In Situ Synthesis of Ti3+ Self-Doped TiO2/N-Doped Carbon Nanocomposites and its Visible Light Photocatalytic Performance

Chaoyi Wu,Zhenggang Gao,Shanmin Gao,Qingyao Wang,Zeyan Wang,Baibiao Huang,Ying Dai 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.8

Ti3+ self-doped TiO2 (TiO2-x)/N-doped carbon nanostructure composites were prepared via a facile one-step hydrothermal method to optimize the use of visible light and reduce recombination of photogenerated electrons and holes. The composites were characterized by X-ray diffraction, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy. The amounts of carbon and nitrogen sources affect the morphology and photocatalytic performance. At low amounts of the sources, the Ndoped carbon nanostructure is an amorphous film and is well-combined with TiO2-x nanoparticles through surface carbon–oxygen groups. At high amounts of the sources, N-doped carbon quantum dots (NCQDs) were obtained, and carbon atoms could substitute for oxygen atoms in the TiO2 lattice to form Ti–C structures, which are responsible for the high photocatalytic activity under visible light illumination. Transient photocurrent response and electrochemical impedance spectroscopy results indicate that the amorphous hybrid film becomes a trap for electrons and that NCQDs can accelerate electron transfer. The improved visible light photocatalytic property for the TiO2-x/NCQDs composite can be attributed to the enhancement of light absorption and inhibition of the photogenerated electron–hole recombination of anchored NCQDs.

Dynamic analysis of high-speed railway train-bridge system after barge collision

Chaoyi Xia,Qin Ma,Fudong Song,Xuan Wu,He Xia 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.1

In this paper, a framework is proposed for dynamic analysis of train-bridge systems with a damaged pier after barge collision. In simulating the barge-pier collision, the concrete pier is considered to be nonlinear-inelastic, and the barge-bow is modeled as elastic-plastic. The changes of dynamic properties and deformation of the damaged pier, and the additional unevenness of the track induced by the change of deck profile, are analyzed. The dynamic analysis model for train-bridge coupling system with a damaged pier is established. Based on the framework, an illustrative case study is carried out with a 5×32 m simply-supported PC box-girder bridge and the ICE3 high-speed train, to investigate the dynamic response of the bridge with a damaged pier after barge collision and its influence on the running safety of high-speed train. The results show that after collision by the barge, the vibration properties of the pier and the deck profile of bridge are changed, forming an additional unevenness of the track, by which the dynamic responses of the bridge and the car-body accelerations of the train are increased, and the running safety of high-speed train is affected.

Vibration analysis of train-bridge system with a damaged pier by flotilla collision and running safety of high-speed train

Chaoyi Xia,Kunpeng Wang,Jiacheng Huang,He Xia,Lin Qi,Xuan Wu 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.81 No.1

The dynamic responses of a pier-pile-soil system subjected to a barge/flotilla collision are analyzed. A coupled highspeed train and bridge system with a damaged pier after barge/flotilla collision is established by taking the additional unevenness of the track induced by the damaged pier as the self-excitation of the system. The whole process of a CRH2 high-speed train running on the 6×32 m simply-supported PC (prestressed concrete) box-girder bridge with a damaged pier is simulated as a case study. The results show that the lateral displacements and accelerations of the bridge with a damaged pier are much greater than the ones before the collision. The running safety indices of the train increase with the train speed as well as with the number of barges in the flotilla. In flotilla collision, the lateral wheel/rail forces of the train exceed the allowable values at a certain speed, which influences the running safety of the trains.

Dynamic analysis of high-speed railway train-bridge system after barge collision

Xia, Chaoyi,Ma, Qin,Song, Fudong,Wu, Xuan,Xia, He Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.1

In this paper, a framework is proposed for dynamic analysis of train-bridge systems with a damaged pier after barge collision. In simulating the barge-pier collision, the concrete pier is considered to be nonlinear-inelastic, and the barge-bow is modeled as elastic-plastic. The changes of dynamic properties and deformation of the damaged pier, and the additional unevenness of the track induced by the change of deck profile, are analyzed. The dynamic analysis model for train-bridge coupling system with a damaged pier is established. Based on the framework, an illustrative case study is carried out with a $5{\times}32m$ simply-supported PC box-girder bridge and the ICE3 high-speed train, to investigate the dynamic response of the bridge with a damaged pier after barge collision and its influence on the running safety of high-speed train. The results show that after collision by the barge, the vibration properties of the pier and the deck profile of bridge are changed, forming an additional unevenness of the track, by which the dynamic responses of the bridge and the car-body accelerations of the train are increased, and the running safety of high-speed train is affected.

Isolation of Dibutyl Phthalate-Degrading Bacteria and Its Coculture with Citrobacter freundii CD-9 to Degrade Fenvalerate

( Min Wu Jie Tang ),( Xuerui Zhou ),( Dan Lei ),( Chaoyi Zeng ),( Hong Ye Ting Cai ),( Qing Zhang ) 한국미생물 · 생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.2

Continued fenvalerate use has caused serious environmental pollution and requires large-scale remediation. Dibutyl phthalate (DBP) was discovered in fenvalerate metabolites degraded by Citrobacter freundii CD-9. Coculturing is an effective method for bioremediation, but few studies have analyzed the degradation pathways and potential mechanisms of cocultures. Here, a DBPdegrading strain (BDBP 071) was isolated from soil contaminated with pyrethroid pesticides (PPs) and identified as Stenotrophomonas acidaminiphila. The optimum conditions for DBP degradation were determined by response surface methodology (RSM) analysis to be 30.9 mg/l DBP concentration, pH 7.5, at a culture temperature of 37.2℃. Under the optimized conditions, approximately 88% of DBP was degraded within 48 h and five metabolites were detected. Coculturing C. freundii CD-9 and S. acidaminiphila BDBP 071 promoted fenvalerate degradation. When CD-9 was cultured for 16 h before adding BDBP 071, the strain inoculation ratio was 5:5 (v/v), fenvalerate concentration was 75.0 mg/l, fenvalerate was degraded to 84.37 ± 1.25%, and DBP level was reduced by 5.21 mg/l. In addition, 12 fenvalerate metabolites were identified and a pathway for fenvalerate degradation by the cocultured strains was proposed. These results provide theoretical data for further exploration of the mechanisms used by this coculture system to degrade fenvalerate and DBP, and also offer a promising method for effective bioremediation of PPs and their related metabolites in polluted environments.

A framework for carrying out train safety evaluation and vibration analysis of a trussed-arch bridge subjected to vessel collision

He Xia,Chaoyi Xia,Nan Zhang,Qin Ma,Xuan Wu 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.59 No.4

Safety is the prime concern for a high-speed railway bridge, especially when it is subjected to a collision. In this paper, an analysis framework for the dynamic responses of train-bridge systems under collision load is established. A multi-body dynamics model is employed to represent the moving vehicle, the modal decomposition method is adopted to describe the bridge structure, and the time history of a collision load is used as the external load on the train-bridge system. A (180+216+180) m continuous steel trussedarch bridge is considered as an illustrative case study. With the vessel collision acting on the pier, the displacements and accelerations at the pier-top and the mid-span of the bridge are calculated when a CRH2 high-speed train running through the bridge, and the influence of bridge vibration on the running safety indices of the train, including derailment factors, offload factors and lateral wheel/rail forces, are analyzed. The results demonstrate that under the vessel collision load, the dynamic responses of the bridge are greatly enlarged, threatening the running safety of high-speed train on the bridge, which is affected by both the collision intensity and the train speed.