Vietnam Academy of Science and Technology: Journals Online
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Optical Properties of Silver Nanowires Conjugated with Protein
No full textOptical properties of protein-conjugated metallic nanowires are theoretically investigated based on the Mie theory and the core-shell model. Our numerical calculations show that optical spectra of protein-conjugated nanowires can have more a maximum compared to these nanowires without biomolecules. This finding is in a good agreement with previous experiments. We provide better interpretation for the origin of optical peaks in absorption spectrum of nanowires. Our results can be used for designing biosensors and bio-detectors
Phylogenetic analyses of ribosomal transcription units from Haplorchis taichui and H. pumilio species of Heterophyidae (Platyhelminthes: Opisthorchiata)
No full textHeterophyidiasis caused by minute intestinal flukes becomes of public concern in many countries worldwide. Haplorchis taichui and H. pumilio, belonging to the family Heterophyidae (Platyhelminthes: Trematoda) are two of many infecting humans and commonly found in Vietnam. Sequence study of these two small intestinal flukes is still very limited, hence we need more prospective markers for taxonomic identification and classification. This study provides complete coding sequence of the ribosomal transcription units (rTU) from H. taichui and H. pumilio (Vietnamese samples) and demonstrates the use of complete 28S rDNA sequences for phylogenetic analysis.The complete coding sequence of the rTU (from 5' 18S to 3' 28S), consisting of complete 18S, ITS-1, 5.8S, ITS2 and complete 28S rRNA genes and spacers, from H. taichui (7,268 bp) and H. pumilio (7,416 bp) from human hosts in Vietnam, were determined and annotated. The 18S and 5.8S genes of both species were of the same length (1,992 bp/18S, 160 bp/5.8S), but 28S genes differed (3,875 bp/H. taichui and 3,870 bp/H. pumilio). ITS-1 in H. taichui (797 bp) and ITS-2 in H. pumilio (280 bp) do not contain tandem repeat units (TRUs), while ITS-1 in H. pumilio (1,106 bp) contains 3 TRUs of 136 bp/each and 2 TRUs of 116 bp/each and ITS-2 in H. taichui (444 bp) contain 3 TRUs (83–85 bp/each). A phylogenetic tree inferred from the alignment of complete 28S rDNA sequences of 32 trematode strains/species, including 2 Vietnamese Haplorchis spp. and 24 species of 8 families in the suborders Xiphidiata (families Nanophyetidae, Paragonimidae, Collyriclidae), Opisthorchiata (Heterophyidae, Opisthorchiidae), and Echinostomata (Echinostomatidae, Fasciolidae). and Schistosoma japonicum of the family Schistosomatidae is used as an outgroup. The topology of the phylogenetic tree clearly confirmed the status of the Vietnamese H. taichui and H. pumilio species. These species gathered in a group (in the family Heterophyidae) clearly identified in the position of "sister” group to those in the family Opisthorchiidae (suborder Opisthorchiata, superfamily Opisthorchioidea)
Assessment of gene and protein similarities of Beijing-1 vaccine producing strain with Japanese encephalitis virus strains circulating in Vietnam
No full textSince 2006, the inactivated Japanese encephalitis vaccine has been studied and produced by the VABIOTECH company from the Beịing-1 strain on Vero cells. Vaccines produced from the materseed and working seed virus have been evaluated at laboratory and clinical scale in humans. The results showed that the vaccine was safe and created 100% protective antibodies after the booster dose. To officially put this vaccine into production and mass use, the master seed virus BV-MSV-0210 and working seed virus BV-WSV-0310 with the reference standard strain JEV Beijing-Kanonji has been tested for genetic stability. By the method of Sanger sequencing and genetic analysis software, we have evaluated the similarity of nucleotide and proteinsequencesof the E antigen-encoding gene. The results showed that the seed virus similarity of amino acids and nucleotides is 100% compared with the reference strain. Thus, it can be concluded, the seed virus has antigen stability. Nucleotide and amino acid gene sequences of E genomic regions of the two seed lots were compared with virus strains isolated from human, pig and mosquito in Vietnam. The results showed that the nucleotide similarity of seed virus compared with the JEV strains isolated from humans ranged from 86.67 to 97.54%; from pigs is 87.47 to 88.33%, and from mosquitoes is 86.05 to 99%. Meanwhile, the amino acid similarity of the seed virus with the JEV strains isolated from humans ranged from 96.73 to 99.02%; from pigs is 98.00 to98.40% and from mosquitoes 94.55 to 98.40%. The sequence of amino acids in the epitope producing neutralizing antibodies of the seed virus did not differ from that of the JEV strain circulating in humans isolated in 2014
