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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]

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]

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]

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. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

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]

• High precision of e-CPA in predicting noble gas solubility in solutions. • Salting-out effect investigation of electrolytes on noble gas solubility in water. • Enhancing the model accuracy based on noble gas dissolution behavior. • Effective modeling tool for achieving sustainable water resource management. Dissolved noble gases in water hold significant potential as tracers and precursors in various hydrogeological and geological applications, particularly in understanding surface water-groundwater interactions. These applications necessitate precise solubility predictions. Employing the fugacity-fugacity approach, our study models the solubilities of Neon, Argon, Krypton, Xenon, and Radon in both pure water and electrolyte solutions. Leveraging the Cubic-Plus-Association Equation of State, we achieve remarkable accuracy, with average deviations below 2.5 % for vapor pressure, liquid, and vapor-phase densities. Additionally, in water–gas binary systems, deviations in gas solubilities within pure water remain under 5.0 %. Extending our analysis to water–gas-salt ternary systems, our model demonstrates deviations smaller than 5.6 %. Alongside discussing the gas dissolution mechanism, this work emphasizes the adaptability of the model, informed by robust experimental and modeling data. The interpretations derived from modeling hydrogeological conditions are poised to enhance our understanding of hydrological processes, thereby assisting planners and water managers in achieving sustainable development and management of water resources. [ABSTRACT FROM AUTHOR]

• Experimental data on the sputtering coefficient of TiC and MAX phase Ti2AlC by noble gas ions Ne, Ar and Xe are summarized. • The sputtering coefficients of TiC and MAX phase Ti2AlC were calculated using a semi-empirical model. • A comparison of the experimental and calculated data showed satisfactory agreement. Information on sputtering coefficients of materials is necessary for coating deposition technologies and studying the interaction of ion beams and plasma with the surface. This paper summarizes experimental data on sputtering coefficients of TiC and MAX phase Ti 2 AlC by noble gas ions Ne, Ar, and Xe. The sputtering coefficients of TiC and MAX phase Ti 2 AlC were calculated using a semi-empirical model. A comparison of the experimental and calculated data showed satisfactory agreement. [ABSTRACT FROM AUTHOR]

Novel analytical approaches to determining the trapped 38Ar/36Ar ratio of gases contained within Martian meteorites are presented and applied to the Martian regolith breccia Northwest Africa (NWA) 7034 and paired stone NWA 11220. The resulting data indicate that extensive mass-dependent fractionation of atmospheric Ar may have occurred within 150 million years of planetary formation, ostensibly as a result of diffusion-limited hydrodynamic escape. The inferred fractional loss of Ar and lighter atmospheric constituents exceeds 50%. These data suggest that volatiles derived from planetary outgassing and/or impactors may dominate the present abundance of atmospheric Ar. [ABSTRACT FROM AUTHOR]

Hydrothermal alteration of oceanic crust represents a globally significant geochemical exchange between the crust and oceans, introducing volatile elements into the oceanic lithosphere and removing latent heat from crystallization. The extent to which hydrothermal systems penetrate the lower oceanic crust is debated and is significant for competing models of lower oceanic crust formation. In this study, we apply halogen and noble gas geochemistry in order to better understand the fluid sources and conditions during a hydrothermal alteration in a suite of gabbros sampled from drill cores in the mid‐ (hole GT3A) and lower‐ (hole GT1A) crust of the Oman Ophiolite. Low Br/Cl in mid‐crustal samples is controlled by amphibole formed at relatively high fluid/rock ratios. Lower crustal samples, meanwhile, have Br/Cl ranging from seawater to much higher values (<5 × 10−3). These require alteration at highly variable fluid/rock ratios from ∼1 to <0.01 in the lower crust. Noble gas isotopes also suggest alteration at relatively high and low fluid/rock ratios in the mid‐ and lower‐crust, respectively. Indicators of alteration and proxies for fluid/rock ratios (loss on ignition, Pb/Ce, Br/Cl, 40Ar/36Ar96Ma) vary systematically with distance from major fault zones in the lower crust with the strongest correlation in the least altered minerals. Together with age constraints derived from K‐Ar decay, these data indicate faults were major conduits, supplying seawater to the lower crust roughly contemporaneous with the formation of the ophiolite, and commencing at the magmatic stage. These results suggest that hydrothermal alteration of the lower crust is primarily controlled by major fault structures. Plain Language Summary: After a new oceanic crust is formed by volcanic activity at mid‐ocean ridges, it cools and reacts with circulating seawater. However, there is controversy over whether water penetrates to the lower oceanic crust, or whether this is cooled by conduction alone. This is important for theories of how the lower oceanic crust is formed. Investigating the lower crust is difficult since few samples have been recovered by deep seafloor drilling. However, ophiolites–sections of oceanic crust, uplifted onto continental margins during tectonic collisions–offer a potential window into processes in the deep oceanic crust. In this study, we use halogens and noble gases as chemical fingerprints for the origin of water in rocks from the Oman Ophiolite. We show that rocks from the mid‐oceanic crust and from the lower‐oceanic crust interacted with water under markedly different conditions and that the supply of water to the lower crust was very variable. Rocks close to large fractures cutting through the lower crust were altered by seawater ∼96 Myr ago. Further from these fractures, compositions are increasingly different from seawater and water was scarce. This provides important evidence that large fractures delivered water to the lower crust and may be important for cooling new oceanic crust globally. Key Points: Gabbros from the Oman Ophiolite record hydrothermal circulation in both the upper and lower oceanic crustHalogen and noble gas systematics suggest alteration under high and low fluid/rock ratiosFluid supply to the lower crust is variable and controlled by major fault zones commencing at the magmatic stage [ABSTRACT FROM AUTHOR]

