Purpose. Flavonoids have been used as antioxidant, chemopreventive and chemosensitizing agents. In this study, eleven flavonoids containing a variety of hydroxy (OH) and/or methoxy (OMe) groups were evaluated for their antioxidant, cytotoxic and chemosensitizing effects to create a structure-activity relationship (SAR). Methods. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical solution-based chemical assay and and 2',7'-dichlorofluorescin diacetate (DCFH-DA) cellular-based assay were used to compare the free radical scavenging activity on the same molar concentration basis using the AML-2/DX100 cells which are characterized by the down-regulated expression of catalase and resulting supersensitiviy to hydrogen peroxide. The chemosensitization and cytotoxicity were determined by the MTT assay in the presence or absence of an anticancer drug using the P-glycoprotein-overexpressing AML-2 subline AML-2/D100 cells. Results. The antioxidant activity of the flavonoid (3,5,7,3’,4’-OH) was higher than that of the flavonoid (5,7,3’,4’-OH). Flavonoids substituted with the various number of OMe decreased antioxidant activity. Flavonoids with 7-OH or 5,7-OH groups have the highest cytotoxicity, and flavonoids with 5,7-OMe group intermediate cytotoxicity. The IC50 values of flavonoid (5,7-OMe, 3’,4’,5’-OMe) and flavonoid (5,7-OMe, 4’-OMe), 0.4 M and 1.4 M. The IC50 values of flavonoid (5,6,7-OMe, 3’,4’-OMe) and flavonoid (5,6,7-OMe, 3’,4’,5’-OMe), 3.2 uM and 0.9 M, respectively, and those of flavonoid (5,6,7-OMe, 3’,4’,5’-OMe) and flavonoid (5,7-OMe,3’,4’,5’-OMe) were 0.9 M and 0.4 M, respectively. Conclusions. These results suggest that flavonoids with 3-OH group play a positive role in antioxidant activities, flavonoids with 5-OH and/or 7-OH groups show the higher cytotoxicity, and flavonoids with 3’-OMe and/or 5’-OMe groups plays positive but 6-OMe groups negative roles in the P-glycoprotein (Pgp) inhibition. It is believed that these SAR results can be taken into account for the development of flavonoids with high therapeutic index.

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A field study was conducted to examine if time of adoption (i.e., purchase innovativeness) was systematically related with use innovativeness, product involvement, and extent of product usage. The results showed that early adopters had significantly higher use innovativeness and product involvement as compared to the early majority. Although usage variety was higher for early adopters, no significant differences were found in usage frequency between the two groups. Use innovativeness and involvement mediated the relationship between purchase innovativeness and usage variety. © 1994 John Wiley & Sons, Inc.

In this study, highly luminescent carbon dots with diameters of 3–5 nm were synthesized via the carbonization of citric acid, and the effects of surface passivation and carbonization temperature on the optical properties were investigated.

The microstructure and electrical resistivity of inkjet-printed silver (Ag) films annealed under ambient air were characterized. Analyses of the impurity amounts in the films using secondary-ion mass spectrometry showed that the decomposition temperature of the capping molecules was just below 170 C. Both the characteristics of the microstructure and electrical resistivity when annealed at low temperatures (lower than the decomposition temperature) were significantly different from those when annealed at high temperatures. The results show that neither microstructural features, such as grain size, nor the amounts of impurities can explain both the magnitude and characteristic decrease in electrical resistivity. The changes in electrical resistivity can be described using exponential decay kinetics. The corresponding activation energy of 0.44 eV when annealed at the high temperatures is explained by the migration of point defects such as vacancy-oxygen pairs. On the other hand, negligible dependence on temperature was identified when annealed at low temperatures, which was attributed to decomposition of the capping molecules. The results indicate the importance of controlling the defects of nanoparticles and the properties of capping molecules from the viewpoint of electrical optimization of metallization fabricated using inkjet printing.

Most tools, utensils, office equipment, home appliances, clothes, medical instruments, sporting goods, weapons and public facilities are made for people who are right-handed. Many left-handed people have to endure a certain amount of inconvenience or difficulty in carrying out daily activities in such an environment. In this study, 2437 Korean male and female participants were randomly selected to collect a variety of data on hand dominance and hand preference when handling diverse products and facilities. Their responses in a questionnaire survey revealed that 5.8% were left-handed and 7.9% were ambidextrous. The younger participants who were from teens to 39 years reported higher percentages of left-handedness than those over 40 years, with those in their thirties reporting the highest proportion of left-handedness (7.3-7.6%) for both men and women. A slightly higher percentage of the male participants (5.9%) said that they were left-handed than did the female participants (5.6%). However, the percentage who were ambidextrous varied with age group, but overall there was a higher percentage of women (8.3%) than of men (7.6%). The analysis of hand use behaviour revealed that the right-handed and ambidextrous people had a tendency to use their right hands more for actions that required accuracy than those that required force. The left-handed people had a strong tendency to use their left hands more often when making a forceful action than for one that required accuracy. Derived from these results, the conclusion is that, depending on their hand dominance, people seem to use their hands differently when they handle objects or use facilities, which should be considered in the design of hand-controlled devices. Depending on which hand is the dominant one, people seem to use their hands differently when they handle objects or use facilities. The left-handed tend to use their left hands more with force-required motions than with accuracy-required motions, while ambidextrous and right-handed people use their right hands more with accuracy-required motions than with force-required motions. Designers of products and facilities will find the results of this study useful for developing hand-controlled devices and systems.