A Chameleon’s Colourful Secret


Chameleons are definitely one of the most fascinating creatures on Earth, and their characteristic colour changes, to camouflage themselves or gain the attention of their mates, can impress both kids and adults alike. As if their ability to change their appearance into anything they’d like wasn’t enough, the mechanism by which they do so could also be unique and worth some credit.

In nature, colours are usually produced by pigments: substances that have a specific colour. For example, our skin gets tan because of a pigment called melanin which darkens it. In chameleons, it was originally thought that they showed one colour because a pigment of that same colour covered their skin, and when they wanted to change colour, a pigment of a new colour just substituted the original one. But it has now been discovered that their colour change, contrary to popular belief, had nothing to do with pigments. It’s actually all because of crystals.

A chameleon’s skin has an outer layer full of specialised cells called superficial iridophores, which have tiny guanine crystals embedded that can reflect light at different wavelengths and so produce different colours. Guanine not only plays an important role for this process, but is also one of the four bases in our DNA, which code for all the substances in our body. When the chameleon wants to change colour, it simply twist these cells around so the distance between crystals changes, which causes the reflection pattern, and subsequently the colour it produces, to change.

chameleon coloured

Chameleon’s can express a wide variety of colours thanks to guanine crystals

This is a very smart design which saves the chameleons a lot of energy and resources on producing and transporting the pigments around. If the animal wants a bluish colour, it just needs to push all these crystals together. For a reddish/yellow colour, just spread them out.

The only thing yet to be discovered is how the chameleons actually modify the superficial iridophores’ shape. In the experiment they carried out to test this new theory, they used salt water to expand and contract the cells and see what effect this had on the colour. But the natural process in chameleons is not necessarily chemical, it could be mechanical. Finding out which one it is is the team from the University of Geneva’s new objective.

Either way, discovering the truth behind this ingenious technique is not only an interesting fact to know about, but could also have real-life applications, for example, in developing computer screens.

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FrankenBattery


We live in a world where energy is currency. Wars are fought over petrol and other fossil fuels, whilst millions of people work tirelessly to provide alternatives like solar energy to prevent global warming and provide a greener and safer future for our planet.

Since energy is so important, a lot of research is put into it, yielding fascinating results. The most recent one has to do with lithium-sulfur batteries. Their mechanism is not new; in fact, it has been known for decades. But there have always been practical imperfections with their functioning. Scientists seem to have discovered a way to solve them and create one of the most useful batteries to date.

lithium sulfur battery

Lithium-sulfur cells coould soon power your phone, your computer, your car, etc…

Normally, this battery consists of two electrodes, one made of lithium and the other of a carbon-sulfur compound. When the battery works, ions from one electrode move to the other through the electrolyte, creating a current. Unfortunately, lithium can react with the sulfur and form lithium sulphides, which dissolve into the electrolyte and slowly use up the sulfur electrode. Up until now, the solution had been to add some other chemicals, like titanium oxide or manganese dioxide, which would stabilise the sulfur and prevent it from dissolving so easily in the electrolyte. But the method which seems the most promising is actually the most unexpected: adding DNA.

Yes, you read that right. DNA, deoxyribonucleic acid, the organic molecule that codes for all of our characteristics actually improves lithium-sulfur batteries. DNA is made of oxygen, nitrogen and phosphorus, and luckily for material scientists, all these elements easily bond with sulfur. This makes DNA ideal for trapping sulfides, preventing them from dissolving in the electrolyte. In turn, it improves the efficiency of these batteries by almost 3 times. Even better: DNA is cheap and biodegradable, and a very small amount is needed for it to improve the battery’s performance.

The interest in this specific type of batteries is not unjustified. They have a high energy density (can deliver up to 3 times as much energy as lithium ion cells), are cheaper to produce and greener for the environment. It is therefore not strange that scientists are trying to do as much work as possible to help improve this technology. However, the battery world is a slow one, and although an idea may look good in the lab, it is harder to extrapolate that into the industry. But keep your hopes up! Lithium-sulfur batteries could very well substitute the widely used lithium ion cells in only 15 years, with original ideas like the one exposed on this article to push it through.

Nobel Prizes 2014: Part 2


Today, with Jean Tirole being awarded the Economics Nobel Prize, was the last day of the Nobel Prize award season. Last week, we looked into the winners for physiology and physics, so we still have one scientific award to investigate: chemistry.

The 2014 Nobel Prize for Chemistry went to… Eric Betzig, Stefan W. Hell and William E. Moerner for “the development of super-resolved fluorescence microscopy”.

Microscopes are a valuable tool for all scientists, from physicists examining subatomic particles to biologists investigating cells. But for many years, it was believed that microscopes were limited in how much magnification they could provide. The smallest they could go was 200 nanometres, or at least that was what they though until these laureates came along. The key to their innovation was brought by the use of fluorescence to increase resolution.

