Search results for "Volt"
showing 10 items of 2187 documents
Electrochemical impedance spectroscopy of polyelectrolyte multilayer modified gold electrodes: influence of supporting electrolyte and temperature.
2005
Electrochemical impedance spectroscopy and cyclic voltammetry are employed to characterize poly(styrenesulfonate)/poly(allylamine hydrochloride) multilayers assembled onto cysteamine-modified gold surfaces. The influence of the supporting electrolyte and temperature on the impedance response is studied because of both its practical interest and the need to test further the capillary membrane model recently developed by Barreira et al. [J. Phys. Chem. B 2004, 108, 17973]. The results obtained are interpreted quite satisfactorily in terms of this model, thus providing additional support to its usefulness for the description of ionic transport through polyelectrolyte multilayers. It is observe…
Ion transport through polyelectrolyte multilayers under steady-state conditions
2004
Abstract The permeability of a self-assembled polyelectrolyte multilayer to small ions under the influence of an applied potential difference is studied as a function of the number of layers and the nature of the supporting electrolyte. The multilayer is described as a series of homogeneously charged membranes with alternating sign of their fixed charge. Ion transport is described on the basis of the diffusion equation and the assumption of (Donnan) electrochemical equilibrium at the boundaries between layers. The calculated steady-state current–voltage curves are found to be in good agreement with experimental linear sweep voltammograms (at low sweep rate). The permeability of polystyrenes…
Feed-in Tariffs for Grid-connected PV Systems: The Situation in the European Community
2007
Distributed generation demonstrates to be able to significantly influence the electric power system bringing considerable benefits to the quality of service and improving the energetic efficiency of the distribution network. In particular, in the last few years, distributed generation from renewable sources is considerably increased thanks to the many support policies promoted worldwide with the aim of facing the environmental issue and the problem of the permanent rise of prices of the fossil energy. In this contest the paper presents a study of the "feed-in tariffs" financing measure carried out, at present, in many European countries and responsible of the increase in these last years of…
Diacylglycerol-containing oleic acid induces increases in [Ca(2+)](i) via TRPC3/6 channels in human T-cells.
2011
Though most of the studies have focused on the effects of free fatty acids on T-cell activation, fatty acids incorporated into plasma membrane phospholipids may also affect cell signaling via diacylglycerol (DAG), generally produced by phospholipid hydrolysis. In the present study, we have synthesized a DAG-containing oleic acid and studied its implication in the modulation of calcium signaling in human Jurkat T-cells. 1-palmitoyl-2-oleoyl-sn-glycerol (POG) induced a dose-dependent increase in [Ca(2+)](i). This effect was due to the presence of oleic acid at the sn-2 position as no differences were observed between POG and 1-stearoly-2-oleoyl-sn-glycerol (SOG). However, the substitution of …
A reexamination of voltage distortion for classical carrier-based vs B-Spline modulation of three-phase Voltage Sources Inverters
2015
Voltage waveform improvement has been the object of several investigations for many years and a manifold of different solutions have been proposed to reduce the harmonic content in Voltage Source Inverters (VSI) power application. In many cases this improvements have been obtained by modifying the reference voltage modulating signal. The recent introduction of cardinal B-spline functions, used as carrier signals, has given rise to a new modulation technique whose main characteristic is a lower value of the Total Harmonic Distortion (THD). After the discussion on the B-Spline modulation principle and on its computational effort, a performance comparisons is carried out by means of Total Harm…
Web tools per promuovere l’apprendimento collaborativo nella formazione iniziale dei futuri insegnanti
2017
L’approccio flipped può risultare una valida proposta didattica in quanto promuove le forme collaborative di apprendimento. L’apprendimento collaborativo, che trova le sue radici nella teoria socioculturale e nella teoria sociocognitiva, per decenni è stato un pilastro della formazione negli USA. Attraverso il lavoro di ricerca si è voluto descrivere lo sviluppo della competenza digitale nei futuri insegnanti, promuovendo al contempo lo spirito collaborativo e la capacità di mobilitazione delle proprie risorse cognitive, emotive e creative. Si è inteso altresì osservare e rilevare il grado di collaborazione, la capacità di richiedere aiuto, l’ impegno motivato e la costanza dei futuri inseg…
Electrochemical identification of metal ions in archaeological ceramic glazes by stripping voltammetry at graphite/polyester composite electrodes
2002
The electrochemical response of metal ions in different samples of coloured ceramic tin-lead glazes attached to graphite/polyester composite electrodes is described. In addition to the ubiquous signals for lead, reductive dissolution processes are followed by anodic stripping peaks for Co, Cu, Sb, Mn, Sn and Fe, enabling the direct identification of such elements in microsamples proceeding from archaeological glazed tiles from Valencia (Spain) workshops (16th-18th century). Additional anodic and cathodic peaks corresponding to redox processes involving metal species in solution generated during stripping processes are also used. Peak potentials, Tafel plots and shape parameters are used for…
Electrochemical analysis of the alterations in copper pigments using charge transfer coefficient/peak potential diagrams. Application to microsamples…
2001
The alteration of copper pigments in art samples was studied by linear scan and cyclic voltammetry using sample-modified Elvacite 2044 film electrodes on the basis of two-dimensional diagrams of charge transfer coefficients calculated from Tafel plots of reductive dissolution processes vs. peak potential. Characteristic voltammetric peaks were obtained for pigments used in the baroque vault frescoes of the Basílica de la Virgen de los Desamparados painted by Antonio Palomino. Results obtained by voltammetric techniques were compared with those from SEM/EDX and FT-IR analysis obtaining a good agreement and leaving to an unambiguous identification of pigments used by Palomino and their altera…
Electrochemical Characterization of Egyptian Blue Pigment in Wall Paintings Using the Voltammetry of Microparticles Methodology
2013
The solid state voltammetric response of Egypt blue, Han blue and ploss blue pigments upon attachment to graphite electrodes in contact with aqueous phosphate buffer at pH 7.0 is studied by voltammetry of microparticles and scanning electrochemical microscopy. Such voltammetric responses, combined with those for synthetic specimens consisting of binary mixtures of the pigment and SiO2 or CaCO3 as well as ternary ones of CaCO3 and SiO2 mixtures allow for the identification of the pigment and the support in samples from wall paintings using different electrochemical parameters, in particular upon performing the Tafel and modified Tafel analysis of voltammetric peaks. Identification of Egypt b…
Initial Preparation and Characterization of Single Step Fabricated Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFC)
2013
In this study, facile tape casting process has been successfully carried out to fabricate an unit anode supported intermediate temperature solid oxide fuel cell (IT-SOFC) with four different layers: a composite cathode which is a mix of La0.6Sr0.4Co0.2Fe0.8O3 (LSCF48) and Gd0.1Ce0.9O1.9 (GDC10), GDC10 as thin electrolyte layer, NiO-GDC10 without pore former as thin anode functional layer (AFL), and anode support layer of NiO-GDC10 with carbon pore former. The multi-layer was sintered once to produce an unit planar cell. An OCV of 1.002 V at 500 °C, and maximum power density of 466 mW cm–2 at 648 °C are obtained. These results indicate negligible leakage of fuel through electrolyte. Furtherm…