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  2. NOx - Wikipedia

    en.wikipedia.org/wiki/NOx

    In atmospheric chemistry, NOx is shorthand for nitric oxide (NO) and nitrogen dioxide (NO2), the nitrogen oxides that are most relevant for air pollution. [1][2] These gases contribute to the formation of smog and acid rain, as well as affecting tropospheric ozone. NOx gases are usually produced from the reaction between nitrogen and oxygen ...

  3. Nitrous oxide - Wikipedia

    en.wikipedia.org/wiki/Nitrous_oxide

    Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, factitious air, among others, [4] is a chemical compound, an oxide of nitrogen with the formula N. 2O. At room temperature, it is a colourless non-flammable gas, and has a slightly sweet scent and taste. [4]

  4. Human tooth - Wikipedia

    en.wikipedia.org/wiki/Human_tooth

    Humans have four types of teeth: incisors, canines, premolars, and molars, which each have a specific function. The incisors cut the food, the canines tear the food and the molars and premolars crush the food. The roots of teeth are embedded in the maxilla (upper jaw) or the mandible (lower jaw) and are covered by gums.

  5. Biological functions of nitric oxide - Wikipedia

    en.wikipedia.org/wiki/Biological_functions_of...

    Nitric oxide (nitrogen monoxide) is a molecule and chemical compound with chemical formula of N O. In mammals including humans, nitric oxide is a signaling molecule involved in several physiological and pathological processes. [1] It is a powerful vasodilator with a half-life of a few seconds in the blood.

  6. Tooth enamel - Wikipedia

    en.wikipedia.org/wiki/Tooth_enamel

    Parts of a tooth, including the enamel (cross section). Tooth enamel is one of the four major tissues that make up the tooth in humans and many animals, including some species of fish. It makes up the normally visible part of the tooth, covering the crown. The other major tissues are dentin, cementum, and dental pulp.

  7. Ground-level ozone - Wikipedia

    en.wikipedia.org/wiki/Ground-level_ozone

    Ozone is least concentrated in the ground layer (or planetary boundary layer) of the troposphere. Ground-level or tropospheric ozone is created by chemical reactions between NOx gases (oxides of nitrogen produced by combustion) and volatile organic compounds (VOCs). The combination of these chemicals in the presence of sunlight form ozone.

  8. Nitrogen cycle - Wikipedia

    en.wikipedia.org/wiki/Nitrogen_cycle

    The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation ...

  9. Tooth discoloration - Wikipedia

    en.wikipedia.org/wiki/Tooth_discoloration

    The appearance and perception of a tooth is the result of a complex interaction of factors such as lighting conditions, translucency, opacity, light scattering, gloss and the human eye and brain. [5] Of these, the intrinsic pigmentation of a tooth is the most influential, [4] which in turn is determined by genetic and natural factors. [6]