The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Gerard B. Nash - One of the best experts on this subject based on the ideXlab platform.
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Disturbed flow promotes deposition of leucocytes from flowing whole blood in a model of a damaged vessel wall
British journal of haematology, 2004Co-Authors: Christopher A. Skilbeck, Peter G. Walker, Tim David, Gerard B. NashAbstract:Departure from simple laminar flow in arteries may promote the local attachment of leucocytes either to intact endothelium or platelet thrombi. We perfused blood through a chamber with a backward facing step, to observe whether adhesion from whole blood to P-selectin was indeed localized to a region of recirculating flow, and whether platelets binding to collagen in such a region could capture leucocytes. Blood flowing over the step established a stable vortex, a Reattachment Point where forward and backward flow separated, and a simple laminar flow with wall shear rate c. 400/s further downstream. Fluorescently labelled leucocytes were observed to attach to P-selectin immediately upstream or downstream of the Reattachment Point, and to roll back towards the step or away from it, respectively. There was negligible adhesion further downstream. When a P-selectin-Fc chimaera was used to coat the chamber, stable attachment occurred, again preferentially in the disturbed flow region. Numerous platelets adhered to a collagen coating throughout the chamber, although there were local maxima either side of the Reattachment Point. The adherent platelets captured flowing leucocytes in these regions alone. Leucocytes may adhere from flowing blood in vessels with high shear rate if the flow is disturbed. While platelets can adhere over a wider range of shear rates, their ability to capture leucocytes may be restricted to regions of disturbed flow.
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Population of the Vessel Wall by Leukocytes Binding to P-Selectin in a Model of Disturbed Arterial Flow
Arteriosclerosis thrombosis and vascular biology, 2001Co-Authors: Christopher A. Skilbeck, Susan M. Westwood, Peter G. Walker, Tim David, Gerard B. NashAbstract:We examined the hypothesis that disturbance of laminar flow promotes the attachment of leukocytes to the vessel wall in regions where the wall shear stress is otherwise too high. Isolated neutrophils, lymphocytes, or monocytes were perfused through chambers with backward-facing steps so that vortices occurred with well-defined Reattachment of flow. Wall shear stresses downstream in reestablished flow equaled 0.07 Pa (low shear) or 0.3 Pa (high shear). In chambers coated with P-selectin, adherent leukocytes rolled. By use of a P-selectin-Fc fragment chimera, adhesion was predominantly stationary, enabling definition of initial attachment sites. Neutrophils adhered in all regions of the low-shear chamber, with a local maximum around the Reattachment Point. However, in the high-shear chamber, adhesion was restricted to the recirculation zone and immediately downstream from the Reattachment Point. Rolling at high shear stress allowed a population of regions where initial attachment could not occur. At high shear, lymphocytes and monocytes also formed attachments restricted to the region of the Reattachment Point. The results imply that all types of leukocytes might bind to a capture receptor in high-shear vessels with discontinuities in the wall and might then spread to other regions.
Christopher A. Skilbeck - One of the best experts on this subject based on the ideXlab platform.
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Disturbed flow promotes deposition of leucocytes from flowing whole blood in a model of a damaged vessel wall
British journal of haematology, 2004Co-Authors: Christopher A. Skilbeck, Peter G. Walker, Tim David, Gerard B. NashAbstract:Departure from simple laminar flow in arteries may promote the local attachment of leucocytes either to intact endothelium or platelet thrombi. We perfused blood through a chamber with a backward facing step, to observe whether adhesion from whole blood to P-selectin was indeed localized to a region of recirculating flow, and whether platelets binding to collagen in such a region could capture leucocytes. Blood flowing over the step established a stable vortex, a Reattachment Point where forward and backward flow separated, and a simple laminar flow with wall shear rate c. 400/s further downstream. Fluorescently labelled leucocytes were observed to attach to P-selectin immediately upstream or downstream of the Reattachment Point, and to roll back towards the step or away from it, respectively. There was negligible adhesion further downstream. When a P-selectin-Fc chimaera was used to coat the chamber, stable attachment occurred, again preferentially in the disturbed flow region. Numerous platelets adhered to a collagen coating throughout the chamber, although there were local maxima either side of the Reattachment Point. The adherent platelets captured flowing leucocytes in these regions alone. Leucocytes may adhere from flowing blood in vessels with high shear rate if the flow is disturbed. While platelets can adhere over a wider range of shear rates, their ability to capture leucocytes may be restricted to regions of disturbed flow.
