Biomedical Engineering Reference
In-Depth Information
Fig. 1.4
Number of water molecules inside the nanotube (
N
) and the water flux (which is defined
as the number of water molecules passing through the nanotube along
z
axis and the opposite
direction per nanosecond) as a function of time for each deformation ı. The time period for each
deformation ı is
T
,where
T
12 ns for
N
and 216 ns for the flux. The flux shown is averaged each
18 ns (reprinted from [
40
]. Copyright 2005 American Chemical Society)
D
Fig. 1.5
Average number of
N
and the average net flux in
thewholeperiodof
T
,
together with the force
F
actingontheatom,asa
function of ı (reprinted from
[
40
]. Copyright 2005
American Chemical Society)
pass through the tube along
z
axis and the opposite direction, respectively, resulting
in a net water flux of 5.69 water molecules per nanosecond along
z
axis.
In macroscopy, as the force
F
(
t
) increases, the flow across the nanotube
decreases monotonically due to the increase in the deformation [
40
], which can
be characterized by a parameter ı, which is the displacement of the forced-atom
from its initial position in the pristine SWNT as shown in Fig.
1.3
.However,
in this system, the water flux and occupancy
N
do not decrease as expected as
showninFigs.
1.4
and
1.5
when ı increases from 0 to 2.0 A. In the interval of
1.4 A <ı<ı
C
2.0 A, the water flux even increases a little. Please be noted that
the radius of a water molecule is only 1.4 A. This shows that the water flux is
unexpectedly stable even when the deformation of the forced-atom is larger than the
