Molecular Characterization of Cold-Inducible β-Galactosidase from Arthrobacter sp. ON14 Isolated from Antarctica

( Xiang Xiao ),( Feng Ping Wang ),( Xu Ke ),( Xi Xiang Tang ),( Ying Bao Gai ),( Muhammad Aamer Mehmood ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.3

A psychrotrophic bacterium, Arthrobacter sp. ON14, isolated from Antarctica, was shown to exhibit a high β-galactosidase activity at a low temperature. A genomic library of ON14 was constructed and screened for β-galactosidase genes on functional plates containing 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-gal) as the substrate. Two different β-galactosidase genes, named as galA, galB, were found in ON14. Computational analyses of the genes revealed that the encoded protein GalA belongs to family 2 of glycosyl hydrolysases and is a cold-active protein, whereas GalB belongs to family 42 of glycosyl hydrolysases and is a mesophilic protein. Reverse transcription analyses revealed that the expression of galA is highly induced at a low temperature (4℃) and repressed at a high temperature (28℃) when lactose is used as the sole carbon source. Conversely, the expression of galB is inhibited at a low temperature and induced at a high temperature. The purified GalA showed its peak activity at 15℃ and pH 8. The mineral ions Na+, K+, Mg2+, and Mn2+ were identified as enzyme activators, whereas Ca2+ had no influence on the enzyme activity. An enzyme stability assay revealed that the activity of GalA is significantly decreased when it is incubated at 45℃ for 2 h, and all its activity is lost when it is incubated at 50℃.

HPLC Determination of Malondialdehyde in ECV304 Cell Culture Medium for Measuring the Antioxidant Effect of Vitexin-4"-O-glucoside

Xi-xiang Ying,Hai-bo Li,Zheng-yun Chu,Yan-jun Zhai,Ai-jing Leng,Xun Liu,Wen-jie Zhang,Ting-guo Kang,Chun Xin 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.7

To investigate the antioxidant effect of vitexin-4"-O-glucoside, a flavone glycoside, isolated from the leaves of Crataegus pinnatifida Bge. var. major, we developed a simple and sensitive high-performance liquid chromatography (HPLC) method to determine levels of malondialdehyde (MDA) in ECV304 cell culture medium after induction by tert-butyl-hydroperoxide (TBHP). The preparation of analyzed samples involved a one-step derivatization with thiobarbituric acid (TBA). HPLC analysis was performed on a SynergiTM Hydro-RP, a polar end-capped C18 column (250×4.6 mm, 4 μm), using an acetonitrile-ammonium acetate aqueous solution (10 mM, pH 6.8) as the mobile phase under linear gradient conditions with UV detection at 532 nm. The calibration curve was linear over 0.0125-1.25 μM MDA (r = 0.9951). Relative standard deviations (RSDs) of intra-day and inter-day precision were less than 6.1% and 5.0%, respectively. The mean recovery was 96.9 ± 1.6%. The lower limit of quantification (LLOQ) of MDA was 0.0125 μM. This chromatographic method was successfully applied to investigating the in vitro antioxidant effect of vitexin-4"-O-glucoside. Vitexin-4"-O-glucoside (120 M) protected ECV304 cells from peroxidation induced by TBHP.

HPLC Determination of Malondialdehyde in ECV304 Cell Culture Medium for Measuring the Antioxidant Effect of Vitexin-4"-O-glucoside

Ying, Xi-Xiang,Li, Hai-Bo,Chu, Zheng-Yun,Zhai, Yan-Jun,Leng, Ai-Jing,Liu, Xun,Xin, Chun,Zhang, Wen-Jie,Kang, Ting-Guo 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.7

To investigate the antioxidant effect of vitexin-4"-O-glucoside, a flavone glycoside, isolated from the leaves of Crataegus pinnatifida Bge. var. major, we developed a simple and sensitive high-performance liquid chromatography (HPLC) method to determine levels of malondialdehyde (MDA) in ECV304 cell culture medium after induction by tert-butyl-hydroperoxide (TBHP). The preparation of analyzed samples involved a one-step derivatization with thiobarbituric acid (TBA). HPLC analysis was performed on a $Synergi^{TM}$ Hydro-RP, a polar end-capped $C_{18}$ column ($250{\times}4.6\;mm$, $4\;{\mu}m$), using an acetonitrile-ammonium acetate aqueous solution (10 mM, pH 6.8) as the mobile phase under linear gradient conditions with UV detection at 532 nm. The calibration curve was linear over $0.0125-1.25\;{\mu}M$ MDA (r=0.9951). Relative standard deviations (RSDs) of intra-day and inter-day precision were less than 6.1% and 5.0%, respectively. The mean recovery was $96.9\;{\pm}\;1.6%$. The lower limit of quantification (LLOQ) of MDA was $0.0125\;{\mu}M$. This chromatographic method was successfully applied to investigating the in vitro antioxidant effect of vitexin-4"-O-glucoside. Vitexin-4"-O-glucoside (120 M) protected ECV304 cells from peroxidation induced by TBHP.

