Experimental Investigation on Fatigue Strength of Joints between SRC Beams and Concrete-Filled RHS Columns

Qingjun Xian,Le-Wei Tong,Liying Zhou,Yiyi Chen 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.5

Fatigue behavior, failure mechanism and fatigue strength of joints between steel reinforced concrete (SRC) beams and Concrete Filled Rectangular Hollow Section (CFRHS) columns is discussed in this paper. Three identical beam-to-column joint specimens were designed and tested under static loading and two stages of fatigue loading. In the first stage of fatigue loading, the specimens were subjected to design fatigue load for 2 million cycles, while during the second stage, they were loaded to failure under increased fatigue load in order to know failure mechanism and fatigue strength. It is found that the joints satisfied design requirements when subjected to static loading and design fatigue loading. Fatigue failure occurred after these joints were applied higher-level fatigue loading. The crack initiated at the weld toe of stud or stirrup hole in the upper flange of I-shaped steel in certain SRC beam, and then it propagated along flange width in winding trajectory until fatigue fracture occurred. Stress amplitude of tension flange in SRC beam can be regarded as the parameter representing fatigue strength of the joints. S-N curves in related codes are selected to evaluate fatigue strength of the joints. The design method is suggested to consider fatigue design of the joints.

Evaluation and optimization of SrCo0.9Ta0.1O3−δ perovskite as cathode for solid oxide fuel cells

Qingjun Zhou,Tong Wei,Yihua Shi,Songqing Guo,Yan Li,Jingxin Su,Huan Ren,Yin Zhu,김경국 한국물리학회 2012 Current Applied Physics Vol.12 No.4

The SrCo0.9Ta0.1O3-δ (SCT) perovskite-type oxide is synthesized by the conventional solid state reaction method and examined as an alternative cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). The electrical conductivity of SCT sample reaches 250e152 S cm-1 in the temperature range 600e800 ℃. SCT exhibits good chemical compatibility with the intermediate-temperature electrolyte material Sm0.2Ce0.8O1.9 (SDC). The average thermal expansion coefficient of SCT is 21.4 × 10-6 K-1. The cathode area specific resistance (ASR) of SCT is only 0.095 U cm2 at 750 ℃ and it decreases to 0.068 U cm2 when SDC is added to form a SCT-SDC composite cathode. The results indicate that the SCT can be a promising alternative cathode material for IT-SOFCs.

Experimental Investigation on Fatigue Behavior of Steel Reinforced Concrete Composite Beam-to-Girder Joints

Le-Wei Tong,Qingjun Xian,Liying Zhou,Yiyi Chen,Yunfeng Zhang 한국강구조학회 2012 International Journal of Steel Structures Vol.12 No.4

Fatigue behavior and failure mechanism of steel reinforced concrete (SRC) beam-to-girder joints is discussed in this paper,which is intended for use in high-speed railway station structures due to their high stiffness and load capacity. Three identical SRC beam-to-girder joint specimens were designed and tested under static loading and two stages of fatigue loading. In the first stage of fatigue loading, the specimens were subjected to design fatigue load for 2 million cycles, while during the second stage, the specimens were loaded to failure under increased fatigue loading amplitude in order to know its fatigue strength and failure mechanism. The constructional details of SRC beam-to-girder joint specimen and the method of loading and testing are presented. The comparison in structural behavior of the joint is made between under static and fatigue loading. Fatigue failure characteristics of the joint are described in detail. It is found that the SRC beam-to-girder joints remained in their elastic range and the concrete surface crack did not exceed 0.1 mm when subjected to design static loading and 2 million cycles of design fatigue loading. There was no significant difference in structural behavior of each component of SRC composite beam between static and fatigue loading. Fatigue failure occurred after these joints were applied higher-level fatigue loading for another 0.70to 0.91 million cycles. Fatigue crack was initiated at the tension flange of I-shape steel of beam connected by welding to the flange of I-shape steel of girder or at the hole in tension flange of I-shape steel of beam, and then the crack propagated along flange width and web height of the I-shape steel in beam until the I-shape steel lost loading capacity due to lack of enough cross section. The fatigue behavior of constructional detail of the I-shape steel played a key role in the fatigue strength of the SRC beam-to-girder joints. Discussions on improving the fatigue strength of SRC beam-to-girder joints and future research aspects are presented finally.

