Gradient-carrier

FIGURE 12.14 Elution profiles obtained at various thermal gradients carrier KNO3 3 mM aqueous solution pH 9, flow rate 0.304mL min" , Si particle diameter=300nm. 

Ability to transport substances against a concentration gradient. Carrier-mediated active transport may be able to carry substances uphill —that is, from areas of low concentration to areas of high concentration. 

The gradient formation occurs by interaction of gradient-former (e.g. diffuser with refraction index ni) with the gradient-carrier. The function the gradient-carrier carries out is to modify the gel-polymer matrix with the refraction index This substance must generate the optical transparent copolymer with the other monomer which has a different refractive... 

Based on the above mentioned eoncepts it may be concluded that, by using of this method, formation of the given distribution of refractive index is due to the dmation of the gradient forming process at the surface of the gradient-carrier component [12, 73, 74],... 

Chemical modification of the gradient carrier by polymer-analogous transformation/two-stage copolymerization is performed by its interaction with the gradient former, the chemically active medium/monomer-drffusant, which may be an individual liquid substance or liquid solution of a gas, liquid or solid. In some cases, the gradient former may exist in the... 

Hence, in the method of controlled gradient formation, formation of the given distribution of the refractive index is produced by gradient of the process duration on the surface of the gradient carrier. That is why, accurate regulation of this parameter in the given directions on the sample surface represents an important technical requirement in the method discussed. 

To set the required duration of the process (polymer-analogous transformation/ diffusion copolymerization) in given directions on the surface of the gradient carrier a device is used that allows use of a diaphragm mask in the contact zone of the gradient former with the gradient earrier. Several teehnical solutions of application of such devices have been... 

In some cases, especially at the application of gel-polymeric matrix as the gradient carrier, tight fixing of the latter in the rotating reactor must be provided. For this purpose, the gel-polymeric sample (23) (Figure 14, b) is placed in a circle framework (26) which, in turn, is fixed to immovable details (22, 24,25, 27) in the reactor (4). 

This transformation can be performed by alcoholysis of PVA films by sodium hydroxide solution in ethanol with [NaOH] = 10 wt% at 60°C. Hence, in the present process, PVA is the gradient carrier, and sodium hydroxide solution is the gradient former ... 

Experiments are performed in order to study function n = f(r) - determination of influence of PVA PVAl transformation duration on variation of the refractive index of the gradient-carrier. These data are shown in Figure 17 indicating that maximal growth of the refractive index in the gradient-carrier, reached after 4 hours, is A = 0.025. 

Figure 17. Dependence of the refractive index of the gradient-carrier (n) on duration (x) of polymer-analogous PVA - PVAl transformation...

Figure 18. Given dependence of the refiactive index (n) on radius (R) of the gradient-carrier at PVA —> PVAl transformation a and b are products with properties of biconcave and biconvex lenses, respectively.

In the above-considered examples, the refractive index of the gradient-carrier was lower than that of the product of polymer-analogous transformation. It is clear that with the reverse relation of refractive indices, as for example, with PVA (n = 1.53) Poly(binylbutyrale) (n = 1.485) transformation ... 

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