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Stephen H. Loring and Nam P. Suh. Lin, Judy Li-Wen Massachusetts Institute of Technology. Dept. of Mechanical Engineering. Massachusetts Institute of Technology. Department of Mechanical Engineering 2007-02-21T13:14:30Z 2007-02-21T13:14:30Z 2006 http://hdl.handle.net/1721.1/36249 77275482 Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. "June 2006." Includes bibliographical references (p. 63-64). In the pleural space, sliding between the lung and chest wall induces shear stress that could damage the delicate mesothelial cells covering the tissue surfaces. Normally, the pleural space, which is filled with fluid, is able to sustain continuous shear loading throughout its lifetime. To understand the mechanisms in preventing frictional damage on mesothelial tissue, we conducted experiments using abdominal tissue excised from a rat. We allowed the tissue to slide against a glass surface, and measured the fluid thickness and shear force between them. We also studied independent variables such as location on the tissue, applied normal load, sliding velocity and direction to determine their effects on mesothelial tissue lubrication. Both thickening and thinning of the fluid layer were observed during sliding. The fluid thickness was found to change with sliding velocity and direction, but invariant with location on tissue surface. In tribological experiments, shear force decreased with increasing velocity until it reached a minimum value varying with different tissue samples. Normal load had a strong effect on shear force, but not on friction coefficient. (cont.) Overall, the friction curves had similar shape as described by the mixed/elasto-hydrodynamic regions of the Stribeck curve. Results were consistent within each tissue sample, but varied among samples. The dependency on velocity and direction suggested elasto-hydrodynamic lubrication. Taken together, we conclude that elasto-hydrodynamic lubrication is likely to be an important lubrication mechanism for mesothelial tissue sliding in the pleural region. Our findings support the existence of a continuous fluid layer separating the pleural surfaces. The fluid pressure gradient generated by surface roughness redistributes fluid from thick to thin regions preventing surface contact. by Judy Li-Wen Lin. S.M. 70 p. eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Mechanical Engineering. Mechanisms of mesothelial tissue lubrication Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="d1dd20da-8a60-47b4-a712-ba401b3d0251"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Mechanisms of mesothelial tissue lubrication</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2006</PublicationDate> <Authors> <Author> <DisplayName>Lin, Judy Li-Wen</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Mechanical Engineering.</Keyword> <Abstract>In the pleural space, sliding between the lung and chest wall induces shear stress that could damage the delicate mesothelial cells covering the tissue surfaces. Normally, the pleural space, which is filled with fluid, is able to sustain continuous shear loading throughout its lifetime. To understand the mechanisms in preventing frictional damage on mesothelial tissue, we conducted experiments using abdominal tissue excised from a rat. We allowed the tissue to slide against a glass surface, and measured the fluid thickness and shear force between them. We also studied independent variables such as location on the tissue, applied normal load, sliding velocity and direction to determine their effects on mesothelial tissue lubrication. Both thickening and thinning of the fluid layer were observed during sliding. The fluid thickness was found to change with sliding velocity and direction, but invariant with location on tissue surface. In tribological experiments, shear force decreased with increasing velocity until it reached a minimum value varying with different tissue samples. Normal load had a strong effect on shear force, but not on friction coefficient.</Abstract> <Abstract>(cont.) Overall, the friction curves had similar shape as described by the mixed/elasto-hydrodynamic regions of the Stribeck curve. Results were consistent within each tissue sample, but varied among samples. The dependency on velocity and direction suggested elasto-hydrodynamic lubrication. Taken together, we conclude that elasto-hydrodynamic lubrication is likely to be an important lubrication mechanism for mesothelial tissue sliding in the pleural region. Our findings support the existence of a continuous fluid layer separating the pleural surfaces. The fluid pressure gradient generated by surface roughness redistributes fluid from thick to thin regions preventing surface contact.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>