scholarly journals Investigation of cell nucleus heterogeneity

2020 ◽  
Author(s):  
Noel Reynolds ◽  
Eoin McEvoy ◽  
Soham Ghosh ◽  
Juan Alberto Panadero Pérez ◽  
Corey P. Neu ◽  
...  
Keyword(s):  
Cell Nucleus ◽  
Three Dimensional ◽  
Shear Stiffness ◽  
Osteoarthritic Cartilage ◽  
Heterogeneous Model ◽  
Shear Moduli ◽  
Dimensional Finite Element ◽  
And Migration ◽  
Heterogeneous Nucleus ◽  
Three Dimensional Finite Element

AbstractNucleus deformation has been shown to play a key role in cell mechanotransduction and migration. Therefore, it is of wide interest to accurately characterize nucleus mechanical behavior. In this study we present the first computational investigation of the in-situ deformation of a heterogeneous cell nucleus. A novel methodology is developed to accurately reconstruct a three-dimensional finite element spatially heterogeneous model of a cell nucleus from confocal microscopy z-stack images of nuclei stained for nucleus DNA. The relationship between spatially heterogeneous distributions microscopic imaging-derived greyscale values, shear stiffness and resultant shear strain is explored through the incorporation of the reconstructed heterogeneous nucleus into a model of a chondrocyte embedded in a PCM and cartilage ECM. Externally applied shear deformation of the ECM is simulated and computed intra-nuclear strain distributions are directly compared to corresponding experimentally measured distributions. Simulations suggest that the nucleus is highly heterogeneous in terms of its mechanical behaviour, with a sigmoidal relationship between experimentally measure greyscale values and corresponding local shear moduli (μn). Three distinct phases are identified within the nucleus: a low stiffness phase (0.17 kPa ≤ μn ≤ 0.63 kPa) corresponding to mRNA rich interchromatin regions; an intermediate stiffness phase (1.48 kPa ≤ μn ≤ 2.7 kPa) corresponding to euchromatin; a high stiffness phase (3.58 kPa ≤ μn ≤ 4.0 kPa) corresponding to heterochromatin. Our simulations indicate that disruption of the nucleus envelope associated with lamin-A/C depletion significantly increases nucleus strain in regions of low DNA concentration. A phenotypic shift of chondrocytes to fibroblast-like cells, a signature for osteoarthritic cartilage, results in a 35% increase in peak nucleus strain compared to control. The findings of this study may have broad implications for the current understanding of the role of nucleus deformation in cell mechanotransduction.

scholarly journals Influence of Surcharge Load on the Adjacent Pile Foundation in Coastal Floodplain

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Hao Zhang ◽  
Kai Sun
Keyword(s):  
Soft Soil ◽  
Three Dimensional ◽  
Bending Moment ◽  
Double Row ◽  
Pile Cap ◽  
Dimensional Finite Element ◽  
Surcharge Load ◽  
Soft Substratum ◽  
And Migration ◽  
Three Dimensional Finite Element

<p><strong> </strong>In this paper, in order to investigate the behavior of existing piles caused by the horizontal and compression deformation of soft substratum due to backfill surcharge on coastal floodplain, three-dimensional finite element models of piles adjacent to surcharge load were established. The deformation and migration law of soft soil was analyzed. The behavior of single pile and double row pile adjacent to surcharge load were studied, in which the influence of surcharge load location, surcharge pressure, pile stiffness, and pile top constraint conditions were considered. The results show that as the position of surcharge load is closer and the surcharge pressure increases, the response (e.g. deformation and bending moment) is more obvious. With the increase of pile stiffness, the range of passive load is increased. The deformation behavior of pile body under different constraints of pile cap is significantly different. The effect of secondary bending moment caused by pile axial force is obvious and cannot be ignored. If there is a thick soft substratum, it is beneficial to improve the behavior of adjacent piles by using cement mixing pile reinforcement.</p>

scholarly journals Numerical and Experimental Study on Modular-Based Timber Structures

2019 ◽  
pp. 471-478
Author(s):  
Sigurdur Ormarsson ◽  
Johan Vessby ◽  
Marie Johansson ◽  
Le Kua
Keyword(s):  
Three Dimensional ◽  
Shear Stiffness ◽  
Element Model ◽  
Structural Safety ◽  
Test Results ◽  
Structural Behaviour ◽  
Ongoing Research ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Connection Design

Building with prefabricated light-frame volume modules is a prevalent and innovative construction method for low and mid-rise timber buildings. Compared to traditionally site-built constructions this method is very advantageous due to its high prefabrication level and the fast on-site assembly of the modules. The focus of this project is to study and optimise the global shear stiffness of the volume modules and to secure a large enough shear and uplift stiffness of the mechanical (or friction based) connections between the modules. Some companies assume that the friction between the modules is sufficient to transfer the wind stabilization forces down through the entire building. Regarding structural safety, connection design is an important task that needs to be numerically studied and experimentally verified. The paper presents numerical and experimental results obtained from two ongoing research projects concerning modular-based timber buildings in Sweden. The final aim of this work is to develop an efficient three dimensional finite-element model to analyse both the global and detailed structural behaviour of these types of buildings. To study the overall shear stiffness of the volume modules, eight different test-modules are to be tested. The test results will be used to calibrate the numerical model.

Finite Element Analysis of Nonuniformity of Tires with Imperfections5

2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Force ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Force Variation ◽  
Three Dimensional Finite Element

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.

Tire Modeling by Finite Elements

1992 ◽  
Vol 20 (1) ◽  
pp. 33-56 ◽  
Author(s):  
L. O. Faria ◽  
J. T. Oden ◽  
B. Yavari ◽  
W. W. Tworzydlo ◽  
J. M. Bass ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Rolling Contact ◽  
Test Problems ◽  
State Behavior ◽  
Normal Contact ◽  
New Developments ◽  
Applied Torque ◽  
Dimensional Finite Element ◽  
Tire Modeling ◽  
Three Dimensional Finite Element

Abstract Recent advances in the development of a general three-dimensional finite element methodology for modeling large deformation steady state behavior of tire structures is presented. The new developments outlined here include the extension of the material modeling capabilities to include viscoelastic materials and a generalization of the formulation of the rolling contact problem to include special nonlinear constraints. These constraints include normal contact load, applied torque, and constant pressure-volume. Several new test problems and examples of tire analysis are presented.

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