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Hydrogen is produced by hydrogenases and nitrogenases enzymes in many microorganisms, some of which are being studied for their potential for biofuel production. [ 8 ] [ 9 ] These H 2 -metabolizing enzymes are found in all three domains of life , and out of known genomes over 30% of microbial taxa contain hydrogenase genes. [ 10 ]
Liquid and solid phases can exist in combination at the triple point, a substance known as slush hydrogen. [39] Metallic hydrogen, a phase obtained at extremely high pressures (in excess of 400 gigapascals (3,900,000 atm; 58,000,000 psi)), is an electrical conductor. It is believed to exist deep within giant planets like Jupiter. [38] [40]
Natural hydrogen (known as white hydrogen, geologic hydrogen, [1] geogenic hydrogen, [2] or gold hydrogen) is molecular hydrogen present on Earth that is formed by natural processes [3] [4] (as opposed to hydrogen produced in a laboratory or in industry).
False-color Cassini radar mosaic of Titan's north polar region; the blue areas are lakes of liquid hydrocarbons. "The existence of lakes of liquid hydrocarbons on Titan opens up the possibility for solvents and energy sources that are alternatives to those in our biosphere and that might support novel life forms altogether different from those on Earth."—NASA Astrobiology Roadmap 2008 [1]
"We can trust these results," Glavin said. Bennu's icy parent body, perhaps about 60 miles (100 km) in diameter, appears to have formed in the outer solar system and was later destroyed, possibly ...
Pie charts of typical human body composition by percent of mass, and by percent of atomic composition (atomic percent) Body composition may be analyzed in various ways. This can be done in terms of the chemical elements present, or by molecular structure e.g., water , protein , fats (or lipids ), hydroxyapatite (in bones), carbohydrates (such ...
Interest is high in this technology because H 2 is a clean fuel and can be readily produced from certain kinds of biomass, [2] including biological waste. [3] Furthermore some photosynthetic microorganisms are capable to produce H 2 directly from water splitting using light as energy source.
The triple point is at a temperature of 273.16 K (0.01 °C; 32.02 °F) and a pressure of 611.657 pascals (0.00604 atm; 0.0887 psi); [71] it is the lowest pressure at which liquid water can exist. Until 2019, the triple point was used to define the Kelvin temperature scale. [72] [73]