Vietnam Journal of Science, Technology and Engineering

8-14

Authors: Van Hung Pham*, Kim Khanh Nguyen, Thi Lan Phi Nguyen

Heat-moisture treatment, a physical modification method of starch, causes changes in the internal structure of starch and thereby produces resistant starch (RS). In this study, the heat-moisture treatment conditions (moisture content, heating temperature, and incubation time) was optimized to maximise the RS contents of the treated sweet potato and yam starches, using the Box-Behnken design and response surface analysis. The predicted maximised RS content of the treated sweet potato starch (43.9%) was obtained under optimal conditions of 34.76% moisture content, heating temperature of 100.11oC, and incubation time of 6.01h; the predicted maximised RS content of the treated yam starch (36.8%) was obtained under optimal conditions of 30.06% moisture content, heating temperature of 109.68oC, and incubation time of 6.59h using a quadratic model within the range of various process variables. The experimental RS contents of the treated sweet potato and yam starches obtained under optimal treatment conditions were 42.4% and 35.4%, respectively; this confirms that the models were valid and adequate because the predicted data and experiment data did not differ significantly. The results also indicate that the RS contents of the treated sweet potato starch were significantly higher than that of the treated yam starch. As a result, both starch structure and treatment conditions were determined to significantly affect the formation of RS in the heat-moisture treated starches.

19-24

Authors: Manh Hai Vu*, Quang Dang Bui, Quoc Hung Nguyen, Van DZung Nguyen

Perennial fruit crops generally and temperate fruits in particular make an important contribution to the sustainable development of the socio-economy in the northern mountainous region of Vietnam where the living standard of local farmers - 40% of whom are minorities from 30 groups - is still low (about 70% of the average of the country as a whole), though significant assistance has been made by the government and a slowly developed socio-economy has been recorded. It is obvious that proper temperate fruit production not only benefits local growers but also protects the environment in a significant way. Recent results concerning varietal selection and cultivation technologies for temperate fruits are summarized in this paper and some of the principal solutions, including proper planning, breeding programme enhancement, the establishing of production and value chains, and the training of skillful technicians and producers that is aimed at promoting production in the future, are also proposed.

31-38

Authors: Thi Minh Ly Nguyen*, Quoc Dang Quan, Thi Bach Hue Nguyen, Hoang Chuong Nguyen

Lung cancer is one of the quickest and most fatal diseases and is divided into two types: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Approximately 50% of NSCLC patients harbour mutations in the epidermal growth factor receptor(EGFR) gene, spanning from exon 18 to exon 21, which are responsible for the tyrosine kinase domain of the EGFR protein. Currently, gefitinib and erlotinib are two drugs inhibiting EGFR which are used in the treatment of lung cancer. The indication for use of these drugs depends on the mutation status of EGFR. Resistance to treatment with these two drugs has been found with mutations in exon 20; however, mutations in exon 18, 19, 21 benefited from the same treatment. Therefore, we built a molecular protocol for detecting mutations in exon 21 of EGFR in NSCLC patients in Vietnam which, in this study, is based on the real-time polymerase chain reaction high resolution melting (PCR HRM) technique. We successfully designed pairs of primers for the real-time PCR HRM technique to detect mutations in exon 21 and for the Sanger sequencing method to confirm the real-time PCR HRM results. We also investigated the optimal concentration of MgCl2 for the real-time PCR HRM protocol. Performance characteristics of the real-time PCR HRM protocol were evaluated in terms of specificity, limit of detection, repeatability, and it showed good results. Finally, we applied the molecular protocol to 172 clinical samples and compared these with the Sanger nucleotide sequencing method and the peptide nucleic acid (PNA) clamping method. The results of the comparison demonstrate that the molecular protocol constructed for detection of exon 21 mutations can be used in the treatment of NSCLC patients.

