Tạp chí Khoa học Tự nhiên Đại học Quốc gia Thành phố Hồ Chí Minh

The MIKE 21 FM model, developed by the Danish Hydraulic Institute, is a distributed system model that is used in hydrological calculations, water quality simulation, sediment transport calculations, resources and water environment in rivers, estuaries, coastal areas, and seas... This paper is an initial step in setting and establishing a set of model's parameters for simulating contaminant transport at the Dinh Vu coastal area, Hai Phong city under different scenarios. The model was calibrated and validated with the real data at 8 surface water quality monitoring sites at Hai Phong coastal area in 2014 and 2015. The result obtained by MIKE 21 HD for adjusters and good quality with specified Nash are 0.96 and 0.93, respectively. The relatively wrong number of Ecolab parameters are below 20 %.

This article was retracted on 15 December 2021 by authors.   Euphorbia tirucalli has not been chemically studied much in Vietnam. This research described the isolation and elucidation of compounds isolated from the plant collected in Binh Thuan. Multiple chromatographic methods were applied, including normal phase silica gel column chromatography and thin-layer chromatography. Seven compounds were isolated and their chemical structures were elucidated by spectroscopic analysis as well as comparing their data with the ones in the literature. They are arjunolic acid (1), eriodictyol (2), quercitrin (3), afzelin (4), scopoletin (5), 3,3′,4- trimethylellagic acid (6), and gallic acid (7). Among them, compound 1 a major component was isolated for the first time in Euphorbia genus, while three compounds 2, 4, and 5 were isolated from this species for the first time.

Ho Chi Minh City plays a role as a leading economic and social center in the South of Vietnam, together with the urbanization, transportation system is being rapidly developing, resulting in an increase in emissions from these activities, and worsen the quality of the city. Therefore in this study, emission inventory for transportation has been conducted using the EMISENS model and then using GIS solfware to distribute the emissions in space in order to have the overall picture of air emissions of this city. The results showed that on-road activites especially from using motorcycles are the major contributer to air emissions in the city. On-road source in general accounting for 88% of NOx, 99% of CO, 79% of SO2, 99% of NMVOC, 88% of PM in total emissions from transportation activities. Key finding in this study is that hahour activities contribute up to 20% of total SOx and 10% of total PM. Other sources of transportation (airport, habour, bus station, rail way) only accounting for negligible amount of emissions Emission maps of transportation showed that central areas (District 1, District 10, District 3 and District 5) reached higer level of emissions than others. In additions, harbours areas as District 2, District 4 and District 7 where Saigon Port and Cat Lat Port are located in suffer the highest emissions of SO2, NOx and Dust.

The early Palaeozoic granitogneiss association in the Chu Lai - Kham Duc area (Quang Nam) is a large area of hundreds of km2, along southern of the East – West ductile deformation zones (Tam Ky – Phuoc Son fault zone), which is studied in detail in different geologic maps scales by the geologists, which is named Chu Lai complex. The five samples studied in detail are composed mainly of granitogneiss and biotite gneiss from the Chu Lai - Kham Duc area. The samples were crushed and large zircons were extracted. The in-situ zircon U–Pb geochronology was conducted on five samples (60 zircons in total) of age between 444 Ma and 426 Ma. These ages indicated the prolonged magmatic – tectonic period between the late Ordovician and middle Silurian in Kon Tum massif.

Rice husk is a common agricultural waste and an abundant source in Viet Nam. In terms of composition, rice husk is a silica-rich material (SiO2) so it can be used to prepare negative electrode materials for rechargeable Li-ion batteries. Recent processes of synthesizing the silica materials for the rechargeable batteries are often complex, expensive, and energy-intensive. In this study, KOH was used to treat rice husk ash to obtain SiO2/C porous composite materials. X-ray diffraction results (XRD) showed that the diffraction peak between 22o and 23o (2q ) was characterized of SiO2 material, and the other peaks around 43-44o was featured of carbon material. Scanning electron microscope image (SEM) showed the porous structure with the pore size 3-5 mm.Besides, the amorphous structure with coverage layers was also confirmed through the Transmission Electron Microscope (TEM) images. Preliminary electrochemical results demonstratedthat Li-ion coin cell using the SiO2/C anode material exhibited a high capacity of 1200 mAh/g at a discharge current of 1.0 A/g and maintained 1000 mAh/g after 100 cycles. SiO2/C materials prepared from rice husks were highly promising for battery application thanks to their low cost, stable performance, environmental friendliness, and easy expansion for production scale.

