[3dem] [EXTERNAL] Re: K3 vs Falcon 4

[Grassucci, Robert]

Hi Yaser,
I agree with Sagar regarding the importance of zlp stability.  It is not a trivial thing to get the environment stable enough with respect to temperature and em fields to keep the zlp stable with the Bioquantum.  While the K3 has a shorter minimum frame time, for practical data collection the Falcon 4 may be catching up.  Another thing to consider is having one company to deal with can be less difficult than having TFS blaming Gatan and Gatan blaming TFS for the problems.  We have found this out on many occasions at Columbia.  Those are just a few things to consider.  I hope that helps.
Regards,
Bob

From: 3dem [mailto:3dem-bounces at ncmir.ucsd.edu] On Behalf Of Sagar Khavnekar
Sent: Thursday, January 21, 2021 4:34 AM
To: yaser hashem <yaser.hashem at u-bordeaux.fr>
Cc: 3dem at ncmir.ucsd.edu
Subject: [EXTERNAL] Re: [3dem] K3 vs Falcon 4

Hi Yaser,

Here @Martinsried we did a SPA comparison of Bioquantum + K3 vs TFS filter + F4 a while ago. I got similar resolutions to ~2 Angstroms with both. However, with Bioquantum + K3 I needed roughly double the number of particles.

Now for the speed, I get ~340 movies/hour with serialEM's Multihole multishot setup (without FFI on a G3 Krios). I think that is comparable to what one would get with K3 (Maybe Wim Hagen can correct me!).

When it comes to robustness, I would any present-day go for a TFS filter until there is better! In my experience over last year, once tuned the filter is stable for well over a month. The zero-loss peak moves only by ~ +- 1ev over a week (or two weeks!). Especially when we have one Krios and one Arctica in the same room with other hardware and offload servers. This allowed us to setup SerialEM without the need to communicate with the filter. (ZLP shift between record(165k/105k) and view(6.35k/411k) is only 0.2-0.3 ev)

Cheers,

Sagar

On Thu, Jan 21, 2021 at 9:40 AM yaser hashem <yaser.hashem at u-bordeaux.fr<mailto:yaser.hashem at u-bordeaux.fr>> wrote:
Dear colleagues,

At the Institut Européen de Chimie et Biologie (IECB) cryo-EM facility, we are looking to purchase either a Falcon 4 or a K3 DDD, in combination with and energy filter, on a Talos Arctica 200kV (that is already installed) or a Galcios 200kV (that will be purchased additionally), we were wondering whether anyone could provide some insight on the performance comparison between both devices in terms of speed and DQE. The device will be used for cryo-EM applications, SP and tomography, over a variety of molecular complexes ranging from several hundred kDa to several MDa, such as bacterial secretion systems, ribosomes and various membrane proteins complexes…
Both DDDs’ performances appear amazing, but would there be any other arguments to consider such as frequent bugs, robustness, installation requirements, etc…?

Thank you!

Best

Yaser

-------------------

yaser hashem (DR2)
Ph.D.
Group Leader

Inserm
Université de Bordeaux

Institut Européen de Chimie et Biologie, U1212
phone: +33 (0) 5 40 00 88 22
2 Rue Robert Escarpit
33600 Pessac
France

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--
Sagar Khavnekar
PhD student,
Department of molecular structural biology,
Max Planck Institute of Biochemistry,
Martinsried
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