 In his 1961 book "The Atom and its Nucleus", Gamow proposed representing the periodic system of the chemical elements as a continuous tape, with the elements in order of atomic number wound round in a three-dimensional helix whose diameter increased stepwise (corresponding to the longer rows of the conventional periodic table).Gamow continued his teaching at the University of Colorado Boulder and focused increasingly on writing textbooks and books on science for the general public.After several months of ill health, surgeries on his circulatory system, diabetes and liver problems, Gamow was dying from liver failure, which he had called the "weak link" that could not withstand the other stresses.