Posts Tagged ‘metal’

Gold nanoparticles make plants glow in the dark

// November 8th, 2010 // 1 Comment » // How Things Work, Recent Research, The Realm of Bizzare

Image by Yellowcloud

Imagine if instead of having sensor lights to illuminate a garden path, you could line it with light-emitting plants. You could stroll along bio-luminescent flower beds, dancing in dappled moonlight and delighting in eerily lit peace, free from the shackles of electricity.

It could be possible with sea urchin shaped gold nanoparticles. Seriously, every time I turn on my computer the world gets more random. Sea urchins, I ask you. In any event, they’re called nano-sea-urchins.

Taiwanese researchers made a solution of gold nano-sea-urchins and dipped into it an aquatic plant, Bacopa caroliniana or blue waterhyssop. The nanoparticles moved into the plant over a day or so, and stayed there for about a month.

When exposed to UV light, the nanoparticles produced blue-violet light which encouraged the chlorophyll inside the plant to make red light. The result? An awesome glowing plant, just add UV.

It’s exciting stuff, there are a lot of excellent uses for light emitting things that work inside plants or animals. If the particles could be attached to a drug we could track exactly where the drug goes over the course of a treatment. You could attach it to proteins and find out where they are located inside a plant. Or you could just have a sweet glow in the dark plant in your house or garden.

Of course, you still need to have that UV source. But what’s wrong with having black light in your house or garden? Just think of the possibilities… You could drink tonic water every day, that stuff glows blue in black light because of the quinine.

Also, if you’ve ever wondered if black light can cause sunburn (as I recently have) here’s the low down. Black light is made of UV light which is close in wavelength to visible light, so it’s quite low energy. This counts as UVA, not UVB which causes most sunburns. Large amounts of UVA (such as those found in tanning beds) can cause skin cancer or premature aging, but the small amount contained in black lights is unlikely to do much damage.

ResearchBlogging.orgSu, Y., Tu, S., Tseng, S., Chang, Y., Chang, S., & Zhang, W. (2010). Influence of surface plasmon resonance on the emission intermittency of photoluminescence from gold nano-sea-urchins Nanoscale DOI: 10.1039/C0NR00330A

Hat tip to New Scientist

How aqua regia saved Nobel Prize medals from the Nazis

// October 25th, 2010 // 12 Comments » // The Realm of Bizzare

Aqua RegiaIt was a brisk April morning in 1940, and George was in a fix. In his hands were two Nobel Prizes illegally smuggled from Germany, while outside the lab Nazi’s swarmed the streets of Copenhagen. Denmark was now occupied by the Germans, and it was only a matter of time before they entered the Institute of Theoretical Physics and searched the building.

The medals belonged to Max von Laue and James Franck, Germans who had won Nobel Prizes in Physics some years ago. Their names where on the medals, and taking gold out of Germany was almost a capital offense, carrying a punishment not to be sneezed at. George was certainly not sneezing, but his palms were sweating as if he had a fever and his heart was pounding like a drum. There might be only hours until Nazis found the medals, and his neck would certainly be on the chopping block along with theirs.

What to do? Hide it in a hollowed out book as children hide sweets? No, there was no guarantee the books would stay put, they could be sent away or burned for all he knew. Bury it then? There simply wasn’t time, a freshly dug grave would only attract attention. No, it had to be changed, made unrecognisable, hidden in plain sight. Somehow. Think George, think. To every problem there must be a solution. Keep at it until a solution appears.

A solution! Of course! The gold should be hidden in solution! To wait out the war in a nondescript bottle sitting on a shelf. The worst that would happen is it would be thrown away, and if that was to be at least there would be no tell-tale engravings to point fingers.

George looked around the lab for the ingredients to a potent cocktail. Only one thing would dissolve gold. Aqua regia, a mix of three parts hydrochloric acid to one part nitric acid. Alone neither of these acids could change gold, very few things could. Gold was considered such a rare and beautiful metal for exactly that reason, because it was unchangeable and very stable. It would not rust like iron or turn green like copper. Strong, concentrated acids would not burn a hole in gold as they would other metals. Unless of course that acid was aqua regia, royal water.

In a large flask George combined the two acids quickly, his hands now dry and mind focused. The resulting mixture was colourless for an instant before turning faintly peach and then bright orange. With one held breath he dropped in the two gold medals.

Chemistry had always attracted George de Hevesy since he had first worked on radioactive isotopes thirty years ago. His work on them had uncovered many mysteries of biology, such as what part of a growing plant captures poisonous lead to protect the rest of the plant (the roots.) He was still a mover and shaker in the field, which was growing rapidly and had even entered the realm of human experimentation. If a man was injected with a radioactive isotope, where did it go, how long did it stay there and how was it excreted?

He was, in certain circles, quite famous. Perhaps in the near future he would be holding a Nobel Prize of his own.

But for now, these two Prizes were all he had, and they were getting smaller. The magic of aqua regia was in the way the two acids worked together.

Nitric acid had the power to take small amounts of solid gold and put it into solution. On its own it wouldn’t make any difference at all, because it would only allow a tiny amount of gold to be in solution at a time, with the gold being in equilibrium between solid and soluble form.

Hydrochloric acid, on the other hand, could supply its chloride atoms to convert gold to chloroaurate. But by itself it did nothing because it couldn’t get a grip on the gold to start with.

In aqua regia, the gold was put into solution by the nitric acid, and then converted to chloroaurate by hydrochloric acid. It pushed the equilibrium across, allowing the nitric acid to pull more and more gold into solution, where it was quickly changed into another form.

Once the reaction was complete, George sealed the flask and put it high up on the shelf. There it would stay until the war was over, and perhaps in brighter years he would return and extract the gold out of the solution, and return it to the Nobel Foundation where it could be recoined and returned. If brighter days ever arrived.

——

This be fiction based on a true story. George de Hevesy is credited with dissolving two Nobel Prizes in aqua regia and storing them during the second world war, where they remained unnoticed despite careful searching by the Nazis. The gold was later recovered and recoined, and presented back to the two owners. George de Hevesy won the 1943 Nobel Prize in Chemistry for his work on radioactive isotopes.






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