Biology Reference
In-Depth Information
Chapter 16
PROBING THE NANOMECHANICAL
PROPERTIES OF VIRUSES, CELLS AND
CELLULAR STRUCTURES
Sandor Kasas a,b and Giovanni Dietler a
a Laboratoire de Physique de la Matière Vivante, Ecole Polytechnique Fédérale de Lausanne,
CH-1015 Lausanne, Switzerland
b Département de Biologie Cellulaire et de Morphologie, Université de Lausanne,
CH-1005 Lausanne, Switzerland
Sandor.Kasas@EPFL.CH
16.1 ELASTICITY
16.1.1 Ideal Solids
Elasticity describes the ability of a material to recover its original shape
after the withdrawal of an external deformation force. If the force (stress)
is suficiently small, then it is proportional to the deformation (strain). The
elastic modulus of a body is expressed as the ratio of stress to strain:
Elastic modulus = Stress
________
Strain
(16.1)
16.1.2 Length Deformaon
If a force is applied longitudinally to a body, the body will deform according
to Eq. (16.1) . Stress and strain are then qualiied by the term tensile, and the
elastic modulus, named Young's modulus (
E
), is given by
= tensile stress
________________
E
tensile strain
(16.2)
 
 
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