Vietnam Academy of Science and Technology: Journals Online
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Potential anti-tumor activites of extract from fresh leaves of the male papaya (Carica papaya L.) collected in Ha Tinh province
No full textNowadays, the percentage of people with cancer is increasing. There are many methods used to treat cancer such as surgery, chemotherapy, the radiation, etc. In addition, the use of medicinal plants, natural products, is also popularly applied for cancer patients. Using 90% ethanol as the extraction solvent, we produced 4 kinds of concentrated extracts from dried flowers, dried leaves, fresh flowers, fresh leaves of male papaya (Carica papaya Linn). In vitro study, the extracts of dried flowers, fresh flowers did not effect on MCF7, A549, HT 29, Huh 7R, HEK 293 and LLC cancer cell lines. The extracts of dried leaves and fresh leaves presented cytotoxic effects with IC50 values ranging from 1.88 to 13.64 mg/mL. Meanwhile, activities of the extract of fresh leaves was 4-6 times stronger than that of the extract of dried leaves's. Based on evaluation of the IL2 and IL6 production capability of macrophage, we found that the extract of fresh leaves strongly inhibited the IL-6 production at 4 mg/mL (50.56%) and 0.8 mg/mL (23.79%) in comparison with the negative control (P0.05) while it did not show the ability to induce IL-2 in the same studied concentrations. Using tumor bearing mice as model for studying the antitumor activities of extract of fresh leaves at the dose of 3 mL/kg/day and 6 mL/kg/day, we identified the positive effects of the higher dose treatment. The results showed that the extract of fresh leaves at the dose of 6 mL/kg/day could inhibit 33.44% the tumors’ sizes on day 28 (P0.05); tumor's weigh decreased to 9.84 against 13.76 g of the negative control; the WBC parameter reduced from 41.65x106/mL to 19.1x106/mL (P0.05), AST decreased from 1441.6 U/L to 1038.97 U/L (P0.01), and creatinin decreased from 26.37 µmol/L to 20.63 µmol/L compared with the negative control group (P0.05). These promising results are the scientific evidences for applying this extract in cancer treatment in the future
EVALUATION OF SOLAR RADIATION ESTIMATED FROM HIMAWARI-8 SATELLITE OVER VIETNAM REGION
Get PDFThe development of Solar energy system is growing rapidly in Vietnam in recent years by encouragement of the Government in renewable energy. Requirement for accurate knowledge of the solar radiation reaching the surface is increasingly important in the successful deployment of Solar photovoltaic plants. However, measurements of different components of solar resources including direct normal irradiance (DNI) and global horizontal irradiance (GHI) are limited to few stations over whole country. Satellite imagery provides an ability to monitor the surface radiation over large areas at high spatial and temporal resolution as alternatives at low cost. Observations from the new Japanese geostationary satellite Himawari-8 produce imagery covering Asia-Pacific region, permitting estimation of GHI and DNI over Vietnam at 10-minute temporal resolution. However, accurate comparisons with ground observations are essential to assess their uncertainty. In this study, we evaluated the Himawari-8 radiation product AMATERASS provided by JST/CREST TEEDDA using observations recorded at 5 stations in different regions of Vietnam. The result shows good agreement between satellite estimation and observed data with high correlation of range 0.92-0.94, but better in clear-sky episodes.Because of AMATERASS outperform, we used it for validating ERA-Interim reanalysis in the spatial scale. The comparison was made dividedly for 7 climate zones and 4 seasons. The conclusion is that ERA-Interim is also well associated with satellite-based estimates in seasonal trend for all season, but in average the reanalysis has negative bias towards satellite estimates. This underestimation is more pronounced in the months of JJA and SON periods and in the north part of Vietnam because of unpredicted cloud in the ERA reanalysis
