Ultimate behavior of long-span steel arch bridges

Cheng, Jin,Jiang, Jian-Jing,Xiao, Ru-Cheng,Xiang, Hai-Fan Techno-Press 2002 Structural Engineering and Mechanics, An Int'l Jou Vol.14 No.3

Because of the increasing span of arch bridges, ultimate capacity analysis recently becomes more focused both on design and construction. This paper investigates the static and ultimate behavior of a long-span steel arch bridge up to failure and evaluates the overall safety of the bridge. The example bridge is a long-span steel arch bridge with a 550 m-long central span under construction in Shanghai, China. This will be the longest central span of any arch bridge in the world. Ultimate behavior of the example bridge is investigated using three methods. Comparisons of the accuracy and reliability of the three methods are given. The effects of material nonlinearity of individual bridge element and distribution pattern of live load and initial lateral deflection of main arch ribs as well as yield stresses of material and changes of temperature on the ultimate load-carrying capacity of the bridge have been studied. The results show that the distribution pattern of live load and yield stresses of material have important effects on bridge behavior. The critical load analyses based on the linear buckling method and geometrically nonlinear buckling method considerably overestimate the load-carrying capacity of the bridge. The ultimate load-carrying capacity analysis and overall safety evaluation of a long-span steel arch bridge should be based on the geometrically and materially nonlinear buckling method. Finally, the in-plane failure mechanism of long-span steel arch bridges is explained by tracing the spread of plastic zones.

Tumor Necrosis Factor-α 238 G/A Polymorphism and Risk of Hepatocellular Carcinoma: Evidence from a Meta-analysis

Cheng, Ke,Zhao, Yu-Jun,Liu, Lian,Wan, Jing-Jing Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.5

Background: Tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) plays a very important role in the development and progression of cancer. Many epidemiological studies have evaluated associations between the TNF-${\alpha}$ 238 G/A polymorphism and hepatocellular carcinoma (HCC) risk, but the published data are inconclusive. Therefore, we performed the present meta-analysis. Methods: Electronic searches of several databases were conducted for all publications on the association between TNF-${\alpha}$ 238 G/A polymorphism and HCC through July 2012. Asummary odds ratio (OR) with its 95% confidence interval (CI) were calculated to evaluate the strength of this association. Results: Eleven case-control studies with a total of 1,572 HCC cases and 1,875 controls were finally included in this meta-analysis. Overall, the TNF-${\alpha}$ 238 G/A polymorphism was significantly associated with increased risk of hepatocellular carcinoma in three genetic comparison models (For A versus G: OR 1.32, 95%CI 1.04-1.69, P = 0.02, $I_2$ = 40%; for AG versus GG: OR 1.32, 95%CI 1.02-1.71, P = 0.03, $I_2$ = 40%; for AA/AG versus GG: OR 1.33, 95%CI 1.03-1.72, P = 0.03, $I_2$ = 41%) when all studies were pooled. Subgroup analysis by ethnicity further showed that there was a significant association between the TNF-${\alpha}$ 238 G/A polymorphism and risk of HCC in Asians under three genetic comparison models (For A versus G: OR 1.30, 95%CI 1.00-1.68, P = 0.05, $I_2$ = 45% for AA/AG versus GG: OR 1.31, 95%CI 1.00-1.71, P = 0.05, $I_2$ = 46%). Conclusions: This meta-analysis provided convincing evidence that the TNF-${\alpha}$ 238 G/A polymorphism is associated with increased susceptibility to HCC. However, more well-designed studies with large sample size are needed to validate this association in Caucasians.

Effect of Water Quality Parameters on the Survival of Indicator Microorganisms in Stormwater Wetland

( Jing Cheng Si ),( Ping Niu Yao ),( Ping Chen ),( Ki Soo Park ),( Heidi B. Guerra ),( Young Chul Kim ) 한국물환경학회 ( 구 한국수질보전학회 ) 2012 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2012 No.-

Characteristics of Reactively Sputtered Niobium Nitride Thin Films as Diffusion Barriers for Cu Metallization

Cheng-Lin Huang,Chih-Huang Lai,Po-Hao Tsai,Hsing-An Huang,Jing-Cheng Lin,Chiapyng Lee 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.5

NbN films were prepared by radio frequency reactive magnetron sputtering and then employed as diffusion barriers between Cu and Si. The microstructure of the NbN films was an assembly of very small columnar crystallites with a cubic structure. To investigate the properties as diffusion barriers, we performed metallurgical reactions of Cu/NbN0.8/Si, Cu/Nb/Si and Cu/TaN0.7/Si for comparisons. The sheet resistance increased dramatically after annealing above 750°C for Cu/NbN0.80/Si, and above 500°C for both Cu/Nb/Si and Cu/TaN0.7/Si. The interfaces were deteriorated seriously and formation of Cu3Si was observed when the sheet resistance was significantly increased. The diffusion coefficient of Cu in NbN barrier films was estimated by using the change of resistance (ΔRs/Rs %). Compared with TaN0.7, NbN0.8 films possess larger grain size and lower Cu diffusion coefficient. Our results suggest that the NbN film can be used as a diffusion barrier for Cu metallization as compared to the well-known TaN film.

