Medical research

Nitric oxide could make blood transfusions safer

(Medical Xpress)—Blood transfusions are supposed to save lives. Doctors give transfusions to severely ill or injured people with the expectation that their conditions will improve. In fact, transfusions do not always help ...

Medical research

'Moonlighting' enzyme unravels arginine paradox

(Medical Xpress) -- Nearly 20 years ago, the journal Science tagged nitric oxide as the "molecule of the year." Since that time, researchers have tried to study and target this simple molecule that is involved in virtually ...


Newly discovered mechanism regulates myocardial distensibility

A healthy heart beats 50 to 100 times a minute and pumps 8,000 liters of blood around our body every day. A precondition for this function is the elasticity of the cardiac walls, which dilate as blood flows in (diastole) ...


Prevention of heart disease can start before birth

Babies that experience low oxygen levels in the womb due to pregnancy complications often go on to develop heart disease in adulthood. A study using sheep has discovered that a specialised antioxidant called MitoQ can prevent ...

Medical research

The secret of lymph: How lymph nodes help cancer cells spread

For decades, physicians have known that many kinds of cancer cells often spread first to lymph nodes before traveling to distant organs through the bloodstream. New research from Children's Medical Center Research Institute ...

Medical research

Stopping tooth decay before it starts—without killing bacteria

Oral bacteria are ready to spring into action the moment a dental hygienist finishes scraping plaque off a patient's teeth. Eating sugar or other carbohydrates causes the bacteria to quickly rebuild this tough and sticky ...


Antioxidant cocktail key to preventing Alzheimer's

Research from The University of Western Australia has found a diet rich in nutrients and antioxidants may prevent or even reverse the effects of Alzheimer's disease.

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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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