Conglomerate structures

Flax is stained blue by zinc chloride-iodine reagent (see Section 8.5.6), as are all other cellulose fibres. In addition the typical V- and X-shaped transverse structures can be seen more clearly. Differentiation from hemp can be made by means of a cross-sectional sample. Flax shows clearly visible irregular polygons with lumen, hemp shows relatively indistinct and often conglomerate structures. 

In addition to the relatively conglomerate structures of the potassium, rubidium, and cesium polymers, there are other characteristics of these polymers, or polymer systems, which may make them unsuitable for practical development as rubbers. The molecular weight of the polymer in these systems decreases as the electropositivity of the metal catalyst increases. Thus, all rubidium and cesium polymers produced so far have been very low in molecular weight. Other disadvantages are the high cost and the safety hazard connected with the use of these metals. 

Chemical development Proof of structure and configuration are required as part of the information on chemical development. The methods used at batch release should be validated to guarantee the identity and purity of the substance. It should be established whether a drug produced as a racemate is a true racemate or a conglomerate by investigating physical parameters such as melting point, solubility and crystal properties. The physicochemical properties of the drug substance should be characterized, e.g. crystallinity, polymorphism and rate of dissolution. 

The starting system is achiral (plates at 90° with isotropic fluid between), but leads to the formation of a chiral TN structure when the fluid becomes nematic. In this case, enantiomeric domains must be formed with equal likelihood and this is precisely what happens. The size of these domains is determined by the geometry and physics of the system, but they are macroscopic. Though the output polarization is identical for a pair of heterochiral domains, domain walls between them can be easily observed by polarized light microscopy. This system represents a type of spontaneous reflection symmetry breaking, leading to formation of a conglomerate of chiral domains. 

Efforts aimed at understanding the structure of this fascinating type of conglomerate are in progress. Unfortunately, the most fundamental aspect of the structure of B4—whether it is crystalline or a liquid crystalline—is not firmly established. That is, at this point it is not clear whether the B4 phase is a fluid conglomerate or a very novel version of a crystal conglomerate. This ambiguity, however, is emphatically absent in the B2 electro-optically active family of phases, as discussed below. 

A conglomerate of three hexagons contains one central atom and 12 atoms around it. A conglomerate of seven hexahedrons comprises 12 external and 12 internal (common) atoms. In these two cases geometric centers of hybridized molecular orbitals of each hexahedron are equidistant from such nearest centers of a conglomerate. This, apparently, explains the experimental fact that polyhedrons of carbon clusters represent an icosahedron - 12-apex crystalline structure each apex of which is connected with five other apexes. 

Crystals composed of the R and S enantiomers of the same racemic mixture must be related by mirror symmetry in terms of both their internal structure and external shape. Enantiomorphous crystals may be sorted visually only if the crystals develop recognizable hemihedral faces. [Opposite (hid) and (hkl) crystal faces are hemihedral if their surface structures are not related to each other by symmetry other than translation, in which case the crystal structure is polar along a vector joining the two faces. Under such circumstances the hemihedral (hkl) and (hkl) faces may not be morphologically equivalent.] It is well known that Pasteur s discovery of enantiomorphism through die asymmetric shape of die crystals of racemic sodium ammonium tartrate was due in part to a confluence of favorable circumstances. In the cold climate of Paris, Pasteur obtained crystals in the form of conglomerates. These crystals were large and exhibited easily seen hemihedral faces. In contrast, at temperatures above 27°C sodium ammonium tartrate forms a racemic compound. 

---