Addition of hexagon

The principles of the last mentioned computations were different from all of those mentioned above, although h was chosen as the leading parameter, and the additions of hexagons were employed. In these computations the different options [31] were exploited to a high degree, whereby the different types of additions (cf. Sect. 2.2) played an important role in the algorithm. The basic principles, which are of relevance to the computations in question, are treated in the next section. 

Another instructive example is found in Fig. 2 The first three systems therein (r + he+ e) illustrate the same features as Fig. 1 with respect to the Kekule structure counts (/iQ. The systems are again obtained by successive additions of hexagons, but four hexagons are added each time in this case. The last system (Fig. 2), obtained by adding four hexagons into the corona hole of the e system, is a concealed non-Kekulean (o). This set of single coronoids illustrate nicely the rheo classification. 

Figures 1 and 2 emphasize the anomalous behaviour of Kekule structure counts for irregular single coronoids. However, it is not always so that the K numbers decrease through similar sets of coronoids as in these figures. The opposite situation is observed in Fig. 3, where again one he and one e system is produced by successive additions of hexagons to a regular (r) coronoid six hexagons are added each time. In this case the K numbers happen to increase udth increasing h in the "normal" way.

Single corofusenes can be produced in copious amounts by additions of hexagons to primitive single coronoids all the five addition modes (viz. 5 cf. Vol. I—Fig. 2.2... 

Figure 1 shows the smallest perfect ground forms (G ), one for each formula. The depicted isomers are those generated by the spiral walk. The reader is referred to Fig. 4.6, which shows the corresponding circular coronoids, 0, from which the ground forms are generated by two-contact additions of hexagons, one to each 0. 

Benzenoids and coronoids can be generated (or built up) by additions of hexagons to the perimeters (Vol. 1-2.1.1 Cyvin BN, Brunvoll and Cyvin 1992b) see also Par. 6.5.1. The addition modes are Li, P2> Pi acorona hole is created. 

Fig. 1. An amplified outline scheme of the making of various wiaes, alternative products, by-products, and associated wastes (23). Ovals = raw materials, sources rectangles = wines hexagon = alternative products (decreasing wine yield) diamond = wastes. To avoid some complexities, eg, all the wine vinegar and all carbonic maceration are indicated as red. This is usual, but not necessarily tme. Similarly, malolactic fermentation is desired in some white wines. FW = finished wine and always involves clarification and stabilization, as in 8, 11, 12, 13, 14, 15, 33, 34, followed by 39, 41, 42. It may or may not include maturation (38) or botde age (40), as indicated for usual styles. Stillage and lees may be treated to recover potassium bitartrate as a by-product. Pomace may also yield red pigment, seed oil, seed tannin, and wine spidts as by-products. Sweet wines are the result of either arresting fermentation at an incomplete stage (by fortification, refrigeration, or other means of yeast inactivation) or addition of juice or concentrate.

The Bertrand lens, an auxiliary lens that is focused on the objective back focal plane, is inserted with the sample between fully crossed polarizers, and the sample is oriented to show the lowest retardation colors. This will yield interference figures, which immediately reveal whether the sample is uniaxial (hexagonal or tetragonal) or biaxial (orthorhombic, monoclinic, or triclinic). Addition of the compensator and proper orientation of the rotating stage will further reveal whether the sample is optically positive or negative. 

R = (i/ r) require translations t in addition to rotations j/. The irreducible representations for all Abelian groups have a phase factor c, consistent with the requirement that all h symmetry elements of the symmetry group commute. These symmetry elements of the Abelian group are obtained by multiplication of the symmetry element./ = (i/ lr) by itself an appropriate number of times, since R = E, where E is the identity element, and h is the number of elements in the Abelian group. We note that N, the number of hexagons in the ID unit cell of the nanotube, is not always equal h, particularly when d 1 and dfi d. 

Carbonyl hydrides and carbonylate anions are obtained by reducing neutral carbonyls, as mentioned above, and in addition to mononuclear metal anions, anionic species of very high nuclearity have been obtained, often by thermolysis. These are especially numerous for Rh and in certain Rh, Rh and Rhi5 anions have structures conveniently visualized either as polyhedra encapsulating further metal atoms, or alternatively as arrays of metal atoms forming portions of hexagonal close packed or body... 

Chalcogenides of Cd are similar to those of Zn and display the same duality in their structures. The sulfide and selenide are more stable in the hexagonal form whereas the telluride is more stable in the cubic form. CdS is the most important compound of cadmium and, by addition of CdSe, ZnS, HgS, etc., it yields thermally stable pigments of brilliant colours from pale yellow to deep red, while colloidal dispersions are used to colour transparent glasses. 

Torkar et al. [702,706—708] identified nucleation as an autocatalytic process at the (hk0) planes of hexagonal platelets of NaN3. The decelera-tory reaction fitted the first-order equation [eqn. (15)]. Values of E tended to be irreproducible for the pure salt E was about 180 kJ mole 1 but this was reduced to about half by doping. This influence of an additive and the observed similarities in magnitudes of E for decomposition and for diffusion were interpreted as indicating that growth of nuclei was controlled by a diffusion process. 

The applications of hexagonal boron nitride form an important market, mostly as powder for lubricants and additives. Many of these applications are produced by CVD. 

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