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The direct and unambiguous detection and identification of individual metabolite molecules present in complex biological mixtures constitute a major challenge in (bio)analytical research. In this context, nuclear magnetic resonance (NMR) spectroscopy has proven to be particularly powerful owing to its ability to provide both qualitative and quantitative atomic-level information on multiple analytes simultaneously in a noninvasive manner. Nevertheless, NMR suffers from a low inherent sensitivity and, moreover, lacks selectivity regarding the number of individual analytes to be studied in a mixture of a myriad of structurally and chemically very different molecules, e.g., metabolites in a biofluid. Here, we describe a method that circumvents these shortcomings via performing selective, photochemically induced dynamic nuclear polarization (photo-CIDNP) enhanced NMR spectroscopy on unmodified complex biological mixtures, i.e., human urine and serum, which yields a single, background-free one-dimensional NMR spectrum. In doing this, we demonstrate that photo-CIDNP experiments on unmodified complex mixtures of biological origin are feasible, can be performed straightforwardly in the native aqueous medium at physiological metabolite concentrations, and act as a spectral filter, facilitating the analysis of NMR spectra of complex biofluids. Due to its noninvasive nature, the method is fully compatible with state-of-the-art metabolomic protocols providing direct spectroscopic information on a small, carefully selected subset of clinically relevant metabolites. We anticipate that this approach, which, in addition, can be combined with existing high-throughput/high-sensitivity NMR methodology, holds great promise for further in-depth studies and development for use in metabolomics and many other areas of analytical research.

Needs for neutron detection and monitoring in high neutron flux environments are increasing in several different fields. A completely solid-state, current mode bolometric detector is constructed as a solid substrate transition edge sensor based on a high-T[Formula: see text] superconducting meander. The detector consists of four individual pixels of which three pixels include [Formula: see text] neutron absorption layers. The absorbed energy per neutron absorption reaction is modelled and compared to experimental data. The response of the tested detector is directly correlated to a cold neutron beam with a flux of [Formula: see text] modulated by a slit. The signal is found to be an order of magnitude higher than the thermal background. The dynamics described by the temporal saturation constants is governed by a modulation frequency less than [Formula: see text]. The thermal response is dynamic and never fully saturates for [Formula: see text] exposures. The efficiency for this proof-of-principle design is 1-2%. Possibilities for optimization are identified, that will increase the efficiency to become comparable to existing solid boron-10 detectors. The existing detectors with event-based read-out have limited functionality in high flux environments. The superconducting bolometer described in this work using current-mode readout will pave the way for high flux applications., (© 2023. The Author(s).)

Liquid plays an important role in bone that has a complex 3D hierarchical pore structure. However, liquid (water) is difficult to discern from e.g. an organic matrix by X-ray imaging. Therefore, we use a correlative approach using both high resolution X-ray and neutron imaging. Human femoral bone with liquid adsorbed into some of the pores was imaged with both the Neutron Microscope at the ICON beamline, SINQ at PSI, and by lab-based μCT using 2.7 μm voxel size. Segmentation of the two datasets showed that, even though the liquid was clearly distinguishable in the neutron data and not in the X-ray data, it remained challenging to segment it from bone due to overlaps of peaks in the gray level histograms. In consequence, segmentations from X-ray and neutron data varied significantly. To address this issue, the segmented X-ray porosities was overlaid on the neutron data, making it possible to localize the liquid in the vascular porosities of the bone sample and use the neutron attenuation to identify it as H 2 O. The contrast in the neutron images was lowered slightly between the bone and the liquid compared to the bone and the air. This correlative study shows that the complementary use of X-rays and neutrons is very favorable, since H 2 O is very distinct in the neutron data, while D 2 O, H 2 O, and organic matter can barely be distinguished from air in the X-ray data., Competing Interests: Declaration of competing interest None., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

A systematic study has been carried out to investigate the neutron transmission signal as a function of sample tem-per-ature. In particular, the experimentally de-ter-mined wavelength-dependent neutron attenuation spectra for a martensitic steel at tem-per-atures ranging from 21 to 700°C are com-pared with simulated data. A theoretical description that includes the Debye-Waller factor in order to describe the tem-per-ature influence on the neutron cross sections was im-plemented in the nxsPlotter software and used for the simulations. The analysis of the attenuation coefficients at varying tem-per-atures shows that the missing contributions due to elastic and inelastic scattering can be clearly distinguished: while the elastically scattered intensities decrease with higher tem-per-atures, the inelastically scattered intensities increase, and the two can be separated from each other by analysing unique sharp features in the form of Bragg edges. This study presents the first systematic approach to qu-antify this effect and can serve as a basis , for example, to correct measurements taken during in situ heat treatments, in many cases being a prerequisite for obtaining qu-anti-fiable results., (© Al-Falahat et al. 2022.)