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The XENONnT experiment is a low-background dual phase liquid xenon Time Projection Chamber (TPC) with 5.9 tonnes of instrumented liquid xenon. Improved liquid xenon purification and radon distillation system along with various background mitigation strategies brought the Electronic Recoil (ER) backgrounds down to an unprecedented low of (15.8 ± 1.3) events/(keV tonne years) below recoil energies of 30 keV. Exploring three different ER datasets spanning 10 to 140 keV collected using the XENON1T and XENONnT detector, a search for a signal of sub-GeV Dark Matter boosted by reflection off the sun is conducted. No excess is observed, and novel stringent upper limits on the Dark Matter-electron scattering cross section in the Dark Matter mass range between 5 keV and 9 MeV are reported.

The question of what generates conscious experience has mesmerized thinkers since the dawn of humanity, yet its origins remain a mystery. The topic of consciousness has gained traction in recent years, thanks to the development of large language models that now arguably pass the Turing test, an operational test for intelligence. However, intelligence and consciousness are not related in obvious ways, as anyone who suffers from a bad toothache can attest-pain generates intense feelings and absorbs all our conscious awareness, yet nothing particularly intelligent is going on. In the hard sciences, this topic is frequently met with skepticism because, to date, no protocol to measure the content or intensity of conscious experiences in an observer-independent manner has been agreed upon. Here, we present a novel proposal: Conscious experience arises whenever a quantum mechanical superposition forms. Our proposal has several implications: First, it suggests that the structure of the superposition determines the qualia of the experience. Second, quantum entanglement naturally solves the binding problem, ensuring the unity of phenomenal experience. Finally, a moment of agency may coincide with the formation of a superposition state. We outline a research program to experimentally test our conjecture via a sequence of quantum biology experiments. Applying these ideas opens up the possibility of expanding human conscious experience through brain-quantum computer interfaces.

We investigated the charge state distributions and energy loss of single and double-charged Xenon ions (20-220 keV) passing through graphene, Quantifoil, and 10 nm thick carbon membranes. Utilizing simultaneous carbon recoil detection on the graphene-containing sample, we determined the areal density of carbon equivalent to 3 monolayers of graphene, indicating only slight contamination by e.g. PMMA, of our exiting surfaces. The charge state distributions revealed notable proportions of higher charge states, up to Xe+5 at higher energies, with mean charge states consistently below 1. The observed exponential decrease in higher charge fractions suggests electron stripping processes play a significant role. Differences in mean charge states are found among the three systems studied.

Anaesthesia and surgery are associated with significant cognitive sequelae which can be devastating, particularly in older adults. The mechanisms that underly neural injury following anaesthesia and surgery, the ability of anaesthetic agents to protect against injury and the mechanisms underlying general anaesthesia itself remain unresolved. Xenon gas has been utilised as a general anaesthetic agent for over 70 years. There is an abundance of pre-clinical literature identifying that xenon provides protection against neural injury for a wide range of neurological insults, including those associated with anaesthesia and surgery. In contrast, the results of randomised controlled trials in humans have not identified improved cognitive outcomes for patients who receive xenon general anaesthesia. The aim of this thesis was to improve our understanding of the mechanisms underlying xenon’s anaesthetic and neuroprotective effects. We first conducted a systematic review of the cellular mechanisms of xenon. We then utilized neural injury biomarkers, electroencephalogram analysis and computational modelling of neurons in a clinical and volunteer cohort receiving xenon anaesthesia to address gaps in our understanding of how xenon provides anaesthesia and neuroprotection. We identified that xenon alters the activity of a unique range of cellular targets, some of which are more commonly associated with propofol and volatile anaesthetics. We found that when utilised for a minor surgical procedure, xenon anaesthesia did not reduce the release of neural injury biomarkers when compared to conventional anaesthesia. We identified that the electroencephalogram features of xenon are unique and distinguishable from propofol and volatile anaesthesia as well as ketamine and nitrous oxide anaesthesia. We found that a commonly utilised monitor of awareness during anaesthesia significantly overestimated the ‘anaesthetic depth’ of individuals receiving xenon anaesthesia during emergence. Finally

The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.

The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.

