Yuncheng, China

Yuncheng University

www.ycu.edu.cn
Yuncheng, China

Yuncheng University is a university in Shanxi, China under the authority of the provincial government. It was formerly known as Yuncheng Advanced Training College. It was here that Justin Hill spent three years, 1993-1995, teaching with Voluntary Service Overseas, which was the source for his first book, A Bend in the Yellow River. Wikipedia.

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Xie W.-J.,Beijing Normal University | Xie W.-J.,Yuncheng University | Zhang F.-S.,Beijing Normal University | Zhang F.-S.,Beijing Radiation Center | Zhang F.-S.,Accelerator Centre
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

The isospin-dependent quantum molecular dynamics model is used to investigate the nuclear collective flow observables in semicentral 197Au+197Au collisions at 400A MeV. It is found that the calculated results can reproduce both the experimental data and the other theoretical calculations. We find that the cluster production influences the rapidity dependence of directed flow of protons but less influences the results of tritons. Neutron-proton differential collective flows have larger values when taking the neutron effective mass less than the one of protons as compared with the case of neutron effective mass greater than the one of protons at larger rapidities and transverse momenta. Thus neutron-proton differential collective flows are proposed to be a useful probe to the neutron-proton effective mass splitting and the momentum-dependent symmetry potential. © 2014 Elsevier B.V.


Yuan S.,Shanghai University | Zhang F.,Yuncheng University
Nonlinear Analysis: Real World Applications | Year: 2010

In this paper, we consider a delayed predator-prey system with same feedback delays of predator and prey species to their growth, respectively. Using the delay as a bifurcation parameter, we investigate the stability of the positive equilibrium and existence of Hopf bifurcation of the model. It is shown that Hopf bifurcations can occur as the delay crosses some critical values. Moreover, the model can exhibit an interesting property, that is, under certain conditions, the positive equilibrium may switch finite times from stability to instability to stability, and becomes unstable eventually. By deriving the equation describing the flow on the center manifold, we can determine the direction of the Hopf bifurcations and the stability of the bifurcating periodic solutions. In addition, special attention is paid to the global continuation of local Hopf bifurcations. Using a global Hopf bifurcation result of Wu [J. Wu, Symmetric functional differential equations and neural networks with memory, Trans. Amer. Math. Soc. 350 (1998) 4799-4838.] for functional differential equations, we may show the global existence of periodic solutions. Computer simulations illustrate the results. © 2009 Elsevier Ltd. All rights reserved.


Li X.,Yuncheng University | Yu H.-Y.,Yuncheng University
Journal of Industrial Microbiology and Biotechnology | Year: 2012

A halotolerant isolate Bacillus sp. L1 producing extracellular cellulase was isolated from Yuncheng, China. Production of the enzyme started from mid-exponential phase of bacterial growth and reached a maximum level during the post-stationary phase. The cellulase was purified to homogeneity with molecular mass of 45 kDa. Substrate specificity test indicated that it was an endoglucanase for soluble cellulose. Optimal enzyme activity was found to be at 60 °C, pH 8.0, and 7.5 % NaCl. Furthermore, it was highly active and stable over broad ranges of temperature (30-80 °C), pH (7.0-9.0), and NaCl concentration (2.5-15 %), thus showing its excellent thermostable, alkali-stable, and halotolerant nature. The cellulase activity was greatly inhibited by ethylenediaminetetraacetic acid, indicating that it was a metalloenzyme. Significant inhibition by phenylmethylsulfonyl fluoride and phenylarsine oxide revealed that serine and cysteine residues were essential for the enzyme catalysis. Moreover, the cellulase was highly active in the presence of surfactants, and it showed high stability in the presence of water-insoluble organic solvents with log P owat least 0.88. Results from this study indicate that the purified cellulase from isolate L1 may have considerable potential for industrial application owing to its useful properties. © 2012 Society for Industrial Microbiology and Biotechnology.


