Science.gov

Sample records for active fluid venting

  1. Neotectonic activity at the Giant Gjallar Vent (Norwegian Sea) indicates a future phase of active fluid venting

    NASA Astrophysics Data System (ADS)

    Dumke, Ines; Berndt, Christian; Crutchley, Gareth; Couillard, Mélanie; Gay, Aurélien

    2013-04-01

    The Giant Gjallar Vent (GGV) is a hydrothermal vent complex that formed during the opening of the North Atlantic at about 55 Ma. Sill intrusions into Cretaceous organic-rich sediments led to the production and subsequent vigorous seafloor venting of methane. A later phase of fluid escape occurred in mid-Oligocene times. The GGV is characterised by two pipes of 440 m and 480 m in diameter that reach up to the Base Late Pliocene Unconformity (BLPU) between the Kai and Naust formations. The unconformity is strongly deformed over an area of c. 18,000 km² across the vent, with a positive relief of up to 38 m above the surrounding paleo-seafloor. The overlying sediments of the Naust Formation conformally drape this deformation, smoothing its relief to a maximum of 15 m at the modern seafloor. The sediment drape indicates present inactivity of the vent system, as does the absence of indicators of active fluid escape in the water column during RV METEOR cruise M87-2 in 2012. However, high-resolution 2D seismic and Parasound data from the same cruise, and exploration-type 3D seismic data acquired by Norsk Hydro, show several indications for recent to ongoing activity at the GGV. Beneath the BLPU, strong frequency attenuation and chaotic reflections indicate the presence of free gas. At the edges of the extent of chaotic reflections, subvertical faults cut the unconformity as well as horizons of the lower and middle Naust Formation, suggesting tectonic activity after deposition of these horizons. Neotectonic activity is further indicated by the extensive occurrence of shallow faults apparent in Parasound records in the immediate vicinity of the vent and up to 16 km away. Some of these faults reach the seafloor. The observed deformation and faults may be the result of fluids accumulating beneath the BLPU due to increased loading of the oozy Kai Formation by denser glacigenic Naust sediments. Because of the lower permeability of the Naust Formation, the unconformity acts as a

  2. Linking geology, fluid chemistry, and microbial activity of basalt- and ultramafic-hosted deep-sea hydrothermal vent environments.

    PubMed

    Perner, M; Hansen, M; Seifert, R; Strauss, H; Koschinsky, A; Petersen, S

    2013-07-01

    Hydrothermal fluids passing through basaltic rocks along mid-ocean ridges are known to be enriched in sulfide, while those circulating through ultramafic mantle rocks are typically elevated in hydrogen. Therefore, it has been estimated that the maximum energy in basalt-hosted systems is available through sulfide oxidation and in ultramafic-hosted systems through hydrogen oxidation. Furthermore, thermodynamic models suggest that the greatest biomass potential arises from sulfide oxidation in basalt-hosted and from hydrogen oxidation in ultramafic-hosted systems. We tested these predictions by measuring biological sulfide and hydrogen removal and subsequent autotrophic CO2 fixation in chemically distinct hydrothermal fluids from basalt-hosted and ultramafic-hosted vents. We found a large potential of microbial hydrogen oxidation in naturally hydrogen-rich (ultramafic-hosted) but also in naturally hydrogen-poor (basalt-hosted) hydrothermal fluids. Moreover, hydrogen oxidation-based primary production proved to be highly attractive under our incubation conditions regardless whether hydrothermal fluids from ultramafic-hosted or basalt-hosted sites were used. Site-specific hydrogen and sulfide availability alone did not appear to determine whether hydrogen or sulfide oxidation provides the energy for primary production by the free-living microbes in the tested hydrothermal fluids. This suggests that more complex features (e.g., a combination of oxygen, temperature, biological interactions) may play a role for determining which energy source is preferably used in chemically distinct hydrothermal vent biotopes. PMID:23647923

  3. Identification and activity of acetate-assimilating bacteria in diffuse fluids venting from two deep-sea hydrothermal systems.

    PubMed

    Winkel, Matthias; Pjevac, Petra; Kleiner, Manuel; Littmann, Sten; Meyerdierks, Anke; Amann, Rudolf; Mußmann, Marc

    2014-12-01

    Diffuse hydrothermal fluids often contain organic compounds such as hydrocarbons, lipids, and organic acids. Microorganisms consuming these compounds at hydrothermal sites are so far only known from cultivation-dependent studies. To identify potential heterotrophs without prior cultivation, we combined microbial community analysis with short-term incubations using (13)C-labeled acetate at two distinct hydrothermal systems. We followed cell growth and assimilation of (13)C into single cells by nanoSIMS combined with fluorescence in situ hybridization (FISH). In 55 °C-fluids from the Menez Gwen hydrothermal system/Mid-Atlantic Ridge, a novel epsilonproteobacterial group accounted for nearly all assimilation of acetate, representing the first aerobic acetate-consuming member of the Nautiliales. In contrast, Gammaproteobacteria dominated the (13) C-acetate assimilation in incubations of 37 °C-fluids from the back-arc hydrothermal system in the Manus Basin/Papua New Guinea. Here, 16S rRNA gene sequences were mostly related to mesophilic Marinobacter, reflecting the high content of seawater in these fluids. The rapid growth of microorganisms upon acetate addition suggests that acetate consumers in diffuse fluids are copiotrophic opportunists, which quickly exploit their energy sources, whenever available under the spatially and temporally highly fluctuating conditions. Our data provide first insights into the heterotrophic microbial community, catalyzing an under-investigated part of microbial carbon cycling at hydrothermal vents. PMID:25244359

  4. Device damps fluid pressure oscillations in vent valve

    NASA Technical Reports Server (NTRS)

    Nein, H. J.

    1968-01-01

    Device, containing a tuned series arrangement of two plenum chambers and two orifices, damps high pressure fluid oscillations in a vent valve. Used in conjunction with vent valves, it relieves gas pressure that develops in liquid hydrogen and liquid oxygen tanks used on a space vehicle.

  5. Fluid venting in the eastern Aleutian Subduction Zone

    NASA Astrophysics Data System (ADS)

    Suess, Erwin; Bohrmann, Gerhard; von Huene, Roland; Linke, Peter; Wallmann, Klaus; Lammers, Stephan; Sahling, Heiko; Winckler, Gisela; Lutz, Richard A.; Orange, Daniel

    1998-02-01

    Fluid venting has been observed along 800 km of the Alaska convergent margin. The fluid venting sites are located near the deformation front, are controlled by subsurface structures, and exhibit the characteristics of cold seeps seen in other convergent margins. The more important characteristics include (1) methane plumes in the lower water column with maxima above the seafloor which are traceable to the initial deformation ridges; (2) prolific colonies of vent biota aligned and distributed in patches controlled by fault scarps, over-steepened folds or outcrops of bedding planes; (3) calcium carbonate and barite precipitates at the surface and subsurface of vents; and (4) carbon isotope evidence from tissue and skeletal hard parts of biota, as well as from carbonate precipitates, that vents expel either methane- or sulfide-dominated fluids. A biogeochemical approach toward estimating fluid flow rates from individual vents based on oxygen flux measurements and vent fluid analysis indicates a mean value of 5.5±0.7 L m-2 d-1 for tectonics-induced water flow [Wallmann et al., 1997b]. A geophysical estimate of dewatering from the same area [von Huene et al., 1997] based on sediment porosity reduction shows a fluid loss of 0.02 L m-2 d-1 for a 5.5 km wide converged segment near the deformation front. Our video-guided surveys have documented vent biota across a minimum of 0.1% of the area of the convergent segment off Kodiak Island; hence an average rate of 0.006 L m-2 d-1 is estimated from the biogeochemical approach. The two estimates for tectonics-induced water flow from the accretionary prism are in surprisingly good agreement.

  6. Isolated communities of Epsilonproteobacteria in hydrothermal vent fluids of the Mariana Arc seamounts.

    PubMed

    Huber, Julie A; Cantin, Holly V; Huse, Susan M; Welch, David B Mark; Sogin, Mitchell L; Butterfield, David A

    2010-09-01

    Low-temperature hydrothermal vent fluids represent access points to diverse microbial communities living in oceanic crust. This study examined the distribution, relative abundance, and diversity of Epsilonproteobacteria in 14 low-temperature vent fluids from five volcanically active seamounts of the Mariana Arc using a 454 tag sequencing approach. Most vent fluids were enriched in cell concentrations compared with background seawater, and quantitative PCR results indicated that all fluids were dominated by bacteria. Operational taxonomic unit-based statistical tools applied to 454 data show that all vents from the northern end of the Mariana Arc grouped together, to the exclusion of southern arc seamounts, which were as distinct from one another as they were from northern seamounts. Statistical analysis also showed a significant relationship between seamount and individual vent groupings, suggesting that community membership may be linked to geographical isolation and not geochemical parameters. However, while there may be large-scale geographic differences, distance is not the distinguishing factor in the microbial community composition. At the local scale, most vents host a distinct population of Epsilonproteobacteria, regardless of seamount location. This suggests that there may be barriers to exchange and dispersal for these vent endemic microorganisms at hydrothermal seamounts of the Mariana Arc. PMID:20533947

  7. The influence of vent fluid chemistry on trophic structure at two deep-sea hydrothermal vent fields on the Mid-Cayman Rise

    NASA Astrophysics Data System (ADS)

    Bennett, Sarah; Van Dover, Cindy; Coleman, Max

    2014-05-01

    The two known deep-sea hydrothermal vent fields along the Mid-Cayman Rise are separated by a distance of only 21 km, yet their chemistry and faunal diversity are distinct. The deeper of the two vent fields, Piccard (with active venting from Beebe Vents, Beebe Woods and Beebe Sea), at 4980 m is basalt hosted. The shallower vent field, Von Damm, at 2300 m appears to have an ultramafic influence. The Von Damm vent field can be separated into two sites: The Spire and The Tubeworm Field. The dominant vent fluids at the Tubeworm Field are distinct from those at the Spire, as a result of fluid modification in the sub-surface. Von Damm and Piccard vent fields support abundant invertebrates, sharing the same biomass-dominant shrimp species, Rimicaris hybisae. Although there are some other shared species (squat lobsters (Munidopsis sp.) and gastropods (Provanna sp. and Iheyaspira sp.)) between the vent fields, they are much more abundant at one site than the other. In this study we have examined the bulk carbon, nitrogen and sulfur isotope composition of microbes and fauna at each vent field. With these data we have deduced the trophic structure of the communities and the influence of vent fluid chemistry. From stable isotope data and end-member vent fluid chemistry, we infer that the basis of the trophic structure at Piccard is dominated by sulfur, iron, and hydrogen-oxidizing microbial communities. In comparison, the basis of the Von Damm trophic structure is dominated by microbial communities of sulfur and hydrogen oxidizers, sulfate reducers and methanotrophs. This microbial diversity at the base of the trophic structure is a result of chemical variations in vent fluids and processes in the sub-surface that alter the vent fluid chemistry. These differences influence higher trophic levels and can be used to explain some of the variability as well as similarity in fauna at the vent sites. Part of this work was performed at the Jet Propulsion Laboratory, California

  8. Post-drilling hydrothermal vent and associated biological activities seen through artificial hydrothermal vents in the Iheya North field, Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Takai, K.; Kawagucci, S.; Miyazaki, J.; Watsuji, T.; Ishibashi, J.; Yamamoto, H.; Nozaki, T.; Kashiwabara, T.; Shibuya, T.

    2012-12-01

    In 2010, IODP Expedition 331 was conducted in the Iheya North Field, the Okinawa Trough and drilled several sites in hydrothermally active subseafloor. In addition, during the IODP Expedition 331, four new hydrothermal vents were created. These post-drilling artificial hydrothermal vents provide excellent opportunities to investigate the physical, chemical and microbiological characteristics of the previously unexplored subseafloor hydrothermal fluid reservoirs, and to monitor and estimate how the anthropogenic drilling behaviors affect the deep-sea hydrothermal vent ecosystem. We were very much interested in the difference of hydrothermal fluid chemistry between the natural hydrothermal vents and the artificial hydrothermal vents. The IODP porewater chemistry of the cores pointed to the density-driven stratification of the phase-separated hydrothermal fluids and the natural vent fluids were likely derived only from the shallower vapor-enriched phases. However, the artificial hydrothermal vents had deeper fluid sources in the subseafloor hydrothermal fluid reservoirs composed of vapor-lost (Cl-enriched) phases. The fluids from the artificial hydrothermal vents were sampled by ROV at 5, 12 and 18 months after the IODP expedition. The artificial hydrothermal vent fluids were slightly enriched with Cl as compared to the natural hydrothermal vent fluids. Thus, the artificial hydrothermal vents successfully entrained the previously unexplored subseafloor hydrothermal fluids. The newly created hydrothermal vents also hosted the very quickly grown, enormous chimney structures, of which mineral compositions were highly variable among the vents. However, the quickly grown C0016B and C0016D vent chimneys were found to be typical Kuroko ore even though the chimney growth rates in the artificial vents were extremely faster than those in the natural vents. In addition, the IODP drilling operation not only created new hydrothermal vents by deep drilling but also induced the

  9. Fluid flow and mass flux determinations at vent sites on the Cascadia margin accretionary prism

    SciTech Connect

    Carson, B.; Strasser, J.C. ); Suess, E. )

    1990-06-10

    Fluid venting from the toe of the accretionary prism off Oregon was measured in situ during a series of dives with DSRV Alvin in 1987 and 1988. A benthic chamber was place over active vent sites to sequentially collect samples of venting fluids and to make direct measurements of discharge rates. Calibrated flow meter measurements and flow rates determined from dissolved methane transfer indicate that discharge from two vent sites, Alvin 1428 and Alvin 1900, ranges roughly between 100 and 500 l/m{sup 2}d with the most reliable estimates falling in the range of 125-150 l/m{sup 2}d. These rates imply subsurface advective flow on the order of 100 m/yr. Comparison of observed discharge rates with rates calculated for steady state expulsion supported by accretion-related compaction indicates that the observed flow is greater than predicted flow by several orders of magnitude. The disparity dictates that fluids are not derived locally, but are transported laterally within the prism, or that flow is not steady state and that individual vents are short-lived features in the ongoing accretion process.

  10. Phylogenetic diversity and functional gene patterns of sulfur-oxidizing subseafloor Epsilonproteobacteria in diffuse hydrothermal vent fluids.

    PubMed

    Akerman, Nancy H; Butterfield, David A; Huber, Julie A

    2013-01-01

    Microorganisms throughout the dark ocean use reduced sulfur compounds for chemolithoautotrophy. In many deep-sea hydrothermal vents, sulfide oxidation is quantitatively the most important chemical energy source for microbial metabolism both at and beneath the seafloor. In this study, the presence and activity of vent endemic Epsilonproteobacteria was examined in six low-temperature diffuse vents over a range of geochemical gradients from Axial Seamount, a deep-sea volcano in the Northeast Pacific. PCR primers were developed and applied to target the sulfur oxidation soxB gene of Epsilonproteobacteria. soxB genes belonging to the genera Sulfurimonas and Sulfurovum are both present and expressed at most diffuse vent sites, but not in background seawater. Although Sulfurovum-like soxB genes were detected in all fluid samples, the RNA profiles were nearly identical among the vents and suggest that Sulfurimonas-like species are the primary Epsilonproteobacteria responsible for actively oxidizing sulfur via the Sox pathway at each vent. Community patterns of subseafloor Epsilonproteobacteria 16S rRNA genes were best matched to methane concentrations in vent fluids, as well as individual vent locations, indicating that both geochemistry and geographical isolation play a role in structuring subseafloor microbial populations. The data show that in the subseafloor at Axial Seamount, Epsilonproteobacteria are expressing the soxB gene and that microbial patterns in community distribution are linked to both vent location and chemistry. PMID:23847608

  11. Phylogenetic diversity and functional gene patterns of sulfur-oxidizing subseafloor Epsilonproteobacteria in diffuse hydrothermal vent fluids

    PubMed Central

    Akerman, Nancy H.; Butterfield, David A.; Huber, Julie A.

    2013-01-01

    Microorganisms throughout the dark ocean use reduced sulfur compounds for chemolithoautotrophy. In many deep-sea hydrothermal vents, sulfide oxidation is quantitatively the most important chemical energy source for microbial metabolism both at and beneath the seafloor. In this study, the presence and activity of vent endemic Epsilonproteobacteria was examined in six low-temperature diffuse vents over a range of geochemical gradients from Axial Seamount, a deep-sea volcano in the Northeast Pacific. PCR primers were developed and applied to target the sulfur oxidation soxB gene of Epsilonproteobacteria. soxB genes belonging to the genera Sulfurimonas and Sulfurovum are both present and expressed at most diffuse vent sites, but not in background seawater. Although Sulfurovum-like soxB genes were detected in all fluid samples, the RNA profiles were nearly identical among the vents and suggest that Sulfurimonas-like species are the primary Epsilonproteobacteria responsible for actively oxidizing sulfur via the Sox pathway at each vent. Community patterns of subseafloor Epsilonproteobacteria 16S rRNA genes were best matched to methane concentrations in vent fluids, as well as individual vent locations, indicating that both geochemistry and geographical isolation play a role in structuring subseafloor microbial populations. The data show that in the subseafloor at Axial Seamount, Epsilonproteobacteria are expressing the soxB gene and that microbial patterns in community distribution are linked to both vent location and chemistry. PMID:23847608

  12. Naked in toxic fluids: A nudibranch mollusc from hydrothermal vents

    NASA Astrophysics Data System (ADS)

    Valdés, Ángel; Bouchet, Philippe

    1998-01-01

    A new species of the nudibranch genus Dendronotus (Mollusca, Opisthobranchia) is reported from a hydrothermal vent at the Lucky Strike area, on the Mid-Atlantic Ridge. This is the first species of nudibranch recorded with certainty from a vent site. Other species of Dendronotus are distributed in temperate waters on the continental shelf of the northern hemisphere. Two factors that probably account for the occurrence of a nudibranch in this hydrothermal field are that the Lucky Strike area presents potential hydroid prey, and that nudibranchs apparently inhabit a lower activity area. It is hypothesized that the new species, which lacks eyes, is a permanent resident of vent fields on the Mid-Atlantic Ridge, but is probably not restricted to that environment.

  13. Quantifying fluid flow, solute mixing, and biogeochemical turnover at cold vents of the eastern Aleutian subduction zone

    NASA Astrophysics Data System (ADS)

    Wallmann, Klaus; Linke, Peter; Suess, Erwin; Bohrmann, Gerhard; Sahling, Heiko; Schlüter, Michael; Dählmann, Anke; Lammers, Stephan; Greinert, Jens; von Mirbach, Nikolaus

    1997-12-01

    In situ oxygen fluxes were measured at vent sites in the Aleutian trench at a water depth of almost 5000 m using a TV-guided benthic flux chamber. The flux was 2 orders of magnitude greater than benthic oxygen fluxes in areas unaffected by venting on the continental margin off Alaska. Porewater profiles taken from the surface sediment below a vent site showed high concentrations of sulfide, methane, and ammonia. The reduced carbon and nitrogen compounds are transported to the vent site by fluids expelled from deeper anoxic sediment layers by the forces of plate convergence. The tectonically driven fluid flow was determined from the biochemical turnover in vent communities and was found to be 3.4 ± 0.5 m yr -1. A model was used to quantify the transport of silica, Ca 2+, and sulfate via diffusion, advection, and bioirrigation through the surface sediments of a vent site. A nonlocal mixing coefficient of 20-30 yr -1 was determined by fitting the model curves to the measured porewater profiles showing that the transport of solutes within the near-surface sediments and across the sediment-water interface is dominated by the activity of the vent fauna. Sulfate-containing oceanic bottom water and methane-rich vent fluids were mixed below the clam colony to produce sulfide and a CaCO 3 precipitate. The vent biota shape their immediate environment and control the sediment-water exchange and the benthic fluxes at vent sites. The oxygen consumption at vent sites is a major sink for oxygen at the study area.

  14. Using the VentCam and Optical Plume Velocimetry to Measure High-Temperature Hydrothermal Fluid Flow Rates in the ASHES Vent Field on Axial Volcano

    NASA Astrophysics Data System (ADS)

    Crone, T. J.; Mittelstaedt, E. L.; Fornari, D. J.

    2014-12-01

    Fluid flow rates through high-temperature mid-ocean ridge hydrothermal vents are likely quite sensitive to poroelastic forcing mechanisms such as tidal loading and tectonic activity. Because poroelastic deformation and flow perturbations are estimated to extend to considerable depths within young oceanic crust, observations of flow rate changes at seafloor vents have the potential to provide constraints on the flow geometry and permeability structure of the underlying hydrothermal systems, as well as the quantities of heat and chemicals they exchange with overlying ocean, and the potential biological productivity of ecosystems they host. To help provide flow rate measurements in these challenging environments, we have developed two new optical flow oriented technologies. The first is a new form of Optical Plume Velocimetry (OPV) which relies on single-frame temporal cross-correlation to obtain time-averaged image velocity fields from short video sequences. The second is the VentCam, a deep sea camera system that can collect high-frame-rate video sequences at focused hydrothermal vents suitable for analysis with OPV. During the July 2014 R/V Atlantis/Alvin expedition to Axial Seamount, we deployed the VentCam at the ~300C Phoenix vent within the ASHES vent field and positioned it with DSRV Alvin. We collected 24 seconds of video at 50 frames per second every half-hour for approximately 10 days beginning July 22nd. We are currently applying single-frame lag OPV to these videos to estimate relative and absolute fluid flow rates through this vent. To explore the relationship between focused and diffuse venting, we deployed a second optical flow camera, the Diffuse Effluent Measurement System (DEMS), adjacent to this vent at a fracture within the lava carapace where low-T (~30C) fluids were exiting. This system collected video sequences and diffuse flow measurements at overlapping time intervals. Here we present the preliminary results of our work with VentCam and OPV

  15. Interrelationship of fluid venting and structural evolution: Alvin observations from the frontal accretionary prism, Oregon

    SciTech Connect

    Moore, J.C.; Orange, D. ); Kulm, L.D. )

    1990-06-10

    Seismic reflection and Sea Beam bathymetric data plus submarine geological measurements define a ramp anticline at the deformatoin front of the central Oregon subduction zone. At its northern termination the ramp anticline is deeply incised by a large 500-m-deep submarine canyon and cut by a probable backthrust. To the south along the strike of the fold, a smaller submarine canyon shallowly erodes the anticline, and backthrusting is not apparent in the submersible observations. Two Alvin dives along a transect through the southern canyon show active fluid vents demarked by biological communities at the frontal thrust and at the breached crest of the anticline. Along a northern transect, encompassing the large submarine canyon, 10 Alvin dives indicated no venting on the formal thrust, limited venting in the canyon, but numerous biological communities along a scarp interpreted as the surface trace of the backthrust. These observations suggest a scenario of vent and structural-geomorphic development consisting of (1) frontal thrust faulting and associated venting, facilitated by high fluid pressure; (2) erosion of the oversteepened seaward flank of the ramp anticline assisted by seepage forces and leading to fluid flow out of stratigraphically controlled conduits in the limbs of the overthrust deposits; (3) locking of the frontal thrust due to dewatering or a local decrease in wedge taper associated with development of the large canyon, leading to failure along the backthrust; and (4) redirection of fluid flow by the backthrust. Thus, within {le}0.3 m.y., deformation of the relatively permeable sediments of the Oregon margin results in stratigraphically controlled flow being partially captured by faults.

  16. Cryogenic fluid management technologies for space transportation. Zero G thermodynamic vent system

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Long term storage of subcritical cryogens in space must address the problem of thermal stratification in the storage tanks, liquid acquisition devices, and associated feed systems. Due to the absence of gravity induced body forces, thermal stratification in zero-g is more severe than commonly experienced in a one-g environment. If left uncontrolled, the thermal gradients result in excessive tank pressure rise and the formation of undesirable liquid/vapor mixtures within the liquid bulk, liquid acquisition system, and propellant transfer lines. Since external heat leakage cannot be eliminated, a means of minimizing the thermal stratification in the ullage gas, liquid, and feed system is required. A subsystem which minimizes the thermal stratification and rejects the environmental heat leakage in an efficient manner is therefore needed for zero-g subcritical cryogenic systems. In ground based storage systems the ullage gas location is always known (top of the tank) and therefore direct venting of gases as a means of heat rejection is easily accomplished. In contrast, because the ullage location in a zero-g environment is not easily predictable, heat rejection through direct gaseous venting is difficult in space (requires liquid settling, or surface tension devices). A means of indirect venting through the use of a thermodynamic vent system (TVS) is therefore required. A thermodynamic vent system allows indirect venting of vapor through heat exchange between the vented fluid and the stored fluid. The objective is to ensure that only gas and not liquid is vented, in order to minimize the propellant losses. Consequently, the design of a TVS is a critical enabling technology for future applications such as solar thermal and electric propulsion, single-stage-to-orbit vertical landers and upper stages, and any space based operations involving subcritical cryogenics. To bridge this technology gap NASA MSFC initiated an effort to build and verify through ground tests a zero

  17. An authoritative global database for active submarine hydrothermal vent fields

    NASA Astrophysics Data System (ADS)

    Beaulieu, Stace E.; Baker, Edward T.; German, Christopher R.; Maffei, Andrew

    2013-11-01

    The InterRidge Vents Database is available online as the authoritative reference for locations of active submarine hydrothermal vent fields. Here we describe the revision of the database to an open source content management system and conduct a meta-analysis of the global distribution of known active vent fields. The number of known active vent fields has almost doubled in the past decade (521 as of year 2009), with about half visually confirmed and others inferred active from physical and chemical clues. Although previously known mainly from mid-ocean ridges (MORs), active vent fields at MORs now comprise only half of the total known, with about a quarter each now known at volcanic arcs and back-arc spreading centers. Discoveries in arc and back-arc settings resulted in an increase in known vent fields within exclusive economic zones, consequently reducing the proportion known in high seas to one third. The increase in known vent fields reflects a number of factors, including increased national and commercial interests in seafloor hydrothermal deposits as mineral resources. The purpose of the database now extends beyond academic research and education and into marine policy and management, with at least 18% of known vent fields in areas granted or pending applications for mineral prospecting and 8% in marine protected areas.

  18. Characterizing Microbial Community and Geochemical Dynamics at Hydrothermal Vents Using Osmotically Driven Continuous Fluid Samplers

    SciTech Connect

    Robidart, Julie C.; Callister, Stephen J.; Song, Peng F.; Nicora, Carrie D.; Wheat, Charles G.; Girguis, Peter R.

    2013-05-07

    Microbes play a key role in mediating all aquatic biogeochemical cycles, and ongoing efforts are aimed at better understanding the relationships between microbial phylogenetic and physiological diversity, and habitat physical and chemical characteristics. Establishing such relationships is facilitated by sampling and studying microbiology and geochemistry at the appropriate spatial and temporal scales, to access information on the past and current environmental state that contributes to observed microbial abundances and activities. A modest number of sampling systems exist to date, few of which can be used in remote, harsh environments such as hydrothermal vents, where the ephemeral nature of venting underscores the necessity for higher resolution sampling. We have developed a robust, continuous fluid sampling system for co-registered microbial and biogeochemical analyses. The osmosis-powered bio-osmosampling system (BOSS) use no electricity, collects fluids with daily resolution or better, can be deployed in harsh, inaccessible environments and can sample fluids continuously for up to five years. Here we present a series of tests to examine DNA, RNA and protein stability over time, as well as material compatability, via lab experiments. We also conducted two field deployments at deep-sea hydrothermal vents to assess changes in microbial diversity and protein expression as a function of the physico-chemical environment. Our data reveal significant changes in microbial community composition co-occurring with relatively modest changes in the geochemistry. These data additionally provide new insights into the distribution of an enigmatic sulfur oxidizing symbiont in its free-living state. Data from the second deployment reveal differences in the representation of peptides over time, underscoring the utility of the BOSS in meta-proteomic studies. In concert, these data demonstrate the efficacy of this approach, and illustrate the value of using this method to study

  19. Extraordinary phase separation and segregation in vent fluids from the southern East Pacific Rise

    USGS Publications Warehouse

    Von Damm, K. L.; Lilley, M.D.; Shanks, Wayne C.; Brockington, M.; Bray, A.M.; O'Grady, K. M.; Olson, E.; Graham, A.; Proskurowski, G.

    2003-01-01

    The discovery of Brandon vent on the southern East Pacific Rise is providing new insights into the controls on midocean ridge hydrothermal vent fluid chemistry. The physical conditions at the time ofsampling (287 bar and 405??C) place the Brandon fluids very close to the critical point of seawater (298 bar and 407??C). This permits in situ study of the effects of near criticalphenomena, which are interpreted to be the primary cause of enhanced transition metal transport in these fluids. Of the five orifices on Brandon sampled, three were venting fluids with less than seawater chlorinity, and two were venting fluids with greater than seawater chlorinity. The liquid phase orifices contain 1.6-1.9 times the chloride content of the vapors. Most other elements, excluding the gases, have this same ratio demonstrating the conservative nature of phase separation and the lack of subsequent water-rock interaction. The vapor and liquid phases vent at the same time from orifices within meters of each other on the Brandon structure. Variations in fluid compositions occur on a time scale of minutes. Our interpretation is that phase separation and segregation must be occurring 'real time' within the sulfide structure itself. Fluids from Brandon therefore provide an unique opportunity to understand in situ phase separation without the overprinting of continued water-rock interaction with the oceanic crust, as well as critical phenomena. ?? 2002 Elsevier Science B.V. All rights reserved.

  20. Mineralogical and Fluid Inclusion Studies on Seafloor Hydrothermal Vents at TA25 Caldera, Tonga Arc

    NASA Astrophysics Data System (ADS)

    Choi, S. K.; Pak, S. J.; Choi, S. H.; Lee, K. Y.; Kim, H. S.; Lee, I. K.

    2015-12-01

    The extensive hydrothermal vent field was discovered at TA25("V18s-HR" in the SO-167 cruise) caldera in the Tonga arc, southwest Pacific. The TA25 caldera is a submarine volcano of dacitic composition and hosts the NE- and NW-trending hydrothermal vent on the western caldera wall. These active hydrothermal crusters are mostly small (chimney: <0.5m in tall; sulfide mound: <3m in diameter) and immature, and emit the transparent fluids of which temperature range from 150℃ to 242℃ (average = 203℃). The hydrothermal sulfide ores, recovered by ROV and/or TV-grab, are mainly composed of sphalerite, pyrite, marcasite, galena, chalcopyrite, covellite, tennantite, enargite and sulfates such as barite, gypsum/anhydrite. It is observed that three distinct mineralogical zonation from exterior to interior of the chimneys: (1) barite-gypsum/anhydrite-pyrite-sphalerite; (2) sphalerite-pyrite-galena±chalcopyrite; (3) sphaleirte-pyrite-chalcopyrite-enargite-tennantite±galena±covellite. FeS content in sphalerite increases from chimney exterior to interior. Chalcopyrite is more abundant in the mound than in the chimney, implying fluid temperatures in mound are greater than in the chimney. The enargite assemblage (pyrite-chalcopyrite-enargite-tennantite) is indicative of high-sulfidation epithermal deposits. Fluid inclusions on barite crystals from mound samples show mono-type inclusion (two-phase liquid-rich inclusions) which is less than 20㎛ in diameter. Homogenization temperatures and salinities from fluid inclusion study range from 148℃ to 341℃ (average = 213℃) and 0.4 to 3.6 equiv. wt.% NaCl, respectively. The main mineralization temperature in mound might be greater than 200℃ since barite on fluid inclusion is early stage mineral.

  1. Comparison of the Organic Composition of Vent Fluids from the Main Endeavour Field and Middle Valley

    NASA Astrophysics Data System (ADS)

    Cruse, A. M.; Seewald, J. S.

    2001-12-01

    Although the Main Endeavour Field is hosted in a sediment-free ridge-crest environment, previously measured high concentrations of NH4 and isotopically light CH4 relative to other bare-rock sites indicate that the chemical composition of these fluids is affected by sub-seafloor alteration of sedimentary material [1]. In contrast, at Middle Valley, located approximately 30 km north of Endeavour, vent fluids pass through up to 2 km of hemipelagic and turbiditic sediment prior to venting at the seafloor. By comparing the distribution and abundances of organic compounds in Endeavour fluids with those from Middle Valley, we can potentially constrain the relative importance of sediment alteration versus other processes (e.g., mantle degassing; abiotic synthesis) as sources for the organic species. Using a gas-tight sampler, vent fluids from Endeavour and ODP Mound and Dead Dog vent fields at Middle Valley were collected in July, 2000, and analyzed for the major inorganic ions and gases, as well as several classes of low-molecular weight organic compounds (C1-C6 alkanes and alkenes, aromatics, alcohols and phenols). We are also measuring the stable carbon isotopic composition of the C1-C6 alkanes, alkenes and aromatics. The concentrations of all organic compounds are greatest in fluids from the Dead Dog field, and vent fluids from the ODP Mound field are enriched in organic species relative to those from Endeavour. Concentrations of Br and NH4, inorganic species derived from sediment alteration, exhibit the same relative distributions among the vent fluids (i.e., concentrations are highest in Dead Dog fluids and lowest in Endeavour fluids). However, the relative abundances of organic compounds in individual vent fluids exhibit subtle differences. For example, while the abundances of the alkanes decrease with increasing chain length in all fluids, those from Endeavour are relatively more enriched in methane versus the C2-C6 alkanes than those from ODP Mound or Dead Dog

  2. Reconstructing the oxygen isotope composition of late Cambrian and Cretaceous hydrothermal vent fluid

    NASA Astrophysics Data System (ADS)

    Turchyn, Alexandra V.; Alt, Jeffrey C.; Brown, Shaun T.; DePaolo, Donald J.; Coggon, Rosalind M.; Chi, Guoxiang; Bédard, Jean H.; Skulski, Thomas

    2013-12-01

    Oxygen isotope analyses (δ18O) of 16 quartz-epidote pairs from late Cambrian (Betts Cove and Mings Bight, Newfoundland), Ordovician (Thetford Mines, Québec, Canada) and Cretaceous (Troodos, Cyprus) ophiolites are used to calculate the δ18O of the hydrothermal fluids from which they crystallized. We combine these with 3 quartz-fluid inclusion measurements and 3 quartz-magnetite measurements from the Cambrian ophiolites to explore how the range in the δ18O of submarine hydrothermal vent fluid has varied between the late Cambrian, Cretaceous and today. The range of calculated δ18O values of vent fluid (-4 to +7.4) is larger than that of modern seafloor hydrothermal vent fluid (0 to +4). We employ two numerical models to ascertain whether this range is most consistent with changes in paleo-seawater δ18O or with changes in the reactive flow path in ancient hydrothermal systems. A static calculation of the vent fluid oxygen isotope composition as a function of the water-rock ratio suggests that in an ocean with a lower δ18O than today, the range of vent fluid δ18O should be larger. Our data, however, show little evidence that the δ18O of the ocean was much lower than the global ice-free value of -1.2. A dual porosity model for reactive flow through fractured and porous media is used to model the relative evolution of the 87Sr/86Sr and δ18O of vent fluid in contact with rock. Our 87Sr/86Sr and δ18O for Cretaceous epidotes suggest the strontium concentration of the Cretaceous oceans may have been much higher than at present. The 87Sr/86Sr and δ18O data from Cambrian epidotes are strikingly different from the younger samples, and are difficult to model unless fluid-rock interaction in the Cambrian hydrothermal systems was substantially different. It is also possible that some of the quartz-epidote veins have been reset by obduction-related metamorphism. Our data suggest that the high calcium-to-sulfate ratio in early (and Cretaceous) seawater may have affected

  3. Mid-Ocean Ridge Hydrothermal Vent Fluid Chemistry at Ultrafast Spreading Rates: Control by Phase Separation and Water-Rock Equilibrium

    NASA Astrophysics Data System (ADS)

    O'Grady, K. M.; Von Damm, K. L.

    2001-12-01

    Phase separation, overprinted by water-rock equilibration are the major controls on the chemical composition of hydrothermal vent fluids sampled from two morphologically distinct areas (18\\deg 24-26'S and 21\\deg 24-27'S) along the ultrafast spreading ( ~15 cm/yr full rate) Southern East Pacific Rise (SEPR) during the 1998 SouEPR Cruise. This conclusion, along with the growing evidence that phase separation and water-rock equilibrium also control the composition of previously sampled hydrothermal vent fluids from slower-spreading ridges, indicates that to a first approximation neither spreading rate nor ridge morphology can be directly related to hydrothermal fluid compositions. Hydrothermal fluids from ultrafast spreading centers therefore do not form a unique subset in the global range of known chemical compositions. Previous geophysical surveys and submersible observations suggested that the hydrothermal system located at 21\\deg 24-27'S, the SouEPR Area, was dominated by tectonic activity (Renard et al., 1985; Tufar, 1995; Krasnov et al., 1997). Submersible observations and hydrothermal vent fluid chemistry indicated that the N. Hump Area, experienced volcanic activity shortly before the 1993 NADUR Cruise (Charlou et al., 1996). The N. Hump Area vent fluids sampled during the 1998 SouEPR Cruise displayed a relatively uniform chlorinity (616-670 mmol/kg Cl) that is greater than seawater. The Si and Cl data from the N. Hump Area vent fluids suggest reaction zone conditions up to ~360 bars (~1 km below the seafloor) and ~430\\deg C, indicating supercritical phase separation. The unusually large chlorinity variation (113-803 mmol/kg Cl) in the SouEPR Area hydrothermal vent fluids covers almost the entire range of sampled mid-ocean ridge (MOR) hydrothermal vent fluid chemistries worldwide (30.5-1245 mmol/kg Cl). The Si and Cl data from the SouEPR Area vent fluids suggest reaction zone conditions up to ~410 bars ( ~1.3 km below the seafloor) and ~450\\deg C. The

  4. Deep-sea hydrothermal vent animals seek cool fluids in a highly variable thermal environment.

    PubMed

    Bates, Amanda E; Lee, Raymond W; Tunnicliffe, Verena; Lamare, Miles D

    2010-01-01

    The thermal characteristics of an organism's environment affect a multitude of parameters, from biochemical to evolutionary processes. Hydrothermal vents on mid-ocean ridges are created when warm hydrothermal fluids are ejected from the seafloor and mixed with cold bottom seawater; many animals thrive along these steep temperature and chemical gradients. Two-dimensional temperature maps at vent sites have demonstrated order of magnitude thermal changes over centimetre distances and at time intervals from minutes to hours. To investigate whether animals adapt to this extreme level of environmental variability, we examined differences in the thermal behaviour of mobile invertebrates from aquatic habitats that vary in thermal regime. Vent animals were highly responsive to heat and preferred much cooler fluids than their upper thermal limits, whereas invertebrates from other aquatic environments risked exposure to warmer temperatures. Avoidance of temperatures well within their tolerated range may allow vent animals to maintain a safety margin against rapid temperature fluctuations and concomitant toxicity of hydrothermal fluids. PMID:20975681

  5. Fluid Geochemistry of the Capelinhos Vent Site. A Key to Understand the Lucky Strike Hydrothermal Vent Field (37°N, MAR).

    NASA Astrophysics Data System (ADS)

    Leleu, T.; Chavagnac, V.; Cannat, M.; Ceuleneer, G.; Castillo, A.; Menjot, L.

    2015-12-01

    The Lucky Strike hydrothermal field is situated at the mid-Atlantic ridge, south of the Azores, on top of a central volcano within the axial valley. The volcano is composed of a fossil lava lake surrounded by three volcanic cones. An Axial Magma Chamber (AMC) is reported 3.4km below the seafloor. The active venting sites are situated around the fossil lava lake and are directly linked to the heat supplied by the AMC. High temperature fluids from the Lucky Strike field were sampled in 2013, 2014 and 2015 in order to document the depth of the reaction zone, subsurface mixing, geographical control and magmatic degassing. A new active site named Capelinhos was discovered approximately 1.5km eastward from the lava lake, during exploration by ROV Victor6000 - MoMARsat cruise, 2013. It is composed of 10m-high chimneys discharging black smoker-type fluid. Fluid temperatures were 328°C in 2013 and decreased to 318°C in 2014 and 2015. Capelinhos fluids are Cl-depleted by 55% compared to seawater indicating phase separation at depth. In comparison, the other sites range from 6% enrichment (2608/Y3 site) to 22% depletion (Eiffel tower site). Si geothermobarometry of Y3 site estimates quartz equilibration at P=300 bars and T=360-380°C, coherent with Fe/Mn geothermometer (T=370±10°C). For Capelinhos, Fe/Mn suggests 398°C (±10°C) which is close to the critical point of seawater (P=300 bars and T=407°C). Other geothermobarometer uses Si/Cl vapor-like fluid to constrain depth of the top of reaction zone and predicts significant bias due to mixing along the up-flow zone. Application gives P=~370 bars, T=~435°C at Capelinhos and P=~390 bars, T=~440°C at Eiffel tower. This is further sustained by end-member 87Sr/86Sr=0.7038, which indicates little interaction of Capelinhos vent fluids with seawater-derived fluid, compared to other vapor-like sites with 87Sr/86Sr=0.7043. Because of its external location, Capelinhos site isn't influenced by the complex tectonic context of the

  6. A bestiary of ordinary vent activities at Stromboli (and what it tells us about vent conditions)

    NASA Astrophysics Data System (ADS)

    Gaudin, Damien; Taddeucci, Jacopo; Scarlato, Piergiorgio

    2015-04-01

    Normal active degassing at Stromboli (Aeolian Islands, Italy) is traditionally divided in two classes. Puffing correspond to the frequent (~1 Hz) release of small gas pockets (0.5 - 1 m of diameter) at low exit velocities (5 - 15 m/s). Whereas, Strombolian explosions occur at a frequency of 1 - 10 per hour, and are characterized the ejection of bombs and/or ash at high velocities (50 - 400 m/s). In order to get a broader overview of two types of degassing, we used a thermal high speed FLIR SC655 camera to monitor the temperature anomalies generated by the expelled gas, ash, and/or bombs. The enhanced time and spatial resolutions of the camera (200 frames per second, 15 cm wide pixels) enables to use numerical algorithms to distinguish and characterize individual ejection events. In particular, for each explosion and puff, we compute the temperature, the volume, the exit point and the rise velocities of the expelled material. These values, as well as the frequency of the release events, are used to portray a total of 12 vent activities, observed during three field campaigns in 2012, 2013 and 2014. Sustained puffing was visible on 7 cases, with an intensity ranging on at least two orders of magnitude. Although the released gas volume is sometimes highly variable, on some cases, constant sized puffs allows to define a typical discharge frequency ranging between 0.4 and 1.5 Hz. Regular Strombolian explosions, with various duration, intensity and ash contents, are reported in 6 cases, 2 of them simultaneously presenting a puffing activity. In some cases, we noticed modifications of the vent activity just before the explosions. These precursors, usually lasting about 1 second but occasionally reaching 10 seconds, can be sorted into 1) increase of the puffing activity ; 2) emission of gas plumes ; 3) inflation of the visible vent surface. Finally, one vent activity was hybrid between puffing and Strombolian explosions, with frequent explosions (1 Hz) ejecting numerous

  7. Detection of Putatively Thermophilic Anaerobic Methanotrophs in Diffuse Hydrothermal Vent Fluids

    PubMed Central

    Huber, Julie A.; Chernyh, Nikolay A.; Bonch-Osmolovskaya, Elizaveta A.; Lebedinsky, Alexander V.

    2013-01-01

    The anaerobic oxidation of methane (AOM) is carried out by a globally distributed group of uncultivated Euryarchaeota, the anaerobic methanotrophic arachaea (ANME). In this work, we used G+C analysis of 16S rRNA genes to identify a putatively thermophilic ANME group and applied newly designed primers to study its distribution in low-temperature diffuse vent fluids from deep-sea hydrothermal vents. We found that the G+C content of the 16S rRNA genes (PGC) is significantly higher in the ANME-1GBa group than in other ANME groups. Based on the positive correlation between the PGC and optimal growth temperatures (Topt) of archaea, we hypothesize that the ANME-1GBa group is adapted to thrive at high temperatures. We designed specific 16S rRNA gene-targeted primers for the ANME-1 cluster to detect all phylogenetic groups within this cluster, including the deeply branching ANME-1GBa group. The primers were successfully tested both in silico and in experiments with sediment samples where ANME-1 phylotypes had previously been detected. The primers were further used to screen for the ANME-1 microorganisms in diffuse vent fluid samples from deep-sea hydrothermal vents in the Pacific Ocean, and sequences belonging to the ANME-1 cluster were detected in four individual vents. Phylotypes belonging to the ANME-1GBa group dominated in clone libraries from three of these vents. Our findings provide evidence of existence of a putatively extremely thermophilic group of methanotrophic archaea that occur in geographically and geologically distinct marine hydrothermal habitats. PMID:23183981

  8. Constraints on hydrocarbon and organic acid abundances in hydrothermal fluids at the Von Damm vent field, Mid-Cayman Rise (Invited)

    NASA Astrophysics Data System (ADS)

    McDermott, J. M.; Seewald, J.; German, C. R.; Sylva, S. P.

    2013-12-01

    The generation of organic compounds in vent fluids has been of interest since the discovery of seafloor hydrothermal systems, due to implications for the sustenance of present-day microbial populations and their potential role in the origin of life on early Earth. Possible sources of organic compounds in hydrothermal systems include microbial production, thermogenic degradation of organic material, and abiotic synthesis. Abiotic organic synthesis reactions may occur during active circulation of seawater-derived fluids through the oceanic crust or within olivine-hosted fluid inclusions containing carbon-rich magmatic volatiles. H2-rich end-member fluids at the Von Damm vent field on the Mid-Cayman Rise, where fluid temperatures reach 226°C, provide an exciting opportunity to examine the extent of abiotic carbon transformations in a highly reducing system. Our results indicate multiple sources of carbon compounds in vent fluids at Von Damm. An ultramafic-influenced hydrothermal system located on the Mount Dent oceanic core complex at 2350 m depth, Von Damm vent fluids contain H2, CH4, and C2+ hydrocarbons in high abundance relative to basalt-hosted vent fields, and in similar abundance to other ultramafic-hosted systems, such as Rainbow and Lost City. The CO2 content and isotopic composition in end-member fluids are virtually identical to bottom seawater, suggesting that seawater DIC is unchanged during hydrothermal circulation of seawater-derived fluids. Accordingly, end-member CH4 that is present in slightly greater abundance than CO2 cannot be generated from reduction of aqueous CO2 during hydrothermal circulation. We postulate that CH4 and C2+ hydrocarbons that are abundantly present in Von Damm vent fluids reflect leaching of fluids from carbon- and H2-rich fluid inclusions hosted in plutonic rocks. Geochemical modeling of carbon speciation in the Von Damm fluids suggests that the relative abundances of CH4, C2+ hydrocarbons, and CO2 are consistent with

  9. Geochemistry of reduced fluids from shallow cold vents hosting chemosynthetic communities (Comau Fjord, Chilean Patagonia, ∼42°S)

    NASA Astrophysics Data System (ADS)

    Muñoz, Práxedes; Sellanes, Javier; Villalobos, Katherine; Zapata-Hernández, Germán; Mayr, Christoph; Araya, Karen

    2014-12-01

    Reduced fluids from shallow-marine vents sustain chemosynthetic bacterial mats located at the base of the volcano Barranco Colorado in Comau Fjord (X-Huinay; 42°23.279‧S, 72°27.635‧W). We characterized the chemical environment in which these bacteria thrive. To this end, we analyzed CH4, ∑H2S, O2, DIC, and stable isotopes (δ13C, δ2H and δ18O) and compared them with readings taken at a control station (which lacks evidence of fluid venting and mat-forming bacteria). In addition, CTD measurements, chlorophyll-a, and nutrient analyses were performed. At depths of approximately 5-7 m, the water column exhibited a pycnocline that formed under the influence of fresh water discharges, especially during the summer season, which also affected the surface temperature. Bacterial mats and elemental sulfur flocs were observed in the vicinity of the vents (X-Huinay station), and higher concentrations of reduced compounds (CH4 and ∑H2S) were found in the vent fluids, in particular at a depth of 36 m. No significant differences in the temperatures of vent and ambient waters were detected. The bottom water close to the vents possessed notably low concentrations of reduced compounds, indicating a rapid and large-quantity dilution of the chemicals from vents. The surface water featured light isotopic values of δ2H and 18O due to the freshwater input from melting ice and precipitation. A linear mixing trend was observed between the freshwater (negative isotopic values) and the fjord bottom water (positive values) that was not influenced by vent fluid. This trend suggests that the venting water corresponds to the mixing among local meteoric water, spring water, and seawater. This result is relevant to understanding how freshwater and meteoric water influence the chemical composition of seawater and how this mixing could impact the marine biota in the vicinities of the vents.

  10. Enhancing commerical aircraft explosion survivability via active venting

    NASA Astrophysics Data System (ADS)

    Veldman, Roger Lee

    2001-10-01

    A new technique for enhancing aircraft safety in the event of an on-board explosion was studied. The method under study employs deployable vent panels located on the fuselage which are activated by an array of pressure sensors in the aircraft interior. In the event that an explosion is detected, appropriate vent panels are rapidly released from the aircraft. This approach seeks to provide timely relief of explosive pressures within an aircraft to prevent catastrophic structural failure. In this study, the approximate time scale of an explosive detonation and the subsequent sensing and electronic processing was determined. Then, the actuation response times of several vent panel systems were determined through analytical modeling and scale-model experimental testing with good correlation achieved. A scale-model experimental analysis was also conducted to determine the decompression venting time of an aircraft fuselage under a variety of conditions. Two different sized pressure vessels were used in the experimental work and the results correlated quite favorably with an analytical model for decompression times. Finally, a dynamic finite element analysis was conducted to determine the response of a portion of a typical commercial aircraft fuselage subjected to explosive pressure loading. It was determined from this analysis that the pre-stressing of the fuselage from cabin pressurization increases the damage vulnerability of a commercial aircraft fuselage to internal explosions. It was also learned from the structural analysis that the peak fuselage strains due to blast loading occur quickly (within approximately 2 milliseconds) while it was conservatively estimated that approximately 5 to 7 milliseconds would be required to sense the explosion, to actuate selected vent panels, and to initiate the release of cabin pressure from the aircraft. Additionally, since it was determined that predicted fuselage strains for both pressurized and unpressurized load cases remained

  11. Recent Investigation of In-Situ pH in Hydrothermal Vent Fluids at Main Endeavour Field (MEF) and ASHES Vent Field (ASHES): Implications for Dynamic Changes in Subseafloor Hydrothermal System

    NASA Astrophysics Data System (ADS)

    Ding, K.; Seyfried, W. E., Jr.; Tan, C.; Schaen, A. T.; Luhmann, A. J.

    2014-12-01

    In-situ pH is among the key factors affecting chemical reactions involved with fluid-rock interaction and metal transport in hydrothermal systems. A small variation in pH will often result in a large difference in dissolved metal concentrations. For instance, at 400oC, a decrease of ~0.15 pH unit will cause dissolved Fe concentration to double in fluid coexisting with a Fe-bearing mineral assemblage. This parameter also offers us an opportunity to better understand processes controlling the temporal evolution of hydrothermal vent fluid chemistry at mid-ocean ridges. During our recent cruise AT 26-17 with newly upgraded DSV2 Alvin, in-situ measurements of pH were carried out along with gas-tight sampling of vent fluids. Our efforts were focused at MEF and ASHES on the Juan de Fuca Ridge. These hydrothermal systems have been shown to be particularly responsive to subseafloor seismic and magmatic events. The measured fluid temperature was approximately 333˚C and 300˚C at Dante vent orifice of MEF and Inferno vent orifice of ASHES, respectively. The corresponding measured in-situ pH values for both vents are: 4.94 and 4.88, respectively. Dissolved gases and other species were also measured from gas-tight fluid samples providing a means of comparison with the in-situ data. As we have known the earthquake and magmatic activity often places the system at higher temperature and more reducing conditions in connection with a new evolutionary cycle. Comparing these relatively low in-situ pH values with those measured in the past, especially with the ones obtained at MEF in 1999 after an intense swarm of earthquakes, we see the system trending towards more acidic conditions along with decreasing temperature and dissolved H2 and H2S. Taking an example from Dante vent site, in-situ pH value of 5.15 was recorded with a measured temperature of 363oC two month after the event in 1999, which gives 0.2 pH unit greater than the more recent data. Measured dissolved H2 and H2S

  12. Investigation of extractable organic compounds in deep-sea hydrothermal vent fluids along the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    McCollom, Thomas M.; Seewald, Jeffrey S.; German, Christopher R.

    2015-05-01

    The possibility that deep-sea hydrothermal vents may contain organic compounds produced by abiotic synthesis or by microbial communities living deep beneath the surface has led to numerous studies of the organic composition of vent fluids. Most of these studies have focused on methane and other light hydrocarbons, while the possible occurrence of more complex organic compounds in the fluids has remained largely unstudied. To address this issue, the presence of higher molecular weight organic compounds in deep-sea hydrothermal fluids was assessed at three sites along the Mid-Atlantic Ridge that span a range of temperatures (51 to >360 °C), fluid compositions, and host-rock lithologies (mafic to ultramafic). Samples were obtained at several sites within the Lucky Strike, Rainbow, and Lost City hydrothermal fields. Three methods were employed to extract organic compounds for analysis, including liquid:liquid extraction, cold trapping on the walls of a coil of titanium tubing, and pumping fluids through cartridges filled with solid phase extraction (SPE) sorbents. The only samples to consistently yield high amounts of extractable organic compounds were the warm (51-91 °C), highly alkaline fluids from Lost City, which contained elevated concentrations of C8, C10, and C12n-alkanoic acids and, in some cases, trithiolane, hexadecanol, squalene, and cholesterol. Collectively, the C8-C12 acids can account for about 15% of the total dissolved organic carbon in the Lost City fluids. The even-carbon-number predominance of the alkanoic acids indicates a biological origin, but it is unclear whether these compounds are derived from microbial activity occurring within the hydrothermal chimney proximal to the site of fluid discharge or are transported from deeper within the system. Hydrothermal fluids from the Lucky Strike and Rainbow fields were characterized by an overall scarcity of extractable dissolved organic compounds. Trace amounts of aromatic hydrocarbons including

  13. Plume-Vent Fluid Connections along the Tonga-Kermadec arc

    NASA Astrophysics Data System (ADS)

    Massoth, G. J.; Arculus, R. J.; Baker, E. T.; Butterfield, D. A.; Chadwick, W. W.; Christenson, B. W.; de Ronde, C. E.; Embley, R. W.; Evans, L. J.; Faure, K.; Graham, I. J.; Greene, R. R.; Ishibashi, J.; Lebon, G. T.; Lupton, J. E.; Resing, J. A.; Roe, K. K.; Schmidt, M.; Stoffers, P.; Walker, S. L.; Worthington, T. J.; Wright, I. C.; Yamanaka, T.

    2005-12-01

    The full extent of the 2530 km-long Tonga-Kermadec intra-oceanic arc was systematically surveyed for hydrothermal plume emissions during 5 expeditions between 1999 and 2005: NZAPLUME I, II and III covered the Kermadec arc using the New Zealand RV TANGAROA and the TELVE and NoToVE cruises surveyed the Tonga arc aboard the Australian RV SOUTHERN SURVEYOR after preliminary swath mapping by the German RV SONNE. At least 71 volcanic centers comprise the arc front, with about 75% of these first mapped or newly discovered during the expeditions. Hydrothermal plumes were detected as light scattering and chemical anomalies over more than half (36) of the volcanoes surveyed. Forty submersible dives were made on one-third (12) of the hydrothermally active volcanoes during the past year: 4 inaugural dives by the Japanese submersible SHINKAI 6500 on Brothers volcano, and 36 dives using the NOAA/HURL submersibles PISCES IV and V on Brothers and an additional 11 volcanoes spread along the arc front. At least 25 venting sites were observed, and most were sampled for gaseous and liquid hydrothermal fluid emanations. We will summarize the pre-dive plume detection results with emphasis on the variability in the magnitude and character of the chemical signals over the active sites and compare/test predictions of the nature of seafloor sources at dive sites with what was actually observed. While most chemical determinations for the seafloor samples are pending, analyses conducted shipboard confirm that simple extension of plume results to the seafloor can be misleading and in contrast to the MOR experience.

  14. Hydrothermal fluids vented at shallow depths at the Aeolian islands: relationships with volcanic and geothermal systems.

    NASA Astrophysics Data System (ADS)

    Italiano, Francesco; Caracausi, Antonio; Longo, Manfredi; Maugeri, Roberto; Paonita, Antonio

    2010-05-01

    lower values detected in venting gases from active volcanoes (e.g. Vulcano and Panarea). The explanation of such a difference is not related to the volcanic activity at all, but to the parent mantle that in the western side looks to be less contaminated compared to the eastern side. Crustal contamination has been invoked by several authors as the main factor that caused the dramatic 3He/4He decrease. Although the parent mantle produced magmas with different isotopic signature, the gas phase looks similar. To explain the results of the chemical analyses it is proposed that similar deep boundary conditions (pressure, temperature, oxidation level) act as buffers for the chemical composition of the venting gases. With the aim of investigating their origin, estimations of the deep equilibration conditions have been carried out. The reactive compounds detected in the sampled gases, largely used for geothermometric and geobarometric considerations of hydrothermal fluids were used in a system based on the CH4-CO-CO2 contents assuming the presence of a boiling aqueous solution. The equilibrium constants of the adopted reactions are a function of temperature and oxygen fugacity, being the latter buffered by the mineral assemblage of the host rocks. Due to the similarity in the chemical composition of the gases vented at all the islands, a theoretical model developed to interpret the chemical composition of the gases released at Panarea during the last volcanic crisis is here applied. The results have shown that geothermal boiling systems are detectable at all the islands with temperatures up to 350°C. The adopted geo-thermobarometric system is more sensitive to the contents of CO and CH4 than that of CO2, implying that although GWI induce modifications in the chemical composition, the estimated equilibrium temperatures do not change very much for variations of the CO2 content in the range of several volume percent, thus, whether or not the gaseous mixture underwent GWI. Moreover

  15. Vented Tank Resupply Experiment Demonstrated Vane Propellant Management Device for Fluid Transfer

    NASA Technical Reports Server (NTRS)

    Chato, David J.

    1998-01-01

    The Vented Tank Resupply Experiment (VTRE) flown on STS-77 confirmed the design approaches presently used in the development of vane-type propellant management devices (PMD) for use in resupply and tank-venting situations, and it provided the first practical demonstration of an autonomous fluid transfer system. All the objectives were achieved. Transfers were more stable than drop tower testing indicated. Liquid was retained successfully at the highest flow rate tested (2.73 gal/min), demonstrating that rapid fills could be achieved. Liquid-free vents were achieved for two different tanks, although the flow rate was higher for the spherical tank (0.1591 cu ft/min) than for the tank with a short barrel section (0.0400 cu ft/min). Recovery from a thruster firing, which moved the liquid to the opposite end of the tank from the PMD, was achieved in 30 sec, showing that liquid rewicked more quickly into the PMD after thruster firing than pretest projections had predicted. In addition, researchers obtained great insights into the PMD behavior from the video footage provided, and discovered new considerations for future PMD designs that would not have been seen without this flight test.

  16. Fluid flow and sound generation at hydrothermal vent fields. Doctoral thesis

    SciTech Connect

    Little, S.A.

    1988-04-01

    Several experiments in this thesis examine methods to measure and monitor fluid flow from hydrothermal vent fields. Simultaneous velocity temperature, and conductivity data were collected in the convective flow emanating from a hydrothermal vent field located on the East Pacific rise. The horizontal profiles obtained indicate that the flow field approaches an ideal plume in the temperature and velocity distribution. Such parameters as total heat flow and maximum plume height can be estimated using either the velocity or the temperature information. The results of these independent calculations are in close agreement, yielding a total heat capacity and volume changes slightly alter the calculations applied to obtain these values. In Guaymas Basin, a twelve day time series of temperature data was collected from a point three centimeters above a diffuse hydrothermal flow area. Using concurrent tidal gauge data from the town of Guaymas it is shown that the effects of tidal currents can be strong enough to dominate the time variability of a temperature signal at a fixed point in hydrothermal flow and are a plausible explanation for the variations seen in the Guaymas Basin temperature data. The increase in power due to convected flow inhomogeneities, however, was lower in the near field than expected. Indirect evidence of hydrothermal sound fields showing anomalous high power and low frequency noise associated with vents is due to processes other than jet noise.

  17. No Vent Tank Fill and Transfer Line Chilldown Analysis by Generalized Fluid System Simulation Program (GFSSP)

    NASA Technical Reports Server (NTRS)

    Majumdar, Alok

    2013-01-01

    The purpose of the paper is to present the analytical capability developed to model no vent chill and fill of cryogenic tank to support CPST (Cryogenic Propellant Storage and Transfer) program. Generalized Fluid System Simulation Program (GFSSP) was adapted to simulate charge-holdvent method of Tank Chilldown. GFSSP models were developed to simulate chilldown of LH2 tank in K-site Test Facility and numerical predictions were compared with test data. The report also describes the modeling technique of simulating the chilldown of a cryogenic transfer line and GFSSP models were developed to simulate the chilldown of a long transfer line and compared with test data.

  18. In situ Raman-based detections of the hydrothermal vent and cold seep fluids

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Du, Zengfeng; Zheng, Ronger; Luan, Zhendong; Qi, Fujun; Cheng, Kai; Wang, Bing; Ye, Wangquan; Liu, Xiaorui; Chen, Changan; Guo, Jinjia; Li, Ying; Yan, Jun

    2016-04-01

    Hydrothermal vents and cold seeps, and their associated biological communities play an important role in global carbon and sulphur biogeochemical cycles. Most of the studies of fluid composition geochemistry are based on recovered samples, both with gas-tight samplers and as open specimens, but the in situ conditions are difficult to maintain in recovered samples. Determination in situ of the chemical signals of the emerging fluids are challenging due to the high pressure, often strongly acidic and temperature in which few sensors can survive. Most of those sensors used so far are based on electrochemistry, and can typically detect only a few chemical species. Here we show that direct measurement of critical chemical species of hydrothermal vents and cold seeps can be made rapidly and in situ by means of a new hybrid version of earlier deep-sea pore water Raman probe carried on the ROV (Remote Operated Vehicle) Faxian. The fluid was drawn through the probe by actuating a hydraulic pump on the ROV, and measured at the probe optical cell through a sapphire window. We have observed the concentrations of H2S, HS‑, SO42‑, HSO4‑, CO2, and H2 in hydrothermal vent fluids from the Pacmanus and Desmos vent systems in the Manus back-arc basin, Papua New Guinea. Two black smokers (279° C and 186° C) at the Pacmanus site showed the characteristic loss of SO42‑, and the increase of CO2 and well resolved H2S and HS‑ peaks. At the white smoker of Onsen site the strong HSO4‑peak observed at high temperature quickly dropped with strong accompanying increase of SO42‑and H2 peaks when the sample contained in the Raman sensing cell was removed from the hot fluid due to rapid thermal deprotonation. We report here also the finding of a new lower temperature (88° C) white smoker "Kexue" field at the Desmos site with strong H2S, HS‑ and CO2 signals. We also have detected the concentrations of CH4,H2S, HS‑, SO42‑, and S8 in cold seep fluids and the surrounding

  19. Microbially-Mediated Sulfur Oxidation in Diffuse Hydrothermal Vent Fluids at Axial Seamount, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Akerman, N. H.; Butterfield, D. A.; Huber, J. A.

    2011-12-01

    Diffusely venting hydrothermal fluids can act as a window to the subseafloor microbial environment, where chemically-reduced hydrothermal fluids mixing with oxygenated seawater in the shallow crust creates chemical disequilibria that chemotrophic microorganisms can exploit for energy gain. At Axial Seamount, an active deep-sea volcano located on the Juan de Fuca Ridge, sulfide concentrations have been measured as high as 5770 μM, and sulfide oxidation is quantitatively the most important chemical energy source for microbial metabolism. In addition, studies of microbial population structure indicate that diffuse fluids at Axial are dominated by putative sulfur- and sulfide-oxidizing bacteria belonging to the Epsilonproteobacteria. To further study this important microbial process, we surveyed diffuse vent samples from Axial over a range of temperature, pH, and sulfide concentrations for the presence and expression of sulfide-oxidizing bacteria using a functional gene approach. Dissolved oxygen concentrations decrease exponentially above 40°C and lower the potential for sulfide oxidation, so we identified six sites of different temperatures, two each in the low (< 30°C), medium (~30°C), and high temperature (30 - 50°C) range. The low temperature sites had sulfide-to-temperature ratios of 1 - 26, the medium from 15 - 29, and the high from 26 - 36. PCR primers were designed to target the sulfur oxidation gene soxB specifically from Epsilonproteobacteria and five of the six sites were positive for soxB in the DNA fraction. Bulk RNA was also extracted from the same sites to examine in situ expression of soxB. Data from these analyses, along with quantification of the soxB gene abundance and expression using quantitative PCR, are currently being carried out. Together, this data set of soxB gene diversity, expression, and abundance along with geochemical data will allow us to quantitatively determine the functional dynamics of sulfide oxidation in the subseafloor at

  20. Subseafloor microbial communities in hydrogen-rich vent fluids from hydrothermal systems along the Mid-Cayman Rise.

    PubMed

    Reveillaud, Julie; Reddington, Emily; McDermott, Jill; Algar, Christopher; Meyer, Julie L; Sylva, Sean; Seewald, Jeffrey; German, Christopher R; Huber, Julie A

    2016-06-01

    Warm fluids emanating from hydrothermal vents can be used as windows into the rocky subseafloor habitat and its resident microbial community. Two new vent systems on the Mid-Cayman Rise each exhibits novel geologic settings and distinctively hydrogen-rich vent fluid compositions. We have determined and compared the chemistry, potential energy yielding reactions, abundance, community composition, diversity, and function of microbes in venting fluids from both sites: Piccard, the world's deepest vent site, hosted in mafic rocks; and Von Damm, an adjacent, ultramafic-influenced system. Von Damm hosted a wider diversity of lineages and metabolisms in comparison to Piccard, consistent with thermodynamic models that predict more numerous energy sources at ultramafic systems. There was little overlap in the phylotypes found at each site, although similar and dominant hydrogen-utilizing genera were present at both. Despite the differences in community structure, depth, geology, and fluid chemistry, energetic modelling and metagenomic analysis indicate near functional equivalence between Von Damm and Piccard, likely driven by the high hydrogen concentrations and elevated temperatures at both sites. Results are compared with hydrothermal sites worldwide to provide a global perspective on the distinctiveness of these newly discovered sites and the interplay among rocks, fluid composition and life in the subseafloor. PMID:26663423

  1. Genomic variation of subseafloor archaeal and bacterial populations from venting fluids at the Mid-Cayman Rise

    NASA Astrophysics Data System (ADS)

    Anderson, R. E.; Eren, A. M.; Stepanauskas, R.; Huber, J. A.; Reveillaud, J.

    2015-12-01

    Deep-sea hydrothermal vent systems serve as windows to a dynamic, gradient-dominated deep biosphere that is home to a wide diversity of archaea, bacteria, and viruses. Until recently the majority of these microbial lineages were uncultivated, resulting in a poor understanding of how the physical and geochemical context shapes microbial evolution in the deep subsurface. By comparing metagenomes, metatranscriptomes and single-cell genomes between geologically distinct vent fields, we can better understand the relationship between the environment and the evolution of subsurface microbial communities. An ideal setting in which to use this approach is the Mid-Cayman Rise, located on the world's deepest and slowest-spreading mid-ocean ridge, which hosts both the mafic-influenced Piccard and ultramafic-influenced Von Damm vent fields. Previous work has shown that Von Damm has higher taxonomic and metabolic diversity than Piccard, consistent with geochemical model expectations, and the fluids from all vents are enriched in hydrogen (Reveillaud et al., submitted). Mapping of both metagenomes and metatranscriptomes to a combined assembly showed very little overlap among the Von Damm samples, indicating substantial variability that is consistent with the diversity of potential metabolites in this ultramafic vent field. In contrast, the most consistently abundant and active lineage across the Piccard samples was Sulfurovum, a sulfur-oxidizing chemolithotroph that uses nitrate or oxygen as an electron acceptor. Moreover, analysis of point mutations within individual lineages suggested that Sulfurovumat Piccard is under strong selection, whereas microbial genomes at Von Damm were more variable. These results are consistent with the hypothesis that the subsurface environment at Piccard supports the emergence of a dominant lineage that is under strong selection pressure, whereas the more geochemically diverse microbial habitat at Von Damm creates a wider variety of stable

  2. Quantifying net microbial metabolism in the sub-seafloor using the chemical composition of adjacent hot and warm vent fluids

    NASA Astrophysics Data System (ADS)

    Butterfield, D. A.; Holden, J. F.; Roe, K. K.; Lilley, M. D.; Olson, E. J.; Ver Eecke, H. C.; Opatkiewicz, A. D.; Huber, J. A.

    2009-12-01

    Myriad evidence points to the existence and activity of diverse microbial communities living in the sub-seafloor where hot hydrothermal fluids (T>300°C) mix with cold seawater to create thermal and chemical gradients that can support many different metabolic types. When the hot source composition is well characterized, chemical mixing models can be used to compare the expected and actual composition of warm diffuse vents. The differences are attributed to sub-seafloor reactions. In some cases, e.g. for methanogenesis and methanotrophy, the sub-seafloor reactions can be unambiguously attributed to microbial activity. In other cases, e.g. sulfide oxidation, the effects of competing abiotic reactions may sometimes be constrained or simplifying assumptions made to estimate the role of microbial activity. The mixing model concept has been applied before, but there have been very few systematic surveys to quantify sub-seafloor mixing zone reactions on a vent field scale. During two recent expeditions to the Endeavour Integrated Studies Site and Axial Volcano on the Juan de Fuca ridge, NE Pacific, the Hydrothermal Fluid and Particle Sampler was used to collect 6-10 paired samples of adjacent focused and diffuse fluids. Chemical mixing model results show evidence of variable, site-specific sulfide oxidation (loss of 25-94%), methane oxidation (loss of 20-66%), and methanogenesis (3 to 5-fold gain) in the sub-seafloor mixing zone. Laboratory experiments on microbial cultures of Methanocaldococcus jannaschii grew optimally at 82°C with H2 concentrations near 100µM, and showed no measurable growth when H2 concentrations were below 20 µM. Most of the high-temperature sources at Endeavour in 2008/9 have too little hydrogen to provide this concentration range when mixed with enough seawater to bring the temperature below 100°C, producing sub-optimal conditions for methanogens. In many Endeavour vents, we find evidence for loss of methane in the sub-seafloor mixing zone

  3. Microbial biofilms associated with fluid chemistry and megafaunal colonization at post-eruptive deep-sea hydrothermal vents

    NASA Astrophysics Data System (ADS)

    O'Brien, Charles E.; Giovannelli, Donato; Govenar, Breea; Luther, George W.; Lutz, Richard A.; Shank, Timothy M.; Vetriani, Costantino

    2015-11-01

    At deep-sea hydrothermal vents, reduced, super-heated hydrothermal fluids mix with cold, oxygenated seawater. This creates temperature and chemical gradients that support chemosynthetic primary production and a biomass-rich community of invertebrates. In late 2005/early 2006 an eruption occurred on the East Pacific Rise at 9°50‧N, 104°17‧W. Direct observations of the post-eruptive diffuse-flow vents indicated that the earliest colonizers were microbial biofilms. Two cruises in 2006 and 2007 allowed us to monitor and sample the early steps of ecosystem recovery. The main objective of this work was to characterize the composition of microbial biofilms in relation to the temperature and chemistry of the hydrothermal fluids and the observed patterns of megafaunal colonization. The area selected for this study had local seafloor habitats of active diffuse flow (in-flow) interrupted by adjacent habitats with no apparent expulsion of hydrothermal fluids (no-flow). The in-flow habitats were characterized by higher temperatures (1.6-25.2 °C) and H2S concentrations (up to 67.3 μM) than the no-flow habitats, and the microbial biofilms were dominated by chemosynthetic Epsilonproteobacteria. The no-flow habitats had much lower temperatures (1.2-5.2 °C) and H2S concentrations (0.3-2.9 μM), and Gammaproteobacteria dominated the biofilms. Siboglinid tubeworms colonized only in-flow habitats, while they were absent at the no-flow areas, suggesting a correlation between siboglinid tubeworm colonization, active hydrothermal flow, and the composition of chemosynthetic microbial biofilms.

