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Kai Qian,XiaoHai Gong,Bo Guan,SuPing Wu,JingJing Zhang,Jing Qian,YanFei Cai,Yun Chen,ZuoYing Duan,Xin Ma,HuaZhong Li,Jian Jin 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.4
Glucagon-like peptide-1 (GLP-1) was a potential therapeutic drug for type II diabetes, mainly because of the stimulatory effect on insulin secretion under condition of high blood glucose. We used PCR to obtain a recombination gene, GGH, in which two GLP-1 (GLP-1A2G) mutants were connected in series and then fused to the N terminal of human serum albumin. The fusion gene was inserted into pGAPZaA plasmid with Saccharomyces cerevisiae α- factor secretion signal sequence, and was expressed by the glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter. The engineered strain was constructed by integrating the recombinant plasmid pGAPZαA/GGH into the genome of Pichia pastoris GS115. Genome PCR and western blot showed that the recombinant P. pastoris successfully expressed the fusion protein GGH. The yield of GGH reached 78 mg/L after 72 h fermentation in a flask, using glucose as the optimal carbon source. Fed-batch fermentation was investigated in a 5 L bioreactor, and the expression level of GGH reached 246 mg/L in 52 h. The fusion protein GGH was purified in four steps, and the final purity was 96.1%. The in vitro bioactivity of GGH was the same as that expressed in P. pastoris by the AOX1 promoter. This study described an efficient way to express GGH fusion protein in P. pastoris using GAP promoter, fermentation was easier to control without carbon source change and fermentation time was 20 h less than AOX1 promotercontrolled GGH fermentation.
Investigations on the exterior flow field and the efficiency of the muzzle brake
Huanhao Zhang,Zhihua Chen,Xiaohai Jiang,Hongzhi Li 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.1
Numerical investigations of the projectile launch process with different muzzle brakes have been performed in a nearly realistic situation. Both two- and three-dimensional unsteady Euler equations are used as the governing equations. The hybrid Roe type scheme is employed to solve the flow fields with strong blast waves, and structured dynamic mesh technique is used for describing projectile motion. Based on the numerical solutions, the flow structures of a bare muzzle, the three-way and multi-hole muzzle brakes have been described, respectively, which agree well with our previous experimental shadowgraphs. Moreover, the efficiency of the three-way muzzle brake is calculated, which is also comparable to the corresponding experimental value. Our results showed that the numerical simulation can be a useful and efficient way for the design of new muzzle brakes.
Zewu Zhang,Qiong Wu,Xiaohai Bu,Zusheng Hang,Zhangzhong Wang,Qikang Wang,Yuhang Ma 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.1
Supported Pt─Au bimetal nanocatalysts have been prepared by an in situ reduction method followed by calcination in air and reduction in H2 atmosphere. The catalysts exhibit a typical yolk-shell construction composed of a moveable magnetic Fe core and metal oxides shells decorated with Pt─Au nanoparticles. The structure of the bimetal nanocatalysts was characterized in detail by TEM, XRD, XPS, and N2 physical adsorption and the catalytic activity of the nanocatalysts was studied by the catalytic reduction of 4-nitrophenol to 4-nitrophenol. It is found that the bimetal nanocatalysts composed with the different metallic oxides (TiO2 and ZrO2) exhibited the comparable Pt─Au particles size (~10 nm). However, the content of Pt─Au nanoparticles was varied with the metallic oxides support. Pt─Au nanoparticles deposited uniformly on TiO2 with higher loadings, however the nanoparticles on ZrO2 exhibited remarkably lower content, which should be attributed to the abundant hydroxyl on TiO2 surface that served as the deposition site for Pt─Au nanoparticles. The result of the reduction reaction indicated that incorporation of TiO2 in the bimetal Pt─Au nanocatalyst could significantly improve the catalytic activity as compared with ZrO2 and m-SiO2. A possible mechanism was proposed to explain the synergistic effect in the supported Pt─Au bimetal nanocatalysts.
Dan Zhang,Zongqi Xu,Hong Xu,Xiaohai Feng,Sha Li,Heng Cai,Yan Wei,Pingkai Ouyang 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.6
In this study, the production of poly(γ-glutamic acid) by Bacillus subtilis NX-2 (PGA) at different agitation speeds was investigated. Based on the analysis of specific cell growth rate (μ) and specific PGA formation rate (q_p),a two-stage strategy for agitation speed control was proposed. During the first 24 h, an agitation speed of 600rpm was used to maintain a high μ for better cell growth,which then reduced to 400 rpm after 24 h to maintain a high qp to enhance PGA production. Using this method, the maximum concentration of PGA reached 40.5 ± 0.91 g/L and the PGA productivity was 0.56 ± 0.012 g/L/h, which was 17.7 and 9.8% higher, respectively, than the best results obtained when a constant agitation speed was used. The flux distributions and the related enzymes of 2-oxoglutarate could be affected by this two-stage strategy for agitation speed. The activity of isocitrate dehydrogenase and glutamate dehydrogenase at the key node of 2-oxoglutarate increased, and more flux distribution was directed to glutamate. The flux distribution from extracellular to intracellular glutamate also increased and improved PGA production as the glutamate uptake rates increased using the agitation-shift control method.
