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During cardiopulmonary resuscitation, pulmonary vasoconstriction due to hypoxia and hypercarbia restricts blood flow from the right to the left heart, resulting in reduced cardiac output that further inhibits adequate oxygenation and the ability to distribute oxygenated blood and medications. An inhaled pulmonary vasodilator could attenuate vasoconstriction and, therefore, increase cardiac output. We used rat isolated lungs to test if inhaled Argon leads to pulmonary vasodilation in phenylephrine-treated lungs. Lungs of 13 adult male Sprague–Dawley rats were isolated, ventilated, and perfused. Pulmonary artery and left atrium were cannulated and lungs perfused at constant flow with 4% albumin physiological saline solution. Controls (n = 6) were ventilated with 65% N2, 5% CO2, 30% O2, and Argon lungs (n = 7) with 65% Argon, 5% CO2, and 30% O2. Pulmonary mean arterial pressure (pMAP) and airway pressure (AWP) were recorded continuously, and pulmonary vascular resistance (PVR) was calculated. Following baseline readings, phenylephrine, a pulmonary vasoconstrictor, was perfused at increasing concentrations from 10−7 to 10−3 mol/L every 5 min. Statistics: Student's t test, α = 0.05. Argon led to significantly lower pMAPs and PVRs, independent of AWP. Thus, it significantly dilated pre-constricted pulmonary vessels in an ex vivo lung model. When given during resuscitation, this might aid to increase cardiac output. [ABSTRACT FROM AUTHOR]

This study explores the estimation of solubility-induced elemental fractionation of noble gases in hydrocarbon-based oils through existing empirical and theoretical models, complemented by a novel molecular simulation-based approach. Quantifying such fractionation is essential for a deeper understanding of fluid processes and migration in subsurface geological resources, an area currently lacking in experimental data. To address this, the research introduces a predictive model that employs the Peng-Robinson equation of state and a fugacity-coefficient-based method to assess noble gas elemental fractionation in hydrocarbons, including normal alkanes, cycloalkanes, and aromatics. However, this model struggles with precise quantitative predictions, prompting the introduction of adjusted cross-interaction parameters to enhance its performance. Furthermore, molecular simulations, in conjunction with the refined equation of state, are shown to offer a novel method for calculating noble gas fractionation coefficients across different hydrocarbon solvents. A key finding is the identification of a universal master curve, demonstrating that noble gas solubility fractionation at low pressure in simple hydrocarbon solvents can be quantitatively determined by temperature and density alone, without the need for detailed compositional information. Consequently, a new correlation is proposed for deriving elemental fractionation coefficients based solely on oil temperature and density, offering significant improvements over existing empirical methods for a wide range of temperatures. Although limitations are noted when applying this approach to oils rich in complex heavy components like resins and asphaltenes, it allows to address inconsistencies observed in traditionally used experimental correlations at high temperatures. [ABSTRACT FROM AUTHOR]

The noble gas argon is one of the most promising neuroprotective agents for hypoxic-reperfusion injuries of the brain. However, its effect on traumatic injuries has been insufficiently studied. The aim of this study was to analyze the effect of the triple inhalation of the argon-oxygen mixture Ar 70%/O2 30% on physical and neurological recovery and the degree of brain damage after traumatic brain injury and to investigate the possible molecular mechanisms of the neuroprotective effect. The experiments were performed in male Wistar rats. A controlled brain injury model was used to investigate the effects of argon treatment and the underlying molecular mechanisms. The results of the study showed that animals with craniocerebral injuries that were treated with argon inhalation exhibited better physical recovery rates, better neurological status, and less brain damage. Argon treatment significantly reduced the expression of the proinflammatory markers TNFα and CD68 caused by TBI, increased the expression of phosphorylated protein kinase B (pAKT), and promoted the expression of the transcription factor Nrf2 in intact animals. Treatment with an argon-oxygen breathing mixture after traumatic brain injury has a neuroprotective effect by suppressing the inflammatory response and activating the antioxidant and anti-ischemic system. [ABSTRACT FROM AUTHOR]

The colourless, odourless and monoatomic gas, helium, is considered as the second most abundant element in the universe after hydrogen. Helium is classified as a noble gas and it is the lightest noble gas. Noble gases including helium, although extremely inert chemically, display a remarkable spectrum of clinically useful biological properties. Medically, helium's applications range from respiratory care, where it facilitates easier breathing through heliox mixtures, to cardiology and neurology, where it offers cardioprotection and neuroprotection during ischemia/reperfusion injuries. [ABSTRACT FROM AUTHOR]

Aiming at understanding the source of the fluids that mineralizing within seismically active fault zones, we investigate the noble gas isotopes (i.e., helium (He), neon (Ne), and argon (Ar)) in the fluid inclusions (FIs) trapped in the calcite veins sampled along high‐angle fault zones of the Contursi hydrothermal basin, southern Italy. The latter basin lies in close vicinity of the MW = 6.9, 1980 Irpinia earthquake and exposes numerous fault scarps dissecting Mesozoic shallow‐water carbonates. The analyses of noble gases (He, Ne, Ar) are conducted to identify the origin of the volatiles circulating along the faults at the time of calcite precipitation. Then, outcomes of this discussions are compared with currently outgassing of deep‐sourced CO2 coupled to mantle‐derived He in that area, whose output is larger than those from some volcanic areas worldwide. The results indicate that He in FIs is dominated by a crustal radiogenic component (4He), and by an up to 20% of a mantle‐derived component (3He), with a highest isotopic signature of 1.38 Ra. This value is consistent with the highest percentage of mantle‐derived He associated to high‐flux CO2 gas emission in the investigated area (1.41 Ra). We propose that the variability of the He isotopic signature measured in primary FIs can result from early trapping of fluid inclusions or post trapping processes and seismic activity that modify the pristine He isotopic signature (i.e., derived from the crust and/or mantle) in groundwater along the faults during periods of background seismicity. Such investigations are fundamental to understand fluid migration in fault systems and the role of fluids in processes of earthquake nucleation. Key Points: Paleofluids in the studied seismogenic fault derive from the mixing between crustal and mantle (∼20%) derived fluidsThe variability of the He isotopic signature registered in fluid inclusions results from either early trapping processes (due to past possible earthquakes events) or post trapping processes by addition of radiogenic 4He produced within fractured calcite veins over time (vein aging)The pristine mantle source has been active in the Irpinia area (southern Italy) for at least 1 Ma based on the post trapping process [ABSTRACT FROM AUTHOR]