Today's VQA models still tend to capture superficial linguistic correlations in the training set and fail to generalize to the test set with different QA distributions. To reduce these language biases, recent VQA works introduce an auxiliary question-only model to regularize the training of targeted VQA model, and achieve dominating performance on diagnostic benchmarks for out-of-distribution testing. However, due to the complex model design, ensemble-based methods are unable to equip themselves with two indispensable characteristics of an ideal VQA model: 1) Visual-explainable: The model should rely on the right visual regions when making decisions. 2) Question-sensitive: The model should be sensitive to the linguistic variations in questions. To this end, we propose a novel model-agnostic Counterfactual Samples Synthesizing and Training (CSST) strategy. After training with CSST, VQA models are forced to focus on all critical objects and words, which significantly improves both visual-explainable and question-sensitive abilities. Specifically, CSST is composed of two parts: Counterfactual Samples Synthesizing (CSS) and Counterfactual Samples Training (CST). CSS generates counterfactual samples by carefully masking critical objects in images or words in questions and assigning pseudo ground-truth answers. CST not only trains the VQA models with both complementary samples to predict respective ground-truth answers, but also urges the VQA models to further distinguish the original samples and superficially similar counterfactual ones. To facilitate the CST training, we propose two variants of supervised contrastive loss for VQA, and design an effective positive and negative sample selection mechanism based on CSS. Extensive experiments have shown the effectiveness of CSST. Particularly, by building on top of model LMH+SAR [1], [2], we achieve record-breaking performance on all out-of-distribution benchmarks ( e.g. , VQA-CP v2, VQA-CP v1, and GQA-OOD).

Searches for Weakly Interacting Massive Particles (WIMPs) carried out by liquid xenon time projection chambers (TPCs) require a careful accounting of all background sources. Because WIMPs are a leading dark matter candidate, their possible existence is of great interest to particle physicists, astrophysicists, and cosmologists. The LUX-ZEPLIN (LZ) detector has completed an initial science run finding no evidence for WIMP scattering events. The data excludes scattering cross sections above 6.5x10$^{-48}$ cm$^{2}$ for a WIMP mass of 30 GeV/c$^{2}$. Background contributions from the beta decay of dispersed \isotope[85]{Kr} were reduced prior to the initial science run using charcoal chromatography to remove trace krypton. Over 10 tonnes of xenon were processed, and a custom mass spectrometry system measured a final mass averaged krypton concentration of 123 $\pm$ 22 parts-per-quadrillion (ppq) $\frac{gram}{gram}$ $\frac{ \isotope[nat]{Kr} }{\isotope[nat]{Xe}}$. A delayed coincidence $\beta$ - $\gamma$ search was also conducted to identify rare decays from \isotope[85]{Kr} in the LZ WIMP search data. The 11.0 $\pm$ 4.0 identified events are equivalent to a concentration of 183 $\pm$ 67 ppq. The total background contribution from \isotope[85]{Kr} to the WIMP search region of interest is 30 $ \pm $ 11 electron recoil events.

We report on a blinded analysis of low-energy electronic recoil data from the first science run of the XENONnT dark matter experiment. Novel subsystems and the increased 5.9 ton liquid xenon target reduced the background in the (1, 30) keV search region to (15.8±1.3) events/(ton×year×keV), the lowest ever achieved in a dark matter detector and ∼5 times lower than in XENON1T. With an exposure of 1.16 ton-years, we observe no excess above background and set stringent new limits on solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter.

The theory of one-photon ionization and two-photon above-threshold ionization is formulated for applications to heavy atoms in attosecond science by using Dirac–Fock formalism. A direct comparison of Wigner–Smith–Eisenbud delays for photoionization is made with delays from the Reconstruction of Attosecond Beating By Interference of Two-photon Transitions (RABBIT) method. Photoionization by an attosecond pulse train, consisting of monochromatic fields in the extreme ultraviolet range, is computed with many-body effects at the level of the relativistic random phase approximation (RRPA). Subsequent absorption and emission processes of infrared laser photons in RABBIT are evaluated by using static ionic potentials as well as asymptotic properties of relativistic Coulomb functions. As expected, light elements, such as argon, show negligible relativistic effects, whereas heavier elements, such a krypton and xenon, exhibit delays that depend on the fine-structure of the ionic target. The relativistic effects are notably close to ionization thresholds and Cooper minima with differences in fine-structure delays predicted to be as large as tens of attoseconds. The separability of relativistic RABBIT delays into a Wigner–Smith–Eisenbud delay and a universal continuum–continuum delay is studied with reasonable separability found for photoelectrons emitted along the laser polarization axis in agreement with prior non-relativistic results.

Delayed single- and few-electron emissions plague dual-phase time projection chambers, limiting their potential to search for light-mass dark matter. This paper examines the origins of these events in the XENON1T experiment. Characterization of the intensity of delayed electron backgrounds shows that the resulting emissions are correlated, in time and position, with high-energy events and can effectively be vetoed. In this work we extend previous S2-only analyses down to a single electron. From this analysis, after removing the correlated backgrounds, we observe rates <30 events/(electron×kg×day) in the region of interest spanning 1 to 5 electrons. We derive 90% confidence upper limits for dark matter-electron scattering, first direct limits on the electric dipole, magnetic dipole, and anapole interactions, and bosonic dark matter models, where we exclude new parameter space for dark photons and solar dark photons.

