W(110) 표면에 CO의 흡착

이경희,유위량,한현석,부진효,이순보,곽현태 성균관대학교 기초과학연구소 1998 論文集 Vol.49 No.-

The interaction of CO with W(110) surface was investigated through LEED, TDS, and photoelectron spectroscopy using synchrotron radiation under UHV condition. After CO saturation at RT, two desorption states, called α and β , were observed at about 400 and 1150 K in thermal desorption spectra, respectively. The kinetics of 3-CO followed the first order kinetics, indicating the existence of molecular CO on W(110) surface. This is contrary to the previous results. The O 1s BE(binding energy) of CO adsorbed on W(110) surface at room temperature was 529.9 eV. On the other hand, the O 1s BE of β-CO after heating to 900 K was different from that of oxygen adsorbed W(110) surface, suggesting a different adsorption state. According to the UP valence band spectra, we observed two peaks at near -10.7 eV (4σ) and -7.0 eV (5σ+1π), indicating the molecular adsorption of CO at room temperature. Furthermore we could see the 4σ peak at the various photon energy and elevated temperatures. Comparing the energy separation, Δ(4σ-1π) , between 4σ and 1π UP peaks of chemisorbed CO, we found that an increased separation reflects an decreased C-O bond strength. Therefore on the basis of TDS and photoelectron spectroscopy, we could suggest that β state of CO on W(110) may not be dissociated and has an adsorption geometry of lying-down mode.

Discovery of novel glycoside hydrolases from C-glycoside-degrading bacteria using sequence similarity network analysis

Wei Bin,Wang Ya-Kun,Yu Jin-Biao,Wang Si-Jia,Yu Yan-Lei,Xu Xue-Wei,Wang Hong 한국미생물학회 2021 The journal of microbiology Vol.59 No.10

C-Glycosides are an important type of natural product with significant bioactivities, and the C-glycosidic bonds of C-glycosides can be cleaved by several intestinal bacteria, as exemplified by the human faeces-derived puerarin-degrading bacterium Dorea strain PUE. However, glycoside hydrolases in these bacteria, which may be involved in the C-glycosidic bond cleavage of C-glycosides, remain largely unknown. In this study, the genomes of the closest phylogenetic neighbours of five puerarin-degrading intestinal bacteria (including Dorea strain PUE) were retrieved, and the protein-coding genes in the genomes were subjected to sequence similarity network (SSN) analysis. Only four clusters of genes were annotated as glycoside hydrolases and observed in the genome of D. longicatena DSM 13814T (the closest phylogenetic neighbour of Dorea strain PUE); therefore, genes from D. longicatena DSM 13814T belonging to these clusters were selected to overexpress recombinant proteins (CG1, CG2, CG3, and CG4) in Escherichia coli BL21(DE3). In vitro assays indicated that CG4 efficiently cleaved the O-glycosidic bond of daidzin and showed moderate β-D-glucosidase and β-D-xylosidase activity. CG2 showed weak activity in hydrolyzing daidzin and pNP- β-D-fucopyranoside, while CG3 was identified as a highly selective and efficient α-glycosidase. Interestingly, CG3 and CG4 could be selectively inhibited by daidzein, explaining their different performance in kinetic studies. Molecular docking studies predicted the molecular determinants of CG2, CG3, and CG4 in substrate selectivity and inhibition propensity. The present study identified three novel and distinctive glycoside hydrolases, highlighting the potential of SSN in the discovery of novel enzymes from genomic data.

