Climate crisis ages fish, amphibians and reptiles

Climatic conditions are changing at an unprecedented rate, affecting mainly fish, amphibians and reptiles, ectothermic animals that are unable to generate their own internal heat. With heat waves and rising temperatures, ...

Energy harvesting goes organic, gets more flexible

Nanogenerators capable of converting mechanical energy into electricity are typically made from metal oxides and lead-based perovskites. But these inorganic materials aren't biocompatible, so the race is on to create natural ...

When methane-eating microbes eat ammonia instead

As a side effect of their metabolism, microorganisms living on methane can also convert ammonia. In the process, they produce nitric oxide (NO), a central molecule in the global nitrogen cycle. Scientists from the Max Planck ...

Methane-eating bacteria like nitrogen, too

Methane-eating bacteria can degrade ammonium in addition to methane, as discovered by microbiologists at Radboud University and the Max Planck Institute in Bremen. Methane-eaters are important for the reduction of greenhouses ...

Tryptophan supports intestinal tracts of stressed trouts

A biologist from RUDN University has found the most beneficial concentration of tryptophan for rainbow trout. When added to the diet of the fish, this amino acid supports the immune system and reduces oxidative stress in ...

Nano particles for healthy tissue

"Eat your vitamins" might be replaced with "ingest your ceramic nano-particles" in the future as space research is giving more weight to the idea that nanoscopic particles could help protect cells from common causes of damage.

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An oxide ( /ˈɒksaɪd/) is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2.

Most of the Earth's crust consists of solid oxides. Oxides result when elements are oxidized by oxygen in air. Combustion of hydrocarbons affords the two principal oxides of carbon, carbon monoxide and carbon dioxide. Even materials that are considered to be pure elements often contain a coating of oxides. For example, aluminium foil has a thin skin of Al2O3 that protects the foil from further corrosion.

Virtually all elements burn in an atmosphere of oxygen, or an oxygen rich environment. In the presence of water and oxygen (or simply air), some elements—lithium, sodium, potassium, rubidium, caesium, strontium and barium—react rapidly, even dangerously, to give the hydroxides. In part for this reason, alkali and alkaline earth metals are not found in nature in their metallic, i.e., native, form. Caesium is so reactive with oxygen that it is used as a getter in vacuum tubes, and solutions of potassium and sodium, so called NaK are used to deoxygenate and dehydrate some organic solvents. The surface of most metals consists of oxides and hydroxides in the presence of air. A well known example is aluminium foil, which is coated with a thin film of aluminium oxide that passivates the metal, slowing further corrosion. The aluminium oxide layer can be built to greater thickness by the process of electrolytic anodising. Although solid magnesium and aluminium react slowly with oxygen at STP, they, like most metals, will burn in air, generating very high temperatures. Finely grained powders of most metals can be dangerously explosive in air. Consequently, they are often used in Solid-fuel rockets.

In dry oxygen, iron readily forms iron(II) oxide, but the formation of the hydrated ferric oxides, Fe2O3−2x(OH)x, that mainly comprise rust, typically requires oxygen and water. The production of free oxygen by photosynthetic bacteria some 3.5 billion years ago precipitated iron out of solution in the oceans as Fe2O3 in the economically important iron ore hematite.

Due to its electronegativity, oxygen forms chemical bonds with almost all elements to give the corresponding oxides. Noble metals (such as gold or platinum) resist direct chemical combination with oxygen, and substances like gold(III) oxide must be generated by indirect routes.

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