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Amperometric Determination of Nitrite at Poly(Methylene Blue)-Modified Glassy Carbon Electrode
Xu, Guang-Ri,Xu, Guifang,Xu, Ming-Lu,Zhang, Zhengqing,Tian, Yuan,Choi, Han-Nim,Lee, Won-Yong Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.2
Electrochemical characteristics of nitrite ion were investigated at a poly(methylene blue)-modified glassy carbon electrode by cyclic voltammetry and differential pulse voltammetry. The poly(methylene blue)-modified glassy carbon electrode exhibited enhanced anodic signals for nitrite. The effects of key parameters on the detection of nitrite were evaluated at the modified electrode, such as pH, accumulation time, and scan rate. Under optimum condition, the chemically modified electrode can detect nitrite in the concentration range $2.0{\times}10^{-6}$ to $5.0{\times}10^{-4}$ M with the detection limit of $2.0{\times}10^{-6}$ M and a correlation coefficient of 0.999. The detection of nitrite using the chemically modified electrode was not affected by common ions such as $Na^+$, $K^+$, $Ca^{2+}$, $Cl^-$, $HPO_4^{2-}$ and $H_2PO_4^- $. The modified electrode showed good stability and reproducibility. The practical application of the present method was successfully applied to the determination of nitrite ion in cabbage samples.
( Tian Yang ),( Ming-da Wang ),( Chao Li ),( Lei Liang ),( Hao Xing ),( Li-yang Sun ),( Bing Quan ),( Han Wu ),( Xin-fei Xu ),( Timothy M ),( Pawlik ),( Wan Yee Lau ),( Feng Shen ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1
Aims: Survival after liver resection of hepatocellular carcinoma (HCC) remains poor due to a high incidence of recurrence. We sought to investigate risk factors, patterns, and long-term prognosis among patients with early and late recurrence after liver resection for hepatitis B virus (HBV)-associated HCC. Methods: Data of consecutive patients undergoing curative resection for HBV-associated HCC were analyzed. According to the time to recurrence after surgery, recurrence was divided into early (≤ 2 years) and late recurrence (> 2 years). Characteristics, patterns of initial recurrence and post-recurrence survival (PRS) were compared between patients with early and late recurrence. Risk factors of early and late recurrence, and predictors of PRS were identified by univariable and multivariable Cox-regression analyses. Results: mong 894 patients, 322 (36.0%) and 282 (31.5%) developed early and late recurrence, respectively. On multivariable analyses preoperative HBV-DNA>104 copies/ml was associated with both early and late recurrence, while postoperative no/ irregular antiviral therapy was associated with late recurrence. Compared with patients with late recurrence, patients with early recurrence had a lower proportion of intrahepatic only recurrence (72.0% vs. 91.1%, P<0.001), as well as a lower chance of receiving potentially-curative treatments for recurrence (33.9% vs. 50.7%, P<0.001) and a worse median PRS (19.1 vs. 37.5 months, P<0.001). Multivariable analysis demonstrated that early recurrence was independently associated with worse PRS (HR 1.361, 95%CI 1.094-1.692, P=0.006). Conclusions: Although risk factors associated with early recurrence and late recurrence were different, a high preoperative HBV-DNA load was an independent hepatitis-related risk for both early and late recurrence. Early recurrence was associated with
Xu Jiang,Qing-Tian Su,Xu Han,Changyu Shao,Liang Chen 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.3
A new-type of orthotropic steel-concrete composite bridge deck system was developed, by casting the concrete overlay on the top of the orthotropic steel deck ribbed with T-shape steel members. To study its mechanical behavior (in terms of failure mode, load-deflection relationship, concrete crack initiation and propagation, strength, stiffness and so on), two new-type orthotropic steel-concrete composite bridge decks with different section dimensions were experimentally investigated and two reference decks (reinforced concrete deck and orthotropic steel deck) were also involved in the research for comparison. For the two new-type orthotropic steel-concrete composite decks, the average value of ultimate loads per width is 885.7kN, which is 2.35 and 1.61 times of that of the concrete and steel reference decks with almost the same section height. Experimental results proved that the composite deck can effectively control the crack initiation and propagation in the concrete and postpone the yielding of the steel bars and steel plates, due to the composite action between the concrete overlay and the underlying steel plate. Furthermore, the Finite Element (FE) model of the orthotropic steel-concrete composite deck was developed and validated by test results. A parametric study is conducted regarding to the stiffness of shear studs. With the validated FE model, stress distribution in the underlying steel plate and T-shape stiffeners and development of concrete cracking in the concrete overlay were characterized at different load levels.
Xu, Shi-Zhou,Wang, Chun-Jie,Han, Tian-Cheng,Li, Xue-Ping,Zhu, Xiang-Yu The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3
Power loss reduction and total harmonic distortion(THD) minimization are two important goals of improving three-level inverters. In this paper, an optimized pulse width modulation (PWM) strategy that can reduce switching losses and balance the neutral point with an optional THD of three-level neutral-point-clamped inverters is proposed. An analysis of the two-level discontinuous PWM (DPWM) strategy indicates that the optimal goal of the proposed PWM strategy is to reduce switching losses to a minimum without increasing the THD compared to that of traditional SVPWMs. Thus, the analysis of the two-level DPWM strategy is introduced. Through the rational allocation of the zero vector, only two-phase switching devices are active in each sector, and their switching losses can be reduced by one-third compared with those of traditional PWM strategies. A detailed analysis of the impact of small vectors, which correspond to different zero vectors, on the neutral-point potential is conducted, and a hysteresis control method is proposed to balance the neutral point. This method is simple, does not judge the direction of midpoint currents, and can adjust the switching times of devices and the fluctuation of the neutral-point potential by changing the hysteresis loop width. Simulation and experimental results prove the effectiveness and feasibility of the proposed strategy.
