Search results for "Volt"
showing 10 items of 2187 documents
Electrochemical Detection of High Oxidation States of Chromium( IV and V ) in Chromium‐Doped Cassiterite and Tin‐Sphene Ceramic Pigmenting Systems
2006
Solid-state electrochemistry is applied to detect the presence of chromium centres with high oxidation states in chromium-doped cassiterite and tin-sphene ceramic pigmenting systems. Voltammetric data indicate that CrV and CrIV centres with different coordinative arrangements exist in the studied materials, and yield proton-assisted reduction processes at +0.95, +0.42 AgCl/Ag in contact with 0.50 M H2SO4. Electrochemical measurements are correlated with spectroscopic data. The CrIV and CrV metal ions display a significant light-driven electrocatalytic effect on the oxidation of 1,4-dihydrobenzoquinone and Fe(CN)64– ions that involves the formation of surface-confined adducts. (© Wiley-VCH V…
Recent Approaches for Chemical Speciation and Analysis by Electrospray Ionization (ESI) Mass Spectrometry
2021
In these latest years, the chemical speciation of several species has been increasingly monitored and investigated by means of electrospray ionization mass spectrometry (ES-MS). This soft ionization technique is capable to gently take into the gas phase metal-ligand complexes and gather a wealth of information on their energetics, shape, and fragmentation pathways. For this reason, this technique is frequently chosen in a synergistic approach to investigate competitive ligand exchange-adsorptive other ways analyzed by cathodic stripping voltammetry (CLE-ACSV). ESI-MS analyses require a careful experimental design as they may be impacted by instrumental artifacts such as ESI adduct formation…
Alternating current electrogravimetry of copper electrodissolution in a sulfuric acid solution
2017
Abstract Copper electrodissolution processes have been studied by means of electrochemical impedance spectroscopy and ac-electrogravimetry (mass impedance). During ac-electrogravimetry acquisition, mass decreases or increases due to the electrodissolution or the electrodeposition of copper, respectively. As a result, this continuous mass drift makes impossible obtaining a true ac-electrogravimetry response unless a numerical correction was applied. It has been compared the electrochemical behavior of copper layers previously treated and other freshly deposited on the gold electrode of the quartz crystal microbalance. The simultaneous analysis of both impedance functions has allowed separati…
Ion motion in salt water flowing under a transverse magnetic field
2012
The problem of ion motion in an electrolyte solution flowing in a thin rectangular duct with velocity VE in the presence of a transverse magnetic field B0 is studied by means of classical mechanics and electrodynamics. Because of Lorentz force on the ions in the electrolyte solution, a so called Faraday voltage appears at the electrodes orthogonal to both the field B0 and the velocity VE. The dynamics of positive and negative ions (cations and anions, respectively) in this classical system is studied by taking into account the viscosity of the fluid and the process of charge accumulation on the opposite walls of the duct. Hydrogen production is seen to take place at one of the electrodes wh…
MOCVD growth of CdTe on glass: analysis of in situ post-growth annealing
2004
Abstract In this paper, we analyse the growth by MOCVD of CdTe on glass substrates using in situ post-growth annealing. First, in order to perform a systematic study, polycrystalline layers of CdTe were deposited by MOCVD on glass substrates. The structure and morphology of the layers was investigated as a function of different growth parameters, temperature, VI/II precursor molar ratio and substrate position on the susceptor. An activation energy of Ek=20.7 kcal/mol was obtained from the experimental data. In order to better understand the process and the effects of different growth parameters, a numerical model that simulated the gas flow in the reactor, was developed. Secondly we analyse…
Bipolar membranes under forward and reverse bias conditions. Theory vs. experiment
1994
Abstract Bipolar membranes are layered structures composed of one cation-and one anion-exchange membrane joined together in series. The current—voltage curves of two recently developed bipolar membranes have been analysed theoretically and experimentally under both forward and reverse bias conditions. The experimental trends observed are high conductivity under forward bias conditions and high impedance first, and then electric field enhanced (EFE) water dissociation for high enough applied voltages, under reverse bias conditions. The forward bias measurements can contribute to a better knowledge of some of the transport parameters entering also in the reverse biased membrane. Comparison of…
"Sweet Chemistry": a Green Way for Obtaining Selenium Nanoparticles Active against Cancer Cells
2017
We present an environment friendly synthesis of selenium nanoparticles and the study of their cytotoxic activity against uterine sarcoma cancer and fibroblasts cells. Amorphous selenium (a-SeNPs) and trigonal selenium (t-SeNPs) were synthesized using D-fructose as the reducing agent and characterized by high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction analysis (XRD), inductively coupled plasma optical emission spectrometry (ICP OES), dynamic light scattering (DLS) to obtain zeta potential values and cyclic voltammetry (CV). Particularly, a-SeNPs presented high toxicity toward the resistant cancer cell line MES-SA/…
Ricostruzione virtuale delle crociere dell'aula della chiesa di San Domenico a Cagliari (XVI sec.)
2016
Il saggio affronta la ricostruzione virtuale delle crociere dell’aula della chiesa di San Domenico a Cagliari, distrutta nel 1943 dai bombardamenti alleati che colpirono la città. La ricostruzione virtuale, combinando gli strumenti dell’indagine storica e della rappresentazione digitale, è stata impiegata per comprendere il processo costruttivo della copertura dell’aula. Lo studio ha inoltre permesso di elaborare una più corretta interpretazione dei dettagli linguistici e delle caratteristiche costruttive delle crociere, consentendo di elaborare nuove ipotesi sulla fabbrica, attraverso la comparazione con architetture coeve. This paper focuses on the 3D virtual reconstruction of the star-sh…
Life Cycle Assessment Performance Comparison of Small Solar Thermal Cooling Systems with Conventional Plants Assisted with Photovoltaics
2012
Abstract Life Cycle Assessment (LCA) allows for the consideration of energy consumption and environmental impacts associated with all the stages of a product's life, from the cradle to the grave . Starting from the results obtained in the IEA SHC Task 38 framework for the LCA of small solar assisted heat driven chillers, the application of such methodology has been extended to systems with a conventional compression chiller assisted by a photovoltaic plant. This study aims to provide a more comprehensive investigation through a comparison of these two families of solar assisted cooling systems (with solar thermal or PV), which is an important topic for studies concerning the research of eff…
Energy and economic assessment of desiccant cooling systems coupled with single glazed air and hybrid PV/thermal solar collectors for applications in…
2009
Abstract This paper presents a detailed analysis of the energy and economic performance of desiccant cooling systems (DEC) equipped with both single glazed standard air and hybrid photovoltaic/thermal (PV/t) collectors for applications in hot and humid climates. The use of ‘solar cogeneration’ by means of PV/t hybrid collectors enables the simultaneous production of electricity and heat, which can be directly used by desiccant air handling units, thereby making it possible to achieve very energy savings. The present work shows the results of detailed simulations conducted for a set of desiccant cooling systems operating without any heat storage. System performance was investigated through h…