디젤분진이 사람 동맥 평활근 세포(VSMC)에 미치는 영향

임용,김수연,정규혁,정진호,문창규,윤여표 한국환경독성학회 2004 환경독성보건학회지 Vol.19 No.1

The purpose of the present study was to examine the effect of diesel exhaust particles on human aortic vascular smooth muscle cells(VSMCs). DNA synthesis, cell viability and morphology of VSMCs after treatment of diesel exhaust particles(DEP) and fine particulate matter(PM_(2.5)) were assayed. PM_(2.5) inhibited the DNA synthesis of VSMCs in a concentration-dependent manner, whereas DEP did not affect VSMCs up to 50㎍/mL . These results were confirmed by morphological examination of VSMCs. PM_(2.5) showed a dose-dependent cytotoxicity of VSMCs by MTT assay. Fraction 4(organic acids) and fraction8(moderately polar compounds) showed the most potent inhibition of DNA synthesis of VSMCs, and fraction7(slightly polar compounds), fraction9(higher polar compounds), and fraction6(aromatic compounds) were next order. These results were confirmed by morphological examination of VSMCs. These results suggest that PM_(2.5) inhibits the DAN synthesis of VSMCs through the cytotoxicity.

Experimental and numerical investigation on post-earthquake fire behaviour of the circular concrete-filled steel tube columns

Yu-Hang Wang,Qi Tang,Mei-Ni Su,Ji-Ke Tan,Wei-Yong Wang,Yong-Sen Lan,Xiao-Wei Deng,Yong-Tao Bai,Wei Luo,Xiao-Hua Li,Jiu-Lin Bai 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.1

Post-earthquake fire is a common disaster which causes serious safety issues to infrastructures. This study aims to investigate the residual loading capacities of circular concrete-filled steel tube (CFST) columns under post-earthquake fire experimentally and numerically. The experimental programme contains two loading steps - pre-damage cyclic loading at room temperature and transient state tests with constant compression loads. Three finite element models are developed and validated against the test results. Upon validation, a total of 48 numerical results were generated in the parametric study to investigate the effects of thickness and strengths of steel tube, axial compression ratio and damage degree on the fire resistance of circular CFST columns. Based on the analysis on experimental and numerical results, the loading mechanism of circular CFST columns is discussed. A design method is proposed for the prediction of fire resistance time under different seismic pre-damage and compression loads. The predictions by the new method is compared with the newly generated experimental and numerical results and is found to be accurate and consistent with the mean value close to the unity and a coefficient of variation around 1%.

Polymer Nanostructured Components Machined Directly by the Atomic Force Microscopy Scratching Method

Yong Da Yan,Da Wei Gao,Zhen Jiang Hu,Xue Sen Zhao,Jiu Chun Yan 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

This study aims to machine complex three dimensional nano-structures on polymer surfaces directly using the Atomic Force Microscopy (AFM)-based nano-mechanical processing method. Processing parameters including the normal load, the feed rate, the machining speed and the scanning direction are optimized by the Taguchi method. Their effects on the machined depth and the surface roughness of the machined structures are analyzed. Meanwhile, the AFM PZT tube is controlled to achieve the tip’s three-dimensional motions in space. Using the optimized processing parameters, three-dimensional nanostructures on the surface of PMMA are directly fabricated. It is a novel low-cost manufacturing method for machining complex three-dimensional nano-structures or nano parts on polymer surfaces directly.

Zernike 모멘트를 이용한 회전에 불변한 한자인식 ( Rotation Invariant Recognition of Chinese Characters Using Zernike Moments )

Zhong Jiu Liu,Yong Sung Kim,Whoi Yui Kim 대한전자공학회 1996 대한전자공학회 학술대회 Vol.1996 No.7

Influencing Factors Analysis of Degradation and Damage and the Effect on Steel Frame

Meng Wang,Yong-Jiu Shi,Yuan-Qing Wang,Wei Guo Yang 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.1

