From: Walter Stafford <STAFFORD@bbri.org>
  To  : RASMB@bbri.org
  Date: Mon, 28 Aug 2000 21:54:15 -0400

scratches on centerpieces

RASMBers,
	Here is the last exchange I had recently with a colleague concerning
potential artifacts in sedimenatation velocity runs. Thought it might be of 
general interest.

- Walter

p.s. that centerpiece (as well as several others found later) was removed
from service.
========================================================================== 
From:	STAFFORD     "Walter Stafford" 28-AUG-2000 21:25:38.11
To:	SMTP%"knut@bbri.org"
CC:	STAFFORD
Subj:	RE: question

Well, actually, there is a potential problem that I have experienced.
If there is a scratch in the wall of the centerpiece on the sample side, it 
can cause convection. I had one cell that created a shoulder on every sample I 
ran. Take a look at the wall of the septum between the sectors on the side you
usually load the sample. If you jab the wall with the syringe needle, it will
create a scratch deep enough to cause his type of problem. 

=======================================================================
>Walter,
>i was just wondering if there was any experimental problems,
>like something with the cells that could cause asymetry of the peak.
>
>--knut



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Walter F. Stafford III, Ph.D.
Senior Scientist
Analytical Ultracentrifugation Research Laboratory
Boston Biomedical Research Institute
64 Grove Street
Watertown, MA  02472-2829

tel: (617) 658-7808
fax: (617) 972-1753

Telephone switchboard operator: (617) 926-8040 or (617) 658-7700

stafford@bbri.org">mailto:stafford@bbri.org

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