Han, Yu Long,Wang, Wenqi,Hu, Jie,Huang, Guoyou,Wang, Shuqi,Lee, Won Gu,Lu, Tian Jian,Xu, Feng Royal Society of Chemistry 2013 Lab on a chip Vol.13 No.24
<P>We presented a benchtop technique that can fabricate reconfigurable, three-dimensional (3D) microfluidic devices made from a soft paper-polymer composite. This fabrication approach can produce microchannels at a minimal width of 100 μm and can be used to prototype 3D microfluidic devices by simple bending and stretching. The entire fabrication process can be finished in 2 hours on a laboratory bench without the need for special equipment involved in lithography. Various functional microfluidic devices (e.g., droplet generator and reconfigurable electronic circuit) were prepared using this paper-polymer hybrid microfluidic system. The developed method can be applied in a wide range of standard applications and emerging technologies such as liquid-phase electronics.</P>
Preparation of Co<sub>3</sub>O<sub>4</sub>/NF Anode for Lithium-ion Batteries
Tian, Shiyi,Li, Botao,Zhang, Bochao,Wang, Yang,Yang, Xu,Ye, Han,Xia, Zhijie,Zheng, Guoxu The Korean Electrochemical Society 2020 Journal of electrochemical science and technology Vol.11 No.4
Due to its characteristics of light weight, high energy density, good safety, long service life, no memory effect, and environmental friendliness, lithium-ion batteries (LIBs) are widely used in various portable electronic products. The capacity and performance of LIBs largely depend on the performance of electrode materials. Therefore, the development of better positive and negative materials is the focus of current research. The application of metal organic framework materials (MOFs) derivatives in energy storage has attracted much attention and research. Using MOFs as precursors, porous metal oxides and porous carbon materials with controllable structure can be obtained. In this paper, rod-shaped Co-MOF-74 was grown on Ni Foam (NF) by hydrothermal method, and then Co-MOF-74/NF precursor was heat-treated to obtain rodshaped Co<sub>3</sub>O<sub>4</sub>/NF. Ni Foam was skeleton structured, which effectively relieved. The change of internal stress changes and destroys the structural volume of the electrode material and reduces the capacity attenuation. Co<sub>3</sub>O<sub>4</sub>/NF composite material has a specific discharge capacity of up to 1858 mA h/g for the first time, and a reversible capacity of up to 902.4 mA h/g at a current density of 200 mA/g, and has excellent rate and impedance performance. The synthesis strategy reported in this article opens the way to design high-performance electrodes for energy storage and electrochemical catalysis.
( Jing Han ),( Yong Sheng Tian ),( Jing Xu ),( Li Juan Wang ),( Bo Wang ),( Ri He Peng ),( Quan Hong Yao ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.9
Glyphosate is the active component of the top-selling herbicide, the phytotoxicity of which is due to its inhibition of the shikimic acid pathway. 5-Enolpyruvylshikimate-3-phosphate synthase (EPSPS) is a key enzyme in the shikimic acid pathway. Glyphosate tolerance in plants can be achieved by the expression of a glyphosate-insensitive aroA gene (EPSPS). In this study, we used a PCR-based two-step DNA synthesis method to synthesize a new aroA gene (aroAR. leguminosarum) from Rhizobium leguminosarum. In vitro glyphosate sensitivity assays showed that aroAR. leguminosarum is glyphosate tolerant. The new gene was then expressed in E. coli and key kinetic values of the purified enzyme were determined. Furthermore, we transformed the aroA gene into Arabidopsis thaliana by the floral dip method. Transgenic Arabidopsis with the aroAR. leguminosarum gene was obtained to prove its potential use in developing glyphosate-resistant crops.
Preparation and deposition mechanism of pyrolytic carbon by CVI using 3D Ni/wood-carbon catalyst
Lulu Han,Xiaohong Shi,Xu Han,Li Yang,Kun Li,Tian Xinfa,Mu Jierui,Wang Guoqing 한국탄소학회 2022 Carbon Letters Vol.32 No.1
To improve the pyrolytic carbon (PyC) deposition rate of Carbon/Carbon (C/C) composites prepared by the traditional chemical vapor infiltration (CVI) method, the 3D Ni/wood-carbon (3D Ni/C) catalyst was introduced into the CVI process. The effects of catalyst on the density of C/C composites were studied, and the deposition rate and morphologies of PyC were investigated after catalytic CVI. The morphologies of catalyst and PyC were characterized by scanning electron microscope and polarized light microscopy. The catalytic deposition mechanism of PyC was studied by density functional theory. The experimental results show that the initial carbon deposition efficiency of the catalytic pyrolysis process was 3–4 times that of the noncatalytic process. The catalyst reduced the energy barrier in the first step of deposition reaction from 382.55 to 171.67 kJ/mol according to simulation results. The pyrolysis reaction energy with Ni catalyst is reduced by 54% than that without the catalyst.