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Re: How do you create extremely low temperatures?

GenJerDan9-Dec-20 22:37

GenJerDan

9-Dec-20 22:37

We used to have cryogenically cooled parametric amplifiers when I worked SATCOM. Temps down to 50K or so, I think, to get "low noise". Cold is pretty easy.

Tanks of helium just sitting there, when we weren't repressurizing the cryo pump.

Tanks just sitting there. Of helium.

So, of course, we used to fill up trash bags with helium, and send them floating over the Wall into East Berlin. Fun times. Laugh | :laugh:

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We won't shut up.
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Re: How do you create extremely low temperatures?

Maximilien10-Dec-20 0:28

Maximilien

10-Dec-20 0:28

Even if the vaccine must be stored at very low temperature, it can be stored a regular freeze temperature for while.

Here's one reference (in French) : Pourquoi le vaccin de Pfizer n'aurait finalement pas besoin d'être stocké à -70 °C

"...D'abord, le vaccin de Pfizer supporterait -20 °C pendant quinze jours et même 2 °C à 8 °C pendant cinq jours, d'après nos informations..."

(google translate)

"...First, Pfizer's vaccine would withstand -20 ° C for fifteen days and even 2 ° C to 8 ° C for five days, according to our information."

I'd rather be phishing!

Re: How do you create extremely low temperatures?

W∴ Balboos, GHB10-Dec-20 3:26

W∴ Balboos, GHB

10-Dec-20 3:26

Heat pumps (normal refrigeration) don't need to have the sink at a lower temperature than the source to keep cooling. Think of air conditioning your house: it's much hotter outside than inside but the pump still can move heat - it just gets less and less efficient (there's an equation for that).

Now, for the COVID vaccine, they temperature is that of Dry Ice (solid CO₂ for the newer generations). To make it, they compress the CO₂ until it liquifies and let that cool by releasing heat to the surroundings - and then they release the pressure and it gets extremely cold, much of it solidifying and the rest returning to the gas phase (now at ambient pressure). Because of this method, the solid is more like snow and is compressed into blocks (opaque white). You can do this yourself if you've a CO₂ fires extinguisher to waste: if turned upside down it will attempt to empty its contents (liquefied gas under pressure) and you'll get some dry-ice snow.

At the extreme end, towards absolute zero (0K = -273C), like liquid helium at 4K, extremely compressed helium is cooled, like the routine for dry ice but cooled to liquid nitrogen temperature, above and when allowed to expand some of it liquefies. It is a particularly energy intensive process as the tiny little helium atoms have virtually no attraction towards one another (compared to any other element). It is a super-fluid and does some creepy stuff like climb out of its container. It's generally difficult to store for any period of time (and dangerous in that it's constantly boiling and creating pressure). I didn't use it but it was used by some of the chemical physicists in my lab. It was ordered so it arrived within a day of when it was needed or it would pretty much be gone. It's stored in specialized dewers (basically thermos bottles).

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Re: How do you create extremely low temperatures?

Marc Clifton10-Dec-20 5:17

Marc Clifton

10-Dec-20 5:17

Quote:
Dry ice is made by liquefying carbon dioxide and injecting it into a holding tank, where it's frozen at a temperature of -109° F and compressed into solid ice.

Hey, maybe the vaccine will help with global warming too!

Oh wait, the dry ice simply evaporates. Frown | :(

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Well, I'm at home again.

OriginalGriff9-Dec-20 5:18

OriginalGriff

9-Dec-20 5:18

And if I'd known they would take this long I'd have come home and the gone back to get her!

But ... using the phone as a WiFi hotspot worked well, and the Surface Go 2 survived 5 hours of youtube, surfing, book reading and a short video with about an hour to go in the battery. Not too bad, but I think the older Surface 3 Pro would have done better (until it bricked itself by refusing to talk to it';s charger any more of course). The phone coped brilliantly, using less than 25% on a couple of calls and 5 hours as a WiFi hotspot. Good going!

08:30 the appointment was, 10:30 they actually saw here and started to prep for the procedure. 13:30 they called me to say Herself would be free to go at 14:00. 14:30 we go out of the building ...

The good news was the Welsh Rush Amble: despite peak traffic time we only stopped in traffic once on the way there, and that was at a set of red lights. So much easier than the same distance journey would have been when I worked inside the M25 (LOndon Orbital Motorway). Back then it could take an hour to get through Hindhead Lights ... Laugh | :laugh:

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Re: Well, I'm at home again.

Richard MacCutchan9-Dec-20 5:49

Richard MacCutchan

9-Dec-20 5:49

OriginalGriff wrote:
Hindhead Lights

Yes, I used to commute through there for a number of years. Absolutely deadly on a Friday evening. All replaced now by a nice tunnel under the hogsback.

Re: Well, I'm at home again.

OriginalGriff9-Dec-20 5:52

OriginalGriff

9-Dec-20 5:52

Gawd yes. And all it ever took was one idiot to do something really stupid and you could be delayed for ages.

About once a week on average. Sigh | :sigh:

The first shoe drops

Gerry Schmitz9-Dec-20 5:10

Gerry Schmitz

9-Dec-20 5:10

Quote:
British regulators warned Wednesday that people who have a history of serious allergic reactions shouldn’t receive the new Pfizer-BioNTech vaccine as they investigate two adverse reactions that occurred on the first day of the country’s mass vaccination program.

You'll soon have (the agony of) multiple choices.

It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
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