Cellular or Dendritic Growth

FIGURE 6.33 Schematic illustration of the characteristic cored microstmcture that can arise due to compositional partitioning effects during a nucleation-and-growth process. 

LIQUID-SOLID AND SOLID-SOLID PHASE TRANSFORMATIONS 

FIGURE 6 Schematic illustration of (a) stable planar (or spherical) growth, (b) unstable cellular growth, and (c) dendritic growth. 

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Growth front instability during transformation can lead to cellular or dendritic microstructures, depending on the severity of the instability. Minor instability leads to the formation of primary protuberances, called cells, which advance perpendicular to the interface. If the instability increases, these primary protuberances can themselves spawn secondary protuberances perpendicular to the primary protuberances, and a dendritic microstmcture develops. Cellular and dendritic microstructures are most commonly observed in vapor-solid or liquid-solid phase transformations, although they can also be formed in solid-solid phase transformations. 

The presence of dislocations can have marked effects. A number of factors can lead to the production of dislocations during growth from the melt. In the presence of impurities when cellular or dendritic interfaces are formed (see Section 4.5), a well-developed dislocation substructure is produced. On a large scale the trapping of foreign particles can produce dislocations both to accommodate mismatch at the particle-solid interface and as a result of misfit stresses.The presence of impurity particles also leads to the development of the dislocation array of sub-boundaries produced during solidification, known as the Uneage structme. "... 

The approach of biochemical purification combined with high-resolution mass spectrometiy used for the definition of the PSP could be easily applied to many other sub-cellular structures. Indeed, subcellular structures, such as axo-glial junctions and nodes of Ranvier would be prime candidates for such an approach. Also, refined or new biochemical approaches to isolate structures such as dendrites, axons and growth cones would facilitate definition of other neuronal proteomes. 

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