Tellurium (Te)-bearing adularia-sericite epithermal Au-Ag deposits are widely distributed in calc-alkaline magmatic arcs and are an important current and future source of precious and critical metals. The source of ore-forming fluids in these deposits remains unclear due to the lack of in situ isotopic evidence on Au-, Ag-, and Te-bearing minerals. To advance the understanding of the source and evolution of Te and precious metals, herein, we combine in situ Pb isotope analysis with He, Ne, and Ar isotope and microthermometric analysis of fluid inclusions in ore and gangue minerals from two Te-rich and two Te-poor epithermal Au-Ag deposits that occur in an Early Cretaceous magmatic arc in the North Heilongjiang Belt, northeastern China. Ore minerals (hessite, petzite, calaverite, altaite, pyrite, chalcopyrite, and galena) from Te-rich Au-Ag deposits, including Sandaowanzi and Yongxin, have the least radiogenic Pb isotope compositions (206Pb/204Pb from 18.1 to 18.3) and the lowest μ1 values (the 238U/204Pb ratio of the lead source down to 9.14) of the deposits studied. For these Te-rich deposits, noble gas isotope data show that fluid inclusions in ore minerals contain a large proportion of mantle He (up to 25%), whereas barren early-stage minerals do not (<1%). The Pb, noble gas isotope, and fluid inclusion microthermometric results suggest that Te-rich ore-forming fluids were likely discharged from mafic magmas into convecting meteoric flow systems at shallow levels (<2 km). In contrast to the Te-rich deposits, ore minerals from the Te-poor Dong'an Au-Ag deposit have radiogenic Pb isotope compositions (206Pb/204Pb from 18.8 to 18.9) and the highest μ1 values (up to 10.54). Fluid inclusions in ore minerals contain a small proportion of mantle He (1% to 5%). The results suggest that metals and ore-forming fluids in these deposits were discharged from either more crustally contaminated intermediate-felsic magmas or leached from upper crustal rocks by convecting meteoric flow systems. Although the Te-poor Tuanjiegou Au-Ag deposit has a non-radiogenic Pb isotope composition consistent with a mafic magma source, Te is much less abundant (electrum [>95%] is the major gold- and silver-bearing mineral) than Au. The main exploration implication of these results is that unexplored volcano-plutonic centers in the northeast Xing'an Block with less radiogenic Pb isotope compositions (206Pb/204Pb < 18.3) and containing fluids with a high proportion of mantle He are more likely to generate Te-rich epithermal Au-Ag deposits than other volcano-plutonic centers in NE China. [ABSTRACT FROM AUTHOR]

Abstract Aiming at understanding the source of the fluids that mineralizing within seismically active fault zones, we investigate the noble gas isotopes (i.e., helium (He), neon (Ne), and argon (Ar)) in the fluid inclusions (FIs) trapped in the calcite veins sampled along high‐angle fault zones of the Contursi hydrothermal basin, southern Italy. The latter basin lies in close vicinity of the MW = 6.9, 1980 Irpinia earthquake and exposes numerous fault scarps dissecting Mesozoic shallow‐water carbonates. The analyses of noble gases (He, Ne, Ar) are conducted to identify the origin of the volatiles circulating along the faults at the time of calcite precipitation. Then, outcomes of this discussions are compared with currently outgassing of deep‐sourced CO2 coupled to mantle‐derived He in that area, whose output is larger than those from some volcanic areas worldwide. The results indicate that He in FIs is dominated by a crustal radiogenic component (4He), and by an up to 20% of a mantle‐derived component (3He), with a highest isotopic signature of 1.38 Ra. This value is consistent with the highest percentage of mantle‐derived He associated to high‐flux CO2 gas emission in the investigated area (1.41 Ra). We propose that the variability of the He isotopic signature measured in primary FIs can result from early trapping of fluid inclusions or post trapping processes and seismic activity that modify the pristine He isotopic signature (i.e., derived from the crust and/or mantle) in groundwater along the faults during periods of background seismicity. Such investigations are fundamental to understand fluid migration in fault systems and the role of fluids in processes of earthquake nucleation.

The colourless, odourless and monoatomic gas, helium, is considered as the second most abundant element in the universe after hydrogen. Helium is classified as a noble gas and it is the lightest noble gas. Noble gases including helium, although extremely inert chemically, display a remarkable spectrum of clinically useful biological properties. Medically, helium’s applications range from respiratory care, where it facilitates easier breathing through heliox mixtures, to cardiology and neurology, where it offers cardioprotection and neuroprotection during ischemia/reperfusion injuries.

Geochemistry of noble gases has been applied to the study of deep Earth materials and celestial meteorites. With advancements in measurement technology, it is also increasingly being used in natural gas research. Using the most advanced noble gas mass spectrometer, a systematic analysis was conducted on the abundance and isotopes of noble gas samples collected from the middle and deep Songliao Basin in eastern China to elucidate the compositional characteristics of noble gases in a faulted basin. The findings reveal that the abundance of noble gases in natural gas decreases from light noble gases to heavy noble gases in a left-to-right reversed L-shaped pattern. Specifically, the isotopic ratios of noble gases are: 3He/4He at 2.64×10-6, 20Ne/22Ne at 9.94, 21Ne/22Ne at 0.029 22, and 40Ar/36Ar at 743.7, all of which are higher than atmospheric values. The isotopes 80Kr, 84Kr, 86Kr, and 131-136Xe show relative excess compared to atmospheric levels, indicating the mixing of mantle-derived gases in the natural gas. Based on the compositional characteristics of noble gases, this study suggests that the natural gas in the middle and deep Songliao Basin originated from inorganic crust and mantle mixing. Additionally, certain differences exist in the contribution of mantle-derived components across different tectonic blocks and categories of natural gas within the basin. Comparison between noble gas compositions and the types of natural gas demonstrates that light noble gases distinguish effectively between different types of natural gas, whereas the composition of heavy noble gases shows no significant differences among various types of natural gas. Noble gas isotopes, in addition to tracing the source of natural gas, can also be used to determine natural gas genesis, distinguish natural gas types and characterize tectonic settings.

