Vietnam Academy of Science and Technology: Journals Online
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SIZE DISTRIBUTION AND CONTRIBUTION OF PARTICLES FROM RICE STRAW OPEN BURNING TO THE ATMOSPHERE IN HANOI
No full textAtmospheric ultrafine, accumulation mode and coarse fractions collected at representative rice straw open burning areas in Hanoi were investigated to identify characteristics of size distribution and contribution of particles emitted from rice straw (RS) burning season to the atmosphere. The sampling was conducted in two episodes: RS burning episode and RS non-burning episode at Dong Anh and Quoc Oai, in seven consecutive days for each sampling campaign from 2018 to 2019. In the RS burning episode, PM1-2.5 showed the highest fraction among all collected particles in both sampling sites, while PM2.5-10 was the most abundant in RS non-burning season. The average mass concentration of PM2.5 in RS burning period and RS non-burning period were 79.7 46.5 g m-3 and 65.2 21.9 g m-3, respectively at Dong Anh sampling site. Those values were 90.9 33.2 g m-3 in the QO_RS burning site and 71.9 29.3 g m-3 in the TM_RS non-burning site. The proportion of fine particle (PM2.5) at both sites were considerable higher in RS burning period as compared to non-burning period, while the concentration of ultrafineparticle (PM0.1) and coarse particle (PM10m) were similar between two episodes. This result provides better understanding on size distribution and contribution of fine particles from open RS burning to the atmosphere in Hanoi, which is an useful information for the environmental managers to control RS open burning in Hanoi as well as in Vietnam.
The status of seagrass communities in the Truong Sa archipelago
No full textSeagrasses in Truong Sa archipelago have not been intensively studied and understood, even in some obviously progressive works recently published. It is essential to carry out much more researches to fill up understanding gaps of seagrasses in the area. In 2019, within the framework of the project coded KC09.29/16–20, two surveys were conducted for three selected islands (Truong Sa Lon, Thuyen Chai and Song Tu Tay) in the area, focusing on marine ecosystems including seagrass beds. Survey results in the selected islands show eight seagrass species (one new record), the estimated total distribution area of 1,190 ha, the total reserve of biomass reaching 7,417.2 tons.dry, equivalent to 11,432.8 tons.CO2
ALGORITHM FOR IMPROVING FEEDING RATES OF INDUSTRIAL WELDING ROBOT TA 1400 IN COMBINATION WITH A TURNTABLE FRAME
No full textAn algorithm for improving feeding rates of industrial welding robot TA 1400 of Panasonic with 6 degrees of freedom is presented. The kinematics and dynamics of the robot are calculated on MATLAB software. The proposed algorithm for improving feeding rates is mathematically analyzed and the performance of the system is evaluated in a simulation environment. The simulation results are used for proving the efficiency of the solution. Based on the achieved results, the algorithm can be applied for reducing time and improving the productivity of other industrial robots in the futur
Antimicrobial and cytotoxic effects of endophytic Streptomyces strains isolated from Cinnamomum cassia Presl in Vietnam
No full textVietnam is recognized as one of the countries with the high diversity of medicinal plant species in the world, nevertheless little is known about the distribution, diversity and biological activity of endophytic actinomycetes associated with host plants. The present study aimed to evaluate antimicrobial and cytotoxic activities of four endophytic Streptomyces strains including Streptomyces sp. HBQ75, HBQ87, HBQ102 and HBQ104 isolated from different organs (roots, stems or leaves) of Cinnamomum cassia Presl. Analysis of 16S rRNA gene sequences and the phylogenetic tree assigned them to four different Streptomyces species as follow Streptomyces fulvissimus HBQ75, Streptomyces parvulus HBQ87, Streptomyces pratensis HBQ102 and Streptomyces ribosidificus HBQ104. These strains exhibited broad antimicrobial spectrum against at least five out of nine pathogens tested, among them S. parvulus HBQ87 showed the best