Bivalves composition and ecological aspects of the Ba Lai River, an estuary of the Mekong Delta, Vietnam

Quang Xuan Ngo,Elena M. Sayenko,Konstantin A. Lutaenko 한국패류학회 2018 The Korean Journal of Malacology Vol.34 No.3

Benthic mollusk communities in the upper part of the Ba Lai River (the Mekong Delta), located upstream an irrigation dam, were investigated with respect to species composition, densities, biodiversity and some ecological aspects in 5 sampling stations. Densities of bivalve communities ranged from 21.5 ± 8.2 inds/10 cm2 to 28.5 ± 3.3 inds/10 cm2. In summary, 12 species from six Bivalvia families were recognised. Preliminary investigation on reproductivity of Corbicula blandiana showed the species is dioecious (specimens with separately female or male gonads were indicated), perhaps non-incubatory. Find of Meretrix lyrata, the most abundant commercial species in southern Vietnam, brings up a necessity on suitable policy and exploration in the Ba Lai to conserve valuable species for economic development and scientific purpose.

A Comprehensive Study on Fish Species Composition, Diversity, Migration, Threatened Status, Economic Value and Endemism in the Co Chien River, Ben Tre Province (Mekong Delta), Vietnam

Xuan-Dong Nguyen,Ngo Xuan Quang,Thanh Luu Pham,Bijeesh Kozhikkodan Veettil 한국해양과학기술원 2022 Ocean science journal Vol.57 No.1

The Mekong River Delta is a hotspot of aquaculture and fish biodiversity. In this study, fish community structure, migration, threatened status and economic value were investigated in the Co Chien River (COR) from August 2017 to July 2019. A total of 3640 fish specimens were collected from 11 sampling stations in the COR. These belong to 133 species of 107 genera of 58 families of 17 orders. The Perch-like order (Perciformes) is the most diverse group, with 65 species accounting for 48.87% of total species collected. The catfish order (Siluriformes) is the second-most diverse group with 15 species (11.28%) and the carps (Cypriniformes) with 14 species (10.53%) is the third. The remaining major groups in the order of diversity are the Herring (Clupeiformes) consisting of 9 species (6.77%) and the Flounder (Pleuronectiformes) consisting of 7 species (5.26%). The remaining orders have number of species varying from 1 to 3 (0.75–2.26%). Among the 133 species recorded, 6 species were considered as Vulnerable category based on the Vietnam Red Data Book (2007). According to the IUCN Red list (2021), 1 species (Coilia mystus) is Endangered (0.75%), 2 species (Maculabatis gerrardi and Pangasius krempfi) are Vulnerable (1.50%), 4 species are Near Threatened (3.01%), 6 species are Data deficient (4.51%), and 76 species are considered as Least concern (57.14%). The results shown that 79 species were migratory fishes (20 species migrated from the upstream and 59 species migrated from the sea), 41 species are endemic species for the MR (30.83% of the total species collected and 23.70% of total endemic species of the MR) and 36 fish species are considered as of local economic value (27.07%). The diversity of fish species was found to be more diverse in the dry season than the wet season, which indicates the influence of river water salinity changes on fish diversity in the region.

Numerical Analysis of a Compressor Type of Dehumidifier: (I) Fluid Flow

Xuan Quang Duong,정재동 대한설비공학회 2017 International Journal Of Air-Conditioning and Refr Vol.25 No.2

A three-dimensional simulation of a compressor dehumidifier was conducted by applying a porous model for condenser and evaporator, and a moving reference frame for the fan. A physical model was simulated for the unit cell of the actual shape of a fin-tube, and the parameters of viscous resistance and initial resistance were obtained. With these values, the porous model showed close agreement with the physical model within a reasonable computation time. A uniform flow across the evaporator and the condenser is desirable for high performance of the dehumidifier. Surface averaged velocity, standard deviation of velocity, and uniformity were chosen as indicators of the design object. A case study showed that two factors, (i) reducing the space between the evaporator and the condenser and (ii) introducing a cover to reduce the by-passing air flow, have the strongest influence on the air distribution in this dehumidifier.

