Around mid-century, Mendeleev began to develop the table of elements which helped in the discovery of new elements. In the last decade of the century, the discovery of radium by Marie and Pierre Curie, and the electron by Becquerel as well as observation of radioactivity in the laboratory, challenged Dalton's theory.
Medications Used to Treat ADHD. Stimulant medications commonly prescribed for attention deficit disorder include methylphenidate (Ritalin, Concerta, Metadate, Methylin) and certain amphetamines (Dexedrine, Dextrostat, Adderall). Methylphenidate is a short acting drug, and in older forms, had to be taken multiple times a day.
Methylphenidate (trade names Concerta, Methylin, Medikinet, Ritalin, Equasym XL, Quillivant XR, Metadate) is a central nervous system (CNS) stimulant of the phenethylamine and piperidine classes that is used in the treatment of attention deficit hyperactivity disorder (ADHD) and narcolepsy.ethylphenidate is a commonly prescribed psychostimulant and works by increasing the activity of the central nervous system. It produces such effects as increasing or maintaining alertness, combating fatigue, and improving attention.