Publications associées à Kinetic fractionation

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

Mercury Isotope Fractionation during Dark Abiotic Reduction of Hg(II) by Dissolved, Surface-Bound, and Structural Fe(II)

Lorenz Schwab

Stable mercury (Hg) isotope ratios are an emerging tracer for biogeochemical transformations in environmental systems, but their application requires knowledge of isotopic enrichment factors for individual processes. We investigated Hg isotope fractionatio ...

Amer Chemical Soc2023

Hydrogen Peroxide Formation during Ozonation of Olefins and Phenol: Mechanistic Insights from Oxygen Isotope Signatures

Urs von Gunten, Joanna Maria Houska

Mitigation of undesired byproducts from ozonation of dissolved organic matter (DOM) such as aldehydes and ketones is currently hampered by limited knowledge of their precursors and formation pathways. Here, the stable oxygen isotope composition of H2O2 for ...

AMER CHEMICAL SOC2023

Snow-Atmosphere Humidity Exchange at the Ice Sheet Surface Alters Annual Mean Climate Signals in Ice Core Records

Sonja Wahl

Surface processes alter the water stable isotope signal of the surface snow after deposition. However, it remains an open question to which extent surface post-depositional processes should be considered when inferring past climate information from ice cor ...

Amer Geophysical Union2023

High-useful yield and new autoionizing state of resonantly ionized tungsten

Reto Georg Trappitsch

In order to measure tungsten isotopic composition in presolar stardust grains that contain a limited number of atoms, we developed a new three-photon three-color resonance ionization scheme using titanium:sapphire lasers and the Laser Ionization of Neutral ...

ROYAL SOC CHEMISTRY2022

Toward waste valorization by converting bioethanol production residues into nanoparticles and nanocomposite films

Xun Liao, Muhammad Farooq

A "waste-valorization" approach was developed to transform recalcitrant hydrolysis lignin (HL) from secondgeneration bioethanol production into multifunctional bio-based products. The hydrolysis lignin (HL) was extracted with aqueous acetone, yielding two ...

ELSEVIER2021

Technical note: Evaluation of a low-cost evaporation protection method for portable water samplers

Jana Freiin von Freyberg

Automated field sampling of streamwater or precipitation for subsequent analysis of stable water isotopes (H-2 and O-18) is often conducted with off-the-shelf automated samplers. However, when water samples are stored in the field for days and weeks in ope ...

2020

Quantum kinetic energy and isotope fractionation in aqueous ionic solutions

Michele Ceriotti, Lu Wang

At room temperature, the quantum contribution to the kinetic energy of a water molecule exceeds the classical contribution by an order of magnitude. The quantum kinetic energy (QKE) of a water molecule is modulated by its local chemical environment and lea ...

ROYAL SOC CHEMISTRY2020

Non-crystalline tetravalent uranium species in the subsurface: formation and stability

Luca Loreggian

Uranium (U) contamination of ground and surface waters poses an acute hazard on the ecosystem and human health. Since the discovery of microbial U(VI) reduction, U bioremediation has been explored as a promising and cost-effective method compared to tradit ...

EPFL2019

Control of the hydrogen:deuterium isotope mixture using pellets in JET

Olivier Sauter, Ambrogio Fasoli, Yiming Li, Basil Duval, Jonathan Graves, Duccio Testa, Patrick Blanchard, Federico Alberto Alfredo Felici, Henri Weisen, Alessandro Pau, Federico Nespoli, Hamish William Patten, Cristian Sommariva, Antoine Pierre Emmanuel Alexis Merle, Samuel Lanthaler, Haomin Sun, Michele Marin, Richard Pitts, Yann Camenen, Jan Horacek, Javier García Hernández, Marco Wischmeier, Nicola Vianello, Mikhail Maslov, Yao Zhou, Davide Galassi, Antonio José Pereira de Figueiredo, Emiliano Fable, Francesca Maria Poli, Daniele Brunetti, Anna Teplukhina, Alberto Mariani, Kenji Tanaka, Bernhard Sieglin, Otto Asunta, Gergely Papp, Leonardo Pigatto

Deuterium pellets are injected into an initially pure hydrogen H-mode plasma in order to control the hydrogen: deuterium (H:D) isotope mixture. The pellets are deposited in the outer 20% of the minor radius, similar to that expected in ITER, creating trans ...

