Fluids trapped as inclusions within minerals can be billions of years old and preserve a record of the fluid chemistry and environment at the time of mineralization. Aqueous fluids that have had a ...similar residence time at mineral interfaces and in fractures (fracture fluids) have not been previously identified. Expulsion of fracture fluids from basement systems with low connectivity occurs through deformation and fracturing of the brittle crust. The fractal nature of this process must, at some scale, preserve pockets of interconnected fluid from the earliest crustal history. In one such system, 2.8 kilometres below the surface in a South African gold mine, extant chemoautotrophic microbes have been identified in fluids isolated from the photosphere on timescales of tens of millions of years. Deep fracture fluids with similar chemistry have been found in a mine in the Timmins, Ontario, area of the Canadian Precambrian Shield. Here we show that excesses of (124)Xe, (126)Xe and (128)Xe in the Timmins mine fluids can be linked to xenon isotope changes in the ancient atmosphere and used to calculate a minimum mean residence time for this fluid of about 1.5 billion years. Further evidence of an ancient fluid system is found in (129)Xe excesses that, owing to the absence of any identifiable mantle input, are probably sourced in sediments and extracted by fluid migration processes operating during or shortly after mineralization at around 2.64 billion years ago. We also provide closed-system radiogenic noble-gas ((4)He, (21)Ne, (40)Ar, (136)Xe) residence times. Together, the different noble gases show that ancient pockets of water can survive the crustal fracturing process and remain in the crust for billions of years.
•Plasma neutralisers can significantly improve the global efficiency of a negative ion based neutral beam injector, which is a requirement for an injector to be used on a fusion reactor. A beam ...driven plasma neutraliser has many advantages over a neutraliser using alternative methods to create the plasma in the neutraliser. However, due to the recombination of electrons and molecular ions, an acceptable plasma density may not be achieved with D2 as the target gas in the neutraliser, and it has been suggested that the use of argon as the target gas should be considered. The advantages and inconveniences of using argon are discussed.•The equations governing the species change in a high energy H- beam traversing an argon plasma are identified and solved.•A careful evaluation of the cross sections needed to calculate the change in beam species and the resulting neutralisation efficiency of an argon plasma neutraliser has been carried out, and the cross sections given as a function of the incident beam energy over the appropriate energy range. Where no measurements have been found of some of the required cross sections, assumed values are used and the effect of different assumed values evaluated.•Calculated neutralisation efficiencies are given as a function of the ionisation fraction in the neutraliser as well as the necessary line densities.•The used of a beam driven argon plasma neutraliser as an upgrade of the ITER diagnostic neutral beam injector is discussed.
A beam driven plasma neutraliser (BDPN) has been proposed 1 as a relatively simple way to increase the efficiency of neutral beam injectors based on the acceleration and neutralisation of H- or D-. Initial calculations showed that sufficient levels of ionisation could be achieved with H2 or D2 as the initial gas target in the neutraliser if a plasma confinement time of the plasma in the neutraliser is >0.5 ms could be achieved. However, later calculations 2,3 show that the afore-mentioned results were very optimistic as the calculations did not take into account the recombination of molecular ions with electrons. Hence, it has been suggested 4 to use an argon (Ar) plasma as the molecular ion content in such a plasma will be negligible. The use of an Ar plasma neutraliser has been suggested previously 5–7, but few details have been given of the obtainable neutralisation efficiency, the necessary line density for that neutralisation efficiency, or of the calculations and cross sections used to deduce those quantities. This paper briefly discusses why Ar could be a good choice for a plasma neutraliser, then the reactions occurring between the H-/D- beam and the particles in the Ar plasma, and the available cross section data for those reactions. Subsequently, the differential equations for the change of the species in the beam as it traverses an Ar plasma are deduced and solved, and the solutions used to calculate the achievable neutralisation efficiency as a function of the line density in the neutraliser etc. Results are given of the neutralisation efficiency as a function of the degree of ionisation in the neutraliser, the required line density, and the species changes in the beam for accelerated H- beams with 100, 500 and 870 keV energies.
The protonated argon ion, {sup 36}ArH{sup +}, was recently identified in the Crab Nebula from Herschel spectra. Given the atmospheric opacity at the frequency of its J = 1-0 and J = 2-1 rotational ...transitions (617.5 and 1234.6 GHz, respectively), and the current lack of appropriate space observatories after the recent end of the Herschel mission, future studies on this molecule will rely on mid-infrared observations. We report on accurate wavenumber measurements of {sup 36}ArH{sup +} and {sup 38}ArH{sup +} rotation-vibration transitions in the v = 1-0 band in the range 4.1-3.7 μm (2450-2715 cm{sup –1}). The wavenumbers of the R(0) transitions of the v = 1-0 band are 2612.50135 ± 0.00033 and 2610.70177 ± 0.00042 cm{sup –1} (±3σ) for {sup 36}ArH{sup +} and {sup 38}ArH{sup +}, respectively. The calculated opacity for a gas thermalized at a temperature of 100 K and with a linewidth of 1 km s{sup –1} of the R(0) line is 1.6 × 10{sup –15} × N({sup 36}ArH{sup +}). For column densities of {sup 36}ArH{sup +} larger than 1 × 10{sup 13} cm{sup –2}, significant absorption by the R(0) line can be expected against bright mid-IR sources.
The kINPen® plasma jet was developed from laboratory prototype to commercially available non-equilibrium cold plasma jet for various applications in materials research, surface treatment and ...medicine. It has proven to be a valuable plasma source for industry as well as research and commercial use in plasma medicine, leading to very successful therapeutic results and its certification as a medical device. This topical review presents the different kINPen plasma sources available. Diagnostic techniques applied to the kINPen are introduced. The review summarizes the extensive studies of the physics and plasma chemistry of the kINPen performed by research groups across the world, and closes with a brief overview of the main application fields.
