Search results for "Diss"
showing 10 items of 2500 documents
Oxygen K-shell spectroscopy of isolated progressively solvated peptide
2020
Gas-phase near-edge X-ray-absorption fine structure (NEXAFS) action spectroscopy around the oxygen K-edge and mass spectrometry were employed to probe isolated substance P (SP) molecular ions, both bare and progressively solvated with 4 and 11 water molecules. Detailed mass spectra of bare and hydrated precursors are presented for the resonant photon energy of 532 eV that corresponds to O1s --> pi(amide)* core excitation, triggering resonant Auger decay and fragmentation from the ionized radical molecular system. The fragmentation pattern of doubly protonated SP hydrated with 4 water molecules clearly shows a series of abundant doubly charged backbone fragments, as well as triply charged pr…
Dynamic Aspects of Quasi-Particle Transfer in Molecular Electronic Devices
1993
Abstract The importance of the dissipative quantum dynamics of molecular systems for possible future device applications is emphasized. The necessity to study in detail the respective quasi-particle transfer phenomena is discussed. As a specific example charge transfer in a molecular dimer and a molecular chain is investigated in order to demonstrate how the quantum dynamical features can be controlled by different intrinsic nonlinearities.
Two- and three-state conical intersections in the electron capture dissociation of disulfides: The importance of multireference calculations
2011
The SS bond cleavage produced upon electron attachment to disulfides was generally assumed to be an adiabatic process because the added electron occupies the σ*(SS) antibonding orbital. This is clearly the case in the parent HSSH compound, but not necessarily in XSSX′ derivatives, where the substituents X and X′ are different. Through the use of MS-CASPT2 calculations, we have shown that the dissociation of the SS two-center-three-electron bond in these asymmetric XSSX′ compounds requires the interaction of at least two states, in order to localize the extra electron in one of the fragments upon dissociation. This is actually the case for the CH3SSNH2 derivative, where the most favorable di…
ETD and ECD Mass Spectrometry Fragmentation for the Characterization of Protein Post Translational Modifications
2012
The introduction of electron capture dissociation (ECD) by McLafferty and co-workers, and further of electron transfer dissociation (ETD), mechanism allows gas-phase fragmentation of multiply charged protein and peptide ions upon capture of a low-energy (<1 eV) electron or electron transfer in a gas phase ion-ion chemistry. The odd-electron species then undergoes rearrangement with subsequent cleavage of N−Cα backbone. Peptide fragmentation can take place inducing the formation of cand ztype fragment ions without loss of the information on the PTM localization. The key to the success of this approach is the selection of intact protein molecular ions and its profound potential for PTM charac…
Internacionalidad de revistas académicas: Un estudio de caso con RELIE-VE
2014
Se revisa elconcepto y los criterios propuestos en la literatura para establecer que unarevista es 'internacional'. Se aplican posteriormente estos criterios alanálisis de las características de RELIEVE (la Revista ELectrónica de Investigación y EValuación Educativa). Los datos analizados permiten concluir que RELIEVE es plenamente una revista internacional.
Spin State and Ligand Dissociation in [CpCoL2] Complexes (L = PH3, H2C=CH2): A Computational Study
1999
International audience; The relative energies of [CpCoL] compounds (L = PH3, H2C=CH2) were calculated at the DFT/B3LYP level of theory. The triplet spin state was found to be favored over the singlet by between 33.0 and 21.0 kcal mol−1 for both fixed and optimized geometries. The basis set size was found to be important for the energy calculations, particularly when the energetics of ligand dissociation was examined. The role of the triplet spin state in facilitating the ligand dissociation process is discussed.
Do electrospray mass spectra of surfactants mirror their aggregation state in solution?
2011
One important feature in the gas phase chemistry of surfactants is to ascertain whether their aggregates produced by electrospray ionization reflect those formed in the starting solution. With this aim, we have performed ESI-MS, ESI-MS/MS and ER-MS spectra of bis(2-ethylhexyl)sulfosuccinate (AOTNa) solutions in different solvents, i.e. water, water/methanol, methanol and n-hexane. The results clearly indicate that, notwithstanding the strongly different aggregation state in solution (direct micelles in water and in water/methanol, molecular dispersion in methanol and reverse micelles in n-hexane) and marked effects of the solvent polarity on the total ionic current, the surfactant aggregate…
Study of the Fragmentation of D-Glucose and Alkylmonoglycosides in the Presence of Sodium Ions in an Ion-Trap Mass Spectrometer
2009
Abstract Using electrospray ion-trap mass spectrometry, the fragmentation of D-glucose and alkylmonoglycopyranosides (alkyl-GPs) was studied. In the presence of Na+, B1 and 0,2A fragmentations were observed. The alkyl-GPs also showed a 2,5Afragmentation. A cluster containing no carbon atoms and adducts of this cluster with neutral molecules were observed. Standards of alkylmonoglycofuranosides (alkyl-GFs) were not available; however, their fragmentation was studied by high-performace liquid chromatography–mass spectrometry (HPLC-MS) and HPLC-MS2 using an industrial mixture of alkylpolyglycosides. The cluster and its adducts were more easily formed by the alkyl-GPs than by the alkyl-GFs, but…
The Contingent Negative Variation – An Electrophysiological Correlate of Temporal Processing or Reference Memory?
2014
Abstract In EEG research, the contingent negative variation (CNV) is considered to be strongly related to interval timing (e.g., Macar & Vidal, 2004 ; Macar, Vidal, & Casini, 1999). However, it is discussed controversially whether certain properties of the CNV (e.g., amplitude, peak latency and resolution) directly reflect the process of temporal accumulation or rather processes related to reference memory or decision stages in temporal information processing (van Rijn et al., 2011). This present study was designed in order to investigate the relationship between CNV mean amplitude, CNV resolution, and memory processes as well as processes of temporal accumulation. The task design aimed at …
Dalle Cronache del mal d’amore al ciclo dell’Amica geniale: continuità ed evoluzione nella narrativa di Elena Ferrante
2019
The paper analyzes the whole narrative production of Elena Ferrante, emphasizing its unity and cohesion. Cohesion coexists with discontinuity: the publication of My Brilliant Friend marks an inventive turning point and reveals new strategies. But it’s even remarkable Ferrante’s predilection for a narrative in which «the flow of storytelling that despite its density manages to sweep you away».