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Effect of topography parameters on cellular morphology during guided cell migration on a graded micropillar Surface

Krishnamoorthy Srikumar, Xu Heqi, Zhang Zhengyi, Xu Changxue

Acta of Bioengineering and Biomechanics

2021

Vol. 23, no. 2

147--157

Purpose: Guided cell migration refers to the engineering of local cell environment to specifically direct cell migration and has important applications such as utilization in cell sorting and wound healing assays. Graded micropillar surfaces have been utilized for achieving guided cell migration. Topographic parameters such as micropillar diameter and spacing gradient may have effects on the morphology of attached cells. It is critical to understand this interaction between the cells and the underlying microscale structures. Methods: In this study, a graded micropillar substrate has been fabricated to investigate the effects of the microtopography on the cell morphology in terms of the cell aspect ratio and cell circularity. Results: It is found that 1) with the increase of the micropillar diameter, the cell aspect ratio has no significance change. At the small spacing gradients, the aspect ratio is smaller than that at the large spacing gradients; 2) statistical analysis shows both the micropillar diameter and spacing gradient have no significant effect on the cell aspect ratio compared to the flat surface; 3) the cell circularity at the small micropillar diameters is higher than that at the large micropillar diameters. The cell circularity at the micropillar gradient of 0.1 µm is higher than those at the other micropillar gradients; 4) three microtopographic conditions are considered to have statistically significant effect on the cell circularity compared to the flat surface, including the micropillar diameters of 5 µm and 10 µm and the spacing gradient of 0.1 µm.

Investigations on mechanical properties and microtopography of electromagnetic self-piercing riveted joints with carbon fiber reinforced plastics/aluminum alloy 5052

Liang Jusong, Jiang Hao, Zhang Jinsheng, Wu Xianhe, Zhang Xu, Li Guangyao, Cui Junjia

Archives of Civil and Mechanical Engineering

2019

Vol. 19, no. 1

240--250

In this paper, the mechanical properties of electromagnetic self-piercing riveted (E-SPR) joints with carbon fiber reinforced plastics (CFRP)/aluminum alloy (Al) 5052 were comprehensively investigated. Microtopography observations, hardness measurements and tensile-shear strength tests were performed by comparing with regular pressure self-piercing riveted (P-SPR) joints. Results showed that the undercut value of E-SPR joints was higher than that of P-SPR joints. The hardness values on rivet legs of E-SPR joints were larger and almost no difference on rivet heads between the E-SPR and P-SPR. In addition, it was found that mechanical properties of E-SPR joints were higher than that of P-SPR joints. The shear fracture appearance indicated that E-SPR joints with higher undercut were more difficult to rupture in the bottom of Al sheet.

Analysis of worn surfaces by a slicing method

Czifra A., Varadi K., Palasti Kovacs B.

International Journal of Applied Mechanics and Engineering

2004

Vol. 9, no spec.

193-198

An algorithm has been developed to characterize the surface microtopography by the analysis of the asperities. The slicing method developed defines as asperities any continuous sets of points located above the slicing plane. Distribution functions were used for characterizing the surface and the asperities and the orientation of the asperities together with their peak angle, peak radius, as well as the ratio of major and minor axes. Our tests were intended to analyze wear processes at the surface by characterizing surface microtopography. In the course of the work, we performed tests of two surfaces generated in the course of dry sliding friction. The method developed properly characterizes worn surfaces and conclusions can be drawn to the contact and wear behavior of the surface by the analysis of microtopography.