Thermal Stability, Adhesion and Electrical Studies on (Ti,Zr)Nx Thin Films as Low Resistive Diffusion Barriers between Cu and Si

Cheng-Lin Huang,Chih-Huang Lai,Po-Hao Tsai,Yu-Lin Kuo,Jing-Cheng Lin,Chiapyng Lee 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.3

In this study, we investigated the thermal stability, wettability, adhesion and reliability of (Ti,Zr)Nx films used as the diffusion barrier between Cu and Si. (Ti,Zr)Nx films were prepared by DC reactive magnetron sputtering from a Ti-5 at. % Zr alloy target in N2/Ar gas mixtures. A minimum film resistivity of 59.3 μΩ cm was obtained at an N2/Ar flow ratio of 2.75, which corresponds to the near stoichiometric composition (N/(Ti,Zr) ratio ~0.95). The sheet resistance of Cu/(Ti,Zr)N0.95/Si was not significantly increased until annealing above 750°C, indicating good thermal stability. On the other hand, the adhesion energy between Cu and the (Ti,Zr)Nx film was reduced as the N/Ti ratio was increased. To obtain reliable performance on stress-induced-voiding (SIV) and electromigration (EM) tests, we proposed to use (Ti,Zr)/(Ti,Zr)Nx/(Ti,Zr) tri-layers. We suggest that the interfacial adhesion between barrier and Cu plays an important role in reliability. The proposed tri-layer structure may be a promising candidate for a barrier, as it exhibits excellent reliability without increasing resistance.

Probabilistic determination of initial cable forces of cable-stayed bridges under dead loads

Cheng, Jin,Xiao, Ru-Cheng,Jiang, Jian-Jing Techno-Press 2004 Structural Engineering and Mechanics, An Int'l Jou Vol.17 No.2

This paper presents an improved Monte Carlo simulation for the probabilistic determination of initial cable forces of cable-stayed bridges under dead loads using the response surfaces method. A response surface (i.e. a quadratic response surface without cross-terms) is used to approximate structural response. The use of the response surface eliminates the need to perform a deterministic analysis in each simulation loop. In addition, use of the response surface requires fewer simulation loops than conventional Monte Carlo simulation. Thereby, the computation time is saved significantly. The statistics (e.g. mean value, standard deviation) of the structural response are calculated through conventional Monte Carlo simulation method. By using Monte Carlo simulation, it is possible to use the existing deterministic finite element code without modifying it. Probabilistic analysis of a truss demonstrates the proposed method' efficiency and accuracy; probabilistic determination of initial cable forces of a cable-stayed bridge under dead loads verifies the method's applicability.

Regeneration of hexamminecobalt(II) under the catalysis of activated carbon modified with ZnCl2 solution

Jing-yi Cheng,Lin Yang,Wei-kang Yuan,Xiang-li Long 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.5

The simultaneous scrubbing of NO and SO2 can be accomplished by hexamminecobalt(II) solution. Activated carbon acts as a catalyst to regenerate hexamminecobalt(II), Co(NH3)62+, to sustain the NO removal efficiency. In this paper, ZnCl2 solution has been used to ameliorate the catalytic performance of coconut activated carbon in the regeneration of Co(NH3)62+. The effects of the modification condition on the catalytic performance of activated carbon have been investigated in a batch stirred cell. The change of the surface chemical characteristics of the activated carbon caused by ZnCl2 treatment was measured by determining the concentrations of acidic and basic groups as well as their points of zero charge (pHpzc)with Boehm titration and mass titration. The alteration of the surface physical characteristics of the carbons was determined with an ASAP2000 Surface Analyzer using N2 as the adsorbate. The experiments demonstrate that the catalytic performance of the coconut activated carbon may be improved when the carbon is treated by ZnCl2 solution with concentration above 0.30 mol l1. The best ZnCl2 concentration may be 0.50 mol l1. The optimal impregnation duration is 9 h. High activation temperature is propitious for the amelioration of the catalytic capability of carbon. 4 h may be the best time for the activation of activated carbon. In our experiment, the NO removal efficiency is maintained at a level of 73% when the regeneration of Co(NH3)62+ is under the catalysis of modified carbon while that is 57% with the regeneration of Co(NH3)62+ catalyzed by original carbon. It can be concluded that such modification can improve the catalytic performance of coconut activated carbon in the simultaneous removal of SO2 and NO with Co(NH3)62+ ammonia solution.