In order to discuss the influencing factors of damage and degradation and the effect on steel frame subject to strongearthquakes, firstly, a constitutive model was proposed for 3D finite element models to calculate the seismic behaviors of steelframe more accurately. The model was proved correct and applicable due to typical quasi-static tests. Then, based on theverified model, the damage and degradation factors were discussed by parametric analyses, including the panel zone, loadinghistory, loading amplitude, the width to thickness ratio and yield strength. The cumulative damage phenomena of steel frameconnections were further studied and the degradation distribution curve was obtained. Finally, the traditional beam elementmodel and proposed shell element model of structure were established by ABAQUS for time history analysis. The effect ofdamage and degradation on seismic behaviors of steel frames were compared and discussed. The tests and analysis resultsrevealed that: panel zone strength, loading amplitude and width-thickness ratios of plates had significant impact on damage anddegradation behaviors and failure modes of connections. Premature weld cracking would lead to earlier damage and degradationunder “strong to weak” earthquake, which would seriously affect the overall mechanical properties of the structure. Once localbuckling caused damage, the results of the beam element model and accurate shell element model were remarkably different. Beam element model without considering damage and degradation underestimated the structural deformations, which shouldbe paid more attention for design safety.

Recent Research Advances of High Strength Steel Structures and Codification of Design Specification in China

Gang Shi,Fangxin Hu,Yong-Jiu Shi 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.4

High strength steel (HSS) with the nominal yield strength fy≥460 MPa has been applied in numerous modern building andbridge structures all over the world. Steel structures using high strength steel have obvious advantages in structural,architectural, economical, environment protection and energy saving aspects. After a brief introduction of early studies, recentresearch advances of high strength steel structures in Tsinghua University in China are comprehensively reviewed. Systematicinvestigations have been carried out on static- and cyclic-loading behavior of high strength steels and their welded connections,residual stress of high strength steel hot-rolled and welded sections, overall and local buckling behavior of high strength steelcolumns under axial compression, seismic behavior of high strength steel columns under combined bending and compression,bearing and slip resistance of bolted connections with high strength steel slices. The research results show that mechanicalbehavior of high strength steel structures has been improved much compared with ordinary strength steel structures, so thedesign methods in current design codes or specifications need be updated to be applicable to high strength steel structures. Therefore, as the chief-editor institute, Tsinghua University has organized 34 institutes including universities, design andresearch institutes, steel structure fabricators, and steel manufacturers, to codify a new code, i.e. Design Specification of HighStrength Steel Structures in China. Based on the above research results, new design methods and calculation formulaeapplicable to high strength steel structures are incorporated into this design specification. The outline of this specification isdiscussed in detail in this paper.

Controlled Growth of Well-Defined Conjugated Polymers from the Surfaces of Multiwalled Carbon Nanotubes: Photoresponse Enhancement <i>via</i> Charge Separation

Hou, Wenpeng,Zhao, Ning-Jiu,Meng, Dongli,Tang, Jing,Zeng, Yi,Wu, Yu,Weng, Yangziwan,Cheng, Chungui,Xu, Xiulai,Li, Yi,Zhang, Jian-Ping,Huang, Yong,Bielawski, Christopher W.,Geng, Jianxin American Chemical Society 2016 ACS NANO Vol.10 No.5

<P>The installation of heterojunctions on the surfaces of carbon nanotubes (CNTs) is an effective method for promoting the charge separation processes needed for CNT-based electronics and optoelectronics applications. Conjugated polymers are proven state-of-the-art candidates for modifying the surfaces of CNTs. However, all previous attempts to incorporate conjugated polymers to CNTs resulted in unordered interfaces. Herein we show that well-defined chains of regioregular poly(3-hexylthiophene) (P3HT) were successfully grown from the surfaces of multiwalled CNTs (MWNTs) using surface-initiated Kumada catalyst-transfer polycondensation. The polymerization was found to proceed in a controlled manner as chains of tunable lengths were prepared through variation of the initial monomer-to-initiator ratio. Moreover, it was determined that large-diameter MWNTs afforded highly ordered P3HT aggregates, which exhibited a markedly bathochromically shifted optical absorption due to a high grafting density induced planarization of the polymer chains. Using ultrafast spectroscopy, the heterojunctions formed between the MWNTs and P3HT were shown to effectively overcome the binding energy of excitons, leading to photoinduced electron transfer from P3HT to MWNTs. Finally, when used as prototype devices, the individual MWNT-g-P3HT core-shell structures exhibited excellent photoresponses under a low illumination density.</P>

