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With the industrialisation of nanoparticle manufacture, the pervasive incursion of nanoparticles into the environment, the need to characterise nano-scale pharmaceuticals and living systems in replicated in vivo conditions, the continuing development of new theories to describe the electro-kinetic behaviour of nano-particles in representative ionic strengths and numerous other applications, there is an urgent requirement to provide simple and effective experimental tools to validate these models and explore new systems. Micro-electrophoresis implemented with a diffusion barrier, which isolates the dispersed phase from the electrode surface, is demonstrated as enabling such measurements for the first time, preventing the catastrophic outgassing, precipitation and sample degradation observed when the dispersed phase is in close proximity to the electrode surface. Using a measurement of a few minute's duration in a standard laboratory light scattering instrument we reproduce the theoretically predicted phenomena of asymptotic, non-zero electrophoretic mobility with increasing ionic strength, the cationic Hofmeister series dependency, charge inversion and a continuously decreasing variation in mobility with pH as molarity increases. Standard operating procedures are developed and included to encourage further work. [ABSTRACT FROM AUTHOR]

Effects of dynamic wall outgassing on divertor plasma during an edge localized mode (ELM)-like heat pulse are modeled using the newly coupled edge plasma code UEDGE and wall reaction-diffusion code FACE. Different divertor regimes are simulated depending on the degree of the plasma detachment. It is shown that hydrogen outgassing from the divertor target plate induced by ELM pulse in the semi-detached regime can trigger deep plasma detachment. The induced detachment does not spontaneously reverse after the pulse due to ineffective implantation of low energy plasma hydrogen in the target material. We also show that plasma neutrals play an essential role in heat transport in a detached divertor. The modeled hydrogen dynamics in the wall material demonstrates that the heat pulse leads to enhanced hydrogen transport toward the wall bulk. [ABSTRACT FROM AUTHOR]

To prevent zinc vapor–induced spatter, pre-scanning was proposed as a means to evaporate the zinc coating prior to the welding process. This paper studied the effectiveness of various pre-scanning parameters such as beam defocusing distance, beam power, scanning velocity, and geometric scanning path. The gap conditions during pre-scanning were also studied in regard to outgassing of zinc vapor during pre-scanning. To complement the experimental testing, a thermomechanical numerical model was developed and validated by comparing the size of the predicted versus the physical fusion zone. The effectiveness of the pre-scanning process was evaluated by examining the temperature distribution at both the top and faying surfaces of the stack-up under the condition that the temperature at the faying interface is greater than the zinc boiling point through the entire pre-scanning process to prevent condensation of the zinc vapor back onto the faying interface. The study found that no gap at the faying interface should be allowed with the use of pre-scanning to ensure an effective heat conduction across the faying interface. When the pre-scanning path is spiral or circular, the beam translation should initiate at the center and work outward towards the periphery. The line energy is suggested to decrease as the radius increases to avoid excessive accumulation of heat in the path center. [ABSTRACT FROM AUTHOR]

Water samples were collected hourly at a small stream on Jeju Island, South Korea in both wet and dry seasons to identify the factors affecting dissolved inorganic carbon (DIC) and its isotopic composition (δ13CDIC). In the wet season, dissolved oxygen (DO) displayed a diurnal pattern with lower values in samples collected between sunset and sunrise compared to samples at other times. Likewise, a diurnal pattern was observed for pH, DIC and δ13CDIC. An overall negative correlation between DIC and DO indicated that photosynthesis and respiration in the stream are the main factors controlling DIC concentration and behavior. Notably, samples at night displayed two trends in plots of DO and DIC, with different δ13CDIC values. This was due to CO2 outgassing from the stream to the ambient atmosphere. Partial pressure of CO2 (pCO2), calcite saturation index (SIcalcite), and equilibrium isotope fractionation between HCO3− and CO2 gas were related to the δ13CDIC value, verifying that photosynthesis and respiration determined DIC behavior. In addition to microbial activity, CO2 outgassing contributed to DIC in the stream after respiration and before photosynthesis. In comparison, δ13CDIC values in the dry season were similar to those in the wet season but showed no clear relationship with pCO2 and SIcalcite. Unlike the wet season, this indicated that in the dry season, photosynthesis and respiration are not the dominant processes and that CO2 exchange between the atmosphere and water is more important in determining DIC. [ABSTRACT FROM AUTHOR]

