Vietnam Journal of Science, Technology and Engineering

3-7

Authors: Thuy Lan Chi Nguyen, Thi Thu Huong Dinh, Thi Cam Tu Dang, Anh Duc Pham*, Thanh Tam Nguyen, Thi Tu Quyen Huynh, Nhat Phuong Tran

The Tien Giang province is located in the tropical climate zone of theMekong delta.In this study, the diversity of zooplankton and benthic macroinvertebrates were investigated in the estuarine coastal waters of the Tien Giang province of southern Vietnam. 10 sites were observed over six time periods from 2019 (March, May, September, and November) and 2020 (March and May). The taxonomic richness, abundance, and diversity index were applied to this biodiversity assessment of the zooplankton and benthic macroinvertebrates. The results of the assessment showed that 30 species of zooplankton and 18 species of benthic macroinvertebrates were found in the study area. The density of zooplankton at each site ranged from 6 to 93 individuals/sample, while the density of benthic macroinvertebrates at each site fluctuated from 3 to 12 individuals/sample. The Shannon-Wiener diversity index of zooplankton fluctuated from 1.02 to 1.58 and that of the benthic macroinvertebrates ranged between 0.91 and 1.33. Besides, statistical analysis showed that the species richness of the zooplankton and benthic macroinvertebrates positively correlated with their density (r=0.2283-0.6423). This study contributes to the diversity information of zooplankton and benthic macroinvertebrates, which can be used to position the sustainable management ofnatural resources and evaluate the natural feed sources for aquaculture in this estuarine area.

18-22

Authors: Thi Cam Trang Truong*, Takaomi Kobayashi

Pectin extracted from dragon fruit peels was used to prepare pectin-based membranes by mixing with the plasticized agent polyethylene glycol (PEG) at pectin to PEG ratios of 5:1, 3:1, and 1:1. SEM images showed the resulting bioplastic films had a transparent yellowish surface without pores or cracks. The water content of the bioplastic films was 29.17, 48.61, and 59.72% for the 5:1, 3:1, and 1:1 ratios, respectively. This showed that the increase in PEG concentration made the bioplastic films weaker and more hydrophilic. The tensile strength of films was 5.0, 4.9, and 2.5 N/mm2 and the value of optical transmittance was 18, 19, and 24%, for the 5:1, 3:1, and 1:1 ratios, respectively. The significant decrease in tensile strength is attributed to the high concentration of PEG, which lead to the clustering in the material’s structure. Therefore, these bioplastic films are applicable to the highly suitable and stable operations of packing materials in the food and medical industries.

30-35

Authors: Diep Yen Nga Dang*, Hong Nhung Vuong, Thi Tam Nguyen, Thi Thanh Thao Phan

This study was conducted to preliminarily assess microbial contamination of the indoor air inside classrooms at the University of Science - Ho Chi Minh city. At the same time, this study demonstrates the scientific basis of air quality assessment in a school environment and develops long-term direct or indirect solutions to protect the environment and ensure student health. In this project, sampling and quantitative analysis were performed to identify the airborne bacteria and fungi. Samples were collected from classrooms over a period of 4 months (03-06/2019) according to Koch’s sedimentation method. The sampling plates were placed 1 m above the floor and the sampling time was 15 min. The colonies were counted after 24-48 h of incubation at 37±1oC for the bacteria and 70-120 h at 25±1oC for moulds. The results showed bacterial and fungal densities ranging from 359.6-2,427.3 CFU/m3 and 106.1-928.9 CFU/m3, respectively. The bacterial density was 2-3 times higher than the fungal density for all survey sites likely because the origin of these microorganisms is human activity. In addition, the density of bacteria and fungi in the air were also affected by weather and environmental factors. 5 isolated bacteria were identified as Bacillus atrophaerus, Acinetobacter baumannii, Bacillus pumilus, Bacillus subtilis, and Bacillus cereus. The fungi isolates included Aspergillus tamarii, Aspergillus niger, and Fuligo septica. They were all related to human and plant diseases.

