae. This vector was transformed into A. oryzae using the Agrobacterium tumefaciens-mediated transformation method. The transformation efficiency was relatively high in two different auxotrophic A. oryzae strains, including RIB40∆pyrG and VS1∆pyrG. All the tested transformants possess in their genomes the construct for expression of the McoD laccase gene under control of the strong A. oryzae amyB promoter. The selected transformants were examined for the laccase activity using the ABTS substrate. The results showed that in comparison to the wild-type fungal strains, the transgenic strains could oxidise ABTS to form the sea green colour, which can be seen directly on the agar plate

74-80

Authors: Le Anh Tuan*

The Vietnamese Mekong river delta (MD) is recognised as the biggest agriculture and aquaculture region of Vietnam. The MD plays an important role in ensuring food security for the country. The MD also has many sensitive ecosystems reliant on the ecology of the Mekong river basin. However, during the last decade, many electricity generation plants, both renewable and non-renewable power projects, have been built and some will be built in the near future in the MD. These energy plants’ construction and operation may prove to be a challenge to the national energy strategy.This paper is a monograph review of two sides of energy sector industrialisation in the MD with a focus on ‘green’ and ‘grey’ socio-economic development (as ‘xanh’ and ‘xám’ in Vietnamese respectively). ‘Green’ energy is understood as the electricity generated from inexhaustible sources and known as renewable energy. It emits fewer greenhouse gases and causes less harm to habitats in comparison to traditional fossil fuels and hydropower. ‘Grey’ energy is another word for non-renewable energy or polluting energy, which can have negative effects on human health, environment, and climate. This paper finds that the MD’s energy development plans at present might not be as ‘green’ as expected, due to more ‘grey’ power plans in the planning pipeline. This paper also considers an outlook on energy prices and impacts on long-term sustainable development of the MD.

89-96

Authors: Mau Nguyen-Dang*, Truong Nguyen-Minh, Hidetaka SASAKI, Izuru TAKAYABU

This article presents analyses of changes in the seasonal characteristics of the far future climate (2080-2099) across Vietnam as projected by the Non-Hydrostatic Regional Climate Model (NHRCM) in terms of the RCP 8.5 (Representative Concentration Pathways 8.5) scenario. The results show significant changes in seasonal rainfall in Vietnam compared with the 1982-2003 baseline period. Specifically, the June-August rainfall is projected to increase in South Central (SCVN), Central Highlands (CHVN), and South Vietnam (SVN), but to decrease by approximately 50% in North Central (NCVN) and off the Central coast. In the September-November season, the NHRCM detects an increase in rainfall of about 50% in North Vietnam (NVN) and CHVN. The increase and decrease in rainfall are due to the convergence and divergence of moisture flux that might be associated with the westward expansion of the Northwestern Pacific High Pressure in the far future

3-6

Authors: Thi Thuy Duy Nguyen, Hoang Phuong Tran*

The rapid and green procedure for the Knoevenagel reaction between aromatic aldehydes and diethyl malonate was developed by using 1-butyl-3-methylimidazolium hydroxide, [Bmim]OH, as an efficient catalyst. The condensations showed good yields with a wide range of aromatic aldehydes in solvent-free condition and short reaction times. [Bmim]OH was easy to recover and could be reused several times without significant loss of catalytic activity.

16-23

Authors: Van Quang Le*, Quang Minh Do, Minh Duc Hoang, Hoc Thang Nguyen

In this study, the alkaline solutions (NaOH) with concentrations from 1M to 18M, red mud (RM) and silica fume (SF) were used as reactors in geopolymer reactions. RM contains 7.40% SiO2 and 13.65% Al2o3and SF has 94.50% SiO2, but only the active oxides can participate in the geopolymer reactions. The activity of the oxides was investigated by determining the compressive strength of the samples under different curing conditions. The characteristics of the geopolymer samples were determined by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA)/differential thermal analysis (DTA) and nuclear magnetic resonance analysis (NMR). The experimental results indicate that active silica mainly exists in SF. In the structure of geopolymers, the silicon can bond directly with each other (Si-Si) or be linked through ‘bridging’ oxygen (Si-O-Si) to form independent polymer chains, while aluminium atoms can only replace the silicon atoms in Si-O-Si polymer chains to form Si-O-Al instead

30-43

Authors: Hieu T. Nguyen*, Huong T.T. Le, Liem T. Nguyen, Hua Lou, Thomas La Framboise

