Pub Date : 2019-03-29DOI: 10.32508/STDJ.V22I1.1230
T. Vo, T. M. Phung, Hoang Quoc Duy Hoang Truong, L. Nguyen, O. H. Nguyen, P. Le
Introduction: Polymers acting as both an electrolyte and a separator are of tremendous interest because of their many virtues, such as no leakage, flexible geometry, excellent safe performance, and good compatibility with electrodes, compared with their liquid counterparts. In this study, polymer electrolyte membranes comprising of poly(vinylidene fluorine-co-hexafluoropropylene) [PVDF-HFP] were plasticized with different mass ratios of poly(ethylene oxide) (PEO) in 1 M NaClO4/PC solutions, and were prepared and characterized in sodium-ion battery. Methods: Polymer electrolyte membranes were prepared by solution-casting techniques. The membranes' performance was evaluated in terms of morphology, conductivity, electrochemical stability, thermal properties and miscibility structure. The following various characterization methods were used: Scanning Electron Microscopy (SEM), impedance spectroscopy (for determination of electrolyte resistance), cyclic voltammetry, thermal degradation analysis, and infra-red spectroscopy (for determination of structure of co-polymer). Results: It was indicated that the PVDF-HFP/PEO membrane with 40 % wt. PVDF-HFP absorbed electrolytes up to 300 % of its weight and had a roomtemperature conductivity of 2.75 x 10-3 Scm-1, which was better than that of pure PVDF-HFP. All polymer electrolyte films were electrochemically stable in the potential voltage range of 2-4.2 V, which could be compatible with 3-4 V sodium material electrodes in rechargeable sodium cells. Conclusion: The PVDF-HFP/PEO polymer electrolyte film is a potential candidate for sodium-ion battery in the potential range of 2-4.2 V.
简介:聚合物作为电解质和分离器，由于其许多优点，如无泄漏，灵活的几何形状，优异的安全性能，以及与电极的良好相容性，与液体相比，引起了极大的兴趣。本研究以聚偏氟乙烯-共六氟丙烯[PVDF-HFP]为材料，在1 M nacl /PC溶液中，以不同质量比的聚环氧乙烷(PEO)进行塑化，制备了聚合物电解质膜，并在钠离子电池中进行了表征。方法:采用溶液铸造法制备聚合物电解质膜。从形貌、电导率、电化学稳定性、热性能和混相结构等方面评价了膜的性能。使用了以下各种表征方法:扫描电镜(SEM)，阻抗谱(测定电解质电阻)，循环伏安法，热降解分析和红外光谱(测定共聚物结构)。结果:结果表明，含40%重量的PVDF-HFP/PEO膜可吸附高达其重量300%的电解质，室温电导率为2.75 × 10-3 cm-1，优于纯PVDF-HFP。聚合物电解质膜在2-4.2 V的电位范围内电化学稳定，可与3-4 V的钠材料电极在可充电钠电池中兼容。结论:PVDF-HFP/PEO聚合物电解质膜在2-4.2 V电位范围内是钠离子电池的潜在候选材料。
{"title":"Physical-chemical and electrochemical properties of sodium ion conducting polymer electrolyte using copolymer poly(vinylidene fluoride- hexafluoropropylene) (PVDF-HFP)/ polyethylene oxide (PEO)","authors":"T. Vo, T. M. Phung, Hoang Quoc Duy Hoang Truong, L. Nguyen, O. H. Nguyen, P. Le","doi":"10.32508/STDJ.V22I1.1230","DOIUrl":"https://doi.org/10.32508/STDJ.V22I1.1230","url":null,"abstract":"Introduction: Polymers acting as both an electrolyte and a separator are of tremendous interest because of their many virtues, such as no leakage, flexible geometry, excellent safe performance, and good compatibility with electrodes, compared with their liquid counterparts. In this study, polymer electrolyte membranes comprising of poly(vinylidene fluorine-co-hexafluoropropylene) [PVDF-HFP] were plasticized with different mass ratios of poly(ethylene oxide) (PEO) in 1 M NaClO4/PC solutions, and were prepared and characterized in sodium-ion battery. \u0000Methods: Polymer electrolyte membranes were prepared by solution-casting techniques. The membranes' performance was evaluated in terms of morphology, conductivity, electrochemical stability, thermal properties and miscibility structure. The following various characterization methods were used: Scanning Electron Microscopy (SEM), impedance spectroscopy (for determination of electrolyte resistance), cyclic voltammetry, thermal degradation analysis, and infra-red spectroscopy (for determination of structure of co-polymer). \u0000Results: It was indicated that the PVDF-HFP/PEO membrane with 40 % wt. PVDF-HFP absorbed electrolytes up to 300 % of its weight and had a roomtemperature conductivity of 2.75 x 10-3 Scm-1, which was better than that of pure PVDF-HFP. All polymer electrolyte films were electrochemically stable in the potential voltage range of 2-4.2 V, which could be compatible with 3-4 V sodium material electrodes in rechargeable sodium cells. \u0000Conclusion: The PVDF-HFP/PEO polymer electrolyte film is a potential candidate for sodium-ion battery in the potential range of 2-4.2 V. \u0000 ","PeriodicalId":285953,"journal":{"name":"Science and Technology Development Journal","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129287960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-03-21DOI: 10.32508/STDJ.V22I1.1661
Loan Thi-Tung Dang, A. Bui, N. Truong, Huy Duc Van, P. Pham
Introduction: 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. Methods: 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. Results: 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. Conclusion: 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.
