Pub Date : 2019-03-15DOI: 10.31276/VJSTE.61(1).41-44
Tam T Vo, N. Dang, Như Hiệp Phạm, Gia Khanh Pham
This study aims to assess the results of kidney retransplantations and the survival of second kidney allografts performed in our center. Methodology: of 550 kidney transplantations performed since July 2001, 26 were second kidney transplants. Many recipients were sensitized. All patients were treated with the same immunosuppressive regimen. Results: grafts were functionally effective in all patients with kidney retransplantations one month after the transplant. Graft survival was 100% after one year (17/17) and after five years (1/1). Graft survival was similar for second and primary kidney transplants performed during the same period of time. There were three cases of acute rejection, but all of these cases responded to the anti-rejection treatment. Conclusions: the rate of acute rejection was similar for both second and primary transplantations in our hospital, and the second graft outcome demonstrated effectiveness 12 months after transplantation.
{"title":"Evaluation of graft function in renal retransplantation at Hue Central Hospital","authors":"Tam T Vo, N. Dang, Như Hiệp Phạm, Gia Khanh Pham","doi":"10.31276/VJSTE.61(1).41-44","DOIUrl":"https://doi.org/10.31276/VJSTE.61(1).41-44","url":null,"abstract":"This study aims to assess the results of kidney retransplantations and the survival of second kidney allografts performed in our center. Methodology: of 550 kidney transplantations performed since July 2001, 26 were second kidney transplants. Many recipients were sensitized. All patients were treated with the same immunosuppressive regimen. Results: grafts were functionally effective in all patients with kidney retransplantations one month after the transplant. Graft survival was 100% after one year (17/17) and after five years (1/1). Graft survival was similar for second and primary kidney transplants performed during the same period of time. There were three cases of acute rejection, but all of these cases responded to the anti-rejection treatment. Conclusions: the rate of acute rejection was similar for both second and primary transplantations in our hospital, and the second graft outcome demonstrated effectiveness 12 months after transplantation.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"84 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75817701","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 : 2019-03-15DOI: 10.31276/VJSTE.61(1).23-29
T. Nguyen, T. Nguyen, V. H. Nong, T. Huynh
Dehydration-responsive element-binding (DREB) proteins play a critical role in the plant’s drought-tolerance mechanism despite their presence in minor amounts in the cell. In this study, a maize-derived transcription factor protein, ZmDREB2.7, was overexpressed in the Escherichia coli strain Rosetta 1. The interested gene conjugating with the thioredoxin gene (TrxA) and his6 tag in the pET-32a vector encoded a 55.7 kDa fusion protein. The optimum condition for inducing the thioredoxin-his6-ZmDREB2.7 expression was five hours of induction with 0.05 mM IPTG at 300C. The Tris-HCl 20 mM pH 8.0 lysis buffer was harnessed to extract the recombinant protein for the purification process. Using the immobilized-metal affinity chromatography column, the recombinant protein was purified and then injected into rabbits. The antisera containing polyclonal antibodies (pAbs) could specifically recognize the ZmDREB2.7 fusion protein. This study represents updated data on the bacterial expression of the recombinant ZmDREB2.7 protein and the production of anti-ZmDREB2.7 pAbs.
