Hi Zhijie --
With all manipulations on the goniometer, I strongly advise what I
learnt from Elspeth Garman: practice, practice, practice... but not
with your real crystal! Take it down, put up a dummy pin, and take the
time play around. I imagine even a non-hollow pin can be bent without
throwing it off with sufficient practice -- though Weikai is right, with
those pins it'll be REALLY tough, the special Hampton pins are much
recommended, because they have a weak point, making them far easier to
bend. A little tool is also supplied.
I do not agree however that you need a beamline with Kappa -- indeed, if
you were at such a beamline, there would be no need to bend the loop!
(How often I've wished for it...) The un-bent loops fit perfectly well
into cryotongs, as long as you affix them to the base at the right
length; once bent, the pins may not fit anymore, but you can always
straighten them again before retrieving them.
Of course, if you've already harvested your crystal on a non-bendable
pin, this doesn't help; but we routinely bend the loop itself, by
pushing on the stem of the loop (close to where it attaches to the pin),
with a pipette tip cut into a sharp point simply with scissors (you want
something non-metal, so as not to conduct heat onto the sample.) It's
not exact, of course, and (again) takes some practice. But very
effective -- it's rescued umpteen datasets for us. But BEWARE: DO NOT
BREATHE WHILE DOING THIS! (Go figure.)
HTH
phx
On 07/06/2011 23:33, Li, Weikai wrote:
> Hi Zhijie,
>
> This loop is good if you have a long unit cell on one dimension and you can align your crystal in a particular direction. You basically need a beamline equipped with Kappa, which allows you to directly put the crystal on with the plastic tube. A normal cryotong does not hold the bent loop.
>
> Regards,
>
> Weikai
>
>
> ________________________________________
> From: CCP4 bulletin board [[log in to unmask]] On Behalf Of Zhijie Li [[log in to unmask]]
> Sent: Tuesday, June 07, 2011 5:30 PM
> To: [log in to unmask]
> Subject: [ccp4bb] Hampton's adjustable cryoloop
>
> Hello,
>
> I just noticed that Hampton Research carries this adjustable mounted cryoloop (HR5-900):
> http://hamptonresearch.com/product_detail.aspx?cid=24&sid=136&pid=385<wlmailhtml:{35C92305-260C-4820-B40D-05B0D91A0A8F}mid://00000065/!x-usc:http://hamptonresearch.com/product_detail.aspx?cid=24&sid=136&pid=385>
>
> This looks quite interesting to me, as it seems that not every synchrotron station's configuration can allow the use of an extended arc.
>
> I wonder if somebody here can share some insights or experiences about this adjustable cryoloop. I once tried to bend my non-hollow stainless steel pin in liquid nitrogen with tweezers. It didn't work - the pin was too stiff then I lost my crystal in the end. I wonder if this cryoloop was designed such that bending it would be easier.
>
> Thanks in advance!
>
> Zhijie
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