Publications associées à Polymorphs of Theophylline Characterized by DNP Enhanced Solid-State NMR

The isotopic signature of U(V) during bacterial reduction

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

Organic matters, but inorganic matters too: column examination of elevated mercury sorption on low organic matter aquifer material using concentrations and stable isotope ratios

Lorenz Schwab

Sorption of mercury (Hg) in soils is suggested to be predominantly associated with organic matter (OM). However, there is a growing collection of research that suggests that clay minerals and oxides are also important solid phases for the sorption of solu ...

2024

Optimal sensitivity for 1H detected relayed DNP of organic solids at fast MAS

David Lyndon Emsley, Pierrick Berruyer, Saumya Badoni

Dynamic nuclear polarization (DNP) combined with high magnetic fields and fast magic angle spinning (MAS) has opened up a new avenue for the application of exceptionally sensitive 1H NMR detection schemes to study protonated solids. Recently, it has been s ...

Academic Press Inc - Elsevier Science2024

Diagenetic isotope exchange in biocalcites for paleoclimate reconstruction

Deyanira Graciela Cisneros Lazaro

The oxygen isotope compositions of fossil biocalcites, such as foraminifera, bivalves, brachiopods, and belemnites have allowed for reconstructions of sea surface and deep ocean temperatures throughout the Phanerozoic and constitute the most important reco ...

EPFL2024

Technical note: Two-component electrical-conductivity-based hydrograph separation employing an exponential mixing model (EXPECT) provides reliable high-temporal-resolution young water fraction estimates in three small Swiss catchments

Davide Canone, Jana Freiin von Freyberg

The young water fraction represents the portion of water molecules in a stream that have entered the catchment relatively recently, typically within 2-3 months. It can be reliably estimated in spatially heterogeneous and nonstationary catchments from the a ...

Copernicus Gesellschaft Mbh2024

129Xe Dynamic Nuclear Polarization Demystified: The Influence of the Glassing Matrix on the Radical Properties

Rolf Gruetter, Jean-Noël Hyacinthe, Andrea Capozzi, Thanh Phong Kevin Lê, Emma Linnea Wiström

129Xe dissolution dynamic nuclear polarization (DNP) is a controversial topic. The gold standard technique for hyperpolarized xenon magnetic resonance imaging (MRI) is spin exchange optical pumping, which received FDA approval in 2022. Nevertheless, the ve ...

2024

Magic Angle Spinning Solid-State 13C Photochemically Induced Dynamic Nuclear Polarization by a Synthetic Donor-Chromophore-Acceptor System at 9.4 T

David Lyndon Emsley, Michael Allan Hope, Máté Visegrádi, Federico De Biasi

Solid-state photochemically induced dynamic nuclear polarization (photo-CIDNP) is a nuclear magnetic resonance spectroscopy technique in which nuclear spin hyperpolarization is generated upon optical irradiation of an appropriate donor-acceptor system. Unt ...

Amer Chemical Soc2024

High power electrostatic beam splitter for a proton beamline

Hua Zhang, Mike Seidel

The High Intensity Proton Accelerator facility (HIPA) delivers a 590 MeV cw (50.6 MHz) proton beam with up to 1.4 MW beam power (2.4 mA) to spallation and meson production targets serving particle physics experiments and material research. The main acceler ...

2024

Magnetism of Single Surface Adsorbed Atoms Studied with Radio-Frequency STM

Clément Marie Soulard

This thesis investigates the magnetic properties of single atoms and molecules adsorbed on thin magnesium oxide decoupling layers, grown on a silver single crystal. To address these systems experimentally, we use a low temperature scanning tunneling micros ...

EPFL2024

Isotope Ratio - Discharge Relationships of Solutes Derived From Weathering Reactions

Paolo Benettin

To date, the vast majority of studies seeking to link discharge to solute concentrations have been based on representations of fluid age distributions in watersheds that are time-invariant. As increasingly detailed spatial and temporal datasets become avai ...

