Three-Dimensional Hierarchically Ternary Iron Tungsten Nitride Nanosheets with Slight Ratio of Nickel Modulation for Oxygen Evolution Reaction

Xuyang Zhang,Hangjia Shen,Babak Rezaei Moghadam,Siqi Liu,Yuejin Zhu,Jiacheng Wang,Minghui Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.7

Practical application of oxygen evolution reaction (OER) in energy conversion devices, such as water splitting and metal-air batteries, relies on the development of highly efficient and stable electrocatalysts and is still challengeable. Here, Nickel modulated ternary Iron tungsten nitride (Ni-FeWN2) nanosheets are synthesized through a facile hydrothermal growth method and subsequently nitriding process for boosting OER. A potential of 1.57V at the current density of 10 mA/cm2 and Tafel slope (40 mV/dec) are achieved on Ni-FeWN2, much lower than that on Ni-free FeWN2 and commercial IrO2. More importantly, Ni-FeWN2 nanosheets display high stability and electrocatalytic activity toward driving oxygen evolution efficiently in alkaline media.

Designing method for fire safety of steel box bridge girders

Xuyang Li,Gang Zhang,Venkatesh Kodur,Shuanhai He,Qiao Huang 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.6

This paper presents a designing method for enhancing fire resistance of steel box bridge girders (closed steel box bridge girder supporting a thin concrete slab) through taking into account such parameters namely; fire severity, type of longitudinal stiffeners (I, L, and T shaped), and number of longitudinal stiffeners. A validated 3-D finite element model, developed through the computer program ANSYS, is utilized to go over the fire response of a typical steel box bridge girder using the transient thermo-structural analysis method. Results from the numerical analysis show that fire severity and type of longitudinal stiffeners welded on bottom flange have significant influence on fire resistance of steel box bridge girders. T shaped longitudinal stiffeners applied on bottom flange can highly prevent collapse of steel box bridge girders towards the end of fire exposure. Increase of longitudinal stiffeners on bottom flange and web can slightly enhance fire resistance of steel box bridge girders. Rate of deflection-based criterion can be reliable to evaluate fire resistance of steel box bridge girders in most fire exposure cases. Thus, T shaped longitudinal stiffeners on bottom flange incorporated into bridge fire-resistance design can significantly enhance fire resistance of steel box bridge girders.

Fire Performance of Continuous Steel-Concrete Composite Bridge Girders

Gang Zhang,Chaojie Song,Xuyang Li,Shuanhai He,Qiao Huang 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.3

This paper presents a detailed investigation in to fire resistance along with failure mode in continuous steel-concrete composite twin I-shaped bridge girders under different localized fire through considering fire severity and fire exposure positions namely; mid-span zone in one of the two span, hogging moment zone and side-support zone. A 3-D finite element (FE) model, built utilizing the computer program ANSYS, is used to track structural fire performance in a typical two span of continuous composite twin I-shaped bridge girders (fabricated with twin I-shaped plates supporting a concrete slab) dependent on thermo-mechanical coupled analysis. The model validation is undertook through comparison of temperature and deflection response attained from a scaled composite single I-shaped girder tested exposed to ISO834 fire. The numerical analysis results show that the developed model can be favorably used to analyze the behavior and failure mode of continuous steel-concrete composite twin I-shaped bridge girders during entire range of fire exposure. Fire severity and fire exposure positions present critical influence in to the fire resistance of continuous composite bridge girders. Fire exposure prevention on hogging moment zone can significantly extend failure time of continuous girders, and further hold back progressive structural collapse. Web buckling based failure criterion can be applicable to calculate fire resistance of realistic continuous girders under simultaneous structural loading together with localized fire. Continuous composite bridge girders subjected to localized fire present highly significant local deformation response in the fire exposed bridge girder span.

Theoretical and experimental investigation of the pressure ratio distribution and the regulation strategy of a two-stage turbocharging system for various altitudes operation

Huiyan Zhang,Xuyang Tang,Liansong Mu,Lei Shi,Kangyao Deng 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.3

Fixed two-stage turbocharging system matched at high altitude leads to engine performance deterioration at low altitudes due to unreasonable pressure ratio distribution between two stages. In this paper, a thermodynamic model of regulated two-stage turbocharging system is established. Theoretical analysis shows the pressure ratio distribution should lean towards a turbocharger with greater efficiency, and the high-altitude operation intensifies the role of HP stage. Experiments are conducted on an environment simulation test bench. Then, the optimal pressure ratio distribution and ETAR at various altitudes are proposed. Experiment results demonstrate that the turbocharging system boosts sufficient intake air with the optimal ETAR. Compared to that with the fixed turbocharging system, the maximum increment of the overall efficiency is 9.3 % at 0 m and attains 1.5 % at 3000 m. Consequently, the output torque is 100 % recovered below 3000 m, and it exceeds 91 % at 4500 m. Moreover, the optimal ETAR reduces the BSFC under low altitude conditions.

