Development of a Filament Extruder Using Flow Theory with the Newtonian Fluid Assumption

This article presents an investigation of the flow characteristics of the polymer melt in a single-screw extruder and the design of a filament extruder to verify the above theory. The flow characteristics of the polymer melt in a single-screw extruder are likable to that of a viscous liquid between two infinitely parallel sheets, one moving and the other stationary. An integrated flow equation was then found for a case when the viscosity of a liquid remains constant in an isothermal extrusion. These flow behavior theories were then verified via the design and fabrication of a filament extruder for 3D printers

POPULATION GENETIC DIVERSITY OF CAMELLIA DILINHENSIS ON THE DI LINH PLATEAU OF VIETNAM REVEALED BY ISSR AND SCOT MARKERS

Genetic diversity of naturally distributed Camellia dilinhensis populations on the Di Linh plateau of Vietnam was assessed by the inter-simple sequence repeat (ISSR) and start codon targeted (SCoT) techniques separately and then by combining data from both techniques for satisfactory results. The genetic diversity parameters and genetic distances among individuals found with the ISSR technique (HeI = 0.1420, II = 0.2092, PPBI = 35.22%, GSCsI = 0.765–0.988, and AGSCI = 0.915) are lower than those found with the SCoT technique (HeS = 0.2100, IS = 0.381, PPBS = 52.27%, GSCsS = 0.644–0.985, and AGSCS = 0.866). Based on the combined data from both techniques, the level of genetic diversity of the investigated population is PPB = 43.77%, He = 0.1720, I = 0.2582, and the genetic similarities among individuals are GSCs = 0.764–0.973 with an average of AGSC = 0.894. The SCoT technique differentiated between individuals better and reflected a higher level of genetic diversity in the population than the ISSR technique, but the ISSR technique revealed more loci in Camellia dilinhensis plants than did the SCoT technique

Development of a Filament Extruder Using Flow Theory with the Newtonian Fluid Assumption

This article presents an investigation of the flow characteristics of the polymer melt in a single-screw extruder and the design of a filament extruder to verify the above theory. The flow characteristics of the polymer melt in a single-screw extruder are likable to that of a viscous liquid between two infinitely parallel sheets, one moving and the other stationary. An integrated flow equation was then found for a case when the viscosity of a liquid remains constant in an isothermal extrusion. These flow behavior theories were then verified via the design and fabrication of a filament extruder for 3D printers

THE SPECIES COMPOSITION IN CATCHES OF GILL-NET IN THE COASTAL AND INSHORE AREA OF BENTRE PROVINCE, VIETNAM

and analyzed. The result of study shows that 105 species belonging to 77 genera and 42 orders have been encountered. In which, demersal fish with 45 species (42.9%), 21 species of pelagic fish (20.0%); 18 species of reef-associated fish (17.1%); shrimps with 14 species (13.3%); crabs with 4 species (3.8%); 2 species of cephalopods (1.9%) and 1 species of seahorse crab (1.0%). In terms of catch composition, the croaker (Sciaenidae), the lizardfishs (Synodontidae) and Anchovies (Engraulidae) dominated with yields up to 60% of the total catch. In terms of species with high economic value and dominant in catches were Bombay duck (Harpadon nehereus), Sodier croaker (Nibea soldado) and Green mub crab (Scylla paramamosain) which were play an important economic species and high proportion of the total income

Geographical variation in morphological leaf traits of Huperzia serrata (lycopodiaceae) from Vietnam

Morphological leaf traits can be used to assess adaptive responses of plants to environmental conditions. To assess how the representation of Huperzia serrata leaf traits, such as leaf length (LL), leaf width (LW) and leaf area (LA) response to changes in mean annual temperature (MAT), sunshine duration (SuH), mean annual precipitation (MAP), air humidity (Hu), intraspecific variation of the morphological leaf traits of the species was analyzed along a geographical gradient of Vietnam. The results showed that among the three populations at the three sites, leaf sizes increased with MAT and MAP. Huperzia serrata, climatic factors, morphological leaf traits, Vietnam.

Parameter optimization of tuned mass damper for three-degree-of-freedom vibration systems

There are problems in mechanical, structural and aerospace engineering that can be formulated as Nonlinear Programming. In this paper, the problem of parameters optimization of tuned mass damper for three-degree-of-freedom vibration systems is investigated using sequential quadratic programming method. The objective is to minimize the extreme vibration amplitude of vibration models. It is shown that the constrained formulation, that includes lower and upper bounds on the updating parameters in the form of inequality constraints, is important for obtaining a correct updated model

Inverse analysis for transmissivity and the Red river bed's leakage factor for Pleistocene aquifer in Sen Chieu, Hanoi by pumping test under the river water level fluctuation