脱水响应元件结合蛋白(DREB)在植物的抗旱机制中发挥着关键作用，尽管它们在细胞中含量很少。在本研究中，一种玉米来源的转录因子蛋白ZmDREB2.7在大肠杆菌Rosetta 1中过表达。在pET-32a载体中，与硫氧还蛋白基因(TrxA)和his6标签结合的基因编码了一个55.7 kDa的融合蛋白。诱导thioredoxin-his6-ZmDREB2.7表达的最佳条件为0.05 mM IPTG在300C下诱导5h。利用Tris-HCl 20 mM pH 8.0裂解缓冲液提取重组蛋白进行纯化。利用固定化金属亲和层析柱纯化重组蛋白，并将其注射到家兔体内。含有多克隆抗体(pAbs)的抗血清能够特异性识别ZmDREB2.7融合蛋白。该研究代表了重组ZmDREB2.7蛋白的细菌表达和抗ZmDREB2.7 pab的最新数据。
{"title":"Expression and purification of thioredoxin-his6-ZmDREB2.7 fusion protein in Escherichia coli for raising antibodies","authors":"T. Nguyen, T. Nguyen, V. H. Nong, T. Huynh","doi":"10.31276/VJSTE.61(1).23-29","DOIUrl":"https://doi.org/10.31276/VJSTE.61(1).23-29","url":null,"abstract":"Dehydration-responsive element-binding (DREB) proteins play a critical role in the plant’s drought-tolerance mechanism despite their presence in minor amounts in the cell. In this study, a maize-derived transcription factor protein, ZmDREB2.7, was overexpressed in the Escherichia coli strain Rosetta 1. The interested gene conjugating with the thioredoxin gene (TrxA) and his6 tag in the pET-32a vector encoded a 55.7 kDa fusion protein. The optimum condition for inducing the thioredoxin-his6-ZmDREB2.7 expression was five hours of induction with 0.05 mM IPTG at 300C. The Tris-HCl 20 mM pH 8.0 lysis buffer was harnessed to extract the recombinant protein for the purification process. Using the immobilized-metal affinity chromatography column, the recombinant protein was purified and then injected into rabbits. The antisera containing polyclonal antibodies (pAbs) could specifically recognize the ZmDREB2.7 fusion protein. This study represents updated data on the bacterial expression of the recombinant ZmDREB2.7 protein and the production of anti-ZmDREB2.7 pAbs.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82913790","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 : 2019-03-15DOI: 10.31276/VJSTE.61(1).14-22
L. Tuan, G. Wyseure
Miscible displacement can be understood as a physical process in a porous medium whereby two or more fluids fully dissolve into each other when a fluid mixes and goes into the pore space occupied by other fluids without the existence of an interface. A physical model was made in Can Tho University, which included an electrical current system connecting nine groups of four-electrode probes for measuring the electrical conductivity of a potassium chloride solution flowing through a horizontal sand column placed in a firm frame. The experiments were performed with different volumetric flow rates and three types of sand (fine, medium and coarse). The breakthrough curves were analysed, and then the hydrodynamic dispersion coefficients were calculated. The hydrodynamic dispersion coefficient was one of the hydraulic and solute transport parameters used to design a constructed subsurface flow wetland. The research proves that the flows were laminar, and that mechanical dispersions dominated over molecular diffusions and that the dispersions were large enough to cause combined mixing and flowing processes.
{"title":"Using a physical model to determine the hydrodynamic dispersion coefficient of a solution through a horizontal sand column","authors":"L. Tuan, G. Wyseure","doi":"10.31276/VJSTE.61(1).14-22","DOIUrl":"https://doi.org/10.31276/VJSTE.61(1).14-22","url":null,"abstract":"Miscible displacement can be understood as a physical process in a porous medium whereby two or more fluids fully dissolve into each other when a fluid mixes and goes into the pore space occupied by other fluids without the existence of an interface. A physical model was made in Can Tho University, which included an electrical current system connecting nine groups of four-electrode probes for measuring the electrical conductivity of a potassium chloride solution flowing through a horizontal sand column placed in a firm frame. The experiments were performed with different volumetric flow rates and three types of sand (fine, medium and coarse). The breakthrough curves were analysed, and then the hydrodynamic dispersion coefficients were calculated. The hydrodynamic dispersion coefficient was one of the hydraulic and solute transport parameters used to design a constructed subsurface flow wetland. The research proves that the flows were laminar, and that mechanical dispersions dominated over molecular diffusions and that the dispersions were large enough to cause combined mixing and flowing processes.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86466617","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 : 2019-03-15DOI: 10.31276/VJSTE.61(1).68-73
D. Tien, H. X. Phong, M. Yamada, Hà Thanh Toàn, N. Dung
Thermotolerant ethanologenic yeasts have attracted the interest of many scientists due to the current challenges caused by increasing global temperature, the benefits associated with processing at high temperatures, and the potential to reduce cooling costs. The objectives of this study are to characterize the selected thermotolerant yeasts and to evaluate their use in Cayratia trifolia fermentation at high temperatures. A total of 151 yeast strains isolated from 53 samples of Cayratia trifolia were studied for their morphology, physiology, biochemistry, and their phylogenetic relationship. Based on the results of tests for thermotolerance ability (37-450C) and ethanol tolerance capacity (9-12% v/v), 57 of the 151 yeast isolates were selected to be tested for use in wine fermentation from three-leaf cayratia at 370C. Thirty isolates that were found to have high fermentation ability and that produced an ethanol concentration of between 6.0 and 9.9% (v/v) were selected for identification using amplified 26S rDNA sequences. The yeasts were identified as follows: Candidaglabrata (BL2.1, CT1.1, CT1.3, CT2.3, HG2.1), Candidatropicalis (KG1.1, KG3.2, CM3.3, HG3.3, TG1.1, TG3.1), Candidanivariensis (DT1.2, CM3.2, ST2.1, BT1.2), Pichiakudriavzevii (KG2.1, KG5.1, AG2.1, AG2.3, AG4.2, DT3.2, LA1.3, CM4.4, BT2.1, BT3.3, TV4.2, CT4.2, VL1.1), Clavisporalusitaniae (TG4.2), and Saccharomycescerevisiae (HG1.3). The phylogenetic tree constructed using MEGA 6 with bootstrap analysis performed by repeating the data 1,000 times revealed that the selected yeast strains were closely related. The newly isolated strain of S. cerevisiaeHG1.3 producing the highest ethanol concentration of 9.9% (v/v) in Cayratia trifolia wine fermentation at 370C was selected for further study.