The molecular and isotopic compositions of shale gases exhibit substantial differences under different storage conditions. Gas geochemistry is widely used when evaluating gas accumulation and expulsion in petroleum systems. Gas geochemical characteristics can provide important references for determining the enrichment mechanism of shale gas reservoirs and predicting shale gas production capacity in different regions. In tectonically stable regions with similar reservoir formation and evolution histories, shale gas reservoirs are expected to exhibit favorable storage conditions with only relatively small variations in gas geochemical characteristics. In tectonically active regions, shale gas preservation conditions are expected to be more variable. In this study, we systematically analyzed the stable isotope signatures (δ[sup 13]C and δD) of alkane gases (CH4, C2H6, and C3H8), along with noble gas compositions and isotopic signatures, of normally pressured Wufeng-Longmaxi marine shale gas samples comprising a continuous pressure coefficient series from a structurally active region at the transition between an orogenic belt and the southeastern (SE) Sichuan Basin, China. The relationships between noble gas contents, isotopic signatures, and shale gas yields were evaluated, and a mechanism for normally pressured shale gas accumulation and expulsion was presented. The δ13C and δD data suggest that the normally pressured shale gas originated from late-mature thermogenic generation, equivalent to shale gas from other production areas in the inner Sichuan Basin. Gas dryness ratios [C[sub 1]/(C[sub 2] + C[sub 3])] exhibit negative relationships with δ13C1 and δ13C2. Normally pressured shale gas yields exhibit a negative correlation with δ13C and a positive correlation with [C1/(C2 + C3)], suggesting differences in shale gas accumulation and expulsion across the studied region related to changes in the pressure coefficient. Noble gas isotope data suggest that the normally pressured Longmaxi shale gas received a substantial contribution of crust-derived He. Coupling noble gas and stable C/H isotope data reveals that the abundance of He and Ar, along with the δ13C signatures of alkane gases, is affected by the abundance of shale gas during the accumulation and expulsion process. The noble gas and stable isotope distribution trends presented herein can be used to evaluate Wufeng-Longmaxi's normally pressured shale gas accumulation and expulsion in complex structural areas of the southeastern Sichuan Basin. Better preservation conditions accompanying lower tectonic activity will normally result in higher shale gas production and a lower concentration of noble gases. The above findings show that gas geochemical characteristics could be used as effective evaluation indicators for determining shale gas accumulation mechanisms in tectonically active regions. [ABSTRACT FROM AUTHOR]

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Abstract Noble gases are useful tracers for geochemistry, used to elucidate the origin and evolution of the solar system and planets. Noble gas analyses have been limited to bulk and spot analyses of solids and have yet to be developed for two- and three-dimensional imaging analysis. Recent developments in He isotope imaging using secondary neutral mass spectrometry are reviewed. The images have been fully quantified, and the spatial resolution has reached the nanoscale. The detection limit has been reduced to the level of ~ 10–3 cm3 STP g−1 (~ 1017 cm−3, ~ 1 ppma) for helium at lateral micrometer resolution. With this development, the concentration distribution of He in solids has been visualized as a map for the first time.

Quantum amplification enables the enhancement of weak signals and is of great importance for precision measurements, such as biomedical science and tests of fundamental symmetries. Here, we observe a previously unexplored magnetic amplification using dark noble-gas nuclear spins in the absence of pump light. Such dark spins exhibit remarkable coherence lasting up to 6 min and the resilience against the perturbations caused by overlapping alkali-metal gas. We demonstrate that the observed phenomenon, referred to as "dark spin amplification," significantly magnifies magnetic field signals by at least three orders of magnitude. As an immediate application, we showcase an ultrasensitive magnetometer capable of measuring subfemtotesla fields in a single 500-s measurement. Our approach is generic and can be applied to a wide range of noble-gas isotopes, and we discuss promising optimizations that could further improve the current signal amplification up to 104 with 21Ne, 105 with 129Xe, and 106 with 3He. This work unlocks opportunities in precision measurements, including searches for ultralight dark matter with sensitivity well beyond the supernova-observation constraints. [ABSTRACT FROM AUTHOR]

The structure and stability of noble gas (Ng) bound [NHCM]+ complexes (M = Cu, Ag, and Au) were investigated using Quantum chemical calculations. Dissociation energies, enthalpy, and free energy changes were computed to comprehend the stability of these Ng‐bonded complexes. The nature of interactions associated to the bonding between metal and noble gas atoms was studied through the computation of electron density‐based descriptors. Detailed electronic structure study revealed electron donation from the noble gas atoms towards the metal center, resulting in the formation of dative bonds. [ABSTRACT FROM AUTHOR]

This is the first in vivo study to investigate the neuroprotective effects of krypton on focal cerebral ischemia. The aim of the study was to analyze the effect of 2 h of inhalation of a krypton–oxygen mixture (Kr 70%/O2 30%) on the recovery of neurological functions and the degree of brain damage in rats after photoinduced ischemic stroke (PIS) and to investigate the possible mechanisms responsible for this neuroprotection. Experiments were performed on male Wistar rats weighing 250–300 g (n = 32). Animals were randomized into four groups. Two groups (n = 20) underwent photoinduced ischemic stroke, followed by 2 h of inhalation of krypton–oxygen mixture consisting of Kr 70%/O2 30% or a nitrogen–oxygen breathing mixture consisting of N2 70%/O2 30%, followed by neurological examinations on days 3 and 7. The other two groups (n = 12) received only gas mixtures of the same concentration and exposure duration as in those in the PIS groups, then Western blot analysis of the potential molecular mechanisms was performed. The results of the study show that treatment with the krypton–oxygen mixture consisting of Kr 70%/O2 30% improves the neurological status on day 7 of observation, reduces the lesion volume according to the MRI examination and the number of Iba-1- and caspase-3-positive cells in the damaged area, promotes the activation of neoangiogenesis (an increase in the von Willebrand factor), and reduces the penumbra area and the number of NeuN-positive cells in it on day 14 of observation. Inhalation of the krypton–oxygen mixture also significantly increases the levels of phosphorylated AKT kinase (protein kinase B) and glycogen synthase kinase 3b (pGSK3b) and promotes the expression of transcription factor Nrf2, which was accompanied by the lowered expression of transcription factor NFkB (p50). Thus, we showed pronounced neuroprotection induced by krypton inhalation after stroke and identified the signaling pathways that may be responsible for restoring neurological functions and reducing damage. [ABSTRACT FROM AUTHOR]

