HOW CAN WE TEACH STUDENT TO ESTIMATE VERTICAL JUMP HEIGHTS USING GROUND REACTION FORCE DATA

The purpose of this study was to estimate vertical jump heights using ground reaction force (GRF) data and to suggest one practical example of biomechanical theory application to a real human motion. Vertical jump heights of impulse and flight time method were statistically smaller than three-dimensional video method. The causes of height differences seemed mainly from the fact that impulse was used to move jumper into the horizontal direction as well as into the vertical direction. Other important factors for accurate height calculation are jumper's mass and threshold value of GRF data collection. Vertical jump height calculation with GRF data showed an example of practical application of biomechanical theory to human motion and demonstrated a way of GRF equipment use for effective biomechanical theory education

Stability of unstable perovskites : recent strategies for making stable perovskite solar cells

Perovskite solar cells (PSCs) are now crossing the certified 23.2% power conversion efficiency (PCE), however, the stability of organic-lead halide perovskites, cost of additives doped hole transport layer (HTL) and upscaling from lab-scale to industrial scale without hampering its efficiency are challenging tasks for its commercial application. These problems could be tackled via different aspects which includes the synthesis of promising electron transport layers (ETLs) and HTLs, synthesis of mixed perovskites via combination of 3D and stable 2D perovskite, replacement of poor-stable methylammonium (MA) cation with MA free perovskite and capping inorganic materials will be the best choice toward highly efficient air-thermal-stable perovskite solar cells (PSCs). This perspective focuses on the current strategies in PSCs for making the stable PSCs via low-cost, easily processed components and shared our views toward commercialization

Symplectic Embedding of a Massive Vector-Tensor Theory with Topological Coupling

In the symplectic Lagrangian framework we newly embed an irreducible massive vector-tensor theory into a gauge invariant system, which has become reducible, by extending the configuration space to include an additional pair of scalar and vector fields, which give the desired Wess-Zumino action. A comparision with the BFT Hamiltonian embedding approach is also done.Comment: LaTeX file, 23 page

Intrinsic and extrinsic stability of triple-cation perovskite solar cells through synergistic influence of organic additive

Surface- or bulk-passivation using organic additives plays a critical role in improving the performance and stability of hybrid perovskite solar cells (HPSCs). Here, we report 2-hydroxyethyl acrylate (HEA) as an additive to reduce crystallization and passivate defects. Because of the dual functionality of the HEA additive, the optimized HPSCs yield 22.05% and 21.46% power conversion efficiency (PCE), respectively, for mesostructured negative-intrinsic-positive (n-i-p)- and planar positive-intrinsic-negative (p-i-n)-type device configurations, which is much higher than control devices. Large devices with 1 cm2 active area also produce a promising 20.03% PCE, which is comparable to the current efficiency. Time-of-flight secondary ion mass spectroscopy (TOF-SIMS) measurement analysis indicates the HEA settles not only in grain boundaries but also within the perovskite grain, which facilitates passivation and suppresses halogen-ion migration. Importantly, photostability analysis reveals negligible efficiency loss over 1,000 h under continuous 1 sun illumination under different environmental conditions

Synthesis of nanoporous Mo:BiVO4 thin film photoanodes using the ultrasonic spray technique for visible-light water splitting

The use of bismuth vanadate (BiVO4) scheelite structures for converting solar energy into fuels and chemicals for fast growth in lab to industrial scale for large-area modules is a key challenge for further development. Herein, we demonstrate a new ultrasonic spray technique as a scalable and versatile coating technique for coating pristine and doped nanoporous BiVO4 thin film photoanodes directly on FTO-coated glass substrates for water splitting under visible irradiation. The successful Mo doping in BiVO4 lattice was confirmed by various characterization techniques such as XRD, Raman, EDS and XPS. The Mo:BiVO4 photoelectrode showed excellent performance with higher stability as compared to pristine BiVO4 samples

Implementing Dopant-Free Hole-Transporting Layers and Metal-Incorporated CsPbI2Br for Stable All-Inorganic Perovskite Solar Cells

