31. It is the ninth product of the neptunium decay series as a daughter isotope of actinium-225. 32. Physicist Philip Abelson, a co-discoverer of neptunium , served as editor from 1962 to 1984. 33. There are 19 isotopes of neptunium with mass numbers from 225 to 244; they are all highly radioactive. 34. Since then, most neptunium has been and still is produced by neutron irradiation of uranium in nuclear reactors. 35. Four atoms of neptunium make up a unit cell, and the Np Np bond lengths are 276 pm. 36. This occurrence in neptunium compounds is somewhat surprising because they often exhibit strong magnetism, which usually destroys superconductivity. 37. The U . S . reported on the status of consideration of possible additional controls on americium and neptunium . 38. As Np also symbolises the element neptunium ( atomic number 93 ) one should use this abbreviation with care. 39. Following the lighter neptunium , plutonium, and heavier curium, americium was the fourth transuranium element to be discovered. 40. Plutonium also exhibits valence states between 3 and 7 inclusive, and thus is chemically similar to neptunium and uranium.