Gas adsorption on one-atom-thick membranes is a growing technology for separation applications owing to its excellent energy efficiency. Herein, we investigate the adsorption of the noble gases, Ne, Ar and Kr on graphynes (GYs), a novel class of one-atom-thick carbon membranes using a swarm intelligence technique, namely particle swarm optimization (PSO). Modeling the adsorption of noble gas clusters on two-dimensional substrates requires a thorough examination of the energy landscape. The high dimensionality of the problem makes it tricky to employ ab initio methods for such studies, necessitating the use of a metaheuristic global optimization technique such as PSO. We explored the adsorption of 1–30 atoms of Ne, Ar and Kr on α-, β-, γ- and rhombic-GYs to predict the most suitable form of GY for the adsorption of each of the gases. Employing the dispersion-corrected density functional theory (DFT-D) data for the adsorption of single gas atoms as the reference data, we parametrized two empirical pairwise potentials, namely, Lennard-Jones (LJ) and improved Lennard-Jones (ILJ) potentials. We then analyzed the growth pattern as well as the energetics of adsorption using the parametrized potentials, in combination with the PSO technique, which enabled us to predict the best possible membrane for the adsorption of the noble gases: α-GY for Ne and γ-GY for Ar and Kr. The accuracy of our modeling approach is further validated against DFT-D computations thereby establishing that PSO, when combined with the ILJ potential, can serve as a computationally feasible approach for modeling gas adsorption on GYs.

Summary: Background: Argon (Ar) has been proposed as a potential therapeutic agent in multiple clinical conditions, specifically in organ protection. However, conflicting data on pre-clinical models, together with a great variability in Ar administration protocols and outcome assessments, have been reported. The aim of this study was to review evidence on treatment with Ar, with an extensive investigation on its neuroprotective effect, and to summarise all tested administration protocols. Methods: Using the PubMed database, all existing pre-clinical and clinical studies on the treatment with Ar were systematically reviewed (registration: https://doi.org/10.17605/OSF.IO/7983D). Study titles and abstracts were screened, extracting data from relevant studies post full-text review. Exclusion criteria included absence of full text and non-English language. Furthermore, meta-analysis was also performed to assess Ar potential as neuroprotectant agent in different clinical conditions: cardiac arrest, traumatic brain injury, ischemic stroke, perinatal hypoxic-ischemic encephalopathy, subarachnoid haemorrhage. Standardised mean differences for neurological, cognitive and locomotor, histological, and physiological measures were evaluated, through appropriate tests, clinical, and laboratory variables. In vivo studies were evaluated for risk of bias using the Systematic Review Center for Laboratory Animal Experimentation tool, while in vitro studies underwent assessment with a tool developed by the Office of Health Assessment and Translation. Findings: The systematic review detected 60 experimental studies (16 in vitro, 7 ex vivo, 31 in vivo, 6 with both in vitro and in vivo) investigating the role of Ar. Only one clinical study was found. Data from six in vitro and nineteen in vivo studies were included in the meta-analyses. In pre-clinical models, Ar administration resulted in improved neurological, cognitive and locomotor, and histological outcomes without any change in physiological parameters (i.e., absence of adverse events). Interpretation: This systematic review and meta-analysis based on experimental studies supports the neuroprotective effect of Ar, thus providing a rationale for potential translation of Ar treatment in humans. Despite adherence to established guidelines and methodologies, limitations in data availability prevented further analyses to investigate potential sources of heterogeneity due to study design. Funding: This study was funded in part by Italian Ministry of Health-Current research IRCCS and by Ministero della Salute Italiano, Ricerca Finalizzata, project no. RF 2019-12371416.

The noble gas argon has demonstrated biological activity that may prove useful as a medical intervention. Pharmacokinetics, the disposition of the drug molecule in the body through time, is fundamental necessary knowledge to drug discovery, development and even post-marketing. The fundamental measurement in pharmacokinetic studies is blood concentration of the molecule (and its metabolites) of interest. While a physiologically based model of argon pharmacokinetics has appeared in the literature, no experimental data have been published. Thus, argon pharmaceutical development requires measurement of argon solubility in blood. This paper reports on the development of a technique based on mass spectrometry for measuring argon solubility in liquids, including blood, to be further employed in pharmacokinetics testing of argon. Based on a prototype, results are reported from sensitivity experiments using ambient air, water and rabbit blood. The key takeaway is that the system was sensitive to argon during all of the testing. We believe the technique and prototype of the quadrupole mass spectrometer gas analyzer will be capable of inferring argon pharmacokinetics through the analysis of blood samples. [ABSTRACT FROM AUTHOR]

Quantum chemical calculations were carried out to investigate the noble gas binding ability of Be3B+ cluster. Calculations reveal that heavier noble gas atoms (ArXe) form stable complexes with this cluster. Detailed bonding analyses reveal that the noble gas atoms act as donor fragment in the formation of Ng → Be donor–acceptor bonds. Three noble gas atoms can consecutively form bonds with the Be atom of the Be3B+ cluster. [ABSTRACT FROM AUTHOR]

Quantum chemical calculations were carried out to investigate the noble gas binding ability of Be3B+ cluster. Calculations reveal that heavier noble gas atoms (ArXe) form stable complexes with this cluster. Detailed bonding analyses reveal that the noble gas atoms act as donor fragment in the formation of Ng → Be donor–acceptor bonds. Three noble gas atoms can consecutively form bonds with the Be atom of the Be3B+ cluster. [ABSTRACT FROM AUTHOR]

In this study, we employ strong field approximation (SFA) to investigate the influence of the number of pulse cycles on above-threshold ionization within the framework of nondipole theory. The SFA enables the analysis of the ionization process under the dominance of the electric field, compared to other factors such as the binding potential of an atom. Nondipole effects, including higher-order multipole fields, can significantly impact ionization dynamics. However, the interaction between nondipole effects and pulse cycles remains unclear. Therefore, we investigate the pulse cycle dependence of ionization and examine peak shifts in Kr and Ar atoms. Our findings have implications for comprehensively understanding the effects of electromagnetic fields on electron behavior. The insights gained from this study provide valuable guidance for future research in strong field ionization. [ABSTRACT FROM AUTHOR]