Long-term monitoring of super-long stay cables on a cable-stayed bridge

Xiang Shen,Ru-jin Ma,Chun-xi Ge,Xiao-hong Hu 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.27 No.6

For a long cable-stayed bridge, stay cables are its most important load-carrying components. In this paper, long-term monitoring of super-long stay cables of Sutong Bridge is introduced. A comprehensive data analysis procedure is presented, in which time domain and frequency domain based analyses are carried out. In time domain, the vibration data of several long stay cables are firstly analyzed and the standard deviation of the acceleration of stay cables, and its variation with time are obtained, as well as the relationship between in-plane vibration and out-plane vibration. Meanwhile, some vibrations such as wind and rain induced vibration are detected. Through frequency domain analysis, the basic frequencies of the stay cables are identified. Furthermore, the axial forces and their statistical parameters are acquired. To investigate the vibration deflection, an FFT-based decomposition method is used to get the modal deflection. In the end, the relationship between the vibration amplitude of stay cables and the wind speed is investigated based on correlation analysis. Through the adopted procedure, some structural parameters of the stay cables have been derived, which can be used for evaluating the component performance and corresponding management of stay cables.

Mesenchymal Stem Cells on a Decellularized Cartilage Matrix for Cartilage Tissue Engineering

Xi-Fu Zheng,Shi-Bi Lu,Wei-Guo Zhang,Shu-Yun Liu,Jing-Xiang Huang,Quan-Yi Guo 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.3

An ideal scaffold for cartilage tissue engineering should be biomimetic in not only its biochemical composition, but also in the morphological structure of the scaffold. In this study, we fabricated a scaffold with an oriented structure using a nanofibrous articular cartilage extracellular matrix (ACECM), in which the ACECM was used to mimic the biochemical composition and oriented structure of articular cartilage. Histology analysis showed that the scaffold contained cartilage ECM (GAGs and collagen II). Scanning electron microscopy (SEM) indicated that the scaffolds were composed of nanofibers and possessed vertical microtubules. Chondrogenic differentiation-induced mesenchymal stem cells (MSCs) were seeded on the scaffold in vitro. SEM showed that MSCs proliferated well and aligned along the vertical microtubules,which mimicked the orientation of deep zone articular cartilage. A cell proliferation assay and live/dead cell staining demonstrated that the ACECM possessed good cell affinity, which favored cell adherence and proliferation. The MSCs that had been labeled with the fluorescent dye PKH26 and seeded on scaffolds were implanted into nude mice. The differentiated cells/ACECM implants formed cartilage-like tissue 4 weeks after implantation, and stained positive for collagen type II and toluidine blue. In addition,the in vivo fluorescent images verified that the MSCs in the implants were the labeled MSCs. These results demonstrated that the oriented ACECM scaffolds hold great promise for use in cartilage tissue engineering applications.

Potential of Femtosecond Electron Diffraction Using Near-Relativistic Electrons from a Photocathode RF Electron Gun

Xi Jie Wang,이효철,Dao Xiang,Tae Kyu Kim 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.3

The electron beam from a photocathode RF electron gun is usually used to drive a free electron laser (FEL) after acceleration and to generate coherent radiation from IR to X-rays. Building on our earlier proposal that such an electron beam itself can be used as scattering particles to produce a time-dependent diffraction signal, which contains structural information on a femtosecond resolution, here we further elucidate several important practical factors relevant to realizing electron diffraction on this time scale. A higher electrical field on the cathode of the RF gun can provide a larger number of electrons per bunch with a shorter temporal width compared to a typical DC gun, owing to a significant reduction in the space-charge effect. The near-relativistic speed of the electrons will further reduce the velocity mismatch and significantly improve the overall time resolution. However, the de Broglie wavelength of near-relativistic electrons at 2 MeV is one order of magnitude shorter than that of the electrons generated by a typical DC gun operated at 30 keV. Consequently the Bragg angle is one order smaller and is comparable to the beam’s intrinsic divergence, significantly blurring the observed diffraction pattern. Our simulations show that it is possible to restore the ideal diffraction pattern from the observed, blurred diffraction pattern; therefore, femtosecond electron diffraction using a photocathode RF gun can be a useful and practical tool. In addition, the sensitive dependence of the diffraction pattern on the electron beam divergence can be utilized to measure the divergence with high accuracy.

