Behavior of Cantilever Composite Girder Bridges with CSWs under Eccentric Loading

Wenqin Deng,Duo Liu,Zongqing Peng,Jiandong Zhang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.10

A study on the torsion and distortion properties of the cantilever single-box three-cell composite girder bridge with corrugated steel webs (CSWs) is carried out based on experimental testing and finite element model analysis. Firstly, the mechanical characteristics such as the deformation, longitudinal warping normal stress were investigated based on a double cantilever girder model test. Secondly, the influence of parameters such as girder height, box width and corrugated steel web thickness on the warping stress of cantilever composite girder with CSWs under eccentric load were analyzed based on the finite element model. Finally, the eccentric load effect of the composite bridge with CSWs at the maximum cantilever construction stage under different load combinations was analyzed based on a finite element model of the real bridge. The results show that the longitudinal warping strain of the CSWs is significantly smaller than that of the top and bottom concrete slabs under eccentric loading due to the accordion effect. The maximum warping normal stress occurs at the corners of the bottom concrete slab. The additional shear stress of the steel webs distributes uniformly along the girder height, and the additional stress of the web on the loading side is clearly greater than that at the middle. The finite element parameter analysis results show that the height and width have a significant influence on the warping stress of single box three-cell composite girder with CSWs, and the thickness of CSWs has almost no effect. In practical engineering, the warping stress of the bottom slab accounts for approximately 20% of the bending stress when the self-weight is considered. Therefore, it is not trivial to consider the influence of the warping normal stress of a concrete slab and the additional shear stress of the CSWs in the design and calculation of this type of bridge.

Lithium chloride promotes proliferation of neural stem cells in vitro, possibly by triggering the Wnt signaling pathway

Jian Zhang,Lu He,Zhong Yang,Lihong Li,Wenqin Cai 한국통합생물학회 2019 Animal cells and systems Vol.23 No.1

The objective of this study was to clarify the relationship between the effect and associated mechanisms of lithium chloride on neural stem cells (NSCs) and the Wnt signaling pathway. The expression of key molecules proteins related to the Wnt signaling pathway in the proliferation and differentiation of control NSCs and lithium chloride-treated NSCs was detected by Western blot analysis. Flow cytometry analysis was applied to study the cell cycle dynamics of control NSCs and NSCs treated with lithium chloride. The therapeutic concentrations of lithium chloride stimulated NSC proliferation. β-catenin expression gradually decreased, while Gsk-3β expression gradually increased (P < 0.01). Furthermore, NSCs treated with lithium chloride showed significantly enhanced β-catenin expression and inhibited Gsk-3β expression in a dosedependent manner. NSCs in the G0/G1-phases were activated with an increased therapeutic concentration of lithium chloride, while NSCs in the S-phase, as well as G2/M-phases, were arrested (P < 0.01). These data confirm that the proliferation of NSCs is remarkably promoted through changes of cell dynamics after treatment with lithium chloride. Our results provide insight into the effects of lithium chloride in promoting the proliferation abilities of NSCs in vitro and preventing the cells from differentiating, which is potentially mediated by activation of the Wnt signaling pathway.

Academia or enterprises: gender, research outputs, and employment among PhD graduates in China

Shen Wenqin,Gao Yao,Zhang Bin,Jiang Jin 서울대학교 교육연구소 2018 Asia Pacific Education Review Vol.19 No.2

PhD graduates play an important role in the national innovation system. However, only a few studies have explored Chinese PhD graduates’ employment and development prospects because of limited data. To fill in this gap, this study conducted a survey of doctoral recipients in 13 Chinese universities. The authors drew on the national survey data and in-depth interviews to critically analyze the PhD graduates’ job preferences, employment outcomes, and factors that affect their employment sectors. Results indicate a notable difference between the graduates’ job preferences and their employment outcomes. The proportion of employment in academia is substantially below expected, particularly among female graduates. This study specifically focuses on the impact of gender and scientific output (including articles and patents) on the employment outcomes of PhD graduates. Compared with graduates employed by the non-academic sectors, male graduates have a lower probability of employment in universities and research institutions. Compared with those working in enterprises, PhD graduates employed in universities and research institutions published more during their doctoral study. For graduates who majored in science, engineering, and agricultural sciences, having patents increases their probability of working in the enterprises.