A halophilic strain SK1 showing cellulolytic activity was isolated from Yuncheng Salt Lake, and was identified as the genus of Gracilibacillus by 16S rRNA gene sequence analysis. Cellulase production was strongly influenced by the salinity of culture medium with maximal level in the presence of 10% NaCl. Substrate specificity test indicated the crude cellulase was a multi-component enzyme system, showing a combined activity of endoglucanase, exoglucanase and β-glucosidase. Zymogram analysis indicated six different endoglucanases were secreted by this strain. The crude enzyme was highly active and stable over broad ranges of temperature (40-70 °C), pH (6.0-10.0) and NaCl concentration (7.5-17.5%), with an optimum at 60 °C, pH 8.0 and 12.5% NaCl, which showed excellent thermostable, alkali-stable and halostable properties. Moreover, it displayed high stability in the presence of hydrophobic organic solvents. Saccharification of corn stover and rice straw by the cellulase resulted in respective yields of 0.678 and 0.502 g g-1 dry substrate of reducing sugars. The enzymatic hydrolysates of corn stover were then used as the substrate for ethanol production by Saccharomyces cerevisiae. The yield of ethanol was 0.186 g g-1 dry substrate, and the efficiency of reducing sugars conversion to ethanol was about 52.8%, which suggested the prospects of the crude enzyme from Gracilibacillus sp. SK1 in application for bio-ethanol production. © 2015 Elsevier Ltd.


Background: Halotolerant bacteria are excellent sources for selecting novel enzymes. Being intrinsically stable and active under high salinities, enzymes from these prokaryotes have evolved to function optimally under extreme conditions, making them robust biocatalysts with potential applications in harsh industrial processes.Results: A halotolerant strain LY19 showing lipolytic activity was isolated from saline soil of Yuncheng Salt Lake, China. It was identified as belonging to the genus of Salimicrobium by 16S rRNA gene sequence analysis. The extracellular enzyme was purified to homogeneity with molecular mass of 57 kDa by SDS-PAGE. Substrate specificity test revealed that the enzyme preferred short-chain p-nitrophenyl esters and exhibited maximum activity towards p-nitrophenyl butyrate (p-NPB), indicating an esterase activity. The esterase was highly active and stable over broad temperature (20°C-70°C), pH (7.0-10.0) and NaCl concentration (2.5%-25%) ranges, with an optimum at 50°C, pH 7.0 and 5% NaCl. Significant inhibition of the esterase was shown by ethylenediaminetetraacetic acid (EDTA), phenylmethylsulfonyl fluoride (PMSF) and phenylarsine oxide (PAO), which indicated that it was a metalloenzyme with serine and cysteine residues essential for enzyme activity. Moreover, the esterase displayed high activity and stability in the presence of hydrophobic organic solvents with log Pow ≥ 0.88 than in the absence of an organic solvent or in the presence of hydrophilic solvents.Conclusions: Results from the present study indicated the novel extracellular esterase from Salimicrobium sp. LY19 exhibited thermostable, alkali-stable, halotolerant and organic solvent-tolerant properties. These features led us to conclude that the esterase may have considerable potential for industrial applications in organic synthesis reactions. © 2013 Xin and Hui-Ying; licensee BioMed Central Ltd.


Li X.,Yuncheng University | Yu H.-Y.,Yuncheng University
International Journal of Biological Macromolecules | Year: 2013

A haloarchaeal strain G10 with celluolytic activity was isolated from the saline soil of Yuncheng Salt Lake, China. Biochemical and physiological characterization along with 16S rRNA gene sequence analysis placed the isolate in the genus Haloarcula. The extracellular cellulase was purified to homogeneity with a molecular mass of 36kDa. Substrate specificity test indicated that it was an endoglucanase for soluble cellulose. Optimal enzyme activity was found to be at 60°C, pH 9.0 and 17.5% NaCl. Furthermore, high activity and stability over broad ranges of temperature (40-80°C), pH (7.0-10.0) and NaCl concentration (12.5-27.5%) were observed, showing thermostable, alkali-stable and halostable properties of the cellulase. Significant inhibition by EDTA, phenylmethylsulfonyl fluoride (PMSF) and diethyl pyrocarbonate (DEPC) revealed it was a metalloenzyme with serine and histidine residues essential for enzyme catalysis. The surfactants tested had little effects on the enzyme activity. The endoglucanase showed high activity and stability in the presence of non-polar hydrophobic organic solvents with log Pow≥0.88. Together these results indicated the cellulase from Haloarcula sp. G10 maybe an ideal choice for applications in industrial process under harsh conditions. © 2013 Elsevier B.V.


Zhang F.,Yuncheng University | Zheng C.,Yuncheng University
Computers and Mathematics with Applications | Year: 2011

By using a continuation theorem based on coincidence degree theory, we obtain some new sufficient conditions for the existence of positive periodic solutions for the neutral ratio-dependent predatorprey model with Holling type II functional response. © 2010 Elsevier Ltd. All rights reserved.


