2,704 research outputs found
The Classics of the First Lorenzo de' Medici. For a New Critical Reading of Corinth
No full textopenIl presente lavoro si propone di rileggere una delle prime opere di Lorenzo de’ Medici, "Corinto", attraverso temi letterari che lo caratterizzano, tenendo presente i modelli latini, greci e italiani ai quali l’autore attinge e confrontandone altri, pertinenti ai temi analizzati. Dopo una rapida introduzione sul contesto storico in cui il poemetto si inserisce, esso viene presentato per quanto concerne il contenuto e la storia redazionale, approfondita nell’Appendice, dove si presentano inoltre i testi di riferimento. Segue dunque la nuova lettura critica. La riflessione sul concetto di classico e su Lorenzo quale autore e personaggio del poemetto conclude l’analisi.The present work aims to re-read one of Lorenzo de’ Medici’s first works, "Corinto", through the literary themes which characterize it, keeping in mind the Latin, Greek and Italian models on which the author draws and comparing others, pertinent to the themes analyzed. After a quick introduction to the historical context in which the poem fits, it is presented in terms of content and editorial history, detailed in the Appendix, where the reference texts are also presented. Thus follows the new critical reading. The reflection on the concept of classic and on Lorenzo as author and character of the poem concludes the analysis
Photofragmentation spectra of halogenated methanes in the VUV photon energy range
No full textIn this paper an investigation of the photofragmentation of dihalomethanes CH2X2 (X = F, Cl, Br, I) and chlorinated methanes (CHnCl4-n with n = 0-3) with VUV helium, neon, and argon discharge lamps is reported and the role played by the different halogen atoms is discussed. Halogenated methanes are a class of molecules used in several fields of chemistry and the study of their physical and chemical proprieties is of fundamental interest. In particular their photodissociation and photoionization are of great importance since the decomposition of these compounds in the atmosphere strongly affects the environment. The results of the present work show that the halogen-loss is the predominant fragmentation channel for these molecules in the VUV photon energy range and confirm their role as reservoir of chlorine, bromine, and iodine atoms in the atmosphere. Moreover, the results highlight the peculiar feature of CH2F2 as a source of both fluorine and hydrogen atoms and the characteristic formation of I-2(+) and CH2+ ions from the photofragmentation of the CH2I2 molecule
Photofragmentation spectra of halogenated methanes in the VUV photon energy range: the role of halogen atom
No full textBreve, E Succinto Racconto Del Viaggio, solenne Entrate, & ossequiosi Vasallaggi ... dell'Augustissimo Imperatore Leopoldo ... Principato Nel Mese di Giugno, e finito d'Ottobre L'Anno 1660 ... / Per opera, e studio di Lorenzo De Churelichz Araldo di Sua Maestà Cesarea
No full textDynamics of ion-molecule reactions of SO2.+with H2O and CH4
No full textThe reaction dynamics and the temperature-dependent kinetic trend of the SO2.+ion-molecule reactions with water and methane have been studied using the tunable synchrotron radiation to produce excited SO2.+ions and ab-initio methods. The experimental results show that only one product, HSO2+, is formed in both reactions and its yield displays different trends with the photon energy. DFT and VTST calculations have been used to explore the dynamics of the reactions and to calculate the rate constants at different temperatures
HSO2+ formation from ion-molecule reactions of SO2+ with water and methane: two fast reactions with reverse temperature-dependent kinetic trend
No full textIn this work an experimental and theoretical study on the formation of HSO2 + ion from the SO2 ⋅++CH4 and SO2 ⋅++H2O ion–molecule reactions at different temperatures is reported. Tunable synchrotron radiation was used to produce the SO2 ⋅+ ion in excited ro-vibrational levels of the ionic ground state X2A1 and mass spectrometry was employed to identify the product ions. Calculations in the frame of the density functional theory and variational transition state theory were combined to explore the dynamics of the reactions. The experimental results show that HSO2 + is the only product in both reactions. Its yield decreases monotonically with photon energy in the SO2 ⋅++H2O reaction, while it decreases at first and then increases in the SO2 ⋅++CH4 reaction. Theory confirms this trend by calculating the rate constants at different temperatures and explains the results by means of the polar, spin and charge effects as well as structural reorganization occurring in the reaction coordinate. The dynamic behavior observed in these two reactions is of general and fundamental interest. It can also provide some insights on the role of these reactions in astrochemistry as well as in their use as models for bond-activation reactions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei
Temporary anion states of pyrimidine and halopyrimidines
No full textThe empty-level electronic structures of pyrimidine and its 2-chloro, 2-bromo and 5-bromo derivatives have been studied with electron transmission spectroscopy (ETS) and dissociative electron attachment spectroscopy (DEAS) in the 0-5 eV energy range. The spectral features are assigned to the corresponding anion states with the support of theoretical calculations at the ab initio and density functional theory levels. The empty orbital energies supplied by simple Koopmans’ theorem calculations, scaled with empirical equations, reproduce quantitatively the energies of vertical electron attachment to pi* and sigma* empty orbitals measured in the ET spectra and predict a vertical electron affinity close to zero for the three halo derivatives.