Histone deacetylase enzymes are overexpressed in many types of hematologic malignancies (acute myelogenous leukemia, myelofibrosis, cutaneous T-cell lymphoma, and Hodgkin lymphoma) and their inhibition of HDACs could result in the inhibition of cell proliferation and induction of apoptosis. Thus, HDAC inhibitors are candidates of anticancer drug development. Belinostat is a histone deacetylase inhibitor which was approved by the US FDA in 2014 for the treatment of refractory T-cell lymphoma and solid tumor. This paper reported the synthesis of two belinostat analogues (including a firstly synthesized compound) by introducing fluorine atoms at the hydrophobic capping group (CAP) of belinostat. The resulted compounds were then tested by molecular docking analysis and in vitro evaluation of their antioxidant and anti-cancer activities. The new compound 8a displayed the highest anti-cancer efficacy against human breast (MCF-7) and liver (Hep-G2) cancer cell lines with EC50 values of 1.5‒4.0 μg/mL. Two compounds showed the antioxidant activity with an EC50 value of 8.30‒13.60 μg/mL. These results suggested that the synthesized belinostat analogs might have anti-cancer potential for further investigation.

This study reported a single-step method for the fabrication of magnetic cellulose nanocrystals (MGCNCs) by coprecipitation iron oxide nanoparticle onto cellulose nanocrystals (CNCs). Cellulose nanocrystals (CNCs) were derived by hydrochloric acid hydrolysis (HCl 6 M, 25 mL/g cellulose) in the optimum condition at 90 °C for 90 min. Pure cellulose was isolated from Nypa fruticans branches, a popular tree in Vietnam. The structure and morphology of CNCs were characterized by crystallinity index, morphology and thermal stability. TEM images showed that the average fiber length of the nanocrystals was 410 nm with a diameter of 10 nm (aspect ratio of 41) and the crystallinity index of 85.2 % (by XRD). The as-prepared MGCNCs were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction measurement (XRD), thermal gravity analysis (TGA) and vibrating sample magnetometry (VSM). The results showed that the magnetic cellulose nanocrystals absorbed about 51 % w/w on CNCs surfaces with magnetic properties and the saturation magnetization of about 24 emu/g. Possessing the biocompatibility as well as paramagnetism, the magnetic cellulose nanocrystals were promising materials for environmental treatment.

The aminolysis of poly(ethylene terephthalate) (PET) waste bottle with excess amount of aliphatic diamines, such as tetramethylenediamine (TMDA) and hexamethylenediamine (HMDA) without catalyst has been carried out. Each trimers and pentamers in the obtained products were isolated and characterized by FTIR, NMR, HPLC methods. Although an excess of diamine was employed, longer blocks of oligomers were still formed as minor products.

The problem of microplastic pollution (<5 mm) is becoming one of the biggest challenges facing countries. One of the problems is the export value of seafood products. Therefore, to assess the microplastic accumulation in clam (Meretrix lyrata), this study investigated the concentration of microplastics (MPs) in clam and their habitat in four clam culture beds (Tan Thanh, Ba Tri, Ganh Hao, and Ba Dong) in three consecutive months (from January to March 2020). The samples were analyzed by the method of oxidation of organic compounds and MPs flotation solution. The result showed that the concentrations of MPs in all three types of samples (seawater, surface sediment, and clam tissues respectively 36,66 ± 11.94 items 1 L- of seawater; 169.34 ± 42.01 items 1 kg- of soil; 13.79 ± 1.06 items individual- 10 g-, w.w) were markedly different between the four clam culture beds in three months (p-value <α = 0.05). Among which, the natural clam culture at Ganh Hao beach had the lowest concentration of MPs compared to Tan Thanh, Ba Dong, and Ba Tri cultured beds by households. Furthermore, the concentration of MPs in March was also the lowest compared to January and February. Hard plastic fibers were found the most (> 50%) compared to other types of plastic. The conclusion that microplastics have appeared everywhere in the environment and were found in the organism of clam, affecting the life of aquatic organisms.

Dendrobium is one of the largest and most important orchid genera because of their ornamental and commercial value. Plant tissue culture is an established method for the effective micropropagation of of valuable plants. In this study, Dendrobium caesar keikis were sterilized with sodium hypochlorite 2.5 % in 15 minutes. Effects of 3 kinds of cytokinin (TDZ, BA and kinetin), adenine and 3 kinds of auxin (IAA, IBA, NAA) with different concentrations on inducing shoots and roots were studied. The highest shoot initation was observed on Knudson C (KC) medium supplemented with BA 2.0 mg/L. Strong roots were induced in KC media supplied with 0.5 g/L active charcoal (AC) and 1.0 mg/L IAA. In order to transfer in vitro plant to the nursery garden, the highest percentage of survival seedling was shown on coconut husk substrate, and peanut husk was the best for the growth and development of Dendrobium caesar. Micropropagation and nursery at garden for Dendrobium caesar were successfully established.