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Title: Investigation of temperature induced mechanical changes in supported bilayers by variants of tapping mode atomic force microscopy: Investigation of mechanical changes in bilayers
Award ID(s):
1054211
NSF-PAR ID:
10018308
Author(s) / Creator(s):
;
Date Published:
Journal Name:
Scanning
Volume:
37
Issue:
1
ISSN:
0161-0457
Page Range / eLocation ID:
23 to 35
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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  1. We investigate the Poisson ratio ν of fluid lipid bilayers, i.e. , the question how area strains compare to the changes in membrane thickness (or, equivalently, volume) that accompany them. We first examine existing experimental results on the area- and volume compressibility of lipid membranes. Analyzing them within the framework of linear elasticity theory for homogeneous thin fluid sheets leads us to conclude that lipid membrane deformations are to a very good approximation volume-preserving, with a Poisson ratio that is likely about 3% smaller than the common soft matter limit . These results are fully consistent with atomistic simulations of a DOPC membrane at varying amount of applied lateral stress, for which we instead deduce ν by directly comparing area- and volume strains. To assess the problematic assumption of transverse homogeneity, we also define a depth-resolved Poisson ratio ν ( z ) and determine it through a refined analysis of the same set of simulations. We find that throughout the membrane's thickness, ν ( z ) is close to the value derived assuming homogeneity, with only minor variations of borderline statistical significance. 
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