Nanometer-sized clusters, production

Two crucial factors required for the successful development of these applications are the need to synthesize the appropriate nanoduster molecules in such a manner as to have zero size distribution and to be able to structurally characterize the products obtained. The numerous practical applications of binary late-metal chalco-genide semiconductors [1] have spurred the development of chemical methods to access nanometer-sized pieces of these solid materials, where single crystal diffraction can be used to eluddate the three-dimensional structure of the clusters obtained. 

Most food products and food preparations are colloids. They are typically multicomponent and multiphase systems consisting of colloidal species of different kinds, shapes, and sizes and different phases. Ice cream, for example, is a combination of emulsions, foams, particles, and gels since it consists of a frozen aqueous phase containing fat droplets, ice crystals, and very small air pockets (microvoids). Salad dressing, special sauce, and the like are complicated emulsions and may contain small surfactant clusters known as micelles (Chapter 8). The dimensions of the particles in these entities usually cover a rather broad spectrum, ranging from nanometers (typical micellar units) to micrometers (emulsion droplets) or millimeters (foams). Food products may also contain macromolecules (such as proteins) and gels formed from other food particles aggregated by adsorbed protein molecules. The texture (how a food feels to touch or in the mouth) depends on the structure of the food. 

It seems that one of the future developments in cluster chemistry lies in the production of nanosized particles (1 nm = 10 A) with well defined stoichiometries, which can be used as catalysts or as catalyst precursors. In this context, high nuclearity mixed-metal clusters are particularly useful because two or more metal atoms with different chemical properties can be combined in the same unit. The Cambridge group has spent the last few years designing rational synthetic routes to mixed-metal high nuclearity clusters of ruthenium and osmium with the coinage elements, which produce cluster cores of up to one nanometer in size. ... 

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