{"title":"Long-term expansion enhances the expression of tumor suppressor genes in human bone marrow-derived mesenchymal stem cells","authors":"Loan Thi-Tung Dang, A. Bui, N. Truong, Huy Duc Van, P. Pham","doi":"10.32508/STDJ.V22I1.1661","DOIUrl":"https://doi.org/10.32508/STDJ.V22I1.1661","url":null,"abstract":"Introduction: 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. \u0000Methods: 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. \u0000Results: 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. \u0000Conclusion: 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. \u0000 ","PeriodicalId":285953,"journal":{"name":"Science and Technology Development Journal","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133607887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Le, T. Vo, Hoang V. Nguyen, Q. Phung, M. Tran, P. Le
Introduction: 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. Methods: 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. Results: 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. Conclusion: EMITFSI can be used to replace conventional carbonate-based liquids as a high-performance electrolyte for Li-ion batteries.
离子液体(ILs)已成为取代传统锂离子电池中挥发性有机溶剂电解质的有前景的候选者。然而，高粘度和低离子电导率的缺点限制了实际电池的高倍率容量和能量密度。为了解决这些问题，设计出一种电化学稳定性高的安全电解质，制备了离子液体1-乙基-3-甲基咪唑-二(三氟甲烷磺酰)亚胺(EMITFSI)与不同量的碳酸乙烯(EC)的混合物，并对其进行了表征。方法:在本工作中，我们考察了四个因素来证明EMITFSI作为锂离子电池电解质的性能。这些因素包括:混合电解质的热性质(Mettler Toledo DSC1 Star - dsc, Q500-TGA)，电导率(HP- AC阻抗谱)，粘度(Ostwald粘度计CANNON)和电化学窗口(循环伏安法- mgp2生物仪器)。除TGA-DSC方法外，所有实验均重复3次。结果:研究表明，20% wt.乙烯碳酸酯(EC)与EMITFSI混合可显著降低电解质粘度，同时提高离子电导率，保持与纯离子液体相似的电化学稳定性。混合电解质的锂扩散系数低于基于常规溶剂的商用电解质，但热稳定性增强。结论:EMITFSI可替代传统碳酸盐基液体作为锂离子电池的高性能电解质。
{"title":"Physical and electrochemical properties of mixed electrolyte 1-ethyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)imide and ethylene carbonate as electrolytes for Li-ion batteries","authors":"L. Le, T. Vo, Hoang V. Nguyen, Q. Phung, M. Tran, P. Le","doi":"10.32508/STDJ.V22I1.837","DOIUrl":"https://doi.org/10.32508/STDJ.V22I1.837","url":null,"abstract":"Introduction: 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. \u0000Methods: 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. \u0000Results: 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. \u0000Conclusion: EMITFSI can be used to replace conventional carbonate-based liquids as a high-performance electrolyte for Li-ion batteries. \u0000 ","PeriodicalId":285953,"journal":{"name":"Science and Technology Development Journal","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125123667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-02-17DOI: 10.32508/STDJ.V22I1.1020
Nguyen Vu Viet Linh, N. T. Duc, H. D. Phu
Introduction: 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. Methods: 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. Results: 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 oC after 6 hours of copolymerization.
