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EXISTENCE AND UNIQUENESS OF PERIODIC SOLUTIONS FOR A KIND OF RAYLEIGH EQUATION WITH A DEVIATING ARGUMENT

  • Zhou, Qiyuan;Xiao, Bing;Yu, Yuehua;Liu, Bingwen;Huang, Lihong
    • Journal of the Korean Mathematical Society
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    • v.44 no.3
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    • pp.673-682
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    • 2007
  • In this paper, we use the coincidence degree theory to establish new results on the existence and uniqueness of T-periodic solutions for a kind of Rayleigh equation with a deviating argument of the form $x'+f(x'(t))+g(t,\;x(t-\tau(t)))=p(t)$.

Reduce on the Cost of Photovoltaic Power Generation for Polycrystalline Silicon Solar Cells by Double Printing of Ag/Cu Front Contact Layer

  • Peng, Zhuoyin;Liu, Zhou;Chen, Jianlin;Liao, Lida;Chen, Jian;Li, Cong;Li, Wei
    • Electronic Materials Letters
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    • v.14 no.6
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    • pp.718-724
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    • 2018
  • With the development of photovoltaic industry, the cost of photovoltaic power generation has become the significant issue. And the metallization process has decided the cost of original materials and photovoltaic efficiency of the solar cells. Nowadays, double printing process has been introduced instead of one-step printing process for front contact of polycrystalline silicon solar cells, which can effectively improve the photovoltaic conversion efficiency of silicon solar cells. Here, the relative cheap Cu paste has replaced the expensive Ag paste to form Ag/Cu composite front contact of silicon solar cells. The photovoltaic performance and the cost of photovoltaic power generation have been investigated. With the optimization on structure and height of Cu finger layer for Ag/Cu composite double-printed front contact, the silicon solar cells have exhibited a photovoltaic conversion efficiency of 18.41%, which has reduced 3.42 cent per Watt for the cost of photovoltaic power generation.

Direct Palladium-Catalyzed C-4 Arylation of Tri-substituted Furans with Aryl Chlorides: An Efficient Access to Heteroaromatics

  • Yang, Hai;Zheng, Zhishuo;Zeng, Jian;Liu, Huajie;Yi, Bing
    • Bulletin of the Korean Chemical Society
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    • v.33 no.8
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    • pp.2623-2626
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    • 2012
  • A series of functionalized furans were synthesized by way of a palladium-catalyzed coupling reaction of 2,3,5-trisubstituted furans with aryl chlorides through C-H bond cleavages at C-4 position. The feature of the reaction was facilitative preparation of furan derivatives with good functional group tolerance. All reactions gave the desired products in moderate to good yields in the presences of $BuAd_2P$ and t-BuOK in DMF at $120^{\circ}C$ after 15 h.

Monitoring and control of wind-induced vibrations of hanger ropes of a suspension bridge

  • Hua, Xu G.;Chen, Zheng Q.;Lei, Xu;Wen, Qin;Niu, Hua W.
    • Smart Structures and Systems
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    • v.23 no.6
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    • pp.683-693
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    • 2019
  • In August 2012, during the passage of the typhoon Haikui (1211), large amplitude vibrations were observed on long hangers of the Xihoumen suspension Bridge, which destroyed a few viscoelastic dampers originally installed to connect a pair of hanger ropes transversely. The purpose of this study is to identify the cause of vibration and to develop countermeasures against vibration. Field measurements have been conducted in order to correlate the wind and vibration characteristics of hangers. Furthermore, a replica aeroelastic model of prototype hangers consisting of four parallel ropes was used to study the aeroelastic behavior of hanger ropes and to examine the effect of the rigid spacers on vibration mitigation. It is shown that the downstream hanger rope experiences the most violent elliptical vibration for certain wind direction, and the vibration is mainly attributed to wake interference of parallel hanger ropes. Based on wind tunnel tests and field validation, it is confirmed that four rigid spacers placed vertically at equal intervals are sufficient to suppress the wake-induced vibrations. Since the deployment of spacers on hangers, server hanger vibrations and clash of hanger ropes are never observed.

2-D meso-scale complex fracture modeling of concrete with embedded cohesive elements

  • Shen, Mingyan;Shi, Zheng;Zhao, Chao;Zhong, Xingu;Liu, Bo;Shu, Xiaojuan
    • Computers and Concrete
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    • v.24 no.3
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    • pp.207-222
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    • 2019
  • This paper has presented an effective and accurate meso-scale finite element model for simulating the fracture process of concrete under compression-shear loading. In the proposed model, concrete is parted into four important phases: aggregates, cement matrix, interfacial transition zone (ITZ), and the initial defects. Aggregate particles were modelled as randomly distributed polygons with a varying size according to the sieve curve developed by Fuller and Thompson. With regard to initial defects, only voids are considered. Cohesive elements with zero thickness are inserted into the initial mesh of cement matrix and along the interface between aggregate and cement matrix to simulate the cracking process of concrete. The constitutive model provided by ABAQUS is modified based on Wang's experiment and used to describe the failure behaviour of cohesive elements. User defined programs for aggregate delivery, cohesive element insertion and modified facture constitutive model are developed based on Python language, and embedded into the commercial FEM package ABAQUS. The effectiveness and accuracy of the proposed model are firstly identified by comparing the numerical results with the experimental ones, and then it is used to investigate the effect of meso-structure on the macro behavior of concrete. The shear strength of concrete under different pressures is also involved in this study, which could provide a reference for the macroscopic simulation of concrete component under shear force.

