The answer is this is good practice because if you’re putting injections into say, a vein and you were to inject a bit of air you’d get what is known as an air embolus.  The air bubble would float along the vein back to the heart; it would go through the right side of your heart and into your lungs and it would lodge in a blood vessel, which is a bit smaller than it is.  The result is that blood would then be stuck behind this bubble of air.  You’d have to wait for the bubble to slowly be absorbed back into the blood stream.  Probably pretty trivial if you just have one-off injections but if you have a lot of injections this could actually compromise the circulation through the blood.

The other point is if you’re having an injection into a muscle it’s pretty painful and the more volume you inject the more painful it is. If you inject a volume of air as well as injection material you’re just going to make the experience even more unpleasant so we try and avoid that where possible.

[Mark is referring to graphene transistors - transistors only one atom thick!]

Richard: Yes, I’m fairly sure it would because with all these components you’ve got electrons running through them. That gives you electricity, that’s the negative charge there. I think the lightning strike would disrupt them just as it would disrupt other electric components.

Chris: It might turn it into a sort of miniature barbecue because carbon burns beautifully in air so if you get enough current through it, it will get hot and presumably ignite?

Richard: Perhaps so.

I don’t think it's the same process as with menthol because dextrose is another term for glucose - that’s just sugar.  I think it’s in fact a clever chemical trick going on why his mouth feels cold when he sucks this sweet.  I think the reason is that to make the sweets fizzy and have that effervescent effect you mix them with sodium bicarbonate which is an alkali substance with some citric acid.  They’re both dry but when they dissolve in your mouth the water in your mouth makes most of these dry crystals become liquids and then they can react together and you get a neutralisation reaction which has an endothermic effect.  In other words it gets colder when you react an acid and an alkali together.  This makes your mouth feel colder.  I think it’s a chemical reaction, it’s one of these unusual reactions but it makes things get colder.