Aeromonas hydrophila cytosolic 5’-methylthioadenosine/S-adenosylhomocysteine nucleosidase MtaN-2

Jinli Chen,Fei Shang,Lulu Wang,Wei Liu,Yuanyuan Chen,Jing Lan,Liming Jin,Nam-Chul Ha,Chunshan Quan,Yongbin Xu 한국구조생물학회 2018 Biodesign Vol.6 No.3

5’-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) plays a critical role in diverse pathways in bacterial cells such as biological methylation, polyamine biosynthesis, methionine recycling, and bacterial quorum sensing. It has been known that MtaN catalyzes the hydrolysis of N-ribosidic bond of adenosine-based substrates such as S-adenosyl-L-homocysteine (SAH), S-methyl-5’-thioadenosine (MTA) and 5’-deoxyadenosine (5’-DOA). In Aeromonas hydrophila, there are two MtnN subfamily proteins: MtaN-1, a periplasmic protein with an N-terminal signal peptide; and MtaN-2, a cytosolic protein. In this study, MtaN-2 from A. hydrophila was successfully expressed and purified using Ni-NTA affinity, Q anion-exchange, and gel-filtration chromatography. We first crystallized apo MtaN-2 but it diffracted to a low resolution of 5.1 Å. New crystals suitable for diffraction were obtained by adding 2 mM adenosine, a substrate analog of MtaN-2 during purification process and the crystals diffracted to the resolution of 2.0 Å. The crystals belong to the trigonal space group P31 or P32, with unit-cell parameters of a = b = 74.94 Å and c = 185.21 Å. The asymmetric unit contains four complexes of MtaN-2 with hydrolysis products of adenosine.

Synthesis and Non-Isothermal Crystallization Behavior of Poly(ethylene-co-1,4-butylene terephthalate)s

Jin Shu Yu,De Ri Zhou,Wei Min Chai,Byeong Du Lee,Seung Woo Lee,Jin Hwan Yoon,Moon Hor Ree 한국고분자학회 2003 Macromolecular Research Vol.11 No.1

Comprehensive Evaluation of Impacts of Connecting Distributed Generation to the Distribution Network

Jin, Wei,Shi, Xuemei,Ge, Fei,Zhang, Wei,Wu, Hongbin,Zhong, Chengyuan The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.2

In this paper, we study the various impacts of connecting distributed generation (DG) to the distribution network. The comprehensive evaluation index system (CEIS) of four hierarchies is established, considering economy, reliability and voltage quality, and the calculation methods of different indexes are presented. This paper puts forward an improved triangular fuzzy number analytic hierarchy process (ITFNAHP) to weight the second level indexes (SLI) and the third level indexes (TLI), and calculates the variation coefficient to weight the fourth level indexes (FLI). We calculate the comprehensive weight coefficients based on the weight coefficients of the SLI, TLI and FLI, and then calculate the comprehensive evaluation of satisfaction (CES) of different access schemes. On the basis of the IEEE 33-bus example system, simulations of the calculation methods and the comprehensive evaluation method are carried out under different DG access schemes according to the same total investment cost and the same permeability, respectively, and the simulation results are analyzed and discussed.

Enhanced Production of L-Tryptophan with Glucose Feeding and Surfactant Addition and Related Metabolic Flux Redistribution in the Recombinant Escherichia coli

Wei Luo,Jin Huang,Xiangcheng Zhu,Lei Huang,Jin Cai,Zhi-nan Xu 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.1

The production of L-tryptophan was investigated in a recombinant strain Escherichia coli W3110-ZDrr. It was observed that phosphate and feeding strategies are key factors to ensure the good cell growth and high production of L-tryptophan. The simple exponential feeding strategy could only produce 10.6 g/L L-tryptophan due to the improper feeding rate; while the manual glucose-feedback feeding approach could effectively control the substrate and inhibit the formation of acetate, and thus improvemed the Ltryptophan production to 25.5 g/L. The modified exponential feeding approach avoided overfeeding or underfeeding and achieved high production of L-tryptophan. Moreover, the addition of Tween 60 or PL61 could enhance the cell growth and the production of L-tryptophan in the fed-batch mode. Subsequent metabolic flux analysis showed that more carbon flux was distributed into the biosynthesis of Ltryptophan when Tween 60 or PL61 was supplied. The present work presents one base for further large-scale production of this important amino acid.

