Vietnam Journal of Science, Technology and Engineering

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.