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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:14.0pt'>Hi David,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>Thanks for taking the time to respond. I’m attempting to respond to your post. Apologies if I’m committing some type of etiquette violation in responding to the group, but as you requested some clarification as to my process I thought to respond publicly.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>To answer your questions.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>I’ve been trying to understand why this particular polymer material produces a large s20w value when another material with different surface charge properties produces an s20w of 7.9s and sediments very differently.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>So the back calculation, going from s20w to s*, was me playing with the data to see if I could go from the 17.3 s20w back to s* which I would have hoped – as you point out – would not have been much different from 17.3s.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>My initial calculation using the s20w correction equation (equation 19) was comforting in that the calculated s* was 16.4s. I used SEDFIT to perform the same calculation just to check that all was in order – and as I stated SEDFIT returned the 16.4s value as had the calculation and the analysis in SEDANAL. Note that vbar and solvent parameters had been entered in into the experiment file and gOfs files had been generated by running DCDT. So I believe the s values returned in SEDNAL are s20w values.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>The problem arose when I used the Experiment page in SEDNTERP (version 20120828 BETA). Using the calculated value of s*, SEDNTERP did not return the same value for s20w that SEDANAL output. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>I also attempted the same operation using the web version of SEDNTERP which resulted in the same result, namely calculating an s20w of 27.8s when the experimentally observed s20w was17.3s.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>I had not thought to turn off the s20w calculation (in order to do so do I just remove vbar from the experiment info?) and attempt to fit for s*. Will try that next.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>Best regards,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>John Sumida, Ph.D.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><a href="http://depts.washington.edu/cidb4bio/index.shtml"><span style='color:windowtext'>Analytical Biopharmacy Core Facility</span></a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>University of Washington<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><a href="http://www.moles.washington.edu/"><span style='color:windowtext'>Molecular Engineering & Sciences Institute, G22</span></a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>3946 West Stevens Way NE<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>Seattle WA 98195-1653<o:p></o:p></span></p></div></body></html>