1,721,001 research outputs found
Glyme electrolytes for the new generation of energy storage devices
No full textThe increasing demand of portable energy in terms of cycle life for electronic devices such as smartphones, tablets and computer or the high stability required for medical application and the high energy density for smart energy grids and electrified transport require a breakthrough in performance lower cost, safety and environmental compatibility. indeed, the conventional energy storage devices are characterized by limited specific capacity and energy density due to the intrinsically properties of the cathodic active materials i.e. LiCoO2 with specific capacity if 150 mAhg-1 and a theoretical energy density of 550 WhKg-1. therefore, the deep investigation and optimization of new classes of electrodes proposed in this work of thesis, may shed light on the possible candidates for a new generation of energy storage devices characterized by high energy density and environmental compatibility. Furthermore, one of the main topic of this work is the study of new classes of electrolytes characterized by low flammability and high ion mobility properties in order to ensure high performances and safety leve
Thermodynamic features and environmental effects in a two-states molecular device under strict electrochemical control
No full textGas-phase proton affinity of nitric acid and its esters. A mass spectrometric and ab initio study on the existence and the relative stability of two isomers of protonated ethyl nitrate.
No full textThe protonation of C2H5ONO2 has been studied in the gas phase by the joint application of mass spectrometric and ab initio theoretical methods. The MIKE and CAD spectra of (C2H5ONO2)H+ ions from various sources and their reactivity toward selected nucleophiles, investigated by FT-ICR mass spectrometry, point to the existence of two protomers, the C2H5OHNO2+ ion−dipole complex (1c) and the covalently bound C2H5ONOOH+ species (2c), and to the tendency of the latter to isomerize into 1c in the presence of neutral C2H5ONO2. The BE of NO2+ to C2H5OH, independently measured by the kinetic and the equilibrium methods, amounts to 22.2 ± 2 kcal mol-1 at 298 K, leading to a PA of C2H5ONO2 of 178.4 ± 2.6 kcal mol-1, referred to the protonation at the ethereal oxygen. The computational results at the G2(MP2) level of theory show that protomers 1c and 2c have the same stability at 298 K and that at the same temperature the 2c → 1c isomerization is characterized by a ΔG° change of ca. −3 kcal mol-1. The PA of C2H5ONO2 is computed to be 177 ± 2 kcal mol-1 at 298 K, irrespective of whether protonation occurs at the ethereal O or at the NO2 group, in excellent agreement with the experimental value. The results are discussed in connection with the general problem concerning the preferred protonation site and the PA trend along the RONO2 homologous series. It is shown that entirely different factors control the local PA of the RO and the NO2 groups
Gas-Phase Positive and Negative Ion Chemistry of Methyl Hydroperoxide.
No full textThe gas-phase ion chemistry of methyl hydroperoxide (1) was investigated by mass spectrometric and theoretical methods. The proton affinity of 1, 173.3 ± 2 kcal mol−1 measured by the FT-ICR bracketing technique and the kinetic method, is in excellent agreement with the value of 172.6 ± 2 kcal mol−1 from G2 ab initio calculations, which identify the α oxygen atom as the most basic site. Methylation of 1 by (CH3)2F+ gives a mixed population of ions methylated at both oxygen atoms. The experimental proton affinity of CH3OOCH3 is 176.2 ± 4 kcal mol−1, versus a theoretically computed value of 180.4 ± 2 kcal mol−1, the most nucleophilic site being again the α oxygen atom. Nitrosation of 1 yields a (CH3OOH·NO)+ adduct that behaves as both a nitrosating and a protonating agent. The results are discussed and compared with earlier pertinent studies
Time dependent density functional calculations on formaldeyde and its hydrated complexes
No full textPROBING GASEOUS ION-MOLECULE COMPLEXES WITH CHIRAL AGENTS: THE REACTION OF ARENIUM IONS WITH (R)-(-)-S-BUTYL CHLORIDE
No full textThe first use of a chiral reagent in the characterization of gaseous ion-neutral complexes is described. Arom. alkylation products were formed from C6DH6+ and MeC6H6+ ions reaction with (R)-(-)-sec-Bu chloride
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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