2019

Ideas and perspectives: Tracing terrestrial ecosystem water fluxes using hydrogen and oxygen stable isotopes - challenges and opportunities from an interdisciplinary perspective

Paolo Benettin, Natalie Claire Ceperley, Jana Freiin von Freyberg

In this commentary, we summarize and build upon discussions that emerged during the workshop "Isotope-based studies of water partitioning and plant-soil interactions in forested and agricultural environments" held in San Casciano in Val di Pesa, Italy, in ...

Copernicus GmbH2018

Correlated TEM-NanoSIMS investigation of foraminiferal metabolism

Charlotte Madeleine Nicole Lekieffre

Foraminifera are ubiquitous eukaryotic protists inhabiting all types of marine environments. The chemical and isotopic compositions of their carbonate tests are commonly used as proxies for paleo-environmental conditions. However, while foraminifera repres ...

EPFL2017

Kinetic isotope effects and how to describe them

Jiri Vanicek, Konstantin Karandashev

We review several methods for computing kinetic isotope effects in chemical reactions including semiclassical and quantum instanton theory. These methods describe both the quantization of vibrational modes as well as tunneling and are applied to the ⋅H + H ...

2017

Reduction and immobilization of uranium in the subsurface : controls, mechanisms, and implications for in situ bioremediation

Malgorzata Alicja Stylo

Decades of uranium (U) mining, milling and military use left a legacy of U contamination around the world. The radioactivity and chemical toxicity of U at contaminated sites pose an acute and long-term hazard to human health and the surrounding environment ...

EPFL2015

Copper isotope evidence for large-scale sulphide fractionation during Earth’s differentiation

James Badro

The differentiation of Earth into a metallic core and silicate mantle left its signature on the chemical and isotopic composition of the bulk silicate Earth (BSE). This is seen in the depletion of siderophile (metal-loving) relative to lithophile (rock-lov ...

2015

Silicon isotopes in angrites and volatile loss in planetesimals

James Badro

Inner solar system bodies, including the Earth, Moon, and asteroids, are depleted in volatile elements relative to chondrites. Hypotheses for this volatile element depletion include condensation from the solar nebula and volatile loss during energetic impa ...

National Academy of Sciences2014

Isotope Effects as New Proxies for Organic Pollutant Transformation

Stephanie Spahr

Assessing the pathways and rates of organic pollutant transformation in the environment is a major challenge due to co-occurring transport and degradation processes. Measuring changes of stable isotope ratios (e.g. C-13/C-12, H-2/H-1, N-15/N-14) in individ ...

Swiss Chemical Soc2014

First day of an oil spill on the open sea: Early mass transfers of hydrocarbons to air and water

Jeremy Samuel Arey, Jonas Gros, Deedar Nabi

During the first hours after release of petroleum at sea, crude oil hydrocarbons partition rapidly into air and water. However limited information is available about very early evaporation and dissolution processes. We report on the composition of the oil ...

Amer Chemical Soc2014

Volatilization induced by impacts recorded in Zn isotope composition of ureilites

Philippe Gillet, Pierre Beck

Ureilites are ultramafic achondrites formed by igneous processes early in the history of the Solar System. Ureilites are heavily depleted in volatile elements, probably by evaporation at the surface of the ureilite parent body: however the moderately volat ...

2010

Three applications of path integrals: equilibrium and kinetic isotope effects, and the temperature dependence of the rate constant of the [1,5] sigmatropic hydrogen shift in (Z)-1,3-pentadiene

Jiri Vanicek, Tomas Zimmermann

Recent experiments have confirmed the importance of nuclear quantum effects even in large biomolecules at physiological temperature. Here we describe how the path integral formalism can be used to describe rigorously the nuclear quantum effects on equilibr ...

Springer Verlag2010