The dissociation of molecules in the air into positive and negative ions under the influence of an electric field.
The mixture of gases present in the earth's atmosphere consisting of oxygen, nitrogen, carbon dioxide, and small amounts of other gases.
The measurement of radiation by photography, as in x-ray film and film badge, by Geiger-Mueller tube, and by SCINTILLATION COUNTING.
Use of a device (film badge) for measuring exposure of individuals to radiation. It is usually made of metal, plastic, or paper and loaded with one or more pieces of x-ray film.
Devices which accelerate electrically charged atomic or subatomic particles, such as electrons, protons or ions, to high velocities so they have high kinetic energy.
Detection and counting of scintillations produced in a fluorescent material by ionizing radiation.
Radiotherapy using high-energy (megavolt or higher) ionizing radiation. Types of radiation include gamma rays, produced by a radioisotope within a teletherapy unit; x-rays, electrons, protons, alpha particles (helium ions) and heavy charged ions, produced by particle acceleration; and neutrons and pi-mesons (pions), produced as secondary particles following bombardment of a target with a primary particle.
Pyrolysis of organic compounds at the temperature of a hydrogen-air flame to produce ionic intermediates which can be collected and the resulting ion current measured by gas chromatography.
Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix.
Oils which evaporate readily. The volatile oils occur in aromatic plants, to which they give odor and other characteristics. Most volatile oils consist of a mixture of two or more TERPENES or of a mixture of an eleoptene (the more volatile constituent of a volatile oil) with a stearopten (the more solid constituent). The synonym essential oils refers to the essence of a plant, as its perfume or scent, and not to its indispensability.
A space which has limited openings for entry and exit combined with unfavorable natural ventilation such as CAVES, refrigerators, deep tunnels, pipelines, sewers, silos, tanks, vats, mines, deep trenches or pits, vaults, manholes, chimneys, etc.
A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds.
The vapor state of matter; nonelastic fluids in which the molecules are in free movement and their mean positions far apart. Gases tend to expand indefinitely, to diffuse and mix readily with other gases, to have definite relations of volume, temperature, and pressure, and to condense or liquefy at low temperatures or under sufficient pressure. (Grant & Hackh's Chemical Dictionary, 5th ed)
The unstable triatomic form of oxygen, O3. It is a powerful oxidant that is produced for various chemical and industrial uses. Its production is also catalyzed in the ATMOSPHERE by ULTRAVIOLET RAY irradiation of oxygen or other ozone precursors such as VOLATILE ORGANIC COMPOUNDS and NITROGEN OXIDES. About 90% of the ozone in the atmosphere exists in the stratosphere (STRATOSPHERIC OZONE).
Elements that constitute group 18 (formerly the zero group) of the periodic table. They are gases that generally do not react chemically.
The study of those aspects of energy and matter in terms of elementary principles and laws. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
A mass spectrometry technique used for analysis of nonvolatile compounds such as proteins and macromolecules. The technique involves preparing electrically charged droplets from analyte molecules dissolved in solvent. The electrically charged droplets enter a vacuum chamber where the solvent is evaporated. Evaporation of solvent reduces the droplet size, thereby increasing the coulombic repulsion within the droplet. As the charged droplets get smaller, the excess charge within them causes them to disintegrate and release analyte molecules. The volatilized analyte molecules are then analyzed by mass spectrometry.
A noble gas that is found in the atmosphere. It has the atomic symbol Kr, atomic number 36, atomic weight 83.80, and has been used in electric bulbs.
A noble gas with the atomic symbol Xe, atomic number 54, and atomic weight 131.30. It is found in the earth's atmosphere and has been used as an anesthetic.
Stable elementary particles having the smallest known negative charge, present in all elements; also called negatrons. Positively charged electrons are called positrons. The numbers, energies and arrangement of electrons around atomic nuclei determine the chemical identities of elements. Beams of electrons are called CATHODE RAYS.
The process by which ELECTRONS are transported from a reduced substrate to molecular OXYGEN. (From Bennington, Saunders Dictionary and Encyclopedia of Laboratory Medicine and Technology, 1984, p270)
Any of several processes in which undesirable impurities in water are removed or neutralized; for example, chlorination, filtration, primary treatment, ion exchange, and distillation. It includes treatment of WASTE WATER to provide potable and hygienic water in a controlled or closed environment as well as provision of public drinking water supplies.