{"title":"Characterization of newly isolated thermotolerant yeasts and evaluation of their potential for use in Cayratia trifolia wine production","authors":"D. Tien, H. X. Phong, M. Yamada, Hà Thanh Toàn, N. Dung","doi":"10.31276/VJSTE.61(1).68-73","DOIUrl":"https://doi.org/10.31276/VJSTE.61(1).68-73","url":null,"abstract":"Thermotolerant ethanologenic yeasts have attracted the interest of many scientists due to the current challenges caused by increasing global temperature, the benefits associated with processing at high temperatures, and the potential to reduce cooling costs. The objectives of this study are to characterize the selected thermotolerant yeasts and to evaluate their use in Cayratia trifolia fermentation at high temperatures. A total of 151 yeast strains isolated from 53 samples of Cayratia trifolia were studied for their morphology, physiology, biochemistry, and their phylogenetic relationship. Based on the results of tests for thermotolerance ability (37-450C) and ethanol tolerance capacity (9-12% v/v), 57 of the 151 yeast isolates were selected to be tested for use in wine fermentation from three-leaf cayratia at 370C. Thirty isolates that were found to have high fermentation ability and that produced an ethanol concentration of between 6.0 and 9.9% (v/v) were selected for identification using amplified 26S rDNA sequences. The yeasts were identified as follows: Candidaglabrata (BL2.1, CT1.1, CT1.3, CT2.3, HG2.1), Candidatropicalis (KG1.1, KG3.2, CM3.3, HG3.3, TG1.1, TG3.1), Candidanivariensis (DT1.2, CM3.2, ST2.1, BT1.2), Pichiakudriavzevii (KG2.1, KG5.1, AG2.1, AG2.3, AG4.2, DT3.2, LA1.3, CM4.4, BT2.1, BT3.3, TV4.2, CT4.2, VL1.1), Clavisporalusitaniae (TG4.2), and Saccharomycescerevisiae (HG1.3). The phylogenetic tree constructed using MEGA 6 with bootstrap analysis performed by repeating the data 1,000 times revealed that the selected yeast strains were closely related. The newly isolated strain of S. cerevisiaeHG1.3 producing the highest ethanol concentration of 9.9% (v/v) in Cayratia trifolia wine fermentation at 370C was selected for further study.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91300474","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 : 2019-03-15DOI: 10.31276/VJSTE.61(1).62-67
B. T. Nguyen, N. X. Ngo, V. Le, L. Nguyen, R. Kana, Huy Nguyen
The objective in this study is to investigate optimal culture conditions for mycelial growth and fruiting body formation of the Ling Zhi mushroom, Ganoderma lucidum strain GA3. The results of the study show that the optimal media and temperature for the mycelial growth are potato, glucose, and agar (PGA) supplemented with rice bran, and 25-300C, respectively. Strain GA3 is able to grow in a wide pH range, between 4 and 12.The most favourable substrate mixture for the formation and development of the fruiting body is 87% sawdust + 4% corn powder + 8% rice bran + 1% calcium carbonate (CaCO3).