  4. Geochemistry of vent fluid particles formed during initial hydrothermal fluid-seawater mixing along the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Klevenz, Verena; Bach, Wolfgang; Schmidt, Katja; Hentscher, Michael; Koschinsky, Andrea; Petersen, Sven

    2011-10-01

    We present geochemical data of black smoker particulates filtered from hydrothermal fluids with seawater-dilutions ranging from 0-99%. Results indicate the dominance of sulphide minerals (Fe, Cu, and Zn sulphides) in all samples taken at different hydrothermal sites on the Mid-Atlantic Ridge. Pronounced differences in the geochemistry of the particles between Logatchev I and 5°S hydrothermal fields could be attributed to differences in fluid chemistry. Lower metal/sulphur ratios (Me/H2S < 1) compared to Logatchev I result in a larger amount of particles precipitated per liter fluid and the occurrence of elemental sulphur at 5°S, while at Logatchev I Fe oxides occur in larger amounts. Systematic trends with dilution degree of the fluid include the precipitation of large amounts of Cu sulphides at a low dilution and a pronounced drop with increasing dilution. Moreover, Fe (sulphides or oxides) precipitation increases with dilution of the vent fluid by seawater. Geochemical reaction path modeling of hydrothermal fluid-seawater mixing and conductive cooling indicates that Cu sulphide formation at Logatchev I and 5°S mainly occurs at high temperatures and low dilution of the hydrothermal fluid by seawater. Iron precipitation is enhanced at higher fluid dilution, and the different amounts of minerals forming at 5°S and Logatchev I are thermodynamically controlled. Larger total amounts of minerals and larger amounts of sulphide precipitate during the mixing path when compared to the cooling path. Differences between model and field observations do occur and are attributable to closed system modeling, to kinetic influences and possibly to organic constituents of the hydrothermal fluids not accounted for by the model.

  5. Temporal evolution of magmatic-hydrothermal systems in the Manus Basin, Papua New Guinea: Insights from vent fluid chemistry and bathymetric observations

    NASA Astrophysics Data System (ADS)

    Reeves, E. P.; Thal, J.; Schaen, A.; Ono, S.; Seewald, J.; Bach, W.

    2015-12-01

    The temporal evolution of hydrothermal fluids from back-arc systems is poorly constrained, despite growing evidence for dynamic magmatic-hydrothermal activity, and imminent commercial mining. Here we discuss surveys of diverse vent fluids from multiple hydrothermal fields in the Manus back-arc basin, Papua New Guinea, sampled in 2006 and 2011. Effects of host rock composition, and dynamic magmatic volatile inputs on fluid chemistry are evaluated to understand changes in these systems. Highly acidic and SO4-rich moderate temperature fluids (~48-215°C), as well as SO4-poor black smoker fluids (up to 358°C), were collected at the PACMANUS, SuSu Knolls and DESMOS areas in 2006 and 2011. Acidic, milky white SuSu and DESMOS fluids, rich in elemental S and SO4, exit the seafloor with Na, K, Mg, and Ca diluted conservatively up to 30% relative to seawater, implying subsurface mixing of seawater with SO2-rich aqueous fluids exsolved from magma, analogous to subaerial fumarole discharge. SO2 disproportionation during cooling and mixing of magmatic fluids contributes acidity, SO4, H2S and S(0)(s), as well as widespread S outcrops on the seafloor. Nearby black smoker fluids indicate entrainment and reaction of magmatic fluid into convecting fluids at depth, and additional hybrid-type fluids appear to consist of evolved seawater and unreacted magmatic fluid SO2 derivatives. Fluids at DESMOS in 2006 indicate increased magmatic SO2 relative to 1995, despite constant low venting temperatures (~120°C). In contrast, dramatic changes in bathymetry and seafloor morphology point to substantial continuous eruption of volcaniclastic material between 2006 and 2011 at SuSu Knolls, burying fumarolic vents from 2006. Compositions of new 2011 acidic, sulfate-rich fluids there suggest reaction with less altered, fresher rock. At the PACMANUS area, farther from the arc, direct magmatic degassing to the seafloor is not occurring presently, but entrainment and reaction of similar acid

  6. A deep sea Hydrothermal Vent Bio-sampler for large volume in-situ filtration of hydrothermal vent fluids

    NASA Technical Reports Server (NTRS)

    Behar, Alberto; Matthews, Jaret; Venkateswaran, Kasthuri; Bruckner, James; Basic, Goran; So, Edmond; Rivadeneyra, Cesar

    2005-01-01

    This paper provides a physical description of the current system, as well as a summary of the preliminary tests conducted in 2005: a pressure chamber test, a dive test in a 30 foot dive pool, and a dive operation at a hydrothermal vent off the northern coast of Iceland.

  7. A dual sensor device to estimate fluid flow velocity at diffuse hydrothermal vents

    NASA Astrophysics Data System (ADS)

    Sarrazin, J.; Rodier, P.; Tivey, M. K.; Singh, H.; Schultz, A.; Sarradin, P. M.

    2009-11-01

    Numerous attempts have been made over the last thirty years to estimate fluid flow rates at hydrothermal vents, either at the exit of black smoker chimneys or within diffuse flow areas. In this study, we combine two methods to accurately estimate fluid flow velocities at diffuse flow areas. While the first method uses a hot film anemometer that performs high-frequency measurements, the second allows a relatively rapid assessment of fluid flow velocity through video imagery and provides in situ data to calibrate the sensor. Measurements of flow velocities on hydrothermal diffuse flow areas were obtained on the Mid-Atlantic Ridge (MAR). They range from 1.1 to 4.9 mm/s at the substratum level, in low-temperature (4.5-16.4 °C) diffuse flow areas from the Tour Eiffel sulfide edifice. A strong correlation was observed between fluid flow velocities and temperature, supporting the possible use of temperature as a proxy to estimate the flow rates in diffuse flow areas where such a simple linear flow/temperature relation is shown to dominate.

  8. Fluid composition of the sediment-influenced Loki's Castle vent field at the ultra-slow spreading Arctic Mid-Ocean Ridge

    NASA Astrophysics Data System (ADS)

    Baumberger, Tamara; Früh-Green, Gretchen L.; Thorseth, Ingunn H.; Lilley, Marvin D.; Hamelin, Cédric; Bernasconi, Stefano M.; Okland, Ingeborg E.; Pedersen, Rolf B.

    2016-08-01

    The hydrothermal vent field Loki's Castle is located in the Mohns-Knipovich bend (73°N) of the ultraslow spreading Arctic Mid-Ocean Ridge (AMOR) close to the Bear Island sediment fan. The hydrothermal field is venting up to 320° C hot black smoker fluids near the summit of an axial volcanic ridge. Even though the active chimneys have grown on a basaltic ridge, geochemical fluid data show a strong sedimentary influence into the hydrothermal circulation at Loki's Castle. Compelling evidence for a sediment input is given by high alkalinity, high concentrations of NH4+, H2, CH4, C2+ hydrocarbons as well as low Mn and Fe contents. The low δ13C values of CO2 and CH4 and the thermogenic isotopic pattern of the C2+ hydrocarbons in the high-temperature vent fluids clearly point to thermal degradation of sedimentary organic matter and illustrate diminution of the natural carbon sequestration in sediments by hydrothermal circulation. Thus, carbon-release to the hydrosphere in Arctic regions is especially relevant in areas where the active Arctic Mid-Ocean Ridge system is in contact with the organic matter rich detrital sediment fans.

  9. Fluid flow rate, temperature and heat flux at Mohns Ridge vent fields: evidence from isosampler measurements for phase separated hydrothermal circulation along the arctic ridge system

    NASA Astrophysics Data System (ADS)

    Schultz, A.; Pedersen, R. B.; Thorseth, I. H.; Taylor, P.; Flynn, M.

    2005-12-01

    An expedition to the Mohns Ridge in the Norwegian-Greenland sea was carried out in July-August 2005 as part of BIODEEP, lead by University of Bergen (UoB). UoB had previously detected water column methane along this very slow spreading ridge. Previous ROV observations along the ridge (71 deg 18'N, 5 deg 47'W, 605 mbsl) near Jan Mayen had uncovered a broad area of ferric hydroxide-rich bacterial/mineral assemblages, comprising large populations of gallionella bacteria. This area was revisted in 2005. Characteristic of sections of this area ("Gallionella Garden") are chimney-like structures standing ~15 cm tall, often topped by a sea lily (heliometra glacialis). The interior of the structures comprised quasi-concentric bands with vertically-oriented channels. The Oregon State University/Cardiff University Isosampler sensor determined that some of these assemblages support fluid flow through their interior. The outflow from the chimney structures was typically +0.5 deg C, against background temperatures of -0.3 deg C. Flow anomalies were also identified atop extensive bacterial mats. Gallionella Gardens is several km in extent with active, albeit extremely low temperature hydrothermal flow. A field of active high temperature smoker chimney structures was located near Gallionella Garden at 540 mbsl. This field extends ~500 m along a scarp wall, with hydrothermal mounds extending along faults running perpendicular to the scarp, each of which has multiple smoker vents and areas of diffuse flow. There was evidence for phase separation, with a negatively buoyant fluid phase exiting some vent orifices and descending along the vent wall; and evidence for gas phase condensing after leaving some vent orifices. Gas bubble emissions were not uncommon. Isosampler sensors were available that were configured for lower temperature measurements at Gallionella Garden. While capable of detecting variations in effluent at the 4 millidegree level, the temperature ceiling for the sensor

  10. Vent fluid chemistry of the Rainbow hydrothermal system (36°N, MAR): Phase equilibria and in situ pH controls on subseafloor alteration processes

    NASA Astrophysics Data System (ADS)

    Seyfried, W. E., Jr.; Pester, Nicholas J.; Ding, Kang; Rough, Mikaella

    2011-03-01

    The Rainbow hydrothermal field is located at 36°13.8'N-33°54.15'W at 2300 m depth on the western flank of a non-volcanic ridge between the South AMAR and AMAR segments of the Mid-Atlantic Ridge. The hydrothermal field consists of 10-15 active chimneys that emit high-temperature (˜365 °C) fluid. In July 2008, vent fluids were sampled during cruise KNOX18RR, providing a rich dataset that extends in time information on subseafloor chemical and physical processes controlling vent fluid chemistry at Rainbow. Data suggest that the Mg concentration of the hydrothermal end-member is not zero, but rather 1.5-2 mmol/kg. This surprising result may be caused by a combination of factors including moderately low dissolved silica, low pH, and elevated chloride of the hydrothermal fluid. Combining end-member Mg data with analogous data for dissolved Fe, Si, Al, Ca, and H 2, permits calculation of mineral saturation states for minerals thought appropriate for ultramafic-hosted hydrothermal systems at temperatures and pressures in keeping with constraints imposed by field observations. These data indicate that chlorite solid solution, talc, and magnetite achieve saturation in Rainbow vent fluid at a similar pH (T,P) (400 °C, 500 bar) of approximately 4.95, while higher pH values are indicated for serpentine, suggesting that serpentine may not coexist with the former assemblage at depth at Rainbow. The high Fe/Mg ratio of the Rainbow vent fluid notwithstanding, the mole fraction of clinochlore and chamosite components of chlorite solid solution at depth are predicted to be 0.78 and 0.22, respectively. In situ pH measurements made at Rainbow vents are in good agreement with pH (T,P) values estimated from mineral solubility calculations, when the in situ pH data are adjusted for temperature and pressure. Calculations further indicate that pH (T,P) and dissolved H 2 are extremely sensitive to changes in dissolved silica owing to constraints imposed by chlorite solid solution-fluid

  11. Tectonic context of fluid venting at the toe of the eastern Nankai accretionary prism: Evidence for a shallow detachment fault

    NASA Astrophysics Data System (ADS)

    Chamot-Rooke, N.; Lallemant, S. J.; Le Pichon, X.; Henry, P.; Sibuet, M.; Boulègue, J.; Foucher, J.-P.; Furuta, T.; Gamo, T.; Glaçon, G.; Kobayashi, K.; Kuramoto, S.; Ogawa, Y.; Schultheiss, P.; Segawa, J.; Takeuchi, A.; Tarits, P.; Tokuyama, H.

    1992-04-01

    During the Kaiko-Nankai diving cruise the peak of the venting activity was located near the top of the very first anticline. The most prominent morphological feature between the mid-slope (3870 m) and the apex of the fold (3770 m) is a 20 m high cliff cutting through subhorizontal massive mudstones affected by numerous joints. The trend of this scarp is oblique to the fold axis and structurally controlled along two sharply defined NNE-SSE and E-W directions. Fresh talus and blocks found locally suggest active tectonics and recent erosion. Intense deformation is evident from strongly tilted strata restricted to the base of the cliff that we interpret as an upslope thrust. At the scale of Seabeam mapping, this thrust can be followed eastward for more than 5 km along the 3820 m isobath. Two seismic lines recorded during one of the pre-site surveys show deformation at shallow depth, including small-scale folding and thrusting affecting only the wedge-shaped top sequence. Deeper layers can be traced continuously below this sequence. We conclude that the boundary between the "piggy-back" basin and the frontal fold turbidites acts as a shallow detachment fault, and interpret the base of the cliff as the outcrop of the fault. Dense colonies ofCalyptogena clams and strongly nonlinear thermal gradients locate the major peak of fluid activity at the edge of the plateau above the main cliff. Scattered biological colonies as well as white bacterial mats and cemented chimneys were also found in a narrow belt along the base of the cliff. Fluid activity is thus closely related to the shallow detachment fault, fluid being expelled both at the outcrop of the fault and above it through the overlying strata, possibly using the very dense joint network.

  12. First hydrothermal active vent discovered on the Galapagos Microplate

    NASA Astrophysics Data System (ADS)

    Tao, C.; Li, H.; Wu, G.; Su, X.; Zhang, G.; Chinese DY115-21 Leg 3 Scientific Party

    2011-12-01

    The Galapagos Microplate (GM) lies on the western Gaplapagos Spreading Center (GSC), representing one of the classic Ridge-Ridge-Ridge (R-R-R) plate boundaries of the Nazca, Cocos, and Pacific plates. The presence of the 'black smoke' and hydrothermal vent community were firstly confirmed on the GSC. Lots of hydrothermal fields were discovered on the center and eastern GSC, while the western GSC has not been well investigated. During 17th Oct. to 9th Nov. 2009, the 3rd leg of Chinese DY115-21 cruise with R/V Dayangyihao has been launched along 2°N-5°S near equatorial East Pacific Rise (EPR). Two new hydrothermal fields were confirmed. One is named 'Precious Stone Mountain', which is the first hydrothermal field on the GM. The other is found at 101.47°W, 0.84°S EPR. The 'Precious Stone Mountain' hydrothermal field (at 101.49°W, 1.22°N) is located at an off-axial seamount on the southern GM boundary, with a depth from 1,450 to 1,700m. Hydrothermal fluids emitting from the fissures and hydrothermal fauna were captured by deep-tow video. Few mineral clasts of pyrite and chalcopyrite were separated from one sediment sample, but no sulfide chimney was found yet. Hydrothermal fauna such as alive mussels, crabs, shrimps, tubeworms, giant clams, as well as rock samples were collected by TV-Grab. The study of the seafloor classification with Simrad EM120 multi-beam echosounder has been conducted on the 'Precious Stone Mountain' hydrothermal field. The result indicates that seafloor materials around the hydrothermal field can be characterized into three types, such as the fresh lava, hydrothermal sediment, and altered rock.

  13. Uniformity and diversity in the composition of mineralizing fluids from hydrothermal vents on the southern Juan de Fuca Ridge

    SciTech Connect

    Philpotts, J.A.; Aruscavage, P.J.; Von Damm, K.L.

    1987-10-10

    Abundances of Li, Ni, K, Rb, Ca, Sr, Ba, Mn, Fe, Zn, and Si have been determined in fluid samples from seven vents located in three areas on the southern Juan de Fuca Ridge. The hydrothermal component estimated from the Mg contents of the samples ranges from 7% to 76%. Concentrations of Fe and Si, among the other elements, in acid-stabilized solutions appear to be generally representative of the parental hydrothermal fluids, but some Zn determinations and most Ba values appear to be too low. Thermodynamic calculations indicate that the acidified samples remain supersaturated with respect to silica, barite, and pyrite; unacidified samples are supersaturated, in addition with respect to ZnS, FeS, and many silicate phases. Within the constraints of limited sampling there appear to be differences in fluid compositions both within and between the three vent areas. Some uniform differences in the elemental abundances predicted for hydrothermal end-member fluids might be due to inmixing of fresh seawater at depth in the hydrothermal system. The Juan de Fuca hydrothermal fluids contain more Fe but otherwise have relative elemental abundances fairly similar to those in 13 /sup 0/N (East Pacific Rise) fluids, albeit at higher levels. In contrast, fluids from 21 /sup 0/N (East Pacific Rise) and Galapagos have lower K/Rb and much lower Sr and Na abundances; these compositional features probably result from interaction of these fluids with a different mineral assemblage, possibly more mature greenstone. copyright American Geophysical Union 1987

  14. Gas venting system

    SciTech Connect

    Khan, Amjad; Dreier, Ken Wayne; Moulthrop, Lawrence Clinton; White, Erik James

    2010-06-29

    A system to vent a moist gas stream is disclosed. The system includes an enclosure and an electrochemical cell disposed within the enclosure, the electrochemical cell productive of the moist gas stream. A first vent is in fluid communication with the electrochemical cell for venting the moist gas stream to an exterior of the enclosure, and a second vent is in fluid communication with an interior of the enclosure and in thermal communication with the first vent for discharging heated air to the exterior of the enclosure. At least a portion of the discharging heated air is for preventing freezing of the moist gas stream within the first vent.

  15. Vented transmission

    SciTech Connect

    Nguyen, T.H.

    1990-01-29

    This patent describes a vented transmission. It comprises: a housing; a rotary input to the housing; a rotary output from the housing; transmission means within the housing interconnecting the input and the output and including a hollow, rotary shaft journaled within the housing; a vent tube having a first end extending into one end of the hollow shaft and a second end in fluid communication with the exterior of the housing; a shoulder within the hollow shaft and intermediate the ends of the vent tube and defining of relatively smaller diameter section near the first end of the vent tube that is within the hollow shaft and a relatively large diameter section nearer the second end of the vent tube; at least one aperture extending through the hollow shaft from the large diameter section immediately adjacent the shoulder; and a labyrinth seal at the interface of the vent tube and the large diameter section at a location between the aperture (s) and the second end of the vent tube.

  16. Fluid and thermal mixing in a model cold leg and downcomer with vent-valve flow. [PWR

    SciTech Connect

    Rothe, P.H.; Marscher, W.D.; Block, J.A.

    1982-03-01

    This report describes an experimental program of fluid mixing experiments performed at atmospheric pressure in a 1/5-scale transparent model of the cold leg and downcomer of typical Babcock and Wilcox pressurized water reactors with vent valves. The results include transient data from a grid of thermocouples and extensive flow visualization photographs. Substantial mixing of cold injected water with hot primary coolant occurred during many of the tests.

  17. Stable isotope studies of vent fluids and chimney minerals, southern Juan de Fuca Ridge: Sodium metasomatism and seawater sulfate reduction

    SciTech Connect

    Shanks W.C. III; Seyfried W.E. Jr.

    1987-10-10

    Sulfur isotope values (delta/sup 34/S) or H/sub 2/S in vent fluids from the southern Juan de Fuca Ridge hydrothermal sites range from 4.0 to 7.4% and are variably /sup 34/S-enriched with respect to coexisting inner wall chimney sulfides. Chimney sulfides range from 1.6 to 5.7%. The chimneys consist of Fe-sphalerite zoned to inner zinc sulfide and chalcopyrite ( +- isocubanite)-pyrrhotite lining channels. Sulfide from inner walls of type A chimneys have the lightest delta/sup 34/S values. Type B chimneys (porous, unzoned, low-Fe-sphalerite) have the isotopically heaviest chimney sulfides and occur at vent sites distal to the along-axis shallow point of the ridge crest, hence distal to the magma chamber. These variations are largely ascribed to sulfate reduction by ferrous iron in the hydrothermal fluid in chimneys of substrate mounds, probably due to transitory entrainment of ambient sulfate-bearing seawater. The delta/sup 18/O values of end-member hydrothermal fluids range from 0.6 to 0.8%, significantly lower than the delta/sup 18/O values at 21 /sup 0/N vent fluids. The deltaD values of the fluid samples range from -2.5 to 0.5%. Isotopic differences from the 21 /sup 0/N fluids may be due to slightly higher water/rock ratios, approximately 1.0, in the southern Juan de Fuca Ridge hydrothermal system. Admixture of a small amount of residual brine from an earlier phase separation even may have contributed water with low deltaD values.

  18. Near-bottom water column anomalies associated with active hydrothermal venting at Aeolian arc volcanoes, Tyrrhenian Sea, Italy

    NASA Astrophysics Data System (ADS)

    Walker, S. L.; Carey, S.; Bell, K. L.; Baker, E. T.; Faure, K.; Rosi, M.; Marani, M.; Nomikou, P.

    2012-12-01

    Hydrothermal deposits such as metalliferous sediments, Fe-Mn crusts, and massive sulfides are common on the submarine volcanoes of the Aeolian arc (Tyrrhenian Sea, Italy), but the extent and style of active hydrothermal venting is less well known. A systematic water column survey in 2007 found helium isotope ratios indicative of active venting at 6 of the 9 submarine volcanoes surveyed plus the Marsili back-arc spreading center (Lupton et al., 2011). Other plume indicators, such as turbidity and temperature anomalies were weak or not detected. In September 2011, we conducted five ROV Hercules dives at Eolo, Enarete, and Palinuro volcanoes during an E/V Nautilus expedition. Additionally, two dives explored the Casoni seamount on the southern flank of Stromboli where a dredge returned apparently warm lava in 2002 (Gamberi, 2006). Four PMEL MAPRs, with temperature, optical backscatter (particles), and oxidation-reduction potential (ORP) sensors, were arrayed along the lowermost 50 m of the Hercules/Argus cable during the dives to assess the relationship between seafloor observations and water column anomalies. Active venting was observed at each of the volcanoes visited. Particle anomalies were weak or absent, consistent with the 2007 CTD surveys, but ORP anomalies were common. Venting at Eolo volcano was characterized by small, localized patches of yellow-orange bacteria; living tubeworms were observed at one location. ORP anomalies (-1 to -22 mv) were measured at several locations, primarily along the walls of the crescent-shaped collapse area (or possible caldera) east of the Eolo summit. At Enarete volcano, we found venting fluids with temperatures up to 5°C above ambient as well as small, fragile iron-oxide chimneys. The most intense ORP anomaly (-140 mv) occurred at a depth of about 495 m on the southeast side of the volcano, with smaller anomalies (-10 to -20 mv) more common as the ROV moved upslope to the summit. At Palinuro volcano, multiple dives located

  19. Uniformity and diversity in the composition of mineralizing fluids from hydrothermal vents on the southern Juan de Fuca Ridge.

    USGS Publications Warehouse

    Philpotts, J.A.; Aruscavage, P. J.; Von Damm, K. L.

    1987-01-01

    Abundances of Li, Na, K, Rb, Ca, Sr, Ba, Mn, Fe, Zn, and Si have been determined in fluid samples from 7 vents located in three areas on the southern Juan de Fuca Ridge. The hydrothermal component estimated from the Mg contents of the samples ranges from 7% to 76%. Concentrations of Fe and Si, among other elements, in acid-stabilized solutions appear to be generally representative of the parental hydrothermal fluids, but some Zn determinations and most Ba values appear to be too low.-from Authors

  20. Observations of Seafloor Deformation and Methane Venting within an Active Fault Zone Offshore Southern California

    NASA Astrophysics Data System (ADS)

    Anderson, K.; Lundsten, E. M.; Paull, C. K.; Caress, D. W.; Thomas, H. J.; Brewer, P. G.; Vrijenhoek, R.; Lundsten, L.

    2013-12-01

    Detailed mapping surveys of the floor and flanks of the Santa Monica Basin, San Pedro Basin, and San Diego Trough were conducted during the past seven years using an Autonomous Underwater Vehicle (AUV) built and operated by MBARI specifically for seafloor mapping. The AUV collected data provide up to 1 m resolution multibeam bathymetric grids with a vertical precision of 0.15 m. Along with high-resolution multibeam, the AUV also collects chirp seismic reflection profiles. Structures within the uppermost 10-20 m of the seafloor, which in the surveys presented here is composed of recent sediment drape, can typically be resolved in the sub-bottom reflectors. Remotely operated vehicle (ROV) dives allowed for ground-truth observations and sampling within the surveyed areas. The objectives of these dives included finding evidence of recent seafloor deformation and locating areas where chemosynthetic biological communities are supported by fluid venting. Distinctive seafloor features within an active fault zone are revealed in unprecedented detail in the AUV generated maps and seismic reflection profiles. Evidence for recent fault displacements include linear scarps which can be as small as 20 cm high but traceable for several km, right lateral offsets within submarine channels and topographic ridges, and abrupt discontinuities in sub-bottom reflectors, which in places appear to displace seafloor sediments. Several topographic highs that occur within the fault zone appear to be anticlines related to step-overs in these faults. These topographic highs are, in places, topped with circular mounds that are up to 15 m high and have ~30° sloping sides. The crests of the topographic highs and the mounds both have distinctive rough morphologies produced by broken pavements of irregular blocks of methane-derived authigenic carbonates, and by topographic depressions, commonly more than 2 m deep. These areas of distinctive rough topography are commonly associated with living

  1. SAGE 2D and 3D Simulations of the Explosive Venting of Supercritical Fluids Through Porous Media

    NASA Astrophysics Data System (ADS)

    Weaver, R.; Gisler, G.; Svensen, H.; Mazzini, A.

    2008-12-01

    Magmatic intrusive events in large igneous provinces heat sedimentary country rock leading to the eventual release of volatiles. This has been proposed as a contributor to climate change and other environmental impacts. By means of numerical simulations, we examine ways in which these volatiles can be released explosively from depth. Gases and fluids cooked out of country rock by metamorphic heating may be confined for a time by impermeable clays or other barriers, developing high pressures and supercritical fluids. If confinement is suddenly breached (by an earthquake for example) in such a way that the fluid has access to porous sediments, a violent eruption of a non-magmatic mixture of fluid and sediment may result. Surface manifestations of these events could be hydrothermal vent complexes, kimberlite pipes, pockmarks, or mud volcanoes. These are widespread on Earth, especially in large igneous provinces, as in the Karoo Basin of South Africa, the North Sea off the Norwegian margin, and the Siberian Traps. We have performed 2D and 3D simulations with the Sage hydrocode (from Los Alamos and Science Applications International) of supercritical venting in a variety of geometries and configurations. The simulations show several different patterns of propagation and fracturing in porous or otherwise weakened overburden, dependent on depth, source conditions (fluid availability, temperature, and pressure), and manner of confinement breach. Results will be given for a variety of 2D and 3D simulations of these events exploring the release of volatiles into the atmosphere.

  2. Geochemistry of hydrothermal fluids from Axial Seamount Hydrothermal Emissions Study vent field, Juan de Fuca Ridge: Subseafloor boiling and subsequent fluid-rock interaction

    SciTech Connect

    Butterfield, D.A.; McDuff, R.E.; Lilley, M.D. ); Massoth, G.J. ); Lupton, J.E. )

    1990-08-10

    Hydrothermal fluids collected from the ASHES vent field in 1986, 1987, and 1988 exhibit a very wide range of chemical composition over a small area ({approximately} 60 m in diameter). Compositions range from a 300C, gas-enriched (285 mmol/kg CO{sub 2}), low-chlorinity ({approximately} 33% of seawater) fluid to a 328C, relatively gas-depleted (50 mmol/kg CO{sub 2}), high-chlorinity ({approximately} 116% of seawater) fluid. The entire range of measured compositions at ASHES is best explained by a single hydrothermal fluid undergoing phase separation while rising through the ocean crust, followed by partial segregation of the vapor and brine phases. Other mechanisms proposed to produce chlorinity variations in hydrothermal fluids (precipitation/dissolution of a chloride-bearing mineral or crustal hydration) cannot produce the covariation of chlorinity and gas content observed at ASHES. There is good argument of the measured fluid compositions generated by a simple model of phase separation, in which gases are partitioned according to Henry's law and all salt remains in the liquid phase. Significant enrichments in silica, lithium and boron in the low-chlorinity fluids over levels predicted by the model are attributed to fluid-rock interaction in the upflow zone. Depletions in iron and calcium suggest that these elements have been removed by iron-sulfide and anhydrite precipitation at some time in the history of the low-chlorinity fluids. The distribution of low- and high-chlorinity venting is consistent with mechanisms of phase segregation based on differential buoyancy or relative permeability. The relatively shallow depth of the seafloor (1,540 m) and the observed chemistry of ASHES fluids are consistent with phase separation in the sub-critical or near-critical region.

  3. Modelling of hydrothermal fluid circulation in a heterogeneous medium: Application to the Rainbow Vent site (Mid-Atlantic-Ridge, 36°14N)

    NASA Astrophysics Data System (ADS)

    Perez, F.; Mügler, C.; Jean-Baptiste, P.; Charlou, J. L.

    2012-04-01

    Hydrothermal activity at the axis of mid-ocean ridges is a key driver for energy and matter transfer from the interior of the Earth to the ocean floor. At mid-ocean ridges, seawater penetrates through the permeable young crust, warms at depth and exchanges chemicals with the surrounding rocks. This hot fluid focuses and flows upwards, then is expelled from the crust at hydrothermal vent sites in the form of black or white smokers completed by diffusive emissions. We developed a new numerical tool in the Cast3M software framework to model such hydrothermal circulations. Thermodynamic properties of one-phase pure water were calculated from the IAPWS formulation. This new numerical tool was validated on several test cases of convection in closed-top and open-top boxes. Simulations of hydrothermal circulation in a homogeneous-permeability porous medium also gave results in good agreement with already published simulations. We used this new numerical tool to construct a geometric and physical model configuration of the Rainbow Vent site at 36°14'N on the Mid-Atlantic Ridge. In this presentation, several configurations will be discussed, showing that high temperatures and high mass fluxes measured at the Rainbow site cannot be modelled with hydrothermal circulation in a homogeneous-permeability porous medium. We will show that these high values require the presence of a fault or a preferential pathway right below the venting site. We will propose and discuss a 2-D one-path model that allows us to simulate both high temperatures and high mass fluxes. This modelling of the hydrothermal circulation at the Rainbow site constitutes a first but necessary step to understand the origin of high concentrations of hydrogen issued from this ultramafic-hosted vent field.

  4. Carson Lecture: Seafloor Hydrothermal Vents and Their Impact on the Composition of the Ocean Crust, Ocean Chemistry, and Biological Activity in the Deep Sea

    NASA Astrophysics Data System (ADS)

    Tivey, M. K.

    2005-05-01

    February 1977 marked the discovery of seafloor hydrothermal vents along mid-ocean ridges, and a beginning to studies of their impact on ocean chemistry and biological activity in the deep sea. Evidence for these systems was known from heat flow anomalies and from the rock record in the form of volcanic-associated massive sulfide deposits. The discovery provided a first chance to analyze the hydrothermal fluids, infer the consequences of high temperature water-rock reaction within the ocean crust, and observe interactions of vent fluids with seawater at, beneath, and above the seafloor. Ocean chemists compared vent fluid and river inputs to the oceans and estimated contributions from hydrothermal activity to global chemical fluxes. Study of the vent deposits and their unusual biological communities, however, is not straightforward, requiring consideration of the complex interactions during mixing of two compositionally distinct fluids. The mixing processes are in some ways analogous to those occurring within estuaries, though at vent sites fluids differ not just in salinity but in temperature, pH, and redox state. As in estuaries, mixing is complicated by non-conservative processes. These studies have required more sophisticated geochemical modeling efforts that consider reactions at elevated temperatures and pressures, and diffusion and advection in environments characterized by steep chemical and thermal gradients. In situ measurements are still needed to test the accuracy of these calculations, especially in the temperature and pressure region close to the critical point of water that is typical of many vents systems. The presence of novel organisms that thrive off the chemical energy created by mixing processes has added to the drive to develop in situ sensors capable of making measurements in hostile vent environments. As we approach the end of the third decade of study of seafloor hydrothermal systems, we have only just scratched the surface in our quest to

  5. Evidence for Pulsed Hydrothermal Venting from Young Abyssal Hills on the EPR Flank Suggests Frequent Seismic Pumping of Ridge Flank Fluid Flow

    NASA Astrophysics Data System (ADS)

    Haymon, R. M.; MacDonald, K. C.; Benjamin, S. B.; Ehrhardt, C. J.

    2004-12-01

    Although measured heat flow suggests that 40-50% of oceanic hydrothermal heat and fluid flux is from young (0.1-5 Ma) abyssal hill terrain on MOR flanks, hydrothermal vents in this setting rarely have been found. On the EPR flanks, seafloor evidence of venting from abyssal hills has been discovered recently at two sites: on ˜0.1 Ma seafloor at 10° 20'N, 103° 33.2'W ("Tevnia Site") and on ˜0.5 Ma seafloor at 9° 27'N, 104° 32.3'W ("Macrobes Site"). Manifestations of venting at these sites include: fault scarp hydrothermal mineralization and macrofauna; fault scarp flocculations containing hyperthermophilic microbes; and hilltop sediment mounds and craters possibly created by fluid "blow-outs." Hydrothermal deposits recovered at the ˜0.1 Ma "Tevnia Site" are fault breccias that record many episodes of brecciation followed by hydrothermal cementation (Benjamin et al., this session). Tubeworm casings, live crabs, and "dandelions" observed at this site indicate that the most recent episode of venting was active during, or shortly before, this site was visited with Alvin in 1994. To create the 200 m-high axis-facing fault scarp at Tevnia Site in 100,000 years, an average uplift rate of at least 2 cm/y is required. Since off-axis earthquakes located on abyssal hill fault scarps typically are venting at the

  6. Fluid-Rock Interaction in the Basement of the Lost City Vent Field: Insights from Stable and Radiogenic Isotopes

    NASA Astrophysics Data System (ADS)

    Delacour, A.; Frueh-Green, G. L.; Frank, M.; Bernasconi, S. M.; Boschi, C.; Kelley, D. S.

    2004-12-01

    The Lost City Hydrothermal Vent Field (LCVF), with its characteristic carbonate-brucite chimneys, is located on a terrace, at a water depth of 750 to 850m on the southern escarpment of the Atlantis Massif (Mid-Atlantic Ridge 30oN). The Atlantis Massif, an oceanic core complex, consists of peridotites and gabbroic rocks that have undergone several phases of serpentinization, talc-metasomatism and carbonate precipitation related to progressive deformation and interaction with seawater during a long-lived exhumation history. We present stable and radiogenic isotope data from the serpentinized peridotites and gabbros that provide constraints on the history of seawater-rock interaction and the role of serpentinization in methane-production and sulfide mineral precipitation. Early phases of serpentinization and metasomatism occurred at temperatures up to ˜250oC, as indicated by depleted bulk-rock O-isotope compositions of the serpentinites and gabbros. Sr- and Nd-isotope data allow modelling and quantification of seawater-rock interaction. The isotopic compositions of the gabbros show heterogeneity, likely related to variable interaction/exchange with hydrothermal fluids. The serpentinites have Sr- and Nd-isotope compositions close to seawater values and correspond to high water/rock ratios (from 1.53 x 103 to 3.65 x 106), indicating large volumes of seawater circulating through the massif during serpentinization. In contrast, the serpentine-talc schists, resulting from high strain and focused fluid flow of Si-rich fluids during detachment faulting and exhumation, exhibit variable but low fluid/rock ratios (from 10 to 150). Analyses of bulk-rock carbon contents and carbon isotope compositions show total non-carbonate carbon contents of <600 ppm with C-isotope compositions of -29 to -22‰ (VPDB). The negative δ 13C values are likely linked to processes of fluid-rock interaction during serpentinization. C- and O-isotope compositions of carbonate-rich serpentinites and

  7. Boron, bromine, and other trace elements as clues to the fate of chlorine in mid-ocean ridge vent fluids

    SciTech Connect

    Berndt, M.E.; Seyfried, W.E. Jr. )

    1990-08-01

    Fluids from mid-ocean ridge hot springs typically have Cl concentrations which depart significantly from seawater values. These variations may be due in part to phase separation processes and/or precipitation and dissolution of chloride-bearing minerals. Both of these processes likely produce systematic and recognizable variations in the distributions of trace elements which should be evident in vent fluid chemistries. To better understand how supercritical phase separation can affect trace element distributions, we conducted an experiment involving a Na-Ca-K-Cl fluid containing trace quantities of Sr, Ba, B, Li, and Br, which was allowed to separate into vapor and brine phases at 425, 440, and 450{degree}C by systematically adjusting pressure. All of the measured trace elements were concentrated into the brine phase relative to the vapor phase. The relative order of partitioning into the brine was Ba > Sr > Ca > K > Na,Cl > Li > Br > B.

  8. Approximating Fluid Flow from Ambient to Very Low Pressures: Modeling ISS Experiments that Vent to Vacuum

    NASA Technical Reports Server (NTRS)

    Minor, Robert

    2002-01-01

    Two ISS (International Space Station) experiment payloads will vent a volume of gas overboard via either the ISS Vacuum Exhaust System or the Vacuum Resource System. A system of ducts, valves and sensors, under design, will connect the experiments to the ISS systems. The following tasks are required: Create an analysis tool that will verify the rack vacuum system design with respect to design requirements, more specifically approximate pressure at given locations within the vacuum systems; Determine the vent duration required to achieve desired pressure within the experiment modules; Update the analysis as systems and operations definitions mature.

  9. Stable isotope studies of vent fluids and chimney minerals, southern Juan de Fuca Ridge: Sodium metasomatism and seawater sulfate reduction

    NASA Astrophysics Data System (ADS)

    Shanks, Wayne C., III; Seyfried, William E., Jr.

    1987-10-01

    Sulfur isotope values (δ34S) of H2S in vent fluids from the southern Juan de Fuca Ridge hydrothermal sites range from 4.0 to 7.4‰ and are variably 34S-enriched with respect to coexisting inner wall chimney sulfides. Chimney sulfides range from 1.6 to 5.7‰. The chimneys consist of Fe-sphalerite zoned to inner zinc sulfide and chalcopyrite (± isocubanite)-pyrrhotite lining channels. Sulfide from inner walls of type A chimneys have the lightest δ34S values. Type B chimneys (porous, unzoned, low-Fe-sphalerite) have the isotopically heaviest chimney sulfides and occur at vent sites distal to the along-axis shallow point of the ridge crest, hence distal to the magma chamber. These variations are largely ascribed to sulfate reduction by ferrous iron in the hydrothermal fluid in chimneys or substrate mounds, probably due to transitory entrainment of ambient sulfate-bearing seawater. The δ18O values of end-member hydrothermal fluids range from 0.6 to 0.8‰, significantly lower than the δ18O values at 21°N vent fluids. The δD values of the fluid samples range from -2.5 to 0.5‰. Isotopic differences from the 21°N fluids may be due to slightly higher water/rock ratios, approximately 1.0, in the southern Juan de Fuca Ridge hydrothermal system. Admixture of a small amount of residual brine from an earlier phase separation event may have contributed water with low δD values. Sulfate reduction occurs in the deep (2.3 km) hydrothermal reaction zone; a small amount of seawater sulfate passes through the zone of anhydrite precipitation during recharge of the hydrothermal system and is reduced by reaction with pyrrhotite in basalt. Sulfide from pyrrhotite is mixed with 34S-enriched sulfate-derived sulfide to produce pyrite having δ34S values of about 3.0‰ and H2S having values of about 2.1‰ in the ascending fluid. Requisite acidity is provided by Na-metasomatism at about 370°C, yielding albite- and epidote-rich alteration phases.

  10. Development and field application of a 6-bottle serial gas-tight fluid sampler for collecting seafloor cold seep and hydrothermal vent fluids with autonomous operation capability

    NASA Astrophysics Data System (ADS)

    Wu, S.; Ding, K.; Yang, C.; Seyfried, W. E., Jr.; Tan, C.; Schaen, A. T.; Luhmann, A. J.

    2014-12-01

    A 6-bottle serial gas-tight sampler (so-called "six-shooter") was developed for application with deep-sea vent fluids. The new device is composed of a custom-made 6-channel valve manifold and six sampling bottles which are circularly distributed around the valve manifold. Each valve channel consists of a high-pressure titanium cartridge valve and a motor-driven actuator. A sampling snorkel is connected to the inlet of the manifold that delivers the incoming fluid to different bottles. Each sampling bottle has a 160 ml-volume chamber and an accumulator chamber inside where compressed nitrogen is used to maintain the sample at near in-situ pressure. An electronics chamber that is located at the center of the sampler is used to carry out all sampling operations, autonomously, if desired. The sampler is of a compact circular configuration with a diameter of 26 cm and a length of 54 cm. During the SVC cruise AT 26-12, the sampler was deployed by DSV2 Alvin at a cold seep site MC036 with a depth of 1090 m in the Gulf of Mexico. The sampler collected fluid samples automatically following the tidal cycle to monitor the potential impact of the tide cycle on the fluid chemistry of cold seep in a period of two day. During the cruise AT 26-17, the sampler was used with newly upgraded DSV2 Alvin three times at the hydrothermal vent sites along Axial Seamount and Main Endeavor Field on Juan de Fuca Ridge. During a 4-day deployment at Anemone diffuse site (Axial Caldera), the sampler was set to work in an autonomous mode to collect fluid samples according to the preset interval. During other dives, the sampler was manually controlled via ICL (Inductively Coupled Link) communication through the hull. Gas-tight fluid samples were collected from different hydrothermal vents with temperatures between 267 ℃ and 335 ℃ at the depth up to 2200 m. The field results indicate unique advantages of the design. It can be deployed in extended time period with remote operation or working

  11. Sill intrusion driven fluid flow and vent formation in volcanic basins: Modeling rates of volatile release and paleoclimate effects

    NASA Astrophysics Data System (ADS)

    Iyer, Karthik; Schmid, Daniel

    2016-04-01

    Evidence of mass extinction events in conjunction with climate change occur throughout the geological record and may be accompanied by pronounced negative carbon isotope excursions. The processes that trigger such globally destructive changes are still under considerable debate. These include mechanisms such as poisoning from trace metals released during large volcanic eruptions (Vogt, 1972), CO2 released from lava degassing during the formation of Large Igneous Provinces (LIPs) (Courtillot and Renne, 2003) and CH4 release during the destabilization of sub-seafloor methane (Dickens et al., 1995), to name a few. Thermogenic methane derived from contact metamorphism associated with magma emplacement and cooling in sedimentary basins has been recently gaining considerable attention as a potential mechanism that may have triggered global climate events in the past (e.g. Svensen and Jamtveit, 2010). The discovery of hydrothermal vent complexes that are spatially associated with such basins also supports the discharge of greenhouse gases into the atmosphere (e.g. Jamtveit et al., 2004; Planke et al., 2005; Svensen et al., 2006). A previous study that investigated this process using a fluid flow model (Iyer et al., 2013) suggested that although hydrothermal plume formation resulting from sill emplacement may indeed release large quantities of methane at the surface, the rate at which this methane is released into the atmosphere is too slow to trigger, by itself, some of the negative δ13C excursions observed in the fossil record over short time scales observed in the fossil record. Here, we reinvestigate the rates of gas release during sill emplacement in a case study from the Harstad Basin off-shore Norway with a special emphasis on vent formation. The presented study is based on a seismic line that crosses multiple sill structures emplaced around 55 Ma within the Lower Cretaceous sediments. A single well-defined vent complex is interpreted above the termination of the

  12. High-Temperature Hydrothermal Vent Field of Kolumbo Submarine Volcano, Aegean Sea: Site of Active Kuroko-Type Mineralization

    NASA Astrophysics Data System (ADS)

    Sigurdsson, H.; Carey, S.; Alexandri, M.; Vougioukalakis, G.; Croff, K.; Roman, C.; Sakellariou, D.; Anagnostou, C.; Rousakis, G.; Ioakim, C.; Gogou, A.; Ballas, D.; Misaridis, T.; Nomikou, P.

    2006-12-01

    Kolumbo submarine volcano is located 7 km north-east of the island of Santorini in the Hellenic arc (Greece), and comprises one of about twenty submarine cones in a NE-trending rift zone. Kolumbo erupted explosively in 1649-50AD, causing 70 fatalities on Santorini. Kolumbo's crater is 1700 m in diameter, with a crater rim at 10 m below sea level and crater floor at depth of 505 m. Recent marine geological investigations, using ROVs, reveal a very active high-temperature hydrothermal vent field in the northeastern part of the Kolumbo crater floor, about 25,000 m2. Vent chimneys up to 4 m high are vigorously emitting colorless gas plumes up to 10 m high in the water column. Temperatures up to 220oC are recorded in vent fluids. Some vents are in crater- like depressions, containing debris from collapsed extinct chimneys. The entire crater floor of Kolumbo is mantled by a reddish-orange bacterial mat, and bacterial filaments of a variety of colors cling to chimneys in dense clusters. Glassy tunicates and anemones are common in lower-temperature environments on the crater floor. Most chimneys show a high porosity, with a central conduit surrounded by an open and very permeable framework of sulfides and sulfates, aiding fluid flow through the chimney walls. In the sulfate-rich samples, blades of euhedral barite and anhydrite crystals coat the outside of the chimney wall, and layers of barite alternate with sulfide in the interior. The dominant sulfides are pyrite, sphalerite, wurtzite, marcasite and galena. Crusts on extinct and lower-temperature chimneys are composed of amorphous silica, goethite and halite. Sulfur isotope composition of sulfates is virtually at sea water values, whereas the sulfides are more depleted. Elevated levels of copper, gold and silver are observed in bulk composition of chimney samples. Both the structural setting, character of the vent field and sulfide/sulfate mineralogy and geochemistry indicate on-going Kuroko-type mineralization in the

  13. Discovery of Nascent Vents and Recent Colonization Associated with(Re)activated Hydrothermal Vent Fields by the GALREX 2011 Expedition on the Galápagos Rift

    NASA Astrophysics Data System (ADS)

    Shank, T. M.; Holden, J. F.; Herrera, S.; Munro, C.; Muric, T.; Lin, J.; Stuart, L.

    2011-12-01

    GALREX 2011 was a NOAA OER telepresence cruise that explored the diverse habitats and geologic settings of the deep Galápagos region. The expedition made12 Little Hercules ROV dives in July 2011.Abundant corals and a strong depth zonation of species (including deepwater coral communities) were found near 500 m depth on Paramount Seamount, likely influenced by past low sea level states, wave-cut terrace processes, and the historical presence of shallow reef structures. At fresh lava flows with associated (flocculent) hydrothermal venting near 88° W, now known as Uka Pacha and Pegasus Vent Fields, rocks were coated with white microbial mat and lacked sessile fauna, with few mobile fauna (e.g., bythograeid crabs, alvinocarid shrimp, polynoid worms, zoarcid fish, and dirivultid copepods). This suggests a recent creation of hydrothermal habitats through volcanic eruptions and/or diking events, which may have taken place over a 15 km span separating the two vent fields. The Rosebud vent field at 86°W was not observed and may have been covered with lava since last visited in 2005. A hydrothermal vent field near 86°W was discovered that is one of the largest vent fields known on the Rift (120m by 40m). Low-temperature vent habitats were colonized by low numbers of tubeworms including Riftia, Oasisia, and a potential Tevnia species (the latter not previously observed on the Galapagos Rift). Patches of tubeworms were observed with individuals less than 2cm in length, and the relatively few large Riftia had tube lengths near 70cm long. Large numbers of small (< 3cm long) bathymodiolin mussels lined cracks and crevices throughout the active part of the field. Live clams, at least four species of gastropod limpets, three species of polynoid polychaetes, juvenile and adult alvinocarid shrimp, actinostolid anemones, and white microbial communities were observed on the underside and vertical surfaces of basalt rock surfaces. There were at least 13 species of vent-endemic fauna

  14. Ecology of deep-sea hydrothermal vent communities: A review

    SciTech Connect

    Lutz, R.A.; Kennish, M.J. )

    1993-08-01

    The present article reviews studies of the past 15 years of active and inactive hydrothermal vents. The focus of the discussion is on the ecology of the biological communities inhabiting hydrothermal vents. These communities exhibit high densities and biomass, low species diversity, rapid growth rates, and high metabolic rates. The authors attempt to relate the biology of hydrothermal vent systems to geology. Future directions for hydrothermal vent research are suggested. Since many vent populations are dependent on hydrothermal fluids and are consequently unstable, both short- and long-term aspects of the ecology of the vent organisms and the influence of chemical and geological factors on the biology of vent systems need to be established. 200 refs., 28 figs.

  15. Molecular Diversity and Activity of Methanogens in the Subseafloor at Deep-Sea Hydrothermal Vents of the Pacific Ocean (Invited)

    NASA Astrophysics Data System (ADS)

    Huber, J. A.; Merkel, A.; Holden, J. F.; Lilley, M. D.; Butterfield, D. A.

    2009-12-01

    Methanogenesis is thought to represent one of the most ancient metabolic pathways on Earth, and methanogens may serve as important primary producers in warm crustal habitats at deep-sea hydrothermal vents. Many of these obligate chemolithoautotrophs depend solely on geochemically-derived energy and carbon sources and grow at high temperatures under strictly anaerobic conditions. A combined geochemical and microbiological approach was used to determine the distribution and molecular diversity of methanogens in low temperature diffuse vent fluids from the Endeavour Segment R2K ISS site, as well as Axial Seamount and volcanoes of the Mariana Arc. Geochemical data from hot and adjacent warm diffuse vent fluids provided chemical indicators to guide sample selection for detailed polymerase chain reaction (PCR)-based analysis of the key enzyme for methane formation, methyl-coenzyme M reductase (mcrA), as well as archaeal 16S rRNA genes. At most Endeavour vent sites, hydrogen concentrations were too low to support hydrogenotrophic methanogensis directly and only one diffuse site, Easter Island, had a positive signal for the mcrA gene. These sequences were most closely related to members of the order Methanococcales, as well as anaerobic methane oxidizers (ANME-1). The presence of ANME, which are rarely found in non-sedimented marine environments, is another line of evidence supporting the occurrence of buried sediments at Endeavour. At Axial, a number of diffuse vents have strong chemical indicators of methanogenesis. Methanogenic communities were detected at 3 sites on the southeast side of the caldera: the northern end of the 1998 lava flow, the International District, and on the pre-1987 lava flow. Time series work at Marker 113 showed that in 4 different years over the last 6 years methanogenic communities are active and abundant, suggesting a stable anaerobic, warm subseafloor habitat. Results show that members of the order Methanococcales dominate at this site

  16. Quantifying diffuse and discrete venting at the Tour Eiffel vent site, Lucky Strike hydrothermal field

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, Eric; EscartíN, Javier; Gracias, Nuno; Olive, Jean-Arthur; Barreyre, Thibaut; Davaille, Anne; Cannat, Mathilde; Garcia, Rafael

    2012-04-01

    The relative heat carried by diffuse versus discrete venting of hydrothermal fluids at mid-ocean ridges is poorly constrained and likely varies among vent sites. Estimates of the proportion of heat carried by diffuse flow range from 0% to 100% of the total axial heat flux. Here, we present an approach that integrates imagery, video, and temperature measurements to accurately estimate this partitioning at a single vent site, Tour Eiffel in the Lucky Strike hydrothermal field along the Mid-Atlantic Ridge. Fluid temperatures, photographic mosaics of the vent site, and video sequences of fluid flow were acquired during the Bathyluck'09 cruise (Fall, 2009) and the Momarsat'10 cruise (Summer, 2010) to the Lucky Strike hydrothermal field by the ROV Victor6000 aboard the French research vessel the "Pourquoi Pas"? (IFREMER, France). We use two optical methods to calculate the velocities of imaged hydrothermal fluids: (1) for diffuse venting, Diffuse Flow Velocimetry tracks the displacement of refractive index anomalies through time, and (2) for discrete jets, Particle Image Velocimetry tracks eddies by cross-correlation of pixel intensities between subsequent images. To circumvent video blurring associated with rapid velocities at vent orifices, exit velocities at discrete vents are calculated from the best fit of the observed velocity field to a model of a steady state turbulent plume where we vary the model vent radius and fluid exit velocity. Our results yield vertical velocities of diffuse effluent between 0.9 cm s-1 and 11.1 cm s-1 for fluid temperatures between 3°C and 33.5°C above that of ambient seawater, and exit velocities of discrete jets between 22 cm s-1 and 119 cm s-1 for fluid temperatures between 200°C and 301°C above ambient seawater. Using the calculated fluid velocities, temperature measurements, and photo mosaics of the actively venting areas, we calculate a heat flux due to diffuse venting from thin fractures of 3.15 ± 2.22 MW, discrete venting of

  17. In-Situ pH Measurements in Mid-Ocean Ridge Hydrothermal Vent Fluids: Constraints on Subseafloor Alteration Processes at Crustal Depths

    NASA Astrophysics Data System (ADS)

    Schaen, A. T.; Ding, K.; Seyfried, W. E.

    2013-12-01

    Developments in electrochemistry and material science have facilitated the construction of ceramic (YSZ) based chemical sensor systems that can be used to measure and monitor pH and redox in aqueous fluids at elevated temperatures and pressures. In recent years, these sensor systems have been deployed to acquire real-time and time series in-situ data for high-temperature hydrothermal vent fluids at the Main Endeavour Field (Juan de Fuca Ridge), 9oN (East Pacific Rise), and at the ultramafic-hosted Rainbow field (36oN, Mid-Atlantic Ridge). Here we review in-situ pH data measured at these sites and apply these data to estimate the pH of fluids ascending to the seafloor from hydrothermal alteration zones deeper in the crust. In general, in-situ pH measured at virtually all vent sites is well in excess of that measured shipboard owing to the effects of temperature on the distribution of aqueous species and the solubility of metal sulfides, especially Cu and Zn, originally dissolved in the vent fluids. In situ pH measurements determined at MEF (Sully vent) and EPR 9oN (P-vent) in 2005 and 2008 were 4.4 ×0.02 and 5.05×0.05, respectively. The temperature and pressure (seafloor) of the vent fluids at each of the respective sites were 356oC and 220 bar, and 380oC and 250 bar. Plotting these data with respect to fluid density reveals that the in-situ pH of each vent fluid is approximately 1.5 pH units below neutrality. The density-pH (in-situ) correlation, however, is important because it provides a means from which the vent fluids were derived. Using dissolved silica and chloride from fluid samples at the MEF (Sully) suggest T/P conditions of approximately 435oC, 380 bar, based on quartz-fluid and NaCl-H2O systems. At the fluid density calculated for these conditions, pH (in-situ) is predicted to be ~6.2. Attempts are presently underway to assess the effect of the calculated pH on metal sulfide and silicate (e.g., plagioclase, chlorite) solubility in comparison with

  18. Hydrothermal activity on the southern Mid-Atlantic Ridge: Tectonically- and volcanically-controlled venting at 4 5°S

    NASA Astrophysics Data System (ADS)

    German, C. R.; Bennett, S. A.; Connelly, D. P.; Evans, A. J.; Murton, B. J.; Parson, L. M.; Prien, R. D.; Ramirez-Llodra, E.; Jakuba, M.; Shank, T. M.; Yoerger, D. R.; Baker, E. T.; Walker, S. L.; Nakamura, K.

    2008-09-01

    We report results from an investigation of the geologic processes controlling hydrothermal activity along the previously-unstudied southern Mid-Atlantic Ridge (3-7°S). Our study employed the NOC (UK) deep-tow sidescan sonar instrument, TOBI, in concert with the WHOI (USA) autonomous underwater vehicle, ABE, to collect information concerning hydrothermal plume distributions in the water column co-registered with geologic investigations of the underlying seafloor. Two areas of high-temperature hydrothermal venting were identified. The first was situated in a non-transform discontinuity (NTD) between two adjacent second-order ridge-segments near 4°02'S, distant from any neovolcanic activity. This geologic setting is very similar to that of the ultramafic-hosted and tectonically-controlled Rainbow vent-site on the northern Mid-Atlantic Ridge. The second site was located at 4°48'S at the axial-summit centre of a second-order ridge-segment. There, high-temperature venting is hosted in an ˜ 18 km 2 area of young lava flows which in some cases are observed to have flowed over and engulfed pre-existing chemosynthetic vent-fauna. In both appearance and extent, these lava flows are directly reminiscent of those emplaced in Winter 2005-06 at the East Pacific Rise, 9°50'N and reference to global seismic catalogues reveals that a swarm of large (M 4.6-5.6) seismic events was centred on the 5°S segment over a ˜ 24 h period in late June 2002, perhaps indicating the precise timing of this volcanic eruptive episode. Temperature measurements at one of the vents found directly adjacent to the fresh lava flows at 5°S MAR (Turtle Pits) have subsequently revealed vent-fluids that are actively phase separating under conditions very close to the Critical Point for seawater, at ˜ 3000 m depth and 407 °C: the hottest vent-fluids yet reported from anywhere along the global ridge crest.

  19. Reduction of Carbon Dioxide in Filtering Facepiece Respirators with an Active-Venting System: A Computational Study

    PubMed Central

    Birgersson, Erik; Tang, Ee Ho; Lee, Wei Liang Jerome; Sak, Kwok Jiang

    2015-01-01

    During expiration, the carbon dioxide (CO2) levels inside the dead space of a filtering facepiece respirator (FFR) increase significantly above the ambient concentration. To reduce the CO2 concentration inside the dead space, we attach an active lightweight venting system (AVS) comprising a one-way valve, a blower and a battery in a housing to a FFR. The achieved reduction is quantified with a computational-fluid-dynamics model that considers conservation of mass, momentum and the dilute species, CO2, inside the FFR with and without the AVS. The results suggest that the AVS can reduce the CO2 levels inside the dead space at the end of expiration to around 0.4% as compared to a standard FFR, for which the CO2 levels during expiration reach the same concentration as that of the expired alveolar air at around 5%. In particular, during inspiration, the average CO2 volume fraction drops to near-to ambient levels of around 0.08% with the AVS. Overall, the time-averaged CO2 volume fractions inside the dead space for the standard FFR and the one with AVS are around 3% and 0.3% respectively. Further, the ability of the AVS to vent the dead-space air in the form of a jet into the ambient – similar to the jets arising from natural expiration without a FFR – ensures that the expired air is removed and diluted more efficiently than a standard FFR. PMID:26115090

  20. Active colloids at fluid interfaces.

    PubMed

    Malgaretti, P; Popescu, M N; Dietrich, S

    2016-05-01

    If an active Janus particle is trapped at the interface between a liquid and a fluid, its self-propelled motion along the interface is affected by a net torque on the particle due to the viscosity contrast between the two adjacent fluid phases. For a simple model of an active, spherical Janus colloid we analyze the conditions under which translation occurs along the interface and we provide estimates of the corresponding persistence length. We show that under certain conditions the persistence length of such a particle is significantly larger than the corresponding one in the bulk liquid, which is in line with the trends observed in recent experimental studies. PMID:27025167

  1. Temporal trends in vent fluid iron and sulfide chemistry following the 2005/2006 eruption at East Pacific Rise, 9°50'N

    NASA Astrophysics Data System (ADS)

    Yücel, Mustafa; Luther, George W.

    2013-04-01

    The chemistry of vent fluids that emanate to the seafloor undergoes dramatic changes after volcanic eruptions. Data on these changes are still limited, but the best studied example is the East Pacific Rise (EPR) at 9°50'N, where the temporal evolution of the vent fluid chemistry after the 1991/1992 eruption was documented. The area underwent another eruption sequence during late 2005/early 2006, and here we show that a similar evolution is recurring in the iron and sulfide contents of the high-temperature fluids sampled in June 2006, January 2007, and June 2008. The vents have had increasing dissolved iron and decreasing acid-volatile sulfide (free sulfide plus FeS) concentrations with 1 order of magnitude variation. In addition, chromium reducible sulfide (mainly pyrite) also had fivefold decreasing concentrations over the 3 years. Our results confirm a pattern that was noted only once before for 9°50'N EPR and emphasize the dramatic yearly variability in the concentrations of iron-sulfur species emanating from vents.

  2. First Active Hydrothermal Vent Fields Discovered at the Equatorial Southern East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Tao, C.; Lin, J.; Wu, G.; German, C. R.; Yoerger, D. R.; Chen, Y. J.; Guo, S.; Zeng, Z.; Han, X.; Zhou, N.; Li, J.; Xia, S.; Wang, H.; Ding, T.; Gao, S.; Qian, X.; Cui, R.; Zhou, J.; Ye, D.; Zhang8, Y.; Zhang, D.; Li, L.; Zhang, X.; Li, Y.; Wu, X.; Li, S.; He, Y.; Huang, W.; Wang, Y.; Wang, T.; Li, X.; Wang, K.; Gai, Y.; Science Party, D.; Baker, E. T.; Nakamura14, K.

    2008-12-01

    The third leg of the 2008 Chinese DY115-20 expedition on board R/V Dayangyihao has successfully discovered, for the first time, active hydrothermal vent fields on the fast-spreading Southern East Pacific Rise (SEPR) near the equator. This expedition follows the work of a 2005 expedition by R/V Dayangyihao, during which water column turbidity anomalies were measured in the region. The newly discovered vent fields are located along a 22-km-long ridge segment of the SEPR at 102.655°W/2.22°S, 102.646°W/2.152°S, 102.619°W/2.078°S, and 102.62°W/2.02°S, respectively, as well as on an off-axial volcano near 102.456°W/1.369°S. A significant portion of the activity appears to be concentrated along the edges of a seafloor fissure system. Furthermore, water column turbidity anomalies were observed over off-axis volcanoes near 102.827°W/2.084°S and 102.58°W/2.019°S. Video footage of the vent fields and water column turbidity, temperature, and methane anomalies were recorded by a deep-towed integrated system consisting of video, still camera, CTD, and ADCP, and MAPR and METS sensors. Two active hydrothermal fields at 2.217°S and 2.023°S were then extensively photographed and surveyed using the autonomous underwater vehicle ABE of the Woods Hole Oceanographic Institution (WHOI). Four samples of hydrothermal chimneys were successfully obtained by a TV-guided grab in three locations, showing evidence of high-temperature hydrothermal venting.

  3. Use of High Temporal Resolution Thermal Imagery of Karymsky's Volcanic Plume to Constrain Volcanic Activity and Elucidate Vent Processes

    NASA Astrophysics Data System (ADS)

    Lopez, T. M.; Dehn, J.; Belousov, A.; Fee, D.; Buurman, H.; Grapenthin, R.; Ushakov, S.

    2011-12-01

    Analysis of high temporal resolution thermal imagery of the volcanic plume from Karymsky volcano, Kamchatka, Russia, was performed to characterize the activity and elucidate vent processes observed during a field campaign from 21 through 26 July 2008. Observed emission styles ranged from explosive eruptions, gas jetting, gas puffing, passive degassing, to absent degassing. These styles can be broadly categorized according to the thermal data. Specifically, we interpret: (1) apparent temperatures in excess of 120°C to indicate eruption of juvenile material; (2) exponential trends between maximum apparent temperature and radiation above background values to indicate degassing or explosive eruptions; (3) flat and/or flat-exponential hybrid trends between maximum apparent temperature and radiation to indicate absent degassing and/or gas puffing, or a transition between degassing and absent degassing; and (4) strong periodicity identified by inspection or through power spectral density analysis of timeseries data to indicate gas puffing. Based on our thermal observations we propose that these styles of volcanic emissions are primarily controlled by shallow vent processes, with the range of emission styles reflecting a continuum between open and closed vent activity. Specifically, we propose that (1) periods of absent degassing indicate vent sealing; (2) periods of gas puffing indicate cyclic behavior between partial vent sealing and vent fracturing; and (3) passive degassing, gas jetting, and continuous eruption all indicate open vent conditions. We suggest that secondary influences by magma recharge and gas exsolution processes may contribute to variations in degassing style under open vent conditions. These results suggest that trends in thermal timeseries data, such as maximum apparent temperature and radiation, can be used to quantitatively characterize volcanic activity and may help constrain vent processes at active volcanoes.

  4. Modeling fluid flow in sedimentary basins with sill intrusions: Implications for hydrothermal venting and global climate change

    NASA Astrophysics Data System (ADS)

    Iyer, K. H.; Rupke, L.

    2013-12-01

    In recent years, the emplacement of Large Igneous Provinces (LIPs) has been closely linked with past climate variations and mass extinctions. The hypothesis is that organic matter present within contact aureole of the surrounding sedimentary rock such as shale undergoes thermal maturation and releases greenhouse gases such as methane and carbon dioxide due to the emplacement of hot igneous bodies. These gases are then vented into the atmosphere through hydrothermal pipe structures resulting in climate change. Although, basin-scale estimates of potential methane generation show that these processes alone could trigger global incidents, the rates at which these gases are released into the atmosphere and the transport mechanism are quantitatively unknown. We use a 2D, hybrid FEM/FVM model that solves for fully compressible fluid flow to quantify the thermogenic release of methane and to evaluate flow patterns within these systems. In addition, methane transport within the system is tracked enabling us to constrain the rate of release of methane from the basin surface. The important outcomes of this study are: (1) the location of hydrothermal vents is directly controlled by the flow pattern, even in systems with no vigorous convection, without the explicit need for explosive degassing and/or boiling effects. The merging of fluid flow from the bottom and top edges of the sill result in hydrothermal plumes positioned at the lateral edges of the sill and is consistent with geological observations. (2) Methane generation potential in systems with fluid flow does not significantly differ from that estimated in diffusive systems, e.g. 2200 to 3350 Gt CH4 can be potentially generated within the Vøring and Møre basins with a sediment TOC content of 5 wt% and varying permeability structure. On the other hand, methane venting at the surface occurs in three distinct stages and can last for hundreds of thousands of years. Also, not all of the methane reaches the surface as some

  5. Isolation and Stability of Distinct Subsurface Microbial Communities Associated with Two Hydrothermal Vent Systems

    NASA Astrophysics Data System (ADS)

    Opatkiewicz, A. D.; Butterfield, D. A.; Baross, J. A.

    2008-12-01

    Subseafloor microbial communities may be important in global primary production and biogeochemical cycling. However, too little is known about the physiological and phylogenetic diversity and activity of these communities to assess this potential, and understanding the temporal and spatial variability in microbial community structure is critical. The microbial community structure of five geographically distinct hydrothermal vents located within the Axial Seamount caldera, and four geographically distinct vents within the Main Endeavour Field, Juan de Fuca Ridge, were examined over six years. Terminal restriction fragment length polymorphism (tRFLP) and 16S rRNA gene sequence analyses were used to determine the bacterial and archaeal diversity, and the statistical software Primer was used to compare vent microbiology, temperature and fluid chemistry. Statistical analysis of vent fluid temperature and chemical composition shows that there are significant differences between vents in any year, and persistent differences in composition between one of the Axial vents compared to the rest of the vents. For the majority of vents, however, the fluid composition changed over time such that separate vents do not maintain a statistically distinct composition. In contrast, the subseafloor microbial communities associated with individual vents also changed from year to year but each location maintained a distinct community structure (based on tRFLP and 16S rRNA gene sequence analyses) that was significantly different and greater than 60-percent dissimilar from all other vents included in this study. At Axial, epsilon-proteobacterial microdiversity is shown to be important in distinguishing vent communities. The deeper, high-temperature archaeal communities have more overlap between sites. We propose that persistent venting at many diffuse sites over time creates the potential to isolate and stabilize diverse microbial community structures between vents. Variation in dilution

  6. The Lost City hydrothermal system: Constraints imposed by vent fluid chemistry and reaction path models on subseafloor heat and mass transfer processes

    NASA Astrophysics Data System (ADS)

    Seyfried, W. E.; Pester, Nicholas J.; Tutolo, Benjamin M.; Ding, Kang

    2015-08-01

    Since the first reported discovery of the Lost City hydrothermal system in 2001, it was recognized that seawater alteration of ultramafic rocks plays a key role in the composition of the coexisting vent fluids. The unusually high pH and high concentrations of H2 and CH4 provide compelling evidence for this. Here we report the chemistry of hydrothermal fluids sampled from two vent structures (Beehive: ∼90-116 °C, and M6: ∼75 °C) at Lost City in 2008 during cruise KNOX18RR using ROV Jason 2 and R/V Revelle assets. The vent fluid chemistry at both sites reveals considerable overlap in concentrations of dissolved gases (H2, CH4), trace elements (Cs, Rb, Li, B and Sr), and major elements (SO4, Ca, K, Na, Cl), including a surprising decrease in dissolved Cl, suggesting a common source fluid is feeding both sites. The absence of Mg and relatively high concentrations of Ca and sulfate suggest solubility control by serpentine-diopside-anhydrite, while trace alkali concentrations, especially Rb and Cs, are high, assuming a depleted mantle protolith. In both cases, but especially for Beehive vent fluid, the silica concentrations are well in excess of those expected for peridotite alteration and the coexistence of serpentine-brucite at all reasonable temperatures. However, both the measured pH and silica values are in better agreement with serpentine-diopside-tremolite-equilibria. Geochemical modeling demonstrates that reaction of plagioclase with serpentinized peridotite can shift the chemical system away from brucite and into the tremolite stability field. This is consistent with the complex intermingling of peridotite and gabbroic bodies commonly observed within the Atlantis Massif. We speculate the existence of such plagioclase bearing peridotite may also account for the highly enriched trace alkali (Cs, Rb) concentrations in the Lost City vent fluids. Additionally, reactive transport modeling taking explicit account of temperature dependent rates of mineral

  7. Cinnabar, arsenian pyrite and thallium-enrichment in active shallow submarine hydrothermal vents at Paleochori Bay, Milos Island, Greece

    NASA Astrophysics Data System (ADS)

    Kati, Marianna; Voudouris, Panagiotis; Valsami-Jones, Eugenia; Magganas, Andreas; Baltatzis, Emmanouil; Kanellopoulos, Christos; Mavrogonatos, Constantinos

    2015-04-01

    We herein report the discovery of active cinnabar-depositing hydrothermal vents in a submarine setting at Paleochori Bay, within the offshore southeastern extension of the Milos Island Geothermal Field, South Aegean Active Volcanic Arc. Active, low temperature (up to 115 °C) hydrothermal venting through volcaniclastic material has led to a varied assemblage of sulfide and alteration mineral phases in an area of approximately 1 km2. Our samples recovered from Paleochori Bay are hydrothermal edifices composed of volcaniclastic detrital material cemented by pyrite, or pure sulfide (mainly massive pyrite) mounts. Besides pyrite and minor marcasite, the hydrothermal minerals include cinnabar, amorphous silica, hydrous ferric oxides, carbonates (aragonite and calcite), alunite-jarosite solid solution and Sr-rich barite. Among others, growth textures, sieve-textured pyrite associated with barite, alunite-jarosite solid solution and hydrous ferric oxides rims colloform-banded pyrite layers. Overgrowths of arsenian pyrite layers (up to 3.2 wt. % As and/or up to 1.1 wt. % Mn) onto As-free pyrite indicate fluctuation in As content of the hydrothermal fluid. Mercury, in the form of cinnabar, occurs in up to 5 μm grains within arsenian pyrite layers, usually forming distinct cinnabar-enriched micro-layers. Hydrothermal Sr-rich barite (barite-celestine solid solution), pseudocubic alunite-jarosite solid solution and Mn- and Sr-enriched carbonates occur in various amounts and closely associated with pyrite and/or hydrous ferric oxides. Thallium-bearing sulfides and/or sulfosalts were not detected during our study; however, hydrous ferric oxides show thallium content of up to 0.5 wt. % Tl. The following scenarios may have played a role in pyrite precipitation at Paleochori: (a) H2S originally dissolved in the deep fluid but separated upon boiling could have reacted with oxygenated seawater under production of sulphuric acid, thus causing leaching and dissolution of primary iron

  8. Fluid venting and seepage at accretionary ridges: the Four Way Closure Ridge offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Klaucke, Ingo; Berndt, Christian; Crutchley, Gareth; Chi, Wu-Cheng; Lin, Saulwood; Muff, Sina

    2015-12-01

    Within the accretionary prism offshore SW Taiwan, widespread gas hydrate accumulations are postulated to occur based on the presence of a bottom simulating reflection. Methane seepage, however, is also widespread at accretionary ridges offshore SW Taiwan and may indicate a significant loss of methane bypassing the gas hydrate system. Four Way Closure Ridge, located in 1,500 m water depth, is an anticlinal ridge that would constitute an ideal trap for methane and consequently represents a site with good potential for gas hydrate accumulations. The analysis of high-resolution bathymetry, deep-towed sidescan sonar imagery, high-resolution seismic profiling and towed video observations of the seafloor shows that Four Way Closure Ridge is and has been a site of intensive methane seepage. Continuous seepage is mainly evidenced by large accumulations of authigenic carbonate precipitates, which appear to be controlled by the creation of fluid pathways through faulting. Consequently, Four Way Closure Ridge is not a closed system in terms of fluid migration and seepage. A conceptual model of the evolution of gas hydrates and seepage at accretionary ridges suggests that seepage is common and may be a standard feature during the geological development of ridges in accretionary prisms. The observation of seafloor seepage alone is therefore not a reliable indicator of exploitable gas hydrate accumulations at depth.

  9. Fluid venting and seepage at accretionary ridges: the Four Way Closure Ridge offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Klaucke, Ingo; Berndt, Christian; Crutchley, Gareth; Chi, Wu-Cheng; Lin, Saulwood; Muff, Sina

    2016-06-01

    Within the accretionary prism offshore SW Taiwan, widespread gas hydrate accumulations are postulated to occur based on the presence of a bottom simulating reflection. Methane seepage, however, is also widespread at accretionary ridges offshore SW Taiwan and may indicate a significant loss of methane bypassing the gas hydrate system. Four Way Closure Ridge, located in 1,500 m water depth, is an anticlinal ridge that would constitute an ideal trap for methane and consequently represents a site with good potential for gas hydrate accumulations. The analysis of high-resolution bathymetry, deep-towed sidescan sonar imagery, high-resolution seismic profiling and towed video observations of the seafloor shows that Four Way Closure Ridge is and has been a site of intensive methane seepage. Continuous seepage is mainly evidenced by large accumulations of authigenic carbonate precipitates, which appear to be controlled by the creation of fluid pathways through faulting. Consequently, Four Way Closure Ridge is not a closed system in terms of fluid migration and seepage. A conceptual model of the evolution of gas hydrates and seepage at accretionary ridges suggests that seepage is common and may be a standard feature during the geological development of ridges in accretionary prisms. The observation of seafloor seepage alone is therefore not a reliable indicator of exploitable gas hydrate accumulations at depth.

