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Production and Characterization of Extracellular Chitin Deacetylase from Absidia corymbifera DY-9
( Yong Zhao ),( Young Ju Kim ),( Kyung Taek Oh ),( Van Nam Nguyen ),( Ro Dong Park ) 한국응용생명화학회 2010 Applied Biological Chemistry (Appl Biol Chem) Vol.53 No.2
Recent attention has been paid to the screening of chitin deacetylase (CDA) from fungi, which may be applied into industrial production of chitosan and chitosan oligomers. We screened an extracellular CDA from a fungus that was further identified to be Absidia corymbifera DY-9. CDA from A. corymbifera DY-9 exhibited a higher enzyme activity than that of Mucor rouxii CDA. The highest yield of CDA was achieved in a liquid medium containing 2% powder chitin at pH 9.0, 28˚C and 150 rpm. Moreover, the biochemical properties of this enzyme were studied. It was found that the optimal pH and temperature were 6.5 and 55˚C. The enzyme activity could be enhanced in the presence of 1-10 mM Co2+, Ca2+ and Mg2+ while inhibited by acetate and EDTA. The enzyme was active on WSCT-50, glycol chitin, chitosan (DDA 71-88 %) and chitin oligosaccharides with a DP no less than 2.
Improved Multi-target Tracking Algorithm Based on Gaussian Mixture Particle PHD Filter
Qing Lin,Pei Cao,Dingan Liao,Yongzhao Zhan,Yaping Yang 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.2
The paper proposes Gaussian mixture particle probability hypothesis density filter(PHD) algorithm ,which can effectively solve the problem that the object number is changing or unknown, based on particle PHD filter. This algorithm calculates the object number and state by recursive procedure, avoiding the uncertainty of target state estimation caused by particle sampling and clustering. Gaussian mixture particle is introduced to effectively maintain the multi-modal distribution of each target,reducing the complexity of calculation.
Lowering Error Floor of LDPC Codes Using an Improved Parallel WBF Algorithm
Kexiang Ma,Yongzhao Li,Caizhi Zhu,Hailin Zhang,Yuming Zhang 한국전자통신연구원 2014 ETRI Journal Vol.36 No.1
In weighted bit-flipping-based algorithms for low-densityparity-check (LDPC) codes, due to the existence ofoverconfident incorrectly received bits, the metric values of thecorresponding bits will always be wrong in the decodingprocess. Since these bits cannot be flipped, decoding failureresults. To solve this problem, an improved parallel weightedbit flipping algorithm is proposed. Specifically, a reliabilitysaturationstrategy is adopted to increase the flippingprobability of the overconfident incorrectly received bits. Simulation results show that the error floor of LDPC codes isgreatly lowered.
Improved Genetic Algorithm based 3-D deployment of UAVs
Xiting Wen,Yuhan Ruan,Yongzhao Li,Hongxing Xia,Rui Zhang,Chao Wang,Wei Liu,Xiaoyu Jiang 한국통신학회 2022 Journal of communications and networks Vol.24 No.2
Unmanned aerial vehicles (UAVs) are widely usedas aerial base stations (BSs) to provide flexible connectivity andcoverage for ground users in various scenarios such as disasterrelief, traffic offloading, and so on. Especially, UAV deployment isan important issue that directly affects the coverage performanceof the UAV network. In this paper, we propose a novel heuristic algorithmbased three-dimensional (3-D) UAV deployment schemewhile guaranteeing the connectivity of the UAV network in bothstatic and dynamic user scenarios. For the static user scenario, weaim to deploy the minimum number of UAVs to provide coveragefor the users from the perspective of deployment cost. To reducethe deployment complexity, we decouple the 3-D UAV deploymentproblem from the vertical and horizontal dimensions. Specifically,we firstly determine the optimal vertical height of UAVs based onthe air-to-ground (A2G) model. Then, to alleviate the prematureconvergence of standard genetic algorithm (SGA), we designan improved genetic algorithm (IGA) to obtain the optimalhorizontal locations of UAVs. On this basis, when the users moveor increase, i.e., the dynamic user scenario, the already deployedUAVs cannot provide effective coverage. For this scenario, wepropose a UAV redeployment scheme to maximize the numberof covered users without increasing the number of UAVs. Tofurther reduce the cost of redeployment, we firstly modify theproposed IGA to obtain a feasible set of two-dimensional (2-D)redeployed locations of the UAVs. Then, we design a backtrackingalgorithm (BA) based UAV movement strategy to minimize thetotal flying distance of the UAVs. The simulation results showthat the effectiveness and convergence of our proposed schemes.