Rivers are a major source of nutrients, carbon and alkalinity to the global ocean. In this study, we firstly estimate pre-industrial riverine loads of nutrients, carbon and alkalinity based on a hierarchy of weathering and terrestrial organic matter export models, while identifying regional hotspots of the riverine exports. Secondly, we implement the riverine loads into a global ocean biogeochemical model to describe their implications for oceanic nutrient concentrations, net primary production (NPP) and air–sea CO2 fluxes globally, as well as in an analysis of coastal regions. Thirdly, we quantitatively assess the terrestrial origins and the long-term fate of riverine carbon in the ocean. We quantify annual bioavailable pre-industrial riverine loads of 3.7 Tg P, 27 Tg N, 158 Tg Si and 603 Tg C delivered to the ocean globally. We thereby identify the tropical Atlantic catchments (20 % of global C), Arctic rivers (9 % of global C) and Southeast Asian rivers (15 % of global C) as dominant suppliers of carbon for the ocean. The riverine exports lead to a simulated net global oceanic CO2 source of 231 Tg C yr -1 to the atmosphere, which is mainly caused by inorganic carbon (source of 183 Tg C yr -1) and by organic carbon (source of 128 Tg C yr -1) riverine loads. Additionally, a sink of 80 Tg C yr -1 is caused by the enhancement of the biological carbon uptake from dissolved inorganic nutrient inputs from rivers and the resulting alkalinity production. While large outgassing fluxes are simulated mostly in proximity to major river mouths, substantial outgassing fluxes can be found further offshore, most prominently in the tropical Atlantic. Furthermore, we find evidence for the interhemispheric transfer of carbon in the model; we detect a larger relative outgassing flux (49 % of global riverine-induced outgassing) in the Southern Hemisphere in comparison to the hemisphere's relative riverine inputs (33 % of global C inputs), as well as an outgassing flux of 17 Tg C yr -1 in the Southern Ocean. The addition of riverine loads in the model leads to a strong NPP increase in the tropical west Atlantic, Bay of Bengal and the East China Sea (+ 166 %, + 377 % and + 71 %, respectively). On the light-limited Arctic shelves, the NPP is not strongly sensitive to riverine loads, but the CO2 flux is strongly altered regionally due to substantial dissolved inorganic and organic carbon supplies to the region. While our study confirms that the ocean circulation remains the main driver for biogeochemical distributions in the open ocean, it reveals the necessity to consider riverine inputs for the representation of heterogeneous features in the coastal ocean and to represent riverine-induced pre-industrial carbon outgassing in the ocean. It also underlines the need to consider long-term CO2 sources from volcanic and shale oxidation fluxes in order to close the framework's atmospheric carbon budget. [ABSTRACT FROM AUTHOR]

Inland waters frequently exhibit carbon dioxide (CO2) supersaturation and potentially serve as CO2 emitters to the atmosphere. However, study on water–air interface CO2 exchange from small rivers remains limited, which causes large uncertainty of local and global carbon budgets. Based on seasonal field measurements, carbonate equilibria (CO2SYS program) and empirical models of gas transfer velocity (k value), we investigated the CO2 partial pressure (pCO2), CO2 emission and its controlling factors in the Longchuan River, a subtropical river in the Dry-hot Valley Region of Southwest China. Over 88% of samples were found to be oversaturated with atmospheric CO2, and the mean pCO2 ranged from 1497 ± 1415 μatm (dry period) to 1734 ± 1648 μatm (post-wet period). With the calibrated k values of 43.4–80.5 cm/h, the CO2 emission rates were estimate at 443–514 mmol/m2/day. We highlighted that long-term gully erosion enhanced the buffering capacity of carbonates in the aquatic environment and resulted in seasonal differences in riverine pCO2. Intensive agricultural practices could alter the pCO2 and further stimulate CO2 emissions. There were positive correlations of pCO2-elevation and pCO2-DOC in the initial-wet period but not in the dry period. This study suggests that extreme soil erosion and anthropogenic activities can regulate environmental variables and thus greatly affect the riverine CO2 outgassing. Our findings provide key insights into the understandings of dynamic controls on riverine pCO2 and CO2 outgassing under global change. [ABSTRACT FROM AUTHOR]

Much of Earth's carbon resides in the "deep" realms of our planet: sediments, crust, mantle, and core. The interaction of these deep reservoirs of carbon with the surface reservoir (atmosphere and oceans) leads to a habitable surface environment, with an equitable atmospheric composition and comfortable range in temperature that together have allowed life to proliferate. The Earth in Five Reactions project (part of the Deep Carbon Observatory program) identified the most important carbon-bearing reactions of our planet, defined as those which perhaps make our planet unique among those in our Solar System, to highlight and review how the deep and surface carbon cycles connect. Here we review the important reactions that control the concentration of carbon dioxide in our atmosphere: outgassing from magmas during volcanic eruptions and during magmatic activity; and uptake of CO2 by alkaline surface waters. We describe the state of our knowledge about these reactions and their controls, the extent to which we understand the mass budgets of carbon that are mediated by these reactions, and finally, the implications of these reactions for understanding present-day climate change that is driven by anthropogenic emission of CO2. [ABSTRACT FROM AUTHOR]

Polyimide foils were irradiated with energetic Kr (740 MeV) and Pb (890 MeV) ions at cryogenic temperature (12 K). Beam-induced degradation processes were monitored by residual gas analysis and online infrared spectroscopy. The outgassing components observed at low irradiation temperatures differ in quantity but are similar in mass distribution to those identified at room temperature exposure. Besides CO as major volatile fragment, a significant contribution of short hydrocarbons like C2Hx is released. In situ infrared spectroscopy indicates accumulation of CO and CO2 molecules at 12 K in the foils. During heat-up cycles, most of these frozen gases become mobile and outgas at a temperature between 35 and 55 K. The study is motivated by the application of polyimide foils as insulating material in high radiation environment of the future accelerator facility for antiproton and ion research (FAIR). [ABSTRACT FROM AUTHOR]

In the OLED panel, we have been investigated to understand diffusion behaviors of light element in various perspectives. It has evaluated by using advanced analytical tools such nano‐SIMS. we could find the diffused hydrogen from insulating film in channel area of bad sample. Increased hydrogen is directly attributed to the negative Vth shift. Also, we make the cross sectional sample and find the diffusion source of internal outgassing using the cross‐sectional Ion Mapping analysis method. [ABSTRACT FROM AUTHOR]

Erratum: "The moisture outgassing kinetics of a silica reinforced polydimethylsiloxane" [J. Chem. Phys. (10)-(12) shows HT ht , where the correct expression should be HT ht . This typo (capital I T i should be used to represent temperature) has no impact on the results presented in the article. [Extracted from the article]