  10. Antimicrobial Activity of Marine Bacterial Symbionts Retrieved from Shallow Water Hydrothermal Vents.

    PubMed

    Eythorsdottir, Arnheidur; Omarsdottir, Sesselja; Einarsson, Hjorleifur

    2016-06-01

    Marine sponges and other sessile macro-organisms were collected at a shallow water hydrothermal site in Eyjafjörður, Iceland. Bacteria were isolated from the organisms using selective media for actinomycetes, and the isolates were screened for antimicrobial activity. A total of 111 isolates revealed antimicrobial activity displaying different antimicrobial patterns which indicates production of various compounds. Known test strains were grown in the presence of ethyl acetate extracts from one selected isolate, and a clear growth inhibition of Staphylococcus aureus was observed down to 0.1 % extract concentration in the medium. Identification of isolates shows different species of Actinobacteria with Streptomyces sp. playing the largest role, but also members of Bacilli, Alphaproteobacteria and Gammaproteobacteria. Sponges have an excellent record regarding production of bioactive compounds, often involving microbial symbionts. At the hydrothermal vents, however, the majority of active isolates originated from other invertebrates such as sea anemones or algae. The results indicate that antimicrobial assays involving isolates in full growth can detect activity not visible by other methods. The macro-organisms inhabiting the Eyjafjörður hydrothermal vent area host diverse microbial species in the phylum Actinobacteria with antimicrobial activity, and the compounds responsible for the activity will be subject to further research. PMID:27147438

  11. Coupled RNA-SIP and metatranscriptomics of active chemolithoautotrophic communities at a deep-sea hydrothermal vent.

    PubMed

    Fortunato, Caroline S; Huber, Julie A

    2016-08-01

    The chemolithoautotrophic microbial community of the rocky subseafloor potentially provides a large amount of organic carbon to the deep ocean, yet our understanding of the activity and metabolic complexity of subseafloor organisms remains poorly described. A combination of metagenomic, metatranscriptomic, and RNA stable isotope probing (RNA-SIP) analyses were used to identify the metabolic potential, expression patterns, and active autotrophic bacteria and archaea and their pathways present in low-temperature hydrothermal fluids from Axial Seamount, an active submarine volcano. Metagenomic and metatranscriptomic results showed the presence of genes and transcripts for sulfur, hydrogen, and ammonium oxidation, oxygen respiration, denitrification, and methanogenesis, as well as multiple carbon fixation pathways. In RNA-SIP experiments across a range of temperatures under reducing conditions, the enriched (13)C fractions showed differences in taxonomic and functional diversity. At 30 °C and 55 °C, Epsilonproteobacteria were dominant, oxidizing hydrogen and primarily reducing nitrate. Methanogenic archaea were also present at 55 °C, and were the only autotrophs present at 80 °C. Correspondingly, the predominant CO2 fixation pathways changed from the reductive tricarboxylic acid (rTCA) cycle to the reductive acetyl-CoA pathway with increasing temperature. By coupling RNA-SIP with meta-omics, this study demonstrates the presence and activity of distinct chemolithoautotrophic communities across a thermal gradient of a deep-sea hydrothermal vent. PMID:26872039

  12. The vent microbiome: patterns and drivers

    NASA Astrophysics Data System (ADS)

    Pachiadaki, M.

    2015-12-01

    Microbial processes within deep-sea hydrothermal vents affect the global biogeochemical cycles. Still, there are significant gaps in our understanding of the microbiology and the biogeochemistry of deep-sea hydrothermal systems. Vents differ in temperature, host rock composition and fluid chemistry; factors that are hypothesized to shape the distribution of the microbial communities, their metabolic capabilities and their activities. Using large-scale single cell genomics, we obtained insights into the genomic content of several linkages of a diffuse flow vent. The genomes show high metabolic versatility. Sulfur oxidation appears to be predominant but there is the potential of using a variety of e- donors and acceptors to obtain energy. To further assess the ecological importance of the vent auto- and heterotrophs, the global biogeography of the analyzed lineages will be investigated by fragment recruitment of metagenomes produced from the same site as well as other hydrothermal systems. Metatranscriptomic and metaproteomic data will be integrated to examine the expression of the predominant metabolic pathways and thus the main energy sources driving chemoautotrophic production. The comparative analysis of the key players and associated pathways among various vent sites that differ in physicochemical characteristics is anticipated to decipher the patterns and drivers of the global dispersion and the local diversification of the vent microbiome.

  13. Active seafloor gas vents on the Shelf and upper Slope in Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; Dallimore, S. R.; Hughes Clarke, J. E.; Blasco, S.; Taylor, A. E.; Melling, H.; Vagle, S.; Conway, K.; Riedel, M.; Lundsten, E.; Gwiazda, R.

    2012-12-01

    seafloor topographic features on the continental slope suggests these are also active vent sites. Vigorous degassing of methane and pore water freshening in cores from features suggest the presence of near seafloor gas hydrate accumulations. If correct, a feature at 290m depth hosts the shallowest known marine gas hydrate occurrence. Here a layer of very cold ocean waters (-1.7°C) extends to ~200m depths, below which the temperature increases slowly with depth. A consequence of the exceptionally low upper water column temperatures is that the top of the methane hydrate stability zone is only slightly shallower that the 290m seafloor feature. Thus, gas hydrate harbored within seafloor sediments at 290m is vulnerable to decomposition with even subtle climatically-induced warming of the overlying water. Further geoscience studies are planned for 2012 and 2013 to study geological processes, geohazards and the sensitivity of the shelf / slope setting to climate change in the Arctic.

  14. Chemical controls on the composition of vent fluids at 13°-11°N and 21°N, East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Bowers, Teresa Suter; Campbell, Andrew C.; Measures, Chris I.; Spivack, Arthur J.; Khadem, Mitra; Edmond, John M.

    1988-05-01

    Six vent fields sampled at 13°-11°N, East Pacific Rise (EPR) in May 1984 exhibit large interfield variations and a much wider range of chemical compositions than previously observed at 21°N. Measured pH at 25°C are acidic, ranging from 3.1 to 3.7. Sodium and chloride vary from 40% lower to 30% higher than seawater. Iron concentrations range from 2 to 10 mmol/kg, compared with 0.7-2.5 mmol/kg at 21°N. Other sulfide-forming metals (Cu, Zn, Cd, and Pb) are generally lower at 11°-13°N than at 21°N. Reliable temperature measurements were obtained at only two of the six vents and both were 350° ± 5°C. The vent fields at 21°N, EPR were resampled in August 1985, thus extending to almost 6 years the time period over which they have been monitored (previous expeditions were made in November 1979 and November 1981). Campbell et al. (this issue) have shown that the chemistry of the hydrothermal fluids from these fields has been very stable over the period of repeated observation. Equilibrium calculations for the fluids from the fields at 13°N and 21°N, using a greatly improved thermodynamic data base, are described in this report. They indicate that the chemistry is rock buffered and that the stability of these systems over time is a result of equilibrium control with respect to a greenschist-type mineral assemblage at depth. Calculated high-temperature pH of the fluids range from 4.1 to 4.7 with those from 13°-11°N at the more acidic end of the range. Calculated affinities show that the fluids are close to, or at, saturation with respect to quartz, albite, muscovite, smectite/chlorite, epidote, and pyrrhotite. The computations imply that lower-temperature vents such as National Geographic Smoker (NGS) (273°C) may have their silica concentrations controlled by equilibrium with respect to a phase other than quartz. A comparison of fluid chemistry between NGS and vent 5 at 11°N suggests that the latter vent may also have a temperature < 300°C. While the fluid

  15. Investigating Late Amazonian Volcanotectonic Activity on Olympus Mons, Mars using Flank Vents and Arcuate Graben

    NASA Astrophysics Data System (ADS)

    Peters, S.; Christensen, P. R.

    2015-12-01

    Volcanism, a fundamental process in shaping the Martian surface, is crucial to understanding its evolution. Olympus Mons, the largest volcano on Mars, is one of several large shield volcanoes. Previous studies were technologically limited to large features associated with these constructs. With the advent of high resolution datasets, we are now able to investigate smaller features, such as flank vents and arcuate graben. Flank vents, common on polygenetic volcanoes, indicate that magma has propagated away from the main conduit and/or magma chamber. Vent morphology allows for the characterization of magma properties and eruption rates. Graben indicate extensional deformation. The distribution of graben provides information on stresses that acted on the volcano. In lieu of geophysical, spectral and in-situ data, morphology, morphometry and spatial relationships are powerful tools. We utilized high resolution image data (CTX, HiRISE and THEMIS IR) and topographic data (HRSC DTM, MOLA) to identify and characterize flank vents and graben. We observed 60 flank vents and 84 arcuate graben on Olympus Mons. Flank vents display varying morphologies and morphometries, suggesting different eruption styles and variable magma volatility. Vents occur primarily on the lower flank. This suggests magma has propagated substantial distances from the magma chamber. Observed clustering of vents may also indicate shallow magma sources. Similarly, graben are observed on the lower flank crosscutting young lava flows that have mantled portions of the escarpment. This indicates either gravitational spreading of Olympus Mons or flexure of the lithosphere in response to the load of the edifice. Collectively, the distribution of flank vents and arcuate graben suggests a similar development to that proposed for Ascraeus Mons. Based on superposition relationships and dates from previous studies, the flank vents and graben formed in the Late Amazonian (≤500 Ma).

  16. Active Venting Sites On The Gas-Hydrate-Bearing Hikurangi Margin, Off New Zealand: ROV Measurements And Observations

    NASA Astrophysics Data System (ADS)

    Naudts, L.; Poort, J.; Boone, D.; Linke, P.; Greinert, J.; de Batist, M.; Henriet, J.

    2007-12-01

    During R.V. Sonne cruise SO191-3, part of the "New (Zealand Cold) Vents" expedition, RCMG deployed a CHEROKEE ROV "Genesis" on the Hikurangi Margin. This accretionary margin, on the east coast of New Zealand, is related to the subduction of the Pacific Plate under the Australian Plate. Several cold vent locations as well as an extensive BSR, indicating the presence of gas hydrates, have been found at this margin. The aims of the ROV-work were to precisely localize active methane vents, to conduct detailed visual observations of the vent structures and activity, and to perform measurements of physical properties and collect samples at and around the vent locations. The three investigated areas generally have a flat to moderate undulating sea floor with soft sediments alternating with carbonate platforms. The different sites were sometimes covered with dense fields of live clams or shell debris, often in association with tube worms, sponges and/or soft tissue corals. Active bubble- releasing seeps were observed at Faure's site and LM-3 site. Bubble-releasing activity was very variable in time, with periods of almost non-activity alternating with periods of violent outbursts. Bubble release occurred mainly from prominent depressions in soft-sediment sea floor. Bottom-water sampling revealed sometimes high concentrations of methane. Sediment-temperature measurements were largely comparable with the bottom- water temperature except for a "raindrop site" (with dense populations of polychaetes), where anomalous low sediment-temperature was measured. Further analysis of the ROV data together with the integration of other datasets will enable us to produce a model characterizing seep structure and environment.

  17. Tapped-Hole Vent Path

    NASA Technical Reports Server (NTRS)

    Chandler, J. A.

    1983-01-01

    Long helical vent path cools and releases hot pyrotechnical gas that exits along its spiraling threads. Current design uses 1/4-28 threads with outer diameter of stud reduced by 0.025 in. (0.62 mm). To open or close gassampler bottle, pyrotechnic charges on either one side or other of valve cylinder are actuated. Gases vented slowly over long path are cool enough to present no ignition hazard. Vent used to meter flow in refrigeration, pneumaticcontrol, and fluid-control systems by appropriately adjusting size and length of vent path.

  18. Immersed Boundary Simulations of Active Fluid Droplets.

    PubMed

    Whitfield, Carl A; Hawkins, Rhoda J

    2016-01-01

    We present numerical simulations of active fluid droplets immersed in an external fluid in 2-dimensions using an Immersed Boundary method to simulate the fluid droplet interface as a Lagrangian mesh. We present results from two example systems, firstly an active isotropic fluid boundary consisting of particles that can bind and unbind from the interface and generate surface tension gradients through active contractility. Secondly, a droplet filled with an active polar fluid with homeotropic anchoring at the droplet interface. These two systems demonstrate spontaneous symmetry breaking and steady state dynamics resembling cell motility and division and show complex feedback mechanisms with minimal degrees of freedom. The simulations outlined here will be useful for quantifying the wide range of dynamics observable in these active systems and modelling the effects of confinement in a consistent and adaptable way. PMID:27606609

  19. Post-Arterial Filter Gaseous Microemboli Activity of Five Integral Cardiotomy Reservoirs during Venting: An In Vitro Study

    PubMed Central

    Myers, Gerard J.; Voorhees, Cheri; Haynes, Rob; Eke, Bob

    2009-01-01

    Abstract: During a previously published study on gaseous micro-emboli (GMEs) and perfusionist interventions, it was noted that emboli could be detected after the arterial filter when blood/air challenges entered the membrane oxygenator’s integral cardiotomy. The findings indicated that further study into the oxygenator’s integral cardiotomy reservoir was warranted. This is the first know published report that connects the vent return to GME activity after the arterial filter. To study the air handling ability of the membranes integral cardiotomy, an in vitro study was conducted on five hard shell coated membrane oxygenators (Terumo Capiox SX25, X coated; Sorin Synthesis, phosphorylcholine coated; Gish Vision, GBS coated; Medtronic Affinity NT, trillium coated; Maquet Quadrox, bioline coated). The oxygenators were matched with their own manufacturer’s coated arterial filters (Medtronic 351T Arterial Filter, Sorin Synthesis Integrated Arterial Filter, Terumo CXAF200X Arterial Filter, Gish GAF40GBS-2 Arterial Filter, and Maquet Quart HBF140 Arterial Filter). There were three arms to the study, and three separate oxygenator/filter combinations were used in each arm. The first arm consisted of a pump flow of 4.0 L/min with only the filter purge blood entering the integral cardiotomy. In the second arm, 500 mL/min of simulated vent blood was added to the filter purge blood entering the integral cardiotomy. During the final arm, 200 mL/min of air was added to the vent blood as it entered the integral cardiotomy, to more closely simulate vent return during cardiopulmonary bypass. All GME activity in the oxygenator/filter combinations was examined using the Hatteland CMD20 Microemboli Counter. Placement of the Hatteland probes was 4 in after the hard shell reservoir outlet (PRO) and 12 in after the arterial filter (PAF). When vent blood flow was turned on, there was a significant increase in the PRO microemboli activity detected in all reservoirs. In the PAF position

  20. Fluid transport by active elastic membranes

    NASA Astrophysics Data System (ADS)

    Evans, Arthur A.; Lauga, Eric

    2011-09-01

    A flexible membrane deforming its shape in time can self-propel in a viscous fluid. Alternatively, if the membrane is anchored, its deformation will lead to fluid transport. Past work in this area focused on situations where the deformation kinematics of the membrane were prescribed. Here we consider models where the deformation of the membrane is not prescribed, but instead the membrane is internally forced. Both the time-varying membrane shape and the resulting fluid motion result then from a balance between prescribed internal active stresses, internal passive resistance, and external viscous stresses. We introduce two specific models for such active internal forcing: one where a distribution of active bending moments is prescribed, and one where active inclusions exert normal stresses on the membrane by pumping fluid through it. In each case, we asymptotically calculate the membrane shape and the fluid transport velocities for small forcing amplitudes, and recover our results using scaling analysis.

  1. Activity and abundance of denitrifying bacteria in the subsurface biosphere of diffuse hydrothermal vents of the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Bourbonnais, A.; Juniper, S. K.; Butterfield, D. A.; Devol, A. H.; Kuypers, M. M. M.; Lavik, G.; Hallam, S. J.; Wenk, C. B.; Chang, B. X.; Murdock, S. A.; Lehmann, M. F.

    2012-11-01

    Little is known about fixed nitrogen (N) transformation and elimination at diffuse hydrothermal vents where anoxic fluids are mixed with oxygenated crustal seawater prior to discharge. Oceanic N sinks that remove bio-available N ultimately affect chemosynthetic primary productivity in these ecosystems. Using 15N paired isotope techniques, we determined potential rates of fixed N loss pathways (denitrification, anammox) and dissimilatory nitrate reduction to ammonium (DNRA) in sulfidic hydrothermal vent fluids discharging from the subsurface at several sites at Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge. We also measured physico-chemical parameters (i.e., temperature, pH, nutrients, H2S and N2O concentrations) as well as the biodiversity and abundance of chemolithoautotrophic nitrate-reducing, sulfur-oxidizing γ-proteobacteria (SUP05 cluster) using sequence analysis of amplified small subunit ribosomal RNA (16S rRNA) genes in combination with taxon-specific quantitative polymerase chain reaction (qPCR) assays. Denitrification was the dominant N loss pathway in the subsurface biosphere of the Juan de Fuca Ridge, with rates of up to ~1000 nmol N l-1 day-1. In comparison, anammox rates were always < 5 nmol N l-1 day-1 and below the detection limit at most of the sites. DNRA rates were up to ~150 nmol N l-1 day-1. These results suggest that bacterial denitrification out-competes anammox in sulfidic hydrothermal vent waters. Taxon-specific qPCR revealed that γ-proteobacteria of the SUP05 cluster sometimes dominated the microbial community (SUP05/total bacteria up to 38%). Significant correlations were found between fixed N loss (i.e., denitrification, anammox) rates and in situ nitrate and dissolved inorganic nitrogen (DIN) deficits in the fluids, indicating that DIN availability may ultimately regulate N loss in the subsurface. Based on our rate measurements, and on published data on hydrothermal fluid fluxes and residence times, we estimated

  2. Activity and abundance of denitrifying bacteria in the subsurface biosphere of diffuse hydrothermal vents of the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Bourbonnais, A.; Juniper, S. K.; Butterfield, D. A.; Devol, A. H.; Kuypers, M. M. M.; Lavik, G.; Hallam, S. J.; Wenk, C. B.; Chang, B. X.; Murdock, S. A.; Lehmann, M. F.

    2012-04-01

    Little is known about nitrogen (N) transformations in general, and the elimination of N in particular, at diffuse vents where anoxic hydrothermal fluids have mixed with oxygenated crustal seawater prior to discharge. Oceanic N sinks that remove bio-available N ultimately affect chemosynthetic primary productivity in these ecosystems. Using 15N paired isotope techniques, we determined potential rates of fixed N-loss pathways (denitrification, anammox) and dissimilative nitrate reduction to ammonium (DNRA) in sulfidic hydrothermal vent fluids discharging from the subsurface at several sites at Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge. We also measured physico-chemical parameters (i.e. temperature, pH, nutrients, H2S and N2O concentrations) as well as the biodiversity and abundance of chemolithotrophic nitrate-reducing, sulfur-oxidizing γ-proteobacteria (SUP05 cluster) using sequence analysis of amplified small subunit ribosomal RNA (16S rRNA) genes in combination with taxon-specific quantitative polymerase chain reaction (qPCR) assays. Denitrification was the dominant N-loss pathway in the subsurface biosphere of the Juan de Fuca Ridge, with rates of up to ~1000 nmol N l-1 day-1. In comparison, anammox rates were always <5 nmol N l-1 day-1 and below the detection limit at most of the sites. DNRA rates were up to 152 nmol N l-1 day-1. These results suggest that bacterial denitrification out-competes anammox in sulfidic hydrothermal vent waters. Taxon-specific qPCR revealed that γ-proteobacteria of the SUP05 cluster sometimes dominated the microbial community (SUP05/total bacteria up to 38%). Significant correlation existed between fixed N-loss (i.e., denitrification, anammox) rates and in-situ nitrate and dissolved inorganic nitrogen (DIN) deficits in the fluids, indicating that DIN availability may ultimately regulate N-loss in the subsurface. Based on our rate measurements, and on published data on hydrothermal fluid fluxes and residence

  3. New boron isotopic evidence for sedimentary and magmatic fluid influence in the shallow hydrothermal vent system of Milos Island (Aegean Sea, Greece)

    NASA Astrophysics Data System (ADS)

    Wu, Shein-Fu; You, Chen-Feng; Lin, Yen-Po; Valsami-Jones, Eugenia; Baltatzis, Emmanuel

    2016-01-01

    Magmatic sources may contribute a significant amount of volatiles in geothermal springs; however, their role is poorly understood in submarine hydrothermal systems worldwide. In this study, new results of B and δ11B in 41 hydrothermal vent waters collected from the shallow hydrothermal system of Milos island in the Aegean Sea were combined with previously published data from other tectonic settings and laboratory experiments to quantify the effects of phase separation, fluid/sediment interaction and magmatic contribution. Two Cl-extreme solutions were identified, high-Cl waters (Cl as high as 2000 mM) and low-Cl waters (Cl < 80 mM). Both sets of waters were characterized by high B/Cl (~ 1.2-5.3 × 10- 3 mol/mol) and extremely low δ11B (1.4-6.3‰), except for the waters with Mg content of near the seawater value and δ11B = 10.3-17.4‰. These high-Cl waters with high B/Cl and low δ11B plot close to the vent waters in sediment-hosted hydrothermal system (i.e., Okinawa Trough) or fumarole condensates from on-land volcanoes, implying B addition from sediment or magmatic fluids plays an important role. This is in agreement with fluid/sediment interactions resulting in the observed B and δ11B, as well as previously reported Br/I/Cl ratios, supporting a scenario of slab-derived fluid addition with elevated B, 11B-rich, and low Br/Cl and I/Cl, which is derived from the dehydration of subducted-sediments. The slab fluid becomes subsequently mixed with the parent magma of Milos. The deep brine reservoir is partially affected by injections of magmatic fluid/gases during degassing. The results presented here are crucial for deciphering the evolution of the brine reservoirs involved in phase separation, fluid/sediment interaction and magmatic contribution in the deep reaction zone of the Milos hydrothermal system; they also have implications in the understanding of the formation of metallic vein mineralization.

  4. A reduced crustal magnetization zone near the first observed active hydrothermal vent field on the Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Lin, Jian; Chen, Yongshun J.; Tao, Chunhui; German, Christopher R.; Yoerger, Dana R.; Tivey, Maurice A.

    2010-09-01

    Inversion of near-bottom magnetic data reveals a well-defined low crustal magnetization zone (LMZ) near a local topographic high (37°47‧S, 49°39‧E) on the ultraslow-spreading Southwest Indian Ridge (SWIR). The magnetic data were collected by the autonomous underwater vehicle ABE on board R/V DaYangYiHao in February-March 2007. The first active hydrothermal vent field observed on the SWIR is located in Area A within and adjacent to the LMZ at the local topographic high, implying that this LMZ may be the result of hydrothermal alteration of magnetic minerals. The maximum reduction in crustal magnetization is 3 A/M. The spatial extent of the LMZ is estimated to be at least 6.7 × 104 m2, which is larger than that of the LMZs at the TAG vent field on the Mid-Atlantic Ridge (MAR), as well as the Relict Field, Bastille, Dante-Grotto, and New Field vent-sites on the Juan de Fuca Ridge (JdF). The calculated magnetic moment, i.e., the product of the spatial extent and amplitude of crustal magnetization reduction is at least -3 × 107 Am2 for the LMZ on the SWIR, while that for the TAG field on the MAR is -8 × 107 Am2 and that for the four individual vent fields on the JdF range from -5 × 107 to -3 × 107 Am2. Together these results indicate that crustal demagnetization is a common feature of basalt-hosted hydrothermal vent fields at mid-ocean ridges of all spreading rates. Furthermore, the crustal demagnetization of the Area A on the ultraslow-spreading SWIR is comparable in strength to that of the TAG area on the slow-spreading MAR.

  5. Immunostimulant activity of n-butanol fraction of root bark of Oroxylum indicum, vent.

    PubMed

    Zaveri, Maitreyi; Gohil, Priyanshee; Jain, Sunita

    2006-07-01

    In the present study, the immunomodulatory activity and the mechanism of action of the n-butanol fraction (100 mg/kg body weight, per os, once daily for 22 consecutive days) of the root bark of Oroxylum indicum, vent. (Bignoniaceae) was evaluated in rats using measures of immune responses to sheep red blood cells (SRBC haemagglutinating antibody [HA] titer) and delayed-type hypersensitivity (DTH) reactions. In response to SRBC, treatment with the n-butanol fraction caused a significant rise in circulating HA titers during secondary antibody responses, indicating a potentiation of certain aspects of the humoral response. The treatment also resulted in a significant rise in paw edema formation, indicating increased host DTH response. Additionally, the antioxidant potential of the drug was exhibited by significant reductions in whole blood malondialdehyde (MDA) content along with a rise in the activities/levels of superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH). Furthermore, histopathologic analysis of lymphoid tissues showed an increase in cellularity, e.g., T-lymphocytes and sinusoids, in the treatment group. In contrast, dexamethasone treatment caused significant reduction in the HA titer, DTH responses, and antioxidant potential. In a triple antigen-mediated immunological edema model, the extent of edema raised in drug-treated rats was greater compared to that in control rats, thus confirming enhanced DTH reactions in response to the drug treatment. Based on the above findings, the reported immunomodulatory activity of an active fraction of O. indicum might be attributed to its ability to enhance specific immune responses (both humoral and cell-mediated) as well as its antioxidant potential. PMID:18958688

  6. δ37Cl of Mid-Ocean Ridge Vent Fluids Determined by a new SIMS Method for Stable Chlorine Isotope Ratio Measurements

    NASA Astrophysics Data System (ADS)

    Bach, W.; Layne, G. L.; von Damm, K. L.

    2002-12-01

    A method has been developed for the direct determination of δ37Cl in natural fluid samples or rock leachates (pyrohydrolysis products) using Secondary Ion Mass Spectrometry (SIMS). Samples as small as 1 μl (<2 μg Cl) are simply dried by evaporation and the residual salts are then admixed with 1 mg of graphite powder and pressed into a small (1mm diameter) pellet amenable to SIMS analysis. Analyses are performed with a large format high-transmission, high-resolution ion microprobe -- the IMS 1270. Mass resolving powers of greater than 5000 are used to exclude isobaric interferences on 35Cl and 37Cl, producing an accurate and reproducible measurement of δ37Cl. Nine analyses of NIST Cl isotope standard 975a yield an external reproducibility of 0.5 ‰ (2σ ). Repeat analyses of samples are reproducible within 1 ‰ . First δ37Cl data for mid-ocean ridge hydrothermal vent fluids from three sites at EPR 9°N and the Logatchev site (MAR 15°N) have been collected. End member δ37Cl compositions for the EPR fluids are between +6.5 and +7.1 ‰ , whereas that of the Logatchev fluid is +4.6 ‰ . Together with pore waters from accretionary prisms, which are depleted in 37Cl (-2.0 to -7.7 ‰ ; Ransom et al., Geology, 23, 715-718, 1995), seawater-derived fluids in the marine environment span range in δ37Cl of 15 ‰ . This variability is remarkably large when compared to >100 analyses of continental waters (formation and oil-field waters, fresh waters, brines, etc.) that cluster around 0 ‰ with a maximum variation of only 5 ‰ . Two observations suggest that the 37Cl enriched nature of the vent fluids is not related to phase separation. (1) Laboratory experiments indicate that the Δ37Cl(vapor-brine) associated with super-critical phase separation of seawater between 420 and 450°C is small (-0.6 to 0.2 ‰ ; Magenheim, PhD Thesis, UCSD, 1995). (2) Conjugate vapor-brine pairs of boiling sampled in 1991 and 1994 at F vent (Von Damm et al. EPSL, 149, 101-111, 1997

  7. Geochemical Controls on the Mobility of Cu and Fe in Hydrothermal Vent Fluids at Mid-Ocean Ridges: Experimental and Theoretical Constraints

    NASA Astrophysics Data System (ADS)

    Schaen, A. T.; Tutolo, B. M.; Seyfried, W. E.

    2012-12-01

    It has long been recognized that MOR hydrothermal vent fluids are characterized by variably high concentrations of dissolved transition metals. These metalliferous fluids play a role in the formation of seafloor massive sulfide deposits, serving as analogues for similar deposits on land, while also contributing to the flux of metals to seawater, with biogeochemical implications. Owing to the evolution of magmatic and tectonic processes associated with crustal formation at both fast and slow spreading ridges, chemical and physical conditions can change in space and time with corresponding changes in the solubility of Cu and Fe. Indeed, time series observations of hydrothermal vent fluids at EPR 9o N have provided unambiguous evidence of both diking and eruptive events with important implications for temperature and pressure changes affecting phase equilibria controls on mineral solubility. At the same time, recent advances in theoretical data have resulted in more robust thermodynamic models that can be used to calculate the effect of temperature and pressure, redox variability and dissolved chloride on metal mobility. However, fluid speciation calculations employing currently accepted Helgeson-Kirkham-Flowers (HKF) parameters for aqueous species result in Cu and Fe solubilities that differ significantly from constraints imposed by published experimental data and sampled MOR vent fluids. Consequently, new thermodynamic data is retrieved in this study from recent high P, T experimental data for Cu and Fe complexes and validated against new experiments to ensure accurate fluid speciation and trace metal solubility calculations. The addition of new experimental data to the thermodynamic data retrieval process strengthens predictions of geochemical interactions not only at the P and T of the experiments, but also over the entire range of applicability of the HKF model. For example, theoretical modeling of seawater salinity fluids (550 mmol/kg Cl) at 400 oC show

  8. Biogeography and biodiversity in sulfide structures of active and inactive vents at deep-sea hydrothermal fields of the Southern Mariana Trough.

    PubMed

    Kato, Shingo; Takano, Yoshinori; Kakegawa, Takeshi; Oba, Hironori; Inoue, Kazuhiko; Kobayashi, Chiyori; Utsumi, Motoo; Marumo, Katsumi; Kobayashi, Kensei; Ito, Yuki; Ishibashi, Jun-ichiro; Yamagishi, Akihiko

    2010-05-01

    The abundance, diversity, activity, and composition of microbial communities in sulfide structures both of active and inactive vents were investigated by culture-independent methods. These sulfide structures were collected at four hydrothermal fields, both on- and off-axis of the back-arc spreading center of the Southern Mariana Trough. The microbial abundance and activity in the samples were determined by analyzing total organic content, enzymatic activity, and copy number of the 16S rRNA gene. To assess the diversity and composition of the microbial communities, 16S rRNA gene clone libraries including bacterial and archaeal phylotypes were constructed from the sulfide structures. Despite the differences in the geological settings among the sampling points, phylotypes related to the Epsilonproteobacteria and cultured hyperthermophilic archaea were abundant in the libraries from the samples of active vents. In contrast, the relative abundance of these phylotypes was extremely low in the libraries from the samples of inactive vents. These results suggest that the composition of microbial communities within sulfide structures dramatically changes depending on the degree of hydrothermal activity, which was supported by statistical analyses. Comparative analyses suggest that the abundance, activity and diversity of microbial communities within sulfide structures of inactive vents are likely to be comparable to or higher than those in active vent structures, even though the microbial community composition is different between these two types of vents. The microbial community compositions in the sulfide structures of inactive vents were similar to those in seafloor basaltic rocks rather than those in marine sediments or the sulfide structures of active vents, suggesting that the microbial community compositions on the seafloor may be constrained by the available energy sources. Our findings provide helpful information for understanding the biogeography, biodiversity and

  9. Biogeography and Biodiversity in Sulfide Structures of Active and Inactive Vents at Deep-Sea Hydrothermal Fields of the Southern Mariana Trough▿ †

    PubMed Central

    Kato, Shingo; Takano, Yoshinori; Kakegawa, Takeshi; Oba, Hironori; Inoue, Kazuhiko; Kobayashi, Chiyori; Utsumi, Motoo; Marumo, Katsumi; Kobayashi, Kensei; Ito, Yuki; Ishibashi, Jun-ichiro; Yamagishi, Akihiko

    2010-01-01

    The abundance, diversity, activity, and composition of microbial communities in sulfide structures both of active and inactive vents were investigated by culture-independent methods. These sulfide structures were collected at four hydrothermal fields, both on- and off-axis of the back-arc spreading center of the Southern Mariana Trough. The microbial abundance and activity in the samples were determined by analyzing total organic content, enzymatic activity, and copy number of the 16S rRNA gene. To assess the diversity and composition of the microbial communities, 16S rRNA gene clone libraries including bacterial and archaeal phylotypes were constructed from the sulfide structures. Despite the differences in the geological settings among the sampling points, phylotypes related to the Epsilonproteobacteria and cultured hyperthermophilic archaea were abundant in the libraries from the samples of active vents. In contrast, the relative abundance of these phylotypes was extremely low in the libraries from the samples of inactive vents. These results suggest that the composition of microbial communities within sulfide structures dramatically changes depending on the degree of hydrothermal activity, which was supported by statistical analyses. Comparative analyses suggest that the abundance, activity and diversity of microbial communities within sulfide structures of inactive vents are likely to be comparable to or higher than those in active vent structures, even though the microbial community composition is different between these two types of vents. The microbial community compositions in the sulfide structures of inactive vents were similar to those in seafloor basaltic rocks rather than those in marine sediments or the sulfide structures of active vents, suggesting that the microbial community compositions on the seafloor may be constrained by the available energy sources. Our findings provide helpful information for understanding the biogeography, biodiversity and

  10. Mud Volcanism and Fluid Venting In The Eastern Mediterranean Sea: Observations From Sidescan Sonar and Submersible Surveys

    NASA Astrophysics Data System (ADS)

    Zitter, T. A. C.; Huguen, C.; Woodside, J. M.; Mascle, J.; Scientific Party, Medineth/Medinaut

    Mud volcanoes in the eastern Mediterranean Sea have been identified by their distinctive acoustic signature as well as their morphology and sedimentology. They appear as circular regions of high backscatter believed to be caused principally by the clast content of the mud flows forming the mud volcano. Both the MEDINAUT and MEDINETH expeditions, conducted in 1998 and 1999 over two mud fields, the Olimpi field and the Anaximander Mountains area, in Eastern Mediterranean Sea, studied mud volcanism using a multidisciplinary approach in order to determine the relationships between the activity of the mud volcanoes (importance of degassing, associated fauna) and their geophysical signature. Mud volcanoes in Eastern Mediterranean Sea vary from conical and dome-shaped reliefs from 500m to 2km wide and 100 to 200m high to large "mud pie" types up to 6km wide. Sidescan sonar records give a very high resolution of the acoustic response, enabling to distinguish several mud flows, often flowing along tectonic lineations. A clear relationship between the occurrence of mud volcanism and cold seeps and both thrust and transcurrent faulting has been observed in both mud fields, although the tectonic settings vary from purely compressional to a more transpressional stress field. The faults are inferred to provide pathways for over- pressured fluids, and secondary faulting (transcurrent and extensional faults) may facilitate mud ascension. On the basis of sidescan sonar interpretation, other typical features have been inferred such as main feeder channels, eruptive cone centers, or brine pools. The in situ observations have been used to characterize the seafloor over numerous mud volcanoes and ground-truth the sonar data. They reveal an abundance of fluid seeps, mainly methane and methane-rich brines, as well as associated specific fauna such as tube worms, clams and chemosynthetic bacteria, and specific diagenetic phenomenon i.e. carbonate crusts. Video observations proved that

  11. Methanocaldococcus bathoardescens sp. nov., a hyperthermophilic methanogen isolated from a volcanically active deep-sea hydrothermal vent.

    PubMed

    Stewart, Lucy C; Jung, Jong-Hyun; Kim, You-Tae; Kwon, Soon-Wo; Park, Cheon-Seok; Holden, James F

    2015-04-01

    A hyperthermophilic methanogen, strain JH146(T), was isolated from 26 °C hydrothermal vent fluid emanating from a crack in basaltic rock at Marker 113 vent, Axial Seamount in the northeastern Pacific Ocean. It was identified as an obligate anaerobe that uses only H2 and CO2 for growth. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain is more than 97% similar to other species of the genus Methanocaldococcus . Therefore, overall genome relatedness index analyses were performed to establish that strain JH146(T) represents a novel species. For each analysis, strain JH146(T) was most similar to Methanocaldococcus sp. FS406-22, which can fix N2 and also comes from Marker 113 vent. However, strain JH146(T) differs from strain FS406-22 in that it cannot fix N2. The average nucleotide identity score for strain JH146(T) was 87%, the genome-to-genome direct comparison score was 33-55% and the species identification score was 93%. For each analysis, strain JH146(T) was below the species delineation cut-off. Full-genome gene synteny analysis showed that strain JH146(T) and strain FS406-22 have 97% genome synteny, but strain JH146(T) was missing the operons necessary for N2 fixation and assimilatory nitrate reduction that are present in strain FS406-22. Based on its whole genome sequence, strain JH146(T) is suggested to represent a novel species of the genus Methanocaldococcus for which the name Methanocaldococcus bathoardescens is proposed. The type strain is JH146(T) ( = DSM 27223(T) = KACC 18232(T)). PMID:25634941

  12. Morphology and dynamics of explosive vents through cohesive rock formations

    NASA Astrophysics Data System (ADS)

    Galland, Olivier; Gisler, Galen R.; Haug, Øystein T.

    2015-04-01

    Shallow explosive volcanic processes, such as kimberlite volcanism, phreatomagmatic and phreatic activity, produce volcanic vents exhibiting a wide variety of morphologies, including vertical pipes and V-shaped vents. In this study we report on experimental and numerical models designed to capture a range of vent morphologies in an eruptive system (Galland et al., 2014). Using dimensional analysis, we identified key governing dimensionless parameters, in particular the gravitational stress-to-fluid pressure ratio (Π2=P/rho.g.h), and the fluid pressure-to-host rock strength ratio (Π3=P/C). We used combined experimental and numerical models to test the effects of these parameters. The experiments were used to test the effect of Π2 on vent morphology and dynamics. A phase diagram demonstrates a separation between two distinct morphologies, with vertical structures occurring at high values of Π2, and diagonal ones at low values of Π2. The numerical simulations were used to test the effect of Π3 on vent morphology and dynamics. In the numerical models we see three distinct morphologies: vertical pipes are produced at high values of Π3, diagonal pipes at low values of Π3, while horizontal sills are produced for intermediate values of Π3. Our results show that vertical pipes form by plasticity-dominated yielding for high-energy systems (high Π2 and Π3), whereas diagonal and horizontal vents dominantly form by fracturing for lower-energy systems (low Π2 and Π3). Although our models are 2-dimensionnal, they suggest that circular pipes result from plastic yielding of the host rock in a high-energy regime, whereas V-shaped volcanic vents result from fracturing of the host rock in lower-energy systems. Galland, O., Gisler, G.R., Haug, Ø.T., 2014. Morphology and dynamics of explosive vents through cohesive rock formations. J. Geophys. Res. 119, 10.1002/2014JB011050.

  13. Venting of carbon dioxide-rich fluid and hydrate formation in mid-okinawa trough backarc basin.

    PubMed

    Sakai, H; Gamo, T; Kim, E S; Tsutsumi, M; Tanaka, T; Ishibashi, J; Wakita, H; Yamano, M; Oomori, T

    1990-06-01

    Carbon dioxide-rich fluid bubbles, containing approximately 86 percent CO(2), 3 percent H(2)S, and 11 percent residual gas (CH(4) + H(2)), were observed to emerge from the sea floor at 1335- to 1550-m depth in the JADE hydrothermal field, mid-Okinawa Trough. Upon contact with seawater at 3.8 degrees C, gas hydrate immediately formed on the surface of the bubbles and these hydrates coalesced to form pipes standing on the sediments. Chemical composition and carbon, sulfur, and helium isotopic ratios indicate that the CO(2)-rich fluid was derived from the same magmatic source as dissolved gases in 320 degrees C hydrothermal solution emitted from a nearby black smoker chimney. The CO(2)-rich fluid phase may be separated by subsurface boiling of hydrothermal solutions or by leaching of CO(2)-rich fluid inclusion during posteruption interaction between pore water and volcanogenic sediments. PMID:17733370

  14. Hydrothermal vents in Lake Tanganyika, East African, Rift system

    NASA Astrophysics Data System (ADS)

    Tiercelin, Jean-Jacques; Pflumio, Catherine; Castrec, Maryse; Boulégue, Jacques; Gente, Pascal; Rolet, Joël; Coussement, Christophe; Stetter, Karl O.; Huber, Robert; Buku, Sony; Mifundu, Wafula

    1993-06-01

    Sublacustrine hydrothermal vents with associated massive sulfides were discovered during April 1987 at Pemba and Cape Banza on the Zaire side of the northern basin of Lake Tanganyika, East African Rift system. New investigations by a team of ten scuba divers during the multinational (France, Zaire, Germany, and Burundi) TANGANYDRO expedition (August-October 1991) found hydrothermal vents down to a depth of 46 m along north-trending active faults bounding the Tanganyika rift on the western side. Temperatures from 53 to 103 °C were measured in hydrothermal fluids and sediments. Veins of massive sulfides 1-10 cm thick (pyrite and marcasite banding) were found associated with vents at the Pemba site. At Cape Banza,active vents are characterized by 1-70-cm-high aragonite chimneys, and there are microcrystalline pyrite coatings on the walls of hydrothermal pipes. Hydrothermal fluid end members show distinctive compositions at the two sites. The Pemba end member is a NaHCO3-enriched fluid similar to the NaHCO3 thermal fluids from lakes Magadi and Bogoria in the eastern branch off the rift. The Cape Banza end member is a solution enriched in NaCl. Such brines may have a deep-seated basement origin, as do the Uvinza NaCl brines on the eastern flank of the Tanganyika basin. Geothermometric calculations have yielded temperatures of fluid-rock interaction off 219 and 179 °C in the Pemba and Cape Banza systems, respectively. Abundant white or reddish-brown microbial colonies resembling Beggiatoa mats were found surrounding the active vents. Thermal fluid circulation is permitted by opening of cracks related to 130 °N normal-dextral faults that intersect the north- south major rift trend. The source of heat for such hydrothermal systems may relate to the existence of magmatic bodies under the rift, which is suggested by the isotopic composition of carbon dioxide released at Pemba and Cape Banza.

  15. Hydrothermal vents of Yellowstone Lake, Yellowstone National Park, Wyoming

    SciTech Connect

    Kaplinski, M.A.; Morgan, P. . Geology Dept.)

    1993-04-01

    Hydrothermal vent systems within Yellowstone Lake are located within the Yellowstone caldera in the northeastern and West Thumb sections of the lake. The vent systems lie within areas of extremely high geothermal gradients (< 1,000 C/km) in the lake sediments and occur as clusters of individual vents that expel both hydrothermal fluids and gas. Regions surrounding the vents are colonized by unique, chemotropic biologic communities and suggest that hydrothermal input plays an important role in the nutrient dynamics of the lake's ecosystem. The main concentration of hydrothermal activity occurs in the northeast region of the main lake body in a number of locations including: (1) along the shoreline from the southern edge of Sedge Bay to the inlet of Pelican Creek; (2) the central portion of the partially submerged Mary Bay phreatic explosion crater, within deep (30--50 m) fissures; (3) along the top of a 3 km long, steep-sided ridge that extends from the southern border of Mary Bay, south-southeast into the main lake basin; and (4) east of Stevenson Island along the lower portion of the slope (50--107 m) into the lake basin, within an anastomosing series of north to northwest trending, narrow troughs or fissures. Hydrothermal vents were also located within, and surrounding the West Thumb of Yellowstone Lake, with the main concentration occurring the offshore of the West Thumb and Potts Geyser Basin. Hydrothermal vents in Yellowstone Lake occur along fractures that have penetrated the lake sediments or along the tops of ridges and near shore areas. Underneath the lake, rising hydrothermal fluids encounter a semi-permeable cap of lake sediments. Upwardly convecting hydrothermal fluid flow may be diverted by the impermeable lake sediments along the buried, pre-existing topography. These fluids may continue to rise along topography until fractures are encountered, or the lake sediment cover is thinned sufficiently to allow egress of the fluids.

  16. Evidence for a Chemoautotrophically Based Food Web at Inactive Hydrothermal Vents (Manus Basin)

    NASA Astrophysics Data System (ADS)

    van Dover, C. L.; Erickson, K.; Macko, S.

    2008-12-01

    Hydrothermal vents are ephemeral systems. When venting shuts down, sulfide-dependent taxa die off, and non-vent taxa can colonize the hard substrata. In Manus Basin (Papua New Guinea), where active and inactive sulfide mounds are interspersed, hydroids, cladorhizid sponges, barnacles, and bamboo sponges, and other invertebrate types may occupy inactive sulfide mounds. Carbon and nitrogen isotopic compositions of animals occupying inactive sulfide mounds are consistent with nutritional dependence on either chemoautotrophically or photosynthetically produced organic material, but sulfur isotopic compositions of these animals point to a chemoautotrophic source of sulfur from dissolved sulfide in vent fluids rather than sulfur derived from seawater sulfate through photosynthesis. Given that suspension-feeding and micro- carnivorous invertebrates are the biomass dominants at inactive sulfide mounds, the primary source of chemoautotrophic nutrition is likely suspended particulates and organisms delivered from nearby active vents.

  17. Evidence for a chemoautotrophically based food web at inactive hydrothermal vents (Manus Basin)

    NASA Astrophysics Data System (ADS)

    Erickson, K. L.; Macko, S. A.; Van Dover, C. L.

    2009-09-01

    Hydrothermal vents are ephemeral systems. When venting shuts down, sulfide-dependent taxa die off, and non-vent taxa can colonize the hard substrata. In Manus Basin (Papua New Guinea), where hydrothermally active and inactive sites are interspersed, hydroids, cladorhizid sponges, barnacles, bamboo corals, and other invertebrate types may occupy inactive sites. Carbon and nitrogen isotopic compositions of animals occupying inactive sites are consistent with nutritional dependence on either chemoautotrophically or photosynthetically produced organic material, but sulfur isotopic compositions of these animals point to a chemoautotrophic source of sulfur from dissolved sulfide in vent fluids rather than sulfur derived from seawater sulfate through photosynthesis. Given that suspension-feeding and micro-carnivorous invertebrates are the biomass dominants at inactive sites, the primary source of chemoautotrophic nutrition is likely suspended particulates and organisms delivered from nearby active vents.

  18. Vented Capacitor

    DOEpatents

    Brubaker, Michael Allen; Hosking, Terry Alan

    2006-04-11

    A technique of increasing the corona inception voltage (CIV), and thereby increasing the operating voltage, of film/foil capacitors is described. Intentional venting of the capacitor encapsulation improves the corona inception voltage by allowing internal voids to equilibrate with the ambient environment.

  19. Processes and Rates of Mass Transfer in Ultramafic-Hosted Hydrothermal Systems: An Experimental Study with Implications for Dissolved Inorganic and Organic Components in High-Temperature Vent Fluids

    NASA Astrophysics Data System (ADS)

    Seyfried, W. E.; Fu, Q.; Foustoukos, D. I.; Allen, D. E.

    2004-12-01

    Recently discovered ultramafic-hosted hydrothermal systems at mid-ocean ridges reveal high temperature vent fluids with relatively high SiO2, Ca, H2, and methane and other hydrocarbons. Dissolved Fe concentrations are the highest of any vent systems yet discovered and require a relatively low pH and reducing conditions in subseafloor reaction zones from which the fluids are derived. This, together with the SiO2 concentrations of the vent fluids, strongly indicates fluid buffering by silica-rich phases possibly produced during pyroxene dissolution, the likely abundant presence of olivine notwithstanding. Theoretical predictions of olivine dissolution kinetics at elevated temperatures and pressures, however, suggest relatively rapid conversion of olivine to talc and serpentine with corresponding lowering of dissolved SiO2 and Fe, and increase in pH. Thus, to test this, we performed a series of experiments at 400°C, 500 bars involving olivine (Fo89) alteration in SiO2-bearing systems containing dissolved Na and chloride concentrations approximately equivalent to the Rainbow hydrothermal system. Time series fluid samples indicate steady state conditions. Results confirm unusually slow olivine reaction kinetics, even when coexisting with moderate to high dissolved SiO2. XPS and SEM analysis indicate Fe-enrichment on olivine surfaces, and formation approximately 14 percent talc. The olivine to talc conversion rate suggests a log rate of olivine hydrolysis of -11.97 (moles/cm2/sec), well below that predicted from available rate data extrapolated from lower temperatures and pressures. The relative enrichment of Fe on olivine surfaces may decrease the thermodynamic and kinetic drive for olivine dissolution; effectively precluding pH increases predicted assuming full equilibrium. Rates and processes of mass transfer involving Fe-bearing minerals may also help to catalyze Fisher-Tropsch synthesis of complex hydrocarbons reported for vent fluids issuing from ultramafic

  20. Violent Gas Venting on the Heng-Chun Mud Volcano, South China Sea Active Continental Margin offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, S.; Cheng, W. Y.; Tseng, Y. T.; Chen, N. C.; Hsieh, I. C.; Yang, T. F.

    2014-12-01

    Accumulation of methane as gas hydrate under the sea floor has been considered a major trap for both thermal and biogenic gas in marine environment. Aided by rapid AOM process near the sea floor, fraction of methane escaping the sea floor has been considered at minuscule. However, most studies focused mainly on deepwater gas hydrate systems where gas hydrate remain relatively stable. We have studied methane seeps on the active margin offshore Taiwan, where rapid tectonic activities occur. Our intention is to evaluate the scale and condition of gas seeps in the tectonic active region. Towcam, coring, heat probe, chirp, multibeam bathymetric mapping and echo sounding were conducted at the study areas. Our results showed that gas is violently venting at the active margin, not only through sediments, but also through overlying sea water, directly into the atmosphere. Similar ventings, but, not in this scale, have also been identified previously in the nearby region. High concentrations of methane as well as traces of propane were found in sediments and in waters with flares. In conjunction, abundant chemosynthetic community, life mussel, clams, tube worms, bacterial mats together with high concentrations of dissolve sulfide, large authigenic carbonate buildups were also found. Our results indicate that methane could be another major green house gas in the shallow water active margin region.

  1. Distribution, activity and function of short-chain alkane degrading phylotypes in hydrothermal vent sediments

    NASA Astrophysics Data System (ADS)

    Adams, M. M.; Joye, S. B.; Hoarfrost, A.; Girguis, P. R.

    2012-12-01

    Global geochemical analyses suggest that C2-C4 short chain alkanes are a common component of the utilizable carbon pool in deep-sea sediments worldwide and have been found in diverse ecosystems. From a thermodynamic standpoint, the anaerobic microbial oxidation of these aliphatic hydrocarbons is more energetically yielding than the anaerobic oxidation of methane (AOM). Therefore, the preferential degradation of these hydrocarbons may compete with AOM for the use of oxidants such as sulfate, or other potential oxidants. Such processes could influence the fate of methane in the deep-sea. Sulfate-reducing bacteria (SRB) from hydrocarbon seep sediments of the Gulf of Mexico and Guaymas Basin have previously been enriched that anaerobically oxidize short chain alkanes to generate CO2 with the preferential utilization of 12C-enriched alkanes (Kniemeyer et al. 2007). Different temperature regimens along with multiple substrates were tested and a pure culture (deemed BuS5) was isolated from mesophilic enrichments with propane or n-butane as the sole carbon source. Through comparative sequence analysis, strain BuS5 was determined to cluster with the metabolically diverse Desulfosarcina / Desulfococcus cluster, which also contains the SRB found in consortia with anaerobic, methane-oxidizing archaea in seep sediments. Enrichments from a terrestrial, low temperature sulfidic hydrocarbon seep also corroborated that propane degradation occurred with most bacterial phylotypes surveyed belonging to the Deltaproteobacteria, particularly Desulfobacteraceae (Savage et al. 2011). To date, no microbes capable of ethane oxidation or anaerobic C2-C4 alkane oxidation at thermophilic temperature have been isolated. The sediment-covered, hydrothermal vent systems found at Middle Valley (Juan de Fuca Ridge, eastern Pacific Ocean) are a prime environment for investigating mesophilic to thermophilic anaerobic oxidation of short-chain alkanes, given the elevated temperatures and dissolved

  2. A ubiquitous thermoacidophilic archaeon from deep-sea hydrothermal vents

    USGS Publications Warehouse

    Reysenbach, A.-L.; Liu, Yajing; Banta, A.B.; Beveridge, T.J.; Kirshtein, J.D.; Schouten, S.; Tivey, M.K.; Von Damm, K. L.; Voytek, M.A.

    2006-01-01

    Deep-sea hydrothermal vents are important in global biogeochemical cycles, providing biological oases at the sea floor that are supported by the thermal and chemical flux from the Earth's interior. As hot, acidic and reduced hydrothermal fluids mix with cold, alkaline and oxygenated sea water, minerals precipitate to form porous sulphide-sulphate deposits. These structures provide microhabitats for a diversity of prokaryotes that exploit the geochemical and physical gradients in this dynamic ecosystem. It has been proposed that fluid pH in the actively venting sulphide structures is generally low (pH < 4.5), yet no extreme thermoacidophile has been isolated from vent deposits. Culture-independent surveys based on ribosomal RNA genes from deep-sea hydrothermal deposits have identified a widespread euryarchaeotal lineage, DHVE2 (deep-sea hydrothermal vent euryarchaeotic 2). Despite the ubiquity and apparent deep-sea endemism of DHVE2, cultivation of this group has been unsuccessful and thus its metabolism remains a mystery. Here we report the isolation and cultivation of a member of the DHVE2 group, which is an obligate thermoacidophilic sulphur- or iron-reducing heterotroph capable of growing from pH 3.3 to 5.8 and between 55 and 75??C. In addition, we demonstrate that this isolate constitutes up to 15% of the archaeal population, providing evidence that thermoacidophiles may be key players in the sulphur and iron cycling at deep-sea vents. ?? 2006 Nature Publishing Group.

  3. A ubiquitous thermoacidophilic archaeon from deep-sea hydrothermal vents.

    PubMed

    Reysenbach, Anna-Louise; Liu, Yitai; Banta, Amy B; Beveridge, Terry J; Kirshtein, Julie D; Schouten, Stefan; Tivey, Margaret K; Von Damm, Karen L; Voytek, Mary A

    2006-07-27

    Deep-sea hydrothermal vents are important in global biogeochemical cycles, providing biological oases at the sea floor that are supported by the thermal and chemical flux from the Earth's interior. As hot, acidic and reduced hydrothermal fluids mix with cold, alkaline and oxygenated sea water, minerals precipitate to form porous sulphide-sulphate deposits. These structures provide microhabitats for a diversity of prokaryotes that exploit the geochemical and physical gradients in this dynamic ecosystem. It has been proposed that fluid pH in the actively venting sulphide structures is generally low (pH < 4.5), yet no extreme thermoacidophile has been isolated from vent deposits. Culture-independent surveys based on ribosomal RNA genes from deep-sea hydrothermal deposits have identified a widespread euryarchaeotal lineage, DHVE2 (deep-sea hydrothermal vent euryarchaeotic 2). Despite the ubiquity and apparent deep-sea endemism of DHVE2, cultivation of this group has been unsuccessful and thus its metabolism remains a mystery. Here we report the isolation and cultivation of a member of the DHVE2 group, which is an obligate thermoacidophilic sulphur- or iron-reducing heterotroph capable of growing from pH 3.3 to 5.8 and between 55 and 75 degrees C. In addition, we demonstrate that this isolate constitutes up to 15% of the archaeal population, providing evidence that thermoacidophiles may be key players in the sulphur and iron cycling at deep-sea vents. PMID:16871216

  4. Morphology and dynamics of explosive vents through cohesive rock formations

    NASA Astrophysics Data System (ADS)

    Galland, O.; Gisler, G. R.; Haug, Ø. T.

    2014-06-01

    Shallow explosive volcanic processes, such as kimberlite volcanism and phreatomagmatic and phreatic activity, produce volcanic vents exhibiting a wide variety of morphologies, including vertical pipes and V-shaped vents. In this study we report on experimental and numerical models designed to capture a range of vent morphologies in an eruptive system. Using dimensional analysis, we identified key governing dimensionless parameters, in particular the gravitational stress-to-fluid pressure ratio (Π2 = P/ρgh) and the fluid pressure-to-host rock strength ratio (Π3 = P/C). We used combined experimental and numerical models to test the effects of these parameters. The experiments were used to test the effect of Π2 on vent morphology and dynamics. A phase diagram demonstrates a separation between two distinct morphologies, with vertical structures occurring at high values of Π2 and diagonal ones at low values of Π2. The numerical simulations were used to test the effect of Π3 on vent morphology and dynamics. In the numerical models we see three distinct morphologies: vertical pipes are produced at high values of Π3, diagonal pipes at low values of Π3, and horizontal sills at intermediate values of Π3. Our results show that vertical pipes form by plasticity-dominated yielding in high-energy systems (high Π2 and Π3), whereas diagonal and horizontal vents dominantly form by fracturing in lower energy systems (low Π2 and Π3). Although our models are two-dimensional, they suggest that circular pipes result from plastic yielding of the host rock in a high-energy regime, whereas V-shaped volcanic vents result from fracturing of the host rock in lower energy systems.

  5. In situ measurements of hydrogen sulfide, oxygen, and temperature in diffuse fluids of an ultramafic-hosted hydrothermal vent field (Logatchev, 14°45‧N, Mid-Atlantic Ridge): Implications for chemosymbiotic bathymodiolin mussels

    NASA Astrophysics Data System (ADS)

    Zielinski, Frank U.; Gennerich, Hans-Hermann; Borowski, Christian; WenzhöFer, Frank; Dubilier, Nicole

    2011-09-01

    The Logatchev hydrothermal vent field (14°45'N, Mid-Atlantic Ridge) is located in a ridge segment characterized by mantle-derived ultramafic outcrops. Compared to basalt-hosted vents, Logatchev high-temperature fluids are relatively low in sulfide indicating that the diffuse, low-temperature fluids of this vent field may not contain sufficient sulfide concentrations to support a chemosymbiotic invertebrate community. However, the high abundances of bathymodiolin mussels with bacterial symbionts related to free-living sulfur-oxidizing bacteria suggested that bioavailable sulfide is present at Logatchev. To clarify, if diffuse fluids above mussel beds of Bathymodiolus puteoserpentis provide the reductants and oxidants needed by their symbionts for aerobic sulfide oxidation, in situ microsensor measurements of dissolved hydrogen sulfide and oxygen were combined with simultaneous temperature measurements. High temporal fluctuations of all three parameters were measured above the mussel beds. H2S and O2 coexisted with mean concentrations between 9 and 31 μM (H2S) and 216 and 228 μM (O2). Temperature maxima (≤7.4°C) were generally concurrent with H2S maxima (≤156 μM) and O2 minima (≥142 μM). Long-term measurements for 250 days using temperature as a proxy for oxygen and sulfide concentrations indicated that the mussels were neither oxygen limited nor sulfide limited. Our in situ measurements at Logatchev indicate that sulfide may also be bioavailable in diffuse fluids from other ultramafic-hosted vents along slow and ultraslow spreading ridges.

  6. Microbial community structure of hydrothermal deposits from geochemically different vent fields along the Mid-Atlantic Ridge

    USGS Publications Warehouse

    Flores, Gilberto E.; Campbell, James H.; Kirshtein, Julie D.; Meneghin, Jennifer; Podar, Mircea; Steinberg, Joshua I.; Seewald, Jeffrey S.; Tivey, Margaret Kingston; Voytek, Mary A.; Yang, Zamin K.; Reysenbach, Anna-Louise

    2011-01-01

    To evaluate the effects of local fluid geochemistry on microbial communities associated with active hydrothermal vent deposits, we examined the archaeal and bacterial communities of 12 samples collected from two very different vent fields: the basalt-hosted Lucky Strike (37°17'N, 32°16.3'W, depth 1600-1750m) and the ultramafic-hosted Rainbow (36°13'N, 33°54.1'W, depth 2270-2330m) vent fields along the Mid-Atlantic Ridge (MAR). Using multiplexed barcoded pyrosequencing of the variable region 4 (V4) of the 16S rRNA genes, we show statistically significant differences between the archaeal and bacterial communities associated with the different vent fields. Quantitative polymerase chain reaction (qPCR) assays of the functional gene diagnostic for methanogenesis (mcrA), as well as geochemical modelling to predict pore fluid chemistries within the deposits, support the pyrosequencing observations. Collectively, these results show that the less reduced, hydrogen-poor fluids at Lucky Strike limit colonization by strict anaerobes such as methanogens, and allow for hyperthermophilic microaerophiles, like Aeropyrum. In contrast, the hydrogen-rich reducing vent fluids at the ultramafic-influenced Rainbow vent field support the prevalence of methanogens and other hydrogen-oxidizing thermophiles at this site. These results demonstrate that biogeographical patterns of hydrothermal vent microorganisms are shaped in part by large scale geological and geochemical processes.

  7. Microbial community structure of hydrothermal deposits from geochemically different vent fields along the Mid-Atlantic Ridge

    SciTech Connect

    Flores, Gilberto E; Campbell, James H; Kirshtein, Julie D; Meneghin, Jennifer; Podar, Mircea; Steinberg, Joshua; Seewald, Jeffrey S; Tivey, Margaret Kingston; Voytek, Mary A; Reysenbach, Anna-Louise; Yang, Zamin Koo

    2011-01-01

    To evaluate the effects of local fluid geochemistry on microbial communities associated with active hydrothermal vent deposits, we examined the archaeal and bacterial communities of 12 samples collected from two very different vent fields: the basalt-hosted Lucky Strike (37 17'N, 32 16.3'W, depth 1600-1750 m) and the ultramafic-hosted Rainbow (36 13'N, 33 54.1'W, depth 2270-2330 m) vent fields along the Mid-Atlantic Ridge (MAR). Using multiplexed barcoded pyrosequencing of the variable region 4 (V4) of the 16S rRNA genes, we show statistically significant differences between the archaeal and bacterial communities associated with the different vent fields. Quantitative polymerase chain reaction (qPCR) assays of the functional gene diagnostic for methanogenesis (mcrA), as well as geochemical modelling to predict pore fluid chemistries within the deposits, support the pyrosequencing observations. Collectively, these results show that the less reduced, hydrogen-poor fluids at Lucky Strike limit colonization by strict anaerobes such as methanogens, and allow for hyperthermophilic microaerophiles, like Aeropyrum. In contrast, the hydrogen-rich reducing vent fluids at the ultramafic-influenced Rainbow vent field support the prevalence of methanogens and other hydrogen-oxidizing thermophiles at this site. These results demonstrate that biogeographical patterns of hydrothermal vent microorganisms are shaped in part by large scale geological and geochemical processes.

  8. Active methane venting observed at giant pockmarks along the U.S. mid-Atlantic shelf break

    NASA Astrophysics Data System (ADS)

    Newman, Kori R.; Cormier, Marie-Helene; Weissel, Jeffrey K.; Driscoll, Neal W.; Kastner, Miriam; Solomon, Evan A.; Robertson, Gretchen; Hill, Jenna C.; Singh, Hanumant; Camilli, Richard; Eustice, Ryan

    2008-03-01

    Detailed near-bottom investigation of a series of giant, kilometer scale, elongate pockmarks along the edge of the mid-Atlantic continental shelf confirms that methane is actively venting at the site. Dissolved methane concentrations, which were measured with a commercially available methane sensor (METS) designed by Franatech GmbH mounted on an Autonomous Underwater Vehicle (AUV), are as high as 100 nM. These values are well above expected background levels (1-4 nM) for the open ocean. Sediment pore water geochemistry gives further evidence of methane advection through the seafloor. Isotopically light carbon in the dissolved methane samples indicates a primarily biogenic source. The spatial distribution of the near-bottom methane anomalies (concentrations above open ocean background), combined with water column salinity and temperature vertical profiles, indicate that methane-rich water is not present across the entire width of the pockmarks, but is laterally restricted to their edges. We suggest that venting is primarily along the top of the pockmark walls with some advection and dispersion due to local currents. The highest methane concentrations observed with the METS sensor occur at a small, circular pockmark at the southern end of the study area. This observation is compatible with a scenario where the larger, elongate pockmarks evolve through coalescing smaller pockmarks.

  9. Pattern formation in Active Polar Fluids

    NASA Astrophysics Data System (ADS)

    Gopinath, Arvind; Hagan, Michael; Baskaran, Aparna

    2011-03-01

    Systems such as bacterial suspensions or cytoskeletal filaments and motility assays can be described within the paradigm of active polar fluids. These systems have been shown to exhibit pattern formation raging from asters and vortices to traveling stripes. A coarse-grained description of such a fluid is given by a scalar density field and a vector polarization field. We study such a macroscopic description of the system using weakly nonlinear analysis and numerical simulations to map out the emergent pattern formation as a function of the hydrodynamic parameters in the context of two specific microscopic models - a quasi-2D suspension of cytoskeletal filaments and motor proteins and a system of self propelled hard rods that interact through excluded volume interactions. The authors thank the Brandeis MRSEC center for financial support.

  10. Vent Field Distribution and Evolution Along the Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Kelley, D. S.; Delaney, J. R.; Lilley, M. D.; Butterfield, D. A.

    2001-12-01

    Five major vent fields have now been discovered along the Endeavour Segment of the Juan de Fuca Ridge. From the north to the south they include Sasquatch, Salty Dawg, High Rise, Main Endeavour, and Mothra. Spacing between the distinct, high-temperature fields increases from the north to the south. For example Sasquatch is located 1.6 km north of Salty Dawg and Mothra is 2.7 km south of the Main Endeavour Field. In addition to changes in spacing of the vent fields along axis there are also dramatic changes in the style, intensity, and thermal-chemical characteristics of venting. The newly discovered Sasquatch field extends for >200 m in length, and venting is limited to a few isolated, small structures that reach 284° C. Active venting is confined to the northern portion of the field. In contrast, extinct, massive sulfide edifices and oxidized sulfide talus can be followed continuously for over 200 m along a 25-30 m wide, 020 trending ridge indicating that this field was very active in the past. In contrast to the delicate active structures, older extinct structures reach at least 25 m in height and the aspect ratios are similar to active pillars in the Mothra Field 7.5 km, to the south. It is unclear if venting at this site represents rejuvenation of the field, or whether it is in a waning stage. Within Salty Dawg, vent fluid temperatures reach 296° C and vigorous venting is constrained to a few, multi-flanged edifices that reach 25 m in height and 25 m in length. The field hosts over 25 structures, oxidized sulfide is abundant, and diffuse flow is dominant. Fluid compositions and temperatures are consistent with Salty Dawg being in a waning stage of evolution. Venting intensity and incidence of venting increase dramatically at High Rise where numerous multi-flanged structures are active; temperatures reach 343° C. The most intense and active of the fields is the Main Endeavour, with at least 21 actively venting, multi-flanged edifices that contain at least 100

  11. A Reactive-Transport Model Describing Methanogen Growth and Methane Production in Diffuse Flow Vents at Axial Seamount

    NASA Astrophysics Data System (ADS)

    Algar, C. K.

    2015-12-01

    Hydrogenotrophic methanogenesis is an important mode of metabolism in deep-sea hydrothermal vents. Diffuse vent fluids often show a depletion in hydrogen with a corresponding increase in methane relative to pure-mixing of end member fluid and seawater, and genomic surveys show an enrichment in genetic sequences associated with known methanogens. However, because we cannot directly sample the subseafloor habitat where these organisms are living, constraining the size and activity of these populations remains a challenge and limits our ability to quantify the role they play in vent biogeochemistry. Reactive-transport modeling may provide a useful tool for approaching this problem. Here we present a reactive-transport model describing methane production along the flow-path of hydrothermal fluid from its high temperature end-member to diffuse venting at the seafloor. The model is set up to reflect conditions at several diffuse vents in the Axial Seamount. The model describes the growth of the two dominant thermophilic methanogens, Methanothermococcus and Methanocaldococcus, observed at Axial seamount. Monod and Arrhenius constants for Methanothermococcus thermolithotrophicus and Methanocaldococcus jannaschii were obtained for the model using chemostat and bottle experiments at varying temperatures. The model is used to investigate the influence of different mixing regimes on the subseafloor populations of these methanogens. By varying the model flow path length and subseafloor cell concentrations, and fitting to observed hydrogen and methane concentrations in the venting fluid, the subseafloor biomass, fluid residence time, and methane production rate can be constrained.

  12. Dynamics and Emergent Structures in Active Fluids

    NASA Astrophysics Data System (ADS)

    Baskaran, Aparna

    2014-03-01

    In this talk, we consider an active fluid of colloidal sized particles, with the primary manifestation of activity being a self-replenishing velocity along one body axis of the particle. This is a minimal model for varied systems such as bacterial colonies, cytoskeletal filament motility assays vibrated granular particles and self propelled diffusophoretic colloids, depending on the nature of interaction among the particles. Using microscopic Brownian dynamics simulations, coarse-graining using the tools of non-equilibrium statistical mechanics and analysis of macroscopic hydrodynamic theories, we characterize emergent structures seen in these systems, which are determined by the symmetry of the interactions among the active units, such as propagating density waves, dense stationary bands, asters and phase separated isotropic clusters. We identify a universal mechanism, termed ``self-regulation,'' as the underlying physics that leads to these structures in diverse systems. Support from NSF through DMR-1149266 and DMR-0820492.

  13. Relationships between lava types, seafloor morphology, and the occurrence of hydrothermal venting in the ASHES vent field of Axial Volcano. [Axial Seamount Hydrothermal Emission Study

    SciTech Connect

    Hammond, S.R. )

    1990-08-10

    Deep-towed and submersible photographic surveys within the caldera of Axial Volcano have been integrated with high-resolution bathmetry to produce a geological map of the most active vent field in the caldera. Locations for over 2,000 photographs in and near the vent field were determined using a seafloor transponder network. Then each photograph was described utilizing a classification system which provides detailed information concerning lava type, hydrothermal activity, sediment cover, geological structure, and biology. Resulting data were entered into a digital data base, and computer-generated maps were created that portray spatial relationships between selected geological variables. In general, the entire ASHES field is characterized by pervasive low-temperature venting. The most vigorous venting is concentrated in an approximately 80 m {times} 80 m area where there are several high-temperature vents including some which are producing high-temperature vapor-phase fluids derived from a boiling hydrothermal system. Lava types within the ASHES vent field are grouped into three distinct morphologies: (1) smooth (flat-surfaced, ropy, and whorled) sheet flows, (2) lobate flows, and (3) jumbled-sheet flows. The most intense hydrothermal venting is concentrated in the smooth sheet flows and the lobate flows. The location of the ASHES field is mainly attributable to faulting which defines the southwest caldera wall, but the concentration of intense venting appears to be related also to the spatial distribution of lava types in the vent field and their contrasting permeabilities. Other structural trends of faults and fissures within the field also influence the location of individual events.

  14. New class of turbulence in active fluids.

    PubMed

    Bratanov, Vasil; Jenko, Frank; Frey, Erwin

    2015-12-01

    Turbulence is a fundamental and ubiquitous phenomenon in nature, occurring from astrophysical to biophysical scales. At the same time, it is widely recognized as one of the key unsolved problems in modern physics, representing a paradigmatic example of nonlinear dynamics far from thermodynamic equilibrium. Whereas in the past, most theoretical work in this area has been devoted to Navier-Stokes flows, there is now a growing awareness of the need to extend the research focus to systems with more general patterns of energy injection and dissipation. These include various types of complex fluids and plasmas, as well as active systems consisting of self-propelled particles, like dense bacterial suspensions. Recently, a continuum model has been proposed for such "living fluids" that is based on the Navier-Stokes equations, but extends them to include some of the most general terms admitted by the symmetry of the problem [Wensink HH, et al. (2012) Proc Natl Acad Sci USA 109:14308-14313]. This introduces a cubic nonlinearity, related to the Toner-Tu theory of flocking, which can interact with the quadratic Navier-Stokes nonlinearity. We show that as a result of the subtle interaction between these two terms, the energy spectra at large spatial scales exhibit power laws that are not universal, but depend on both finite-size effects and physical parameters. Our combined numerical and analytical analysis reveals the origin of this effect and even provides a way to understand it quantitatively. Turbulence in active fluids, characterized by this kind of nonlinear self-organization, defines a new class of turbulent flows. PMID:26598708

  15. Reactor pressure vessel vented head

    DOEpatents

    Sawabe, James K.

    1994-01-11

    A head for closing a nuclear reactor pressure vessel shell includes an arcuate dome having an integral head flange which includes a mating surface for sealingly mating with the shell upon assembly therewith. The head flange includes an internal passage extending therethrough with a first port being disposed on the head mating surface. A vent line includes a proximal end disposed in flow communication with the head internal passage, and a distal end disposed in flow communication with the inside of the dome for channeling a fluid therethrough. The vent line is fixedly joined to the dome and is carried therewith when the head is assembled to and disassembled from the shell.

  16. Active Polar Two-Fluid Macroscopic Dynamics

    NASA Astrophysics Data System (ADS)

    Pleiner, Harald; Svensek, Daniel; Brand, Helmut R.