The analysis and measurement of Wigner time delays can provide detailed information about the electronic environment within and around atomic and molecular systems, with one the key differences being the lack of a long-range potential after a halogen ion undergoes photoionization. In this work, we use relativistic random-phase approximation to calculate the average Wigner delay from the highest occupied subshells of the atomic pairings (2p, 2s in Fluorine, Neon), (3p, 3s in Chlorine, Argon), (4p, 4s, 3d, in Bromine, Krypton), and (5p, 5s, 4d in Iodine, Xenon). The qualitative behaviors of the Wigner delays between the isoelectronic pairings were found to be similar in nature, with the only large differences occurring at photoelectron energies less than 20   e V and around Cooper minima. Interestingly, the relative shift in Wigner time delays between negatively charged halogens and noble gases decreases as atomic mass increases. All atomic pairings show large differences at low energies, with noble gas atoms showing large positive Wigner delays, while negatively charged halogen ions show negative delays. The implications for photoionization studies in halide-containing molecules is also discussed. [ABSTRACT FROM AUTHOR]

Surface casing vents divert natural gas migration along oil and gas boreholes to bypass groundwater, with the gas venting to the atmosphere. While this strategy is designed to protect groundwater, it constitutes a source of greenhouse gases to the atmosphere. In instances where gas leakage occurs, the characterization of the molecular and isotopic composition of natural gas emitted from surface casing vent flows can be used to assist in identifying the gas source. We compare concentration measurements of non-hydrocarbon gases (within natural gas) of samples analyzed by laboratory-based gas chromatography (N2, Ar, CO2 and O2) and magnetic sector noble gas mass spectrometry (He, Ar and Kr) with field measurements conducted using a field portable quadrupole mass spectrometer (miniRUEDI). The standard deviation of miniRUEDI concentration results was within plus/minus one standard deviation of samples measured using laboratory-based GC (N2, O2, Ar and He) and magnetic sector noble gas mass spectrometry (He, Ar). Additional laboratory-based determination of isotope ratios of methane and argon (δ13CCH4, δ2HCH4, and 40Ar/36Ar) enabled a comparison between information provided by the analysis of reactive gases compared with noble gas isotopes. Gases from different sources displayed quantifiable differences in δ13CCH4 and δ2HCH4, but these changes may or may not be distinguished if only one sampling event is conducted. By comparison, 40Ar/36Ar further enabled the differentiation of various gas sources. The objective of this paper is to discuss the advantages and trade-offs of the three different analysis methods considered, and the feasibility of their application in different environmental monitoring scenarios. [ABSTRACT FROM AUTHOR]

This is the first in vivo study to investigate the neuroprotective effects of krypton on focal cerebral ischemia. The aim of the study was to analyze the effect of 2 h of inhalation of a krypton–oxygen mixture (Kr 70%/O2 30%) on the recovery of neurological functions and the degree of brain damage in rats after photoinduced ischemic stroke (PIS) and to investigate the possible mechanisms responsible for this neuroprotection. Experiments were performed on male Wistar rats weighing 250–300 g (n = 32). Animals were randomized into four groups. Two groups (n = 20) underwent photoinduced ischemic stroke, followed by 2 h of inhalation of krypton–oxygen mixture consisting of Kr 70%/O2 30% or a nitrogen–oxygen breathing mixture consisting of N2 70%/O2 30%, followed by neurological examinations on days 3 and 7. The other two groups (n = 12) received only gas mixtures of the same concentration and exposure duration as in those in the PIS groups, then Western blot analysis of the potential molecular mechanisms was performed. The results of the study show that treatment with the krypton–oxygen mixture consisting of Kr 70%/O2 30% improves the neurological status on day 7 of observation, reduces the lesion volume according to the MRI examination and the number of Iba-1- and caspase-3-positive cells in the damaged area, promotes the activation of neoangiogenesis (an increase in the von Willebrand factor), and reduces the penumbra area and the number of NeuN-positive cells in it on day 14 of observation. Inhalation of the krypton–oxygen mixture also significantly increases the levels of phosphorylated AKT kinase (protein kinase B) and glycogen synthase kinase 3b (pGSK3b) and promotes the expression of transcription factor Nrf2, which was accompanied by the lowered expression of transcription factor NFkB (p50). Thus, we showed pronounced neuroprotection induced by krypton inhalation after stroke and identified the signaling pathways that may be responsible for restoring neurological functions and reducing damage.

The noble gas helium (He) induces cardioprotection in vivo through unknown molecular mechanisms. He can interact with and modify cellular membranes. Caveolae are cholesterol and sphingolipid-enriched invaginations of the plasma-membrane-containing caveolin (Cav) proteins that are critical in protection of the heart. Mice (C57BL/6J) inhaled either He gas or adjusted room air. Functional measurements were performed in the isolated Langendorff perfused heart at 24 h post He inhalation. Electron paramagnetic resonance spectrometry (EPR) of samples was carried out at 24 h post He inhalation. Immunoblotting was used to detect Cav-1/3 expression in whole-heart tissue, exosomes isolated from platelet free plasma (PFP) and membrane fractions. Additionally, transmission electron microscopy analysis of cardiac tissue and serum function and metabolomic analysis were performed. In contrast to cardioprotection observed in in vivo models, the isolated Langendorff perfused heart revealed no protection after He inhalation. However, levels of Cav-1/3 were reduced 24 h after He inhalation in whole-heart tissue, and Cav-3 was increased in exosomes from PFP. Addition of serum to muscle cells in culture or naïve ventricular tissue increased mitochondrial metabolism without increasing reactive oxygen species generation. Primary and lipid metabolites determined potential changes in ceramide by He exposure. In addition to direct effects on myocardium, He likely induces the release of secreted membrane factors enriched in caveolae. Our results suggest a critical role for such circulating factors in He-induced organ protection.

Xenon capture and Xe/Kr separation are important processes in industry. For instance, Xe/Kr separation is an indispensable step in recycle and treatment of nuclear fuel emission. Among different separation methods, selectively adsorb gas molecules using porous materials is a promising way to reduce the high energy consumption in traditional cryogenic distillation. However, many reported adsorbents still face the challenges of: i) poor separation property at low Xe/Kr concentrations; ii) insufficient retention volumes, which influence the viability of whole process. In this work, we present a stable covalent organic polymer, i.e., COP-14, showing promising potential for Xe/Kr separiton. In dynamic breakthrough experiments, COP-14 successfully separates low concentration Xe (350 ppm) and Kr (35 ppm) from target gas mixtures. Meanwhile, the xenon retention volume per gram (1700 mL g−1 at 298 K) of COP-14 in dynamics absorption process achieves 3.8 times of benchmark active carbon. The good performance of the newly devloped COP-14 mainly from its rich nitrogen sites and suitable pore size with xenon molecues. The promising results of COP-14 on Xe/Kr separation in this work provide a promising way for designing efficient Xe/Kr separation mateirals.

