[3dem] 3dem Digest, Vol 148, Issue 24

Thu Dec 19 19:32:33 PST 2019

 Dear all, 
thank you so much for all your kind help and valuable inputs! 

Best regards,
Qiaohui

    On Friday, 20 December 2019, 03:31:43 am GMT+8, 3dem-request at ncmir.ucsd.edu <3dem-request at ncmir.ucsd.edu> wrote:  

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Today's Topics:

  1. Re: Precipitation observed after making freeze substitution
      cocktail containing 5% water (Gibson, Kimberley)
  2. Re: Precipitation observed after making freeze substitution
      cocktail containing 5% water (Christopher Peddie)

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Message: 1
Date: Thu, 19 Dec 2019 15:08:07 +0000
From: "Gibson, Kimberley" <kimberley.gibson at yale.edu>
To: Christopher Peddie <Christopher.Peddie at crick.ac.uk>, Qiaohui Yang
    <qiaohui.yang at ymail.com>
Cc: "3dem at ncmir.ucsd.edu" <3dem at ncmir.ucsd.edu>
Subject: Re: [3dem] Precipitation observed after making freeze
    substitution cocktail containing 5% water
Message-ID:
    <BYAPR08MB4886C15DA68DA2CCB921FAF3EB520 at BYAPR08MB4886.namprd08.prod.outlook.com>

Content-Type: text/plain; charset="us-ascii"

It's not possible to make a stock solution of 20% Uranyl Acetate. Even making a 10% UA stock is not possible. At best, the solubility of UA is around 7-8 % in water. It's best to make a 5% stock solution, dissolved in water, for example, and add the quantity of 5%UA to the acetone. The precipitation of UA is likely due to the acetone as UA is not really soluble in acetone.
Best,

Kimberley Gibson

Research Associate, Charles Sindelar Lab

Dept. Molecular Biophysics and Biochemistry
Yale University
________________________________
From: 3dem <3dem-bounces at ncmir.ucsd.edu> on behalf of Christopher Peddie <Christopher.Peddie at crick.ac.uk>
Sent: Thursday, December 19, 2019 03:56
To: Qiaohui Yang <qiaohui.yang at ymail.com>
Cc: 3dem at ncmir.ucsd.edu <3dem at ncmir.ucsd.edu>
Subject: Re: [3dem] Precipitation observed after making freeze substitution cocktail containing 5% water

Hi Qiaohui,

Mix the osmium, water and acetone and cool to -20oC. Then add the uranyl acetate from a stock e.g. 20%. Cooling the mixture in my experience stops the uranyl acetate from precipitating out.

Best,

Chris

From: 3dem [mailto:3dem-bounces at ncmir.ucsd.edu] On Behalf Of Qiaohui Yang
Sent: 19 December 2019 08:39
To:
Subject: [3dem] Precipitation observed after making freeze substitution cocktail containing 5% water

Hi everyone!

We recently tried to make freeze substitution cocktail consisting of 1% osmium tetroxide, 0.1% uranyl acetate and 5% water but observed that the mixture turned slightly cloudy within 1-2 minutes. We tried to see if the precipitation would occur in the absence of osmium tetroxide, and we observed some cloudiness too after mixing uranyl acetate solution in water with pure acetone.

Just wondering if anyone has encountered similar problem and if so, would appreciate some tips on how to overcome this problem.

Thank you!

Best regards,

Qiaohui

The Francis Crick Institute Limited is a registered charity in England and Wales no. 1140062 and a company registered in England and Wales no. 06885462, with its registered office at 1 Midland Road London NW1 1AT
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Message: 2
Date: Thu, 19 Dec 2019 19:30:52 +0000
From: Christopher Peddie <Christopher.Peddie at crick.ac.uk>
To: "3dem at ncmir.ucsd.edu" <3dem at ncmir.ucsd.edu>
Subject: Re: [3dem] Precipitation observed after making freeze
    substitution cocktail containing 5% water
Message-ID:
    <VI1PR05MB5726A2F01FAB0FBE282F2FB1D6520 at VI1PR05MB5726.eurprd05.prod.outlook.com>

Content-Type: text/plain; charset="iso-8859-1"

Sorry, I should have been more specific: 20% in methanol.

________________________________
From: Gibson, Kimberley <kimberley.gibson at yale.edu>
Sent: 19 December 2019 15:08
To: Christopher Peddie <Christopher.Peddie at crick.ac.uk>; Qiaohui Yang <qiaohui.yang at ymail.com>
Cc: 3dem at ncmir.ucsd.edu <3dem at ncmir.ucsd.edu>
Subject: Re: [3dem] Precipitation observed after making freeze substitution cocktail containing 5% water