Lab Talk

We ask four researchers to tell us about the recent papers that have excited them the most.

Left to right: Deanna D’Alessandro, Russell Keast, Jesse J. Sabatini and Ben Eggleton.

Crystalising a new Vision

By Deanna D’Alessandro

Chemists making molecules face a problem – you can’t see atoms, so how can you know what you’ve made? X-ray crystallography allows you to “see” atoms in molecules by taking a snapshot. It is the most reliable method to determine structure in the chemist’s toolkit. But as its name suggests, it only works with molecules that form crystals, which can be difficult. Some molecules refuse to form crystals at all.

This paper shows how a sponge-like material called a metal-organic framework (MOF) can help. The MOF can absorb nanogram amounts of a molecule from solution into its highly regular pores, holding these guests firmly in place as if they were a kind of crystal. X-rays are able to reveal the molecular structure of the absorbed guest with atomic resolution. This exciting technique provides a convenient tool to analyse molecular structures for applications such as food science, drug discovery and forensics.

Paper: X-ray analysis on the nanogram to microgram scale using porous complexes, Nature, 2013, vol 495, p461.

Upping the taste of low fat foods

By Russell Keast

When it comes to the ideal diet, ice-cream, marbled streak and cream cakes are definitely off the menu. But for some people, a low-fat diet rather destroys the pleasure of eating.

A recent study in mice reveals why. When the mice consumed fat, their intestinal cells released a compound that tickled the pleasure centre of the brain. The compound, named oleoylethanolamide (OEA), triggers the release of dopamine in the reward areas of the brain, creating a pleasurable experience. However, some individuals produce less OEA after consuming fat, and so get a smaller dopamine hit.

The researchers hypothesised that those individuals over-consume fat to raise their levels of OEA in a subconscious attempt to normalise dopamine levels and feel satisfied. This idea suggests that adding OEA to low-fat foods could be the answer to helping people feel satisfied and sticking with a low-fat diet.

Paper: A gut lipid messenger links excess dietary fat to dopamine deficiency. Science, 2013, vol 341, p800.

Cleaner Green Pyrotechnics

By Jesse J. Sabatini

Fireworks have a dark side. As they burst, they spread pollutants far and wide. Green-coloured fireworks are among the worst.

Fireworks need two key ingredients to make a bang: an oxidiser and a fuel. Traditional green-coloured pyrotechnics use a barium-nitrate oxidiser that generates barium chloride as it burns. Barium is a heavy metal, with toxic combustion products. We have previously created green pyrotechnics powered by a much cleaner mixture: a potassium-nitrate oxidiser and a boron carbide fuel. This generates green-light-emitting boron dioxide, but the potassium combustion products add white light, diluting the effect.

This paper describes an energetic, potassium-free oxidiser called tris-(2,2,2-trinitroethyl) borate, which also releases boron dioxide as it burns. Combining this oxidiser with a boron-based fuel should yield metal-free pyrotechnics with a clean, bright, pure green light.

Paper: Polynitroethyl- and Fluorodinitroethyl Substituted Boron Esters, Chem. Eur. J., 2013, vol 19, p12113.

Computers at the speed of light

By Ben Eggleton

Photonic chips are a sleek new form of computer chip that use photons of light rather than electrons to transmit and process information. Just as light whizzes far more efficiently through a fibre optic cable than electrons can chug through copper, photonic chips are faster, and potentially greener and smarter, than traditional electronic ones.

Guiding light efficiently around a photonic circuit without scattering it remains a challenge, but a new paper suggests a way to do it. In the world of electrons, researchers have discovered a strange new family of materials called topological insulators, in which electrons cannot flow through the interior but do flow smoothly along the surface. This paper demonstrates the first equivalent material for light: a photonic topological insulator, created using nanostructured photonic materials.

Photonic circuits based on this concept offer fundamentally new ways to control light at circuit-scale, paving the way to new applications.

Paper: Photonic Floquet topological insulators, Nature, 2013, vol 496, p196.

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