1 Routine screening of average-risk women should begin at age 50, instead of age 40. 2  Routine screening should end at age 74. 3  Women should get screening mammograms every two years instead of every year.4  Breast self-exams have little value, based on findings from several large studies. Routine screening of average-risk women should begin at age 50, instead of age 40. 2  Routine screening should end at age 74. 3  Women should get screening mammograms every two years instead of every year.
in chemical compound: Alkynes. Molecules that contain a triple bond between two carbon atoms are known as alkynes. The triple bond is made up of one Ï bond and two Ï bonds. As in alkenes, the Ï bonds constitute regions of increased electron density lying parallel to the carbon-carbon bond axis.
The general formula for an alkyne is C n H 2n-2 where n is the number of carbon atoms in the molecule. Alkanes are named by adding the the-yne suffix to the prefix associated with the number of carbon atoms present in the molecule.