activity (inhibition zones 20 mm). Interestingly, S. parvulus HBQ87 carried all three genes (pks-I, pks-II and nrps) encoding for polyketide synthase or non-ribosomal peptide synthetase enzymes involved in biosynthesis of secondary metabolites, while the remaining strains only possessed one or two genes. All the Streptomyces strains were positive for the anthracyclines-like antibiotic activity. The cell-free supernatants of S. parvulus HBQ87 revealed remarkable inhibitory effects against all three human cacinomar cell lines including hepatoma Hep3B, breast adenocarcinoma MCF7 and lung cancer A549 cells at both concentrations tested (30 µg/mL and 100 µg/mL), while S. fulvissimus HBQ75 and S. pratensis HBQ102 were active against only Hep3B and MCF7 cells. In conclusion, the phenotypic and genotypic features of the four endophytic Streptomyces strains suggest that they have a capacity to produce different broad-spectrum secondary metabolites. Among them, S. parvulus HBQ87 could be the most potential candidate for the production of important antimicrobial and antitumor compounds
Cloning, expression and purification of Leptospira LigB antigen in Escherichia coli
No full textLeptospira is one of the most common zoonotic diseases in the tropics and subtropics. Humans are infected by exposure to Leptospira contained water or food sources. Leptospirosis usually breaks out after the flood and causes several consequences for people and economy. Leptospirosis disease, if not rapidly detected and treated promptly, it causes serious consequences such as acute hepatitis-kidneys, meningitis and bleeding, heart and nerve complications, and severe illness can lead to death. Therefore, quick and accurate detection of Leptospira pathogen plays a very important role in Leptospirosis disease treatment. Among antigens of Leptospira, a conserved domain of LigB antigen (Leptospiral immunoglobulin-like protein) was reported that is present in the most of pathogenic serovars of Leptospira, but not in the non-pathogenic Leptospira biflexa, thus this conserved domain was used for production of Leptospirosis detection kits as well as vaccine for Leptospirosis. In order to create a kit for Leptospirosis diagonostic, especially detect anti-Leptospira antibodies in Leptospira infected serum and plasma samples, about 1kb gene fragment encoding for conserved domain of LigB (about 36 kb in molecular weight) was used as the material for producing of LigB protein by DNA recombinant technology. In this study, we present the results for cloning, expressing a conserved domain of LigB antigen in E. coli cells and purifying protein by affinity chromatography collumn. The result indicates that recombinant LigB protein was successfully expressed in E. coli Rosetta 1 and purified by Hitrap chealating collumn. The LigB protein concentration after purification reached 60 mg/L medium with 98% purity. This purified protein will be used as the materials for creating Leptospirosis kit
ACTIVATED CARBON FABRICATED FROM VIETNAMESE SUGARCANE BAGASSE FOR REMOVAL OF CIPROFLOXACIN FROM AQUEOUS SOLUTION: PREPARATION, CHARACTERIZATION AND KINETIC STUDIES
No full textRecent interest in wastewater treatment has shifted to the use of agricultural waste to treat antibiotics in aqueous solutions due the economic efficiency the technique brings. This study focuses on the synthesis, properties and study of the kinetic mechanism of activated carbon and its potential application to remove antibiotics from aqueous solutions. Activated carbon is synthesized from sugarcane bagasse by activated method with active substance of ZnCl2. With a specific surface area of about 980.84 m2/g and high porosity, the product could absorb a large amount of ciprofloxacin (CIP) antibiotics. The properties of materials are characterized by relevant analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET). The behavior of CIP adsorption was studied under the effect of adsorption dose, initial CIP concentration and pH value. The adsorption and isothermal mechanisms are also studied. The results show that the adsorption adhered to the second kinetic model and the experimental data was found to be reasonably fitted to the Langmuir isotherm. Therefore, activated carbon manufactured from sugarcane bagasse could be used as a potential adsorbent to effectively remove antibiotics from aqueous solution