43-48

Authors: Thi Hoang Yen Tran, Thanh Thai Tran, Xuan Quang Ngo, Thanh-Luu Pham

Benthic algal assemblages are considered effective indicators of environmental change because they sensitively respond to a variety of environmental conditions. This study aims to investigate the relationship between the benthic algal community and nutrient variables in sediment using Spearman’s correlation and linear regression analysis. A total of 27 genera of benthic algae were recorded during the study period where cyanobacteria and diatom were the two dominant groups. Several species belonging to Achnanthidium, Luticola,Lyngbya, Navicula, and Phormidium sensitively responded to nutrient levels and were used as bioindicators. Multiple stepwise linear regression revealed that ammonium (NH4+) and total nitrogen (TN) positively correlated with several indices of the benthic algae assemblage. This preliminary data set demonstrates the use of benthic algae as precise biological indicators for a measure of the ecological integrity of an aquatic ecosystem and contributes to the further study of benthic environments in tropical regions.

60-64

Authors: Thi Thu Dung Tran*, Thanh Thoang Ngo, Ngoc Tuyen Nguyen, Bich Chau Tran, Minh Hoang Truong

Sediment-water interaction is a complicated process; hence, it is essential to know the potential mobility of an element from sediment to the aquatic environment. In this study, the potential mobility of phosphorus (P) in sediment from Can Gio was investigated. Three single extractions were applied including a mild salt (NH4Cl), an acid (HCl), and a base (NaOH) each representing different environmental factors during sediment resuspension. Other geochemical parameters were also determined. The total amount of P in the sediments varied from 320.41 mg/kg to 668.22 mg/kg in five sampling sites. The general range of potential mobility of P decreased as follows: P-mild (3.70-13.13 mg/kg) < P-base (36.80-78.53 mg/kg) < P-acid (133.85-380.57 mg/kg). Although P-acid was not easily released to the environment, its relatively high concentration can affect the aquatic environment when the environment becomes acidic.

71-76

Authors: Thi Anh Thi Nguyen*, Ngoc Han Bui

According to Decision No. 711/QD-TCMT of the Ministry of Natural Resources and Environment, the water quality index (WQI) formula has been adjusted toward localisation, particularly, for the Nhue Day and Cau river basins. In this work, the WQI formula was amended by adjusting the weights of the components of surface water quality. This is an advance forward toward enhancing the effectiveness of local environmental management so that local economic development conditions are shaped according to its own potential and in accordance with the natural characteristics and culture of the regions. Based on surface water quality data from 2012 to 2019 in Tien Giang and the theory of fuzzy entropy weighting to identify component weights, this study adjusted the WQI formula in accordance with natural conditions as well as special characteristics of the socio-economic development of Tien Giang. Finally, a zoning map of surface water quality in the province was set up

87-94

Authors: Tran Huynh Duy, Duong Thi Thuy Nga*

Nowadays, air pollution is a serious problem for the entire world, but especially in developing countries like Vietnam. For monitoring and managing air quality, scientists have successfully used different technologies such as predictive models, interpolation, and monitoring, however; these methods require a large amount of input data to simulate. Further, the results from spatial simulations are not detailed and have deviations from reality due to factors such as terrain changes, wind direction, and rainfall. Based on the physical index extracted from remote sensing images like radiation and reflection values, the aerosol optical depth (AOD) can be extracted. In this work, a regression equation is constructed and the correlation between the extracted AOD and measured PM10concentration is found. The results show that PM10 and AOD are best correlated with a non-linear regression equation. This work also shows that the concentration of PM10 in Ho Chi Minh city is distributed mainly along the outskirts of the city, which has many highways, industrial parks, factories, and enterprises.

3-9

Authors: Hue Thi Dao*, Tung Duc Vu

Building an integrated river delta basin and coastal management plan in the context of climate change requires suspended sediments data, which plays an important role and is the key component for understanding the hydrology regime in the delta region. Sediments are responsible for carrying a considerable amount of nutrients and contaminants. Most sediment discharge data is acquired by surveys/data collection activities or by mathematical modelling. However, these methods are costly, time-consuming, and complex. Therefore, in this study, the authors investigate the potential use of satellite observations (MODIS reflectance) to detect suspended sediment flux in the Red river delta (RRD) of Vietnam. The relationships between discharge (Q), suspended sediment concentration (SSC), and total load (L) collected from the three in-situ stations Son Tay station (ST), Thuong Cat station (TC), and Hanoi station (HN) in the RRD are determined by regression analyses of reflectance data (R) obtained from MODIS bands 1-2 (250-m resolution). The results present a close connection between the monthly average of SSC and R and a good statistical relationship between the monthly average of Q and R in HN. At TC and ST, a lower correlation was found compared to HN because of the cloud cover and the position where data was collection in the river. The coefficient of determination ranged from 0.11 to 0.40 for the R-SSC and R-Q relationships. A method of estimating SSC and L at a single point along the river using data from Q and R was proposed based on the relationship correlation results.

