The mechanics of transcapillary exchange.
Item
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Title
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The mechanics of transcapillary exchange.
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Identifier
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AAI9207130
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identifier
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9207130
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Creator
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Tsay, Ruey-Yug.
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Contributor
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Adviser: Sheldon Weinbaum
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Date
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1991
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Chemical | Engineering, Biomedical
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Abstract
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The interendothelial cleft is the principal pathway for water and hydrophilic solute transport across the capillary wall. Existing theories, based largely on one-dimensional models, have had limited success in correlating capillary permeability data and junctional ultrastructure. A new theoretical framework has been developed herein to examine the role of the detailed structure of the intercellular cleft in the regulation of capillary permeability.;The new three-dimensional junction-pore-matrix model has been used to examine the transport behavior of a cleft with a junction strand with discrete pores and fiber matrix components in its wide part. The results indicate that for a cleft with infrequent larger pores, the lateral spreading at the entrances/exits of the junctional pores can be very significant. New hydrodynamic theories have been developed for the effect of fibers in the wide part of the cleft. A rigorous solution for a channel flow through a square array of fibers with aspect ratio B {dollar}>{dollar} 5 provides convincing evidence for the accuracy of a Brinkman approximation for long slender fibers.;The new theoretical models developed herein indicate that neither a junction-pore model with small pores of the required size for them to be the primary molecular sieve nor a simple fiber matrix filling the entire cleft can explain all the measured data for capillary permeability. Feasibility studies show that a cleft with larger junctional breaks, typically 22 x 44 nm in cross-section, and with a fiber layer at the cleft entrance is the most likely cleft structure to reconcile the structural and permeability data. The present model predicts that a cleft with 22 x 44 nm pores, with pore spacing of 480 nm, when combined with a fiber matrix with open spacing {dollar}\Delta{dollar} = 7 nm can fit the measured values for the hydraulic conductivities with and without a fiber layer. This structure can also fit the measured values of diffusive permeability for small ions and large solutes of size close to albumin. However, this model still does not fit the diffusive permeability data for intermediate size solutes of 1-2 nm radius. Experiments based on the present study are suggested for the future work.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
