Vietnam Academy of Science and Technology: Journals Online
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Conamomum odorum , a new species of Zingiberaceae from central Vietnam
Get PDFConamomum odorum is described as a new species from Khanh Hoa Province, Central Vietnam. It is characterized by sweet smell, striate and narrowly elliptic leaf leaves with short petiole and ligule, ovoid congested inflorescence, pubescent calyx, cream corolla lobes, yellow, obovate and reflexed labellum with median red bands at base and hairy ovary. The new species is illustrated with detailed photographs of key characters and morphologically compared to its closest congeners C. piereanum and C. rubidum. A distribution map of the genus in Vietnam is provided.
The effect of some factors on expression of gene encoding endoglucanase from dna metagenome of Binh Chau hot spring in Escherichia coli
Get PDFExpression of microbial target genes in Escherichia coli is broadly used due to its advantages namely: well established system, easy to manipulate, a huge biomass, high level productivity, safe and inexpensive to grow. Metagenomic technique has been applying in Vietnam recently for effective mining of uncultured gene resources, especially in endemic mini-ecologies such as hot springs where the cell densities are low. DNA metagenome of Binh Chau hot spring was isolated and sequenced by Illumia HiseqTM. Based on analyses of databases of cellulase-encoded genes, denovogenes 18736 gene sequence for thermal endoglucanase was selected for expression in E. coli. In this paper, some factors for expression of endoglucanase have been investigated. The results show that appropriate gene expression conditions are: Expression performed in E. coli C43 (DE3) on TB medium at 30oC with 0.25 mM of IPTG as inducer, the culture volume of 20% compared with the bottle volume and the expression time is 42–48 hours. In this condition, the biomass production and soluble enzyme activity can reached up to 5.54–5.58 g /L and 1.92–1.98 U/mL, respectively. Our results show the prospect of exploiting microbial genes without culture
Infection status and molecular identification of digenean cercariae in snails in Kim Son district, Ninh Binh Province and Ba Vi district, Ha Noi
Get PDFIn this study, the molecular method was used to identify digenean cercariae from freshwater snails in Kim Son District (Ninh Binh Province) and Ba Vi District Ha Noi. A total of 9 snail species were collected and examined for cercarial infection. Three snail species (Radix swinhoei, Angulyagra polyzonata and Pomacea canaliculata) were not infected, while the other 6 species (Austropeplea viridis, Gyraulus convexiusculus, Parafossarulus striatulus, Bithynia fuchsiana, Melanoides tuberculata and Tarebia granifera) were infected with digenean cercariae at low infection rates, ranging from 2.3% to 6.3%. Seven cercarial groups were identified: Echinostome, Monostome, Parapleurophocercaria, Xiphidiocercaria, Fucocercaria, Gymnocephalous and Megalurous. Snails M. tuberculata and P. striatulus were infected with 4 cercarial groups, A. viridis and G. convexiusculus snails were infected with 2 groups, 2 snail species B. fuchsiana and T. granifera were infected with one group of cercaria. The results of ITS2 sequences analyses of the cercarial groups identified the larvae of 9 trematode species, namely Echinostoma revolutum, Echinochasmus japonicus, Notocotylus intestinalis, Philophthalmus gralli, Haplorchis pumilio, Procerovum cheni, Fasciola gigantica, Australapatemon burti and Cyathocotyle prussica. Among them the last three species, P. cheni, A. burti and C. prussica, were found for the first time in Vietnam. In addition, the ITS-2 sequence of Gymnocephalous cercariae which was previously identified as Sphaeridiotrema monorchis, from P. striatulus snail was 97% similar to that of Sphaeridiotrema pseudoglobulus. Likewise, ITS-2 sequence of Echinostome cercaria from B. fuchsiana snail was 93% similar to that of E. japonicus and that of Xiphidiocercaria cercaria from M. tuberculata snail was 93% similar to Lecithodendrium spathulatum.
Distribution of and the taxonomic keys to the species in the genus Daptonema Cobb, 1920 in Vietnam
No full textUp to now, 22 nematodes species have been recognized in the genus Daptonema Cobb, 1920 from mangrove, river and estuary ecosystems in Vietnam, with 18 species described as new species and 4 others recognized for science. Three species, D. dihystera Gagarin and Nguyen Vu Thanh, 2005, D. salvum Gagarin, Nguyеn Vu Thanh Nguyen Thi Thu, 2005 and D. rigidum Gagarin, Nguyеn Vu Thanh Ngudyen Thi Thu, 2005 were found in fresh water, while other species were distributed in the mangrove forest, estuaries and seagrass ecosystem. The distribution and taxonomic keys to the species in the genus Daptonema Cobb, 1920 in Vietnam have been provided.
New records of rare genera of the subfamily Cheloninae (Hymenoptera: Braconidae), with description of two new species from Vietnam
Get PDF New species of subgenus Areselonus Braet, 1999 and genus Odontosphaeropyx Cameron, 1910, viz. Chelonus (Areselonus) intermedius Long, sp. n. and Odontosphaeropyx plesius Long, sp. n. (Braconidae: Cheloninae) are described and illustrated. Additionally, these two rare taxa are newly recorded for Vietnam’s braconid fauna. The checklist and distribution of the already known species of the genera are also provided.