{"title":"Optimal culture conditions for mycelial growth and fruiting body formation of Ling Zhimushroom Ganoderma lucidum strain GA3","authors":"B. T. Nguyen, N. X. Ngo, V. Le, L. Nguyen, R. Kana, Huy Nguyen","doi":"10.31276/VJSTE.61(1).62-67","DOIUrl":"https://doi.org/10.31276/VJSTE.61(1).62-67","url":null,"abstract":"The objective in this study is to investigate optimal culture conditions for mycelial growth and fruiting body formation of the Ling Zhi mushroom, Ganoderma lucidum strain GA3. The results of the study show that the optimal media and temperature for the mycelial growth are potato, glucose, and agar (PGA) supplemented with rice bran, and 25-300C, respectively. Strain GA3 is able to grow in a wide pH range, between 4 and 12.The most favourable substrate mixture for the formation and development of the fruiting body is 87% sawdust + 4% corn powder + 8% rice bran + 1% calcium carbonate (CaCO3).","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89574755","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 : 2019-03-15DOI: 10.31276/VJSTE.61(1).58-61
Lein Trinh, Van Son Ta, Thi Ngoc Han Luu, M. Nguyen, Thi Huong Dinh, V. Nguyen, T. Doan, B. Pham
This study, the presence of 4 common beta-lactamase encoding genes including OXA-23, OXA-51, VIM and IMP was determined simultaneously by multiplex PCR, either directly with sputum samples or with purified DNA, giving results within 3-4 hours instead of 2 days compared to the culture method. Within 58 samples positive with Acinetobacter baumannii collected from the hospital, OXA-51 fragment was dominant (81%), whereas, VIM fragment was only identified in one sample (DNA and sputum samples) (1.7%). The antibiograms indicated for 19 samples were used to find correlation between genotype and resistance phenotype.
{"title":"Studies of common antibiotic resistance-associated genes of Acinetobacter baumannii","authors":"Lein Trinh, Van Son Ta, Thi Ngoc Han Luu, M. Nguyen, Thi Huong Dinh, V. Nguyen, T. Doan, B. Pham","doi":"10.31276/VJSTE.61(1).58-61","DOIUrl":"https://doi.org/10.31276/VJSTE.61(1).58-61","url":null,"abstract":"This study, the presence of 4 common beta-lactamase encoding genes including OXA-23, OXA-51, VIM and IMP was determined simultaneously by multiplex PCR, either directly with sputum samples or with purified DNA, giving results within 3-4 hours instead of 2 days compared to the culture method. Within 58 samples positive with Acinetobacter baumannii collected from the hospital, OXA-51 fragment was dominant (81%), whereas, VIM fragment was only identified in one sample (DNA and sputum samples) (1.7%). The antibiograms indicated for 19 samples were used to find correlation between genotype and resistance phenotype.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"107 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85566086","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 : 2019-03-15DOI: 10.31276/VJSTE.61(1).30-35
N. Q. Huy, M. Quan, L. Man, D. Nguyen, T. Hoat
Cassava (Manihot esculenta Crantz) is one of the most important crops in Vietnam for providing food, starch sources, and raw materials for the production of bio-ethanol and other purposes. Cassava bacterial blight (CBB)disease, caused by Xanthonomas axonopodis pv. manihotis (Xam), is one of the most important factors affecting cassava production in Vietnam. A rapid and sensitive molecular tool is required to support the traditional method, primarily based on biochemical reactions, that was considered less sensitive and time-consuming. In the present study, in order to detect Xam, the Polymerase Chain Reaction (PCR) technique was applied with the two primerpairs, rpoD_17F/rpoD_1005R and XgyrconpcrF1/Xgyrconrpcr1, to amplify partial sequences of rpoD and gyrBgenes, respectively. The primers directed the amplification of about 900 bp DNA fragments from CBB-infected leaf and stem tissues. All the amplified DNA sequences were identical in each gene and to the Xam reference strains (accession numbers KP265376 and KP265378 for the rpoD gene, and KP265387 and KP265388 for the gyrB gene) from GenBank. The representative sequences of rpoD and gyrB genes were deposited in GenBank with accession numbers MF774491 and MF774490, respectively. DNA and phylogenetic analysis based on the sequences of rpoD and gyrB genes have confirmed that Xam is the causal agent of CBB in Dong Nai, Vietnam. This is the first confirmed identification of the causal pathogen of CBBdisease in Vietnam using molecular tools, and this method is a reliable tool for the detection and identification of other plant bacterial pathogens.
