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( Jun Mei Ding ),( Ting Ting Yu ),( Lian Ming Liang ),( Zhen Rong Xie ),( Yun Juan Yang ),( Jun Pei Zhou ),( Bo Xu ),( Jun Jun Li ),( Zun Xi Huang ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.11
The esterase gene Est8 from the thermophilic bacterium Bacillus sp. K91 was cloned and expressed in Escherichia coli. The monomeric enzyme exhibited a theoretical molecular mass of 24.5 kDa and an optimal activity around 50°C at pH 9.0. A model of Est8 was constructed using a hypothetical YxiM precursor structure (2O14_A) from Bacillus subtilis as template. The structure showed an α/β-hydrolase fold and indicated the presence of a typical catalytic triad consisting of Ser-11, Asp-182, and His-185, which were investigated by site directed replacements coupled with kinetic characterization. Asp-182 and His-185 residues were more critical than the Ser-11 residue in the catalytic activity of Est8. A comparison of the amino acid sequence showed that Est8 could be grouped into the GDSL family and further classified as an SGNH hydrolase. Est8 is a new member of the SGNH hydrolase subfamily and may employ a different catalytic mechanism.
Xu, Ming-Ming,Mao, Guo-Xin,Liu, Jian,Li, Jian-Chao,Huang, Hua,Liu, Yi-Fei,Liu, Jun-Hua Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.9
Because of its importance in tumor invasion and metastasis, the epithelial-mesenchymal transition (EMT) has become a research focus in the field of cancer. Recently, evidence has been presented that FoxO4 might be involved in EMT. Our study aimed to detect the expression of FoxO4, E-cadherin and vimentin in non-small cell lung cancers (NSCLCs). We also investigated clinical features and their correlations with the markers. In our study, FoxO4, E-cadherin and vimentin were assessed by immunohistochemistry in a tissue microarray (TMA) containing 150 cases of NSCLC. In addition, the expression level of FoxO4 protein was determined by Western blotting. The percentages of FoxO4, E-cadherin and vimentin positive expression in NSCLCs were 42.7%, 38.7% and 55.3%, respectively. Immunoreactivity of FoxO4 was low in NSCLC when compared with paired normal lung tissues. There were significant correlations between FoxO4 and TNM stage (P<0.001), histological differentiation (P=0.004) and lymph node metastasis (P<0.001), but no significant links with age (P=0.323), gender (P=0.410), tumor size (P=0.084), smoking status (P=0.721) and histological type (P=0.281). Our study showed that low expression of FoxO4 correlated with decreased expression of E-cadherin and elevated expression of vimentin. Cox regression analysis indicated FoxO4 to be an independent prognostic factor in NSCLC (P=0.046). These data suggested that FoxO4 might inhibit the process of EMT in NSCLC, and might therefore be a target for therapy.
Preparation of Flame Retardant and Antibacterial Wood with Composite Membrane Coating
( Jun-xian Xu ),( Yang Liu ),( Ming-yu Wen ),( Hee-jun Park ),( Jia-zhi Zhu ),( Yu-nan Liu ) 한국목재공학회 2021 목재공학 Vol.49 No.6
A novel flame retardant and antibacterial composite membrane coating for wood surfaces was prepared by adding POSS-based phosphorous nitrogen flame retardant (later referred to as NH<sub>2</sub>-POSS) and silver nanoparticles (Ag NPs) to chitosan (CS). The effects of NH<sub>2</sub>-POSS content (mass fractions of CS 0%, 0.5%, 1%, 3%, 5%, and 7%) on the structure and properties of the composite membrane coating on wood were investigated. The composite film was prepared by the method of blending and ducting. Contact angle, tensile property and antibacterial effects of the composite film were measured, and infrared spectroscopy was used. The results show that the addition of NH<sub>2</sub>-POSS can not only improve the toughness of the membrane, but also the flame retardancy of the membrane, which improves the application of the membrane in wood products. However, with the addition of NH<sub>2</sub>-POSS, the transparency of the composite membrane was weakened. The inhibitory effect of the composite membrane on the growth of Escherichia coli was enhanced with the increase in Ag NPs. This research provides a foundation for the application of functional wood.