A Hydrogel-based First-Aid Tissue Adhesive with Effective Hemostasis and Anti-bacteria for Trauma Emergency Management

Dongjie Zhang,Li Mei,Yuanping Hao,Bingcheng Yi,Jilin Hu,Danyang Wang,Yaodong Zhao,Zhe Wang,Hailin Huang,Yongzhi Xu,Xuyang Deng,Cong Li,Xuewei Li,Qihui Zhou,Yun Lu 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Background Clinical tissue adhesives remain some critical drawbacks for managing emergency injuries, such as inadequate adhesive strength and insufficient anti-infection ability. Herein, a novel, self-healing, and antibacterial carboxymethyl chitosan/polyaldehyde dextran (CMCS/PD) hydrogel is designed as the first-aid tissue adhesive for effective trauma emergency management. Methods We examined the gel-forming time, porosity, self-healing, antibacterial properties, cytotoxicity, adhesive strength, and hemocompatibility. Liver hemorrhage, tail severance, and skin wound infection models of rats are constructed in vivo, respectively. Results Results demonstrate that the CMCS/PD hydrogel has the rapid gel-forming (~ 5 s), good self-healing, and effective antibacterial abilities, and could adhere to tissue firmly (adhesive strength of ~ 10 kPa and burst pressure of 327.5 mmHg) with excellent hemocompatibility and cytocompatibility. This suggests the great prospect of CMCS/ PD hydrogel in acting as a first-aid tissue adhesive for trauma emergency management. The CMCS/PD hydrogel is observed to not only achieve rapid hemostasis for curing liver hemorrhage and tail severance in comparison to commercial hemostatic gel (Surgiflo ®) but also exhibit superior anti-infection for treating acute skin trauma compared with clinical disinfectant gel (Prontosan ®). Conclusions Overall, the CMCS/PD hydrogel offers a promising candidate for first-aid tissue adhesives to manage the trauma emergency. Because of the rapid gel-forming time, it could also be applied as a liquid first-aid bandage for mini-invasive surgical treatment.

EFFECT OF Cu ATOMIC SEGREGATION ON THE FROZEN STRUCTURES OF Co–Cu BIMETALLIC CLUSTERS

YINGJIE ZHANG,YONGQIANG LI,XUYANG XIAO,YUNHUI YAN 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.6

Atomic segregation in bimetallic clusters can in°uence the surface constituent and be used to a®ect the frozen structure. In this study, molecular dynamics simulation with an embedded atom method was used to study the frozen structures of (CoCu)561 clusters with di®erent Co contents. It is found that the clusters can freeze to form icosahedron, truncated octahedron, decahedron or hcp with the change of Co contents. In these geometries, the structure of the lowest energy state is hcp, then in turn decahedron and truncated octahedron. The frozen structures are related to the release of excess energy, while the released excess energy was a®ected by the amount of segregated Cu atoms. This means that the atomic segregation can be used to tune the structures of bimetallic clusters.

Damage Inspection of Shell Structures Using a Technology of Ultrasonic Propagation Visualization Based on Laser Scanning Excitation

Liu, Yaolu,Zhang, Jun,Liu, Xuyang,Zhao, Youxuan,Hu, Ning The Korean Society for Nondestructive Testing 2018 한국비파괴검사학회지 Vol.38 No.3

In this work, a small pit on the internal surface of an aluminum thin-walled shell was inspected by using a technology of ultrasonic propagation visualization. This technology employs laser scanning within an inspection area to excite ultrasonic Lamb waves, and three cheap lead zirconate titanate (PZT) sensors to receive the wave signals. The laser scanning area and the three PZT sensors were located on the outside surface of the shell. Betti's reciprocal theorem was further incorporated into the present technology to visualize the wave propagation in the time-domain. The occurrence of notable scattering around the pit identified from the wave propagation snapshots at different time points can be used to detect the pit damage easily. We further adopted a method based on wave energy flow (WEF) map concept proposed by us to evaluate the size and shape of the pit. It was found that, even using a fast laser scanning of a step size of 8 mm, the present technology can still detect the damage quickly, and evaluate the damage accurately.

Damage Inspection of Shell Structures Using a Technology of Ultrasonic Propagation Visualization Based on Laser Scanning Excitation

Yaolu Liu,Jun Zhang,Xuyang Liu,Youxuan Zhao,Ning Hu 한국비파괴검사학회 2018 한국비파괴검사학회지 Vol.38 No.3

In this work, a small pit on the internal surface of an aluminum thin-walled shell was inspected by using a technology of ultrasonic propagation visualization. This technology employs laser scanning within an inspection area to excite ultrasonic Lamb waves, and three cheap lead zirconate titanate (PZT) sensors to receive the wave signals. The laser scanning area and the three PZT sensors were located on the outside surface of the shell. Betti’s reciprocal theorem was further incorporated into the present technology to visualize the wave propagation in the time-domain. The occurrence of notable scattering around the pit identified from the wave propagation snapshots at different time points can be used to detect the pit damage easily. We further adopted a method based on wave energy flow (WEF) map concept proposed by us to evaluate the size and shape of the pit. It was found that, even using a fast laser scanning of a step size of 8 mm, the present technology can still detect the damage quickly, and evaluate the damage accurately.