Transfer of a teaching-learning sequence from greek to italian school : do similarities in educational systems really help?

The specific purpose of this paper is to investigate the changes that occurred in the process of the transfer of a Teaching-Learning Sequence (TLS) from the designer’s to a host’s context. Besides we discuss if the similarities between educational systems may actually favour such a transfer. The specific case concerns the transfer of a TLS on thermal properties of materials from the Greek educational context into Italian one. The research has been framed in the “Adaptation and Re-Invention” (ARI) theoretical model. According to this model, some “core” elements of the original TLS, namely, scientific concepts addressed, pedagogical approach adopted, ICT-enhanced aspects and the activities’ sequence, have been first identified and then adapted for the new context. The resulting new core elements of the transferred TLS have been compared with those of the original TLS to investigate about the feasibility of the transfer. Results show that the similarities between the two educational contexts acted mainly as facilitators of the transfer process. Moreover, direct communication and interactions between the involved groups and an external expert helped significantly the process. Data from implementations in the two educational contexts show also similar positive effects on students’ learning outcomes

Structure inhomogeneities, shallow defects, and charge transport in the series of thermoelectric materials K2Bi8−xSbxSe13

The charge transport properties of the low-dimensional thermoelectric materials K2Bi8-xSbxSe13 (02Bi8-xSbxSe13 was analyzed on the basis of the classical semiconductor theory and discussed in the context of recent band calculations. The results suggest that the K2Bi8-xSbxSe13 materials possess coexisting domains with semimetallic and semiconducting characters whose ratio is influenced by the value of x and by local defects. The extent and relative distribution of these domains control the charge transport properties. Electron diffraction experiments performed on samples of K2Bi8-xSbxSe13 with x=1.6 show evidence for such domains by indicating regions with long range ordering of K+/Bi3+ atoms and regions with increased disorder. The semiconducting behavior is enhanced with increasing x (i.e., Sb/Bi ratio) in the composition through a decrease of the semimetallic fraction

Models for the Analysis of~IR Reflectivity in TlBiTe2TlBiTe_2 with Different Size of Twins

In this work $TlBiTe_2$ were grown by a modified Bridgman technique and examined samples had different lateral dimensions of twins, ranging from 0.1 μm to 1 μm. The average lateral size of the twins seems to affect free carrier concentration and plasma frequency. Infrared spectra were analyzed by two models, the extended Drude model and a generalized empirical model of frequency-dependent damping factor. Increase in size of twins affects the electronic properties and hence plasma reflectivity and free carrier concentration of $TlBiTe_2$

On the Recovery of Wasted Heat Using a Commercial Thermoelectric Device

Waste heat recovery from car's exhaust gases provides an opportunity to significantly improve the overall car engine efficiency. One approach for recovering energy from the exhaust gases is to generate electrical power through thermoelectric conversion. A thermoelectric device, using a commercially available thermoelectric generator module was made, in order to measure the gained power and efficiency at different places of the exhaust pipe of a small size car (Toyota Starlet, 1300cc), for various engine loads. With the use of a modeling approach, we evaluated the thermal contact resistances and their influence on the final device efficiency

The experimental model of a non-ideal memristor

In this paper, the experimental study and the related evaluation of the memristive behavior demonstrated by a simple device, a tungsten filament bulb, is presented. It was found that this device operates as a non-ideal memristor, demonstrating a Type-II non-crossing, pinched hysteretic loop, while the evaluation of experimental results clearly hints to assorting the type of this device as an extended memristor. © 2016 IEEE

A non-deal memristor device

In this brief, the memristive behavior of a very simple device, that of a tungsten filament bulb, is reported. In specific, this kind of element operates as a non-ideal memristor, thus demonstrating a Type-II non-crossing, pinched hysteretic loop. A brief description of this experimental behavior from the perspective of memristive properties, is apposed. © 2015 IEEE

Transfer of a teaching-learning sequence from greek to italian school : do similarities in educational systems really help?

The specific purpose of this paper is to investigate the changes that occurred in the process of the transfer of a Teaching-Learning Sequence (TLS) from the designer’s to a host’s context. Besides we discuss if the similarities between educational systems may actually favour such a transfer. The specific case concerns the transfer of a TLS on thermal properties of materials from the Greek educational context into Italian one. The research has been framed in the “Adaptation and Re-Invention” (ARI) theoretical model. According to this model, some “core” elements of the original TLS, namely, scientific concepts addressed, pedagogical approach adopted, ICT-enhanced aspects and the activities’ sequence, have been first identified and then adapted for the new context. The resulting new core elements of the transferred TLS have been compared with those of the original TLS to investigate about the feasibility of the transfer. Results show that the similarities between the two educational contexts acted mainly as facilitators of the transfer process. Moreover, direct communication and interactions between the involved groups and an external expert helped significantly the process. Data from implementations in the two educational contexts show also similar positive effects on students’ learning outcomes

Analysis of Phase Separation in High Performance PbTe–PbS Thermoelectric Materials

Phase immiscibility in PbTe–based thermoelectric materials is an effective means of top-down synthesis of nanostructured composites exhibiting low lattice thermal conductivities. PbTe1− x Sx thermoelectric materials can be synthesized as metastable solid solution alloys through rapid quenching. Subsequent post-annealing induces phase separation at the nanometer scale, producing nanostructures that increase phonon scattering and reduce lattice thermal conductivity. However, there has yet to be any study investigating in detail the local chemical structure of both the solid solution and nanostructured variants of this material system. Herein, quenched and annealed (i.e., solid solution and phase-separated) samples of PbTe–PbS are analyzed by in situ high-resolution synchrotron powder X-ray diffraction, solid-state 125Te nuclear magnetic resonance (NMR), and infrared (IR) spectroscopy analysis. For high concentrations of PbS in PbTe, e.g., x \u3e 16%, NMR and IR analyses reveal that rapidly quenched samples exhibit incipient phase separation that is not detected by state-of-the-art synchrotron X-ray diffraction, providing an example of a PbTe thermoelectric “alloy” that is in fact phase inhomogeneous. Thermally-induced PbS phase separation in PbTe–PbS occurs close to 200 ° C for all compositions studied, and the solubility of the PbS phase in PbTe at elevated temperatures \u3e 500 ° C is reported. The findings of this study suggest that there may be a large number of thermoelectric alloy systems that are phase inhomogeneous or nanostructured despite adherence to Vegard’s Law of alloys, highlighting the importance of careful chemical characterization to differentiate between thermoelectric alloys and composites