This article provides a discussion on the nature of bonding between noble gases (Ng) and noble metals (M) from a quantum chemical perspective by investigating compounds such as NgMY (Y=CN, O, NO3, SO4, CO3), [NgM−(bipy)]+, NgMCCH, and MCCNgH complexes, where M=Cu, Ag, Au and Ng=Kr−Rn, with some complexes containing the lighter noble gas atoms as well. Despite having very low chemical reactivity, noble gases have been observed to form weak bonds with noble metals such as copper, gold, and silver. In this study, we explore the factors that contribute to this unusual bonding behavior, including the electronic structure of the atoms involved and the geometric configuration of the concerned fragments. We also investigate the metastable nature of the resulting complexes by studying the energetics of their possible dissociation and internal isomerization channels. The noble gas-binding ability of the bare metal cyanides are higher than most of their bromide counterparts, with CuCN and AgCN showing higher affinity than their chloride analogues as well. In contrast, the oxides seem to have lower binding power than their corresponding halides. In the oxide and the bipyridyl complexes, the Ng-binding ability follows the order Au > Cu > Ag. The dissociation energies calculated, considering the zero-point energy correction for possible dissociation channels, increase as we move down the noble gas group. The bond between the noble gases and the noble metals in the complexes are found to have comparable weightage of orbital and electrostatic interactions, suggestive of a partial covalent nature. The same is validated from the topological analysis of electron density. [ABSTRACT FROM AUTHOR]

An in silico strategy of handling the thermochemical stability of XOPO(OH)2 compounds (X = F, Cl, Br) is performed by insertion of noble gas (Ng) atoms (Ng = Kr, Xe and Rn) within the X–O bond. The theoretical prediction of the set of new compounds, XNgOPO(OH)2 (X = F, Cl, Br; Ng = Kr, Xe, Rn) and their thermochemical stability are investigated using both ab initio and density-functional theory techniques considering different possible dissociation channels. The Ng (Kr–Rn) inserted analogues show that these compounds exist in their corresponding minima on their respective potential-energy surfaces. Most importantly, the release of Ng atom resulting in the formation of the bare XOPO(OH)2 and free Ng is thermochemically favorable. However, this process has very high activation energy barriers, thus kinetically protecting it from undergoing the said dissociation at room temperature. All other possible two-body and three-body ionic as well as neutral dissociation pathways are endergonic at 298 K. The generation of new Ng-based insertion compounds offers a hitherto unknown strategy of the metastable behavior of these compounds. A thorough description of the X–Ng and Ng–O bonds in XNgOPO(OH)2 compounds is provided with the help of natural bond orbital, Wiberg bond index, electron density, and energy decomposition analyses, and the more favorable representation of the compounds is proclaimed in our present discussion. [ABSTRACT FROM AUTHOR]

Isotopic ratios of radioxenons sampled in the atmosphere or subsurface can be used to verify the occurrence of an underground nuclear explosion (UNE). Differences in the half-lives of radioactive xenon precursors and their decay-chain networks produce different time-dependent concentration profiles of xenon isotopes allowing isotopic ratios to be used for tracking UNE histories including estimating the time of detonation. In this study, we explore the potential effects of post-detonation cavity processes: precipitation of iodine precursors, gas seepage, and prompt venting on radioxenon isotopic evolution which influences UNE histories. Simplified analytical models and closed-form solutions yielding a potentially idealized radioactive decay/ingrowth chain in a closed and well-mixed system typically have limited application by not including the partitioning of the radionuclide inventory between a gas phase and rock melt created by the detonation and by ignoring gas transport from the cavity to host rock or ground surface. In reality, either subsurface transport or prompt release that is principally responsible for gas signatures violates the closed-system (or batch-mode) assumption. A closed-form solution representing time-dependent source-term activities is extended by considering the cavity partitioning process, slow seepage, and/or prompt release of gases from the cavity and applied to realistic systems. [ABSTRACT FROM AUTHOR]

Quantum chemical calculations were carried out to investigate the nature of the bonding between a neutral Be3 ring and noble gas atom. Electronic structure calculation for these complexes was carried out at different computational levels in association with natural bond orbital, quantum theory of atoms in molecules, electron localization function, symmetry adapted perturbation theory, and molecular electrostatic potential surface analysis of Be3 complexes. The Be atoms in the Be3 moiety are chemically bonded to one another, with the BeBe bond dissociation energy being ~125 kJ mol−1. The Be3 ring interacts with the noble gases through non‐covalent interactions. The binding energies of the noble gas atoms with the Be3 ring increases with increase in their atomic number. The non‐covalent interaction index, density overlap region indicator and independent gradient model analyses reveal the presence of non‐covalent inter‐fragment interactions in the complexes. Energy decomposition analysis reveals that dispersion plays the major role towards stabilizing these systems. [ABSTRACT FROM AUTHOR]

The chemical and isotopic composition of gases emitted by subduction zone volcanoes can provide insights into the origin of magmatic volatiles. In volcanic arcs, magmatic volatiles can be supplied from the mantle, the subducting slab, or the rocks of the arc crust. Determining the relative contributions of these distinct sources is important for understanding the transfer of volatiles between Earth's interior and exterior reservoirs, which has implications for the physical and chemical evolution of both the mantle and the atmosphere. Each subduction zone has a different recycling efficiency, controlled by the composition of the slab and the pressure-temperature path it experiences upon subduction, and accordingly all volcanic arc emissions can be characterised by their chemical and isotopic compositions. In this study, we analyse the composition of volcanic gases from Rabaul caldera in the New Britain subduction zone, Papua New Guinea, and show that the emissions are substantially influenced by slab recycling of carbon and nitrogen. We find helium emissions are dominated by a mantle contribution, with little influence from the arc crust. Carbon isotopes point towards a mixture of mantle, carbonate and organic sediment-derived contributions, with the dominant input coming from carbonates. This may be of sedimentary origin, seafloor calcareous muds, or altered basalts of the subducting oceanic crust. Nitrogen isotopes also indicate a significant influence of sedimentary nitrogen and, potentially, a contribution from altered ocean crust. Our study is the first comprehensive investigation of volatile sources in the New Britain subduction zone and our results and interpretation are consistent with previous studies of element recycling based on New Britain arc lavas. [ABSTRACT FROM AUTHOR]

