| HEPA | high-efficiency particulate air [filter] |
|---|---|
| HPF | heparin-precipitable fraction; hepatic plasma flow; high-pass filter; high-power field [microscope];... |
| QMF | quadrature mirror filter |
| ULPA | ultra low penetration air filter |
| AGE | acrylamide gel; acute gastroenteritis; advanced glycation end product; agarose gel electrophoresis; ... |
| Greenfield filter | A multistrutted spring-styled filter usually placed in the inferior vena cava to prevent venous emboli from reaching the pulmonary circulation from the lower extremity. (05 Mar 2000) |
|---|---|
| micropore filter | A filter made of a meshwork of cellulose acetate or nitrate and with defined pore size. They can be autoclaved and the smaller pore sizes (0.22m,0.45m) are used for sterilising heat labile materials by filtering out micro organisms. Larger pore size filters are used in setting up Boyden chambers. They are about 150m thick and should be distinguished from Nucleopore filters. Millipore is a trade name for micropore filters. (18 Nov 1997) |
| Millipore filter | <cell culture, equipment> Trade name for a well known brand of micropore filters. (12 Jan 1998) |
| hemming filter | <apparatus> A filter placed between two tubes attached to each other, often used with centrifuges to selectively remove a substance of interest from a mixture in one tube and deposit the substance into the other tube. (09 Oct 1997) |
| high-pass filter | A device or material that allows high frequency signals to pass while attenuating other signals. (05 Mar 2000) |
| high quality filter paper | Used in paper chromatography. Synonym: high quality filter paper. Congo red paper, paper impregnated with Congo red; used as a pH indicator, changing from blue-violet at 3.0 to red at 5.0. Filter paper, an unsized paper used in pharmacy and chemistry for filtering solutions; many varieties are used for paper chromatography. (05 Mar 2000) |
| simon nitinol ivc filter | <radiology> Introduced 1990; Nitinol Medical Technologies, Woburn, MA. BARD, thermal memory alloy:titanium and nickel;, straightened form at cool temperatures (4-10C), reforms into predetermined filter shape at body temperatures efficacy, recurrent PE: 0 - 4.8%, IVC thrombosis: 7 - 11% (by clinical symptoms), access site thrombosis: 2 - 10% advantages, narrow introducer sheath (9 Fr), largest choice of access: brachial or left CFV approach without difficulty, only mild MRI artifacts disadvantages, IVC thrombosis: symptomatic occlusion rates higher than reported wtih Greenfield or bird's nest filters, caval penetration: 1 - 33%, caudal drop: exact filter location difficult to predict (12 Dec 1998) |
| spatial filter | <radiobiology> Device consisting of a lens pair and a pinhole aperture stop. Intensity fluctuations over the spatial extent of a laser beam are removed by passing the focused beam through the aperture stop. The pinhole must be placed in a vacuum to prevent air breakdown by the focused beam. These filters are used to counter the effects caused by self-focusing. (09 Oct 1997) |
| neutral-density filter | <equipment> A light-absorbing filter whose absorption spectrum is moderately flat. Depending on the type, the absorption curve is flat primarily in the visible spectral range, or may extend to varying degrees beyond the visible range. For video microscopy, this is an important point since the absorbance may or may not extend into the near-infrared region where the sensitivity of many video image pickup devices is very high. (05 Aug 1998) |
| nitinol filter | A vena cava filter made with a metal that springs into shape when warmed to body heat by the blood after catheter insertion. (05 Mar 2000) |
| Nucleopore filter | Filter of defined pore size made by etching a polycarbonate filter that has been bombarded by neutrons, the extent of etching determining the pore size. Very thin, with neat circular holes going right through the membrane, not a complex meshwork like micropore filters. (18 Nov 1997) |
| DNA filter assay | <molecular biology> A lab technique used to identify the complementary base sequences of DNA. It involves immobilising the DNA on a filter and putting it in a solution that contains radioactively-labelled probe DNA or RNA molecules. (09 Oct 1997) |
| inferior vena cava filter | <radiology> Indications: contraindication to anticoagulation, failure of anticoagulation, complication of anticoagulation: haemorrhage or thrombocytopenia, large free-floating IVC/iliac vein thrombus expanded indications: cor pulmonale and DVT/PE, patients with high risk of complications to anticoagulation, metastatic disease, syncope in elderly, prophylactic placement in high-risk trauma patients, spinal cord injury, severe head injury, complex pelvic fractures, multiple long bone fractures, prophylactic placement before hip/knee replacement in patients with prior DVT prophylactic filters remain controversial see also: types of IVC filters (12 Dec 1998) |
| titanium greenfield ivc filter | <radiology> Advantages: low profile: 14.3 Fr introducer sheath, percutaneous placement, lack of ferromagnetic properties, low recurrent PE rate (3-5%), low IVC thrombosis rate (1-9%), successful placement (97%) disadvantages: maximum caval diameter = 28mm, tilting/leg assymetry, difficult placement from left femoral approach see also: indications (12 Dec 1998) |
| filter | 1. A porous substance through which a liquid or gas is passed in order to separate it from contained particulate matter or impurities. Synonym: filtrum. 2. To use or to subject to the action of a filter. 3. In diagnostic or therapeutic radiology, a plate made of one or more metals such as aluminum and copper that, placed in the x-or gamma-ray beam, permits passage of a greater proportion of higher energy radiation and attenuation of lower and less desirable energy radiation, raising the average energy or hardening the beam. 4. A device used in spectrophotometric analysis to isolate a segment of the spectrum. 5. A mathematical algorithm applied to image data for the purpose of enhancing image quality, usually by suppression of high spatial frequency noise. Origin: Mediev. L. Filtro, pp. -atus, to strain through felt, fr. Filtrum, felt (05 Mar 2000) |