Low Temperature

Boy , it is cold around here !

Superconductors
In 1911, Dutch physicist K. Ownes discovered that when the metal mercury is cooled to an extremely low temperature, its electrical resistance is reduced to an insignificant amount. It became a highly efficient electrical conductor, or superconductor. Ownes lowered the temperature to 4 K, just above absolute zero. It was an important discovery but such low temperature could only be achieved with great difficult and at great cost.

Many attempts were made to find superconducting, materials at higher temperature but they all failed until 1986. Two physicist in the IBM research laboratory in Zurich, Switzerland, K Muller and J Bednorz, found that certain ceramics becomes superconductive at much higher temperatures than before. They created one at 35 K. A new class of materials called high-temperature superconductors (HTS) was born.

Cold Treatments
Science fiction became reality in the operating theatres of modern hospitals. This was true when doctors cooled the body of a patient to state of near death in order to operate on him without his blood flowing. The patient is then in a physical state called hypothermic arrest. His heart stops beating and blood circulation comes to halt. The patient survives this condition under the controlled circumstances because the brain does not need oxygen for a longer time at low temperatures. This techniques has been used for removal of brain aneurysms in which the blood vessel wall puffs up like a ballon. The resulting pressure on the brain causes paralysis and eventually death

Cryosurgery uses extreme cold to destroy diseased tissues. This has been employed for years on skin tumours and now it has been extended to other forms of cancer. A thin probe is inserted into the cancerous organ, e.g, liver. Liquid nitrogen is allowed to flow through the probe, thus freezing the tumour and destroying the cancer cells. The survival rate for this technique