Vietnam Academy of Science and Technology: Journals Online
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PHENOLIC GLYCOSIDES FROM THE STEMS OF CLERODENDRUM INERME GAERTN. COLLECTED IN VIETNAM
No full textFive phenolic glycosides, clerodenoside A (1), seguinoside K (2), cistanoside D (3), verbascoside (4), and isoverbacoside (5) were isolated from the ethyl acetate soluble fraction of methanolic extract of the Clerodendrum inerme stems. Their structures were determined by spectroscopic analysis and comparison of spectral data with those reported in the literature. Compound 3 was isolated from this plant for the first time
Cloning, expression, and purification of Acrv tip protein from Aeromonas hydrophila using Escherichia coli host cells
No full textAeromonas spp. use T3SS to secrete and transport effector proteins to the host cells. These proteins play a major role in bacteria virulence by interfering with the signaling cascades and by disrupting the cytoskeleton structure of the host cell. Despite tremendous efforts, structural and functional information regarding AcrV tip protein of T3SS remains elusive. In this study, we cloned the gene encoding the AcrV protein from Aeromonas hydrophila AH-1 and inserted it into the pET-M expression vector. The pET-M vector containing AcrV gene was transformed and expressed in E.coli BL21 (DE3) cells. The recombinant AcrV protein was purified by affinity chromatography using Ni-NTA column. The obtained AcrV with high purity can be used for structural and functional studies.
ENZYMATIC SACHARIFICATION OF ALKALINE PRETREATED RICE STRAW BY CELLULASE FROM CELLULOSIMICROBIUM SP. MP1
No full textThe effects of different physical and technological parameter such as time, substrate to liquid ratio, enzyme concentration, temperature, and pH on enzymatic saccharification of alkaline pretreated straw cellulose were studied. For alkaline pretreatment, the straw was incubated with 10 % NaOH at ratio 1:20 (w/v) at 90 °C for 1 hour. After the alkaline pretreatment the cellulose content increased from 50.2 % (w/w) to 67.3 % (w/w). Enzyme used for saccharification of treated and untreated straw was produced from Cellulosimicrobium sp MP1 which was isolated from termite gut. Results from research showed that the highest percentage of saccharification of alkaline pretreated straw was 69.91 %, corresponding to 10.58 mg/mL of reducing sugar. The hydrolysis conditions for reaching this highest saccharification yield were: temperature of 55 ºC, substrate to liquid ratio of 2 g/100 mL, enzyme concentration of 37.5 U/g, pH of 5.5 and hydrolysis time of 48 hours
ANTIFUNGAL ACTIVITY OF COUMARIN AND TRITERPENOID TARAXASTERYL ACETATE FROM THE N-HEXANE SOLUBLE FRACTION OF THE AERIAL PART OF EUPATORIUM FORTUNE AGAINST SCLEROTIUM ROLFSSI AND RHIZOCTONIA SOLANI
No full textAbstract-HCTN7. Phytopathogenic fungi Sclerotium rolfssi and Rhizoctonia solani in the form of sclerotia can survive in the soil for a long time and cause serious disease severity by attacking the roots and lower stems of plants. There are challenges in the control of the plant fungal diseases by using chemical fungicides. During screening antifungal-plant, we found that the n-hexane soluble fraction of Eupatorium fortune highly inhibited the mycelia growth of both phytopathogenic fungi. The bioassay-guided fractionation of the hexane soluble fraction led to the isolation of antifungal compounds coumarin (1) and taraxasteryl acetate (2). The other compounds scopoletin (3), and scololin (4) were isolated from the ethyl acetate soluble fraction of E. fortune. The chemical structures of 1-4 were elucidated by 1D- and 2D-NMR spectroscopy and ESI-MS methods. The isolated compounds were evaluated their antifungal activity against S. rolfssi and R. solani by in vitro food poisoned technique bioassay. The mycelial growth of R. solani was markedly inhibited by 89.7% and 85.8% when exposed to 1 after 1 day and 2 days treatments at 250 ppm, respectively. Compound 2 displayed the most antifungal activity; it inhibited the mycelia growth of S. rolfssi by 98.7 and 89.4 % at 250 and 100 ppm 1 day after treatment, respectively. This study indicated that the aerial part of E. fortune possesses potent in vitro antifungal activity against S. rolfssi and R. solani and contains bioactive compounds that could be used as active ingredients for developing botanical fungicides against plant diseases.
