liquid nitrogen


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Related to liquid nitrogen: dry ice

nitrogen

 (N) [ni´tro-jen]
a chemical element, atomic number 7, atomic weight 14.007. (See Appendix 6.) It is a gas constituting about four-fifths of common air; chemically it is almost inert. It is not poisonous but is fatal if breathed alone because of oxygen deprivation. It is soluble in the blood and body fluids, and can cause serious symptoms when released as bubbles of gas by rapid decompression (see bends). Nitrogen occurs in proteins and amino acids and is thus present in all living cells.
nitrogen 13 a radioactive isotope of nitrogen having a half-life of 9.97 minutes and decaying by positron emission; it is used as a tracer in positron emission tomography.
nitrogen balance the state of the body in regard to the rate of protein intake and protein utilization. When protein is metabolized, about 90 per cent of its nitrogen is excreted in the urine in the form of urea, uric acid, creatinine, and other nitrogen end-products. The remaining 10 per cent of the nitrogen is eliminated in the feces. A negative nitrogen balance occurs when more protein is used by the body than is taken in. A positive nitrogen balance implies a net gain of protein in the body. Negative nitrogen balance can be caused by such factors as malnutrition, debilitating diseases, blood loss, and glucocorticoids. A positive balance can be caused by exercise, growth hormone, and testosterone.
liquid nitrogen nitrogen in liquid form, i.e., below −195.79°C; used as a coolant, such as in thermographic equipment.
nitrogen mustards a group of toxic, blistering alkylating agents that are cell cycle phase nonspecific; it includes nitrogen mustard itself (mechlorethamine hydrochloride), chlorambucil, cyclophosphamide, ifosfamide, and melphalan. Some have been used as antineoplastic agents in certain forms of cancer; they do not cure these conditions, but ease their effects by destroying mitotic cells (those newly formed by division), thereby affecting malignant tissue in its early stage of development, and leaving normal tissue unaffected. They are especially useful in treatment of leukemia, in which they reduce the leukocyte count, and in cases in which the malignant disease is widespread throughout the body and therefore cannot be effectively treated locally by surgery or radiotherapy. In cases of lung cancer, mechlorethamine hydrochloride is usually injected directly into the lungs via the pulmonary circulation. Side effects, which tend to limit the usefulness of these drugs, include nausea, vomiting, and a decrease in bone marrow production.
nonprotein nitrogen (NPN) the nitrogenous constituents of the blood exclusive of the protein bodies, consisting of the nitrogen of urea, uric acid, creatine, creatinine, amino acids, polypeptides, and an undetermined part known as rest nitrogen. Measurement of this is used as a test of renal function, but has been largely replaced by measurement of specific substances, such as urea and creatinine.
nitrogen washout test a test for vital capacity of lungs; with the patient inhaling pure oxygen, the volume of exhaled nitrogen is obtained for each breath until it falls below 1 per cent of the gas being exhaled (usually about seven minutes' time); the total volume of nitrogen that has been exhaled at this point is assumed to be 0.8 of the vital capacity.
nitrogen washout test, single breath the patient inhales a vital capacity's volume of pure oxygen and then slowly exhales. The nitrogen content of the exhalation is measured over the entire breath and a curve is generated; different parts of the curve represent nitrogen concentrations of gas in different components of the total lung capacity, and can be analyzed for irregularities. Called also single breath test.

liquid nitrogen

See cryogen.
Enlarge picture
LIQUID NITROGEN

liquid nitrogen

Nitrogen cooled to 77K (77°C above absolute zero). Liquid nitrogen is used to cool or freeze body parts, esp. the skin, in anesthesia and some surgeries. See: illustration
See also: nitrogen

liquid nitrogen

compressed, liquefied nitrogen gas at -196°C; expands rapidly on release into air and cooling its surroundings; applied (as a spray) to destroy minor skin lesions, e.g. basal cell carcinoma, verrucae (induces formation of intranuclear ice crystals, disrupts viral DNA, ruptures cell membranes and triggers an immune response)

liquid

1. a substance that flows readily in its natural state.
2. flowing readily; neither solid nor gaseous.

liquid diet
a diet limited to the intake of liquids or foods that can be changed to a liquid state.
liquid nitrogen
compressed nitrogen in liquid form; used as a supercoolant in freezing semen, and in cryosurgery.
liquid paraffin, liquid petrolatum
see mineral oil.
References in periodicals archive ?
He added: "The liquid nitrogen machine is my own venture but obviously I've been getting lots of advice from my parents who know the food business like the back of their hands.
Basically, you get some ice-cream mix and you have it in a bowl and you pour in the liquid nitrogen.
From the constructive viewpoint, the designed liquid nitrogen cooling installation (IRC) is made of 4 modules:
The cell dewar (not shown in photograph) is simply a styrofoam container, allowing the cell to be maintained at liquid nitrogen temperature during compression.
The scientist, whose favourite ice cream is egg and bacon flavour, unveiled the formula of water, sugar, butter fat and liquid nitrogen before a seminar dedicated to ice cream.
HOSPITALS and laboratories use liquid nitrogen to preserve material such as human tumour samples.
Freezing in liquid nitrogen has been used for the cryopreservation of biological tissues for many decades.
Before my retirement, I used to deliver semen and liquid nitrogen to farmers so that they could breed their own cows through artificial insemination.
A string of crashes, beginning with an overturned tanker carrying liquid nitrogen, snarled traffic in the Ventura Freeway's northbound lanes between Camarillo and Newbury Park for some seven hours Tuesday, the California Highway Patrol reported.
By replacing mechanical blast freezers at Warrenton with a liquid nitrogen system, Pacific was able to improve the quality of its frozen fish and the efficiency of its plant in terms of freezing times and maintenance.
Gas-assist injection molders (GAIM) can improve efficiency and quality -- even on lightweight parts and difficult geometries -- with the help of a new liquid nitrogen (N2) pressure booster from Linde North America.