Noble gases are ideal natural tracers to characterize the storage, migration and origin of fluids in geological environments. They are chemically and biologically inert and therefore are only partially separated by physical processes including the one related to the molecular diffusion phenomenon, so called kinetic fractionation. However, its precise quantification is difficult to achieve and its modeling is still open for debates. Thus, in this work, we have investigated the capability of simple and predictive models to estimate elemental and isotopic fractionation of noble gases in various geological fluids. To do so, molecular dynamics simulations on noble gases in water, gas and oil under sub-surface conditions were performed. These numerical results were found to be consistent with previous ones including experiments and molecular simulations when available, i.e. in water. Interestingly, it appeared that the widely used square-root law is able to provide a good prediction for elemental fractionation between noble gases in all solvents, except for helium. Such unexpected result from the theoretical point of view is explained by a peculiar relationship between the molecular mass and the molecular size of noble gas elements. Regarding the noble gas isotopic fractionation, the square-root law is shown to be unable to provide reasonable results, confirming recent experimental and numerical works. As expected, it has been noticed that the kinetic theory relation provides a reasonable estimate of the isotopic fractionation in gas whereas it deteriorates in water and in oil. Finally, using the previous findings, we propose a simple and predictive scheme for the isotopic fractionation of noble gases in all studied geo-fluids which is noticeably better than both the square-root and the kinetic theory relations. [ABSTRACT FROM AUTHOR]

The nature of inert gas bonding has always been an important topic. The bonds of noble gases cover the entire range of chemical bonds, from the weakest van der Waals forces, to non-covalent interactions, and to covalent bonds. Two types of methods were used to investigate the properties of chemical bonds in the inert gas inserted compound MNgBY with the transition metal M = Cu/Ag/Au and substituents Y = O/S/NH, one based on orbital analysis and the other based on electron density analysis. The NBO/NRT analysis shows that in these compounds there exists long-bonding striding the noble gas between the transitional metal and boron, similar to the noble gas insertion compounds HNgX of hydrohalide, and so a three-center four-electron bond exists among the M-Ng-B part. The electron density analyses show that the M-Ng bond between the metal Cu/Ag/Au and noble gas and the Ng-B bond in the Cu/Ag compounds are partial covalent but the Ng-B bond in Au compounds is a typical covalent bond. The large relativistic effects of Au cause the bonds in Au compounds shorter and stronger than the bonds in Ag/Cu compounds. The properties of the M-Ng and Ng-B bonds are not affected by substituents Y, but the bond lengths are sensitive to substituents. [ABSTRACT FROM AUTHOR]

Howardite-Eucrite-Diogenite(HED) clan meteorites come from Vesta, and are the important window for studying the formation and evolution of the solar system and terrestrial planets. The noble gases are the key means to understand the impact and thermal history of HED meteorites and Vesta. This research work presents a detail study of the noble gas isotopes, cosmic-ray exposure(CRE) age and nominal gas retention age for the unbrecciated eucrite NWA 11586. The noble gas isotopes indicate that the He, Ne and Ar of NWA 11586 are mainly cosmogenic and radiogenic. The CRE age of this meteorite(38. 5±4. 1 Ma) is consistent with the ages of major impact events(35-41 Ma) of HEDs, indicating that it may be launched from Vesta or V-type asteroids at -40 Ma. The U, Th-4He(T4) and 40K-40Ar(T40) gas retention ages of NWA 11586 are 1 019±41 Ma and 3 041±77 Ma respectively, the reset may be caused by late thermal events. [ABSTRACT FROM AUTHOR]

With the resurgence of interest in molten salt reactors, there is a need for new experiments and modeling capabilities to characterize the unique phenomena present in this fluid fuel system. A Versatile Experimental Salt Irradiation Loop (VESIL) is currently under investigation at Idaho National Laboratory to be placed in the Advanced Test Reactor (ATR). One of the key phenomena this proposed experiment plans to elucidate is fission product speciation in the fuel-salt and the subsequent effects this has on the fuel-salt properties, source term generation, and corrosion control. Specifically, noble gases (Xe & Kr) will bubble out to a plenum or off-gas system, and noble metals (Mo, Tc, Te, etc.) will precipitate and deposit in specific zones in the loop. This work extends the mass transfer and species interaction models in CTF (Coolant-Boiling in Rod Arrays--Two Fluids) and applies these models to give a preliminary estimation of fission product behavior in the proposed VESIL design. A noble metal-helium bubble mass transfer model is coupled with the thermal- hydraulic results from CTF to determine the effectiveness of this insoluble fission product (IFP) extraction method for VESIL. Amounts of IFP species extracted to the off-gas system and species distributions in VESIL after a 60-day ATR cycle are reported. [ABSTRACT FROM AUTHOR]