Hell created a mechanism called STED (Stimulated Emission Depletion) to take higher resolution pictures which involved laser lights. As an example, he used an E. coli bacterium coated with fluorescent molecules and a special microscope which emitted two tiny rays of light. One of these excited some molecules so certain parts of the bacterium glowed, whilst the other did the opposite, and made the sample duller. This might seem contradictive, except the centre of the convergence was left to shine, so only a small area was illuminated. A picture was then taken of the glowing part, and the procedure repeated at many angles. Combining the pictures taken, he was able to form an image of an unprecedented resolution.

microscope

Imagine being able to look deeper into cells – it’s possible now thanks to this year’s Chemistry winners

This is close to what Moerner and Betzig did. They used fluorescent proteins, which could be activated by short pulses of lights. They shone these onto a different part of the sample every few milliseconds, so they only glowed for a short period of time. By superimposing the images of the lighted parts, they were able to capture individual molecules in images! This amazing method is now called single-molecule microscopy and has been used in a wide variety of studies, from HIV research to gene modification.

Thanks to these men’s work and dedication towards science, we can now see deeper into our world than we have ever done before. A few years ago, we could only look at individual cells, never inside of them. But now, we can actually see what they contain, into their small organelles like mitochondria and the Golgi body that allow cells to do all the complex processes that keep us alive. Not only this, we can actually investigate individual molecules from chemicals, advancing the field of chemistry. Their contribution to our knowledge pool is immeasurable, both directly and indirectly, and for this, they are well-deserving of the Chemistry Nobel Prize.

Alien Molecule


isopropyl cyanide

Isopropyl Cyanide, the molecule found light years away that could tell us about how we were formed

Where did life come from? Are we alone in the universe? These are common questions which scientists from all around the world are trying to answer everyday, and that have yet to be answered. But we could be closer to understanding the origin of life thanks to the combined work of researchers at Cornell University, the Max Planck Institute, and Cologne University in Germany, who have discovered a complex organic molecule deep in the heart of the universe.

The molecule itself is isopropyl cyanide and consists of carbon, hydrogen and nitrogen. Compared to other chemicals floating around in space, it’s special because it’s branched, rather than straight, and larger than usual. In fact, it may be the largest molecule ever detected in a region of space without a fully formed star.

Obviously, scientists didn’t go all that way themselves to retrieve a sample of the compound to analyse it, and sounding rockets don’t go that far. Instead, they used ALMA, a set of radio telescopes in Chile which can detect microwaves produced by chemicals many light years away, to scan an area of space an examine its chemical makeup. Surprisingly, they found isopropyl cyanide, 400 light years away, in gas cloud Sagittarius B2, where a star is in the process of being formed.

It is not a clear sign or of life, so all you crazy UFOs enthusiasts can calm down, but it is an interesting discovery. Its complex structure, although simpler, is reminiscent of amino acids, the building blocks of life. These are often found in meteorites, so a popular theory is that the ingredients for life were formed in space and then drifted onto our planet, where they became ‘alive’.

Finding out more about how this chemical is formed and the conditions under which it is produced could be used to paint a better picture of how life managed to originate in our planet.

 

Blender Potion for Graphene


Graphene is quickly rising to become one of the most useful substances on Earth. It is an extremely hard substance, an excellent conductor of heat and electricity, and only 1 atom layer thick. Even better, it is as abundant as graphite, the black substance found in pencil leads, as graphene stuck together in many layers is in fact graphite.

But up until now, there had been a problem with this amazing material: its production. Obtaining some graphene is relatively easy: you get a piece a graphite from any pencil, and using some tape, stick and unstick it to the surface of the graphite continuously. This way, you will end up with a very small of graphene. This surprising method was discovered by two students at the University of Manchester: Andre Geim and Konstantin Novoselov, who won the Nobel Prize for Chemistry precisely for this technique.

graphene

This is graphene, a layer of atoms made of hexagonal carbon rings

The problem is that although this tape method works perfectly fine to produce some graphene, it’s not an efficient way to manufacture amounts large enough to meet the demand for this product. So scientists have been working non-stop to find a solution to their problem, and indeed they have found a very curious one.

Just as the original technique, its fairly straightforward. You just need some graphite, some water, soap and a blender. Now just add it all into the blender and turn it on. After a few seconds of work, you have produced a decent amount of graphene. The blades manage to cut between the layers of graphene in graphite and produce individual graphene.
The bright side of this process is that it produces 5 grams of graphene an hour, whilst previous methods produced only half a gram an hour. On the downside, however, is the fact that its not really as easy as this, and to get the best results you need to use more sophisticated substances and to get a decent amount the experiment would have to be scaled up.

It is still an enormous improvement compared to the previous methods that will for sure make this outstanding material more approachable, and all the technological revolutions it will bring closer to our reach.