Articles by: Mark

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.
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.
Then to cap it off show your audience the levitating frogs, and I promise they won’t forget diamagnetism after that.
Originally posted (in a slightly different form) at
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 2 comments 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