Coated particles synthesis

Figure 5 A schematic illustration of a multistep continuous-flow synthesis system for making ZnS-coated CdSe composite particles. Luminescence spectra of uncoated CdSe from CdSe portion and coated particles from the outlet at different flow rates. Labels denote the flow volume of the two syringes for the CdSe and ZnS raw feedstock. Uncoated CdSe nanoparticles were obtained using a flow rate of 100 pi min 1 images reproduced, with permission, from Wang et al, 2004).

Segmented gas-liquid (Taylor) flow was used for particle synthesis within the liquid slugs. Tetraethylorthosilicate in ethanol was hydrolyzed by a solution of ammonia, water and ethanol (Stober synthesis) [329]. The resulting silicic acid monomer Si (OH)4 is then converted by polycondensation to colloidal monodisperse silica nanoparticles. These particles have industrial application, for example, in pigments, catalysts, sensors, health care, antireflective coatings and chromatography. 

Hirayama, K. Borow, M. Morikawa, Y. Minoura, N. Synthesis of polymer-coated particles with specific recognition sites for glucose oxidase by the molecular imprinting technique. Chem. Lett. 1998, 731-732. 

Sherif and Shyu [163] used three different routes for particle synthesis (Section 4.3) all-alkoxides, salt/alkoxide and all-salts. Plasma sprayed coatings on steel coupons exhibited somewhat similar properties, though the best results were obtained with powders from the all-salts route. Table 6.1 presents a comparison of some of the coating properties with those obtained from a commercial powder prepared under the same set of conditions. 

A report in the same line [380] involves suspension of ZnS.Mn nanoparticles in microemulsions, with the surface modified by polyoxyethylene(l)laurylether phosphoric acid or polyoxyethylene(4.5)laurylether acetic acid. The coated particles exhibited several times higher photoluminescence intensity and quantum efficiency compared to the uncoated ones. The phosphate group P = O or the carboxyl group C = O, with their luminescent centers, were functional in this improvement, thus opening new routes for imparting superior optical properties on microemulsion-synthesized particles. Gan etaL [376] used four routes for the synthesis of ZnS Mn (i) the relatively new route that involved hydrothermal... 

The methods described earlia- for the synthesis of mondisperse powders and coated particles have not made significant inroads into industrial production he-... 

FIGURE 1.25 The virus life cycle. Viruses are mobile bits of genetic iuformatiou encapsulated in a protein coat. The genetic material can be either DNA or RNA. Once this genetic material gains entry to its host cell, it takes over the host machinery for macromolecular synthesis and subverts it to the synthesis of viral-specific nucleic acids and proteins. These virus components are then assembled into mature virus particles that are released from the cell. Often, this parasitic cycle of virus infection leads to cell death and disease. 

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