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Broadley, M., Byrne, D., Ardoin, L., Almayrac, M., Bekaert, D., & Marty, B. High precision noble gas measurements of hydrothermal quartz reveal variable loss rate of Xe from the Archean atmosphere. Earth and Planetary Science Letters, 588, (2022): 117577, https://doi.org/10.1016/j.epsl.2022.117577., Determining the composition of the Archean atmosphere and oceans is vital to understanding the environmental conditions that existed on the surface of the early Earth. The analysis of atmospheric remnants in fluid inclusions trapped in Archean-aged samples has shown that the Xe isotopic signature of the Archean atmosphere progressively evolved via mass-dependent fractionation, arriving at a modern atmospheric composition around the Archean-Proterozoic transition. The mechanisms driving this evolution are however not well constrained, and it is not yet clear whether the evolution proceeded continuously or via episodic bursts. Providing further constraints on the evolution of Xe in the Archean atmosphere is hampered by the limited amounts of atmospheric gas trapped within fluid inclusions during mineral formation, which impacts the precision at which the Archean atmosphere can be determined. Here, we develop a new crush-and-accumulate extraction technique that enables the heavy noble gases (Ar, Kr and Xe) released from crushing large quantities of hydrothermal quartz to be accumulated and analysed to a higher precision than was previously possible. Using this new technique, we re-evaluate the composition of atmospheric gases trapped within fluid inclusions of 3.3 Ga quartz samples from Barberton, South Africa. We find that the Xe isotopic signature is fractionated by +10.3 ± 1.0‰u−1 (2 SE) relative to modern atmosphere, which is within uncertainty of, but slightly lower than, the previous determination of 12.9 ± 2.4‰u−1 for this sample (Avice et al., 2017). We show for the first time that the Kr/Xe ratio measured within Archean quartz samples is enriched in Xe compared to the modern atmosphere, demonstrating that the atmosphere has lost Xe since the Archean. This further reinforces the proposal of atmospheric escape as the primary mechanism for Earth's Xe loss. We further show that the atmospheric Kr/Xe and Xe isotope fractionation recorded in the Barberton quartz at, This study was supported by the European Research Council (PHOTONIS project, grant agreement No. 695618). This is CRPG contribution #2820.

source:https://www.iaea.org/publications/12222/atomic-and-plasma-material-interaction-data, identifier:0000-0001-7544-1773

In this dissertation, we present several recent developments in instrumentation for dark matter detectors. The liquid/gas two-phase xenon time projection chamber is well-established as an excellent technology to search for Weakly Interacting Massive Particles (WIMPs). We present analyses of data from the Large Underground Xenon (LUX) and Particle Identification in Xenon at Yale (PIXeY) experiments, in which we study signal vs. background discrimination as a function of detector parameters. This informs design decisions for current and future xenon detectors. Then, we focus on cutting-edge calorimetric technologies geared towards searches at the MeV/c^2 scale. We present measurements of the superconducting transition of several materials, and we discuss their potential use as transition-edge sensors (TES). Helium as a detection target with TES signal readout is explored, and its sensitivity to dark matter-induced nuclear recoils is calculated.

The dual-phase xenon time projection chamber (TPC) is a powerful tool for direct-detection experiments searching for WIMP dark matter, other dark matter models, and neutrinoless double-beta decay. Successful operation of such a TPC is critically dependent on the ability to hold high electric fields in the bulk liquid, across the liquid surface, and in the gas. Careful design and construction of the electrodes used to establish these fields is therefore required. We present the design and production of the LUX-ZEPLIN (LZ) experiment's high-voltage electrodes, a set of four woven mesh wire grids. Grid design drivers are discussed, with emphasis placed on design of the electron extraction region. We follow this with a description of the grid production process and a discussion of steps taken to validate the LZ grids prior to integration into the TPC.