Comets are considered to be some of the most pristine and unprocessed Solar system objects accessible to in situ exploration. Investigating their molecular and elemental composition takes us on a journey back to the early period of our Solar system and possibly even further. In this work, we deduce the bulk abundances of the major volatile species in comet 67P/Churyumov-Gerasimenko, the target of the European Space Agency's (ESA) Rosetta mission. The basis are measurements obtained with the ROSINA instrument suite on board the Rosetta orbiter during a suitable period of high outgassing near perihelion. The results are combined with both gas and dust composition measurements published in the literature. This provides an integrated inventory of the major elements present in the nucleus of 67P/Churyumov-Gerasimenko. Similar to comet 1P/Halley, which was visited by ESA's Giotto spacecraft in 1986, comet 67P/Churyumov-Gerasimenko also shows near-solar abundances of oxygen and carbon, whereas hydrogen and nitrogen are depleted compared to solar. Still, the degree of devolatilization is lower than that of inner Solar system objects, including meteorites and the Earth. This supports the idea that comets are amongst the most pristine objects in our Solar system. [ABSTRACT FROM AUTHOR]

Copyright of Vakuum in Forschung und Praxis is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Identifying processes within the Earth System that have modulated atmospheric pCO2 during each glacial cycle of the late Pleistocene stands as one of the grand challenges in climate science. The growing array of surface ocean pH estimates from the boron isotope proxy across the last glacial termination may reveal regions of the ocean that influenced the timing and magnitude of pCO2 rise. Here we present two new boron isotope records from the subtropical‐subpolar transition zone of the Southwest Pacific that span the last 20 kyr, as well as new radiocarbon data from the same cores. The new data suggest this region was a source of carbon to the atmosphere rather than a moderate sink as it is today. Significantly higher outgassing is observed between ~16.5 and 14 kyr BP, associated with increasing δ13C and [CO3]2− at depth, suggesting loss of carbon from the intermediate ocean to the atmosphere. We use these new boron isotope records together with existing records to build a composite pH/pCO2 curve for the surface oceans. The pH disequilibrium/CO2 outgassing was widespread throughout the last deglaciation, likely explained by upwelling of CO2 from the deep/intermediate ocean. During the Holocene, a smaller outgassing peak is observed at a time of relatively stable atmospheric CO2, which may be explained by regrowth of the terrestrial biosphere countering ocean CO2 release. Our stack is likely biased toward upwelling/CO2 source regions. Nevertheless, the composite pCO2 curve provides robust evidence that various parts of the ocean were releasing CO2 to the atmosphere over the last 25 kyr. Key Points: Boron‐isotope‐based pH reconstructions indicate that the subtropical/subpolar Southwest Pacific was a source of CO2 during the last 19 kaMajor CO2 outgassing from the Southwest Pacific was associated with enhanced ventilation of intermediate waters between 16.5 and 14 kyr BPA surface pH/pCO2 composite derived from 12 planktic δ11B records shows widespread CO2 release from the ocean during the last deglaciation [ABSTRACT FROM AUTHOR]

Measurements from the Rosetta mission have shown a multitude of nonthermal electron distributions in the cometary environment, challenging the previously assumed plasma interaction mechanisms near a cometary nucleus. In this paper, we discuss electron trapping near a weakly outgassing comet from a fully kinetic (particle-in-cell) perspective. Using the electromagnetic fields derived from the simulation, we characterize the trajectories of trapped electrons in the potential well surrounding the cometary nucleus and identify the distinguishing features in their respective velocity and pitch angle distributions. Our analysis allows us to define a clear boundary in velocity phase space between the distributions of trapped and passing electrons. [ABSTRACT FROM AUTHOR]

A large set of micro- and nanodevices requires hybrid vacuum packaging at the wafer level to optimize their performance and lifetime. When the temperature of the packaging fabrication process is limited, getter films must be integrated into the packaging cavity to obtain a low and sustainable pressure. In this paper, gas generation and residual gases inside a wafer-level package, as well as the main getter alloy films and multilayers investigated previously, are reviewed. An emphasis is put on the effect of a gaseous environment on the physicochemical mechanisms involved in getter film activation and gas sorption. A large outgassing occurs during the packaging fabrication process. It produces a gas load larger than or similar to that generated during the entire lifetime of the device at room temperature. The resulting partial pressures of gases in a micropackage are quite different from those found in ultrahigh vacuum during characterization by surface analysis techniques and when getter films are used in accelerators. Consequently, in micropackages, activation and sorption steps can no longer be analyzed separately and surface oxidation and/or oxygen bulk diffusion during activation should be taken into account. It is thus recommended to use and develop complementary characterization techniques that enable the investigation of surface and bulk phenomena at various temperatures, pressures, and gas mixtures for the assessment of getter films for vacuum packaging. [ABSTRACT FROM AUTHOR]

The Torr-Seal gluing method was often used to attach the nanofabricated leak elements to the vacuum system. However, such new leaks are difficult to be applied in ultrahigh vacuum due to the strong outgassing effect of Torr-Seal. To eliminate such issue and achieve enclosed sealing of leak element and CF flange, a new nanofluidic channels type leak assembly has been fabricated based on the glass frit sealing method. Nanofluidic channels with a feature dimension of ∼162 nm were enclosed as a leak element using reactive ion etching and silicon direct bonding processes. The outgassing rate of the leak assembly was analyzed by a residual gas analyzer. The results exhibit that the outgassing rate with the glass paste is 1 order of magnitude lower than that with the Torr-Seal. The flow conductance of helium, nitrogen, and argon was characterized by the difference method. It is found that the measured values are close to the calculated values and the molecular flow is achieved from vacuum to atmosphere pressure. [ABSTRACT FROM AUTHOR]

