http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Jianpeng Sun,Zihan Tan,Jiaju Zhang,Wenwu Sun,Li Zhu 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.2
The spatial Y-shaped tied arch bridge is a rare form of innovative bridge on arch bridges around the world. It has important reference significance for the design and construction of bridge engineering worldwide. This arch bridge is novel in design and adopts single and double arch ribs combined structure. However, as a novel bridge type, its force situation is indetermination, so it is very important to study its mechanical properties and parameter sensitivity. In order to study the mechanical properties of the spatial Y-shaped tied arch bridge and the influence of structural parameters, this paper takes a spatial Y-shaped tied arch bridge under construction in China as the research object. The finite element software MIDAS Civil is used to establish the bridge model. The finite element model is used to analyze the static and dynamic performance of the spatial Y-shaped tied arch bridge under the use stage and the mechanical change trend under the influence of different rise-span ratios and double arch bifurcation angles. The results of single arch rib and double arch rib under constant load and live load are compared under different structural parameters in this paper, and the parameter sensitivity analysis of statics and dynamics is carried out. These analyses provide the adjustment basis and design reference for the design of the special-shaped arch bridge in the future.
Exosomes derived from miR-214-3p overexpressing mesenchymal stem cells promote myocardial repair
Wenwu Zhu,Qingjie Wang,Jian Zhang,Ling Sun,Xiu Hong,Wei Du,Rui Duan,Jianguang Jiang,Yuan Ji,Haoran Wang,Bing Han 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00
Aims Exosomes are known as nanovesicles that are naturally secreted, playing an essential role in stem-mediated cardioprotection. This study mainly focused on investigating if exosomes derived from miR-214 overexpressing mesenchymal stem cells (MSCs) show more valid cardioprotective ability in a rat model of acute myocardial infarction (AMI) and its potential mechanisms. Methods Exosomes were isolated from control MSCs (Ctrl-Exo) and miR-214 overexpressing MSCs (miR-214OE-Exo) and then they were delivered to cardiomyocytes and endothelial cells in vitro under hypoxia and serum deprivation (H/SD) condition or in vivo in an acutely infarcted Sprague-Dawley rat heart. Regulated genes and signal pathways by miR-214OE-Exo treatment were explored using western blot analysis and luciferase assay. Results in vitro , miR-214OE-Exo enhanced migration, tube-like formation in endothelial cells. In addition, miR-214OE-Exo ameliorated the survival of cardiomyocytes under H/SD. In the rat AMI model, compared to Ctrl-Exo, miR-214OE-Exo reduced myocardial apoptosis, and therefore reduced infarct size and improved cardiac function. Besides, miR-214OE-Exo accelerated angiogenesis in peri-infarct region. Mechanistically, we identified that exosomal miR-214-3p promoted cardiac repair via targeting PTEN and activating p-AKT signal pathway. Conclusion Exosomes derived from miR-214 overexpressing MSCs have greatly strengthened the therapeutic efficacy for treatment of AMI by promoting cardiomyocyte survival and endothelial cell function.
Repair Decision Based on Sensitivity Analysis for Aero-Engine Assembly
Yanhui Sun,Junkang Guo,Jun Hong,Guanghui Liu,Wenwu Wu,Cong Yue 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.3
Strict requirements for concentricity of the multistage high pressure rotor of an aero-engine are employed to guarantee performances such as vibration. Tedious and time-wasting trial assembly by adjusting the installation angles of stages is needed to meet the requirements due to the lack of effective analysis methods. Furthermore, there is no quick way to find out where the problem is and how to repair the parts when the installation-angle-adjusting method fails. This article focuses on a solution to optimize the installation angle of each stage and to make repair decisions in the assembly process. The run-out data are processed by least square method to get the spatial positions and attitudes of flanges and a deviation propagation analysis model is built by virtue of homogeneous coordinate transformation theory to predict the accumulative errors of each stage. The eccentricities of stages are evaluated with reference to the common axis and the installation angles of stages are optimized by minimizing the sum of eccentricities. Sensitivities of eccentricity, eccentric angle and parallelism of each stage are analyzed and repair decisions for parts are made to meet more strict requirements. An example of a three-stage subassembly is presented to demonstrate the solution.