Cytotoxic Isoflavanones from Uraria clarkei

Xiang-Zhong Huang,Xi-Shan Bai,Hui Liang,Chao Wang,Wen-Juan Li,Junming Guo,Zhi-Yong Jiang 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.5

Two new isoflavanones, (3R) 5,7,3',4'-tetrahydroxy-2'-methoxyisoflavanone (1) and (3R) 5',8-di-(γ,γ- dimethylallyl)-2',5-dihydroxyl-4',7-dimethoxyl-isoflavanone (2), were isolated from Uraria clarkei, together with two known compounds dalbergioidin (3), 5,7-dihydroxy-2',4'-dimethoxyisoflavanone (4). The structures involving the absolute configuration of the new compounds were well elucidated by MS, IR, UV, CD, 1D and 2D NMR analyses. Cytotoxicity of the four compounds were assessed, results suggested that compound 2 possessed well cytotoxic activity, against the Hela, K562, and HL60 cell lines with IC50 values of 28.0, 40.6 and 35.1 μM, respectively.

The New Ecosystem of Cross-border E-Commerce among Korea, China and Japan Based on Blockchain

Xiang-Dong Shen,Xi Chen,Ran Ji,Ren-Hong Wu 한국무역학회 2020 Journal of Korea trade Vol.24 No.5

Purpose - The purpose of the study is to propose a theoretical framework of cross-border e-commerce ecosystems based on blockchain technology. The ecosystem includes five systems, namely, crossborder supply chain intelligent system, cross-border logistics system, cross-border payment system, cross-border product quality traceability system and cross-border customs supervision system. Design/methodology - This study firstly derived the main improvement factors for the new ecosystem based on blockchain through prior research and expert interviews on cross-border e-commerce. Then explored the use of virtue of decentralization, anti-counterfeiting traceability, consensus mechanism, smart contract and other means of the core technology of blockchain to overcome the bottleneck of cross-border e-commerce development among Korea, China, and Japan. Finally, proposed valuable implications in both theoretical and practical perspectives. Findings - As a result, we combined with the problems existing in cross-border e-commerce among Korea, China and Japan, this paper proposes a solution based on blockchain. On this basis, it constructs a cross-border e-commerce ecosystem among these three countries, including five systems. In addition, we discuss the main problems existing in the current blockchain, such as low transaction concurrency, security loopholes, and inconsistent standards, the corresponding countermeasures are proposed from the technical level, security level and industry standards. Originality/value - This study is the first to apply the blockchain technology to solve the cross-border e-commerce problems in Korea, China and Japan, which is of pioneering significance in both literature and practice. Block chain technology is in the ascendency. This study provides technical solutions for promoting the development of cross-border e-commerce import and export trade between Korea, China and Japan.

IoT Makes Life Simpler: How to Improve the Chinese Consumer’s Intention to Use of LG HomNet Smart Home

Xiang-Dong Shen,Xi Chen,Yuting Jiang,Haixin Ji 한국무역학회 2022 Journal of Korea trade Vol.26 No.8

Purpose – The paper aims to develop the theory of TAM and perceived risk through a more comprehensive and rigorous understanding of the influencing factors of the consumer’s adoption of LG HomNet smart home from the perspective of trade-offs. Design/methodology – Based on the TAM and perceived risk theory, combined with the individual characteristics of consumers in the context of information technology as the external factors of the technology acceptance model, this paper constructs a theoretical model of the factors affecting the use intention of the consumer. It was empirically tested by using SEM, and survey data was collected from 458 respondents. Findings – The research results show that 9 hypotheses of the research model are supported and have reliable prediction accuracy. Consumers’ perceived interest, perceived connectivity and perceived controllability have a significant positive impact on their intention to use. In addition, this paper also confirmed the mediating effect of perceived usefulness and perceived ease of use. Originality/value – Consumers are very concerned about gains and losses. Low-level performance risks, security risks, and financial risks will drive the consumer to have a stronger intention to use, and financial risks have the strongest impact. This research provides a useful implication and guidance for smart home equipment manufacturers and service providers in product and service innovation and marketing and promotion strategies.

Radar Emitter Signals Identification with a Optimal Recurrent Type 2 Wavelet Fuzzy Neural Network

Xiang-jian Chen,Di Li,Xi-Bei Yang,Hongmei Li 한국항공우주학회 2018 International Journal of Aeronautical and Space Sc Vol.19 No.3

One optimal recurrent type 2-wavelet fuzzy neural network (RT2WFNN) is proposed in this paper to deal with the problem of emitter identification caused by some types of noise. The RT2WFNN has both an on-line parameter and structure learning ability. The new adaptive method based on gradient decent with Lyapunov theorem used for parameter learning can improve the learning ability of RT2WFNN; the type 2 FCM and optimal improved EKM algorithm are used to select the cluster centers of the membership functions in the antecedent part of fuzzy rules of the RT2WFNN for shortening the adjustment time. A number of simulations are presented to demonstrate the identification capability of the RT2WFNN algorithm for the radar emitter identification. The simulation and actual experimental results illustrated that the proposed RT2WFNN cannot only have better identification capability, but also is relatively more insensitive to noise and accelerate the computing speed.