Aquifer parameters and riverbed hydraulic resistance to an aquifer have an important role in the quantitative assessment of groundwater sources, especially the aquifer recharge from river. The analytical determination of aquifer parameters and riverbed hydraulic resistance to the aquifer is rather complicated in case if the water level in the river fluctuates before and during the pumping test time. This is especially true for Pleistocene aquifer along the Red River in Hanoi city, where the riverbed has been changed very much during the recent decades. A trial-error inverse analysis in the parameters' determination by a group pumping test data obtained with a test located close to the Red river bank in Sen Chieu area, Phuc Tho district, Hanoi city was carried out. Before and during the pumping test time the water level in the river changed five times. The results have shown that the Pleistocene aquifer has a relatively high hydraulic conductivity of 55.5 m/day, which provides a good role in the transport of a large volume of water recharged by the river to the abstraction wells located near the river. The aquifer storage coefficient had lightly decreased with the pumping time, which is corresponding to the physical nature of that the aquifer stativity is a function of the aquifer pressure. A special point is worthwhile to be noted that the Red river bed resistance to the Pleistocene is very low, about 0.537 days, which is corresponding to the increase of the distance from the river bank further from the well in 28.4 m to have the river as a specified water level boundary of the aquifer. In contrast, the 1990's investigations had found that the Red river bed resistance to the Pleistocene aquifer to be about 130 days (Tran Minh, 1984), which is corresponding to the increase of the distance from the river bank further from the well in a thousand of meters to have the river as a specified water level boundary for the aquifer.ReferencesChristensen S., 2000. On the estimation of stream flow depletion parameters by drawdown analysis. Ground Water, 38(5), 726-734. Fetter C.W., 2001. Applied Hydrogeology. Prentice Hall-Upper Saddle River, NJ 07458. Fletcher G. Driscoll., 1987. Groundwater and Wells. Published by Johnson Division, St. Paul, Minnesota 55112, USA.Fox G.A., 2004. Evaluation of a stream aquifer analysis test using analytical solutions and field data. Journal of the American Water Resources Association. 40(3), 455-763. Hunt B., Wei J. and Clausen B., 2001. A stream depletion field experiment. Ground Water 39(2), 283-289. John H. Cushman and Daniel M. Tartakovsky (Editors), 2017. The Handbook of Groundwater Engineering. Third Edition. CRC Press. Taylors Francis Group. 6000 Broken Sound Parkway NW, Suite 300.Lough H.K. and Hunt B., 2006. Pumping test evaluation of stream depletion parameters. Ground Water. Jul-Aug, 44(4), 540-546. Mironhenco V.A. and Shestakov V.M., 1974. Fundamentals of hydromechanics. Publishers "Nedra", Moscow, Russia. Ne-Zheng Sun, 1994. Inverse Problems in Groundwater Modeling. Cluwer Academic Publishers. Nguyen Minh Lan, 2014. Report on "Study of the relationship between the Red river and groundwater, proposal of methods of determination of groundwater abstraction potential along the Red river from Son Tay to Hung Yen". Code: TNMT.02.33. Nguyen Quoc Thanh and Nguyen Van Hoang, 2007. Hydrogeomechanical processes affecting the stability of Red river dike's foundation and in the Son Tay-Ha Noi area. Hanoi Geoengineering 2007. International Conference Proceedings, 120-123. Nguyen The Chuyen, Vu Ngoc Duc, Dao Trong Tu, Nguyen Van Hoang, 2017. Study on determination of effective porosity and longitudinal dispersivity of aquifer and the application to field tracer injection test in Mo Lao, Ha Dong area, Hanoi, Vietnam. Vietnam National University Journal of Science, 33(1), 1-15. Nguyen Van Giang, Nguyen Ba Duan, Le Ngoc Thanh, Noboru Hida, 2014. Hydro-geophysical Techniques to Aquifer Locating and Monitoring for Industrial zone north Thang Long and Quang Minh, Hanoi. Vietnam J. Earth Sci., 36(3), 221-232. Doi: 10.15625/0866-7187/36/3/5905. Nguyen Van Hoang, 2016. Modelling of water pollution. Vietnam Academy of Science and Technology Publishers. Pham Dinh, 2016. Report on "Study of the effects of the sand and gravel excavation in the Red river and Thai Binh river system on the flow regime and bed load regime for supporting sustainable management and planning of sand and gravel excavation" code ĐTĐL.2012-T/27. Vietnam Academy of Water Resources. Sophocleous M., 2001. Interactions between groundwater and surface water: the state of the science. Hydrogeology Journal, 10, 52-67. Tong Ngoc Thanh, Trieu Duc Huy, Nguyen Van Kenh, Tong Thanh Tung,  Pham Ba Quyen, Nguyen Van Hoang, 2017. Methodology of determining effective porosity and longitudinal dispersivity of aquifer and the application to field tracer injection test in Southern Hanoi, Vietnam. Vietnam J. Earth Sci., 39(1), 57-75. Doi: 10.15625/0866-7187/39/1/9228. Tran Minh, 1984. Report on "Results of groundwater investigation in Hanoi area". Northern Union for Water Resources Planning and Investigation. Trieu Duc Huy (Project head), 2015. Proposal "Groundwater protection in large cities (Hanoi city)" and the project's implementation data and materials. Vietnam National Center for Water Resources Planning and Investigation. Vu Tat Uyen and Le Manh Hung, 2011. Warning on the consequences of sand and gravel excavation in the Red river more than the annual bed load supply. Journal of Water Resources Science and Technology, 3, 2-6

