10,735 research outputs found

    A mechanistic study of the EC′ mechanism – the split wave in cyclic voltammetry and square wave voltammetry

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    In this paper, a detailed investigation of electrochemical reactions coupled with homogenous chemical steps using cyclic voltammetry (CV) and square wave voltammetry (SWV) was carried out to study the electrocatalytic (EC’) mechanism. In CV, parameters including scan rate, electrode material and redox reactant were investigated while in SWV, parameters including substrate concentrations and frequencies were altered to demonstrate EC’ mechanism. Mechanistic studies focused on the EC’ mechanism using L-cysteine with ferrocenecarboxylic acid and 1,1 ′-ferrocenedicarboxylic acid respectively. Voltammetric responses were recorded and under conditions of high chemical rate constant and low substrate concentration, a split wave was observed in both CV and SWV studies

    The Influence of Protonation on the Electroreduction of Bi (III) Ions in Chlorates (VII) Solutions of Different Water Activity

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    We examined the electroreduction of Bi (III) ions in chlorate (VII) solutions under varied protonation conditions of the depolariser using voltammetric and impedance methods. The results of the kinetic parameter correlation lead to the statement that the changes in the amount of chloric (VII) acid against the amount of its sodium salt in the supporting electrolytes of the low water activity have a significant influence on the rate of Bi (III) ion electroreduction. The increase of the concentration of chloric acid sodium salt, aswell as the chloric (VII) acid alone within the particular concentration of the supporting electrolyte, inhibits the process of Bi (III) ion electroreduction. It should be associated with the reorganisation of the structure of the double layer connected with the slow dehydration inhibited by ClO 4 − ions. The standard rate constants ks values with the increase of the chlorate (VII) concentrations for all the solutions examined of chlorates (VII) confirms the catalytic influence of the decrease of water activity on the process of Bi (III) ion electroreduction. The multistage process is confirmed by the non-rectilinear 1nkf=f(E) dependences

    Electrically Guided DNA Immobilization and Multiplexed DNA Detection with Nanoporous Gold Electrodes.

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    Molecular diagnostics have significantly advanced the early detection of diseases, where the electrochemical sensing of biomarkers (e.g., DNA, RNA, proteins) using multiple electrode arrays (MEAs) has shown considerable promise. Nanostructuring the electrode surface results in higher surface coverage of capture probes and more favorable orientation, as well as transport phenomena unique to nanoscale, ultimately leading to enhanced sensor performance. The central goal of this study is to investigate the influence of electrode nanostructure on electrically-guided immobilization of DNA probes for nucleic acid detection in a multiplexed format. To that end, we used nanoporous gold (np-Au) electrodes that reduced the limit of detection (LOD) for DNA targets by two orders of magnitude compared to their planar counterparts, where the LOD was further improved by an additional order of magnitude after reducing the electrode diameter. The reduced electrode diameter also made it possible to create a np-Au MEA encapsulated in a microfluidic channel. The electro-grafting reduced the necessary incubation time to immobilize DNA probes into the porous electrodes down to 10 min (25-fold reduction compared to passive immobilization) and allowed for grafting a different DNA probe sequence onto each electrode in the array. The resulting platform was successfully used for the multiplexed detection of three different biomarker genes relevant to breast cancer diagnosis

    On the use of electrochemical techniques to monitor free oxide content in molten fluoride media

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    The electrochemical behaviour of oxide ions has been studied in fluoride melts(LiF/NaF eutectic) by cyclic voltammetry, square wave voltammetry and chronopotentiometry. The purpose is to determine whether these techniques can be used for titration of free oxide ions (O2-) in molten fluorides released by lithium oxide additions. Cyclic voltammetry is shown to be unsuitable for this purpose due to oxygen bubbling disturbing the oxidation peak, while square wave voltammetry is far more appropriate because the observed signal is a well defined oxidation peak with a height proportional to the oxide content. Thus, the present work is focused on a strategy of oxide ions titration by square wave voltammetry. In addition, this work allows assessing that the electrochemical reduction of oxide ions proceeds by diffusion of these species, and the O2- diffusion coefficient is estimated by chronopotentiometry

    Boston University Concert Choir, Odi et Amo: Songs of Love and Hate, February 19, 2008

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    This is the concert program of the Boston University Concert Choir, Odi et Amo: Songs of Love and Hate performance on Tuesday, February 19, 2008 at 8:00 p.m., at Marsh Chapel, 735 Commonwealth Avenue. Works performed were "Italienische Madrigale," D'orrida selce alpina (SWV 6) and Quella damma son io (SWV 11) by Heinrich Schütz, Caro bell' idol mio (K. 562) by Wolfgang Amadeus Mozart, Sie, sie ist dahin (K. 229) by W. A. Mozart, and V'amo di core (K. 348) by W. A. Mozart, Cold Lake by Mary Montgomery Koppel, and A capella choruses from "Catulli Carmina, Ludi scaeni" by Carl Orff. Digitization for Boston University Concert Programs was supported by the Boston University Center for the Humanities Library Endowed Fund

    Final-State Phases in BB \to Baryon-Antibaryon Decays

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    The recent observation of the decay \ob \to \Lambda_c^+ \bar p suggests that related decays may soon be visible at e+ee^+ e^- colliders. It is shown how these decays can shed light on strong final-state phases and amplitudes involving the spectator quark, both of which are normally expected to be small in B decays.Comment: 14 pages, LaTeX, 2 figures, submitted to Phys. Rev. D, references and discussion of helicity amplitudes adde
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