45-51

Authors: Thi TrangLe*, Quang Doc Luong, Thi Thu Ha Vo , Van TuNguyen

Studies of the composition and density of phytoplankton and the water quality of Nhu Y river were conducted over six months (March to August 2011). Phytoplankton samples were collected by filtration and immediately preserved in Lugol’s solution. The phytoplankton species composition recorded 117 species belonging to six divisions: Cyanobacteria (24 taxa), Bacillariophyta (14 taxa), Chlorophyta (45 taxa), Euglenophyta (31 taxa), Cryptophyta (2 taxa), and Dinophyta (1 taxa), of which Chlorophyta and Euglenophyta were dominant in terms of species numbers. The total phytoplankton density fluctuated from 110,146 to 5,964x103individuals/litre and Cyanophyta were dominant in terms of individual density. The algal genus pollution index (Palmer index) ranged from 30 to 41, indicating that the water was highly organically polluted, and the Shannon-Weiner index results of 0.66-2.92 showed moderately to heavily polluted water. With values for the Diatomeae index of more than 0.2, the quality of the eight sites during the period of the study showed that the aquatic environment was eutrophic. Phytoplankton and their indexes are useful tools for assessing water environment quality.

59-65

Authors: Khac Tam Pham, Thu Chang Nguyen, Thi Ha Luong, Phu Hoang Dang, Dinh Chi Vu, Thanh Nhan Do, Thi Cam Mien Phi, Duc Bach Nguyen*

Green microalgae Haematococcus pluvialis is best known for astaxanthin production. The cultivation of H. pluvialis involves two main phases, namely green vegetative stage and cyst stage with astaxanthin accumulation. In fact, the growth of H. pluvialis in the vegetative stage is one of the most important parts in the entire cultivation process. The aim of the study is to investigate the influence of temperature, inoculum size, CO2 concentration and light emitting diodes (LEDs) on the specific growth rate, cell density and dry weight of H. pluvialis in the vegetative stage. Results indicated that the temperature from 25 to 280C and the inoculum size from 3×104 cells.ml-1 were suitable for the growth of the studied strain. Illumination with red light LEDs (630 nm) at 80 μE.m-2.s-1, the highest specific growth rate (μ) was 0.197 day-1 and the maximal density was of 2.87×105 cells.ml-1. A concentration of 5% CO2 (v/v) was the optimal dose for the growth of this strain. Under the condition of both 5% CO2 and illumination with red light LEDs at 80 μE.m-2.s-1, the specific growth rate was 0.242 day-1 and the cell density was 4.28×105cells.ml-1. Illumination with only blue LEDs (430 nm) at 120 μE.m-2.s-1 stimulated the astaxanthin accumulation with a maximum content at 2.36 μg.ml-1.

71-77

Authors: Thi Hong Nguyen

The quality of river water is influenced by two factors: nature and man. The aims of this paper are to determine the influence of anthropogenic sources of pollution on water quality, by assessing integrated measurements from use of the Pollution Index (PI) of Indonesia and diverse statistical techniques, including one-way analysis of variance (ANOVA) and ArcGIS. In this study, 10 physicochemical parameters for the determination of water quality, from surface water taken the Thi Vai river, are examined: dissolved oxygen (DO), biochemical oxygen demand (BOD5), chemical oxygen demand(COD), ammonium (NH4+-N), phosphate (PO43--P); total dissolved solids (TSS), pH, nitrite (NO2-), nitrate (NO3-), total coliforms, and fecal E. coli. The samples were collected from seven monitoring sites, for assessing spatial and temporal water quality, in the three years 2015 to 2017.The findings revealed that water quality index values within the study area showed a significant pollution level for nitrite, and fecal E. coli. Water quality was detrimental at the sites TV2, TV3, and TV4. A further finding was that there was significant variation recorded between the two methods of measuring PI - that of the Ministry of the Environment, Indonesia, and that of Vietnam. Finally, this integrated technique could, it is suggested, be an effective approach for communicating information on water quality for sustainable waste management in Thi Vai river.

82-88

Authors: Van Dai Nguyen*, Tien Anh Do, Kim Tuyen Nguyen

In addition to surface water, groundwater is an essential source of water for agriculture, industry, and living in Ha Tinh province (central Vietnam). However, overexploitation and unreasonable use of groundwater has put this resource at risk of endangerment and pollution. In the coastal areas especially, the impact of climate change and the rise in sea-level has increased the risk of salt-water intrusion into groundwater. In this study, the groundwater system model (GSM) is applied to simulate the intrusion of saline water in different climate change scenarios in the coastal area of Ha Tinh province. The result reveals that saline intrusion into groundwater is becoming more complex and is a rising trend in climate change scenarios RCP4.5 and RCP8.5.