( Bo Xu ),( Li Ming Dai ),( Jun Jun Li ),( Meng Deng ),( Hua Biao Miao ),( Jun Pei Zhou ),( Yue Lin Mu ),( Qian Wu ),( Xiang Hua Tang ),( Yun Juan Yang ),( Jun Mei Ding ),( Nan Yu Han ),( Zun Xi Huang 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.1
Xylanases sourced from different bacteria have significantly different enzymatic properties. Therefore, studying xylanases from different bacteria is important to their applications in different fields. A potential xylanase degradation gene in Massilia was recently discovered through genomic sequencing. However, its xylanase activity remains unexplored. This paper is the first to report a xylanase (XynRBM26) belonging to the glycosyl hydrolase family (GH10) from the genus Massilia. The gene encodes a 383-residue polypeptide (XynRBM26) with the highest identity of 62% with the endoxylanase from uncultured bacterium BLR13. The XynRBM26 expressed in Escherichia coli BL21 is a monomer with a molecular mass of 45.0 kDa. According to enzymatic characteristic analysis, pH 5.5 is the most appropriate for XynRBM26, which could maintain more than 90% activity between pH 5.0 and 8.0. Moreover, XynRBM26 is stable at 37°C and could maintain at least 96% activity after being placed at 37°C for 1 h. This paper is the first to report that GH10 xylanase in an animal gastrointestinal tract (GIT) has salt tolerance, which could maintain 86% activity in 5 M NaCl. Under the optimum conditions, Km, Vmax, and kcat of XynRBM26 to beechwood xylan are 9.49 mg/ml, 65.79 μmol/min/mg, and 47.34 /sec, respectively. Considering that XynRBM26 comes from an animal GIT, this xylanase has potential application in feedstuff. Moreover, XynRBM26 is applicable to high-salt food and seafood processing, as well as other high-salt environmental biotechnological fields, because of its high catalytic activity in high-concentration NaCl.
Jun Zhao,Shan-Ming Luo,Feng-Qiang Li,Chen-Bing Xu 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.7
Failure analysis shows that increased die temperature caused by severe plastic deformation of material and heat conduction between hot billet and cavity significantly affects the distortion of gear cavity in steel synchronizer ring forging process. The forging process of steel synchronizer ring and die temperature distribution under different forging conditions are analyzed through finite element method. Simulation results show that severe plastic deformation occurs in the gear cavity. The improvement of lubrication condition results in decreased die temperature. When the initial billet temperature is high, the die temperature is also high. Increasing forging speed in a certain range facilitates the die temperature decrease. The distribution of die temperature in synthetic forming technology is more reasonable than that of one step forging. The synthetic forming technology is adopted in production to reduce the effects of severe plastic deformation caused by die temperature. The ejection mechanism and control system of the double disc friction press are improved to reduce the contact time between the hot billet and cavity. Experimental results show that synthetic forming technology is reasonable, and that the die service life is prolonged.
Xu Qilin,Liu Ji Ming,Yao Hongmiao,Zhao Jinyang,Wang Zhikuo,Liu Junli,Zhou Jiadi,Yu Zhiqun,Su Weike 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.10
In this paper, the kinetics of acylation reaction of o-phenylenediamine/p-phenylenediamine and benzoic anhydride were determined in microreactors, respectively. A kinetic model was established, all kinetic parameters including reaction orders, reaction rate constants, pre-exponential factors, and activation energies were acquired. Validation experiments showed experimental data fit well with calculated data at different reactant concentrations and residence times. The comparisons of the reaction rate constants and activation energies were summarized to show the difference of chemical reactivities of phenylenediamines. According to the calculation of the kinetic model, the optimized reaction conditions were listed to meet the monoacylation selectivity equal to 97.0%.
