No abstract

A CD-ROM consisting of videos of two lessons by different teachers demonstrating exemplary science teaching was used to elicit, develop and track the changing conceptions of good science teaching of student teachers enrolled for the one-year Postgraduate Diploma in Education (PGDE) at several stages during the programme. It was found that the videos acted as an effective probe to elicit student teachers' conceptions and had significant impact on those conceptions at different stages of the programme through the provision of teacher models demonstrating exemplary teaching. The experience has extended novice teachers' awareness of alternative teaching methods and approaches not experienced in their own schooling, broadened their awareness of different classroom situations, provided proof of existence of good practices and prompted them to reflect on their current conceptions of good science teaching. Most importantly, the strategy of asking student teachers to watch the same videos on three separate occasions at different times of the course was recognized by them as a crucial element in facilitating their reflection on their changing conceptions of good science teaching.

Polyurethanes incorporated with rhenium diimine complexes were synthesized. The polymers exhibited interesting morphologies and solution properties. Results from gel permeation chromatography suggested the formation of polymer aggregates in solutions. The polymers could act as probes for metal ions. The addition of metal ions to polymer solutions led to significant changes in the electronic absorption properties of the polymer solutions. This was attributed to the interactions between the polyether moieties and metal ions. The metal complexes could also act as efficient photosensitizers. After doping with charge‐transport viologens, the photoconductivity of the polymers was greatly enhanced. The experimental quantum efficiency was simulated with Onsager's theory. The thermalization distances and the primary yields were typically 12–14 Å and 10−3, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1708–1715, 2003

Photovoltaic devices were fabricated using rhenium bis(arylimino)acenaphthene (DIAN) complex containing poly(p-phenylenevinylene). These polymers absorb strongly in the visible region at ca. 440-550 nm. In addition, this type of transition metal based polymers have been shown to exhibit large photo-sensitivity due to the presence of the rhenium complex, which has a relatively long-lived Metal-to-Ligand Charge Transfer (MLCT) character. By using this type of polymers, the metal content can be adjusted easily by simply changing the monomer feed ratio. Moreover, the excited state properties and electronic absorption properties can be modified by varying the structure of the diimine ligand coordinated to the metal. This approach allows us to fine-tune the absorption spectra of the polymers by employing different types of rhenium complex derivatives. PEDOT:PSS and PTCDI were used as the hole and electron transport layers, respectively. The ITO/PEDOT:PSS/DIAN-PPV/PTCDI/Al devices were found to exhibit photovoltaic response under the illumination of AM1 solar radiation. The short-circuit current I sc , open-circuit voltage V oc , and the fill factor FF were measured to be 38 µ A/cm 2 , 0.93 V and 0.21 respectively. Another photovoltaic device was prepared with the structure ITO/PEDOT:PSS/DIAN-PPV:TiO 2 /PTCDI/Al and its photovoltaic properties were studied. The presence of TiO 2 will assist the electron transport of the DIAN-PPV to the PTCDI, in which the electrons can be collected at the aluminium electrode. The short-circuit current I sc , open-circuit voltage V oc , and the fill factor FF were measured to be 51 µ A/cm 2 , 1.18 V and 0.12 respectively. It was observed that the power conversion efficiency of photovoltaic devices related closely to the rhenium content and the structure of the rhenium complex used.