• Chang'e-5 lunar soil reveals a non-binary mixture. • Cometary and meteoritic component identified, adding to compositional diversity. • 134,136Xe depletion link to cometary isotopes rather than early atmospheric escape. • Previous models insufficient in explaining Kr and Xe fractionation in lunar soils. • Chang'e-5 contributes to billions of years of solar system history. The extent of volatile elements on the surface and interior of the Moon remains a highly debated topic. Previous studies conducted on bulk lunar soil samples and solar wind samples collected by the Genesis mission indicate a discernible isotope mass- or non-mass-dependent fractionation of krypton and xenon. However, a detailed investigation of these processes is missing, particularly in determining the possible incorporation of cometary volatiles in the lunar regolith. New lunar soil samples returned by the Chang'e-5 mission provide a chance to answer these key questions. In this study, noble gas isotopes of nine subsamples from a Chang'e-5 scooped sample were analysed through stepwise-heating and total fusion laser extraction. The results reveal that a simple binary mixture of solar wind and cosmogenic components did not explain alone the isotopic composition of these samples. The Xe data shows insignificant amounts of atmospheric Xe and presents clear evidence of cometary contributions to the lunar regolith, with a significant depletion of 134,136Xe compared to that in the solar wind. Additionally, a meteoritic component is identified. Compared to the Apollo results, our findings further validate the theory of Earth's atmospheric escape, substantiate the plausibility of these exogenous admixtures to elucidate the isotopic fractionation mechanisms of Kr and Xe within the lunar regolith, and provide novel insights into long-term constancy in the solar wind composition. [ABSTRACT FROM AUTHOR]

Determining solubilities of pure noble gases and He–CO 2 /CH 4 /N 2 gas mixtures in aqueous solutions is essential for various applications of noble gases in geological processes and for understanding the migration and accumulation of helium. This study developed two thermodynamic models for calculations of solubilities of five pure noble gases (i.e. He, Ne, Ar, Kr, and Xe) and He–CO 2 /CH 4 /N 2 gas mixtures in water and in aqueous NaCl solution. The first model is constructed by extending the improved SAFT-LJ equation of state (EOS) to five binary H 2 O-noble gas systems and four ternary systems (i.e. H 2 O–He–NaCl, H 2 O–He–CO 2 , H 2 O–He–CH 4 , and H 2 O–He–N 2). Both the non-ideality of aqueous phase and that of vapor phase of these systems were described using the improved SAFT-LJ EOS (φ - φ model). The second model is developed by modifying the gas solubility model proposed by Duan and his coworkers (one type of γ-φ model). The Pitzer theory was used to describe the non-ideality of aqueous phase and the improved SAFT-LJ EOS was used to describe the non-ideality of vapor phase. Both binary adjustable parameters of the improved SAFT-LJ EOS and parameters of the modified solubility model for pure gas were evaluated from experimental solubility data for pure gas. Both models are predictive for solubilities of gas mixtures since there is no need to evaluate their parameters from solubility data of gas mixtures. Comparisons of calculations of two models with experimental data show that both models can well represent solubilities and Henry's coefficients of five noble gases in pure water, as well as the solubility of He in aqueous NaCl solutions over a wide P - T range (273–600 K, 1–2000 bar for the solubility of He in water). The absolute average deviation of the improved SAFT-LJ EOS from experimental solubility data for five noble gases in pure water is 3.14% and that of the modified solubility model is 2.21%. Predictions of the improved SAFT-LJ EOS for Henry's coefficients for He in the He–CO 2 –H 2 O system are consistent with available experimental data. According to predictions of the improved SAFT-LJ EOS, Henry's coefficient for He in the He–CO 2 –H 2 O system is always lower than that in the He–H 2 O system at the same depth. Within 0–5 km depth, He solubility of He–CO 2 gas mixture is much greater than that of pure He at the same depth and He partial pressure, He solubility of He–N 2 mixture is a little greater than that of pure He, and He solubility of He–CH 4 mixture is between that of He–CO 2 mixture and that of He–N 2 mixture. A computer program for calculations of solubilities of pure noble gases and He–CO 2 /CH 4 /N 2 gas mixtures in pure water and in aqueous NaCl solutions can be obtained from the corresponding author via email. • Two thermodynamic models are developed to calculate solubilities of pure noble gases and He–CO 2 /CH 4 /N 2 gas mixtures. • Calculations of both models for solubilities of He–CO 2 /CH 4 /N 2 gas mixtures are predictive. • Both models can well represent solubilities of He in water and in aqueous NaCl solutions over a wide pressure-temperature range. [ABSTRACT FROM AUTHOR]

