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 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.

Preparation and Properties of HUHPC with Low Shrinkage and High Impact Resistance

Qingjun Ding,Jinhua Gong,Gaozhan Zhang,Yang Liu,Jun Yang,Yongyuan Zhang,Peng Zhou 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.8

At present, nuclear energy is widely used to reduce pollution and clean energy. However, the radiation-proof concrete currently used to prepare nuclear shields cannot meet the protection requirements of nuclear safety. Therefore, there is an urgent need to develop radiation-proof concrete materials with high impact resistance and ultra-high strength. In this paper, the low-shrinkage, high-impact Heavy Ultra-High-Performance Concrete (HUHPC) was designed by the following innovative methods: Porous high titanium heavy slag sand (HTHS) (industrial solid waste) with “slow-water release” effect and expansion agent were synergistically used to improve volume stability; Irregular HTHS with “embedded lock” effect and steel fibers were synergistically utilized to enhance impact resistance; Heavy ilmenite sand was used to lift volume weight. The workability, mechanical properties, volume stability, impact resistance, and microstructure were studied. The results show that the designed HUHPC volume weight is more than 2,800 kg/m3 which can enhance the radiation protection performance greatly. The 180 d shrinkage of HUHPC is less than 400 με, which volume stability is improved by more than 30%. The addition of lithium carbonate slightly decreased the 28 d strength of HUHPC, but the appropriate admixture amount (0.9%) could improve the impact resistance of HUHPC by 33%.

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.

Amentoflavone protects the hematopoietic system of mice against γ‑irradiation

Xin-yan Qu,Qingjun Li,Xiao-juan Zhang,Zhaofen Wang,Shengqi Wang,Zhe Zhou 대한약학회 2019 Archives of Pharmacal Research Vol.42 No.11

Some flavonoids have been shown to exhibitgood antioxidant activity and protect mice from damageinduced by radiation. Amentoflavone (AMF), a biflavonoidderived from the traditional herb-Selaginella tamariscina,has been reported to have antioxidant properties. The protectiveeffects and mechanism of action of AMF against radiationinjury remain unknown. In this study, male C57BL/6mice were subjected to total-body 60Co γ-irradiation at 7.5or 3.0 Gy. The survival rate and mean survival time wereevaluated to determine the radioprotective effect of AMF. Number of peripheral blood cells, frequency of colony formingunit-granulocytes, monocytes and micronuclei weremeasured to assess the protective effects of AMF on thehematopoietic system. Levels of superoxide dismutase andglutathione, and pathological changes in the bone marrowwere determined. Additionally, next-generation sequencingtechnology was used to explore potential targets of AMF. Weobserved that AMF markedly extends average survival time,reduces injury to the hematopoietic system and promotes itsrecovery. Furthermore, treatment with AMF significantlyattenuated radiation-induced oxidative stress. In addition,AMF had a significant effect on gene tumor necrosis factor alpha-induced protein 2. Together, the results of this studysuggest that AMF is a potential protective agent againstradiation injury.

High vis-light photocatalytic property of g-C3N4 on four pollutants (RhB, MB, TC-HCl and P-Nitrophenol)

Lian Xiaoxue,Li Yan,Zou Yunling,An Dongmin,Wang Qiong,Zhou Qingjun,Li Xueqi 한국물리학회 2022 Current Applied Physics Vol.39 No.-

The g-C3N4 nanosheets were synthesized by a multistage program calcination with different heating rate, which was an easy, low-cost, and quick method. The morphology and structure of samples were characterized by various techniques. The performance evaluation of the samples was tested by degrading Rhodamine B, Methylene Blue, Tetracycline Hydrochloride and P-Nitrophenol in visible light. The results show that the photodegradation properties of TP-g-C3N4 prepared by multistage program calcination are the best than others. In particular, the degradation rate of TP-g-C3N4 to Rhodamine B reached 99.6% in just 4 min. TP-g-C3N4 catalyst has excellent stability and recycling performance. According to free radical capture experiments, •O2- may be the main active species for pollutant degradation. The possible photocatalytic degradation mechanism was also discussed. Due to the high specific surface area and a narrow band gap, the TP-g-C3N4 becomes a promising photocatalyst.

Blasting vibration velocity prediction based on least squares support vector machine with particle swarm optimization algorithm

Qing Yuan,Shihong Zhai,Li Wu,Peishuai Chen,Yuchun Zhou,Qingjun Zuo 한국자원공학회 2019 Geosystem engineering Vol.22 No.5

In blasting excavation engineering of super-large section underground caverns, blasting vibration velocity prediction accuracy is affected by many factors. In order to improve its accuracy, the key problem is to obtain these affect factors comprehensively. In this paper, we innovatively put forward eight independent factors in the aspect of explosion source conditions, engineering conditions and propagation medium conditions. These factors have complex non-linear relationship with blasting vibration velocity. We consider particle swarm optimization (PSO) algorithm and least squares support vector machine (LS-SVM) method for prediction (PSO-LSSVM). In this way, how to determine the characteristic parameters and calculation rules of PSO-LSSVM method is another key problem, which has been innovatively solved in this paper. Then it is used to predict the blasting vibration velocity of underground water-sealed LPG caverns in Yantai, China, and compared with Sadov’s formula (SA), fuzzy neural network (FNN) and LS-SVM methods. The results indicate that relative errors of PSO-LSSVM are significantly less than LS-SVM, FNN and SA. Whether global root mean square relative error for prediction accuracy, or group number meeting requirement of error threshold value for generalization performance, the PSO-LSSVM method is superior to LS-SVM, FNN and SA with best availability and superiority.