Abstract: An apparatus is provided for measuring the concentration of a substance in a sample solution. The apparatus comprises first electrode means, second electrode means and an enzyme channel between the first and second electrode means. The enzyme channel contains an enzyme for catalyzing a reaction of the substance whose concentration is to be measured. In use, a known volume of the sample solution is presented to the first electrode means in a test solution including an excess of a mediator, one of reduction or oxidation of the mediator being coupled to the reaction of the substance. The first electrode means is arranged to ensure that the mediator is respectively completely oxidized or reduced, and also to remove any interferent species. The test solution is then passed through the enzyme channel so as to permit reaction of all of the substance present in the solution, whereby a quantity of the mediator is respectively reduced or oxidized.

Abstract: A method of electroluminescent panel manufacture in which a doped zinc chalcogenide phospher film--for example manganese doped zinc sulphide, is deposited upon an electrode bearing substrate in the presence of a hydrogen enriched atmosphere--for example a 90%:10% argon:hydrogen atmosphere. This is followed by rapid anneal treatment, the substrate being raised quickly to a temperature of 450.degree. C., or greater, and cooled rapidly. It is preferable that, prior to film deposition, the substrate is pretreated by baking in the hydrogen enriched atmosphere. An additional current density limiting film may be applied--a film of low resistance cermet material--for example silica/nickel 20% Ni in SiO.sub.2, or a film of amorphous silicon.

Abstract: A method in which a phosphor film of manganese doped zinc chalcogenide is produced by chemical vapor deposition from alkyl zinc vapor and the gaseous hydride of the chalcogen. The manganese dopant is introduced uniformly during deposition by decomposition of tricarbonyl alkylcyclopentadienyl manganese: ##STR1## where here R denotes the alkyl radical. Preferably dimethyl zinc and tricarbonyl methylcyclopentadienyl manganese are used.The phosphor produced may be one of the following manganese doped compounds: zinc sulphide, zinc selenide, zinc sulphur selenide, zinc oxy-sulphide, zinc oxy-selenide or zinc cadmium sulphide.