http://stdj.scienceandtechnology.com.vn/index.php/stdj/issue/feed Science and Technology Development Journal 2019-03-24T00:04:46+00:00 Phuc Van Pham pvphuc@vnuhcm.edu.vn Open Journal Systems http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1009 In vitro α-glucosidase inhibitory activity of compounds isolated from mangrove Lumnitzera littorea leaves 2019-03-24T00:04:46+00:00 http://stdj.scienceandtechnology.com.vn/public/journals/2/article_1009_cover_en_US.png Thuy Thi Le Nguyen thuy.ntl@ou.edu.vn Thuy Thi Pham thuyphamhcmup@gmail.com Poul Erik Hansen poulerik@ruc.dk Phung Kim Phi Nguyen kimphiphung@yahoo.fr <p><strong>Introduction</strong>: Lumnitzera littorea grown at CanGio Mangrove Forest has been investigated. The present study reports the isolation, characterization and evaluation of the alpha-glucosidase inhibitory activity of isolated compounds from Lumnitzera littorea leaves.</p> <p><strong>Methods</strong>: Their structures were elucidated by spectroscopic methods (including MS, 1D and 2D–NMR) and comparison with values from the literature. From the n-hexane extract, nine compounds including lupeol (<strong>1</strong>), betulin (<strong>2</strong>), betulinic acid (<strong>3</strong>), oleanolic acid (<strong>4</strong>), corosolic acid (<strong>5</strong>), -sitosterol (<strong>6</strong>), beta-sitosterol 3-O- beta-D-glucopyranoside (<strong>7</strong>), stigmast-5-ene-3beta-O-(6-O-hexadecanoyl-beta-D-glucopyranoside) (<strong>8</strong>), and stigmast-4-ene-3-one (<strong>9</strong>) were isolated and identified.</p> <p><strong>Results</strong>: The results of the alpha-glucosidase inhibitory activity showed thatcorosolic acid (5) and oleanolic acid (4) were the most potent, with IC<sub>50</sub> values of 17.86 +/- 0.42 and 18.82 +/- 0.59 ug/mL, respectively. Five of the other seven compounds exhibited inhibitory activity with IC<sub>50</sub> values below 100 ug/mL, and higher than the positive control acarbose (127.64 +/- 0.64 ug/mL).</p> <p>&nbsp;</p> 2019-01-07T00:00:00+00:00 ##submission.copyrightStatement## http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/837 Physical and electrochemical properties of mixed electrolyte 1-ethyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)imide and ethylene carbonate as electrolytes for Li-ion batteries 2019-03-24T00:04:42+00:00 http://stdj.scienceandtechnology.com.vn/public/journals/2/article_837_cover_en_US.png Linh Thi-My Le phamvanphuc2308@gmail.com Thanh Duy Vo phamvanphuc2308@gmail.com Hoang Van Nguyen phamvanphuc2308@gmail.com Quan Phung phamvanphuc2308@gmail.com Man Van Tran phamvanphuc2308@gmail.com Phung My Loan Le lmlphung@hcmus.edu.vn <p><strong>Introduction</strong>: Ionic liquids (ILs) have become a prospective candidate to replace the conventional electrolytes based on the volatile organic-solvents in lithium-ion batteries. However, the drawbacks of high viscosity and low ionic conductivity have restricted the high rate capacity and energy density in practical batteries. With the aims to resolve these problems and design a safe electrolytes with high electrochemical stability, mixtures of ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (EMITFSI) with different amounts of ethylene carbonate (EC) was prepared and characterized as electrolytes for Li-ion batteries.</p> <p><strong>Methods</strong>: In this work, we investigated four factors to demonstrate the performance of EMITFSI as electrolytes for Li-ion batteries. These factors include: thermal properties of mixed electrolytes (Mettler Toledo DSC1 Star -DSC, Q500-TGA), Conductivity (HP- AC impedance spectroscopy), Viscosity (Ostwald viscometer CANNON) and electrochemical window (cyclic voltammetry-MGP2 Biologic Instrument). All experiments were repeated three times with the exception of TGA-DSC methods.</p> <p><strong>Results</strong>: The study indicated that 20 % wt. ethylene carbonate (EC) when mixed with EMITFSI could significantly decrease the electrolyte viscosity while improving ionic conductivity and maintain similar electrochemical stability as pure ionic liquid. Lithium diffusion coefficient of mixed electrolytes was lower than commercial electrolytes based on conventional solvents, however, the thermal stability was enhanced.</p> <p><strong>Conclusion</strong>: EMITFSI can be used to replace conventional carbonate-based liquids as a high-performance electrolyte for Li-ion batteries.</p> <p>&nbsp;</p> 2019-02-25T00:00:00+00:00 ##submission.copyrightStatement## http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1010 Phenolic compounds from Pamotrema dilatatum growing in Lam Dong province 2019-03-24T00:04:45+00:00 http://stdj.scienceandtechnology.com.vn/public/journals/2/article_1010_cover_en_US.png Huy Thuc Duong thuchuy84@yahoo.com <p><strong>Introduction</strong>: Only chemical study on the lichen Parmotrema dilatatum was found so far in the world. The lichen Parmotrema dilatatum widely distributed in Lam Dong province, Vietnam has been studied about the isolation and elucidation of several metabolites.