Helium is a critical, strategic and nonrenewable resource with limited reserves and unstable supplies. However, the helium sources and migration processes in petroliferous basins remain unclear. The Qaidam Basin features multiple reservoir layers, multiple genetic types of natural gas, and varying helium concentrations, providing an ideal natural laboratory for understanding the helium enrichment processes. Here, we present the original noble gas isotopic compositions and major gas components of 11 microbial gas samples from three gas layers in the Sebei No.1 gas field, eastern Qaidam Basin, China. The helium isotopic ratios range from 0.007 to 0.057 Ra, reflecting a predominantly crustal source. The Quaternary Sebei microbial gas features much lower helium concentration (0.0003–0.001%), 21Ne/22Ne ratio (0.031–0.034), and 40Ar/36Ar ratio (292–380) than thermogenic natural gases in the Qaidam Basin. The middle gas layer (II) of the Sebei gas field features higher 21Ne/22Ne and 40Ar/36Ar ratios than the top and bottom gas layers, displaying positive correlations with higher 4He groundwater concentrations before degassing, as calculated from 4He/20Ne ratios and 20Ne concentrations in air-saturated water. However, the correlations between the 4He contents in natural gas and the 21Ne/22Ne and 40Ar/36Ar ratios are unclear, suggesting that 4He dissolves into the groundwater system before degassing into a gas reservoir and that the variations in the 4He concentration in the gas phase are caused by the different levels of hydrocarbon dilution. Quantitative calculations of helium production revealed an external helium flux from the crustal basement except for the in-situ production from sedimentary strata even in this broadly-defined self-generating and self-preserving natural gas system. The helium resources in the Qaidam Basin are mainly distributed in tectonically active zones with uplifted pre-Jurassic basement rocks (providing sufficient helium sources), ancient groundwater systems (accumulating more helium) and suitable hydrocarbon production (acting as a carrier gas but diluting helium as slightly as possible). • Crust-derived features and poor resource prospects are revealed for helium in Qaidam microbial gases. • Noble gas isotopes correlations identify the exsolution process of dissolved helium from groundwater. • External helium flux from the crustal basement is an important contributor to helium enrichment. • Helium resources in the Qaidam Basin are mainly distributed in the tectonic zones with uplifted pre-Jurassic basement, ancient groundwater system and suitable hydrocarbon production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recent progress on Xe/Kr adsorption and separation using MOF adsorbents was reviewed. • Innovative strategies to boost Xe/Kr separation in MOF materials have been disclosed. • The importance of advanced computational studies in Xe/Kr separation were described. • The promises, challenges and next steps in MOFs for Xe/Kr separation were presented. Xenon (Xe) and krypton (Kr) separation is of great interest and plays an essential role in the industry. However, the identical properties and ultra-low concentrations of Xe and Kr are the main challenges related with the separation. Compared with the conventionally used cryogenic process, porous materials-based physical adsorption is promising for efficient and cost-effective separation processes. Herein, this review targets on recent development in the design, synthesis, and Xe/Kr capture and separation performances of metal–organic frameworks (MOFs). We thoroughly evaluate and discuss innovative strategies to enhance Xe/Kr capture and separation in MOFs. Along with the discussions of strategies and developments in MOF, a brief discussion about the advances of computational studies was also provided. Finally, future challenges and prospects of MOFs for Xe/Kr capture and separation are highlighted. We believe that this review will effectively guide readers in the design and selection of suitable MOFs for Xe/Kr adsorption and separation in future endeavors. [ABSTRACT FROM AUTHOR]

Surface water (SW) - groundwater (GW) interactions exhibit complex spatial and temporal patterns often studied using tracers. However, most natural and artificial tracers have limitations in studying SW–GW interactions, particularly if no significant contrasts in concentrations between SW and GW exist or can be maintained for long durations. In such context, (noble) gases have emerged as promising alternatives to add to the available tracer methods, especially with the recent development of portable mass spectrometers, which enable continuous monitoring of dissolved gas concentrations directly in the field. However, long-duration gas injection into river water presents logistical challenges. To overcome this limitation, we present an efficient and robust diffusion-injection apparatus for labeling large amounts of river water. Our setup allows fine, real-time control of the gas injection rate, and is suitable for extended injection durations and different gas species. To illustrate the effectiveness of our approach, we present a case study where helium (He) is used as an artificial tracer to study river water infiltration into an alluvial aquifer. Our injection of He as a tracer increased the dissolved He concentration of the river water by one order of magnitude compared to air-saturated water concentration for 35 days. This experiment yields valuable information on travel times from the river to a pumping well and on the mixing ratios between freshly infiltrated river water and regional groundwater. • Gas can be injected into rivers by diffusion through a semi-permeable membrane. • Diffusive gas injection is much more efficient than bubbling injection. • Portable mass spectrometers allow on-site continuous monitoring of the injected gases. • Infiltrating river water tagged with gas tracers was identified in groundwater. • Gas tracers provide valuable insight into aquifer heterogeneity. [ABSTRACT FROM AUTHOR]

The low thermodynamic cycle efficiency of the plasma synthetic jet actuator (PSJA) limits its application in flow control of supersonic aircraft. To improve the thermodynamic cycle efficiency of the PSJA, the energy conversion process of the PSJA under single discharge has been investigated by thermodynamic theory analysis and numerical simulation. The relations between thermodynamic cycle efficiency, specific heat ratio of gas medium, non-dimensional energy deposition and heating efficiency are established by theoretical deduction. Employing the three-dimensional nonconstant electrode center energy deposition model, energy conversion processes in the PSJA with six different gas mediums have been investigated. The simulation results show that the thermodynamic cycle efficiency of the PSJA with noble gas medium can exceed 3.2 %, which is 1.92 times of the PSJA with air medium due to their low volume specific heat. The maximum jet x-velocity of helium can reach 493.11 m/s, which is 3.3 times higher than that of air. Consequently, noble gases prove to be effective in improving the thermodynamic cycle efficiency of the PSJA and enhancing the strength of the synthetic jet. The advancement in the performance of the PSJA contributes to their enhanced capabilities in the field of active flow control. [ABSTRACT FROM AUTHOR]

In terms of averaged interactive fields, this research discovered a new relation between averaged binary potential field (ABPF) and sound speed. Then, the ABPFs of five noble gases were modeled using an extended Lennard–Jones potential function. The derived equation based on the ABPF and the model potential accurately described the sound speed data of the five noble gases from the National Institute of Standards and Technology. Later, the surface of the ABPF was determined from the data, which indicated that the ABPF principally exhibited the conventional Lennard–Jones' potential at low temperatures, but performed as a soft sphere potential at high temperatures. This temperature-based shift represents new knowledge regarding intermolecular interactions. The derived equation also provided a novel and practical method to calculate the sound speed from temperature and density. [ABSTRACT FROM AUTHOR]

Minoru Ozima describes important influences in his scientific life, from the trauma of World War II during adolescence to studying with such giants of Earth science as J. Tuzo Wilson. He benefited from international collaborations in helping to establish noble gas geochemistry as an important discipline that reveals much about the origin and evolution of our planet Earth. [ABSTRACT FROM AUTHOR]