Production of nanoliposomes with piperine from black pepper (Piper nigrum) and its improved growth inhibitory activity on colorectal cancer cells
No full textBlack pepper (Piper nigrum) is an autoicous and decorous vine cultivated in many local regions of Gia Lai. Black pepper is one of the most commonly consumed spices, and its pungency is due to the presence of alkaloids, such as piperine. This compound represents diverse biological activities, including anti-inflammatory, anticancer, antiviral, anti-larvicidal, pesticide, anti-alzheimer’s activities, etc. However, due to its poor solubility as well as its toxic effects at high use concentration, piperine is still in limit of pharmaceutical applications. In this study, we have used black pepper seed collected at Chu Se - Gia Lai to extract piperine. The compound extracted efficiency was approximately 18% with 96.7% of purity. Based on the obtained pure piperine, the hybrid nanopiperine-CD133 monoclonal antibody (mAb^CD133) complexes were fabricated with the nanoparticle size of about 170 nm, the polydispersity index (PDI) of 0.23 and the zeta potential of -9.4 mV. The nanocomplex was subjected for growth inhibitory activities against cancer colorectal cells (HT-29 cell line). The results showed that the nanopiperine-mAb^CD133 complex exhibited significant in vitro growth inhibition HT-29 colorectal cancer cells (46.56 ± 2.78%), while the viability of healthy cells remained unaffected (17.77 ± 0.82 %). The nanocomplex could also label 12.17% of HT-29 cells, which was rather higher than 3.83% from mAb^CD133 conjugated phycoerythrin (PE) as positive control. The fabricated nanopiperine-mAb^CD133 complex has proved the enhanced cytotoxic activities against colorectal cancerous cells as well as promising biopharmaceutical potency
QUANTITATIVE NUCLEAR MAGNETIC RESONANCE BASED ON PULCON METHODOLOGY: APPLICATION TO QUANTIFICATION OF SOME STANDARD MATERIAS AND NATURAL PRODUCTS
No full textQuantitative nuclear magnetic resonance (qNMR) is not as widespread as structural NMR, but has recently received increasing attention from the analytical community due to its advantages such as nondestructive sampling, fast analysis, no need to prepare a calibration curve, the reference standard is not identical to the analyte so that one reference material can be used to find the purity of any compound. Traditional qNMR uses internal standard method, where sample and the reference standard are mixed together in the NMR tube so both sample and reference standard integrity is an issue after analysis. In PULCON (Pulse Length–based Concentration), a relatively new qNMR method using external standards, analytical samples and standards are always separated during qNMR experiment, not mixed together, thus integrity is not an issue for both sample and reference standard. Currently, both internal standard and external standard qNMR are not widely disseminated in Vietnam. In this report, the ERETIC qNMR procedure was introduced on the 1H qNMR experiments of two high purity substances and three natural products, extracted in Vietnam. The results obtained with the PULCON qNMR method were compared to the reference data from manufactories or those obtained by traditional internal standard qNMR and were found to be in reasonable agreement. Thus, PULCON qNMR can be of wide utility for routine analysis, especially for the expensive and new compounds
Monitoring of coastline change using Sentinel-2A and Landsat 8 data, a case study of Cam Pha city - Quang Ninh province
No full textThe main purpose of this study is to evaluate the performance of Sentinel - 2A and Landsat 8 data in monitoring coastline change from 1999 to 2018 at Cam Pha city, Quang Ninh province. Both data were collected under similar conditions of time and weather features to minimize the differences in interpretation results caused by these factors. The coastline was extracted from Sentinel-2A and Landsat 8 in 2018 by using the Normalized Difference Water Index (NDWI). Coastline map from Quang Ninh Department of Natural Resources and Environment with a scale of 1: 50.000 in 1999 was used as a reference of the same mask and overlaid on coastline maps in 2018 to identify the changes in the study area. The data from fieldwork and Google Earth was used to evaluate the accuracy and make comparative comments. The results presented that changes dramatically occurred between 1999 and 2018 with the accretion process prevailing. This process took place quite strongly on the East and Southeast coast while the erosion process only occurred with small areas at scattered points in the study area. The results also showed that the overall classification accuracy of Sentinel-2A imagery (95.0%) was slightly higher than that of Landsat-8 (87.5%). The combined use of Landsat-Sentinel-2 imagery is expected to generate reliable data records for continuous detecting of coastline changes
