Preparation of N-Doped Nanoporous Carbon from Crude Biomass and its Electrochemical Activity

Zezhong Xu,Jingyu Si 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.3

H2O2 detection plays an important role in electrochemical sensing since H2O2 often acts as an intermediate product or regulator in various reactions. Nanoporous carbon (NPC) can be a potential candidate in electrochemical sensing because of its high specific surface area, various pore sizes and structures. In this work, we reported the preparation of N-doped NPC derived from the highly available, accessible and recyclable plant Typha orientalis. The products have high surface area (highest surface areas of 1439.0 m2 g-1) and a number of nanopores. Highest content of nitrogen atom in the product is 3.66 at.%). Typical product exhibits high electrocatalytic activity for reduction of hydrogen peroxide. The product may have further use for glucose biosensing. We developed a low-cost, simple and readily scalable approach to prepare the excellent carbon electrocatalyst directly from crude biomass. In addition, because of high surface area and doping of nitrogen element, the product may find broad applications in the fields of supercapacitors, lithium-ion batteries, gas uptake and so on.

Zn-MOF loading Cu2O cube to construct hierarchical solid cage to improve photocatalytic hydrogen evolution

Jing Xu,Zezhong Li,Zhenlu Liu,Shengming Xu,Xinyu Liu 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.126 No.-

A novel composite is constructed by loading ZIF-8 on Cu2O by in situ growth. By visible light driven semiconductorand p-p* conjugation effect of the metal–organic framework, the migration ability of photogeneratedcarriers is improved, and electrons are accumulated to participate in hydrogen ionreduction. The superior hydrogen evolution performance (981.8 lmolg1h1) and stability test indicatethat the coupling of ZIF-8 and semiconductor Cu2O successfully improves the catalytic capacity of thematerial. Cu2O provides a place to stimulate activity for ZIF-8 with high specific surface area. The electrontransfer mechanism in composites is studied by electrochemical and spectroscopy methods. This workalso provides a new opportunity for the in-situ growth of metal–organic frame materials onto singlemetaloxides.

Power Flow Algorithm for Weakly Meshed Distribution Network with Distributed Generation Based on Loop-analysis in Different Load Models

Hongsheng Su,Zezhong Zhang 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.2

As distributed generation (DG) is connected to grid, there is new node-type occurring in distribution network. An efficient algorithm is proposed in this paper to calculate power flow for weakly meshed distribution network with DGs in different load models. The algorithm respectively establishes mathematical models focusing on the wind power, photovoltaic cell, fuel cell, and gas turbine, wherein the different DGs are respectively equivalent to PQ, PI, PQ (V) and PV node-type. When dealing with PV node, the algorithm adopts reactive power compensation device to correct power, and the reactive power allocation principle is proposed to determine reactive power initial value to improve convergence of the algorithm. In addition, when dealing with the weakly meshed network, the proposed algorithm, which builds path matrix based on loop-analysis and establishes incident matrix of node voltage and injection current, possesses good convergence and strong ability to process the loops. The simulation results in IEEE33 and PG&G69 node distribution networks show that with increase of the number of loops, the algorithm’s iteration times will decrease, and its convergence performance is stronger. Clearly, it can be effectively used to solve the problem of power flow calculation for weakly meshed distribution network containing different DGs.

Power Flow Algorithm for Weakly Meshed Distribution Network with Distributed Generation Based on Loop-analysis in Different Load Models

Su, Hongsheng,Zhang, Zezhong The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.2

As distributed generation (DG) is connected to grid, there is new node-type occurring in distribution network. An efficient algorithm is proposed in this paper to calculate power flow for weakly meshed distribution network with DGs in different load models. The algorithm respectively establishes mathematical models focusing on the wind power, photovoltaic cell, fuel cell, and gas turbine, wherein the different DGs are respectively equivalent to PQ, PI, PQ (V) and PV node-type. When dealing with PV node, the algorithm adopts reactive power compensation device to correct power, and the reactive power allocation principle is proposed to determine reactive power initial value to improve convergence of the algorithm. In addition, when dealing with the weakly meshed network, the proposed algorithm, which builds path matrix based on loop-analysis and establishes incident matrix of node voltage and injection current, possesses good convergence and strong ability to process the loops. The simulation results in IEEE33 and PG&G69 node distribution networks show that with increase of the number of loops, the algorithm's iteration times will decrease, and its convergence performance is stronger. Clearly, it can be effectively used to solve the problem of power flow calculation for weakly meshed distribution network containing different DGs.

