Articles by: Mark

Helium for balloons but none for my NMR

Our reserves of helium are finite and we’re running out. This may come as a mild disappointment to children everywhere but its really bad news for science.

My (and everyone else’s) NMR machines use liquid helium (at 3 Kelvin) as the coolant for their superconducting magnets. The same goes for MRI scanners and those cathedrals of science the particle accelerators like the LHC. And right now there’s a world wide shortage of helium which means that we may have to decommission some of our NMRs. Re-commissioning them will then cost 10s of thousands of dollars, plus it would require huge amounts of liquid helium to cool them down again.

We fill these instruments with liquid helium regularly, replacing the stuff that’s boiled off. The thing is that once that helium has evaporated off and into the atmosphere its gone. There’s no getting is back. So why don’t we bother collecting the boiled off helium? All we’d need to do is stick a balloon on top of the NMR machine, then a simple compressor could be used to turn it back into a liquid.

We don’t bother with this simple bit of recycling because there’s no immediate economic imperative. But hang on, didn’t I just say the reserves are limited, so surely helium is really expensive? Well it aught to be. According to Professor Robert Richardson, who won the Nobel physic prize in 1996 for his research on helium, a helium party balloon should cost $100. Instead they cost about 50 cents. The reason helium is sold well below its ‘real’ value is because of an odd law passed by the US congress in the 1996. Robin McKie explained some background in The Observer newspaper last month.

 In the 1920s the US decided helium would be a strategic resource. It realised that air power would be crucial in future wars, and assumed that these would be fought by airships that would use helium to float.

Then to cut costs in 1996 Congress passed a law mandating the U.S. helium reserve (the largest in the world by some way) be sold off by 2015, irrespective of market price. They set in stone the amount of helium that needed to be sold and so ever since they have been dumping it on the market.

This is a long term issue, but it doesn’t explain the immediate shortage. The problem here, as far as I can gather because our suppliers (BOC) aren’t telling us much, is that several of the worlds helium refineries are out of action. That, at least, was the case 10 months ago according to gasworld.  And they don’t expect things to improve until a new plant comes on line in 2013.

In the meantime it looks like there’s going to be a long queue for the remaining NMR machine.

25th April UPDATE :

Here’s the latest on the helium situation from BOC in the UK.

Magnetic grapes and NMR

When I was an undergrad I found NMR to be one of the trickiest techniques to get my head around. I think it was because the technique involves so many concepts that run counter to everything we’ve learnt before. After all in school we get told about ferromagnets and thats it. Then at uni suddenly someone is trying to tell us that actually there’s these other things called diamagnets and paramagnets, which means that even water is magnetic!

So now that I get to teach NMR I like to demonstrate diamagnetism right from the get go. Of course diamagnetism is really weak so you need a precision built, low friction setup. So I set about building one with ….

  • 2 grapes
  • A wooden skewer
  • A pin
  • An old film canister
  • A neodymium magnet. I get mine from emagnets. The stronger the better I use  one with 20 Kg pull.
Safety:
THIS IS REALLY IMPORTANT
The neodymium magnets are really powerful. So…
  1. Don’t let kids play with them.
  2. Don’t put them near your credit cards, phone, watch or any other electrical equipment.
  3. Don’t put 2 magnets anywhere near each other because they’ll fly towards one another, shatter and send chunks flying.
  4. If you have any medical implants don’t go anywhere near them.
  5. Read the safety instructions that come with the magnets.

The Build:

1. Push the 2 grapes onto either end of the skewer

2. Push the pin through the cap of the film canister, so that its pointing upward. Put the cap back on the canister.
3. This is the tricky but. You need to balance the skewer and grapes on the point of the pin.
4. Once you’ve managed that just put the edge of the magnet near one of the grapes and watch it spin.
There you go, the magnet repeals the water in the grapes and you have a nice down to earth demo of diagmanetism.
http://youtu.be/-zOzEvHmaK8
Then to cap it off show your audience the levitating frogs, and I promise they won’t forget diamagnetism after that.http://youtu.be/A1vyB-O5i6E
Originally posted (in a slightly different form) at http://www.t2ah.com/
By April 15, 2012 2 comments chemical education, fun, Uncategorized

3 year old singing the element song!

How about this then! A 3 year old singing Tom Lehrer’s the element song. Impressed? I am.

By April 13, 2012 1 comment fun

Taking a dinosaur’s name in vain.

This is my first post here so imagine my excitement when I came across this attention grabbing title from the JACS press room “Could “advanced” dinosaurs rule other planets?”. Something cool to write about on my first day! Excellent.

So of I trotted to look at the paper that was the bases of the press release. It has the more mundane title “Evidence for the Likely Origin of Homochirality in Amino Acids, Sugars, and Nucleosides on Prebiotic Earth”.

What’s this got to do with dinosaurs I thought? Best delve a little deeper into the paper.

The paper describes how the homochirality of sugars and amino acids in life on Earth may have originated from a small excess of L-amino acids and D-sugars in meteorites.  These then seeded early life, leading to their near total dominance in life as we know it.

Sorry, still no idea what this has to do with dinosaurs. The paper is pretty interesting in it self, but I still don’t get the press release. I’d best read a little further .

Ahh, it turns out that astronomers think that neutron stars may act like cyclotrons and produce circularly polarized light. And if this light has enough energy it could account for the deracemization of amino acids on asteroids.

Still no dinosaurs.

OK, maybe the link with dinos will be clearer in the conclusions.

“An implication from this work is that elsewhere in the universe there could be life forms based on D amino acids and L sugars depending on the chirality of circular polarized light in that sector of the universe …”

Wow, that’s pretty cool (no Dinosaurs though), but it goes on..

“ Such life forms could well be advanced versions of dinosaurs, if mammals did not have the good fortune to have the dinosaurs wiped out by an asteroidal collision, as on Earth”.

WHAT! THAT’S IT! Can somebody please explain to me how we get from homochirality of life to that!

Is it just me or does this smack of blatantly sticking an irrelevant reference to dinosaurs in the conclusion in an attempt to get some press coverage?

Maybe we could all try it. Here goes, the new conclusion from my last paper.

“In contrast, conventional NMR spectroscopy would require several months to collect the same quantity and quality of data. This massive boast in NMR signals could one day mean that we will be able to collect NMR spectra of scarce dinosaur proteins”

By April 11, 2012 11 comments chemical biology, opinion, science news