The structural similarities with the references are 0.9922 for the complete FOV and above 0.9999 for the ROI.Bird feathers are complex structures that passively deflect as they interact with air to produce aerodynamic force. Newtonian theory suggests that feathers should be stiff to effectively utilize this force. Observations of flying birds indicate that feathers respond to aerodynamic loading via spanwise bending, twisting, and sweeping. These deflections are hypothesized to optimize flight performance, but this has not yet been tested. We measured deflection of isolated feathers in a wind tunnel to explore how flexibility altered aerodynamic forces in emulated gliding flight. Using primary feathers from seven raptors and a rigid airfoil, we quantified bending, sweep, and twisting, as well as ∝ (attack angle) and slip angle. We predicted that 1) feathers would deflect under aerodynamic load, 2) bending would result in lateral redirection of force, 3) twisting would alter spanwise ∝ "washout" and delay the onset of stall, and 4) flexural stiffness of feathers would exhibit positive allometry. The first three predictions were supported by our results, but not the fourth. We found that bending resulted in the generation of lateral forces towards the base of the feather on the order of ~10% of total lift. In comparison to the airfoil which stalled at ∝=13.5°, all feathers continued to increase lift production with increasing angle of attack to the limit of our range of measurements (α=27.5°). We observed that feather stiffness exhibited positive allometry (∝ mass1.1±0.3), approximately consistent with previous research showing that stiffness does not scale as predicted by geometric similarity (∝ mass1.67). These findings demonstrate that feather flexibility may provide passive roll stability and delay stall by twisting to reduce local ∝ at the feather tip. Our findings are the first to measure forces due to feather deflection under aerodynamic loading and can inform future models of avian flight as well as biomimetic morphing-wing technology.Synthesis of rational nanostructure design of hybrid materials including uniformly growing, stable and highly porous structures have received a great deal of attention for many energy storage applications. In this study, the positive electrode of the uniform distribution of NiCo2O4 nanorods anchored on carbon nanofibers has been successfully prepared by in-situ growth under the hydrothermal process. Whereas, the activated multichannel carbon nanofibers (AMCNFs) have been fabricated via electrospinning followed by alkaline activation as the negative electrode. The crystal phase, morphological structure for the proposed electrode materials were characterized by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Moreover, the electrochemical behaviors were investigated using cyclic voltammetry (CV), galvanostatic charge and discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurements. Compared to the neat CNFs and the pristine NiCo2O4, the NiCo2O4@CNFs hybrid electrodes showed better electrochemical performance and achieved a high specific capacitance up to 649 F g-1 at a current density of 3 A g-1. The optimized NiCo2O4@CNFs//AMCNFs asymmetric device achieved a high energy density of 38.5 Wh kg-1 with a power density of 1.6 kW kg-1 and possessed excellent recyclability with 93.1% capacitance retention over 6000 charging/discharging cycles. Overall, the proposed study introduces a facile strategy for the robust design of hybrid structured as effective nanomaterials based electrode for high-performance electrochemical supercapacitors.The broad application of metal-air batteries and fuel cells have been greatly limited due to their slow kinetics of oxygen electrodes involving the oxygen reduction reaction (ORR), and therefore the development of high-efficient, low-cost and high-reserve ORR electrocatalysts is of great significance. Herein, a hypersaline-protected pyrolysis strategy is presented for preparing 3D honeycombed cobalt, nitrogen co-doped carbon nanosheets (Co/N-CNS) by using eco-friendly biomass as a carbon and nitrogen source. During the hypersaline-protected pyrolysis, the pyridinic nitrogen-rich biomass facilitates the formation of highly active Co/N active sites among the resultant Co/N-CNS, while the templating-washing-drying cyclic utilization of salts creates honeycombed pore structures among the Co/N-CNS. Due to the structural features of honeycombed pores and uniform distributed active sites, the Co/N-CNS catalyst offers excellent ORR activity, high durability and methanol-tolerant performance in an alkaline electrolyte. As a demonstration, a primary Zn-air battery using the Co/N-CNS cathode delivers a high power density and excellent operating stability beyond that of commercial Pt/C cathode.Long term stability is a major obstacle to the success of perovskite solar cell (PSC) photovoltaic technology. PSC performance deteriorates significantly in the presence of humidity, oxygen and exposure to UV light and heat. Here the change in charge transport properties of PSC with temperature and the associated significant drop in device performance at high temperature have been investigated. The latter is shown to be primarily due to an increase in charge carrier recombination, which impacts the open-circuit voltage. To understand the pathway of temperature-induced degradation, low-frequency 1/f noise characteristics, and the capacitance-frequency, as well as capacitance-voltage characteristics have been investigated under various conditions. https://www.selleckchem.com/products/--mk-801-maleate.html The results show that at high operating temperature accumulation of ions and charge carriers at the interface increase the surface recombination. Aging experiments at different temperatures show high stability of PSCs up to temperature less then 70 °C, but a drastic, irreversible degradation occurs at higher temperature (≥80 °C). Low-frequency 1/f noise study revealed that the magnitude of normalized noise in degraded perovskite solar cells is four orders of magnitude higher than the pristine device. This study shows the power of low-frequency noise measurement technique as a highly sensitive non-invasive tool to study the degradation mechanism of PSCs.