The mantle is Earth’s largest reservoir as it constitutes 80% of its volume, and the chemical composition and structure of the mantle can provide constraints on the formation and evolution processes of the Earth. The geochemistry of rocks derived from the mantle are extensively utilized to elucidate the nature of the mantle. For example, the lithophile element geochemistry of oceanic basalts portray a heterogeneous, geochemically layered mantle that is extensively altered by crust formation and subduction processes. However, the story as told by the lithophile elements provide only a partial history of the Earth as the volatile elements behave distinctly from the refractory elements. The noble gases are excellent tools for constraining mantle evolution processes due to their inert nature, low abundance, and ubiquitous presence in all mantle and surface components. Furthermore, as the solar system volatile reservoirs contains uniquely identifying “fingerprints” of noble gas isotopic ratios, the precise measurements of the noble gases in the mantle can provide clues as to which building blocks contributed to the formation of the Earth. However, despite the utility of the noble gases, there are several challenges that hinder the precise determination of the mantle noble gas isotopic ratios, such as atmospheric contamination, low sample abundance, and difficulties in cryogenic separation of the noble gases for mass spectrometric measurements. The chapters in this dissertation report on the successful measurement of the noble gas data of mantle derived mid-ocean ridge basalts (MORBs) collected from the Mid-Atlantic Ridge (MAR) and provides insight into the origin, evolution, and heterogeneity of the volatiles in the mantle.Chapter 1 presents He, Ne, Ar, and Xe data determined from the depleted MORBs (D-MORBs) collected along the MAR between the Kane and Atlantis fracture zones from 24-30 °N. iii D-MORBs are likely representative of the depleted mantle, more so than E-MOR

Determining the composition of the Archean atmosphere and oceans is vital to understanding the environmental conditions that existed on the surface of the early Earth. The analysis of atmospheric remnants in fluid inclusions trapped in Archean-aged samples has shown that the Xe isotopic signature of the Archean atmosphere progressively evolved via mass-dependent fractionation, arriving at a modern atmospheric composition around the Archean-Proterozoic transition. The mechanisms driving this evolution are however not well constrained, and it is not yet clear whether the evolution proceeded continuously or via episodic bursts. Providing further constraints on the evolution of Xe in the Archean atmosphere is hampered by the limited amounts of atmospheric gas trapped within fluid inclusions during mineral formation, which impacts the precision at which the Archean atmosphere can be determined. Here, we develop a new crush-and-accumulate extraction technique that enables the heavy noble gases (Ar, Kr and Xe) released from crushing large quantities of hydrothermal quartz to be accumulated and analysed to a higher precision than was previously possible. Using this new technique, we re-evaluate the composition of atmospheric gases trapped within fluid inclusions of 3.3 Ga quartz samples from Barberton, South Africa. We find that the Xe isotopic signature is fractionated by +10.3 ± 1.0‰u−1 (2 SE) relative to modern atmosphere, which is within uncertainty of, but slightly lower than, the previous determination of 12.9 ± 2.4‰u−1 for this sample (Avice et al. 2017). We show for the first time that the Kr/Xe ratio measured within Archean quartz samples is enriched in Xe compared to the modern atmosphere, demonstrating that the atmosphere has lost Xe since the Archean. This further reinforces the proposal of atmospheric escape as the primary mechanism for Earth's Xe loss. We further show that the atmospheric Kr/Xe and Xe isotope fractionation recorded in the Barberton quartz at 3, SCOPUS: ar.j, info:eu-repo/semantics/published

The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.

ObjectivesProlonged survival of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on environmental surfaces and personal protective equipment may lead to these surfaces transmitting this pathogen to others. We sought to determine the effectiveness of a pulsed-xenon ultraviolet (PX-UV) disinfection system in reducing the load of SARS-CoV-2 on hard surfaces and N95 respirators.MethodsChamber slides and N95 respirator material were directly inoculated with SARS-CoV-2 and were exposed to different durations of PX-UV.ResultsFor hard surfaces, disinfection for 1, 2, and 5 minutes resulted in 3.53 log10, >4.54 log10, and >4.12 log10 reductions in viral load, respectively. For N95 respirators, disinfection for 5 minutes resulted in >4.79 log10 reduction in viral load. PX-UV significantly reduced SARS-CoV-2 on hard surfaces and N95 respirators.ConclusionWith the potential to rapidly disinfectant environmental surfaces and N95 respirators, PX-UV devices are a promising technology to reduce environmental and personal protective equipment bioburden and to enhance both healthcare worker and patient safety by reducing the risk of exposure to SARS-CoV-2.

This article discusses the development of an automated and robotic gamma-ray spectrometric complex for use in decommissioning nuclear physics installations, as well as in monitoring the radiation situation of radiation spent fuel storage facilities. The special physical and technical characteristics of the xenon gamma-ray spectrometer are presented, which can be expediently used as a recording device for gamma radiation of various types of radioisotopes, including radioactive control of the surrounding territory of objects dealing with the operation of nuclear physics installations.

