Publications de Ashley Richards Brown

The isotopic signature of U(V) during bacterial reduction

Marinella Mazzanti, Rizlan Bernier-Latmani, Margaux Camille Andréa Molinas, Radmila Faizova, Ashley Richards Brown

The two-step electron transfer during bacterial reduction of UVI to UIV is typically accompanied by mass-independent fractionation of the 238U and 235U isotopes, whereby the heavy isotope accumulates in the reduced product. However, the role of the UV inte ...

2024

Electron flux is a key determinant of uranium isotope fractionation during bacterial reduction

Rizlan Bernier-Latmani, Margaux Camille Andréa Molinas, Ashley Richards Brown

Uranium isotopic signatures in the rock record are utilized as a proxy for past redox conditions on Earth. However, these signatures display significant variability that complicates the interpretation of specific redox conditions. Using the model uranium-r ...

2023

Contribution of the nuclear field shift to kinetic uranium isotope fractionation

Rizlan Bernier-Latmani, Ashley Richards Brown

2023

Biological reduction of a U(V)-organic ligand complex

Margaux Camille Andréa Molinas, Radmila Faizova, Ashley Richards Brown

Metal-reducing microorganisms such as Shewanella oneidensis MR-1 reduce highly soluble species of hexavalent uranyl (U(VI)) to less mobile tetravalent uranium (U(IV)) compounds. The biologically mediated immobilization of U(VI) is being considered for the ...

2021

Colloidal Size and Redox State of Uranium Species in the Porewater of a Pristine Mountain Wetland

Rizlan Bernier-Latmani, Barbora Bártová, Manon Frutschi, Gabrielle Dublet, Ashley Richards Brown, Giada Chantal Zünd

Uranium (U) speciation was investigated in anoxically preserved porewater samples of a natural mountain wetland in Gola di Lago, Ticino, Switzerland. U porewater concentrations ranged from less than 1 mu g/L to tens of mu g/L, challenging the available ana ...

AMER CHEMICAL SOC2019

Systems engineering perspective to the integration of the heating and current drive system in the EU DEMO: Analysis of requirements and functions

Ashley Richards Brown

In the framework of the EUROfusion Consortium, the Work Package Heating and Current Drive (WPHCD) is undertaking the development and design of the DEMO Heating and Current Drive (HCD) system, supported by the Work Package Plant Level Systems Engineering, D ...

2018

Exploring a broad spectrum of design options for DEMO

Holger Reimerdes, Ashley Richards Brown

In the pursuit of realistically achievable design options for demonstrating fusion electricity generation and tritium self-sufficiency in a device to follow ITER, it is vital to explore as fully as possible the available design space and technology options ...

2018

DEMO design activity in Europe: Progress and updates

Minh Quang Tran, Ashley Richards Brown

This paper describes the progress of the DEMO Design Activities in Europe and particularly the work done to address critical design integration issues that affect the machine configuration and performance, the plant concept layout and the selection of syst ...

2018