Online Monitoring System of Fish Behavior

Gang Xiao,Wen Zhang,Yong-Liang Zhang,Jiu-Jun Chen,Shan-Shan Huang,Lu-Ming Zhu 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10

In order to overcome the defect of physic-chemical monitoring system and enhance the intelligence of biological monitoring technology, an online monitoring system of fish behavior is proposed in this paper. The main contributions of this system are as follows: 1) adaptive background updating algorithm (ABU); 2) automatic camshift tracking algorithm (ACT) with twice searching; 3) particle filter tracking (PFT) algorithm; 4) persistent turning walker (PTW) model; 5) artificial immune algorithm (AIA). This online system is used to monitor and analyse the fish behavior continuously, establish a normal behavior model and detect the anormal behavior. Experimental results show that the system is running stably and has achieved well effect in the simulation environment.

Cloning of gonadal aromatase gene Cyp19a in an endemic fish (Schizothorax kozlovi) of the Upper Yangtze River, and temperature effects on its expression

De-guo Yang,Yong-feng He,Xing-bing Wu,Yong-jiu Zhu 한국유전학회 2016 Genes & Genomics Vol.38 No.9

In order to elucidate the role of Cyp19a in sex differentiation of Schizothorax kozlovi, the full length cDNA of Cyp19a was cloned from the mature ovary of S. kozlovi by using rapid amplification of cDNA ends method, and then its relative mRNA expression levels among tissues and temperature groups were determined by using quantitative real-time PCR. The complete Cyp19a cDNA of 1795 bp of S. kozlovi was obtained, which encoded 517 amino acids and belonged to gonadal aromatase. Its deduced amino acid sequence had the above 70 % identity compared with gonadal aromatase genes of teleost fishes, but only 62–67 % when compared with brain aromatase genes of fishes. It was expressed only in heart and gonad, but no expression in other tissues, presenting relatively high tissue specificity. It also exhibited sex-specific expression pattern in gonads, but no sex differences in heart. Comparing with the Cyp19a expression levels at 12 days post hatching (dph), significant temperature effects were revealed in low temperature group (10 C) at 18 dph, and in high temperature group (26 C) at 40 dph. It suggested that gonadal aromatase Cyp19a gene may play important roles on the feminization or masculinization of S. kozlovi affected by temperature during the early developmental stage.

Theoretical and Exprerimental Sutdy on Interactive Local Buckling of Arch-shaped Corrugated Steel Roof

Li-Li Wu,Xuan-Neng Gao,Yong-Jiu Shi,Yuan-Qing Wang 한국강구조학회 2006 International Journal of Steel Structures Vol.6 No.3

The arch-shaped corugated steel roof is a new type of cold formed thin-waled structure. Since the width-to-thickness ratiosof the plate asemblies of corrugated sections exceed the limits specified in the current design codes, the load-bearingbehavior, especialy loading modes, initial imperfections and boundary conditions, therefore its ultimate load-carying capacityis determined not only by its global stability, but also by its interactive local buckling. In this paper the finite element methodwas aplied to analyze the local buckling behavior of stel arch panels with corrugated trapezium sections. Some tests on theloads to further investigate the loading mechanism of corrugated steel arch panels and the factors refered above. A comparisonbetween the experimental and theoretical results was made, and good agrement was achieved herein. It is shown that therealso exists interactive local buckling among corugated plate assemblies. The experimental results are lower than theoreticalones for axial loading capacity, vice-versa, the former ones are higher for eccentricaly loaded specimens. It is noted that thealso indicate that the trapezium sections have high local buckling capacities, yet they hardly have post-buckling capacities,which are distinctive from that of the plain ones. All these also give some explanations to some corugated steel arch rofscolapsed suddenly in some areas of China.