    2014-03-01

    We study the dynamics of systems with a polar dynamic preferred direction. Examples include the pattern-forming growth of bacteria (in a solvent, shoals of fish (moving in water currents), flocks of birds and migrating insects (flying in windy air). Because the preferred direction only exists dynamically, but not statically, the macroscopic variable of choice is the macroscopic velocity associated with the motion of the active units. We derive the macroscopic equations for such a system and discuss novel static, reversible and irreversible cross-couplings connected to this second velocity. We find a normal mode structure quite different compared to the static descriptions, as well as linear couplings between (active) flow and e.g. densities and concentrations due to the genuine two-fluid transport derivatives. On the other hand, we get, quite similar to the static case, a direct linear relation between the stress tensor and the structure tensor. This prominent ``active'' term is responsible for many active effects, meaning that our approach can describe those effects as well. In addition, we also deal with explicitly chiral systems, which are important for many active systems. In particular, we find an active flow-induced heat current specific for the dynamic chiral polar order.

  17. Novel active vibration absorber with magnetorheological fluid

    NASA Astrophysics Data System (ADS)

    Gerlach, T.; Ehrlich, J.; Böse, H.

    2009-02-01

    Disturbing vibrations diminish the performance of technical high precision devices significantly. In search of a suitable solution for reducing these vibrations, a novel concept of active vibration reduction was developed which exploits the special properties of magnetorheological fluids. In order to evaluate the concept of such an active vibration absorber (AVA) a demonstrator was designed and manufactured. This demonstrator generates a force which counteracts the motion of the vibrating body. Since the counterforce is generated by a centrifugal exciter, the AVA provides the capability to compensate vibrations even in two dimensions. To control the strength of the force transmitted to the vibrating body, the exciter is based on a tunable MR coupling. The AVA was integrated in an appropriate testing device to investigate its performance. The recorded results show a significant reduction of the vibration amplitudes by an order of magnitude.

  18. Geomicrobiology of Hydrothermal Vents in Yellowstone Lake: Phylogenetic and Functional Analysis suggest Importance of Geochemistry (Invited)

    NASA Astrophysics Data System (ADS)

    Inskeep, W. P.; Macur, R.; Jay, Z.; Clingenpeel, S.; Tenney, A.; Lavalvo, D.; Shanks, W. C.; McDermott, T.; Kan, J.; Gorby, Y.; Morgan, L. A.; Yooseph, S.; Varley, J.; Nealson, K.

    2010-12-01

    Yellowstone Lake (Yellowstone National Park, WY, USA) is a large, high-altitude, fresh-water lake that straddles the most recent Yellowstone caldera, and is situated on top of significant hydrothermal activity. An interdisciplinary study is underway to evaluate the geochemical and geomicrobiological characteristics of several hydrothermal vent environments sampled using a remotely operated vehicle, and to determine the degree to which these vents may influence the biology of this young freshwater ecosystem. Approximately six different vent systems (locations) were sampled during 2007 and 2008, and included water obtained directly from the hydrothermal vents as well as biomass and sediment associated with these high-temperature environments. Thorough geochemical analysis of these hydrothermal environments reveals variation in pH, sulfide, hydrogen and other potential electron donors that may drive primary productivity. The concentrations of dissolved hydrogen and sulfide were extremely high in numerous vents sampled, especially the deeper (30-50 m) vents located in the Inflated Plain, West Thumb, and Mary Bay. Significant dilution of hydrothermal fluids occurs due to mixing with surrounding lake water. Despite this, the temperatures observed in many of these hydrothermal vents range from 50-90 C, and elevated concentrations of constituents typically associated with geothermal activity in Yellowstone are observed in waters sampled directly from vent discharge. Microorganisms associated with elemental sulfur mats and filamentous ‘streamer’ communities of Inflated Plain and West Thumb (pH range 5-6) were dominated by members of the deeply-rooted bacterial Order Aquificales, but also contain thermophilic members of the domain Archaea. Assembly of metagenome sequence from the Inflated Plain vent biomass and to a lesser extent, West Thumb vent biomass reveal the importance of Sulfurihydrogenibium-like organisms, also important in numerous terrestrial geothermal

  19. Overview af MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Griffin, Lisa; Williams, Robert

    2004-01-01

    This paper presents viewgraphs on NASA Marshall Space Flight Center's Applied Fluid Dynamics Analysis Group Activities. The topics include: 1) Status of programs at MSFC; 2) Fluid Mechanics at MSFC; 3) Relevant Fluid Dynamics Activities at MSFC; and 4) Shuttle Return to Flight.

  20. New class of turbulence in active fluids

    PubMed Central

    Bratanov, Vasil; Frey, Erwin

    2015-01-01

    Turbulence is a fundamental and ubiquitous phenomenon in nature, occurring from astrophysical to biophysical scales. At the same time, it is widely recognized as one of the key unsolved problems in modern physics, representing a paradigmatic example of nonlinear dynamics far from thermodynamic equilibrium. Whereas in the past, most theoretical work in this area has been devoted to Navier–Stokes flows, there is now a growing awareness of the need to extend the research focus to systems with more general patterns of energy injection and dissipation. These include various types of complex fluids and plasmas, as well as active systems consisting of self-propelled particles, like dense bacterial suspensions. Recently, a continuum model has been proposed for such “living fluids” that is based on the Navier–Stokes equations, but extends them to include some of the most general terms admitted by the symmetry of the problem [Wensink HH, et al. (2012) Proc Natl Acad Sci USA 109:14308–14313]. This introduces a cubic nonlinearity, related to the Toner–Tu theory of flocking, which can interact with the quadratic Navier–Stokes nonlinearity. We show that as a result of the subtle interaction between these two terms, the energy spectra at large spatial scales exhibit power laws that are not universal, but depend on both finite-size effects and physical parameters. Our combined numerical and analytical analysis reveals the origin of this effect and even provides a way to understand it quantitatively. Turbulence in active fluids, characterized by this kind of nonlinear self-organization, defines a new class of turbulent flows. PMID:26598708

  1. Motility of active fluid drops on surfaces

    NASA Astrophysics Data System (ADS)

    Khoromskaia, Diana; Alexander, Gareth P.

    2015-12-01

    Drops of active liquid crystal have recently shown the ability to self-propel, which was associated with topological defects in the orientation of active filaments [Sanchez et al., Nature 491, 431 (2013), 10.1038/nature11591]. Here, we study the onset and different aspects of motility of a three-dimensional drop of active fluid on a planar surface. We analyze theoretically how motility is affected by orientation profiles with defects of various types and locations, by the shape of the drop, and by surface friction at the substrate. In the scope of a thin drop approximation, we derive exact expressions for the flow in the drop that is generated by a given orientation profile. The flow has a natural decomposition into terms that depend entirely on the geometrical properties of the orientation profile, i.e., its bend and splay, and a term coupling the orientation to the shape of the drop. We find that asymmetric splay or bend generates a directed bulk flow and enables the drop to move, with maximal speeds achieved when the splay or bend is induced by a topological defect in the interior of the drop. In motile drops the direction and speed of self-propulsion is controlled by friction at the substrate.

  2. Gallium-67 activity in bronchoalveolar lavage fluid in sarcoidosis

    SciTech Connect

    Trauth, H.A.; Heimes, K.; Schubotz, R.; von Wichert, P.

    1986-01-01

    Roentgenograms and gallium-67 scans and gallium-67 counts of BAL fluid samples, together with differential cell counts, have proved to be useful in assessing activity and lung involvement in sarcoidosis. In active pulmonary sarcoidosis gallium-67 scans are usually positive. Quantitation of gallium-67 uptake in lung scans, however, may be difficult. Because gallium-67 uptake and cell counts in BAL fluid may be correlated, we set out to investigate gallium-67 activity in BAL fluid recovered from patient of different groups. Sixteen patients with recently diagnosed and untreated sarcoidosis, nine patients with healthy lungs, and five patients with CFA were studied. Gallium-67 uptake of the lung, gallium-67 activity in the lavage fluid, SACE and LACE levels, and alpha 1-AT activity were measured. Significantly more gallium-67 activity was found in BAL fluid from sarcoidosis patients than in that from CFA patients (alpha = .001) or patients with healthy lungs (alpha = .001). Gallium-67 activity in BAL fluid could be well correlated with the number of lymphocytes in BAL fluid, but poorly with the number of macrophages. Subjects with increased levels of SACE or serum alpha 1-AT showed higher lavage gallium-67 activity than did normals, but no correlation could be established. High gallium-67 activity in lavage fluid may be correlated with acute sarcoidosis or physiological deterioration; low activity denotes change for the better. The results show that gallium-67 counts in BAL fluid reflects the intensity of gallium-67 uptake and thus of activity of pulmonary sarcoidosis.

  3. High-Resolution Micro-Bathymetry Mapping in the Lau Basin: Examples From the Tui Malila and Mariner Vent Sites

    NASA Astrophysics Data System (ADS)

    Ferrini, V.; Sterling, A.; Martinez, F.; Tivey, M. K.; Mottl, M.; Kim, S.

    2005-12-01

    High-resolution SM2000 (200 kHz) multibeam sonar data were collected at six vent areas on the Lau Basin spreading center in April 2005. Data were acquired during near-bottom surveys conducted with the ROV Jason II at altitudes ranging from 5 to 20 m. High altitude (20 m) bathymetric surveys were complemented by near-bottom visual surveys, which provided ground-truth observations of the seafloor. Combined with Doppler and Long Baseline (LBL) Navigation, these bathymetry data provide sub-meter resolution of seafloor features, and reveal individual vent structures, faults and fissures. We present bathymetry data from two sites located 22 km apart, which are geologically and biologically distinct and exhibit contrasts in venting styles and biota. The Mariner vent field contains massive vent structures, many of which are taller than 25 m, with active venting from their bases and sides. Fluids exit as vigorous, high-temperature (< 363°C) black smoker fluids through chalcopyrite-lined conduits, and as less focused flow from porous beehive structures. Inactive structures are friable and are composed of iron- and copper-oxides. There was little evidence of faulting or fracture at the vent field, but we note the presence of collapsed volcanic dome structures. The vent fauna at Mariner is very limited; only Bythograeid and Galatheid crabs, and one Brisingid Seastar, were found. Tui Malila, by contrast, is characterized by shorter and wider branched vent structures with coalesced spires, the tops of which were actively venting. There is extensive faulting and fracture at this site, as well as a number of large flanges and areas of diffuse flow. At Tui Malila fluids exit tall structures through chalcopyrite- and zinc-lined conduits (at temperatures < 312°C), from beneath flanges, and directly from andesite. Hydrothermal breccias are also present. Tui Malila hosts a more typical vent community, with greater abundances of both Bythograeid and Galatheid crabs, mostly within 4 m

  4. Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Griffin, Lisa; Williams, Robert

    2002-01-01

    This viewgraph report presents an overview of activities and accomplishments of NASA's Marshall Space Flight Center's Applied Fluid Dynamics Analysis Group. Expertise in this group focuses on high-fidelity fluids design and analysis with application to space shuttle propulsion and next generation launch technologies. Topics covered include: computational fluid dynamics research and goals, turbomachinery research and activities, nozzle research and activities, combustion devices, engine systems, MDA development and CFD process improvements.

  5. Hydrothermal vents is Lake Tanganyika, East African Rift system

    SciTech Connect

    Tiercelin, J.J.; Pflumio, C.; Castrec, M.

    1993-06-01

    Sublacustrine hydrothermal vents with associated massive sulfides were discovered during April 1987 at Pemba and Cape Banza on the Zaire side of the northern basin of Lake Tanganyika, East African Rift system. New investigations by a team of ten scuba divers during the multinational (France, Zaire, Germany, and Burundi) TANGANYDRO expedition (August-October 1991) found hydrothermal vents down to a depth of 46 m along north-trending active faults bounding the Tanganyika rift on the western side. Temperatures from 53 to 103 {degrees}C were measured in hydrothermal fluids and sediments. Veins of massive sulfides 1-10 cm thick (pyrite and marcasite banding) were found associated with vents at the Pemba site. At Cape Banza, active vents are characterized by 1-70-cm-high aragonite chimneys, and there are microcrystalline pyrite coatings on the walls of hydrothermal pipes. Hydrothermal fluid end members show distinctive compositions at the two sites. The Pemba end member is a NaHCO{sub 3}-enriched fluid similar to the NaHCO{sub 3} thermal fluids form lakes Magadi and Bogoria in the eastern branch of the rift. The Cape Banza end member is a solution enriched in NaCl. Such brines may have a deep-seated basement origin, as do the Uvinza NaCl brines on the eastern flank of the Tanganyika basin. Geothermometric calculations have yielded temperatures of fluid-rock interaction of 219 and 179 {degrees}C in the Pemba and Cape Banza systems, respectively. Abundant white or reddish-brown microbial colonies resembling Beggiatoa mats were found surrounding the active vents. Thermal fluid circulation is permitted by opening of cracks related to 130{degrees}N normal-dextral faults that intersect the north-south major rift trend. The sources of heat for such hydrothermal systems may relate to the existence of magmatic bodies under the rift, which is suggested by the isotopic composition of carbon dioxide released at Pemba and Cape Banza. 21 refs., 2 figs.

  6. Geophysical Signatures of cold vents on the northern Cascadia margin

    NASA Astrophysics Data System (ADS)

    Riedel, M.; Paull, C. K.; Spence, G.; Hyndman, R. D.; Caress, D. W.; Thomas, H.; Lundsten, E.; Ussler, W.; Schwalenberg, K.

    2009-12-01

    The accretionary prism of the northern Cascadia margin is a classic gas hydrate research area. Ocean Drilling Program Leg 146 and Integrated Ocean Drilling Program (IODP) Expedition 311 documented that gas hydrate is widely distributed across the margin. In recent years an increased research focus has been on cold vents, where methane gas is actively released. Two recent expeditions funded by the Monterey Bay Aquarium Research Institute (MBARI) were conducted in the area of IODP Sites U1327 and U1328. An autonomous underwater vehicle (AUV) was used to map the seafloor bathymetry followed by dives with the ROV Doc Ricketts for ground truth information of various seafloor morphological features identified. The two cruises revealed many new seafloor features indicative of methane venting that were previously unknown. Bullseye Vent (BV) has been extensively studied using seismic imaging, piston coring, heat-flow, controlled-source EM, and deep drilling. BV is seismically defined by a circular wipe-out zone but the new AUV data show that BV is rather an elongated depression. BV is associated with a shoaling in the BSR, but lacks evidence for the existence of an underlying fault in the previous data. Although a massive gas-hydrate plug was encountered within the top 40 mbsf in the IODP holes, the ROV observations only revealed some platy methane derived carbonate outcrops at the outer-most rim of the depressions, a few beds of Vesicomya clams, and no observed gas vents, which together do not indicate that BV is especially active now. Further northeast of BV, but along the same trend, active gas venting was found associated with seafloor blistering and bacterial mats suggesting that there is an underlying fault system providing a fluid flow conduit. The newly discovered vent area has few seismic line crossings; however the available seismic data surprisingly are not associated with wipe-out zones. Another prominent fault-related gas vent also was investigated during the

  7. Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Griffin, Lisa; Williams, Robert

    2003-01-01

    TD64, the Applied Fluid Dynamics Analysis Group, is one of several groups with high-fidelity fluids design and analysis expertise in the Space Transportation Directorate at Marshall Space Flight Center (MSFC). TD64 assists personnel working on other programs. The group participates in projects in the following areas: turbomachinery activities, nozzle activities, combustion devices, and the Columbia accident investigation.

  8. 40Ar/39Ar dating of tuff vents in the Campi Flegrei caldera (southern Italy): Toward a new chronostratigraphic reconstruction of the Holocene volcanic activity

    USGS Publications Warehouse

    Fedele, L.; Insinga, D.D.; Calvert, A.T.; Morra, V.; Perrotta, A.; Scarpati, C.

    2011-01-01

    The Campi Flegrei hosts numerous monogenetic vents inferred to be younger than the 15 ka Neapolitan Yellow Tuff. Sanidine crystals from the three young Campi Flegrei vents of Fondi di Baia, Bacoli and Nisida were dated using 40Ar/39Ar geochronology. These vents, together with several other young edifices, occur roughly along the inner border of the Campi Flegrei caldera, suggesting that the volcanic conduits are controlled by caldera-bounding faults. Plateau ages of ∼9.6 ka (Fondi di Baia), ∼8.6 ka (Bacoli) and ∼3.9 ka (Nisida) indicate eruptive activity during intervals previously interpreted as quiescent. A critical revision, involving calendar age correction of literature 14C data and available 40Ar/39Ar age data, is presented. A new reference chronostratigraphic framework for Holocene Phlegrean activity, which significantly differs from the previously adopted ones, is proposed. This has important implications for understanding the Campi Flegrei eruptive history and, ultimately, for the evaluation of related volcanic risk and hazard, for which the inferred history of its recent activity is generally taken into account.

  9. Antioxidant systems and lipid peroxidation in Bathymodiolus azoricus from Mid-Atlantic Ridge hydrothermal vent fields.

    PubMed

    Bebianno, M J; Company, R; Serafim, A; Camus, L; Cosson, R P; Fiala-Médoni, A

    2005-11-30

    Enzymatic defenses involved in protection from oxygen radical damage were determined in gills and mantle of Bathymodiolus azoricus collected from three contrasting Mid-Atlantic Ridge (MAR) hydrothermal vent fields (Menez-Gwen, Lucky Strike and Rainbow). The activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (GPx) (total and Se-dependent), and levels of total oxyradical scavenging capacity (TOSC), metallothioneins (MT) and lipid peroxidation (LPO) were determined in B. azoricus tissues and the impact of metal concentrations on these antioxidant systems and lipid peroxidation assessed. SOD, CAT, TOSC, MTs and LPO levels were higher in B. azoricus gills while glutathione peroxidases (total and Se-dependent) were higher in the mantle, and with the exception of CAT, were of the same order of magnitude as in other molluscs. TOSC levels from Menez-Gwen indicate that the vent environment at this site is less stressful and the formation of ROS in mussels is effectively counteracted by the antioxidant defense system. TOSC depletion indicates an elevated ROS production in molluscs at the other two vent sites. Cytosolic SOD, GPx and LPO were more relevant at Lucky Strike (Bairro Alto) where levels of essential (Cu and Zn) and toxic metals (Cd and Ag) were highest in the organisms. CAT activity and LPO were predominant at the Rainbow vent site, where an excess of Fe in mussel tissues and in vent fluids (the highest of all three vent sites) may have contributed to increased LPO. Therefore, three distinct pathways for antioxidant enzyme systems and LPO based on environmental metal speciation of MAR vent fields are proposed for Bathymodiolus gills. At Menez-Gwen, TOSC towards peroxyl and hydroxyl radicals and peroxynitrite are predominant, while at Lucky Strike cytosolic SOD activity and GPx are the main antioxidant mechanisms. Finally at Rainbow, catalase and lipid peroxidation are dominant, suggesting that resistance of mussels to metal toxicity at

  10. Two Vent Fields Discovered at the Ultraslow Spreading Arctic Ridge System

    NASA Astrophysics Data System (ADS)

    Pedersen, R. B.; Thorseth, I. H.; Hellevang, B.; Schultz, A.; Taylor, P.; Knudsen, H. P.; Steinsbu, B. O.

    2005-12-01

    Two high-temperature vent fields were discovered at the Mohns Ridge during an expedition with the Norwegian research vessel "G.O. Sars" in July 2005. Both vent fields are located within the southernmost segment of the Mohns Ridge approximately 50 km north of the West Jan Mayen Fracture Zone. Water depths along this segment range from 3800 meters close to the fracture zone to ~500 meters at the segment centre where the vent fields are located. The largest field - named "Gallionella Garden" - is situated within a rift graben where high- and low-temperature venting occurs along ridge-parallel normal faults and fissures. Presently we have documented high- and low-temperature venting along more then 2 km of the fault and fissure system in the area. The high-temperature venting takes place at around 550 mbsl at the base of a 100 meter high fault wall and was traced ~500 meters along strike. The field consists of at least 10 major vent sites, each composed of multiple chimneys that are up to 5-10 meters tall. There are also large areas of diffuse flow. The temperature of the vent fluids was measured to be above 260°C at a chimney orifice. This is at the boiling point of seawater at these water depths, and gas bubbling was observed at several of the vent sites. A sample of the top of a chimney consists of anhydrite, barite, sphalerite and pyrite. Outside the high-temperature vent area mounds of ferric iron are abundant. Such deposits have presently been traced along ~2 km of the faults and fissure system in the area. The deposits are predominantly made up of branching and twisted stalks comparable to those formed by the iron oxidizing bacteria Gallionella ferruginea showing that the precipitation is mediated by microbial activity. The temperatures below the upper crust of a mound were measured to be one degree above the ambient water temperature. The Fe-oxyhydroxides show Nd-isotope compositions similar to the basaltic crust and Sr-isotope compositions close to that of

  11. 30,000 years of hydrothermal activity at the lost city vent field.

    PubMed

    Früh-Green, Gretchen L; Kelley, Deborah S; Bernasconi, Stefano M; Karson, Jeffrey A; Ludwig, Kristin A; Butterfield, David A; Boschi, Chiara; Proskurowski, Giora

    2003-07-25

    Strontium, carbon, and oxygen isotope data and radiocarbon ages document at least 30,000 years of hydrothermal activity driven by serpentinization reactions at Lost City. Serpentinization beneath this off-axis field is estimated to occur at a minimum rate of 1.2 x 10(-4) cubic kilometers per year. The access of seawater to relatively cool, fresh peridotite, coupled with faulting, volumetric expansion, and mass wasting processes, are crucial to sustain such systems. The amount of heat produced by serpentinization of peridotite massifs, typical of slow and ultraslow spreading environments, has the potential to drive Lost City-type systems for hundreds of thousands, possibly millions, of years. PMID:12881565

  12. Complement, complement activation and anaphylatoxins in human ovarian follicular fluid.

    PubMed Central

    Perricone, R; de Carolis, C; Moretti, C; Santuari, E; de Sanctis, G; Fontana, L

    1990-01-01

    Functionally active complement was sought and detected in human follicular fluids obtained during the pre-ovulatory period. All the functional complement activities tested, including total haemolytic complement, classical pathway activity and alternative pathway activity were present in nine fluids from four different donors with values within the normal serum range. The immunochemical analysis demonstrated the presence of complement factors from C1 to C9, of B and of C1 INH, H, I. Complement anaphylatoxins were found employing RIA techniques in amounts significantly higher than in human plasma, thus demonstrating that follicular fluid complement, at least during the pre-ovulatory period, is partially activated. A possible role for urokinase-like substances in such an activation was indicated by further in vitro experiments. The presence of active complement in follicular fluid can be relevant for the function of the enzymatic multi-factorial mechanism of ovulation. PMID:2242616

  13. Hydrothermal vents and methane seeps: Rethinking the sphere of influence

    USGS Publications Warehouse

    Levin, Lisa A.; Baco, Amy; Bowden, David; Colaco, Ana; Cordes, Erik E.; Cunha, Marina; Demopoulos, Amanda; Gobin, Judith; Grupe, Ben; Le, Jennifer; Metaxas, Anna; Netburn, Amanda; Rouse, Greg; Thurber, Andrew; Tunnicliffe, Verena; Van Dover, Cindy L.; Vanreusel, Ann; Watling, Les

    2016-01-01

    Although initially viewed as oases within a barren deep ocean, hydrothermal vent and methane seep communities are now recognized to interact with surrounding ecosystems on the sea floor and in the water column, and to affect global geochemical cycles. The importance of understanding these interactions is growing as the potential rises for disturbance from oil and gas extraction, seabed mining and bottom trawling. Here we synthesize current knowledge of the nature, extent and time and space scales of vent and seep interactions with background systems. We document an expanded footprint beyond the site of local venting or seepage with respect to elemental cycling and energy flux, habitat use, trophic interactions, and connectivity. Heat and energy are released, global biogeochemical and elemental cycles are modified, and particulates are transported widely in plumes. Hard and biotic substrates produced at vents and seeps are used by “benthic background” fauna for attachment substrata, shelter, and access to food via grazing or through position in the current, while particulates and fluid fluxes modify planktonic microbial communities. Chemosynthetic production provides nutrition to a host of benthic and planktonic heterotrophic background species through multiple horizontal and vertical transfer pathways assisted by flow, gamete release, animal movements, and succession, but these pathways remain poorly known. Shared species, genera and families indicate that ecological and evolutionary connectivity exists among vents, seeps, organic falls and background communities in the deep sea; the genetic linkages with inactive vents and seeps and background assemblages however, are practically unstudied. The waning of venting or seepage activity generates major transitions in space and time that create links to surrounding ecosystems, often with identifiable ecotones or successional stages. The nature of all these interactions is dependent on water depth, as well as

  14. Diverse styles of submarine venting on the ultraslow spreading Mid-Cayman Rise

    PubMed Central

    German, C. R.; Bowen, A.; Coleman, M. L.; Honig, D. L.; Huber, J. A.; Jakuba, M. V.; Kinsey, J. C.; Kurz, M. D.; Leroy, S.; McDermott, J. M.; de Lépinay, B. Mercier; Nakamura, K.; Seewald, J. S.; Smith, J. L.; Sylva, S. P.; Van Dover, C. L.; Whitcomb, L. L.; Yoerger, D. R.

    2010-01-01

    Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global mid-ocean ridge remains unexplored for hydrothermal activity. Of particular interest are the world’s ultraslow spreading ridges that were the last to be demonstrated to host high-temperature venting but may host systems particularly relevant to prebiotic chemistry and the origins of life. Here we report evidence for previously unknown, diverse, and very deep hydrothermal vents along the ∼110 km long, ultraslow spreading Mid-Cayman Rise (MCR). Our data indicate that the MCR hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultramafic systems and, at ∼5,000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent types identified here and their relative geographic isolation make the MCR unique in the oceans. These new sites offer prospects for an expanded range of vent-fluid compositions, varieties of abiotic organic chemical synthesis and extremophile microorganisms, and unparalleled faunal biodiversity—all in close proximity. PMID:20660317

  15. Diverse styles of submarine venting on the ultra-slow spreading Mid-Cayman Rise (Invited)

    NASA Astrophysics Data System (ADS)

    German, C. R.; Bowen, A.; Coleman, M. L.; Honig, D. L.; Huber, J. A.; Jakuba, M.; Kinsey, J. C.; Kurz, M. D.; Leroy, S.; McDermott, J.; Mercier de Lepinay, B. F.; Nakamura, K.; Seewald, J.; Smith, J.; Sylva, S.; van Dover, C. L.; Whitcomb, L. L.; Yoerger, D. R.

    2010-12-01

    Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global Mid Ocean Ridge remains unexplored for hydrothermal activity. Of particular interest are the world’s ultra-slow spreading ridges which were the last to be demonstrated to host high-temperature venting, but may host systems particularly relevant to pre-biotic chemistry and the origins of life. Here we report first evidence for diverse and very deep hydrothermal vents along the ~110 km long, ultra-slow spreading Mid-Cayman Rise collected using a combination of CTD-rosette operations and dives of the Hybrid Remotely Operated Vehicle (HROV) Nereus in 2009 followed by shore based work-up of samples for geochemical and microbiological analyses. Our data indicate that the Mid-Cayman Rise hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultra-mafic systems and, at ~5000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent-types identified here and their relative geographic isolation make the Mid-Cayman Rise unique in the oceans. These new sites offer prospects for: an expanded range of vent-fluid compositions; varieties of abiotic organic chemical synthesis and extremophile microorganisms; and unparalleled faunal biodiversity - all in close proximity.

  16. Mud volcano venting induced gas hydrate formation at the upper slope accretionary wedge, offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, Saulwood; Tseng, Yi-Ting; Cheng, Wan-Yen; Chou, Cheng-Tien; Chen, NeiChen; Hsieh, I.-Chih

    2016-04-01

    TsanYao Mud Volcano (TYMV) is the largest mud volcano cone in the Hengchun Mud Volcano Group (HCMVG), located at the upper slope of the accrretionary wedge, southwest of Taiwan. The region is under active tectonic activity with the Philippine Plate, moving northwestward at a rate of ~8 cm/year. This region also receives huge quantity of suspended particle load of ~100 mT/year at present time from adjacent small rivers of the Island of Taiwan. Large loads of suspended sediments influx become a major source of organic carbon and later gas and other hydrocarbon. Gas and fluid in the mud volcano are actively venting from deep to the sea floor on the upper slope of the accretionary wedge. In order to understand venting on the HCMVG, echo sounder, towcam and coring were carried out. Pore water sulfate, chloride, potassium, calcium, stable isotope O-18, gas compositions, dissolved sulfide were analysed. The HCMVG consists of 12 volcano cones of different sizes. Large quantity of gas and fluid are venting directly from deep to the TYMV structure high, as well as 50+ other vents as appeared as flares on the echo sounder. Some flares are reaching to the atmosphere and likely a source of green house gases to the atmosphere. Venting fluids include gas bubbles, suspended particle, mud, and breccia. Breccia size could reach more than 12 cm in diameter. Circular bands in different color appeared around the cone may represent stages of vent eruptions. Compositions of vent gas include methane, ethane and propane. High proportions of ethane and propane in the vent gas demonstrated that source of gas are thermogenic in origin. Patchy authigenic carbonate, bacterial mats, bivalves, tube worms and other chemosynthesis organisms were supported by venting gas AOM process near the sea floor. Pore water chloride concentrations show distinct variation pattern from center cone to the side of the volcano, with low in the center and high away from the cone. Pore water with higher than seawater

  17. Reactor pressure vessel vented head

    DOEpatents

    Sawabe, J.K.

    1994-01-11

    A head for closing a nuclear reactor pressure vessel shell includes an arcuate dome having an integral head flange which includes a mating surface for sealingly mating with the shell upon assembly therewith. The head flange includes an internal passage extending therethrough with a first port being disposed on the head mating surface. A vent line includes a proximal end disposed in flow communication with the head internal passage, and a distal end disposed in flow communication with the inside of the dome for channeling a fluid therethrough. The vent line is fixedly joined to the dome and is carried therewith when the head is assembled to and disassembled from the shell. 6 figures.

  18. Detection of active hydrothermal vent fields in the Pescadero Basin and on the Alarcon Rise using AUV multibeam and CTD data

    NASA Astrophysics Data System (ADS)

    Caress, D. W.; Troni, G.; Clague, D. A.; Paduan, J. B.; Martin, J. F.; Thomas, H. J.; Thompson, D.; Conlin, D.; Martin, E. J.; meneses-Quiroz, E.; Nieves-Cardoso, C.; Angel Santa Rosa del Rio, M.

    2015-12-01

    The MBARI AUV D. Allan B. collected high resolution bathymetry, sidescan, and subbottom profiles along the neovolcanic zone of the Alarcon Rise and across the southern Pescadero Basin during 2012 and 2015 MBARI expeditions to the Gulf of California (GOC). The combination of high resolution multibeam bathymetry and seawater temperature data has proven effective in identifying active high temperature vent fields, as validated by inspection and sampling during ROV dives. The AUV carries a 200 kHz multibeam sonar, 110 kHz chirp sidescan sonar, a 1-6 kHz chirp subbottom profiler, and a conductivity, temperature and depth (CTD) sensor for ~17-hour duration missions. Flying at 5.4 km/hr at 50 m altitude, the processed AUV bathymetry has a 0.1 m vertical precision and a 1 m lateral resolution. Chimneys taller than 1.5 m are sufficiently distinctive to allow provisional identification. The CTD temperature data have a nominal 0.002°C accuracy. Following calculation of potential temperature and correcting for average local variation of potential temperature with depth, anomalies greater than 0.05 °C can be reliably identified using a spike detection filter. MBARI AUV mapping surveys are typically planned using a 150 m survey line spacing, so the CTD data may be collected as much as 75 m away from any vent plume source. Five active high temperature vent fields were discovered in the southern GOC, with the Auka Field in the southern Pescadero Basin, and the Ja Sít, Pericú, Meyibó, and Tzab-ek Fields along the Alarcon Rise. In all five cases, hydrothermal vent chimneys are readily identifiable in the multibeam bathymetry, and temperature anomalies are observed above background variability. Other apparent hydrothermal chimneys were observed in the bathmetry that did not exhibit water temperature anomalies; most of these were visited during ROV dives and confirmed to be inactive sites. The maximum water column anomalies are 0.13°C observed above the Meyibó field and 0.25

  19. Hydrogen isotope exchange between n-alkanes and water under hydrothermal conditions: implications for abiotic and thermogenic hydrocarbons in vent fluids

    NASA Astrophysics Data System (ADS)

    Reeves, E. P.; Seewald, J.; Sylva, S.

    2010-12-01

    Stable isotopes are extensively utilized in studies of hydrocarbons in naturals fluids. However, factors controlling the hydrogen isotope (2H/1H) composition of dissolved hydrocarbons in hydrothermal fluids are still poorly understood despite interest in their 2H/1H signatures as indicators of abiogenesis. Due to its high activation energy for exchange, alkyl-bound hydrogen (H) is typically considered to be isotopically conservative. Incorporation of water-derived H under hydrothermal conditions may, however, obscure any primary signatures associated with abiotic polymerization. To examine this process, we conducted experiments to investigate 2H/1H exchange between aqueous n-alkanes and water using a Au-TiO2 flexible cell hydrothermal apparatus. C1-C5 n-alkanes were heated at 325°C and 350 bar in aqueous solutions of varying initial 2H/1H ratios (δ2H) in the presence of a pyrite-pyrrhotite-magnetite (PPM) mineral redox buffer. Extensive incorporation of water-derived H into C2-C5 n-alkanes was observed on timescales of months. In contrast, relatively minor incorporation was observed for CH4. Isotopic exchange is facilitated by reversible equilibration of n-alkanes and their corresponding alkenes by the reaction: CnH2n+2(aq) = CnH2n(aq) + H2(aq) Where H2(aq) is derived from water. The lack of substantial n-alkane decomposition on the timescale of observation, combined with an approach to steady-state isotopic compositions, indicate that n-alkane δD values likely reflect an approach to isotopic equilibrium rather than kinetically-controlled fractionation effects associated with degradation reactions. Substantially lower amounts of exchange were observed for ethane relative to C3-C5 n-alkanes, which suggests that alkene isomerization reactions may enhance incorporation of water-derived H in these compounds. Thus, reaction mechanisms exist in hydrothermal fluids that allow rapid 2H/1H exchange of alkyl-H with water on timescales comparable to crustal residence times

  20. Active mixing of complex fluids at the microscale

    PubMed Central

    Ober, Thomas J.; Foresti, Daniele; Lewis, Jennifer A.

    2015-01-01

    Mixing of complex fluids at low Reynolds number is fundamental for a broad range of applications, including materials assembly, microfluidics, and biomedical devices. Of these materials, yield stress fluids (and gels) pose the most significant challenges, especially when they must be mixed in low volumes over short timescales. New scaling relationships between mixer dimensions and operating conditions are derived and experimentally verified to create a framework for designing active microfluidic mixers that can efficiently homogenize a wide range of complex fluids. Active mixing printheads are then designed and implemented for multimaterial 3D printing of viscoelastic inks with programmable control of local composition. PMID:26396254

  1. Investigating the Influence of Magmatic Volatile Input and Seawater Entrainment on Vent Deposit Morphology and Composition in Manus Basin (Back-arc) Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Tivey, M.; Bach, W.; Tivey, M.; Seewald, J.; Craddock, P.; Rouxel, O.; Yoerger, D.; Yeats, C.; McConachy, T.; Quigley, M.; Vanko, D.

    2006-12-01

    In August 2006, hydrothermal activity within the eastern Manus Basin north of Papua New Guinea was investigated using a combination of mapping (SeaBeam from the R/V Melville, near-bottom multi-beam sonar and magnetometer from AUV ABE and ROV Jason-2) and sampling (fluids and solids using ROV Jason-2). Objectives included identifying tectonic/geologic settings, examining interactions of seawater with felsic rocks that constitute the high silica end-member in the range of basement compositions, determining the extent of volatile magmatic inputs into these systems, and examining the evolution of hydrothermal activity through time. At the PACMANUS (Papua New Guinea Australia Canada Manus) area five previously discovered vent fields were mapped and sampled, and a new very active field, Fenway, was located south of the Satanic Mills field. The core of the Fenway field is a 40 m diameter two-tiered mound. A large black smoker complex venting boiling (356C, 172 bar) fluids forms the upper tier, with the lower tier composed of sulfide debris, massive anhydrite-sulfide deposits, and anhydrite sand. At the DESMOS Caldera hyaloclastites and extensive patches of bleached and stained substrate were mapped and sampled, as were diffuse (72C) and focused (119C) acidic fluids with a pH (25C) of 1.0; no sulfide deposits were observed in the area. At the North Su vent field within the SuSu Knolls area even lower pH fluids were sampled (see Seewald et al., this session). Hydrothermal activity includes venting of white sulfur-rich fluids through cracks and sediments, formation of native sulfur flanges, diffuse venting through spires, and black smoker activity (324C). Anhydrite cement is also present. The abundance of massive anhydrite at Fenway and presence of anhydrite cement at North Su is consistent with significant local entrainment and heating of seawater. The extremely low pH (less than 2) of some vent fluids supports previous hypotheses that fluids in this area contain

  2. Increased digitalis-like activity in human cerebrospinal fluid after expansion of the extracellular fluid volume

    SciTech Connect

    Halperin, J.A.; Martin, A.M.; Malave, S.

    1985-08-12

    The present study was designed to determine whether acute expansion of the extracellular fluid volume influenced the digitalis-like activity of human cerebrospinal fluid (CSF), previously described. Human CSF samples, drawn before and 30 minutes after the intravenous infusion of 1 liter of either saline or glucose solutions, were assayed for digitalis-like activity by inhibition of either the /sup 86/Rb/sup +/ uptake into human erythrocytes or by the activity of a purified Na/sup +/-K/sup +/ ATPase. The CSF inhibitory activity on both systems significantly increased after the infusion of sodium solutions but did not change after the infusion of glucose. These results indicate that the digitalis-like factor of human CSF might be involved in the regulation of the extracellular fluid volume and electrolyte content and thereby in some of the physiological responses to sodium loading. 31 references, 2 figures, 1 table.

  3. Active microrheology of fluids inside developing zebrafish

    NASA Astrophysics Data System (ADS)

    Taormina, Mike; Parthasarathy, Raghuveer

    2014-03-01

    Biological fluids are a source of diverse and interesting behavior for the soft matter physicist. Since their mechanical properties must be tuned to fulfill functional roles important to the development and health of living things, they often display complex behavior on length and time scales spanning many orders of magnitude. For microbes colonizing an animal host, for example, the mechanical properties of the host environment are of great importance, affecting mobility and hence the ability to establish a stable population. Indeed, some species possess the ability to affect the fluidity of their environment, both directly by chemically modifying it, and indirectly by influencing the host cells' secretion of mucus. Driving magnetically doped micron-scale probes which have been orally micro-gavaged into the intestinal bulb of a larval zebrafish allows the rheology of the mucosal layer within the fish to be measured over three decades of frequency, complementing ecological data on microbial colonization with physical information about the gut environment. Here, we describe the technique, provide the first measurement of mucosal viscosity in a developing animal, and explore the technique's applicability to other small-volume or spatially inhomogeneous fluid samples.

  4. Discovery of a black smoker vent field and vent fauna at the Arctic Mid-Ocean Ridge

    PubMed Central

    Pedersen, Rolf B.; Rapp, Hans Tore; Thorseth, Ingunn H.; Lilley, Marvin D.; Barriga, Fernando J. A. S.; Baumberger, Tamara; Flesland, Kristin; Fonseca, Rita; Früh-Green, Gretchen L.; Jorgensen, Steffen L.

    2010-01-01

    The Arctic Mid-Ocean Ridge (AMOR) represents one of the most slow-spreading ridge systems on Earth. Previous attempts to locate hydrothermal vent fields and unravel the nature of venting, as well as the provenance of vent fauna at this northern and insular termination of the global ridge system, have been unsuccessful. Here, we report the first discovery of a black smoker vent field at the AMOR. The field is located on the crest of an axial volcanic ridge (AVR) and is associated with an unusually large hydrothermal deposit, which documents that extensive venting and long-lived hydrothermal systems exist at ultraslow-spreading ridges, despite their strongly reduced volcanic activity. The vent field hosts a distinct vent fauna that differs from the fauna to the south along the Mid-Atlantic Ridge. The novel vent fauna seems to have developed by local specialization and by migration of fauna from cold seeps and the Pacific. PMID:21119639

  5. Dynamics of an open basaltic magma system: The 2008 activity of the Halema'uma'u Overlook vent, Kīlauea Caldera

    NASA Astrophysics Data System (ADS)

    Eychenne, Julia; Houghton, Bruce F.; Swanson, Donald A.; Carey, Rebecca J.; Swavely, Lauren

    2015-01-01

    On March 19, 2008 a small explosive event accompanied the opening of a 35-m-wide vent (Overlook vent) on the southeast wall of Halema'uma'u Crater in Kīlauea Caldera, initiating an eruptive period that extends to the time of writing. The peak of activity, in 2008, consisted of alternating background open-system outgassing and spattering punctuated by sudden, short-lived weak explosions, triggered by collapses of the walls of the vent and conduit. Near-daily sampling of the tephra from this open system, along with exceptionally detailed observations, allow us to study the dynamics of the activity during two eruptive sequences in late 2008. Each sequence includes background activity preceding and following one or more explosions in September and October 2008 respectively. Componentry analyses were performed for daily samples to characterise the diversity of the ejecta. Nine categories of pyroclasts were identified in all the samples, including wall-rock fragments. The six categories of juvenile clasts can be grouped in three classes based on vesicularity: (1) poorly, (2) uniformly highly to extremely, and (3) heterogeneously highly vesicular. The wall-rock and juvenile clasts show dissimilar grainsize distributions, reflecting different fragmentation mechanisms. The wall-rock particles formed by failure of the vent and conduit walls above the magma free surface and were then passively entrained in the eruptive plume. The juvenile componentry reveals consistent contrasts in degassing and fragmentation processes before, during and after the explosive events. We infer a crude 'layering' developed in the shallow melt, in terms of both rheology and bubble and volatile contents, beneath a convecting free surface during background activity. A tens-of-centimetres thick viscoelastic surface layer was effectively outgassed and relatively cool, while at depths of less than 100 m, the melt remained slightly supersaturated in volatiles and actively vesiculating. Decoupled metre

  6. Dynamics of an open basaltic magma system: The 2008 activity of the Halema‘uma‘u Overlook vent, Kīlauea Caldera

    USGS Publications Warehouse

    Eychenne, Julia; Houghton, Bruce; Swanson, Don; Carey, Rebecca; Swavely, Lauren

    2015-01-01

    On March 19, 2008 a small explosive event accompanied the opening of a 35-m-wide vent (Overlook vent) on the southeast wall of Halema‘uma‘u Crater in Kīlauea Caldera, initiating an eruptive period that extends to the time of writing. The peak of activity, in 2008, consisted of alternating background open-system outgassing and spattering punctuated by sudden, short-lived weak explosions, triggered by collapses of the walls of the vent and conduit. Near-daily sampling of the tephra from this open system, along with exceptionally detailed observations, allow us to study the dynamics of the activity during two eruptive sequences in late 2008. Each sequence includes background activity preceding and following one or more explosions in September and October 2008 respectively. Componentry analyses were performed for daily samples to characterise the diversity of the ejecta. Nine categories of pyroclasts were identified in all the samples, including wall-rock fragments. The six categories of juvenile clasts can be grouped in three classes based on vesicularity: (1) poorly, (2) uniformly highly to extremely, and (3) heterogeneously highly vesicular. The wall-rock and juvenile clasts show dissimilar grainsize distributions, reflecting different fragmentation mechanisms. The wall-rock particles formed by failure of the vent and conduit walls above the magma free surface and were then passively entrained in the eruptive plume. The juvenile componentry reveals consistent contrasts in degassing and fragmentation processes before, during and after the explosive events. We infer a crude ‘layering’ developed in the shallow melt, in terms of both rheology and bubble and volatile contents, beneath a convecting free surface during background activity. A tens-of-centimetres thick viscoelastic surface layer was effectively outgassed and relatively cool, while at depths of less than 100 m, the melt remained slightly supersaturated in volatiles and actively vesiculating

  7. Isotopic signatures associated with growth and metabolic activities of chemosynthetic nitrate-reducing microbes from deep-sea hydrothermal vents

    NASA Astrophysics Data System (ADS)

    Perez-Rodriguez, I. M.; Foustoukos, D.; Fogel, M. L.; Sievert, S. M.

    2013-12-01

    Epsilonproteobacteria and Aquificaceae have been identified as dominant members of microbial communities at deep-sea hydrothermal vents. Cultured representatives from these two groups appear to be mostly genetically wired to perform chemosynthesis at moderate-to-high temperatures (45 - 80oC) under anaerobic and sulfidic conditions. In this study we used Caminibacter mediatlanticus and Thermovibrio ammonificans as model organisms to constrain physiological parameters associated with dissimilatory nitrate reduction to ammonium (DNRA) in deep-sea vent Epsilonproteobacteria and Aquificaceae. We postulate that nitrate-based metabolic processes are of relevance for understanding primary production as well as nitrate mobilization in deep-sea vents. By constraining growth and respiration rates during DNRA, we observed that C. mediatlanticus achieved higher cell densities than T. ammonificans while exhibiting similar growth rates. DNRA kinetic rate constants and cell-specific nitrate reduction rates (csNRR) obtained from our data showed that within similar time frames T. ammonificans used 2.5 to 3 times as much nitrate than C. mediatlanticus and it did so ~3 times faster. However, the increased consumption of nitrate in T. ammonificans did not translate into higher growth yield. This is suggestive of either differential efficiencies in energy generating pathways or differential organic matter production (cell biomass versus extracellular organic material) associated with DNRA in these microorganisms. Nitrogen isotope fractionation for nitrate was similar for both organisms, with discrimination factors of ~ -5 to -6‰ for C. mediatlanticus and ~ -7 to -8‰ for T. ammonificans. Similar experiments performed under high hydrostatic pressure conditions (50 and 200 bar) showed that changes in pressure greatly affected both growth rates and DNRA kinetic rate constants in both microorganisms, however, δ15N discrimination factors for nitrate were not affected. This study provides

  8. Implications of an ultramafic body in a basalt-dominated oceanic hydrothermal system on the vent fluid composition and on processes within sediments overlying a hydrothermal discharge zone: results of reactive-transport modeling

    NASA Astrophysics Data System (ADS)

    Alt-Epping, P.; Diamond, L. W.

    2009-04-01

    We use 2D reactive transport simulations to assess the hydraulic, thermal and chemical implications of an ultramafic body of lherzolitic composition within a basalt-dominated oceanic hydrothermal system. The simulations are fully coupled and hence account for the progressive serpentinization and the associated porosity/permeability reduction of the model lherzolite over time. We focus on the chemical fingerprints that reveal the presence of the ultramafic body at depth and that may be detected by direct seafloor exploration. These are the vent fluid composition and the porewater and mineral alteration within the rock column overlying a hydrothermal discharge zone. We compare ocean crust sections with and without sedimentary cover. Simulations suggest that the boundary between the basalt and the lherzolite constitutes a sharp reaction front. The type and distribution of alteration phases that form at the reaction front are a result of fluid flow across the basalt-lherzolite interface and thus are determined by the geometry and rate of hydrothermal fluid flow. Consequently, observations of the occurrence and extent of alteration phases, such as Fe-rich chlorite in the lherzolite or of rodingitization of the basalt, may be interpreted in terms of the reactive-transport model to reconstruct paleo-fluid flow in the permeable oceanic basement. The alteration of the lherzolite produces a fluid that is strongly reducing and depleted in silica. The most important chemical indicator of this rock-water interaction is an elevated H2 concentration. Under reducing (i.e. SO4-2 and CO2 free) conditions the enrichment in H2 is proportional to the extent of reaction between the fluid and the ultramafic rock. Under these conditions H2 behaves conservatively and the fluid remains enriched in H2 even though the concentration of all other major aqueous species is quickly buffered to new values when the fluid subsequently passes through basalt. This produces a vent fluid which is

  9. Shallow vent architecture during hybrid explosive-effusive activity at Cordón Caulle (Chile, 2011-12): Evidence from direct observations and pyroclast textures

    NASA Astrophysics Data System (ADS)

    Schipper, C. Ian; Castro, Jonathan M.; Tuffen, Hugh; James, Mike R.; How, Penelope

    2013-07-01

    In June 2011, an eruption of rhyolite magma began at the Puyehue-Cordón Caulle volcanic complex, southern Chile. By January 2012, explosive activity had declined from sustained pyroclastic (Plinian to sub-Plinian) fountaining to mixed gas and ash jetting punctuated by Vulcanian blasts. This explosive activity was accompanied by synchronous effusion of obsidian lava in a hybrid explosive-effusive eruption. Fortuitous climatic conditions permitted ground-based observation and video recording of transient vent dynamics as well as real-time collection of proximal juvenile ash as it sedimented from the active plume. The main eruptive vent complex and site of lava effusion were represented by two loci of Vulcanian blasts within a single tephra cone containing a pancake-shaped proto-lava dome. These blast loci each consisted of clusters of sub-vents that expressed correlated shifts in eruption intensity, indicating the presence of partially connected and/or branching zones of high permeability within the upper conduit. Pyroclast textures were examined by X-ray computed microtomography and their permeability was modelled by lattice Boltzmann simulations. The porosity (39 to 67%) and Darcian permeability (3.1 × 10- 15 m2 perpendicular to fabric to 3.8 × 10- 11 m2 parallel to fabric) of fine ash emitted during ash jetting indicate that the permeable zones comprised highly sheared, tube-like bubbly magma, and contrast with the low porosity (~ 17%) and nul permeability of bombs ejected to hundreds of metres from the vent in Vulcanian blasts. Residual H2O content of ash (0.14 wt.%) and two bombs (0.2-0.25 wt.%), determined by Karl-Fischer titration indicate degassing of this pyroclastic material to near-atmospheric pressures. Ash textures and simple degassing/vesiculation models indicate the onset of permeability by ductile processes of shear-enhanced bubble coalescence in the upper 1 to 1.5 km of the conduit. Repeated ash jetting and Vulcanian blasts indicate that such

  10. Surface activity of Janus particles adsorbed at fluid-fluid interfaces: Theoretical and experimental aspects.

    PubMed

    Fernandez-Rodriguez, Miguel Angel; Rodriguez-Valverde, Miguel Angel; Cabrerizo-Vilchez, Miguel Angel; Hidalgo-Alvarez, Roque

    2016-07-01

    Since de Gennes coined in 1992 the term Janus particle (JP), there has been a continued effort to develop this field. The purpose of this review is to present the most relevant theoretical and experimental results obtained so far on the surface activity of amphiphilic JPs at fluid interfaces. The surface activity of JPs at fluid-fluid interfaces can be experimentally determined using two different methods: the classical Langmuir balance or the pendant drop tensiometry. The second method requires much less amount of sample than the first one, but it has also some experimental limitations. In all cases collected here the JPs exhibited a higher surface or interfacial activity than the corresponding homogeneous particles. This reveals the significant advantage of JPs for the stabilization of emulsions and foams. PMID:26094083

  11. Chemical signatures from hydrothermal venting on slow spreading ridges

    NASA Astrophysics Data System (ADS)

    Edmonds, Henrietta N.

    At least 24 sites of active venting have been confirmed on slow and ultraslow spreading ridges, with dozens more indicated on the basis of hydrothermal plume distributions and/or dredge recovery of massive sulfides. Fluid chemistry data have been published for 13 sites: 8 on the northern Mid-Atlantic Ridge, 3 on the southern Mid-Atlantic Ridge, and 2 on the Central Indian Ridge. Three of these 13 sites (Rainbow, Logatchev, and Lost City) are known to be hosted in ultramafic terrain, and their fluid chemistries reflect the influence of serpentinization reactions, including elevated hydrogen and methane, and low silica concentrations. This brief review presents the published fluid chemistry for all 13 sites, including time series where available, and demonstrates the diversity of chemical compositions engendered by the myriad settings (near and off axis, young volcanic to ultramafic terrain, and depths up to 4100 m) of hydrothermal systems on slow and ultraslow spreading ridges.

  12. Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Wang, Tee-See; Griffin, Lisa; Turner, James E. (Technical Monitor)

    2001-01-01

    This document is a presentation graphic which reviews the activities of the Applied Fluid Dynamics Analysis Group at Marshall Space Flight Center (i.e., Code TD64). The work of this group focused on supporting the space transportation programs. The work of the group is in Computational Fluid Dynamic tool development. This development is driven by hardware design needs. The major applications for the design and analysis tools are: turbines, pumps, propulsion-to-airframe integration, and combustion devices.

  13. Battery venting system and method

    DOEpatents

    Casale, Thomas J.; Ching, Larry K. W.; Baer, Jose T.; Swan, David H.

    1999-01-05

    Disclosed herein is a venting mechanism for a battery. The venting mechanism includes a battery vent structure which is located on the battery cover and may be integrally formed therewith. The venting mechanism includes an opening extending through the battery cover such that the opening communicates with a plurality of battery cells located within the battery case. The venting mechanism also includes a vent manifold which attaches to the battery vent structure. The vent manifold includes a first opening which communicates with the battery vent structure opening and second and third openings which allow the vent manifold to be connected to two separate conduits. In this manner, a plurality of batteries may be interconnected for venting purposes, thus eliminating the need to provide separate vent lines for each battery. The vent manifold may be attached to the battery vent structure by a spin-welding technique. To facilitate this technique, the vent manifold may be provided with a flange portion which fits into a corresponding groove portion on the battery vent structure. The vent manifold includes an internal chamber which is large enough to completely house a conventional battery flame arrester and overpressure safety valve. In this manner, the vent manifold, when installed, lessens the likelihood of tampering with the flame arrester and safety valve.

  14. Battery venting system and method

    DOEpatents

    Casale, T.J.; Ching, L.K.W.; Baer, J.T.; Swan, D.H.

    1999-01-05

    Disclosed herein is a venting mechanism for a battery. The venting mechanism includes a battery vent structure which is located on the battery cover and may be integrally formed therewith. The venting mechanism includes an opening extending through the battery cover such that the opening communicates with a plurality of battery cells located within the battery case. The venting mechanism also includes a vent manifold which attaches to the battery vent structure. The vent manifold includes a first opening which communicates with the battery vent structure opening and second and third openings which allow the vent manifold to be connected to two separate conduits. In this manner, a plurality of batteries may be interconnected for venting purposes, thus eliminating the need to provide separate vent lines for each battery. The vent manifold may be attached to the battery vent structure by a spin-welding technique. To facilitate this technique, the vent manifold may be provided with a flange portion which fits into a corresponding groove portion on the battery vent structure. The vent manifold includes an internal chamber which is large enough to completely house a conventional battery flame arrester and overpressure safety valve. In this manner, the vent manifold, when installed, lessens the likelihood of tampering with the flame arrester and safety valve. 8 figs.

  15. Battery Vent Mechanism And Method

    DOEpatents

    Ching, Larry K. W.

    2000-02-15

    Disclosed herein is a venting mechanism for a battery. The venting mechanism includes a battery vent structure which is located on the battery cover and may be integrally formed therewith. The venting mechanism includes an opening extending through the battery cover such that the opening communicates with a plurality of battery cells located within the battery case. The venting mechanism also includes a vent manifold which attaches to the battery vent structure. The vent manifold includes a first opening which communicates with the battery vent structure opening and second and third openings which allow the vent manifold to be connected to two separate conduits. In this manner, a plurality of batteries may be interconnected for venting purposes, thus eliminating the need to provide separate vent lines for each battery. The vent manifold may be attached to the battery vent structure by a spin-welding technique. To facilitate this technique, the vent manifold may be provided with a flange portion which fits into a corresponding groove portion on the battery vent structure. The vent manifold includes an internal chamber which is large enough to completely house a conventional battery flame arrester and overpressure safety valve. In this manner, the vent manifold, when installed, lessens the likelihood of tampering with the flame arrester and safety valve.

  16. Effects of Hemagglutination Activity in the Serum of a Deep-Sea Vent Endemic Crab, Shinkaia Crosnieri, on Non-Symbiotic and Symbiotic Bacteria.

    PubMed

    Fujiyoshi, So; Tateno, Hiroaki; Watsuji, Tomoo; Yamaguchi, Hideyuki; Fukushima, Daisuke; Mino, Sayaka; Sugimura, Makoto; Sawabe, Tomoo; Takai, Ken; Sawayama, Shigeki; Nakagawa, Satoshi

    2015-01-01

    In deep-sea hydrothermal environments, most invertebrates associate with dense populations of symbiotic microorganisms in order to obtain nutrition. The molecular interactions between deep-sea animals and environmental microbes, including their symbionts, have not yet been elucidated in detail. Hemagglutinins/lectins, which are carbohydrate-binding proteins, have recently been reported to play important roles in a wide array of biological processes, including the recognition and control of non-self materials. We herein assessed hemagglutination activity in the serum of a deep-sea vent endemic crab, Shinkaia crosnieri, which harbors chemosynthetic epibionts on its plumose setae. Horse and rabbit erythrocytes were agglutinated using this serum (opt. pH 7.5 and opt. temperature 15°C). Agglutinating activity was inhibited by eight kinds of sugars and several divalent cations, did not require any divalent metal ions, and remained detectable even after heating the serum at 100°C for 30 min. By using fluorescently labeled serum, we demonstrated that deep-sea crab serum components bound to the epibionts even in the presence of sugars. This study represents the first immunological assessment of a deep-sea vent endemic crab and demonstrated the possibility of a non-lectin-mediated symbiont-host interaction. PMID:26212518

  17. Effects of Hemagglutination Activity in the Serum of a Deep-Sea Vent Endemic Crab, Shinkaia Crosnieri, on Non-Symbiotic and Symbiotic Bacteria

    PubMed Central

    Fujiyoshi, So; Tateno, Hiroaki; Watsuji, Tomoo; Yamaguchi, Hideyuki; Fukushima, Daisuke; Mino, Sayaka; Sugimura, Makoto; Sawabe, Tomoo; Takai, Ken; Sawayama, Shigeki; Nakagawa, Satoshi

    2015-01-01

    In deep-sea hydrothermal environments, most invertebrates associate with dense populations of symbiotic microorganisms in order to obtain nutrition. The molecular interactions between deep-sea animals and environmental microbes, including their symbionts, have not yet been elucidated in detail. Hemagglutinins/lectins, which are carbohydrate-binding proteins, have recently been reported to play important roles in a wide array of biological processes, including the recognition and control of non-self materials. We herein assessed hemagglutination activity in the serum of a deep-sea vent endemic crab, Shinkaia crosnieri, which harbors chemosynthetic epibionts on its plumose setae. Horse and rabbit erythrocytes were agglutinated using this serum (opt. pH 7.5 and opt. temperature 15°C). Agglutinating activity was inhibited by eight kinds of sugars and several divalent cations, did not require any divalent metal ions, and remained detectable even after heating the serum at 100°C for 30 min. By using fluorescently labeled serum, we demonstrated that deep-sea crab serum components bound to the epibionts even in the presence of sugars. This study represents the first immunological assessment of a deep-sea vent endemic crab and demonstrated the possibility of a non-lectin-mediated symbiont-host interaction. PMID:26212518

  18. Mercury accumulation in hydrothermal vent mollusks from the southern Tonga Arc, southwestern Pacific Ocean.

    PubMed

    Lee, Seyong; Kim, Se-Joo; Ju, Se-Jong; Pak, Sang-Joon; Son, Seung-Kyu; Yang, Jisook; Han, Seunghee

    2015-05-01

    We provide the mercury (Hg) and monomethylmercury (MMHg) levels of the plume water, sulfide ore, sediment, and mollusks located at the hydrothermal vent fields of the southern Tonga Arc, where active volcanism and intense seismic activity occur frequently. Our objectives were: (1) to address the potential release of Hg from hydrothermal fluids and (2) to examine the distribution of Hg and MMHg levels in hydrothermal mollusks (mussels and snails) harboring chemotrophic bacteria. While high concentrations of Hg in the sediment and Hg, As, and Sb in the sulfide ore indicates that their source is likely hydrothermal fluids, the MMHg concentration in the sediment was orders of magnitude lower than the Hg (<0.001%). It suggests that Hg methylation may have not been favorable in the vent field sediment. In addition, Hg concentrations in the mollusks were much higher (10-100 times) than in other hydrothermal vent environments, indicating that organisms located at the Tonga Arc are exposed to exceedingly high Hg levels. While Hg concentration was higher in the gills and digestive glands than in the mantles and residues of snails and mussels, the MMHg concentrations in the gills and digestive glands were orders of magnitude lower (0.004-0.04%) than Hg concentrations. In summary, our results suggest that the release of Hg from the hydrothermal vent fields of the Tonga Arc and subsequent bioaccumulation are substantial, but not for MMHg. PMID:25748345

  19. Edge states in confined active fluids

    NASA Astrophysics Data System (ADS)

    Souslov, Anton; Vitelli, Vincenzo

    Recently, topologically protected edge modes have been proposed and realized in both mechanical and acoustic metamaterials. In one class of such metamaterials, Time-Reversal Symmetry is broken, and, to achieve this TRS breaking in mechanical and acoustic systems, an external energy input must be used. For example, motors provide a driving force that uses energy and, thus, explicitly break TRS. As a result, motors have been used as an essential component in the design of topological metamaterials. By contrast, we explore the design of topological metamaterials that use a class of far-from-equilibrium liquids, called polar active liquids, that spontaneously break TRS. We thus envision the confinement of a polar active liquid to a prescribed geometry in order to realize topological order with broken time-reversal symmetry. We address the design of the requisite geometries, for example a regular honeycomb lattice composed of annular channels, in which the active liquid may be confined. We also consider the physical character of the active liquid that, when introduced into the prescribed geometry, will spontaneously form the flow pattern of a metamaterial with topologically protected edge states. Finally, we comment on potential experimental realizations of such metamaterials.

  20. Active Learning in Fluid Mechanics: Youtube Tube Flow and Puzzling Fluids Questions

    ERIC Educational Resources Information Center

    Hrenya, Christine M.

    2011-01-01

    Active-learning exercises appropriate for a course in undergraduate fluid mechanics are presented. The first exercise involves an experiment in gravity-driven tube flow, with small groups of students partaking in a contest to predict the experimental flow rates using the mechanical energy balance. The second exercise takes the form of an…

  1. Submarine venting of magmatic volatiles in the Eastern Manus Basin, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Seewald, Jeffrey S.; Reeves, Eoghan P.; Bach, Wolfgang; Saccocia, Peter J.; Craddock, Paul R.; Shanks, Wayne C.; Sylva, Sean P.; Pichler, Thomas; Rosner, Martin; Walsh, Emily

    2015-08-01

    The SuSu Knolls and DESMOS hydrothermal fields are located in the back-arc extensional transform zone of the Eastern Manus Basin. In 2006, highly acidic and ΣSO4-rich vent fluids were collected at both sites and analyzed for the chemical and isotopic composition of major and trace species. Fluids exiting the seafloor have measured temperatures from 48 to 215 °C and are milky white in appearance due to precipitation of elemental S0. Vent fluid concentrations of Na, K, and Mg are depleted by as much as 30% relative to seawater, but have the same relative abundance. In contrast, the fluids are highly enriched in dissolved ΣCO2, Cl, SiO2(aq), Fe, and Al relative to seawater. Measured pH (25 °C) ranged from 0.95 to 1.87 and aqueous ΣSO4 ranged from 35 to 135 mmol/kg. The chemical and isotopic composition points to formation via subsurface mixing of seawater with a Na-, K-, Mg-, and Ca-free, volatile-rich magmatic fluid exsolved from subsurface magma bodies during a process analogous to subaerial fumarole discharge. Estimates of the magmatic end-member composition indicate a fluid phase where H2O > SO2 > CO2 ≈ Cl > F. The hydrogen and oxygen isotopic composition of H2O and carbon isotopic composition of ΣCO2 in the vent fluids strongly suggest a contribution of slab-derived H2O and CO2 to melts generated in the mantle beneath the Eastern Manus volcanic zone. Abundant magmatically-derived SO2 undergoes disproportionation during cooling in upflow zones and contributes abundant acidity, SO42-, and S0 to the venting fluids. Interaction of these highly acidic fluids with highly altered mineral assemblages in the upflow zone are responsible for extensive aqueous mobilization of SiO2(aq), Fe, and Al. Temporal variability in the speciation and abundance of aqueous S species between 1995 and 2006 at the DESMOS vent field suggests an increase in the relative abundance of SO2 in the magmatic end-member that has mixed with seawater in the subsurface. Results of this study

  2. Evaluation of cellulolytic activity in insect digestive fluids.

    PubMed

    Su, L-J; Zhang, H-F; Yin, X-M; Chen, M; Wang, F-Q; Xie, H; Zhang, G-Z; Song, A-D

    2013-01-01

    Efficient and low-cost cellulolytic enzymes are urgently needed to degrade recalcitrant plant biomass during the industrial production of lignocellulosic biofuels. Here, the cellulolytic activities in the gut fluids of 54 insect species that belong to 7 different taxonomic orders were determined using 2 different substrates, carboxymethyl cellulose (CMC) (approximating endo-β-1,4-glucanase) and filter paper (FP) (total cellulolytic activities). The use of CMC as the substrate in the zymogram analysis resulted in the detection of distinct cellulolytic protein bands. The cellulolytic activities in the digestive system of all the collected samples were detected using cellulolytic activity analysis. The highest CMC gut fluid activities were found in Coleoptera and Orthoptera, while FP analysis indicated that higher gut fluid activities were found in several species of Coleoptera and Lepidoptera. In most cases, gut fluid activities were higher with CMC than with FP substrate, except for individual Lepidoptera species. Our data indicate that the origin of cellulolytic enzymes probably reflects the phylogenetic relationship and feeding strategies of different insects. PMID:23315870

  3. Superfluid-like dynamics in active vortex fluids

    NASA Astrophysics Data System (ADS)

    Slomka, Jonasz; Dunkel, Jorn

    Active biological fluids exhibit rich non-equilibrium dynamics and share striking similarities with quantum fluids, from vortex formation and magnetic ordering to superfluid-like behavior. Building on universality ideas, we have recently proposed a generalization of the Navier-Stokes equations that captures qualitatively the active bulk flow structures observed in bacterial suspensions. Here, we present new numerical simulations that explicitly account for boundary and shear effects. The theory successfully reproduces recent experimental observations of bacterial suspensions, including a superfluid-like regime of nearly vanishing shear viscosity. Our simulations further predict a geometry-induced 'quantization' of viscosity and the existence of excited states capable of performing mechanical work. It is plausible that these results generalize to a broad a class of fluids that are subject to an active scale selection mechanism.

  4. Synchronous droplets as a test bed for pulsatory active fluids

    NASA Astrophysics Data System (ADS)

    Katsikis, Georgios; Prakash, Manu

    2014-11-01

    Collective behavior in many-body systems has been studied extensively focusing on a wide range of interacting entities including: flocking animals, sedimenting particles and microfluidic droplets among others. Here, we propose an experimental platform to explore an oscillatory active fluid with synchronous ferrofluid droplets immersed in an immiscible carrier fluid in a Hele-Shaw configuration. The droplets are organized and actuated on a 2-D uniform grid through application of a precessive magnetic field. The state of our system is dependent on three parameters: the grid occupancy with fluid droplets, the grid geometry and the magnetic field. We study the long range orientational order of our system over a range of those parameters by tracking the motion of the droplets and analyzing the PIV data of the carrier fluid flow. Numerical simulations are juxtaposed with experimental data for prediction of the system's behavior.

  5. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... vent pipe or equivalent directly connected to the toilet drain within the distance allowed in § 3280... any other vent pipe. Vents for horizontal drains shall connect above the centerline of the drain... this section and as otherwise required by this standard. (b) Materials—(1) Pipe. Vent piping shall...

  6. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... for all changes in direction or size and where pipes are joined. The material and design of vent...) Size of vent piping—(1) Main vent. The drain piping for each toilet shall be vented by a 11/2 inch... toilet drain within the distance allowed in § 3280.611(c)(5), for 3-inch trap arms undiminished in...

  7. Phase separation and emergent structures in an active nematic fluid

    PubMed Central

    Putzig, Elias; Baskaran, Aparna

    2015-01-01

    We consider a phenomenological continuum theory for an active nematic fluid and show that there exists a universal, model independent instability which renders the homogeneous nematic state unstable to order fluctuations. Using numerical and analytic tools we show that, in the vicinity of a critical point, this instability leads to a phase separated state in which the ordered regions form bands in which the direction of nematic order is perpendicular to the direction of density gradient. We argue that the underlying mechanism that leads to this phase separation is a universal feature of active fluids of different symmetries. PMID:25375491

  8. Tracer motion in an active dumbbell fluid

    NASA Astrophysics Data System (ADS)

    Suma, Antonio; Cugliandolo, Leticia F.; Gonnella, Giuseppe

    2016-05-01

    The diffusion properties of spherical tracers coupled through a repulsive potential to a system of active dumbbells are analyzed. We model the dumbbells’ dynamics with Langevin equations and the activity with a self-propulsive force of constant magnitude directed along the main axis of the molecules. Two types of tracers are considered. Thermal tracers are coupled to the same bath as the dumbbells while athermal tracers are not; both interact repulsively with the dumbbells. We focus our attention on the intruders’ mean square displacement and how it compares to the one of the dumbbells. We show that the dynamics of thermal intruders, with mass similar to the one of the dumbbells, display the typical four time-lag regimes of the dumbbells’ mean square displacement. The thermal tracers’ late-time diffusion coefficient depends on their mass very weakly and it is close to the one of the dumbbells at low Péclet only. Athermal tracers only have ballistic and late-time diffusive regimes. The late time diffusion coefficients of athermal tracers and dumbbells have similar values at high Péclet number when their masses are of the same order, while at low Péclet number this coefficient gets close to the one of the dumbbells only when the tracers are several order of magnitude heavier than the dumbbells. We propose a generalization of the Enskog law for dilute hard disks, that describes the athermal tracers’ mean square displacement in the form of a scaling law in terms of their mass.

  9. Assessing the influence of physical, geochemical and biological factors on anaerobic microbial primary productivity within hydrothermal vent chimneys.

    PubMed

    Olins, H C; Rogers, D R; Frank, K L; Vidoudez, C; Girguis, P R

    2013-05-01

    Chemosynthetic primary production supports hydrothermal vent ecosystems, but the extent of that productivity and its governing factors have not been well constrained. To better understand anaerobic primary production within massive vent deposits, we conducted a series of incubations at 4, 25, 50 and 90 °C using aggregates recovered from hydrothermal vent structures. We documented in situ geochemistry, measured autochthonous organic carbon stable isotope ratios and assessed microbial community composition and functional gene abundances in three hydrothermal vent chimney structures from Middle Valley on the Juan de Fuca Ridge. Carbon fixation rates were greatest at lower temperatures and were comparable among chimneys. Stable isotope ratios of autochthonous organic carbon were consistent with the Calvin-Benson-Bassham cycle being the predominant mode of carbon fixation for all three chimneys. Chimneys exhibited marked differences in vent fluid geochemistry and microbial community composition, with structures being differentially dominated by gamma (γ) or epsilon (ε) proteobacteria. Similarly, qPCR analyses of functional genes representing different carbon fixation pathways showed striking differences in gene abundance among chimney structures. Carbon fixation rates showed no obvious correlation with observed in situ vent fluid geochemistry, community composition or functional gene abundance. Together, these data reveal that (i) net anaerobic carbon fixation rates among these chimneys are elevated at lower temperatures, (ii) clear differences in community composition and gene abundance exist among chimney structures, and (iii) tremendous spatial heterogeneity within these environments likely confounds efforts to relate the observed rates to in situ microbial and geochemical factors. We also posit that microbes typically thought to be mesophiles are likely active and growing at cooler temperatures, and that their activity at these temperatures comprises the

  10. Hydrothermal vents near a mantle hot spot: the Lucky Strike vent field at 37°N on the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Langmuir, C.; Humphris, S.; Fornari, D.; Van Dover, C.; Von Damm, K.; Tivey, M. K.; Colodner, D.; Charlou, J.-L.; Desonie, D.; Wilson, C.; Fouquet, Y.; Klinkhammer, G.; Bougault, H.

    1997-04-01

    The Lucky Strike hydrothermal field occurs in the summit basin of a large seamount that forms the shallow center of a 65 km long ridge segment near 37°N on the Mid-Atlantic Ridge. The depth and chemistry of the ridge segment are influenced by the Azores hot spot, and this hydrothermal field is the first Atlantic site found on crust that is dominated by a hot spot signature. Multiple hydrothermal vents occur over an area of at least 300 m by 700 m. Vent morphologies range from flanges and chimneys with temperatures of 200-212°C, to black smoker chimneys with temperatures up to 333°C. Cooler fluids from northern vents have higher chlorinities and lower gas volumes, while hotter, southern fluids have chlorinities 20% below seawater with higher gas volumes, suggesting phase separation has influenced their compositions. All gas volumes in fluids are higher than those at TAG and Snake Pit hydrothermal fields. Black smokers exhibit their typical mineralogy, except that barite is a major mineral, particularly at lower-temperature sites, which contrasts with previously investigated Atlantic sites. The fluid chemistry, distribution of the relict sulfide deposits on the seamount summit in the areas investigated using DSV Alvin, and contact relationships between active vent sites and surrounding basaltic and sulfide substrate suggest that the hydrothermal system has a long history and may have recently been rejuvenated. Fauna at the Lucky Strike vent sites are dominated by a new species of mussel, and include the first reported sea urchins. The Lucky Strike biological community differs considerably from other vent fauna at the species level and appears to be a new biogeographic province. The Lucky Strike field helps to constrain how variations in the basaltic substrate influence the composition of hydrothermal fluids and solids, because basalt compositions at Lucky Strike are 10-30 times enriched in incompatible elements compared to other Atlantic hydrothermal sites such as

  11. Examination of frit vent from Sixty-Watt Heat Source simulant fueled clad vent set

    SciTech Connect

    Ulrich, G.B.

