Carbon nanotubes and nanofibres, however, seem to be able to absorb hydrogen well, even at room temperature.

ECONOMIST: Space-age soot

But Dr Kirczenow and Dr Rego reckon that some cooling should take place even at room temperature.

ECONOMIST: Microelectronics

Above all, they can be made intense even at room temperature, whereas competing technologies require bulky, expensive cooling systems.

ECONOMIST: Lasers

The men had been detained in a room with no ventilation, even though the average temperature in the city at this time of the year is higher than 38C, it added.

BBC: Mali conflict: 'Tortured Tuaregs die in Bamako jail'