Outgassing remains a pertinent issue for high power applications and is exacerbated by the high field driven, localized heating environments commonly encountered. Here, molecular dynamics simulations are performed for a simple model-based assessment of outgassing from electrodes. Our results of temperature dependent diffusion coefficients for hydrogen in copper agree well with experimental reports over a wide range spanning 300 K to 1330 K. Separate results are also obtained for transport of hydrogen to ascertain whether a grain-boundary would facilitate channeled transport or work to impede flow by clustering the gas atoms. Finally, the use of a tungsten overlayer on copper is evaluated as a material-based strategy for mitigating outgassing. It is demonstrated that a few monolayers of tungsten coating on the outer surface can be effective in significantly reducing outdiffusion at 700 K. [ABSTRACT FROM AUTHOR]

PM2.5 is an important global air pollution issue. PM2.5 causes various problems on the environment and human health. Even though PM2.5 of the outdoor air is eliminated by particulate air filters, the chemicals adsorbed on the filtered PM2.5 can be outgassed and introduced into the semiconductor manufacturing facilities and processes, thus causing defects on the semiconductor chips by producing particles and haze as airborne molecular contamination. Therefore, estimating the amount of the outgassing from PM2.5 is a very important factor to control gaseous contaminants in the semiconductor industry. In this paper, the PM2.5 samples at different PM2.5 mass loadings were collected in Xi’an, China and evaluated using the soft X-ray radiolysis method for determining the relation between the outgassing and the PM2.5 mass loading. The PM2.5 samples were also analyzed by several methods for quantifying organic and elemental carbons, water soluble ions, and organic compounds in the PM2.5 samples. The outgassing measured by the soft X-ray method increased linearly with the PM2.5 mass loading, and the chemical analyses explained that the organic carbon (OC) was dominantly detected by the soft X-ray method in the current study. Moreover, the sampling location of the PM2.5 affected on the organic compounds of the PM2.5. [ABSTRACT FROM AUTHOR]

Copyright of Vakuum in Forschung und Praxis is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There is growing evidence that outgassing through transient fracture networks exerts an important control on conduit processes and explosive‐effusive activity during silicic eruptions. Indeed, the first modern observations of rhyolitic eruptions have revealed that degassed lava effusion may depend upon outgassing during simultaneous pyroclastic venting. The outgassing is thought to occur as gas and pyroclastic debris are discharged through shallow fracture networks within otherwise low‐permeability, conduit‐plugging lava domes. However, this discharge is only transient, as these fractures become clogged and eventually blocked by the accumulation and sintering of hot, melt‐rich pyroclastic debris, drastically reducing their permeability and creating particle‐filled tuffisites. In this study we present the first published permeability measurements for rhyolitic tuffisites, using samples from the recent rhyolitic eruptions at Chaitén (2008–2009) and Cordón Caulle (2011–2012) in Chile. To place constraints on tuffisite permeability evolution, we combine (1) laboratory measurements of the porosity and permeability of tuffisites that preserve different degrees of sintering, (2) theoretical estimates on grainsize‐ and temperature‐dependent sintering timescales, and (3) H2O diffusion constraints on pressure‐time paths. The inferred timescales of sintering‐driven tuffisite compaction and permeability loss, spanning seconds (in the case of compaction‐driven sintering) to hours (surface tension‐driven sintering), coincide with timescales of diffusive degassing into tuffisites, observed vent pulsations during hybrid rhyolitic activity (extrusive behavior coincident with intermittent explosions), and more broadly, timescales of pressurization accompanying silicic lava dome extrusion. We discuss herein the complex feedbacks between fracture opening, closing, and sintering and their role in outgassing rhyolite lavas and mediating hybrid explosive‐effusive activity. Key Points: Permeability of variably sintered tuffisites from Chaitén and Cordón Caulle is between 10−16 and 10−15 m2Surface tension and compaction‐driven sintering timescales are between 2 min and 13.6 h and between 3.5 s and 5 min, respectivelyInferred timescales of sintering‐driven tuffisite compaction coincide with observed vent pulsations during hybrid rhyolitic activity [ABSTRACT FROM AUTHOR]

Outgassing of volcanic systems is a ubiquitous phenomenon. Yet the mechanisms facilitating gas escape from vesiculating magmas and lavas remain poorly understood. Pervasive outgassing is thought to depend on the efficient and abundant formation of permeable pathways. Here we present results from experiments designed to identify the conditions and mechanisms needed to form such permeable pathways. We use a foamed silicate melt (FOAMGLAS®) in our experiments as a proxy for natural vesicular melts. FOAMGLAS® cores are compressed under a range of temperatures and strain rates, and results are evaluated against the state of melt relaxation (parameterized using the Deborah number). We find that foam microstructure and rheological and outgassing behaviors evolve with strain and as a function of melt relaxation state. Relaxed melt foams harden during deformation but remain impermeable. As foams become less relaxed at higher strain rate and/or melt viscosity, they show complex responses to deformation (strain weakening and hardening) yet remain impermeable. Strain localization and formation of high‐permeability bands occur only in highly strained, unrelaxed foams. However, these bands are thin and oriented perpendicular to the principal stress, resulting in limited outgassing. Permeable pathways do not readily form in foams; rather, high‐porosity melts are "persistently impermeable." Our results imply that vesicular silicic lavas may not outgas as efficiently as previously thought. Instead, sustained impermeability allows the lava to maintain low effective viscosities, and to flow extended distances. In addition, pore pressures may rise in deforming impermeable lavas, perhaps priming the lava for later explosive behavior. Key Points: High‐temperature deformation experiments on cores of FOAMGLAS® explore melt foam rheological and outgassing behaviorsDeforming melt foams show strain weakening, hardening, and localization, but undergo little or no outgassing (i.e., are impermeable)Crystal‐free bubble‐rich silicic lavas outgas inefficiently, allowing for sustained low effective viscosities and efficient transport [ABSTRACT FROM AUTHOR]

