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Computational and Experimental Approaches to Cellular and Subcellular Tracking at the Nanoscale
Published in Sarhan M. Musa, ®, 2018
Zeinab Al-Rekabi, Dominique Tremblay, Kristina Haase, Richard L. Leask, Andrew E. Pelling
In this section, we present an example of a MATLAB script for multiple particle tracking In the past, various techniques were used for this type of tracking such as cross-correlation of subsequent images (Gelles et al. 1988), two-dimensional Gaussian function fitting (Anderson et al. 1992), and brightness-weighed centroid (Ghosh and Webb 1994). Here, we present an example of particle tracking using the centroid method. This script was first written for marker tracking painted using a tissue dye on the endothelium of aortic tissues (Tremblay et al. 2010) (see Figure 9.4). This was employed to track the position of the markers and compute the tissue strain field during biaxial tensile testing. This script has been optimized for background with a uniform intensity profile and for tracking four markers or particles at the same time. It can be easily modified to compute centroid position of more than four markers or simply one single marker. The input file is a four-dimensional matrix from time-lapse image acquisition using the MATLAB acquisition toolbox. It corresponds to the variable “data(:, :, :, :).” The first two indexes refer to the pixel intensity for a given x−y position in the frame. The last index refers to the frame number of the acquisition.
Bioprinting of living aortic valve
Published in Ali Khademhosseini, Gulden Camci-Unal, 3D Bioprinting in Regenerative Engineering, 2018
D.Y. Cheung, S. Wu, B. Duan, J.T. Butcher
The aortic root wall encloses the leaflets and comprises a variety of entities crucial to the function of the organ (Charitos and Sievers 2013; Ho 2009). The sinuses of Valsalva are curved dilations occurring immediately anterior of each leaflet, making the root wall an inverted bulb shape. The left and right sinuses give rise to the left and right coronary arteries, respectively. The cusps are attached to the base of the root where they form a crown shape with the annulus, which is a fibrous ring that is considered a transition point between the ventricle and aortic root. The leaflets are joined together at commissural points, which are connected to the sinotubular junction, the distal ring portion of the sinuses. The histological composition of the aortic root, although not extensively studied, is similar to the ascending aorta and other large arteries, consisting of intimal, medial, and adventitial layers (Ho 2009; Butcher et al. 2011). The intimal and medial layers contain mainly of elastin, whereas the adventitial layer had higher levels of collagen (Iliopoulos et al. 2013; Azadani et al. 2012a, 2012b). Although similar in histology, the sinus displayed larger tissue stiffness in both the longitudinal and circumferential directions. In addition, the biaxial tensile testing showed no significant differences in stiffness between longitudinal and circumferential directions (approximately 3.5 MPa) (Azadani et al. 2012a). Overall, the entire root structure is stiffer than the leaflets.
Evaluating the tensile behaviour of rat myocardium across its three walls from biaxial tensile test data
Published in Alphose Zingoni, Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, 2022
H.M. Ngwangwa, M. Msibi, I. Mabuda, F. Nemavhola, T. Pandelani
Fifteen (N = 15) Wistar rats (200-250 g) aged between 8 and 10 weeks, were sacrificed in accordance with animal welfare regulations in South Africa. A total of 15 samples were harvested from the LV, SPT and RV and subjected to equi-biaxial tensile testing.
Deformation behavior of recrystallized and stress-relieved Zircaloy-4 fuel cladding under biaxial stress conditions
Published in Journal of Nuclear Science and Technology, 2018
Takeshi Mihara, Yutaka Udagawa, Masaki Amaya
Biaxial tensile testing facilitates the evaluation of mechanical properties under various biaxial stress conditions, especially for materials with anisotropic crystal structure and orientation. The cladding tube used in LWRs is made of Zirconium-based alloy, e.g. Zircaloy, which has the hexagonal close-packed (HCP) crystal structure, and the tube often has preferred distribution of crystallographic orientations. Since mechanical testing studies of Zircaloy sheets have revealed that the fracture strains of the sheets decrease with increasing a degree of biaxial stress condition, e.g. stress biaxiality [10,11], it is probable that the state of biaxial stress significantly influences the fracture limit of Zircaloy cladding tube.