Investigation on the effect of vibration frequency on vortex-induced vibrations by section model tests

  • Hua, X.G.;Chen, Z.Q.;Chen, W.;Niu, H.W.;Huang, Z.W.
    • Wind and Structures
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    • v.20 no.2
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    • pp.349-361
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    • 2015
  • Higher-mode vertical vortex-induced vibrations (VIV) have been observed on several steel box-girder suspension bridges where different vertical modes are selectively excited in turn with wind velocity in accordance with the Strouhal law. Understanding the relationship of VIV amplitudes for different modes of vibration is very important for wind-resistant design of long-span box-girder suspension bridges. In this study, the basic rectangular cross-section with side ratio of B/D=6 is used to investigate the effect of different modes on VIV amplitudes by section model tests. The section model is flexibly mounted in wind tunnel with a variety of spring constants for simulating different modes of vibration and the non-dimensional vertical amplitudes are determined as a function of reduced velocity U/fD. Two 'lock-in' ranges are observed at the same onset reduced velocities of approximately 4.8 and 9.4 for all cases. The second 'lock-in' range, which is induced by the conventional vortex shedding, consistently gives larger responses than the first one and the Sc-normalized maximum non-dimensional responses are almost the same for different spring constants. The first 'lock-in' range where the vibration frequency is approximately two times the vortex shedding frequency is probably a result of super-harmonic resonance or the "frequency demultiplication". The main conclusion drawn from the section model study, central to the higher-mode VIV of suspension bridges, is that the VIV amplitude for different modes is the same provided that the Sc number for these modes is identical.

ZNF552, a novel human KRAB/C2H2 zinc finger protein, inhibits AP-1- and SRE-mediated transcriptional activity

  • Deng, Yun;Liu, Bisheng;Fan, Xiongwei;Wang, Yuequn;Tang, Ming;Mo, Xiaoyang;Li, Yongqing;Ying, Zaochu;Wan, Yongqi;Luo, Na;Zhou, Junmei;Wu, Xiushan;Yuan, Wuzhou
    • BMB Reports
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    • v.43 no.3
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    • pp.193-198
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    • 2010
  • In this study, we report the identification and characterization of a novel C2H2 zinc finger protein, ZNF552, from a human embryonic heart cDNA library. ZNF552 is composed of three exons and two introns and maps to chromosome 19q13.43. The cDNA of ZNF552 is 2.3 kb, encoding 407 amino acids with an amino-terminal KRAB domain and seven carboxyl-terminal C2H2 zinc finger motifs in the nucleus and cytoplasm. Northern blotting analysis indicated that a 2.3 kb transcript specific for ZNF552 was expressed in liver, lung, spleen, testis and kidney, especially with a higher level in the lung and testis in human adult tissues. Reporter gene assays showed that ZNF552 was a transcriptional repressor, and overexpression of ZNF552 in the COS-7 cells inhibited the transcriptional activities of AP-1 and SRE, which could be relieved through RNAi analysis. Deletion studies showed that the KRAB domain of ZNF552 may be involved in this inhibition.

KBTBD7, a novel human BTB-kelch protein, activates transcriptional activities of SRE and AP-1

  • Hu, Junjian;Yuan, Wuzhou;Tang, Ming;Wang, Yuequn;Fan, Xiongwei;Mo, Xiaoyang;Li, Yongqing;Ying, Zaochu;Wan, Yongqi;Ocorr, Karen;Bodmer, Rolf;Deng, Yun;Wu, Xiushan
    • BMB Reports
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    • v.43 no.1
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    • pp.17-22
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    • 2010
  • In this study, a novel member of BTB-kelch proteins, named KBTBD7, was cloned from a human embryonic heart cDNA library. The cDNA of KBTBD7 is 3,008 bp long and encodes a protein product of 684 amino acids (77.2 kD). This protein is highly conserved in evolution across different species. Western blot analysis indicates that a 77 kD protein specific for KBTBD7 is wildly expressed in all embryonic tissues examined. In COS-7 cells, KBTBD7 proteins are localized to the cytoplasm. KBTBD7 is a transcription activator when fused to GAL4 DNA-binding domain. Deletion analysis indicates that the BTB domain and kelch repeat motif are main regions for transcriptional activation. Overexpression of KBTBD7 in MCF-7 cells activates the transcriptional activities of activator protein-1 (AP-1) and serum response element (SRE), which can be relieved by siRNA. These results suggest that KBTBD7 proteins may act as a new transcriptional activator in mitogen-activated protein kinase (MAPK) signaling.

Human Intersectin 2 (ITSN2) binds to Eps8 protein and enhances its degradation

  • Ding, Xiaofeng;Yang, Zijian;Zhou, Fangliang;Hu, Xiang;Zhou, Chang;Luo, Chang;He, Zhicheng;Liu, Qian;Li, Hong;Yan, Feng;Wang, Fangmei;Xiang, Shuanglin;Zhang, Jian
    • BMB Reports
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    • v.45 no.3
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    • pp.183-188
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    • 2012
  • Participates in actin remodeling through Rac and receptor endocytosis via Rab5. Here, we used yeast two-hybrid system with Eps8 as bait to screen a human brain cDNA library. ITSN2 was identified as the novel binding factor of Eps8. The interaction between ITSN2 and Eps8 was demonstrated by the in vivo co-immunoprecipitation and colocalization assays and the in vitro GST pull-down assays. Furthermore, we mapped the interaction domains to the region between amino acids 260-306 of Eps8 and the coiled-coil domain of ITSN2. In addition, protein stability assays and immunofluorescence analysis showed ITSN2 overexpression induced the degradation of Eps8 proteins, which was markedly alleviated with the lysosome inhibitor NH4Cl treatment. Taken together, our results suggested ITSN2 interacts with Eps8 and stimulates the degradation of Eps8 proteins.