Ultra-high vacuum (UHV) in high-energy particle accelerator is essential to ensure the required beam lifetime. In the present communication, the UHV characterization of vacuum chambers coated with a thin film of carbon is reported. Recently, such coatings have attracted the interest for their low secondary electron yield and, consequently, their capability to eradicate electron cloud in high-intensity proton beam accelerators. Carbon was coated on stainless steel beam pipes by magnetron sputtering. Coated and uncoated stainless steel pipes ( C ssp and UC ssp ) were compared based on their outgassing rates and electron-stimulated desorption yields. The study conclusively verified that magnetron-sputtered carbon coatings are compatible with the requirements of most of the modern particle accelerators. [ABSTRACT FROM AUTHOR]

Volume transport in the presence of fully resolved convection and turbulence is investigated in a reentrant channel model of the Southern Ocean. The response of the meridional overturning and zonal transport to variations in wind and buoyancy forcing is quantified. Our simulations show two overturning cells—a buoyancy‐driven lower cell and a wind‐driven upper cell. The lower overturning cell is much larger in meridional extent and magnitude than the upper cell. The mean component of the overturning transport is smaller than the fluctuating component in the lower overturning cell, indicating that transport is dominated by eddies and/or turbulent convective flow. In contrast, the upper cell can be primarily described as a mean flow (indicating minimal eddy compensation). Both cells strengthen with increasing winds, with the upper cell being more sensitive to increasing wind intensity than the lower cell. Scaling for the mean upper overturning is also derived and matches previous theories which predict a linear sensitivity of the upper cell to wind. Zonal transport remains insensitive to increasing wind stress, suggesting that the system is eddy saturated when turbulence and eddies are resolved. These results suggest that fine‐scale flows control zonal transport and abyssal meridional overturning in the Southern Ocean, while wind stress drives the upper meridional overturning transport, highlighting the importance of accurately characterizing turbulence and convection in large‐scale models. Key Points: We analyze zonal and meridional transport in an idealized Southern Ocean model with resolved convection and turbulenceResolving all scales of motion, zonal transport is insensitive to wind stress, indicating eddy saturationAbyssal meridional overturning is greater than upper overturning, enabled by fluctuating flows, and increases with enhanced wind stress [ABSTRACT FROM AUTHOR]

The Chelyabinsk meteorite sample of type LL5 was subjected to calcination in the specially constructed instrument in the temperature range 200–800°C in increments of 100°C. The composition of the obtained volatile constituents was examined on a chromatograph. Detected were: CO2, H2O, and N2 in concentrations of 5–40 μg/g of the sample; H2, CO, CH4, and H2S in concentrations of 0.1–2.0 μg/g. By observing changes in the selected component concentrations over time (up to 90 minutes), it was concluded that chemical reactions in the system between volatile components occur directly during outgassing. [ABSTRACT FROM AUTHOR]

Mangrove‐ and saltmarsh‐dominated estuaries have high rates of organic carbon burial. Here, we estimate soil, pore water, and surface‐water carbon fluxes in an Australian estuarine tidal creek to assess whether (1) advective pore water exchange releases some of the soil carbon, (2) outwelling (lateral exports) represents a major carbon sequestration mechanism, and (3) methane emissions offset soil carbon sequestration. A radon (222Rn) mass balance implied tidally driven pore‐water exchange rates ranging from 5.5 ± 3.6 to 15.6 ± 8.1 cm d−1. Pore water exchange explained most of the dissolved organic carbon (DOC) and methane surface‐water fluxes but not dissolved inorganic carbon (DIC) and alkalinity. Organic carbon burial in soils derived from 239 + 240Pu dating was 11–63 g C m−2 yr−1. Methane and carbon dioxide emissions at the water–air interface were 0.27 ± 0.03 and 63 ± 166 mmol m−2 d−1, respectively. When calculated as CO2‐equivalents, aquatic CH4 emissions converted to 19–94 g C‐CO2 m−2 yr−1. Upscaling methane and soil carbon fluxes to representative areas revealed that CH4 emissions could offset < 5% of soil carbon burial. DIC outwelling (12 ± 6 mmol m−2 catchment d−1) was less than five‐fold greater than DOC and particulate organic carbon (POC) outwelling and four‐fold greater than catchment‐wide carbon burial. Because much of this DIC remains in the ocean after air–water equilibration, lateral DIC exports may represent an important long‐term carbon sink. Recent research has focused on quantifying carbon burial rates in blue carbon habitats such as saltmarshes and mangroves. We suggest that DIC outwelling and methane outgassing should also be considered when assessing the carbon sequestration capacity of these coastal vegetated habitats. [ABSTRACT FROM AUTHOR]