This study has been performed for a 2-D fluid model of sodium photoplasma with noble gas mixtures in two-chamber cells. A source of photoexcitation of sodium resonance levels is located in the first (source) chamber. In contrast, plasma in the second (diffusion) chamber is formed due to the transport of charges from the first chamber. The created photoplasma at different excitation rate, gas type, and pressure have been studied. Unlike previous investigations of photoplasma based on the study of the temporal and spatial distributions of plasma parameters, in this research, the transport processes also have been investigated explicitly. The different flux components throughout the cell and the corresponding variations of electron temperature gradient affect the fluxes magnitude and, consequently, the electromotive force (EMF). Generally speaking, the findings from the model contribute to that, for the optimization of photoplasma cells, the study of transport processes must be focused. [ABSTRACT FROM AUTHOR]

Whether Earth's core is a significant repository of noble gases is an open question because their partitioning between liquid metal and silicate melt during core formation is poorly known. Here we calculated the He and Ar partition coefficients (D) between liquid Fe and MgSiO3 melt from 20 to 135 GPa at 5,000 K using ab initio molecular dynamics combined with thermodynamic integration. Our simulations show that DHe does not change significantly with pressure, while DAr increases strongly with increasing pressure. Furthermore, we found that the metal/silicate partitioning behaviors of He and Ar are controlled by their atomic size and the charge density properties of the host compositions. These results indicate that Earth's core is a plausible reservoir for 3He and could possibly account for the high 3He/4He ratios in the OIBs that associated with deep‐rooted plumes, but the core is unlikely to be a significant source for 36Ar. Plain Language Summary: The deep Earth source of primordial noble gases that are emitted at volcanoes is currently in active debate. Previous studies have mainly focused on the silicate mantle, but the metallic core is also a potential noble gas reservoir. In this work, by calculating the metal/silicate partition coefficients of He and Ar under conditions corresponding to core formation, we found that the concentration of He dissolved into Earth's core is much higher than that of Ar. Therefore, Earth's core could serve as a source for 3He degassing throughout geological time, but not as a source for 36Ar. Key Points: DHe is insensitive to pressure from 20 to 135 GPa, while DAr is positively dependent on pressureThe pressure dependences of DHe and DAr are controlled by the atomic size of the noble gas and the charge density of the host phaseEarth's core is a plausible source of 3He in the OIBs associated with plumes, but is unlikely to be a significant source of 36Ar [ABSTRACT FROM AUTHOR]

Closed Brayton cycle (CBC) having single-shaft, centrifugal type compressor is considered as an efficient energy-conversion option associated for gas-cooled reactor (GCR) heat source. In terrestrial power plants and space power systems noble gases are considered as an efficient working fluid for most of the GCR's and CBC engines. The effectiveness of various noble gases as working fluid in closed cycle power plants for the power conversion units is of imperative concern. Although pure helium is relatively difficult to compress nonetheless it is measured as the best coolants for closed Brayton cycle power plants due to its better transport properties. Due to compression properties, its use resulted in the requirement of more mass, bigger size, higher cost and relatively more dynamic problems of rotatory machines in energy conversion system. The mixture of xenon with helium up to a molecular weight of <40 g/mol resulted in an increase of the coefficient of heat transfer as well as the significant increase in the loading of the compressor. Therefore, performance analysis is conducted for a novel design of helium xenon centrifugal compressor. The performance analysis is conducted with different molecular weight mixtures of helium xenon using similarity criteria. It is concluded that the use of helium xenon 40 g/mol is the optimum choice for space applications and 15 g/mol for closed Brayton cycle terrestrial power plants. • Centrifugal compressor performance analysis conducted using similarity criteria. • First time numerical simulation conducted considering similarity parameters. • Concluded that use of HeXe 40 g/mol is the optimum choice for space applications. • For CBC terrestrial power plants HeXe 15 g/mol is the optimum choice. [ABSTRACT FROM AUTHOR]

The recent expansion of studies at hydrothermal submarine vents from investigation of abiotic methane formation to include abiotic production of organics such acetate and formate, and rising interest in processes of abiotic organic synthesis on the ocean-world moons of Saturn and Jupiter, have raised interest in potential Earth analogs for investigation of prebiotic/abiotic processes to an unprecedented level. The deep continental subsurface provides an attractive target to identify analog environments where the influence of abiotic carbon cycling may be investigated, particularly in hydrogeological isolated fracture fluids where the products of chemical water-rock reactions have been less overprinted by the biogeochemical signatures of the planet's surficial water and carbon cycles. Here we report, for the first time, a comprehensive set of concentration measurements and isotopic signatures for acetate and formate, as well as the dissolved inorganic and organic carbon pools, for saline fracture waters naturally flowing 2.4 km below surface in 2.7 billion year-old rocks on the Canadian Shield. These geologically ancient fluids at the Kidd Creek Observatory were the focus of previous investigations of fracture fluid geochemistry, microbiology and noble gas-derived residence times. Here we show the fracture waters of Kidd Creek contain high concentrations of both acetate and formate with concentrations from 1200 to 1900 µmol/L, and 480 to 1000 µmol/L, respectively. Acetate and formate alone account for more than 50–90% of the total DOC – providing a very simple "organic soup". The unusually elevated concentrations and profoundly 13C-enriched nature of the acetate and formate suggest an important role for abiotic organic synthesis in the deep carbon cycle at this hydrogeologically isolated site. A variety of potential abiotic production reactions are discussed, including a radiolytically driven H, S and C deep cycle that could provide a mechanism for sustaining deep subsurface habitability. Scientific discoveries are beginning to reveal that organic-producing reactions that would have prevailed on Earth before the rise of life, and that may persist today on planets and moons such as Enceladus, Europa and Titan, can be accessed in some specialized geologic settings on Earth that provide valuable natural analog environments for the investigation of abiotic organic chemistry outside the laboratory. [ABSTRACT FROM AUTHOR]

