[RASMB] observation boundaries for the fluorescence detector

[smcbryan]

Gentlemen, 
Is it possible that the stepper motor setting (Flo position unit 1) has
been compromised, and the offset calibration needs to be reset to 6.677cm
(outer edge) within the SERVICE\HARDWARE SETTINGS\STEPPER MOTOR SETTING
component of the AOS software?
steve mcbryant





I have had to do this from time to time to ensure magnet angle capture. 
On Tue, 3 Nov 2009 12:44:52 -0500, "Cole, James" <james.cole at uconn.edu>
wrote:
> Dear Titus
> The meniscus in this data set is at  5.8 cm. If you are using  the
> Beckman-Coulter or Spin Analytics  2-sector cells, a nearly  filled
channel
> should have the meniscus at around 5.9-6.0 cm. The window holder/
> screw-ring block the fluorescence detector at the bottom of the  cell,
> causing the downward slope. It has nothing to do with fluorescence
> quenching. In our system, the drop off begins at about 7 cm. In  your
data
> it seems to occur at about 6.9 cm. So, it does seem possible that the
radii
> are shifted low in this data. This is strange because in the fluorescence
> system  the detector movement is is controlled by stepper motor and is
> stable.
> Regards,
> Jim Cole
> 
> On 11/2/09 1:54 PM, "Titus M. Franzmann" <tmfr at umich.edu> wrote:
> 
> Hi,
> What are the optical sedimentation observation boundaries for the
> fluorescence detector? I do not have access to the system currently. A
> friend sent me his data. I have the impression that in this particular
run
> the entire signal is shifted toward smaller radii. My impression was
> always, that the cell gets illuminated to about 7.1 cm before the bottom
> gets visible due to the dye quenching. My suspicion is that the radial
> calibration is off on this machine.
> Thanks for your help
> Best,
> Titus
> 
> Titus M. Franzmann
> 
> 
> University of Michigan
> Molecular, Cellular,
>    Developmental and Biology (MCDB)
> 4140 Nat. Sci. Bldg
> 830 North University
> Ann Arbor, Mi, 48109
> USA
> 
> Tel: +1 (734) 647 2291
> eMail: tmfr at umich.edu
> web: walter lab website <http://www.mcdb.lsa.umich.edu/labs/walter/>
> 
> 
> 
> ----------------------------------------
> James Cole
> Associate Professor, Department of Molecular and Cell Biology
> Head, National Analytical Ultracentrifugation Facility
> University of Connecticut
> 91 North Eagleville Road
> Storrs, Connecticut 06269
> Tel: (860) 486-4333
> Fax: (860) 486-4331
> email: james.cole at uconn.edu
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