Thus the net effect is the disappearance of radioactive elements, which is even better, engineering and technology wise.
Only the radioactivity disappears. 63Ni goes to 63Cu all the rest information of the paper is highly speculative - especially the change of isotopes they measure. Sonotrode/containers air etc contain always traces of all elements they measure.
They claim to measure about 2400 count's/s what corresponds to an effective 63Ni amount of 1 micro mole at most and this calculated with a lot of goodwill.
Before we can draw any conclusions they should do the same experiment with inactive Nickel and the same electrode/sonotrode (not the identical one). Everything done in a closed system.
They also give no serious data, what would include all detailed masses of the original elements found before/after in a control and the experiment.
My impression is that they just look for a cheap explanation of a fantasy model.
Nevertheless 63Ni is a good candidate to investigate as it has the exact same outer 4D quantum structure as 40K, what is claimed by other to follow a transmutation during sonication.