On the Performance of Cyclic-Prefixed Single-Carrier Cellular Systems in Cochannel Interference
Kyeong Jin Kim,Yongzhao Li,Tsiftsis, T. A. IEEE 2011 IEEE Transactions on Vehicular Technology VT Vol.60 No.8
<P>In this paper, we study cyclic-prefixed single-carrier cellular systems in the presence of cochannel interference from neighboring cells. Performance analysis for the maximum achievable average rate and outage probability based on approximated distributions for the signal-to-interference-plus-noise ratio (SINR) is presented. An asymptotic diversity gain is also derived. Monte Carlo simulations verify the derived analytical expressions.</P>
The Nrf2 antioxidant defense system in intervertebral disc degeneration: Molecular insights
Xiang Qian,Zhao Yongzhao,Lin Jialiang,Jiang Shuai,Li Weishi 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-
Intervertebral disc degeneration (IDD) is a common degenerative musculoskeletal disorder and is recognized as a major contributor to discogenic lower back pain. However, the molecular mechanisms underlying IDD remain unclear, and therapeutic strategies for IDD are currently limited. Oxidative stress plays pivotal roles in the pathogenesis and progression of many age-related diseases in humans, including IDD. Nuclear factor E2-related factor 2 (Nrf2) is a master antioxidant transcription factor that protects cells against oxidative stress damage. Nrf2 is negatively modulated by Kelch-like ECH-associated protein 1 (Keap1) and exerts important effects on IDD progression. Accumulating evidence has revealed that Nrf2 can facilitate the transcription of downstream antioxidant genes in disc cells by binding to antioxidant response elements (AREs) in promoter regions, including heme oxygenase-1 (HO-1), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and NADPH quinone dehydrogenase 1 (NQO1). The Nrf2 antioxidant defense system regulates cell apoptosis, senescence, extracellular matrix (ECM) metabolism, the inflammatory response of the nucleus pulposus (NP), and calcification of the cartilaginous endplates (EP) in IDD. In this review, we aim to discuss the current knowledge on the roles of Nrf2 in IDD systematically.
Matrix-Diffusion-Controlled Coarsening of the γ′ Phase in Waspaloy
Haiping Wang,Dong Liu,Yongzhao Shi,Jianguo Wang,Yanhui Yang,Longxiang Wang,Weidong Qin 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.6
This paper discussed the coarsening behavior of the γ′ phase in Waspaloy during heat treatment at different aging timesunder the temperatures of 960 °C and 1000 °C. The morphology of γ′ phase is obtained by scanning electron microscopyand it is measured by the software Image Pro Plus 6.0 in a variety of aging conditions. The volume fraction of the γ′ phase isdecreasing with the increase of the temperature. The radius of the γ′ phase is subject to involve the coarsening process duringaging treatment, and the coarsening rate decreases with the extension of the aging time at certain temperature. Besides,the coarsening kinetics of γ′ phase in Waspaloy is adequately characterized by the Lifshitz–Slyozov–Wagner (LSW) theorymodel as the particle size distribution and coarsening behavior show excellent agreement with the LSW model. Accordingto the experimental results and LSW model, the coarsening rate coefficients were determined to be 27.23 nm3/s and58.67 nm3/s under the aging temperature of 960 °C and 1000 °C respectively. Meanwhile, on the basis of the experimentalstatistics analysis and the LSW model, the mathematical model of the coarsening behavior of the γ′ phase in Waspaloy wasdeveloped. Mathematical model developed in this paper can be used to evaluate the coarsening process of the γ′ phase duringthermal exposure. The interfacial energy between the γ′ phase and the γ matrix was determined to be 56.04 mJ/m2 and44.27 mJ/m2 at the temperature of 960 °C and 1000 °C respectively.