Study of antihyperglycaemic activity in streptozotocin induced diabetic mice and antioxidant activities of medicinal plant extracts
Get PDFSome extracts of medicinal plants have demonstrated potential benefits in treatment of different diseases for centuries such as antihyperglycemic, antioxidant, anti-inflammatory, antibacterial. The purpose of this study is to evaluate the effect of extracts from several herbal plants, such as Gymnema sylvestre, Stevia rebaudiana, Cinnamomum cassia, Zea may, Ocimum basilicumon blood glucose level in streptozotocin (STZ) induced diabetic miceand to offer scientific proofs for the identified antihyperglycemic effect by investigating on mechanismsof the most effective extract. The results proved that diabetic mice treated with 70% ethanol extracts of Gymnema sylvestre leaves and Stevia rebaudiana leaves showed significant reduction of the blood glucose levels at a dose of 500 mg/kg body weight when compared to control (p0,05). Antihyperglycemic activity of Gymnema sylvestre (57,68%) and Stevia rebaudiana extracts (54,93%) were significantly higher than other extracts. The inhibition of α-amylase and α-glucosidase activity of Gymnema sylvestreand, Stevia rebaudiana extracts were carried out in vitro. The result demonstrated that these Gymnema sylvestre and Stevia rebaudiana extracts exerted significant inhibition and specific on intestinal α-amylase and α-glucosidases activities. Using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay showed that Gymnema sylvestre and Stevia rebaudiana extracts exhibited relatively low antioxidant activity with the concentration of a sample required for 50% scavenging of the DPPH free radical of 115,88 ± 1,16 µg/ml and 160,27 ± 2,01 µg/mlcompared to vitamin C (49,16 ± 1,26 µg/ml).
Combination of hydrologic and hydraulic modeling on flood and inundation warning: case study at Tra Khuc-Ve River basin in Vietnam
No full textFlooding caused by historically high flows, especially in Tra Khuc-Ve River basin in the Mid-Central region in Vietnam in November 2013, which caused widespread damage. The purpose of this paper was to establish the inundation maps in the downstream part of Tra Khuc-Ve rivers by using the coupling of the hydrological and hydraulic models (MIKE SHE/MIKE 11 and MIKE 11 GIS). Calibration and validation of the hydrological model were in good agreement in terms of the vibration amplitude, absolute value, and phases. The hydraulic model results showed good agreement between observed and simulated flood events in 2012 and 2013 after calibration and validation. The rainfall forecasting from the IFS model was also used to establish six flood warning scenarios based on the alarm level III (6.5 m) and the historical level (8.76 m). The inundation maps showed the extent of flooding and the water depth in the downstream part of the study area. The simulation results of historical data showed that Tu Nghia and Son Tinh Districts were the most affected areas by inundation with over 11% affected area while Quang Ngai Town inundated 8.1%. The study results will support decision makers in planning to reduce the impacts of natural disasters in Tra Khuc-Ve River basin in the future
Application Terrasar-X data for studying land subsidence in Hanoi City
No full textSAR Interferometry (InSAR) is a technique to measure land subsidence and can build a subsidence map on a large spatial scale with high accuracy. The study presented the application of PSInSAR for determining the subsidence of the central area of Hanoi through Terrasar-X data set from 2010 to 2015, with 23 images. The result shows that some area has the high subsidence in the districts of Hanoi such as Hoang Mai, Ha Dong and the slow subsidence such as Dong Da, Hai Ba Trung with subsidence velocity is less than -10mm/year. Besides, the correlation between ground subsidence measured by PSInSAR and subsidence monitoring of building CC02 Van Quan in Ha Dong district for the same period was computed with a correlation coefficient (R2) of 0.94. The PSInSAR technique can detect and estimate subsidence phenomena effectively with X-band.1
Kinematic and dynamic analysis of a serial manipulator with local closed loop mechanisms
Get PDFThis paper addresses the kinematic and dynamic modelling and analysis for a robot arm consisting of two hydraulic cylinders driving two revolute joints of the arm. The two cylinders and relevant links of the robot constitute two local closed kinematic chains added to the main robot mechanism. Therefore, the number of the generalized coordinates of the mechanical system is increased, and the mathematical modelling is more complex that requires a formulation of constraint equations with respect to the local closed chains. By using the Lagrangian formulation with Lagrangian Multipliers, the dynamic equations are first derived with respect to all extended generalized coordinates. Then a compact form of the dynamic equations is yielded by canceling the Multipliers. Since the obtained dynamic equations are expressed in terms of independent generalized coordinates which are selected according to active joint variables of the arm, the equations could be best suitable for control law design and implementation. The simulation of the forward and inverse kinematics and dynamics of the arm demonstrates the motion behavior of the robot system
Three new species of the spiral nematode genus helicotylenchus steiner, 1945 (nematoda: hoplolaimidae) from Vietnam
Get PDFInvestigations on entomopathogenic and plant parasitic nematodes in some natural forests in the Ngoc Linh mountain (Quang Nam province) and the Thuong Xuan forest (Thanh Hoa province) revealed three new species of plant parasitic nematodes belonging to the genus Helicotylenchus Steiner, 1945 (Nematoda: Hoplolaimidae). These new species were named Helicotylenchus castanus sp. n., Helicotylenchus madhucus sp. n. and Helicotylenchus digitus sp. n. with morphological characteristics described and illustrated. The new species Helicotylenchus castanus sp.n. is characterized by the highly hemispherical shape of the lip region, extremely short and rounded tail without projection. The second new species Helicotylenchus madhucus sp. n. is characterized by high lip region with 4-5 annuli, hemispherical and not set off from body contour, stylet 31.3-35.9 (33.3 ± 1.3) µm long, tail with a short ventral projection and the presence of males in the population. The third new species, Helicotylenchus digitus sp.n. was recognized by broad rounded tail with strong annulated projection in the digital shape, and also the presence of males in population.