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Zhang, Shuang,Shang, Wenting,Yang, Xiaoxi,Zhang, Shujuan,Zhang, Xiaogang,Chen, Jiawei Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.9
The immobilization of enzyme is one of the key issues both in the field of enzymatic research and industrialization. In this work, we reported a facile method to immobilize Candida Antarctica lipase B (CALB) in alginate carrier. In the presence of calcium cation, the enzyme-alginate suspension could be cross-linked to form beads with porous structure at room temperature, and the enzyme CALB was dispersed in the beads. Activity of the enzyme-alginate composite was verified by enzymatic hydrolysis reaction of p-nitrophenol butyrate in aqueous phase. The effects of reaction parameters such as temperature, pH, embedding and lyophilized time on the reactive behavior were discussed. Reuse cycle experiments for the hydrolysis of p-nitrophenol butyrate demonstrated that activity of the enzyme-alginate composite was maintained without marked deactivation up to 6 repeated cycles.
Xiaogang Li,Renchun Yang,Junsheng Wu,Xin Zhang,Zhihua Zhang 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.1
Two mesoporous material Ni/γ-Al2O3 catalysts were prepared and characterized by ICP-AES, XRD, and TPR. The differences in reaction activity between Ni-in-Al2O3 and Ni-on-Al2O3 were investigated for hydrotreating of crude 2-ethylhexanol. The results show that the Ni species (Ni-on-Al2O3) exhibit excellent hydrogenation activities at a wide range of H2 pressure and space velocity, while the Ni species (Ni-in-Al2O3) exhibit similar activities with those of Ni-on-Al2O3 only at higher H2 pressure and lower space velocity. Due to the presence of extensively exposed Ni species on the Ni-on-Al2O3 catalyst, its hydrogenation performance was increased significantly because of the low interphase mass transfer resistance.
Shuang Zhang,Wenting Shang,Xiaoxi Yang,Shujuan Zhang,Xiaogang Zhang,Jiawei Chen 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.9
The immobilization of enzyme is one of the key issues both in the field of enzymatic research and industrialization. In this work, we reported a facile method to immobilize Candida Antarctica lipase B (CALB) in alginate carrier. In the presence of calcium cation, the enzyme-alginate suspension could be cross-linked to form beads with porous structure at room temperature, and the enzyme CALB was dispersed in the beads. Activity of the enzyme-alginate composite was verified by enzymatic hydrolysis reaction of p-nitrophenol butyrate in aqueous phase. The effects of reaction parameters such as temperature, pH, embedding and lyophilized time on the reactive behavior were discussed. Reuse cycle experiments for the hydrolysis of pnitrophenol butyrate demonstrated that activity of the enzyme-alginate composite was maintained without marked deactivation up to 6 repeated cycles.
( Zhenghong Zhang ),( Helong Hao ),( Zhongmei Tang ),( Zhengzheng Zou ),( Keya Zhang ),( Zhiyong Xie ),( Lilia Babe,),Frits Goedegebuur,Xiaogang Gu 한국미생물생명공학회(구 한국산업미생물학회) 2015 Journal of microbiology and biotechnology Vol.25 No.8
Thermolysin and its homologs are a group of metalloproteases that have been widely used in both therapeutic and biotechnological applications. We here report the identification and characterization of a novel thermolysin-like protease, BtsTLP1, from insect pathogen Bacillus thuringiensis serovar Sichuansis strain MC28. BtsTLP1 is extracellularly produced in Bacillus subtilis, and the active protein was purified via successive chromatographic steps. The mature form of BtsTLP1 has a molecule mass of 35.6 kDa as determined by mass spectrometry analyses. The biochemical characterization indicates that BtsTLP1 has an apparent Km value of 1.57 mg/ml for azocasein and is active between 20oC and 80oC. Unlike other reported neutral gram-positive thermolysin homologs with optimal pH around 7, BtsTLP1 exhibits an alkaline pH optimum around 10. The activity of BtsTLP1 is strongly inhibited by EDTA and a group of specific divalent ions, with Zn2+ and Cu2+ showing particular effects in promoting the enzyme autolysis. Furthermore, our data also indicate that BtsTLP1 has potential in cleaning applications.
