Additively written group

Let M be an additively written group (with neutral element 0). 

An (additively written) group is called a ring if it is a group over itself. 

This addition reaction can be repeated over and over in the propagation process, and each step adds two CH2 groups to the growing polymer chain. The propagation can be written in the following general form ... 

The toxicological data will be sent to a WHO expert for evaluation, with a second expert appointed to comment on the report prepared for submission to the Expert Committee. The specification will be written based on information submitted by an FAO expert, and another FAO expert will consider the likely consumption. When the Expert Committee meets, these three groups of people discuss the aspects of the toxicology, specification and likely consumption before an additive is approved and an ADI is allocated. 

In addition to the material balance equation for the surface hydroxyl groups listed above, a charge balance equation can be written ... 

On the basis of Equation 15, the increment in /Jg by the addition of a methylene group to the hydrocarbon chain of surfactant, (CH2), is written as... 

Prior to any work on heteroatom clusters the notion was expressed (20) that heteroatom placement within the polyatomic clusters would lead to a decrease In delocalization and bonding and thence stability. Although this may lessen stability the substitution clearly does not preclude It. Furthermore, many of the likely polyhedra already have Inequlvalent atom positions, the 5, 7, 9 and 10 atom examples already considered here for example, and mixed species especially with elements from different groups may be quite stable within the discrimination provided by Inequlvalent positions. Even the nominally equivalent atom positions In a tetrahedron can obviously accommodate substantial differences. Additional examples of mixed element polycations are certainly to be expected. An Inadequate foresight was revealed In a review of polycations (20) written for a 1974 award symposium, about one year before the crypt discoveries, by the expectation that polycations should be more stable than polyanions for the metallic elements. In hindsight, metallic behavior Is a property of the dense solid state and has little to do with the stability of small clusters where electronic and geometric factors are far more important. 

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