GRAPH BASED CLUSTERING WITH CONSTRAINTS AND ACTIVE LEARNING
No full textDuring the past few years, semi-supervised clustering has emerged as a new interesting direction in machine learning research. In a semi-supervised clustering algorithm, the clustering results can be significantly improved by using side information, which is available or collected from users. There are two main kinds of side information that can be learned in semi-supervised clustering algorithms: the class labels - called seeds or the pairwise constraints. The first semi-supervised clustering was introduced in 2000, and since that, many algorithms have been presented in literature. However, it is not easy to use both types of side information in the same algorithm. To address the problem, this paper proposes a semi-supervised graph based clustering algorithm that tries to use seeds and constraints in the clustering process, called MCSSGC. Moreover, we introduces a simple but efficient active learning method to collect the constraints that can boost the performance of MCSSGC, named KMMFFQS. In order to verify effectiveness of the proposed algorithm, we conducted a series of experiments not only on real data sets from UCI, but also on a document data set applied in an Information Extraction of Vietnamese documents. These obtained results show that the proposed algorithm can significantly improve the clustering process compared to some recent algorithms
FABRICATION OF TITANIUM DIOXIDE (TiO2) NANOTUBE ARRAYS DOPED WITH PLATIN (Pt) AND THEIR PHOTOELECTROCHEMICAL CHARACTERISTICS
No full textIn this work, Titanium dioxide (TiO2) nanotube arrays doped with Platin (TiO2/Pt) was successfully synthesized at low temperature by anodic and chemical reduction methods. Results showed that Pt/TiO2 NTAs with 0,57 wt% Pt exhibited the highest photoelectrochemical properties. Furthermore, high surface area, small particle size and enhanced visible-light absorption as well as improved charge transfer and separation are believed to be responsible for the improvement of photocatalytic activity of the doped materials
Removal of Rhodamine B Dye by Plasma Jet Oxidation Process
No full textRecently, nonthermal atmospheric pressure plasma has been developed as a novel tool in removal of water pollutants. Rhodamine B dye, widely used in textiles and biology, is toxic to both humans and animals, hence removing residual Rhodamine B in solution is necessary. In this work, we have setup a cold plasma jet system and used it to effectively remove Rhodamine B in the solution. We have shown that the main oxidation substance responsible to remove Rhodamine B is the hydroxyl radical (•OH). By studying the effect of the hydrogen peroxide (H2O2) concentration in the initial and later was produced in the solution, the plasma power, and the Ar gas flow speed on the dye remove rate, we have identified 2 main reaction pathways to generate hydroxyl radical (•OH). Both of these reaction pathways involve high-energy electrons interacting with water and O2 in the solution and in the ambient air. Our work provides important information to understand the mechanism of dye removal by cold plasma treatment
A mesoscale numerical approach to predict damage behavior in concrete basing on phase field method
No full textIn this paper, we develop a numerical approach to simulate the 2D complex damage and fracture process of quasi-brittle concrete materials. Based on the phase field theory for the case of elastic isotropic multicomponent materials and the generation process based upon Monte Carlo’s simulation method, we construct a numerical procedure to solve complex damage thermodynamic problems. The diffusive phase field variable obtained from this calculation can be used to represent the crack nucleation and propagation within 2D complex mesostructure. Some factors that affect the numerical result (type of crack density function and type of split decomposition of strain energy) are accounted to make the predictions more accurate for the case of concrete material. Some new numerical examples are provided to show the usefulness of the approach.