[RASMB] timing of auc runs

John E Harlan john.e.harlan at abbott.com
Fri Sep 25 15:13:51 PDT 2009


Judith-

I went back and looked at some of the log files from some recent velocity 
experiments where I had only one cell in the centrifuge.  I basically had 
the centrifuge collect scans as quickly as it could (no delay between 
scans).  I collected interference data as well as absorbance at A280nm, 
from 5.8cm to 7.3cm, with a radial step size of 0.003cm and no replicates, 
speed is 42,000rpm.  I was using an 8-hole rotor.

When I look at the elapsed time for the scan, I see it vary by a few 
seconds, from 1:31 to 1:35.  However, when I look at the interval between 
the start times for adjacent scans, it varies quite a bit (in one instance 
it went from 1:40 to 2:09).  This is all in the same experiment.

When I look at the next experiment I see a similar spread in elapsed time 
a the scan, 1:32 to 1:37.  I don't see quite the variation in the interval 
between start times in the experiment, it seems they are all about 1:40 or 
so.

I suppose this difference in start interval could account for differing 
total experiment times.  I think John Philo is correct in that differing 
experimental times probably won't bother any given experiment, as long as 
the time stamps are correct for the data.  I can't say that I have paid 
much attention to this before, but it looks like the same thing happens 
for me as well.

Interestingly, I had some communication problems with the computer and 
centrifuge in between these runs that forced me to power everything down 
(often helps restore communication).  Upon restarting everything, it looks 
like my  intervals between start times are more consistent.

Good Luck, 

John



Judith Kornblatt <judithk at alcor.concordia.ca> 
Sent by: rasmb-bounces at rasmb.bbri.org
09/25/2009 03:18 PM

To
smcbryan <smcbryan at lamar.colostate.edu>
cc
rasmb at server1.bbri.org
Subject
Re: [RASMB] timing of auc runs






In reply to the same question from two of you, yes, the Rmin and Rmax 
are the same in every run - we never change them.
Judith Kornblatt

smcbryan wrote:
> For your first two experiments at 32K, you are collecting data at 3.975
> minutes per scan and 4.455 minutes per scan for the 13:15 and 14:51
> experiments, respectively. Assuming you are scanning in the Abs mode 
(which
> the scans per unit time suggests) that is a significant difference 
between
> scan time, if you set the radial increment and scan limits (Rmin and 
Rmax)
> the same for both runs. Did you set Rmin and Rmax to the same limits? 
> Our machines won't collect every scan at the set radial increment,
> typically a 0.001cm experiment will average 1.0015cm radial increments. 
But
> that value is the same between different experiments, so your 
differences
> are unusual. 
> Steve Mcbryant, PhD
> Director, PPC Facility
> Colorado State University
>
>
>
>
> On Fri, 25 Sep 2009 13:38:01 -0400, Judith Kornblatt
> <judithk at alcor.concordia.ca> wrote:
> 
>> How consistent should the length of time for a run be? I've been doing 
>> the same basic run multiple times - same speed, same number of scans - 
>> and the total time for the run, as displayed on the panel of the AUC, 
>> varies considerably. For example, 200 scans, 32000 rpm, the times 
varied 
>> from 13:15 to 14:51. More recently, 200 scans at 37000, times varied 
>> from about 13 hours to 14 hours. Is this variation normal?
>> Judith Kornblatt
>> Chemistry and Biochemistry
>> Concordia University
>> Montreal Quebec
>>
>> _______________________________________________
>> RASMB mailing list
>> RASMB at rasmb.bbri.org
>> http://rasmb.bbri.org/mailman/listinfo/rasmb
>> 
>
>
> 


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