Various material objects and items in the home. It includes temporary or permanent machinery and appliances. It does not include furniture or interior furnishings (FURNITURE see INTERIOR DESIGN AND FURNISHINGS; INTERIOR FURNISHINGS see INTERIOR DESIGN AND FURNISHINGS).
A process of separating particulate matter from a fluid, such as air or a liquid, by passing the fluid carrier through a medium that will not pass the particulates. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
The immersion or washing of the body or any of its parts in water or other medium for cleansing or medical treatment. It includes bathing for personal hygiene as well as for medical purposes with the addition of therapeutic agents, such as alkalines, antiseptics, oil, etc.
Living facilities for humans.
The contamination of indoor air.
A purine base found in most body tissues and fluids, certain plants, and some urinary calculi. It is an intermediate in the degradation of adenosine monophosphate to uric acid, being formed by oxidation of hypoxanthine. The methylated xanthine compounds caffeine, theobromine, and theophylline and their derivatives are used in medicine for their bronchodilator effects. (Dorland, 28th ed)
Compounds that accept electrons in an oxidation-reduction reaction. The reaction is induced by or accelerated by exposure to electromagnetic radiation in the spectrum of visible or ultraviolet light.
Enzymes of the transferase class that catalyze the transfer of a pentose group from one compound to another.
Any substance in the air which could, if present in high enough concentration, harm humans, animals, vegetation or material. Substances include GASES; PARTICULATE MATTER; and volatile ORGANIC CHEMICALS.
A parasitic hemoflagellate of the subgenus Leishmania leishmania that infects man and animals and causes visceral leishmaniasis (LEISHMANIASIS, VISCERAL). The sandfly genera Phlebotomus and Lutzomyia are the vectors.
The destroying of all forms of life, especially microorganisms, by heat, chemical, or other means.
Procedures that render the female sterile by interrupting the flow in the FALLOPIAN TUBE. These procedures generally are surgical, and may also use chemicals or physical means.
Procedures to block or remove all or part of the genital tract for the purpose of rendering individuals sterile, incapable of reproduction. Surgical sterilization procedures are the most commonly used. There are also sterilization procedures involving chemical or physical means.
Procedures to reverse the effect of REPRODUCTIVE STERILIZATION and to regain fertility. Reversal procedures include those used to restore the flow in the FALLOPIAN TUBE or the VAS DEFERENS.
Epidemics of infectious disease that have spread to many countries, often more than one continent, and usually affecting a large number of people.
Ovoid body resting on the CRIBRIFORM PLATE of the ethmoid bone where the OLFACTORY NERVE terminates. The olfactory bulb contains several types of nerve cells including the mitral cells, on whose DENDRITES the olfactory nerve synapses, forming the olfactory glomeruli. The accessory olfactory bulb, which receives the projection from the VOMERONASAL ORGAN via the vomeronasal nerve, is also included here.
Microscopic particles comprising dead skin, dried salivary proteins, hair, SEBUM and microorganisms, shed by animals which causes allergic reactions in atopic persons.
The fertilizing element of plants that contains the male GAMETOPHYTES.
Antigen-type substances that produce immediate hypersensitivity (HYPERSENSITIVITY, IMMEDIATE).
Earth or other matter in fine, dry particles. (Random House Unabridged Dictionary, 2d ed)
Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)
Works about pre-planned studies of the safety, efficacy, or optimum dosage schedule (if appropriate) of one or more diagnostic, therapeutic, or prophylactic drugs, devices, or techniques selected according to predetermined criteria of eligibility and observed for predefined evidence of favorable and unfavorable effects. This concept includes clinical trials conducted both in the U.S. and in other countries.
Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.
The use of two or more chemicals simultaneously or sequentially in the drug therapy of neoplasms. The drugs need not be in the same dosage form.
A therapeutic approach, involving chemotherapy, radiation therapy, or surgery, after initial regimens have failed to lead to improvement in a patient's condition. Salvage therapy is most often used for neoplastic diseases.
A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.
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