March 24, 2006 -- A torn ACL in the knee can be replaced -- but it can't be healed.A new technique now shows promise to change this. Doctors long ago gave up trying to repair a torn ACL (anterior cruciate ligament).arch 24, 2006 -- A torn ACL in the knee can be replaced -- but it can't be healed.
In chemistry, pH (/piËËeÉªtÊ/) is a numeric scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the logarithm to base 10 of the molar concentration, measured in units of moles per liter, of hydrogen ions.
Calculating pH. The pH definition we use today is the negative logarithm of the hydrogen (H+) ion activity in a given solution. Read What does pH stand for. Note I say hydrogen (H+) ion activity, not concentration.