| mean free path | <radiobiology> Average distance a particle travels between occurrences of the given event, for example, between collisions. For collisions, the mean free path is roughly equal to unity divided by the product of the collision cross-section times the particle density. (09 Oct 1997) |
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| cell-free extract | <cell culture> A liquid that is a mixture of the contents of a particular type of cell, sometimes the organelles are also filtered out of the liquid. (26 Mar 1998) |
| cell-free protein synthesis | <technique> An in vitro method to make proteins, using amino acids, the mRNA corresponding to the protein to be made, and a cell-free extract (the contents of a cell after removal of the cell wall and/or outer cell membranes) for other needed components and enzymes. (26 Mar 1998) |
| cell-free system | <cell culture, molecular biology> Any system in which a normal cellular reaction is reconstituted in the absence of cells for example in vitro translation systems that will synthesise protein from mRNA using a lysate of rabbit reticulocytes or wheat germ. A fractionated cell extract that maintains a biological function. A subcellular fraction isolated by ultracentrifugation or other separation techniques must first be isolated so that a process can be studied free from all of the complex side reactions that occur in a cell. The cell-free system is therefore widely used in cell biology. (12 Dec 1998) |
| gluten-free diet | Elimination of all wheat, rye, barley, and oat gluten from the diet; treatment for gluten-sensitive enteropathy (coeliac disease). See: coeliac disease. (05 Mar 2000) |
| working distance free | <microscopy> The distance between the front lens of the objective and the coverslip (or uncovered object) when the lens is focused on the specimen. (05 Aug 1998) |
| culture media, serum-free | Culture media free of serum proteins but including the minimal essential substances required for cell growth. This type of medium avoids the presence of extraneous substances that may affect cell proliferation or unwanted activation of cells. (12 Dec 1998) |
| purine-free diet | A diet containing a minimal quantity of purine bases (meats); liver, kidney, and sweetbread especially are excluded and replaced by dairy products, fruits, and cereals; alcoholic beverages also are excluded. Synonym: purine-free diet. (05 Mar 2000) |
| skeleton of free inferior limb | The bones of the lower limb except the hip bones, i.e., all lower limb bones including and distal to the femur. (05 Mar 2000) |
| skeleton of free superior limb | The bones of the upper limb except the scapula and clavicle, i.e., all upper limb bones including and distal to the humerus. (05 Mar 2000) |
| specific pathogen-free organisms | Animals or humans raised in the absence of a particular disease-causing virus or other microorganism. Less frequently plants are cultivated pathogen-free. (12 Dec 1998) |
| disease-free survival | Period after successful treatment in which there is no appearance of the symptoms or effects of the disease. (12 Dec 1998) |
| oxygen derived free radicals | An atom or atom group having an unpaired electron on an oxygen atom, typically derived from molecular oxygen. For example, one-electron reduction of O2 produces the superoxide radical, O2-; other examples include the hydroperoxyl radical (HOO-), the hydroxyl radical (HO-), and nitric oxide (NO-). (05 Mar 2000) |
| echo-free | The property of appearing echo-free or without echoes on a sonographic image; a clear cyst appears anechoic. See: transonic. Synonym: echo-free. Origin: G. An-priv. + echo + ic (05 Mar 2000) |
| joints of free inferior limb | The joints uniting the bones of the free inferior limb to one another and to the pelvic girdle; they are the hip joint, knee joint, tibiofibular joints, and the joints of the ankle and foot. Synonym: articulationes membri inferioris liberi, joints of free inferior limb, juncturae membri inferioris liberi. (05 Mar 2000) |