SECURITY CAPABILITY ANALYSIS OF COGNITIVE RADIO NETWORK WITH SECONDARY USER CAPABLE OF JAMMING AND SELF-POWERING
Get PDFThis paper investigates a cognitive radio network where a secondary sender assists a primarytransmitter in relaying primary information to a primary receiver and also transmits its own information toa secondary recipient. This sender is capable of jamming to protect secondary and/or primary informationagainst an eavesdropper and self-powering by harvesting radio frequency energy of primary signals.Security capability of both secondary and primary networks are analyzed in terms of secrecy outageprobability. Numerous results corroborate the proposed analysis which serves as a design guidelineto quickly assess and optimize security performance. More importantly, security capability trade-offbetween secondary and primary networks can be totally controlled with appropriate selection of systemparameters
Mapping flood inundation areas over the lower part of the Con River basin using Sentinel 1A imagery
No full textThis study aims to determine a processing method for rapid flood inundation and potential flood-damaged area mapping in the lower part of the Con River basin, a region most vulnerable to floods in Vietnam, using Sentinel 1A (S1A) image. A threshold from -23 dB to -12 dB of the VV band was identified for extracting the water areas from S1A image and was applied in 28 S1A scenes to identify flood dynamics. The time-series map of flood inundation areas during the period of December 2017 to December 2018 evidenced Tuy Phuoc and northern part of An Nhon as the districts most inundated by the 2017 and 2018 floods, which is consistent to the local records. The round-year trend of total flood inundation area shows strong correlations with the Con river water level (R = 0.75) and local precipitation (R = 0.64) measured in Binh Nghi hydro-meteorological station confirming the appropriateness of the study method and the capability of S1A data in monitoring floods
A modified averaging operator with some applications
No full textThe paper presents a new approach to the conventional averaging in which the role of boundary values is considered in a more detailed way. It results in a new weighted local averaging operator (WLAO) taking into account the particular role of boundary values. A remarkable feature of WLAO is that this operator contains a parameter of boundary regulation p and depends on a local value h of the integration domain. By varying these two parameters one can regulate the obtained approximate solutions in order to get more accurate ones. It has been shown that the combination of WLAO with Galerkin method can lead to an effective approximate tool for the buckling problem of columns and for the frequency analysis of free vibration of strongly nonlinear systems.
The dna barcoding data and genetic distance of leaf beetles (Coleoptera, Chrysomelidae) in Vietnam
No full textDNA barcoding is a useful tool in identifying species, biodiversity assessment, and revealing phylogenetic relationships of living organisms in the world. However, the DNA barcode data for leaf beetles in Vietnam is lacking. In this study, sixteen DNA sequences of 658 bp of COI gene from nine species (five genera; three subfamilies) of Chrysomelidae in Vietnam were (obtained). Intra- and inter-specific diversities, and phylogenetic relationships of these species were analyzed.
Cyperus entrerianus Boeckeler, a new record from Vietnam
No full textCyperus entrerianus Boeckeler, an invasive alien plant from South America, is newly recorded from Vietnam. A morphological description, color illustrations, line drawings and distinguishable morphological characters of C. entrerianus from C. surinamensis and C. luzulae were provided, additionally and short notes, and habitat of the species were also given.