Potential involvement of oxidative stress in cartilage senescence and development of osteoarthritis: oxidative stress induces chondrocyte telomere instability and downregulation of chondrocyte function

Oxidative stress leads to increased risk for osteoarthritis (OA) but the precise mechanism remains unclear. We undertook this study to clarify the impact of oxidative stress on the progression of OA from the viewpoint of oxygen free radical induced genomic instability, including telomere instability and resulting replicative senescence and dysfunction in human chondrocytes. Human chondrocytes and articular cartilage explants were isolated from knee joints of patients undergoing arthroplastic knee surgery for OA. Oxidative damage and antioxidative capacity in OA cartilage were investigated in donor-matched pairs of intact and degenerated regions of tissue isolated from the same cartilage explants. The results were histologically confirmed by immunohistochemistry for nitrotyrosine, which is considered to be a maker of oxidative damage. Under treatment with reactive oxygen species (ROS; 0.1 μmol/l H(2)O(2)) or an antioxidative agent (ascorbic acid: 100.0 μmol/l), cellular replicative potential, telomere instability and production of glycosaminoglycan (GAG) were assessed in cultured chondrocytes. In tissue cultures of articular cartilage explants, the presence of oxidative damage, chondrocyte telomere length and loss of GAG to the medium were analyzed in the presence or absence of ROS or ascorbic acid. Lower antioxidative capacity and stronger staining of nitrotyrosine were observed in the degenerating regions of OA cartilages as compared with the intact regions from same explants. Immunostaining for nitrotyrosine correlated with the severity of histological changes to OA cartilage, suggesting a correlation between oxidative damage and articular cartilage degeneration. During continuous culture of chondrocytes, telomere length, replicative capacity and GAG production were decreased by treatment with ROS. In contrast, treatment with an antioxidative agent resulted in a tendency to elongate telomere length and replicative lifespan in cultured chondrocytes. In tissue cultures of cartilage explants, nitrotyrosine staining, chondrocyte telomere length and GAG remaining in the cartilage tissue were lower in ROS-treated cartilages than in control groups, whereas the antioxidative agent treated group exhibited a tendency to maintain the chondrocyte telomere length and proteoglycan remaining in the cartilage explants, suggesting that oxidative stress induces chondrocyte telomere instability and catabolic changes in cartilage matrix structure and composition. Our findings clearly show that the presence of oxidative stress induces telomere genomic instability, replicative senescence and dysfunction of chondrocytes in OA cartilage, suggesting that oxidative stress, leading to chondrocyte senescence and cartilage ageing, might be responsible for the development of OA. New efforts to prevent the development and progression of OA may include strategies and interventions aimed at reducing oxidative damage in articular cartilage

VBD-MT Chinese-Vietnamese Translation Systems for VLSP 2022

We present our systems participated in the VLSP 2022 machine translation shared task. In the shared task this year, we participated in both translation tasks, i.e., Chinese-Vietnamese and Vietnamese-Chinese translations. We build our systems based on the neural-based Transformer model with the powerful multilingual denoising pre-trained model mBART. The systems are enhanced by a sampling method for backtranslation, which leverage large scale available monolingual data. Additionally, several other methods are applied to improve the translation quality including ensembling and postprocessing. We achieve 38.9 BLEU on ChineseVietnamese and 38.0 BLEU on VietnameseChinese on the public test sets, which outperform several strong baselines

Gravity terrain correction for mainland territory of Vietnam

Terrain corrections for gravity data are a critical concern in rugged topography, because the magnitude of the corrections may be largely relative to the anomalies of interest. That is also important to determine the inner and outer radii beyond which the terrain effect can be neglected. Classical methods such as Lucaptrenco, Beriozkin and Prisivanco are indeed too slow with radius correction and are not extended while methods based on the Nagy’s and Kane’s are usually too approximate for the required accuracy. In order to achieve 0.1 mGal accuracy in terrain correction for mainland territory of Vietnam and reduce the computing time, the best inner and outer radii for terrain correction computation are 2 km and 70 km respectively. The results show that in nearly a half of the Vietnam territory, the terrain correction values ≥ 10 mGal, the corrections are smaller in the plain areas (less than 2 mGal) and higher in the mountainous region, in particular the correction reaches approximately 21 mGal in some locations of northern mountainous region. The complete Bouguer gravity map of mainland territory of Vietnam is reproduced based on the full terrain correction introduced in this paper