Aluminum microfoams are found to exhibit persistent sputtering yield reductions of 40%-80% compared to a flat aluminum surface under 100 to 300 eV argon plasma bombardment. An analytical model ...reveals a strong dependency of the yield on the foam geometry and plasma sheath. For foam pore sizes near or larger than the sheath thickness, the plasma infuses the foam and transitions the plasma-surface interactions from superficial to volumetric phenomena. By defining a plasma infusion parameter, the sputtering behavior of foams is shown to be separated into the plasma-facing and plasma-infused regimes. While plasma infusion leads to a larger effective sputtering area, geometric recapture of ejected particles facilitates an overall reduction in yield. For a given level of plasma infusion, the reductions in normalized yield are more pronounced at lower ion energies since angular sputtering effects enable more effective geometric recapture of sputterants.
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The surface composition of perovskite films is very sensitive to film processing and can deviate from the optimal, which generates unfavorable defects and results in efficiency loss in solar cells ...and slow response speed in photodetectors. An argon plasma treatment is introduced to modify the surface composition by tuning the ratio of organic and inorganic components as well as defect type before deposition of the passivating layer. It can efficiently enhance the charge collection across the perovskite–electrode interface by suppressing charge recombination. Therefore, perovskite solar cells with argon plasma treatment yield enhanced efficiency to 20.4% and perovskite photodetectors can reach their fastest respond speed, which is solely limited by the carrier mobility.
An argon plasma treatment is introduced to modify the surface trap types of halide perovskite, which improves the efficiency of a solar cell to 20.4%. The plasma treatment is shown as being also applicable to modify the perovskite single crystals, which enable the fastest response speed for single‐crystal photodetectors.
Irradiation of 2D sheets of transition metal dichalcogenides with ion beams has emerged as an effective approach to engineer chemically active defects in 2D materials. In this context, argon‐ion ...bombardment has been utilized to introduce sulfur vacancies in monolayer molybdenum disulfide (MoS2). However, a detailed understanding of the effects of generated defects on the functional properties of 2D MoS2 is still lacking. In this work, the correlation between critical electronic device parameters and the density of sulfur vacancies is systematically investigated through the fabrication and characterization of back‐gated monolayer MoS2 field‐effect transistors (FETs) exposed to a variable fluence of low‐energy argon ions. The electrical properties of pristine and ion‐irradiated FETs can be largely improved/recovered by exposing the devices to vapors of short linear thiolated molecules. Such a solvent‐free chemical treatment—carried out strictly under inert atmosphere—rules out secondary healing effects induced by oxygen or oxygen‐containing molecules. The results provide a guideline to design monolayer MoS2 optoelectronic devices with a controlled density of sulfur vacancies, which can be further exploited to introduce ad hoc molecular functionalities by means of thiol chemistry approaches.
Ion irradiation is used to controllably introduce sulfur vacancies in monolayer MoS2 sheets, which serve as channel material in field‐effect transistors. The evolution of critical device parameters is systematically investigated as a function of sulfur‐vacancy density. A vapor‐phase treatment, based on short linear thiolated molecules, enables a remarkable recovery of the functional properties of defective 2D MoS2.
In recent years, argon has been shown to exert neuroprotective effects in an array of models. However, the mechanisms by which argon exerts its neuroprotective characteristics remain unclear. ...Accumulating evidence imply that argon may exert neuroprotective effects via modulating the activation and polarization of microglia/macrophages after ischemic stroke. In the present study, we analyzed the underlying neuroprotective effects of delayed argon application until 7 days after reperfusion and explored the potential mechanisms.
Twenty-one male Wistar rats underwent transient middle cerebral artery occlusion or sham surgery randomly for 2 h using the endoluminal thread model. Three hours after transient middle cerebral artery occlusion induction and 1 h after reperfusion, animals received either 50% vol Argon/50% vol O
or 50% vol N
/50% vol O
for 1 h. The primary outcome was the 6-point neuroscore from 24 h to d7 after reperfusion. Histological analyses including infarct volume, survival of neurons (NeuN) at the ischemic boundary zone, white matter integrity (Luxol Fast Blue), microglia/macrophage activation (Iba1), and polarization (Iba1/Arginase1 double staining) on d7 were conducted as well. Sample size calculation was performed using nQuery Advisor + nTerim 4.0. Independent t test, one-way ANOVA and repeated measures ANOVA were performed, respectively, for statistical analysis (SPSS 23.0).
The 6-point neuroscore from 24 h to d7 after reperfusion showed that tMCAO Ar group displayed significantly improved neurological performance compared to tMCAO N
group (p = 0.026). The relative numbers of NeuN-positive cells in the ROIs of tMCAO Ar group significantly increased compared to tMCAO N
group (p = 0.010 for cortex and p = 0.011 for subcortex). Argon significantly suppressed the microglia/macrophage activation as revealed by Iba1 staining (p = 0.0076) and promoted the M2 microglia/macrophage polarization as revealed by Iba1/Arginase 1 double staining (p = 0.000095).
Argon administration with a 3 h delay after stroke onset and 1 h after reperfusion significantly alleviated neurological deficit within the first week and preserved the neurons at the ischemic boundary zone 7 days after stroke. Moreover, argon reduced the excessive microglia/macrophage activation and promoted the switch of microglia/macrophage polarization towards the anti-inflammatory M2 phenotype. Studies making efforts to further elucidate the protective mechanisms and to benefit the translational application are of great value.
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