Vietnam Academy of Science and Technology: Journals Online
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In silico Probing Ca2+ And Zn2+ Permeable Transmembrane 4Aβ1-42 Barrel
No full textAlzheimer’s disease is known as one of the most popular forms of dementia affecting numerous people worldwide. The Amyloid beta (Aβ) peptides form to oligomeric conformations that cause the intracellular Ca2+ and Zn2+ abnormality leading to the death of neuron cells. The failure of AD therapy targeting Aβ oligomers probably caused by misunderstanding the ions transport through transmembrane Aβ (tmAβ) ion-like channel since Aβ oligomers transiently exist in a mixture order of Aβ oligomers. The high-resolution of tmAβ peptides are thus unavailable until the date. Fortunately, computational approaches are able to complement the missing experimental structures. The transmembrane 4Aβ1-42 (tm4Aβ1-42) barrel, one of the most neurotoxic elements, was thus predicted in the previous work. Therefore, in this context, the Ca2+/Zn2+ ions transport through the tm4Aβ1-42 barrel was investigated by using the fast pulling of ligand (FPL) and umbrella sampling (US) methods. Good consistent results were obtained implying that Ca2+ ion transport through tm4Aβ1-42 barrel with a lower free energy barrier compared with Zn2+ ion. The obtained results about Ca2+/Zn2+ transport across tmAβ1-42 barrel probably enhances the AD therap
EFFECT OF EXTRACTION SOLVENTS ON QUALITY OF VIETNAMESE TEA (Camellia sinensis O.Kuntze) SEED OIL
No full textTea (Camellia sinesis) seed oil (TSO) is one of high-quality vegetable oils, similar to olive oil with high portion of unsaturated fatty acids, especially essential linoleic acid and low content of saturated fat. Solvent extraction method was used to obtain not only oil but also natural compounds from raw material. This study provides data on the physicochemical properties of TSO extracted from Trung du variety, cultivated in Phu Tho, Vietnam.
The toxicity of lead to the freshwater microalgae Scenedesmus and the water flea Daphnia carinata
No full textSai Gon river is the important source for water supply in Ho Chi Minh City. However, its water quality is degrading gradually due to rapid population growth, increasing of urbanization and industrialization. The river is continuously loaded with xenobiotics released by anthropogenic activities. Among pollutants, heavy metals are considered as the most toxic elements to aquatic living organisms and human health. The aim of this study is to assess the sensibility of freshwater microalgae Scenedesmus and water flea Daphnia carinata, two fresh water species from Viet Nam to lead (Pb). After physical and chemical characterization, field water samples from the upstream of Sai Gon River was used as dilution water in toxicity tests. With water flea D. carinata, the EC50 value of 48h immobilization experiment was 121.64 µg/L for Pb. Growth inhibition of the algae cells was determined following exposure for 96 h, and EC50 values of Pb was 14,767.9 µg/L. The results showed that Pb was highly toxic to D. carinata, and harmful to freshwater algae Scenedesmus. Based on the observed high sensitivity with Pb, D. carinata is a potential bioindicator for the assessment of Pb pollution in Sai Gon river. While lead-tolerance algae Scenedesmus calls for further investigation on metal uptake capacity and utilization in Pb contaminated water treatmen
Microplastic contamination in commercial sea salt of Vietnam
No full textThis is the first study which assessed the microplastic pollution of sea salt products from Vietnam. The results obtained from 9 iodate fine table sea salt and 4 raw sea salt samples collected from different regions in Vietnam showed that microplastic were present in 100% of the salts samples. The mean concentration of microplastic was 787±101 items/kg and 340±26 items/kg for raw and fine sea salts, respectively. For both raw and fine sea salt, fibers were the predominant type of microplastic, accounted more 60% of total microplastic particles. In added, three types of polymer were detected in 12 microplastic particles by FTIR, including polyethylene (PE), polypropylene (PP) and polystyrene, in which, the most common is PE (accounted 67%). With a mean daily salt consumption of 5-10g/day, the annual number of microplastic particles ingested per Vietnamese adult varies from 637 to 1241 particles from salt alone
Normed Division Algebras Application to the Monopole Physics
No full textWe review some normed division algebras (R, C, H, O) applications to the monopole physics and MICZ-Kepler problems. More specifically, we will briefly review some results in applying the normed division algebras to interpret the existence of Dirac, Yang, and SO(8) monopoles. These monopoles also appear during the examination of the duality between isotropic harmonic oscillators and the MICZ-Kepler problems. We also revisit some of our newest results in the nine-dimensional MICZ-Kepler problem using the generalized Hurwitz transformation
Aggregation of Zoospores on Sharklet Microtopographic Surfaces
No full textSurfaces with engineered microtopographies are potential candidate against biofouling to replace the use of biocides in the marine environment. Understanding the antifouling mechanism of microtopographic surfaces against marine microorganisms, however, has been limited. In this work, we theoretically studied the aggregation of Ulva linza zoospores on the Sharklet topographic surfaces by employing the extended Surface Energetic Attachment (SEA) model proposedin a previous work. The energy parameters of the model were obtained by matching theoretical results with experimental data for one type of Sharklet surface. Monte Carlo simulations were then carried out for a series of Sharklet surfaces with various numbers of distinct features. Inagreement with prior experimental results, our simulations indicate that engineered topographies promote smaller aggregates than those on a smooth surface. Furthermore, we show that the maximum effect of the Sharklet topography on the aggregate size of U. linza can be obtained with just 3 distinct features
Earthworms (Annelida: Oligochaeta) of the Con Dao archipelago
No full text The earthworms of the Con Dao archipelago are investigated based on literature and newly collected specimens. A total of 16 species belonging to seven genera in three families are documented in Con Son and Bay Canh islands. The species, Polypheretima grandisetosa (Thai, 1996) is re-described from holotype and freshly collected specimens. All species are imaged for recognition. An identification key to all earthworm species is provided for the Con Dao archipelago.
