| ESM | ejection systolic murmur; endoscopic specular microscope; ethosuximide |
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| LM | lactic acid mineral [medium]; lactose malabsorption; laryngeal mask; laryngeal muscle; lateral malle... |
| MS | Maffuci syndrome; maladjustment score; mandibular series; Marfan syndrome; Marie-Strumpell [syndrome... |
| SAM | S-adenosyl-L-methionine; scanning acoustic microscope; senescence accelerated mouse; sex arousal mec... |
| SLAM | scanning laser acoustic microscope; systemic lupus erythematosus activity measure |
| ion exchange resin | <chemistry> A resin of polymers that havefixed charged groups which is used in chromatographic columns to separate ions. (27 Oct 1998) |
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| ion exchange resins | <chemistry> High molecular weight, insoluble polymers which contain functional groups that are capable of undergoing exchange reactions (ion exchange) with either cations or anions. See: ion exchange, ion exchanger. (12 Dec 1998) |
| ion pump | A membranal complex of proteins that is capable of transporting ions against a concentration gradient using the energy from ATP. (05 Mar 2000) |
| ion pumps | Integral membrane proteins that transport ions across a membrane against an electrochemical gradient. (12 Dec 1998) |
| ion selective electrode | An electrode half cell, with a semi permeable membrane that is permeable only to a single ion. The electrical potential measured between this and a reference half cell (e.g. A calomel electrode) is thus the Nernst potential for the ion. Given that the solution filling the ion selective electrode is known, the activity (rather than concentration) of the ion in the unknown solution can be measured. Commercial ion selective electrodes frequently use a hydrophobic membrane containing an ionophore, such as valinomycin (for potassium) or monensin (for sodium). A pH electrode is made with a thin membrane of pH sensitive (i.e. Proton permeable) glass. (18 Nov 1997) |
| ion-selective electrodes | Electrodes which can be used to measure the concentration of particular ions in cells, tissues, or solutions. (12 Dec 1998) |
| ion transport | The movement of ions across energy-transducing cell membranes. Transport can be active or passive. Passive ion transport (facilitated diffusion) derives its energy from the concentration gradient of the ion itself and allows the transport of a single solute in one direction (uniport). Active ion transport is usually coupled to an energy-yielding chemical or photochemical reaction such as ATP hydrolysis. This form of primary active transport is called an ion pump. Secondary active transport utilises the voltage and ion gradients produced by the primary transport to drive the cotransport of other ions or molecules. These may be transported in the same (symport) or opposite (antiport) direction. (12 Dec 1998) |
| oxonium ion | <chemistry> A positively charged ion that is water with an additional hydrogen atom (H3O). (09 Oct 1997) |
| tetraethylammonium ion | A monovalent cation widely used in neurophysiology as a specific blocker of potassium channels. It is similar in size to the hydrated potassium ion and gets stuck (reversibly) in the channels. (18 Nov 1997) |
| ligand gated ion channel | A transmembrane ion channel whose permeability is increased by the binding of a specific ligand, typically a neurotransmitter at a chemical synapse. The permeability change is often drastic, such channels let through effectively no ions when shut, but allow passage at up to 10exp7 ions sexp 1 when a ligand is bound. Recently, the receptors for both acetylcholine and GABA have been found to share considerable sequence homology, implying that there may be a family of structurally related ligand gated ion channels. (18 Nov 1997) |
| light-ion fusion | <radiobiology> Light-Ion-Beam-Driven Inertial Confinement fusion, using beams of light ions driven at implosion targets. Pulsed-power driven accelerators are relatively efficient and cost-effective, but beam-focusing is a technical hurdle for this approach. (09 Oct 1997) |
| binocular microscope | <instrument, microscopy> A microscope fitted with double eyepieces for vision with both eyes. The purpose in dividing the same image from a single objective of the usual compound micro-scope is to reduce eyestrain and muscular fatigue which may result from monocular, high-power microscopy. The purpose in obtaining a different image for each of two oculars is to provide stereoscopy by means of two different angles of view. There are two kinds of stereoscopic microscopes: binobjective (Greenough) older type and monobjective (common main objective) newer type. (See stereo microscope, Greenough microscope, etc.) (05 Aug 1998) |
| Rheinberg microscope | <instrument> A modified form of dark-field microscope in which the central opaque stop in the condenser is replaced by a coloured filter, producing a background of contrasting colour against which the specimen is illuminated. (05 Mar 2000) |
| Greenough microscope | <instrument, microscopy> One of two kinds of stereomicroscopes with two separate compound microscopes, one for each eye, focused on the same object. The other kind has a common main objective. See: binocular microscope. (05 Aug 1998) |
| phase-contrast microscope | <instrument> A specially constructed microscope that has a special condenser and objective containing a phase-shifting ring whereby small differences in index of refraction are made visible as intensity or contrast differences in the image; particularly useful for examining structural details in transparent specimens such as living or unstained cells and tissues. (05 Mar 2000) |