Units growth

Figure 5.4 Attachment of a growth unit into a kink site...

The seeond-order dependenee of the growth rate on the supersaturation ean be explained by a number of growth theories. The most eonvineing, however, is that of Burton etal. (1951). In their BCF theory about the serew disloeation eentred surfaee spiral step, it is assumed that growth units enter at kinks with a rate proportional to cr and that the kink density is also proportional to cr whieh gives the faetor cr in the rate expression. 

S. C. Ke, L. J. DeLucas, J. G. Harrison. Computer simulation of protein crystal growth using aggregates as the growth unit. J Phy D 57 1064, 1998. 

Fig. 4.1a-c. Various types of roughness which may occur on the growth face of a lamella (The details of the polymer are not shown), a All growth units are complete stems which are of the same length, b Stems may be of differing lengths, c Growth units are only parts of complete stems... 

Materials and methods. Each species studied was grown in the greenhouse in a growth unit constructed from 10 cm PVC drain pipe and T-fittings, as described previously. The growth units were filled with an artificial soil mix of perlite/coarse sand/coarse vermlculite 3/2/1 by volume. On the second and fifth day of each week four liters of a full strength Peter s Hydro-sol solution plus calcium nitrate (36.7 g/37.8 liters plus 17.0 g Ca(N03 )2 /37.8 liters) were added to each growth... 

Soybean bloassays of root exudates. Four soybean seeds ( Bragg ) were planted In each of 100 12.5 cm plastic pots filled with an artificial soil mix consisting of perlite/coarse sand/coarse vermiculite 3/2/1 by volume. After one week the plants were thinned to two per pot and the treatments were begun. The experimental design was a completely randomized design with 10 replications (pots) per treatment. On the first day of each week each pot was watered with 300 ml effluent from the appropriate growth units. On the fifth day of each week all pots were watered with Peter s Hydro-sol solution with CaCNOj. At other times the pots were watered as needed with tap water. On the second and fifth day of each week the height of the soybeans (base to apical bud) was measured. 

A single adsorbed ion is only bonded in one direction, whereas an ion in a kink is bonded in three directions. Growth is therefore likely to proceed through addition of growth units (molecules or ions) at kinks. 

What differentiates CVD from other evaporation techniques is that growth units, the fundamental bricks essential for growth, are chemically generated at the mixing zone. The formation of growth units implies either chemical reaction of the... 

Figure 3.3. Various features of diffusion and convection associated with crystal growth in solution (a) in a beaker and (b) around a crystal. The crystal is denoted by the shaded area. Shown are the diffusion boundary layer (db) the bulk diffusion (D) the convection due to thermal or gravity difference (T) Marangoni convection (M) buoyancy-driven convection (B) laminar flow, turbulent flow (F) Berg effect (be) smooth interface (S) rough interface (R) growth unit (g). The attachment and detachment of the solute (solid line) and the solvent (open line) are illustrated in (b).

H. Komatsu, Coincidence site conjugation of cholesterol monohydrate crystals, in Morphology and Growth Unit of Crystals, ed. I. Sunagawa, Tokyo, Terra Scientific Publications, 1989, pp. 761-75... 

Uniform attachment of growth units (i.e., solute molecules) to a surface that is rough on a molecular scale... 

Uniform attachment of growth units mechanism. This mechanism refers to the situation where there is a discontinuous process of layer-by-layer adsorption of molecules onto a crystal surface that is rough on a molecular scale. This surface roughness provides numerous nuclei for attachment of solute molecules. The crystal growth rate is proportional to the driving force ... 

Altering the adsorption layer at the solid-liquid interface, therefore affecting the integration of growth units... 

Instead of supramolecular synthons, in nucleation work it is more common to talk about a growth unit defined as the es-sential building block that transfers structural information from the solution to the crystal surface. The relationship between supramolecular synthons, which come from observation of complete crystal structures, and growth units, is at present poorly understood. 

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