Background:Traditional vertical and side-alternating whole body vibrations(WBV) can effectively improve muscle power performance but have a limited efficacy for enhancing change-of-direction(COD) ability.Novel dual-pl...Background:Traditional vertical and side-alternating whole body vibrations(WBV) can effectively improve muscle power performance but have a limited efficacy for enhancing change-of-direction(COD) ability.Novel dual-plate WBV uniquely providing various directions of movements with higher and distinctive frequencies for each leg may cause better acute effect on muscle power and stretch-shortening cycle efficacy contributing to COD ability.Therefore,the purpose of this study was to investigate the acute effect of dual-or single-frequency WBV on squat jumps(SJs),countermovement jumps(CMJs),eccentric utilization ratios(EURs),and COD ability in rugby players.Methods:Fourteen male rugby players were recruited and performed a 4 min partial squat with 3 types of WBV protocols on a dual-plate WBV machine,including 1 dual-frequency WBV protocol(DFW) with the dominant leg receiving 35 Hz and the non-dominant leg receiving 45 Hz,and2 single-frequency WBV protocols(SFWs) with 35 Hz or 45 Hz provided to both legs(SFW35Hz and SFW45Hz) on 3 different days.Results:The results showed that all the vibration protocols significantly improved SJ and CMJ performances(SJ:p = 0.008;CMJ:p < 0.001),but did not significantly change EURs(p > 0.05).In addition,only the DFW significantly improved COD ability(p = 0.001 for the pre–post comparison).Conclusion:A 4 min dual-frequency WBV session improved both vertical jumping and COD ability in rugby players,suggesting that this could be a potential warm-up protocol for athletes.展开更多
Plastic thermo-electrochemical ceils （thermocells） involving aqueous potassium ferricyanide/ferrocyanide electrolyte have been investigated as an alternative to conventional thermoelectrics for thermal energy harves...Plastic thermo-electrochemical ceils （thermocells） involving aqueous potassium ferricyanide/ferrocyanide electrolyte have been investigated as an alternative to conventional thermoelectrics for thermal energy harvesting. Plastic thermocells that consist of all pliable materials such as polyethylene terephthalate （PET）, fabrics, and wires are flexible enough to be wearable on the human body and to be wrapped around cylindrical shapes. The performance of the thermocells is enhanced by incorporating carbon nanotubes into activated carbon textiles, due to improved charge transfer at the interface. In cold weather conditions （a surrounding temperature of 5 ℃）, the thermocell generates a short-circuit current density of 0.39 A/m2 and maximum power density of 0.46 mW/m2 from body heat （temperature of 36℃）. For practical use, we have shown that the thermocell charges up a capacitor when worn on a T-shirt by a person. We also have demonstrated that the electrical energy generated from waste pipe heat using a serial array of the thermocells and voltage converters can power a typical commercial light emitting diode （LED）.展开更多
文摘Background:Traditional vertical and side-alternating whole body vibrations(WBV) can effectively improve muscle power performance but have a limited efficacy for enhancing change-of-direction(COD) ability.Novel dual-plate WBV uniquely providing various directions of movements with higher and distinctive frequencies for each leg may cause better acute effect on muscle power and stretch-shortening cycle efficacy contributing to COD ability.Therefore,the purpose of this study was to investigate the acute effect of dual-or single-frequency WBV on squat jumps(SJs),countermovement jumps(CMJs),eccentric utilization ratios(EURs),and COD ability in rugby players.Methods:Fourteen male rugby players were recruited and performed a 4 min partial squat with 3 types of WBV protocols on a dual-plate WBV machine,including 1 dual-frequency WBV protocol(DFW) with the dominant leg receiving 35 Hz and the non-dominant leg receiving 45 Hz,and2 single-frequency WBV protocols(SFWs) with 35 Hz or 45 Hz provided to both legs(SFW35Hz and SFW45Hz) on 3 different days.Results:The results showed that all the vibration protocols significantly improved SJ and CMJ performances(SJ:p = 0.008;CMJ:p < 0.001),but did not significantly change EURs(p > 0.05).In addition,only the DFW significantly improved COD ability(p = 0.001 for the pre–post comparison).Conclusion:A 4 min dual-frequency WBV session improved both vertical jumping and COD ability in rugby players,suggesting that this could be a potential warm-up protocol for athletes.
文摘Plastic thermo-electrochemical ceils （thermocells） involving aqueous potassium ferricyanide/ferrocyanide electrolyte have been investigated as an alternative to conventional thermoelectrics for thermal energy harvesting. Plastic thermocells that consist of all pliable materials such as polyethylene terephthalate （PET）, fabrics, and wires are flexible enough to be wearable on the human body and to be wrapped around cylindrical shapes. The performance of the thermocells is enhanced by incorporating carbon nanotubes into activated carbon textiles, due to improved charge transfer at the interface. In cold weather conditions （a surrounding temperature of 5 ℃）, the thermocell generates a short-circuit current density of 0.39 A/m2 and maximum power density of 0.46 mW/m2 from body heat （temperature of 36℃）. For practical use, we have shown that the thermocell charges up a capacitor when worn on a T-shirt by a person. We also have demonstrated that the electrical energy generated from waste pipe heat using a serial array of the thermocells and voltage converters can power a typical commercial light emitting diode （LED）.