</p> <p><strong>Methods</strong>: Phytochemical study on the polar fractions of this lichen was carried out by using various chromatographic methods including thin-layer chromatography and normal phase silica gel chromatography.</p> <p><strong>Results</strong>: Eight phenolic compounds were isolated. The chemical structures of isolated compounds were unambiguously elucidated by NMR spectroscopy and comparison with the data in the literature. These are 8'-O-methylsalazinic acid, salazinic acid, 8'-O-methylprotocetraric acid, diffractaic acid, lecanorin, lecanoric acid, isolecanoric acid, and diorcinolic acid.</p> <p><strong>Conclusion</strong>: Among them, 8'-O-methylsalazinic acid was found as a new natural product.</p> <p>&nbsp;</p> 2019-01-26T02:30:05+00:00 ##submission.copyrightStatement## http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1661 Long-term expansion enhances the expression of tumor suppressor genes in human bone marrow-derived mesenchymal stem cells 2019-03-24T00:04:41+00:00 http://stdj.scienceandtechnology.com.vn/public/journals/2/article_1661_cover_en_US.png Loan Thi Tung Dang phamvanphuc2308@gmail.com Anh Thi Van Bui phamvanphuc2308@gmail.com Nhat Chau Truong phamvanphuc2308@gmail.com Huy Duc Van phamvanphuc2308@gmail.com Phuc Van Pham pvphuc@hcmuns.edu.vn <p><strong>Introduction</strong>: Mesenchymal stem cells (MSCs) are possibly the most potent type of stem cells for the treatment of many diseases since they possess many advantageous properties, such as abundant source, ease of isolation, and potential to differentiate and trans-differentiate into different types of cells. Although the therapeutic potential of expanded MSCs has been well proven, their biosafety features have not been fully understood. This study aimed to investigate some changes in phenotype and gene expression of bone marrow derived MSCs after long term expansion.</p> <p><strong>Methods</strong>: In this study, expanded mesenchymal stem cells derived from human bone marrow (hBMSCs) were identified for their characteristics (which included morphology, immunophenotype, and differentiation potential) at passages 5, 10 and 15. Moreover, they were evaluated for the expression of various tumor suppressor genes (PTEN, p16, and p53) by real-time RT-PCR.</p> <p><strong>Results</strong>: The results showed that the hBMSCs at passage 15 displayed a change in morphology and a slight reduction of the expression of CD44 and CD90, whereas their potential for adipogenic and osteogenic differentiation was maintained. Moreover, the expression of tumor suppressor genes in the hBMSCs increased after long-term culture.</p> <p><strong>Conclusion</strong>: It could be assumed that prolonged cultures of more than 15 passages drove the hBMSCs into senescence phase. Cultured hBMSCs below passage 10 seemed to be more effective in application because their properties were still preserved.</p> <p>&nbsp;</p> 2019-03-21T22:51:11+00:00 ##submission.copyrightStatement## http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1020 Copolymerization of n-butyl acrylate/methyl methacrylate in xylene solvent 2019-03-24T00:04:44+00:00 http://stdj.scienceandtechnology.com.vn/public/journals/2/article_1020_cover_en_US.png Nguyen-Vu Viet Linh nguyenvuvietlinh@hcmut.edu.vn Nguyen Trung Duc phamvanphuc2308@gmail.com Huynh Dai Phu hdphu@hcmut.edu.vn <p><strong>Introduction</strong>: Copolymers are being used in a variety of fields because of their diversity and since any change could result in significant modifications. The butyl acrylate/methyl methacrylate copolymer is an extensively used polymer system with many advantages. This study aims to analyze some changes in copolymerization, from using different time or temperature of synthesis, in order to find an optimal process that can be applied in Vietnam.</p> <p><strong>Methods</strong>: Copolymerization of butyl acrylate/methyl methacrylate copolymer with different butyl acrylate/methyl methacrylate monomer ratios was done using Xylene solvent. Copolymer compositions were determined from the Proton nuclear magnetic resonance spectra and Gel permeation chromatography.</p> <p><strong>Results</strong>: The experimental results indicate that the copolymer was successfully synthesized. The highest molecular weight was 15,591 g/mol, with the lowest dispersity of 1.53 at 100<sup> o</sup>C after 6 hours of copolymerization.</p> <p>&nbsp;</p> 2019-02-17T00:00:00+00:00 ##submission.copyrightStatement##