Capture and storage of the long-lived 85Kr is an efficient approach to mitigate the emission of volatile radionuclides from the spent nuclear fuel reprocessing facilities. However, it is challenging to separate krypton (Kr) from xenon (Xe) because of the chemical inertness and similar physical properties. Herein we prepared high-silica CHA zeolite membranes with ultra-high selectivity and irradiation stability for Kr/Xe separation. The suitable aperture size and rigid framework endures the membrane a strong size-exclusion effect. The ultrahigh selectivity of 51–152 together with the Kr permeance of 0.7–1.3×10−8 mol m−2 s−1 Pa−1 of high-silica CHA zeolite membranes far surpass the state-of-the-art polymeric membranes. The membrane is among the most stable polycrystalline membranes for separation of humid Kr/Xe mixtures. Together with the excellent irradiation stability, high-silica CHA zeolite membranes pave the way to separate radioactive Kr from Xe for a notable reduction of the volatile nuclear waste storage volume., ChemE/Catalysis Engineering

A fully functioning Comprehensive nuclear-Test-Ban Treaty (CTBT) is essential for a world free of nuclear weapons. To measure radionuclides in the atmosphere in accordance with the CTBT, facilities such as SAUNA uses double coincidence techniques to discriminate between interesting Xenon isotopes. In this paper, a Monte-Carlo code (open source) based on first principles simulating a radionuclide detector has been built to investigate the viability of triple coincidence methods for measurements of $^{131m}$Xe, $^{133m}$Xe, $^{133}$Xe and $^{135}$Xe and found that by measuring $\beta - $ Ce $-$ X-ray coincides in $^{133}$Xe and $^{135}$Xe one could seperate the 30 keV photon energy region of interest by as much as $42.9 \pm 26.8$ keV and $214 \pm 50.8$ keV away from the original electron $-$ photon energy axes measured in SAUNA, using concentrations of Xenon isotopes typical for a nuclear weapons test one day after testing. The conclusion is that triple coincidence is a viable method for nuclear weapons detection in light of double coincidence methods, if only considering this theoretical approach. No conclusions on the practicality of triple coincidence methods in a CTBT could be drawn from these results.

Values on cumulative fission yields for the Xenon isotopes 131Xe, 131mXe, 133Xe, 133mXe, 135Xe and 135mXe were compiled from the nuclear data libraries ENDF/B-VIII.0, GEFY-8.1, JEFF-3.3 and JENDL-4.0, partly available via the Nuclear Data Services of the the International Atomic Energy Agency. This dataset lists the collected values and their uncertainties as reported.

Fluids, especially liquid crystals, enclosed in porous materials exhibit a rich phase behaviour which can be exploited in both the study of the fundamental properties of the fluid itself, as well as its confinement. Nuclear magnetic resonance spectroscopy of xenon dissolved in the confined fluid is a sensitive and noninvasive method to study these systems. The purpose of this thesis is to develop and validate computational methods which can be used to interpret, as well as predict the structure and ¹²⁹Xe NMR of the fluid. The work used a combination of classical simulations of coarse-grained molecular models with quantum-chemical parameterisation for the pairwise-additive potential energies and the ¹²⁹Xe nuclear shielding tensors. More specifically, Monte Carlo molecular simulation was used to study the structure and phase behaviour of a uniaxial liquid crystal in a cylindrical nanocavity. Next, a small number of xenon atoms was added to the simulation and the nuclear shielding of ¹²⁹Xe was computed from the simulated configurations. Finally, the factors contributing to the maximum of the chemical shift of ¹²⁹Xe in water were studied with a semianalytical cavity model, which was parameterised using a combination of molecular dynamics simulations and quantum-chemical calculations. It was found that planar anchoring of liquid-crystal molecules at the walls of a cylindrical cavity promotes orientational order well above the isotropic-nematic phase transition temperature and the sharp isotropic-nematic transition of the bulk liquid crystal is replaced by a gradual paranematic-nematic transition. At lower temperatures the formation of translationally ordered phases is hindered by the packing of molecules at the wall. The ¹²⁹Xe shielding computed from the simulations corresponds qualitatively to earlier experimental results for xenon dissolved in a liquid crystal enclosed in the small cavities of controlled pore glass. The gradual change of orientational order at

Ventilation is inhomogeneous in the lungs across species. It has been hypothesized that ventilation inhomogeneity is largely determined by the design of the airway branching network. Because exchange of gases at the alveolar barrier is more efficient when gas concentrations are evenly distributed at subacinar length scales, it is assumed that a ‘functional unit’ of ventilation exists within the lung periphery, where gas concentration becomes uniform. On the other hand, because the morphology of pulmonary airways and alveoli, and the distribution of inhaled fluorescent particles show self-similar fractal properties over a wide range of length scales, it has been predicted that fractal dimension of ventilation approaches unity within an internally homogeneous functional unit of ventilation. However, the existence of such a functional unit has never been demonstrated experimentally due to lack of in situ gas concentration measurements of sufficient spatial resolution in the periphery of a complex bifurcating network. Here, using energy-subtractive synchrotron radiation tomography, we measured the distribution of an inert gas (Xe) in the in vivo rabbit lung during Xe wash-in breathing manoeuvres. The effects of convective flow rate, diffusion and cardiac motion were also assessed. Fractal analysis of resulting gas concentration and tissue density maps revealed that fractal dimension was always smaller for Xe than for tissue density, and that only for the gas, a length scale existed where fractal dimension approached unity. The length scale where this occurred was seen to correspond to that of a rabbit acinus, the terminal structure comprising only alveolated airways. Key points: Gas ventilation is inhomogeneous in the lung of many species. However, it is not known down to what length scales this inhomogeneity persists. It is generally assumed that ventilation becomes homogeneous at subacinar length scales, beyond the spatial resolution of commonly available im, SCOPUS: ar.j, DecretOANoAutActif, info:eu-repo/semantics/published