15-18

Authors: Nguyen Thanh Le*, Huu Giap Tran, Thi Kim Oanh Vu, Thuy Duong Pham, Ngoc Thuc Dinh, Anna Stojakowska, Bich Ngan Truong

Maesa membranacea A. DC. (Myrsinaceae) has been traditionally used for the treatment of fever and hepatitis. The phytochemical investigation of Maesa membranacea stems has led to the isolation of six compounds including kaempferol (1), (-)-epicatechin (2), betulinic acid (3), p-hydroxybenzoic acid (4), vanilic acid (5), and protocatechuic acid (6). The chemical structures of these compounds have been determined by nuclear magnetic resonance (NMR), mass spectrometry (MS) data, and by comparison with previously reported works. This is the first report of a chemical study on Maesa membranacea as compounds 1-6 listed above were found from the Maesa genusfor the first time.

26-32

Authors: Thi Tuyet Mai Phan*, Ho Viet Cuong, Pham Ngoc Lan

Carboxymethyl cellulose-graft-poly(acrylic acid-Sodium acrylate-acrylamide) SAPs have been prepared by the free-radical grafting solution polymerization of acrylic acid (AA) and acrylamide monomers (AM) onto carboxymethyl cellulose (CMC) in the presence of N,N′-methylenebisacrylamide as a crosslinker (MBA) and ammonium persulfate (APS) as an initiator. Various factors influencing the water absorbency of the polymer were studied. These include the weight ratio of APS, MBA, and CMC compared to the monomers. The optimal conditions were found as follows: 1% APS, 0.25% MBA, and 10% CMC (weight ratio to monomers). The maximum absorbencies for distilled water and 0.9 wt.% NaCl solution were 406 g/g and 69 g/g, respectively. The structure of the synthesized polymer was confirmed by Fourier Transform Infrared spectroscopy (FTIR). Additionally, the water absorption and water retention behavior of the polymer in soil were investigated. The results showed that this polymer could be employed as a suitable moisture-holding additive in soil for cultivation purposes.

38-44

Authors: Vu Thi Thu Nga*, Gilbert Teyssedre

Cable technologies have evolved in different ways for applications using high voltage alternating current (HVAC) and high voltage direct current (HVDC) over the last 40 years. Since the 1950s, mass-impregnated paper was progressively replaced by extruded insulation made of polyethylene and then cross-linked polyethylene (XLPE). The switch from paper insulation to extruded cables went on continuously while cables were designed with ever increasing voltage requirements. However, regarding space charge build-up and field redistribution, particularly at polarity reversal stages in thyristors, the behaviour of extruded cables under such DC stress is not fully understood. For this reason, material improvement, characterization, and modelling are still intensively researched for cables, accessories, and power conversion equipment. The weaknesses and methods used to simulate the characteristics of insulation are presented and compared in this work through the simulation results of the macroscopic and fluid model.

49-55

Authors: N.N. Quynh*, B.H. Hieu, N.N. Dang, N.H. Quang, To Vinh Cuong

n recent years, the construction of upstream reservoirs and the extraction and structural construction activities on the river banks and beds have caused downstream changes in river morphology and hydrological regime of the Red river system, which has especially accelerated from 2000 to 2018. These dramatic variations have significantly changed the morphological characteristics and relationship between the flow and morphology that are a fundamental parameter to evaluate the stability of the channels. In this study, the morphological characteristics and relationship between flow and morphology over some periods as well as under current conditions were analysed. This work provides basic river training parameters for studying river training planning of the Red river system in general and for the Red and Duong river sections in Hanoi in particular.

62-67

Authors: Ha Duc Chu*, Quynh Thi Ngoc Le, Yen Hai Thi Hoang, Thu Phuong Pham, Hong Viet La, Nguyet Minh Thi Nguyen, Anh Xuan Duong, Thao Duc Le, Linh Hung Le, Hoi Xuan Pham

SWEET (Sugars Will Eventually be Exported Transporter) proteins are well known to play pivotal roles in the growth and development of plants. Here, we report the presence of 43 members of the AhSWEET family in peanut (Arachis hypogaea) and determine their general characteristics including chromosomal localization, gene structure, and numerous physical and chemical features of the proteins. We found that the AhSWEET genes were unevenly distributed among the peanut’s 20 chromosomes. The AhSWEET proteins were hydrophobic with a grand average hydropathicity >0 while a majority of the proteins were basic with isoelectric points >7.0. Additionally, most of the AhSWEET genes contained 6 exons and 5 introns. The expression profiles of the AhSWEET genes were explored based on the previous transcriptome atlas. Interestingly, we found that the AhSWEET genes exhibited differential expression patterns across various organs and tissues during the growth and development of peanut plants. Our study provides a solid foundation of the AhSWEET gene family for further functional characterization of AhSWEET genes in the regulation of peanut growth and development

