Английский язык: Аннотирование и реферирование текста

179 20 years' worth of effort, there is still no definitive theory of how or why the copper oxide compounds superconduct. These compounds also pose a multitude of physical challenges. Initially they were hard to make in either high-purity or single-crystal form, making the measurements of their fundamental properties diffi- cult. In addition, the synthesis of wires is not easy: unlike the intermet- allic superconductors, the individual grains that make up a piece of one of these oxides have to be aligned with respect to one another for the wire to have useful engineering properties. These problems left re- searchers and engineers wishing for a substance with the somewhat eas- ier material properties of the intermetallic superconductors that also had a critical temperature significantly higher than 20 K. By the dawn of the new millennium, then, the superconducting state could be achieved with varying degrees of ease and expense. In the oxides, superconductivity was practical near 77 K, which can be reached relatively easily by bathing the material in liquid nitrogen. The older intermetallic compounds such as triniobium tin were being used in the laboratory and as medical magnets operating at temperatures closer to 4 K, which can be reached with liquid helium. The discovery in 2001 that the simple intermetallic compound magnesium diboride superconducts at 40 K, about double the tempera- ture of the other intermetailics, was almost exactly what the doctor (or in this case, engineers) had ordered. Notes to the text : Coolant – охладитель , охлаждающее вещество Properties – свойства Mercury – ртуть Slowly but surely – медленно , но верно Seemed to be stuck – казалось застыла Slew – множество , масса BCS theory – ( авторы теории , объясняющей механизм сверх - проводимости в металлах John Bardeen, Leon N. Cooper, J. Robert Schrieffer)