hydrogen cycle
21Biogeochemical cycle — A commonly cited example is the water cycle. In ecology and Earth science, a biogeochemical cycle or substance turnover or cycling of substances is a pathway by which a chemical element or molecule moves through both biotic (biosphere) and… …
22Oxygen cycle — The oxygen cycle. The Oxygen cycle is the biogeochemical cycle that describes the movement of oxygen within its three main reservoirs: the atmosphere (air), the total content of biological matter within the biosphere (the global sum of all… …
23Mercury cycle — The mercury cycle is a biogeochemical cycle involving mercury. Mercury is notable for being the only heavy metal which is liquid at room temperature. It is a volatile metal and evaporates easily, going into the atmosphere.[citation needed]… …
24Sulfur-iodine cycle — 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… …
25Copper-chlorine cycle — Simplified diagram of the Copper Chlorine cycle The copper chlorine cycle (Cu Cl cycle) is a four step thermochemical cycle. It has a maximum temperature requirement of about 530 degrees Celsius.[1] The Cu Cl cycle is one of the prominent… …
26CNO cycle — Overview of the CNO I Cycle. The CNO cycle (for carbon–nitrogen–oxygen) is one of two sets of fusion reactions by which stars convert hydrogen to helium, the other being the proton–proton chain. Unlike the proton–proton chain reaction, the CNO… …
27Cerium(IV) oxide-cerium(III) oxide cycle — Simplified diagram of the Cerium(IV) oxide cerium(III) oxide cycle The cerium(IV) oxide cerium(III) oxide cycle or CeO2/Ce2O3 cycle is a two step thermochemical process based on cerium(IV) oxide and cerium(III) oxide for hydrogen production.[1] …
28Sulfur cycle — Sulfur is one of the constituents of many proteins, vitamins and hormones. It recycles as in other biogeochemical cycles.The essential steps of the sulfur cycle are: * Mineralization of organic sulfur to the inorganic form, hydrogen sulfide:… …
29Q cycle — History The Q cycle describes a series of reactions first proposed by Peter Mitchell that describe how the sequential oxidation and reduction of the lipophilic electron carrier, ubiquinol ubiquinone (a.k.a. Coenzyme Q), can result in the net… …
30Nuclear fuel cycle — The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. It consists of steps in the front end, which are the preparation of the fuel, steps in the service period in which… …