Rivers are a major source of nutrients, carbon and alkalinity for the global ocean, where the delivered compounds strongly impact biogeochemical processes. In this study, we firstly estimate pre-industrial riverine fluxes of nutrients, carbon and alkalinity based on a hierarchy of weathering and land-ocean export models, while identifying regional hotspots of the land-ocean exports. Secondly, we implement the riverine loads into a global biogeochemical ocean model and describe their implications for oceanic nutrient concentrations, the net primary production (NPP) and CO2 fluxes globally, as well as in a regional shelf analysis. Thirdly, we quantify the terrestrial origins and the long-term oceanic fate of riverine carbon in the framework, while assessing the potential implementation of riverine carbon fluxes in a fully coupled land-atmosphere-ocean model. Our approach leads to annual pre-industrial riverine exports of 3.7Tg P, 27Tg N, 158Tg Si and 603Tg C, which were derived from weathering and non-weathering sources and were fractionated into organic and inorganic compounds. We thereby identify the tropical Atlantic catchments (20% of global C), Arctic rivers (9% of total C) and Southeast Asian rivers (15% of total C) as dominant providers of carbon to the ocean. The riverine exports lead to a global oceanic source of CO2 to the atmosphere (231Tg Cyr-1), which is largely a result of a source from inorganic riverine carbon loads (183Tg Cyr-1), and from organic riverine carbon inputs (128Tg C yr-1). Additionally, a sink of 80Tg C yr-1 is caused by the enhancement of the biological carbon uptake by dissolved inorganic nutrient inputs, resulting alkalinity production and a slight model drift. While large outgassing fluxes are mostly found in proximity to major river mouths, substantial outgassing fluxes can also be observed further offshore, most prominently in the tropical Atlantic. Furthermore, we find evidence for the interhemispheric transfer of carbon in the model; we detect a stronger relative outgassing flux (49% of global river induced outgassing) in the southern hemisphere in comparison to the hemisphere's relative riverine inputs (33% of global river inputs), as well as an outgassing flux of 17Tg Cyr-1 in the Southern Ocean. Riverine exports lead to a strong increase in NPP in the tropical West Atlantic, Bay of Bengal and the East China Sea (166%, 377% and 71% respectively). While the NPP is not strongly sensitive to riverine loads on the light limited Arctic shelves, the CO2 flux is strongly altered due to substantial dissolved carbon supplies to the region. While our study confirms that the ocean circulation is the main driver for open ocean biogeochemical distributions, it reveals the necessity to consider riverine exports for the representation of heterogeneous features of the coastal ocean, to represent riverine-induced carbon outgassing, as well as to consider the long-term volcanic CO2 flux to close the atmospheric carbon budget in a coupled land-ocean-atmosphere setting. [ABSTRACT FROM AUTHOR]

In this study we discuss the occurrence of mantle‐derived heat and volatiles (i.e., helium and CO2) feeding hydrothermal systems in a seismically active margin between two convergent plates (African and European) without any signals of volcanism. The helium (He) isotopes clearly indicate a mantle‐derived component in the outgassing volatiles. The estimated mantle‐derived He fluxes are up to two to three orders of magnitude greater than those in a stable continental area. Such high He fluxes cannot be provided by a long‐lasting diffusion, thereby implying a more efficient transport (i.e., advective transport through faults). He data coupled to heat‐He relationship suggest the occurrence of active degassing of magmatic intrusions in this area of continental collisional. Geophysical data indicate the presence of a hot mantle wedge below the outgassing of mantle volatiles and a system of faults cutting the continental crust down to the hot mantle wedge. Here we discuss the hot mantle wedge and possible associated magmatic intrusions as the source of the mantle‐derived volatiles outgassing in the region. We also assessed the output of mantle‐derived CO2 from the investigated hydrothermal basins. The possible occurrence of magma at depth as well as the geometry of the thick‐skinned deformed wedge unambiguously indicates delamination processes that are related to continental subduction. Hence, we show that delamination processes can really produce magma at depth without evidences of volcanism at the surface. Finally, we have also provided the fault systems that work as a network of pathways and actively sustain the advective transfer of the mantle fluids toward the surface. Plain Language Summary: Volatiles from the Earth's mantle escape into the atmosphere mainly in volcanic districts and in submarine regions where new magma reaches the oceanic bottom. A lesser extent occurs in continental regions undergoing active tectonics. How mantle volatiles degas in continental regions and where evidences of volcanic activity are lacking remain a key challenge, given that in absence of magma the mantle would not lose its volatiles. Here we use the He‐heat systematics and recognize the presence of mantle volatiles in a continental region where there is no evidence of volcanism on the surface. This is a rare case of active outgassing of fluids coming from the mantle in a region that is characterized by continental collision. These geochemical evidences support the occurrence of magmatic bodies at depth and an advective flow of volatiles and heat through the crust. Geophysical data corroborate the geochemical evidences demonstrating the occurrence of a portion of hot mantle in between two crustal layers in correspondence of the mantle volatiles at the surface. Geology coupled to geophysics shows the presence of tectonic discontinuities cutting the crust down to the mantle working as a network of pathways through which mantle fluids move to the surface. Key Points: Mantle‐derived volatiles outgas in the continental convergent region without any evidences of volcanism at the surfaceHeat‐helium relationship highlights the occurrence of magmatic intrusion at depth in convergent regionDelamination processes in continental convergent margin can produce magmatism at depth [ABSTRACT FROM AUTHOR]

This paper describes a miniature, silicon-glass, electron-impact ion source, in which a field emission carbon nanotube cathode is separated from the external atmosphere by a semitransparent Si3N4 membrane. High vacuum necessary for the proper operation of the ion source is generated on a chip by an integrated micropump. The experiment revealed that it is possible to obtain and maintain high vacuum inside the structure; however, some problems associated with outgassing occurred during field emission measurements. Despite this fact, both the transmission of electrons through the thin membrane and the possibility of gas ionization have been confirmed. [ABSTRACT FROM AUTHOR]

