Gases: 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)Air: The mixture of gases present in the earth's atmosphere consisting of oxygen, nitrogen, carbon dioxide, and small amounts of other gases.Blood-Brain Barrier: Specialized non-fenestrated tightly-joined ENDOTHELIAL CELLS with TIGHT JUNCTIONS that form a transport barrier for certain substances between the cerebral capillaries and the BRAIN tissue.Air Pollutants: 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.Air Pollution: The presence of contaminants or pollutant substances in the air (AIR POLLUTANTS) that interfere with human health or welfare, or produce other harmful environmental effects. The substances may include GASES; PARTICULATE MATTER; or volatile ORGANIC CHEMICALS.Embolism, Air: Blocking of a blood vessel by air bubbles that enter the circulatory system, usually after TRAUMA; surgical procedures, or changes in atmospheric pressure.Air Microbiology: The presence of bacteria, viruses, and fungi in the air. This term is not restricted to pathogenic organisms.Air Movements: The motion of air currents.Air Pollution, Indoor: The contamination of indoor air.Blood-Retinal Barrier: A specialized transport barrier, in the EYE, formed by the retinal pigment EPITHELIUM, and the ENDOTHELIUM of the BLOOD VESSELS of the RETINA. TIGHT JUNCTIONS joining adjacent cells keep the barrier between cells continuous.Blood-Air Barrier: The barrier between capillary blood and alveolar air comprising the alveolar EPITHELIUM and capillary ENDOTHELIUM with their adherent BASEMENT MEMBRANE and EPITHELIAL CELL cytoplasm. PULMONARY GAS EXCHANGE occurs across this membrane.Air Sacs: Thin-walled sacs or spaces which function as a part of the respiratory system in birds, fishes, insects, and mammals.Air Conditioning: The maintenance of certain aspects of the environment within a defined space to facilitate the function of that space; aspects controlled include air temperature and motion, radiant heat level, moisture, and concentration of pollutants such as dust, microorganisms, and gases. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Communication Barriers: Those factors, such as language or sociocultural relationships, which interfere in the meaningful interpretation and transmission of ideas between individuals or groups.Blood-Testis Barrier: A specialized barrier, in the TESTIS, between the interstitial BLOOD compartment and the adluminal compartment of the SEMINIFEROUS TUBULES. The barrier is formed by layers of cells from the VASCULAR ENDOTHELIUM of the capillary BLOOD VESSELS, to the SEMINIFEROUS EPITHELIUM of the seminiferous tubules. TIGHT JUNCTIONS form between adjacent SERTOLI CELLS, as well as between the ENDOTHELIAL CELLS.Permeability: Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.Tight Junctions: Cell-cell junctions that seal adjacent epithelial cells together, preventing the passage of most dissolved molecules from one side of the epithelial sheet to the other. (Alberts et al., Molecular Biology of the Cell, 2nd ed, p22)Air Pollutants, Occupational: Air pollutants found in the work area. They are usually produced by the specific nature of the occupation.Air Ionization: The dissociation of molecules in the air into positive and negative ions under the influence of an electric field.Air Bags: Automotive safety devices consisting of a bag designed to inflate upon collision and prevent passengers from pitching forward. (American Heritage Dictionary, 1982)Particulate Matter: Particles of any solid substance, generally under 30 microns in size, often noted as PM30. There is special concern with PM1 which can get down to PULMONARY ALVEOLI and induce MACROPHAGE ACTIVATION and PHAGOCYTOSIS leading to FOREIGN BODY REACTION and LUNG DISEASES.Capillary Permeability: The property of blood capillary ENDOTHELIUM that allows for the selective exchange of substances between the blood and surrounding tissues and through membranous barriers such as the BLOOD-AIR BARRIER; BLOOD-AQUEOUS BARRIER; BLOOD-BRAIN BARRIER; BLOOD-NERVE BARRIER; BLOOD-RETINAL BARRIER; and BLOOD-TESTIS BARRIER. Small lipid-soluble molecules such as carbon dioxide and oxygen move freely by diffusion. Water and water-soluble molecules cannot pass through the endothelial walls and are dependent on microscopic pores. These pores show narrow areas (TIGHT JUNCTIONS) which may limit large molecule movement.Air Pressure: The force per unit area that the air exerts on any surface in contact with it. Primarily used for articles pertaining to air pressure within a closed environment.Occludin: A MARVEL domain