Experimental Study of Seismic Damage with Park-Ang Model for Recycled Aggregate Concrete Columns

Yujiang Fan,Ziqiang Guo,Yachao Wang,Pengcheng Zhao,Binshan Yu 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.9

By means of the low cycle loading tests on six recycled aggregate concrete (RAC) columns with different proportions, in combination with the Park-Ang two-parameter damage model suitable for ordinary concrete columns and the damage degree Dc of actual structures, the calculated value of cyclic loading coefficient β of recycled aggregate concrete columns was determined. It would be achieved by analyzing the calculated β that the impact of the replacement ratio of recycled aggregate and the content of mixed fibers on β was significantly different. Considering the reinforcement ratio mentioned in paper. Matlab was further employed to fit multivariable linear equation regarding recycled aggregate replacement ratio, mixed fibers contents and reinforcement rate as the basis, so that the computation formula of the cyclic loading coefficient β suitable for recycled aggregate concrete columns was revealed.

Study on the influence of flow blockage in severe accident scenario of CAP1400 reactor

Gao Pengcheng,Zhang Bin,Li Jishen,Miao Fan,Tang Shaowei,Cao Sheng,Yang Hao,Shan Jianqiang 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3

Deformed fuel rods can cause a partial blockage of the flow area in a subchannel. Such flow blockage will influence the core coolant flow and further the core heat transfer during the reflooding phase and subsequent severe accidents. Nevertheless, most of the system analysis codes simulate the accident process based on the assumed flow blockage ratio, resulting in inconsistencies between simulated results and actual conditions. This paper aims to study the influence of flow blockage in severe accident scenario of the CAP1400 reactor. First, the flow blockage model of ISAA code is improved based on the FRTMB module. Then, the ISAA-FRTMB coupling system is adopted to model and calculate the QUENCH-LOCA- 0 experiment. The correctness and validity of the flow blockage model are verified by comparing the peak cladding temperature. Finally, the DVI Line-SBLOCA accident is induced to analyze the influence of flow blockage on subsequent CAP1400 reactor core heat transfer and core degradation. From the results of the DVI Line-SBLOCA accident analysis, it can be concluded that the blockage ratio is in the range of 40%e60%, and the position of severe blockage is the same as that of cladding rupture. The blockage reduces the circulation area of the core coolant, which in turn impacts the heat exchange between the core and the coolant, leading to the early failure and collapse of some core assemblies and accelerating the core degradation process.

A serine/threonine phosphatase 1 of Streptococcus suis type 2 is an important virulence factor

Lihua Fang,Jingjing Zhou,Pengcheng Fan,Yunkai Yang,Hongxia Shen,Weihuan Fang 대한수의학회 2017 Journal of Veterinary Science Vol.18 No.4

Streptococcus suis is regarded as one of the major pathogens of pigs, and Streptococcus suis type 2 (SS2) is considered a zoonotic bacterium based on its ability to cause meningitis and streptococcal toxic shock-like syndrome in humans. Many bacterial species contain genes encoding serine/threonine protein phosphatases (STPs) responsible for dephosphorylation of their substrates in a single reaction step. This study investigated the role of stp1 in the pathogenesis of SS2. An isogenic stp1 mutant (stp1) was constructed from SS2 strain ZJ081101. The stp1 mutant exhibited a significant increase in adhesion to HEp-2 and bEnd.3 cells as well as increased survival in RAW264.7 cells, as compared to the parent strain. Increased survival in macrophage cells might be related to resistance to reactive oxygen species since the stp1 mutant was more resistant than its parent strain to paraquat-induced oxidative stress. However, compared to parent strain virulence, deletion of stp1 significantly attenuated virulence of SS2 in mice, as shown by the nearly double lethal dose 50 value and the lower bacterial load in organs and blood in the murine model. We conclude that Stp1 has an essential role in SS2 virulence.

