Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

The detection methods and generation mechanisms of the intrinsic reactive oxygen species (ROS), i.e., superoxide anion radical (•O2–), hydrogen peroxide (H2O2), singlet oxygen (1O2), and hydroxyl radical (•OH) in photocatalysis, were surveyed comprehensively. Consequently, the major photocatalyst used in heterogeneous photocatalytic systems was found to be TiO2. However, besides TiO2 some representative photocatalysts were also involved in the discussion. Among the various issues we focused on the detection methods and generation reactions of ROS in the aqueous suspensions of photocatalysts. On the careful account of the experimental results presented so far, we proposed the following apprehension: adsorbed •OH could be regarded as trapped holes, which are involved in a rapid adsorption–desorption equilibrium at the TiO2–solution interface. Because the equilibrium shifts to the adsorption side, trapped holes must be actually the dominant oxidation species whereas •OH in solution would exert the reactivity...

Generation and Detection of Reactive Oxygen Species in Photocatalysis

Theoretical and experimental studies of multiple nucleation

This article provides an up-to-date perspective on the use of anion-exchange membranes in fuel cells, electrolysers, redox flow batteries, reverse electrodialysis cells, and bioelectrochemical systems (e.g. microbial fuel cells). The aim is to highlight key concepts, misconceptions, the current state-of-the-art, technological and scientific limitations, and the future challenges (research priorities) related to the use of anion-exchange membranes in these energy technologies. All the references that the authors deemed relevant, and were available on the web by the manuscript submission date (30th April 2014), are included.

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Anion-exchange membranes in electrochemical energy systems

Superoxide ion (O2•–) is of great significance as a radical species implicated in diverse chemical and biological systems. However, the chemistry knowledge of O2•– is rather scarce. In addition, numerous studies on O2•– were conducted within the latter half of the 20th century. Therefore, the current advancement in technology and instrumentation will certainly provide better insights into mechanisms and products of O2•– reactions and thus will result in new findings. This review emphasizes the state-of-the-art research on O2•– so as to enable researchers to venture into future research. It comprises the main characteristics of O2•– followed by generation methods. The reaction types of O2•– are reviewed, and its potential applications including the destruction of hazardous chemicals, synthesis of organic compounds, and many other applications are highlighted. The O2•– environmental chemistry is also discussed. The detection methods of O2•– are categorized and elaborated. Special attention is given to the f...

Superoxide Ion: Generation and Chemical Implications

Electrochemical oxidation of nickel in alkaline solutions: a voltammetric study and modelling

In the present work, we focus on the surface charge properties of well-defined maghemite (γ-Fe2O3) nanoparticles dispersed in water. Because of the acidic properties of surface groups, the nanoparticles' surface can be positively or negatively charged depending on the pH. Consequently, there are electrostatic repulsion forces between particles that allow stabilizing the suspensions in water. Acid−base titrations of the surface groups starting from acidic, alkaline, and neutral pH are performed to access the dependence of the surface charge density with the pH. Titrations are followed by potentiometric and conductometric measurements. Simultaneous zetametry measurements by acoustophoresis are implemented. The experimental curves are analyzed using several hypotheses; in particular, we assume that the sites on the surface of the particles behave as weak diacids. The interpretation of the experimental determinations of the charge implies taking into account an electrostatic term due to the potential develope...

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Surface Charge Density of Maghemite Nanoparticles: Role of Electrostatics in the Proton Exchange

Electrogeneration and some properties of the superoxide ion in aqueous solutions

Adsorption of diethylether on single-crystal gold electrodes

A high sensitivity multiple waveform voltammetric method and instrument are provided for use in electrochemical and other applications. The method consists of applying one or several variable potential excitation signals between electrodes of an electrochemical cell to produce an electrochemical reaction in the solution. The excitation signals include a DC bias potential increasing cyclically by a potential step to form a potential staircase signal sweeping across a potential domain, and a number of pulse trains either of opposite polarity or shifted in potential per potential step. An electric current derived from a diffusion flux of ions through the solution is measured as a result of the applied excitation signal. The instrument is adapted to perform the method, and is provided with an accurate and low noise signal generator circuit, a circuit for reducing a double layer capacitive effect in the cell, a potentiostat having a virtual mass counter electrode, a feedback circuit for compensating an ohmic drop in the cell, and an integrator circuit for integrating the current signal produced by the cell.

Jean Chevalet

Papers

Electrochemical oxidation of nickel in alkaline solutions: a voltammetric study and modelling

Surface Charge Density of Maghemite Nanoparticles: Role of Electrostatics in the Proton Exchange

Electrogeneration and some properties of the superoxide ion in aqueous solutions

Adsorption of diethylether on single-crystal gold electrodes

High sensitivity multiple waveform voltammetric instrument