Ye Dou,Enying Zhang,Qinglu Wang,Xiaohai Zhu,Xuewen Tian,Jingjing Cheng 대한진단검사의학회 2015 Annals of Laboratory Medicine Vol.35 No.3
Background: Several studies have focused on the association between the lipid-lowering efficacy of statins and the SLCO1B1 c.521T>C polymorphism; however, the results are conflicting. The effects of statins show significant variability between individuals. This meta-analysis aimed to investigate the effects of the SLCO1B1 c.521T>C polymorphism on the lipid-lowering effects of statins. Methods: We systematically searched PubMed and Web of Science to screen relevant studies. Meta-analysis was performed to identify the association between SLCO1B1 c.521 polymorphisms and the lipid-lowering effects of statinson the basis of the standard mean difference (SMD) and 95% confidence intervals (CIs). Additionally, we checked for heterogeneity (I2) among studies and evidence of publication bias. We obtained eight studies including 2,012 wild genotype (T/T) and 526 variant genotype (T/C and C/C) cases. Results: No significant difference was observed in the lipid-lowering efficacy of statins between the wildand variant genotypes of SLCO1B1, with a pooled SMD of 0.03 (95% CI: -0.07-0.13). Furthermore, there was no significant effect in the meta-analyses of the variant heterozygote, homozygote, and Chinese populations. Subgroup meta-analysis indicated that the timerequired for the statin to take effectdid notsignificantly affect the association between lipid-lowering efficacy of statins and SLCO1B1 c.521T>C polymorphism. However, thewild genotype improved the lipid-lowering efficacy of simvastatin with a pooled SMD of -0.26 (95% CI: -0.47- -0.05). Conclusions: No significant association was detected between the lipid-lowering efficacy of statins and the SLCO1B1 c.521T>C polymorphism, with the exception of simvastatin.
Xu Xu,Jia Song,Ke Wang,YingChun Gu,Feng Luo,XiaoHai Tang,Ping Xie,ZhiYong Qian 한국고분자학회 2013 Macromolecular Research Vol.21 No.8
In this paper, a novel biodegradable and pH/thermo-sensitive hydrogel based on poly(ε-caprolactone),methoxyl poly(ethylene glycol), methylacrylic acid and N-isopropylacrylamide was prepared by UV-initiated free radical polymerization. The hydrogels were characterized by Fourier transforms infrared ray. The thermal responsibility was investigated with the help of differential scanning calorimetry. Swelling behavior in aqueous medium with different pH value was studied in detail. When the pH value of the aqueous medium was increased from 1.2 to 7.2,the swelling ratio of the hydrogels increased accordingly. The morphology was observed by scanning electron microscopy, and the hydrolytic degradation behavior in different aqueous media (pH 1.2 and pH 7.2) was also investigated in detail. The prepared biodegradable pH/thermo-sensitive hydrogel based on poly(ε-caprolactone), methoxyl poly(ethylene glycol), methylacrylic acid and N-isopropylacrylamide hold great promise in the development of a smart drug delivery system.
Gong, Qing,Luo, Huadong,Cao, Di,Zhang, Haibo,Wang, Wenjing,Zhou, Xiaohai Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.6
Rhodamine B (RhB) and rhodamine 6G (Rh6G) were employed as catalysts for the synthesis of cyclic carbonate from carbon dioxide and epoxide. It turned out that the catalytic activity of Rh6G was nearly 29 times higher than that of RhB at 1 atm pressure, $90^{\circ}C$. Furthermore, the catalytic efficiency of RhB and Rh6G was greatly enhanced with triethylamine as co-catalyst. Under the optimized conditions, the best isolated yield (93%) of cyclic carbonate was achieved without organic solvent and metal component.
Zewu Zhang,Jinghui Zhang,Guangqing Liu,Mengwei Xue,Zhangzhong Wang,Xiaohai Bu,Qiong Wu,Xuejuan Zhao 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.9
Au-Pt alloy nanoparticles that are selectively anchored on TiO2 surface of the ellipsoidal zirconium titanium composite oxides were successfully prepared by a facile two-step method: prefabricated binary composite oxides on the ellipsoidal Fe2O3@SiO2 by a versatile cooperative template-directed coating method, and then in situ formation of Au-Pt alloy NPs with Sn2+ as the reduction agent. The alloy catalysts were characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The result suggested that highly dispersive and ultrafine Au-Pt alloy nanoparticles were deposited onto TiO2 surface of the binary oxides solely. The particle size of nanoalloys was closely related to the ratio of Zr : Ti in the composite oxides shell. Increasing the content of Zr element led to a growth in the size of alloy nanoparticles. When used as catalysts for the reduction of 4-nitrophenol, the prepared supported alloyed catalysts exhibited high catalytic activity, and the sample could be easily recycled without a significant decrease of the catalytic activity.
( Zhaoxian Xu ),( Changhong Cao ),( Zhuzhen Sun ),( Sha Li ),( Zheng Xu ),( Xiaohai Feng ),( Hong Xu ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.11
Poly(ε-L-lysine) (ε-PL) is a novel bioactive polymer secreted by filamentous bacteria. Owing to lack of a genetic system for most ε-PL-producing strains, very little research on enhancing ε-PL biosynthesis by genetic manipulation has been reported. In this study, an effective genetic system was established via intergeneric conjugal transfer for Streptomyces albulus PD-1, a famous ε-PL-producing strain. Using the established genetic system, the Vitreoscilla hemoglobin (VHb) gene was integrated into the chromosome of S. albulus PD-1 to alleviate oxygen limitation and to enhance the biosynthesis of ε-PL in submerged fermentation. Ultimately, the production of ε-PL increased from 22.7 g/l to 34.2 g/l after fed-batch culture in a 5 L bioreactor. Determination of the oxygen uptake rate, transcriptional level of ε-PL synthetase gene, and ATP level unveiled that the expression of VHb in S. albulus PD-1 enhanced ε-PL biosynthesis by improving respiration and ATP supply. To the best of our knowledge, this is the first report on enhancing ε-PL production by chromosomal integration of the VHb gene in an ε-PL-producing strain, and it will open a new avenue for ε-PL production.