A series of donor-acceptor low-bandgap conjugated polymers, that is, HThmBT (m ¼ 3,6,9,12,15), composed of regioregular 3-hexylthiophene segments and 2,1,3-benzothiadiazole units, were synthesized through the Stille coupling polymerization to optimize the p-conjugation length of the polymer and the intramolecular charge transfer (ICT) effect in the polymer backbone. The polymers had relatively low optical bandgaps ranging from 1.6 to 1.72 eV. Among these polymers, HTh6BT exhibited the best device performance with a power conversion efficiency (PCE) of 1.6%. Moreover, despite being based on thiophene, HTh6BT exhibited a high-open circuit voltage (V OC ) of over 0.8 V because of its low high occupied molecular orbital (HOMO) energy level. These results provided an effective strategy for designing and synthesizing low-bandgap conjugated polymers with broad absorption ranges and wellbalanced energy levels. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: [4875][4876][4877][4878][4879][4880][4881][4882][4883] 2010
The purpose of this study was to investigate the antioxidant and skin whitening effects of Artemisia iwayomogi extract. Artemisia iwayomogi was extracted with 100% ethanol and water. The antioxidative and skin whitening effects of these extracts were determined with in vitro assays by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) method assessing the inhibitory effects on tyrosinase activity and melanogenesis in B16 melanoma cells. Radical scavenging activity of the extracts was tested by DPPH assay which showed a high DPPH radical scavenging activity (SC 50 ; 17.1 ppm in EtOH, 198.4 ppm in water). In term of tyrosinase inhibitory activity, Artemisia iwayomogi ethanol extract showed high inhibition activity (IC 50 : 481.8 ppm). In B16 mouse melanoma cells, the ethanol extract significantly inhibited melanin synthesis by 36.8% at a concentration of 50 ppm. These results suggest that Artemisia iwayomogi ethanol extract has significant antioxidant activity and whitening activity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.