Hi there,
Thank you for all your suggestions and generous help, I tried some methods
you guys mentioned and learned something new . I really appreciate it.
With Kay's help,(after exclusion of the ice rings he found that the data are
P1, not P2(1). ) I got my structure solved, there are four copies
ctober 15, 2011 6:10 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] data processing problem with ice rings
Hi ChenTiantian,
the R-factors and I/sigma are bad even at low resolution where the first
icering does not influence the results.
Thus, the problem with your data processing has little t
Hi,
I agree with other people. You must have a wrong index here. Can you tell us
what is the unit cell for this crystal from your determination? I can see
very close spots in the high resolution shell from your image, which are
overlapped into one spot in the low resolution shell. Try to use other
Hi
I'd agree with Kay here - I would think that the original indexing is
incorrect.
One thing I notice on the original image as posted - there's a red
cross on it - if that's supposed to mark the beam position, I think
it's about 4mm or so away from the true position.
So -
(1) check th
Hi ChenTiantian,
the R-factors and I/sigma are bad even at low resolution where the first
icering does not influence the results.
Thus, the problem with your data processing has little to do with the
icerings. I guess that the indexing is not correct.
My suggestion:
1) using adxv or a similar
These rings are nanocrystalline cubic ice (ice Ic, as opposed to the
"usual" ice Ih). It is an interesting substance in that noone has ever
prepared a large single crystal of it. In fact, for very small crystals
it can be hard to distinguish it from amorphous ice (or "glassy
water"). The thr
Hello ,
Can any one send me pdf of this paper as its a old paper and not
accessible here .
M.F. Perutz, Preparation of haemoglobin crystals. *J. Cryst. Growth*
, * 2 * (1968), pp. 54–56.
On Fri, Oct 14, 2011 at 10:42 AM, ChenTiantian
wrote:
> Hi there,
> I am processing a data
Your main problem is not the ice rings but a wrong lattice/indexing solution. R
factors are very high for even low res shells and I/sigma very low. To me this
tells you are not finding your diffraction spots at all.
First thing to try: Take more images for the indexing step and use only the
str
First of all, are you sure those are ice rings? They do not look typical. I
think you might have salt crystals from dehydration *before* freezing.
Otherwise, I think your freezing went well. Maybe try a humidity controlled
environment when you freeze.
Second, I'm not so sure the bad stats come
try a frozen xtal ...
On Fri, 14 Oct 2011 13:12:12 +0800
ChenTiantian wrote:
> Hi there,
> I am processing a dataset which has bad ice rings (as you
> can see in the
> attach png file).
> I tried both XDS and imosflm, and got similar results, it
> seems that adding
> " EXCLUDE_RESOLUTION_RANGE"
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