Biomechanics and Biotransport Commons^™

Bending Energy Schemes For Discrete-Spring-Network Structural Modelling Of Red Blood Cells, Osayomwanbor Ehi-Egharevba, Mingzhu Chen, Fergal Boyle

Articles

Red blood cells (RBCs) undergo large structural deformation, including bending, when passing through capillaries. They also exhibit a range of complex shapes such as stomatocytes, discocytes and echinocytes that form due to altered blood pH and salt levels, ingested drugs and adenosine triphosphate depletion. Discrete-spring-network structural models of RBCs employ different numerical treatments of the continuum bending energy. This affects bending accuracy and the prediction of accurate RBC shapes. This research compares three representations called bending energy scheme (BES) A, B and C to evaluate their accuracy in shape predictions. BES A, seen throughout the literature, is based on the …

An Investigation Of The Effect Of Cyclic Loading Of Bone On Osteocyte Processes Spanning Micro-Cracks As A Driver Of Targeted Remodelling Of Bone, Morgana Pires Afonso Shirsath

Doctoral

Bone remodelling is essential to maintain and improve the quality of bones. This occurs with the action of specialised cells - osteoclasts and osteoblasts - which replace the old bone tissue with new in regions where damage has occurred. Osteocytes are responsible for signalling the presence of damage and trigger the bone remodelling response. According to the Scissors Model, the presence of micro-cracks causes rupture of the osteocyte processes by fatigue because of the repeated stretching resulting from the relative movement of micro-crack faces, when bone is subjected to cyclic loads.

Morton-Ordered Gpu Lattice Boltzmann Cfd Simulations With Application To Blood Flow, Gerald Gallagher, Fergal J. Boyle

Conference Papers

Computational fluid dynamics (CFD) is routinely used for numerically predicting cardiovascular-system medical device fluid flows. Most CFD simulations ignore the suspended cellular phases of blood due to computational constraints, which negatively affects simulation accuracy. A graphics processing unit (GPU) lattice Boltzmann-immersed boundary (LB-IB) CFD software package capable of accurately modelling blood flow is in development by the authors, focusing on the behaviour of plasma and stomatocyte, discocyte and echinocyte red blood cells during flow. Optimised memory ordering and layout schemes yield significant efficiency improvements for LB GPU simulations. In this work, comparisons of row-major-ordered Structure of Arrays (SoA) and Collected …

Finite Element Simulation Of Head Impacts In Mixed Martial Arts, Stephen Tiernan, Aidan Meagher, David O'Sullivan Dr, Eoin O'Kelly Dr

Articles

This study determined brain stress and strain in an unhelmeted sport and correlated this with concussive injuries. Thirteen MMA athletes were fitted with the MiG2.0 Stanford instrumented mouthguard. The mouthguard records linear acceleration and angular velocity in 6 degrees of freedom. Angular acceleration was calculated by differentiation. All events were video recorded, time stamped and reported impacts confirmed. 298 impacts above 10g were recorded during sparring sessions and 153 impacts in competitive events. The competitive events resulted in five concussions which were diagnosed by a medical doctor. The impact with the highest angular acceleration from each sparring session and competitive …

An Enhanced Spring-Particle Model For Red Blood Cell Structural Mechanics: Application To The Stomatocyte–Discocyte– Echinocyte Transformation, Mingzhu Chen, Fergal Boyle

Articles

Red blood cells (RBCs) are the most abundant cellular element suspended in blood. Together with the usual biconcave-shaped RBCs, i.e., discocytes, unusual-shaped RBCs are also observed under physiological and experimental conditions, e.g., stomatocytes and echinocytes. Stomatocytes and echinocytes are formed from discocytes and in addition can revert back to being discocytes; this shape change is known as the stomatocyte–discocyte–echinocyte (SDE) transformation. To-date, limited research has been conducted on the numerical prediction of the full SDE transformation. Spring- particle RBC (SP-RBC) models are commonly used to numerically predict RBC mechanics and rheology. However, these models are incapable of predicting the full …

An Engineering Evaluation Of Ankle Prosthetics, Christopher Thian, Stephen Tiernan, Fiona Mcevoy, Robert Flavin

Conference Papers

There are a wide range of different types of ankle replacements on the market today each with a
different mechanical design. Unfortunately the results of ankle replacements are not as good as hip
and knee replacements; this is due to the complexity of the ankle joint. In the early days of ankle
replacements some of the prosthetics only lasted 4 months. Recent developments have improved the
longevity of the replacements although, there are still many complications and failures of the
replacements, these include; the prosthetic components migrating into the bone, the components
failing due to stresses induced by the forces …

The Effect Of Physiological Cyclic Stretch On The Cell Morphology, Cell Orientation And Protein Expression Of Endothelial Cells, V. Barron, Claire Brougham, K. Coghlan, C. Stenson-Cox, D. O'Mahoney, P.E. Mchugh

Articles

In vivo, endothelial cells are constantly exposed to pulsatile shear and tensile stresses. The main aim of this study was to design and build a physiological simulator, which reproduced homogenous strain profiles of the tensile strain experienced in vivo, and to investigate the effect of this cyclic tensile strain on the cell morphology, cell orientation and protein expression of endothelial cells. The biological response of human umbilical vein endothelial cells to a uniaxial cyclic stretch, in this newly developed simulator, was examined experimentally using immunohistostaining and confocal imaging and it was

found that the cells elongated and oriented at 58.9± …

Mechano-Biological Interactions Of Endothelial Cells, Claire Brougham, Karen Coughlan, Valerie Barron, Peter Mchugh

Conference Papers

Atherosclerosis is an ever-increasing cause of morbidity in the western world. Current surgical treatments include bypass grafts and coronary artery stents. However, there is still a need for alternative approaches especially for those who cannot receive conventional therapy. Tissue engineering is one such approach that may hold the key to the repair and regeneration. Tissue engineering is one such approach that may hold the key to the repair and regeneration of coronary arteries. Nevertheless, many questions need to be answered before a vialbe vascular tissie with the inherent properties of native tissue becomes a real contender with the surgical therapies …