70-75

Authors: Vu Xuan Tao*, Tran Bao Tram, Nguyen Thi Hien, Thai Hanh Dung, Tran Van Tuan

Vietnam possesses an abundant and highly diverse resource of plants. Therefore, the search and evaluation of bioactive compounds extracted from these plants are a potential research direction to support developing products that improve human health. The purpose of this study is to assess the antifungal activity of some essential oils produced by materials harvested in Vietnam such asKing orange peel (Citrussinensis),lemongrass (Cymbopogonflexuosus), peppermint(Mentha arvensis), and betel leaf (Piperbetle). The antifungal effect of these essential oils was determined by the Kirby-Bauer disc diffusion technique. In addition, the antifungal properties of the essential oils were also assessed through their effects on the reproduction ofC. albicansand the spore germination, mycelium elongation, and sporulation ofA. fumigatus. The results demonstrated that all peppermint, lemongrass, and betel leaf essential oils showed antifungal activity againstC. albicansandA. fumigatus. Especially, betel leaf essential oil could perform antifungal activity at a low dilution concentration of 10% and could also inhibit the reproduction of C. albicansand the spore germination, mycelium elongation, and sporulation of A. fumigatus. Meanwhile, orange peel essential oil did not exhibit any antifungal properties.

83-89

Authors: Thuong Quoc Thinh, Truong Tran Nguyen Sang, Tran Quoc Viet, Le Thi Minh Tam, Nguyen Phuoc Dan, Emilie Strady,Kieu Le Thuy Chung*

Microplastic pollution has become a global issue in recent years. Since the early 2000s, scientists have investigated the occurrence of microplastics (MiPs) in the environment. While research on marine MiPs is more advanced at present, there are immense gaps of knowledge regarding continental MiPs. Airborne MiPs are one source of MiPs in the aquatic environment. In the scientific literature, there have been only three publications on presence of MiPs in atmospheric fallout. In developing countries, where plastic waste management is weak, studies on the presence of MiPs in this area are limited. This current study presents a preliminary assessment of the presence of MiPs in atmospheric fallout sampled from the Phuoc Hiep landfill, Ho Chi Minh city (HCMC). The results of this work show that MiP concentrations vary between 1,801 items m-2d-1 and 913 items m-2d-1 in the dry and rainy seasons, respectively.

3-6

Authors: Xuan Quan Cao*, Ngoc Dung Hoang, Hoang Luong Nguyen

The development of a luminance responsivity standard is central to the study of photometry and radiometry at the Vietnam Metrology Institute (VMI). Today, two methods are used to determine luminance responsivity. The first method uses an integrating sphere light source, also known as a luminous intensity standard lamp, and the second method compares the luminance responsivity value to that of a known standard photometer. Using these methods, it is possible to identify small uncertainties. In this work, we analysed the luminance responsivity standard system (model: VMI-PR-006) based on the national standard system of luminance (model: V11.04.18). This system was used to calibrate the luminance responsivity scale of standard photometer and luminance standard integrating sphere.When using the national standard system (V11.04.18) to calibrate the luminance standard integrating sphere (model: LN3; S/N:05B840), an uncertainty of U=0.73% for k=2, where k is the *, was found [1]. On the other hand, we calibrated the luminance responsivity scale of a standard photometer system (VMI-PR-006) based on the national standard system of luminance (V11.04.18) and compared it to the luminance responsivity scale calibrated at NMIA (National Measurement Institute Australia) with En=0.13<1, where En is *. This standard system is used for the calibration and verification of measurement devices within the luminance measurement requirements specified by the Vietnam technical documents.

12-18

Authors: Huong Thi Le, Tien Anh Nguyen, Thu Hoang Vo, Michał Michalak, Tam Hoang Luu, Ha Tran Nguyen*

Lanthanum orthoferrite (LaFeO3) photocatalysts were synthesized by a facile and cost-effective co-precipitation method via the hydrolysis of La (III) and Fe (III). The characteristics of LaFeO3 were investigated through thermogravimetric analysis (TGA), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), vibrating sample magnetometry (VSM), and transmission electron microscopy (TEM). During the investigation of the applicability of LaFeO3 as a photocatalyst for the atom transfer radical polymerization (ATRP) of methyl methacrylate monomer under UV irradiation, the obtained poly(methyl methacrylate) exhibited a high molecular weight and narrow polydispersity index. In addition, the LaFeO3 can be recovered via application of a magnetic field and reused for the atom transfer radical polymerization process.

