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<p class=MsoPlainText><font size=4 face="Times New Roman"><span
style='font-size:14.0pt;font-family:"Times New Roman"'>Hi Yifan,</span></font></p>
<p class=MsoPlainText><font size=4 face="Times New Roman"><span
style='font-size:14.0pt;font-family:"Times New Roman"'> </span></font></p>
<p class=MsoPlainText style='line-height:150%'><font size=4
face="Times New Roman"><span style='font-size:14.0pt;line-height:150%;
font-family:"Times New Roman"'>Thanks for your response. You brought a really
good suggestion. I love to try it. However due to our very limited access to the
scope and due to the fact that we don’t have a CCD camera, I prefer to
get a direct answer to the question from our 3DEM community. I guess some
people do have experience on this issue.</span></font></p>
<p class=MsoPlainText style='line-height:150%'><font size=4
face="Times New Roman"><span style='font-size:14.0pt;line-height:150%;
font-family:"Times New Roman"'>By the way, as indicated in my previous message,
the purpose for me to estimate the maximum of ice thickness is for my image
analysis, which implied that the ice thickness is still appropriate for
imaging. On the other hand, my experience suggested that ice thickness varies
on different type of grids, for example, on 7/2 quantifoil holy grids, I
usually get thinner ice than that on 3.5/1 quantifoil holy grids. But I have
never tried to figure out how significant the difference of ice thickness could
be. </span></font></p>
<p class=MsoPlainText style='line-height:150%'><font size=4
face="Times New Roman"><span style='font-size:14.0pt;line-height:150%;
font-family:"Times New Roman"'>I’m still waiting for more response and an
answer. Thanks for attention and help!</span></font></p>
<p class=MsoPlainText style='line-height:150%'><font size=4
face="Times New Roman"><span style='font-size:14.0pt;line-height:150%;
font-family:"Times New Roman"'> </span></font></p>
<p class=MsoPlainText style='line-height:150%'><font size=4
face="Times New Roman"><span style='font-size:14.0pt;line-height:150%;
font-family:"Times New Roman"'>Regards,</span></font></p>
<p class=MsoPlainText style='line-height:150%'><font size=4
face="Times New Roman"><span style='font-size:14.0pt;line-height:150%;
font-family:"Times New Roman"'>Guobin </span></font></p>
<p class=MsoPlainText style='line-height:150%'><font size=4
face="Times New Roman"><span style='font-size:14.0pt;line-height:150%;
font-family:"Times New Roman"'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>-----Original Message-----<br>
From: Yifan Cheng [mailto:Yifan_Cheng@hms.harvard.edu] <br>
Sent: Tuesday, February 15, 2005 6:39 PM<br>
To: Hu, Guobin ; 3dem@ucsd.edu<br>
Subject: Re: [3DEM] A question about ice thickness of cryo-EM</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Hi</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Well, the ice can be very very very thick no matter what grids you use.
</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Did you ever get cryo grids which is too thick to be seen through?</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>What you can do to measure the ice thickness is to burn a small hole in
</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>the middle of the ice. Then tilt you holder to a high tilt say 60
degree </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>and measure the size of the hole. This can tell you how thick is your </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>ice. Then you can calibrate it with your CCD camera by measure the </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>counts over an empty hole and over ice. Next time just by comparing the
</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>CCD counts over ice and empty hole will give you some fairly good </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>estimation about your ice thickness. Good luck</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Yifan</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Hu, Guobin wrote:</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> Hi colleagues,</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> For our image analysis, we need to estimate the maximum ice
thickness in </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> our cryo-EM specimen on 3.5/1 quantifoil grids. We may be able to </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> estimate that based on the thickness of carbon foil. As indicated
by the </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> quantifoil product catalogue, the standard thickness of carbon
foil is </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> 12 nm. While observations of our cryo-EM micrographs have
suggested that </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> the thickness of carbon foil is definitely much larger than 12 nm.
Does </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> anybody have an idea of what the maximum thickness of ice could be
on </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> quantifoil grids (3.5/1)?</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> Thanks for help!</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> Guobin Hu</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>-- </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>************************************************************</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Yifan Cheng, Ph.D.</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Department of Cell Biology, Harvard Medical School</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>240 Longwood Avenue, Boston, MA 02115, USA</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Phone: 1-617-432-4095 (office), 432-4097 (wet lab),</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>
432-4708 (EM lab), 432-4107 (computer lab);</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Fax: 1-617-432-1144 (department)</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>email: Yifan_Cheng@hms.harvard.edu</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>************************************************************</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
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