Annealing Under Controlled Conditions

Phase separation in block copolymer films has been shown to be sensitive to the solvent selectivity and its concentration in the film [49, 51, 114, 120, 123]. We emphasize the importance of a well-controlled atmosphere of solvent vapor for the annealing process since even slight changes in the solvent concentration or in the temperature of the system may induce structural phase transitions. 

One of the easy and effective approaches for quantifying the polymer volume fraction within films in situ is to use in situ spectroscopic ellipsometry (SE) [49,118, 119, 144], The measurements should be performed in a thermostated cell (Fig. 7) with full control over the solvent vapor atmosphere p/po, where po is the solvent vapor pressure at saturation and p is the actual pressure, which can be adjusted by a combination of the saturated vapor flow and dry nitrogen flow [118, 119], or by the difference between the temperature 7j of the polymer sample and the temperature 72 of the solvent vapor [49, 114, 144], 

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A crucial aspect of virtually all DNA-DNA hybridization studies is that they involve only so-called single-copy DNA (scDNA) or "unique DNA. Total genomic DNA is made single-stranded by heating and then allowed to reassociate into duplex DNA after cooling. Repeated copies of DNA sequences re-anneal faster than single-copy sequences due to their higher concentration in the solution. Thus, under controlled conditions and time, it is possible to remove excess copies of repeated sequences. 

The technique generally used to minimize the degree of change in crystallinity of the milled product is to eliminate the water or other solvents from the product, usually by packaging the material within a suitable barrier (for example, aluminum foil laminate). Other techniques include the production of a 100% crystalline material, which may eliminate the effects of moisture. This technique, however, may require a secondary production stage of annealing or a quarantine period to allow the product to equilibrate under controlled storage conditions. 

In summary, wc conclude tluu particle shape control in supported metal catalysis is feasible. When a supported platinum catalyst is annealed under conditions where the platinum particles stay dean, the platinum particles assume a spherical shape with flat facets in the (100) and (111) directions. All of the particles in the catalyst assume the same general shape. In contrast, different shapes are observed when the catalyst is annealed in various udgasscs. Shi[ll] showed theoretically that only a few planes can be produced by eciuilibratiug the particles in simple adsorbates. However, w e speculate that one may be able to produce a wide distribution of panicle siiapes. with appropriate adsorbates,... 

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