{"title":"Copolymerization of n-butyl acrylate/methyl methacrylate in xylene solvent","authors":"Nguyen Vu Viet Linh, N. T. Duc, H. D. Phu","doi":"10.32508/STDJ.V22I1.1020","DOIUrl":"https://doi.org/10.32508/STDJ.V22I1.1020","url":null,"abstract":"Introduction: 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. \u0000Methods: 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. \u0000Results: 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 oC after 6 hours of copolymerization. \u0000 ","PeriodicalId":285953,"journal":{"name":"Science and Technology Development Journal","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114320085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-02-13DOI: 10.32508/STDJ.V16I4.1606
A. Phung, T. T. Dang
Artificial stone is composite of unsaturated polyester and calcium carbonate that is mostly synthesized. This study aimed to investigate the effect of additives on shrinkage property of Unsaturated Polyester (UP) and mechanical properties of artificial stone such as flexural strength, impact strength, and hardness. In this paper, we tested effect of additives such as anhydride maleic (AM), acrylonitrile butadiene styrene (ABS), methyl methacrylate (MMA) and polyvinyl acetate (PVAc) with varying concentrations from 1 – 10 phr under condition process includes 2 phr BPO, 1100C cured temperature and 20 mins cured time
{"title":"Effect of additives on shrinkage property of unsaturated polyester and mechanical properties of artificial stone","authors":"A. Phung, T. T. Dang","doi":"10.32508/STDJ.V16I4.1606","DOIUrl":"https://doi.org/10.32508/STDJ.V16I4.1606","url":null,"abstract":"Artificial stone is composite of unsaturated polyester and calcium carbonate that is mostly synthesized. This study aimed to investigate the effect of additives on shrinkage property of Unsaturated Polyester (UP) and mechanical properties of artificial stone such as flexural strength, impact strength, and hardness. In this paper, we tested effect of additives such as anhydride maleic (AM), acrylonitrile butadiene styrene (ABS), methyl methacrylate (MMA) and polyvinyl acetate (PVAc) with varying concentrations from 1 – 10 phr under condition process includes 2 phr BPO, 1100C cured temperature and 20 mins cured time","PeriodicalId":285953,"journal":{"name":"Science and Technology Development Journal","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130770135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-26DOI: 10.32508/STDJ.V22I1.1010
H. Dương
Introduction: 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. Methods: 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. Results: 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. Conclusion: Among them, 8'-O-methylsalazinic acid was found as a new natural product.
导读:目前国际上仅有对扩张地衣的化学研究。本文研究了广泛分布于越南林东省的地衣(Parmotrema dilatatum)几种代谢物的分离和鉴定。方法:采用薄层色谱和正相硅胶色谱等多种色谱方法对该地衣极性组分进行植物化学研究。结果:分离得到8个酚类化合物。分离化合物的化学结构通过核磁共振波谱和与文献数据的比较得到了明确的阐明。它们是8'- o -甲基萨拉津酸，萨拉津酸，8'- o -甲基原癸酸，衍射酸，lecanorin, lecanoric acid，异芥子酸，和二羟喹啉酸。结论:其中8′- o -甲基萨拉嗪酸是一种新的天然产物。
{"title":"Phenolic compounds from Pamotrema dilatatum growing in Lam Dong province","authors":"H. Dương","doi":"10.32508/STDJ.V22I1.1010","DOIUrl":"https://doi.org/10.32508/STDJ.V22I1.1010","url":null,"abstract":"Introduction: 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. \u0000Methods: 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. \u0000Results: 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. \u0000Conclusion: Among them, 8'-O-methylsalazinic acid was found as a new natural product. \u0000 ","PeriodicalId":285953,"journal":{"name":"Science and Technology Development Journal","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132299296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-14DOI: 10.32508/STDJ.V16I2.1473
Hien Thi Nguy, Trung Pham
Today, enterprise resource planning system (ERP) becomes popular and it is implemented in most business (in all fields and sizes) all over the world as well as in Vietnam. However, according to consultant experts, ERP projects, though on a large scale with high cost, entail low success rate. For Vietnamese contexts, those findings above are all the more true, because most of Vietnamese enterprises are on a small scale with short-time computerization access, lack of understanding of enterprise systems, and lack of financial resources. This research focuses on exploring key factors affecting the success of ERP projects in Vietnam. Through case studies and data collection, using SPSS for data analysis, key factors affecting the success of ERP projects are listed on such a descending order as follows: Characteristics of ERP team, Quality of consultancy, Characteristics of end-users and Characteristics of business. From the abovementioned analysis, suggestions for ensuring success of ERPs in Vietnam are also proposed.