Improvement and validation of aerosol models for natural deposition mechanism in reactor containment

Jishen Li,Bin Zhang,Pengcheng Gao,Fan Miao,Jianqiang Shan Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.7

Nuclear safety is the lifeline for the development and application of nuclear energy. In severe accidents of pressurized water reactor (PWR), aerosols, as the main carrier of fission products, are suspended in the containment vessel, posing a potential threat of radioactive contamination caused by leakage into the environment. The gas-phase aerosols suspended in the containment will settle onto the wall or sump water through the natural deposition mechanism, thereby reducing atmospheric radioactivity. Aiming at the low accuracy of the aerosol model in the ISAA code, this paper improves the natural deposition model of aerosol in the containment. The aerosol dynamic shape factor was introduced to correct the natural deposition rate of non-spherical aerosols. Moreover, the gravity, Brownian diffusion, thermophoresis and diffusiophoresis deposition models were improved. In addition, ABCOVE, AHMED and LACE experiments were selected to validate and evaluate the improved ISAA code. According to the calculation results, the improved model can more accurately simulate the peak aerosol mass and respond to the influence of the containment pressure and temperature on the natural deposition rate of aerosols. At the same time, it can significantly improve the calculation accuracy of the residual mass of aerosols in the containment. The performance of improved ISAA can meet the requirements for analyzing the natural deposition behavior of aerosol in containment of advanced PWRs in severe accident. In the future, further optimization will be made to address the problems found in the current aerosol model.

Toward Understanding the Adsorption And Inhibition Mechanism of Cu‑MBTA Passivation Film on Copper Surface: A Combined Experimental and DFT Investigation

Mengrui Liu,Da Yin,Baimei Tan,Fan Yang,Xiaoqin Sun,Pengcheng Gao,Shihao Zhang,Yazhen Wang 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.1

The adsorption and passivation reactions of 5-methyl benzotriazole (MBTA) with different copper samples (as received, citricacid treated and citric acid and KIO4treated) were studied. The experiments were characterized by contact angle measurement,potentiodynamic polarization curve, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The results showed that the adsorption behavior of MBTA on different treated surfaces was different and MBTA was preferentiallyadsorbed on the surface of citric acid treated copper. Based on the density functional theory, quantum chemicaldescriptors such as the frontier molecular orbital energies EHOMO,ELUMOand the energy gap between them, molecularelectrostatic potential, and Fukui function had been calculated and discussed. The adsorption mechanism of MBTA andcopper surface was further revealed, which had positive significance for the corrosion inhibition of copper surface in copperinterconnection CMP.

Effects of modified-BHI medium on the growth and metabolites of Akkermansia muciniphila

Qinren Zhang,Yupan Zhou,Qianzu He,Haiyan Zhao,Fan Zhou,Pengcheng Chi,Quanyang Li 한국식품과학회 2024 Food Science and Biotechnology Vol.33 No.8

Akkermansia muciniphila (Akk) has recently become popular due to its therapeutic effect on various diseases. However, Akk’s high-density cultivation is difficult due to its anaerobic characteristics. Therefore, Akk was cultured with modified brain–heart infusion (M-BHI) to reach 1011 CFU/mL. 1H-NMR determined the metabolites of Akk and validated them by an amino acid analyzer. Compared to the BHI, Akk significantly up-regulated lactate, histidine, fumaric acid, cytidine, threonine, arginine, and hydroxyproline in the M-BHI and significantly down-regulated methionine, trimethylamine, and sarcosine. Regarding pathway enrichment analysis, histidine metabolism, arginine and proline metabolism, cysteine and methionine metabolism mainly regulate differential metabolites. In addition, M-BHI alters the metabolic profile by affecting Akk’s involvement in amino acid metabolism remodeling. Changed metabolites showed that Akk fermentation in M-BHI may play a physiological role in regulating immune homeostasis and reducing risk factors related to diseases. Therefore, M-BHI provides a promising reference for Akk cultivation in future industrial preparation.