SECONDARY METABOLITES FROM THE STEM BARKS OF RHIZOPHORA MUCRONATA LAMK
No full textUsing various chromatographic separations, three phenolic derivatives (1‒3) and three phytosteryl glycosides (4‒6) were isolated from a methanolic extract of R. mucronata stem barks. Their structures were elucidated to be cinchonain Ia (1), breynioside B (2), polystachyol (3), β-sitosterol 3-O-β-D-glucopyranoside (4), β-sitosterol 3-O-β-D-(6'-O-palmitoyl) glucopyran-oside (5), and β-sitosterol 3-O-β-D-(6'-O-stearoyl)glucopyranoside (6) by detailed analysis via spectroscopic techniques (1D, 2D NMR, and ESI-MS data) as well as comparison with those reported. This is the first report of compounds 1‒6 from the Rhizophora genus
STUDY ON DIFFERENT FACTORS AFFECT COD REMOVAL CAPACITY OF HALANAEROBIUM LACRUISEI IN SALINE WASTEWATER
No full textThis study evaluated a number of factors (including temperature, pH, salinity) affecting the growth of Halanaerobium lacruisei bacteria in order to reduce COD concentration in saline wastewater of a fish sauce processing plant. The results of the study showed that halophillic bacteria had good capacity of reducing COD concentration under specific conditions.Laboratory experiments with different bacterial culture conditions showed that 30°C, pH 7.0 and 6-7 % salinity is the optimal culturing condition for Halanaerobium lacruisei treating COD in wastewater. In the laboratory condition, COD treatment capacity in saline wastewater of this microorganism can be up to nearly 88% after 48 hours, ensuring that the effluent meets the environmental requirements. In pilot condition of culturing the bacteria (in plastic tank, stimulating the real condition), after 25 days, the COD removal decreased continously, 80% effectively compared with the inlet wastewater. The effluent treatment efficiency by a laboratory method meets the standard of type B wastewater specified in QCVN 40:2011/BTNMT. This study showed that Halanaerobium lacruisei can be usedeffectively to treat the COD parameter in saline wastewater which can be applied in industrial wastewater treatment area as well
Study on genetic variations of the D-loop region in three Vietnamese ethnic groups Kinh, Lolo and Lahu
No full textMitochondrial DNA (mtDNA) sequence analysis has been widely used to investigate population genetic and evolutional history of different ethnic groups worldwide. In this study, the D-loop region of 119 Vietnamese individuals belonging to three different ethnic groups was sequenced and compared with reference mtDNA on rCRS for genetic variations. Total 218 genetic polymorphisms were found in this population, among which 48 variations appeared with frequencies of more than 0.1. Further statistical analysis showed that there were 23, 13 and 24 single nucleotide polymorphisms (SNP) distributed differently between Kinh vs. Lolo, Kinh vs. Lahu , and Lolo vs. Lahu groups, respectively. The mean pairwise genetic distances between each pair of ethnic groups were 0.0101, 0.0098 and 0.0092 for Kinh - Lolo, Kinh - Lahu, Lolo - Lahu, respectively. This indicated that although the Lolo and Lahu ethnic groups both belong to the Tibeto-Burman language group, the genetic distance between them was no closer than the genetic distances between them and the Kinh group of the Viet-Muong (Austroasiatic) language group. This study was the first research on the D-loop region of the Lolo and Lahu populations in Vietnam. These results provided more data for exploring the genetic background and the history of those ethnic groups as well as other minority ethnic groups in Vietnam
Simultaneous effect of nitrogen, trifluoromethyl and dimethyl amino group on the radical trapping capacity of diphenylamine: a quantum chemical study
No full textIn order to maximize the peroxyl radical trapping capacity of diphenynlamines, the substituents such as N, NMe2, and CF3 are suggested to add to their phenolic rings. The reasonable combination of these substituents at right position can reduce the bond strength of the N-H bond, but still keep the derivatives stable in air