1 Only two, neptunium (93) and plutonium (94), occur in nature, and only as traces in uranium ores as a result of neutron irradiation.

2 The adsorption isotherm of neptunium on silica gel corresponds to the form of Langmuir isotherm.

3 In the spent fuel reprocessing process and for the environmental concerns, very strict control is required for determination of neptunium.

4 I'm not gonna talk too much about the but in the fertile to fissile chain if you look uranium 238 it captures the neutron, 239 by beta decay 239 goes to neptunium, neptunium to plutonium 239.

5 The method including the process of extraction chromatography and the mass spectrum measurement for the exact analysis of micro neptunium in the existence of large quantity of uranium is established.