Next-generation sequencing (NGS) is a high throughput sequencing technology, which has revolutionized both basic and clinical research of the human genetic disorders. This technology is also called massively parallel sequencing (MPS) due to its ability to generate a huge amount of output data in a cost- and time-effective manner. NGS is widely utilized for different sequencing applications such as targeted sequencing (a group of candidate genes), exome sequencing (all coding regions), and whole genome sequencing (the entire human genome). With NGS, a variety of genomic aberrations can be screened simultaneously such as common and rare variants, structural variations (amplifications and deletion), copy-number variation, and fusion transcripts. NGS technologies combined with advanced bioinformatic analysis have tremendously expanded our knowledge. On the one hand, the basic research area involves direct use of NGS to identify novel variations and determine human disease mechanisms. On the other hand, clinical research is being advanced by high-throughput genetic tests with high resolution and clinically relevant genetic information for molecular diagnoses of human disorders. In this communication, we introduce NGS technologies and review a few key areas where NGS has made a significant impact, with an emphasis on the application of NGS to the identification of the molecular bases of human genetic diseases.

51-55

Authors: Ngo Tat Trung*, Dao Thanh Quyen, Phan Quoc Hoan, Thirumalaisamy P.P. Velavan, Le Huu Song*

Background/aims: It has been shown that quinolone resistance arises due to mutations in the quinolone resistance-determining regions of the drug targets. This study aimed to optimise a multiplex PCR assay to track plasmid-mediated low-level quinolone resistance profiles.Subjects and methods: A multiplex PCR-based-method in which the primers were already established by our team. About 44 samples were collected from 44 patients who enrolled in this study by using surgical site infection (SSI).Results: By targeting the conserved domains of qnrA, qnrB, qnrS and the qnrVC gene families, the primer number was reduced significantly to only four pairs in one multiplex PCR. Using multiplex PCR, 3/44 SSI samples were found to be carrying fluoroquinolone-resistance genes (qnrA, qnrB, qnrS, qnrVC).Conclusion: A multiplex PCR for detecting pathogens as well as identifying quinolone resistance genes all in one reaction was successfully established

57-67

Authors: Van Canh Doan, Duc Nhan Dang*, Kien Chinh Nguyen

The origin and chemistry of the groundwater in the middle Pleistocene (qp23), lower Pleistocene (qp1), upper Pliocene (n22), lower Pliocene (n21), and the Miocene (n13) in the Mekong river delta (MKRD) were investigated by using isotopic and geochemical techniques. The origin of the groundwater was evaluated based on the composition of the water stable isotopes (d2H and d18O) in the local precipitation, in water from the rivers system, and in the groundwater samples. The hydraulic interaction between the surface water and the groundwater as well as between the aquifers was assessed by a statistical treatment for the mean and standard deviation of the d18O signature and based on the 14C-ages of the water samples taken from different aquifers. The salinization of groundwater in the deep aquifers was investigated using the d18O signature combined with the geochemical composition of the water samples. It was revealed that the groundwater in the deep aquifers in the MKRD could be divided into two groups. The first group is fresh and represents the regional precipitation with the long traveling time ranging from older than 100 years to older than 40 ka BP (kilo years Before Present). The second group is the regional precipitation that is recharged from the remote areas mixed with the seawater. Statistical treatment with the mean d18O using the Mann-Whitney test showed that the water from the Mekong river system did not or very weakly recharged the deep aquifers. The groundwater in the deep aquifers in that region was likely to be connate, so that fresh groundwater resource in the region seemed to be limited. The chemistry of the groundwater in the study region is controlled by the incongruent dissolution of the Mg-calcite as well as sulfate and iron oxy-hydroxide reductions by organic matters presented in the aquifer sediment. The groundwater in the deep aquifers in the MKRD from some locations was saline, but the salinity in most aquifers was thought to result from the migration of saline water entrapped in the marine sediment pores to the fresh water in the aquifers. Meanwhile, in other locations, the salinity was suggested to result from the salt intrusion due to the over-abstraction rate, as it was evident from the d18O vs. [Cl-] relationship, or due to the up conning of saline water from the deeper aquifers to the upper ones. Particular measures must be developed for the better management of groundwater in the MKRD to ensure a sustainable resource of freshwater being supplied to the local population in future

73-77

Authors: Lam Nguyen, Xuan Thi Trinh, Hien Trinh, Dang Hung Tran, Cuong Nguyen*

The development of next-generation sequencing tech-nologies has helped sequence large genomes easily, producing a huge number of short-reads - small frag-ments of DNA. Despite the existence of many developed alignment tools, mapping short-read datasets to the reference genome, a crucial step of genome analysis, still remains a challenge. In this study, we develop a short-read alignment program, BWTaligner, based on the Burrows-Wheeler transform compression - exact and inexact matching. We tested it on the paired-end read data simulated from chromosome 9 of the rice genome to compare the alignment and single-nucleo-tide polymorphism (SNP) calling between our aligner and BWA - the preferred alignment program. The re-sults showed that the BWA delivers higher recall and F-score, while BWTaligner has better precision in high coveragedepth