    1995-11-01

    The flow rate and the metallurgical condition of a frit vent from a simulant-fueled clad vent set (CVS) that had been hot isostatically pressed (HIP) for the Sixty-Watt Heat Source program were evaluated. The flow rate form the defueled vent cup subassembly was reduced approximately 25% from the original flow rate. No obstructions were found to account for the reduced flow rate. Measurements indicate that the frit vent powder thickness was reduced about 30%. Most likely, the powder was compressed during the HIP operation, which increased the density of the powder layer and thus reduced the flow rate of the assembly. All other observed manufacturing attributes appeared to be normal, but the vent hole activation technique needs further refinement before it is used in applications requiring maximum CVS integrity.

  12. Hydrothermal Vents at 5000m on the Mid-Cayman Rise: The Deepest and Hottest Hydrothermal Systems Yet Discovered!

    NASA Astrophysics Data System (ADS)

    Murton, B. J.; Connelly, D. P.; Copley, J. T.; Stansfield, K. L.; Tyler, P. A.; Cruise Jc044 Sceintific Party

    2010-12-01

    This contribution describes the geological setting of hydrothermal activity within the Mid- Cayman Rise (MCR) using data acquired during cruise JC044 (MAR-APR 2010) from the deep-towed sidescan sonar TOBI, AUV Autosub6000 and the ROTV HyBIS. The 110 km-long Mid- Cayman Rise (MCR), located within Caribbean Sea, is the deepest spreading centre known, reaching over 6000m. Hence it poses an end-member of extreme depth for hydrothermal circulation. Accretion of new volcanic crust is focused within two ridge segments, to the north and south of a centrally located massif of peridotite and gabbro. Following earlier indications of hydrothermal plumes (German et al., in 2009), we discovered two high-temperature hydrothermal system: one at a depth of 5000m in the neovolcanic zone of the northern segment, and another at 2300m on the flanks of the MCR. These sites show contrasting styles of fluid venting, mineralisation, geological setting and host rock interaction. At 5000m-depth, the ultra-deep vent site forms the deepest hydrothermal system known. Venting is focused at the western side of a 100m diameter, 30m high mound, while inactive sulphides extend eastwards for at least 800m. Fluids discharge from clusters of chimneys whose location is related to basement faults. Changes in salinity in the venting fluids indicate discharge of a low salinity phase and a brine phase. At 500bar, this is definitive evidence for supercritical fluid emission. We also found the sulphide mineralization to be copper-rich, giving a characteristic green hue to many of the deposits, probably a result of the super-critical state of the vent fluids. A prominent axial volcanic ridge nearby indicates a robust magma supply to the northern MCR segment. Thus it is likely the ultra-deep vent site derives its thermal energy from magmatic sources, similar to those thought to underlie other slow-spreading ridge volcanic-hosted vent sites (e.g. Broken Spur: MAR). The shallower (2300m) MCR hydrothermal vent

  13. How many vent fields? New estimates of vent field populations on ocean ridges from precise mapping of hydrothermal discharge locations

    NASA Astrophysics Data System (ADS)

    Baker, Edward T.; Resing, Joseph A.; Haymon, Rachel M.; Tunnicliffe, Verena; Lavelle, J. William; Martinez, Fernando; Ferrini, Vicki; Walker, Sharon L.; Nakamura, Koichi

    2016-09-01

    Decades of exploration for venting sites along spreading ridge crests have produced global datasets that yield estimated mean site spacings of ∼ 12- 220 km. This conclusion demands that sites where hydrothermal fluid leaks from the seafloor are improbably rare along the 66 000 km global ridge system, despite the high bulk permeability of ridge crest axes. However, to date, exploration methods have neither reliably detected plumes from isolated low-temperature, particle-poor, diffuse sources, nor differentiated individual, closely spaced (clustered within a few kilometers) sites of any kind. Here we describe a much lower mean discharge spacing of 3-20 km, revealed by towing real-time oxidation-reduction-potential and optical sensors continuously along four fast- and intermediate-rate (>55 mm/yr) spreading ridge sections totaling 1470 km length. This closer spacing reflects both discovery of isolated sites discharging particle-poor plumes (25% of all sites) and improved discrimination (at a spatial resolution of ∼1 km) among clustered discrete and diffuse sources. Consequently, the number of active vent sites on fast- and intermediate-rate spreading ridges may be at least a factor of 3-6 higher than now presumed. This increase provides new quantitative constraints for models of seafloor processes such as dispersal of fauna among seafloor and crustal chemosynthetic habitats, biogeochemical impacts of diffuse venting, and spatial patterns of hydrothermal discharge.

  14. How many vent fields? New estimates of vent field populations on ocean ridges from precise mapping of hydrothermal discharge locations

    NASA Astrophysics Data System (ADS)

    Baker, Edward T.; Resing, Joseph A.; Haymon, Rachel M.; Tunnicliffe, Verena; Lavelle, J. William; Martinez, Fernando; Ferrini, Vicki; Walker, Sharon L.; Nakamura, Koichi

    2016-09-01

    Decades of exploration for venting sites along spreading ridge crests have produced global datasets that yield estimated mean site spacings of ∼ 12- 220 km. This conclusion demands that sites where hydrothermal fluid leaks from the seafloor are improbably rare along the 66 000 km global ridge system, despite the high bulk permeability of ridge crest axes. However, to date, exploration methods have neither reliably detected plumes from isolated low-temperature, particle-poor, diffuse sources, nor differentiated individual, closely spaced (clustered within a few kilometers) sites of any kind. Here we describe a much lower mean discharge spacing of 3-20 km, revealed by towing real-time oxidation-reduction-potential and optical sensors continuously along four fast- and intermediate-rate (>55 mm/yr) spreading ridge sections totaling 1470 km length. This closer spacing reflects both discovery of isolated sites discharging particle-poor plumes (25% of all sites) and improved discrimination (at a spatial resolution of ∼1 km) among clustered discrete and diffuse sources. Consequently, the number of active vent sites on fast- and intermediate-rate spreading ridges may be at least a factor of 3-6 higher than now presumed. This increase provides new quantitative constraints for models of seafloor processes such as dispersal of fauna among seafloor and crustal chemosynthetic habitats, biogeochemical impacts of diffuse venting, and spatial patterns of hydrothermal discharge.

  15. Investigations Into Tank Venting for Propellant Resupply

    NASA Technical Reports Server (NTRS)

    Hearn, H. C.; Harrison, Robert A. (Technical Monitor)

    2002-01-01

    Models and simulations have been developed and applied to the evaluation of propellant tank ullage venting, which is integral to one approach for propellant resupply. The analytical effort was instrumental in identifying issues associated with resupply objectives, and it was used to help develop an operational procedure to accomplish the desired propellant transfer for a particular storable bipropellant system. Work on the project was not completed, and several topics have been identified as requiring further study; these include the potential for liquid entrainment during the low-g and thermal/freezing effects in the vent line and orifice. Verification of the feasibility of this propellant venting and resupply approach still requires additional analyses as well as testing to investigate the fluid and thermodynamic phenomena involved.

  16. EVALUATION AND DEMONSTRATION OF THE CHEMICALLY ACTIVE FLUID BED

    EPA Science Inventory

    The report gives results of the operation of a 17-MW Chemically Active Fluid Bed (CAFB) demonstration unit, retrofitted to a natural gas boiler. The CAFB process gasifies high-sulfur, high-metals-content liquid and solid fuels. Residual oil, lignite, and bituminous coal were gasi...

  17. The Geologic Setting of Hydrothermal Vents at Mariana Arc Submarine Volcanoes: High-Resolution Bathymetry and ROV Observations

    NASA Astrophysics Data System (ADS)

    Chadwick, W. W.; Embley, R. W.; de Ronde, C. E.; Stern, R. J.; Hein, J.; Merle, S.; Ristau, S.

    2004-12-01

    Remotely operated vehicle (ROV) dives were made at 7 submarine volcanoes between 14-23° N in the Mariana Arc in April 2004 with the ROPOS ROV. Six of these volcanoes were known to be hydrothermally active from CTD data collected during a previous expedition in March 2003: NW Rota-1, E Diamante, NW Eifuku, Daikoku, Kasuga-2, and Maug, a partly submerged caldera. The physical setting of hydrothermal venting varies widely from volcano to volcano. High-resolution bathymetric surveys of the summits of NW Rota-1 and NW Eifuku volcanoes were conducted with an Imagenex scanning sonar mounted on ROPOS. Near bottom observations during ROPOS dives were recorded with digital video and a digital still camera and the dives were navigated acoustically from the R/V Thompson using an ultra-short baseline system. The mapping and dive observations reveal the following: (1) The summits of some volcanoes have pervasive diffuse venting (NW Rota-1, Daikoku, NW Eifuku) suggesting that hydrothermal fluids are able to circulate freely within a permeable edifice. At other volcanoes, the hydrothermal venting is more localized (Kasuga-2, Maug, E Diamante), suggesting more restricted permeability pathways. (2) Some volcanoes have both focused venting at depth and diffuse venting near the summit (E Diamante, NW Eifuku). Where the hydrothermal vents are focused, fluid flow appears to be localized by massive lava outcrops that form steep cliffs and ridges, or by subsurface structures such as dikes. High-temperature (240° C) venting was only observed at E Diamante volcano, where the "Black Forest" vent field is located on the side of a constructional cone near the middle of E Diamante caldera at a depth of 350 m. On the side of an adjacent shallower cone, the venting style changed to diffuse discharge and it extended all the way up into the photic zone (167 m). At NW Eifuku, the pattern of both deep-focused and shallow-diffuse venting is repeated. "Champagne vent" is located at 1607 m, ~150 m

  18. Three-dimensional structure of fluid conduits sustaining an active deep marine cold seep

    USGS Publications Warehouse

    Hornbach, M.J.; Ruppel, C.; Van Dover, C.L.

    2007-01-01

    Cold seeps in deep marine settings emit fluids to the overlying ocean and are often associated with such seafloor flux indicators as chemosynthetic biota, pockmarks, and authigenic carbonate rocks. Despite evidence for spatiotemporal variability in the rate, locus, and composition of cold seep fluid emissions, the shallow subseafloor plumbing systems have never been clearly imaged in three dimensions. Using a novel, high-resolution approach, we produce the first three-dimensional image of possible fluid conduits beneath a cold seep at a study site within the Blake Ridge gas hydrate province. Complex, dendritic features diverge upward toward the seafloor from feeder conduits at depth and could potentially draw flow laterally by up to 103 m from the known seafloor seep, a pattern similar to that suggested for some hydrothermal vents. The biodiversity, community structure, and succession dynamics of chemosynthetic communities at cold seeps may largely reflect these complexities of subseafloor fluid flow.

  19. First evidence for high-temperature off-axis venting of deep crustal/mantle heat: The Nibelungen hydrothermal field, southern Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Melchert, B.; Devey, C. W.; German, C. R.; Lackschewitz, K. S.; Seifert, R.; Walter, M.; Mertens, C.; Yoerger, D. R.; Baker, E. T.; Paulick, H.; Nakamura, K.

    2008-10-01

    During segment-scale studies of the southern Mid-Atlantic Ridge (MAR), 7-12° S, we found evidence in the water column for high-temperature hydrothermal activity, off-axis, east of Ascension Island. Extensive water column and seafloor work using both standard CTD and deep submergence AUV and ROV deployments led to the discovery and sampling of the "Drachenschlund" ("Dragon Throat") black smoker vent at 8°17.87' S/13°30.45' W in 2915 m water depth. The vent is flanked by several inactive chimney structures in a field we have named "Nibelungen". The site is located 6 km south of a non-transform offset between two adjacent 2nd-order ridge-segments and 9 km east of the presently-active, northward-propagating A2 ridge-segment, on a prominent outward-facing fault scarp. Both vent-fluid compositions and host-rock analyses show this site to be an ultramafic-hosted system, the first of its kind to be found on the southern MAR. The thermal output of this single vent, based on plume rise-height information, is estimated to be 60 ± 15 MW. This value is high for a single "black smoker" vent but small for an entire field. The tectonic setting and low He content of the vent fluids imply that high-temperature off-axis venting at "Drachenschlund" is driven not by magmatic processes, as at the majority of on-axis hydrothermal systems, but by residual heat "mined" from the deeper lithosphere. Whether this heat is being extracted from high-temperature mantle peridotites or deep crustal cumulates formed at the "duelling" non-transfrom offset is unclear, in either case the Drachenschlund vent provides the first direct observations of how cooling of deeper parts of the lithosphere, at least at slow-spreading ridges, may be occurring.

  20. Community Structure of Macrobiota and Environmental Parameters in Shallow Water Hydrothermal Vents off Kueishan Island, Taiwan.

    PubMed

    Chan, Benny Kwok Kan; Wang, Teng-Wei; Chen, Pin-Chen; Lin, Chia-Wei; Chan, Tin-Yam; Tsang, Ling Ming

    2016-01-01

    Hydrothermal vents represent a unique habitat in the marine ecosystem characterized with high water temperature and toxic acidic chemistry. Vents are distributed at depths ranging from a few meters to several thousand meters. The biological communities of shallow-water vents have, however, been insufficiently studied in most biogeographic areas. We attempted to characterize the macrofauna and macroflora community inhabiting the shallow-water vents off Kueishan Island, Taiwan, to identify the main abiotic factors shaping the community structure and the species distribution. We determined that positively buoyant vent fluid exhibits a more pronounced negative impact to species on the surface water than on the bottom layer. Species richness increased with horizontal distance from the vent, and continuing for a distance of 2000 m, indicating that the vent fluid may exert a negative impact over several kilometers. The community structure off Kueishan Island displayed numerous transitions along the horizontal gradient, which were broadly congruent with changes in environmental conditions. Combination of variation in Ca2+, Cl-, temperature, pH and depth were revealed to show the strongest correlation with the change in benthic community structure, suggesting multiple factors of vent fluid were influencing the associated fauna. Only the vent crabs of Kueishan Island may have an obligated relationship with vents and inhabit the vent mouths because other fauna found nearby are opportunistic taxa that are more tolerant to acidic and toxic environments. PMID:26849440

  1. Community Structure of Macrobiota and Environmental Parameters in Shallow Water Hydrothermal Vents off Kueishan Island, Taiwan

    PubMed Central

    Chan, Benny Kwok Kan; Wang, Teng-Wei; Chen, Pin-Chen; Lin, Chia-Wei; Chan, Tin-Yam; Tsang, Ling Ming

    2016-01-01

    Hydrothermal vents represent a unique habitat in the marine ecosystem characterized with high water temperature and toxic acidic chemistry. Vents are distributed at depths ranging from a few meters to several thousand meters. The biological communities of shallow-water vents have, however, been insufficiently studied in most biogeographic areas. We attempted to characterize the macrofauna and macroflora community inhabiting the shallow-water vents off Kueishan Island, Taiwan, to identify the main abiotic factors shaping the community structure and the species distribution. We determined that positively buoyant vent fluid exhibits a more pronounced negative impact to species on the surface water than on the bottom layer. Species richness increased with horizontal distance from the vent, and continuing for a distance of 2000 m, indicating that the vent fluid may exert a negative impact over several kilometers. The community structure off Kueishan Island displayed numerous transitions along the horizontal gradient, which were broadly congruent with changes in environmental conditions. Combination of variation in Ca2+, Cl-, temperature, pH and depth were revealed to show the strongest correlation with the change in benthic community structure, suggesting multiple factors of vent fluid were influencing the associated fauna. Only the vent crabs of Kueishan Island may have an obligated relationship with vents and inhabit the vent mouths because other fauna found nearby are opportunistic taxa that are more tolerant to acidic and toxic environments. PMID:26849440

  2. Microbial colonization of post eruptive vents on the EPR at 9N

    NASA Astrophysics Data System (ADS)

    Vetriani, C.

    2008-12-01

    The overarching goal of this project is to understand the role of microbial colonists at newly formed vents as "mediators" in the transfer of energy from the geothermal source to the higher trophic levels, and their role in altering fluid chemistry and in "conditioning" the vent environment for metazoans to settle. Following the 2005-06 volcanic eruption along the East Pacific Rise (EPR) ridge crest between 9°N and 9°N, we had several opportunities to investigate the microbial colonization of the post-eruptive vents: in 2006 (about six months after the eruption), in January 2007 (one year after the eruption), and in December 2007/January 2008 (two years after the eruption). In order to investigate microbial colonization, we designed and deployed several experimental microbial colonizers on active diffuse flow vents characterized by different temperatures (approximate range 20-60°C) chemical (different redox conditions), and biological (e.g., presence or absence of metazoan colonists) regimes. Analyses of the 16S rRNA and fuctional gene transcripts from the colonizing communities indicated that Epsilonproteobacteria represented the dominant and active fraction of the chemosynthetic early microbial colonists, and that they expressed in-situ the genes involved in carbon dioxide fixation and nitrate respiration. However, data from our semi quantitative culture experiments indicated that Epsilonproteobacteria were not the only microorganisms that attached to basalts or to the experimental colonizers during the early phases of colonization. Sulfur dependent, chemosynthetic members of the Gamma- and Alphaproteobacteria were isolated from up to 10-5 dilutions of original samples along with heterotrophic Gammaproteobacteria capable of growth on n-alkanes as their sole carbon source. We propose a model that links the chemistry of hydrothermal fluids to the colonization of newly formed vents and suggests a role for chemosynthetic and heterotrophic bacteria in the

  3. Parachute having improved vent line stacking

    NASA Technical Reports Server (NTRS)

    Hengel, John E.

    1994-01-01

    A parachute having an improved vent line stacking wherein the parachute is provided with a canopy having a central vent opening and a vent band secured to the canopy around the periphery of the vent opening, with a plurality of vent lines each lying on a diameter of the vent opening and having its ends secured to the vent band on opposite sides of the vent opening is described. The vent lines are sewed to the vent band in an order such that the end of a first vent line is sewed to the vent band at a starting point with the end of a second vent band then being sewed to the vent band adjacent to and counterclockwise from the first band. A third vent band is sewed to the vent band adjacent to and clockwise from the first band, with a fourth vent band being sewed to the vent band adjacent to and counterclockwise from the second vent band. It can be seen that, if the vent lines are numbered in the order of being sewed to the vent band, the odd numbered vent lines will run consecutively in a clockwise direction and the even numbered lines will run consecutively in a counterclockwise direction from the starting point. With this order of assembly, each and every vent line will be separated from adjacent vent lines by no more than one vent line in the center of the vent opening where the vent lines cross.

  4. Assessing Microbial Activity in Marcellus Shale Hydraulic Fracturing Fluids

    NASA Astrophysics Data System (ADS)

    Wishart, J. R.; Morono, Y.; Itoh, M.; Ijiri, A.; Hoshino, T.; Inagaki, F.; Verba, C.; Torres, M. E.; Colwell, F. S.

    2014-12-01

    Hydraulic fracturing (HF) produces millions of gallons of waste fluid which contains a microbial community adapted to harsh conditions such as high temperatures, high salinities and the presence of heavy metals and radionuclides. Here we present evidence for microbial activity in HF production fluids. Fluids collected from a Marcellus shale HF well were supplemented with 13C-labeled carbon sources and 15N-labeled ammonium at 25°C under aerobic or anaerobic conditions. Samples were analyzed for 13C and 15N incorporation at sub-micrometer scale by ion imaging with the JAMSTEC NanoSIMS to determine percent carbon and nitrogen assimilation in individual cells. Headspace CO2 and CH4 were analyzed for 13C enrichment using irm-GC/MS. At 32 days incubation carbon assimilation was observed in samples containing 1 mM 13C-labeled glucose under aerobic and anaerobic conditions with a maximum of 10.4 and 6.5% total carbon, respectively. Nitrogen assimilation of 15N ammonium observed in these samples were 0.3 and 0.8% of total nitrogen, respectively. Head space gas analysis showed 13C enrichment in CH4 in anaerobic samples incubated with 1mM 13C-labeled bicarbonate (2227 ‰) or methanol (98943 ‰). Lesser 13C enrichment of CO2 was observed in anaerobic samples containing 1 mM 13C-labeled acetate (13.7 ‰), methanol (29.9 ‰) or glucose (85.4 ‰). These results indicate metabolic activity and diversity in microbial communities present in HF flowback fluids. The assimilation of 13C-labeled glucose demonstrates the production of biomass, a critical part of cell replication. The production of 13CO2 and 13CH4 demonstrate microbial metabolism in the forms of respiration and methanogenesis, respectively. Methanogenesis additionally indicates the presence of an active archaeal community. This research shows that HF production fluid chemistry does not entirely inhibit microbial activity or growth and encourages further research regarding biogeochemical processes occurring in

  5. Activity of antioxidant enzymes in response to atmospheric pressure induced physiological stress in deep-sea hydrothermal vent mussel Bathymodiolus azoricus.

    PubMed

    Martins, Inês; Romão, Célia V; Goulart, Joana; Cerqueira, Teresa; Santos, Ricardo S; Bettencourt, Raul

    2016-03-01

    Deep sea hydrothermal Bathymodiolus azoricus mussels from Portuguese EEZ Menez Gwen hydrothermal field possess the remarkable ability to overcome decompression and survive successfully at atmospheric pressure conditions. We investigated the potential use of antioxidant defense enzymes in mussel B. azoricus as biomarkers of oxidative stress induced by long term acclimatization to atmospheric pressure conditions. Mussels collected at Menez Gwen hydrothermal field were acclimatized for two weeks in three distinct conditions suitable of promoting physiological stress, (i) in plain seawater for concomitant endosymbiont bacteria loss, (ii) in plain seawater under metal iron exposure, (iii) constant bubbling methane and pumped sulfide for endosymbiont bacteria survival. The enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and iron storage proteins in addition to electrophoretic profiles were examined in vent mussel gills and digestive gland. Gills showed approximately 3 times more SOD specific activity than digestive glands. On the other hand, digestive glands showed approximately 6 times more CAT specific activity than gills. Iron storage proteins were identified in gill extracts from all experimental conditions mussels. However, in digestive gland extracts only fresh collected mussels and after 2 weeks in FeSO4 showed the presence of iron storage proteins. The differences between SOD, CAT specific activities and the presence of iron storage proteins in the examined tissues reflect dissimilar metabolic and antioxidant activities, as a result of tissue specificities and acclimatization conditions influences on the organism. PMID:26790096

  6. The Evaluation of Antibacterial, Antifungal and Antioxidant Activity of Methanolic Extract of Mindium Laevigatum (Vent.) Rech. F., From Central Part of Iran

    PubMed Central

    Modaressi, Masoud; Shahsavari, Roia; Ahmadi, Farhad; Rahimi-Nasrabadi, Mehdi; Abiri, Ramin; Mikaeli, Ali; Batoli, Hossein

    2013-01-01

    Background Mindium laevigatum (Vent.) Rech. F. plant grows in central part of Iran. And used by local people as medical plant. Objectives The purpose of this study was to investigate the in vitro antibacterial, antifungal and antioxidant activities of the methanolic extracts of aerial and flower parts of plant. Materials and Methods The leaves and stem and flower of bark from M. laevigatum were separately collected, air-dried and powdered. Then the plant species extracts were prepared with methanol, water 80:20 and two polar and non-polar subfractions were realized. The antioxidant activity was evaluated by scavenging the radicals 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH), β-Carotene linoleic acid assay and reducing power methods. The antifungal and antibacterial evaluation was performed by disc diffusion and minimum inhibitory concentration methods. Results The total phenolic analysis of subfractions found 182 ± 4.2 µg.gr-1 for polar and 158 ± 3.9 µg.gr-1 for non-polar extracts. The antifungal activity of the extracts against the various fungal varied from 14.0 to 34 mm. MIC values from 50 to 400 µg.mL-1 were satisfactory when compared with other plant products. The antibacterial results revealed that the subfraction extracts are mostly effective against Staphylococcus aureus. The antioxidant results showed polar subfraction has more activity against non-polar subfraction. Conclusion These findings demonstrated that the extract of Mindium laevigatum has remarkable in vitro antifungal and antioxidant activity. PMID:24624184

  7. Magnetorheological effect in a suspension with an active carrier fluid

    SciTech Connect

    Kashevskii, B.E.; Kordonskii, V.I.; Prokhorov, I.V.

    1988-07-01

    The main quantitative laws governing the magnetorheological effect in a magnetorheological suspension with an active carrier liquid were established. The family of flow curves obtained for several samples of suspensions of one type of nonmagnetic particle was analyzed. Particles were suspended in a magnetic fluid of the magnetite-kerosite type. The main goal was to establish the law governing rheological similarity by generalizing experimental data with a universal relation while employing a small amount of initial data on the system. The data included the law of magnetization of the magnetic carrier fluid, the law of change in its viscosity in the field, and the law of change in the viscosity of the magnetorheological suspension/active carrier liquid system with an increase in the concentration of nonmagnetic particles in a zero field.

  8. Fluid management in space construction

    NASA Technical Reports Server (NTRS)

    Snyder, Howard

    1989-01-01

    The low-g fluids management group with the Center for Space Construction is engaged in active research on the following topics: gauging; venting; controlling contamination; sloshing; transfer; acquisition; and two-phase flow. Our basic understanding of each of these topics at present is inadequate to design space structures optimally. A brief report is presented on each topic showing the present status, recent accomplishings by our group and our plans for future research. Reports are presented in graphic and outline form.

  9. Application of linear multivariate calibration techniques to identify the peaks responsible for the antioxidant activity of Satureja hortensis L. and Oliveria decumbens Vent. essential oils by gas chromatography-mass spectrometry.

    PubMed

    Samadi, Naser; Masoum, Saeed; Mehrara, Bahare; Hosseini, Hossein

    2015-09-15

    Satureja hortensis L. and Oliveria decumbens Vent. are known for their diverse effects in drug therapy and traditional medicine. One of the most interesting properties of their essential oils is good antioxidant activity. In this paper, essential oils of aerial parts of S. hortensis L. and O. decumbens Vent. from different regions were obtained by hydrodistillation and were analyzed by gas chromatography-mass spectrometry (GC-MS). Essential oils were tested for their free radical scavenging activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay to identify the peaks potentially responsible for the antioxidant activity from chromatographic fingerprints by numerous linear multivariate calibration techniques. Because of its simplicity and high repeatability, orthogonal projection to latent structures (OPLS) model had the best performance in indicating the potential antioxidant compounds in S. hortensis L. and O. decumbens Vent. essential oils. In this study, P-cymene, carvacrol and β-bisabolene for S. hortensis L. and P-cymene, Ç-terpinen, thymol, carvacrol, and 1,3-benzodioxole, 4-methoxy-6-(2-propenyl) for O. decumbens Vent. are suggested as the potentially antioxidant compounds. PMID:26262598

  10. Thermodynamic Vent System Test in a Low Earth Orbit Simulation

    NASA Technical Reports Server (NTRS)

    VanOverbeke, Thomas J.

    2004-01-01

    A thermodynamic vent system for a cryogenic nitrogen tank was tested in a vacuum chamber simulating oxygen storage in low earth orbit. The nitrogen tank was surrounded by a cryo-shroud at -40 F. The tank was insulated with two layers of multi-layer insulation. Heat transfer into cryogenic tanks causes phase change and increases tank pressure which must be controlled. A thermodynamic vent system was used to control pressure as the location of vapor is unknown in low gravity and direct venting would be wasteful. The thermodynamic vent system consists of a Joule-Thomson valve and heat exchanger installed on the inlet side of the tank mixer-pump. The combination is used to extract thermal energy from the tank fluid, reducing temperature and ullage pressure. The system was sized so that the tank mixer-pump operated a small fraction of the time to limit motor heating. Initially the mixer used sub-cooled liquid to cool the liquid-vapor interface inducing condensation and pressure reduction. Later, the thermodynamic vent system was used. Pressure cycles were performed until steady-state operation was demonstrated. Three test runs were conducted at tank fills of 97, 80, and 63 percent. Each test was begun with a boil-off test to determine heat transfer into the tank. The lower tank fills had time averaged vent rates very close to steady-state boil-off rates showing the thermodynamic vent system was nearly as efficient as direct venting in normal gravity.

  11. Coil spring venting arrangement

    DOEpatents

    McCugh, R.M.

    1975-10-21

    A simple venting device for trapped gas pockets in hydraulic systems is inserted through a small access passages, operated remotely, and removed completely. The device comprises a small diameter, closely wound coil spring which is pushed through a guide temporarily inserted in the access passage. The guide has a central passageway which directs the coil spring radially upward into the pocket, so that, with the guide properly positioned for depth and properly oriented, the coil spring can be pushed up into the top of the pocket to vent it. By positioning a seal around the free end of the guide, the spring and guide are removed and the passage is sealed.

  12. Spatial distribution, diversity and composition of bacterial communities in sub-seafloor fluids at a deep-sea hydrothermal field of the Suiyo Seamount

    NASA Astrophysics Data System (ADS)

    Kato, Shingo; Hara, Kurt; Kasai, Hiroko; Teramura, Takashi; Sunamura, Michinari; Ishibashi, Jun-ichiro; Kakegawa, Takeshi; Yamanaka, Toshiro; Kimura, Hiroyuki; Marumo, Katsumi; Urabe, Tetsuro; Yamagishi, Akihiko

    2009-10-01

    Spatial distribution, diversity, and composition of bacterial communities within the shallow sub-seafloor at the deep-sea hydrothermal field of the Suiyo Seamount, Izu-Bonin Arc, Western Pacific Ocean, were investigated. Fluids were sampled from four boreholes in this area. Each borehole was located near or away from active vents, the distance ranging 2-40 m from active vents. In addition, fluids discharging from a natural vent and ambient seawater were sampled in this area. We extracted DNA from each sample, amplified bacterial 16S rRNA genes by PCR, cloned the PCR products and sequenced. The total number of clones analyzed was 348. Most of the detected phylotypes were affiliated with the phylum Proteobacteria, of which the detection frequency in each clone library ranged from 84.6% to 100%. The bacterial community diversity and composition were different between hydrothermal fluids and seawater, between fluids from the boreholes and the vent, and even among fluids from each borehole. The relative abundances of the phylotypes related to Thiomicrospira, Methylobacterium and Sphingomonas were significantly different among fluids from each borehole. The phylotypes related to Thiomicrospira and Alcanivorax were detected in all of the boreholes and vent samples. Our findings provide insights into bacterial communities in the shallow sub-seafloor environments at active deep-sea hydrothermal vent fields.

  13. The mechanics of intermittent methane venting at South Hydrate Ridge inferred from 4D seismic surveying

    NASA Astrophysics Data System (ADS)

    Bangs, Nathan L. B.; Hornbach, Matthew J.; Berndt, Christian

    2011-10-01

    Sea floor methane vents and seeps direct methane generated by microbial and thermal decompositions of organic matter in sediment into the oceans and atmosphere. Methane vents contribute to ocean acidification, global warming, and providing a long-term (e.g. 500-4000 years; Powell et al., 1998) life-sustaining role for unique chemosynthetic biological communities. However, the role methane vents play in both climate change and chemosynthetic life remains controversial primarily because we do not understand long-term methane flux and the mechanisms that control it ( Milkov et al., 2004; Shakhova et al., 2010; Van Dover, 2000). Vents are inherently dynamic and flux varies greatly in magnitude and even flow direction over short time periods (hours-to-days), often tidally-driven ( Boles et al., 2001; Tryon et al., 1999). But, it remains unclear if flux changes at vents occur on the order of the life-cycle of various species within chemosynthetic communities (months, years, to decades Leifer et al., 2004; Torres et al., 2001) and thus impacts their sustainability. Here, using repeat high-resolution 3D seismic surveys acquired in 2000 and 2008, we demonstrate in 4D that Hydrate Ridge, a vent off the Oregon coast has undergone significant reduction of methane flow and complete interruption in just the past few years. In the subsurface, below a frozen methane hydrate layer, free gas appears to be migrating toward the vent, but currently there is accumulating gas that is unable to reach the seafloor through the gas hydrate layer. At the same time, abundant authigenic carbonates show that the system has been active for several thousands of years. Thus, it is likely that activity has been intermittent because gas hydrates clog the vertical flow pathways feeding the seafloor vent. Back pressure building in the subsurface will ultimately trigger hydrofracturing that will revive fluid-flow to the seafloor. The nature of this mechanism implies regular recurring flow interruptions

  14. Vent Relief Valve Test

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Shown is the disassembly, examination, refurbishment and testing of the LH2 ( liquid hydrogen) and LOX (liquid oxygen) vent and relief valves for the S-IVB-211 engine stage in support of the Constellation/Ares project. This image is extracted from high definition video and is the highest resolution available.

  15. Pressure is not a state function for generic active fluids

    NASA Astrophysics Data System (ADS)

    Solon, A. P.; Fily, Y.; Baskaran, A.; Cates, M. E.; Kafri, Y.; Kardar, M.; Tailleur, J.

    2015-08-01

    Pressure is the mechanical force per unit area that a confined system exerts on its container. In thermal equilibrium, it depends only on bulk properties--such as density and temperature--through an equation of state. Here we show that in a wide class of active systems the pressure depends on the precise interactions between the active particles and the confining walls. In general, therefore, active fluids have no equation of state. Their mechanical pressure exhibits anomalous properties that defy the familiar thermodynamic reasoning that holds in equilibrium. The pressure remains a function of state, however, in some specific and well-studied active models that tacitly restrict the character of the particle-wall and/or particle-particle interactions.

  16. Evidence for Hydrothermal Vents as "Biogeobatteries" (Invited)

    NASA Astrophysics Data System (ADS)

    Nielsen, M. E.; Girguis, P. R.

    2010-12-01

    Hydrothermal vents are unique systems that play an important role in oceanic biogeochemical cycles. As chemically reduced hydrothermal fluid mixes with cold oxic seawater, minerals precipitate out of solution resulting in chimney structures composed largely of metal sulfides and anhydrite. Pyrite, which is a natural semi-conductor, is the primary sulfide mineral, but other minerals within chimneys are also conductive (e.g. chalcopyrite, wurtzite, and some iron oxides). Sulfide chimneys are also known to host an extensive endolithic microbial community. Accordingly, submarine hydrothermal systems appear to be examples of biogeobatteries, wherein conductive mineral assemblages span naturally occuring redox gradients and enable anaerobic microbes to access oxygen as an oxidant via extracellular electron transfer (or EET). To test this hypothesis, we ran a series of electrochemical laboratory experiments in which pyrite was used as an anode (in a vessel flushed with hydrothermal-like fluid). When placed in continuity with a carbon fiber cathode, pyrite was found to accept and conduct electrons from both abiotic and biological processes (microbial EET). Specifically, electrical current increased 4-fold (5 nA/m2 to 20 nA/m2) in response to inoculation with a slurry prepared from a hydrothermal vent sample. Inspection of the pyrite anode with SEM revealed ubiquitous coverage by microbes. DNA was extracted from the anodes and the inoculum, and was subjected to pyrosequencing to examine prokaryotic diversity. These data suggest that key microbial phylotypes were enriched upon the pyrite, implicating them in EET. In addition, we deployed an in situ experiment based on microbial fuel cell architecture with a graphite anode inserted into a vent wall coupled to a carbon fiber cathode outside the vent. We observed current production over the course of one year, implying microbial EET in situ. Via pyrosequencing, we observed that the microbial community on the anode was

  17. Microbial diversity in deep-sea sediments from the Menez Gwen hydrothermal vent system of the Mid-Atlantic Ridge.

    PubMed

    Cerqueira, Teresa; Pinho, Diogo; Egas, Conceição; Froufe, Hugo; Altermark, Bjørn; Candeias, Carla; Santos, Ricardo S; Bettencourt, Raul

    2015-12-01

    Deep-sea hydrothermal sediments are known to support remarkably diverse microbial consortia. Cultureindependent sequence-based technologies have extensively been used to disclose the associated microbial diversity as most of the microorganisms inhabiting these ecosystems remain uncultured. Here we provide the first description of the microbial community diversity found on sediments from Menez Gwen vent system. We compared hydrothermally influenced sediments, retrieved from an active vent chimney at 812 m depth, with non-hydrothermally influenced sediments, from a 1400 m depth bathyal plain. Considering the enriched methane and sulfur composition of Menez Gwen vent fluids, and the sediment physicochemical properties in each sampled area, we hypothesized that the site-associated microbes would be different. To address this question, taxonomic profiles of bacterial, archaeal and micro-eukaryotic representatives were studied by rRNA gene tag pyrosequencing. Communities were shown to be significantly different and segregated by sediment geographical area. Specific mesophilic, thermophilic and hyperthermophilic archaeal (e.g., Archaeoglobus, ANME-1) and bacterial (e.g., Caldithrix, Thermodesulfobacteria) taxa were highly abundant near the vent chimney. In contrast, bathyal-associated members affiliated to more ubiquitous phylogroups from deep-ocean sediments (e.g., Thaumarchaeota MGI, Gamma- and Alphaproteobacteria). This study provides a broader picture of the biological diversity and microbial biogeography, and represents a preliminary approach to the microbial ecology associated with the deep-sea sediments from the Menez Gwen hydrothermal vent field. PMID:26375668

  18. Angiogenic, mitogenic, and chemotactic activity in human follicular fluid (HFF)

    SciTech Connect

    Bryant, S.M.; Frederick, J.L.; Gale, J.A.; Campeau, J.D.; diZerega, G.S.

    1986-03-01

    The capacity of human follicular fluid to induce neovascularization was investigated. Three parameters were employed to assess the extent of angiogenic activity: (1) new vessel formation on the chick chorioallantoic membrane (CAM); (2) mitogenesis and (3) chemotaxis of bovine aortic endothelial cells. HFF resuspended in hydron induced new blood vessel formation on the CAM, as manifested by a spoke-wheel pattern of vessels radiating from the locus of application after two to six days. Endothelial cells cultured with a 1:10 dilution of HFF for two days demonstrated an enhanced incorporation of /sup 3/H-thymidine into acid-precipitable material when compared to control cells. The ratio of counts-per-minute for HFF stimulated cells versus control cells was 3.02 +/- 0.53 (anti S.E.M., n = 5). Endothelial cells also exhibited a directional migration towards HFF through a polycarbonate membrane with 8..mu..m pores. The ratio of the number of cells migrating completely through the filter towards a 1:10 dilution of HFF compared to those migrating towards medium alone was 5.61 +/- 0.61 (anti +/- S.E.M., n = 3). Human serum at an equivalent protein concentration as HFF demonstrated no activity in the CAM, mitogenic, and chemotaxis assays. These results demonstrate specific angiogenic, mitogenic and chemotactic activity in human follicular fluid.

  19. Vigorous venting and biology at Pito Seamount, Easter microplate

    NASA Astrophysics Data System (ADS)

    Naar, D. F.; Hekinian, R.; Segonzac, M.; Francheteau, J.; Armijo, R.; Cogne, J.-P.; Constantin, M.; Girardeau, J.; Hey, R. N.; Searle, R. C.

    A Nautile submersible investigation of Pito Seamount documents vigorous hydrothermal venting at 23°19.65'S, 111°38.41'W and at a depth of 2270 m. The data indicate the volcano is young and recently active, as predicted from analyses of SeaMARC II side-scan and swath bathymetry, and geophysical data. Pito Seamount lies near Pito Deep (5980 m), which marks the tip of the northwestward propagating East rift of the Easter microplate. Bathymetry surrounding Pito Seamount consists of a series of ridges and valleys with relief up to ˜4 km. The 4-km submersible-transect to the summit of Pito Seamount crossed areas of very glassy basalt with little or no sediment cover, suggesting the lava flows are very young. Most of the lava samples from Pito Seamount are depleted normal MORB (mid-ocean ridge basalt). Lava samples associated with active and dead hydrothermal vents consist of phyric and aphyric transitional and enriched MORB. Sulfides consist primarily of sphalerite and pyrite, with traces of chalcopyrite. The active hydrothermal chimney on Pito Seamount has a small, undiversified biological community similar to northern East Pacific Rise vent sites (alvinellid worms, bythograeid crabs and bythitid fishes) and western Pacific back-arc basin sites (alvinocaridid shrimps). No vestimentiferan worms were observed. Previous geophysical data, and new geochemical data and visual observations, suggest that the vigorous black smoker is a result of deep, extensive crosscutting faults formed by extensive tectonic thinning of Pito Deep, and a very robust magmatic supply being supplied from upwelling asthenosphere. Although no biological or vent fluid samples were obtained, geological and biological observations, such as the large number of inactive chimneys, old hydrothermal deposits, and starfish, as well as the occurrence of dead mollusks (gastropod and mussels), suggest a recent waning of hydrothermal activity near the summit. The speculative interpretation that Pito Seamount

  20. D0 Vent Stacks

    SciTech Connect

    Fuerst, J.D.; /Fermilab

    1988-01-22

    There are two nitrogen/argon exhaust headers in the D0 cryogenic piping system, one for the liquid argon dewar and another for the three argon calorimeters. These headers serve two functions, venting both nitrogen exhaust from the cooling loops and cold argon gas should any argon vessel blow a relief. These headers are vacuum jacketed until they exit the building. At that point, uninsulated exhaust stacks direct the flow into the atmosphere. This note deals with the these stacks.

  1. The Origin of Life in Alkaline Hydrothermal Vents.

    PubMed

    Sojo, Victor; Herschy, Barry; Whicher, Alexandra; Camprubí, Eloi; Lane, Nick

    2016-02-01

    Over the last 70 years, prebiotic chemists have been very successful in synthesizing the molecules of life, from amino acids to nucleotides. Yet there is strikingly little resemblance between much of this chemistry and the metabolic pathways of cells, in terms of substrates, catalysts, and synthetic pathways. In contrast, alkaline hydrothermal vents offer conditions similar to those harnessed by modern autotrophs, but there has been limited experimental evidence that such conditions could drive prebiotic chemistry. In the Hadean, in the absence of oxygen, alkaline vents are proposed to have acted as electrochemical flow reactors, in which alkaline fluids saturated in H2 mixed with relatively acidic ocean waters rich in CO2, through a labyrinth of interconnected micropores with thin inorganic walls containing catalytic Fe(Ni)S minerals. The difference in pH across these thin barriers produced natural proton gradients with equivalent magnitude and polarity to the proton-motive force required for carbon fixation in extant bacteria and archaea. How such gradients could have powered carbon reduction or energy flux before the advent of organic protocells with genes and proteins is unknown. Work over the last decade suggests several possible hypotheses that are currently being tested in laboratory experiments, field observations, and phylogenetic reconstructions of ancestral metabolism. We analyze the perplexing differences in carbon and energy metabolism in methanogenic archaea and acetogenic bacteria to propose a possible ancestral mechanism of CO2 reduction in alkaline hydrothermal vents. Based on this mechanism, we show that the evolution of active ion pumping could have driven the deep divergence of bacteria and archaea. PMID:26841066

  2. 3D structure and formation of hydrothermal vent complexes in the Møre Basin

    NASA Astrophysics Data System (ADS)

    Kjoberg, Sigurd; Schmiedel, Tobias; Planke, Sverre; Svensen, Henrik H.; Galland, Oliver; Jerram, Dougal A.

    2016-04-01

    The mid-Norwegian Møre margin is regarded as a type example of a volcanic rifted margin, with its formation usually related to the influence of the Icelandic plume activity. The area is characterized by the presence of voluminous basaltic complexes such as extrusive lava sequences, intrusive sills and dikes, and hydrothermal vent complexes within the Møre Basin. Emplacement of hydrothermal vent complexes is accommodated by deformation of the host rock. The edges of igneous intrusions mobilize fluids by heat transfer into the sedimentary host rock (aureoles). Fluid expansion may lead to formation of piercing structures due to upward fluid migration. Hydrothermal vent complexes induce bending of overlying strata, leading to the formation of dome structures at the paleo-surface. These dome structures are important as they indicate the accommodation created for the intrusions by deformation of the upper layers of the stratigraphy, and may form important structures in many volcanic margins. Both the morphological characteristics of the upper part and the underlying feeder-structure (conduit-zone) can be imaged and studied on 3D seismic data. Seismic data from the Tulipan prospect located in the western part of the Møre Basin have been used in this study. The investigation focusses on (1) the vent complex geometries, (2) the induced surface deformation patterns, (3) the relation to the intrusions (heat source), as well as (4) the emplacement depth of the hydrothermal vent complexes. We approach this by doing a detailed 3D seismic interpretation of the Tulipan seismic data cube. The complexes formed during the initial Eocene, and are believed to be a key factor behind the rapid warming event called the Paleocene-Eocene thermal maximum (PETM). The newly derived understanding of age, eruptive deposits, and formation of hydrothermal vent complexes in the Møre Basin enables us to contribute to the general understanding of the igneous plumbing system in volcanic basins and

  3. Energy and Carbon Flow: Comparing ultramafic- and basalt-hosted vents

    NASA Astrophysics Data System (ADS)

    Perner, M.; Bach, W.; Seifert, R.; Strauss, H.; Laroche, J.

    2010-12-01

    -hosted vents or that elevated sulfide consumption rates and biomass syntheses are significantly elevated in emissions from basalt-hosted over those from ultramafic-hosted vents. Yet, PCR-amplification from environmental samples demonstrated that the richness of uptake hydrogenases is significantly higher in the tested ultramafic-hosted (n = 4) than in the basalt-hosted (n = 3) vents. The sequence-based screening of metagenomic libraries constructed from basalt-hosted sites resulted in finding only 1 recognizable sqr-gene, but no genes encoding uptake hydrogenases or key enzymes of the CBB or rTCA cycles. Pyrosequencing of a diffuse fluid and a vent chimney (both basalt-hosted) has currently not lead to a great diversity of genes encoding enzymes associated with sulfur oxidizing mechanisms, but have displayed some genes encoding enzymes required for the maturation of uptake hydrogenases. Geochemical constraints appear to effect metabolic diversity and activity differently. [1] Amend, J., et al. (2010) AbSciCon. Texas, USA: p. 5134 [2] McCollom, T.M. (2007) Astrobiol. 7(6): p. 933-950

  4. Selective activation of functional suppressor cells by human seminal fluid.

    PubMed Central

    Witkin, S S

    1986-01-01

    The ability of seminal fluid (SF) to induce suppressor cell activity from peripheral blood mononuclear cells (PBMN) was examined. PBMN were incubated with SF for 48 h, washed to remove SF components, treated with mitomycin C (mit C) and co-cultured with Raji cells, a lymphoblastoid cell line. Raji cell proliferation was inhibited by SF-treated PBMN proportionally to SF concentration. SF (50-200 micrograms), mit C-treated Raji cells or mit C-treated PBMN pre-incubated with phytohaemagglutinin were without effect on Raji cell growth. Suppressor T lymphocytes generated by incubation of PBMN with concanavalin A inhibited Raji cells to the same extent as did SF-treated PBMN. All activity was lost following heating at 56 degrees C for 30 min; freezing and thawing reduced the ability of SF to induce suppression by 50%. Dialysis of SF or treatment with antibody to prostaglandin E2 led to a 50% reduction in suppression. PMID:2943541

  5. Spacecraft Compartment Venting

    NASA Technical Reports Server (NTRS)

    Scialdone, John J.

    1998-01-01

    At various time concerns have been expressed that rapid decompressions of compartments of gas pockets and thermal blankets during spacecraft launches may have caused pressure differentials across their walls sufficient to cause minor structural failures, separations of adhesively-joined parts, ballooning, and flapping of blankets. This paper presents a close form equation expressing the expected pressure differentials across the walls of a compartment as a function of the external to the volume pressure drops, the pressure at which the rates occur and the vent capability of the compartment. The pressure profiles measured inside the shrouds of several spacecraft propelled by several vehicles and some profiles obtained from ground vacuum systems have been included. The equation can be used to design the appropriate vent, which will preclude excessive pressure differentials. Precautions and needed approaches for the evaluations of the expected pressures have been indicated. Methods to make a rapid assessment of the response of the compartment to rapid external pressure drops have been discussed. These are based on the evaluation of the compartment vent flow conductance, the volume and the length of time during which the rapid pressure drop occurs.

  6. Refining the Subseafloor Circulation Model of the Middle Valley Hydrothermal System Using Fluid Geochemistry

    NASA Astrophysics Data System (ADS)

    Inderbitzen, K. E.; Wheat, C. G.; Baker, P. A.; Fisher, A. T.

    2014-12-01

    Currently, fluid circulation patterns and the evolution of rock/fluid compositions as circulation occurs in subseafloor hydrothermal systems are poorly constrained. Sedimented spreading centers provide a unique opportunity to study subsurface flow because sediment acts as an insulating blanket that traps heat from the cooling magma body and limits: (a) potential flow paths for seawater to recharge the aquifer in permeable upper basaltic basement and (b) points of altered fluid egress. This also allows for a range of thermal and geochemical gradients to exist near the sediment-water interface. Models of fluid circulation patterns in this type of hydrologic setting have been generated (eg. Stein and Fisher, 2001); however fluid chemistry datasets have not previously been used to test the model's viability. We address this issue by integrating the existing circulation model with fluid compositional data collected from sediment pore waters and high temperature hydrothermal vents located in Middle Valley on the Juan de Fuca Ridge. Middle Valley hosts a variety of hydrologic regimes: including areas of fluid recharge (Site 855), active venting (Site 858/1036; Dead Dog vent field), recent venting (Site 856/1035; Bent Hill Massive Sulfide deposit) and a section of heavily sedimented basement located between recharge and discharge sites (Site 857). We will present new results based on thermal and geochemical data from the area of active venting (Sites 858 and 1036), that was collected during Ocean Drilling Program Legs 139 and 169 and a subsequent heat flow/gravity coring effort. These results illuminate fine scale controls on secondary recharge and fluid flow within the sediment section at Site 858/1036. The current status of high temperature vents in this area (based on observations made in July, 2014) will also be outlined.

  7. Potential biomass in deep-sea hydrothermal vent ecosystem

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Takai, K.

    2012-12-01

    Since the first discovery of black smoker vents hosting chemosynthetic macrofaunal communities (Spiess et al., 1980), submarine hydrothermal systems and associated biota have attracted interest of many researchers (e.g., Humphris et al., 1995; Van Dover, 2000; Wilcock et al., 2004). In the past couple of decades, particular attention has been paid to chemolithoautotrophic microorganisms that sustain the hydrothermal vent-endemic animal communities as the primary producer. This type of microorganisms obtains energy from inorganic substances (e.g., sulfur, hydrogen, and methane) derived from hydrothermal vent fluids, and is often considered as an important modern analogue to the early ecosystems of the Earth as well as the extraterrestrial life in other planets and moons (e.g., Jannasch and Mottl, 1985; Nealson et al., 2005; Takai et al., 2006). Even today, however, the size of this type of chemosynthetic deep-sea hydrothermal vent ecosystem is largely unknown. Here, we present geophysical and geochemical constraints on potential biomass in the deep-sea hydrothermal vent ecosystem. The estimation of the potential biomass in the deep-sea hydrothermal vent ecosystem is based on hydrothermal fluid flux calculated from heat flux (Elderfield and Schltz, 1996), maximum chemical energy available from metabolic reactions during mixing between hydrothermal vent fluids and seawater (McCollom, 2007), and maintenance energy requirements of the chemolithoautotrophic microorganisms (Hoehler, 2004). The result shows that the most of metabolic energy sustaining the deep-sea hydrothermal vent ecosystem is produced by oxidation reaction of reduced sulfur, although some parts of the energy are derived from hydrogenotrophic and methanotrophic reactions. The overall total of the potential biomass in deep-sea hydrothermal vent ecosystem is calculated to be much smaller than that in terrestrial ecosystems including terrestrial plants. The big difference in biomass between the

  8. Where are the undiscovered hydrothermal vents on oceanic spreading ridges?

    NASA Astrophysics Data System (ADS)

    Beaulieu, Stace E.; Baker, Edward T.; German, Christopher R.

    2015-11-01

    In nearly four decades since the discovery of deep-sea vents, one-third of the length of global oceanic spreading ridges has been surveyed for hydrothermal activity. Active submarine vent fields are now known along the boundaries of 46 out of 52 recognized tectonic plates. Hydrothermal survey efforts over the most recent decade were sparked by national and commercial interests in the mineral resource potential of seafloor hydrothermal deposits, as well as by academic research. Here we incorporate recent data for back-arc spreading centers and ultraslow- and slow-spreading mid-ocean ridges (MORs) to revise a linear equation relating the frequency of vent fields along oceanic spreading ridges to spreading rate. We apply this equation globally to predict a total number of vent fields on spreading ridges, which suggests that ~900 vent fields remain to be discovered. Almost half of these undiscovered vent fields (comparable to the total of all vent fields discovered during 35 years of research) are likely to occur at MORs with full spreading rates less than 60 mm/yr. We then apply the equation regionally to predict where these hydrothermal vents may be discovered with respect to plate boundaries and national jurisdiction, with the majority expected to occur outside of states' exclusive economic zones. We hope that these predictions will prove useful to the community in the future, in helping to shape continuing ridge-crest exploration.

  9. Microbial anaerobic methane cycling in the subseafloor at the Von Damm hydrothermal vent field, Mid-Cayman Rise

    NASA Astrophysics Data System (ADS)

    Huber, J. A.; Reveillaud, J. C.; Stepanauskas, R.; McDermott, J. M.; Sylva, S. P.; Seewald, J.

    2013-12-01

    The Mid-Cayman Rise (MCR) is Earth's deepest and slowest spreading mid-ocean ridge located in the western Caribbean. With an axial rift valley floor at a depth of ~4200-6500 m, it represents one of the deepest sections of ridge crest worldwide. In 2009, the world's deepest hydrothermal vents (Piccard at 4960 m) and an ultramafic-influenced system only 20 km away on top of an oceanic core complex (Von Damm at 2350 m) were discovered along the MCR. Each site is hosted in a distinct geologic setting with different thermal and chemical regimes. The Von Damm site is a particularly interesting location to examine chemolithoautotrophic subseafloor microbial communities due to the abundant hydrogen, methane, and organic compounds in the venting fluids. Here, we used a combination of stable isotope tracing, next-generation sequencing, and single cell techniques to determine the identity, activity, and genomic repertoire of subseafloor anaerobic archaea involved in methane cycling in hydrothermal fluids venting at the Von Damm site. Molecular sequencing of phylogenetic marker genes revealed the presence of diverse archaea that both generate and consume methane across a geochemical and thermal spectrum of vents. Stable isotope tracing experiments were used to detect biological utilization of formate and dissolved inorganic carbon, and methane generation at 70 °C under anaerobic conditions. Results indicate that methanogenesis with formate as a substrate is occurring at 70 °C at two Von Damm sites, Ginger Castle and the Main Orifice. The results are consistent with thermodynamic predictions for carbon speciation at the temperatures encountered at the ultramafic-hosted Von Damm, where formate is predicted to be thermodynamically stable, and may thus serve as a an important source of carbon. Diverse thermophilic methanogenic archaea belonging to the genera Methanothermococcus were detected at all vent sites with both 16S rRNA tag sequencing and single cell sorting. Other

  10. Fluid dynamics of active heterogeneities in a mantle plume conduit

    NASA Astrophysics Data System (ADS)

    Farnetani, C. G.; Limare, A.; Hofmann, A. W.

    2015-12-01

    Laboratory experiments and numerical simulations indicate that the flow of a purely thermal plume preserves the azimuthal zonation of the source region, thus providing a framework to attribute a deep origin to the isotopic zonation of Hawaiian lavas. However, previous studies were limited to passive heterogeneities not affecting the flow. We go beyond this simplification by considering active heterogeneities which are compositionally denser, or more viscous, and we address the following questions: (1) How do active heterogeneities modify the axially symmetric velocity field of the plume conduit? (2) Under which conditions is the azimuthal zonation of the source region no longer preserved in the plume stem? (3) How do active heterogeneities deform during upwelling and what is their shape once at sublithospheric depths? We conducted both laboratory experiments, using a Particle Image Velocimetry (PIV) to calculate the velocity field, and high resolution three-dimensional simulations where millions of tracers keep track of the heterogeneous fluid. For compositionally denser heterogeneities we cover a range of buoyancy ratios 0fluid and η is viscosity. The initial heterogeneity has the arbitrary shape of a sphere and we vary its volume and its distance from the plume axis. We find that by increasing λ, the shape of the heterogeneity changes from filament-like to blob-like characterized by internal rotation and little stretching. By increasing B the heterogeneity tends to spread at the base of the plume stem and to rise as a tendril close to the axis, so that the initial zonation may be poorly preserved. We also find that the plume velocity field can be profoundly modified by active heterogeneities, and we explore the relation between strain rates and the evolving shape of the upwelling heterogeneity.

  11. Airbag vent valve and system

    NASA Technical Reports Server (NTRS)

    Peterson, Leslie D. (Inventor); Zimmermann, Richard E. (Inventor)

    2001-01-01

    An energy absorbing airbag system includes one or more vent valve assemblies for controlling the release of airbag inflation gases to maintain inflation gas pressure within an airbag at a substantially constant pressure during a ride-down of an energy absorbing event. Each vent valve assembly includes a cantilever spring that is flat in an unstressed condition and that has a free end portion. The cantilever spring is secured to an exterior surface of the airbag housing and flexed to cause the second free end portion of the cantilever spring to be pressed, with a preset force, against a vent port or a closure covering the vent port to seal the vent port until inflation gas pressure within the airbag reaches a preselected value determined by the preset force whereupon the free end portion of the cantilever spring is lifted from the vent port by the inflation gases within the airbag to vent the inflation gases from within the airbag. The resilience of the cantilever spring maintains a substantially constant pressure within the airbag during a ride-down portion of an energy absorbing event by causing the cantilever spring to vent gases through the vent port whenever the pressure of the inflation gases reaches the preselected value and by causing the cantilever spring to close the vent port whenever the pressure of the inflation gases falls below the preselected value.

  12. Prolonged effect of fluid flow stress on the proliferative activity of mesothelial cells after abrupt discontinuation of fluid streaming

    SciTech Connect

    Aoki, Shigehisa; Ikeda, Satoshi; Takezawa, Toshiaki; Kishi, Tomoya; Makino, Junichi; Uchihashi, Kazuyoshi; Matsunobu, Aki; Noguchi, Mitsuru; Sugihara, Hajime; Toda, Shuji

    2011-12-16

    Highlights: Black-Right-Pointing-Pointer Late-onset peritoneal fibrosis leading to EPS remains to be elucidated. Black-Right-Pointing-Pointer Fluid streaming is a potent factor for peritoneal fibrosis in PD. Black-Right-Pointing-Pointer We focused on the prolonged effect of fluid streaming on mesothelial cell kinetics. Black-Right-Pointing-Pointer A history of fluid streaming exposure promoted mesothelial proliferative activity. Black-Right-Pointing-Pointer We have thus identified a potent new factor for late-onset peritoneal fibrosis. -- Abstract: Encapsulating peritoneal sclerosis (EPS) often develops after transfer to hemodialysis and transplantation. Both termination of peritoneal dialysis (PD) and transplantation-related factors are risks implicated in post-PD development of EPS, but the precise mechanism of this late-onset peritoneal fibrosis remains to be elucidated. We previously demonstrated that fluid flow stress induced mesothelial proliferation and epithelial-mesenchymal transition via mitogen-activated protein kinase (MAPK) signaling. Therefore, we speculated that the prolonged bioactive effect of fluid flow stress may affect mesothelial cell kinetics after cessation of fluid streaming. To investigate how long mesothelial cells stay under the bioactive effect brought on by fluid flow stress after removal of the stress, we initially cultured mesothelial cells under fluid flow stress and then cultured the cells under static conditions. Mesothelial cells exposed to fluid flow stress for a certain time showed significantly high proliferative activity compared with static conditions after stoppage of fluid streaming. The expression levels of protein phosphatase 2A, which dephosphorylates MAPK, in mesothelial cells changed with time and showed a biphasic pattern that was dependent on the duration of exposure to fluid flow stress. There were no differences in the fluid flow stress-related bioactive effects on mesothelial cells once a certain time had passed

  13. A comparison of bivalve ( Calyptogena magnifica) growth at two deep-sea hydrothermal vents in the eastern Pacific

    NASA Astrophysics Data System (ADS)

    Lutz, Richard A.; Fritz, Lowell W.; Cerrato, Robert M.

    1988-10-01

    Analyses of specimens of a common deep-sea hydrothermal vent bivalve, Calyptogena magnifica, from two hydrothermal vent sites in the eastern Pacific, have been utilized to develop a mathematical model of the growth of this species based on accurate measurements of: (1) in situ rates of dissolution of the aragonitic outer granular shell layer; and (2) the thickness of the outer shell layer remaining at any given point in time at various distances from the umbo. The model permits the variances of each independently measured variable to be combined into a final confidence limit on age at a given size, making possible statistical comparisons of the calculated parameters of the von Bertalanffy growth equation. This model, in turn, provides a powerful tool for quantifying temporal and spatial variability in rates of biological processes both within and between deep-sea hydrothermal vent communities. Ontogenetic growth curves for C. magnifica specimens at both hydrothermal sites suggest that growth rates of this species are several orders of magnitude greater than those reported for the one bivalve ( Tindaria callistiformis) analysed to date from a deep-sea, non-vent habitat. These data provide additional evidence that biological processes at submarine hydrothermal vents along the mid-oceanic ridge system proceed at rates that are extremely rapid for a deep-sea environment and are comparable with those from some shallow water temperate environments. Rates of shell dissolution decreased markedly with increasing distance from vent fluids. In a 20 cm distance spanning 10 cm into a bivalve assemblage atop an active vent at Rose Garden (Galapagos Rift) to 10 cm outside the assemblage, dissolution rates of the outer granular layer of C. magnifica declined 100-fold (from 355.4 to 3.5 μm y -1, respectively) in in situ exposures of approximately 210 days. At distances ranging from 1 to 6 m away from active vent sites, no measurable thickness (<1 μm) of C. magnifica shells had

  14. Deep-sea hydrothermal vent Epsilonproteobacteria encode a conserved and widespread nitrate reduction pathway (Nap)

    PubMed Central

    Vetriani, Costantino; Voordeckers, James W; Crespo-Medina, Melitza; O'Brien, Charles E; Giovannelli, Donato; Lutz, Richard A

    2014-01-01

    Despite the frequent isolation of nitrate-respiring Epsilonproteobacteria from deep-sea hydrothermal vents, the genes coding for the nitrate reduction pathway in these organisms have not been investigated in depth. In this study we have shown that the gene cluster coding for the periplasmic nitrate reductase complex (nap) is highly conserved in chemolithoautotrophic, nitrate-reducing Epsilonproteobacteria from deep-sea hydrothermal vents. Furthermore, we have shown that the napA gene is expressed in pure cultures of vent Epsilonproteobacteria and it is highly conserved in microbial communities collected from deep-sea vents characterized by different temperature and redox regimes. The diversity of nitrate-reducing Epsilonproteobacteria was found to be higher in moderate temperature, diffuse flow vents than in high temperature black smokers or in low temperatures, substrate-associated communities. As NapA has a high affinity for nitrate compared with the membrane-bound enzyme, its occurrence in vent Epsilonproteobacteria may represent an adaptation of these organisms to the low nitrate concentrations typically found in vent fluids. Taken together, our findings indicate that nitrate reduction is widespread in vent Epsilonproteobacteria and provide insight on alternative energy metabolism in vent microorganisms. The occurrence of the nap cluster in vent, commensal and pathogenic Epsilonproteobacteria suggests that the ability of these bacteria to respire nitrate is important in habitats as different as the deep-sea vents and the human body. PMID:24430487

  15. Crustal-scale fluid migration and dewatering of the Costa Rica subduction zone

    NASA Astrophysics Data System (ADS)

    Bangs, N. L.; McIntosh, K. D.; Kluesner, J. W.; Silver, E. A.

    2014-12-01

    In 2011 we acquired a large 3D seismic reflection data volume with the R/V Langseth to examine the structure of the Costa Rica margin, NW of the Osa Peninsula. Multibeam bathymetry and backscatter data also acquired during the cruise reveal mud mounds, pockmarks, and gas plumes that indicate numerous, previously unknown, seafloor vent-related features that extend from the lower slope to the outer shelf region (Kluesner et al., 2013). These features imply active or recently active seafloor vents; however, the processes of fluid focusing into vents are not apparent from the seafloor data alone. The 3D seismic reflection data reveal indirect indicators of fluids below the seafloor. In the slope cover sediment, within the uppermost 1000 m of the seafloor, we calculated the RMS amplitude of the seismic reflections to identify vent systems from anomalously high seismic reflection amplitudes. We attribute anomalously high-amplitude zones to fluid-filled fractures and concentrated free gas directly associated with vents. Along the lower slope where a BSR is present, vents inferred from amplitude anomalies are also coincident with local shallow BSR depth anomalies. Fluids feeding these shallow vent systems appear to originate from the underlying fault-cored fold and thrust systems of the margin wedge. High amplitude anomalies within the slope cover lie directly over margin wedge thrust anticlines that develop within the 2-to-8 km thick margin wedge sequence. These anticlines are typically cored by thrusts, many of which themselves have high amplitude, reversed polarity seismic reflections that we interpret as fault zone dilation and active fluid migration. Fluids originating from the plate interface appear to be migrating up toward the seafloor along these thrust faults, as well as along the imbricately stacked stratigraphic horizons within the margin wedge. Fluids become focused into the crest of fold anticlines and directed to the seafloor vent-related features. This

  16. Synchronization and liquid crystalline order in soft active fluids.

    PubMed

    Leoni, M; Liverpool, T B

    2014-04-11

    We introduce a phenomenological theory for a new class of soft active fluids with the ability to synchronize. Our theoretical framework describes the macroscopic behavior of a collection of interacting anisotropic elements with cyclic internal dynamics and a periodic phase variable. This system can (i) spontaneously undergo a transition to a state with macroscopic orientational order, with the elements aligned, a liquid crystal, (ii) attain another broken symmetry state characterized by synchronization of their phase variables, or (iii) a combination of both types of order. We derive the equations describing a spatially homogeneous system and also study the hydrodynamic fluctuations of the soft modes in some of the ordered states. We find that synchronization can promote or inhibit the transition to a state with orientational order, and vice versa. We provide an explicit microscopic realization: a suspension of microswimmers driven by cyclic strokes. PMID:24766022

  17. The dynamics of mid-ocean ridge hydrothermal systems: Splitting plumes and fluctuating vent temperatures

    NASA Astrophysics Data System (ADS)

    Coumou, Dim; Driesner, Thomas; Geiger, Sebastian; Heinrich, Christoph A.; Matthäi, Stephan

    2006-05-01

    We present new, accurate numerical simulations of 2D models resembling hydrothermal systems active in the high-permeability axial plane of mid-ocean ridges and show that fluid flow patterns are much more irregular and convection much more unstable than reported in previous simulation studies. First, we observe the splitting of hot, rising plumes. This phenomenon is caused by the viscous instability at the interface between hot, low-viscosity fluid and cold, high-viscosity fluid. This process, known as Taylor-Saffman fingering could potentially explain the sudden extinguishing of black smokers. Second, our simulations show that for relatively moderate permeabilities, convection is unsteady resulting in transiently varying vent temperatures. The amplitude of these fluctuations typically is 40 °C with a period of decades or less, depending on the permeability. Although externally imposed events such as dike injections are possible mechanisms, they are not required to explain temperature variations observed in natural systems. Our results also offer a simple explanation of how seismic events cause fluctuating temperatures: Earthquake-induced permeability-increase shifts the hydrothermal system to the unsteady regime with accompanying fluctuating vent temperatures. We demonstrate that realistic modelling of these high-Rayleigh number convection systems does not only require the use of real fluid properties, but also the use of higher order numerical methods capable of handling high-resolution meshes. Less accurate numerical solutions smear out sharp advection fronts and thereby artificially stabilize the system.

  18. Towards a statistical mechanical theory of active fluids.

    PubMed

    Marini Bettolo Marconi, Umberto; Maggi, Claudio

    2015-12-01

    We present a stochastic description of a model of N mutually interacting active particles in the presence of external fields and characterize its steady state behavior in the absence of currents. To reproduce the effects of the experimentally observed persistence of the trajectories of the active particles we consider a Gaussian force having a non-vanishing correlation time τ, whose finiteness is a measure of the activity of the system. With these ingredients we show that it is possible to develop a statistical mechanical approach similar to the one employed in the study of equilibrium liquids and to obtain the explicit form of the many-particle distribution function by means of the multidimensional unified colored noise approximation. Such a distribution plays a role analogous to the Gibbs distribution in equilibrium statistical mechanics and provides complete information about the microscopic state of the system. From here we develop a method to determine the one- and two-particle distribution functions in the spirit of the Born-Green-Yvon (BGY) equations of equilibrium statistical mechanics. The resulting equations which contain extra-correlations induced by the activity allow us to determine the stationary density profiles in the presence of external fields, the pair correlations and the pressure of active fluids. In the low density regime we obtained the effective pair potential ϕ(r) acting between two isolated particles separated by a distance, r, showing the existence of an effective attraction between them induced by activity. Based on these results, in the second half of the paper we propose a mean field theory as an approach simpler than the BGY hierarchy and use it to derive a van der Waals expression of the equation of state. PMID:26387914

  19. Safe venting of hydrogen

    SciTech Connect

    Stewart, W.F.; Dewart, J.M.; Edeskuty, F.J.

    1990-01-01

    The disposal of hydrogen is often required in the operation of an experimental facility that contains hydrogen. Whether the vented hydrogen can be discharged to the atmosphere safely depends upon a number of factors such as the flow rate and atmospheric conditions. Calculations have been made that predict the distance a combustible mixture can extend from the point of release under some specified atmospheric conditions. Also the quantity of hydrogen in the combustible cloud is estimated. These results can be helpful in deciding of the hydrogen can be released directly to the atmosphere, or if it must be intentionally ignited. 15 refs., 5 figs., 2 tabs.

  20. Tornado protection by venting

    SciTech Connect

    Cavanagh, C.A.

    1987-01-01

    The purpose of this paper is to demonstrate the ability to protect a modern nuclear power plant from the effects of a tornado by the use of a system of venting in all safety-related structures outside of the containment. The paper demonstrates this by presenting a method of analysis and of equipment selection that fully complies with the intent and the letter of applicable federal regulatory guides. A report of an actual tornado in the City of Kalamazoo, Michigan, suggests that the concept of sealing a plant during a tornado may not always be applicable.

  1. Vented gaseous deflagrations modelling of hinged inertial vent covers.

    PubMed

    Molkov, V V; Grigorash, A V; Eber, R M; Makarov, D V

    2004-12-10

    The model of explosion pressure build up in enclosures with inertial vent covers and the CINDY code implementing the model are validated against experiments by Hochst and Leuckel (1998) in a 50 m3 vessel with a pair of ceiling-mounted upwards-opening hinged doors in a 'butterfly' configuration with surface densities of 73 and 124 kg/m2 under conditions of initially quiescent and turbulent mixtures. The model and the code are further validated against an experiment by Zalosh (1978) in a 33.5 m3 room-like enclosure with a pair of wall-mounted rectangular doors, in a parallel configuration, each hinged at its bottom edge with a surface density of 23.1 kg/m2 and initially quiescent mixture. A formula for the torque acting upon a rotating venting door is derived under conditions of vent cover jet formation. The vent cover jet effect decreases the torque three times compared to an elementary approach valid at the start of vent cover movement. It is demonstrated that, similar to translating vent covers, the vent cover jet effect is crucial for prediction of interdependent vent cover displacement in time and pressure transients. PMID:15561358

  2. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Vents and venting. 3280.611 Section 3280.611 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued) OFFICE OF ASSISTANT SECRETARY FOR HOUSING-FEDERAL HOUSING COMMISSIONER, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT MANUFACTURED...

  3. Battery vent valve

    SciTech Connect

    McCartney, C.P. Jr.; Montgomery, C.C.; Meadows, C.A.; Cole, B.A.

    1988-10-25

    This patent describes an electric storage battery comprising (1) a container defining a compartment containing gas-generating electro-chemical means for producing an electric current, and (2) check/relief valve means operatively associated with the container upon closing to isolate the electrochemical means from the ambient atmosphere and upon opening to vent the compartment when the internal pressure of the gas generated in the compartment exceeds a predetermined superatmospheric pressure the improvement wherein the valve comprises: a housing defining a vent chamber and including a valve seat projecting into the chamber, the seat having a sloping exterior sealing surface; an inlet in one end of the housing for admitting gas into the chamber from the compartment; means for exhausting the gas from the chamber to the environment; and a sealing member in the chamber circumscribing the inlet for controlling the internal pressures at which the opening and closing occurs and as necessary, for dumping relatively large volumes of the gas without excessive build-up of the internal pressure in the container. The sealing member comprising an annular elastomeric skirt secured at one end and having a tubular portion extending from the one end above the inlet so as to provide an internal annular surface exposed to the internal gas pressure and a sealing edge on the interior of the other end of the tubular portion circumferentially sealing engaging the sloping exterior sealing surface when the valve is closed

  4. Minimal continuum theories of structure formation in dense active fluids

    NASA Astrophysics Data System (ADS)

    Dunkel, Jörn; Heidenreich, Sebastian; Bär, Markus; Goldstein, Raymond E.

