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Liwei Ren,Honghua Jia,Min Yu,Wenzhong Shen,Hua Zhou,Ping Wei 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.5
Candida rugosa lipase (CRL) is one of the most widely used lipases. To enhance the catalytic abilities of CRL in both aqueous and non-aqueous phases, hollow silica microspheres (HSMSs) with a pore size of 18.07 nm were used as an immobilization support, and aldehydecontaining dextrans were employed to further cross-link the adsorbed CRL. In the experimental ranges examined,the loading amount of lipase linearly increased to 171 ±3.4 mgprotein/gsupport with the CRL concentration and all the adsorption equilibriums were reached within 30 min. After simple cross-linking, the tolerance to pH 4.0 ~ 8.0 as well as the thermal stability of immobilized CRL at 40 ~ 80oC were both substantially increased, and 82 ± 2.1% activity remaining after the sixth reuse. The immobilized CRL was successfully applied to the resolution of racemic ibuprofen in non-aqueous phase. The initial reaction rate increased by 1.4- and 3.6-fold compared with the rates of adsorbed and native lipases, respectively. Furthermore, the R-ibuprofen was obtained at ee > 93%, and the enantiomeric ratio reached E > 140 at the conversion of 50 ± 1.5% within 48 h.
Zan Wang,Chaofei Gao,Liwei Zheng,Jikun Ren,Wei Wang,Yushuai Zhang,Shijie Han 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.1
Ultrasonic signals will be generated when partial discharge occurs in internal insulation faults in large oil immersed power transformers: because the ultrasonic signal has strong anti-interference ability and has no direct electromagnetic contact with the equipment, it is widely used in transformer fault detection and positioning. In this paper, the fi nite element method (FEM) is used to simulate the ultrasonic signal in a 35 kV power transformer. The infl uence of transformer case on ultrasonic signal propagation is considered, and the propagation law of the ultrasonic signal inside the transformer is obtained. Fabry–Pérot (F–P) fi bre acoustic sensors with a centre frequency of 28 kHz were fabricated. A partial discharge detection test was carried out in a 35 kV transformer winding model using the F–P sensors. The test results show that the ultrasonic waveform detected by the F–P sensors are in good agreement with the simulation results, and the propagation of the ultrasonic wave inside the transformer is verifi ed. It lays a foundation for detecting and locating PDs in power transformer by F–P acoustic sensors.
Fluorinated/Non-Fluorinated Sulfonated Polynaphthalimides as Proton Exchange Membranes
Yang Song,Chang Liu,Dianfu Ren,Liwei Jing,Zhenhua Jiang,Baijun Liu 한국고분자학회 2013 Macromolecular Research Vol.21 No.5
Two -SO3H containing diamine monomers, 2,5-bis(4-amino-2-trifluoromethylphenoxy)benzenesulfonic acid and 2,5-bis(4-aminophenoxy)benzenesulfonic acid were successfully synthesized through a typical aromatic nucleophilic substitution reaction followed by a reduction reaction, respectively. Derived from the diamine monomers,two series of sulfonated naphthalic polyimides (polynaphthalimides) containing ether and ketone linkages were synthesized through a “one pot” polymerization reaction. Some properties including thermal stability, mechanical properties, water uptake, swelling dimensional ratio, methanol permeability, and proton conductivity were thoroughly investigated. Some exhibited attractive properties as proton exchange membranes. It was found that the fluorinated series (CF3-SPI-X) exhibited higher dimensional stability and lower methanol permeability in comparison with non-fluorinated ones (SPI-X) at the same -SO3H group content.