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InSAR Studies of Alaska Volcanoes
Lu Zhong,Wicks Chuck,Dzurisin Dan,Power John The Korean Society of Remote Sensing 2005 大韓遠隔探査學會誌 Vol.21 No.1
Interferometric synthetic aperture radar (InSAR) is a remote sensing technique capable of measuring ground surface deformation with sub-centimeter precision and spatial resolution in tens-ofmeters over a large region. This paper describes basics of InSAR and highlights our studies of Alaskan volcanoes with InSAR images acquired from European ERS-l and ERS-2, Canadian Radarsat-l, and Japanese JERS-l satellites.
Lu He,Hong-Bo Xu,Bing-Bing Wang,Dan-Dan Liu,Ke-Sen Qian 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.2
Poly(ethyleneimine)-functionalized organic-inorganic hybrid silica adsorbent was synthesized by hydrothermal-assisted surface grafting technique for the removal of Ni(II) ions from aqueous solution, and was characterizedby FT-IR, nitrogen adsorption and the static adsorption-desorption experiment method. The results indicated thatthe maximum static adsorption capacity of Ni(II) on poly(ethyleneimine)-functionalized hybrid silica adsorbent byhydrothermal heating method was 1.6 times as much as the conventional heating method. The poly(ethyleneimine)-functionalized hybrid silica adsorbent offered a fast kinetics for the adsorption of Ni(II), had a substantial binding capacityin the range of pH 4-8 and could be used repeatedly. The Langmuir adsorption model was more favorable thanthe Freundlich and Dubinin-Radushkevich adsorption models. The adsorption followed a pseudo-second-order modelcompared with pseudo-first-order model. Various thermodynamic parameters such as ΔGo, ΔHo and ΔSo indicated thatthe adsorption process was spontaneous and endothermic. The results showed that poly(ethyleneimine)-functionalizedhybrid silica adsorbent could be employed as an effective material for the removal of Ni(II) ions from aqueous solution.
Lu Yunjun,Li Shu,Shen Xiaodong,Zhao Yan,Zhou Dongming,Hu Dan,Cai Xushen,Lu Lixia,Xiong Xiaohui,Li Ming,Cao Min 한국미생물학회 2021 The journal of microbiology Vol.59 No.10
Streptococcus suis serotype 2 (S. suis 2) is an important zoonotic pathogen that presents a significant threat both to pigs and to workers in the pork industry. The initial steps of S. suis 2 pathogenesis are unclear. In this study, we found that the type II histidine triad protein HtpsC from the highly virulent Chinese isolate 05ZYH33 is structurally similar to internalin A (InlA) from Listeria monocytogenes, which plays an important role in mediating listerial invasion of epithelial cells. To determine if HtpsC and InlA function similarly, an isogenic htpsC mutant (ΔhtpsC) was generated in S. suis by homologous recombination. The htpsC deletion strain exhibited a diminished ability to adhere to and invade epithelial cells from different sources. Double immunofluorescence microscopy also revealed reduced survival of the ΔhtpsC mutant after cocultivation with epithelium. Adhesion to epithelium and invasion by the wild type strain was inhibited by a monoclonal antibody against E-cadherin. In contrast, the htpsC-deficient mutant was unaffected by the same treatment, suggesting that E-cadherin is the host-cell receptor that interacts with HtpsC and facilitates bacterial internalization. Based on these results, we propose that HtpsC is involved in the process by which S. suis 2 penetrates host epithelial cells, and that this protein is an important virulence factor associated with cell adhesion and invasion.
Circular Holes Punched in a Magnetic Circuit used in Microspeakers to Reduce Flux Leakage
Dan-Ping Xu,Yuan-Wu Jiang,Han-Wen Lu,Joong-Hak Kwon,Sang-Moon Hwang 한국자기학회 2016 Journal of Magnetics Vol.21 No.3
Lower flux leakage designs have become important in the development of microspeakers used in thin and miniaturized mobile phones. We propose four methods to reduce the flux leakage of the magnetic circuit in a microspeaker. Optimization was performed based on the proposed approach by using the response surface method. Electromagnetic analyses were conducted using the finite element method. Experimental results are in good agreement with the simulated results obtained in one degree-of-freedom analysis from 100 to 5 ㎑. Both the simulated and experimental results confirm that one of the proposed methods is much more effective in reducing flux leakage than the other methods. In the optimized method, compared with a default approach, the average radial flux density in the air gap decreased only by 5.5%, the maximum flux leakage was reduced by 28.6%, and the acoustic performance at primary resonance decreased by 0.45 ㏈, which gap is indiscernible to the human ear.
Kinetics of Sn(Oct)2-Catalyzed Ring Opening Polymerization of ε-Caprolactone
Dan Wu,Yin Lv,Rui Guo,Jiahui Li,Aerman Habadati,Bowen Lu,Heyun Wang,Zhong Wei 한국고분자학회 2017 Macromolecular Research Vol.25 No.11
To evaluate the effects of different alcohols (primary, secondary, and two different tertiary alcohols) as initiators on the structure of polycaprolactone (PCL) in ring-opening polymerization (ROP), four experiments were conducted in toluene with tin(II) 2-ethylhexanoate (Sn(Oct)2) as the catalyst. The kinetics of ε-caprolactone (ε-CL) ROP at different temperatures and monomer concentrations were studied with n-butanol as the initiator and Sn(Oct)2 as the catalyst. The kinetic plot of ln(M0/Mt) vs. time (t) seems a linear, which indicates that the propagation rate is in the first order with respect to monomer concentration. When the reaction temperature increased, the reaction rate and the final relative maximum monomer conversions also increased. The molecular weight of PCL initially increased and then decreased as monomer conversion increased. This behavior can be attributed to the high viscosity of the system, which affected monomer diffusion and polymer chain propagation. In addition, prolonging reaction time caused inter-/intramolecular transesterification. However, when monomer concentration decreased, the reaction rate decreased. The actual activation energy of Sn(Oct)2-catalyzed ROP of ε-CL in toluene was -75 kJ/mol.
The Antibacterial Mechanism of Zn(II) Frame Supported on Alginate Membrane
Dan Luo,Ruo-Wei Lu,Cui-Juan Wang,Yan Tong,Cheng Liu,Yu-Mei Xiao,Yan-Xia Chen 대한화학회 2020 Bulletin of the Korean Chemical Society Vol.41 No.11
In order to solve the problem of antibiotic-resistant bacteria caused by excessive use of antibiotics, herein, an antibacterial membrane composed of natural sodium alginate (ALG), zeolite imidazolate skeleton (ZIF-8) and niflumic acid (NIF) was reported. The membrane serves as a versatile platform for local antibacterial. This report carried out in-depth research on the physical properties and antibacterial mechanism of the synthesized sodium alginate composite film. The data shows that the sodium alginate-based antibacterial film has a continuous antibacterial effect, and the release of antibacterial molecules can be controlled according to changes in the external environment. The results show that the complex has stronger mechanical and bacteriostatic properties. Niflumic acid and Zn(II) have synergistic antibacterial effect. The complex promotes bacterial death by hindering bacterial respiratory metabolism and destroying cell membrane structure.