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Population of the Vessel Wall by Leukocytes Binding to P-Selectin in a Model of Disturbed Arterial Flow
Arteriosclerosis thrombosis and vascular biology, 2001Co-Authors: Christopher A. Skilbeck, Susan M. Westwood, Peter G. Walker, Tim David, Gerard B. NashAbstract:We examined the hypothesis that disturbance of laminar flow promotes the attachment of leukocytes to the vessel wall in regions where the wall shear stress is otherwise too high. Isolated neutrophils, lymphocytes, or monocytes were perfused through chambers with backward-facing steps so that vortices occurred with well-defined Reattachment of flow. Wall shear stresses downstream in reestablished flow equaled 0.07 Pa (low shear) or 0.3 Pa (high shear). In chambers coated with P-selectin, adherent leukocytes rolled. By use of a P-selectin-Fc fragment chimera, adhesion was predominantly stationary, enabling definition of initial attachment sites. Neutrophils adhered in all regions of the low-shear chamber, with a local maximum around the Reattachment Point. However, in the high-shear chamber, adhesion was restricted to the recirculation zone and immediately downstream from the Reattachment Point. Rolling at high shear stress allowed a population of regions where initial attachment could not occur. At high shear, lymphocytes and monocytes also formed attachments restricted to the region of the Reattachment Point. The results imply that all types of leukocytes might bind to a capture receptor in high-shear vessels with discontinuities in the wall and might then spread to other regions.
Tim David - One of the best experts on this subject based on the ideXlab platform.
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Disturbed flow promotes deposition of leucocytes from flowing whole blood in a model of a damaged vessel wall
British journal of haematology, 2004Co-Authors: Christopher A. Skilbeck, Peter G. Walker, Tim David, Gerard B. NashAbstract:Departure from simple laminar flow in arteries may promote the local attachment of leucocytes either to intact endothelium or platelet thrombi. We perfused blood through a chamber with a backward facing step, to observe whether adhesion from whole blood to P-selectin was indeed localized to a region of recirculating flow, and whether platelets binding to collagen in such a region could capture leucocytes. Blood flowing over the step established a stable vortex, a Reattachment Point where forward and backward flow separated, and a simple laminar flow with wall shear rate c. 400/s further downstream. Fluorescently labelled leucocytes were observed to attach to P-selectin immediately upstream or downstream of the Reattachment Point, and to roll back towards the step or away from it, respectively. There was negligible adhesion further downstream. When a P-selectin-Fc chimaera was used to coat the chamber, stable attachment occurred, again preferentially in the disturbed flow region. Numerous platelets adhered to a collagen coating throughout the chamber, although there were local maxima either side of the Reattachment Point. The adherent platelets captured flowing leucocytes in these regions alone. Leucocytes may adhere from flowing blood in vessels with high shear rate if the flow is disturbed. While platelets can adhere over a wider range of shear rates, their ability to capture leucocytes may be restricted to regions of disturbed flow.
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Population of the Vessel Wall by Leukocytes Binding to P-Selectin in a Model of Disturbed Arterial Flow
Arteriosclerosis thrombosis and vascular biology, 2001Co-Authors: Christopher A. Skilbeck, Susan M. Westwood, Peter G. Walker, Tim David, Gerard B. NashAbstract:We examined the hypothesis that disturbance of laminar flow promotes the attachment of leukocytes to the vessel wall in regions where the wall shear stress is otherwise too high. Isolated neutrophils, lymphocytes, or monocytes were perfused through chambers with backward-facing steps so that vortices occurred with well-defined Reattachment of flow. Wall shear stresses downstream in reestablished flow equaled 0.07 Pa (low shear) or 0.3 Pa (high shear). In chambers coated with P-selectin, adherent leukocytes rolled. By use of a P-selectin-Fc fragment chimera, adhesion was predominantly stationary, enabling definition of initial attachment sites. Neutrophils adhered in all regions of the low-shear chamber, with a local maximum around the Reattachment Point. However, in the high-shear chamber, adhesion was restricted to the recirculation zone and immediately downstream from the Reattachment Point. Rolling at high shear stress allowed a population of regions where initial attachment could not occur. At high shear, lymphocytes and monocytes also formed attachments restricted to the region of the Reattachment Point. The results imply that all types of leukocytes might bind to a capture receptor in high-shear vessels with discontinuities in the wall and might then spread to other regions.