The total anion currents of the halo derivatives, measured at the walls of the collision chamber as a function of the impact electron energy, present intense maxima below 0.5 eV. The mass-selected spectra show that in this energy range the total anion current is essentially due to halide fragment anions. The DEA cross-section of the bromo derivatives is about six times larger than that of the chloro derivative. The absolute cross-sections at incident electron energy close to zero are evaluated to be 10 -16-10 -15 cm2
First person – Alba Delrio-Lorenzo
No full textFirst Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Alba Delrio-Lorenzo is first author on ‘Sarcoplasmic reticulum Ca2+ decreases with age and correlates with the decline in muscle function in Drosophila’, published in JCS. Alba is a PhD student in the lab of Javier García-Sancho and María Teresa Alonso at the Instituto de Biología y Genética Molecular (IBGM), University of Valladolid, Spain, investigating the molecular mechanisms implicated in aging, particularly muscle aging.Peer reviewe
A Synchrotron Radiation Study of Nitroimidazoles and their Derivatives
No full textNitroimidazole derived molecules are used in radiotherapy thanks to their capability to sensitize hypoxic tumor cells to radiation by ‘mimicking’ the effects of the presence of oxygen as a damaging agent. Inthis work we present the results of a bottom-up approach, which goes from the model molecule to the real drugs used in therapy. Mass spectrometry and several spectroscopic techniques (XPS, PES, NEXAFS, PEPICO) basedon the use of synchrotron radiation have been combined with computational methods to link the electronic and geometric structure of the molecule to their functions.The investigation of the fragmentation patterns of the nitroimidazole isomers [1,2] has allowed to understand their capacity to produce reactive molecular species like nitric oxide, carbon monoxide or hydrogencyanide and their potential impact on the biological system. Guided by these results, the fragmentation mechanisms of metronidazole and misonidazole, the two radiosensitisers built on the 5-nitroimidazole and 2-nitroimidazole compounds used in therapy, as well as the 1-Methyl-5-nitroimidazole have been investigated. The results on these more complex systems suggest that different mechanisms are active. The release of nitric oxideis hampered by the efficient formation of nitrous acid or nitrogen dioxide and the long and branched tails attached to the imidazole ring increase the ring stability, providing an efficient channel for excess energy dissipation
Photoionization of methanol: a molecular source for the prebiotic chemistry
No full textMethanol is one of the most abundant and ubiquitous molecules in the space. Its chemistry is fundamental to
understand the molecular growing from prebiotic molecules, ions and radicals. In this work the reaction of
labelled methanol CD3OH•+ radical cation, produced with different internal energies by monochromatic synchrotron
radiation, with neutral CD3OH was studied. The dynamics of the main reaction channels were investigated
by theoretical calculations. The results show how these processes can be considered suitable pathways for
the formation of fundamental species as CH3O(H)H+, CH3O•, •CH2OH, CH2O which are potential precursors to
prebiotic molecules
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