Jun-Nan Hu,Xing-Yue Xu,Wei Li,Yi-Ming Wang,Ying Liu,Zi Wang,Ying-Ping Wang 고려인삼학회 2019 Journal of Ginseng Research Vol.43 No.1
Background: Frequent overdose of paracetamol (APAP) has become the major cause of acute liver injury. The present study was designed to evaluate the potential protective effects of ginsenoside Rk1 on APAPinduced hepatotoxicity and investigate the underlying mechanisms for the first time. Methods: Micewere treated with Rk1 (10 mg/kg or 20 mg/kg) by oral gavage once per d for 7 d. On the 7th d, all mice treatedwith250mg/kgAPAPexhibitedsevere liver injuryafter24h, andhepatotoxicitywas assessed. Results: Our results showed that pretreatment with Rk1 significantly decreased the levels of serum alanine aminotransferase, aspartate aminotransferase, tumor necrosis factor, and interleukin-1b compared with the APAPgroup.Meanwhile, hepatic antioxidants, including superoxide dismutase andglutathione,were elevated compared with the APAP group. In contrast, a significant decrease in levels of the lipid peroxidation product malondialdehyde was observed in the ginsenoside Rk1-treated group compared with the APAP group. These effectswere associatedwith a significant increase of cytochromeP450 E1 and 4-hydroxynonenal levels in liver tissues. Moreover, ginsenoside Rk1 supplementation suppressed activation of apoptotic pathways by increasing Bcl-2 and decreasing Bax protein expression levels, which was shown using western blotting analysis.Histopathological observation also revealed that ginsenoside Rk1 pretreatment significantly reversed APAP-induced necrosis and inflammatory infiltration in liver tissues. Biological indicators of nitrative stress, such as 3-nitrotyrosine, were also inhibited after pretreatment with Rk1 compared with the APAP group. Conclusion: The results clearly suggest that the underlying molecular mechanisms in the hepatoprotection of ginsenoside Rk1 in APAP-induced hepatotoxicity may be due to its antioxidation, antiapoptosis, anti-inflammation, and antinitrative effects.
Ming Cai Xu,Zhao Jun Song,Jin Pan 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.4
The fi re accidents casually happen during operation of ship, which would infl uence the load carrying capacity of stiff ened panel of ship structures due to the thermal load. The present paper aims to understand the infl uence of thermal loads on the collapse behaviour of stiff ened panels under longitudinal compressive load. Considering the heating and cooling down processes, the collapse behaviours of the stiff ened panels under combined in-plane displacement and heat loads representative of fi re accident are simulated in the FE (fi nite element) analysis herein. Firstly, the thermal load is considered to investigate the stress state of the stiff ened panels during heating and cooling processes. It is found that the stiff ened panels would collapse during thermal loads for the structure with large heated zone. After that, the longitudinal compression loads are applied to assess the collapse strength of the stiff ened panels. The parametric studies including diff erent geometrical dimensions and areas of heat zone are performed in detail to quantify the eff ects of heat loads on the collapse behaviours of stiff ened panels. It is found that the expansion could produce biaxial stress state that depends on not only in-plane stiff ness but also collapse modes, and for stiff ened panels with various heated area the cooling down to room temperature induce similar ultimate strength to that without considering heat loads.
Ming Cai Xu,Zhao Jun Song,Jin Pan,C. Guedes Soares 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.4
Using the finite element analysis, a series stiffened panels under combined normal loads and biaxial compressions are conducted to investigate the effect of several influential factors on the ultimate limit states. Two spans/bays FE model with periodical boundary condition is adopted to consider the interaction between adjacent structural members. The initial deflections assumed as Fourier components including symmetric and asymmetric modes are used to identify the half-wave number of collapse of the local plate, which is compared with half-wave number of buckling calculated by formula. Based on the numerical results, the influences of half-wave number assumed in the equivalent initial imperfection and loads combination on the collapse behaviours of stiffened panels are discussed. It is found that lateral pressure might increase the ultimate strength of stiffened panels for the stiffener-induced failure modes. The one half-wave region of local plate influences significantly the load carrying capacity of stiffened panels.