Oxygen-free palladium/titanium (Pd/Ti) is a new nonevaporable getter material with an activation temperature as low as 133 °C. Because pumping speeds of oxygen-free Pd/Ti for H2 and CO have been reported to be improved by baking under an O2 atmosphere, the authors investigated oxygen-free Pd/Ti samples heated in an ultrahigh vacuum (UHV) or under an O2 pressure of 1.3 × 10−4 Pa by x-ray photoelectron spectroscopy. The authors found that carbon contamination decreased to an extent on heating in UHV, but decreased considerably on heating in O2. Pressure-curve measurements in an oxygen-free Pd/Ti-coated chamber show that pumping speeds for H2 and CO were considerably improved after baking the chamber under an O2 pressure of 1.3 × 10−4 Pa (O2 baking) in comparison with baking in UHV. Furthermore, partial-pressure measurements suggested that O2 baking removes adsorbed carbon and hydrogen, and consequently suppresses the formation of H2, CO, H2O, and CH4. Catalytic chemical reactions on the Pd surface appear to be responsible for the removal of adsorbed carbon and hydrogen. The pumping speeds of the oxygen-free Pd/Ti-coated chamber for H2 and CO were measured by using the orifice method and were found to be improved after O2 baking. O2 baking is therefore useful for improving pumping speeds for H2 and CO and for reducing the partial pressures of H2, CO, H2O, and CH4. [ABSTRACT FROM AUTHOR]

Different sources and processes contribute to pCO2 and CO2 exchange with the atmosphere in the rivers and floodplains of the Amazon basin. We measured or estimated pCO2, CO2 fluxes with the atmosphere, planktonic community respiration (PCR), and environmental and landscape variables along the Negro and Amazon-Solimões rivers during different periods of the fluvial hydrological cycle. Values of pCO2 ranged from 307 to 7527 μatm, while CO2 fluxes ranged from − 9.3 to 1128 mmol m−2 d−1 in the Amazon-Solimões basin. In the Negro basin, pCO2 values ranged from 648 to 6526 μatm, and CO2 fluxes from 35 to 1025 mmol m−2 d−1. In a general linear model including data from Negro and Amazon-Solimões basins, seasonal and spatial variation in flooded vegetated habitat area, dissolved oxygen, depth and water temperature explained 85% of surface pCO2 variation. Levels of pCO2 varied with inundation extent, with higher pCO2 values occurring in periods with greater water depth and inundation area, and lower dissolved oxygen concentrations and water temperatures. In a separate analysis for the Amazon-Solimões river and floodplains, ecosystem type (lotic or lentic), hydrological period, water temperature, dissolved oxygen, depth and dissolved phosphorus explained 83% of pCO2 variation. Our results demonstrate the influence of alluvial floodplains and seasonal variations in their limnological characteristics on the pCO2 levels in river channels of the lowland Amazon. [ABSTRACT FROM AUTHOR]

Only a small fraction (approx. 1–20%) of magmas generated in the mantle erupt at the surface. While volcanic eruptions are typically considered as the main exhaust pipes for volatile elements to escape into the atmosphere, the contribution of magma reservoirs crystallizing in the crust is likely to dominate the volatile transfer from depth to the surface. Here, we use multiscale physical modelling to identify and quantify the main mechanisms of gas escape from crystallizing magma bodies. We show that most of the outgassing occurs at intermediate to high crystal fraction, when the system has reached a mature mush state. It is particularly true for shallow volatilerich systems that tend to exsolve volatiles through second boiling, leading to efficient construction of gas channels as soon as the crystallinity reaches approximately 40–50 vol.%. We, therefore, argue that estimates of volatile budgets based on volcanic activity may be misleading because they tend to significantly underestimate the magmatic volatile flux and can provide biased volatile compositions. Recognition of the compositional signature and volumetric dominance of intrusive outgassing is, therefore, necessary to build robust models of volatile recycling between the mantle and the surface. [ABSTRACT FROM AUTHOR]

Eddy covariance measurements show gas transfer velocity suppression at medium to high wind speed. A wind–wave interaction described by the transformed Reynolds number is used to characterize environmental conditions favoring this suppression. We take the transformed Reynolds number parameterization to review the two most cited wind speed gas transfer velocity parameterizations: and. We propose an algorithm to adjust k values for the effect of gas transfer suppression and validate it with two directly measured dimethyl sulfide (DMS) gas transfer velocity data sets that experienced gas transfer suppression. We also show that the data set used in the Nightingale 2000 parameterization experienced gas transfer suppression. A compensation of the suppression effect leads to an average increase of 22 % in the k vs. u relationship. Performing the same correction for Wanninkhof 2014 leads to an increase of 9.85 %. Additionally, we applied our gas transfer suppression algorithm to global air–sea flux climatologies of CO2 and DMS. The global application of gas transfer suppression leads to a decrease of 11 % in DMS outgassing. We expect the magnitude of Reynolds suppression on any global air–sea gas exchange to be about 10 %. [ABSTRACT FROM AUTHOR]

