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BBC Radio 4 - 92 to 94 FM and 198 Long WaveListen to Digital Radio, Digital TV and OnlineListen on Digital Radio, Digital TV and Online

Science
LEADING EDGE
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Thursday 21:00-21:30
Leading Edge brings you the latest news from the world of science. Geoff Watts celebrates discoveries as soon as they're being talked about - on the internet, in coffee rooms and bars; often before they're published in journals. And he gets to grips with not just the science, but with the controversies and conversation that surround it.
radioscience@bbc.co.uk
LISTEN AGAINListen 30 min
Listen to 31 October
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GEOFF WATTS
Geoff Watts
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Thursday 31 October 2002
Limestone subjected to a sodium sulfate test.                       The stone on the right has been treated with a polymer solution and remains undamaged.

Saving the medieval walls of Rhodes from salt rot

This week Geoff Watts talks to George Scherer , Professor of Civil Engineering at Princeton University about a new way of preventing salt deterioration in the stone of historic buildings. He shows Geoff a particularly manky salt-attacked brick wall in the basement of one of the campus buildings and then goes onto talk about a new preventative treatment he's devising to combat the problem generally. It's based on an understanding the physics of salt damage which his group have analysed.

Salts seep into stonework when it rains. As the water evaporates, salt crystals precipitate within the pores of the stone, there's a repulsive force at a microscopic level between the tiny crystals and the surrounding sand or limestone grains. As a result, very large strains build up within the fabric of the stone and it begins to crumble away.

Having worked out the physics, the Princeton team have been screening chemicals (polymers) which interfere with this repulsive interaction. The polymer lightly coats the surfaces of the grains defining the pore spaces and neutralises the repulsive force between salt and stone grains. The molecule is attractive to both the salt and the rock grains. Next year, they are going to try out the solution on test sections of the medieval walls around Rhodes in Greece which are crumbling away like nobody's business because of 800 years of continuous salt attack. Salt damage to buildings in Mediterranean area is a severe problem because of all the salt from sea spray in the air.

West Nile Virus

After reports this week that birds showing signs of exposure to the West Nile Virus have been found in the UK , Geoff talks to Prof Andre Dhondt at Cornell University , about the transmission of the virus between mosquitoes, birds and people elsewhere in the world such as the United States and Eastern Europe .

'Sun Rings'

Premiered last weekend by the Kronos Quartet at the University of Iowa, 'Sun Rings' is a new piece of music inspired by the 'sounds' of plasma waves in around Earth and the planet Jupiter. Geoff talks to the composer Terry Rileyand astrophysicist Prof Don Gurnett of the University of Iowa ,who is the scientific advisor for the piece. His large collection of cassettes of plasmawave sounds were the material inspiration for the work, and include the radio waves generated by lightning flashes in Earth and Jovian atmosphere and the dawn chorus-like recordings from the radiation belts around Earth and Jupiter.

The Kronos Quartet will be performing 'Sun Rings' at London's Barbican Centre on 22nd March 2003.



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