1,721,019 research outputs found
Novel photoredox and photoinduced approaches for synthetic applications
No full textThe use of light as activation mode for organic molecules is surely one of the oldest concepts in the universe. In fact, organic photochemistry is almost as old as organic chemistry itself. However, for long time the field remained mostly unexplored, and the applications limited. Only now, with depauperate reserves of fossil fuels, a quest for more sustainable energy sources to feed our processes started. Light, omnipresent on our planet and in the universe, makes the perfect candidate as source of green energy. After more than a hundred years humanity is eventually answering the hopes of Giacomo Ciamician, that envisioned a light-driven world already in 1912. Within the context of this steadily expanding field, the aim of the present thesis was to expand the synthetic toolbox of light driven transformation available to an organic chemist. The Introduction to this thesis will deliver to the readers less acquianted with modern photochemical processes the necessary background and theoretical context for the treated arguments. Within Chapters 2-4, each project is discussed in details after a shorter state-of-the art introduction. Chapter 2 presents the results of the recent merger between isocyanide-based multicomponent reactions and visible light activation. The development of a more selective, facile and effective protocol for performing ketene multicomponent reactions is discussed. The products achieved from the multicomponent transformation were then used for the stereoselective synthesis of simplified analogues of bioactive natural compounds, discussed in the second part of the chapter.
A study aimed to the radical functionalization of olefins exploiting light induced protocols is presented in Chapter 3. Several approaches to achieve the desired functionalization are discussed, and the presented results, although yet not conclusive, represent a good leap forward towards the mild functionalization of olefin substrates. In the light of the recent Nobel prize awarded for the development of organocatalysis, I had the pleasure of working on the topic of enantioselective photoorganocatalysed processes towards the functionalization of enals. The results of my efforts are reported in Chapter 4
Wetting in the nanoscale: a continuum mechanics approach
No full textA continuum mechanics model has been developed to study the equilibrium shape of nanometric droplets on a planar solid substrate and how, in this scale, the contact angle depends on the drop size. The drop is modeled as a liquid volume enclosed in an inextensible membrane, subject to an isotropic tension (the surface tension) and to a field of surface forces including, in the proximity of the solid, the liquid-to solid interactions, envisaged as a generic potential force per unit surface directed normally to the solid surface (i.e. vertically). The only conditions required to solve the problem are those of mechanical and thermodynamic equilibrium. The predictions of the model are discussed in comparison with data on nanodrops retrieved by a special AFM device for a number of different liquid–solid systems
Background Internal Friction in Metals Interpreted as a Soret Cross-effect of Point Defect Diffusion
No full textAutostress induced by point defects in sintering phenomena: effect on mass transport and sintering stress
No full textThermally Activated Step for Densification and Creep of High-porosity MgO Compacts in the Intermediate Sintering Stage
No full textBending response of PVDF piezoelectric sensors2012 IEEE Sensors
No full textThe aim of the present work is to investigate the
response to pure bending of a piezoelectric PVDF film as a
standing-alone device. A model is proposed and experimental
results show that these polymer films enjoy this property,
opening very promising scenarios for their integration into
flexible tactile sensing system
- …