The luminescence spectra for noble gases and their binary mixtures excited by Ar ions with energies up to 70 MeV were examined in the range of 200–980 nm. The emissions at the transitions of heteronuclear ionic molecules ArXe+, ArKr+, KrXe+ were studied for a gas-mixture, with a wide variation in the percentage composition. The noble gases atomic spectra are dominated by lines of (n + 1)p-(n + 1)s-transitions (2p-1s in Pashen's notation); lines of d-(n + 1)p-transitions were also observed. The distribution of radiation over 2p-levels of noble gas atoms was also measured. The sharp predominance of the fraction of radiation from the levels 2p 2 of Ar, 2p 6 of Kr and 2p 5 of Xe is partially explained by the relatively small values of the rate constants for the deactivation of these levels, by own atoms. The mechanisms of levels population under the excitation of noble gases by ionizing radiation are discussed. [ABSTRACT FROM AUTHOR]

Brine samples from the wells in the Kashio mineral spring (an "Arima-type" hot spring at Ooshika-Mura, central Japan) were analyzed to determine the original chemical and isotopic compositions of the deep brine end-member before its dilution by meteoric water and to elucidate the origin of the end-member. The trends of variation between Cl, δD, and δ18O indicated the existence of a two-component mixing system and a systematic variation in the mixing ratio, which were mentioned in previous studies. By carefully tracking the variation in tritium (3H) and atmospheric noble gas in the brine, the Cl concentration in the end-member was determined to be 24,000 mg/L. This value is consistent with the result of previous studies. Based on the estimated composition and other related data, we inferred that the end-member originated from slab-derived fluid, which in turn may have undergone oxygen isotope exchange reactions with minerals. Although both the Arima and Kashio brines are considered to be derived from fluid dehydrated from the Philippine Sea slab, the chemical and isotopic compositions of the Kashio end-member are different from those of the Arima end-member. In particular, the Kashio end-member is characterized by low Cl concentration (~ 40% lower than that in the Arima end-member), low hydrogen isotope ratio, and low 3He/4He ratio (1.4 Ra). These results indicate that the chemical and isotopic compositions of the slab-derived fluid are different for each location. The significant difference in δD could reflect the difference in the dehydration depth. Finally, the low temperature and relatively low 3He/4He ratio of the brine end-member could be explained by its long residence time within the crust. [ABSTRACT FROM AUTHOR]

To investigate paleoclimate conditions and mean annual ground temperatures at the time of infiltration, concentrations of dissolved atmospheric noble gases, 18O, 2H and 14C were studied in Sfax deep groundwater in southeastern of Tunisia. Carbon-14 corrected ages are up to 40 Ka BP suggesting that most of this water infiltrated during Late Pleistocene. Noble gas temperatures (NGTs) clearly show the presence of water that infiltrated under much cooler conditions than at present. According to the NGT's, the mean annual temperature in this mid latitude coastal site during the last glacial maximum (LGM) was 5.5 ± 1.0 °C colder than during the Holocene. This transition of Holocene –Pleistocene is well marked by a depletion of oxygen-18 isotope composition by 1.5‰ when compared to the modern rain water signature. Furthermore, the amount of excess air, which is closely linked to the magnitude of groundwater table fluctuations, provides further information on drought and wet period alternations during Late Pleistocene in Northern Africa. [ABSTRACT FROM AUTHOR]

Volatile elements (e.g., H, C, N) have a strong influence on the physical and chemical evolution of planets and are essential for the development of habitable conditions. Measurement of the volatile and incompatible heavy halogens, Cl, Br, and I, can provide insight into volatile distribution and transport processes, due to their hydrophilic nature. However, information on the bulk halogen composition of martian meteorites is limited, particularly for Br and I, largely due to the difficulty in measuring ppb-level Br and I abundances in small samples. In this study, we address this challenge by using the neutron irradiation noble gas mass spectrometry (NI-NGMS) method to measure the heavy halogen composition of five olivine-phyric shergottite meteorites, including the enriched (Larkman Nunatak LAR 06319 and LAR 12011) and depleted (LAR 12095, LAR 12240, and Tissint) compositional end-members. Distinct differences in the absolute abundances and halogen ratios exist between enriched (74 to 136 ppm Cl, 1303 to 3061 ppb Br, and 4 to 1423 ppb I) and depleted (10 to 26 ppm Cl, 46 to 136 ppb Br, and 3 to 329 ppb I) samples. All halogen measurements are within the ranges previously reported for martian shergottite, nakhlite, and chassignite (SNC) meteorites. Enriched shergottites show variable and generally high Br and I absolute abundances. Halogen ratios (Br/Cl and I/Cl) are in proportions that exceed those of both carbonaceous chondrites and the martian surface. This may be linked to a volatile-rich martian mantle source, be related to shock processes or could represent a small degree of heavy halogen contamination (a feature of some Antarctic meteorites, for example). The differences observed in halogen abundances and ratios between enriched and depleted compositions, however, are consistent with previous suggestions of a heterogeneous distribution of volatiles in the martian mantle. Depleted shergottites have lower halogen abundances and Br and Cl in similar proportions to bulk silicate Earth and carbonaceous chondrites. Tissint in particular, as an uncontaminated fall, allows an estimate of the depleted shergottite mantle source composition to be made: 1.2 ppm Cl, 7.0 ppb Br, and 0.2 ppb I. The resultant bulk silicate Mars (BSM) estimate (22 ppm Cl, 74 ppb Br, and 6 ppb I), including the martian crust and depleted shergottite mantle, is similar to estimates of the bulk silicate earth (BSE) halogen composition. [ABSTRACT FROM AUTHOR]

