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  2. Hydrogen cycle - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_cycle

    The hydrogen cycle consists of hydrogen exchanges between biotic (living) and abiotic (non-living) sources and sinks of hydrogen-containing compounds. Hydrogen (H) is the most abundant element in the universe. [1] On Earth, common H-containing inorganic molecules include water (H 2 O), hydrogen gas (H 2), hydrogen sulfide (H 2 S), and ammonia ...

  3. Marine biogeochemical cycles - Wikipedia

    en.wikipedia.org/wiki/Marine_biogeochemical_cycles

    Given the ubiquity of hydrogen atoms in inorganic and organic chemical compounds, the hydrogen cycle is focused on molecular hydrogen (H 2). Nitrogen The nitrogen cycle is the process by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere , terrestrial , and marine ecosystems .

  4. Biogeochemical cycle - Wikipedia

    en.wikipedia.org/wiki/Biogeochemical_cycle

    A biogeochemical cycle, or more generally a cycle of matter, [1] is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust. Major biogeochemical cycles include the carbon cycle , the nitrogen cycle and the water cycle .

  5. Hydrogen - Wikipedia

    en.wikipedia.org/wiki/Hydrogen

    Hydrogen is a chemical element; ... Phase diagram of hydrogen. ... The natural cycle of hydrogen production and consumption by organisms is called the hydrogen cycle.

  6. Water splitting - Wikipedia

    en.wikipedia.org/wiki/Water_splitting

    The sulfur–iodine cycle (S–I cycle) is a series of thermochemical processes used to produce hydrogen. The S–I cycle consists of three chemical reactions whose net reactant is water and whose net products are hydrogen and oxygen. All other chemicals are recycled. The S–I process requires an efficient source of heat.

  7. CNO cycle - Wikipedia

    en.wikipedia.org/wiki/CNO_cycle

    The CNO cycle (for carbon–nitrogen–oxygen; sometimes called Bethe–Weizsäcker cycle after Hans Albrecht Bethe and Carl Friedrich von Weizsäcker) is one of the two known sets of fusion reactions by which stars convert hydrogen to helium, the other being the proton–proton chain reaction (p–p cycle), which is more efficient at the Sun's ...

  8. As the military changes policy, the Army will no longer ...

    www.aol.com/military-changes-policy-army-no...

    The U.S. Army says transgender individuals may no longer join the service. While other branches have not yet made similar posts announcing the change, it is expected across the military.

  9. Hydrogen production - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_production

    In this method, iodine-sulfur (IS) thermo-chemical cycle for splitting water and high-temperature steam electrolysis (HTSE) were selected as the main processes for nuclear hydrogen production. The S-I cycle follows three chemical reactions: [100] Bunsen reaction: I 2 +SO 2 +2H 2 O→H 2 SO 4 +2HI HI decomposition: 2HI→H 2 +I 2