We report the growth of Si nanostructures, either as thin films or nanoparticles, on graphene substrates. The Si nanostructures are shown to be single crystalline, air stable and oxidation resistive, as indicated by t...We report the growth of Si nanostructures, either as thin films or nanoparticles, on graphene substrates. The Si nanostructures are shown to be single crystalline, air stable and oxidation resistive, as indicated by the observation of a single crystalline Si Raman mode at around 520 cm^-1, a STM image of an ordered surface structure under ambient condition, and a Schottky junction with graphite. Ultra-thin silicon regions exhibit silicene-like behavior, including a Raman mode at around 550 cm^-1, a triangular lattice structure in STM that has distinctly different lattice spacing from that of either graphene or thicker Si, and metallic conductivity of up to 500 times higher than that of graphite. This work suggests a bottom-up approach to forming a Si nanostructure array on a large-scale patterned graphene substrate that can be used to fabricate nanoscale Si electronic devices.展开更多
Metal/Air batteries are considered to be promising electricity storage devices given their compactness, environmental benignity and affordability. As a commonly available metal, aluminum has received great attention s...Metal/Air batteries are considered to be promising electricity storage devices given their compactness, environmental benignity and affordability. As a commonly available metal, aluminum has received great attention since its first use as an anode in a battery. Its high specific energy （even better volumetric energy density than lithium） makes it ideal for many primary battery applications. However, the development of A1/Air cell with alkaline electrolyte has been lagged behind mainly due to the unfavorable parasitic hydrogen generation. Herein, we designed and constructed a novel A1/H_2/Air tandem fuel cell to turn the adverse parasitic reaction into a useful process. The system consists of two anodes, namely, aluminum and hydrogen, and one common air-breathing cathode. The aluminum acts as both the anode for the A1/Air sub-cell and the source to generate hydrogen for the hydrogen/air sub-cell. The aluminum/air sub-cell has an open circuit voltage of 1.45 V and the H_2/Air sub-cell of 0.95 V. We demonstrated that the maximum power output of aluminum as a fuel was largely enhanced by 31% after incorporating the H_2/Air sub-cell with the tandem concept. In addition, a passive design was utilized in our tandem system to eliminate the dependence on auxiliary pumping sub-systems so that the whole system remained neat and eliminated the dependence of energy consuming pumps or heaters which were typically applied in micro fuel cells.展开更多
Aquatic plants develop strong fragment propagation and colonization ability to endure the natural disturbances. However, detailed research of ability to endure the natural disturbances has been lacking to date. Theref...Aquatic plants develop strong fragment propagation and colonization ability to endure the natural disturbances. However, detailed research of ability to endure the natural disturbances has been lacking to date. Therefore, reproduction （shoot） and colonization （root） of shoot fragments of Potamogeton crispus L. with or without apices were investigated for the effect of apical dominance, and the growth of decapitated shoot fragments at three lengths （2, 4, 6 cm） was compared. Meanwhile, fragment propagation at levels of bud position was studied for bud position effect after escaping from apical dominance. The results showed significant increases occurred in the outgrowth of lateral branches on fragments decapitated compared with the fragments with apices, implying that apical dominance exists. Different lengths of fragments showed little difference in biomass allocations, but significant differences were noted in their propagation. Meanwhile, the effect of bud position was verified, due to the significant difference of average reproduction per node among the three length groups. Thus, the present study has made progress in the current understanding of aquatic plant dispersion among natural systems and contributes to improve methods of in vitro propagation for re-implantation purposes.展开更多
基金supported by ARO/Materials Science(Grant No.W911NF-10-1-0281 and W911NF-18-1-0079,managed by Dr.Chakrapani Varanasi)
文摘We report the growth of Si nanostructures, either as thin films or nanoparticles, on graphene substrates. The Si nanostructures are shown to be single crystalline, air stable and oxidation resistive, as indicated by the observation of a single crystalline Si Raman mode at around 520 cm^-1, a STM image of an ordered surface structure under ambient condition, and a Schottky junction with graphite. Ultra-thin silicon regions exhibit silicene-like behavior, including a Raman mode at around 550 cm^-1, a triangular lattice structure in STM that has distinctly different lattice spacing from that of either graphene or thicker Si, and metallic conductivity of up to 500 times higher than that of graphite. This work suggests a bottom-up approach to forming a Si nanostructure array on a large-scale patterned graphene substrate that can be used to fabricate nanoscale Si electronic devices.
文摘Metal/Air batteries are considered to be promising electricity storage devices given their compactness, environmental benignity and affordability. As a commonly available metal, aluminum has received great attention since its first use as an anode in a battery. Its high specific energy （even better volumetric energy density than lithium） makes it ideal for many primary battery applications. However, the development of A1/Air cell with alkaline electrolyte has been lagged behind mainly due to the unfavorable parasitic hydrogen generation. Herein, we designed and constructed a novel A1/H_2/Air tandem fuel cell to turn the adverse parasitic reaction into a useful process. The system consists of two anodes, namely, aluminum and hydrogen, and one common air-breathing cathode. The aluminum acts as both the anode for the A1/Air sub-cell and the source to generate hydrogen for the hydrogen/air sub-cell. The aluminum/air sub-cell has an open circuit voltage of 1.45 V and the H_2/Air sub-cell of 0.95 V. We demonstrated that the maximum power output of aluminum as a fuel was largely enhanced by 31% after incorporating the H_2/Air sub-cell with the tandem concept. In addition, a passive design was utilized in our tandem system to eliminate the dependence on auxiliary pumping sub-systems so that the whole system remained neat and eliminated the dependence of energy consuming pumps or heaters which were typically applied in micro fuel cells.
基金Supported by the Hi-Tech Research and Development (863) Program of China (2003AA06011000-04 and 2002AA601012-06).
文摘Aquatic plants develop strong fragment propagation and colonization ability to endure the natural disturbances. However, detailed research of ability to endure the natural disturbances has been lacking to date. Therefore, reproduction （shoot） and colonization （root） of shoot fragments of Potamogeton crispus L. with or without apices were investigated for the effect of apical dominance, and the growth of decapitated shoot fragments at three lengths （2, 4, 6 cm） was compared. Meanwhile, fragment propagation at levels of bud position was studied for bud position effect after escaping from apical dominance. The results showed significant increases occurred in the outgrowth of lateral branches on fragments decapitated compared with the fragments with apices, implying that apical dominance exists. Different lengths of fragments showed little difference in biomass allocations, but significant differences were noted in their propagation. Meanwhile, the effect of bud position was verified, due to the significant difference of average reproduction per node among the three length groups. Thus, the present study has made progress in the current understanding of aquatic plant dispersion among natural systems and contributes to improve methods of in vitro propagation for re-implantation purposes.