protein that plays an important role in the formation and regulation of the TIGHT JUNCTION paracellular permeability barrier.Blood-Aqueous Barrier: The selectively permeable barrier, in the EYE, formed by the nonpigmented layer of the EPITHELIUM of the CILIARY BODY, and the ENDOTHELIUM of the BLOOD VESSELS of the IRIS. TIGHT JUNCTIONS joining adjacent cells keep the barrier between cells continuous.Environmental Monitoring: The monitoring of the level of toxins, chemical pollutants, microbial contaminants, or other harmful substances in the environment (soil, air, and water), workplace, or in the bodies of people and animals present in that environment.Nitrogen Dioxide: Nitrogen oxide (NO2). A highly poisonous gas. Exposure produces inflammation of lungs that may only cause slight pain or pass unnoticed, but resulting edema several days later may cause death. (From Merck, 11th ed) It is a major atmospheric pollutant that is able to absorb UV light that does not reach the earth's surface.Air Filters: Barriers used to separate and remove PARTICULATE MATTER from air.Ozone: 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).Sulfur Dioxide: A highly toxic, colorless, nonflammable gas. It is used as a pharmaceutical aid and antioxidant. It is also an environmental air pollutant.Dictionaries, MedicalDictionaries as Topic: Lists of words, usually in alphabetical order, giving information about form, pronunciation, etymology, grammar, and meaning.Lung: Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.Visible Human Projects: Digital image data sets, consisting of complete, anatomically detailed, three-dimensional representations of the normal male and female human bodies.Tomography, Optical Coherence: An imaging method using LASERS that is used for mapping subsurface structure. When a reflective site in the sample is at the same optical path length (coherence) as the reference mirror, the detector observes interference fringes.Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.Diffusion: The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.Rumex: A plant genus of the family POLYGONACEAE that contains patientosides and other naphthalene glycosides.Dissertations, Academic as Topic: Dissertations embodying results of original research and especially substantiating a specific view, e.g., substantial papers written by candidates for an academic degree under the individual direction of a professor or papers written by undergraduates desirous of achieving honors or distinction.Vanadium: A metallic element with the atomic symbol V, atomic number 23, and atomic weight 50.94. It is used in the manufacture of vanadium steel. Prolonged exposure can lead to chronic intoxication caused by absorption usually via the lungs.Vehicle Emissions: Gases, fumes, vapors, and odors escaping from the cylinders of a gasoline or diesel internal-combustion engine. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed & Random House Unabridged Dictionary, 2d ed)Libraries, Digital: Libraries in which a major proportion of the resources are available in machine-readable format, rather than on paper or MICROFORM.Lens Nucleus, Crystalline: The core of the crystalline lens, surrounded by the cortex.Libraries, MedicalLibraries: Collections of systematically acquired and organized information resources, and usually providing assistance to users. (ERIC Thesaurus, accessed 2/1/2008)Library Collection Development: Development of a library collection, including the determination and coordination of selection policy, assessment of needs of users and potential users, collection use studies, collection evaluation, identification of collection needs, selection of materials, planning for resource sharing, collection maintenance and weeding, and budgeting.Construction Materials: Supplies used in building.PubMed: A bibliographic database that includes MEDLINE as its primary subset. It is produced by the National Center for Biotechnology Information (NCBI), part of the NATIONAL LIBRARY OF MEDICINE. PubMed, which is searchable through NLM's Web site, also includes access to additional citations to selected life sciences journals not in MEDLINE, and links to other resources such as the full-text of articles at participating publishers' Web sites, NCBI's molecular biology databases, and PubMed Central.Dust: Earth or other matter in fine, dry particles. (Random House Unabridged Dictionary, 2d ed)Naphazoline: An adrenergic vasoconstrictor agent used as a decongestant.Periodicals as Topic: A publication issued at stated, more or less regular, intervals.Awards and PrizesBooks