    2013-04-01

    Self-sustained dynamical phases of living matter can exhibit remarkable similarities over a wide range of scales, from mesoscopic vortex structures in microbial suspensions and motility assays of biopolymers to turbulent large-scale instabilities in flocks of birds or schools of fish. Here, we argue that, in many cases, the phenomenology of such active states can be efficiently described in terms of fourth- and higher-order partial differential equations. Structural transitions in these models can be interpreted as Landau-type kinematic transitions in Fourier (wavenumber) space, suggesting that microscopically different biological systems can share universal long-wavelength features. This general idea is illustrated through numerical simulations for two classes of continuum models for incompressible active fluids: a Swift-Hohenberg-type scalar field theory, and a minimal vector model that extends the classical Toner-Tu theory and appears to be a promising candidate for the quantitative description of dense bacterial suspensions. We discuss how microscopic symmetry-breaking mechanisms can enter macroscopic continuum descriptions of collective microbial motion near surfaces, and conclude by outlining future applications.

  5. EVALUATION OF SOIL VENTING APPLICATION

    EPA Science Inventory

    The ability of soil venting to inexpensively remove large amounts of volatile organic compounds (VOCs) from contaminated soils is well established. However, the time required using venting to remediate soils to low contaminant levels often required by state and federal regulators...

  6. Genomic Reconstruction of an Uncultured Hydrothermal Vent Gammaproteobacterial Methanotroph (Family Methylothermaceae) Indicates Multiple Adaptations to Oxygen Limitation

    PubMed Central

    Skennerton, Connor T.; Ward, Lewis M.; Michel, Alice; Metcalfe, Kyle; Valiente, Chanel; Mullin, Sean; Chan, Ken Y.; Gradinaru, Viviana; Orphan, Victoria J.

    2015-01-01

    Hydrothermal vents are an important contributor to marine biogeochemistry, producing large volumes of reduced fluids, gasses, and metals and housing unique, productive microbial and animal communities fueled by chemosynthesis. Methane is a common constituent of hydrothermal vent fluid and is frequently consumed at vent sites by methanotrophic bacteria that serve to control escape of this greenhouse gas into the atmosphere. Despite their ecological and geochemical importance, little is known about the ecophysiology of uncultured hydrothermal vent-associated methanotrophic bacteria. Using metagenomic binning techniques, we recovered and analyzed a near-complete genome from a novel gammaproteobacterial methanotroph (B42) associated with a white smoker chimney in the Southern Lau basin. B42 was the dominant methanotroph in the community, at ∼80x coverage, with only four others detected in the metagenome, all on low coverage contigs (7x–12x). Phylogenetic placement of B42 showed it is a member of the Methylothermaceae, a family currently represented by only one sequenced genome. Metabolic inferences based on the presence of known pathways in the genome showed that B42 possesses a branched respiratory chain with A- and B-family heme copper oxidases, cytochrome bd oxidase and a partial denitrification pathway. These genes could allow B42 to respire over a wide range of oxygen concentrations within the highly dynamic vent environment. Phylogenies of the denitrification genes revealed they are the result of separate horizontal gene transfer from other Proteobacteria and suggest that denitrification is a selective advantage in conditions where extremely low oxygen concentrations require all oxygen to be used for methane activation. PMID:26779119

  7. Genomic Reconstruction of an Uncultured Hydrothermal Vent Gammaproteobacterial Methanotroph (Family Methylothermaceae) Indicates Multiple Adaptations to Oxygen Limitation.

    PubMed

    Skennerton, Connor T; Ward, Lewis M; Michel, Alice; Metcalfe, Kyle; Valiente, Chanel; Mullin, Sean; Chan, Ken Y; Gradinaru, Viviana; Orphan, Victoria J

    2015-01-01

    Hydrothermal vents are an important contributor to marine biogeochemistry, producing large volumes of reduced fluids, gasses, and metals and housing unique, productive microbial and animal communities fueled by chemosynthesis. Methane is a common constituent of hydrothermal vent fluid and is frequently consumed at vent sites by methanotrophic bacteria that serve to control escape of this greenhouse gas into the atmosphere. Despite their ecological and geochemical importance, little is known about the ecophysiology of uncultured hydrothermal vent-associated methanotrophic bacteria. Using metagenomic binning techniques, we recovered and analyzed a near-complete genome from a novel gammaproteobacterial methanotroph (B42) associated with a white smoker chimney in the Southern Lau basin. B42 was the dominant methanotroph in the community, at ∼80x coverage, with only four others detected in the metagenome, all on low coverage contigs (7x-12x). Phylogenetic placement of B42 showed it is a member of the Methylothermaceae, a family currently represented by only one sequenced genome. Metabolic inferences based on the presence of known pathways in the genome showed that B42 possesses a branched respiratory chain with A- and B-family heme copper oxidases, cytochrome bd oxidase and a partial denitrification pathway. These genes could allow B42 to respire over a wide range of oxygen concentrations within the highly dynamic vent environment. Phylogenies of the denitrification genes revealed they are the result of separate horizontal gene transfer from other Proteobacteria and suggest that denitrification is a selective advantage in conditions where extremely low oxygen concentrations require all oxygen to be used for methane activation. PMID:26779119

  8. Trophic regions of a hydrothermal plume dispersing away from an ultramafic-hosted vent-system: Von Damm vent-site, Mid-Cayman Rise

    NASA Astrophysics Data System (ADS)

    Bennett, Sarah A.; Coleman, Max; Huber, Julie A.; Reddington, Emily; Kinsey, James C.; McIntyre, Cameron; Seewald, Jeffrey S.; German, Christopher R.

