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Xuejun, Cao,Jianhang, Zhu,Dongzhi, Wei,Hur, Byong Ki 한국공업화학회 2002 Journal of Industrial and Engineering Chemistry Vol.8 No.3
Partition behavior of cephalexin and 7-ADCA in PEG-salts and EOPO-salts aqueous two-phase systems has been investigated under various different conditions. Effect of polymer molecular weight, salts types, tie line length on partition coefficients of cephalexin and 7-ADCA were described. Additives such as salts, water miscible solvents and surfactants were used to improve partition of cephalexin and 7-ADCA. NaSCN shows greatest influence on partition of cephalexin and 7-ADCA in 20% PEG 400-17.5% (NH_4)_2SO_4. Cephalexin and 7-ADCA partition coefficients reached 12.92 and 2.58, respectively. While NaCI shows greatest influence on partition of cephalexin and 7-ADCA in E0_40PO_60-(NH_4)_2SO_4. In 15% E0_40P0_60-13% (NH_4)_2SO_4 ATPS, partition coefficients of cephalexin and 7-ADCA reached 0.08 and 0.42, respectively. Cephalexin and 7-ADCA shows different partition trend in PEG-(NH_4)_2SO_4 and EOPO-(NH_4)_2SO_4 ATPS. In EOPO-(NH_4)_2SO_4 ATPS, diagrams of PEG3000-(NH_4)_2SO_4, E0_40PO_60-(NH_4)_2SO_4, E0_20PO_80-(NH_4)_2SO_4 were prepared and their differences were analyzed, and recovery of E0_40PO_60-(NH_4)_2SO_4 ATPS was performed with yield of 90-95%.
Valley-dependent electron transport in ferromagnetic/normal/ ferromagnetic silicene junction
Xuejun Qiu,Yanfu Cheng,Zhenzhou Cao,Jiemei Lei 한국물리학회 2015 Current Applied Physics Vol.15 No.6
The electron transport through ferromagnetic/normal/ferromagnetic silicene junction with an induced energy gap is investigated in this work. The energy gap can be tuned by applying electric field or exchange fields due to the buckled structure of silicene. We analyze the local electric field, exchange field, length of normal region-dependence transmission probabilities of four groups and valley conductance. These transmission probabilities and valley conductance can be turned on or off by adjusting the local electric field and exchange field. In particular, a fully valley polarized conductance with 80% transmission is found in this junction, which can be caused by the interplay of valley-dependent massive Dirac electron, the exchange potential and the on-site potential difference of sublattices. Our findings will benefit applications in silicene-based high performance nano-electronics.
Synthesis and Application of a Light-sensitive Polymer Forming Aqueous Two-phase Systems
Kong FanQi,Cao Xuejun,Xia Jinan,허병기 한국공업화학회 2007 Journal of Industrial and Engineering Chemistry Vol.13 No.3
Abstract:A visible light-sensitive polymer that forms aqueous two-phase systems has been synthesized by using N-isopropylacrylamide, n-butyl acrylate, and chlorophyllin sodium copper salt as monomers, and its capability to form aqueous two-phase system was investigated. The polymer formed aqueous two-phase systems with Dextran20000. Over 98 % of the polymer could be recovered by using light radiation at 488 nm. The recovery experiments were repeated five times. The recoveries were maintained fairly stable. The polymer could be recovered at more than 95 % by using thermo separation. Trypsin constantly maintained a relatively high activity and stability in the aqueous two-phase systems.
Preparation of ursodeoxycholic acid by direct electro-reduction of 7-ketolithocholic acid
Xiangxi Yuan,Xuejun Cao,Xiaolei Ma 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.7
A novel method of producing ursodeoxycholic acid was developed through direct electro-reduction of 7-ketolithocholic acid in a divided electrolytic cell. Titanium ruthenium mesh electrode was used as the anode, whilehigh purity lead plate was used as the cathode. The process was optimized with regards to the electrolyte, temperature,concentration of methanol, current density and concentration of anolyte. When potassium bromide was used as theelectrolyte, the saturated solution of 7-ketolithocholic acid in 85-93% (v/v) methanol, current density 9.52-28.6 A/m2and concentration of anolyte at 4-6% (w/w), the maximum percentage yield of ursodeoxycholic acid could be 47%. The method will provide a potential approach for large-scale production of ursodeoxycholic acid.