Mining and selecting genes encoding chitinase from DNA metagenome data
No full textIn this study, genes encoding chitinaseswere obtained by mining the rhizosphere metagenome database of 2-year-old replanted coffee trees in Dak Lak province and annotating using CAZy data. These sequences predictably are covered 90% of chitinase domains by BLASTp and range from 33% to 99% identity in comparison with published sequence data of chitinase genes. In order to find new funtional chitinase gene(s), among 8/56 chitinase genes with sequence identity less than 75%, ChiA_2 sequenceshowed the highest max score andsignificant homology (72%) was initially selected. Analysis of in silico sequence identified a protein motif for a signal peptide of 30 amino acid residues at the N- terminal using SignalP 4.1 server. By InterProscan software, the ChiA_2 gene sequence is predicted to have conserved active site FDGIDIDWE located at 134-142. The ChiA_2 sequence consisting of 1167 nucleotides, encoding for 389 amino acids with a predicted molecular mass of 43 kDa was synthesized, cloned into the pET21 a(+) vector and transformed into E. coli BL21 (DE3) by heat shock. ChiA_2 protein was specifically expressed in the recombinant E. coli BL21 (DE3) cell with an activity of 4.9 U/ml. In this study, analyzing metagenomic data from the soil sample of rhizosphere provided relatively sufficient genetic information of chitinase gene and initially successful expression and functional evaluation of ChiA_2 sequence, encoding Chitinase 2
Effect of gamma irradiation on the viability and cellulase production of some filamentous fungi
No full textThe motivation of our research is to examine the mutagenic effect of gamma irradiation on cellulase secretion of some filamentous fungi. The spore suspensions of Aspergillus sp. TTG and Trichoderma sp. VTCC were irradiated at dose ranging 0-2500 Gy under gamma Cobalt-60 source at Ha Noi Irradiation Center. The result showed that the survival rate of fungi decreases with the increasing dose. The radiation dose required to kill 90% of the total number of fungal spores (D10) of these strains was about 400 Gy. The viability of Aspergillus sp. TTG and Trichoderma sp. VTCC at 500 Gy were 0.46 % and 0.78%, respectively, while the number of survival spore decreased by 6.5-7.5 Log unit at the dose of 2500 Gy. By screening in PDA medium with the addition of CMC (carboxymethyl cellulose) and Congo red as an indicator of cellulose degradation, hundreds of colonies with higher hydrolysis capacity’s value (HC) compared to the initial strain were observed after irradiation. The colonies expressed the highest cellulose hydrolysis capacity with maximum HC value were obtained at dose range of 700-1500 Gy. It is important to notice the 5 potential mutants including 3 mutants of Aspergillus (TTG-700, TTG-1000 and TTG-1200) and 2 mutants of Trichoderma (VTCC-1000, VTCC-1500) demonstrated the higher CMCase secretion (1.78 – 2.48 times) compared to the wild types. After 5 generations, the enzyme productions of the mutants were fairly stable and there were no differences in growth rates and morphology of each generation. The result of this study is an evidence for using gamma irradiation to improve cellulase production in filamentous fungi
Genetic data of the ITS1-5.8S rDNA sequences of small liver flukes (Opisthorchiidae) from cats in Northern Vietnam
No full textDomestic cats and humans are favorite final hosts for some hepatic trematodes of Opisthorchiidae. The present study examined the sequence variation in the nuclear ribosomal DNA (rDNA) region, including the internal transcribed spacer (ITS1) and the 5.8S gene, of two human opisthorchiid species Clonorchis sinensis (Cobbold, 1875) Looss, 1907 and Opisthorchis viverrini (Poirier, 1886) Stiles Hassal, 1896, in cats sampled in Northern Vietnam. The length of 30 partial ITS1‒5.8S rDNA sequences of C. sinensis from different hosts and localities varied from 761 to 766 bp. The results showed completely identity for all investigated 5.8S rDNA sequences of C. sinensis. In contrast, the variations were revealed in the complete ITS1 sequences of C. sinensis. Three polymorphic sites, indel and new sites with intragenomic polymorphism were detected. The length of the complete ITS1 rDNA region ranged from 656 to 661 bp. There are no substitutions downstream of the 5 bp insertion, and the different ratio of nucleotide in polymorphic sites with presence/absence of insertion leads to the existence of 6 genotypes in the investigated samples. The major genotype was obtained in 70% of sequences, other genotypes were presented by 1, 2 or 3 sequences. Nucleotide diversity in whole sample of C. sinensis was 0.00122 ± 0.00073. Partial sequences of ITS1‒5.8S rDNA of O. viverrini were 745 bp in length, and no difference was observed. Phylogenetic analyses by neighbor joining phylogram inferred from ITS1‒5.8S rDNA of 3 sequences of O. viverrini and 30 sequences of C. sinensis were formed two separately monophyletic clades.