    2013-02-01

    Abstract Deep-sea ultramafic-hosted <span class="hlt">vent</span> systems have the potential to provide large amounts of metabolic energy to both autotrophic and heterotrophic microorganisms in their dispersing hydrothermal plumes. Such <span class="hlt">vent</span>-systems release large quantities of hydrogen and methane to the water column, both of which can be exploited by autotrophic microorganisms. Carbon cycling in these hydrothermal plumes may, therefore, have an important influence on open-ocean biogeochemistry. In this study, we investigated an ultramafic-hosted system on the Mid-Cayman Rise, emitting metal-poor and hydrogen sulfide-, methane-, and hydrogen-rich hydrothermal <span class="hlt">fluids</span>. Total organic carbon concentrations in the plume ranged between 42.1 and 51.1 μM (background = 43.2 ± 0.7 μM (n = 5)) and near-field plume samples with elevated methane concentrations imply the presence of chemoautotrophic primary production and in particular methanotrophy. In parts of the plume characterized by persistent potential temperature anomalies but lacking elevated methane concentrations, we found elevated organic carbon concentrations of up to 51.1 μM, most likely resulting from the presence of heterotrophic communities, their extracellular products and <span class="hlt">vent</span> larvae. Elevated carbon concentrations up to 47.4 μM were detected even in far-field plume samples. Within the Von Damm hydrothermal plume, we have used our data to hypothesize a microbial food web in which chemoautotrophy supports a heterotrophic community of microorganisms. Such an <span class="hlt">active</span> microbial food web would provide a source of labile organic carbon to the deep ocean that should be considered in any future studies evaluating sources and sinks of carbon from hydrothermal <span class="hlt">venting</span> to the deep ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016SPIE.9864E..05H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016SPIE.9864E..05H&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Active</span> <span class="hlt">fluid</span> mixing with magnetic microactuators for capture of salmonella</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hanasoge, S.; Owen, D.; Ballard, M.; Mills, Z.; Xu, J.; Erickson, M.; Hesketh, P. J.; Alexeev, A.</p> <p>2016-05-01</p> <p>Detection of low concentrations of bacteria in food samples is a challenging process. Key to this process is the separation of the target from the food matrix. We demonstrate magnetic beads and magnetic micro-cilia based microfluidic mixing and capture, which are particularly useful for pre-concentrating the target. The first method we demonstrate makes use of magnetic microbeads held on to NiFe discs on the surface of the substrate. These beads are rotated around the magnetic discs by rotating the external magnetic field. The second method we demonstrate shows the use of cilia which extends into the <span class="hlt">fluid</span> and is manipulated by a rotating external field. Magnetic micro-features were fabricated by evaporating NiFe alloy at room temperature, on to patterned photoresist. The high magnetic permeability of NiFe allows for maximum magnetic force on the features. The magnetic features were actuated using an external rotating magnet up to frequencies of 50Hz. We demonstrate <span class="hlt">active</span> mixing produced by the microbeads and the cilia in a microchannel. Also, we demonstrate the capture of target species in a sample using microbeads.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/874927','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/874927"><span id="translatedtitle"><span class="hlt">Active</span> microchannel <span class="hlt">fluid</span> processing unit and method of making</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Bennett, Wendy D [Kennewick, WA; Martin, Peter M [Kennewick, WA; Matson, Dean W [Kennewick, WA; Roberts, Gary L [West Richland, WA; Stewart, Donald C [Richland, WA; Tonkovich, Annalee Y [Pasco, WA; Zilka, Jennifer L [Pasco, WA; Schmitt, Stephen C [Dublin, OH; Werner, Timothy M [Columbus, OH</p> <p>2002-12-10</p> <p>The present invention is an <span class="hlt">active</span> microchannel <span class="hlt">fluid</span> processing unit and method of making, both relying on having (a) at least one inner thin sheet; (b) at least one outer thin sheet; (c) defining at least one first sub-assembly for performing at least one first unit operation by stacking a first of the at least one inner thin sheet in alternating contact with a first of the at least one outer thin sheet into a first stack and placing an end block on the at least one inner thin sheet, the at least one first sub-assembly having at least a first inlet and a first outlet; and (d) defining at least one second sub-assembly for performing at least one second unit operation either as a second flow path within the first stack or by stacking a second of the at least one inner thin sheet in alternating contact with second of the at least one outer thin sheet as a second stack, the at least one second sub-assembly having at least a second inlet and a second outlet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/873572','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/873572"><span id="translatedtitle"><span class="hlt">Active</span> microchannel <span class="hlt">fluid</span> processing unit and method of making</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Bennett, Wendy D [Kennewick, WA; Martin, Peter M [Kennewick, WA; Matson, Dean W [Kennewick, WA; Roberts, Gary L [West Richland, WA; Stewart, Donald C [Richland, WA; Tonkovich, Annalee Y [Pasco, WA; Zilka, Jennifer L [Pasco, WA; Schmitt, Stephen C [Dublin, OH; Werner, Timothy M [Columbus, OH</p> <p>2001-01-01</p> <p>The present invention is an <span class="hlt">active</span> microchannel <span class="hlt">fluid</span> processing unit and method of making, both relying on having (a) at least one inner thin sheet; (b) at least one outer thin sheet; (c) defining at least one first sub-assembly for performing at least one first unit operation by stacking a first of the at least one inner thin sheet in alternating contact with a first of the at least one outer thin sheet into a first stack and placing an end block on the at least one inner thin sheet, the at least one first sub-assembly having at least a first inlet and a first outlet; and (d) defining at least one second sub-assembly for performing at least one second unit operation either as a second flow path within the first stack or by stacking a second of the at least one inner thin sheet in alternating contact with second of the at least one outer thin sheet as a second stack, the at least one second sub-assembly having at least a second inlet and a second outlet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110011190','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110011190"><span id="translatedtitle"><span class="hlt">Venting</span> of a Water/Inhibited Propylene Glycol Mixture in a Vacuum Environment-Characterization and Representative Test Results</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ungar, Eugene K.; Erickson, Lisa R.</p> <p>2011-01-01</p> <p>A planned use of the Orion space vehicle involves its residence at the International Space Station for six months at a time. One concept of operations involves temporarily <span class="hlt">venting</span> portions of the idle Orion <span class="hlt">active</span> thermal control system (ATCS) during the docked phase, preventing freezing. The <span class="hlt">venting</span> would have to be reasonably complete with few, if any, completely filled pockets of frozen liquid. Even if pockets of frozen liquid did not damage the hardware during the freezing process, they could prevent the system from filling completely prior to its reactivation. The <span class="hlt">venting</span> of single component systems in a space environment has been performed numerous times and is well understood. Local nucleation occurs at warm, relatively massive parts of the system, which creates vapor and forces the bulk liquid out of the system. The remnants of the liquid will freeze, then evaporate over time through local heating. Because the Orion ATCS working <span class="hlt">fluid</span> is a 50/50 mixture of water and inhibited propylene glycol, its boiling behavior was expected to differ from that of a pure <span class="hlt">fluid</span>. It was thought that the relatively high vapor pressure water might evaporate preferentially, leaving behind a mixture enriched with the low vapor pressure propylene glycol, which would be vaporization ]resistant. Owing to this concern, a test was developed to compare the evaporation behavior of pure water, a 50/50 mixture of water and inhibited propylene glycol, and inhibited propylene glycol. The test was performed using room temperature <span class="hlt">fluids</span> in an instrumented thin walled stainless steel vertical tube. The 1 in x 0.035 in wall tube was instrumented with surface thermocouples and encased in closed cell polyurethane foam. Reticulated polyurethane foam was placed inside the tube to reduce the convection currents. A vacuum system connected to the top of the tube set the pressure boundary condition. Tests were run for the three <span class="hlt">fluids</span> at back pressures ranging from 1 to 18 torr. During each test</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900009170','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900009170"><span id="translatedtitle">Zero-Gravity Vortex <span class="hlt">Vent</span> and PVT Gaging System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Downey, M. G.; Trevathan, J. T.</p> <p>1989-01-01</p> <p>Space Station and satellite reservicing will require the ability to <span class="hlt">vent</span> gas on orbit from liquid supply or storage tanks and to gage liquid quantity under microgravity conditions. In zero gravity, (zero-g) the vortex <span class="hlt">vent</span> is capable of <span class="hlt">venting</span> gas from a tank of liquid containing gas randomly distributed as bubbles. The concept uses a spinning impeller to create centrifugal force inside a vortex tube within a tank. This creates a gas pocket and forces the liquid through a venturi and back into the tank. Gas is then <span class="hlt">vented</span> from the gas pocket through a liquid detector and then out through an exhaust port. If the liquid detector senses liquid in the <span class="hlt">vent</span> line, the <span class="hlt">fluid</span> is directed to the low-pressure port on the venturi and is returned to the tank. The advantages of this system is that it has no rotating seals and is compatible with most corrosive and cryogenic <span class="hlt">fluids</span>. A prototype was designed and built at the NASA Johnson Space Center and flown on the KC-135 zero-g aircraft. During these test flights, where microgravity conditions are obtained for up to 30 sec, the prototype demonstrated that less than 0.10 percent of the volume of <span class="hlt">fluid</span> <span class="hlt">vented</span> was liquid when the tank was half full of liquid. The pressure volume temperature (PVT) gaging system is used in conjunction with the vortex <span class="hlt">vent</span> to calculate the amount of liquid remaining in a tank under microgravity conditions. The PVT gaging system is used in conjunction with the vortex <span class="hlt">vent</span> to gage liquid quantity in zero or low gravity. The system consists of a gas compressor, accumulator, and temperature and pressure instrumentation. To measure the liquid in a tank a small amount of gas is <span class="hlt">vented</span> from the tank to the compressor and compressed into the accumulator. Pressure and temperature in the tank and accumulator are measured before and after the gas transfer occurs. Knowing the total volume of the tank, the volume of the accumulator, the volume of the intermediate lines, and initial and final pressures and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16782453','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16782453"><span id="translatedtitle">Effects of shallow-water hydrothermal <span class="hlt">venting</span> on biological communities of coastal marine ecosystems of the western Pacific.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tarasov, V G</p> <p>2006-01-01</p> <p>This review is based on integrated studies of the composition, structure and function of shallow-water ecosystems in the western Pacific that are influenced by underwater gas-hydrothermal <span class="hlt">activity</span>. Most of the data were collected from 1985 to 1997 by the Institute of Marine Biology of the Far East Branch of the Russian Academy of Science during expeditions to zones of modern volcanism. Gas-hydrothermal <span class="hlt">activity</span> of volcanoes has a great influence on the physicochemical characteristics of the water column and plankton, and of bottom sediment and benthic communities. The abundance of nutrients (SiO(3)(2-), PO(4)(3-), NO(3)(-)), gases (CO(2), CH(4), H(2), H(2)S) and other reduced compounds (C(n)H(n), S(0), S(2)O(3)(2-), NH(4)(+)) in zones of shallow-water hydrothermal <span class="hlt">vents</span> provides conditions for the use of two energy sources for primary production: sunlight (photosynthesis) and the oxidation of reduced compounds (bacterial chemosynthesis). In areas of shallow-water volcanic <span class="hlt">activity</span>, chemosynthesis occurs not only in the immediate vicinity of <span class="hlt">venting</span> <span class="hlt">fluid</span> release but also in the surface layer of the water column, where it occurs together with intense photosynthesis. This surface photosynthesis is found below the layer of chemosynthesis, which is related to the distribution of hydrothermal <span class="hlt">fluids</span> at the water surface. The contribution of each of these processes to total primary production depends on the physical and chemical conditions created by the <span class="hlt">vents</span> and on the range and adaptation potential of the organisms. On the seabed in zones of shallow-water <span class="hlt">venting</span>, microorganisms form mats that consist of bacteria of various physiological groups, microalgae, the products of their metabolism and sedimentary particles. Oxygenic photosynthesis of benthic diatoms, bacterial photosynthesis (anoxygenic photosynthesis) and autotrophic chemosynthesis in algobacterial and bacterial mats generate organic matter additional to that produced in the water column. The high rates of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24862554','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24862554"><span id="translatedtitle">Spatial patterns of Aquificales in deep-sea <span class="hlt">vents</span> along the Eastern Lau Spreading Center (SW Pacific).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ferrera, Isabel; Banta, Amy B; Reysenbach, Anna-Louise</p> <p>2014-09-01</p> <p>The microbial diversity associated with <span class="hlt">actively</span> <span class="hlt">venting</span> deep-sea hydrothermal deposits is tightly connected to the geochemistry of the hydrothermal <span class="hlt">fluids</span>. Although the dominant members of these deposits drive the structure of the microbial communities, it is less well understood whether the lower abundance groups are as closely connected to the geochemical milieu, or driven perhaps by biotic factors such as microbial community interactions. We used the natural geochemical gradients that exist in the back-arc basin, Eastern Lau Spreading Center and Valu-Fa Ridge (ELSC/VFR) in the Southwestern Pacific, to explore whether the chemolithotrophic Aquificales are influenced by geographical location, host-rock of the <span class="hlt">vent</span> field or deposit type. Using a combination of cloning, DNA fingerprinting (DGGE) and enrichment culturing approaches, all genera of this order previously described at marine <span class="hlt">vents</span> were detected, i.e., Desulfurobacterium, Thermovibrio, Aquifex, Hydrogenivirga, Persephonella and Hydrogenothermus. The comparison between clone libraries and DGGE showed similar patterns of distribution of different Aquificales whereas results differed for the enrichment cultures that were retrieved. However, the use of cultivation-based and -independent methods did provide complementary phylogenetic diversity overview of the Aquificales in these systems. Together, this survey revealed that the ELSC/VFR contains some of the largest diversity of Aquificales ever reported at a deep-sea <span class="hlt">vent</span> area, that the diversity patterns are tied to the geography and geochemistry of the system, and that this geochemical diverse back-arc basin may harbor new members of the Aquificales. PMID:24862554</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS22B..07M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS22B..07M&link_type=ABSTRACT"><span id="translatedtitle">Abundance of volatile and organic species in intermediate temperature <span class="hlt">fluids</span> from the Von Damm and Piccard deep sea hydrothermal fields, Mid-Cayman Rise</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McDermott, J. M.; Seewald, J.; Reeves, E. P.; German, C. R.; Sylva, S. P.; Klein, F.</p> <p>2012-12-01</p> <p>Two recently discovered submarine hydrothermal systems at the ultra-slow spreading Mid-Cayman Rise provide a unique opportunity to investigate how mixing and cooling influence hydrothermal <span class="hlt">fluid</span> chemistry at the deepest-yet discovered, basalt-hosted Piccard <span class="hlt">vent</span> field (4960m) and at the Von Damm <span class="hlt">vent</span> field (2300m), postulated to be ultramafic-hosted. <span class="hlt">Vent</span> <span class="hlt">fluids</span> were collected in January 2012 during R/V Atlantis cruise AT18-16 with gas-tight samplers deployed by the ROV Jason II, allowing the characterization and quantification of redox-reactive volatile species and organic compounds. Von Damm <span class="hlt">vent</span> <span class="hlt">fluids</span> ranged in temperature from 21 to 226°C, whereas Piccard <span class="hlt">fluids</span> ranged from 45 to 398°C. A key feature of these systems is the variety of <span class="hlt">fluids</span> that were <span class="hlt">actively</span> <span class="hlt">venting</span> from the seafloor at 100 to 200°C, substantially cooler than the hottest <span class="hlt">fluids</span> observed at either site. The lower temperatures reflect subsurface seawater mixing and/or conductive heat loss. <span class="hlt">Fluids</span> <span class="hlt">venting</span> within this temperature range have rarely been sampled at other systems, and the Cayman <span class="hlt">fluids</span> thus present an excellent opportunity to study the effect of cooling and mixing processes on enriched volatile species such as H2, H2S, CO2 and CH4. Three dominant processes are thought to affect volatile and organic species in intermediate temperature <span class="hlt">fluids</span>. These include microbial consumption or production, thermal alteration of biomass, and abiotic reactions. The effect of these processes on <span class="hlt">fluid</span> compositions carries implications for carbon utilization and metabolic <span class="hlt">activity</span> of modern microbial populations hosted within hydrothermal mineral deposits and ascending plumes, carbon cycling within hydrothermal systems, and net geochemical fluxes to the ocean. Endmember CO2 concentrations at Von Damm range from slightly enriched relative to seawater in the highest temperature <span class="hlt">fluids</span>, to measurably depleted in the cooler <span class="hlt">fluids</span>. Such CO2 depletions have not been previously observed in other acidic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS13B1731M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS13B1731M"><span id="translatedtitle">How Disturbance Influences Community Composition at Hydrothermal <span class="hlt">Vents</span>: a Theoretical Model of Macrofaunal Coexistence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miller, A. D.; Hsing, P.; Roxburgh, S. H.; Shea, K.; Fisher, C. R.</p> <p>2012-12-01</p> <p>Biological communities at spreading centers experience a continuum of disturbance regimes, with fast spreading ridges characterized by relatively frequent tectonic and magmatic events, and slow spreading ridges displaying more stable environmental conditions. We develop a theoretical model to show how disturbance (or lack thereof) can influence the composition of biological communities at hydrothermal <span class="hlt">vents</span>. Our model assumptions are based on empirical data, which show that macrofaunal species of interest (Riftia pachyptila, Bathymodiolus thermophilus, Calyptogena magnifica) establish in distinct microhabitats, based on availability of <span class="hlt">vent</span> <span class="hlt">fluids</span> that nourish endosymbiotic chemoautotrophs. We focus on how these establishment strategies interact with species fecundity, and with disturbance frequency and intensity, to determine what types of strategies can coexist in the system. We find that species must adopt sufficiently different fecundity-establishment strategies to coexist in the community, though strict tradeoffs between fecundity and establishment ability are not required. Additionally, we describe how the strategies that lead to coexistence depend on habitat availability and disturbance regime. Though other coexistence mechanisms may also play a role, our findings suggest why communities within a single biogeographic province may vary with spreading rate (as from N to S along the East Pacific Rise), and what strategies will allow coexistence under different disturbance regimes. Understanding how changes to disturbance regimes influence community composition is very important, as commercial mining interests are rapidly developing plans to exploit the rich mineral resources associated with hydrothermal <span class="hlt">vents</span> and their <span class="hlt">activities</span> will change the disturbance regime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960016938','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960016938"><span id="translatedtitle">[Research <span class="hlt">activities</span> in applied mathematics, <span class="hlt">fluid</span> mechanics, and computer science</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1995-01-01</p> <p>This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, <span class="hlt">fluid</span> mechanics, and computer science during the period April 1, 1995 through September 30, 1995.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS53C1062S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS53C1062S"><span id="translatedtitle">Seismicity at the Kairei Hydrothermal <span class="hlt">Vent</span> Field Near the Rodriguez Triple Junction in the Indian Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sato, T.; Takata, H.; Imai, Y.; Mori, T.; Noguchi, Y.; Kono, A.; Yamada, T.; Shinohara, M.</p> <p>2014-12-01</p> <p>1. Introduction In the first segment of the central Indian Ridge from the Rodriguez triple junction, the Kairei hydrothermal <span class="hlt">vent</span> field exists and extrudes hydrothermal <span class="hlt">fluid</span> with richer hydrogen content compared to other hydrothermal <span class="hlt">vents</span> in the world. Around the Kairei hydrothermal field, serpentinized peridotite and troctolites, and gabbroic rocks were discovered. These deep-seated rocks exposed around the Kairei field may cause the enrichment of H2 in the Kairei <span class="hlt">fluids</span>. At the Kairei field, a hydrogen-based subsurface microbial ecosystem and various hydrothermal <span class="hlt">vent</span> macrofauna were found. In the "TAIGA" Project (Trans-crustal Advection and In situ reaction of Global sub-seafloor Aquifer), this area is a representative field of "TAIGA" of hydrogen. To investigate how the deep-seated rocks (originally situated at several kilometers below seafloor) are uplifted and exposed onto seafloor, and the hydrothermal <span class="hlt">fluids</span> circulate in subsurface, we conducted a seismic refraction/reflection survey and seismicity observation with ocean bottom seismometers (OBSs). This presentation will show seismicity of the survey area. 2. Observation and results We conducted a seismic survey around the Kairei hydrothermal field from January 27 to March 19 in 2013 using S/V Yokosuka of Jamstec. We used 21 OBSs. From the 50 days seismicity observation, we found many micro earthquakes in this area. A swarm of micro earthquakes exists at a location about 1 km northwest of the Kairei field. The swarm has a NNW-SSE strike, parallel to the ridge axis. The depth of the swarm is very shallow (~4 km from seafloor). This swarm may be related to the hydrothermal <span class="hlt">activities</span> of the Kairei field. At the first segment of the central Indian Ridge, many micro earthquakes occurred. The depth of these events is deeper than that of the swarm near the Kairei field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title24-vol5/pdf/CFR-2012-title24-vol5-sec3280-611.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title24-vol5/pdf/CFR-2012-title24-vol5-sec3280-611.pdf"><span id="translatedtitle">24 CFR 3280.611 - <span class="hlt">Vents</span> and <span class="hlt">venting</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-04-01</p> <p>...) Materials—(1) Pipe. <span class="hlt">Vent</span> piping shall be standard weight steel, wrought iron, brass, copper tube DWV, listed... fixture unit loading. (4) The device shall be installed in a location that permits a free flow of air...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.B42C..05M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.B42C..05M"><span id="translatedtitle">Microbial life in cold, hydrologically <span class="hlt">active</span> oceanic crustal <span class="hlt">fluids</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meyer, J. L.; Jaekel, U.; Girguis, P. R.; Glazer, B. T.; Huber, J. A.</p> <p>2012-12-01</p> <p>It is estimated that at least half of Earth's microbial biomass is found in the deep subsurface, yet very little is known about the diversity and functional roles of these microbial communities due to the limited accessibility of subseafloor samples. Ocean crustal <span class="hlt">fluids</span>, which may have a profound impact on global nutrient cycles given the large volumes of water moving through the crustal aquifer, are particularly difficult to sample. Access to uncontaminated ocean crustal <span class="hlt">fluids</span> is possible with CORK (Circulation Obviation Retrofit Kit) observatories, installed through the Integrated Ocean Drilling Program (IODP). Here we present the first microbiological characterization of the formation <span class="hlt">fluids</span> from cold, oxygenated igneous crust at North Pond on the western flank of the Mid Atlantic Ridge. <span class="hlt">Fluids</span> were collected from two CORKs installed at IODP boreholes 1382A and 1383C and include <span class="hlt">fluids</span> from three different depth horizons within oceanic crust. Collection of borehole <span class="hlt">fluids</span> was monitored in situ using an oxygen optode and solid-state voltammetric electrodes. In addition, discrete samples were analyzed on deck using a comparable lab-based system as well as a membrane-inlet mass spectrometer to quantify all dissolved volatiles up to 200 daltons. The instruments were operated in parallel and both in situ and shipboard geochemical measurements point to a highly oxidized <span class="hlt">fluid</span>, revealing an apparent slight depletion of oxygen in subsurface <span class="hlt">fluids</span> (~215μM) relative to bottom seawater (~245μM). We were unable to detect reduced hydrocarbons, e.g. methane. Cell counts indicated the presence of roughly 2 x 10^4 cells per ml in all <span class="hlt">fluid</span> samples, and DNA was extracted and amplified for the identification of both bacterial and archaeal community members. The utilization of ammonia, nitrate, dissolved inorganic carbon, and acetate was measured using stable isotopes, and oxygen consumption was monitored to provide an estimate of the rate of respiration per cell per day</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720000553','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720000553"><span id="translatedtitle">Overflow sensor for cryogenic-<span class="hlt">fluid</span> vessels</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tener, W. M.</p> <p>1972-01-01</p> <p>Overflow sensor for cryogenic <span class="hlt">fluid</span> vessels has been designed by winding electrical resistance element on porous tubular coil form. Form is positioned in overflow <span class="hlt">vent</span> of cryogenic <span class="hlt">fluid</span> vessel where it can differentiate vapor from liquid at same temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFMOS21D..04G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFMOS21D..04G&link_type=ABSTRACT"><span id="translatedtitle">Islands in the Sea: the Patchy Distribution and Physiological Poise of <span class="hlt">Vent</span> Microbes and the Implications for Carbon Cycling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Girguis, P. R.</p> <p>2014-12-01</p> <p>The last thirty-five years have been a watershed for deep-sea microbiology. The discovery of hydrothermal <span class="hlt">vents</span> and their extraordinarily productive communities, along with the discovery of the deep subsurface biosphere and their slow-growing, energy-starved microbial communities have changed our ideas about the nature and extent of microbial life in the deep sea. Moreover, the avent of genomics and other -omics further reshaped our understanding of microbial evolution and ecology. Nevertheless, after decades of research, there remain a number of long-standing questions regarding the distribution and <span class="hlt">activity</span> of microbes in situ. For example, we know that hydrothermal <span class="hlt">vents</span> are energy-rich environments, and the energy for microbial primary productivity at hydrothermal <span class="hlt">vents</span> is primarily derived from compounds that are in disequilibria between hot, reduced thermal <span class="hlt">fluids</span> and the ambient, oxidized bottom seawater. However, we have a rudimentary understanding of how microbes are distributed within this geochemical gradient, and how temporal variability in <span class="hlt">fluid</span> flow and even eruptions influences primary and secondary productivity. At the other extreme, deep subsurface environs can be very energy limiting, and microbes are seemingly limited in their access to either electron donors (e.g. dissolved organic matter, or DOM) or electron acceptors (e.g. oxygen). Yet here, recent data revealed patterns of microbial <span class="hlt">activity</span> in the deep subsurface that are inconsistent with our conventional wisdom, and suggest that the availability of electron donors/acceptors may be greater than previously thought. Here we present our latest data, as well as the technologies and methods that allow us to synoptically measure geochemistry and microbial processes (community composition and gene expression) over space and time. Our findings reveal striking patterns of microbial distribution, gene expression and <span class="hlt">activity</span> within a <span class="hlt">vent</span> field and in the deep subsurface that begin to shed some light</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22233630','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22233630"><span id="translatedtitle">Hydrothermal <span class="hlt">vent</span> fields and chemosynthetic biota on the world's deepest seafloor spreading centre.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Connelly, Douglas P; Copley, Jonathan T; Murton, Bramley J; Stansfield, Kate; Tyler, Paul A; German, Christopher R; Van Dover, Cindy L; Amon, Diva; Furlong, Maaten; Grindlay, Nancy; Hayman, Nicholas; Hühnerbach, Veit; Judge, Maria; Le Bas, Tim; McPhail, Stephen; Meier, Alexandra; Nakamura, Ko-Ichi; Nye, Verity; Pebody, Miles; Pedersen, Rolf B; Plouviez, Sophie; Sands, Carla; Searle, Roger C; Stevenson, Peter; Taws, Sarah; Wilcox, Sally</p> <p>2012-01-01</p> <p>The Mid-Cayman spreading centre is an ultraslow-spreading ridge in the Caribbean Sea. Its extreme depth and geographic isolation from other mid-ocean ridges offer insights into the effects of pressure on hydrothermal <span class="hlt">venting</span>, and the biogeography of <span class="hlt">vent</span> fauna. Here we report the discovery of two hydrothermal <span class="hlt">vent</span> fields on the Mid-Cayman spreading centre. The Von Damm <span class="hlt">Vent</span> Field is located on the upper slopes of an oceanic core complex at a depth of 2,300 m. High-temperature <span class="hlt">venting</span> in this off-axis setting suggests that the global incidence of <span class="hlt">vent</span> fields may be underestimated. At a depth of 4,960 m on the Mid-Cayman spreading centre axis, the Beebe <span class="hlt">Vent</span> Field emits copper-enriched <span class="hlt">fluids</span> and a buoyant plume that rises 1,100 m, consistent with >400 °C <span class="hlt">venting</span> from the world's deepest known hydrothermal system. At both sites, a new morphospecies of alvinocaridid shrimp dominates faunal assemblages, which exhibit similarities to those of Mid-Atlantic <span class="hlt">vents</span>. PMID:22233630</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3274706','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3274706"><span id="translatedtitle">Hydrothermal <span class="hlt">vent</span> fields and chemosynthetic biota on the world's deepest seafloor spreading centre</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Connelly, Douglas P.; Copley, Jonathan T.; Murton, Bramley J.; Stansfield, Kate; Tyler, Paul A.; German, Christopher R.; Van Dover, Cindy L.; Amon, Diva; Furlong, Maaten; Grindlay, Nancy; Hayman, Nicholas; Hühnerbach, Veit; Judge, Maria; Le Bas, Tim; McPhail, Stephen; Meier, Alexandra; Nakamura, Ko-ichi; Nye, Verity; Pebody, Miles; Pedersen, Rolf B.; Plouviez, Sophie; Sands, Carla; Searle, Roger C.; Stevenson, Peter; Taws, Sarah; Wilcox, Sally</p> <p>2012-01-01</p> <p>The Mid-Cayman spreading centre is an ultraslow-spreading ridge in the Caribbean Sea. Its extreme depth and geographic isolation from other mid-ocean ridges offer insights into the effects of pressure on hydrothermal <span class="hlt">venting</span>, and the biogeography of <span class="hlt">vent</span> fauna. Here we report the discovery of two hydrothermal <span class="hlt">vent</span> fields on the Mid-Cayman spreading centre. The Von Damm <span class="hlt">Vent</span> Field is located on the upper slopes of an oceanic core complex at a depth of 2,300 m. High-temperature <span class="hlt">venting</span> in this off-axis setting suggests that the global incidence of <span class="hlt">vent</span> fields may be underestimated. At a depth of 4,960 m on the Mid-Cayman spreading centre axis, the Beebe <span class="hlt">Vent</span> Field emits copper-enriched <span class="hlt">fluids</span> and a buoyant plume that rises 1,100 m, consistent with >400 °C <span class="hlt">venting</span> from the world's deepest known hydrothermal system. At both sites, a new morphospecies of alvinocaridid shrimp dominates faunal assemblages, which exhibit similarities to those of Mid-Atlantic <span class="hlt">vents</span>. PMID:22233630</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007GeCoA..71.1170O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007GeCoA..71.1170O"><span id="translatedtitle">S-33 constraints on the seawater sulfate contribution in modern seafloor hydrothermal <span class="hlt">vent</span> sulfides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ono, Shuhei; Shanks, Wayne C.; Rouxel, Olivier J.; Rumble, Douglas</p> <p>2007-03-01</p> <p>Sulfide sulfur in mid-oceanic ridge hydrothermal <span class="hlt">vents</span> is derived from leaching of basaltic-sulfide and seawater-derived sulfate that is reduced during high temperature water rock interaction. Conventional sulfur isotope studies, however, are inconclusive about the mass-balance between the two sources because 34S/ 32S ratios of <span class="hlt">vent</span> <span class="hlt">fluid</span> H 2S and chimney sulfide minerals may reflect not only the mixing ratio but also isotope exchange between sulfate and sulfide. Here, we show that high-precision analysis of S-33 can provide a unique constraint because isotope mixing and isotope exchange result in different Δ 33S (≡δ 33S-0.515 δ 34S) values of up to 0.04‰ even if δ 34S values are identical. Detection of such small Δ 33S differences is technically feasible by using the SF 6 dual-inlet mass-spectrometry protocol that has been improved to achieve a precision as good as 0.006‰ (2 σ). Sulfide minerals (marcasite, pyrite, chalcopyrite, and sphalerite) and <span class="hlt">vent</span> H 2S collected from four <span class="hlt">active</span> seafloor hydrothermal <span class="hlt">vent</span> sites, East Pacific Rise (EPR) 9-10°N, 13°N, and 21°S and Mid-Atlantic Ridge (MAR) 37°N yield Δ 33S values ranging from -0.002 to 0.033 and δ 34S from -0.5‰ to 5.3‰. The combined δ 34S and Δ 33S systematics reveal that 73 to 89% of <span class="hlt">vent</span> sulfides are derived from leaching from basaltic sulfide and only 11 to 27% from seawater-derived sulfate. Pyrite from EPR 13°N and marcasite from MAR 37°N are in isotope disequilibrium not only in δ 34S but also in Δ 33S with respect to associated sphalerite and chalcopyrite, suggesting non-equilibrium sulfur isotope exchange between seawater sulfate and sulfide during pyrite precipitation. Seafloor hydrothermal <span class="hlt">vent</span> sulfides are characterized by low Δ 33S values compared with biogenic sulfides, suggesting little or no contribution of sulfide from microbial sulfate reduction into hydrothermal sulfides at sediment-free mid-oceanic ridge systems. We conclude that 33S is an effective new tracer for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70032178','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70032178"><span id="translatedtitle">S-33 constraints on the seawater sulfate contribution in modern seafloor hydrothermal <span class="hlt">vent</span> sulfides</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ono, Shuhei; Shanks, Wayne C., III; Rouxel, O.J.; Rumble, D.</p> <p>2007-01-01</p> <p>Sulfide sulfur in mid-oceanic ridge hydrothermal <span class="hlt">vents</span> is derived from leaching of basaltic-sulfide and seawater-derived sulfate that is reduced during high temperature water rock interaction. Conventional sulfur isotope studies, however, are inconclusive about the mass-balance between the two sources because 34S/32S ratios of <span class="hlt">vent</span> <span class="hlt">fluid</span> H2S and chimney sulfide minerals may reflect not only the mixing ratio but also isotope exchange between sulfate and sulfide. Here, we show that high-precision analysis of S-33 can provide a unique constraint because isotope mixing and isotope exchange result in different ??33S (?????33S-0.515 ??34S) values of up to 0.04??? even if ??34S values are identical. Detection of such small ??33S differences is technically feasible by using the SF6 dual-inlet mass-spectrometry protocol that has been improved to achieve a precision as good as 0.006??? (2??). Sulfide minerals (marcasite, pyrite, chalcopyrite, and sphalerite) and <span class="hlt">vent</span> H2S collected from four <span class="hlt">active</span> seafloor hydrothermal <span class="hlt">vent</span> sites, East Pacific Rise (EPR) 9-10??N, 13??N, and 21??S and Mid-Atlantic Ridge (MAR) 37??N yield ??33S values ranging from -0.002 to 0.033 and ??34S from -0.5??? to 5.3???. The combined ??34S and ??33S systematics reveal that 73 to 89% of <span class="hlt">vent</span> sulfides are derived from leaching from basaltic sulfide and only 11 to 27% from seawater-derived sulfate. Pyrite from EPR 13??N and marcasite from MAR 37??N are in isotope disequilibrium not only in ??34S but also in ??33S with respect to associated sphalerite and chalcopyrite, suggesting non-equilibrium sulfur isotope exchange between seawater sulfate and sulfide during pyrite precipitation. Seafloor hydrothermal <span class="hlt">vent</span> sulfides are characterized by low ??33S values compared with biogenic sulfides, suggesting little or no contribution of sulfide from microbial sulfate reduction into hydrothermal sulfides at sediment-free mid-oceanic ridge systems. We conclude that 33S is an effective new tracer for interplay among</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19010682','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19010682"><span id="translatedtitle">Cement penetration after patella <span class="hlt">venting</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jones, Christopher W; Lam, Li-On; Butler, Adam; Wood, David J; Walsh, William R</p> <p>2009-01-01</p> <p>There is a high rate of patellofemoral complications following total knee arthroplasty. Optimization of the cement-bone interface by <span class="hlt">venting</span> and suction of the tibial plateau has been shown to improve cement penetration. Our study was designed to investigate if <span class="hlt">venting</span> the patella prior to cementing improved cement penetration. Ten paired cadaver patellae were allocated prior to resurfacing to be <span class="hlt">vented</span> or non-<span class="hlt">vented</span>. Bone mineral density (BMD) was measured by DEXA scanning. In <span class="hlt">vented</span> specimens, a 1.6 mm Kirschner wire was used to breach the anterior cortex at the center. Specimens were resurfaced with standard Profix instrumentation and Versabond bone cement (Smith and Nephew PLC, UK). Cement penetration was assessed from Faxitron and sectioned images by a digital image software package (ImageJ V1.38, NIH, USA). Wilcoxon rank sum test was used to assess the difference in cement penetration between groups. The relationship between BMD and cement penetration was analyzed by Pearson correlation coefficient. There was a strong negative correlation between peak BMD and cement penetration when analyzed independent of experimental grouping (r(2)=-0.812, p=0.004). Wilcoxon rank sum testing demonstrated no significant difference (rank sum statistic W=27, p=0.579) in cement penetration between <span class="hlt">vented</span> (10.53%+/-4.66; mean+/-std dev) and non-<span class="hlt">vented</span> patellae (11.51%+/-6.23; mean+/-std dev). <span class="hlt">Venting</span> the patella using a Kirschner wire does not have a significant effect on the amount of cement penetration achieved in vitro using Profix instrumentation and Versabond cement. PMID:19010682</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007AGUFMOS43A0989S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007AGUFMOS43A0989S&link_type=ABSTRACT"><span id="translatedtitle">Macrofauna of shallow hydrothermal <span class="hlt">vents</span> on the Arctic Mid-Ocean Ridge at 71N</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schander, C.; Rapp, H. T.; Pedersen, R. B.</p> <p>2007-12-01</p> <p>Deep-sea hydrothermal <span class="hlt">vents</span> are usually associated with a highly specialized fauna and since their discovery in 1977, more than 400 species of animals have been described. Specialized <span class="hlt">vent</span> fauna includes various animal phyla, but the most conspicuous and well known are annelids, mollusks and crustaceans. We have investigated the fauna collected around newly discovered hydrothermal <span class="hlt">vents</span> on the Mohns Ridge north of Jan Mayen. The <span class="hlt">venting</span> fields are located at 71°N and the <span class="hlt">venting</span> takes place within two main areas separated by 5 km. The shallowest <span class="hlt">vent</span> area is at 500-550 m water depth and is located at the base of a normal fault. This <span class="hlt">vent</span> field stretches approximately 1 km along the strike of the fault, and it is composed of 10-20 major <span class="hlt">vent</span> sites each with multiple chimney constructions discharging up to 260°C hot <span class="hlt">fluids</span>. A large area of diffuse, low- temperature <span class="hlt">venting</span> occurs in the area surrounding the high-temperature field. Here, partly microbial mediated iron-oxide-hydroxide deposits are abundant. The hydrothermal <span class="hlt">vent</span> sites do not show any high abundance of specialized hydrothermal <span class="hlt">vent</span> fauna. Single groups (i.e. Porifera and Mollusca) have a few representatives but groups otherwise common in hydrothermal <span class="hlt">vent</span> areas (e.g. vestimentifera, Alvinellid worms, mussels, clams, galathaeid and brachyuran crabs) are absent. Up until now slightly more than 200 species have been identified from the <span class="hlt">vent</span> area. The macrofauna found in the <span class="hlt">vent</span> area is, with few exceptions, an assortment of bathyal species known in the area. One endemic, yet undescribed, species of mollusc has been found so far, an gastropod related to Alvania incognita Warén, 1996 and A. angularis Warén, 1996 (Rissoidae), two species originally described from pieces of sunken wood north and south of Iceland. It is by far the most numerous mollusc species at the <span class="hlt">vents</span> and was found on smokers, in the bacterial mats, and on the ferric deposits. A single specimen of an undescribed tanaidacean has also</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006SPIE.6171..148Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006SPIE.6171..148Z"><span id="translatedtitle">A magnetorheological <span class="hlt">fluid</span> based orthopedic <span class="hlt">active</span> knee brace</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zite, Jamaal L.; Ahmadkhanlou, Farzad; Neelakantan, Vijay A.; Washington, Gregory N.</p> <p>2006-03-01</p> <p>The disadvantage of current knee braces ranges from high cost for customization to a loss in physical mobility and limited rehabilitative value. One approach to solving this problem is to use a Magnetorheological (MR) device to make the knee brace have a controllable resistance. Our design solution is to replace the manufacturer's joint with an rotary MR <span class="hlt">fluid</span> based shear damper. The device is designed based on a maximum yield stress, a corresponding magnetic field, a torque and the MR <span class="hlt">fluid</span> viscosity. The analytical and experimental results show the advantages and the feasibility of using the proposed MR based controllable knee braces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V14A..02T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V14A..02T"><span id="translatedtitle">Fake ballistics and real explosions: field-scale experiments on the ejection and emplacement of volcanic bombs during <span class="hlt">vent</span>-clearing explosive <span class="hlt">activity</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taddeucci, J.; Valentine, G.; Gaudin, D.; Graettinger, A. H.; Lube, G.; Kueppers, U.; Sonder, I.; White, J. D.; Ross, P.; Bowman, D. C.</p> <p>2013-12-01</p> <p>Ballistics - bomb-sized pyroclasts that travel from volcanic source to final emplacement position along ballistic trajectories - represent a prime source of volcanic hazard, but their emplacement range, size, and density is useful to inverse model key eruption parameters related to their initial ejection velocity. Models and theory, however, have so far focused on the trajectory of ballistics after leaving the <span class="hlt">vent</span>, neglecting the complex dynamics of their initial acceleration phase in the <span class="hlt">vent</span>/conduit. Here, we use field-scale buried explosion experiments to study the ground-to-ground ballistic emplacement of particles through their entire acceleration-deceleration cycle. Twelve blasts were performed at the University at Buffalo Large Scale Experimental Facility with a range of scaled depths (burial depth divided by the cubic root of the energy of the explosive charge) and crater configurations. In all runs, ballistic analogs were placed on the ground surface at variable distance from the vertical projection of the buried charge, resulting in variable ejection angle. The chosen analogs are tennis and ping-pong balls filled with different materials, covering a limited range of sizes and densities. The analogs are tracked in multiple high-speed and high-definition videos, while Particle Image Velocimetry is used to detail ground motion in response to the buried blasts. In addition, after each blast the emplacement position of all analog ballistics was mapped with respect to the blast location. Preliminary results show the acceleration history of ballistics to be quite variable, from very short and relatively simple acceleration coupled with ground motion, to more complex, multi-stage accelerations possibly affected not only by the initial ground motion but also by variable coupling with the gas-particle mixture generated by the blasts. Further analysis of the experimental results is expected to provide new interpretative tools for ballistic deposits and better</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS22B..05D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS22B..05D&link_type=ABSTRACT"><span id="translatedtitle">Microbial geochemistry in rising plumes of two hydrothermal <span class="hlt">vents</span> at the Mid-Cayman Rise</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dick, G.; Breier, J. A.; Toner, B. M.; Sheik, C.; Cron, B. R.; Li, M.; Reed, D. C.; Anantharaman, K.; Baker, B. J.; Jain, S.; Klausmeier, C. A.; Jiang, H.; German, C. R.; Seewald, J.; Sylva, S. P.; McDermott, J. M.; Bennett, S. A.</p> <p>2012-12-01</p> <p>Slow and ultraslow spreading ridges comprise ~50% of the global ridge-axis length and are thus relevant to the impact of hydrothermal <span class="hlt">activity</span> on global ocean biogeochemistry. These ridges host ultramafic <span class="hlt">vent</span> systems with reducing chemical environments that yield hydrothermal <span class="hlt">fluids</span> rich in methane, hydrogen, and organic carbon, thus providing energy sources to biological communities relevant to the origin and early evolution of life on Earth and the potential for life on other planets. Microbial-geochemical interactions are also important for understanding how deep-sea hydrothermal <span class="hlt">vents</span> impact ocean biogeochemistry, especially in hydrothermal plumes, where <span class="hlt">vent</span> <span class="hlt">fluids</span> stimulate chemosynthetic microbial communities and microbes influence the oceanic fate of hydrothermally-sourced elements. Many critical processes occur in the rising portion of hydrothermal plumes, which are dynamic and challenging to sample. To address these questions and challenges, we developed methods for the in situ collection and preservation of paired microbiology and geochemical samples from rising hydrothermal plumes. Samples were collected with ROV Jason from two hydrothermal <span class="hlt">vent</span> systems, Von Damm and Beebe, which are in close proximity to each other on the Mid Cayman Rise yet are quite distinct in terms of chemistry, temperature, and depth. Bulk geochemistry, spatially-resolved spectroscopy, and molecular microbiological approaches were applied to yield some of the first views into the dynamic biotic and abiotic processes operative in rising hydrothermal plumes from an ultra-slow spreading system. Results indicate that the Cayman plumes are enriched in hydrogen, sulfur, and methane-utilizing microorganisms relative to background deep Caribbean seawater. Clear differences were observed between near-<span class="hlt">vent</span> samples, which were dominated by seafloor-derived organisms, and samples from the upper buoyant or non-buoyant plume. These Cayman plume microbes are distinct from those observed in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5435606','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5435606"><span id="translatedtitle">Geologic form and setting of a hydrothermal <span class="hlt">vent</span> field at latitude 10/sup 0/56'N, East Pacific Rise: a detailed study using Angus and Alvin</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McConachy, T.F.; Ballard, R.D.; Mottl, M.J.; Von Herzen, R.P.</p> <p>1986-04-01</p> <p>A hydrothermal <span class="hlt">vent</span> field, here called the Feather Duster site, occurs on the eastern marginal high near the edge of a narrow (95-m) and shallow (15-20-m) axial graben, within an area dominated by sheet flows and collapse features. The sheet flows are intermediate in relative age between younger <span class="hlt">fluid</span>-flow lavas on the floor of the axial graben and older pillow (constructional) lavas on the marginal highs. Hydrothermal <span class="hlt">activity</span> occurs in two zones within a 65 by 45 m area. The main zone is located where a fissure system and sulfide-sulfate chimneys <span class="hlt">vent</span> warm (9-47/sup 0/C) and hot (347/sup 0/C) hydrothermal <span class="hlt">fluids</span>. Here, two mounds of massive sulfide totaling about 200 t are forming. One occurs at the base of a 3-m-high scarp which is the wall of a drained lava lake; the other is perched on top of the scarp. 19 references, 4 figures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010632','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010632"><span id="translatedtitle">Neutron <span class="hlt">activation</span> analysis of <span class="hlt">fluid</span> inclusions for copper, manganese, and zinc</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Czamanske, G.K.; Roedder, E.; Burns, F.C.</p> <p>1963-01-01</p> <p>Microgram quantities of copper, manganese, and zinc, corresponding to concentrations greater than 100 parts per million, were found in milligram quantities of primary inclusion <span class="hlt">fluid</span> extracted from samples of quartz and fluorite from two types of ore deposits. The results indicate that neutron <span class="hlt">activation</span> is a useful analytical method for studying the content of heavy metal in <span class="hlt">fluid</span> inclusions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6962771','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6962771"><span id="translatedtitle">Chemistry of hydrothermal solutions from Pele's <span class="hlt">Vents</span>, Loihi Seamount, Hawaii</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sedwick, P.N.; McMurtry, G.M. ); Macdougall, J.D. )</p> <p>1992-10-01</p> <p>Hydrothermal <span class="hlt">fluids</span> were sampled from Pele's <span class="hlt">Vents</span> on the summit of Loihi Seamount, an intraplate, hotspot volcano, on four occasions from February 1987 to September 1990. The warm ([le]31C) <span class="hlt">vent</span> solutions are enriched in dissolved Si, CO[sub 2], H[sub 2]S, alkalinity, K[sup +], Li[sup +], Rb[sup +], Ca[sup 2+], Ba[sup 2+], Fe[sup 2+], Mn[sup 2+], NH[sup +][sub 4], and possibly Ni[sup 2+], and depleted in SO[sup 2-][sub 4], O[sub 2], Mg[sup 2+], [sup 87]Sr/[sup 86]Sr, NO[sup -][sub 3], and sometimes Cl[sup -] and Na[sup +] (calculated), relative to ambient seawater. Dissolved Si correlates linearly with sample temperature, suggesting that the solutions sampled from numerous <span class="hlt">vents</span> in the [approximately]20 m diameter field have a common source and that Si can be used as a conservative tracer for mixing of the <span class="hlt">vent</span> <span class="hlt">fluids</span> with ambient seawater. These juvenile inputs likely reflect the shallow, hotspot setting of this hydrothermal system. A simple quantitative <span class="hlt">fluid</span>-history model is considered and shown to be consistent with mass-balance constraints and saturation-state calculations, which suggest that the Si concentration of the <span class="hlt">fluids</span> may be controlled by amorphous silica saturation at [approximately]31C. Observed temporal variations in <span class="hlt">fluid</span> composition between expeditions - specifically, in Cl[sup -], A[sub T], C[sub T], Na[sup +] (calculated), Mg[sup 2+], Ca[sup 2+], Sr[sup 2+], [sup 87]Sr/[sup 86]Sr, Fe[sup 2+], Mn[sup 2+] and perhaps NH[sup +][sub 4], relative to Si - are, excepting Mg[sup 2+], [sup 87]Sr/[sup 86]Sr, and Mn[sup 2+], consistent with the effects of variable phase segregation at the proposed high-temperature endmember.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010IEITE..93.1399C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010IEITE..93.1399C"><span id="translatedtitle">Effect of Different <span class="hlt">Vent</span> Configurations on the Interruption Performance of Arc Chamber</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Degui; Li, Xingwen; Dai, Ruicheng</p> <p></p> <p>Gas flow in arc quenching chamber has an important effect on the interruption capability of low voltage circuit breakers. In this paper, based on a simplified model of arc chamber with a single break, which can be opened by the electro-dynamics repulsion force automatically, the effect of different <span class="hlt">vent</span> configurations including middle <span class="hlt">vent</span> and side <span class="hlt">vent</span> on the interruption performance is investigated. First, the experiments are carried out to compare the different performance in the interruption process between middle <span class="hlt">vent</span> type and side <span class="hlt">vent</span> type. In addition, according to the experimental model, a 3-D magneto-hydrodynamic model was developed by adapting and modified the commercial computational <span class="hlt">fluid</span> dynamics software FLUENT. The simulation results show the same trend in arc motion as explained in the experimental conclusions in theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMOS12C..05L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMOS12C..05L"><span id="translatedtitle">Gas hydrate and spatial <span class="hlt">venting</span> variations in the continental margin offshore Southwestern Taiwan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, S.; Lim, Y.; Hsieh, W.; Yang, T.; Wang, Y.</p> <p>2006-12-01</p> <p>Strong BSR, high methane contents and rapid sulfate reduction were found in the continental margin sediments offshore southwestern Taiwan. In order to identify the <span class="hlt">venting</span> phenomena and its relationship with gas hydrate, this research investigate sea floor <span class="hlt">vent</span> features using WHOI?|s Towcam system as well as piston core in the study region. A total of 10 dives were conducted on board the r/v OR-1. Pore water sulfate, dissolved sulfide, methane, chloride, del O18 ratio, sediment organic carbon, carbonate content and carbonate del C13 ratio, pyrite-S were measured Large spatial variations were found based on pictures obtained from Towcam system and piston cores. <span class="hlt">Active</span> <span class="hlt">venting</span> features include bacteria mat, live dense bivalve patches, gas plume, temperature and salinity fluctuations, rapid sulfate reduction and high concentrations of methane in sediments. In addition, <span class="hlt">vent</span> chimney, pockmark and large authigenic carbonate buildup were also observed in the <span class="hlt">active</span> <span class="hlt">venting</span> area. In contrast, in some areas without <span class="hlt">active</span> <span class="hlt">venting</span> features, scatter dead chimney, semi- buried carbonate structures, and dead bivalves were found. Total sulfate depletion was found at depth as shallow as 1 meter below sediment water interface in area near <span class="hlt">active</span> <span class="hlt">vent</span> whereas almost no sulfate depletion was observed in areas without any <span class="hlt">vent</span> feature. Stages of carbonate build up existed, with initial phase dominated by small tube, chimney, and later with massive carbonate structures protruding the sea floor. The appearances of massive carbonate buildup structures seemed to indicate the end stage of gas hydrate <span class="hlt">venting</span> phenomena.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17841485','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17841485"><span id="translatedtitle">Geomicrobiology of deep-sea hydrothermal <span class="hlt">vents</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jannasch, H W; Mottl, M J</p> <p>1985-08-23</p> <p>During the cycling of seawater through the earth's crust along the mid-ocean ridge system, geothermal energy is transferred into chemical energy in the form of reduced inorganic compounds. These compounds are derived from the reaction of seawater with crustal rocks at high temperatures and are emitted from warm (</=25 degrees C) and hot ( approximately 350 degrees C) submarine <span class="hlt">vents</span> at depths of 2000 to 3000 meters. Chemolithotrophic bacteria use these reduced chemical species as sources of energy for the reduction of carbon dioxide (assimilation) to organic carbon. These bacteria form the base of the food chain, which permits copious populations of certain specifically adapted invertebrates to grow in the immediate vicinity of the <span class="hlt">vents</span>. Such highly prolific, although narrowly localized, deep-sea communities are thus maintained primarily by terrestrial rather than by solar energy. Reduced sulfur compounds appear to represent the major electron donors for aerobic microbial metabolism, but methane-, hydrogen-, iron-, and manganese-oxidizing bacteria have also been found. Methanogenic, sulfur-respiring, and extremely thermophilic isolates carry out anaerobic chemosynthesis. Bacteria grow most abundantly in the shallow crust where upwelling hot, reducing hydrothermal <span class="hlt">fluid</span> mixes with downwelling cold, oxygenated seawater. The predominant production of biomass, however, is the result of symbiotic associations between chemolithotrophic bacteria and certain invertebrates, which have also been found as fossils in Cretaceous sulfide ores of ophiolite deposits. PMID:17841485</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985Sci...229..717J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985Sci...229..717J"><span id="translatedtitle">Geomicrobiology of Deep-Sea Hydrothermal <span class="hlt">Vents</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jannasch, Holger W.; Mottl, Michael J.</p> <p>1985-08-01</p> <p>During the cycling of seawater through the earth's crust along the midocean ridge system, geothermal energy is transferred into chemical energy in the form of reduced inorganic compounds. These compounds are derived from the reaction of seawater with crustal rocks at high temperatures and are emitted from warm (<= 25 degrees C) and hot (~ 350 degrees C) submarine <span class="hlt">vents</span> at depths of 2000 to 3000 meters. Chemolithotrophic bacteria use these reduced chemical species as sources of energy for the reduction of carbon dioxide (assimilation) to organic carbon. These bacteria form the base of the food chain, which permits copious populations of certain specifically adapted invertebrates to grow in the immediate vicinity of the <span class="hlt">vents</span>. Such highly prolific, although narrowly localized, deep-sea communities are thus maintained primarily by terrestrial rather than by solar energy. Reduced sulfur compounds appear to represent the major electron donors for aerobic microbial metabolism, but methane-, hydrogen-, iron-, and manganese-oxidizing bacteria have also been found. Methanogenic, sulfur-respiring, and extremely thermophilic isolates carry out anaerobic chemosynthesis. Bacteria grow most abundantly in the shallow crust where upwelling hot, reducing hydrothermal <span class="hlt">fluid</span> mixes with downwelling cold, oxygenated seawater. The predominant production of biomass, however, is the result of symbiotic associations between chemolithotrophic bacteria and certain invertebrates, which have also been found as fossils in Cretaceous sulfide ores of ophiolite deposits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.V41B2076G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.V41B2076G"><span id="translatedtitle">Bacterial Diets of Primary Consumers at Hydrothermal <span class="hlt">Vents</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Govenar, B.; Shank, T. M.</p> <p>2008-12-01</p> <p>Chemical energy produced by mixing hydrothermal <span class="hlt">fluids</span> and seawater supports dense biological communities on mid-ocean ridges. The base of the food web at deep-sea hydrothermal <span class="hlt">vents</span> is formed by chemolithoautotrophic bacteria that use the energy from the oxidation of reduced chemicals to fix inorganic carbon into simple sugars. With the exception of a few species that have chemolithoautotropic bacterial symbionts, most of the <span class="hlt">vent</span>-endemic macrofauna are heterotrophs that feed on free-living bacteria, protists, and other invertebrates. The most abundant and diverse group of primary consumers in hydrothermal <span class="hlt">vent</span> communities belong to the Gastropoda, particularly the patellomorph limpets. Gastropod densities can be as high as 2000 individuals m-2, and there can be as many as 13 species of gastropods in a single aggregation of the siboglinid tubeworm Riftia pachyptila and more than 40 species along the East Pacific Rise. Some gastropods are ubiquitous and others are found in specific microhabitats, stages of succession, or associated with different foundation species. To determine the mechanisms of species coexistence (e.g. resource partitioning or competition) among hydrothermal <span class="hlt">vent</span> primary consumers and to track the flow of energy in hydrothermal <span class="hlt">vent</span> communities, we employed molecular genetic techniques to identify the gut contents of four species of co-occurring hydrothermal <span class="hlt">vent</span> gastropods, Eulepetopsis vitrea, Lepetodrilus elevatus, Lepetodrilus ovalis and Lepetodrilus pustulosus, collected from a single diffuse-flow hydrothermal <span class="hlt">vent</span> site on the East Pacific Rise. Unique haplotypes of the 16S gene that fell among the epsilon-proteobacteria were found in the guts of every species, and two species had gut contents that were similar only to epsilon-proteobacteria. Two species had gut contents that also included haplotypes that clustered with delta-proteobacteria, and one species had gut contents that clustered with alpha- proteobacteria. Differences in the diets</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JPS...271..326Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JPS...271..326Z"><span id="translatedtitle"><span class="hlt">Activated</span> oil sands <span class="hlt">fluid</span> coke for electrical double-layer capacitors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zuliani, Jocelyn E.; Kirk, Donald W.; Jia, Charles Q.; Tong, Shitang</p> <p>2014-12-01</p> <p>Electrochemical capacitors are important energy storage devices that have high power density, rapid charging cycles and are highly cyclable. In this study, <span class="hlt">activated</span> <span class="hlt">fluid</span> coke has demonstrated high surface area, improved capacitive properties, and high energy density. <span class="hlt">Fluid</span> coke is a by-product generated from continuous high temperature bitumen upgrading, resulting in the formation of nearly spherical particles with concentric carbon layers. The residual sulphur impurities in <span class="hlt">fluid</span> coke may enhance its energy storage performance. The <span class="hlt">activated</span> coke samples have high specific surface areas, up to 1960 m2 g-1, and show promising capacitive performance, in 4 M KOH electrolyte, with high gravimetric and specific capacitances of 228-257 F g-1 and 13-14 μF cm-2, respectively. These results are comparable to other top performing <span class="hlt">activated</span> carbon materials [1-3]. The <span class="hlt">activated</span> <span class="hlt">fluid</span> coke maintains high performance at fast charging rates, greater than 160 F g-1 at a current density of 7500 mA g-1. <span class="hlt">Activated</span> <span class="hlt">fluid</span> coke's high capacitance and promising rate performance are potentially associated with its unique layered, and the moderate sulphur content in the chemical structure. <span class="hlt">Activated</span> <span class="hlt">fluid</span> coke is a unique opportunity to use a limited use by-product to generate <span class="hlt">activated</span> carbon that has a high surface area and promising energy storage properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810008066','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810008066"><span id="translatedtitle">Development and testing of heat transport <span class="hlt">fluids</span> for use in <span class="hlt">active</span> solar heating and cooling systems</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parker, J. C.</p> <p>1981-01-01</p> <p>Work on heat transport <span class="hlt">fluids</span> for use with <span class="hlt">active</span> solar heating and cooling systems is described. Program objectives and how they were accomplished including problems encountered during testing are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15188434','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15188434"><span id="translatedtitle">Functional and hierarchical interactions among zebrafish vox/<span class="hlt">vent</span> homeobox genes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gilardelli, Claudio N; Pozzoli, Ombretta; Sordino, Paolo; Matassi, Giorgio; Cotelli, Franco</p> <p>2004-07-01</p> <p>The vertebrate Vox/<span class="hlt">Vent</span> family of transcription factors plays a crucial role in the establishment of the dorsoventral (DV) axis, by repressing organizer genes such as bozozok/dharma, goosecoid, and chordino. In Danio rerio (zebrafish), members of the vox/<span class="hlt">vent</span> gene family (vox/vega1, <span class="hlt">vent</span>/vega2, and ved) are thought to share expression patterns and functional properties. Bringing novel insights in the differential <span class="hlt">activity</span> of the zebrafish vox/<span class="hlt">vent</span> genes, we propose a critical role for the ved gene in DV patterning of vertebrate embryos. ved is not only expressed as a maternal gene, but it also appears to function as a repressor of dorsal factors involved in organizer formation. At early- and mid-gastrula stage, ved appears to be finely controlled by antagonist crosstalks in a complex regulatory network, involving gradients of bone morphogenetic protein (BMP) <span class="hlt">activity</span>, dorsal factors, and vox/<span class="hlt">vent</span> family members. We show that ved transcripts are ventrally restricted by BMP factors such as bmp2b, bmp7, smad5, and alk8, and by dorsal factors (chd and gsc). Alteration of ved expression in both vox and <span class="hlt">vent</span> deletion mutants and vox and <span class="hlt">vent</span> mRNAs-injected embryos, suggests that vox and <span class="hlt">vent</span> function downstream of BMP signaling to negatively regulate ved expression. This inhibitory role is emphasized by a vox and <span class="hlt">vent</span> redundant <span class="hlt">activity</span>, compared with single gene effects. PMID:15188434</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFMOS33A1458Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFMOS33A1458Z"><span id="translatedtitle">Hydrogen may be an energy source for endosymbiotic bacteria of the <span class="hlt">vent</span> mussel Bathymodiolus puteoserpentis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zielinski, F.; Pape, T.; Wenzhöfer, F.; Seifert, R.; Dubilier, N.</p> <p>2005-12-01</p> <p>The ultramafic hosted Logatchev hydrothermal <span class="hlt">vent</span> field at the slow spreading Mid-Atlantic Ridge (MAR) exhibits unusually high hydrogen concentrations due to serpentinization of ultramafic rocks. Endmember H2-concentrations here have been calculated to be as high as 12 mM which is significantly higher than at most other <span class="hlt">vent</span> sites along the MAR. Hydrogen is a potential energy source for bacteria providing an energy yield of roughly 240 kJ/mol if oxidized with oxygen. Hence, the energy yield is even higher than for conventional aerobic respiration which liberates 220 kJ/mol. The ability to use H2 as an energy source has been shown for a variety of free-living bacteria. However, to date no other energy sources besides methane and sulfide have been identified for <span class="hlt">vent</span> (or seep) symbionts. Here we show that H2 is consumed by endosymbiotic bacteria of the Logatchev <span class="hlt">vent</span> mussel Bathymodiolus puteoserpentis. B. puteoserpentis is known to live in dual symbiosis with methane- and sulfide-oxidizing bacteria that occur intracellularly in specialized gill cells called bacteriocytes. The methanotrophic symbionts use methane as both an energy and carbon source whereas the thiotrophic symbionts use H2S as an energy and dissolved CO2 as a carbon source. Hydrothermal <span class="hlt">fluids</span> carrying methane and sulfide provide the energy for the bacteria and the bacteria in turn provide the mussel with carbon compounds. The mussel on the other hand supplies its symbionts with a constant <span class="hlt">fluid</span> flow and, by hosting them offers an ideal ecological niche. Freshly dissected gill pieces of B. puteoserpentis incubated in chilled sea water containing hydrogen gas readily consumed H2. The consumption of H2 over time was significantly higher in gill tissues than in symbiont-free mussel tissue indicating that the symbiotic bacteria are responsible for the observed <span class="hlt">activity</span>. H2-consumption rates were similar in mussels from two different sampling sites, Irina II: 37 nmol h-1 (ml gill)-1 and Quest: 31 nmol h-1</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.4342K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.4342K"><span id="translatedtitle">Heat and Volume Fluxes at the Turtle Pits <span class="hlt">Vent</span> Site, southern Mid Atlantic Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Köhler, Janna; Walter, Maren; Mertens, Christian; Sültenfuß, Jürgen; Rhein, Monika</p> <p>2010-05-01</p> <p>The Turtle Pits <span class="hlt">vent</span> site consists of eight known high temperature <span class="hlt">vents</span> and several diffuse <span class="hlt">vent</span> sites which are distributed over three hydrothermal fields: Turtle Pits, Comfortless Cove, and Red Lion. These <span class="hlt">vent</span> fields are located in a north-south orientated rift valley at the Mid-Atlantic Ridge (MAR) near 5°S. The total volume and heat emissions of the entire Turtle Pits site have been calculated with three different approaches using data collected during a Meteor cruise in May 2006 and a L'Atalante cruise in January 2008. The data sets consist of vertical profiles and towed transects of temperature, salinity, and turbidity, as well as direct velocity measurements with a lowered acoustic Doppler current profiler (LADCP) and water samples for Helium isotope analysis. <span class="hlt">Vent</span> <span class="hlt">fluid</span> samples for noble gas analysis where taken with ROVs. Since the <span class="hlt">vent</span> <span class="hlt">fluid</span> is highly enriched in primordial 3He this noble gas can be used as a conservative tracer for <span class="hlt">vent</span> <span class="hlt">fluid</span>. The geographical setting of the <span class="hlt">vent</span> site confines the particle plume to the rift valley since the depth of the valley exceeds the rise height of the plume. Therefore the fluxes of heat and volume can be estimated from the horizontal helium transport in the valley in combination with a mean 3He endmember concentration determined from the water samples taken with the ROVs. The comparison of the 3He concentrations measured south of the hydrothermal <span class="hlt">vents</span> with the 3He signal north of the hydrothermal <span class="hlt">vents</span> suggests a rather strong northward flow. This is confirmed by the tide corrected velocities observed with the LADCP during the Meteor cruise. The northward volume transport has been calculated using the local bathymetry and tide corrected velocities from the Meteor cruise. In combination with the 3He concentrations and the average 3He endmember concentration a flux of 1000 l/s is estimated, which corresponds to a heat flux of 1400 MW. The measured temperature anomalies within the plume combined with the known</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005AGUFM.V51C1505B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005AGUFM.V51C1505B&link_type=ABSTRACT"><span id="translatedtitle">Iron Oxidizing and Reducing Bacteria as Contributors to Basaltic Glass Colonization and Subsequent Weathering in <span class="hlt">Active</span> Hydrothermal <span class="hlt">Vent</span> Systems on Loihi and Vailulu'u Seamounts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bailey, B.; Templeton, A.; Haucke, L.; Staudigel, H.; Tebo, B. M.</p> <p>2005-12-01</p> <p>The extreme oligotrophic nature of the oceanic crust was once believed to be an inhospitable environment to support microbial life. However, numerous studies in the past two decades have revealed diverse chemolithotrophic microbial communities inhabiting the deep biosphere within the oceanic crust. Vailulu'u Seamount in American Samoa and Loihi Seamount in Hawai'i provide access to the deep biosphere environments through the study of the interaction of hydrothermal <span class="hlt">vent</span> water, basaltic substrates and microbial communities. Both seamounts have been found to exhibit similar iron-encrusted microbial mats surrounding both high and low temperature hydrothermal <span class="hlt">vent</span> orifices. We are targeting iron as the main electron donor/acceptor in these environments due to the relative abundance and availability in basalts. Through the use of the HURL Pisces submersibles, we exposed amended basaltic glasses of several different compositions to a host of different environments on both seamounts in order to study the colonization and biofilm characteristics of the microbial communities. A large culturing effort reveals multiple iron oxidizing and reducing bacteria as members of the microbial community responsible for the colonization and subsequent dissolution and alteration of basaltic glass. We employ an annular reactor to expose the same suite of chemically altered basaltic glasses to a sample of iron microbial mats taken from Vailulu'u to provide a laboratory complement the environmental exposure experiments. Here cell counts reveal a 90% enhanced colonization and growth on the basalt glass versus the surrounding epoxy and borosilicate glass. The ability of microbes to leach nutrients (such as iron) out of the host substrate has far reaching astrobiological implications for nutrient sources available to sustain life in a Mars or Europa biosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BGeo...12.5455P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BGeo...12.5455P"><span id="translatedtitle">Comparative study of <span class="hlt">vent</span> and seep macrofaunal communities in the Guaymas Basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Portail, M.; Olu, K.; Escobar-Briones, E.; Caprais, J. C.; Menot, L.; Waeles, M.; Cruaud, P.; Sarradin, P. M.; Godfroy, A.; Sarrazin, J.</p> <p>2015-09-01</p> <p>Understanding the ecological processes and connectivity of chemosynthetic deep-sea ecosystems requires comparative studies. In the Guaymas Basin (Gulf of California, Mexico), the presence of seeps and <span class="hlt">vents</span> in the absence of a biogeographic barrier, and comparable sedimentary settings and depths offers a unique opportunity to assess the role of ecosystem-specific environmental conditions on macrofaunal communities. Six seep and four <span class="hlt">vent</span> assemblages were studied, three of which were characterised by common major foundation taxa: vesicomyid bivalves, siboglinid tubeworms and microbial mats. Macrofaunal community structure at the family level showed that density, diversity and composition patterns were primarily shaped by seep- and <span class="hlt">vent</span>-common abiotic factors including methane and hydrogen sulfide concentrations, whereas <span class="hlt">vent</span> environmental specificities (higher temperature, higher metal concentrations and lower pH) were not significant. The type of substratum and the heterogeneity provided by foundation species were identified as additional structuring factors and their roles were found to vary according to <span class="hlt">fluid</span> regimes. At the family level, seep and <span class="hlt">vent</span> similarity reached at least 58 %. All <span class="hlt">vent</span> families were found at seeps and each seep-specific family displayed low relative abundances (< 5 %). Moreover, 85 % of the identified species among dominant families were shared between seep and <span class="hlt">vent</span> ecosystems. This study provides further support to the hypothesis of continuity among deep-sea seep and <span class="hlt">vent</span> ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.7272K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.7272K"><span id="translatedtitle">Hydrothermal Fluxes at the Turtle Pits <span class="hlt">Vent</span> Site, southern MAR</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Köhler, J.; Walter, M.; Mertens, C.; Sültenfuß, J.; Rhein, M.</p> <p>2009-04-01</p> <p>The Turtle Pits <span class="hlt">vent</span> fields are located in a north-south orientated rift valley at the Mid-Atlantic Ridge (MAR) near 5oS. The site consists of three known hydrothermal fields: Turtle Pits, Comfortless Cove, and Red Lion. Data collected during a Meteor cruise in May 2006 and a L' Atalante cruise in January 2008 are used to calculate the total emission of volume, heat, and helium of the site. The data sets consist of vertical profiles and towed transsects of temperature, salinity, and turbidity, as well as direct velocity measurements with a lowered acoustic Doppler current profiler (LADCP) and water samples for Helium isotope analysis. <span class="hlt">Vent</span> <span class="hlt">fluid</span> samples for noble gas analysis where taken with an ROV. The particle plume is confined to the rift valley since the depth of the valley exceeds the rise height of the plume. Therefore the fluxes of heat and volume can be estimated from the helium fluxes at the <span class="hlt">vent</span> sites in comparison with the horizontal helium transport in the valley. The comparison of the 3He concentration measured south of the hydrothermal <span class="hlt">vents</span> with the 3He signal north of the hydrothermal <span class="hlt">vents</span> suggests a rather strong northward flow. This is confirmed by the tide corrected velocities observed with the LADCP during the Meteor cruise. The northward volume transport has been calculated using the local bathymetry and tide corrected velocities from the Meteor cruise. In combination with the 3He concentrations and an average 3He end member concentration a flux of 900 l/s is estimated, which corresponds to a heat flux of 450 MW. The rise height of the particle plume estimated from the turbidity data combined with the known background stratification yields an estimate of the total flux of the hydrothermal <span class="hlt">vents</span> which is one order of magnitude lower.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001E%26PSL.193..395K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001E%26PSL.193..395K"><span id="translatedtitle">Discovery of new hydrothermal <span class="hlt">vent</span> sites in Bransfield Strait, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klinkhammer, G. P.; Chin, C. S.; Keller, R. A.; Dählmann, A.; Sahling, H.; Sarthou, G.; Petersen, S.; Smith, F.; Wilson, C.</p> <p>2001-12-01</p> <p>We carried out a search for hydrothermal <span class="hlt">vents</span> in the Central Basin of Bransfield Strait, Antarctica. The ZAPS (zero angle photon spectrometer) chemical sensor and instrument package (Oregon State University), OFOS (ocean-floor observation system) camera sled and TVG (TV-grab) (GEOMAR) were used to explore the water column and underlying seafloor. These operations were supplemented with a series of dredges. Hydrothermal plumes over Hook Ridge at the eastern end of the basin are confined to the E ridge crest and SE flank. The plumes are complex and sometimes contain two turbidity maxima one widespread feature centered at 1150 m and a smaller, more localized but broad maximum at 600-800 m. We traced the source of the shallower plume to a sunken crater near the ridge crest using sensors on the ZAPS instrument package. Subsequently two TV-grabs from the crater brought back hot, soupy sediment (42-49°C) overlain by hard, siliceous crusts and underlain by a thick layer of volcanic ash. We also recovered chimney fragments whose texture and mineralogy indicate <span class="hlt">venting</span> temperatures in excess of 250°C. Native sulfur and Fe-sulfides occur in fractures and porous layers in sediment from throughout the area. Pore water data from the crater site are consistent with <span class="hlt">venting</span> into a thin sediment layer and indicate phase separation of <span class="hlt">fluids</span> beneath Hook Ridge. The source of the deeper plumes at Hook Ridge has yet to be located. We also explored a series of three parallel volcanic ridges west of Hook Ridge called Three Sisters. We detected water column anomalies indicative of <span class="hlt">venting</span> with the ZAPS package and recovered hydrothermal barites and sulfides from Middle Sister. We spent considerable time photographing Middle Sister and Hook Ridge but did not identify classic <span class="hlt">vent</span> fauna at either location. We either missed small areas with our photography or typical MOR <span class="hlt">vent</span> fauna are absent at these sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990106579&hterms=gravity+definition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgravity%2Bdefinition','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990106579&hterms=gravity+definition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgravity%2Bdefinition"><span id="translatedtitle">Zero Gravity Cryogenic <span class="hlt">Vent</span> System Concepts for Upper Stages</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Flachbart, Robin H.; Holt, James B.; Hastings, Leon J.</p> <p>1999-01-01</p> <p>The capability to <span class="hlt">vent</span> in zero gravity without resettling is a technology need that involves practically all uses of sub-critical cryogenics in space. <span class="hlt">Venting</span> without resettling would extend cryogenic orbital transfer vehicle capabilities. However, the lack of definition regarding liquid/ullage orientation coupled with the somewhat random nature of the thermal stratification and resulting pressure rise rates, lead to significant technical challenges. Typically a zero gravity <span class="hlt">vent</span> concept, termed a thermodynamic <span class="hlt">vent</span> system (TVS), consists of a tank mixer to destratify the propellant, combined with a Joule-Thomson (J-T) valve to extract thermal energy from the propellant. Marshall Space Flight Center's (MSFC's) Multipurpose Hydrogen Test Bed (MHTB) was used to test both spray bar and axial jet TVS concepts. The axial jet system consists of a recirculation pump heat exchanger unit. The spray bar system consists of a recirculation pump, a parallel flow concentric tube, heat exchanger, and a spray bar positioned close to the longitudinal axis of the tank. The operation of both concepts is similar. In the mixing mode, the recirculation pump withdraws liquid from the tank and sprays it into the tank liquid, ullage, and exposed tank surfaces. When energy is required. a small portion of the recirculated liquid is passed sequentially through the J-T expansion valve, the heat exchanger, and is <span class="hlt">vented</span> overboard. The <span class="hlt">vented</span> vapor cools the circulated bulk <span class="hlt">fluid</span>, thereby removing thermal energy and reducing tank pressure. The pump operates alone, cycling on and off, to destratify the tank liquid and ullage until the liquid vapor pressure reaches the lower set point. At that point. the J-T valve begins to cycle on and off with the pump. Thus, for short duration missions, only the mixer may operate, thus minimizing or even eliminating, boil-off losses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20544439','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20544439"><span id="translatedtitle">Research <span class="hlt">activities</span> on supercritical <span class="hlt">fluid</span> science in food biotechnology.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Khosravi-Darani, Kianoush</p> <p>2010-06-01</p> <p>This article serves as an overview, introducing the currently popular area of supercritical <span class="hlt">fluids</span> and their uses in food biotechnology. Within each application, and wherever possible, the basic principles of the technique, as well as a description of the history, instrumentation, methodology, uses, problems encountered, and advantages over the traditional, non-supercritical methods are given. Most current commercial application of the supercritical extraction involve biologically-produced materials; the technique may be particularly relevant to the extraction of biological compounds in cases where there is a requirement for low-temperature processing, high mass-transfer rates, and negligible carrying over of the solvent into the final product. Special applications to food processing include the decaffeination of green coffee beans, the production of hops extracts, the recovery of aromas and flavors from herbs and spices, the extraction and fractionation of edible oils, and the removal of contaminants, among others. New advances, in which the extraction is combined with reaction or crystallization steps, may further increase the attractiveness of supercritical <span class="hlt">fluids</span> in the bioprocess industries. To develop and establish a novel and effective alternative to heating treatment, the lethal action of high hydrostatic pressure CO(2) on microorganisms, with none or only a minimal heating process, has recently received a great deal of attention. PMID:20544439</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840015786','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840015786"><span id="translatedtitle">Modeling of zero gravity <span class="hlt">venting</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Merte, H., Jr.</p> <p>1984-01-01</p> <p>The <span class="hlt">venting</span> of cylindrical containers partially filled with initially saturated liquids was conducted under zero gravity conditions and compared with an analytical model which determined the effect of interfacial mass transfer on the ullage pressure response during <span class="hlt">venting</span>. A model is proposed to improve the estimation of the interfacial mass transfer. Duhammel's superposition integral is incorporated in this analysis to approximate the transient temperature response of the interface, treating the liquid as a semiinfinite solid with conduction heat transfer. This approach to estimating interfacial mass transfer gives improved response when compared to previous models. The model still predicts a pressure decrease greater than those in the experiments reported.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/915497','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/915497"><span id="translatedtitle">TRANSPORT OF WASTE SIMULANTS IN PJM <span class="hlt">VENT</span> LINES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Qureshi, Z</p> <p>2007-02-21</p> <p>The experimental work was conducted to determine whether there is a potential for waste simulant to transport or 'creep' up the air link line and contaminate the pulse jet <span class="hlt">vent</span> system, and possibly cause long term restriction of the air link line. Additionally, if simulant creep occurred, establish operating parameters for washing down the line. The amount of the addition of flush <span class="hlt">fluids</span> and mixer downtime must be quantified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title24-vol5/pdf/CFR-2013-title24-vol5-sec3280-611.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title24-vol5/pdf/CFR-2013-title24-vol5-sec3280-611.pdf"><span id="translatedtitle">24 CFR 3280.611 - <span class="hlt">Vents</span> and <span class="hlt">venting</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-04-01</p> <p>...) Materials—(1) Pipe. <span class="hlt">Vent</span> piping shall be standard weight steel, wrought iron, brass, copper tube DWV, listed... fittings shall conform to the type of piping used. (i) Fittings for screw pipe shall be cast iron, malleable iron, plastic, or brass, with standard pipe threads. (ii) Fittings for copper tubing shall be...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.T52A0923M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.T52A0923M"><span id="translatedtitle">First Survey For Submarine Hydrothermal <span class="hlt">Vents</span> In NE Sulawesi, Indonesia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McConachy, T.; Binns, R.; Permana, H.</p> <p>2001-12-01</p> <p>The IASSHA-2001 cruise (Indonesia-Australia Survey for Submarine Hydrothermal <span class="hlt">Activity</span>) was successfully conducted from June 1 to June 29 on board Baruna Jaya VIII. Preliminary results are reported of the first expedition to locate and study submarine hydrothermal <span class="hlt">activity</span> in north east Sulawesi. Leg A focussed on Tomini Bay, a virtually unexplored Neogene sedimentary basin. Its objective was to test whether modern sediment-hosted hydrothermal <span class="hlt">activity</span> occurred on the sea floor. The results of new bathymetric mapping, sediment coring and CTD/transmissometer hydrocasts negate the likely presence in central Tomini Bay of large-scale modern analogues of hydrothermal massive sulfide environments involving hydrothermal <span class="hlt">venting</span> of basinal or magma-derived <span class="hlt">fluids</span> into reduced sediments. It is possible that the "heat engine" required to drive circulation of basinal and hydrothermal <span class="hlt">fluids</span> is today too weak. Surveys around Colo volcano indicate that it may be in its final stage of evolution. Leg B studied the arc and behind-arc sectors of the Sangihe volcanic island chain extending northwards from Quaternary volcanoes on the northeastern tip of Sulawesi's North Arm, near Manado. West of the main <span class="hlt">active</span> chain and extending northwards from Manado there is a subparallel ridge surmounted by a number of high (>2000 m) seamounts of uncertain age. Fifteen relatively high-standing submarine edifices were crossed during this leg, of which nine were tested for hydrothermal <span class="hlt">activity</span> by hydrocast and dredging. Eight sites were known from previous bathymetric surveys, and seven are new discoveries made by narrow-beam or multibeam echo sounding. Two submarine edifices at least 1000 m high were discovered in the strait immediately north of Awu volcano on Sangihe Island. One, with crest at 206 m, is surrounded by a circular platform 300m deep which we infer to be a foundered fringing reef to a formerly emergent island. The other, lacking such a platform, appears relatively young and may be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1237624','SCIGOV-DOEDE'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1237624"><span id="translatedtitle">Google Earth locations of USA and seafloor hydrothermal <span class="hlt">vents</span> with associated rare earth element data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Andrew Fowler</p> <p>2016-02-10</p> <p>Google Earth .kmz files that contain the locations of geothermal wells and thermal springs in the USA, and seafloor hydrothermal <span class="hlt">vents</span> that have associated rare earth element data. The file does not contain the actual data, the actual data is available through the GDR website in two tier 3 data sets entitled "Compilation of Rare Earth Element Analyses from US Geothermal Fields and Mid Ocean Ridge (MOR) Hydrothermal <span class="hlt">Vents</span>" and "Rare earth element content of thermal <span class="hlt">fluids</span> from Surprise Valley, California"</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21326076','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21326076"><span id="translatedtitle">Remote-Handled Transuranic Waste Drum <span class="hlt">Venting</span> - Operational Experience and Lessons Learned</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Clements, Th.L.Jr.; Bhatt, R.N.; Troescher, P.D.; Lattin, W.J.</p> <p>2008-07-01</p> <p>Remote-handled transuranic (RH TRU) waste drums must be <span class="hlt">vented</span> to meet transportation and disposal requirement before shipment to the Waste Isolation Pilot Plant. The capability to perform remote <span class="hlt">venting</span> of drums was developed and implemented at the Idaho National Laboratory. Over 490 drums containing RH TRU waste were successfully <span class="hlt">vented</span>. Later efforts developed and implemented a long-stem filter to breach inner waste bags, which reduced layers of confinement and mitigated restrictive transportation wattage limits. This paper will provide insight to the technical specifications for the drum <span class="hlt">venting</span> system, development, and testing <span class="hlt">activities</span>, startup, operations, and lessons learned. (authors)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002Geo....30..407S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002Geo....30..407S"><span id="translatedtitle">Mass wasting, methane <span class="hlt">venting</span>, and biological communities on the Mendocino transform fault</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stakes, Debra S.; Trehu, Anne M.; Goffredi, Shana K.; Naehr, Thomas H.; Duncan, Robert A.</p> <p>2002-05-01</p> <p>Chemosynthetic cold-seep vestimentiferan tubeworms and vesicomyid clams inhabiting oceanic basaltic rock have been discovered on the Gorda Escarpment sector of the Mendocino transform fault 73 km west of Cape Mendocino, northern California. The sparse cold-seep animals are “biomarkers” that identify zones of focused <span class="hlt">fluid</span> <span class="hlt">venting</span> from a methane gas horizon seismically imaged as a bottom-simulating reflector (BSR) within sediments on the southern flank of the escarpment. This is the first example of a methane-based cold-seep community on exposed oceanic basement rock within an area dominated by transform tectonics. This discovery extends the range of known environments in which the subsurface flow and <span class="hlt">venting</span> of methane-rich <span class="hlt">fluids</span> are linked both with geological <span class="hlt">activity</span> and chemosynthetic communities. Observations by remotely operated vehicle of the distribution of the animals, sediment, basaltic talus, and basement outcrop delineate a large slump headscarp that channels subsurface <span class="hlt">fluid</span>. Seismic surveys of the southern flank of the Mendocino transform fault (the Vizcaino block) define a BSR hosted in the thick sedimentary sequence that projects to the wall of the Gorda Escarpment at the same depth as the chemosynthetic community. The well-defined BSR in the marine sediment of the Vizcaino block results from an accumulation of methane gas possibly capped by methane hydrate. The isotopic composition of Mg-calcite found along the headscarp (δ13C = -65‰; δ18O = 4.8‰) is consistent with <span class="hlt">fluids</span> derived from dissociated methane hydrate. We propose that the tectonic uplift along this transform margin has resulted in the lateral, northward movement of methane from the Vizcaino sedimentary sequence to the east-trending wall of the north-facing Gorda Escarpment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AIPC..699..463C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AIPC..699..463C"><span id="translatedtitle">Evaluation of <span class="hlt">Active</span> Working <span class="hlt">Fluids</span> for Brayton Cycles in Space Applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Conklin, J. C.; Courville, G. E.; Scott, J. H.</p> <p>2004-02-01</p> <p>The main parameter of interest for space thermal power conversion to electricity is specific power, defined as the total electric power output per unit of system mass, rather than the cycle thermal efficiency. For a closed Brayton cycle, performance with two <span class="hlt">active</span> working <span class="hlt">fluids</span>, nitrogen tetroxide and aluminum chloride, is compared to that with an inert mixture of helium and xenon having a molecular mass of 40. A chemically <span class="hlt">active</span> working <span class="hlt">fluid</span> is defined here as a chemical compound that has a relatively high molecular weight at temperatures appropriate for the compressor inlet and dissociates to a lighter molecular weight <span class="hlt">fluid</span> at typical turbine inlet temperatures. The <span class="hlt">active</span> working <span class="hlt">fluids</span> may have the advantage of a higher net turbomachinery work output and an advantageous enhancement of the heat transfer coefficient in the heat exchangers. The fundamental theory of the <span class="hlt">active</span> working <span class="hlt">fluid</span> concept is presented to demonstrate these potential advantages. Scoping calculations of the heat exchanger mass for a selected spacecraft application of 36.4 kW of electrical power output show that the nitrogen tetroxide <span class="hlt">active</span> working <span class="hlt">fluid</span> has an advantageous 7% to 30% lower mass-to-power ratio than that for the inert noble gas mixture, depending on the allowable turbine inlet temperature. The calculations for the aluminum chloride system suggest only a slight improvement in performance relative to the inert noble gas mixture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/12712202','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/12712202"><span id="translatedtitle">Magmatic events can produce rapid changes in hydrothermal <span class="hlt">vent</span> chemistry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lilley, Marvin D; Butterfield, David A; Lupton, John E; Olson, Eric J</p> <p>2003-04-24</p> <p>The Endeavour segment of the Juan de Fuca ridge is host to one of the most vigorous hydrothermal areas found on the global mid-ocean-ridge system, with five separate <span class="hlt">vent</span> fields located within 15 km along the top of the ridge segment. Over the past decade, the largest of these <span class="hlt">vent</span> fields, the 'Main Endeavour Field', has exhibited a constant spatial gradient in temperature and chloride concentration in its <span class="hlt">vent</span> <span class="hlt">fluids</span>, apparently driven by differences in the nature and extent of subsurface phase separation. This stable situation was disturbed on 8 June 1999 by an earthquake swarm. Owing to the nature of the seismic signals and the lack of new lava flows observed in the area during subsequent dives of the Alvin and Jason submersibles (August-September 1999), the event was interpreted to be tectonic in nature. Here we show that chemical data from hydrothermal <span class="hlt">fluid</span> samples collected in September 1999 and June 2000 strongly suggest that the event was instead volcanic in origin. Volatile data from this event and an earlier one at 9 degrees N on the East Pacific Rise show that such magmatic events can have profound and rapid effects on <span class="hlt">fluid</span>-mineral equilibria, phase separation, 3He/heat ratios and fluxes of volatiles from submarine hydrothermal systems. PMID:12712202</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3683637','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3683637"><span id="translatedtitle">Microbiological characterization of post-eruption “snowblower” <span class="hlt">vents</span> at Axial Seamount, Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Meyer, Julie L.; Akerman, Nancy H.; Proskurowski, Giora; Huber, Julie A.</p> <p>2013-01-01</p> <p>Microbial processes within the subseafloor can be examined during the ephemeral and uncommonly observed phenomena known as snowblower <span class="hlt">venting</span>. Snowblowers are characterized by the large quantity of white floc that is expelled from the seafloor following mid-ocean ridge eruptions. During these eruptions, rapidly cooling lava entrains seawater and hydrothermal <span class="hlt">fluids</span> enriched in geochemical reactants, creating a natural bioreactor that supports a subseafloor microbial “bloom.” Previous studies hypothesized that the eruption-associated floc was made by sulfide-oxidizing bacteria; however, the microbes involved were never identified. Here we present the first molecular analysis combined with microscopy of microbial communities in snowblower <span class="hlt">vents</span> from samples collected shortly after the 2011 eruption at Axial Seamount, an <span class="hlt">active</span> volcano on the Juan de Fuca Ridge. We obtained <span class="hlt">fluid</span> samples and white flocculent material from <span class="hlt">active</span> snowblower <span class="hlt">vents</span> as well as orange flocculent material found on top of newly formed lava flows. Both flocculent types revealed diverse cell types and particulates when examined by phase contrast and scanning electron microscopy (SEM). Distinct archaeal and bacterial communities were detected in each sample type through Illumina tag sequencing of 16S rRNA genes and through sequencing of the sulfide oxidation gene, soxB. In <span class="hlt">fluids</span> and white floc, the dominant bacteria were sulfur-oxidizing Epsilonproteobacteria and the dominant archaea were thermophilic Methanococcales. In contrast, the dominant organisms in the orange floc were Gammaproteobacteria and Thaumarchaeota Marine Group I. In all samples, bacteria greatly outnumbered archaea. The presence of anaerobic methanogens and microaerobic Epsilonproteobacteria in snowblower communities provides evidence that these blooms are seeded by subseafloor microbes, rather than from microbes in bottom seawater. These eruptive events thus provide a unique opportunity to observe subseafloor microbial</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GML....36...15C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GML....36...15C&link_type=ABSTRACT"><span id="translatedtitle">Influence of hydrothermal <span class="hlt">venting</span> on water column properties in the crater of the Kolumbo submarine volcano, Santorini volcanic field (Greece)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Christopoulou, Maria E.; Mertzimekis, Theo J.; Nomikou, Paraskevi; Papanikolaou, Dimitrios; Carey, Steven; Mandalakis, Manolis</p> <p>2016-02-01</p> <p>The Kolumbo submarine volcano, located 7 km northeast of the island of Santorini, is part of Santorini's volcanic complex in the south Aegean Sea, Greece. Kolumbo's last eruption was in 1650 AD. However, a unique and <span class="hlt">active</span> hydrothermal <span class="hlt">vent</span> field has been revealed in the northern part of its crater floor during an oceanographic survey by remotely operated vehicles (ROVs) in 2006. In the present study, conductivity-temperature-depth (CTD) data collected by ROV Hercules during three oceanographic surveys onboard E/V Nautilus in 2010 and 2011 have served to investigate the distribution of physicochemical properties in the water column, as well as their behavior directly over the hydrothermal field. Additional CTD measurements were carried out in volcanic cone 3 (VC3) along the same volcanic chain but located 3 km northeast of Kolumbo where no hydrothermal <span class="hlt">activity</span> has been detected to date. CTD profiles exhibit pronounced anomalies directly above the <span class="hlt">active</span> <span class="hlt">vents</span> on Kolumbo's crater floor. In contrast, VC3 data revealed no such anomalies, essentially resembling open-sea (background) conditions. Steep increases of temperature (e.g., from 16 to 19 °C) and conductivity near the maximum depth (504 m) inside Kolumbo's cone show marked spatiotemporal correlation. Vertical distributions of CTD signatures suggest a strong connection to Kolumbo's morphology, with four distinct zones identified (open sea, turbid flow, invariable state, hydrothermal <span class="hlt">vent</span> field). Additionally, overlaying the near-seafloor temperature measurements on an X-Y coordinate grid generates a detailed 2D distribution of the hydrothermal <span class="hlt">vent</span> field and clarifies the influence of <span class="hlt">fluid</span> discharges in its formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title14-vol1/pdf/CFR-2013-title14-vol1-sec29-975.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title14-vol1/pdf/CFR-2013-title14-vol1-sec29-975.pdf"><span id="translatedtitle">14 CFR 29.975 - Fuel tank <span class="hlt">vents</span> and carburetor vapor <span class="hlt">vents</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fuel tank <span class="hlt">vents</span> and carburetor vapor <span class="hlt">vents</span>. 29.975 Section 29.975 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System § 29.975 Fuel tank <span class="hlt">vents</span> and carburetor vapor <span class="hlt">vents</span>....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title14-vol1/pdf/CFR-2013-title14-vol1-sec25-975.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title14-vol1/pdf/CFR-2013-title14-vol1-sec25-975.pdf"><span id="translatedtitle">14 CFR 25.975 - Fuel tank <span class="hlt">vents</span> and carburetor vapor <span class="hlt">vents</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fuel tank <span class="hlt">vents</span> and carburetor vapor <span class="hlt">vents</span>. 25.975 Section 25.975 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.975 Fuel tank <span class="hlt">vents</span> and carburetor vapor <span class="hlt">vents</span>....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFMOS23C2028S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFMOS23C2028S&link_type=ABSTRACT"><span id="translatedtitle">Noble Gas geochemistry of the newly discovered hydrothermal fields in the Gulf of California: preliminary He-isotope ratios from the Alarcon Rise and Pescadero basin <span class="hlt">vent</span> sites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Spelz, R. M.; Lupton, J. E.; Evans, L. J.; Zierenberg, R. A.; Clague, D. A.; Neumann, F.; Paduan, J. B.</p> <p>2015-12-01</p> <p>Numerous submarine deep-sea hydrothermal <span class="hlt">vents</span> related to volcanic <span class="hlt">activity</span> of the East Pacific Rise (EPR) are situated along the Pacific margins of Mexico. Until recently, <span class="hlt">active</span> hydrothermal <span class="hlt">venting</span> was unknown between the Guaymas Basin and 21°N on the EPR. MBARI's recent oceanographic surveys have added 7 new <span class="hlt">active</span> <span class="hlt">vent</span> sites. In this study, we aimed to sample the high-temperature hydrothermal <span class="hlt">fluids</span> emanating from two distinct <span class="hlt">vent</span> sites, named Meyibo and Auka, located in the Alarcon Rise and Pescadero Basin, respectively. Mantle-derived He have long been identified in hydrothermal <span class="hlt">fluid</span> releases. The presence of He in aqueous <span class="hlt">fluids</span> with 3He/4He ratios greater than in-situ production values (~0.05 RA, where RA = air He or 1.4 x 10-6) indicates the presence of mantle-derived melts. Preliminary analyses of He-isotope ratios derived from the newly discovered Meyibo and Auka hydrothermal fields show high 3He/4He ratios (~8RA), typical of MORB's. Auka <span class="hlt">vent</span> field, characterized by chimneys composed of light carbonate minerals and oil-like hydrocarbons, and temperatures between 250-290oC, show average values of ~7.87RA. In contrast, the black-smokers at the Meyibo field, composed of dark sulfide minerals and temperatures over 350oC, yielded a higher He ratio of ~8.24RA. Recently, it has become clear that regional maximum mantle He values correlate with the velocity structure in the mantle, therefore, He has the potential to map regions of the underlying mantle that are undergoing partial melting. Seismic records could then be compared with the geochemical He ratio signal and supply information regarding tectonics and other processes involved in the generation of these gases. The data presented here will be completing a totally new inventory of He results from hydrothermal <span class="hlt">vents</span> in the EPR and fault-termination basins distributed along the P-NA plate boundary in the Gulf of California. The results will be further coupled with the analysis of other geochemical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EGUGA..1616710Y&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EGUGA..1616710Y&link_type=ABSTRACT"><span id="translatedtitle">Dynamic drivers of a shallow-water hydrothermal <span class="hlt">vent</span> ecogeochemical system (Milos, Eastern Mediterranean)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yücel, Mustafa; Sievert, Stefan; Giovanelli, Donato; Foustoukos, Dionysis; DeForce, Emelia; Thomas, François; Vetriani, Constantino; Le Bris, Nadine</p> <p>2014-05-01</p> <p>Shallow-water hydrothermal <span class="hlt">vents</span> share many characteristics with their deep-sea analogs. However, despite ease of access, much less is known about the dynamics of these systems. Here, we report on the spatial and temporal chemical variability of a shallow-water <span class="hlt">vent</span> system at Paleochori Bay, Milos Island, Greece, and on the bacterial and archaeal diversity of associated sandy sediments. Our multi-analyte voltammetric profiles of dissolved O2 and hydrothermal tracers (e.g. Fe2+, FeSaq, Mn2+) on sediment cores taken along a transect in hydrothermally affected sediments indicate three different areas: the central <span class="hlt">vent</span> area (highest temperature) with a deeper penetration of oxygen into the sediment, and a lack of dissolved Fe2+ and Mn2+; a middle area (0.5 m away) rich in dissolved Fe2+ and Mn2+ (exceeding 2 mM) and high free sulfide with potential for microbial sulfide oxidation as suggested by the presence of white mats at the sediment surface; and, finally, an outer rim area (1-1.5 m away) with lower concentrations of Fe2+ and Mn2+ and higher signals of FeSaq, indicating an aged hydrothermal <span class="hlt">fluid</span> contribution. In addition, high-frequency temperature series and continuous in situ H2S measurements with voltammetric sensors over a 6-day time period at a distance 0.5 m away from the <span class="hlt">vent</span> center showed substantial temporal variability in temperature (32 to 46 ºC ) and total sulfide (488 to 1329 µM) in the upper sediment layer. Analysis of these data suggests that tides, winds, and abrupt geodynamic events generate intermittent mixing conditions lasting for several hours to days. Despite substantial variability, the concentration of sulfide available for chemoautotrophic microbes remained high. These findings are consistent with the predominance of Epsilonproteobacteria in the hydrothermally influenced sediments Diversity and metagenomic analyses on sediments and biofilm collected along a transect from the center to the outer rim of the <span class="hlt">vent</span> provide further insights on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20866262','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20866262"><span id="translatedtitle">Sheared <span class="hlt">active</span> <span class="hlt">fluids</span>: thickening, thinning, and vanishing viscosity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Giomi, Luca; Liverpool, Tanniemola B; Marchetti, M Cristina</p> <p>2010-05-01</p> <p>We analyze the behavior of a suspension of <span class="hlt">active</span> polar particles under shear. In the absence of external forces, orientationally ordered <span class="hlt">active</span> particles are known to exhibit a transition to a state of nonuniform polarization and spontaneous flow. Such a transition results from the interplay between elastic stresses, due to the liquid crystallinity of the suspension, and internal <span class="hlt">active</span> stresses. In the presence of an external shear, we find an extremely rich variety of phenomena, including an effective reduction (increase) in the apparent viscosity depending on the nature of the <span class="hlt">active</span> stresses and the flow-alignment property of the particles, as well as more exotic behaviors such as a nonmonotonic stress-strain-rate relation and yield stress for large <span class="hlt">activities</span>. PMID:20866262</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16675106','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16675106"><span id="translatedtitle">CFD analysis of gas explosions <span class="hlt">vented</span> through relief pipes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ferrara, G; Di Benedetto, A; Salzano, E; Russo, G</p> <p>2006-09-21</p> <p><span class="hlt">Vent</span> devices for gas and dust explosions are often ducted to safe locations by means of relief pipes. However, the presence of the duct increases the severity of explosion if compared to simply <span class="hlt">vented</span> vessels (i.e. compared to cases where no duct is present). Besides, the identification of the key phenomena controlling the violence of explosion has not yet been gained. Multidimensional models coupling, mass, momentum and energy conservation equations can be valuable tools for the analysis of such complex explosion phenomena. In this work, gas explosions <span class="hlt">vented</span> through ducts have been modelled by a two-dimensional (2D) axi-symmetric computational <span class="hlt">fluid</span> dynamic (CFD) model based on the unsteady Reynolds Averaged Navier Stokes (RANS) approach in which the laminar, flamelet and distributed combustion models have been implemented. Numerical test have been carried out by varying ignition position, duct diameter and length. Results have evidenced that the severity of ducted explosions is mainly driven by the vigorous secondary explosion occurring in the duct (burn-up) rather than by the duct flow resistance or acoustic enhancement. Moreover, it has been found out that the burn-up affects explosion severity due to the reduction of <span class="hlt">venting</span> rate rather than to the burning rate enhancement through turbulization. PMID:16675106</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS42A..03F&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS42A..03F&link_type=ABSTRACT"><span id="translatedtitle">Hydrocarbon flux from natural deepwater Gulf of Mexico <span class="hlt">vents</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Flemings, P. B.; Smith, A. J.</p> <p>2012-12-01</p> <p>Natural <span class="hlt">vents</span> that expel water and hydrocarbons are present on continental margins around the world. The expelled <span class="hlt">fluids</span> support biological <span class="hlt">vent</span> communities, escape to the ocean and atmosphere, and may contribute significantly to oceanic and atmospheric carbon budgets. We describe two <span class="hlt">vents</span> in the northern Gulf of Mexico (GoM) at lease blocks MC852/853 and GB425 that have significant flow, high salinities, and elevated temperatures. We use a steady state multi-phase flow model and show that there is a unique water and hydrocarbon flux that simulates the observed salinity and temperature. We estimate the hydrocarbon flux at each <span class="hlt">vent</span> to be 2.0-9.9x104 t yr-1 and 1.7-7.1x104 t yr-1, respectively. We extrapolate these results and estimate the hydrocarbon flux from the entire Gulf of Mexico to be 9.7-55x106 t yr-1. This flux is at least 50x greater than previous estimates11 and is 6-40% of the hydrocarbon flux from the Macondo oil spill. Large natural seepage may inoculate marine basins such as the Gulf of Mexico from oil spills like the 2010 Deepwater Horizon blowout by sustaining populations of hydrocarbon-degrading bacteria.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015DSRII.121..193G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015DSRII.121..193G&link_type=ABSTRACT"><span id="translatedtitle">Variation in the diets of hydrothermal <span class="hlt">vent</span> gastropods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Govenar, Breea; Fisher, Charles R.; Shank, Timothy M.</p> <p>2015-11-01</p> <p>A prevailing paradigm of hydrothermal <span class="hlt">vent</span> ecology is that primary consumers feed on chemoautotrophic bacteria. However, for the purposes of reconstructing <span class="hlt">vent</span> food webs and for tracking energy flow from the generation of rock and <span class="hlt">fluid</span> chemistry through primary/ secondary productivity and consumption to the overlying water column, it remains unclear which consumers feed on which bacteria. In paired analyses of carbon and nitrogen tissue stable isotope values with unique 16S rRNA sequences from the stomach contents, we determined that two species of gastropod grazers appear to feed on epsilon-proteobacteria, while two other species have more diverse diets, including one species that consumes alpha-proteobacteria, planctomycetes, and non-green sulfur bacteria. Different carbon fixation pathways used by epsilon- and alpha-proteobacteria may account for the variation in the carbon stable isotope values among the consumers. Furthermore, our results indicate that trophic specialization and niche partitioning may contribute to the distribution and abundance of <span class="hlt">vent</span>-endemic gastropods and support the hypothesis that consumers in the warmer habitats commonly feed on epsilon-proteobacteria that use the rTCA cycle, while in the cooler habitats they feed on additional bacteria that use the CBB cycle. These results suggest that the phylogenetic and metabolic diversity of free-living bacteria may play an important and previously overlooked role in facilitating species coexistence among primary consumers at hydrothermal <span class="hlt">vents</span> and other chemosynthesis-based ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.V72A1288D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.V72A1288D"><span id="translatedtitle">A Retrievable Mineral Microcosm for Examining Microbial Colonization and Mineral Precipitation at Seafloor Hydrothermal <span class="hlt">Vents</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dunn, E. E.; Holloway, J. R.; Cary, S.; Voglesonger, K. M.; Ashbridge, D. A.; O'Day, P. A.</p> <p>2002-12-01</p> <p>Although seafloor hydrothermal <span class="hlt">vent</span> environments are known to support thriving ecosystems, the microscale physical and chemical environment suitable for microbial colonization and the identity of pioneering organisms is unknown. Because of the fragility of young chimneys and their ephemeral nature, novel methods for sample retrieval and analysis are required. The mineral microcosm consists of four titanium mesh chambers containing crushed minerals mounted on a titanium base that allows for <span class="hlt">fluid</span> flow through the chambers. The chambers can be filled with different minerals or mineral mixtures (or no minerals) to supply different substrates for microbial colonization and different local microenvironments as minerals react with the surrounding <span class="hlt">fluids</span>. The device sets on top of an <span class="hlt">active</span> hydrothermal <span class="hlt">vent</span> for a period of days to weeks to allow colonization and mineral reaction. The mineral microcosm was deployed during the Atlantis/Alvin Extreme 2001 Cruise (Oct.- Nov.,2001) to 9° 50'N on the East Pacific Rise a total of three times, for ~ 24, ~ 96, and ~ 48 hours each. It was deployed in two different environments, twice in lower temperature (<300°C), diffuse-flow environments and once (for ~96 hours) in a higher temperature black smoker environment (>350°C).Seed minerals included sulfides, sulfates, magnetite, apatite, and quartz, both individually and in mixtures. In the first 24-hour deployment, dissolution of anhydrite but not sulfide minerals within the chambers indicated high temperatures in chamber interiors and rapid reaction rates. Temperatures measured on chamber exteriors before retrieval ranged from 4° -98°C. The 96-hour deployment on a hot <span class="hlt">vent</span> (<span class="hlt">fluid</span> ~370°C before deployment) resulted in extensive mineral precipitation and chimney growth inside the mineral chambers, on the outer surfaces of the chambers, and on the platform as a whole, creating micro-chimneys several centimeters tall. The young chimneys were mainly composed of pyrite with lesser</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFM.B43G0496O&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFM.B43G0496O&link_type=ABSTRACT"><span id="translatedtitle">Microbial Primary Productivity in Hydrothermal <span class="hlt">Vent</span> Chimneys at Middle Valley, Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olins, H. C.; Rogers, D.; Frank, K. L.; Girguis, P. R.; Vidoudez, C.</p> <p>2012-12-01</p> <p>Chemosynthetic primary productivity supports hydrothermal <span class="hlt">vent</span> ecosystems, but the extent of that productivity has not been well measured. To examine the role that environmental temperature plays in controlling carbon fixation rates, and to assess the degree to which microbial community composition, in situ geochemistry, and mineralogy influence carbon fixation, we conducted a series of shipboard incubations across a range of temperatures (4, 25, 50 and 90°C) and at environmentally relevant geochemical conditions using material recovered from three hydrothermal <span class="hlt">vent</span> chimneys in the Middle Valley hydrothermal <span class="hlt">vent</span> field (Juan de Fuca Ridge). Net rates of carbon fixation (CFX) were greatest at lower temperatures, and were similar among structures. Rates did not correlate with the mineralogy or the geochemical composition of the high temperature <span class="hlt">fluids</span> at each chimney. No obvious patterns of association were observed between carbon fixation rates and microbial community composition. Abundance of selected functional genes related to different carbon fixation pathway exhibited striking differences among the three study sites, but did not correlate with rates. Natural carbon isotope ratios implicate the Calvin Benson Bassham Cycle as the dominant mechanism of primary production in these systems, despite the abundance of genes related to other pathways (and presumably some degree of <span class="hlt">activity</span>). Together these data reveal that primary productivity by endolithic communities does not exhibit much variation among these chimneys, and further reveal that microbial <span class="hlt">activity</span> cannot easily be related to mineralogical and geochemical assessments that are made at a coarser scale. Indeed, the relationships between carbon fixation rates and community composition/functional gene abundance were also likely obfuscated by differences in scale at which these measurements were made. Regardless, these data reveal the degree to which endolithic, anaerobic carbon fixation contributes to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20099811','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20099811"><span id="translatedtitle">Deep-sea hydrothermal <span class="hlt">vents</span>: potential hot spots for natural products discovery?