An association football (soccer) match is presided over by a referee, whom the Laws of the Game give full authority to enforce the Laws of the Game in connection with the match to which he has been appointed (Law 5). The referee is oftentimes assisted by two assistant referees, and sometimes by a fourth official.
Barfoed's test. Barfoed's test is a chemical test used for detecting the presence of monosaccharides. It is based on the reduction of copper(II) acetate to copper(I) oxide (Cu2O), which forms a brick-red precipitate.
Uses For tuberculin. Tuberculin purified protein derivative (PPD) is used in a skin test to help diagnose tuberculosis (TB) infection in persons at increased risk of developing active disease. Tuberculin skin test is done by injecting tuberculin PPD into the surface layer of the skin. If the test is positive, a reaction will be seen at and around the place of injection or puncture. If the test is given using an injection, this reaction is usually a hard, raised area with clear margins.