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<TITLE>Re: AW: [RASMB] FW: viscosity</TITLE>
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<BLOCKQUOTE><FONT COLOR="#800000">Hi Antje, Helmut and everyone<BR>
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You are right, Antje, it is certainly the <I>dynamic</I> viscosity of the solvent which should be used - the full expression for the correction of s values to s(20,w) already contains a term which takes into account the effect of the density of the solvent. <BR>
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However, there is an interesting little point arises, which has only occasionally been commented on. That is - if one is reporting s(c) values, should one report the <I>dynamic</I> s value or the <I>kinematic</I> s value? The difference is that the former includes a term correcting for the density of the <I>solution</I>, not merely that of the solvent. Unlike the case of intrinsic viscosity, where the 'Tanford correction' is applicable, the <I>dynamic</I> s value and the <I>kinematic</I> s value become identical at infinite dilution: but that still leaves the dilemma - which s(c) value ought one to report? I think that in 99.9% of cases it is the kinematic value which gets reported.<BR>
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For anything with a large frictional ratio, whether from extension or from swelling, the difference between the two types of s value is numerically negligible. However for compact, 'globular' solutes that is not the case. For PSL spheres, Cheng & Schachman long ago (1955) showed that the s-c dependence coefficient ks(dynamic) = 4.06 ml/g, whilst the kinematic coefficient is ~5 ml/g, all in accordance with expectation based on theory. In general,<BR>
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ks (dynamic) = ks (kinematic) - vbar<BR>
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It probably does not matter too much that unspecified s(c) values get reported, since they will almost always be kinematic s(c) values. And it is easy enough to convert the two types of s(c) value if one wants to. But the issue becomes more important if you are doing conformation analysis, say via conformation zoning (Pavlov et al 1997), or by getting the Wales-Van Holde ratio (ks/[eta]) and using the formula for that ratio (Rowe 1977). Here is is important to have both <I>dynami</I>c<I> </I>ks and <I>dynamic</I> [eta] values if one is to get meaningful estimates.<BR>
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Arthur<BR>
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P Y Cheng & H K Schachman (1955) J Polymer Sci 16: 19<BR>
A J Rowe (1977) Biopolymers 16 2595<BR>
Georges M Pavlov, Arthur J Rowe & Stephen E Harding (1997) "Conformation zoning of large molecules using the analytical ultracentrifuge" Trends in Analytical Chemistry,<B> </B>16: 401-405<BR>
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</FONT></BLOCKQUOTE><FONT COLOR="#800000">-- <BR>
*************************<BR>
Arthur Rowe<BR>
Lab at Sutton Bonington<BR>
tel: +44 115 951 6156<BR>
fax: +44 115 951 6157<BR>
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<BLOCKQUOTE><FONT SIZE="2"><FONT FACE="Arial">Dear Helmut and colleagues,</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">I took the dynamic viskosity, because it is in good agreement with the literature values.</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">Checking the units, I found that kinematic viscosity is in m2/s and dynamic viscosity is in </FONT></FONT>kg/(m·s) which is Pas and 10 Poise. <BR>
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<FONT SIZE="2"><FONT FACE="Arial">Best regards to upstairs :)</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">and everywhere</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">Antje</FONT></FONT> <BR>
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</FONT><FONT SIZE="2"><B>Von:</B> rasmb-bounces@rasmb.bbri.org [mailto:rasmb-bounces@rasmb.bbri.org] <B>Im Auftrag von </B>Helmut Coelfen<BR>
<B>Gesendet:</B> Dienstag, 31. März 2009 00:12<BR>
<B>An:</B> rasmb@rasmb.bbri.org<BR>
<B>Betreff:</B> [RASMB] FW: vsicosity</FONT> <BR>
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</FONT><FONT SIZE="2"><B>From:</B> Helmut Coelfen <BR>
<B>Sent:</B> Dienstag, 31. März 2009 00:09<BR>
<B>To:</B> 'rasmb@rasmb.bbri.edu'<BR>
<B>Subject:</B> vsicosity</FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">Dear colleagues,</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial"> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">When correcting sedimentation coefficients from a given temperature to s20,w; which viscosity is needed ? Dynamic or kinematic ?</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">Thanks for any insight</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">Helmut</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Times New Roman">________________________________________________________________</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">PD Dr. habil. Helmut Cölfen</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">Max-Planck-Institute of Colloids and Interfaces</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">Colloid Chemistry</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">Am Mühlenberg, D-14476 Golm, Germany</FONT></FONT> <BR>
<BR>
<FONT SIZE="2"><FONT FACE="Arial">Tel: --49 331 567-9513</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">Fax: --49 331 567-9502</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Arial">http://www.mpikg-golm.mpg.de/kolloidchemie/arbGruppen/trennmethoden/index.html</FONT></FONT> <BR>
<BR>
<FONT SIZE="2"><FONT FACE="Arial">http://www.mpikg-golm.mpg.de/kolloidchemie/arbGruppen/trennmethoden/MitarbeiterInnen/Helmut_C__lfen/index.html</FONT></FONT> <BR>
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<FONT SIZE="2"><FONT FACE="Times New Roman"> </FONT>_______________________________________________________________</FONT> <BR>
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<FONT SIZE="4"><FONT FACE="Arial"><B>New Book out:</B></FONT></FONT> <BR>
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<FONT FACE="Arial">Dr. Helmut Cölfen <http://eu.wiley.com/WileyCDA/Section/id-302479.html?query=Dr.+Helmut+Coelfen> , Prof. Markus Antonietti <http://eu.wiley.com/WileyCDA/Section/id-302479.html?query=Prof.+Markus+Antonietti> <BR>
</FONT><BR>
<FONT FACE="Arial">ISBN: 978-0-470-02981-7</FONT> <BR>
<BR>
<FONT FACE="Arial">Hardcover</FONT> <BR>
<BR>
<FONT FACE="Arial">288 pages</FONT> <BR>
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<FONT FACE="Arial">June 2008</FONT> <BR>
<BR>
<FONT FACE="Arial">http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0470029811.html</FONT> <BR>
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