[Display omitted] • B 3 C 2 H 5 structure was designed and inductive charge transfer from Ng atoms was investigated for the first time. • E HOMO , E LUMO , E g , E ad , and analyses were utilized for studying the electronic changes upon interactions with Ng atoms. • LOL, ELF, and RDG analyses were used for studying the interaction nature. Quantum chemical calculations were performed to study the binding affinity of the B 3 C 2 H 5 cluster with noble gases. The results indicate that noble gas atoms especially the heavier ones such as Xe and Kr can form stable complexes with this cluster. Detailed analysis of the interaction mechanism reveals that the noble gas atoms serve as donor fragments in the formation of Ng@B 3 C 2 H 5 , 2Ng@B 3 C 2 H 5 , and 3Ng@B 3 C 2 H 5 donor–acceptor complexes. [ABSTRACT FROM AUTHOR]

Villarrica volcano, in the southern Andes, is a composite mafic volcano whose persistent open-vent activity is punctuated by frequent Strombolian/Hawaiian eruptions and, more rarely, by more energetic (sub-Plinian) events. Here, we investigate the volatile composition of the parental melts that sustain this activity, and the conditions of pre-eruptive magma storage, by characterizing the composition of olivine-hosted melt and fluid inclusions. We concentrate on inclusions entrapped in minerals from pyroclastic materials erupted from both Villarrica summit and from its flank Minor Eruptive Centers (MECs) post the 14.5–13.5 kyr caldera collapse event that formed the Licán ignimbrite. Our micro-FTIR and SIMS measurements indicate that the Pucón eruption records the highest volatile contents, with 6.0 wt% H 2 O, >1500 ppm CO 2 , 1330 ppm S, 1556 ppm Cl, and 2055 ppm F. These volatile contents imply a volatile-saturated magma originating from a depth of 14.4 to 17 km below Villarrica. Results for other flank eruptions highlight a similarly deep (17–21 km depth) source for basaltic CO 2 -rich mafic magmas erupted at regional MECs (Los Nevados, Caburgua). Melt inclusion results also reveal that deep rising mafic magma batches, when temporarily stored at 1–5 km depth, produce the more differentiated and degassed magma batches that sustain the decadal-old persistent effusive-explosive eruptive activity at Villarrica. Helium isotope ratios (3He/4He; Rc/Ra when corrected for atmosphere) measured in bulk noble gases from olivines (Fo 75 – 88) indicate that the parental magmatic fluid signature (Rc/Ra = 6.7–7.6; CO 2 /3He = 4.7–7.5E+08) is only recorded during central paroxysmal sub-Plinian eruption, and that this primitive gas signal is diluted in lateral MECs (Rc/Ra < 6.5; CO 2 /3He = 1.4 × 10+9–3.1E+10). • Pucón Ignimbrite represent Villarrica post-glacial primitive mafic magma. • Polygenetic eruptive vents source >17 km depth CO 2 -rich volatile melts. • Villarrica and lateral vent degas mafic magma at <5 km storage depths. • Shallow atmospheric and mixed crustal 4He in volcanic arc fluids. • Subplinian paroxysms preserve MORB-like 3He/4He fluid ratios. [ABSTRACT FROM AUTHOR]

Density functional calculations have been carried out to investigate the possibility of trapping of noble gas dimers by cyclo[18]carbon dimer. Parallel‐displaced conformation of the cyclo[18]carbon dimer is found to be the minimum energy structure. Noncovalent interaction is found to hold the noble gas dimers. The lighter noble gases (He, Ne) posses weaker attractive interactions while the heavier one (Ar, Kr) are held by stronger attractive interactions forming genuine bonds. Each of the noble gas atoms in turn forms noncovalent interaction with the cyclo[18]carbon monomers. The bond dissociation energy of the noble gas dimers dramatically increases inside the cyclo[18]carbon dimer. Energy decomposition analysis reveals that dispersion plays the major role toward the stabilization energy. [ABSTRACT FROM AUTHOR]

A density functional theory study is performed to determine the stability and bonding in the neon dimer inside the B30N30 fullerene cage, the fluxional B40 cage, and within non-fluxional cages such as B12N12 and C60. The nature of bonding in the Ne2 encapsulated B40 is compared with the that in other cages in an attempt to determine whether any possible alterations are brought about by the dynamical nature of the host cage apart from the associated confinement effects. The bonding analysis includes the natural bond order (NBO), Bader's Atoms-in-Molecules electron density analysis (AIM), and energy decomposition analysis (EDA), revealing the non-covalent nature of the interactions between the Ne atoms and that between the Ne and the cage atoms. The formation of all the Ne2@cage systems is thermochemically unfavourable, the least being that for the B30N30 cage, which can easily be made favourable at lower temperatures. The Ne-Ne distance is lowest in the smallest cage and increases as the cage size increase due to steric relaxation experienced by the dimer. The dynamical picture of the systems is investigated by performing ab initio molecular dynamics simulations using the atom-centred density matrix propagation (ADMP) technique, which shows the nature of the movement of the dimer inside the cages, and by the fact that since it moves as a single entity, a weak bonding force holds them together, apart from their proven kinetic stability. [ABSTRACT FROM AUTHOR]

Almost all experimental studies of the characteristics of nuclear-excited plasma formed by excitation of gaseous media with nuclear reactions products are conducted at pulsed nuclear reactors that differ in the composition and design of the core, the duration, flux and fluence of the neutron pulse, the impulse repetition frequency, the volume and configuration of the irradiation space. This paper presents a description of the experimental (methodical and hardware) base of the National Nuclear Center of RK (Kurchatov) to conduct experiments on studying the threshold characteristics of laser action at the p-s-transition of noble gas atoms upon 6Li(n,α)3H nuclear reaction products excitation in conditions of a pulsed nuclear IGR reactor. To conduct in-pile reactor experiments, a special experimental facility was developed and constructed. The experimental facility functionally includes: in-pile experimental device, a gas–vacuum system, information and measurement system consisting of a system for registering and controlling the temperature of the device housing, and a system for registering optical radiation. The paper also briefly describes the methodology of in-pile reactor experiments on the pulsed nuclear reactor. [ABSTRACT FROM AUTHOR]