24-29

Authors: Thi Bich Van Pham, Minh Hao Hoang*

A coagulation cascade forms through proteolytic reactions and involves different factors. There are two coagulation pathways, including intrinsic and extrinsic mechanisms, which converge by the formation of factor Xa. Factor Xa plays a crucial role in the formation of the complex with factor Va in the presence of calcium ions and phospholipids. This complex converts prothrombin to thrombin, which leads to the formation of a very strong fibrin clot. Much effort has been devoted to the efficient interference of this enzyme cascade by the inhibition of factor Xa due to its important effect. (R)-3-amidinophenylalanine inhibitors are known inhibitors of factor Xa reported so far. In the present work, a two-dimensional quantitative structure activity relationship (2D-QSAR) was performed on 50 (R)-3-amidinophenylalanine inhibitors (the training set) with respect to their pKi values toward factor Xa, where pKi=-logKi, and Ki is the inhibition constant, to develop a mathematical model that depends on the physicochemical properties of the inhibitors. Partial least squares regression (PLSR) was used to yield a QSAR model containing molecular descriptors that significantly contribute to pKi values. The statistically significant parameters of the model, such as squared correlation coefficient, R2=0.834, root mean square error, RMSE=0.210, cross-validated Q2cv=0.789, and cross-validated RMSEcv=0.237, were obtained for the training set. The developed 2D-QSAR model was applied to predict the pKi values of the 62 inhibitors. Furthermore, the reliability of the model was also confirmed via statistically significant parameters obtained from validation on an external set.

34-37

Authors: Thi Thoi Bui*, Dai Quang Ngo, Van Loc Tran

The paper describes the preparation of new sulfonylurea derivatives from sulfonyl carbamate 6 with amino derivatives. The process for synthesis of the key compound 6 included three steps starting from compound 6-chloronicotinic acid 1, which are readily available chemicals. The compound 1 in the presence of triethylamine in anhydrous acetone solvent and ethyl chloroformate to obtain 6-chloronicotinic (ethyl carbonic) anhydride compound 3. The compound 3 were subsequently reacted with compound 4 to obtain compounds 5. The sulfonamides 5 was refluxed with ethyl chloroformate in present anhydrous potassium carbonate in dry acetone to obtain the key compounds 6. The total yield of the key intermediate compound 6 is about 81.35%, related to the starting materials. Finally, threesulfonylurea derivatives 7a-c were synthesized by condensation of 6 with various of amines in toluene. Their structures have been determined by IR, MS and 1H and 13C NMR spectroscopic methods,and their α-glucosidase inhibitory activity have been evaluated.

41-47

Authors: Ha Lan Nguyen, Viet Ky Nguyen, Van Ngo Dau, Thi Phi Oanh Tran*

Water is extremely important to all life currently, the Cu Chi district has been provided with one hundred percent clean water. However, due to long-standing habits and easy extraction, citizens are still using groundwater daily for water consumption and cooking.Therefore, in this study, the use of groundwater from the middle-upper Pleistocene aquifer in the Cu Chi district of Ho Chi Minh city, for domestic and drinking purposes was investigated. In terms of pH and Fe, NH4+, NO3-, As and Mn content, data were collected from central water supply stations under the operation of the Centre for Rural Water Supply and Sanitation (CERWASS). Furthermore, samples collected from 94 households and water supply stations were also evaluated for groundwater quality via pH and Fe, As, Hg, Cd, Pb, Cr6+ and CN- concentration. On the other hand, a human health risk assessment for carcinogenic substances (As) and non-carcinogenic substances (Mn) was performed by a variety of assessments including the susceptibility to contamination according to the DRASTIC index, which weights water risks by applying a semi-quantitative model. Because pollution is inevitable with today’s modernization and industrialization, these research results contribute to management and control measures deeply needed to achieve and maintain a safe water supply, thereby ensuring the health and safety for the communities in the Cu Chi district

