Period 4 element be dangerous in large enough quantities due to its radioactivity. Nickel (Ni) is an element in period 4, between cobalt and copper. Nickel is rare in the Earth's crust, mainly due to the fact that it reacts with oxygen in the air, with most of the nickel on Earth coming from nickel iron meteorites. However, nickel is incredibly common in the Earth's core; along with iron it is one of the two main components. Nickel is an important component of stainless steel, and in many superalloys. Copper (Cu) is an element in period 4, between nickel and zinc. Copper is
CU-2010 and CU-2020 a substrate, due to its peptide-like properties. After intravenous infusion, CU-2010 is quickly cleared as it has a half-life of about 20 minutes (in rats and dogs). Polymerization and covalent attachment of polymer chains of polyethylene glycol (PEG) or pegylation results in the formation of CU-2020, which has a longer half-life of 45 minutes. The advantage of the short half-life of CU-2010 is that it allows it to work in an “on-off” mode, hence being able to adapt to the haemostatic situation of the moment. CU-2010 and CU-2020 have the ability to inhibit plasmin to a similar extent as aprotinin,