Entity Solid

This chapter summarizes, completes, and compares elementary curves, elementary surfaces, offset geometric entities, solid primitives, and form features. An elementary shape exists as an individual shape and has its own type, shape characteristics, and attributes. On the other hand, it is a segment or a structural element of a more complex shape and its characteristics and attributes probably depend on other elements in the complex shape. 

ENTITY SOLID MODEL = CLASS( POLY HEDRON, B REP,... 

From a general point of view, the tautomeric studies can be divided into 12 areas (Figure 20) depending on the migrating entity (proton or other groups, alkyl, acyl, metals. ..), the physical state of the study (solid, solution or gas phase) and the thermodynamic (equilibrium constants) or the kinetic (isomerization rates) approach. 

The electrical conductivity in the solid state is determined by the product of the carrier concentration and the carrier mobility. In conjugated polymers both entities are material dependent and, i.e., are different for electrons and holes. Electrons or holes placed on a conjugated polymer lead to a relaxation of the surrounding lattice, forming so-called polarons which can be positive or negative. Therefore, the conductivity, o, is the sum of both the conductivity of positive (P+) and negative polarons (P ) ... 

There are many other examples of changes in which a solid passes into a liquid, or a liquid into a gas, with absorption of heat at constant temperature. The constant temperature may be called the transition temperature the heat absorbed is called the latent heat of the transition. The latter name is due to Joseph Black, the discoverer of the phenomenon (1757) he appears to have regarded the heat as existing latent in the body in some sort of chemical combination, just as fixed air exists latent in chalk. In both cases the entity has lost its properties by chemical combination, but may be set free again in a suitable way. 

Two product barrier layers are formed and the continuation of reaction requires that A is transported across CB and C across AD, assuming that the (usually smaller) cations are the mobile species. The interface reactions involved and the mechanisms of ion migration are similar to those already described for other systems. (It is also possible that solid solutions will be formed.) As Welch [111] has pointed out, reaction between solids, however complex they may be, can (usually) be resolved into a series of interactions between two phases. In complicated processes an increased number of phases, interfaces, and migrant entities must be characterized and this requires an appropriate increase in the number of variables measured, with all the attendant difficulties and limitations. However, the careful selection of components of the reactant mixture (e.g. the use of a common ion) or the imaginative design of reactant disposition can sometimes result in a significant simplification of the problems of interpretation, as is seen in some of the examples cited below. 

Adamantane (CAS No 281-23-2) l-tricyclo[3.3.1.1 ]decane is a cage hydrocarbon with a white or almost white crystalline solid nature, like solid wax, at normal conditions. Its odor resembles that of camphor. It is a stable and nonbiodegradable compound that is combustible due to its hydrocarbon nature. It has not been found to be hazardous or toxic to living entities [14, 15]. It should be pointed out that adamantane can exist in gas, liquid, and two solid crystalline states. 

Sometimes it so happens that crystals of a new salt are formed when solutions of two simple salts are mixed and the mixed solution is evaporated. The salt thus obtained is a distinct chemical substance in the solid state as well as in solution. In aqueous solution, it does not dissociate into all the simple ions of the salts it is obtained from, but yields complex ions along with the simple ions. Such a salt is known as a complex salt. A characteristic feature of complex salts is that in these the constituents retain their separate entities both in the solid state and in solution. Potassium ferrocynide, K4Fe(CN)6, is a complex salt and is obtained on mixing the solution of a ferrous salt with an excess of potassium cyanide solution. From its composition [Fe(CN)2,4 KCN], it appears to be a mixture of ferrous cyanide and potassium cyanide in the ratio of 1 4, and is thus taken to be an ordinary double salt. This representation of the compound is, however, not satisfactory since it responds neither to tests for Fe2+ ions nor to those for CN ions but does respond to tests for K+ ions and tetravalent Fe(CN)Jj ions. The ionization reaction of the complex salt cited in the present example can be represented as ... 

---