| EMER | electromagnetic molecular electron resonance |
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| ENDOR | electron nuclear double resonance |
| EPR | early progressive resistance; electron paramagnetic resonance; electronic patient record; electrophr... |
| EI | Edmonton injector; electrolyte imbalance; electron impact; electron ionization; emotionally impaired... |
| E/M | electron microscope, electron microscopy; evaluation and management |
| nuclear magnetic resonance tomography | A special imaging technique used to image internal stuctures of the body, particularly the soft tissues. An MRI image is often superior to a normal X-ray image. It uses the influence of a large magnet to polarize hydrogen atoms in the tissues and then monitors the summation of the spinning energies within living cells. Images are very clear and are particularly good for soft tissue, brain and spinal cord, joints and abdomen. These scans may be used for detecting some cancers or for following their progress. Acronym: MRI (11 Nov 1997) |
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| surface plasmon resonance | <chemistry> Alteration in light reflectance as a result of binding of molecules to a surface from which total internal reflection is occuring. Used in the Biacore (Pharmacia Trademark) machine that detects the binding of ligand to surface immobilised receptor or antibody. (19 Jan 1998) |
| tympanitic resonance | 1. <clinical sign> A flatulent distention of the belly; tympanites. 2. Hence, inflation; conceit; bombast; turgidness. "Thine 's a tympany of sense." "A plethoric a tautologic tympany of sentence." (De Quincey) Origin: Gr, fr. A kettledrum. See Tympanites. (28 Oct 1998) |
| aperture for electron microscopy | <technique> Anode aperture: The opening in the accelerating voltage anode shield of the electron gun through which the electrons must pass to irradiate the specimen. Condenser aperture: An opening in the condenser lens controlling the number of electrons entering the lens and the angular aperture of the electron beam. The angular aperture can also be controlled by the condenser lens current. Physical objective aperture: A metallic diaphragm, with a small central hole, used to limit the cone of electrons accepted by the objective lens. This improves image-contrast since highly scattered electrons are prevented from arriving at the Gaussian image plane and therefore cannot contribute to background fog. Aplanatic. Free from spherical aberration and coma. (05 Aug 1998) |
| Auger electron | An electron ejected from a lower energy orbital after a photoelectric interaction of an X-ray photon with a K-shell electron by the characteristic radiation photon; the Auger electron recoils with energy equal to the characteristic radiation less the difference in shell binding energies. See: photoelectric effect. (05 Mar 2000) |
| backscattered electron | <microscopy> Produced by an incident electron colliding with the nucleus of an atom in the specimen. The incident electron is then scattered backward about 180 degrees with no appreciable loss of energy, an elastic collision. (05 Aug 1998) |
| backscattered electron imaging | <microscopy> The production of backscattered electrons from a sample varies directly with the specimen's average atomic number, higher atomic number elements produce more backscattered electrons than lower atomic number ones. Detection of Backscattered Electrons is achieved by using a donut shaped solid state saemiconductor device mounted on the bottom of the objective lens. When Backscattered Electrons strike the detector electron-hole pairs are created which are then counted. This quantity is translated into a pixel intensity and displayed on the CRT, forming the image. By splitting the detector into halves (or quadrants) differences in the signal level on the individual detector segments provide surface topography information. (05 Aug 1998) |
| valence electron | One of the electron's that take part in chemical reactions of an atom. (05 Mar 2000) |
| reverse electron transport | <chemistry> The energy-dependent movement of electrons against the thermodynamic gradient to form a strong reductant from a weaker electron donor. (11 Jan 1998) |
| microscope, electron | <microscopy> An electron-optical device which produces a magnified image of an object. Detail may be revealed by virtue of selective transmission, reflection, or emission of electrons by the object. (05 Aug 1998) |
| microscopy, electron | Visual and photographic microscopy in which electron beams with wavelengths thousands of times shorter than visible light are used in place of light, thereby allowing much greater magnification. (12 Dec 1998) |
| microscopy, electron, scanning | Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point, giving the surface image a three-dimensional quality. (12 Dec 1998) |
| microscopy, electron, scanning transmission | A type of electron microscopy which scans with an extremely narrow beam that is transmitted through the sample. The detection apparatus produces an image whose brightness depends on the atomic number of the sample. It should not be confused with microscopy, electron scanning nor with microscopy, electron, transmission (see microscopy, electron). (12 Dec 1998) |
| Conventional Transmission Electron Microscopy | <technique> A term applied to 'normal' transmission electron microscopy imaging. The electron beam is passed through a thin film sample (typically ~1-200 nm thick). Bright field diffraction contrast images are formed with the direct (undiffracted) beam. Dark field images are formed with a selected diffracted beam. CTEM imaging is used in the general observation of samples and careful selection of the diffracting conditions of the sample will allow the analysis of defect structures within the sample. (05 Aug 1998) |
| Convergent Beam Electron Diffraction | <microscopy> An electron probe is tightly focused on a transmission electron microscopy specimen and the resulting pattern of diffracted electrons is observed. The patterns contains information on the crystal symmetry and atomic and electronic structure of the sample. Regions as small as 0.2 nm may be examined. Acronym: CBED (05 Aug 1998) |