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26 January 2013 | NewScientist | 21

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“Fish are promising models for human armour because they have already tested designs on themselves”

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Body armour to scale up by mimicking flexible fishIN DAYS of old, knights protected themselves in armour made up of tough, interlocking “scales”. This idea might one day be revisited, with future soldiers decked out in scales inspired by the almost impenetrable skin of the “dragon fish”.

This fish, Polypterus senegalus, is a tough beast whose strong bite and sturdy exoskeleton has kept its species going for 96 million years. Each of the scales that cover its long body is made up of multiple layers; when the fish is bitten, each layer cracks in a different pattern so that the scale stays intact as a whole (Nature Materials, doi.org/frkx9r).

Now we know how the different types of scales work – as a series of joints between “pegs” and “sockets”, allowing the fish to bend as it swims. This combination of flexibility and strength is perfect for human armour, says Swati Varshney of the Massachusetts Institute of Technology, speaking at the Society for Integrative and Comparative Biology meeting in San Francisco earlier this month. She and colleagues performed X-ray scans of scales, reconstructed the shapes and then worked out how they slotted together.

Scales near the flexible parts of the fish, such as the tail, are small and allow the fish to bend. Those on the side, protecting the internal

organs, are larger and more rigid. Their joints fit together tightly so that each peg reinforces the next scale rather than allowing it to flex.

The researchers created computer models of the different scale types and blew them up to 10 times their original size. Using a 3D printer, they printed a sheet of 144 interlocking scales out of a rigid material (an early prototype is pictured, below). The group hopes to eventually develop a full suit of fish-scale body armour for the US military that could replace the

heavy Kevlar armour currently used, but Varshney says this is still some way off. Such a suit would mimic the fish: rigid and strong across the torso and more flexible towards the joints.

These fish are promising models for human armour because they have already tested out engineering designs on themselves, says Dominique Adriaens of Ghent University in Belgium. Once the design is pinned down, researchers could use different materials to make suits. Ceramic, for instance, would provide heat protection; metal could prevent punctures. Sara Reardon n

Powerful prose stored in DNA

It is one of the most iconic speeches of all time, and now it has been immortalised in a very unusual way. A snippet of Martin Luther King’s “I Have a Dream” has been stored in the ACTG alphabet of DNA. Nick Goldman at the European Bioinformatics Institute in Hinxton, UK, and colleagues synthesised DNA to encode an eclectic mix of information, including an MP3 file of 26 seconds of King’s speech, and all 154 of Shakespeare’s sonnets. The team built on previous DNA-encoding techniques by adding error correction, allowing content to be retrieved with 100 per cent accuracy.

Bad grammar good, good grammar bad

Birthdays and the names of pets aren’t the only things that are password no-nos. Good grammar is now joining the list. Ashwini Rao and colleagues at Carnegie Mellon University in Pittsburgh, Pennsylvania, developed an algorithm that makes light work of cracking long passwords that are grammatically correct, even if they are mixed with numbers and symbols. The algorithm makes guesses by combining words into phrases, like “Ihave3cats”, for instance. The team’s paper on the technique is due to be presented at a privacy conference in San Antonio, Texas, next month.

Belting up helps cyclists find their wayThink of it as satnav for your waist. A vibrating belt for cyclists, which guides you to your destination, has proven successful in early tests. Wearing a “vibrobelt”, you simply choose a destination on your smartphone and set off. The belt then gives you directional nudges just before each turn. Developed by Haska Steltenpohl of the Intelligent Systems Lab at the University of Amsterdam, the Netherlands, the system is designed to help cyclists keep their attention trained on the road. In tests, cyclists who used the vibrobelt were much more aware of their surroundings than those who had to glance at the screen of a GPS device.

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