Effect of dietary astaxanthin on reproductive performance, egg quality and larvae of clowfish Amphiprion ocellaris (Cuvier, 1830)
No full textThis study was designed to evaluate the effects of astaxanthin in broodfish diets on reproductive performance, egg quality and larvae quality parameters of clownfish (Amphirion ocellaris). Five treatments were tested with 5 levels of astaxanthin (Carophyll Pink 10% CWS) of 0, 50, 100, 150 and 200 mg/kg added to the feed. Each treatment was repeated in triplicate and the supplemental feeding trials were arranged for 13 months. The results showed that there were significant differences in hatching rate of egg, malformed rate and survival rate of larvae in 3 days post-hatch (p0.05) among the feeding trials of astaxanthin supplements. The highest hatching rate of egg and survival rate and the lowest malformed rate of larvae were observed in the treatment that was supplemented with astaxanthin 150 mg/kg feed, respectively 92.14 %; 93.57 % and 0.55 %. However, the astaxanthin supplementary diets did not affect the re-maturation and spawning period, spawning frequency, fecundity, egg diameter and larval size of nemo fish among the treatments. The results also suggested that astaxanthin requirement for clownfish broodstock to improve reproductive performance was 150 mg/kg feed
Certain properties of nanohydroxyapatite obtained from Lates calcarifer fish bone
No full textFish bone by-products are considered as abundant source of hydroxyapatite (HAp). The preparation of HAp from fish bones not only contributes to improving the value of by-products but also minimizes negative impacts on the environment. In this study, nanohydroxyapatite was successfully obtained from Lates calcarifer fish bone purchased from seafood export company in Khanh Hoa province. Fish bones were under alkali treatment and then heated at 600oC within different time intervals of 1, 2 and 4 hours. Analysis of XRD and SEM showed that the calcium formed was completely single-phase and possessed an average size of 50–64 nm depending on the calcination time. The results of the Ca/P molar ratio from 1.839 to 1.847 prove that the nano-HAp powders are B-type biological hydroxyapatites, which has been confirmed by FTIR spectrum. In addition, the content of heavy metals such as As, Pb, Hg, Cd is detected within safety limits. These properties allow nano-HAp powders to be applied in food and medicine fields.
ESTIMATION OF TIDAL EXCURSION LENGTH ALONG THE SHATT AL-ARAB ESTUARY, SOUTHERN IRAQ
No full textThe tidal excursion length along the Shatt Al-Arab estuary was estimated based on the mathematical relation proposed by Parsa and Shahidi (2010). The field measurements of water level, bathymetry, and discharges were conducted to fulfill the objective of the study. The results revealed that the tidal excursion length is site-specific and depends on the characteristics of location which include tidal phases, bathymetry, and geometry. However, the results indicated that there are pronounced differences in tidal excursions lengths between the spring and neap tide phases in all studies stations. The spring tide coincided with the maximum tidal excursion lengths in Shatt Al-Arab estuary with 16.537, 16.187, 11.122, and 9.139 km in the estuary mouth, Faw, Siba, and Abo Flous stations respectively. While the neap tidal excursion lengths were 12.298, 9.254, and 7.269 km in Faw, Siba, and Abo Flous stations respectively
Size Effect of Gold Nanoparticles on Optical and Electrical Properties of Au@TiO Nanocomposite Thin Films
No full textThis study focuses on the influence of gold nanoparticle sizes on optical and electrical properties of Au@TiO2 nanocomposite films. Here, the gold nanoparticles (AuNPs) of different sizes of 5 nm, 10 nm, 20 nm, 40 nm and 60 nm were dispersed onto nanoporous TiO2 thin films to form Au@TiO2 nanocomposite films. FE-SEM images and UV-vis absorption spectra show that AuNPs had good dispersion on the TiO2 films and all Au@TiO2 nanocomposite films exhibited a good surface plasmon resonance (SPR) with the resonance absorption peaks in the visible light region (about 550 nm). The effect of AuNPs on the films photoluminescence property was investigated using excited laser light of 325 nm wavelength at room temperature. The films electrical properties were studied from the change of the photocurrent under illumination of solar simulator and UV light source. The results show that the presence of gold nanoparticles has significantly improved the photocurrent of Au@TiO2 nanocomposite films and especially when AuNPs size was less than 20 nm. In addition, we also found that the photocurrent magnitude of the films with small AuNPs sizes (5 nm and 10 nm) under solar simulator light was 4 times larger than the one under UV light. These results indicate that AuNPs size had a great influence on the improvement of photocurrent in nanocomposite films
Excitation Function for the Production of Nb in the Zr() Reaction
No full textWe have measured the excitation function for the production of 96Nb in proton induced reaction on natural zirconium in the energy range of 10.58 MeV to 43.61 MeV. The measurement was performed using a stacked-foil activation method combined with off-line γ-ray spectrometry. The stack containing Zr samples, Cu monitors, and several energy degraders was irradiated at the MC-50 Cyclotron of the Korea Institute of Radiological and Medical Sciences (KIRAM), Korea. The cross section of the natZr(p,x)96Nb reaction was extracted from the measured activity of reaction product using an HPGe γ-ray detector. The energy of the proton beam along the stacked foil was calculated using the code SRIM-2013. The proton beam flux was determined via the natCu(p,x)62Zn and natCu(p,x)65Zn monitoring reactions. The measured cross sections of the natZr(p,x)96Nb reaction as a function of the proton energy are compared with the literature data as well as with the theoretical predictions using the TALYS-1.95 nuclear model code and the TENDL-2019 nuclear data library
Compression Effects on Structural Relaxation Process of Amorphous Indomethacin
No full textIndomethacin is a common nonsteroidal anti-inflammatory drug, but its glass transition behaviors remain ambiguous. Here we present a simple theoretical approach to investigate the molecular mobility of amorphous indomethacin under compression. In our model, the relaxation of a particle is governed by its nearest-neighbor interactions and long-range cooperative effects of fluid surroundings. On that basis, the temperature and pressure dependence of the structural relaxation time is deduced from the thermal expansion process. Additionally, we also consider correlations between the activated dynamics and the shear response in the deeply supercooled state. Our numerical calculations agree quantitatively well with previous experimental works