Attitudes Towards English Language Learning Apps from Korean and Chinese EFL Students

Jing Cheng,김현주 한국영어교육학회 2019 ENGLISH TEACHING(영어교육) Vol.74 No.4

The purpose of study was to investigate university students’ attitudes towards English language learning apps and examine whether there is any significant difference in their attitudes depending on their personal variables such as their gender, major, grade, nationality, and so on. This study also explored students’ perceptions of English language learning apps that they have used. Participants were college students living in Korea and China. Data were collected by means of a questionnaire and an interview. Results showed that both Korean and Chinese students generally held positive attitudes towards English language learning apps, although Chinese students showed more positive attitudes than Koreans. The main reasons that they liked to use English language learning apps were their convenience, ubiquity, and rich resources. On the other hands, it was revealed that the lack of communication and feedback was the main problem of using such apps. Both Korean and Chinese students stated that it was an effective way to use English language learning apps to practice pronunciation, vocabulary, listening, and reading skills. Findings of this research suggest that English language learning apps should be developed to inspire users/students’ learning interest and foster learner autonomy.

Investigation of Proteomic Responses of Streptomyces lydicus to Pitching Ratios for Improving Streptolydigin Production

Jing-Sheng Cheng,Xiao-Min Lv,Ying-Jin Yuan 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.5

Streptomyces lydicus has been reported to produce antibiotic streptolydigin. Pitching ratios play crucial roles in primary and secondary metabolism of Streptomyces bacteria. The higher pitching ratio (30%, v/v)significantly enhanced the levels of streptolydigin products in S. lydicus. Proteome analysis revealed that betaglucosidase and UTP-glucose-1-phosphate uridylyltransferase were up-regulated to accelerate the starch hydrolyzation at the high pitching ratios. Enhancement in the levels of UDPN-acetylmuramoylalanyl-D-glutamate-2, 6-diaminopimelate ligase and glycine cleavage system aminomethyltransferase were involved in the conversion of amino acids into secondary metabolites. Additionally, the expression levels of PfkA2, PfkA3, Zwf2, SucD, GalE1, GatB, TktA1 and ThcA, associated with glycolysis, pentose phosphate pathway, TCA cycle and amino acid metabolism, were dramatically elevated at high pitching ratios, which play important roles in the enhanced streptolydigin production in S. lydicus E9. Interestingly, the levels of proteins (glutamine synthetase I, glutamate synthase subunit beta and glutamine synthetase) were down-regulated with the increases of pitching ratios and fermentation progress,revealing that pitching ratio altered the glutamine synthetase levels and consequently regulated the streptolydigin production of S. lydicus E9. The up-regulation of proteins (eg, aldehyde dehydrogenase and alkyl hydroperoxide reductase) was involved in the redox-based regulation network triggered by an imbalance of the intracellular cell redox homeostasis and by crosstalk with secondary metabolism at the higher pitching ratio. These results settle new insights into physiological facts of S. lydicus E9 in responses to pitching ratios and will eventually improve the antibiotic production schemes in industry.

Mangiferin ameliorates cardiac fibrosis in D-galactose-induced aging rats by inhibiting TGF-β/p38/MK2 signaling pathway

Cheng, Jing,Ren, Chaoyang,Cheng, Renli,Li, Yunning,Liu, Ping,Wang, Wei,Liu, Li The Korean Society of Pharmacology 2021 The Korean Journal of Physiology & Pharmacology Vol.25 No.2

Aging is the process spontaneously occurred in living organisms. Cardiac fibrosis is a pathophysiological process of cardiac aging. Mangiferin is a well-known C-glucoside xanthone in mango leaves with lots of beneficial properties. In this study, rat model of cardiac fibrosis was induced by injected with 150 mg/kg/d D-galactose for 8 weeks. The age-related cardiac decline was estimated by detecting the relative weight of heart, the serum levels of cardiac injury indicators and the expression of hypertrophic biomakers. Cardiac oxidative stress and local inflammation were measured by detecting the levels of malondialdehyde, enzymatic antioxidant status and proinflammatory cytokines. Cardiac fibrosis was evaluated by observing collagen deposition via masson and sirius red staining, as well as by examining the expression of extracellular matrix proteins via Western blot analysis. The cardiac activity of profibrotic TGF-β1/p38/MK2 signaling pathway was assessed by measuring the expression of TGF-β1 and the phosphorylation levels of p38 and MK2. It was observed that mangiferin ameliorated D-galactose-induced cardiac aging, attenuated cardiac oxidative stress, inflammation and fibrosis, as well as inhibited the activation of TGF-β1/p38/MK2 signaling pathway. These results showed that mangiferin could ameliorate cardiac fibrosis in D-galactose-induced aging rats possibly via inhibiting TGF-β/p38/MK2 signaling pathway.