56-64

Authors: Duy Tue Nguyen, Tri Nhut Do*

Solar energy is a free and nearly endless source of energy. Vietnam has the advantage of harnessing solar energy for many essential purposes because of its geographic location in the tropics. This allows electricity usage to be minimized in solar chemistry and energy conversion from solar energy into electricity; or to completely replace electricity usage in applications such as heating, cooling, ventilation, water treatment, cooking processes, and heating processes. In this paper, three solar water heating systems with a heat pump are designed for resorts located at three famous tourist destinations in Vietnam: Phu Quoc island and the towns of Bao Loc, and Sa Pa. These places represent the Southern, Central, and Northern regions of Vietnam, respectively. Ecotect and Grasshopper software applications are employed with the latest weather, heat, and radiation data and was obtained from climate.onebuilding.org. Data analysis is based on Ecotect software and the computational design is done in Grasshopper software. These software applications show that Phu Quoc island is the most efficient place to exploit solar energy, followed by Bao Loc, which is lower due to the fog, and Sa Pa, where solar radiation is low. In order to increase the water heating efficiency in places with very low solar radiation, a heat pump is considered along with a conventional solar water heating system and optimum azimuth angle of 180o South for the solar collector. This method is an efficient solution that can be applied in Sa Pa as well as in other places in Vietnam where there is a lack of solar radiation. The solar energy factor (SEF) is significantly increased from 14.37 to 57.47 and the solar fraction (SF) per year is increased from 93.5 to 98.3% using this method.

71-76

Authors: Le Thi Quyen, Nguyen Thi Minh Thu, Le Thi Minh Phuong, Nguyen Thi Trang*

The objectives of this work were to accurately evaluate testing kits that analyse sperm DNA fragmentation in infertile men and to provide a comparison of an improved testing kit (SSSperm testing kit) to the existing Halosperm testing kit in an analysis of sperm DNA fragmentation. A cross-sectional study was conducted on 300 semen samples from infertile men with a sperm concentration ≥1 million/ml using the Bland-Altman, T-test, and Pearson test for statistical study. The SSSperm testing kit had a coefficient of variation of CV%=2.26%<5% and ttn=0.970.05). In conclusion, the SSSperm testing kit for the analysis of sperm DNA fragmentation is qualified as determined from quantitative tests, and the SSSperm testing kit is equivalent to the Halosperm testing kit.

83-88

Authors: Van-Tuan Tran*, Tao Xuan Vu

Penicillium digitatum exists in nature as a causative agent of green mould disease in citrus fruits at the postharvest stages. Inspections of the molecular mechanism of the host invasion by P. digitatum usually require suitable selection markers for genetic manipulation. In this study, we recruited the phleomycin resistance gene as a selection marker for the genetic transformation of P. digitatum using Agrobacterium tumefaciens. The results showed that the growth of the wild strain P. digitatum PdVN1 from fungal spores is quite sensitive to phleomycin and is inhibited at a concentration of 50 μg/ml, whereas growth from fungal mycelium is more tolerant and completely suppressed at a concentration of 200 μg/ml. Under optimised conditions, the A. tumefaciens-mediated transformation (ATMT) efficiency of P. digitatum with the phleomycin resistance marker could reach over 1000 transformants per 106 spores. All the tested transformants presented the integration of T-DNA in their genomes and were mitotically stable for the phleomycin resistance. Furthermore, the results also revealed the success for heterologous expression of the DsRed fluorescent gene in the fungus, in which the strong red fluorescent signal could be observed over the whole fungal mycelium and spores. Our work demonstrates for the first time that the phleomycin resistance gene can serve as a reliable selection marker for A. tumefaciens-mediated transformation of the postharvest pathogen P. digitatum. This selection marker can be exploited for T-DNA insertional mutagenesis and for functional investigations of target genes involved in citrus decay by P. digitatum.

3-16

Authors: Vu Dinh Quang, Van Quang Doan, Van Nguyen Dinh, Nguyen Dinh Duc*

The shortage of reliable datasets and resource assessments, resource variations, and lack of marine planning are the technical challenges facing offshore wind energy development in Vietnam. This pioneering paper comprehensively addresses these challenges by first screening available datasets to select cross-calibrated multi-platform (CCMP) data and validating them with measurements. The resource is divided into four zones of 100 NM-width from the coastline. The wind energy density (WED) and capacity factor (CF) are calculated using an 8 MW reference turbine. The assessment of the zoned resource and infrastructures is based on the location of synchronous power sources and ports, along with the variation of WED and CF. Zone 3, comprising of the Binh Thuan and Ninh Thuan seas, the southern part of Zone 2 (Phu Yen and Khanh Hoa), and the northern part of Zone 4 (Ba Ria and Vung Tau) are found to have the highest wind energy potential, where the annual accumulated WED is 80 GWh/km2. The five year CF and average wind speed in Phu Quy island were 54.5% and 11 m/s, respectively. These zones, with moderate resource variation and excellent ports are the most suitable for offshore wind energy development. Zones 1 and 4 are recommended for far-offshore wind farms. This work is useful to various environmental groups and is a crucial input to marine and power planning