Study and Experimentation on Detection of Nicks inside of Porcelain with Acoustic Emission

Wei JIN,Fen LI 한국멀티미디어학회 2006 멀티미디어학회논문지 Vol.9 No.12

Valve core shapes analysis on flux through control valves in nuclear power plants

Jin-yuan Qian,Cong-wei Hou,Juan Mu,Zhi-xin Gao,Zhi-jiang Jin 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.10

Control valves are widely used to regulate fluid flux in nuclear power plants, and there are more than1500 control valves in the primary circuit of one nuclear power plant. With their help, the flux can beregulated to a specific level of water or steam to guarantee the energy efficiency and safety of the nuclearpower plant. The flux characteristics of the control valve mainly depend on the valve core shape. In orderto analyze the effects of valve core shapes on flux characteristics of control valves, this paper focuses onthe valve core shapes. To begin with, numerical models of different valve core shapes are established, andresults are compared with the ideal flux characteristics curve for the purpose of validation. Meanwhile,the flow fields corresponding to different valve core shapes are investigated. Moreover, relationshipsbetween the valve core opening and the outlet flux under different valve core shapes are carried out. Theflux characteristics curve and equation are proposed to predict the outlet flux under different valve coreopenings. This work can benefit the further rese

Effect of LiF addition on the sinterability, crystal structure and microwave dielectric properties of Li3Mg4NbO8 ceramics

Wei Jin,Jingjing Tan,Jiaxin Yan,Yao Tao,Ningning Yao,Xiaomeng Ruan,Cuijin Pei 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.6

The normative solid-state reaction process was adopted to prepare Li3Mg4NbO8 ceramics with LiF addition. We investigatedthe impacts of LiF additive on the crystal structure, sinterabillity as well as dielectric performance at microwave region of theLi3Mg4NbO8-basic ceramics. XRD analysis confirmed that the addition of LiF to Li3Mg4NbO8 lead to the formation of newphase Li4Mg4NbO8F with cubic rock salt structure. The densified temperature of Li3Mg4NbO8-basic ceramics could beeffectively reduced from 1150 oC to 900 oC with LiF addition. Both the permitivity (εr) and quality factor (Qf) of presentceramics were is closely correlated with the bulk density and cell volume. The 900 oC-sintered Li3Mg4NbO8-basic ceramicsowned excellent chemical compatibility with silver and optimized microwave dielectric performance (εr ~13. 4, Qf ~ 32,400GHz at 9.4 GHz, and temperature coefficient of resonant frequency (τf) ~ -43.0 ppm/℃).

Orthologous based study to detect the fast evolutionary genes related to rice pre-harvest sprouting

Wei Tong,Tae-Sung Kim,Kyu-Won Kim,Yong-Jin Park 한국육종학회 2015 한국육종학회 심포지엄 Vol.2015 No.07

Pre-harvest sprouting (PHS) results in lower yields for rice and other crops, especially in rainy season before harvest. By using gene based functional studies to reveal the mechanism of PHS related pathways can be a good way in breeding for more PHS resistant accessions. Orthologous genes, which are homologous genes that diverged after a speciation event, generally maintain a similar function in different species to that of the ancestral gene in which they evolved from. Applied with a McDonald-Kreitman Test (MKT), we examined more than 10,000 orthologous genes between rice (Oryza sativa) and Brachypodium (outgroup) based on different phenotypic groups in order to find some fast evolutionary genes in rice PHS. Three groups which represented the PHS susceptible (group 1), PHS medium (group 2) and PHS resistant (group 3) were separated based on the phenotype and each group was examined with the outgroup for MKT. Total 60 fast evolutionary genes that have a positive selection with FDR ≤ 0.05 were found in the three groups, and 19, 5 and 8 genes were specific existed in group 1, 2 and 3, respectively. Annotation of these genes were conducted and the predicted functions were investigated, leading that one Ethylene receptor-like gene that may related to PHS based on the previous studies, which need to be validated later, however. In addition, network analysis of these characterized genes were also investigated, which could reveal the connection of genes between each other. Moreover, the association study between the candidate gene ethylene receptor and the PHS phenotype was performed and indicated that this gene is significantly correlated with PHS in rice. All these above indicated that with this orthologous based method, we can find some important candidate genes that may play an important role in some traits.