Thermal and electromechanical properties of melilite-type piezoelectric single crystals

Melilite-type crystals, including Ca2Ga2SiO7, Ca2MgSi2O7, and CaNdGa3O7, were successfully grown by the Czochralski technique. Thermal properties were investigated and full matrices of electromechanical constants of these melilite crystals were evaluated by impedance method, with d14 being on the order of 5.3-9.3 pC/N. The relationship between microstructure and electromechanical properties of the three kinds of crystals was established, in order to explore the piezoelectric origin and further optimize the piezoelectric properties. The distortion of eight-fold antiprisms and the distortion/rotation of tetrahedrons were thought to contribute to the piezoelectric d14 and d36, respectively. In addition, the layered structure leads to strong anisotropic behavior, accounts for the high resistivity along Z direction in Ca2MgSi2O7, while the disordered structure accounts for the degraded resistivity in CaNdGa3O7. The properties at elevated temperature were investigated, where the elastic constants show high thermal stability over the range of 25-500 C, with minimal variation of 6%

Examining the potential of web-based multimedia to support complex fine motor skill learning: An empirical study

Research on the utilization of the Web for complex fine motor skill learning that involves whole body movements is still scarce. The aim of this study was to evaluate the impact of the introduction of a multimedia web-based learning environment, which was targeted at a rhythmic gymnastics routine consisting of eight fine motor skills, into an undergraduate course in a physical education department, as a complementary tool to campus-based instruction. The impact was evaluated in terms of: acquisition of knowledge regarding the routine skills by students, improvement of students' ability to execute the routine, and students' responses to the environment. The study followed a pretest/posttest experimental design and involved 76 students randomly split into two groups: The Multimedia Web-based Learning Group (MWLG) students (N = 38), who attended campus-based instruction on the routine and also used the environment in their own space and time, and the Traditional On-site Instruction Group (TOIG) students (N = 38), who only attended campus-based instruction. The research data were gathered through student questionnaires and ratings of students' performances. It was found that the use of the environment as a supplement to campus-based instruction increased the effectiveness of this instruction as regards the cognitive component of motor skill learning (i.e. acquisition of knowledge regarding the routine skills) and was well-accepted by the students, although it did not have any significant contribution to the physical component of motor skill learning (i.e. performance of the routine skills). These findings partially support the future wider adoption of multimedia web-based learning environments within physical education and other academic disciplines that involve complex fine motor skill learning. Relevant implications are discussed. © 2013 Springer Science+Business Media New York