Ureilites are equilibrated carbon-rich olivine-pyroxene rocks from the partially melted mantle of a large (>500 km diameter) heterogeneous parent body. Recently the ureilite parent body was interpreted as an incomplete mixture of material from two carbon-rich chondritic reservoirs, one (Mg-rich) with reduced iron, low Δ17O and low δ13C, and the other with oxidised iron, high Δ17O and high δ13C. Here we analyse noble gases (Ar, Kr and Xe) in six equilibrated (unbrecciated) ureilites from Northwest Africa (NWA 2236, NWA 7686, NWA 8049, NWA 8172, NWA 11032 and NWA 11368). We observe weak positive and negative correlations of Δ17O and Mg# with the elemental ratios of Ar/Xe and Kr/Xe, respectively, as well as a weak positive correlation of Mg# with the heavy isotopes of Xe. These correlations broadly support the idea of the two-component mixing hypothesis. Our analyses further suggest that the Mg-rich endmember was rich in Xe from presolar grains (HL-Xe) while the Mg-poorer component may have contained solar-derived noble gases. The observed correlations are less straightforward to reconcile with a recent model for the origin of the ureilite parent body, involving oxidation of metal by H 2 O from accreted ice with 'heavy' oxygen isotopes. [ABSTRACT FROM AUTHOR]

He+ impact single ionization cross sections of noble gases have been calculated in the Modified Binary Encounter Approximation. Accurate expression of σΔE (cross section for energy transfer ΔE) and Hartree-Fock velocity distributions for the target electrons have been used throughout the calculations. The present results of single ionization cross sections are in excellent agreement with the experimental observations throughout the energy range. We have also compared our calculated results of H+ impact ionization cross sections of noble gases with experimental measurement of Cavalcanti et al. Our present model is more suitable and gives reliable results. The calculated cross sections differs from the experimental results of H+ impact, this shows that more theoretical calculations is required to understand the dynamics of the system. [ABSTRACT FROM AUTHOR]

The migration of hydrocarbons from source-rock to reservoir is a critical stage in petroleum system evolution. However, as migration occurs along confined pathways over geologically rapid timescales it is challenging to place quantitative constraints on migration behaviour in terms of interaction with other basinal fluids, flux, and lengthscales associated with this process. Due to their inert nature, noble gases are ideal tracers of fluid provenance and physical processes in a variety of subsurface systems, and thus can serve as a potential geochemical indicator of migration distance. The recent proliferation of unconventional hydrocarbon production (i.e., production directly from source-rocks) allows for the analysis of fluids from these strata. Here we present noble gas data from natural gas samples produced from 27 related conventional and unconventional wells within the East Texas basin. These data enable characterisation of fluids during migration from source-rock to conventional reservoir. Unconventional gases and fluids are produced from the Haynesville shale (n = 8), and conventional gases and fluids are sourced from the overlying Cotton Valley (n = 5), Travis Peak (n = 9), and James Lime (n = 5) formations. Samples consist primarily of methane (>70%), with small contributions from longer-chain hydrocarbons, and other gases including CO 2 and N 2. Atmosphere-derived 36Ar, which is introduced into natural gas accumulations via interaction with groundwater during hydrocarbon generation and migration, is consistently higher in samples that have undergone a greater migration distance from the source interval. Thus, calculated volume ratios of gas-water interaction (V g /V w) show a far greater incidence of groundwater interaction in migrated samples. Radiogenically-produced 40Ar is also consistently elevated in migrated samples, despite these reservoirs being located in geologically younger strata. We derive the representative volume of rock required to produce the observed radiogenic 40Ar in each sample and show that samples that have migrated further have acquired radiogenic isotopes from larger volumes of rock. Furthermore, our volumetric parameters derived from atmospheric and radiogenic isotopes are consistent with a simple conceptual model of migration. We quantitatively apply this model to demonstrate that migration occurs along relatively localised pathways. Helium (3He/4He) and argon (40Ar/36Ar) isotopes are correlated and show elevated amounts of mantle-derived 3He and radiogenic 40Ar in migrated samples. We interpret this to represent mixing between a pristine source-rock signature and an endmember characterised by elevated 3He/4He and 40Ar/36Ar, likely representative of mantle-enriched groundwater circulating in the wider hydrogeological basin. Finally, we use an advection-diffusion model to show that enriched mantle 3He in the shallower strata and towards the southern edge of the basin can be explained by influx of mantle helium along the fault-bounded southern edge of the basin over timescales of millions of years. Together these approaches represent the first complete noble gas based characterization of a hydrocarbon system, sampling migration from source-rock to trap. We show conclusively that both atmospheric and radiogenic noble gases are entrained in the hydrocarbon phase during migration and that concentrations scale proportionally with migration distance, as greater volumes of groundwater and host rock are encountered. [ABSTRACT FROM AUTHOR]