Peter G. Walker - One of the best experts on this subject based on the ideXlab platform.
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Disturbed flow promotes deposition of leucocytes from flowing whole blood in a model of a damaged vessel wall
British journal of haematology, 2004Co-Authors: Christopher A. Skilbeck, Peter G. Walker, Tim David, Gerard B. NashAbstract:Departure from simple laminar flow in arteries may promote the local attachment of leucocytes either to intact endothelium or platelet thrombi. We perfused blood through a chamber with a backward facing step, to observe whether adhesion from whole blood to P-selectin was indeed localized to a region of recirculating flow, and whether platelets binding to collagen in such a region could capture leucocytes. Blood flowing over the step established a stable vortex, a Reattachment Point where forward and backward flow separated, and a simple laminar flow with wall shear rate c. 400/s further downstream. Fluorescently labelled leucocytes were observed to attach to P-selectin immediately upstream or downstream of the Reattachment Point, and to roll back towards the step or away from it, respectively. There was negligible adhesion further downstream. When a P-selectin-Fc chimaera was used to coat the chamber, stable attachment occurred, again preferentially in the disturbed flow region. Numerous platelets adhered to a collagen coating throughout the chamber, although there were local maxima either side of the Reattachment Point. The adherent platelets captured flowing leucocytes in these regions alone. Leucocytes may adhere from flowing blood in vessels with high shear rate if the flow is disturbed. While platelets can adhere over a wider range of shear rates, their ability to capture leucocytes may be restricted to regions of disturbed flow.
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Population of the Vessel Wall by Leukocytes Binding to P-Selectin in a Model of Disturbed Arterial Flow
Arteriosclerosis thrombosis and vascular biology, 2001Co-Authors: Christopher A. Skilbeck, Susan M. Westwood, Peter G. Walker, Tim David, Gerard B. NashAbstract:We examined the hypothesis that disturbance of laminar flow promotes the attachment of leukocytes to the vessel wall in regions where the wall shear stress is otherwise too high. Isolated neutrophils, lymphocytes, or monocytes were perfused through chambers with backward-facing steps so that vortices occurred with well-defined Reattachment of flow. Wall shear stresses downstream in reestablished flow equaled 0.07 Pa (low shear) or 0.3 Pa (high shear). In chambers coated with P-selectin, adherent leukocytes rolled. By use of a P-selectin-Fc fragment chimera, adhesion was predominantly stationary, enabling definition of initial attachment sites. Neutrophils adhered in all regions of the low-shear chamber, with a local maximum around the Reattachment Point. However, in the high-shear chamber, adhesion was restricted to the recirculation zone and immediately downstream from the Reattachment Point. Rolling at high shear stress allowed a population of regions where initial attachment could not occur. At high shear, lymphocytes and monocytes also formed attachments restricted to the region of the Reattachment Point. The results imply that all types of leukocytes might bind to a capture receptor in high-shear vessels with discontinuities in the wall and might then spread to other regions.
Omer Musa - One of the best experts on this subject based on the ideXlab platform.
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Numerical Investigation of the Effect of Sudden Expansion Ratio of Solid Fuel Ramjet Combustor with Swirling Turbulent Reacting Flow
Energies, 2019Co-Authors: Xiong Chen, Wenxiang Cai, Omer MusaAbstract:In this paper, the effect of sudden expansion ratio of solid fuel ramjet (SFRJ) combustor is numerically investigated with swirl flow. A computational fluid dynamics (CFD) code is written in FORTRAN to simulate the combustion and flow patterns in the combustion chamber. The connected-pipe facility is used to perform the experiment with swirl, and high-density Polyethylene (HDPE) is used as the solid fuel. The investigation is performed with different sudden expansion ratios, in which the port and inlet diameters are independently varied. The results indicated that the self-sustained combustion of the SFRJ occurs around the Reattachment Point at first, and then the heat released in Reattachment Point is used to achieve the self-sustained combustion in the redevelopment zone. The average regression rate is proportional to the sudden expansion ratio for the cases with a fixed port diameter, which is mainly dominated by the enhancement of heat transfer in backward-facing step. However, the average regression rate is inversely proportional to the sudden expansion ratio for the cases with fixed inlet diameter, which is influenced by the heat transfer mechanism of developed turbulent flow in the redevelopment zone.
