[3dem] Regarding Image Quality from FEI Tecnai G2 Polara

Thu Sep 8 16:14:10 PDT 2016

Well, this may seem obvious, but we fell into this trap once in Boulder with our TF30. And no one seemed to mention this.

Our rule was that no one was supposed to remove the cryo-box, so we worked for over a year that way on a scope with both plastic and cryo use. Then, a service engineer removed the cryo-box and didn't put it back. Months of trouble-shooting with very similar problems you've described led to an AHA!! moment where we checked and sure enough the cryo-box was out. The new protocol became always check the cryo-box is in before doing anything else. Every time.

It was a very frustrating experience to say the least.

Also, like Guenter, we had bad braids once that led to issues.

I hope you find the issue.
Cheers,
Cindi

--
Cindi L. Schwartz
Electron Microscopist
Rocky Mountain Labs/NIAID/NIH
903 South 4th Street
Hamilton, MT  59840
240-669-5473
Cindi.Schwartz at NIH.gov<mailto:Cindi.Schwartz at NIH.gov>
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From: Sayan Bhakta <19sayanbhakta89 at gmail.com<mailto:19sayanbhakta89 at gmail.com>>
Date: Saturday, September 3, 2016 at 4:39 AM
To: "3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>" <3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>>
Subject: [3dem] Regarding Image Quality from FEI Tecnai G2 Polara

Hi,
We are facing many problems with our Cryo EM facility. I am giving some details of the machine and one of the main problems we are facing. It would be very helpful if people comment on this and help us to find the actual problem.

Machine:
FEI Tecnai G2 Polara
300Kv
Have been running for last two years.

Camera:
FEI Eagle 4k*4K

Problem:
On the first day when we are putting our sample into the Cryo EM, we are getting good images. From the second day the quality of the images deteriorates.

1.  If we look at the images taken on the first day and second day, the intensity values of the images decreased on the second day.
2.  From the FFT, we see nice thorn rings from the images taken on the first day. But for the images taken in the second day, the FFT is very bad. Most of them are having drifts.
3. Irrespective of the days, there are some images for which the 1D spectrum is having a cut in between. What I mean by that is there is spectrum upto certain distance in the 1D spectrum, then there is no waves, then again there are some waves.
4. Irrespective of the days, images are sometimes with blakish shadow on one side and with whitish shadow on other side. We need to do gain correction more frequently than usual- a number of times in a day.

For your information:

1. The vacuum is stable on the second day.
2. We are giving Cryo-cycle each weekend.

If anyone has ever faced the same problem or has any advice on this regard, it would be very helpful. We have been struggling very hard to standardise many issues with our microscope.
--

Sayan Bhakta

Research Scholar

Group of Dr. Jayati Sengupta

CSIR - Indian Institute of Chemical Biology

Kolkata, West Bengal

India
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