{"title":"Identification of cassava bacterial blight-causing Xanthomonas axonopodis pv. Manihotis based on rpoD and gyrB genes","authors":"N. Q. Huy, M. Quan, L. Man, D. Nguyen, T. Hoat","doi":"10.31276/VJSTE.61(1).30-35","DOIUrl":"https://doi.org/10.31276/VJSTE.61(1).30-35","url":null,"abstract":"Cassava (Manihot esculenta Crantz) is one of the most important crops in Vietnam for providing food, starch sources, and raw materials for the production of bio-ethanol and other purposes. Cassava bacterial blight (CBB)disease, caused by Xanthonomas axonopodis pv. manihotis (Xam), is one of the most important factors affecting cassava production in Vietnam. A rapid and sensitive molecular tool is required to support the traditional method, primarily based on biochemical reactions, that was considered less sensitive and time-consuming. In the present study, in order to detect Xam, the Polymerase Chain Reaction (PCR) technique was applied with the two primerpairs, rpoD_17F/rpoD_1005R and XgyrconpcrF1/Xgyrconrpcr1, to amplify partial sequences of rpoD and gyrBgenes, respectively. The primers directed the amplification of about 900 bp DNA fragments from CBB-infected leaf and stem tissues. All the amplified DNA sequences were identical in each gene and to the Xam reference strains (accession numbers KP265376 and KP265378 for the rpoD gene, and KP265387 and KP265388 for the gyrB gene) from GenBank. The representative sequences of rpoD and gyrB genes were deposited in GenBank with accession numbers MF774491 and MF774490, respectively. DNA and phylogenetic analysis based on the sequences of rpoD and gyrB genes have confirmed that Xam is the causal agent of CBB in Dong Nai, Vietnam. This is the first confirmed identification of the causal pathogen of CBBdisease in Vietnam using molecular tools, and this method is a reliable tool for the detection and identification of other plant bacterial pathogens.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"138 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77443095","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 : 2019-03-15DOI: 10.31276/vjste.61(1).09-13
Viet Linh Nguyen-Vu, Mai Anh Pham, D. P. Huynh
Triblock copolymers were polymerised by the ring-opening reaction of D,L-lactide in the presence of poly(ethylene glycol) (PEG), with number-average molecular weight (Mn) of 1500 and 2050 g/mol, using Sn(Oct)2 as a catalyst. The influences of the reaction time, the ratio of PEG and Poly(D,L-lactic acid) (PLA), and PEG types on structure and sol-gel phase transition of PLA-PEG-PLA triblock copolymers were investigated. Optimal polymerisation parameters were obtained, such as reaction time of 18 hours, a catalyst amount of 1.3%, and PEG/PLA ratio of 1/1.7, PEG (Mn=1500); the efficiency of the triblock synthesis was 42.3%. The properties of PLA-PEG-PLA copolymers were evaluated by analytical methods such as proton nuclear magnetic resonance H1NMR spectroscopy, gel permeation chromatography (GPC), and the sol-gel state transition at varying temperature. The results show that the triblock was successfully synthesised and its hydrogel had capability of the sol-gel state transition when the temperature changed. The PLA-PEG-PLA copolymer in aqueous solution is a thermo-sensitive hydrogel that can be used for drug and protein delivery systems or triblock denaturation applications for commercial purposes.
以Sn(Oct)2为催化剂，在聚乙二醇(PEG)存在下，用D, l -丙交酯开环反应聚合了三嵌段共聚物，其数平均分子量(Mn)分别为1500和2050 g/mol。考察了反应时间、PEG与聚(D, l-乳酸)(PLA)的比例、PEG类型对PLA-PEG-PLA三嵌段共聚物结构和溶胶-凝胶相变的影响。得到了最佳聚合参数:反应时间为18小时，催化剂用量为1.3%，PEG/PLA比为1/1.7,PEG (Mn=1500);三嵌段的合成效率为42.3%。采用质子核磁共振(H1NMR)、凝胶渗透色谱(GPC)和不同温度下的溶胶-凝胶态转变等分析方法评价了PLA-PEG-PLA共聚物的性能。结果表明，该三嵌段化合物成功合成，其水凝胶在温度变化时具有溶胶-凝胶态转变的能力。水溶液中的PLA-PEG-PLA共聚物是一种热敏水凝胶，可用于药物和蛋白质输送系统或用于商业目的的三嵌段变性应用。
{"title":"The effects of temperature, feed ratio, and reaction time on the properties of copolymer PLA-PEG-PLA","authors":"Viet Linh Nguyen-Vu, Mai Anh Pham, D. P. Huynh","doi":"10.31276/vjste.61(1).09-13","DOIUrl":"https://doi.org/10.31276/vjste.61(1).09-13","url":null,"abstract":"Triblock copolymers were polymerised by the ring-opening reaction of D,L-lactide in the presence of poly(ethylene glycol) (PEG), with number-average molecular weight (Mn) of 1500 and 2050 g/mol, using Sn(Oct)2 as a catalyst. The influences of the reaction time, the ratio of PEG and Poly(D,L-lactic acid) (PLA), and PEG types on structure and sol-gel phase transition of PLA-PEG-PLA triblock copolymers were investigated. Optimal polymerisation parameters were obtained, such as reaction time of 18 hours, a catalyst amount of 1.3%, and PEG/PLA ratio of 1/1.7, PEG (Mn=1500); the efficiency of the triblock synthesis was 42.3%. The properties of PLA-PEG-PLA copolymers were evaluated by analytical methods such as proton nuclear magnetic resonance H1NMR spectroscopy, gel permeation chromatography (GPC), and the sol-gel state transition at varying temperature. The results show that the triblock was successfully synthesised and its hydrogel had capability of the sol-gel state transition when the temperature changed. The PLA-PEG-PLA copolymer in aqueous solution is a thermo-sensitive hydrogel that can be used for drug and protein delivery systems or triblock denaturation applications for commercial purposes.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85330469","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 : 2019-03-15DOI: 10.31276/VJSTE.61(1).92-96