23-27

Authors: Thu Vo Hoang, Huong Thi Le, Nhung Thanh Thi Truong, Michał Michalak, Ha Tran Nguyen*

In this research, a novel organic photocatalyst of 10-(perylene-3-yl-10H-phenoxazine (PHP) has been successfully synthesized from perylene and phenoxazine via Buchwald-Hartwig C-N coupling. The chemical structure of catalyst was determined via FT-IR, proton nuclear magnetic resonance (1H-NMR) spectrum and optical properties were investigated through UV-Vis spectroscopy. The PHP has been used as the reducing photoredox catalyst for organocatalyzed atom transfer radical polymerrization (O-ATRP) under UV irradiation. The well controlled molecular weight of the methyl methacrylate polymers have been obtained nearly 80% with a low polydispersity index under 1.5.

32-37

Authors: Thi Tuyet Mai Phan*, Thi Sen Ngo

Pectin and cellulose were successfully extracted from passion fruit peel waste. The maximum pectin yield of the process was 12.60% at pH=2 for 1.5 h. The pure cellulose obtained from the passion fruit peel waste was prepared by refluxing of the passion fruit peel powder with 1 M NaOH and 1.25 M HNO3 solutions at 90°C for 1 h and 1.5 h, respectively. The passion fruit peel cellulose was converted to carboxymethyl cellulose (CMC) by etherification. The pure cellulose was soaked in a mixed solution of isopropyl alcohol and NaOH for 1.5 h. After that, it was reacted with cholroacetic acid at 70°C for 1.5 h. The optimum conditions for carboxymethylation were 5 g cellulose, 2.0 g cholroacetic acid, and 15 ml 20%w/v NaOH. The optimised product had a degree of substitution (DS) of 0.78 and was used as constituent in a biopolymer.

43-49

Authors: Pham Minh Xuan*, Le Hai Tran*, Huynh Ky Phuong Ha, Mai Thanh Phong, Van-Huy Nguyen, Chao-Wei Huang

Herein, a polyamide-based thin film composite (TFC) membrane was fabricated for the removal of arsenic (As) from water. The polyamide thin film was synthesized through interfacial polymerization (IP) onto a polysulfone porous substrate. A Box-Behnken design of response surface methodology was used to investigate the effect of preparation conditions, including piperazine (PIP) concentration, trimesoyl chloride (TMC) concentration, and reaction time on the As rejection and permeate flux of the synthesized membrane. The separation performance of the prepared membranes from 15 designed experiments was conducted with an arsenate (Na2AsHSO4) solution of 150 ppm at a pressure of 40 psi and a temperature of 25oC. The analysis of variance revealed the regression models to be adequate. From the regression analysis, the flux and As rejection were expressed by quadratic equations as a function of PIP concentration, TMC concentration, and reaction time. It was observed that the PIP concentration, TMC concentration, and reaction time had a significant effect on the flux and As rejection of the polyamide membrane. Moreover, a strong impact from the interaction of PIP and TMC was also observed on rejection of the resulting membrane. Using the desirability function approach to analyse the regression model, the optimal preparation conditions of the polyamide membrane were a PIP concentration of 2.5 wt.%, TMC concentration of 0.11 wt.%, and reaction time of 40 sec. The membrane exhibited a good As rejection of 95%.

55-61

Authors: Nguyen Xuan Thang*, Bui Manh Cuong, Dang Ngoc Ha, Do Van Dung, Sudha Nair, M.T. Vinayan, Gajanan Saykhedkar, Raman Babu, Doan Thi Bich Thao, Tran Quang Dieu, Nguyen Chi Thanh, P.H. Zaidi