Amer Journal Science2023

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

Deuterated TEKPol Biradicals and the Spin-Diffusion Barrier in MAS DNP

Dominik Józef Kubicki, David Lyndon Emsley, Yu Rao, Amrit Venkatesh, Federico De Biasi

The sensitivity of NMR spectroscopy is considerably enhanced by dynamic nuclear polarization (DNP). In DNP polarization is transferred from unpaired electrons of a polarizing agent to nearby proton spins. In solids, this transfer is followed by the transpo ...

Wiley-VCH Verlag GmbH2023

The role of isotope mass and transport for H-mode access in tritium containing plasmas at JET with ITER-like wall

Henri Weisen, Marco Wischmeier, Mikhail Maslov, Javier García Hernández, Nicola Vianello, Haomin Sun

The required heating power, P-LH, to access the high confinement regime (H-mode) in tritium containing plasmas is investigated in JET with ITER-like wall at a toroidal magnetic field of B-t = 1.8 T and a plasma current of I-p = 1.7 MA. PLH, also referred t ...

IOP Publishing Ltd2023

Hierarchy of the Components in Spray-Dried, Protein-Excipient Particles Using DNP-Enhanced NMR Spectroscopy

David Lyndon Emsley, Baptiste Busi, Pierrick Berruyer, Andrea Bertarello

Protein-based drugs are becoming increasingly important, but there are challenges associated with their formulation (for example, formulating stable inhalable aerosols while maintaining the proper long-term stability of the protein). Determining the morpho ...

Amer Chemical Soc2023

Assessing sublimation during snow transport and sublimation effects on the isotopic composition of water vapor

Armin Sigmund

Sublimation influences the water storage in snow covers and glaciers, which is important for water use and projections of the sea level rise. Yet, it is challenging to quantify sublimation for large areas or in conditions of snow transport. In-situ measure ...

EPFL2023

NMR Crystallography in the Big Data Era: New Methods and Applications Powered by Machine Learning

Manuel Cordova

Structure determination of materials is key to understanding their physical properties. While single-crystal X-ray diffraction is the gold standard for structures displaying long-range order, many materials of interest are polycrystalline and/or disordered ...

EPFL2023

Single Chip Dynamic Nuclear Polarization Microsystems

Nergiz Sahin Solmaz

Nuclear magnetic resonance (NMR) methods are powerful tools employed in many fields, including physics, chemistry, material science, biology, and medicine. The use of NMR methodologies in an even wider range of applications is often hindered by the relativ ...

EPFL2023

Reliable uncertainties: Error correlation, rotated error bars, and linear regressions in three-isotope plots and beyond

Reto Georg Trappitsch

Correlated errors of experimental data are a common but often neglected problem in physical sciences. Various tools are provided here for thorough propagation of uncertainties in cases of correlated errors. Discussed are techniques especially applicable to ...

ELSEVIER2023

Pure Isotropic Proton NMR Spectra in Solids using Deep Learning

Manuel Cordova, David Lyndon Emsley, Pinelopi Moutzouri, Bruno Simões de Almeida, Daria Torodii

The resolution of proton solid-state NMR spectra is usually limited by broadening arising from dipolar interactions between spins. Magic-angle spinning alleviates this broadening by inducing coherent averaging. However, even the highest spinning rates expe ...

Wiley-VCH Verlag GmbH2023

Two-dimensional Pure Isotropic Proton Solid State NMR

Manuel Cordova, David Lyndon Emsley, Pinelopi Moutzouri, Bruno Simões de Almeida, Daria Torodii

One key bottleneck of solid-state NMR spectroscopy is that H-1 NMR spectra of organic solids are often very broad due to the presence of a strong network of dipolar couplings. We have recently suggested a new approach to tackle this problem. More specifica ...

Wiley-VCH Verlag GmbH2023