[RASMB] Xl-I wavelength check question

[Karel Planken]

Well, Mark's question was about wavelength accuracy check. Wobbling or tilting of the rotor does not affect the wavelength calibration. Your suggestion to measure light intensities through an empty hole works equally well and if the rotor is properly balanced one could perform the radial calibration and subsequent check right away.
 
Karel.
 
P.S.: rotor stretching at 3 krpm is negligible, especially considering the radial resolution of the absorbance optical detection system. For the An-60 Ti rotor the stretch is approx. 25 um at 20 krpm and the radial resolution is on the order of 25 um. So only above 20 krpm stretching may become an issue.

________________________________

From: Titus M. Franzmann [mailto:titus_franzmann at hotmail.com] 
Sent: Wednesday, 17. February 2010 13:19
To: Karel Planken; 'Mark Agacan'; rasmb at server1.bbri.org
Subject: AW: [RASMB] Xl-I wavelength check question



Good morning, 

Just out of curiosity:

One can measure rotor stretching that occurs already at 3000 rpm. So I wonder whether imbalance also causes wobbling/tilting of the rotor at low speed? And if so, wouldn't that impact the calibration procedure? 

Is there any disadvantage performing the optical checks/calibrations on an empty hole with a rotor with balanced centerpiece and cell? 

Best

Titus

 

 

Titus M. Franzmann, Dr. 

Research Fellow

University of Michigan

Mol. Cell. and Develop. Biol.

4140C Nat. Sci. Bldg

830 N. University Ave 

Ann Arbor, Mi, 48109-1048, USA

+1 (734) 647 2291

tmfr at umich.edu <mailto:tmfr at umich.edu> 

walter lab website <http://www.mcdb.lsa.umich.edu/labs/walter/> 

 

 

 

Von: rasmb-bounces at server1.bbri.org [mailto:rasmb-bounces at server1.bbri.org] Im Auftrag von Karel Planken
Gesendet: Mittwoch, 17. Februar 2010 06:43
An: Mark Agacan; rasmb at server1.bbri.org
Betreff: Re: [RASMB] Xl-I wavelength check question

 

Dear Mark,

 

Just measure through a windowless cell (complete cell without windows). The weight difference with the counterbalance may be up to 5 g but as long as the rotor is not spinning above 3000 rpm you're safe. You may want to look up the appendix in the hardware manual available at "http://ultrascan.uthscsa.edu/aucmanual/AUCuserGuideVolume-1-Hardware.pdf <http://ultrascan.uthscsa.edu/aucmanual/AUCuserGuideVolume-1-Hardware.pdf> ". Good luck,

 

Karel Planken

 

Dr. K.L. Planken

 

Max-Planck-Institute of Colloids and Interfaces
Colloid Chemistry

 

Am Mühlenberg 1
D-14476 Golm
Germany

 

Tel.: +49 331 567 9518
Fax:  +49 331 567 9502
Office:K-2.102
E-mail: karel.planken at mpikg.mpg.de..

 

________________________________

From: rasmb-bounces at rasmb.bbri.org [mailto:rasmb-bounces at rasmb.bbri.org] On Behalf Of Mark Agacan
Sent: Wednesday, 17. February 2010 11:49
To: rasmb at server1.bbri.org
Subject: [RASMB] Xl-I wavelength check question

I have a question regarding the wavelength accuracy check for the XL-I:

 

Using a windowless cell (aluminium cell housing only with no centerpiece or windows, or one of the empty holes in the rotor?) - how can I match the weight of this cell with the counterbalance, even at the relatively low speed of 3000 rpm?

The remainder of the procedure as outlined in the Troubleshooting and Maintenance section of the XL-I manual seems straighforward enough, i'm just a little unclear on exactly how to load the rotor for this measurement.

 

Best Regards

 

Mark

 

 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr Mark Agacan, Scientific Officer for the Division of Biological Chemistry and Drug Discovery,
Wellcome Trust Biocentre, College of Life Sciences, University of Dundee, Dundee, DD1 5EH 
Tel: +44 1382 386095 Fax: +44 1382 345764 Mobile: 07525 451 117
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