The results of testing the International Maize and Wheat Improvement Center’s (CIMMYT’s) hybrid combinations, developed from hybrid 790 F2:3 lines and 10 parental lines, using two testers (CML451 and CLO2450) under optimal and managed drought conditions in Ninh Thuan, Vietnam, show that the average grain yield of the biparental (BP) groups of heterosis groups A and B is, respectively, 2.58-3.65 tons/ha and 2.56-2.76 tons/ha in drought conditions, and 4.24-5.02 tons/ha and 5.41-5.93 tons/ha in well-watered conditions, respectively. By genotyping eight BP populations with 39,846 single nucleotide polymorphism (SNP) markers, CIMMYT experts identified 15 important gene regions that regulate grain yield associated with 15 SNP markers on chromosomes 3, 4, 5, 6, 7, 8, 9, and 10 which is useful for applying molecular markers in breeding drought-tolerant maize. On that basis, the Maize Research Institute of Vietnam studied and genotyped three populations, including 450 F2 families, with 96 SNPs using the Kompetitive Allele Specific PCR (KASP) genotyping method. The result was that 57 SNP markers related to drought tolerance were found useful to these populations. In addition, 27 F2 families demonstrating drought tolerance and high grain yield were selected as primary materials for breeding maize hybrids tolerant to stresses and adaptive to climate change.

69-73

Authors: Minh-Tan Vo, Van-Tai Nguyen, Thi-My-Chi Vo, Thi-Nhu-Phuong Bui, Thanh-Son Dao*

In this study, the detrimental effects of trace metals on the growth of phytoplankton and the phytoremediation potential of microalgae from Vietnam are elucidated. Two green algae Scenedesmus accuminatus var biseratus and Scenedesmus protuberans, along with the diatom species Cyclotella sp., were exposed to chromium (Cr) and cadmium (Cd) at three distinct concentrations ranging from 5-761 μgl-1 and 18-667 μgl-1, respectively, over a period of 14 days. The results indicated that S. acuminatus var biseratus and Cyclotella sp. were relatively tolerant to Cr, even at the highest test concentration, while the growth rate of S. protuberans was significantly inhibited when exposed to 660 μgl-1 of Cr. Only Cyclotella sp. showed a high Cd tolerance, whereas Cd at concentrations of 493 and 607 μgl-1 prohibited the growth rate of S. acuminatusand S. protuberans, respectively. Moreover, at the concentrations tested, all three algal species could remove 90-100% of the Cr out of the test medium. The diatom Cyclotella sp. could reduce up to 99% of Cd whereas the two green algae could only do not remove more than 13% of Cd from the test medium.We strongly recommend the Cyclotella sp. as a candidate for phytoremediation in metal-contaminated water. Our results contribute vital information toward solutions that environmental experts and managers are searching for to resolve pollution caused by trace metal contaminants

85-89

Authors: Minh Nhat Phan, Nguyen Van Nhi Tran, Jimmy Yu, Tan Phong Nguyen*

Slaughterhouse wastewater (SWW) possesses very high organic and nutrient concentrations and its residues are moderately solubilized, which leads to pollution affecting the environment and human health. The objective of this study was to investigate the effective removal of ammonium in slaughter wastewater by up flow anaerobic sludge blanket (UASB) technology combined with an expanded granular sludge bed (EGSB) using anammox and PVA gel as the biomass carrier. Ammonium loading rates (NLRs) increased from 0.25 kgN-NH4+/m3.d to 0.75 kg N-NH4+/m3.d with hydraulic retention times (HRTs) of 12, 6, and 4h. The system was operated in 2 phases. In phase 1, the removal of ammonium by employing the combination of UASB technology and EGSB using anammox was examined. The removal efficiencies of nitrite were 52% (NLRs=0.25 kgN-NH4+/m3.d), 69% (NLRs=0.5 kgN-NH4+/m3.d) and 64% (NLRs=0.75 kgN-NH4+/m3.d). On the other hand, the removal efficiencies of ammonium were about 37% (NLRs=0.25 kgN-NH4+/m3.d), 64% (NLRs=0.5 kgN-NH4+/m3.d) and 55% (NLRs=0.75 kgN-NH4+/m3.d). In phase 2, a PVA gel was supplied to the EGSB as the biomass carrier for growing the anammox sludge. The result showed that the removal efficiencies of nitrite were about 55% (NLRs=0.25 kgN-NH4+/m3.d), 77% (NLRs=0.5 kgN-NH4+/m3.d), and 73% (NLRs=0.75 kgN-NH4+/m3.d). In addition, the removal efficiencies of ammonium were about 56% (NLRs=0.25 kgN-NH4+/m3.d), 68% (NLRs=0.5 kgN-NH4+/m3.d), and 60% (NLRs=0.75 kgN-NH4+/m3.d)