[3DEM] A question about ice thickness of cryo-EM

Hu, Guobin guohu at UTMB.EDU
Fri Feb 18 09:54:13 PST 2005


Hi Paul,

Thanks for your response! I appreciate your patience.
I finally found a paper which addressed the issue of the miximal ice thickness for imaging with 120 kV electron source. I could estimate that for 100 kV source based on that paper.

I think it may be time for this discussion to end. I thank everybody who responded to my question including to 3DEM mail list and personally to myself. I appreciate your help!

All the best,
Guobin 




-----Original Message-----
From:	Paul Chipman [mailto:paulrc at bilbo.bio.purdue.edu]
Sent:	Fri 2/18/2005 7:14 AM
To:	Hu, Guobin ; 3dem at ucsd.edu
Cc:	
Subject:	RE: [3DEM] A question about ice thickness of cryo-EM
Hi Goubin,

We are using a 300kV unit when imaging through the 800nm thick ice. 
As for 100kV, I really don't know how thick of ice you can image 
through but as Bill pointed out, it is also a question of how well 
you actually want to resolve the sample you are examining.

cheers,
Paul


At 1:16 PM -0600 2/17/05, Hu, Guobin  wrote:
>Dear Dr. Bill Tivol,
>
>You are so right that the maximum ice thickness for imaging depends 
>on the HT of the scope. I sent a message to Paul asking about the 
>specific HT of 100 Kv. Hopefully He would tell me a number. Of 
>course, I'd be happier if our colleagues could tell me the numbers 
>not only of 100 Kv, but also of 200 Kv, 300 Kv and 400 Kv.
>Thanks!
>
>Regards,
>Guobin
>
>
>
>
>-----Original Message-----
>From: owner-3dem at ncmir.ucsd.edu [mailto:owner-3dem at ncmir.ucsd.edu] 
>On Behalf Of Bill Tivol
>Sent: Thursday, February 17, 2005 1:01 PM
>To: 3dem at ucsd.edu
>Subject: Re: [3DEM] A question about ice thickness of cryo-EM
>
>
>On Feb 17, 2005, at 9:34 AM, Hu, Guobin wrote:
>
>
>Thanks for your information! You might have given me a basic idea 
>what the maximum of ice thickness could be.  Actually as indicated 
>in my earliest message, I'm not trying to figure out how thick the 
>ice could be in any specific case. What I'm trying to find out is an 
>estimate of the maximum of ice thickness of cryo-EM grids which is 
>good enough for imaging. I wonder if anybody has ever collected data 
>with ice thicker than 800 nm.
>
>
>Thanks for any further help!
>
>
>
>Dear Guobin,
>The maximum ice thickness for imaging depends on the HT of your 
>scope. We have been imaging small whole cells at 300 kV, and we can 
>do tomography on cells that are a little smaller than 1 um. Of 
>course, the ice may not be that thick except in the immediate 
>neighborhood of the cell, and the resolution should improve for 
>thinner ice, so the answer to "Is the ice too thick for imaging?" is 
>"It depends on what you're trying to do and what equipment you have 
>to do it."
>Yours,
>Bill Tivol, PhD
>EM Scientist and Manager
>Cryo-Electron Microscopy Facility
>Broad Center, Mail Code 114-96
>California Institute of Technology
>Pasadena CA 91125
>(626) 395-8833
>tivol at caltech.edu
>


-- 
Paul Chipman
Electron Microscopy Facility Manager
Dept. of Biology, Purdue University
Lilly Hall, Rm. B216
Phone: 765-494-1487
Fax:765-496-1189






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