In recent years, inert gases such as helium, argon, and xenon have gained considerable attention for their medical value. Noble gases present an intriguing scientific paradox: although extremely chemically inert, they display a remarkable spectrum of clinically useful biological properties. Despite a relative paucity of knowledge about their mechanisms of action, some noble gases have been used successfully in clinical practice. The neuroprotection elicited by these noble gases has been investigated in experimental animal models of various types of brain injuries, such as traumatic brain injury, stroke, subarachnoid hemorrhage, cerebral ischemic/reperfusion injury, and neurodegenerative diseases. Collectively, these central nervous system injuries are a leading cause of morbidity and mortality every year worldwide. Treatment options are presently limited to thrombolytic drugs and clot removal for ischemic stroke, or therapeutic cooling for other brain injuries before the application of noble gas. Currently, there is increasing interest in noble gases as novel treatments for various brain injuries. In recent years, neuroprotection elicited by particular noble gases, xenon, for example, has been reported under different conditions. In this article, we have reviewed the latest in vitro and in vivo experimental and clinical studies of the actions of xenon, argon, and helium, and discuss their potential use as neuroprotective agents. [ABSTRACT FROM AUTHOR]

In the semiconductor industry, fluorocarbon (FC) plasma is widely used in SiO2 etching, with Ar typically employed in the dilution of the FC plasma due to its cost effectiveness and accessibility. While it has been reported that plasmas with other noble gases, namely Kr and Xe, have distinct physical properties such as electron density and temperature, their implementation into plasma etching has not been sufficiently studied. In this work, we conducted SiO2 etching with FC plasmas diluted with different noble gases, i.e., FC precursors of C4F8 and CH2F2 with Ar, Kr, or Xe, under various gas flow rates of each as well as plasma diagnostics for the process interpretation. We show that Ar, Kr, and Xe gas mixtures depend on the FC precursor flow rate and the pattern width in a significantly different manner and we elucidate these findings based on plasma diagnostic results. The results of this work are expected to offer a practical etching database for diverse applications including plasma process engineering and the development of plasma simulation in the semiconductor industry. [ABSTRACT FROM AUTHOR]

The reduction of energy losses and destroyed exergy requires the optimization of the double-glazing space. The poor thermophysical characteristics of the air are a limiting factor in the attenuation of heat loss through the double-glazing of the solar collector.The aim of this study is to examine the effect of trapped gases (argon, xenon, krypton, and SF6) within the double-glazing and between the inner glass and the absorber on the efficiency, useful energy, overall heat loss coefficient, and outlet temperature of the back-plate solar air heater. This research was conducted by applying constant solar radiation of 1000 W/m2. The new Eismann correlation is implemented to iteratively evaluate the heat transfer coefficients in gas-filled interspaces and to optimally define these distances. Furthermore, the impact of these gases on exergy efficiency, destruction exergy, and system exergy has been studied. Among these rare gases, xenon leads to the best thermal performance, followed by krypton and argon, compared to air. Respectively, the efficiencies obtained are 51.8%, 50.6%, 48.8%, and 45.8% for xenon, krypton, argon, and air. The optimal gas-filled spaces corresponding to these efficiencies are 4 mm, 5 mm, 9 mm, and 10 mm. Similarly, the exergy approach leads to the same optimal widths of the gas-filled spaces.

Whether auriferous hydrothermal fluid is generated during crustal metamorphism or by subcrustal processes to form orogenic gold deposits is hotly debated. Noble gas isotope and halogen abundance ratios can provide important constraints to help resolve this controversy. The Danba gold deposit is a rare example of a Jurassic age hypozonal orogenic gold deposit on the western margin of the Yangtze Craton, China. It is characterized by thick barren quartz veins with fractures infilled by thin auriferous quartz veinlets. The syn -gold quartz veinlets are associated with plagioclase and pyrrhotite and are distinguished from the barren quartz vein hosts on the basis of cathodoluminescence, trace-element content and Raman spectroscopy and microthermometry of fluid inclusions. The dominant fluid inclusions in the gold-bearing quartz and plagioclase are H 2 O–CH 4 with vapor fill of ∼ 15–45 vol% and high pressure-corrected trapping temperatures of ∼ 500 °C, low salinities (<4 wt% NaCl equiv.) and high Mg/Fe ratios. Crushing syn -gold quartz and plagioclase released fluid inclusions with 40Ar/36Ar ratios of between 490 and 710, molar Br/Cl ratios of (0.3–0.7) × 10−3 and molar I/Cl ratios of (18–60) × 10−6. Crushing syn -gold pyrrhotite released fluid inclusions with 3He/4He ratios of 0.21–0.38 Ra (Ra = air value, 1.39 × 10−6) that are higher than typical crustal values of < 0.1 Ra, and 40Ar/36Ar of 330–640 that are similar to the gold-related quartz-hosted inclusions. The combined noble gas and halogen data do not favor an auriferous fluid derived from K- and U-rich Proterozoic granitic basement, which is expected to have radiogenic 40Ar/36Ar and 3He/4He ratios. Instead, the data are more consistent with a fluid source from underlying mantle lithosphere containing a high proportion of altered ocean crust (AOC). The auriferous fluid that formed the Danba gold deposit is thus considered to have been derived from a source comprising both metasomatized mantle lithosphere that had been fertilized in a Neoproterozoic subduction event and a portion of relict AOC beneath the western margin of the Yangtze Craton. In contrast with syn -gold fluid inclusions, those in pre-gold barren quartz are H 2 O–CO 2 dominated. Crushing pre-gold quartz released fluid inclusions with 40Ar/36Ar ratios of 2410–5450, Br/Cl ratios of (1.2–1.5) × 10−3 and I/Cl ratios of (60–80) × 10−6 that are distinctly different to the gold-ore stage. The higher 40Ar/36Ar ratios of the pre-gold fluids are consistent with a source for the barren host quartz veins from prograde greenschist- to amphibolite-facies metamorphism of the Proterozoic granitic basement. [ABSTRACT FROM AUTHOR]