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Chen Kaiqi,Xu Mimi,Lu Feng,He Yunfan 한국조직공학과 재생의학회 2023 조직공학과 재생의학 Vol.20 No.5
Extracellular matrix (ECM) components confer biomechanical properties, maintain cell phenotype and mediate tissue homeostasis. ECM remodeling is complex and plays a key role in both physiological and pathological processes. Matrix metalloproteinases (MMPs) are a group of enzymes responsible for ECM degradation and have been accepted as a key regulator in ECM remodeling. In this mini-review, we summarize MMPs categories, functions and the targeted substrates. We then discuss current understanding of the role of MMPs-mediated events, including inflammation reaction, angiogenesis, cellular activities, etc., in ECM remodeling in the context of regenerative medicine.
Shear Performance of Short Channel Connectors in a Steel-UHPC Composite Deck
Qiu Zhao,Yang Du,Yunfan Peng,Chen Xu,Guanming Huang 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.1
The steel-ultra high performance concrete (UHPC) composite deck has been increasingly concerned for the fatigue damage ameliorations on the steel bridge deck and the pavement. The UHPC plate in the composite deck featured by the favorable tensile performance and small thickness helps achieving a light self-weight. However, it results to a limited short space for the shear connector to transfer the interlayer shear force. Therefore, this study proposed a kind of short steel channel-section connector for the composite deck with a thin UHPC plate, and investigated its mechanical behavior through push-out tests and parametric FEM analysis. The test results showed the deformation of the channel connector during the loading process generally included the elastic, elastic–plastic, and plastic stages, and the shear fracture of channel connector dominated in the failure mode. The shear stiff ness of the specimen with embedded reinforcement was increased by 39%, but had little infl uence on the shear capacity. On the other side, the parametric analysis told that the shear strength of connector increased signifi cantly as the connector height increased from 50 to 80 mm. Nevertheless, the connector arrangement direction was a sensitive factor to the uplift resistance of the connector.
Qiu Zhao,Guanming Huang,Chen Xu,Yunfan Peng 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.7
A steel-ultra high performance concrete (UHPC) composite deck has good fatigue performancewhile the thin UHPC slab leaves a very limited space for the connector configuration. This is actually crucial to achieve the composite action. Current literatures concerning the short stud behavior are still limited for a general mechanism understanding. Therefore, a series of push-tests containing 15 specimens were conducted for investigating the mechanical behavior of short studs with various diameters and lengths in UHPC composite deck. And a parametric FEM analysis with nonlinear material constitutions was conducted as well for the bearing performance understanding. The push-out tests showed the shear fracture near stud roots is the leading dominant failure mode, and a longer stud length might introduce a higher percentage of stud shank bending deformation. It explained longer stud length could be helpful to improve the shear strength of stud in UHPC. Meanwhile, the shear stiffness of the push-out specimens were all increased with a larger stud diameter or length. On the other side, the analysis results showed that a pull-out failure could happen when the stud length was less than 25 mm in UHPC and the failure mode of stud could also be affected by the concrete strength. In addition to the tests and analysis, the safety redundancies of strength evaluations of short stud in UHPC based on several civil codes were discussed in terms of the comparison works.
Yun Fan,Xuan Tang,Shaohan Wang,Bin Chen 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10
Various sets of heat treatments are applied on 7075 alloy in this study in order to reduce the treatment time and yet stillachieve the similar mechanical property as the traditional T6 tempered alloy. The main parameters like solid solution treatmenttime, single aging temperature, as well as first aging duration in double aging treatment, first aging temperature andsecond aging temperature are studied and valued by hardness test. The double aging treatment at 125 °C for 60 min andthen at 165 °C for 130 min is compared with traditional single aging treatment by using advanced Cs-corrected high-angleannular dark field scanning-transmission electron microscopy (HAADF-STEM). The precipitates and dispersoids found inthose two corresponding samples are mainly Cr-containing large dispersoids, a few η particles and large quantity of fineprecipitates like η′. The similarity of precipitates in them can well support the approximate hardness level of the doubleaged and single aged samples.