Competitive growth

When used in tumor cells, fulvestrant was initially described as a potent, competitive growth inhibitor of ER-positive, human breast cancer MCF-7 cells, whose growth is stimulated by estradiol. The compound was ineffective in tumor cell lines without ER, such as MDA-MB-231. The inhibitory effects were more pronounced with fulvestrant than with tamoxifen in the same cell line (Wakeling et al. 1991). 

An antibiotic inhibition zone often appears around Trichoderma spp. interacting with other fungi. The genus contains many species which produce secondary metabolites. Claydon et al. (23) have identified an antibiotic from T. harzianum as a volatile, 6-n-pentyl-2H-pyran-2-one this was recently shown to be an active antibiotic from T. koningii (24). The volatile appeared to be the factor responsible for the coconut smell of some biocontrol-effective strains of T. harzianum (25). However, in a Petri-plate assay, it can be difficult to be certain that antibiosis is involved. As well as competitive growth, lytic enzymes could also contribute to the action and Trichoderma has been shown to produce / -l,3-glucanase and chitinase (26-29). 

Effect of pasteurizing irradiation on the competitive growth (repression) activities of the natural microflora of sea foods. 

Thus, Eqs.(16) and (23) seem to give almost the same accuracy in calculating Ap, considering that competitive growth rate of polymer particles with different size is not necessarily well understood (12). ... 

If we examine the competitive growth of multiple-size crystallites in solutions, we find the growth occurring along concentration gradients. The concentration gradients around the particles are explained with the Gibbs-Thomson equation ... 

Two major entry models - the diffusion-controlled and propagation-controlled models - are widely used at present. However, Liotta et al. [28] claim that the collision entry is more probable. They developed a dynamic competitive growth model to understand the particle growth process and used it to simulate the growth of two monodisperse polystyrene populations (bidisperse system) at 50 °C. Validation of the model with on-line density and on-line particle diameter measurements demonstrated that radical entry into polymer particles is more likely to occur by a collision mechanism than by either a propagation or diffusion mechanism. 

From mixed surfactant systems of emulsion polymerization, monodispersed latices were usually obtained at fairly low conversions with rather wide variations in emulsifier compositions (j ). Therefore, samples for the determination of the particle size distribution in this system should be taken at relatively low conversions, otherwise, monodispersed latices will be obtained due to competitive growth from all samples regardless of the surfactant ratios in the recipe of polymerization. These particles will be different in size, but not in size distribution. 

One of the tests described for the relative stability of polymorphs (Sections 3.5.1 and 4.12) involves the observation of competitive growth rates in a particular solvent (Fig. 1.4). Such experiments may be easily followed and recorded on the microscope (at different temperatures) as demonstrated in Fig. 3.5. 

Emulsion polymerization of styrene using the competitive growth technique (lOy 37—39)... 

Broughton, P.L. (1983) Environmental implications of competitive growth fabrics in stalactitic carbonate. International Journal of Speleology 13, 31-41. 

Breidt, F., Jr. and Fleming, H.P 1998. Modeling of the competitive growth of Listeria monocytogenes and Lcatococcus lactis in vegetable broth. Applied and Environmental Microbiology 64 3159-3165. 

Low redox potential Nutrient depletion Crowding pH reduction of surrounding medium (pH 3.5-4.5) Growth decreases carbohydrate food content Competitive growth inhibits spoilage or pathogenic organisms... 

This is the difference between a living polymerization system (chains grow until the reaction is terminated) and a nonliving system (continuous and competitive growth and termination). Phillips catalysts are nonliving systems, and in the above example an active Cr site produces about 20,000 chains during its 1-h lifetime. 

Cloud point 52, 53 Coagulum 47, 53 Coating, graft copolymers 32 Competitive growth experiment 49 Crq)oly(styrene-dimethylacrylamide) 19 Cumyloxy free radicals 71 Cyanoisopixqtyl free mono-madicals 88, 94-96... 

F-Erythritol (a competitive growth inhibitor of the Bipuoella group) was a crystalline compound, isomorphous with erythritol itself, whose structure had to be established by X-ray diffraction analysis. 2F-Ribitol likewise was obtained by a similar synthetic route. 

In practice, the latexes resulting from emulsion polymerization most often contain particles within a wide size range. In fact, a broad particle size distribution (PSD) with a substantial amount of large size particles (dp > 1000 nm) is often required for low-viscosity plastisols. The relative growth of each particle size is determined by principles of competitive growth. Due to the complexi of a syston with a broad PSD, most woik dealing with this problem has been carried out with a bimodal system of two well-defined particle sizes. 

Problems caused by polymorphism appear in many fields such as fine chemicals in industries (pharmaceuticals(7,2), foods, etc.), optical electronic materials(i), clathrate compounds(4) and biominerals(5). In crystallizations of these materials the crystallization behavior of the polymorphs is controlled first by basic operational conditions such as temperature, supersaturation degree, stirring rates. In addition to these basic factors, solvents, additives and guest molecules (in clathrate compounds) should be also considered as the important factors((5,7). The crystallization process of the polymorphs is composed of comp)etitive nucleation, competitive growth of polymorphs and transformation from metastable to stable form. Accordingly individual step should be investigated to clarify the crystallization mechanism of polymorphs. 

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