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From the great ocean liner's construction to its sinking to its discovery on the ocean floor, the key moments in the Titanic 's history. See our full centenary coverage here Thirty years of struggle and research have led to dozens of treatments for HIV/AIDS--although both a cure and an effective vaccine remain elusive Whether gas, liquid or solid; radioactive or stable; reactive or inert; toxic or in your vitamin pill, the 118 building blocks each has its own chemically idiosyncratic characteristics--and certain commonalities. See what makes your favorite element unique on this interactive periodic table
