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This study examined the impact of including a formal requirement of achieving predetermined energy expenditures as part of students' participation grades during a Sport Education-based college physical education class. Calorie consumption was measured using the Heart Zones Blink 3.0 sensor, and the percentage of students who reached the lesson target was calculated across a 15-week semester. The instructor kept a weekly journal and students participated in interviews at mid and end of term. Results showed that the average calorie consumption across the semester well exceeded the daily targets, while the percentage of students who reached the daily challenge cuto# ranged from 77% to 100% (average = 87%). Analysis of the journal entries and interviews resulted in the generation of four themes: students' commitment to reaching the activity targets, group-based strategies for achieving physical activity targets, activity consequences of oWciating roles, and activity challenges problematized skill development for some. [ABSTRACT FROM AUTHOR]

Hexagonal In2O3-ZnO heterostructural composites with high visible-light photocatalytic activity have been obtained by a one-step hydrothermal process. The microscopic analysis revealed that the In2O3-ZnO heterostructures were composed of In2O3 nanoparticles dispersed on the surface of ZnO nanodisks. Compared with pure ZnO nanodisks, the obtained In2O3-ZnO composites exhibit significantly enhanced photocatalytic activity for methylene blue degradation under visible light irradiation. The enhanced photocatalytic activity could be attributed to the formation of heterostructures, which might improve the separation of photogenerated electrons and holes. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) van der Waals heterostructures are ideal building blocks of optoelectronic devices for muti-functional applications. In this work, the electronic and optical properties of 2D MoS2/GaN van der Waals heterostructures (vdW HTs) are explored via first-principles calculations, considering interlayer coupling and external electric field modulations. The results show that 2D MoS2/GaN vdW HTs possess a direct gap about 1.79 eV with type-II band alignment and excellent optical absorbance about ~5.5  ×  105 cm−1. Moreover, changing interlayer coupling and applying external electric fields can effectively and broadly engineer its band gap and optical properties. These predicted results may be useful to experimentally construct ultra-thin optoelectronic devices based on 2D MoS2/GaN vdW HTs. [ABSTRACT FROM AUTHOR]

Lead-free piezoelectric materials attract more and more attention owing to the environmental toxicity of lead-containing materials. In this work, we review our first attempts of single crystal grown by the top-seeded solution growth method of BaTiO3 substituted with zirconium and calcium (BCTZ) and (K0.5Na0.5)NbO3 substituted with lithium, tantalum, and antimony (KNLSTN). The growth methodology is optimized in order to reach the best compositions where enhanced properties are expected. Chemical analysis and electrical characterizations are presented for both kinds of crystals. The compositionally-dependent electrical performance is investigated for a better understanding of the relationship between the composition and electrical properties. A cross-over from relaxor toferroelectric state in BCTZ solid solution is evidenced similar to the one reported in ceramics. In KNLSTN single crystals, we observed a substantial evolution of the orthorhombic-to-tetragonal phase transition under minute composition changes. [ABSTRACT FROM AUTHOR]

A ferroelectric field effect in the bulk heterojunction was found when an external electric field (EEF) was applied on the active layer of polymer solar cells (PSCs) during the annealing process of the active layer spin-coated with poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester. For one direction field, the short circuit current density of PSCs was improved from 7.2 to 8.0 mA/cm², the power conversion efficiency increased from 2.4% to 2.8%, and the incident photon-to-current conversion efficiency increased from 42% to 49% corresponding to the different EEF magnitude. For an opposite direction field, the applied EEF brought a minus effect on the performance mentioned above. EEF treatment can orientate molecular ordering of the polymer, and change the morphology of the active layer. The authors suggest a explanation that the ferroelectric field has been built in the active layer, and therefore it plays a key role in PSCs system. A needle-like surface morphology of the active film was also discussed. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of electrode geometry on the performance of polymer solar cells (PSCs). The negative electrodes with equal area (0.09 cm2) but different shape (round, oval, square and triangular) are evaluated with respect to short-circuit current density, open-circuit voltage, fill factor and power conversion efficiency of PSCs. The results show that the device with round electrodes gives the best photovoltaic performance; in contrast, the device with triangular electrodes reveals the worst properties. A maximum of almost a 19% increase in power conversion efficiency with a round electrode is obtained in the devices compared with that of the triangular electrode. To conclude, the electrode boundary curvature has a significant impact on the performance of PSCs. The larger curvature, i.e. sharper electrodes edges, perhaps has a negative effect on exciton separation and carrier transport in photoelectric conversion processes. [ABSTRACT FROM AUTHOR]