Xenon is a rare noble gas that was introduced into clinical practice more than 70 years ago. Xenon's clinical properties are predicated by its ability to fit into preformed cavities of macromolecules thereby altering their biological functions. One such action targets the NMDA-subtype of the glutamate receptors thereby inhibiting its excitatory action. As the glutamate receptors are pivotal for both anesthesia and acute neurological injury, its clinical use has included both general anesthesia as well as neuroprotection. In this manuscript, the efficacy and safety of xenon in clinical trials that address both the anesthetic and neuroprotective applications are discussed. Because of the clinical safety of this chemically inert monatomic gas, the lack of an alternative for neuroprotection, and encouraging phase 2 trial data, a multinational pivotal randomized clinical trial (XePOHCAS) has been launched to assess the utility of xenon for patients that have been successfully resuscitated following an out of hospital cardiac arrest but still remain comatose, indicating ongoing neurological ischemic-perfusion injury. If successful, the trial will herald a new era of treatments for previously intractable conditions such as traumatic brain injury, ischemic and hemorrhagic strokes, and anesthetic-induced developmental neurotoxicity.

Interaction between p-cresol and xenon was studied by Raman spectroscopy. The main questions are crystal structure of resulting clathrate and its stability. The most informative regions of our spectra are those related to the O-H stretching vibrations, the aromatic ring vibrations between 900 and 800 cm⁻¹ and the lattice vibrations of the host. From obtained data and their analysis we confirmed formation of hexagonal rings of [···O-H⋯O-]₆ hydrogen bonds as the main structural motif of the clathrate cages and we estimated length of the O⋯O bridges of these bonds. We found evidence that the last factor is responsible for low stability of studied complex and for higher stability of similar clathrates formed by hydroquinone.

© 2020 Elsevier B.V. We used Monte Carlo simulation with canonical and grand canonical ensembles to investigate the structure of the adsorbate and the hysteresis in the isotherm for xenon adsorption in a closed-end graphitic wedge pore at temperatures below the simulated bulk triple point of 159 K. The simulation results are compared with those of the corresponding open-end wedge to reveal the interesting behaviours in the presence of the closed end. We found that when the apex angle is less than a critical angle hysteresis occurs because of the ordering of the adsorbate. This is due to the enhancement in the solid-fluid interactions that induces the adsorbate into a sequence of domains of ordered layers, separated by smaller disordered junctions, and each domain has its own characteristic temperature above which it becomes disordered. The difference in the pressure at which the ordered domain forms during adsorption and that at which the evaporation occurs upon desorption is the microscopic reason behind the hysteresis, and we can view the alternate domain/junction as the solid-like structure of the adsorbate in the mesoscopic scale. However, as the adsorbate progresses further away from the apex, it becomes disordered with a clear interface separating the adsorbate and the bulk gas, and it is found that the functional form of the Cohan equation can be used to relate the radius of curvature of the interface to the bulk pressure. Through this equation we have found that the adsorbate is denser than the supercooled liquid, and yet is not as structured as the bulk solid for temperatures below the bulk triple point temperature.

To cope with the foreseen demand for tungsten-based TESs in the current and future phases of the CRESST experiment, we investigated the possibility to implement a reliable, simple and reproducible fabrication method using sputtering. In this contribution, we present the method under development for tungsten deposition using conventional magnetron sputtering with xenon as sputtering gas. TESs with transition temperatures (Tc) down to 15 mK have been obtained with transition widths smaller than 1 mK. We also give a first assessment on the reproducibility of the process and present the potential for tuning of the Tc.

