PMC:2812708 / 12886-14360 JSONTXT

{"project":"MyTest","denotations":[{"id":"19242689-15080720-28778240","span":{"begin":741,"end":745},"obj":"15080720"}],"namespaces":[{"prefix":"_base","uri":"https://www.uniprot.org/uniprot/testbase"},{"prefix":"UniProtKB","uri":"https://www.uniprot.org/uniprot/"},{"prefix":"uniprot","uri":"https://www.uniprot.org/uniprotkb/"}],"text":"We now discuss the optical properties that result from the specific colloidal microstructures as discussed above. Due to different preparation conditions, the morphology of the β-carotene core changes. H- and J-aggregates have different UV/vis spectra, shown as visual impression on the right side of Fig. 2. Figure 1 dot line curve shows the UV/vis spectrum of 0.05 g/l product without any ultracentrifugation. Four peaks at 288, 449, 478 and 518 nm can be seen. The three peaks in the visible can be attributed to the 1Ag− (S0)–1Bu+ (S2) transition with the vibrational progression 2–0, 1–0, 0–0 of the C–C stretch vibration along the alternatingly double bonded electronically conjugated backbone of the carotenoid (Polivka and Sundstrom 2004).The UV peak partially can be attributed also to the carotenoid transition 1Ag−–1Ag+, which is forbidden by symmetry, but becomes allowed in the crystalline assembly. The spectrum of the composite particle indicates the β-carotene J-aggregate (Auweter et al. 1999). Figure 1 solid curve shows the pure gelatin spectrum for 1 g/l. It can be seen that gelatin only contributes to the UV region of the spectra below 280 nm. However, the contribution of gelatin is vanishing compared to the three times stronger absorption of the composite sample at 20 times lower overall concentration. Another component that presumably contributes to the UV absorption is the ascorbylpalmitat dispersant that is added during the co-precipitation."}

{"project":"2_test","denotations":[{"id":"19242689-15080720-28778240","span":{"begin":741,"end":745},"obj":"15080720"}],"text":"We now discuss the optical properties that result from the specific colloidal microstructures as discussed above. Due to different preparation conditions, the morphology of the β-carotene core changes. H- and J-aggregates have different UV/vis spectra, shown as visual impression on the right side of Fig. 2. Figure 1 dot line curve shows the UV/vis spectrum of 0.05 g/l product without any ultracentrifugation. Four peaks at 288, 449, 478 and 518 nm can be seen. The three peaks in the visible can be attributed to the 1Ag− (S0)–1Bu+ (S2) transition with the vibrational progression 2–0, 1–0, 0–0 of the C–C stretch vibration along the alternatingly double bonded electronically conjugated backbone of the carotenoid (Polivka and Sundstrom 2004).The UV peak partially can be attributed also to the carotenoid transition 1Ag−–1Ag+, which is forbidden by symmetry, but becomes allowed in the crystalline assembly. The spectrum of the composite particle indicates the β-carotene J-aggregate (Auweter et al. 1999). Figure 1 solid curve shows the pure gelatin spectrum for 1 g/l. It can be seen that gelatin only contributes to the UV region of the spectra below 280 nm. However, the contribution of gelatin is vanishing compared to the three times stronger absorption of the composite sample at 20 times lower overall concentration. Another component that presumably contributes to the UV absorption is the ascorbylpalmitat dispersant that is added during the co-precipitation."}