Growth rates measurement

Fig. 3.9 The positive effect of nitrogen fertilizer (potassium nitrate) on the growth and productivity of transgenic sprouts (A.) The growth rate, measured as the increase in fresh weight during sprouting.

Polymorphism also seems to influence the growth rate of filaments. In their AFM study of Sup35pNM filaments involving a compilation of the growth rates measured on many in dividual filaments, DePace and Weissmann (2002) found different classes, for example, fast on both ends, slow at one end, and so on (Section V.A Fig. 8). They were able to show in several rounds of growth analysis that growth rate is an intrinsic property for each class of filaments. 

Therefore a particular method was chosen (4). We worked on a statistical population of crystals in order to minimize the dispersion and on simultaneous measurement of all faces in order to compare their growth rate under the same conditions of supersaturation and temperature. Therefore classical (R,o ) isotherms were obtained. Experimentally we grew at the same time and in the same solution a single crystal and twin. Whereas growth rate measurements of the forms hOL are relatively simple (thanks to the fact that the b axis is a binary axis) (Figure lb), the kinetic measurements of the p 110 and p llO forms are more difficult. 

A modern and very exact method of growth rate measurements is the laser-scanner. The disadvantage of this method is, that it can only be used on the outside of tubes. In the industrial application the disadvantage is that by this method only one tube of a bundle of tubes can be measured at a time. 

From the results of analysis of the structural form of quartz crystal and the growth rate measurements on synthetic quartz, it has been well established that the difference in growth rates of r 1011] and z 0111] is small,... 

TqVjUo (with crs =aeonalon/cr being the ambipolar conductivity, see Section NlA.ii). Owing to its constancy the flux can be recast as (1/L) Jaod o r lus die growth rate measured by the thickness... 

From a practical viewpoint, ATiscc may be defined in terms of the limit of sensitivity of crack growth rate measurements, which typically is of the order of 1 X 10 cm/s, under the best circumstances. However, recognizing that the growth rate at the lower limit is controlled by creep, an argument can be made that the concept of a ATiscc is inappropriate because creep crack growth gradually transitions into environment-assisted crack growth as the environmental conditions become more conducive to the latter. 

Depending on the objectives and applications of growth rate measurements, the growth rate may be expressed as follows ... 

Myerson (2002), Mullin (2001), and Mersmann (2001) provide excellent descriptions of methods for crystal growth rate measurements. These methods involve measurements of either single crystals or suspensions. Much information can be gained from the traditional technique of measuring ( grab samples or in-line) solute concentration versus time in batch crystallization on a seed bed. Initial and later slopes on such a plot can provide multiple data points of growth rate versus supersaturation. 

Typically, using about 5 gm of monosized seed (usually a sieve fraction), and harvesting after several hours of operation, can produce an accurate and reproducible growth rate measurement. The effects of supersaturation (including the data in Fig. 4-20), impurity level in the mother liquors, and absolute temperature are easily determined. 

For other methods, see Section 9.2 on in-line crystallization (mean particle size < 10 microns) and Section 4.3.2 for a discussion of semicontinuous fluidized bed growth rate measurement apparatus. 

Cell Growth Experiments For the growth rate measurement, overnight cultures were diluted to the initial ODgoo of 0.1. Three replicates of each strain were performed. Initial cell growth (ODgoo, <2) was used for calculation of the specific growth rate. 

Table 3.4. Spherulite growth rate measurements in miscible polymer blends (G versus T).

Figure 1- is known (6 =35"). The growth rate measurements of these polymorphs were carried out first in pure solutions(without L-Hien) and secondly in solutions containing L-Phen at various concentrations. 

Table 8.1 shows the dependence of K and n on the mechanism of nucleation and growth. Measurements of n have shown that it decreases as crystallization proceeds. Mandelkem [28)] has considered the case of sporadic nucleation on predetermined nuclei that cause a decrease in as crystallization proceeds. However, n may also decrease when A cs is not constant but varies with time. A comparison of degree of crystallinity measurements with spherulitic growth rate measurements on the same polymer [29] shows this. The polymer continues to crystallize after the volume fills with spherulites. The value of n for this secondary crystallization is usually less than for the primary crystallization process. This difference gives rise to a change of n with time. Reference 30 treats this problem theoretically as do Hilliar [31] and Price [32]. 

Overall growth rates for potash alum measured in the fluidized bed crystallizer coincide very well with those predicted from face growth rates measured in the single crystal cell Figure 6.22). The alums grow as almost perfect octa-hedra, i.e. eight (111) faces, so it is a simple matter, using the crystal density, pc, to convert linear face velocities to overall mass deposition rates Rq = pcV u ))-... 

Desupersaturation methods for crystal growth rate measurements have been reported for ammonium alum (Bujac and Mullin, 1969), potassium sulphate (Jones and Mullin, 1973a), nickel ammonium sulphate (Ang and Mullin, 1979), potassium chloride (Nyvlt, 1989) and succinic acid (Qui and Rasmuson, 1990). 

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