Tuning the self-assembled 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol nanoarchitectures using the phase inversion method

[[abstract]]1,3:2,4-Di(3,4-dimethylbenzylidene) sorbitol (DMDBS) molecules can self-assemble into nanoscaled structures in organic solvents and polymer melts. The nanofibril structures were the mostly found. In this study, we used two phase inversion methods, i.e., dry and wet methods, to obtain different DMDBS nanoarchitectures. Poly(vinylidene fluoride) (PVDF) was chosen as polymer matrix, and the DMDBS structures were tuned by the process of PVDF membrane formation (crystallization and liquid–liquid demixing). When the membrane was prepared using the dry method, the DMDBS structure is controlled by the PVDF crystallization. Fewer DMDBS nanofibrils formed on the surfaces, and no nanofibrils were found in the cross-sections. On the other hand, when the membrane was prepared using the wet method, the liquid–liquid demixing (nonsolvent induced phase separation) occurred simultaneously as PVDF crystallized, and thus influenced the aggregation of DMDBS molecules. DMDBS is an amphiphilic molecule with two hydrophilic hydroxyl groups. The addition of nonsolvent (water) caused a large number of DMDBS molecules to aggregate outside the hydrophobic PVDF. In addition, a new structure “nanomat” was found. The mat was composed of DMDBS nanofibrils with diameters of 10–20 nm, similar to those observed in the dry method membranes. Fourier transform infra-red spectroscopy indicates that the DMDBS molecules self-assembled (aggregated) mainly through intermolecular hydrogen bonding in the presence of PVDF. The more intermolecular hydrogen bonding between DMDBS existed, the more excessive amounts of DMDBS molecules were, leading to the formation of nanomats.[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子

Attention to Intentions—How to Stimulate Strong Intentions to Change

The implementation of educational reforms requires behavioral changes from the teachers involved. Theories on successful behavioral change prescribe the following conditions: teachers need to possess the necessary knowledge and skills, form strong positive intentions to perform the new behavior, and have a supporting environment for change. However, existing approaches to teacher professional development in the context of educational reforms are predominantly aimed at the development of knowledge and skills and at creating a supporting environment, but lack attention to teachers’ intentions to change. In the study described in this article, we performed “motivating-for-educational-change” interviews (MECI) and explored the influence on teachers’ intentions to change in the direction of the proposed national biology education reform, that is, the introduction of a context-based curriculum. The MECI comprised two tools: building on earlier successful experiences and using lesson segments to rearrange instructional approaches. We explored the influence of the MECI technique on the strength and specificity of participating teachers’ intentions. When conducting the MECI, many participants expressed that they now realized how they had already implemented aspects of the reform in their regular instructional approaches. Furthermore, all the participants formulated stronger and more specific intentions to change their regular instructional approach towards that of the proposed reform while taking their regular instructional approach as a starting point

The Concept of Competence and Its Relevance for Science, Technology and Mathematics Education

Since the beginning of the twenty-first century, the concept of competence has been introduced as a new paradigm in several educational systems. It reflects the need of educational systems to respond to societal and economic changes, i.e. the transition from industrial- to information-based societies. In contrast to earlier educational goals that focused more on basic skills and knowledge expectations, competences are more functionally oriented. They involve the ability to solve complex problems in a particular context, e.g. in vocational or everyday situations. In science, technology and mathematics education, the concept of competence is closely linked to the concept of literacy. Apart from these rather cognitive and affective perspectives influenced by the need to assess students’ achievement of desired learning goals in relation to their interest and motivation, the perspectives of the concept of Bildung as well as of the labour market influence today’s definition of educational goals. In order to address these perspectives, twenty-first-century skills were defined that encompass skills believed to be critically important to success in today’s world like, e.g. innovation and communication. This chapter addresses these developments by describing the concept of competence, by explaining its relevance for science, technology and mathematics education and by examining future directions. The chapter concludes with some remarks regarding commonalities and differences between the three domains: science, technology and mathematics