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Biogeochemical Argo floats, profiling to 2,000‐m depth, are being deployed throughout the Southern Ocean by the Southern Ocean Carbon and Climate Observations and Modeling program (SOCCOM). The goal is 200 floats by 2020, to provide the first full set of annual cycles of carbon, oxygen, nitrate, and optical properties across multiple oceanographic regimes. Building from no prior coverage to a sparse array, deployments are based on prior knowledge of water mass properties, mean frontal locations, mean circulation and eddy variability, winds, air‐sea heat/freshwater/carbon exchange, prior Argo trajectories, and float simulations in the Southern Ocean State Estimate and Hybrid Coordinate Ocean Model (HYCOM). Twelve floats deployed from the 2014–2015 Polarstern cruise from South Africa to Antarctica are used as a test case to evaluate the deployment strategy adopted for SOCCOM's 20 deployment cruises and 126 floats to date. After several years, these floats continue to represent the deployment zones targeted in advance: (1) Weddell Gyre sea ice zone, observing the Antarctic Slope Front, and a decadally‐rare polynya over Maud Rise; (2) Antarctic Circumpolar Current (ACC) including the topographically steered Southern Zone chimney where upwelling carbon/nutrient‐rich deep waters produce surprisingly large carbon dioxide outgassing; (3) Subantarctic and Subtropical zones between the ACC and Africa; and (4) Cape Basin. Argo floats and eddy‐resolving HYCOM simulations were the best predictors of individual SOCCOM float pathways, with uncertainty after 2 years of order 1,000 km in the sea ice zone and more than double that in and north of the ACC. Plain Language Summary: The Southern Ocean, which surrounds Antarctica, is a huge, very sparsely observed region. But we know from the decades of observations and from computer models that the Southern Ocean is a major player in the Earth's climate, taking up a significant fraction of the excess carbon dioxide from the atmosphere and absorbing a large fraction of the extra heat that results from that extra carbon dioxide. The extra carbon dioxide is also acidifying the Southern Ocean waters. To observe these, we are expanding one of the major ocean‐observing systems: Argo profiling floats that measure temperature and salinity to 2,000‐m depth every 10 days. SOCCOM has (1) added extra sensors that measure the ocean's pH, oxygen, nitrate, chlorophyll, and particles; (2) developed algorithms to derive the rest of the carbon budget terms, and (3) vigorously expanded Argo into the enormous seasonal ice zone. We are deploying about 30 floats per year all around Antarctica. We describe our strategy for float deployments in 2014 in the large region between Africa and Antarctica, describing the circulation, water properties, and forcing of this region. We evaluate how well we met our goal of sampling each of the distinct oceanographic regimes. Key Points: SOCCOM float deployment strategy is based on prior water mass, frontal zone, forcing, and circulation information from data and modelsThese floats were deployed in the sea ice zone, Weddell and Ross Seas, Antarctic Circumpolar Current, and Subantarctic and Subtropical ZonesFloats have already provided information on carbon outgassing, mixing during Maud Rise polynya, oxygen utilization, and net community production [ABSTRACT FROM AUTHOR]

In a cometary coma, the ion-neutral decoupling distance, sometimes referred to as the ion exobase or collisionopause, can be defined as the cometocentric distance, r in, where ions, initially moving with the neutral outgassing speed, have a probability of 1/ e of not colliding with neutrals on their subsequent journey radially outwards. We present an analytical model for calculating this decoupling distance in the presence of a static radial electric field. We show that for a logarithmically decaying potential, the value of r incan even decrease to ∼15 per cent of its field-free case value. Moreover, already at this distance, the effective ion speed can be expected to markedly exceed the neutral expansion velocity. These analytical results are in line with previous numerical calculations, adapting similar but not identical field profiles. The presence of a non-negligible ambipolar electric field and limited importance of ion-neutral collisional coupling are further supported by observations in the diamagnetic cavity of comet 67P/Churyumov–Gerasimenko by plasma instruments onboard Rosetta that reveal ion speeds several times higher than the neutral expansion velocity. [ABSTRACT FROM AUTHOR]

The material’s plasma exposure experiment (MPEX) is a steady-state, linear plasma facility proposed to provide plasma conditions that simulate the first wall and divertor of the next-step fusion devices. MPEX will use an actively cooled, high-power helicon antenna as a plasma source. The antenna is located outside of the vacuum region, and during operation, a significant percentage of the antenna power is deposited on the plasma facing surface of the antenna window. The window thus must be actively cooled so that thermal stresses do not become excessive. The design presented includes two cylindrical windows with an annular water passage in-between in order to allow active cooling. A ceramic-to-metal seal is proposed in order to produce a water-to-vacuum seal that will not outgas and produce impurities. Experimental results from an uncooled window on a short-pulse prototype experiment are modeled using finite-element (FE) results in order to correlate with the heat flux profile. The design of the actively cooled window assembly is presented with computational fluid dynamics and FE analyses to confirm that the hardware can function with a 200-kW antenna within performance limits. [ABSTRACT FROM AUTHOR]

Recent improvements in additive layer manufacturing (ALM) have provided new designs of geometrically complex structures with lighter materials and low processing costs. The use of additive manufacturing in spacecraft production is opening up many new possibilities in both design and fabrication, allowing for the reduction of the weight of the structure subsystems. In this aim, polymeric ALM structures can become a choice, in terms of lightweight and demisability, as far as good thermomechanical properties. Moreover, provided that fused-deposition modeling (FDM) is used, nanosats and other structures could be easily produced in space. However, the choice of the material is a crucial step of the process, as the final performance of the printed parts is strongly dependent on three pillars: design, material, and printing process. As a high-performance technopolymer, polyether ether ketone (PEEK) has been adopted to fabricate parts via ALM; however, the space compatibility of 3D-printed parts remains not demonstrated. This work aimed to realize a nanosat polymeric structure via FDM, including all the phases of the development process: thermomechanical design, raw material selection, printing process tuning, and manufacturing of a proof of concept of a technological model. The design phase includes the application of topology optimization to maximize mass saving and take full advantage of the ALM capability. 3D-printed parts were characterized via thermomechanical tests, outgassing tests of 3D-printed parts are reported confirming the outstanding performance of polyether ether ketone and its potential as a material for structural space application.