압축식 제습기에 대한 수치해석 연구

Xuan Quang Duong,Huy Hai Nguyen,김규목(Kyu-Mok Kim),정재동(Jae Dong Chung) 대한설비공학회 2018 설비공학 논문집 Vol.30 No.2

A numerical analysis of a compressor dehumidifier has been conducted focusing on the air side heat transfer, which is a part of a series research on the dehumidifier. The moving reference frame was applied to the fan modeling, and the porous model was used for the evaporator and condenser modeling. Curve fitting obtained the inertial and viscous resistances parameters to the results of the physical model of the unit cell with actual shape of a fin tube. The porous model was validated within a reasonable computation time for the range of practical inlet velocity of a dehumidifier. A parametric study has been conducted for fin number, fan speed (i.e., air flow rate), and evaporator/ condenser tube arrangement. ANOVA analysis showed the dependency of each parameter on the velocity and temperature uniformity, which are desirable for high performance of the dehumidifier.

Biodiversity of Meiofauna in the Intertidal Khe Nhan Mudflat, Can Gio MangroveForest, Vietnam with Special Emphasis on Free Living Nematodes

Quang Ngo Xuan,and Nic Smol,Ann Vanreusel,Nguyen Vu Thanh 한국해양과학기술원 2007 Ocean science journal Vol.42 No.3

The ecological aspect of meiofaunal communities in Can Gio mangrove forest, Ho Chi Minh city, Vietnam has not been investigated before. The composition, distribution, density and biodiversity of meiofaunal communities were studied along an intertidal transect at the Khe Nhan mudflat. Each time, three replicate samples were collected in four stations along a transect following the water line from low tide level up to the mangrove forest edge. In total, 18 meiofaunal taxa were found with the dominant taxa belonging to Nematoda, Copepoda, Sarcomastigophora and Polychaeta. The densities of meiofauna ranged from 1156 inds/10 cm2 to 2082 inds/10 cm2. The increase in densities from the mangrove forest edge towards the low water line was significant. Along the mudflat transect, the biodiversity (expressed by different indices) was relatively high at different taxonomic levels but did not vary significantly along the mudflat except for taxa richness. Eighty nematode genera belonging to 24 families with Comesomatidae having the highest abundance 33.8 % were found. Theristus and Neochromadora decreased in densities from the lower water line towards the mangrove forest edge, while Paracomesoma and Hopperia are typical and more abundant at the middle of the mudflat. Halalaimus increased from high on the mudflat to the low water line.

Biodiversity of Meiofauna in thee Intertidal Khe Nhan Mudflat, Can Gio Mangrove Forest, Vietnam with Special Emphasis on Free Living Nematodes

Xuan, Quang-Ngo,Vanreusel, Ann,Thanh, Nguyen Vu,Smol, Nic The Korean Society of Oceanography 2007 Ocean science journal Vol.42 No.3

The ecological aspect of meiofaunal communities in Can Gio mangrove forest, Ho Chi Minh city, Vietnam has not been investigated before. The composition, distribution, density and biodiversity of meiofaunal communities were studied along an intertidal transect at the Khe Nhan mudflat. Each time, three replicate samples were collected in four stations along a transect following the water line from low tide level up to the mangrove forest edge. In total, 18 meiofaunal taxa were found with the dominant taxa belonging to Nematoda, Copepoda, Sarcomastigophora and Polychaeta. The densities of meiofauna ranged from $1156inds/10cm^2$ to $2082inds/10cm^2$. The increase in densities from the mangrove forest edge towards the low water line was significant Along the mudflat transect, the biodiversity (expressed by different indices) was relatively high at different taxonomic levels but did not vary significantly along the mudflat except for taxa richness. Eighty nematode genera belonging to 24 families with Comesomatidae having the highest abundance 33.8 % were found. Theristus and Neochromadora decreased in densities from the lower water line towards the mangrove forest edge, while Paracomesoma and Hopperia are typical and more abundant at the middle of the mudflat. Halalaimus increased from high on the mudflat to the low water line.

