While the method of chemical characterisation of a daughter was successful in the cases of flerovium and livermorium, and the simpler structure of even–even nuclei made the confirmation of oganesson (element 118) straightforward, there have been difficulties in establishing the congruence of decay chains from isotopes with odd protons, odd neutrons, or both. To get around this problem with hot fusion, the decay chains from which terminate in spontaneous fission instead of connecting to known nuclei as cold fusion allows, experiments were performed at Dubna in 2015 to produce lighter isotopes of flerovium in the reactions of 48Ca with 239Pu and 240Pu, particularly 283Fl, 284Fl, and 285Fl; the last had previously been characterised in the 242Pu(48Ca,5n)285Fl reaction at the Lawrence Berkeley National Laboratory in 2010. The isotope 285Fl was more clearly characterised, while the new isotope 284Fl was found to undergo immediate spontaneous fission instead of alpha decay to known nuclides around the "N" = 162 shell closure, and 283Fl was not found. This lightest isotope may yet conceivably be produced in the cold fusion reaction 208Pb(76Ge,n)283Fl, which the team at RIKEN in Japan has considered investigating: this reaction is expected to have a higher cross-section of 200 fb than the "world record" low of 30 fb for 209Bi(70Zn,n)278Nh, the reaction which RIKEN used for the official discovery of element 113, now named nihonium. The Dubna team repeated their investigation of the 240Pu+48Ca reaction in 2017, observing three new consistent decay chains of 285Fl, an additional decay chain from this nuclide that may pass through some isomeric states in its daughters, a chain that could be assigned to 287Fl (likely stemming from 242Pu impurities in the target), and some spontaneous fission events of which some could be from 284Fl, though other interpretations including side reactions involving the evaporation of charged particles are also possible.