A potential industrialized fiber-supported copper catalyst for one-pot multicomponent CuAAC reactions in water

Xian-Lei Shi,Yongju Chen,Qianqian Hu,Wenqin Zhang,Chenxu Luo,Peigao Duan 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.53 No.-

A potential industrialized fiber catalyst for “click chemistry” via the one-pot multicomponent Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) for the synthesis of 1,2,3-triazoles in water, is reported. Detailed characterization by appearance, mechanical properties, elemental analysis, FTIR spectroscopy, and SEM confirmed the rangeability of the fiber catalyst during the preparation and utilization processes. Moreover, the fiber catalyst-mediated reactions proceeded smoothly to afford triazoles with nearly quantitative yields in short time (15 min). Furthermore, the fiber catalyst has shown tandem activities and superior recyclability (over 10 cycles), and the procedure is operationally simple and amenable to the gram-scale on a simple fixed-bed reactor.

Mechanical Behavior of Composite Beams Considering Nonlinear Shear Stiffness of Clustered Studs

Duo Liu,Ding Zhou,Bohai Ji,Wenqin Deng,Shang Zha,Jiandong Zhang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.4

Clustered studs are suitable for use in prefabricated steel-concrete composite beams. As a kind of shear connector, clustered studs have a non-negligible influence on the mechanical behavior of structures. Based on the theory of elasticity, prefabricated composite beams investigated via laminated plane stress problem. The load-slip curves of the shear connectors are linearly processed, and through iterative calculations, the displacement and stress distribution functions of prefabricated composite beams are obtained. Then, a model test is carried out on the positive bending moment section of prefabricated composite beams. A sampling method with front segments controlled by the load and back segments controlled by the slip is adopted. This method provides a better rate of convergence and higher accuracy than those of other methods. The test results show that when the load is small and the composite beam is in the elastic stage, the slope of the load-slip curve can be used as the shear stiffness of the clustered studs. When the load is large and the composite beam enters the plastic stage, the nonlinear shear stiffness of the studs must be considered to obtain a high-precision solution.

Synergistic catalysis of bifunctional polyacrylonitrile fiber for the synthesis of (E)-α,β-unsaturated esters from aldehydes by decarboxylative Doebner–Knoevenagel reaction

Pengyu Li,Liwei Mi,Yuanyuan Liu,Wenqin Zhang,Xian-Lei Shi 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.81 No.-

A series of monofunctional and bifunctional polyacrylonitrilefiber catalysts have been successfullyprepared to catalyze the decarboxylative Doebner–Knoevenagel reaction of aldehydes and monoethylmalonate for the syntheses of the (E)-α,β-unsaturated esters. Among which, the catalyst PANPDFII/I showsthe best synergistic catalytic activity with high yields (89–96%), stereoselectivities (Z:E > 99:1) andreusability (up to 8 times). The influences of the N position on aminopyridine moiety, solvent andtemperature on the catalytic system were investigated in detail. This catalytic system can process well inhigher or lower polar organic solvents instead of moderate polar solvents, which is an interestingphenomenon in organic catalysis, and the reasons are explained in this work. Furthermore, a DMAP (4-dimethylaminopyridine) and piperazine synergistic catalytic mechanism in the micro-environment ofthefiber catalyst has been conceived to explain the high catalytic performance of this catalytic system. Besides, thefiber catalyst PANPDFII/I shows high application potential in industry for its good performancein scaled-up experiment, as well as its advantages of the easy preparation, high mechanical strength,flexibility and high stability in air.

