The Law of Conservation of Mass dates from Antoine Lavoisier's 1789 discovery that mass is neither created nor destroyed in chemical reactions. In other words, the mass of any one element at the beginning of a reaction will equal the mass of that element at the end of the reaction.
Antibiotic Gentamicin, when mixed with DePuy Orthopaedics bone cement products, may weaken the bond between cement and bone in joint replacement patients, and cause the prosthetic to slide off of the bone after the patient has suffered a great deal of pain and immobility.
Cement is a binding agent made of limestone and clay; it has no strength and cannot be used to construct sidewalks or walls. Concrete is an actual construction material made of cement, rocks, sand and water -- and it is useful for building driveways, walls and sidewalks.