{"title":"Key factors affecting on the success of ERP projects in Vietnam","authors":"Hien Thi Nguy, Trung Pham","doi":"10.32508/STDJ.V16I2.1473","DOIUrl":"https://doi.org/10.32508/STDJ.V16I2.1473","url":null,"abstract":"Today, enterprise resource planning system (ERP) becomes popular and it is implemented in most business (in all fields and sizes) all over the world as well as in Vietnam. However, according to consultant experts, ERP projects, though on a large scale with high cost, entail low success rate. For Vietnamese contexts, those findings above are all the more true, because most of Vietnamese enterprises are on a small scale with short-time computerization access, lack of understanding of enterprise systems, and lack of financial resources. This research focuses on exploring key factors affecting the success of ERP projects in Vietnam. Through case studies and data collection, using SPSS for data analysis, key factors affecting the success of ERP projects are listed on such a descending order as follows: Characteristics of ERP team, Quality of consultancy, Characteristics of end-users and Characteristics of business. From the abovementioned analysis, suggestions for ensuring success of ERPs in Vietnam are also proposed.","PeriodicalId":285953,"journal":{"name":"Science and Technology Development Journal","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125414418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-07DOI: 10.32508/STDJ.V22I1.1009
T. Nguyen, T. Pham, P. Hansen, P. K. Nguyen
Introduction: 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. Methods: 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 (1), betulin (2), betulinic acid (3), oleanolic acid (4), corosolic acid (5), -sitosterol (6), beta-sitosterol 3-O- beta-D-glucopyranoside (7), stigmast-5-ene-3beta-O-(6-O-hexadecanoyl-beta-D-glucopyranoside) (8), and stigmast-4-ene-3-one (9) were isolated and identified. Results: The results of the alpha-glucosidase inhibitory activity showed thatcorosolic acid (5) and oleanolic acid (4) were the most potent, with IC50 values of 17.86 +/- 0.42 and 18.82 +/- 0.59 ug/mL, respectively. Five of the other seven compounds exhibited inhibitory activity with IC50 values below 100 ug/mL, and higher than the positive control acarbose (127.64 +/- 0.64 ug/mL).
前言:本文对生长在CanGio红树林中的柳杉进行了调查。本研究报道了从littorea Lumnitzera叶片中分离的化合物的分离、表征和α -葡萄糖苷酶抑制活性的评价。方法:采用质谱、一维、二维核磁共振等波谱方法对其结构进行鉴定，并与文献值进行比较。从正己烷提取液中分离鉴定出九种化合物，分别为鹿皮醇(1)、白桦素(2)、白桦酸(3)、齐墩果酸(4)、花椰果酸(5)、-谷甾醇(6)、-谷甾醇3-o - β - d -葡萄糖苷(7)、柱头甾-5-烯-3-o -(6- o -hexadecanoyl- β - d -glucopyranoside)(8)和柱头甾-4-烯-3-one(9)。结果:α -葡萄糖苷酶抑制活性结果显示，花椰菜酸(5)和齐墩果酸(4)的抑制作用最强，IC50值分别为17.86 +/- 0.42和18.82 +/- 0.59 ug/mL。其中5个化合物的IC50值低于100 ug/mL，均高于阳性对照阿卡波糖(127.64 +/- 0.64 ug/mL)。
{"title":"In vitro α-glucosidase inhibitory activity of compounds isolated from mangrove Lumnitzera littorea leaves","authors":"T. Nguyen, T. Pham, P. Hansen, P. K. Nguyen","doi":"10.32508/STDJ.V22I1.1009","DOIUrl":"https://doi.org/10.32508/STDJ.V22I1.1009","url":null,"abstract":"Introduction: 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. \u0000Methods: 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 (1), betulin (2), betulinic acid (3), oleanolic acid (4), corosolic acid (5), -sitosterol (6), beta-sitosterol 3-O- beta-D-glucopyranoside (7), stigmast-5-ene-3beta-O-(6-O-hexadecanoyl-beta-D-glucopyranoside) (8), and stigmast-4-ene-3-one (9) were isolated and identified. \u0000Results: The results of the alpha-glucosidase inhibitory activity showed thatcorosolic acid (5) and oleanolic acid (4) were the most potent, with IC50 values of 17.86 +/- 0.42 and 18.82 +/- 0.59 ug/mL, respectively. Five of the other seven compounds exhibited inhibitory activity with IC50 values below 100 ug/mL, and higher than the positive control acarbose (127.64 +/- 0.64 ug/mL). \u0000 ","PeriodicalId":285953,"journal":{"name":"Science and Technology Development Journal","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126194583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-30DOI: 10.32508/STDJ.V20IK7.1375
P. Huu
There have been various attempts to improve the surface finish after Electrical Discharge Machining (EDM) by polishing and other means. But if it is possible to improve the surface during machining it will shorten the machining time. From this viewpoint powder mixed EDM (PMEDM) is one of these processes. PMEDM not only imparts fine machined surface finish but also modifies the machined surface. However, it is necessary to understand the mechanism of PMEDM process. In this study, influence of process parameters to tool wear rate (TWR) of PMEDM using titanium (Ti) powder is presented. The objective of the study is to evaluate the main effects of workpiece material, tool material, polarity, pulse-on time, intensity of discharge, pulse-off time, and powder concentration on the TWR in PMEDM. They carried out the investigation based on the Taguchi method involving seven control factors with three levels for an orthogonal array L27 (1313).The results indicated that electrode material, electrode polarity, pulse on time, current and powder concentration were the most significant parameters that influenced the TWR. This result will be the basis for selecting the factors in further optimization studies.
