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Tage Berglund of Vännäs, Sweden, is patenting a way of detecting tiny quantities of biowarfare bugs by quickly concentrating them in an air sample (WO 0218904). Current devices simply use a small propeller to blow suspect air into a detector. But in Berglund’s device the vanes of the propeller have inlet slits on their leading edges which connect to channels running down the rotor shaft and out through a fine nozzle. The tips of the vanes cut through the air at high speed, up to 50 metres per second, pulling in a full cubic metre of air every minute, making…