Curium is a hard, brittle, radioactive silvery metal. It does not occur in nature and must be made in a nuclear reactor by neutron capture reactions from plutonium and americium isotopes. It tarnishes slowly in dry air at room temperature.
Romaine lettuce is a rich source of fiber and has very few calories, only 8 in a one-cup serving. In terms of vitamins, a cup of Romaine lettuce delivers more than 50% of your daily requirement for vitamin A, as well as significant levels of vitamin K and vitamin C.
Green leaf lettuce contains 105 percent of the daily value of vitamin K, while romaine and butterhead have 85 percent. Green leaf lettuce also delivers 10 percent of the recommended daily intake of vitamin C, which is twice the amount in romaine or butterhead lettuce. Iceberg has 3 to 7 percent fewer B vitamins.