Heat Recovery Time of Adsorption Cooling System

Xuan Quang Duong,Ngoc Vi Cao,JAE DONG CHUNG 대한설비공학회 2018 International Journal Of Air-Conditioning and Refr Vol.26 No.2

In this study, a two-dimensional numerical model of finned-tube type adsorbers was developed and used to examine heat recovery time to improve the performance of an adsorption cooling system. The optimal heat recovery time, which resulted in the highest COP, was determined for a range of heat source temperatures (60–90 ∘ C) and cycle times (600–1200 s). The introduced heat recovery process enhanced COP, but also reduced SCP. This penalty became more serious when the hot water temperature was low and cycle time was short, which serves as a guideline for when heat recovery should be adopted in a given operating condition.

A portable surface-enhanced Raman scattering sensor integrated with a lab-on-a-chip for field analysis

Quang, Ly Xuan,Lim, Chaesung,Seong, Gi Hun,Choo, Jaebum,Do, Ki Jun,Yoo, Seoung-Kyo Royal Society of Chemistry 2008 Lab on a chip Vol.8 No.12

<P>An integrated real-time sensing system that uses a portable Raman spectrometer and a micropillar array chip has been developed for field analysis. The problem of poor detection sensitivity, caused by miniaturization in the portable Raman spectrometer, was overcome by using the surface-enhanced Raman scattering (SERS) technique. The problem of poor reproducibility in the SERS detection, caused by different particle sizes and inhomogeneous degrees of aggregation, was also overcome by using continuous flow and homogeneous mixing between the analytes and nanocolloidal silver in a micropillar array microfluidic chip. Two hazardous materials, dipicolinic acid and malachite green, were quantitatively analysed using our integrated portable Raman sensor system. The observed limit of detection was estimated to be 200 ppb and 500 ppb, respectively. Our proposed analytical method, using a micropillar array PDMS chip and a portable SERS system, offers a rapid and reproducible trace detection capability for hazardous materials in the field.</P> <P>Graphic Abstract</P><P>This paper represents a sensing system that uses a portable Raman spectrometer and a micropillar array chip. This offers a rapid and reproducible trace detection capability for hazardous materials in the field. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b808835g'> </P>

Non-Uniform Velocity Effect to the Performance of Adsorption Cooling

Xuan Quang Duong,Ngoc Vi Cao,Woo Su Lee(이우수),Jae Dong Chung(정재동) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12

Cytotoxic Oleane-type Triterpene Saponins from Glochidion eriocarpum

Nguyen Xuan Nhiem,김영호,Vu Kim Thu,Phan Van Kiem,Chau Van Minh,Bui Huu Tai,TRANHONG QUANG,Nguyen Xuan Cuong,Pham Hai Yen,Hye-Jin Boo,강정일,강희경 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.1

The anticancer activity of ten compounds from the aerial parts of Glochidion eriocarpum were evaluated on two human cancer cell lines, HL-60 and HCT-116. Compounds 1-4 displayed highly potent cytotoxic activity on the HCT-116 cancer cell line with IC50 values ranging of 0.41~1.16 μM. Compounds 1-4 significantly inhibited the HL-60 cell line with IC50 values ranging of 4.51~6.33 μM. These results suggested that the benzoyl group at the C-22 position in oleane-type triterpene saponins was essential for cytotoxicity towards tumor cells. Moreover, compounds 2 and 3 showed more potent cytotoxicity than compounds 1 and 4 against HL-60 and HCT-116 cells. With respect to the mechanism underlying cytotoxicity, compounds 1-4 increased chromatin condensation, a typical apoptotic characteristic in HL-60 and HCT-116 cells. In the mechanism of apoptosis induction, compounds 1-4 reduced Bcl-2expression, whereas the expression of Bax was increased compared to controls in HCT-116 cells. In addition, compounds 1-4 decreased the level of procaspase-3. The cleavage of poly (ADP-ribose) poly merase (PARP), a vital substrate of effector caspase, was observed in HCT-116 cells. Furthermore, the induction of apoptosis was also accompanied by an activation of extracellular signal-regulated kinase (ERK) and p38 kinase in HCT-116 cells. These findings provide evidence demonstrating that the pro-apoptotic effects of compounds 1-4 are mediated through the activation of ERK and p38 in HCT-116 cells.