SonicStream: A Network Coding Based Live P2P Media Streaming SystemWith Rich User Experiences
Xiaogang Chen,Ning Ren,Xiaochen Zhang,Xin Wang,Jin Zhao 한국통신학회 2008 Journal of communications and networks Vol.10 No.4
Recent studies have convinced that network coding can improve the performance of live media streaming in terms of startup delay, resilience to peer dynamics, as well as reduced bandwidth cost on dedicated streaming servers. However, there still exist some strategy drawbacks and neglected problems which need to be further researched. In addition to the commonly used evaluation parameters of the network and user experiences mentioned above, we focus on additional key factors, playback lag and switch lag, which have not been fully explored in previous work. In this paper, we present SonicStream, a novel and fully implemented live peer to peer (P2P) media streaming system with consideration of rich user experiences, including startup delay, playback continuity, playback lag, switch lag, etc. In pursuit of a further enhanced user experience, we revise traditional peer selection/data scheduling methods. Through a series of experimental evaluations and a cautious comparison with the latest similar work R², the superior performance of SonicStream has been preliminarily verified.
Neutral-point Potential Balancing Method for Switched-Inductor Z-Source Three-level Inverter
Xiaogang Wang,Jie Zhang 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.3
Switched-inductor (SL) Z-source three-level inverter is a novel high power topology. The SL based impedance network can boost the input dc voltage to a higher value than the single LC impedance network. However, as all the neutral-point-clamped (NPC) inverters, the SL Z-source threelevel inverter has to balance the neutral-point (NP) potential too. The principle of the inverter is introduced and then the effects of NP potential unbalance are analyzed. A NP balancing method is proposed. Other than the methods for conventional NPC inverter without Z-source impedance network, the upper and lower shoot-through durations are corrected by the feedforward compensation factors. With the proposed method, the NP potential is balanced and the voltage boosting ability of the Z-source network is not affected obviously. Simulations are conducted to verify the proposed method.
Carbon-coated Mg–Al layered double oxide nanosheets with enhanced removal of hexavalent chromium
Xiaogang Zheng,Fuyan Kang,Xinhui Liu,Hao Peng,JinYang Zhang 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-
Carbon-coated Mg–Al layered double oxide (MgAl@C LDO) nanosheets were synthesized for the removalof hexavalent chromium (Cr(VI)) ions. Carbon coating could enhance the sorption capacity of Mg5Al1 LDOfor the Cr(VI) removal. The sorption capacity of Mg5Al1@C LDO increased and then decreased with anincrease in carbon-coated content, of which the Mg5Al1@C-2 with a carbon thickness of around 5.0 nmexhibited the best sorption capacity. The sorption behaviors of Mg5Al1@C-2 was explained by Langmuirsorption model, pseudo-second-order model, Weber–Morris model, and Boyd kinetic model. Mg5Al1@C-2 for Cr(VI) removal was a spontaneous, endothermic, and chemisorption process.
Xiaogang Zheng,Fuyan Kang,Congying Huang,Sihao Lv,JinYang Zhang,Hao Peng 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.88 No.-
ZnS–ZnO–Sm2O3 (Zn–Sm–XY) composites were prepared via the high-temperature calcination of coreshellstructured ZnS@Sm2O3 for the enhanced photocatalytic degradation of dyes and antibiotics invisible light region. Effects of calcined temperature, Sm2O3 content, pH value, contaminantconcentration, and inorganic ions on the photocatalytic activity were investigated. Ternary Zn–Smcomposites exhibit the excellent photocatalytic activity for the visible light driven degradation oftetracycline hydrochloride. Among these composites, Zn–Sm–2B prepared via the heat-treatment ofZnS–Sm2O3 at 673 K shows the best photocatalytic activity for the removal of tetracycline hydrochloride. The enhanced photocatalytic activity of Zn–Sm–2B is also achieved for the visible light drivendegradation of methyl orange, methylene blue, and rhodamine B within 20 min. In addition, Zn–Sm–6Ccalcined from Zn–Sm–C at 1073 K as well as Zn–Sm–2B exhibits excellent photocatalytic activity. OH andO2radicals are vital for the enhanced photocatalytic activity of Zn–Sm–2B and Zn–Sm–2B in visiblelight region, respectively. The lattice defects, sulfur vacancies, and oxygen vacancies facilitate the efficientcharge transfer and the rapid separation of electron-hole pairs at the junction interface of Zn–Sm–2B.
A study of binomial AR(1) process with an alternative generalized binomial thinning operator
Zhang Jie,Wang Jiacong,Tai Zhiyan,Dong Xiaogang 한국통계학회 2023 Journal of the Korean Statistical Society Vol.52 No.1
In order to describe the fnite-range integer-valued time series data with dependent structure and excess zeros, we introduce a new binomial AR(1) process with an alternative generalized binomial thinning operator. Some probabilistic and statistical properties of this model are derived. Model parameters are estimated by conditional least squares method and conditional maximum likelihood method. The consistency and asymptotic normality of these estimators are studied. In addition, a real data analysis shows a better performance of the proposed model than other existing models.