The structural similarities with the references are 0.9922 for the complete FOV and above 0.9999 for the ROI.Bird feathers are complex structures that passively deflect as they interact with air to produce aerodynamic force. Newtonian theory suggests that feathers should be stiff to effectively utilize this force. Observations of flying birds indicate that feathers respond to aerodynamic loading via spanwise bending, twisting, and sweeping. These deflections are hypothesized to optimize flight performance, but this has not yet been tested. We measured deflection of isolated feathers in a wind tunnel to explore how flexibility altered aerodynamic forces in emulated gliding flight. Using primary feathers from seven raptors and a rigid airfoil, we quantified bending, sweep, and twisting, as well as ∝ (attack angle) and slip angle. We predicted that 1) feathers would deflect under aerodynamic load, 2) bending would result in lateral redirection of force, 3) twisting would alter spanwise ∝ "washout" and delay the onset of stall, and 4) flexural stiffness of feathers would exhibit positive allometry. The first three predictions were supported by our results, but not the fourth. We found that bending resulted in the generation of lateral forces towards the base of the feather on the order of ~10% of total lift. In comparison to the airfoil which stalled at ∝=13.5°, all feathers continued to increase lift production with increasing angle of attack to the limit of our range of measurements (α=27.5°). We observed that feather stiffness exhibited positive allometry (∝ mass1.1±0.3), approximately consistent with previous research showing that stiffness does not scale as predicted by geometric similarity (∝ mass1.67). These findings demonstrate that feather flexibility may provide passive roll stability and delay stall by twisting to reduce local ∝ at the feather tip. Our findings are the first to measure forces due to feather deflection under aerodynamic loading and can inform future models of avian flight as well as biomimetic morphing-wing technology.Synthesis of rational nanostructure design of hybrid materials including uniformly growing, stable and highly porous structures have received a great deal of attention for many energy storage applications. In this study, the positive electrode of the uniform distribution of NiCo2O4 nanorods anchored on carbon nanofibers has been successfully prepared by in-situ growth under the hydrothermal process. Whereas, the activated multichannel carbon nanofibers (AMCNFs) have been fabricated via electrospinning followed by alkaline activation as the negative electrode. The crystal phase, morphological structure for the proposed electrode materials were characterized by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Moreover, the electrochemical behaviors were investigated using cyclic voltammetry (CV), galvanostatic charge and discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurements. Compared to the neat CNFs and the pristine NiCo2O4, the NiCo2O4@CNFs hybrid electrodes showed better electrochemical performance and achieved a high specific capacitance up to 649 F g-1 at a current density of 3 A g-1. The optimized NiCo2O4@CNFs//AMCNFs asymmetric device achieved a high energy density of 38.5 Wh kg-1 with a power density of 1.6 kW kg-1 and possessed excellent recyclability with 93.1% capacitance retention over 6000 charging/discharging cycles. Overall, the proposed study introduces a facile strategy for the robust design of hybrid structured as effective nanomaterials based electrode for high-performance electrochemical supercapacitors.The broad application of metal-air batteries and fuel cells have been greatly limited due to their slow kinetics of oxygen electrodes involving the oxygen reduction reaction (ORR), and therefore the development of high-efficient, low-cost and high-reserve ORR electrocatalysts is of great significance. Herein, a hypersaline-protected pyrolysis strategy is presented for preparing 3D honeycombed cobalt, nitrogen co-doped carbon nanosheets (Co/N-CNS) by using eco-friendly biomass as a carbon and nitrogen source. During the hypersaline-protected pyrolysis, the pyridinic nitrogen-rich biomass facilitates the formation of highly active Co/N active sites among the resultant Co/N-CNS, while the templating-washing-drying cyclic utilization of salts creates honeycombed pore structures among the Co/N-CNS. Due to the structural features of honeycombed pores and uniform distributed active sites, the Co/N-CNS catalyst offers excellent ORR activity, high durability and methanol-tolerant performance in an alkaline electrolyte. As a demonstration, a primary Zn-air battery using the Co/N-CNS cathode delivers a high power density and excellent operating stability beyond that of commercial Pt/C cathode.Long term stability is a major obstacle to the success of perovskite solar cell (PSC) photovoltaic technology. PSC performance deteriorates significantly in the presence of humidity, oxygen and exposure to UV light and heat. Here the change in charge transport properties of PSC with temperature and the associated significant drop in device performance at high temperature have been investigated. The latter is shown to be primarily due to an increase in charge carrier recombination, which impacts the open-circuit voltage. To understand the pathway of temperature-induced degradation, low-frequency 1/f noise characteristics, and the capacitance-frequency, as well as capacitance-voltage characteristics have been investigated under various conditions. https://www.selleckchem.com/products/--mk-801-maleate.html The results show that at high operating temperature accumulation of ions and charge carriers at the interface increase the surface recombination. Aging experiments at different temperatures show high stability of PSCs up to temperature less then 70 °C, but a drastic, irreversible degradation occurs at higher temperature (≥80 °C). Low-frequency 1/f noise study revealed that the magnitude of normalized noise in degraded perovskite solar cells is four orders of magnitude higher than the pristine device. This study shows the power of low-frequency noise measurement technique as a highly sensitive non-invasive tool to study the degradation mechanism of PSCs.
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