The aim of this study was to identify the immediate effect of self-modelling with different focus of attention strategies (i.e., internal vs. external) on the teaching/learning of gymnastics ...motor-skills. Fifty-nine non-gymnast students participated in this study and were divided into three groups (i.e., an external focus group (EF), an internal focus group (IF), and a control group (CG)). Each participant’s performance of the back dismount in the parallel bars was assessed before the experiment (i.e., base-score), and each participant was asked to provide a self-evaluation of their performance and their efficiency percentage. Afterwards, participants received a specific learning session (i.e., self-modelling with external focus, self-modelling with internal focus, or traditional learning with verbal instruction) and performed the back dismount in the parallel bars again immediately after (i.e., final score). Four international judges evaluated performance of our participants. The results showed that the EF and IF outperformed the CG in the final score. Importantly, a significant difference between the base and the final score was observed in the EF and IF, but not in the CG. In addition, the EF showed the highest percentage of improvement (Δ-score) and self-estimation scores compared to the two other groups. In conclusion, this study supports the adoption of external focus of attention for teaching/learning gymnastics motor-skills.
The development of high-performance anode materials is one of the greatest challenges for the practical implementation of Microbial Fuel Cell (MFC) technology. Copper (Cu) has a much higher ...electrical conductivity than carbon-based materials usually used as anodes in MFCs. However, it is an unsuitable anode material, in raw state, for MFC application due to its corrosion and its toxicity to microorganisms. In this paper, we report the development of a Cu anode material coated with a corrosion-resistant composite made of Polydimethylsiloxane (PDMS) doped with carbon nanofiber (CNF). The surface modification method was optimized for improving the interfacial electron transfer of Cu anodes for use in MFCs. Characterization of CNF-PDMS composites doped at different weight ratios demonstrated that the best electrical conductivity and electrochemical properties are obtained at 8% weight ratio of CNF/PDMS mixture. Electrochemical characterization showed that the corrosion rate of Cu electrode in acidified solution decreased from (17 ± 6) × 10
μm y
to 93 ± 23 μm y
after CNF-PDMS coating. The performance of Cu anodes coated with different layer thicknesses of CNF-PDMS (250 µm, 500 µm, and 1000 µm), was evaluated in MFC. The highest power density of 70 ± 8 mW m
obtained with 500 µm CNF-PDMS was about 8-times higher and more stable than that obtained through galvanic corrosion of unmodified Cu. Consequently, the followed process improves the performance of Cu anode for MFC applications.
This study aimed at exploring the key kinetic and kinematic factors of 110-m hurdle clearance performance using three-dimensional (3D) analysis system. Ten national level athletes participated in ...this study. The kinematic analysis of the hurdling sequences was recorded using ten mutually synchronized digital cameras. Body markers were digitized using SkillSpector® software. Ground-reaction force was calculated by using rigid body inverse dynamics using the Smith's equations. All variables were combined into components through a principal component analysis. The retained components have been used in a multiple regression analysis. Twenty variables were retained as key hurdling performance determinants. Specifically, the horizontal and vertical velocity of the centre of mass (COM) and the lead-leg/trail-leg in all phases (i.e., take-off, flight, and landing), horizontal and vertical displacement of the COM, the lead-leg/trail-leg vertical displacement, and the flight-time at clearance are among the main hurdling performance determinants. Overall, to improve hurdling performance, greater horizontal velocity, lower vertical displacement at flight and lower contact-time at the takeoff phases through a higher rate of force development are needed.
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FSPLJ, NUK, ODKLJ, UL, UM, UPUK
Phenylethyl ammonium trichloromercurate exhibits a structural phase transition at 402K Phase I-(402K)→ Phase II
This transition has been characterized by differential scanning calorimetry, dielectric ...measurements and X-ray diffraction. The space groups and the cell parameters of both phases were determined by X-ray diffraction from single crystals and powder samples. Phase I has space group I2 or I2/m, a = 25.88(2) Å, b = 7.792(3) Å; c = 5.971(4) Å; β = 96.14(1)°. Phase II has orthorhombic symmetry, space group Cmm2 or C222 with a = 25.91(1) Å; b = 7.836(5) Å; c = 6.116(4) Å.
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