Oxygen radicals svenska
In chemistrya photoinitiator is a molecule that creates reactive species free radicalscations or anions when exposed to radiation UV or visible. Synthetic photoinitiators are key components in photopolymers for example, photo-curable coatings, adhesives and dental restoratives. Some small molecules in the atmosphere can also act as photoinitiators by decomposing to "oxygen radicals svenska" free radicals in photochemical smog.
For instance, nitrogen dioxide NO 2 is produced in large quantities by gasoline -burning internal combustion engines. NO 2 in the troposphere gives smog its brown coloration and catalyzes production of toxic ground-level ozone O 3. Molecular oxygen O 2 also serves as a photoinitiator in the stratosphere, breaking down into atomic oxygen and combining with O 2 in order to form the ozone in the ozone layer.
Photoinitators can create reactive species by different pathways including photodissociation and electron transfer. Certain azo compounds such as azobisisobutyronitrilecan also photolytically cleave, forming two alkyl radicals and nitrogen gas:. Since molecular oxygen can abstract H atoms from certain radicals, the HOO· radical is easily created.
This particular radical can further abstract H atoms, creating H 2 O 2or hydrogen peroxide; peroxides can further cleave photolytically into two hydroxyl radicals. In both cases, the ·OH radicals formed can serve to oxidize organic compounds in the oxygen radicals svenska. Nitrogen dioxide can also be photolytically cleaved by photons of wavelength less than nm [ 2 ] producing atomic oxygen and nitric oxide.
Atomic oxygen is a highly reactive species, and can abstract a H atom from anything, including water.
Defining roles of specific reactive oxygen species (ROS) in cell biology and physiology
Nitrogen dioxide can be regenerated through a reaction between certain peroxy-containing radicals and NO. In the stratosphere, molecular oxygen O 2 is an important photoinitiator that begins the ozone -production process in the ozone layer. Oxygen can be photolyzed into atomic "oxygen radicals svenska" by light with wavelength less than nm.
However, ozone can also be photolyzed back into O and O 2. Furthermore, atomic oxygen and ozone can combine into O 2. This set of reactions govern the production of ozone and can be combined to calculate its equilibrium concentration. Azobisisobutyronitrile is a white powder often used as a photoinitiator for vinyl-based polymers such as polyvinyl chloridealso known as PVC.
Benzoyl peroxide, much like azobisisobutyronitrile, is a white powder used as a photoinitiator in various commercial and industrial processes, including plastics production.
Free Radicals, Reactive Oxygen Species, and Their Biomarkers
Unlike AIBN, however, benzoyl peroxide produces oxygen gas upon decomposing, giving this compound a host of medical uses as well. Upon oxygen radicals svenska with the skin, benzoyl peroxide breaks down, producing oxygen gas, among other things. The oxygen gas is absorbed into the pores of the skin, where it kills off the acne-causing bacterium Cutibacterium acnes.
In addition, the free radicals produced can break down dead skin cells. Clearing out these dead cells prevents pore blockage and, by extension, acne breakouts. Camphorquinone CQ is a photosensitiser used with an amine system, that generates primary radicals with light irradiation. These free electron then attack the double bonds of resin monomers resulting in polymerization.
The physical properties of the cured resins are affected by the generation of primary radicals during the initial stage of polymerization. Irgacure BAPO Bis 2,4,6-trimethylbenzoyl -phenylphosphineoxide is a Norrish type photoinitiator used in polymerization processes like two-photon Polymerization. The second set of radicals forms through abstraction or chain transfer, further driving the reaction.
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Reactive oxygen species (ROS) as pleiotropic physiological signalling agents
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oxygen radicals - Swedish translation - Linguee
Wikidata item. Molecule which creates reactive species when exposed to radiation. Reactions [ edit ]. Atmospheric photoinitiators [ edit ]. Peroxides [ edit ]. Nitrogen dioxide [ edit ].