From: Philo, John <jphilo@amgen.com>
  To  : 'les.holladay@ALZA.COM' <les.holladay@ALZA.COM>
  Date: Thu, 4 Sep 1997 16:01:03 -0700

RE: question about Wiener skewing...

Les, 

I can't answer your question exactly, but I done velocity runs at 40
mg/ml with 3 mm centerpieces.  This was an ~80 kDa protein at 60 K rpm
(i.e. pretty sharp boundaries), and when I look back at those data I see
slopes of up to about 30 fringes/mm, so one can certainly go that high
(and probably higher) with 3 mm centerpieces.

On the other hand, I tried running 8-channel cells at 40 mg/ml and had a
LOT of trouble keeping the gradient small enough.  I had to keep cutting
the speed back and back.  The steepest data I see from that experiment
give about 20 fringes/mm.  

John

>----------
>From: 	les.holladay@ALZA.COM[SMTP:les.holladay@ALZA.COM]
>Sent: 	September 04, 1997 2:44 PM
>To: 	rasmb@bbri.harvard.edu
>Subject: 	question about Wiener skewing...
>
>     Hi youall..
>     
>     I seem to remember some kind soul posting on rasmb the usuable limit 
>     for dJ/dr (fringe steepness) that one could go to before data 
>     degradation.  I'd be grateful if one of the wizards out there could 
>     give me this number.  And... while you are at it, would it be 
>     different for a 3 mm c/p than for a 12 mm c/p?
>     
>     thanking youall in advance..
>     
>     Les Holladay
>     les.holladay@alza.com
>