84-91

Authors: Van Doanh Vu*, Ha Phong Doan, Thi Thu Trang Bui

Nam Dinh province is located in the Red river delta with a relatively flat terrain. The North East of Nam Dinh is bordered by the Red river and the southwest by the Day river and has a coastline of approximately 80 km. Given the geographical location, Nam Dinh has favourable conditions for agricultural and aquaculture production. Climate change creates a large number of potential risks for Nam Dinh. This includes sea level rise, typhoons, flood tide, etc. According to the climate change and sea level rise scenario in 2016, if the sea level rises by 100 cm, the flood risk area in coastal districts such as Hai Hau would be 67.34%, Giao Thuy 64.6%, Nghia Hung 81.61% and Xuan Truong 59.3% [1]. According to the monitoring data from Vietnam Institute of Meteorology, Hydrology and Climate Change (IMHEN), the salinity intrusion area due to sea level rise is likely to widen, which degrades and affects the area of the mangrove ecosystem [2]. In addition, the sea level rise may reduce the resilience of irrigation system due to the changes in estuarine and coastal dynamics such as water levels, flows, waves, etc. Through synthesising the local and international guidelines and in combination with expert consultation and field surveys, this paper develops an assessment procedure for sea level rise that causes economic damage to agricultural land use in order to quantify the impact of sea level rise in 4 coastal districts of Xuan Truong, Giao Thuy, Hai Hau and Nghia Hung in Nam Dinh province.

3-16

Authors: Sum Nguyen

Let Pk the graded polynomial algebra F2[x1,x2,...,xk] with the degree of each generation x1 being 1, where F2 denote the prime field of two elements, and let GLk be the general linear group ober F2 which acts regularly on Pk. We stydy the algebraic transfer contructed by Singer [[1] using the technique of the Prtersin hit problem. This subspace of F2x.aPk consisting of all the GLk-invariant classes of degree d. In this paper, by using the results on the Peterson hit problem we prevent the proof of the fact that the Singer algebraic transfer is an isomorphism for k<=3. This result has been proved by Singer in [1] for k<=2 and by Boardman in [2] for k=3. We show that the forth Singer tranfer is also an isomorphism in certain internal degrees. This results is new and it is different from the ones Bruner, Ha and Hung [3], Chon and Ha [4], Ha [5], Hung and Quynh [6], Nam [7].

23-27

Authors: Hung Viet Pham*, Thi Kim Trang Pham, Viet Nga Dao

Arsenic contamination in groundwater and its effect on human health has been a growing concern over recent decades. Some of the most severe incidents occurred in South and Southeast Asia, including the Red river delta, Vietnam. The highest concentration of arsenic found in the Red river delta was 810 μg/L, 16 times higher than the standard guidelines given by WHO for levels of arsenic concentration in groundwater (50 μg/L). However, the contamination levels were not uniform in the whole area. The arsenic levels might be affected by natural factors such as the characteristics of the aquifer, the chemical composition of groundwater and by human activities such as the exploitation of groundwater in the urban and industrial areas or irrigation in rural areas. Due to the complex mobilisation of arsenic in sediment and groundwater, questions remain about arsenic distribution, which are yet to be answered and are in need of further study.

38-41

Authors: Sang Ngoc Nguyen*, Viet Quoc Tran, Quang Van Vu

Idiopathic nephrotic syndrome (INS) is a major manifestation of chronic idiopathic glomerulonephritis and a common disease in children. The cause and pathogenesis of the disease have not been clarified so far. The treatment is usually a long-term process, from a few months to several years, even decades, including the period of hospitalisation, outpatient treatment period and follow-up period after treatment. The INS patients are negatively affected by the disease and its treatment process. The aim of this study is to assess the health-related quality of life (QOL) of children with INS according to clinical types in Haiphong Children’s Hospital. Object: Describe some factors related to the QOL of children with INS. Subjects:71 patients diagnosed with INS, who are being monitored and treated at Haiphong Children’s Hospital from 10/2015 to 05/2016. Methods: Prospective studies, descriptive cross-sectional. QOL of the patients is assessed by the PedsQL 4.0 scale; the higher score shows that the lower QOL. Results: The general QOL score of children with INS (21.24±13.91) was higher than normal children (16.98±10.20). Children with steroid-resistant INS have a higher score (31.62±14.32) than children with steroid-dependent (20.57±9.08) and responsive INS (14.58±6.83). The QOL score of children with one of the symptoms Cushing’s face, hirsutism or acne are significantly higher than children without the corresponding symptoms. Children who finished their treatment had a lower score (15.47±7.42) than children being treated (21.33±10.23). The average QOL score has a linear correlation with the duration of INS. Conclusion: The general QOL of children with INS substantially declined compared with that of healthy children. The QOL of children with steroid-dependent and resistant INS is lower than that of the children with steroid-responsive type. The QOL of children with one of the symptoms Cushing’s face, hirsutism or acne is significantly lower than that of children without the corresponding symptoms. The QOL of children who completed treatment is higher than the group being treated. The longer the duration of treatment, the more the children’s QOL declined

