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Chemistry - Mark Lorch

This summer the journals Nature Chemistry and Proceedings of the National Academy of Science (PNAS) have both published papers on a fascinating chemical. Yet the chemical featured in these prestigious publications is so ubiquitous, so ordinary and so familiar that its formula was probably your first taste of chemical nomenclature – H2O, also known as aqua, dihydrogen monoxide or just plain old water. It could hardly be more simple: just a pair of hydrogen atoms accompanying one of oxygen. The result is an elegant V-shaped molecule which, in bulk, is the archetypal liquid covering 72 per cent of our planet.

So why are top-flight journals publishing papers on it? In short, because water is anything but ordinary. It’s easy to describe the structure of a single molecule, but this belies the complexity and strangeness that emerge when you look at water en masse. For example, water has unexpectedly high melting and boiling points; if you heat or cool water at 4°C it expands; and hot water can freeze faster than cold. Other liquids don’t do these things – we still don’t understand why water is different.

A great deal of time and computer power is used to model water: the hope is that if we can predict its known properties then a whole load of unknown characteristics will be revealed. That’s just what happened in the study published by PNAS; if the predictions are correct then just near water surfaces, particles with the same charge may start to attract one another. This is, of course, completely counterintuitive – a basic fact of chemistry is that opposite charges attract, whilst like charges repel each other.

So far, so weird, but why is this important? Quite simply, humans are bags of water living on a wet planet. Water meets other materials all over the place, from the air-water interfaces in oceans to water-membrane interfaces at the boundaries of your cells. If we want to understand the complex chemistry that goes on in and around water, then we have to understand the water itself. So experiments and simulations on the strange liquid emanating from your taps are bound to continue.

Mark Lorch lectures in Chemistry at the University of Hull

Physics - Ceri Brenner

The death of a giant star is the most extreme event that occurs in the universe. Known as supernova explosions, these colossal eruptions are vital for existence – they are where the key organic elements for life, planets and other smaller stars, such as our own Sun, originate. To paraphrase Carl Sagan, we really are all stardust. Astrophysicists study these events by observing the light that supernovas give off. The colour and brightness tell us what kind of energy is being emitted and how far the light has travelled. But observations of the supernova Cassiopeia A – 11,000 light years from the Earth – tell us that it gave off higher energy X-rays than expected, associated with there being a higher magnetic field present.

In order to understand this unexpected observation, a group of physicists recently replicated a supernova blast wave in the lab. Scientists fired three super-powerful laser pulses onto a carbon rod, heating it to several millions of degrees in only a few billionths of a second. This propelled a blast wave of carbon debris forwards into a region of low-pressure argon background. The wave then collided with a plastic grid, to mimic supernova remnants colliding with the clumpy bodies of planets and other interstellar material. Using flash imaging techniques, the scientists observed the wave crashing through the plastic grid and inducing turbulent motion into the expanding material. When this turbulence was introduced, an increase in the magnetic field – which explains that peculiar Cassiopeia A observation – was measured.

This elegant, simple experiment replicates the remnants of the most extreme event in our universe, one that occurred 11,000 years ago in a region of space 64 million billion miles away from Earth. And, of course, understanding what you see when you look at something – whether it is as ordinary as the light coming from your computer screen, or as extreme as the light from supernova explosion remnants – allows us to piece together the story of where we are and where we came from.

Ceri Brenner is a physicist who works for the Science and Technology Facilities Council

Biology - Lydia Leon

Since the 1950s, scientists have worked to eradicate malaria. The global rate of sickness and death has improved significantly, mainly through the use of insecticides and artemisinin-based antimalarial drugs. But malaria still causes an estimated 627,000 deaths a year, and, with the looming threat of resistance to insecticide and drugs, scientists are looking to increasingly elaborate weaponry.

On 10 June, scientists from Imperial College London published a paper in Nature Communications detailing an experiment in which they produced a genetically modified (GM) strain of mosquito that strongly favoured the production of male over female progeny. The team altered a naturally occurring enzyme, I-Ppol, which effectively chops up the X chromosome, making it non-functional in any sperm cell that carries it. This means that XY embryos (necessary for a male to be born) are heavily favoured compared to the female XX chromosome. Lab tests produced populations that were 95 per cent male – and since only female mosquitos are able to bite humans and therefore transmit the malarial parasite, the equation is simple: fewer females equals less malaria.

There’s another effect too. A population with such extreme sex ratios would probably become swiftly extinct in the wild. In other experiments, the release of GM males into a normal population of (caged) males and females led to the effective elimination of the population after just six generations – a cycle that takes around 12 weeks.

Clearly, human-induced extinction of an entire species poses big ecological and ethical questions. Although we have a long track record of contributing to extinction, only two diseases have ever been successfully targeted for eradication: smallpox and rinderpest. The work on malaria is still in its very early stages, and publication of the research has sparked healthy debate over the dangers and challenges of eradication programmes. But it marks a promising development in the battle against a disease we are far from conquering.

Lydia Leon is a PhD student at University College London’s Institute of Child Health