Polymacromonomers consisting of oligostyrene side chains (700 ≤ M n ≤ 5000 g/mol) and of a high molar mass polymethacrylate main chain are shown to exhibit a bottlebrush structure in that the PMA main chain adopts an extremely stiff conformation (i.e., a Kuhn statistical segment length of up to l k = 2000 Å) which is surrounded by the expanded but still flexible polystyrene side chains.

Ca-alginate gels were studied by small-angle X-ray scattering and rheology to determine relations between chemical composition and concentrations of the alginate and the elasticity and structure of the gels. The gels were prepared by in situ release of Ca 2+ from either Ca-EGTA or CaCO3 with total Ca 2+ concentration in the range 5-30 mM. Alginates with low (39%), intermediate (50%), and high (68%) fractions of R-L-GulA originating from the brown algae Ascophyllum nodosum, Laminaria hyperborea leaf, and Laminaria hyperborea stipe, respectively, were employed. Two to three different degrees of polymerization for each chemical composition were used in the experiments. The excess small-angle X-ray scattering for the alginates in solution yielded linear cross-sectional Guinier plots, and the cross-sectional radius of gyration, R g,c, was determined to be 3.1-4.6 Å. The SAXS profiles of the alginate gels depended on the alginate concentration, Ca 2+ concentration, and the alginate composition. The SAXS data suggested that dimerization of chain segments was the principal association mode at low fractional Ca 2+ saturation of guluronic acid of the alginate. Increasing the fractional Ca 2+ saturation of guluronic acid, either by the concentrations or selection of alginate source, yielded coexisting lateral association modes, as manifested in a curvature in the cross-sectional plots. The coexisting junction zone multiplicities occur because of a delicate balance between the block length distribution of the R-L-GulA residues, polymer concentration, and Ca 2+ . These results are quantitative extensions of the "egg-box" model used to describe ionotropic gelation of alginate and hence enhance the understanding of the structure-function relationship of alginate gels.

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This study investigates the relationship between color perceptual attributes and color emotions, as well as the influence of different cultural backgrounds. Totally 214 color samples were evaluated on 12 emotion variables by subjects from seven different region groups in the psychophysical experiment. By factor analysis, it was found that three factors were sufficient to represent 80 11 "region-emotion" variables. For each variable, there is no distinct difference among different region groups. The 12 emotion variables could be divided into four categories, namely, activity index, potency index, definition index, and temperature index. Factor scores were further calculated to study the determinants on each factor. The analysis showed that the three factors were mainly related to chroma, lightness, and hue, respectively. It was concluded that chroma and lightness were the most important factors on color emotion, whereas the influences of hue and cultural background were very limited. (c) 2007 Wiley Periodicals, Inc