Occurrence and Function

Ozone has received increased attention for its occurrence and function in the Earth s atmosphere.For example the decreasing ozone concentration in the stratospheric ozone layer, becoming most obvious with the Antarctic ozone hole. 

In previous reviews on this matter by Gogelein [9] and myself [10] it has been pointed out that the Cl -channels of the central nervous system and of skeletal muscle are distinct from those of non-excitable cells. The latter entity is in itself obviously heterogeneous with respect to its occurrence and function. In apolar as well as in polarized cells Cl -channels may be involved in volume regulation. As a simple rule gating of K" - and Cl -channels is likely to occur whenever cell volume has to be down-regulated [11], as is the case in regulatory volume decrease of cell volume. A simple means to induce this phenomena is the exposure of cells to hypoosmolar solutions [12]. For example Cl -channels play an important role in... 

The two conditions stated above do not assure the occurrence of gelation. The final and sufficient condition may be expressed in several ways not unrelated to one another. First, let structural elements be defined in an appropriate manner. These elements may consist of primary molecules or of chains as defined above or they may consist of the structural units themselves. The necessary and sufficient condition for infinite network formation may then be stated as follows The expected number of elements united to a given element selected at random must exceed two. Stated alternatively in a manner which recalls the method used in deriving the critical conditions expressed by Eqs. (7) and (11), the expected number of additional connections for an element known to be joined to a previously established sequence of elements must exceed unity. However the condition is stated, the issue is decided by the frequency of occurrence and functionality of branching units (i.e., units which are joined to more than two other units) in the system, on the one hand, as against terminal chain units (joined to only one unit), on the other. 

Occurrence and function Main mineral form Composition... 

Bailey, S., N. Mann, C. Robinson, and D. J. Scanlan (2005). The occurrence of rapidly reversible non-photochemical quenching of chlorophyll a fluorescence in cyanobacteria. FEBS Lett 579(1) 275-280. Boulay, C., L. Abasova, C. Six, I. Vass, and D. Kirilovsky (2008a). Occurrence and function of the orange carotenoid protein in photoprotective mechanisms in various cyanobacteria. Biochim Biophys Acta 1777(10) 1344-1354. 

Families of hydrogenases, their occurrence and function Genotypes used to describe hydrogenases, their accessory genes and related functions... 

Essential oil, also defined as essence, volatile oil, etheric oil or aetheroleum, is a complex mixture of volatile constituents biosynthesised by living organisms. Essential oils can be liberated from their matrix by water, steam and dry distillation, or expression in the case of citrus fruits [1-5]. Their occurrence and function in nature is still a question and the subject of ongoing research. However, there is evidence that organisms produce essential oils for defence, signalling or as part of their secondary metabolism. As a consequence essential oils comprise an important bio resource for renewable natural products [1-25]. 

MertzW. 1969. Chromium occurrence and function in biological systems. Physiol Rev 49(2) 163-239. 

Kimelberg HK (1986) Occurrence and functional significance of serotonin and catecholamine uptake by astrocytes. Biochem Pharmacol 35 2273-2281. 

Brief, general reviews of chitin chemistry exist,as do accounts of fungal chitin. The occurrence and function of chitin in arthropod cuticles are dealt with at length by Richards. The purpose of the present Chapter is to present a more comprehensive account of the chemistry and biochemistry of chitin. 

Williams CM, Couch MW, Thonoor CM,Midgley JM. Isomeric octopamines their occurrence and functions. J Pharm Pharmacol 1987 39 153-157. 

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