46-49

Authors: Thi Ngoc Lan Nguyen, Huu Quan Nguyen, Thi Hanh Nguyen, Thi Mai Thu Lo, Hoang Mau Chu*

Jewels of Opar (Talinum paniculatum) is a herbaceous plant known for its highly medicinal value. This medicinal plant is listed in the Red List of Vietnam’s medicinal plants and in the handbook of Vietnam’s medicinal plants, both documents warranting its necessity for protection. Jewels of Opar contains bioactive substances such as phytosterols, saponins, flavonoids, tannins, steroids, and many other inorganic substances. Jewels of Opar plants collected in Thanh Hoa, Vietnam, are tree-like herbs, their green trunks grows straight up and then branch out. The shapes of the leaves vary; they are generally oval or ovate-oblong in shape, with wavy veins. The flowers of this tree have five reddish purple wings, two sepals, more than ten stamens, and a spherical ovary. Both the fruits and their seeds are small and black. Tuberous roots are cylindrical with many small roots, and the tubers themselves are sweet and spicy. Internal transcribed spacer (ITS) region isolated from T. paniculatum plants in Thanh Hoa, Vietnam is 643 bp in length. Based on the nucleotide sequences of the ITS region and using the basic local alignment search tool (BLAST) in theNational Center for Biotechnology Information (NCBI), the Jewels of Opar samples collected in Thanh Hoa, Vietnam were determined to belong to T. paniculatum species, Talinumgenus, Portulacaceae.

68-72

Authors: Thi Thu Do*, Thi Hien Hoang, Thi Anh Thu Do*, Quang Ngan Pham, Hong Thai Giang, Ha Trung Bui, Trung Tran, Truong Giang Ho

In this research, we present the ZnO nanorods synthesized through the simple route of the hydrothermal method. The ZnO nanorods were developed through the application of only zinc acetate Zn(CH3COO)2 and ammonia solution, NH4OH, in the hydrothermal process at 1500C for 10 hours. The size of the ZnO nanorods was defined as approximately 300 nm in diameter and 1-2 μm in length. The fabrication of sensors was achieved through drop-coating of synthesized ZnO nanorods on Al2O3 substrates integrated with Au electrodes. Subsequent to the process of sintering done at 500oC for different durations, ZnO nanorod-based sensors were investigated when exposed to NO2 gas (1.5, 2.5, and 5 ppm) at room temperature under continuous UV-LED (385 nm) illumination. The correlation between NO2gas sensing performance and the optical property of the ZnO nanorods is discussed in detail. Herein, the defect concentration, particularly `in the surface region of the ZnO nanorods could be modified through sintering, and this indicates its importance in the reduction of response-recovery times and enhancement of high sensitivity to NO2 gas.

83-89

Authors: Van Khiem Mai*, Truong Minh Ha, Quang Nam Pham

The ability of simulation on large-scale global circulation, as well as temperature and rainfall over Vietnam area with different sea surface temperature (SST) boundary conditions by the Conformal-Cubic Atmospheric Model (CCAM) is presented in this paper. CCAM is a global circulation model, which may be used in the variable resolution mode to function as a regional climate model. That is, the model may be integrated with high horizontal resolution over the area of interest, with the resolution gradually decreasing as one moved away from the area of interest. The results show that model has well predicted large global circulation all over the global compared to Climate Forecast System (CFS) analysis data, two experiment of CCAM model were not too different with CFS model. For detailed forecasts in Vietnam region, the CCAM model will capture surface temperature compared to observed data with correlation coefficient above 0.85. Forecast temperature of CCAM tends to be lower than observed data, but the magnitude of error is not so much. Comparing the two experiments, forecast skill of CCAM_IRI is slightly better than CCAM_CFS. For rainfall, CCAM generally tends to forecast rainfall higher than observation data in summer and lower in winter. The predictive skill of rainfall in short lead times is better than others and skill of CCAM_CFS is significantly better than CCAM_IRI