Revisiting the Knoevenagel condensations: A universal and flexible bis-ammoniated fiber catalyst for the mild synthesis of α,β-unsaturated compounds

Qianqian Hu,Xian-Lei Shi,Yongju Chen,Xuefeng Han,Peigao Duan,Wenqin Zhang 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.54 No.-

A universal fiber catalyst for the Knoevenagel condensations is presented. The detailed characterization by mechanical properties, elemental analysis, FTIR spectroscopy, and SEM confirmed the rangeability of the fiber catalyst during the full-course. Moreover, the mediated condensations proceeded smoothly with lower catalyst amount (1 mol%) in different solvents of varying polarities and the products were obtained in good to excellent yields (95–99%), and even with water as the solvent could also achieve a series of a,b-unsaturated compounds with nearly quantitative yields at room temperature. Furthermore, the catalyst exhibited excellent flexibility and could be easily recovered and recycled with prominent stability over 10 cycles, and the procedure was operationally convenient and effectively amenable to the gram scale on a simple fixed-bed reactor.

Study on the neutron imaging detector with high spatial resolution at China spallation neutron source

Jiang, Xingfen,Xiu, Qinglei,Zhou, Jianrong,Yang, Jianqing,Tan, Jinhao,Yang, Wenqin,Zhang, Lianjun,Xia, Yuanguang,Zhou, Xiaojuan,Zhou, Jianjin,Zhu, Lin,Teng, Haiyun,Yang, Gui-an,Song, Yushou,Sun, Zhiji Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.6

Gadolinium oxysulfide (GOS) is regarded as a novel scintillator for the realization of ultra-high spatial resolution in neutron imaging. Monte Carlo simulations of GOS scintillator show that the capability of its spatial resolution is towards the micron level. Through the time-of-flight method, the light output of a GOS scintillator was measured to be 217 photons per captured neutron, ~100 times lower than that of a ZnS/LiF:Ag scintillator. A detector prototype has been developed to evaluate the imaging solution with the GOS scintillator by neutron beam tests. The measured spatial resolution is ~36 ㎛ (28 line pairs/mm) at the modulation transfer function (MTF) of 10%, mainly limited by the low experimental collimation ratio of the beamline. The weak light output of the GOS scintillator requires an enormous increase in the neutron flux to reduce the exposure time for practical applications.

Polyacrylonitrile fiber with strongly acidic electrostatic microenvironment: Highly efficient and recyclable heterogeneous catalyst for the synthesis of heterocyclic compounds

Jian Xiao,Gang Xu,Lu Wang,Pengyu Li,Wenqin Zhang,Ning Ma,Minli Tao 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.77 No.-

Four categories of sulfonic acid functionalizedfiber catalysts with different surface microenvironmentswere synthesized by covalent grafting using polyacrylonitrilefiber (PANF) as the support. After the effectof acid structure on catalytic activity has been investigated by Friedlander reaction, PANEOSF was chosenfor the synthesis of quinolines and coumarin derivatives with high yields and extensive substrate scope(51 examples) in ethanol or water. The effect of electrostatic microenvironment and solvent has beendiscussed, and a “release-catch-release-catch” catalytic pattern was proposed accordingly. PANEOSF canbe easily recycled for 20 times without any decrease of catalytic activity.

Fault Detection for Two-dimensional Multi State Delay Roesser Systems with Finite Frequency Specifications

Wen Qin,Chen Zhang,Mouquan Shen,Guopeng Wang 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.1

This article investigates the problem of fault detection filtering for two dimensional (2-D) continuousdiscrete systems with multi state delay in finite frequency domain. Firstly, by the Lyapunov-Krasovskii functional (LKF) method, a finite frequency bounded real lemma (BRL) is presented. Secondly, based on the obtained finite frequency BRL, an observer-based finite frequency fault detection filter is provided as a residual generator, which is used to simultaneously minimize the disturbance effect and maximize the fault effect in finite frequency ranges. Finally, simulations confirm the effectiveness of the proposed method.