ISOLATION, PURIFICATION AND STRUCTURAL CHARACTERISTICS OF GLYCOSAMINOGLYCANS FROM SEA CUCUMBER STICHOPUS HORRENS
No full textSea cucumber glycosaminoglycans have been well known as potential anticoagulant and antithrombin agents. In this investigation, glycosaminoglycans were isolated from sea cucumber Stichopus horrens by papain enzymatic digestion. Crude glycosaminoglycans were fractionated and purified by using anion-exchange chromatography on the DEAE-Macro Prep column to give two fractions of fucosylated chondroitin sulfate (FCS1) and fucan sulfate (FS2). Structural characteristics of F1 and F2 fractions were elucidated using chemical and IR, NMR spectroscopic methods. The results showed that the monosaccharide compositions of FCS1 consist of N-Acetyl-Galactosamine (GlcNAc), D-Glucuronic acid (GlcA) and Fucose (Fuc) residues with different molar ratios, while FS2 content only fucose residues. Sulfate contents of FCS1 and FS2 were 47.4% and 48.1%, respectively. FCS1 and FS2 fractions were different in the pattern of sulfation of N-Acetyl-Galactosamine and fucose residues. IR and NMR spectra of two frations showed that sulfate groups were primarily occupied at C4 of pyranose residues in FS2 and C6, C2 and/or C3 of pyranose residues in FCS1 fraction. Our results contributed to knowledge on structural types of glycosaminoglycan from sea cucumbers in Vietnam. The establishment of structural features plays an important role in further studies of the structure-bioactivity relationship of sea cucumber glycosaminoglycan
Study on distribution characteristics of wind speed field in the sea area of Ly Son island of Quang Ngai province
No full textOn the basis of the data source of the 10 m wind field above the sea with the hourly frequency and during the period of 41 years (1979–2019) by the NCEP CFRS, we used the probability distribution functions to study the distribution law of wind speed in the waters of Ly Son island. Specifically, four distribution functions (normal distribution, gamma distribution, Weibull distribution and extreme value distribution) were used to estimate the characteristic parameters of the shape and proportion of the wind distribution in the waters of Ly Son island
A TIME SERIES FORECASTING MODEL BASED ON LINGUISTIC FORECASTING RULES
No full textThe fuzzy time series (FTS) forecasting models have been being studied intensively over the past few years. Most of the researches focus on improving the effectiveness of the FTS forecasting models using time-invariant fuzzy logical relationship groups proposed by Chen et al. In contrast to Chen’s model, a fuzzy set can be repeated in the right-hand side of the fuzzy logical relationship groups of Yu’s model. N. C. Dieu enhanced Yu’s forecasting model by using the time-variant fuzzy logical relationship groups instead of the time-invariant ones. The forecasting models mentioned above partition the historical data into subintervals and assign the fuzzy sets to them by the human expert’s experience. N. D. Hieu et al. proposed a linguistic time series by utilizing the hedge algebras quantification to converse the numerical time series data to the linguistic time series. Similar to the FTS forecasting model, the obtained linguistic time series can define the linguistic, logical relationships which are used to establish the linguistic, logical relationship groups and form a linguistic forecasting model. In this paper, we propose a linguistic time series forecasting model based on the linguistic forecasting rules induced from the linguistic, logical relationships instead of the linguistic, logical relationship groups proposed by N. D. Hieu. The experimental studies using the historical data of the enrollments of University of Alabama observed from 1971 to 1992 and the daily average temperature data observed from June 1996 to September 1996 in Taipei show the outperformance of the proposed forecasting models over the counterpart ones