4 research outputs found
Arylethynyl Derivatives of the Dihydroazulene/Vinylheptafulvene Photo/Thermoswitch: Tuning the Switching Event
No full textA selection of dihydroazulene (DHA) photoswitches incorporating an arylethynyl-substituent in the seven-membered ring was prepared by palladium-catalyzed Sonogashira cross-coupling reactions employing a suitable bromo-functionalized DHA. Shielding of the alkyne bridge and separating the aryl and DHA units, by sterically demanding groups, was required to obtain stable compounds. The DHAs underwent a light-induced ring-opening to vinylheptafulvenes (VHFs) which were thermally converted to a mixture of two DHA regioisomers, one of which was the original one. The influence of the aryl groups on the DHA and VHF absorptions and on their interconversion was investigated in detail. The rates of the switching events were finely tuned by the donor or acceptor strength of the aryl group. The thermal ring closure was found to proceed most readily in the presence of an electron-donating group on the seven-membered ring. The rate constant was found to follow a Hammett linear free energy correlation, which signals that stabilization of a positive charge in the seven-membered ring plays a crucial role in the ring-closure reaction. In view of these findings, it was possible to control the switching event by protonation/deprotonation of an anilino-substituted DHA. Also, the light-induced ring opening reaction was strongly controlled by acid/base. In addition to the mesomeric effects exerted by an arylethynyl group, the inductive effects exerted by different groups on the thermal ring closure were elucidated. Although the alkyne bridge transmits the electronic character of the aryl group, the ring-closure is retarded for all the ethynylated compounds relative to the parent unsubstituted compound. Along with our synthesis of suitable arylalkynes, we discovered an interesting byproduct in a Sonogashira cross-coupling reaction involving a nitrophenyl group, namely a diaryl azoxy compound. Its structure was confirmed by X-ray crystallographic analysis
A multi-sector version of the Post-Keynesian growth model
No full textWith this inquiry we seek to develop a disaggregated version of the post-Keynesian approach to economic growth, by showing that indeed it can be treated as a particular case of the Pasinettian model of structural change and economic expansion. By relying upon vertical integration it becomes possible to carry out the analysis initiated by Kaldor (1956) and Robinson (1956, 1962), and followed by Dutt (1984), Rowthorn (1982) and later Bhaduri and Marglin (1990) in a multi-sectoral model in which demand and productivity increase at different paces in each sector. By adopting this approach it is possible to show that the structural economic dynamics is conditioned not only to patterns of evolving demand and diffusion of technological progress but also to the distributive features of the economy, which can give rise to different regimes of economic growth. Besides, we find it possible to determine the natural rate of profit that makes the mark-up rate to be constant over time.Post-Keynesian growth model, structural change, multi-sector models
Germany
No full textThe German team undertook from two workshops in a makerspace in Germany, and a series of workshops across two days in a UK museum. Two children aged 5 and 6took part in the first two workshops (along with two older children). Children and families who visited the museum were able to drop into the museum workshops.Across all workshops, the focus of the work was on creating Augmented Reality and Virtual Reality worlds.The only form of data collection in the German project was video and still images, therefore the majority of data cannot be shared. Only images that do not contain recognisable images of children are shared. </div
Makerspaces in the Early Years: Current Perceptions and Practices of Early Years Practitioners, Library and Museum Educators and Makerspace Staff - A Survey
No full textThe MakEY project explores the place of the rising ‘maker’ culture in the development of young children’s digital literacy and creative design skills.A survey was undertaken of early years professionals, including teachers, staff working in museums and libraries, and makerspace staff to identify what current understanding and practice is with regard to the use of makerspaces. The survey was developed by the project team and placed online using Qualtrics. The survey was translated into the languages of countries participating in the project: Danish, German, Icelandic, Norwegian and Romanian. At a later stage in the project, the survey was translated into Portuguese and Spanish, for future use. </div