Genetically encoded (GE) contrast agents detectable by magnetic resonance imaging (MRI) enable non-invasive visualization of gene expression and cell proliferation at virtually unlimited penetration depths. Using hyperpolarized Xe-129 in combination with chemical exchange saturation transfer, an MR contrast approach known as hyper-CEST, enables ultrasensitive protein detection and biomolecular imaging. GE MRI contrast agents developed to date include nanoscale proteinaceous gas vesicles as well as the monomeric bacterial proteins TEM-1 beta-lactamase (bla) and maltose binding protein (MBP). To improve understanding of hyper-CEST NMR with proteins, structural and computational studies were performed to further characterize the Xe-bla interaction. X-ray crystallography validated the location of a high-occupancy Xe binding site predicted by MD simulations, and mutagenesis experiments confirmed this Xe site as the origin of the observed CEST contrast. Structural studies and MD simulations with representative bla mutants offered additional insight regarding the relationship between local protein structure and CEST contrast., QC 20190305

Xenon possesses some, but not all, of the clinical features of an ideal anesthetic agent. Besides well-known advantages of rapid awakening, stable hemodynamics and lack of biotransformation, preclinical data lead to the expectation of xenon's advantageous use for settings of acute ongoing brain injury; a single randomized clinical trial using an imaging biomarker for assessing brain injury corroborated xenon's preclinical efficacy in protecting the brain from further injury. In this review, we discuss the mechanisms and hence the putative applications of xenon for brain protection in neurosurgery. Although the expense of this rare monoatomic gas will likely prevent its widespread penetration into routine clinical neurosurgical practice, we draw attention to the theoretical benefits of xenon anesthesia over other anesthetic regimens for awake craniotomy and for neurosurgery in older, high-risk, and sicker patients.

The development of sensitive and chemically selective MRI contrast agents is imperative for the early detection and diagnosis of many diseases. Conventional responsive contrast agents used in 1 H MRI are impaired by the high abundance of protons in the body. 129 Xe hyperCEST NMR/MRI comprises a highly sensitive complement to traditional 1 H MRI because of its ability to report specific chemical environments. To date, the scope of responsive 129 Xe NMR contrast agents lacks breadth in the specific detection of small molecules, which are often important markers of disease. Herein, we report the synthesis and characterization of a rotaxane-based 129 Xe hyperCEST NMR contrast agent that can be turned on in response to H2 O2 , which is upregulated in several disease states. Added H2 O2 was detected by 129 Xe hyperCEST NMR spectroscopy in the low micromolar range, as well as H2 O2 produced by HEK 293T cells activated with tumor necrosis factor.

A cyclic hexapeptide with three pyridyl moieties connected to its backbone forms a hydrogen-bonded dimer, which tightly encapsulates a single xenon atom, like a pearl in its shell. The dimer imprints its shape and symmetry to the captured xenon atom, as demonstrated by 129Xe NMR spectroscopy, single-crystal X-ray diffraction, and computational studies. The dimers self-assemble hierarchically into tubular structures to form a porous supramolecular architecture, whose cavities are filled by small molecules and gases.

[EN] Conceived to host 5 kg of xenón at a pressure of 15 bar in the ¿ducial volume,the NEXTWhite (NEW)apparatus is currently the largest high pressure xenon gas TPC using electroluminescent ampli¿cation in the world. It is also a 1:2 scale model of the NEXT-100 detector scheduled to start searching for ßß0¿ decays in 136Xe in 2019. Both detectors measure the energy of the event using a plane of photomultipliers located behind a transparent cathode. They can also reconstruct the trajectories of charged tracks in the dense gas of the TPC with the help of a plane of silicon photomultipliers located behind the anode. A sophisticated gas system, common to both detectors, allows the high gas purity needed to guarantee a long electron lifetime. NEXT-White has been operating since October 2017 at the Canfranc Underground Laboratory (LSC), in Spain. This paper describes the detector and associated infrastructures.

The Large Underground Xenon (LUX) experiment operates at the Sanford Underground Research Facility to detect nuclear recoils from the hypothetical Weakly Interacting Massive Particles (WIMPs) on a liquid xenon target. Liquid xenon typically contains trace amounts of the noble radioactive isotopes 85Kr and 39Ar that are not removed by the in situ gas purification system. The decays of these isotopes at concentrations typical of research-grade xenon would be a dominant background for a WIMP search experiment. To remove these impurities from the liquid xenon, a chromatographic separation system based on adsorption on activated charcoal was built. 400 kg of xenon was processed, reducing the average concentration of krypton from 130 ppb to 3.5 ppt as measured by a cold-trap assisted mass spectroscopy system. A 50 kg batch spiked to 0.001 g/g of krypton was processed twice and reduced to an upper limit of 0.2 ppt.