Extraterrestrial materials have He and Ne isotopic compositions that are distinct from those of the Earth's surface. In order to track the extraterrestrial material accreted onto Earth during the Ediacaran period, we have analyzed the He and Ne isotopic composition of thirteen sedimentary rocks in the age range ~550–600 Ma, coming from the Huqf supergroup in Oman for which carbon and sulfur isotopic data have been characterized previously. 3He/4He ratios range between 0.006 ± 0.003 and 0.27 ± 0.01 R A , with R A being the atmospheric ratio. 3He/4He ratios show a positive relationship with 3He contents ranging between 0.6 and 31 × 10−13 cm3 STP·g−1. The 3He contents are within the literature data for 3 to 480 Myr old samples with evidence of IDP 3He (IDP for interplanetary dust particles), suggesting that extraterrestrial 3He is still retained in such old samples. 20Ne/22Ne ratios are close to or below the modern atmospheric ratio of 9.8 with the minimum value equal to 9.05 ± 0.03. 21Ne/22Ne ratios show a high range of variation, going from 0.0345 ± 0.0009 to 0.0935 ± 0.0023. The Ne isotopic compositions follow a nucleogenic trend similar to that of crustal fluids from the literature and predicted continental crust. However, one sample (3404) shows an unusual Ne isotopic composition with a lower 20Ne/22Ne at similar 21Ne/22Ne compared to the other samples. Two hypotheses can explain this singular Ne isotopic composition. First, it could be the result of a particular nucleogenic trend due to the presence of F-bearing minerals in this sample. SEM-EDS elemental mapping showed that although F- and Ca-rich phases, which could correspond to fluorites, are present in sample 3404. However, their abundance of ~0.15% seems too low to explain the unusual Ne isotopic composition. However, due to the high uncertainty of the calculations, we cannot totally rule out this hypothesis. Alternatively, the singular Ne isotopic composition could be due to the presence of a Ne-A component, a component characterizing pre-solar diamonds contained in chondrites. This would indicate that a major object impacted the Earth at the time the sediment was forming, between ~600 and ~550 Ma, which is coherent with the estimated age range of the Acraman impact in Australia. • Helium and neon isotopes have been measured in Huqf supergroup in Oman • Neon shows a peculiar isotopic signature suggesting either a major extraterrestrial impact or a peculiar enrichment in fluorine • Extraterrestrial 3He has been observed [ABSTRACT FROM AUTHOR]

Since 1998, there have been improvements in the capability to detect atmospheric radioxenon in the International Monitoring System operated by the Preparatory Commission of the Comprehensive Nuclear-Test-Ban Treaty Organization. The upgrades have resulted in next-generation versions of the radioxenon systems. This paper explores radioxenon data analysis improvements beyond the original radioxenon beta–gamma analysis equations that were formulated in 2000. Additionally, it provides recommendations to further improve analysis and refine the equations. The areas of improvement are described in terms of equations, physical detectors, and field-testing. These recommendations are provided with the intention of improving accuracy and precision of radioxenon measurements. [ABSTRACT FROM AUTHOR]

CO 2 sequestration in the form of carbonate minerals via alteration of oceanic crust and upper mantle is an important part of the global carbon cycle, but the annual rate of CO 2 mineralization is not well quantified. This study aimed to constrain groundwater ages within the Samail ophiolite, Sultanate of Oman. Such ages could provide upper bounds on the time required for ongoing low temperature CO 2 mineralization. While we were able to estimate apparent groundwater ages for modern waters, results from hyperalkaline boreholes and springs were disappointing. Waters from boreholes and hyperalkaline springs within the ophiolite were characterized using multiple environmental tracers including tritium (3H), noble gases (3He, 4He, Ne, Ar, Kr, Xe), stable isotopes (δ 18 O, δ 2 H), and chemical parameters (pH, Ca, Mg, DIC, etc.). Shallow peridotite groundwater and samples from boreholes near the mantle transition zone have a pH < 9.3, are 4-40 yrs old, have little to no non-atmospheric He accumulation, NGTs (noble gas temperatures) equivalent to the modern mean annual ground temperature, and stable isotopes within the range of current local precipitation. In contrast, hyperalkaline springs and deeper samples from peridotite boreholes have pH > 10, are pre-H-bomb (older than 1952), have significant non-atmospheric helium accumulation (30-70% of dissolved helium), often are isotopically heavier (enriched in δ 18 O), and can have NGTs 6-7 °C lower than the modern ground temperature. These differences suggest that groundwater in deep (>50 m) peridotite aquifers is considerably older than shallow groundwater in peridotite and water in deeper aquifers near the mantle transition zone. Unfortunately, how much older remains an open question. The low NGT of groundwater from one deep (300 m) peridotite borehole indicates it is probably glacial in origin. If so, it must date back to at least the late Pleistocene, the most recent glacial period; He accumulation suggests it could be from 20-220 ka. The inefficacy of this suite of environmental tracers to quantitatively estimate apparent groundwater age for hyperalkaline fluids necessitates the use of different techniques. Future work to constrain groundwater ages should utilize a packer system to isolate discrete depth intervals within boreholes and less common environmental tracers such as 39Ar and 81Kr. • Environmental tracers were used to evaluate water in peridotite aquifers in Oman. • Shallow peridotite and deeper mantle transition zone boreholes contain modern water. • pH > 11 boreholes and springs contain old water (apparent age still unknown). • pH > 11 water has pre-bomb 3H levels and accumulation of non-atmospheric He. • pH > 11 water can be glacial, with lower recharge temperatures and δ 18 O enrichment. [ABSTRACT FROM AUTHOR]

The sensitivity of planar multijunction thermal converters was significantly increased by filling the housing with noble gasses, preferably xenon or krypton. The performance was observed for almost two years, and no degradation of the sensitivity was found. Also, the frequency response of the ac–dc transfer difference remains unchanged at high frequencies and even improves below 40 Hz. Using the lowest at present manufacturable heater resistance of 90 $\Omega $ with the noble gas filling, ac–dc transfer at voltages down to almost 70 mV compared to about 100 mV in air becomes possible. [ABSTRACT FROM AUTHOR]