Copper-64 specific activity (the number of decays per second per amount of substance) and low yield through the Cu(n,γ)Cu reaction. At the University of Missouri Research Reactor Center (MURR) Cu was produced using high-energy neutrons via the Zn(n,p)Cu reaction in high specific activity but low yield. Using a biomedical cyclotron the Ni(p,n)Cu nuclear reaction can produce large quantities of the nuclide with high specific activity. Wilson’s disease is a rare condition in which copper is retained excessively in the body. Toxic levels of copper can lead to organ failure and premature death. Cu is used to study whole body retention of
Brain-to-body mass ratio highest for an invertebrate, although some ant species have 14%-15% of their mass in their brains, the highest value known for any animal. Sharks have one of the highest for fish alongside manta rays (although the electrogenic elephantfish has a ratio nearly 80 times higher - about 1/32, which is slightly higher than that for humans). Treeshrews have a higher brain to body mass ratio than any other mammal, including humans. Shrews hold about 10% of their body mass in their brain. It is a trend that the larger the animal gets, the smaller the brain-to-body mass ratio is. Large