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140 results on '"Liu, Weiqiao"'

7. Study on the Design of college students’ Employment courses

Author

Liu Weiqiao and Wang Lin

Subjects
Social Sciences
Abstract

with social development and technological progress, higher standards and requirements are constantly put forward for talents. traditional employment courses have problems such as lack of pertinence, single content, lack of practice, and lack of communication between teachers and students, which cannot meet the needs of students for employment-related knowledge. centering on students’ career development, the paper designs courses from five aspects: reforming the content and form of employment guidance courses, strengthening the construction of employment guidance service teachers, establishing and perfecting the extracurricular normal personalized employment guidance system, cultivating graduates’ ability to independently plan for the future, and exploring the whole-cycle personalized employment guidance service system.

Published
2023
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24. Efficient asymmetric hydrolysis of styrene oxide by Mung bean epoxide hydrolases in a supercritical CO2/buffer biphasic system

Author

Liu Weiqiao, Shu Li, Yang Fengli, Wang Bin, Liang Guobin, and Qinting He

Subjects
0106 biological sciences, Aqueous solution, Supercritical carbon dioxide, 010405 organic chemistry, Chemistry, Process Chemistry and Technology, 01 natural sciences, Supercritical fluid, 0104 chemical sciences, Hydrolysis, chemistry.chemical_compound, 010608 biotechnology, Yield (chemistry), Styrene oxide, Epoxide Hydrolases, Chemical Engineering (miscellaneous), Stepwise reaction, Waste Management and Disposal, Nuclear chemistry
Abstract

The asymmetric hydrolysis of styrene oxide (SO) by Mung bean epoxide hydrolases in a supercritical carbon dioxide (scCO2)/buffer biphasic system was investigated. With the addition of 0.80 M sodium bicarbonate, the yield of (R)-1-phenyl-1,2-ethanediol ((R)-PED) improved from 20.8% to 47.1%. Compared to the case of the aqueous monophasic system, the enantiomer excess (ee) of (R)-PED improved from 81.8% to 91.5%. Under the optimized conditions for the enzymatic reaction, i.e., at a pressure, temperature, SO concentration, and water content of 12 MPa, 40 °C, 80 mM, and 6.0% (v/v), respectively, an (R)-PED yield of 49.2% and ee of 94.1% were achieved. As the water content had a significant effect on the (R)-PED yield and ee, a stepwise reaction method was adopted. When the initial water content was 8.0% (v/v) and 1% (v/v) water was added at intervals of 1 h, the (R)-PED yield and ee reached 49.1% and 97.2%, respectively.

Published
2018

29. Efficient resolution of (R,S)-1-(1-naphthyl)ethylamine by Candida antarctica lipase B in ionic liquids

Author

Liang Guobin, Wang Bin, Zhang Chao, Qinting He, Liu Weiqiao, and Hengfei Qin

Subjects
Circular dichroism, biology, 010405 organic chemistry, Chemistry, Process Chemistry and Technology, Substrate (chemistry), 010402 general chemistry, biology.organism_classification, 01 natural sciences, Medicinal chemistry, Michaelis–Menten kinetics, Catalysis, 0104 chemical sciences, chemistry.chemical_compound, Ionic liquid, biology.protein, Candida antarctica, Physical and Theoretical Chemistry, Ethylamine, Lipase, Enantiomer
Abstract

The resolution of (R,S)-1-(1-naphthyl)ethylamine ((R,S)-NEA) by Candida antarctica lipase B (CALB) in ionic liquids (ILs) containing 1-alkyl-3-methylimidazolium cations ([Cnmim]+) and [Tf2N]−, [BF4]−, and [PF6]− anions was investigated. When the alkyl chain on the cation contained less than six carbons, the lipase activity corresponded with the hydrophobicity of the ILs, but further increase in the chain length suppressed the enzyme activity. The enzyme activity decreased depending on the anion, where [Tf2N]− > [PF6]− > [BF4]−. The effects of acyl donors, pH, temperature, water activity, and substrate concentration on the resolution were determined. Under the optimal conditions, the conversion of (R,S)-NEA and enantiomer excess of (R)-n-octyl acyl-NEA was 49.3% and 99.2%, respectively. The resolution kinetics of (R,S)-NEA by CALB in [C6mim][Tf2N] were studied and a ping-pong mechanism with a two substrate inhibition model was selected. The kinetic parameters of the fitting results were as follows: Michaelis constant of (R,S)-NEA Kma, 461.8 mmol/L; Michaelis constant of vinyl n-octanoateKmb, 262.1 mmol/L; inhibition constant of (R,S)-NEA Kia, 8737.2 mmol/L; inhibition constant of vinyl n-octanoateKib, 62336.8 mmol/L; maximum reaction rate rmax, 0.352 mmol/(mg min). Moreover, circular dichroism revealed that incubation of CALB in [C6mim][Tf2N] resulted in increased β-sheet content; its secondary structure was stable.

Published
2018

30. Simulation of Electrodepositing Process Based on Supercritical Fluid and Test Research

Author

Qian Haifeng, Shen Yu, Liu Weiqiao, Tan Heng, and Lei Weining

Subjects
Materials science, Coating, Multiphysics, Composite number, General Engineering, engineering, Coupling (piping), engineering.material, Composite material, Current density, Indentation hardness, Supercritical fluid, Cathodic protection
Abstract

The coupling field of electrodepositing process under the supercritical fluid was simulated by COMSOL Multiphysics software to study the distribution of the current density and the growth of the electrodepositing coating which was verified by the experimental supercritical composite electrodepositing coating. Simultaneously the surface morphology and microhardness of the experimental supercritical nickel-diamond electrodepositing coating were studied. The results show that the current density on cathodic edge is much higher than that of the middle section and the predicted growth of the electrodepositing coating accords with current density distribution. The error between predicted and experimental thickness of the central supercritical electrodepositing coating is smaller. The biggest microhardness HV of the composite supercritical electrodepositing coating can reach 9540 MPa (200 g), 80% higher than that of ordinary composite electrodepositing coating. The supercritical composite electrodepositing coating has smooth surface and compact structure.

Published
2018

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