Synthesis of acetic acid-[(hydrazinylthioxomethyl)thio]-sodium and its application on the flotation separation of molybdenite from galena

Zhigang Yin,Wei Sun,Yuehua Hu,Runqing Liu,Wei Jiang,Chenhu Zhang,Qingjun Guan,Chenyang Zhang 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.52 No.-

A novel organic compound acetic acid-[(hydrazinylthioxomethyl)thio]-sodium was synthesized andcharacterized. Theflotation performance and adsorption mechanism of AHS to galena were investigatedby micro, benchflotation tests, UV spectra, zeta potential, FTIR and XPS measurements. The resultsdemonstrated that AHS exhibited superior depressing power to galena and could be used as selectivedepressant forflotation separation of molybdenite from galena. The results of UV spectra, FTIR, zetapotential and XPS measurements demonstrated that AHS chemisorb on galena surface by formingfivememberedcheat ring with releasing of H ions. Therefore, the possible adsorption mode of AHS on galenasurface was recommended.

Indole-3-acetic acid ameliorates dextran sulfate sodium-induced colitis via the ERK signaling pathway

Xinyan Qu,Yingying Song,Qingjun Li,Qi Xu,Yanru Li,Huimin Zhang,Xuemei Cheng,Charles R. Mackay,Quanbo Wang,Wei Liu 대한약학회 2024 Archives of Pharmacal Research Vol.47 No.3

Microbiota-derived catabolism of nutrients is closely related to ulcerative colitis (UC). The level of indole-3-acetic acid(IAA), a microbiota-dependent metabolite of tryptophan, was decreased signifi cantly in the feces of UC patients. Thus supplementationwith IAA could be a potential therapeutic method for ameliorating colitis. In this work, the protective eff ect ofsupplementation with IAA on dextran sulfate sodium (DSS)-induced colitis was evaluated, and the underlying mechanismwas elucidated. The results indicated that the administration of IAA signifi cantly relieved DSS-induced weight loss, reducedthe disease activity index (DAI), restored colon length, alleviated intestinal injury, and improved the intestinal tight junctionbarrier. Furthermore, IAA inhibited intestinal infl ammation by reducing the expression of proinfl ammatory cytokines andpromoting the production of IL-10 and TGF-β1. In addition, the ERK signaling pathway is an important mediator of variousphysiological processes including infl ammatory responses and is closely associated with the expression of IL-10. Notably,IAA treatment induced the activation of extracellular signal-regulated kinase (ERK), which is involved in the progressionof colitis, while the ERK inhibitor U0126 attenuated the benefi cial eff ects of IAA. In summary, IAA could attenuate theclinical symptoms of colitis, and the ERK signaling pathway was involved in the underlying mechanism. Supplementationwith IAA could be a potential option for preventing or ameliorating UC.

MicroRNA-338-3p as a novel therapeutic target for intervertebral disc degeneration

Jiang Hua,Moro Abu,Wang Jiaqi,Meng Dihua,Zhan Xinli,Wei Qingjun 생화학분자생물학회 2021 Experimental and molecular medicine Vol.53 No.-

Recent studies have demonstrated the pivotal role played by microRNAs (miRNAs) in the etiopathogenesis of intervertebral disc degeneration (IDD). The study of miRNA intervention in IDD models may promote the advancement of miRNA-based therapeutic strategies. The aim of the current study was to investigate whether intradiscal delivery of miRNA can attenuate IDD development. Our results showed that miR-338-3p expression was significantly increased in the nucleus pulposus (NP) of patients with IDD. Moreover, there was a statistically significant positive correlation between the expression level of miR-338-3p and the severity of IDD. Our functional studies showed that miR-338-3p significantly influenced the expression of extracellular matrix synthesis genes, as well as the proliferation and apoptosis of NP cells. Mechanistically, miR-338-3p aggravated IDD progression by directly targeting SIRT6, a negative regulator of the MAPK/ERK pathway. Intradiscal injection of antagomir-338-3p significantly decelerated IDD development in mouse models. Our study is the first to identify miR-338-3p as a mediator of IDD and thus may be a promising target for rescuing IDD.