[RASMB] s values as function of cell position

[Leech, AP]

John Philo wrote:
> Jack,
>  
> I agree with Jack Correia that you should try swapping cells to see whether
> this variation is really associated with the particular cell or the position
> in the rotor. If it is the cell, then also try swapping centerpieces between
> housings.
>  
> This issue might be related to convection. First be sure your centerpieces
> have no scratches or roughness inside the channels (this often happens when
> people fill them using syringe needles). Sometimes too when you have a
> severe leak at high speed the center rib gets permanently bowed, which is
> not always easy to see by eye.
>  

Hi John, RASMBers,

Are there good ways of telling that convection has occurred from the data
(apart from irreproducibility)? Are there "tell tale" signs one should look
out for? I understand convection can also be caused by temperature changes.

> One other possibility might be that the alignment marks on your rotor or
> cell housings are incorrect (although if this is truly a problem that did
> not exist 2 years ago that cannot be the cause). I don't know the age of
> your rotor but there was definitely a period some years back where the marks
> on the rotors were not positioned properly. The cell alignment tool sold by
> BITC at U.N.H. would take care of that issue (assuming the slots in the cell
> housings are properly located). Similarly, at another time some centerpieces
> were produced where the key slot was not properly centered between the
> channels.
>  
> John

Similarly, is there a way to tell if you have such a rotor or centrepiece?

Best regards to all,

Andrew

-- 
Dr Andrew Leech                   *  Head of the Molecular
Technology Facility               *   Interactions Laboratory
Department of Biology (Area 15)   *  Tel   : +44 (0)1904 328723
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