Enhancement in Photovoltaic Performance of Solar Cells by Electrostatic Adsorption of Dyes on ZnO Nanorods.

ZnO nanorods were formed by chemical bath deposition on fluorine-doped tin oxide (FTO) glass and the photovoltaic performance of ZnO-based dye-sensitized solar cells (DSCs) was investigated. A DSC with 8 h-grown ZnO nanorods showed a higher power conversion efficiency (PCE) than devices with 4, 6, and 10 h-grown ones. Further improvement in PCE was achieved in a cell with a silver-ion-deposited ZnO/FTO electrode. By deposition of Ag+ on the surface of the 8 h-grown ZnO nanorods, the dye-loading amount increased by approximately 210%, compared to that of pristine ZnO nanorods, resulting in a 1.8-times higher PCE. A DSC with the pristine ZnO/FTO electrode showed a PCE of 0.629%, while in a device with the silver-ion-deposited ZnO/FTO, the PCE increased to 1.138%. In addition, interfacial resistance at the ZnO/dye/electrolyte was reduced to approximately 170 Ω from 460 Ω for the control cell with the pristine ZnO/FTO. We attributed the higher dye-loading amount in the silver-ion-deposited ZnO/FTO to the electrostatic attraction between the positively charged ZnO and carboxylate anions (-COO-) of the N719 dyes.

Photovoltaic Performance of Dye-Sensitized Solar Cells Containing ZnO Microrods.

At an elevated temperature of 90 °C, a chemical bath deposition using an aqueous solution of Zn(NO3)2·6H2O and (CH2)6N4 resulted in the formation of both nanoflowers and microrods of ZnO on F-doped SnO2 glass with a seed layer. The nanoflowers and microrods were sensitized with dyes for application to the photoelectrodes of dye-sensitized solar cells (DSSCs). By extending the growth time of ZnO, the formation of nanoflowers was reduced and the formation of microrods favored. As the growth time was increased from 4 to 6 and then to 8 h, the open circuit voltage (Voc) values of the DSSCs were increased, whilst the short circuit current (Jsc) values varied only slightly. Changes in the dye-loading amount, dark current, and electrochemical impedance were monitored and they revealed that the increase in Voc was found to be due to a retardation of the charge recombination between photoinjected electrons and I3- ions and resulted from a reduction in the surface area of ZnO microrods. A reduced surface area decreased the dye contents adsorbed on the ZnO microrods, and thereby decreased the light harvesting efficiency (LHE). An increase in the electron collection efficiency attributed to the suppressed charge recombination counteracted the decreased LHE, resulting in comparable Jsc values regardless of the growth time.

Application and Developmental Strategies for Community-Based Injury Prevention Programs of the International Safe Communities Movement in Korea.

PURPOSE: Safety of humans is an important factor that affects health overall, and injuries are one of the major public-health problems in the world. The purposes of this study were to describe the International safe Community movement which contributes to the injury prevention and safety promotion all over the world, and to identify out the application and developmental strategies for Korea. METHODS: A review was done of previous research, reviews, and reports on the history, concepts, basic principles, and recommendations for actions of the Safe Community. RESULTS: For this study, the application strategies of the International Safe Community movement in Korea were examined to deduce the strengths of the safe Community program. Community-based injury prevention work according to the International Safe Community model is a successful and cost-effective way of reducing injuries in the community. CONCLUSION: Through the International Safe Community program, communities are able to realize a healthy community and achieve improved quality of lives for the people, which is the ultimate objective of the Safe Community model. In addition, it will contribute to the economic vitalization and gain through energy and enhancement of productivity of people.

Effects of a Fall Prevention Exercise Program on Muscle Strength and Balance of the Old-old Elderly.

[Purpose] The purpose of this study was to investigate the effects of an 8-week balance exercise and elastic-resistance exercise program on muscle strength and balance of the old-old elderly (over the age of 75). [Subjects and Methods] Fifty-five elderly persons were recruited from the community and assigned to three groups for convenience: balance exercise (intervention group 1; INT 1), resistance exercise (intervention group 2; INT 2), and control (CON) groups. The intervention was performed twice a week at a senior center and three times a week at home for 8 weeks. Muscle strength and balance were evaluated before and at the end of the trial, using a PowertrackIIand Tetrax. [Results] There were significant improvements in the strength of all seven muscle groups and balance in the INT 2 group. In the INT 1 group, there were significant improvements in the strength of all muscle groups except for the knee flexor and ankle plantar flexor muscle groups. [Conclusion] This study demonstrated that an intervention using balance exercises or elastic-resistance exercises is effective at improving the muscle strength and balance of the old-old elderly. These type of exercises should be appropriate for the physical characteristics of the subjects.

Effects of Recreational Exercises on the Strength, Flexibility, and Balance of Old-old Elderly Individuals.

[Purpose] The purposes of this study were to investigate the effects of recreational exercises on the muscle strength, flexibility, and balance of old-old elderly individuals over the age of 75 years. [Subjects and Methods] Forty-three old-old elderly subjects (aged 78.7 ± 2.9 years) participated in 8 weeks of recreational exercises. The exercises were performed twice a week for 8 weeks. Muscle strength, flexibility, and balance were evaluated by the Senior Fitness Test before and at the end of the intervention. [Results] Significant improvements in muscle strength, flexibility, and balance were observed at the end of the intervention. [Conclusion] This study demonstrated that an intervention using recreational exercises effectively improves the muscle strength, flexibility, and balance of old-old elderly individuals.

[Effects of community-based comprehensive fall prevention program on muscle strength, postural balance and fall efficacy in elderly people].

PURPOSE: The purposes of this study was to develop a comprehensive community-based fall prevention program and to test the effects of the program on the muscle strength, postural balance and fall efficacy for elderly people. METHODS: The design of this study was a nonequivalent control group pretest-posttest design. There were 28 participants in the experimental group and 29 in the control group. The program consisted of balance exercises, elastic resistance exercises and prevention education. The program was provided five times a week for 8 weeks and each session lasted 90 minutes. Data were analyzed using χ²-test, independent t-test and paired t-test using the SPSS program. RESULTS: Muscle strength of the lower extremities, postural balance and fall efficacy scores significantly improved in the experimental group compared to the control group. CONCLUSION: These results suggest that this program can improve lower extremity muscle strength, postural balance and fall efficacy in elders. Therefore, this program is recommended for use in fall prevention programs for elders living in the community.