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Re: [ccp4bb] twin fraction varies between crystals?
 

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CCP4bb <-- 2007 <-- April 2007 <-- 17 April 2007
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Subject: Re: twin fraction varies between crystals?
From: Christopher Colbert Christopher {- dot -} Colbert {- at -} UTSOUTHWESTERN {- dot -} EDU
Date: 2007-04-17 		Next message:
Subject: Re: twin fraction varies between crystals?. .
From: Iain Kerr iain {- dot -} kerr {- at -} STJUDE {- dot -} ORG
Date: 2007-04-17


Subject: Re: twin fraction varies between crystals?
From: Manish C Pathak pmxtal {- at -} YAHOO {- dot -} CO {- dot -} IN
Date: 2007-04-17

I agree with you Mark. Even in my case the twinning fractions
varied substantially among the different crystals grown in same
drop. Moreover, I feel the fractions may vary at different part of
the crystal too. Please correct me if i am wrong.

regards
Manish


Mark Mayer wrote: For cases where people have had merohedral twinning, did the twin fraction vary substantially
between individual crystals grown under indentical conditions? I have no prior experience with
merohedral twinning, and was surprised to see that the twin fraction varied substantially as detailed
below, and that by screening we were able to get untwinned xtals.

The project started with a weak home data set for which the twin fraction was 0.478, and which
scaled in both H3 and H32. We just came back from APS with data sets from another three crystals,
for which the ML twin fraction, estimated using phenix.xtriage with scalepack merged intensities as
input, varied from 0.335, 0.219 and 0.02. The latter is refining very nicely, in H3 and will not scale in
H32.

Thanks - Mark



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