201 research outputs found
FLUORINE SUBSTITUTION IN NEUROTRANSMITTERS: MICROWAVE SPECTROSCOPY AND MODELLING OF THE CONFORMATIONAL SPACE AND NON BONDING INTERACTIONS
No full textAuthor Institution: Dipartimento di Chimica Ciamician, Universita di Bologna, via Selmi 2,40126 Bologna, ItalyFluorine substitution in molecules is a common practice in bio-organic chemistry in order to modulate physicochemical properties and biological activity of molecules and an increasing number of drugs on the market contain fluorine, the presence of which is often of major importance to modify pharmacokinetics properties and molecular activity. The rationale for such a strategy is that fluorine is generally a stronger electron acceptor than the other halogen atoms and its size is intermediate between that of hydrogen and oxygen. We have studied two fluorinated analogs of 2-phenylethylamine (PEA), the prototype molecule for adrenergic neurotransmitters, namely: 4-Fluoro (4FPEA) and 2-Fluoro-2-phenylethylamine (2FPEA) by Molecular Beam Fourier Transform Microwave Spectroscopy in the frequency range 6-18 GHz and \textit{ab initio} calculations at the MP2/6311++G** level. The aim is to obtain information on the spatial arrangement of the ethylamine side chain and the effects of fluorination on the energy landscape. The conformational space is dominated by low energy \textit{gauche} conformations stabilized by weak interactions between the aminic hydrogens and the electron cloud of the benzene ring and \textit{anti} conformations higher in energy. In 2FPEA the presence of the fluorine atom almost duplicate the number of possible conformation with respect to 4FPEA. We observed two conformers of 4FPEA and five conformers of 2FPEA which have been classified with the guide provided by accurate \textit{ab initio} calculations. The identification of the conformational species was helped by the analysis of the quadrupole hyperfine pattern which is greatly influenced by the orientation of the amino group and acts as a fingerprint for each conformation. The orientation of the dipole moment within the principal axis frame and the order of stability of the different conformations are other independent pieces of evidence for the unambiguous assignment and identification of the conformers. The order of stability was found to be altered in both molecules with respect to the prototype PEA molecule, especially in the case of 2FPEA where we observe a stabilization of some of the \textit{anti} forms and great destabilization of some of the \textit{gauche} forms. These observations are in agreement with the results of the theoretical calculation and can be rationalized in terms of the effect of the fluorine atom on the electron density of the molecule and in particular on the electron cloud on the benzene ring
Black hole (g)Astronomy - Exploring the different flavours of accretion
No full textThe meeting has been held in Brindisi on 2-6 Sept., 2013.
The greatest challenge in black hole astrophysics lies in the attempt to unify Galactic, intermediate and supermassive black holes under the same physical scheme to gain a more profound understanding of different classes of objects. In such grand-unification models, the observed behaviours and manifestations of accreting black holes are driven by only a few fundamental parameters, such as mass, accretion rate and spin. The conference tackles the issues related to accretion physics, production of jets/winds/outflows and their time evolution by putting a particular emphasis on the role of the net accretion rate onto black holes of all sizes. We are going to explore to which extent grand-unification schemes of black hole accretion are possible and also where they possibly fail. Participants are encouraged to present theoretical and/or observational results and prospects, across the entire electromagnetic spectrum, and to discuss them in the light of grand-unification paradigms of black hole accretion
Understanding AGN evolution with large (X-ray) surveys: current constraints and prospects for eROSITA
No full textIn the past 50 years, astronomers have used X-ray surveys to tackle fundamental questions for structure formation such as: How did supermassive black holes form and grow in the nuclei of galaxies? Why are their physical properties today so tightly linked to those of their hosts? What was the impact on the surrounding structures of the copious energy release, either in radiative or mechanical form, associated to the growth of such black holes in active galactic nuclei (AGN)? I will show how state of the art observations with multi-wavelength surveys have been used to give at least partial answers to some of these questions, and discuss the current knowledge of the history of black hole accretion.
The next generation of wide-area, sensitive X-ray surveys designed to map the hot and energetic Universe will be heralded by eROSITA (extended ROentgen Survey with an Imaging Telescope Array), the core instrument on the Russian-German Spektrum-Roentgen-Gamma (SRG) mission, scheduled for launch in 2019. eROSITA will perform a deep survey of the entire X-ray sky, and will be about 30 times more sensitive than ROSAT in the soft energy band (0.5-2 keV), while in the hard band (2-8 keV) it will provide the first ever true imaging survey of the full sky. eROSITA is expected to yield a sample of around 3 million active galactic nuclei, which is bound to revolutionize our view of the evolution of supermassive black holes and their impact on the process of structure formation in the Universe.</p
The fundamental plane of black hole activity and the census of the local black holes' population
No full textValutazione della qualità dei sistemi dunosi regionali su basi vegetazionali - Realizzazione di un intervento di vegetalizzazione sulla nuova duna del sito pilota di Foce Bevano (Ravenna).
No full textIl lavoro riporta i risultati ottenuti dall'Unità di Ricerca del Dipartimento di Scienze e Tecnologie Agroambientali dell'Università di Bologna, che ha partecipato al progetto internazionale Beachmed-e finanziato dalla UE con fondi INTERREG III C.
Viene fornito un quadro sulla qualità dei sistemi dunosi della costa romagnola, valutati in base alla vegetazione presente e viene descritto in dettaglio un intervento di vegetalizzazione di una duna artificiale, costruita presso la nuova foce del torrente Bevano, area protetta appartenente al Parco regionale del Delta del Po
- …
