| BHT | beta-hydroxytheophylline; breath hydrogen test; butylated hydroxytoluene |
|---|---|
| cH+ | hydrogen ion concentration |
| CHN | carbon, hydrogen, and nitrogen; child neurology; Chinese [hamster]; community health network; commun... |
| D/H | deuterium/hydrogen [ratio] |
| EHP | di-(20-ethylhexyl) hydrogen phosphate; Environmental Health Perspectives; excessive heat production;... |
| hydrogen bromide | HBr;a colourless gas that has a very irritating odour and fumes in moist air; in aqueous solution, it is hydrobromic acid. Hydrogen chloride, HCl;a very soluble gas which, in solution, forms hydrochloric acid. (05 Mar 2000) |
|---|---|
| hydrogen carrier | A molecule that, in conjunction with a tissue enzyme system, carries hydrogen from one metabolite (oxidant) to another (reductant) or to molecular oxygen to form H2O. Synonym: hydrogen acceptor. (05 Mar 2000) |
| hydrogen cyanide | <chemical> Hydrogen cyanide (hcn). A toxic liquid or colourless gas. It is found in the smoke of various tobacco products and released by combustion of nitrogen-containing organic materials. Pharmacological action: poisons. Chemical name: Hydrocyanic acid (12 Dec 1998) |
| hydrogen dehydrogenase | <enzyme> Hoxf, hoxh, hoxu, and hoxy from rhodococcus opacus encode the alpha-, beta-, gamma-, and delta-subunits, respectively Registry number: EC 1.12.1.2 Synonym: hydrogen-nad+ oxidoreductase, nad-reducing hydrogenase, hoxf gene product, hoxu gene product, hoxy gene product, hoxh gene product (26 Jun 1999) |
| hydrogen dioxide | <chemical> Hydrogen peroxide is produced by vertebrate phagocytes and is used in bacterial killing (the myeloperoxidase halide system). (05 May 1997) |
| hydrogen donor | A metabolite from which hydrogen is removed (by a dehydrogenase system) and transferred by a hydrogen carrier to another metabolite, which is thus reduced. (05 Mar 2000) |
| hydrogen electrode | The ultimate standard of reference in all pH determinations, limited and technically difficult to use, consisting of a piece of spongy platinum black partly immersed in a solution in a small glass tube; the tube above the solution is filled with hydrogen gas that is bubbled through the solution and absorbed by the platinum; the electrode thus measures the potential between H2 and H+, the "standard" potential of which (1 atmosphere, 1 molar) is taken as zero; hence, the hydrogen electrode potential measures [H+] or pH. (05 Mar 2000) |
| hydrogen embrittlement | <physics> A decrease in the fracture strength of metals (embrittlement) due to the incorporation of hydrogen within the metal lattice. (09 Oct 1997) |
| hydrogen exponent | The logarithm of the hydrogen ion concentration in blood or other fluid; its negative is the pH of that fluid. (05 Mar 2000) |
| hydrogen ion | A hydrogen atom minus its electron and therefore carrying a unit positive charge (i.e., a proton); in water, it combines with a water molecule to form hydronium ion, H3O+. (05 Mar 2000) |
| hydrogen number | The quantity of hydrogen that 1 g of fat will absorb; it is a measurement of the amount of unsaturated fatty acids in the fat. See: iodine number. (05 Mar 2000) |
| hydrogen peroxide | <chemical> Hydrogen peroxide is produced by vertebrate phagocytes and is used in bacterial killing (the myeloperoxidase halide system). (05 May 1997) |
| hydrogen-potassium-exchanging atpase | <enzyme> An enzyme isolated from the gastric mucosa that catalyses the hydrolysis of ATP coupled with the exchange of hydrogen and potassium ions across the cell wall. Chemical name: ATP phosphohydrolase (H+/K+-transporting) Registry number: EC 3.6.1.36 (12 Dec 1998) |
| hydrogen pump | Molecular mechanism for acid secretion from gastric parietal cells based on the activity of a H+-K+-ATPase. (05 Mar 2000) |
| hydrogen sulfide | <chemical> Hydrogen sulfide (h2s). A flammable, poisonous gas with a characteristic odour of rotten eggs. It is used in the manufacture of chemicals, in metallurgy, and as an analytical reagent. Chemical name: Hydrogen sulfide (H2S) (12 Dec 1998) |