| hydrogen dioxide | <chemical> Hydrogen peroxide is produced by vertebrate phagocytes and is used in bacterial killing (the myeloperoxidase halide system). (05 May 1997) |
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| silicon dioxide | <chemical> Silica. Transparent, tasteless crystals found in nature as agate, amethyst, chalcedony, cristobalite, flint, sand, quartz, and tridymite. The compound is insoluble in water or acids except hydrofluoric acid. Chemical name: Silica (12 Dec 1998) |
| nitrogen dioxide | <chemical> Nitrogen oxide (no2). A highly poisonous gas. Exposure produces inflammation of lungs that may only cause slight pain or pass unnoticed, but resulting oedema several days later may cause death. It is a major atmospheric pollutant that is able to absorb uv light that does not reach the earth's surface. Pharmacological action: oxidants, photochemical, poisons. Chemical name: Nitrogen oxide (NO2) (12 Dec 1998) |
| sulfur dioxide | <chemical> A highly toxic, colourless, nonflammable gas. It is used as a pharmaceutical aid and antioxidant. It is also an environmental air pollutant. Pharmacological action: air pollutants, environmental, antioxidants, pharmaceutic aid. Chemical name: Sulfur dioxide (12 Dec 1998) |
| dioxide | <chemistry> An oxide containing two atoms of oxygen in each molecule; binoxide. An oxide containing but one atom or equivalent of oxygen to two of a metal; a suboxide. Carbon dioxide. See Carbonic acid, under Carbonic. Origin: Pref. Di- + oxide. Source: Websters Dictionary (01 Mar 1998) |
| thorium dioxide | <chemical> Thorium oxide (tho2). A radiographic contrast agent that was used in the early 1930s through about 1954. High rates of mortality have been linked to its use and it has been shown to cause liver cancer. Pharmacological action: carcinogens. Chemical name: Thorium oxide (ThO2) (12 Dec 1998) |
| titanium dioxide | TiO2;contains not less than 99.0% and not more than 100.5% of TiO2, calculated on the dry basis; used in creams and powders as a protectant against external irritations and solar rays. (05 Mar 2000) |
| 1,4-diethylene dioxide | 1,4-dioxane;a colourless liquid used as a solvent for cellulose esters and in histology as a drying agent. Synonym: 1,4-diethylene dioxide. (05 Mar 2000) |
| active electrode | A small electrode whose exciting effect is used to stimulate or record potentials from a localised area. Synonym: exciting electrode, localizing electrode, therapeutic electrode. (05 Mar 2000) |
| calomel electrode | An electrode in which the wire is connected through a pool of mercury to a paste of mercurous chloride (Hg2Cl2, calomel) in a potassium chloride solution covered by more potassium chloride solution; commonly used as a reference electrode. (05 Mar 2000) |
| redox electrode | An electrode capable of measuring oxidation-reduction potential. See: quinhydrone electrode. Synonym: redox electrode. (05 Mar 2000) |
| reference electrode | An electrode expected to have a constant potential, such as a calomel electrode, and used with another electrode to complete an electrical circuit through a solution; e.g., when a reference electrode is used with a glass electrode for pH measurement, changes in voltage between the two electrode's can be attributed to the effects of pH on the glass electrode alone. (05 Mar 2000) |
| glass electrode | A thin-walled glass bulb containing a standard buffer solution, quinhydrone, and a platinum wire; when immersed in an unknown solution, a potential difference develops that varies with the pH of the unknown solution; this difference can be made to give the pH; used in pH meters. (05 Mar 2000) |
| central terminal electrode | In electrocardiography, an electrode in which connections from the three limbs (right arm, left arm, and left leg) are joined and led to the electrocardiograph to form the indifferent electrode, theoretically at zero potential for the system. (05 Mar 2000) |
| Clark electrode | An oxygen electrode consisting of the tip of a platinum wire exposed to a thin film of electrolyte covered by a plastic membrane permeable to oxygen but not to water or the electrolyte. When a certain voltage is applied, oxygen is destroyed at the platinum surface; the flow of current is then proportional to the rate at which oxygen can diffuse to the platinum surface from the gas or liquid sample outside the membrane, and is thus a measure of the oxygen pressure in the sample; commonly used to measure oxygen pressure in arterial blood samples. (05 Mar 2000) |