The guardian angels of the source of the Seine
The river Seine, the centerpiece of the Paris Olympics opening ceremony in July, starts with a few drops of water in a mossy grotto deep in the woods of central France.
The river Seine, the centerpiece of the Paris Olympics opening ceremony in July, starts with a few drops of water in a mossy grotto deep in the woods of central France.
Environment
Apr 25, 2024
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Peregrine falcon populations across North America are heavily contaminated with harmful flame retardants–including those that have been phased out for years—according to a new study published in Environmental Science ...
Environment
Apr 9, 2024
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Epoxy resin (EP), an essential material in various applications such as adhesives, coatings, and composites, faces challenges due to its intrinsic flammability and dense smoke production, posing threats to safety and property. ...
Analytical Chemistry
Mar 25, 2024
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Organophosphorus flame retardants are a possible alternative to brominated flame retardants. However, comparative life cycle studies on this type of flame retardant are still lacking.
Analytical Chemistry
Mar 22, 2024
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26
Understanding how a thermonuclear flame spreads across the surface of a neutron star—and what that spreading can tell us about the relationship between the neutron star's mass and its radius—can also reveal a lot about ...
Astronomy
Mar 21, 2024
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2107
Since the first report of metal-organic framework (MOF)-based flame retardants in 2017, this research area has exploded. However, improving the flame-retardant efficiency of MOFs and expanding their application areas remain ...
Analytical Chemistry
Feb 20, 2024
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Research on the International Space Station is helping scientists to understand how fire spreads and behaves in different environments and learn how to prevent and extinguish fires in space.
Space Exploration
Dec 28, 2023
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More than 150 species of wild animals across every continent are contaminated with flame retardant chemicals, according to a new map tracking peer-reviewed research worldwide.
Environment
Oct 18, 2023
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A research group led by assistant professor Wu Chengyuan from Yunnan Observatories of the Chinese Academy of Sciences has investigated the evolution of post-merger remnant resulting from the coalescence of double oxygen-neon ...
Astronomy
Sep 27, 2023
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25
Eighteen suspected migrants were found dead Tuesday in a Greece forest fire near the Turkish border as scores of firefighters battled to contain the second deadly wave of blazes to hit the country in a month.
Environment
Aug 22, 2023
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A flame (from Latin flamma) is the visible (light-emitting), gaseous part of a fire. It is caused by a highly exothermic reaction (for example, combustion, a self-sustaining oxidation reaction) taking place in a thin zone. If a fire is hot enough to ionize the gaseous components, it can become a plasma.
Color and temperature of a flame are dependent on the type of fuel involved in the combustion, as, for example, when a lighter is held to a candle. The applied heat causes the fuel molecules in the candle wax to vaporize. In this state they can then readily react with oxygen in the air, which gives off enough heat in the subsequent exothermic reaction to vaporize yet more fuel, thus sustaining a consistent flame. The high temperature of the flame causes the vaporized fuel molecules to decompose, forming various incomplete combustion products and free radicals, and these products then react with each other and with the oxidizer involved in the reaction. Sufficient energy in the flame will excite the electrons in some of the transient reaction intermediates such as CH and C2, which results in the emission of visible light as these substances release their excess energy (see spectrum below for an explanation of which specific radical species produce which specific colors). As the combustion temperature of a flame increases (if the flame contains small particles of unburnt carbon or other material), so does the average energy of the electromagnetic radiation given off by the flame (see blackbody).
Other oxidizers besides oxygen can be used to produce a flame. Hydrogen burning in chlorine produces a flame and in the process emits gaseous hydrogen chloride (HCl) as the combustion product. Another of many possible chemical combinations is hydrazine and nitrogen tetroxide which is hypergolic and commonly used in rocket engines. Fluoropolymers can be used to supply fluorine as an oxidizer of metallic fuels, e.g. in the magnesium/teflon/viton composition.
The chemical kinetics occurring in the flame are very complex and involves typically a large number of chemical reactions and intermediate species, most of them radicals. For instance, a well-known chemical kinetics scheme, GRI-Mech, uses 53 species and 325 elementary reactions to describe combustion of biogas.
There are different methods of distributing the required components of combustion to a flame. In a diffusion flame, oxygen and fuel diffuse into each other; where they meet the flame occurs. In a premixed flame, the oxygen and fuel are premixed beforehand, which results in a different type of flame. Candle flames (a diffusion flame) operate through evaporation of the fuel which rises in a laminar flow of hot gas which then mixes with surrounding oxygen and combusts.
This text uses material from Wikipedia, licensed under CC BY-SA