Direct enhancement of nuclear singlet order by dynamic nuclear polarization

Hyperpolarized singlet order is available immediately after dissolution DNP, avoiding need for additional preparation steps. We demonstrate this procedure on a sample of [1,2–13C2]pyruvic aci

Riociguat treatment in patients with chronic thromboembolic pulmonary hypertension: Final safety data from the EXPERT registry

Objective: The soluble guanylate cyclase stimulator riociguat is approved for the treatment of adult patients with pulmonary arterial hypertension (PAH) and inoperable or persistent/recurrent chronic thromboembolic pulmonary hypertension (CTEPH) following Phase

Paramagnetic relaxation of nuclear singlet states

Nuclear singlet states often display lifetimes that are much longer than conventional nuclear spin relaxation times. Here we investigate the effect of dissolved paramagnetic species on the singlet relaxation of proton pairs in solution. We find a linear correlation between the singlet relaxation rate constant T(S)(-1) and the longitudinal relaxation rate constant T(1)(-1). The slope of the correlation depends on the nature of the paramagnetic relaxation agent, but typically, singlet states are between two to three times less sensitive to paramagnetic relaxation than conventional nuclear magnetization. These observations may be interpreted using a model of partially-correlated local fields acting on the nuclear sites. We explore the effect on singlet relaxation of adding a metal-ion-chelating agent to the solution. We also investigate the effect of ascorbate, which reacts with dissolved oxyge

Polarization losses from the nonadiabatic passage of hyperpolarized solutions through metallic components

From complex-mixture analysis to in vivo molecular imaging, applications of liquid-state nuclear spin hyperpolarization have expanded widely over recent years. In most cases, hyperpolarized solutions are generated ex situ and transported from the polarization instrument to the measurement device. The sample hyperpolarization usually survives this transport, since the changes in magnetic fields that are external to the sample are typically adiabatic (slow) with respect to the internal nuclear spin dynamics. The passage of polarized samples through weakly magnetic components such as stainless steel syringe needles and ferrules is not always adiabatic, which can lead to near-complete destruction of the magnetization. To avoid this effect becoming “folklore” in the field of hyperpolarized NMR, we present a systematic investigation to highlight the problem and investigate possible solutions. Experiments were carried out on: (i) dissolution-DNP-polarized [1-13C]pyruvate with NMR detection at 1.4T, and (ii) 1.5-T-polarized H2O with NMR detection at 2.5μT. We show that the degree of adiabaticity of solutions passing through metal parts is intrinsically unpredictable, likely depending on many factors such as solution flow rate, degree of remanent ferromagnetism in the metal, and nuclear spin species. However, the magnetization destruction effects can be suppressed by application of an external field on the order of 0.1–10mT

Miniature Biplanar Coils for Alkali-Metal-Vapor Magnetometry

| openaire: EC/H2020/820393/EU//macQsimal | openaire: EC/H2020/766402/EU//ZULF | openaire: EC/H2020/754510/EU//PROBIST Funding Information: The work was funded by: the European Union Horizon 2020 research and innovation programme under project macQsimal (Grant Agreement No. 820393); the Horizon H2020 Marie Skłodowska-Curie Actions projects ITN ZULF-NMR (Grant Agreement No. 766402) and PROBIST (Grant Agreement No. 754510); the Spanish MINECO project OCARINA (the PGC2018-097056-B-I00 project funded by MCIN/AEI/10.13039/501100011033/FEDER, “A way to make Europe”); the Severo Ochoa program (Grant No. SEV-2015-0522); the Generalitat de Catalunya through the CERCA program; the Agència de Gestió d’Ajuts Universitaris i de Recerca under Grant No. 2017-SGR-1354; the Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya, cofunded by the European Union Regional Development Fund within the ERDF Operational Program of Catalunya (project QuantumCat, ref. 001-P-001644); the Fundació Privada Cellex; and the Fundació Mir-Puig. M.C.D.T. acknowledges financial support through the Junior Leader Postdoctoral Fellowship Programme from the “La Caixa” Banking Foundation (project LCF/BQ/PI19/11690021). We also thank Jacques Haesler, Sylvain Karlen, and Thomas Overstolz of the Centre Suisse d’Electronique et de Microtechnique SA (CSEM) in Neuchâtel (Switzerland) for supplying the MEMS vapor cells. Publisher Copyright: © 2022 American Physical Society.Atomic spin sensors offer precision measurements using compact microfabricated packages, placing them in a competitive position for both market and research applications. The performance of these sensors, such as the dynamic range, may be enhanced through magnetic field control. In this work, we discuss the design of miniature coils for three-dimensional localized field control by direct placement around the sensor, as a flexible and compact alternative to global approaches used previously. Coils are designed on biplanar surfaces using a stream-function approach and then fabricated using standard printed-circuit techniques. Application to a laboratory-scale optically pumped magnetometer of sensitivity approximately 20fT/Hz is shown. We also demonstrate the performance of a coil set measuring 7×17×17mm3 that is optimized specifically for magnetoencephalography, where multiple sensors are operated in close proximity to one another. Characterization of the field profile using 87Rb free-induction spectroscopy andother techniques show >96% field homogeneity over the target volume of a MEMS vapor cell and a compact stray-field contour of approximately 1% at 20 mm from the center of the cell.Peer reviewe

Enzymatic reactions observed with zero- and low-field nuclear magnetic resonance

We demonstrate that enzyme-catalyzed reactions can be observed in zero- and low-field NMR experiments by combining recent advances in parahydrogen-based hyperpolarization methods with state-of-the-art magnetometry. Specifically, we investigated two model biological processes: the conversion of fumarate into malate, which is used in vivo as a marker of cell necrosis, and the conversion of pyruvate into lactate, which is the most widely studied metabolic process in hyperpolarization-enhanced imaging. In addition to this, we constructed a microfluidic zero-field NMR setup to perform experiments on microliter-scale samples of [1-13C]fumarate in a lab-on-a-chip device. Zero- to ultralow-field (ZULF) NMR has two key advantages over high-field NMR: the signals can pass through conductive materials (e.g., metals), and line broadening from sample heterogeneity is negligible. To date, the use of ZULF NMR for process monitoring has been limited to studying hydrogenation reactions. In this work, we demonstrate this emerging analytical technique for more general reaction monitoring and compare zero- vs low-field detection.</p