Catalytic transfer hydrogenation of 7-ketolithocholic acid to ursodeoxycholic acid with Raney nickel
He Tian,Xuejun Cao,Hongbin Zhao 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2
Ursodeoxycholic acid was produced by the stereoselective reduction of 7-ketolithocholic acid. This hydrogenation reaction was catalyzed by the T-1 Raney nickel and potassium borohydride was used as hydrogen donor instead of inflammable hydrogen gas. Potassium tert-butoxide was introduced to improve yield of ursodeoxycholic acid from about 70% to a maximum of 94% by inducing the stereoselectivity on hydroxyl group at 40 8C and atmospheric pressure. Reduction reaction conditions such as amount of reactants, temperature and stirring speed were optimized. The whole process is safe and low-cost. Eventually, the product, ursodeoxycholic acid was characterized by IR, 1H NMR and 13C NMR spectra.
Zhihua Shao,Fanqi Kong,Xuejun Cao 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.1
Our Laboratory has synthesized a novel light-sensitive and recycling copolymer PNBC. The PNBC copolymer could form recycling aqueous two-phase systems with Dextran. Recycling aqueous two-phase systems have important application in bioseparation engineering. Phase diagram prediction of the novel aqueous two-phase systems also is an important aspect in engineering. This article applied the Cabezas model and effective excluded volume (EEV) model to the experimental data of light-sensitive recycling aqueous two-phase systems. It has been found that the EEV model could consist with experimental data very well. The maximum absolute error and average absolute error is 0.81% (wt%) and 0.23% (wt%), respectively.
A novel process for preparing pure chenodeoxycholic acid from poultry bile
Junfen Wan,Jiemin He,Xuejun Cao 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.1
Macroporous adsorption by column chromatography was introduced into chenodeoxycholic acid (CDCA)separation from duck bile in this study. After bile saponification in 2.5 M NaOH for 6 h and conversion of CDCA calcium salt with Na2CO3, CDCA was purified by the hydrophobic chromatography with macroporous resin HZ-802. With 40% ethanol as loading solvent and 50% and 60% ethanol as stage elution solvents, high purity of CDCA was obtained, and its melting point could be achieved 160–170 8C (99%purity) after crystallization by 65–70 8C water bath cultivation. The novel process was environmentally friendly and economical compared to conventional method, and it has been successfully scaled up in industry.
Guo Zhou,Haiyan Meng,Yan Cao,Xuejun Kou,Shuxiang Duan,Leilei Fan,Ming Xiao,Fangzhou Zhou,Zhenzi Li,Zipeng Xing 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.64 No.-
The tiny Ag nanoparticles-uniformly decorated Ti3+ self-doped porous black TiO2 pillars (Ag-TPBTPs) are prepared, which show obvious surface plasmon resonance (SPR) and extend the photoresponse to visible light and near-infrared region (∼1500 nm). The Ag-TPBTPs exhibit excellent solar-driven photocatalytic activities by mineralizing of high-toxic 2,4-dichlorophenol (∼99%), which is three times higher than that of the pristine TiO2. The remarkable solar-driven photocatalytic performance can be ascribed to the porous pillars structure offering more surface active sites, the self-doped Ti3+ and SPR effect of Ag nanoparticles improving the utilization of solar light, and enhancing the spatial separation efficiency of photogenerated charge carriers.
Sipeng Li,Jialing Chen,Xuanjun Zhang,Zhaoyang Ding,Xuejun Cao 한국생물공학회 2018 Biotechnology and Bioprocess Engineering Vol.23 No.1
Microbial transglutaminase (MTG) has been widely used in the food and pharmaceuticals industries. In this study, MTG was purified using affinity precipitation with an affinity polymer (PMMDN-T), which was synthesized using a pH-responsive polymer (PMMDN) coupled with L-thyroxin as an affinity ligand. Interactions between MTG and PMMDN-T were investigated using turbidimetric titration, zeta potential measurements, and low-field nuclear magnetic resonance (LF-NMR). We found different behaviors, architectures, and phase states of pH-dependent interactions between MTG and PMMDN-T interactions. Binding energetics between MTG and PMMDN-T were determined by isothermal titration calorimetry (ITC). The isoelectric point (pI) of the affinity polymer was 4.65 and was recovered with 96.7% efficiency after recycling the polymer three times. The optimal adsorption condition was 0.02 mol/L phosphate buffer (pH 6.0) with 1.0 mol/L NaCl at 30.0°C and a ligand density of 50.0 μmol/g. The maximum elution recoveries of total MTG were 98.44% (protein) with 92.19% (activity) using 0.02 mol/L pH 10.0 Gly-NaOH as the eluent.