[3dem] K3 vs Falcon 4

[Sagar Khavnekar]

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>
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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