A Parametric and Accurate CAD Model of Flat End Mills Based on Its Grinding Operations

Liming Wang,Lin Kong,Jian-Feng Li,Zezhong Chen 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.10

End mills are widely used in CNC machining. However, the complex structures of end mills make it difficult to define the CAD model which determines the quality and performance of virtual cutting tests. This paper presents an accurate CAD model of end mill through analyzing kinematic models of grinding processes. Initially, a common parametric representation of grinding wheel is given. Base on the given wheel profile and the design parameters of cutters including the rake angle, core diameters and pitch angle, the representation of helix flute surface is first calculated using contact theory and also the formulation of rake angle and pitch angle are investigated. Next, four design parameters are used to control the shape of the gash which is formed via Boolean operation between the given wheel and end mill. Similarly, the peripheral edges and end edges are swept using grinding simulation. Finally, integrating all the above processes, a parametric CAD model of end mill is represented. The simulation results showed that the proposed CAD model could achieve 1e-3 mm and 2e-2 deg. in accuracy, which can be used to evaluate the grinding process or improve the future FEA analysis of end-mills.

Sorbent steam reactivation and methane-concentrated calcination for calcium-looping carbon capture: Compatibilities and limitations

Arian Ebneyamini,Jun Young Kim,Zezhong John Li,John R. Grace,C. Jim Lim,Naoko Ellis 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.87 No.-

This paper investigates the equilibrium performance of CaO hydration and CaCO3/Ca(OH)2 co-calcinationin calcium-looping processes. A novel lime hydration configuration is proposed, introducing saturatedsteam as the reactivating reagent and direct-heat-removal medium. The proposed hydrator generates asubstantial amount of superheated steam, used elsewhere as required. The slaked lime and limestone arecalcined simultaneously in a methane-concentrated oxy-fuel calciner. The equilibrium performance ofthe co-calciner is studied at different reactor temperatures, operating pressures, solid/gas feed ratios andfeed compositions. A correlation is proposed which estimates the required gaseous feed composition forautothermal, coke-free and complete sorbent regeneration using this novel technology.

Support Vector Machine Prediction Model Based on Chaos Theory

Song Liangong,Wu Huixin,Zhang Zezhong 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.2

In order to enhance prediction precision of online public opinion, it put forward a kind of online public opinion prediction model (PSR-SVR) with the combination of chaos theory and support vector regression. First of all, the original data of online public opinion were obtained throughout topic segmentation, hotspot extraction, and data aggregate. Then, time sequence of online public opinion was reconstructed throughout phase-space reconstruction. Finally, the reconstructed time sequence of online public opinion was input support vector regression for modeling and prediction, and then it was compared with other online public opinion prediction model by experiment. The result shows that compared with the contrast model, PSR-SVR improves the prediction precision and reliability of online public opinion, and the prediction results have certain practical value.

Construction of fat1 Gene Expression Vector and Its Catalysis Efficiency in Bovine Fetal Fibroblast Cells

Liu, Boyang,Yang, Runjun,Li, Junya,Zhang, Lupei,Liu, Jing,Lu, Chunyan,Lian, Chuanjiang,Li, Zezhong,Zhang, Yong-Hong,Zhang, Liying,Zhao, Zhihui Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.5

The FAT-1 protein is an n-3 fatty acid desaturase, which can recognize a range of 18- and 20-carbon n-6 substrates and transform n-6 polyunsaturated fatty acids (PUFAs) into n-3 PUFAs while n-3 PUFAs have beneficial effect on human health. Fat1 gene is the coding sequence from Caenorhabditis elegans which might play an important role on lipometabolism. To reveal the function of fat1 gene in bovine fetal fibroblast cells and gain the best cell nuclear donor for transgenic bovines, the codon of fat1 sequence was optimized based on the codon usage frequency preference of bovine muscle protein, and directionally cloned into the eukaryotic expression vector pEF-GFP. After identifying by restrictive enzyme digests with AatII/XbaI and sequencing, the fusion plasmid pEF-GFP-fat1 was identified successfully. The pEF-GFP-fat1 vector was transfected into bovine fetal fibroblast cells mediated by Lipofectamine2000$^{TM}$. The positive bovine fetal fibroblast cells were selected by G418 and detected by RT-PCR. The results showed that a 1,234 bp transcription was amplified by reverse transcription PCR and the positive transgenic fat1 cell line was successfully established. Then the expression level of fat1 gene in positive cells was detected using quantitative PCR, and the catalysis efficiency was detected by gas chromatography. The results demonstrated that the catalysis efficiency of fat1 was significantly high, which can improve the total PUFAs rich in EPA, DHA and DPA. Construction and expression of pEF-GFP-fat1 vector should be helpful for further understanding the mechanism of regulation of fat1 in vitro. It could also be the first step in the production of fat1 transgenic cattle.