{"title":"Study of the effects of process parameters on tool wear rate in powder mixed electrical discharge machining by Taguchi method","authors":"P. Huu","doi":"10.32508/STDJ.V20IK7.1375","DOIUrl":"https://doi.org/10.32508/STDJ.V20IK7.1375","url":null,"abstract":"There have been various attempts to improve the surface finish after Electrical Discharge Machining (EDM) by polishing and other means. But if it is possible to improve the surface during machining it will shorten the machining time. From this viewpoint powder mixed EDM (PMEDM) is one of these processes. PMEDM not only imparts fine machined surface finish but also modifies the machined surface. However, it is necessary to understand the mechanism of PMEDM process. In this study, influence of process parameters to tool wear rate (TWR) of PMEDM using titanium (Ti) powder is presented. The objective of the study is to evaluate the main effects of workpiece material, tool material, polarity, pulse-on time, intensity of discharge, pulse-off time, and powder concentration on the TWR in PMEDM. They carried out the investigation based on the Taguchi method involving seven control factors with three levels for an orthogonal array L27 (1313).The results indicated that electrode material, electrode polarity, pulse on time, current and powder concentration were the most significant parameters that influenced the TWR. This result will be the basis for selecting the factors in further optimization studies. \u0000 ","PeriodicalId":285953,"journal":{"name":"Science and Technology Development Journal","volume":"35 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124984049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Trang, L. Tu, Co Le Thanh Tuyen, Tran Van Man, V. Thu
In this paper, the surface of titanium dioxide (TiO2) nanotubes (NTs) was decorated with sulfur by impregnation procedure. The crystalline structure and morphology of the S-TiO2 NT hybrid catalyst were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The chemical components of S-TiO2 NT-1 sample were analyzed by energy dispersive X-ray (EDX). The results showed that sulfur impurities were incorporated into TiO2 crystal structure and decorated on its surface due to the heat treatment temperature used throughout the fabrication process. Moreover, its photocatalytic reaction was evaluated by change of adsorption intensity of methyl orange (MO) aqueous solution at wavelength of 467 nm. This work revealed that the sulfur loaded onto TiO2 NT nanostructures exhibited excellent photocatalytic efficacy for the degradation of the MO dye compared with pristine TiO2 NTs (93.12 ± 0.02% and 80.21 ± 0.04% MO degradation efficacy under UV light versus visible-light regime, respectively, after 180 minutes). This was mainly governed by sulfur ions modified on the surface of TiO2 NTs which played a critical role in promoting the separation rate of photo-induced charge carriers.
{"title":"Surface modification of titanium dioxide nanotubes with sulfur for highly efficient photocatalytic performance under visible light irradiation","authors":"T. Trang, L. Tu, Co Le Thanh Tuyen, Tran Van Man, V. Thu","doi":"10.32508/STDJ.V21I3.694","DOIUrl":"https://doi.org/10.32508/STDJ.V21I3.694","url":null,"abstract":"In this paper, the surface of titanium dioxide (TiO2) nanotubes (NTs) was decorated with sulfur by impregnation procedure. The crystalline structure and morphology of the S-TiO2 NT hybrid catalyst were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The chemical components of S-TiO2 NT-1 sample were analyzed by energy dispersive X-ray (EDX). The results showed that sulfur impurities were incorporated into TiO2 crystal structure and decorated on its surface due to the heat treatment temperature used throughout the fabrication process. Moreover, its photocatalytic reaction was evaluated by change of adsorption intensity of methyl orange (MO) aqueous solution at wavelength of 467 nm. This work revealed that the sulfur loaded onto TiO2 NT nanostructures exhibited excellent photocatalytic efficacy for the degradation of the MO dye compared with pristine TiO2 NTs (93.12 ± 0.02% and 80.21 ± 0.04% MO degradation efficacy under UV light versus visible-light regime, respectively, after 180 minutes). This was mainly governed by sulfur ions modified on the surface of TiO2 NTs which played a critical role in promoting the separation rate of photo-induced charge carriers. \u0000 ","PeriodicalId":285953,"journal":{"name":"Science and Technology Development Journal","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122919049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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