Li X.,Yuncheng University | Yu H.-Y.,Yuncheng University
Journal of Industrial Microbiology and Biotechnology | Year: 2013

A haloarchaeal strain LLSG7 with cellulolytic activity was isolated from the saline soil of Yuncheng Salt Lake, China. Biochemical and physiological characterization along with 16S rRNA gene sequence analysis placed the isolate in the genus Haloarcula. Cellulase production was strongly influenced by the salinity of the culture medium with the maximum obtained in the presence of 25 % NaCl. Substrate specificity tests showed that the crude cellulase was a multicomponent enzyme system, and zymogram analysis revealed that five different endoglucanases were secreted by strain LLSG7. Optimal cellulase activity was at 50 °C, pH 8.0, and 20 % NaCl. In addition, it was highly active and stable over broad ranges of temperature (40-80 °C), pH (7.0-11.0), and NaCl concentration (17.5-30 %). The cellulase displayed remarkable stability in the presence of non-polar organic solvents with log Pow C 1.97. The crude cellulase secreted by strain LLSG7 was further applied to hydrolyze alkali-pretreated rice straw and the enzymatic hydrolysate was used as the substrate for bioethanol fermentation by Saccharomyces cerevisiae. The yield of ethanol was 0.177 g per gram of pretreated rice straw, suggesting that it might be potentially useful for bioethanol production.


A halophilic isolate Salimicrobium halophilum strain LY20 producing extracellular amylase and protease was isolated from Yuncheng, China. Production of both enzymes was synchronized with bacterial growth and reached a maximum level during the early-stationary phase. The amylase and protease were purified to homogeneity with molecular weights of 81 and 30 kDa, respectively. Optimal amylase activity was observed at 70 °C, pH 10.0% and 10% NaCl. Complete inhibition by EDTA, diethyl pyrocarbonate (DEPC), and phenylarsine oxide (PAO) indicated that the amylase was a metalloenzyme with histidine and cysteine residues essential for its catalysis. Maltose was the main product of starch hydrolysis, indicating an β-amylase activity. The purified protease from LY20 showed highest activity at 80 °C, pH 10.0% and 12.5% NaCl. Complete inhibition was shown by phenylmethylsulfonyl fluoride, DEPC, and PAO, indicating that the enzyme probably belonged to the subclass of the serine proteases with histidine and cysteine residues essential for catalysis. Furthermore, both enzymes were highly stable over broad temperature (30-80 °C), pH (6.0-12.0) and NaCl concentration (2.5-20%) ranges, showing excellent thermostable, alkalistable, and halotolerant nature. The surfactants (SDS, Tween 80, and Triton X-100) did not affect their activities. In addition, both enzymes from LY20 displayed remarkable stability in the presence of water-soluble organic solvents with log Pow ≤ -0.24. © 2012 Federation of European Microbiological Societies.


Li X.,Yuncheng University | Yu H.-Y.,Yuncheng University
Folia Microbiologica | Year: 2014

A haloarchaeal strain G41 showing lipolytic activity was isolated from the saline soil of Yuncheng Salt Lake, China. Biochemical and physiological characterizations along with 16S rRNA gene sequence analysis placed the isolate in the genus Haloarcula. Lipase production was strongly influenced by the salinity of growth medium with maximum in the presence of 20 % NaCl or 15 % Na2SO4. The lipase was purified to homogeneity with a molecular mass of 45 kDa. Substrate specificity test revealed that it preferred long-chain p-nitrophenyl esters. The lipase was highly active and stable over broad ranges of temperature (30–80 °C), pH (6.0–11.0), and NaCl concentration (10–25 %), with an optimum at 70 °C, pH 8.0, and 15 % NaCl, showing thermostable, alkali-stable, and halostable properties. Enzyme inhibition studies indicated that the lipase was a metalloenzyme, with serine and cysteine residues essential for enzyme function. Moreover, it displayed high stability and activation in the presence of hydrophobic organic solvents with log Pow ≥ 2.73. The free and immobilized lipases from strain G41 were applied for biodiesel production, and 80.5 and 89.2 % of yields were achieved, respectively. This study demonstrated the feasibility of using lipases from halophilic archaea for biodiesel production. © 2014, Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i.

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