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Nematicidal coumarin from Ficus carica L.
Fangfang Liu,Zhongshan Yang,Xi Zheng,Shaoliu Luo,Ke Qin Zhang,Guo Hong Li 한국응용곤충학회 2011 Journal of Asia-Pacific Entomology Vol.14 No.1
The methanol extracts from 40 plant species were screened for their nematicidal activity against the nematodes Bursaphelenchus xylophilus, Panagrellus redivivus and Caenorhabditis elegans. The leaf extract of Ficus carica L. exhibited the strongest nematicidal activity, causing 74.3%, 96.2% and 98.4% mortality,respectively, within 72 h. By bioassay-guided fractionation, a coumarin was obtained. The compound was determined to be psoralen based on spectroscopic data. It showed nematicidal activity against the tested nematodes. This is the first report of the nematicidal activity of F. carica and psoralen.
Hongyan Lin,Fangfang Sui,Peng Liu,Xiu-Li Wang,Guo-Cheng Liu 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.7
Two new 3D coordination complexes [Cd(3-bpcd)(pht)] (1) and [Zn(3-bpcd)(pht)] (2) [3-bpcd = N,N'-bis(pyridin- 3-yl)cyclohexane-1,4-dicarboxamide, H2pht = phthalic acid] have been hydrothermally synthesized. X-ray diffraction analysis reveals that the complexes 1 and 2 represent a 4-connected diamondoid topology with a 3- fold interpenetrating feature. Moreover, the fluorescent properties of complexes 1 and 2 are studied.
Content-driven Joint Allocation of Communication and Computing Resources in Vehicular Networks
Xu Zhu,Fangfang Liu,Zhimin Zeng,Caili Guo,Jiujiu Chen 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.2
With the rapid growth of computer vision applications, a large amount of video data in the Internet of Vehicles scenario are used for content analysis. Tasks based on video content understanding are usually accompanied by huge amount of calculation, which put great pressure on traditional wireless communication resource and Mobile Edge Computing (MEC) server computing resource. Furthermore, existing resource allocation schemes based on Quality of Service (QoS) or Quality of Experience (QoE) may not be the best choice for the purpose of video content understanding. In this paper, we propose a joint resource allocation scheme based on Quality of Content (QoC) to maximize the accuracy of video content understanding. Due to the real-time nature of resource allocation and the variability of the environment in autonomous driving scenarios, we design a Multi-agent Distributed Q-Learning algorithm to solve such multi-constrained nonlinear programming problems. Finally, the simulation results show that our proposed QoC-based joint resource allocation scheme has better video content understanding performance.
Phase Noise Self-Cancellation Scheme Based on Orthogonal Polarization for OFDM System
( Yao Nie ),( Chunyan Feng ),( Fangfang Liu ),( Caili Guo ),( Wen Zhao ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.9
In orthogonal frequency-division multiplexing (OFDM) systems, phase noise introduced by the local oscillators can cause bit error rate (BER) performance degradation. To solve the phase noise problem, a novel orthogonal-polarization-based phase noise self-cancellation (OP-PNSC) scheme is proposed. First, the efficiency of canceling the phase noise of the OP-PNSC scheme in the AWGN channel is investigated. Then, the OP-PNSC scheme in the polarization-dependent loss (PDL) channel is investigated due to power imbalance caused by PDL, and a PDL pre-compensated OP-PNSC (PPC -OP-PNSC) scheme is proposed to mitigate the power imbalance caused by PDL. In addition, the performance of the PPC-OP-PNSC scheme is investigated, where the signal-to-interference-plus-noise ratio (SINR) and spectral efficiency (SE) performances are analyzed. Finally, a comparison between the OP-PNSC and polarization diversity scheme is discussed. The numerical results show that the BER and SINR performances of the OP-PNSC scheme outperform the case with the phase noise compensation and phase noise self-cancellation scheme.
Fengxia Lv,Chong Zhang,Fangfang Guo,Yingjian Lu,Xiaomei Bie,Hui Qian,Zhaoxin Lu 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.1
The gene encoding the fibrinolytic enzyme (PPFE-I) from Paenibacillus polymyxa EJS-3 was cloned and sequenced (Genbank No. KC176802). The 1773 bp gene encoded 590 amino acids and had low homology with other known fibrinolytic enzymes. PPFE-I was soluble and expressed in E. coli BL21 to enhance the activity. The recombinant enzyme (rPPFE-I) was purified to homogeneity, and enzymatic properties were characterized. The optimal temperature and pH for rPPFE-I were 37℃ and 7.5, respectively. Observed activities of rPPFE-I were highest in the presence of Zn2+, Mg2+, and Fe2+ and the lowest in the presence of Ca2+ and Cu2+. The rPPFE-I activity was strongly inhibited by PMSF. The α-chain was affected by the rPPFE-I cleavage speed of fibrinogen, followed by the b and γ chains. The inhibitory effects of rPPFE-I against ADP-induced human platelet aggregation were dosedependent with an IC50 value of 1.54 μM.
Bit-Level Image Encryption Algorithm Based on Composite Chaotic Mapping
Cai Yang,Haiyu Zhang,Jinliang Guo,Songhao Jia,Fangfang Li 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.8
Because the single chaotic mapping easily creates security weaknesses in the image encryption algorithm, the security needs to be improved. Aiming at this problem, a bit-level image encryption algorithm based on composite chaotic mapping (CCM-IEA) is proposed. First of all, the algorithm scrambles the plain image on bit level through the Cat mapping for the first time. And then the Henon mapping of two dimensional discrete is used to scramble for the second time. Finally, image diffusion is operated through the one dimensional Logistic mapping, and the data sensitivity is enhanced. The experimental results show that the performance of the CCM-IEA algorithm is better on the histogram, information entropy and correlation analysis. Compared with the single chaotic images encryption algorithm, the CCM-IEA algorithm has the ability to resist the information entropy analysis and correlation analysis. It can be seen that the CCM-IEA algorithm has high safety performance and good encryption effect.
A Trust Management Model for Mobile P2P Networks based on Multiple-Fuzzy Theory
Meijuan JIA,Huiqiang WANG,Guangsheng FENG,Fangfang GUO 보안공학연구지원센터 2014 International Journal of Multimedia and Ubiquitous Vol.9 No.12
The characteristics of dynamic, heterogeneity and limited resources of peers result in the existence of selfish behavior in MP2P network, which affect the network performance. To improve the performance of MP2P, a trust management model for peer reputation is established based on multiple-fuzzy theory in this paper. Direct trust, indirect trust, residual energy and active degree of peers are used as the fundamental variables and their weights are determined by using fuzzy theory, and then the reputation of peers is calculated. Peers with high reputation are allowed to participate in the communication and peers with low reputation are not allowed. The experimental simulation results show that the model not only effectively improve the malicious peer detection rate and the query hit rate but also reduce the Cx of the network.