Generation number

Table 10.1 shows the seleetion of parents for mating from the initial population. If a random number generator is used to generate numbers between 0.0 and 1.0, then the eumulative probability values in Table 10.1 is used as follows ... 

AFM has also been used to study adsorbed dendrimers of increasing generation number. When this is done, it is found that there is a steady and regular rise in the diameters of the adsorbed dendrimers with each additional generation number, but that each generation of dendrimers remains highly homogeneous. 

PAMAM dendrimers are synthesized in a multistep process. Starting from a multifunctional amine (for example ammonia, ethylenediamine, or tris(2-amino-ethyl)amine) repeated Michael addition of methylacrylate and reaction of the product with ethylenediamine leads to dendrimers of different generation numbers [1,9]. Two methylacrylate monomers are added to each bifunctional ethylenediamine generating a branch at each cycle. Unreacted ethylenediamine has to be completely removed at each step to prevent the initiation of additional dendrimers of lower generation number. Excess methylacrylate has also to be removed. Bridging between two branches of the same or of two different dendrimers by ethylenediamine can also be a problem, and has to be avoided by choosing appropriate reaction conditions. 

The generation number, activation procedure, and core moiety of PolyFect Transfection Reagent have been developed specifically for transfection of certain cell lines, including HeLa and COS-7. Optimized amounts of DNA and den-drimer delivered transfection efficiencies in both cell lines significantly higher than those obtained using a standard transfection method. 

Complexation of gold ions, [Au(I)], with peripheral phosphine groups of a P-based dendrimer was reported by Majoral et al. [185]. Transmission electron microscopy (TEM) was used to analyze the large aggregates formed by the dendritic gold complexes and a direct correlation was observed between the size of the particles and the dendrimer generation number. In a recent report [186], Majoral et al. further demonstrated that up to 48 diphosphino groups could be anchored to the surface of dendrimers and various dendritic metal-complexes... 

Recently, Astruc et al. [189] reported novel amido-ferrocene dendrimers (e.g., 91) which were shown to act as supramolecular redox sensors for the recognition of small inorganic ions (Fig. 41). It was further observed that as the den-drimer generation number increased the sensitivity to the guest molecules also increased as observed by cyclic voltammetry experiments. 

Vogtle et al. have prepared chiral poly(imine) dendrimers of various generations by condensation of non-racemic 5-formyl-4-hydroxy[2.2]paracyclophane moieties with poly(amine) dendrimers [71]. They have found that the optical activity of these dendrimers was nearly constant with increasing generation number. 

The rate of a catalytic reaction depends on the rate of diffusion of both substrates and products to and from the catalytic sites. Therefore it is of outmost importance that the catalytically active sites are freely accessible for reactions. Only dendrimers of low generation number can possibly be expected to be suitable carriers for catalytically active sites, especially when these are located in the interior. In high-generation dendrimers with crowded surfaces catalytic activity of an internal site would be prevented. On the other hand, a crowded surface will not only hinder access to an interior ligand site but will also cause steric hindrance between groups attached to it and thus prevent high reactivity of sites at the periphery. 

The variation with generation number of the average fitness of the population and the fitness of the best string within that population are shown in Figure 5.16. The fairly steady rise in the fitness of the best string and the more erratic improvement of the average fitness are typical of the progress of... 

Variation of the fitness of the best string (upper line) and the average population fitness (lower line) with generation number. 

The effect of elitism on the fitness as a function of generation number. 

Dendritic molecules with a single triethylene amine core surrounded by hyperbranched polyether sectors catalyze the nitro-aldol reaction between aromatic aldehydes and nitroalkanes (Eq. 3.5).15 The activity of the catalysts decreases when the generation number increases. No significant changes in stereo-control are observed on passing from lower- to higher-generation dendrimers. 

Percec, V., Cho, W.D., Mosier, P.E., Ungar, G., and Yeardley, D.J.P. (1998) Structural analysis of cylindrical and spherical supramolecular dendrimers quantifies the concept of monodendron shape control by generation number./. Am. Chem. Soc. 120, 11061-11070. 

D. magna 200 Exposure for six generations. Number of young per female in 21 days did not differ from controls in generations 1, 2, and 3, but significant reduction measured in generations 4, 5, and 6 2... 

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