BACKGROUND:Postoperative delirium occurs frequently in elderly hip fracture surgery patients and is associated with poorer overall outcomes. Because xenon anaesthesia has neuroprotective properties, we evaluated its effect on the incidence of delirium and other outcomes after hip fracture surgery. METHODS:This was a phase II, multicentre, randomized, double-blind, parallel-group, controlled clinical trial conducted in hospitals in six European countries (September 2010 to October 2014). Elderly (≥75yr-old) and mentally functional hip fracture patients were randomly assigned 1:1 to receive either xenon- or sevoflurane-based general anaesthesia during surgery. The primary outcome was postoperative delirium diagnosed through postoperative day 4. Secondary outcomes were delirium diagnosed anytime after surgery, postoperative sequential organ failure assessment (SOFA) scores, and adverse events (AEs). RESULTS:Of 256 enrolled patients, 124 were treated with xenon and 132 with sevoflurane. The incidence of delirium with xenon (9.7% [95% CI: 4.5 -14.9]) or with sevoflurane (13.6% [95% CI: 7.8 -19.5]) were not significantly different (P=0.33). Overall SOFA scores were significantly lower with xenon (least-squares mean difference: -0.33 [95% CI: -0.60 to -0.06]; P=0.017). For xenon and sevoflurane, the incidence of serious AEs and fatal AEs was 8.0% vs 15.9% (P=0.05) and 0% vs 3.8% (P=0.06), respectively. CONCLUSIONS:Xenon anaesthesia did not significantly reduce the incidence of postoperative delirium after hip fracture surgery. Nevertheless, exploratory observations concerning postoperative SOFA-scores, serious AEs, and deaths warrant further study of the potential benefits of xenon anaesthesia in elderly hip fracture surgery patients. CLINICAL TRIAL REGISTRATION:EudraCT 2009-017153-35; ClinicalTrials.gov NCT01199276.

In this work we investigate the level of theory necessary for reproducing the non-linear variation of the 129Xe nuclear magnetic resonance (NMR) chemical shift with the density of Xe in supercritical conditions. In detail we study how the 129Xe chemical shift depends under these conditions on electron correlation, relativistic and many-body effects. The latter are included using a sequential-QM/MM methodology, in which a classical MD simulation is performed first and the chemical shift is then obtained as an average of quantum calculations of 250 MD snapshots conformations carried out for Xen clusters (n =2-8 depending on the density). The analysis of the relativistic effects is made at the level of 4-component Hartree-Fock calculations (4c-HF) and electron correlation effects are considered using second order Møller-Plesset perturbation theory (MP2). To simplify the calculations of the relativistic and electron correlation effects we adopted an additive scheme, where the calculations on the Xen clusters are carried out at the non-relativistic Hartree-Fock (HF) level, while electron correlation and relativistic corrections are added for all the pairs of Xe atoms in the clusters. Using this approach we obtain very good agreement with the experimental data, showing that the chemical shift of 129Xe in supercritical conditions is very well described by cluster calculations at the HF level, with small contributions from relativistic and electron correlation effects.

The Fukushima accident emphasized the fact that ways to monitor in real time the evolution of a nuclear reactor during a severe accident remain to be developed. No fission products were monitored during twelve days; only dose rates were measured, which is not sufficient to carry out an online diagnosis of the event. The first measurements were announced with little reliability for low volatile fission products. In order to improve the safety of nuclear plants and minimize the industrial, ecological and health consequences of a severe accident, it is necessary to develop new reliable measurement systems, operating at the earliest and closest to the emission source of fission products. Through the French program ANR « Projet d'Investissement d'Avenir ,the aim of the DECA-PF project (diagnosis of core degradation from fission products measurements) is to monitor in real time the release of the major fission products (krypton, xenon, gaseous forms of iodine and ruthenium) outside the nuclear reactor containment. These products are released at different times during a nuclear accident and at different states of the nuclear core degradation. Thus, monitoring these fission products gives information on the situation inside the containment and helps to apply the Severe Accident Management procedures. Analytical techniques have been proposed and evaluated. The results are discussed here., SCOPUS: cp.p, info:eu-repo/semantics/published

A multiple increase in the atom mobility in metastable supersaturated (quenched from 850 °C) Fe-8.16 at % Mn solid solution is detected at temperatures less than 250°C under irradiation with 5-keV Ar+ and Xe+ ions of different masses. The irradiation-induced atom redistribution in the entire volume of foils 30 μm thick at a projected Ar+ and Xe+ ion ranges as much as 20-30 nm only is found and studied by the transmission Mössbauer spectroscopy. Long-range effects at low irradiation doses and anomalously low temperatures are attributed to "radiation shaking" of metastable media with post-cascade solitary waves in contrast to thermally stimulated radiation-enhanced processes in the narrow nanoscale near-surface layers of the alloy. It has been shown that heavier Xe+ ions at higher irradiation doses have a stronger impact on the solid solution than Ar+ ions.