T. D. Hoa, D. Nam
Increasing flood risks in a changing climate tend to put greater pressure on water-related infrastructure, existing operations, and management practices. This paper introduces preliminary research results on river information management and flood-risk reduction based on an early flood-release approach that has the goals of better reservoir operation, adapting to climate change, and ensuring dam safety in Vietnam. Early flood release is performed using inflow prediction information derived from a medium-range global numerical weather-prediction model. The results show that peak discharge and inundation areas are remarkably reduced, and are useful for improving the safety of dams and flood-risk management in downstream areas.
{"title":"River information management and early flood release in response to climate change in Vietnam","authors":"T. D. Hoa, D. Nam","doi":"10.31276/VJSTE.61(1).92-96","DOIUrl":"https://doi.org/10.31276/VJSTE.61(1).92-96","url":null,"abstract":"Increasing flood risks in a changing climate tend to put greater pressure on water-related infrastructure, existing operations, and management practices. This paper introduces preliminary research results on river information management and flood-risk reduction based on an early flood-release approach that has the goals of better reservoir operation, adapting to climate change, and ensuring dam safety in Vietnam. Early flood release is performed using inflow prediction information derived from a medium-range global numerical weather-prediction model. The results show that peak discharge and inundation areas are remarkably reduced, and are useful for improving the safety of dams and flood-risk management in downstream areas.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"122 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90593846","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 : 2019-03-15DOI: 10.31276/VJSTE.61(1).03-08
T. Vu, H. Le
In complex indoor environments, due to the attenuation of the signal and the changing surrounding environment, the censoring and multi-component problems may be present in the observed data. Censoring refers to the fact that sensors on portable devices cannot measure Received Signal Strength Index (RSSI) values below a specific threshold, such as -100 dBm. The multi-component problem occurs when the measured data varies due to obstacles and user directions, whether the door is closed or open, etc. By accounting for these problems, this paper proposes to model the RSSI probability density distributions using the Censoring Gaussian Mixture Model (C-GMM) and develop the Expectation-Maximization (EM) algorithm to estimate the parameters of this model in the offline phase of the Wi-Fi fingerprinting based Indoor Positioning Systems (IPS). The simulation results demonstrate the effectiveness of the proposed method.
{"title":"Gaussian Mixture Modeling for Wi-Fi fingerprintingbased indoor positioning in the presence of censored data","authors":"T. Vu, H. Le","doi":"10.31276/VJSTE.61(1).03-08","DOIUrl":"https://doi.org/10.31276/VJSTE.61(1).03-08","url":null,"abstract":"In complex indoor environments, due to the attenuation of the signal and the changing surrounding environment, the censoring and multi-component problems may be present in the observed data. Censoring refers to the fact that sensors on portable devices cannot measure Received Signal Strength Index (RSSI) values below a specific threshold, such as -100 dBm. The multi-component problem occurs when the measured data varies due to obstacles and user directions, whether the door is closed or open, etc. By accounting for these problems, this paper proposes to model the RSSI probability density distributions using the Censoring Gaussian Mixture Model (C-GMM) and develop the Expectation-Maximization (EM) algorithm to estimate the parameters of this model in the offline phase of the Wi-Fi fingerprinting based Indoor Positioning Systems (IPS). The simulation results demonstrate the effectiveness of the proposed method.","PeriodicalId":23548,"journal":{"name":"Vietnam Journal of Science, Technology and Engineering","volume":"121 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86442055","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：