Index:
[thread]
[date]
[subject]
[author]
From: Stephen Harding <Steve.Harding@nottingham.ac.uk>
To : minton@helix.nih.gov
Date: Fri, 07 Sep 2001 08:14:30 +0100
Re: hydrodynamic question
This is a MIME message. If you are reading this text, you may want to
consider changing to a mail reader or gateway that understands how to
properly handle MIME multipart messages.
--=_4A10E4F2.61001BEB
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: quoted-printable
Dear Allen
You can either use formulae for the rod, the latest one I think being the =
Garcia-de la Torre-Tirado one (see eq. 34 of my 1995 review Biophys. Chem. =
55, (1995) 69-93) or use a bead-shell model. Jose Garcia de la Torre has =
a new programme which both sets up the model and does the calculations =
coupled to HYDRO/SOLPRO so why don't you drop him a line?=20
Remember that unlike for ellipsoids the hydrodynamic equations for beads =
and rods are only approximate - but thanks to the work of the Garcia de la =
Torre team the approximation is generally very good.
Alternatively if the rod is long enough a prolate ellipsoid may suffice
Steve Harding
---------------------------------------------------------------------------=
-------
Professor S.E. Harding
NCMH Physical Biochemistry Laboratory
University of Nottingham
School of Biosciences
Sutton Bonington=20
LE12 5RD, UK
Tel: +44(0) 115-951-6148
Fax: +44(0) 115-951-6142
http://www.nottingham.ac.uk/ncmh/ =20
---------------------------------------------------------------------------=
------
>>> Allen Minton <minton@helix.nih.gov> 09/06/01 09:41pm >>>
Hi gang -
A question for the hydrodynamics experts:
We can calculate the frictional coefficient for an ellipsoid of rotation=20=
(prolate or oblate) using the well-known Perrin equation. How can we=20
calculate the frictional coefficient for a cylindrical rod of arbitrary=20
length/diameter ratio?
I am guessing that the bead model might work, but it's not clear how =
one=20
would best represent the rod as an array of beads. I doubt that one =
could=20
realistically represent the rod as a simple linear array of beads with =
a=20
diameter equal to a bead diameter and a length equal to the number of =
beads=20
times the bead diameter, but perhaps some experienced person could set =
me=20
right on that point.
Does anyone know of an analytical solution to the rod problem, along =
the=20
lines of the Perrin equation?
Allen Minton
--=_4A10E4F2.61001BEB
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Content-Description: HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=3DContent-Type content=3D"text/html; charset=3Diso-8859-1"=
>
<META content=3D"MSHTML 5.50.4134.600" name=3DGENERATOR></HEAD>
<BODY style=3D"MARGIN-TOP: 2px; FONT: 8pt MS Sans Serif; MARGIN-LEFT: =
2px">
<DIV><FONT size=3D1></FONT>Dear Allen<BR>You can either use formulae for =
the rod,=20
the latest one I think being the Garcia-de la Torre-Tirado one (see eq. 34 =
of my=20
1995 review Biophys. Chem. 55, (1995) 69-93) or use a bead-shell model.&nbs=
p;=20
Jose Garcia de la Torre has a new programme which both sets up the model =
and=20
does the calculations coupled to HYDRO/SOLPRO so why don't you drop him a =
line?=20
<BR>Remember that unlike for ellipsoids the hydrodynamic equations for =
beads and=20
rods are only approximate - but thanks to the work of the Garcia de la =
Torre=20
team the approximation is generally very good.</DIV>
<DIV>Alternatively if the rod is long enough a prolate ellipsoid =
may=20
suffice<BR>Steve Harding<BR></DIV>
<DIV> </DIV>
<DIV>----------------------------------------------------------------------=
------------<BR>Professor=20
S.E. Harding<BR>NCMH Physical Biochemistry Laboratory<BR>University of=20
Nottingham<BR>School of Biosciences<BR>Sutton Bonington <BR>LE12 5RD, =
UK<BR>Tel:=20
+44(0) 115-951-6148<BR>Fax: +44(0) 115-951-6142<BR><A=20
href=3D"http://www.nottingham.ac.uk/ncmh/">http://www.nottingham.ac.uk/ncmh=
/</A> &nbs=
p; &=
nbsp; =20
<BR>-----------------------------------------------------------------------=
----------</DIV>
<DIV> </DIV>
<DIV><BR><BR><BR>>>> Allen Minton <minton@helix.nih.gov> =
09/06/01=20
09:41pm >>><BR>Hi gang -<BR><BR>A question for the hydrodynamics=
=20
experts:<BR><BR>We can calculate the frictional coefficient for an =
ellipsoid of=20
rotation <BR>(prolate or oblate) using the well-known Perrin=20
equation. How can we <BR>calculate the frictional coefficient =
for a=20
cylindrical rod of arbitrary <BR>length/diameter ratio?<BR><BR>I am =
guessing=20
that the bead model might work, but it's not clear how one <BR>would =
best=20
represent the rod as an array of beads. I doubt that one could=20
<BR>realistically represent the rod as a simple linear array of beads with =
a=20
<BR>diameter equal to a bead diameter and a length equal to the number of =
beads=20
<BR>times the bead diameter, but perhaps some experienced person could set =
me=20
<BR>right on that point.<BR><BR>Does anyone know of an analytical solution =
to=20
the rod problem, along the <BR>lines of the Perrin equation?<BR><BR>Allen=
=20
Minton<BR></DIV></BODY></HTML>
--=_4A10E4F2.61001BEB--
Index:
[thread]
[date]
[subject]
[author]