Mixed-halide CsPbI2Br perovskite is promising for efficient and thermally stable all-inorganic solar cells; however, the use of conventional antisolvent methods and additives-based hole-transporting layers (HTLs) currently hampers progress. Here, we have employed hot-air-assisted perovskite deposition in ambient condition to obtain high-quality photoactive CsPbI2Br perovskite films and have extended stable device operation using metal cation doping and dopant-free hole-transporting materials. Density functional theory calculations are used to study the structural and optoelectronic properties of the CsPbI2Br perovskite when it is doped with metal cations Eu2+ and In3+. We experimentally incorporated Eu2+ and In3+ metal ions into CsPbI2Br films and applied dopant-free copper(I) thiocyanate (CuSCN) and poly(3-hexylthiophene) (P3HT)-based materials as low-cost hole transporting layers, leading to record-high power conversion efficiencies of 15.27% and 15.69%, respectively, and a retention of >95% of the initial efficiency over 1600 h at 85 °C thermal stress

Implementing dopant-free hole-transporting layers and metal-incorporated CsPbI2Br for stable all-inorganic perovskite solar cells

Mixed-halide CsPbI2Br perovskite is promising for efficient and thermally stable all-inorganic solar cells; however, the use of conventional antisolvent methods and additives-based hole-transporting layers (HTLs) currently hampers progress. Here, we have employed hot-air-assisted perovskite deposition in ambient condition to obtain high-quality photoactive CsPbI2Br perovskite films and have extended stable device operation using metal cation doping and dopant-free hole-transporting materials. Density functional theory calculations are used to study the structural and optoelectronic properties of the CsPbI2Br perovskite when it is doped with metal cations Eu2+ and In3+. We experimentally incorporated Eu2+ and In3+ metal ions into CsPbI2Br films and applied dopant-free copper(I) thiocyanate (CuSCN) and poly(3-hexylthiophene) (P3HT)-based materials as low-cost hole transporting layers, leading to record-high power conversion efficiencies of 15.27% and 15.69%, respectively, and a retention of >95% of the initial efficiency over 1600 h at 85 °C thermal stress

Source Characteristics of Atmospheric CO(2)and CH(4)in a Northeastern Highland Area of South Korea

This study aims to present the atmospheric CO(2)and CH(4)levels and analyze their source characteristics at an observation station in a northeastern highland area of Korea for the 2012-2014 period. We summarized the measured CO(2)and CH(4)concentrations for the 2012-2014 period. In addition, we characterized the major source of the rise of CO(2)and CH(4)in Ganseong (GS) by employing bivariate polar plots (BPP) and the concentration weighted trajectory (CWT) method together with currently available information on emission sources. For the three years, CO(2)was generally high in the order of winter, spring, autumn and summer and CH(4)high in the order of winter, autumn, spring and summer. The observed positive correlations between the hourly CO(2)and CH(4)in every season suggested the possibility of shared common emission sources, but there is a necessity for elucidation on this in the future. The BPP analysis indicated the local sources that are likely to be associated with the rise of greenhouse gases (GHGs) observed at GS (combustion in the village, plant respirations nearby GS, and mobile emissions on the nearby road for CO(2)and leakages from the gas stations along the road and agricultural activities for CH4). Synthesizing the CWT results together with emission source information from national and global emission inventories, we identified likely major source areas and characterized major emission sources. For example, the identified major sources for the winter CO(2)are coal combustion, coal washing and industrial activities in Inner Mongolia, northern and the northeastern China, fuel burning for the energy for the infrastructure of a northwestern city in South Korea, and the manufacturing industry and fuel combustion in the northern parts of North Korea. Hopefully, these kinds of results will aid environmental researchers and decision-makers in performing more in-depth studies for GHG sources in order to derive effective mitigation strategies

Expanded polystyrene beads coated with intumescent flame retardant material to achieve fire safety standards

The compatibility and coating ratio between flame retardant materials and expanded polystyrene (EPS) foam is a major impediment to achieving satisfactory flame retardant performance. In this study, we prepared a water-based intumescent flame retardant system and methylene diphenyl diisocyanate (MDI)-coated expandable polystyrene microspheres by a simple coating approach. We investigated the compatibility, coating ratio, and fire performance of EPS- and MDI-coated EPS foam using a water-based intumescent flame retardant system. The microscopic study revealed that the water-based intumescent flame retardant materials were successfully incorporated with and without MDI-coated EPS microspheres. The cone calorimeter tests (CCTs) of the MDI-coated EPS containing water-based intumescent flame retardant materials exhibited better flame retardant performance with a lower total heat release (THR) 7.3 MJ/m2, peak heat release rate (PHRR) 57.6 kW/m2, fire growth rate (FIGRA) 2027.067 W/m2.s, and total smoke production (TSP) 0.133 m2. Our results demonstrated that the MDI-coated EPS containing water-based intumescent flame retardant materials achieved flame retarding properties as per fire safety standards