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thornburg, Christopher C; Zabriskie, T Mark; McPhail, Kerry L</p> <p>2010-03-26</p> <p>Deep-sea hydrothermal <span class="hlt">vents</span> are among the most extreme and dynamic environments on Earth. However, islands of highly dense and biologically diverse communities exist in the immediate vicinity of hydrothermal <span class="hlt">vent</span> flows, in stark contrast to the surrounding bare seafloor. These communities comprise organisms with distinct metabolisms based on chemosynthesis and growth rates comparable to those from shallow water tropical environments, which have been rich sources of biologically <span class="hlt">active</span> natural products. The geological setting and geochemical nature of deep-sea <span class="hlt">vents</span> that impact the biogeography of <span class="hlt">vent</span> organisms, chemosynthesis, and the known biological and metabolic diversity of Eukarya, Bacteria, and Archaea, including the handful of natural products isolated to date from deep-sea <span class="hlt">vent</span> organisms, are considered here in an assessment of deep-sea hydrothermal <span class="hlt">vents</span> as potential hot spots for natural products investigations. Of critical importance too are the logistics of collecting deep <span class="hlt">vent</span> organisms, opportunities for re-collection considering the stability and longevity of <span class="hlt">vent</span> sites, and the ability to culture natural product-producing deep <span class="hlt">vent</span> organisms in the laboratory. New cost-effective technologies in deep-sea research and more advanced molecular techniques aimed at screening a more inclusive genetic assembly are poised to accelerate natural product discoveries from these microbial diversity hot spots. PMID:20099811</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.8108D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.8108D"><span id="translatedtitle">Carbon fluxes from hydrothermal <span class="hlt">vents</span> off Milos, Aegean Volcanic Arc, and the influence of <span class="hlt">venting</span> on the surrounding ecosystem.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dando, Paul; Aliani, Stefano; Bianchi, Nike; Kennedy, Hilary; Linke, Peter; Morri, Carla</p> <p>2014-05-01</p> <p>The island of Milos, in the Aegean Sea, has extensive hydrothermal fields to the east and southeast of the island with additional <span class="hlt">venting</span> areas near the entrance to and within the central caldera. A calculation of the total area of the <span class="hlt">vent</span> fields, based on ship and aerial surveys, suggested that the hydrothermal fields occupy 70 km2, twice the area previously estimated. The <span class="hlt">vents</span> ranged in water depth from the intertidal to 300 m. As a result of the low depths there was abundant free gas release: in places water boiled on the seabed. The stream of gas bubbles rising through the sandy seabed drove a shallow re-circulation of bottom seawater. The majority of the water released with the gas, with a mean pH of 5.5, was re-circulated bottom water that had become acidified in contact with CO2 gas and was often diluted by admixture with the vapour phase from the deeper <span class="hlt">fluids</span>. The major component of the free gas, 80%, was CO2, with an estimated total flux of 1.5-7.5 x 1012 g a-1. The methane flux, by comparison, was of the order of 1010 g a.-1 Using methane as a tracer it was shown that the major gas export from the <span class="hlt">vents</span> was below the thermocline towards the southwest, in agreement with the prevailing currents. Areas of hydrothermal brine seepage occurred between the gas <span class="hlt">vents</span> and occasional brine pools were observed in seabed depressions. Under relatively calm conditions, many of the brine seeps were covered by thick minero-bacterial mats consisting of silica and sulphur and surrounded by mats of diatoms and cyanobacteria. The minerals were not deposited in the absence of bacteria. Storms disrupted the mats, leading to an export of material to the surrounding area. Stable isotope data from sediments and sediment trap material suggested that exported POM was processed by zooplankton. The combined effects of the geothermal heating of the seabed, the large gas flux, variation in the <span class="hlt">venting</span> and the effect of the brine seeps had a dramatic effect on the surrounding</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED477324.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED477324.pdf"><span id="translatedtitle">Living with the Heat. Submarine Ring of Fire--Grades 5-6. Hydrothermal <span class="hlt">Vent</span> Ecology.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>National Oceanic and Atmospheric Administration (DOC), Rockville, MD.</p> <p></p> <p>This <span class="hlt">activity</span> is designed to teach about hydrothermal <span class="hlt">vent</span> ecology. Students are expected to describe how hydrothermal <span class="hlt">vents</span> are formed and characterize the physical conditions at these sites, explain chemosynthesis and contrast this process with photosynthesis, identify autotrophic bacteria as the basis for food webs in hydrothermal vent…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4393452','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4393452"><span id="translatedtitle">Quantitative PCR Analysis of Functional Genes in Iron-Rich Microbial Mats at an <span class="hlt">Active</span> Hydrothermal <span class="hlt">Vent</span> System (Lō'ihi Seamount, Hawai'i)</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jesser, Kelsey J.; Fullerton, Heather; Hager, Kevin W.</p> <p>2015-01-01</p> <p>The chemolithotrophic Zetaproteobacteria represent a novel class of Proteobacteria which oxidize Fe(II) to Fe(III) and are the dominant bacterial population in iron-rich microbial mats. Zetaproteobacteria were first discovered at Lō'ihi Seamount, located 35 km southeast off the big island of Hawai'i, which is characterized by low-temperature diffuse hydrothermal <span class="hlt">venting</span>. Novel nondegenerate quantitative PCR (qPCR) assays for genes associated with microbial nitrogen fixation, denitrification, arsenic detoxification, Calvin-Benson-Bassham (CBB), and reductive tricarboxylic acid (rTCA) cycles were developed using selected microbial mat community-derived metagenomes. Nitrogen fixation genes were not detected, but all other functional genes were present. This suggests that arsenic detoxification and denitrification processes are likely cooccurring in addition to two modes of carbon fixation. Two groups of microbial mat community types were identified by terminal restriction fragment length polymorphism (T-RFLP) and were further described based on qPCR data for zetaproteobacterial abundance and carbon fixation mode preference. qPCR variance was associated with mat morphology but not with temperature or sample site. Geochemistry data were significantly associated with sample site and mat morphology. Together, these qPCR assays constitute a functional gene signature for iron microbial mat communities across a broad array of temperatures, mat types, chemistries, and sampling sites at Lō'ihi Seamount. PMID:25681182</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25681182','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25681182"><span id="translatedtitle">Quantitative PCR analysis of functional genes in iron-rich microbial mats at an <span class="hlt">active</span> hydrothermal <span class="hlt">vent</span> system (Lō'ihi Seamount, Hawai'i).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jesser, Kelsey J; Fullerton, Heather; Hager, Kevin W; Moyer, Craig L</p> <p>2015-05-01</p> <p>The chemolithotrophic Zetaproteobacteria represent a novel class of Proteobacteria which oxidize Fe(II) to Fe(III) and are the dominant bacterial population in iron-rich microbial mats. Zetaproteobacteria were first discovered at Lō'ihi Seamount, located 35 km southeast off the big island of Hawai'i, which is characterized by low-temperature diffuse hydrothermal <span class="hlt">venting</span>. Novel nondegenerate quantitative PCR (qPCR) assays for genes associated with microbial nitrogen fixation, denitrification, arsenic detoxification, Calvin-Benson-Bassham (CBB), and reductive tricarboxylic acid (rTCA) cycles were developed using selected microbial mat community-derived metagenomes. Nitrogen fixation genes were not detected, but all other functional genes were present. This suggests that arsenic detoxification and denitrification processes are likely cooccurring in addition to two modes of carbon fixation. Two groups of microbial mat community types were identified by terminal restriction fragment length polymorphism (T-RFLP) and were further described based on qPCR data for zetaproteobacterial abundance and carbon fixation mode preference. qPCR variance was associated with mat morphology but not with temperature or sample site. Geochemistry data were significantly associated with sample site and mat morphology. Together, these qPCR assays constitute a functional gene signature for iron microbial mat communities across a broad array of temperatures, mat types, chemistries, and sampling sites at Lō'ihi Seamount. PMID:25681182</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3483289','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3483289"><span id="translatedtitle">Microdistribution of Faunal Assemblages at Deep-Sea Hydrothermal <span class="hlt">Vents</span> in the Southern Ocean</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Marsh, Leigh; Copley, Jonathan T.; Huvenne, Veerle A. I.; Linse, Katrin; Reid, William D. K.; Rogers, Alex D.; Sweeting, Christopher J.; Tyler, Paul A.</p> <p>2012-01-01</p> <p>Chemosynthetic primary production by microbes supports abundant faunal assemblages at deep-sea hydrothermal <span class="hlt">vents</span>, with zonation of invertebrate species typically occurring along physico-chemical gradients. Recently discovered <span class="hlt">vent</span> fields on the East Scotia Ridge (ESR) in the Southern Ocean represent a new province of <span class="hlt">vent</span> biogeography, but the spatial dynamics of their distinct fauna have yet to be elucidated. This study determines patterns of faunal zonation, species associations, and relationships between faunal microdistribution and hydrothermal <span class="hlt">activity</span> in a <span class="hlt">vent</span> field at a depth of 2,400 m on the ESR. Remotely operated vehicle (ROV) dives obtained high-definition imagery of three chimney structures with varying levels of hydrothermal <span class="hlt">activity</span>, and a mosaic image of >250 m2 of seafloor co-registered with temperature measurements. Analysis of faunal microdistribution within the mosaiced seafloor reveals a consistent pattern of faunal zonation with increasing distance from <span class="hlt">vent</span> sources and peak temperatures. Assemblages closest to <span class="hlt">vent</span> sources are visibly dominated by a new species of anomuran crab, Kiwa n. sp. (abundance >700 individuals m−2), followed by a peltospiroid gastropod (>1,500 individuals m−2), eolepadid barnacle (>1,500 individuals m−2), and carnivorous actinostolid anemone (>30 individuals m−2). Peripheral fauna are not dominated by a single taxon, but include predatory and scavenger taxa such as stichasterid seastars, pycnogonids and octopus. Variation in faunal microdistribution on chimneys with differing levels of <span class="hlt">activity</span> suggests a possible successional sequence for <span class="hlt">vent</span> fauna in this new biogeographic province. An increase in δ34S values of primary consumers with distance from <span class="hlt">vent</span> sources, and variation in their δ13C values also indicate possible zonation of nutritional modes of the <span class="hlt">vent</span> fauna. By using ROV videography to obtain a high-resolution representation of a <span class="hlt">vent</span> environment over a greater extent than previous studies</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23144754','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23144754"><span id="translatedtitle">Microdistribution of faunal assemblages at deep-sea hydrothermal <span class="hlt">vents</span> in the Southern Ocean.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marsh, Leigh; Copley, Jonathan T; Huvenne, Veerle A I; Linse, Katrin; Reid, William D K; Rogers, Alex D; Sweeting, Christopher J; Tyler, Paul A</p> <p>2012-01-01</p> <p>Chemosynthetic primary production by microbes supports abundant faunal assemblages at deep-sea hydrothermal <span class="hlt">vents</span>, with zonation of invertebrate species typically occurring along physico-chemical gradients. Recently discovered <span class="hlt">vent</span> fields on the East Scotia Ridge (ESR) in the Southern Ocean represent a new province of <span class="hlt">vent</span> biogeography, but the spatial dynamics of their distinct fauna have yet to be elucidated. This study determines patterns of faunal zonation, species associations, and relationships between faunal microdistribution and hydrothermal <span class="hlt">activity</span> in a <span class="hlt">vent</span> field at a depth of 2,400 m on the ESR. Remotely operated vehicle (ROV) dives obtained high-definition imagery of three chimney structures with varying levels of hydrothermal <span class="hlt">activity</span>, and a mosaic image of >250 m(2) of seafloor co-registered with temperature measurements. Analysis of faunal microdistribution within the mosaiced seafloor reveals a consistent pattern of faunal zonation with increasing distance from <span class="hlt">vent</span> sources and peak temperatures. Assemblages closest to <span class="hlt">vent</span> sources are visibly dominated by a new species of anomuran crab, Kiwa n. sp. (abundance >700 individuals m(-2)), followed by a peltospiroid gastropod (>1,500 individuals m(-2)), eolepadid barnacle (>1,500 individuals m(-2)), and carnivorous actinostolid anemone (>30 individuals m(-2)). Peripheral fauna are not dominated by a single taxon, but include predatory and scavenger taxa such as stichasterid seastars, pycnogonids and octopus. Variation in faunal microdistribution on chimneys with differing levels of <span class="hlt">activity</span> suggests a possible successional sequence for <span class="hlt">vent</span> fauna in this new biogeographic province. An increase in δ(34)S values of primary consumers with distance from <span class="hlt">vent</span> sources, and variation in their δ(13)C values also indicate possible zonation of nutritional modes of the <span class="hlt">vent</span> fauna. By using ROV videography to obtain a high-resolution representation of a <span class="hlt">vent</span> environment over a greater extent than previous studies</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21734728','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21734728"><span id="translatedtitle">Expression patterns of mRNAs for methanotrophy and thiotrophy in symbionts of the hydrothermal <span class="hlt">vent</span> mussel Bathymodiolus puteoserpentis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wendeberg, Annelie; Zielinski, Frank U; Borowski, Christian; Dubilier, Nicole</p> <p>2012-01-01</p> <p>The hydrothermal <span class="hlt">vent</span> mussel Bathymodiolus puteoserpentis (Mytilidae) from the Mid-Atlantic Ridge hosts symbiotic sulfur- and methane-oxidizing bacteria in its gills. In this study, we investigated the <span class="hlt">activity</span> and distribution of these two symbionts in juvenile mussels from the Logatchev hydrothermal <span class="hlt">vent</span> field (14°45'N Mid-Atlantic Ridge). Expression patterns of two key genes for chemosynthesis were examined: pmoA (encoding subunit A of the particulate methane monooxygenase) as an indicator for methanotrophy, and aprA (encoding the subunit A of the dissimilatory adenosine-5'-phosphosulfate reductase) as an indicator for thiotrophy. Using simultaneous fluorescence in situ hybridization (FISH) of rRNA and mRNA we observed highest mRNA FISH signals toward the ciliated epithelium where seawater enters the gills. The levels of mRNA expression differed between individual specimens collected in a single grab from the same sampling site, whereas no obvious differences in symbiont abundance or distribution were observed. We propose that the symbionts respond to the steep temporal and spatial gradients in methane, reduced sulfur compounds and oxygen by modifying gene transcription, whereas changes in symbiont abundance and distribution take much longer than regulation of mRNA expression and may only occur in response to long-term changes in <span class="hlt">vent</span> <span class="hlt">fluid</span> geochemistry. PMID:21734728</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5162004','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5162004"><span id="translatedtitle">Electrochemical cell having a safety <span class="hlt">vent</span> closure</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zupancic, R.L.</p> <p>1982-05-11</p> <p>A safety blow-out <span class="hlt">vent</span> closure for galvanic cells, such as nonaqueous oxyhalide cells, which comprises the employment of a conductive tubular member secured to the cell's housing and surrounding a <span class="hlt">vent</span> orifice in the cell's housing and wherein a deformable member is force-fitted in said <span class="hlt">vent</span> orifice and adapted to at least partially be ejected from the <span class="hlt">vent</span> orifice upon the build up of a predetermined internal gas pressure within the cell. The invention is also directed to a method for assembling an electrochemical cell with the above-described safety <span class="hlt">vent</span> closure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4820435','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4820435"><span id="translatedtitle">Nanocalorimetric Characterization of Microbial <span class="hlt">Activity</span> in Deep Subsurface Oceanic Crustal <span class="hlt">Fluids</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Robador, Alberto; LaRowe, Douglas E.; Jungbluth, Sean P.; Lin, Huei-Ting; Rappé, Michael S.; Nealson, Kenneth H.; Amend, Jan P.</p> <p>2016-01-01</p> <p>Although <span class="hlt">fluids</span> within the upper oceanic basaltic crust harbor a substantial fraction of the total prokaryotic cells on Earth, the energy needs of this microbial population are unknown. In this study, a nanocalorimeter (sensitivity down to 1.2 nW ml-1) was used to measure the enthalpy of microbially catalyzed reactions as a function of temperature in samples from two distinct crustal <span class="hlt">fluid</span> aquifers. Microorganisms in unamended, warm (63°C) and geochemically altered anoxic <span class="hlt">fluids</span> taken from 292 meters sub-basement (msb) near the Juan de Fuca Ridge produced 267.3 mJ of heat over the course of 97 h during a step-wise isothermal scan from 35.5 to 85.0°C. Most of this heat signal likely stems from the germination of thermophilic endospores (6.66 × 104 cells ml-1<span class="hlt">FLUID</span>) and their subsequent metabolic <span class="hlt">activity</span> at temperatures greater than 50°C. The average cellular energy consumption (5.68 pW cell-1) reveals the high metabolic potential of a dormant community transported by <span class="hlt">fluids</span> circulating through the ocean crust. By contrast, samples taken from 293 msb from cooler (3.8°C), relatively unaltered oxic <span class="hlt">fluids</span>, produced 12.8 mJ of heat over the course of 14 h as temperature ramped from 34.8 to 43.0°C. Corresponding cell-specific energy turnover rates (0.18 pW cell-1) were converted to oxygen uptake rates of 24.5 nmol O2 ml-1<span class="hlt">FLUID</span> d-1, validating previous model predictions of microbial <span class="hlt">activity</span> in this environment. Given that the investigated <span class="hlt">fluids</span> are characteristic of expansive areas of the upper oceanic crust, the measured metabolic heat rates can be used to constrain boundaries of habitability and microbial <span class="hlt">activity</span> in the oceanic crust. PMID:27092118</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27092118','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27092118"><span id="translatedtitle">Nanocalorimetric Characterization of Microbial <span class="hlt">Activity</span> in Deep Subsurface Oceanic Crustal <span class="hlt">Fluids</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Robador, Alberto; LaRowe, Douglas E; Jungbluth, Sean P; Lin, Huei-Ting; Rappé, Michael S; Nealson, Kenneth H; Amend, Jan P</p> <p>2016-01-01</p> <p>Although <span class="hlt">fluids</span> within the upper oceanic basaltic crust harbor a substantial fraction of the total prokaryotic cells on Earth, the energy needs of this microbial population are unknown. In this study, a nanocalorimeter (sensitivity down to 1.2 nW ml(-1)) was used to measure the enthalpy of microbially catalyzed reactions as a function of temperature in samples from two distinct crustal <span class="hlt">fluid</span> aquifers. Microorganisms in unamended, warm (63°C) and geochemically altered anoxic <span class="hlt">fluids</span> taken from 292 meters sub-basement (msb) near the Juan de Fuca Ridge produced 267.3 mJ of heat over the course of 97 h during a step-wise isothermal scan from 35.5 to 85.0°C. Most of this heat signal likely stems from the germination of thermophilic endospores (6.66 × 10(4) cells ml(-1) <span class="hlt">FLUID</span>) and their subsequent metabolic <span class="hlt">activity</span> at temperatures greater than 50°C. The average cellular energy consumption (5.68 pW cell(-1)) reveals the high metabolic potential of a dormant community transported by <span class="hlt">fluids</span> circulating through the ocean crust. By contrast, samples taken from 293 msb from cooler (3.8°C), relatively unaltered oxic <span class="hlt">fluids</span>, produced 12.8 mJ of heat over the course of 14 h as temperature ramped from 34.8 to 43.0°C. Corresponding cell-specific energy turnover rates (0.18 pW cell(-1)) were converted to oxygen uptake rates of 24.5 nmol O2 ml(-1) <span class="hlt">FLUID</span> d(-1), validating previous model predictions of microbial <span class="hlt">activity</span> in this environment. Given that the investigated <span class="hlt">fluids</span> are characteristic of expansive areas of the upper oceanic crust, the measured metabolic heat rates can be used to constrain boundaries of habitability and microbial <span class="hlt">activity</span> in the oceanic crust. PMID:27092118</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMOS13G..08G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS13G..08G"><span id="translatedtitle">Geological and geochemical controls on the distribution of Alviniconcha <span class="hlt">vent</span> snail symbioses: Have we finally linked mantle to microbe? (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Girguis, P. R.; Beinart, R.; Sanders, J.; Seewald, J.</p> <p>2010-12-01</p> <p>Gastropods of the genus Alviniconcha are found at hydrothermal <span class="hlt">vent</span> fields in the Western Pacific, and have been reported to associate with either γ- or ɛ-Proteobacterial endosymbionts. These symbionts harness energy from the oxidation of chemicals in <span class="hlt">vent</span> <span class="hlt">fluid</span> to fix inorganic carbon and are the primary source of nutrition for the holobiont. An extensive sampling effort during a recent expedition to the Eastern Lau Spreading Center (ELSC) has revealed that Alviniconcha host both previously observed symbiont types, as well as an additional γ- proteobacterial symbiont. Specifically, we collected 266 Alviniconcha individuals from four <span class="hlt">vent</span> fields along the spreading center (30-140km apart) which span the north-south transition from fast spreading, basalt-hosted to slower spreading, andesite-hosted fields. <span class="hlt">Vent</span> <span class="hlt">fluids</span> from each field were also analyzed for the abundances of aqueous volatile and non-volatile species. The symbionts of all collected Alviniconcha were genotyped using restriction fragment length polymorphism analysis as well as quantitative PCR. Individuals were found to primarily host one of the three symbiont genotypes (two γ- and one ɛ-Proteobacteria). Notably, we found that the two northern-most sites (basalt-hosted <span class="hlt">vents</span>) were greatly dominated by individuals with the ɛ-Proteobacterial symbiont, while the two southern sites (andesite-hosted <span class="hlt">vents</span>) were dominated by individuals hosting one of the two γ-Proteobacterial symbionts. This pattern corresponds to differences in the aqueous chemistry of the <span class="hlt">vent</span> <span class="hlt">fluids</span> along the spreading center. In particular, we have measured higher concentrations of hydrogen and hydrogen sulfide in the <span class="hlt">vent</span> <span class="hlt">fluids</span> at the northern sites than in the <span class="hlt">fluids</span> of the southern sites. We posit that <span class="hlt">vent</span> chemistry -which is influenced by subsurface water-rock interactions- may be influencing the dominance of each symbiont type along the ELSC. The putative implications for the role that geology and geochemistry plays in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26337149','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26337149"><span id="translatedtitle">Bacterial abundance, processes and diversity responses to acidification at a coastal CO2 <span class="hlt">vent</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Burrell, Tim J; Maas, Elizabeth W; Hulston, Debbie A; Law, Cliff S</p> <p>2015-09-01</p> <p>Shallow CO2 <span class="hlt">vents</span> are used as natural laboratories to study biological responses to ocean acidification, and so it is important to determine whether pH is the primary driver of bacterial processes and community composition, or whether other variables associated with <span class="hlt">vent</span> water have a significant influence. Water from a CO2 <span class="hlt">vent</span> (46 m, Bay of Plenty, New Zealand) was compared to reference water from an upstream control site, and also to control water acidified to the same pH as the <span class="hlt">vent</span> water. After 84 h, both <span class="hlt">vent</span> and acidified water exhibited higher potential bulk water and cell-specific glucosidase <span class="hlt">activity</span> relative to control water, whereas cell-specific protease <span class="hlt">activities</span> were similar. However, bulk <span class="hlt">vent</span> water glucosidase <span class="hlt">activity</span> was double that of the acidified water, as was bacterial secondary production in one experiment, suggesting that pH was not the only factor affecting carbohydrate hydrolysis. In addition, there were significant differences in bacterial community composition in the <span class="hlt">vent</span> water relative to the control and acidified water after 84 h, including the presence of extremophiles which may influence carbohydrate degradation. This highlights the importance of characterizing microbial processes and community composition in CO2 <span class="hlt">vent</span> emissions, to confirm that they represent robust analogues for the future acidified ocean. PMID:26337149</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26769011','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26769011"><span id="translatedtitle">Spontaneous flow in polar <span class="hlt">active</span> <span class="hlt">fluids</span>: the effect of a phenomenological self propulsion-like term.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bonelli, Francesco; Gonnella, Giuseppe; Tiribocchi, Adriano; Marenduzzo, Davide</p> <p>2016-01-01</p> <p>We present hybrid lattice Boltzmann simulations of extensile and contractile <span class="hlt">active</span> <span class="hlt">fluids</span> where we incorporate phenomenologically the tendency of <span class="hlt">active</span> particles such as cell and bacteria, to move, or swim, along the local orientation. Quite surprisingly, we show that the interplay between alignment and <span class="hlt">activity</span> can lead to completely different results, according to geometry (periodic boundary conditions or confinement between flat walls) and nature of the <span class="hlt">activity</span> (extensile or contractile). An interesting generic outcome is that the alignment interaction can transform stationary <span class="hlt">active</span> patterns into continuously moving ones: the dynamics of these evolving patterns can be oscillatory or chaotic according to the strength of the alignment term. Our results suggest that flow-polarisation alignment can have important consequences on the collective dynamics of <span class="hlt">active</span> <span class="hlt">fluids</span> and <span class="hlt">active</span> gel. PMID:26769011</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JChPh.140s4506M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JChPh.140s4506M"><span id="translatedtitle">Elastically cooperative <span class="hlt">activated</span> barrier hopping theory of relaxation in viscous <span class="hlt">fluids</span>. I. General formulation and application to hard sphere <span class="hlt">fluids</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mirigian, Stephen; Schweizer, Kenneth S.</p> <p>2014-05-01</p> <p>We generalize the force-level nonlinear Langevin equation theory of single particle hopping to include collective effects associated with long range elastic distortion of the liquid. The <span class="hlt">activated</span> alpha relaxation event is of a mixed spatial character, involving two distinct, but inter-related, local and collective barriers. There are no divergences at volume fractions below jamming or temperatures above zero Kelvin. The ideas are first developed and implemented analytically and numerically in the context of hard sphere <span class="hlt">fluids</span>. In an intermediate volume fraction crossover regime, the local cage process is dominant in a manner consistent with an apparent Arrhenius behavior. The super-Arrhenius collective barrier is more strongly dependent on volume fraction, dominates the highly viscous regime, and is well described by a nonsingular law below jamming. The increase of the collective barrier is determined by the amplitude of thermal density fluctuations, dynamic shear modulus or transient localization length, and a growing microscopic jump length. Alpha relaxation time calculations are in good agreement with recent experiments and simulations on dense <span class="hlt">fluids</span> and suspensions of hard spheres. Comparisons of the theory with elastic models and entropy crisis ideas are explored. The present work provides a foundation for constructing a quasi-universal, fit-parameter-free theory for relaxation in thermal molecular liquids over 14 orders of magnitude in time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7239298','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7239298"><span id="translatedtitle">Lysozyme <span class="hlt">activity</span> in earthworm (Lumbricus terrestris) coelomic <span class="hlt">fluid</span> and coelomocytes: Enzyme assay for immunotoxicity of xenobiotics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Goven, A.J.; Chen, S.C.; Fitzpatrick, L.C. . Dept. of Biological Sciences); Venables, B.J. . Dept. of Biological Sciences TRAC Laboratories Inc., Denton, TX )</p> <p>1994-04-01</p> <p>Lysozyme <span class="hlt">activity</span> in earthworm (Lumbricus terrestris) coelomic <span class="hlt">fluid</span> and coelomocytes appears sufficiently sensitive for use as a nonmammalian biomarker to detect toxic effects of sublethal body burdens of Cu[sup 2+]. Lysozyme, a phylogenetically conserved enzyme, is capable of bactericidal <span class="hlt">activity</span> via action on peptidoglycan of gram-positive bacterial cell walls and functions as a component of an organism's innate antimicrobial defense mechanism. Coelomic <span class="hlt">fluid</span> and coelomocyte lysozyme <span class="hlt">activities</span>, which exhibit temperature-response patterns similar to those of human saliva, plasma, serum and leukocyte extracts, were sensitive to Cu[sup 2+] exposure. Lysozyme <span class="hlt">activity</span> of coelomic <span class="hlt">fluid</span> and coelomocyte extracts from earthworms exposed for 5 d to CuSO[sub 4], using filter paper contact exposure, decreased with increasing sublethal Cu[sup 2+] concentrations of 0.05 and 0.1 [mu]g/cm[sup 2]. Compared to controls, coelomic <span class="hlt">fluid</span> lysozyme <span class="hlt">activity</span> was suppressed significantly at both exposure concentrations, whereas coelomocyte extract lysozyme <span class="hlt">activity</span> was suppressed significantly at the 0.1-[mu]g/cm[sup 2] exposure concentration. Low inherent natural variability and sensitivity to sublethal Cu[sup 2+] body burdens indicate that lysozyme <span class="hlt">activity</span> has potential as a biomarker for assaying immunotoxicity of metals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990105708&hterms=activity+Physics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dactivity%2BPhysics','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990105708&hterms=activity+Physics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dactivity%2BPhysics"><span id="translatedtitle">Overview of <span class="hlt">Fluid</span> Dynamics <span class="hlt">Activities</span> at the Marshall Space Flight Center</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Garcia, Roberto; Griffin, Lisa W.; Wang, Ten-See</p> <p>1999-01-01</p> <p>Since its inception 40 years ago, Marshall Space Flight Center (MSFC) has had the need to maintain and advance state-of-the-art flow analysis and cold-flow testing capability to support its roles and missions. This overview discusses the recent organizational changes that have occurred at MSFC with emphasis on the resulting three groups that form the core of <span class="hlt">fluid</span> dynamics expertise at MSFC: the <span class="hlt">Fluid</span> Physics and Dynamics Group, the Applied <span class="hlt">Fluid</span> Dynamics Analysis Group, and the Experimental <span class="hlt">Fluid</span> Dynamics Group. Recently completed <span class="hlt">activities</span> discussed include the analysis and flow testing in support of the Fastrac engine design, the X-33 vehicle design, and the X34 propulsion system design. Ongoing <span class="hlt">activities</span> include support of the RLV vehicle design, Liquid Fly Back Booster aerodynamic configuration definition, and RLV focused technologies development. Other ongoing <span class="hlt">activities</span> discussed are efforts sponsored by the Center Director's Discretionary Fund (CDDF) to develop an advanced incompressible flow code and to develop optimization techniques. Recently initiated programs and their anticipated required <span class="hlt">fluid</span> dynamics support are discussed. Based on recent experiences and on the anticipated program needs, required analytical and experimental technique improvements are presented. Due to anticipated budgetary constraints, there is a strong need to leverage <span class="hlt">activities</span> and to pursue teaming arrangements in order to advance the state-of-the-art and to adequately support concept development. Throughout this overview there is discussion of the lessons learned and of the capabilities demonstrated and established in support of the hardware development programs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17.8146G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17.8146G&link_type=ABSTRACT"><span id="translatedtitle">Subsurface magma pathways inferred from statistical analysis of volcanic <span class="hlt">vent</span> distribution and numerical model of magma ascent</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Germa, Aurelie; Connor, Laura; Connor, Chuck; Malservisi, Rocco</p> <p>2015-04-01</p> <p> with variable conductivity dependent on flow rate and lithospheric stress to model the flow of a viscous <span class="hlt">fluid</span> within a homogeneous porous medium. Here, we apply the initial developments of this framework to the Lassen Segment (northern California), a distributed volcanic system. An investigation of the spatial density of eruptive <span class="hlt">vents</span> has been processed separately for basaltic, andesitic and silicic <span class="hlt">vents</span>. Results suggest that mafic and andesitic melt regions are related, widespread in space and time, with frequent eruptions distributed across the entire field. In contrast, silicic volcanism is spatially focused, and geochronological record suggest episodic <span class="hlt">activity</span>. Additionally, we explore the influence of various physical parameters, such as crust porosity and the development of shallow reservoirs, into magma transport and flux by modeling it as the non-linear flow of a viscous <span class="hlt">fluid</span> within a homogeneous porous medium. By comparing output data from numerical simulations to the flux revealed at the surface by our spatial density analysis, we gain insights into the subsurface processes controlling the location of mafic distributed volcanism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRB..113.8S12L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRB..113.8S12L"><span id="translatedtitle"><span class="hlt">Venting</span> of a separate CO2-rich gas phase from submarine arc volcanoes: Examples from the Mariana and Tonga-Kermadec arcs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lupton, John; Lilley, Marvin; Butterfield, David; Evans, Leigh; Embley, Robert; Massoth, Gary; Christenson, Bruce; Nakamura, Ko-Ichi; Schmidt, Mark</p> <p>2008-08-01</p> <p>Submersible dives on 22 <span class="hlt">active</span> submarine volcanoes on the Mariana and Tonga-Kermadec arcs have discovered systems on six of these volcanoes that, in addition to discharging hot <span class="hlt">vent</span> <span class="hlt">fluid</span>, are also <span class="hlt">venting</span> a separate CO2-rich phase either in the form of gas bubbles or liquid CO2 droplets. One of the most impressive is the Champagne <span class="hlt">vent</span> site on NW Eifuku in the northern Mariana Arc, which is discharging cold droplets of liquid CO2 at an estimated rate of 23 mol CO2/s, about 0.1% of the global mid-ocean ridge (MOR) carbon flux. Three other Mariana Arc submarine volcanoes (NW Rota-1, Nikko, and Daikoku), and two volcanoes on the Tonga-Kermadec Arc (Giggenbach and Volcano-1) also have <span class="hlt">vent</span> fields discharging CO2-rich gas bubbles. The <span class="hlt">vent</span> <span class="hlt">fluids</span> at these volcanoes have very high CO2 concentrations and elevated C/3He and δ13C (CO2) ratios compared to MOR systems, indicating a contribution to the carbon flux from subducted marine carbonates and organic material. Analysis of the CO2 concentrations shows that most of the <span class="hlt">fluids</span> are undersaturated with CO2. This deviation from equilibrium would not be expected for pressure release degassing of an ascending <span class="hlt">fluid</span> saturated with CO2. Mechanisms to produce a separate CO2-rich gas phase at the seafloor require direct injection of magmatic CO2-rich gas. The ascending CO2-rich gas could then partially dissolve into seawater circulating within the volcano edifice without reaching equilibrium. Alternatively, an ascending high-temperature, CO2-rich aqueous <span class="hlt">fluid</span> could boil to produce a CO2-rich gas phase and a CO2-depleted liquid. These findings indicate that carbon fluxes from submarine arcs may be higher than previously estimated, and that experiments to estimate carbon fluxes at submarine arc volcanoes are merited. Hydrothermal sites such as these with a separate gas phase are valuable natural laboratories for studying the effects of high CO2 concentrations on marine ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020050395','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020050395"><span id="translatedtitle">Zero Gravity Cryogenic <span class="hlt">Vent</span> System Concepts for Upper Stages</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Flachbart, Robin H.; Holt, James B.; Hastings, Leon J.</p> <p>2001-01-01</p> <p>The capability to <span class="hlt">vent</span> in zero gravity without resettling is a technology need that involves practically all uses of sub-critical cryogenics in space, and would extend cryogenic orbital transfer vehicle capabilities. However, the lack of definition regarding liquid/ullage orientation coupled with the somewhat random nature of the thermal stratification and resulting pressure rise rates, lead to significant technical challenges. Typically a zero gravity <span class="hlt">vent</span> concept, termed a thermodynamic <span class="hlt">vent</span> system (TVS), consists of a tank mixer to destratify the propellant, combined with a Joule-Thomson (J-T) valve to extract thermal energy from the propellant. Marshall Space Flight Center's (MSFC's) Multipurpose Hydrogen Test Bed (MHTB) was used to test both spray-bar and axial jet TVS concepts. The axial jet system consists of a recirculation pump heat exchanger unit. The spray-bar system consists of a recirculation pump, a parallel flow concentric tube heat exchanger, and a spray-bar positioned close to the longitudinal axis of the tank. The operation of both concepts is similar. In the mixing mode, the recirculation pump withdraws liquid from the tank and sprays it into the tank liquid, ullage, and exposed tank surfaces. When energy extraction is required, a small portion of the recirculated liquid is passed sequentially through the J-T expansion valve, the heat exchanger, and is <span class="hlt">vented</span> overboard. The <span class="hlt">vented</span> vapor cools the circulated bulk <span class="hlt">fluid</span>, thereby removing thermal energy and reducing tank pressure. The pump operates alone, cycling on and off, to destratify the tank liquid and ullage until the liquid vapor pressure reaches the lower set point. At that point, the J-T valve begins to cycle on and off with the pump. Thus, for short duration missions, only the mixer may operate, thus minimizing or even eliminating boil-off losses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GGG....16.2661W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GGG....16.2661W"><span id="translatedtitle">Geology, sulfide geochemistry and supercritical <span class="hlt">venting</span> at the Beebe Hydrothermal <span class="hlt">Vent</span> Field, Cayman Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Webber, Alexander P.; Roberts, Stephen; Murton, Bramley J.; Hodgkinson, Matthew R. S.</p> <p>2015-09-01</p> <p>The Beebe <span class="hlt">Vent</span> Field (BVF) is the world's deepest known hydrothermal system, at 4960 m below sea level. Located on the Mid-Cayman Spreading Centre, Caribbean, the BVF hosts high temperature (˜401°C) "black smoker" <span class="hlt">vents</span> that build Cu, Zn and Au-rich sulfide mounds and chimneys. The BVF is highly gold-rich, with Au values up to 93 ppm and an average Au:Ag ratio of 0.15. Gold precipitation is directly associated with diffuse flow through "beehive" chimneys. Significant mass-wasting of sulfide material at the BVF, accompanied by changes in metal content, results in metaliferous talus and sediment deposits. Situated on very thin (2-3 km thick) oceanic crust, at an ultraslow spreading centre, the hydrothermal system circulates <span class="hlt">fluids</span> to a depth of ˜1.8 km in a basement that is likely to include a mixture of both mafic and ultramafic lithologies. We suggest hydrothermal interaction with chalcophile-bearing sulfides in the mantle rocks, together with precipitation of Au in beehive chimney structures, has resulted in the formation of a Au-rich volcanogenic massive sulfide (VMS) deposit. With its spatial distribution of deposit materials and metal contents, the BVF represents a modern day analogue for basalt hosted, Au-rich VMS systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013003','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013003"><span id="translatedtitle">An estimate of hydrothermal <span class="hlt">fluid</span> residence times and <span class="hlt">vent</span> chimney growth rates based on 210Pb Pb ratios and mineralogic studies of sulfides dredged from the Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kadko, D.; Koski, R.; Tatsumoto, M.; Bouse, R.</p> <p>1985-01-01</p> <p>The 210Pb Pb ratios across two sulfide samples dredged from the Juan de Fuca Ridge are used to estimate the growth rate of the sulfide material and the residence time of the hydrothermal <span class="hlt">fluid</span> within the oceanic crust from the onset of basalt alteration. 210Pb is added to the hydrothermal <span class="hlt">fluid</span> by two processes: (1) high-temperature alteration of basalt and (2) if the residence time of the <span class="hlt">fluid</span> is on the order of the 22.3-year half-life of 210Pb, by in-situ growth from 222Rn (Krishnaswami and Turekian, 1982). Stable lead is derived only from the alteration of basalt. The 210Pb Pb ratio across one sample was ??? 0.5 dpm/10-6 g Pb, and across the other it was ??? 0.4 dpm/10-6 g Pb. These values are quite close to the 238U Pb ratios of basalts from the area, suggesting that the residence time of the hydrothermal <span class="hlt">fluid</span> from the onset of basalt alteration is appreciably less than the mean life of 210Pb, i.e., the time required for ingrowth from the radon. An apparent growth rate of 1.2 cm/yr is derived from the slope of the 210Pb Pb curve for one of the samples. This is consistent with its mineralogy and texture which suggest an accretionary pattern of development. There is no obvious sequential growth pattern, and virtually no gradient in 210Pb Pb across the second sample. This is consistent with alteration of the original 210Pb Pb distribution by extensive remobilization reactions which are inferred from the mineralogic and textural relationships of the sample. ?? 1985.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AGUFMOS24A..06G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AGUFMOS24A..06G&link_type=ABSTRACT"><span id="translatedtitle">Laboratory quantification of permeability-porosity relationships for seafloor <span class="hlt">vent</span> deposits: anisotropy in flange, slab, and crust samples</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gribbin, J. L.; Zhu, W.; Tivey, M. K.</p> <p>2010-12-01</p> <p>Seafloor hydrothermal <span class="hlt">vents</span> accommodate the convective transfer of material from Earth’s interior to the oceans. A variety of seafloor deposits form at <span class="hlt">vent</span> fields, including flanges, slabs, and crust. Flanges recovered from Guaymas Basin and the Main Endeavour Field (MEF) are horizontal ledges that protrude from the sides of larger structures. <span class="hlt">Fluid</span> pools under and can percolate upwards through the flanges. Slabs taken from the Lucky Strike <span class="hlt">Vent</span> Field are layered silicified deposits rich in sulfides, barite, and volcanic fragments; <span class="hlt">fluids</span> can percolate upward through the cracked slab layers. Crust samples recovered from the Trans-Atlantic Geotraverse (TAG) <span class="hlt">active</span> mound are composed of re-cemented older <span class="hlt">vent</span> debris, and, again, <span class="hlt">fluids</span> can percolate upward through the crust layers. Permeability and porosity measurements were made on a suite of flange, slab, and crust samples to determine evolution of permeability-porosity relationships (EPPRs). EPPRs are power-law relationships relating permeability and porosity through an exponent, α, that varies with changes in pore geometry - the higher the α value, the greater the change in permeability with respect to changes in porosity. Two trends were identified for the measured permeability and porosity data. First, measurements made on cores taken parallel to flange/slab/crust layers had consistently higher permeabilities (≈ 10-12 m2) and porosities (30-40%), and followed a trend of α ≈ 2. This trend differs significantly from the trend determined for measurements made on cores taken perpendicular to layering (representing most of the sample measurements): permeabilities ranged from 10-16-10-12 m2 and porosities from 20-45%, with a trend of α ≈ 4. The two distinct trends are consistent with the primary <span class="hlt">fluid</span> flow direction having been parallel to layering (the α ≈ 2 trend), with flow perpendicular to layering (the α ≈ 4 trend) having been restricted to serial pathways that intersected the various layers</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoRL..43.6205C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoRL..43.6205C&link_type=ABSTRACT"><span id="translatedtitle">Crustal magnetization and the subseafloor structure of the ASHES <span class="hlt">vent</span> field, Axial Seamount, Juan de Fuca Ridge: Implications for the investigation of hydrothermal sites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caratori Tontini, Fabio; Crone, Timothy J.; Ronde, Cornel E. J.; Fornari, Daniel J.; Kinsey, James C.; Mittelstaedt, Eric; Tivey, Maurice</p> <p>2016-06-01</p> <p>High-resolution geophysical data have been collected using the Autonomous Underwater Vehicle (AUV) Sentry over the ASHES (Axial Seamount Hydrothermal Emission Study) high-temperature (~348°C) <span class="hlt">vent</span> field at Axial Seamount, on the Juan de Fuca Ridge. Multiple surveys were performed on a 3-D grid at different altitudes above the seafloor, providing an unprecedented view of magnetic data resolution as a function of altitude above the seafloor. Magnetic data derived near the seafloor show that the ASHES field is characterized by a zone of low magnetization, which can be explained by hydrothermal alteration of the host volcanic rocks. Surface manifestations of hydrothermal <span class="hlt">activity</span> at the ASHES <span class="hlt">vent</span> field are likely controlled by a combination of local faults and fractures and different lava morphologies near the seafloor. Three-dimensional inversion of the magnetic data provides evidence of a vertical, pipe-like upflow zone of the hydrothermal <span class="hlt">fluids</span> with a vertical extent of ~100 m.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3219595','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3219595"><span id="translatedtitle">TRY-5 Is a Sperm-<span class="hlt">Activating</span> Protease in Caenorhabditis elegans Seminal <span class="hlt">Fluid</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Smith, Joseph R.; Stanfield, Gillian M.</p> <p>2011-01-01</p> <p>Seminal <span class="hlt">fluid</span> proteins have been shown to play important roles in male reproductive success, but the mechanisms for this regulation remain largely unknown. In Caenorhabditis elegans, sperm differentiate from immature spermatids into mature, motile spermatozoa during a process termed sperm <span class="hlt">activation</span>. For C. elegans males, sperm <span class="hlt">activation</span> occurs during insemination of the hermaphrodite and is thought to be mediated by seminal <span class="hlt">fluid</span>, but the molecular nature of this <span class="hlt">activity</span> has not been previously identified. Here we show that TRY-5 is a seminal <span class="hlt">fluid</span> protease that is required in C. elegans for male-mediated sperm <span class="hlt">activation</span>. We observed that TRY-5::GFP is expressed in the male somatic gonad and is transferred along with sperm to hermaphrodites during mating. In the absence of TRY-5, male seminal <span class="hlt">fluid</span> loses its potency to transactivate hermaphrodite sperm. However, TRY-5 is not required for either hermaphrodite or male fertility, suggesting that hermaphrodite sperm are normally <span class="hlt">activated</span> by a distinct hermaphrodite-specific <span class="hlt">activator</span> to which male sperm are also competent to respond. Within males, TRY-5::GFP localization within the seminal vesicle is antagonized by the protease inhibitor SWM-1. Together, these data suggest that TRY-5 functions as an extracellular <span class="hlt">activator</span> of C. elegans sperm. The presence of TRY-5 within the seminal <span class="hlt">fluid</span> couples the timing of sperm <span class="hlt">activation</span> to that of transfer of sperm into the hermaphrodite uterus, where motility must be rapidly acquired. Our results provide insight into how C. elegans has adopted sex-specific regulation of sperm motility to accommodate its male-hermaphrodite mode of reproduction. PMID:22125495</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800013238','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800013238"><span id="translatedtitle">Emergency relief <span class="hlt">venting</span> of the infrared telescope liquid helium dewar</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Urban, E. W.</p> <p>1980-01-01</p> <p>An analysis is made of the emergency relief <span class="hlt">venting</span> of the liquid helium dewar of the Spacelab 2 infrared telescope experiment in the event of a massive failure of the dewar guard vacuum. Such a failure, resulting from a major accident, could cause rapid heating and pressurization of the liquid helium in the dewar and lead to relief <span class="hlt">venting</span> through the emergency relief system. The heat input from an accident is estimated for various <span class="hlt">fluid</span> conditions in the dewar and the relief process as it takes place through one or both of the emergency relief paths is considered. It is shown that under all reasonable circumstances the dewar will safely relieve itself, and the pressure will not exceed 85 percent of the proof pressure or 63 percent of the burst pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20728991','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20728991"><span id="translatedtitle">Influence of <span class="hlt">venting</span> areas on the air blast pressure inside tubular structures like railway carriages.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Larcher, Martin; Casadei, Folco; Solomos, George</p> <p>2010-11-15</p> <p>In case of a terrorist bomb attack the influence and efficiency of <span class="hlt">venting</span> areas in tubular structures like train carriages is of interest. The pressure-time function of an air blast wave resulting from a solid charge is first compared to that of a gas or dust explosion and the capability of a <span class="hlt">venting</span> structure to fly away is assessed. Several calculations using <span class="hlt">fluid</span>-structure interaction are performed, which show that after a certain distance from the explosion, the air blast wave inside a tubular structure becomes one-dimensional, and that the influence of <span class="hlt">venting</span> areas parallel to the wave propagation direction is small. The pressure peak and the impulse at certain points in a tubular structure are compared for several opening sizes. The overall influence of realistic size <span class="hlt">venting</span> devices remains moderate and their usefulness in mitigating internal explosion effects in trains is discussed. PMID:20728991</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7047999','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7047999"><span id="translatedtitle">Experimental and theoretical constraints on the origin of mid-ocean ridge geothermal <span class="hlt">fluids</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Berndt, M.E.</p> <p>1987-01-01</p> <p>Hydrothermal experiments were performed using basalt, diabase, and two synthetic plagioclase bearing assemblages and Na-Ca-K-Cl <span class="hlt">fluids</span> of seawater chlorinity at conditions from 350 to 425/sup 0/C and 250 to 400 bars. Dissolved Ca, Na, SiO/sub 2/, and pH appear to be controlled by equilibrium with plagioclase and epidote. <span class="hlt">Fluids</span> reacting with diabase at low <span class="hlt">fluid</span>/rock ratios (0.5-1) remain undersaturated with respect to quartz due to formation of olivine hydration products, whereas <span class="hlt">fluids</span> reacting with basalt become supersaturated with respect to quartz due to breakdown of fractionated glass and formation of amphibole. High SiO/sub 2/ <span class="hlt">activities</span> during basalt alteration, leads to high Ca and base metal concentrations and low pH compared to diabase alteration at the same conditions. Dissolved Li, K, Rb, and Ba concentrations reach higher levels during basalt alteration than during diabase alteration. Since these elements avoid incorporation into crystalline phases during solidification of magmas they are concentrated in the glass which is easily altered by <span class="hlt">fluids</span> and explains their increased mobility during basalt alteration. Na-Ca-pH-SiO/sub 2/ relationships in <span class="hlt">vent</span> <span class="hlt">fluids</span> can be used to constrain reaction zone conditions assuming the <span class="hlt">fluids</span> are equilibrated with plagioclase and epidote. The temperatures predicted by such models are higher than measured <span class="hlt">vent</span> <span class="hlt">fluid</span> temperatures. Dissolved Sr/Ca ratios for ridge crest <span class="hlt">fluids</span> are similar to those produced during diabase alteration and higher than those produced during basalt alteration. This observation supports deep-seated reaction of the hydrothermal <span class="hlt">fluids</span> with diabase dikes and/or gabbro for <span class="hlt">vent</span> <span class="hlt">fluid</span> origin. Only 4% of the Sr initially present in basalt is mobilized during hydrothermal alteration even after 800 hours of reaction.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/11493559','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11493559"><span id="translatedtitle">The homeobox genes vox and <span class="hlt">vent</span> are redundant repressors of dorsal fates in zebrafish.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Imai, Y; Gates, M A; Melby, A E; Kimelman, D; Schier, A F; Talbot, W S</p> <p>2001-06-01</p> <p>Ventralizing transcriptional repressors in the Vox/<span class="hlt">Vent</span> family have been proposed to be important regulators of dorsoventral patterning in the early embryo. While the zebrafish genes vox (vega1) and <span class="hlt">vent</span> (vega2) both have ventralizing <span class="hlt">activity</span> in overexpression assays, loss-of-function studies are needed to determine whether these genes have distinct or redundant functions in dorsoventral patterning and to provide critical tests of the proposed regulatory interactions among vox, <span class="hlt">vent</span> and other genes that act to establish the dorsoventral axis. We show that vox and <span class="hlt">vent</span> are redundant repressors of dorsal fates in zebrafish. Mutants that lack vox function have little or no dorsoventral patterning defect, and inactivation of either vox or <span class="hlt">vent</span> by injection of antisense morpholino oligonucleotides has little or no effect on the embryo. In contrast, embryos that lack both vox and <span class="hlt">vent</span> function have a dorsalized phenotype. Expression of dorsal mesodermal genes, including chordin, goosecoid and bozozok, is strongly expanded in embryos that lack vox and <span class="hlt">vent</span> function, indicating that the redundant action of vox and <span class="hlt">vent</span> is required to restrict dorsal genes to their appropriate territories. Our genetic analysis indicates that the dorsalizing transcription factor Bozozok promotes dorsal fates indirectly, by antagonizing the expression of vox and <span class="hlt">vent</span>. In turn, vox and <span class="hlt">vent</span> repress chordin expression, restricting its function as an antagonist of ventral fates to the dorsal side of the embryo. Our results support a model in which BMP signaling induces the expression of ventral genes, while vox and <span class="hlt">vent</span> act redundantly to prevent the expression of chordin, goosecoid and other dorsal genes in the lateral and ventral mesendoderm. PMID:11493559</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003DSRI...50..269Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003DSRI...50..269Z"><span id="translatedtitle">Mineralogical gradients associated with alvinellids at deep-sea hydrothermal <span class="hlt">vents</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zbinden, Magali; Le Bris, Nadine; Compère, Philippe; Martinez, Isabelle; Guyot, François; Gaill, Françoise</p> <p>2003-02-01</p> <p>Alvinella pompejana and Alvinella caudata live in organic tubes on <span class="hlt">active</span> sulphide chimney walls at deep-sea hydrothermal <span class="hlt">vents</span>. These polychaete annelids are exposed to extreme thermal and chemical gradients and to intense mineral precipitation. This work points out that mineral particles associated with Pompeii worm ( A. pompejana and A. caudata) tubes constitute useful markers for evaluating the chemical characteristics of their micro-environment. The minerals associated with these worm tubes were analysed on samples recovered from an experimental alvinellid colony, at different locations in the <span class="hlt">vent</span> <span class="hlt">fluid</span>-seawater interface. Inhabited tubes from the most upper and lower parts of the colony were analysed by light and electron microscopies, X-ray microanalysis and X-ray diffraction. A change was observed from a Fe-Zn-S mineral assemblage to a Zn-S assemblage at the millimeter scale from the outer to the inner face of a tube. A similar gradient in proportions of minerals was observed at a decimeter scale from the lower to the upper part of the colony. The marcasite/pyrite ratio of iron disulphides also displays a steep decrease along the few millimeters adjacent to the external tube surface. The occurrence of these gradients indicates that the micro-environment within the tube differs from that outside the tube, and suggests that the tube wall acts as an efficient barrier to the external environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140000625','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140000625"><span id="translatedtitle"><span class="hlt">Vent</span> System Analysis for the Cryogenic Propellant Storage Transfer Ground Test Article</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hedayat, A</p> <p>2013-01-01</p> <p>To test and validate key capabilities and technologies required for future exploration elements such as large cryogenic propulsion stages and propellant depots, NASA is leading the efforts to develop and design the Cryogenic Propellant Storage and Transfer (CPST) Cryogenic <span class="hlt">Fluid</span> Management (CFM) payload. The primary objectives of CPST payload are to demonstrate: 1) in-space storage of cryogenic propellants for long duration applications; and 2) in-space transfer of cryogenic propellants. The Ground Test Article (GTA) is a technology development version of the CPST payload. The GTA consists of flight-sized and flight-like storage and transfer tanks, liquid acquisition devices, transfer, and pressurization systems with all of the CPST functionality. The GTA is designed to perform integrated passive and <span class="hlt">active</span> thermal storage and transfer performance testing with liquid hydrogen (LH2) in a vacuum environment. The GTA storage tank is designed to store liquid hydrogen and the transfer tank is designed to be 5% of the storage tank volume. The LH2 transfer subsystem is designed to transfer propellant from one tank to the other utilizing pressure or a pump. The LH2 <span class="hlt">vent</span> subsystem is designed to prevent over-pressurization of the storage and transfer tanks. An in-house general-purpose computer program was utilized to model and simulate the <span class="hlt">vent</span> subsystem operation. The modeling, analysis, and the results will be presented in the final paper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS51E..06T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS51E..06T"><span id="translatedtitle">Influence of Geologic Setting on the Morphology, Mineralogy, and Geochemistry of <span class="hlt">Vent</span> Deposits Along the Eastern Lau Spreading Center and Valu Fa Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tivey, M. K.; Evans, G. N.; Ferrini, V. L.</p> <p>2014-12-01</p> <p>Establishment of links between lithology, <span class="hlt">vent</span> <span class="hlt">fluid</span> chemistry, and <span class="hlt">vent</span> deposit characteristics along the Eastern Lau Spreading Center (ELSC) and Valu Fa Ridge (VFR) was made possible using deep submergence vehicles and technology. ROV Jason was used to collect ultrahigh-resolution (submeter) bathymetric data sufficient to quantify characteristics of volcanic, tectonic and hydrothermal features; differences within <span class="hlt">vent</span> fields from north to south include a change from low-relief volcanic domes cut by faults and fissures to higher aspect ratio volcanic domes dominated by aa-type lava morphologies (Ferrini et al., G-cubed, 2008). Highest temperature <span class="hlt">fluids</span> are associated with crosscutting faults at all but Mariner <span class="hlt">vent</span> field where faults are not observed. The detailed maps were used to target areas within <span class="hlt">vent</span> fields for observations and sampling. <span class="hlt">Vent</span> deposit morphologies are similar at the northernmost <span class="hlt">vent</span> fields (Kilo Moana, TowCam, Tahi Moana), with black smokers and diffusers present on branched edifices. <span class="hlt">Vent</span> deposits at the more southerly ABE, Tui Malila and Mariner <span class="hlt">vent</span> fields vary in morphology, despite similar substrate lithology. Examples include abundant flanges at ABE and Tui Malila and ~20m-tall spires and squat barite-rich edifices at Mariner. Geochemical analyses and petrographic observations document the influence of lithology, <span class="hlt">fluid</span> temperature, pH, and extents of seawater mixing on deposit formation. Concentrations of As, which increase from north to south, reflect lithologic control. Sb, Pb, and Ba concentrations also reflect lithologic control, but are affected as well by low pH and/or extents of seawater mixing. The significant differences in Mariner deposits reflect formation from very high temperature, low pH (<3 vs >4) <span class="hlt">fluids</span> that keep Zn in solution, combined with local subsurface mixing. Overall, results document the influence of the Tonga Subduction Zone on <span class="hlt">vent</span> deposits through its affects on lithology and <span class="hlt">vent</span> <span class="hlt">fluid</span> composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006cosp...36..334J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006cosp...36..334J"><span id="translatedtitle">NASA/JPL hydrothermal <span class="hlt">vent</span> bio-sampler</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jonsson, J.; Behar, A.; Bruckner, J.; Matthews, J.</p> <p></p> <p>pagestyle empty begin document On the bottom of the oceans with volcanic <span class="hlt">activity</span> present hydrothermal <span class="hlt">vents</span> can be found which spew out mineral rich superheated water from the porous seafloor crust Some of these <span class="hlt">vents</span> are situated several thousands of meters below the surface where the sunlight never reaches Yet life thrives here on the minerals and chemical compounds that the <span class="hlt">vent</span> water brings up with it This chemosynthetic microbial community forms the basis of some of the most interesting ecosystems on our planet and could possibly also be found on other water rich planets and moons in the solar system Perhaps under the icy surface of the moon Europa there exist hydrothermal <span class="hlt">vents</span> with such biota thriving independently of the solar energy The Hydrothermal <span class="hlt">Vent</span> Bio-sampler HVB is a system which will be used to collect pristine samples of the water emanating from hydrothermal <span class="hlt">vents</span> An array of temperature and flow sensors will monitor the sampling conditions This will allow for the samples to be collected from defined locations within the plume and the diversity and distribution of the chemosynthetic communities that might live there can be accurately described The samples will have to be taken without any contamination from the surrounding water thus the pristine requirement Monitoring the flow will assure that enough water has been sampled to account for the low biomass of these environments The system will be using a series of filters down to 0 2 mu m in pore size and the samples can be directly collected from the system for both culture-</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940012018','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940012018"><span id="translatedtitle"><span class="hlt">Fluid</span> flow and heat convection studies for <span class="hlt">actively</span> cooled airframes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mills, A. F.</p> <p>1993-01-01</p> <p>This report details progress made on the jet impingement - liquid crystal - digital imaging experiment. With the design phase complete, the experiment is currently in the construction phase. In order to reach this phase two design related issues were resolved. The first issue was to determine NASP leading edge <span class="hlt">active</span> cooling design parameters. Meetings were arranged with personnel at SAIC International, Torrance, CA in order to obtain recent publications that characterized expected leading edge heat fluxes as well as other details of NASP operating conditions. The information in these publications was used to estimate minimum and maximum jet Reynolds numbers needed to accomplish the required leading edge cooling, and to determine the parameters of the experiment. The details of this analysis are shown in Appendix A. One of the concerns for the NASP design is that of thermal stress due to large surface temperature gradients. Using a series of circular jets to cool the leading edge will cause a non-uniform temperature distribution and potentially large thermal stresses. Therefore it was decided to explore the feasibility of using a slot jet to cool the leading edge. The literature contains many investigations into circular jet heat transfer but few investigations of slot jet heat transfer. The first experiments will be done on circular jets impinging on a fiat plate and results compared to previously published data to establish the accuracy of the method. Subsequent experiments will be slot jets impinging on full scale models of the NASP leading edge. Table 1 shows the range of parameters to be explored. Next a preliminary design of the experiment was done. Previous papers which used a similar experimental technique were studied and elements of those experiments adapted to the jet impingement study. Trade-off studies were conducted to determine which design was the least expensive, easy to construct, and easy to use. Once the final design was settled, vendors were</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS13D1761S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS13D1761S&link_type=ABSTRACT"><span id="translatedtitle">Characterization of <span class="hlt">Active</span> Hydrothermal <span class="hlt">Fluid</span> Discharge and Recharge Zones in the Endeavour Axial Valley, Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salmi, M.; Hutnak, M.; Hearn, C.; Tivey, M.; Bjorklund, T.; Johnson, H. P.</p> <p>2012-12-01</p> <p>Sites where warm hydrothermal <span class="hlt">fluid</span> <span class="hlt">vents</span> at mid-ocean spreading centers are important for understanding a wide range of critical oceanic processes, but discharge zones represent a very limited portion of crustal <span class="hlt">fluid</span> circulation pathways. Mapping the distribution of both <span class="hlt">fluid</span> recharge and discharge sites within the axial valley provides wider insight into the larger scale features of hydrothermal circulation. Our 2011 survey consisted of 180 conductive heat flow stations within the Endeavour axial valley in roughly a 400 m by 1000 m grid, extending across the entire axial valley from the outer flank of the western boundary ridge to the eastern wall. Data acquisition used thermal blankets which measured conductive heat flow without requiring substantial sediment cover. A surprising result from this survey was zones of high heat flow extending across-strike, from the summit of the west valley wall across the entire axial valley floor. This trend was correlated with anomalously low seafloor magnetization from a near-bottom survey with the ROV JASON. Unexpectedly, over half of the axial valley floor was anomalously low at <50 mW m-2, while a small portion of the sites within the 'warm zone' had heat flow values >1 W m-2. The areas of extremely low heat flow values are interpreted as being directly influenced by recharge zones. Based on MCS estimates of partial melt depth below the axial valley and the assumption of no <span class="hlt">fluid</span> advection, the purely conductive heat flow for this region should be on the order of 1 W m-2.The observation that conductive heat flux is suppressed over large portions of the axial valley floor suggests that heat transfer within the crustal sub-surface <span class="hlt">fluid</span> reservoir is widespread, and impacts a large portion of our survey area. The largely bi-modal distribution of high and low conductive heat flow, coupled with geophysical and video observations, suggest current Endeavour axial valley crustal <span class="hlt">fluid</span> circulation models need to be re-evaluated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3025736','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3025736"><span id="translatedtitle">Traps of carnivorous pitcher plants as a habitat: composition of the <span class="hlt">fluid</span>, biodiversity and mutualistic <span class="hlt">activities</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Adlassnig, Wolfram; Peroutka, Marianne; Lendl, Thomas</p> <p>2011-01-01</p> <p>Background Carnivorous pitcher plants (CPPs) use cone-shaped leaves to trap animals for nutrient supply but are not able to kill all intruders of their traps. Numerous species, ranging from bacteria to vertrebrates, survive and propagate in the otherwise deadly traps. This paper reviews the literature on phytotelmata of CPPs. Pitcher <span class="hlt">Fluid</span> as a Habitat The volumes of pitchers range from 0·2 mL to 1·5 L. In Nepenthes and Cephalotus, the <span class="hlt">fluid</span> is secreted by the trap; the other genera collect rain water. The <span class="hlt">fluid</span> is usually acidic, rich in O2 and contains digestive enzymes. In some taxa, toxins or detergents are found, or the <span class="hlt">fluid</span> is extremely viscous. In Heliamphora or Sarracenia, the <span class="hlt">fluid</span> differs little from pure water. Inquiline Diversity Pitcher inquilines comprise bacteria, protozoa, algae, fungi, rotifers, crustaceans, arachnids, insects and amphibia. The dominant groups are protists and Dipteran larvae. The various species of CPPs host different sets of inquilines. Sarracenia purpurea hosts up to 165 species of inquilines, followed by Nepenthes ampullaria with 59 species, compared with only three species from Brocchinia reducta. Reasons for these differences include size, the life span of the pitcher as well as its <span class="hlt">fluid</span>. Mutualistic <span class="hlt">Activities</span> Inquilines closely interact with their host. Some live as parasites, but the vast majority are mutualists. Beneficial <span class="hlt">activities</span> include secretion of enzymes, feeding on the plant's prey and successive excretion of inorganic nutrients, mechanical break up of the prey, removal of excessive prey and assimilation of atmospheric N2. Conclusions There is strong evidence that CPPs influence their phytotelm. Two strategies can be distinguished: (1) Nepenthes and Cephalotus produce acidic, toxic or digestive <span class="hlt">fluids</span> and host a limited diversity of inquilines. (2) Genera without efficient enzymes such as Sarracenia or Heliamphora host diverse organisms and depend to a large extent on their symbionts for prey utilization</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830026735','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830026735"><span id="translatedtitle">Evaluation of aperture cover tank <span class="hlt">vent</span> nozzles for the IRAS spacecraft</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Richter, R.</p> <p>1983-01-01</p> <p>The influence of coefficients for the three axes of the Infrared Astronomical Satellite (IRAS) were established to determine the maximum allowable thrust difference between the two <span class="hlt">vent</span> nozzles of the aperture cover tank low thrust <span class="hlt">vent</span> system and their maximum misalignment. Test data generated by flow and torque measurements permitted the selection of two nozzles whose thrust differential was within the limit of the attitude control capability. Based on thrust stand data, a thrust vector misalignment was indicated that was slightly higher than permissible for the worst case, i.e., considerable degradation of the torque capacity of the attitude control system combined with <span class="hlt">venting</span> of helium at its upper limit. The probability of destabilizing the IRAS spacecraft by <span class="hlt">activating</span> the <span class="hlt">venting</span> system appeared to be very low. The selection and mounting of the nozzles have satisfied all the requirements for the safe <span class="hlt">venting</span> of helium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4752255','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4752255"><span id="translatedtitle">Comparison of <span class="hlt">Active</span> Drug Concentrations in the Pulmonary Epithelial Lining <span class="hlt">Fluid</span> and Interstitial <span class="hlt">Fluid</span> of Calves Injected with Enrofloxacin, Florfenicol, Ceftiofur, or Tulathromycin</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Foster, Derek M.; Martin, Luke G.; Papich, Mark G.</p> <p>2016-01-01</p> <p>Bacterial pneumonia is the most common reason for parenteral antimicrobial administration to beef cattle in the United States. Yet there is little information describing the antimicrobial concentrations at the site of action. The objective of this study was to compare the <span class="hlt">active</span> drug concentrations in the pulmonary epithelial lining <span class="hlt">fluid</span> and interstitial <span class="hlt">fluid</span> of four antimicrobials commonly used in cattle. After injection, plasma, interstitial <span class="hlt">fluid</span>, and pulmonary epithelial lining <span class="hlt">fluid</span> concentrations and protein binding were measured to determine the plasma pharmacokinetics of each drug. A cross-over design with six calves per drug was used. Following sample collection and drug analysis, pharmacokinetic calculations were performed. For enrofloxacin and metabolite ciprofloxacin, the interstitial <span class="hlt">fluid</span> concentration was 52% and 78% of the plasma concentration, while pulmonary <span class="hlt">fluid</span> concentrations was 24% and 40% of the plasma concentration, respectively. The pulmonary concentrations (enrofloxacin + ciprofloxacin combined) exceeded the MIC90 of 0.06 μg/mL at 48 hours after administration. For florfenicol, the interstitial <span class="hlt">fluid</span> concentration was almost 98% of the plasma concentration, and the pulmonary concentrations were over 200% of the plasma concentrations, exceeding the breakpoint (≤ 2 μg/mL), and the MIC90 for Mannheimia haemolytica (1.0 μg/mL) for the duration of the study. For ceftiofur, penetration to the interstitial <span class="hlt">fluid</span> was only 5% of the plasma concentration. Pulmonary epithelial lining <span class="hlt">fluid</span> concentration represented 40% of the plasma concentration. Airway concentrations exceeded the MIC breakpoint for susceptible respiratory pathogens (≤ 2 μg/mL) for a short time at 48 hours after administration. The plasma and interstitial <span class="hlt">fluid</span> concentrations of tulathromcyin were lower than the concentrations in pulmonary <span class="hlt">fluid</span> throughout the study. The bronchial concentrations were higher than the plasma or interstitial concentrations, with over 900</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26872361','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26872361"><span id="translatedtitle">Comparison of <span class="hlt">Active</span> Drug Concentrations in the Pulmonary Epithelial Lining <span class="hlt">Fluid</span> and Interstitial <span class="hlt">Fluid</span> of Calves Injected with Enrofloxacin, Florfenicol, Ceftiofur, or Tulathromycin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Foster, Derek M; Martin, Luke G; Papich, Mark G</p> <p>2016-01-01</p> <p>Bacterial pneumonia is the most common reason for parenteral antimicrobial administration to beef cattle in the United States. Yet there is little information describing the antimicrobial concentrations at the site of action. The objective of this study was to compare the <span class="hlt">active</span> drug concentrations in the pulmonary epithelial lining <span class="hlt">fluid</span> and interstitial <span class="hlt">fluid</span> of four antimicrobials commonly used in cattle. After injection, plasma, interstitial <span class="hlt">fluid</span>, and pulmonary epithelial lining <span class="hlt">fluid</span> concentrations and protein binding were measured to determine the plasma pharmacokinetics of each drug. A cross-over design with six calves per drug was used. Following sample collection and drug analysis, pharmacokinetic calculations were performed. For enrofloxacin and metabolite ciprofloxacin, the interstitial <span class="hlt">fluid</span> concentration was 52% and 78% of the plasma concentration, while pulmonary <span class="hlt">fluid</span> concentrations was 24% and 40% of the plasma concentration, respectively. The pulmonary concentrations (enrofloxacin + ciprofloxacin combined) exceeded the MIC90 of 0.06 μg/mL at 48 hours after administration. For florfenicol, the interstitial <span class="hlt">fluid</span> concentration was almost 98% of the plasma concentration, and the pulmonary concentrations were over 200% of the plasma concentrations, exceeding the breakpoint (≤ 2 μg/mL), and the MIC90 for Mannheimia haemolytica (1.0 μg/mL) for the duration of the study. For ceftiofur, penetration to the interstitial <span class="hlt">fluid</span> was only 5% of the plasma concentration. Pulmonary epithelial lining <span class="hlt">fluid</span> concentration represented 40% of the plasma concentration. Airway concentrations exceeded the MIC breakpoint for susceptible respiratory pathogens (≤ 2 μg/mL) for a short time at 48 hours after administration. The plasma and interstitial <span class="hlt">fluid</span> concentrations of tulathromcyin were lower than the concentrations in pulmonary <span class="hlt">fluid</span> throughout the study. The bronchial concentrations were higher than the plasma or interstitial concentrations, with over 900</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5642B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5642B"><span id="translatedtitle"><span class="hlt">Vents</span> Pattern Analysis at Etna volcano (Sicily, Italy).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brancato, Alfonso; Tusa, Giuseppina; Coltelli, Mauro; Proietti, Cristina; Branca, Stefano</p> <p>2014-05-01</p> <p>Mount Etna is a composite stratovolcano located along the Ionian coast of eastern Sicily. It is characterized by basaltic eruptions, both effusive and explosive, occurred during a complex eruptive history over the last 500 ka. Flank eruptions occur at an interval of decades, mostly concentrated along the NE, S and W rift zones. A <span class="hlt">vent</span> clustering at various scales is a common feature in many volcanic settings. In order to identify the clusters within the studied area, a spatial point pattern analysis is undertaken using <span class="hlt">vent</span> positions, both known and reconstructed. It reveals both clustering and spatial regularity in the Etna region at different distances. The visual inspection of the <span class="hlt">vent</span> spatial distribution suggests a clustering on the rift zones of Etna volcano. To confirm this evidence, a coarse analysis is performed by the application of Ξ2- and t-test simple statistics. Then, a refined analysis is performed by using the Ripley K-function (Ripley, 1976), whose estimator K(d), knowing the area of the study region and the number of <span class="hlt">vents</span>, allow us to calculate the distance among two different location of events. The above estimator can be easier transformed by using the Besag L-function (Besag, 1977); the peaks of positive L(d)=[K(d)/π]1/2 -d values indicate clustering while troughs of negative values stand for regularity for their corresponding distances d (L(d)=0 indicates complete spatial randomness). Spatial pattern of flank <span class="hlt">vents</span> is investigated in order to model the spatial distribution of likely eruptive <span class="hlt">vents</span> for the next event, basically in terms of relative probabilities. For this, a Gaussian kernel technique is used, and the L(d) function is adopted to generate an optimal smoothing bandwidth based on the clustering behaviour of the Etna volcano. A total of 154 <span class="hlt">vents</span> (among which 36 are reconstructed), related to Etna flank <span class="hlt">activity</span> of the last 4.0 ka, is used to model future <span class="hlt">vent</span> opening. The investigated region covers an area of 850 km2, divided</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4565717','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4565717"><span id="translatedtitle">ADAMTS-4 <span class="hlt">activity</span> in synovial <span class="hlt">fluid</span> as a biomarker of inflammation and effusion</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Roberts, S.; Evans, H.; Wright, K.; van Niekerk, L.; Caterson, B.; Richardson, J.B.; Kumar, K.H.S.; Kuiper, J.H.</p> <p>2015-01-01</p> <p>Summary Objective To evaluate the potential of ADAMTS-4 (aggrecanase -1) <span class="hlt">activity</span> in synovial <span class="hlt">fluid</span> (SF) as a biomarker of knee injury and joint disease. Design We have measured ADAMTS-4 <span class="hlt">activity</span> in the synovial <span class="hlt">fluid</span> of 170 orthopaedic patients with different degrees of joint pathology, using a commercial ADAMTS-4 fluorescence resonance energy transfer (FRET) substrate assay. Patients were classified at arthroscopy as (i) macroscopically normal, (ii) with an injury of the meniscus, anterior cruciate ligament or chondral/osteochondral defects or (iii) with osteoarthritis, and the influence of independent factors (age, patient group, effusion and synovial inflammation) on ADAMTS-4 <span class="hlt">activity</span> levels was assessed. Results In most patients (106/170) ADAMTS-4 <span class="hlt">activity</span> was undetectable; ADAMTS-4 ranged from 0 to 2.8 ng/mL in synovial <span class="hlt">fluid</span> from patients with an injury, 0–4.1 ng/mL in osteoarthritic patients and 4.0–12.3 ng/mL in patients with large effusions. Four independent variables each significantly influenced ADAMTS-4 <span class="hlt">activity</span> in synovial <span class="hlt">fluid</span> (all P < 0.001): age (concordance = 0.69), presence of osteoarthritis (OA) (concordance = 0.66), level of effusion (concordance = 0.78) and inflammation (concordance = 0.68). Not only did effusion influence the amount of ADAMTS-4 <span class="hlt">activity</span> most strongly, but it also did this in an ordered manner (P < 0.001). Conclusions The main finding of this study is that ADAMTS-4 levels in synovial <span class="hlt">fluid</span> are most strongly correlated with inflammation and severity of effusion in the knee. Further study is required to determine if it could provide a useful tool to aid clinical diagnoses, indicate treatment, to monitor progression of joint degeneration or OA or alternatively the success of treatment. PMID:26003949</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=255867','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=255867"><span id="translatedtitle">Characterization of cellulolytic <span class="hlt">activity</span> from digestive <span class="hlt">fluids</span> of Dissosteira carolina (Orthoptera: Acrididae)</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Previous screening of head-derived and gut <span class="hlt">fluid</span> extracts of Carolina grasshoppers, Dissosteira carolina (L.), revealed relatively high <span class="hlt">activity</span> against cellulase substrates when compared to other insect groups. In this work we report on the characterization and identification of enzymes involved i...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6673822','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6673822"><span id="translatedtitle">LOFT experimental measurements uncertainty analyses. Volume XX. <span class="hlt">Fluid</span>-velocity measurement using pulsed-neutron <span class="hlt">activation</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lassahn, G.D.; Taylor, D.J.N.</p> <p>1982-08-01</p> <p>Analyses of uncertainty components inherent in pulsed-neutron-<span class="hlt">activation</span> (PNA) measurements in general and the Loss-of-<span class="hlt">Fluid</span>-Test (LOFT) system in particular are given. Due to the LOFT system's unique conditions, previously-used techniques were modified to make the volocity measurement. These methods render a useful, cost-effective measurement with an estimated uncertainty of 11% of reading.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=43392&keyword=turbine&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=77066471&CFTOKEN=23920574','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=43392&keyword=turbine&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=77066471&CFTOKEN=23920574"><span id="translatedtitle">CHEMICALLY <span class="hlt">ACTIVE</span> <span class="hlt">FLUID</span> BED PROCESS FOR SULPHUR REMOVAL DURING GASIFICATION OF CARBONACEOUS FUELS</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The report covers the final 3 years of a 9-year program to evaluate the Chemically <span class="hlt">Active</span> <span class="hlt">Fluid</span> Bed (CAFB) process for gasification and desulfurization of liquid and solid fuels in a fluidized bed of hot lime. A range of alternative fuels, including three coals and a lignite, wer...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080047210','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080047210"><span id="translatedtitle">Deep-Sea Hydrothermal-<span class="hlt">Vent</span> Sampler</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Behar, Alberto E.; Venkateswaran, Kasthur; Matthews, Jaret B.</p> <p>2008-01-01</p> <p>An apparatus is being developed for sampling water for signs of microbial life in an ocean hydrothermal <span class="hlt">vent</span> at a depth of as much as 6.5 km. Heretofore, evidence of microbial life in deep-sea hydrothermal <span class="hlt">vents</span> has been elusive and difficult to validate. Because of the extreme conditions in these environments (high pressures and temperatures often in excess of 300 C), deep-sea hydrothermal- <span class="hlt">vent</span> samplers must be robust. Because of the presumed low density of biomass of these environments, samplers must be capable of collecting water samples of significant volume. It is also essential to prevent contamination of samples by microbes entrained from surrounding waters. Prior to the development of the present apparatus, no sampling device was capable of satisfying these requirements. The apparatus (see figure) includes an intake equipped with a temperature probe, plus several other temperature probes located away from the intake. The readings from the temperature probes are utilized in conjunction with readings from flowmeters to determine the position of the intake relative to the hydrothermal plume and, thereby, to position the intake to sample directly from the plume. Because it is necessary to collect large samples of water in order to obtain sufficient microbial biomass but it is not practical to retain all the water from the samples, four filter arrays are used to concentrate the microbial biomass (which is assumed to consist of particles larger than 0.2 m) into smaller volumes. The apparatus can collect multiple samples per dive and is designed to process a total volume of 10 L of <span class="hlt">vent</span> <span class="hlt">fluid</span>, of which most passes through the filters, leaving a total possibly-microbe-containing sample volume of 200 mL remaining in filters. A rigid titanium nose at the intake is used for cooling the sample water before it enters a flexible inlet hose connected to a pump. As the water passes through the titanium nose, it must be cooled to a temperature that is above a mineral</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24851333','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24851333"><span id="translatedtitle">Evaluation of <span class="hlt">activated</span> sludge for biodegradation of propylene glycol as an aircraft deicing <span class="hlt">fluid</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Delorit, Justin D; Racz, LeeAnn</p> <p>2014-04-01</p> <p>Aircraft deicing <span class="hlt">fluid</span> used at airport facilities is often collected for treatment or disposal in order to prevent serious ecological threats to nearby surface waters. This study investigated lab scale degradation of propylene glycol, the <span class="hlt">active</span> ingredient in a common aircraft deicing <span class="hlt">fluid</span>, by way of a laboratory-scale sequencing batch reactor containing municipal waste water treatment facility <span class="hlt">activated</span> sludge performing simultaneous organic carbon oxidation and nitrification. The ability of <span class="hlt">activated</span> sludge to remove propylene glycol was evaluated by studying the biodegradation and sorption characteristics of propylene glycol in an <span class="hlt">activated</span> sludge medium. The results indicate sorption may play a role in the fate of propylene glycol in AS, and the heterotrophic bacteria readily degrade this compound. Therefore, a field deployable bioreactor may be appropriate for use in flight line applications. PMID:24851333</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol15/pdf/CFR-2011-title40-vol15-sec65-62.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol15/pdf/CFR-2011-title40-vol15-sec65-62.pdf"><span id="translatedtitle">40 CFR 65.62 - Process <span class="hlt">vent</span> group determination.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>..., or Group 2B) for each process <span class="hlt">vent</span>. Group 1 process <span class="hlt">vents</span> require control, and Group 2A and 2B... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Process <span class="hlt">vent</span> group determination. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Process <span class="hlt">Vents</span> § 65.62 Process <span class="hlt">vent</span> group determination. (a)...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol16/pdf/CFR-2012-title40-vol16-sec65-62.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol16/pdf/CFR-2012-title40-vol16-sec65-62.pdf"><span id="translatedtitle">40 CFR 65.62 - Process <span class="hlt">vent</span> group determination.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>..., or Group 2B) for each process <span class="hlt">vent</span>. Group 1 process <span class="hlt">vents</span> require control, and Group 2A and 2B... 40 Protection of Environment 16 2012-07-01 2012-07-01 false Process <span class="hlt">vent</span> group determination. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Process <span class="hlt">Vents</span> § 65.62 Process <span class="hlt">vent</span> group determination. (a)...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol15/pdf/CFR-2010-title40-vol15-sec65-62.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol15/pdf/CFR-2010-title40-vol15-sec65-62.pdf"><span id="translatedtitle">40 CFR 65.62 - Process <span class="hlt">vent</span> group determination.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>..., or Group 2B) for each process <span class="hlt">vent</span>. Group 1 process <span class="hlt">vents</span> require control, and Group 2A and 2B... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Process <span class="hlt">vent</span> group determination. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Process <span class="hlt">Vents</span> § 65.62 Process <span class="hlt">vent</span> group determination. (a)...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol16/pdf/CFR-2013-title40-vol16-sec65-62.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol16/pdf/CFR-2013-title40-vol16-sec65-62.pdf"><span id="translatedtitle">40 CFR 65.62 - Process <span class="hlt">vent</span> group determination.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>..., or Group 2B) for each process <span class="hlt">vent</span>. Group 1 process <span class="hlt">vents</span> require control, and Group 2A and 2B... 40 Protection of Environment 16 2013-07-01 2013-07-01 false Process <span class="hlt">vent</span> group determination. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Process <span class="hlt">Vents</span> § 65.62 Process <span class="hlt">vent</span> group determination. (a)...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SMaS...23k5008G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SMaS...23k5008G"><span id="translatedtitle">A semi-<span class="hlt">active</span> magnetorheological <span class="hlt">fluid</span> mechanism with variable stiffness and damping</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Greiner-Petter, Christoph; Suryadi Tan, Aditya; Sattel, Thomas</p> <p>2014-10-01</p> <p>In this paper a semi-<span class="hlt">active</span> <span class="hlt">fluid</span>-mechanism is presented, which offers a variable stiffness and damping by utilizing two magnetorheological <span class="hlt">fluid</span> valves and two springs. The study incorporates the attributes of variable damping and stiffness into one compact device. A model for the magnetical, rheological, fluidical and mechanical behaviour of the whole system is derived. An experimental setup of the proposed system and an appropriate test bench are built in order to study the variable mechanical impedance behaviour with the corresponding simulations. The results proof that the stiffness of the system can be varied among three different values, while its damping is continuously variable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4512689','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4512689"><span id="translatedtitle">Interleukin 35 Synovial <span class="hlt">Fluid</span> Levels Are Associated with Disease <span class="hlt">Activity</span> of Rheumatoid Arthritis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Šenolt, Ladislav; Šumová, Barbora; Jandová, Romana; Hulejová, Hana; Mann, Heřman; Pavelka, Karel; Vencovský, Jiří; Filková, Mária</p> <p>2015-01-01</p> <p>Objectives To study the association of systemic and local interleukin-35 (IL-35) levels in rheumatoid arthritis. Methods 37 patients with treatment naïve early RA, 49 with established RA and 29 control patients with osteoarthritis (OA) were studied. Serum and paired synovial <span class="hlt">fluid</span> samples were analysed for IL-35. Disease <span class="hlt">activity</span> of RA patients was assessed according to the 28-Joint Count Disease <span class="hlt">Activity</span> Score (DAS28). Results The levels of serum IL-35 were significantly higher in patients with treatment naïve early RA compared to those with established disease and control OA subjects. In addition, serum levels of IL-35 significantly decreased 12 weeks after initiation of glucocorticoids and conventional synthetic disease modifying antirheumatic drugs in patients with treatment naïve early RA. Synovial <span class="hlt">fluid</span> IL-35 levels were significantly higher in RA compared to OA patients, were significantly elevated compared to serum counterparts and correlated with synovial <span class="hlt">fluid</span> leukocyte count (r=0.412; p<0.01), serum CRP levels (r=0.362; p<0.05) and DAS28 (r=0.430, p<0.01). Conclusion This is the first study showing elevated circulating levels of IL-35 in treatment naïve early RA, its significant decrease after treatment initiation and positive association between increased synovial <span class="hlt">fluid</span> IL-35 and disease <span class="hlt">activity</span> in patients with long-lasting RA. PMID:26204444</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007767','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007767"><span id="translatedtitle">Explosive Volcanic Eruptions from Linear <span class="hlt">Vents</span> on Earth, Venus and Mars: Comparisons with Circular <span class="hlt">Vent</span> Eruptions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Glaze, Lori S.; Baloga, Stephen M.; Wimert, Jesse</p> <p>2010-01-01</p> <p>Conditions required to support buoyant convective plumes are investigated for explosive volcanic eruptions from circular and linear <span class="hlt">vents</span> on Earth, Venus, and Mars. <span class="hlt">Vent</span> geometry (linear versus circular) plays a significant role in the ability of an explosive eruption to sustain a buoyant plume. On Earth, linear and circular <span class="hlt">vent</span> eruptions are both capable of driving buoyant plumes to equivalent maximum rise heights, however, linear <span class="hlt">vent</span> plumes are more sensitive to <span class="hlt">vent</span> size. For analogous mass eruption rates, linear <span class="hlt">vent</span> plumes surpass circular <span class="hlt">vent</span> plumes in entrainment efficiency approximately when L(sub o) > 3r(sub o) owing to the larger entrainment area relative to the control volume. Relative to circular <span class="hlt">vents</span>, linear <span class="hlt">vents</span> on Venus favor column collapse and the formation of pyroclastic flows because the range of conditions required to establish and sustain buoyancy is narrow. When buoyancy can be sustained, however, maximum plume heights exceed those from circular <span class="hlt">vents</span>. For current atmospheric conditions on Mars, linear <span class="hlt">vent</span> eruptions are capable of injecting volcanic material slightly higher than analogous circular <span class="hlt">vent</span> eruptions. However, both geometries are more likely to produce pyroclastic fountains, as opposed to convective plumes, owing to the low density atmosphere. Due to the atmospheric density profile and water content on Earth, explosive eruptions enjoy favorable conditions for producing sustained buoyant columns, while pyroclastic flows would be relatively more prevalent on Venus and Mars. These results have implications for the injection and dispersal of particulates into the planetary atmosphere and the ability to interpret the geologic record of planetary volcanism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4351821','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4351821"><span id="translatedtitle">Micro-poromechanics model of <span class="hlt">fluid</span>-saturated chemically <span class="hlt">active</span> fibrous media</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Misra, Anil; Parthasarathy, Ranganathan; Singh, Viraj; Spencer, Paulette</p> <p>2014-01-01</p> <p>We have developed a micromechanics based model for chemically <span class="hlt">active</span> saturated fibrous media that incorporates fiber network microstructure, chemical potential driven <span class="hlt">fluid</span> flow, and micro-poromechanics. The stress-strain relationship of the dry fibrous media is first obtained by considering the fiber behavior. The constitutive relationships applicable to saturated media are then derived in the poromechanics framework using Hill’s volume averaging. The advantage of this approach is that the resultant continuum model accounts for the discrete nature of the individual fibers while retaining a form suitable for porous materials. As a result, the model is able to predict the influence of micro-scale phenomena, such as the fiber pre-strain caused by osmotic effects and evolution of fiber network structure with loading, on the overall behavior and in particular, on the poromechanics parameters. Additionally, the model can describe <span class="hlt">fluid</span>-flow related rate-dependent behavior under confined and unconfined conditions and varying chemical environments. The significance of the approach is demonstrated by simulating unconfined drained monotonic uniaxial compression under different surrounding <span class="hlt">fluid</span> bath molarity, and <span class="hlt">fluid</span>-flow related creep and relaxation at different loading-levels and different surrounding <span class="hlt">fluid</span> bath molarity. The model predictions conform to the experimental observations for saturated soft fibrous materials. The method can potentially be extended to other porous materials such as bone, clays, foams and concrete. PMID:25755301</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1535502','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1535502"><span id="translatedtitle">Cytolytic <span class="hlt">activity</span> in T cell clones derived from human synovial rheumatoid membrane: inhibition by synovial <span class="hlt">fluid</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Miltenburg, A M; Van Laar, J M; De Kuiper, P; Daha, M R; Breedveld, F C</p> <p>1990-01-01</p> <p>A panel of T cell clones was derived from the synovial membrane of a patient with rheumatoid arthritis (RA). We investigated whether T cell clones with cytolytic properties were present and whether T cell cytotoxicity was influenced by the presence of synovial <span class="hlt">fluid</span>. These issues were studied using anti-CD3 and lectin-induced cytotoxicity assays. The majority of the T cell clones derived from the synovial membrane showed cytotoxic properties although non-cytotoxic clones were also found. Three clones (N11, N6 and N15) showed strong cytotoxicity (more than 40% lysis at an effector-to-target cell ratio of 10:1) whereas three clones (N16, N4 and N14) were non-cytotoxic (less than 20% lysis at an effector-to-target cell ratio of 10:1). The induction of cytotoxicity in the anti-CD3-driven system was shown to be dependent on the dose of anti-CD3 present. When synovial <span class="hlt">fluid</span> was added to these assays a strong inhibition of cytotoxicity was found. This inhibition of cytotoxicity was found with synovial <span class="hlt">fluid</span> samples of RA patients, as well as with non-RA synovial <span class="hlt">fluids</span>. Both anti-CD3 and lectin-dependent cytotoxicity assays were strongly inhibited. In conclusion, T cell clones with cytotoxic <span class="hlt">activity</span> can be isolated from rheumatoid synovial membrane. In the presence of synovial <span class="hlt">fluid</span> these cytotoxic cells are inhibited to exert their cytotoxic function. PMID:2148285</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26266751','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26266751"><span id="translatedtitle">Diversity of hydrolases from hydrothermal <span class="hlt">vent</span> sediments of the Levante Bay, Vulcano Island (Aeolian archipelago) identified by <span class="hlt">activity</span>-based metagenomics and biochemical characterization of new esterases and an arabinopyranosidase.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Placido, Antonio; Hai, Tran; Ferrer, Manuel; Chernikova, Tatyana N; Distaso, Marco; Armstrong, Dale; Yakunin, Alexander F; Toshchakov, Stepan V; Yakimov, Michail M; Kublanov, Ilya V; Golyshina, Olga V; Pesole, Graziano; Ceci, Luigi R; Golyshin, Peter N</p> <p>2015-12-01</p> <p>A metagenomic fosmid expression library established from environmental DNA (eDNA) from the shallow hot <span class="hlt">vent</span> sediment sample collected from the Levante Bay, Vulcano Island (Aeolian archipelago) was established in Escherichia coli. Using <span class="hlt">activity</span>-based screening assays, we have assessed 9600 fosmid clones corresponding to approximately 350 Mbp of the cloned eDNA, for the lipases/esterases/lactamases, haloalkane and haloacid dehalogenases, and glycoside hydrolases. Thirty-four positive fosmid clones were selected from the total of 120 positive hits and sequenced to yield ca. 1360 kbp of high-quality assemblies. Fosmid inserts were attributed to the members of ten bacterial phyla, including Proteobacteria, Bacteroidetes, Acidobateria, Firmicutes, Verrucomicrobia, Chloroflexi, Spirochaetes, Thermotogae, Armatimonadetes, and Planctomycetes. Of ca. 200 proteins with high biotechnological potential identified therein, we have characterized in detail three distinct α/β-hydrolases (LIPESV12_9, LIPESV12_24, LIPESV12_26) and one new α-arabinopyranosidase (GLV12_5). All LIPESV12 enzymes revealed distinct substrate specificities tested against 43 structurally diverse esters and 4 p-nitrophenol carboxyl esters. Of 16 different glycosides tested, the GLV12_5 hydrolysed only p-nitrophenol-α-(L)-arabinopyranose with a high specific <span class="hlt">activity</span> of about 2.7 kU/mg protein. Most of the α/β-hydrolases were thermophilic and revealed a high tolerance to, and high <span class="hlt">activities</span> in the presence of, numerous heavy metal ions. Among them, the LIPESV12_24 was the best temperature-adapted, retaining its <span class="hlt">activity</span> after 40 min of incubation at 90 °C. Furthermore, enzymes were <span class="hlt">active</span> in organic solvents (e.g., >30% methanol). Both LIPESV12_24 and LIPESV12_26 had the GXSXG pentapeptides and the catalytic triads Ser-Asp-His typical to the representatives of carboxylesterases of EC 3.1.1.1. PMID:26266751</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013SPIE.8916E..0IZ','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013SPIE.8916E..0IZ"><span id="translatedtitle">Variable stiffness and damping semi-<span class="hlt">active</span> vibration control technology based on magnetorheological <span class="hlt">fluids</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Shiyu; Deng, Huaxia; Zhang, Jin; Sun, ShuaiShuai; Li, Weihua; Wang, Lei</p> <p>2013-10-01</p> <p>Vibration is a source to induce uncertainty for the measurement. The traditional passive vibration control method has low efficiency and limited working conditions. The <span class="hlt">active</span> vibration control method is not practical for its power demanding, complexity and instability. In this paper, a novel semi-<span class="hlt">active</span> vibration control technology based on magnetorheological (MR) <span class="hlt">fluid</span> is presented with dual variable stiffness and damping capability. Because of the rheological behavior depending on the magnetic field intensity, MR <span class="hlt">fluid</span> is used in many damping semi-<span class="hlt">active</span> vibration control systems. The paper proposed a structure to allow the both overall damping and stiffness variable. The equivalent damping and stiffness of the structure are analyzed and the influences of the parameters on the stiffness and damping changing are further discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4937142','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4937142"><span id="translatedtitle">Synovial <span class="hlt">fluid</span> matrix metalloproteinase-2 and -9 <span class="hlt">activities</span> in dogs suffering from joint disorders</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>MURAKAMI, Kohei; MAEDA, Shingo; YONEZAWA, Tomohiro; MATSUKI, Naoaki</p> <p>2016-01-01</p> <p>The <span class="hlt">activity</span> of matrix metalloproteinase (MMP)-2 and MMP-9 in synovial <span class="hlt">fluids</span> (SF) sampled from dogs with joint disorders was investigated by gelatin zymography and densitometry. Pro-MMP-2 showed similar <span class="hlt">activity</span> levels in dogs with idiopathic polyarthritis (IPA; n=17) or canine rheumatoid arthritis (cRA; n=4), and healthy controls (n=10). However, dogs with cranial cruciate ligament rupture (CCLR; n=5) presented significantly higher pro-MMP-2 <span class="hlt">activity</span> than IPA and healthy dogs. Meanwhile, dogs with IPA exhibited significantly higher <span class="hlt">activity</span> of pro- and <span class="hlt">active</span> MMP-9 than other groups. <span class="hlt">Activity</span> levels in pro- and <span class="hlt">active</span> MMP-9 in cRA and CCLR dogs were not significantly different from those in healthy controls. Different patterns of MMP-2 and MMP-9 <span class="hlt">activity</span> may reflect the differences in the underlying pathological processes. PMID:26902805</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.T13F..04Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.T13F..04Y"><span id="translatedtitle"><span class="hlt">Active</span> Faulting and Pore-<span class="hlt">Fluid</span> Pressure in the Taiwan Thrust Belt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yue, L.; Suppe, J.</p> <p>2004-12-01</p> <p> compaction trend shown by sonic log data using standard petroleum techniques that show the magnitude of uplift and erosion and the fossil and present pore-<span class="hlt">fluid</span> pressures. The fossil top of the overpressured zone in several wells drilled through major thrusts and eroded anticlines is at a substantially higher (~1-2 km) stratigraphic level than the present top of <span class="hlt">fluid</span> pressures, but never reaches the level of the Pliocene Chinshui Shale. It implies uplift and erosion of the <span class="hlt">active</span> fold-and-thrust belt causes a major drop in <span class="hlt">fluid</span> pressures in the formerly overpressured zone. Finally, a preliminary estimate of Hubbert-Rubey <span class="hlt">fluid</span> pressure ratio needed to slide the Chelungpu thrust sheet (and also the Changhua thrust) using normal Byerlee's Law friction is about 0.8 (which is higher than any observed <span class="hlt">fluid</span> pressures even within the deeper overpressured zone). Therefore the Hubbert and Rubey mechanism of static excess <span class="hlt">fluid</span> pressure does not appear to be important for major thrusts such as the Chelungpu thrust that slipped in the Chi-Chi earthquake. The many other proposed non-Hubbert-Rubey mechanisms of reduction of fault strength should be considered, including dynamical mechanisms, <span class="hlt">fluid</span>-pressure transients and non Byerlee coefficients of friction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1821086','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1821086"><span id="translatedtitle">Complement Regulatory <span class="hlt">Activity</span> of Normal Human Intraocular <span class="hlt">Fluid</span> Is Mediated by MCP, DAF, and CD59</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sohn, Jeong-Hyeon; Kaplan, Henry J.; Suk, Hye-Jung; Bora, Puran S.; Bora, Nalini S.</p> <p>2007-01-01</p> <p>Purpose To identify the molecules in normal human intraocular <span class="hlt">fluid</span> (aqueous humor and vitreous) that inhibit the functional <span class="hlt">activity</span> of the complement system. Methods Aqueous humor and vitreous were obtained from patients with noninflammatory ocular disease at the time of surgery. Samples were incubated with normal human serum (NHS), and the mixture assayed for inhibition of the classical and alternative complement pathways using standard CH50 and AH50 hemolytic assays, respectively. Both aqueous humor and vitreous were fractionated by microconcentrators and size exclusion column chromatography. The inhibitory molecules were identified by immunoblotting as well as by studying the effect of depletion of membrane cofactor protein (MCP), decay-accelerating factor (DAF), and CD59 on inhibitory <span class="hlt">activity</span>. Results Both aqueous humor and vitreous inhibited the <span class="hlt">activity</span> of the classical pathway (CH50). Microcentrifugation revealed the major inhibitory <span class="hlt">activity</span> resided in the fraction with an Mr ≥ 3 kDa. Chromatography on an S-100-HR column demonstrated that the most potent inhibition was associated with the high-molecular-weight fractions (≥ 19.5 kDa). In contrast to unfractionated aqueous and vitreous, fractions with an Mr ≥ 3 kDa also had an inhibitory effect on the alternative pathway <span class="hlt">activity</span> (AH50). The complement regulatory <span class="hlt">activity</span> in normal human intraocular <span class="hlt">fluid</span> was partially blocked by monoclonal antibodies against MCP, DAF, and CD59. Immunoblot analysis confirmed the presence of these three molecules in normal intraocular <span class="hlt">fluid</span>. Conclusions Our results demonstrate that normal human intraocular <span class="hlt">fluid</span> (aqueous humor and vitreous) contains complement inhibitory factors. Furthermore, the high-molecular-weight factors appear to be the soluble forms of MCP, DAF, and CD59. PMID:11095615</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFMOS12A..07V&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFMOS12A..07V&link_type=ABSTRACT"><span id="translatedtitle">Modeling the Growth of Hyperthermophiles in Deep-sea Hydrothermal Diffuse <span class="hlt">Fluids</span> and Sulfide Deposits</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ver Eecke, H. C.; Oslowski, D. M.; Butterfield, D. A.; Olson, E. J.; Lilley, M. D.; Holden, J. F.</p> <p>2009-12-01</p> <p>In 2008 and 2009, 534 hydrothermal <span class="hlt">fluid</span> samples and 5 <span class="hlt">actively-venting</span> black smoker chimneys were collected using Alvin for correlative microbiological and chemical analyses as part of the Endeavour Segment and Axial Volcano Geochemistry and Ecology Research (EAGER) program. Hyperthermophilic, autotrophic Fe(III) oxide reducers, methanogens, and sulfur-reducing heterotrophs were enriched for at 85 and 95°C using most-probable-number estimates from 28 diffuse <span class="hlt">fluid</span> and 8 chimney samples. Heterotrophs were the most abundant of the three groups in both diffuse <span class="hlt">fluids</span> and black-smoker chimneys. Iron reducers were more abundant than methanogens, and more abundant in sulfide-hosted <span class="hlt">vents</span> than in basalt-hosted <span class="hlt">vents</span>. <span class="hlt">Fluid</span> chemistry suggests that there is net biogenic methanogenesis at the Marker 113/62 diffuse <span class="hlt">vent</span> at Axial Volcano but nowhere else sampled. The growth of hyperthermophilic methanogens and heterotrophs was modeled in the lab using pure cultures. Methanocaldococcus jannaschii grew at 82°C in a 2-liter reactor with continuous gas flow at H2 concentrations between 20 and 225 µM with a H2 km of 100 µM. Correlating H2 end-member mixing curves from <span class="hlt">vent</span> <span class="hlt">fluids</span> and seawater with our laboratory modeling study suggests that H2 concentrations are limiting for Methanocaldococcus growth at most Mothra, Main Field, and High Rise <span class="hlt">vent</span> sites at Endeavour but sufficient to support growth at some Axial Volcano <span class="hlt">vents</span>. Therefore, hyperthermophilic methanogens may depend on H2 syntrophy at low H2 sites. Twenty-one pure hyperthermophilic heterotroph strains each grew on α-1,4 and β-1,4 linked sugars and polypeptides with concomitant H2 production. The H2 production rate (cell-1 doubling-1) for Pyrococcus furiosus at 95°C without sulfur was 29 fmol, 36 fmol, and 53 fmol for growth on α-1,4 sugars, β-1,4 sugars, and peptides, respectively. The CH4 production rate for M. jannaschii was 390 fmol cell-1 doubling-1; therefore, we estimate that it would take approximately</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SMaS...24h5024Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SMaS...24h5024Z"><span id="translatedtitle">Topology optimization of magnetorheological <span class="hlt">fluid</span> layers in sandwich plates for semi-<span class="hlt">active</span> vibration control</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Xiaopeng; Kang, Zhan</p> <p>2015-08-01</p> <p>This paper investigates topology optimization of the magnetorheological (MR) <span class="hlt">fluid</span> layer in a sandwich plate for improving the semi-<span class="hlt">active</span> vibration control performance. Therein, a uniform magnetic field is applied across the MR <span class="hlt">fluid</span> layer to provide a semi-<span class="hlt">active</span> damping control effect. In the optimization model, the pseudo-densities describing the MR <span class="hlt">fluid</span> material distribution are taken as design variables, and an artificial magneto-rheological <span class="hlt">fluid</span> model (AMRF) with penalization is proposed to suppress intermediate density values. For reducing the vibration level under harmonic excitations, the dynamic compliance under a specific excitation frequency, or the frequency-aggregated dynamic compliance in a given frequency band, is taken as the objective function to be minimized. In this context, the adjoint-variable sensitivity analysis scheme is derived. The effectiveness and efficiency of the proposed method are demonstrated by numerical examples, in which the structural dynamic performance can be remarkably improved through optimization. The influences of several key factors on the optimal designs are also explored. It is shown that the AMRF model is effective in yielding clear boundaries in the final optimal solutions without use of additional regularization techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004SPIE.5390..135W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004SPIE.5390..135W"><span id="translatedtitle">Semi-<span class="hlt">active</span> control of torsional vibrations using an MR <span class="hlt">fluid</span> brake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Williams, Keith A.; Ye, Shaochun</p> <p>2004-07-01</p> <p>Control of torsional vibrations in an automotive crankshaft is a classical vibration control problem. The most common solution is to mount a crankshaft damper at one end of the crankshaft. Typical crankshaft dampers are composed of parallel stiffness and damping elements connecting a rotational inertia to the crankshaft. Appropriate design of the damper elements may result in substantial crankshaft vibration. Conventional couplings include elastomeric spring-damper elements and purely viscous <span class="hlt">fluid</span> couplings. While those approaches result in satisfactory reduction of crankshaft vibration, it may be that a semi-<span class="hlt">active</span> approach can achieve improved performance. To that end, an investigation of a semi-<span class="hlt">active</span> crankshaft damper using magneto-rheological (MR) <span class="hlt">fluid</span> has been initiated. A torsional MR <span class="hlt">fluid</span> brake was obtained and applied to a scale model of a crankshaft for a common eight-cylinder engine. Experiments were performed with the MR brake as a fixed-friction device. In addition, a simple stick-slip control algorithm was developed such that the MR brake became an on-line variable friction device. While a good deal of work remains to be performed in future efforts, the preliminary experimental results have demonstrated that a torsional damper composed of an MR <span class="hlt">fluid</span> brake has potential application in the field of torsional vibration control.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFM.V32B..06C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFM.V32B..06C&link_type=ABSTRACT"><span id="translatedtitle">Hydrothermal mineralogy and <span class="hlt">fluid</span> inclusions chemistry to understand the roots of <span class="hlt">active</span> geothermal systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chambefort, I. S.; Dilles, J. H.; Heinrich, C.</p> <p>2013-12-01</p> <p>An integrated study to link magmatic textures, magmatic mineral compositions, hydrothermal alteration zoning, hydrothermal mineral chemistry, and <span class="hlt">fluid</span> inclusion compositions has been undertaken to link an intrusive complex and its degassing alteration halo with their surface equivalent in an <span class="hlt">active</span> geothermal system. Ngatamariki geothermal system, New Zealand, presents a unique feature in the Taupo Volcanic Zone (TVZ). Drilling intercepted an intrusive complex with a high temperature alteration halo similarly to what is observed in magmatic-derived ore deposits. Thus it presents the perfect opportunity to study the magmatic-hydrothermal transition of the TVZ by characterizing the nature of the deep magmatic <span class="hlt">fluids</span> link to the heat source of the world known geothermal fields. The record of magmatic-hydrothermal <span class="hlt">fluid</span>-rock interactions preserved at Ngatamariki may be analogous of processes presently occurring at depth beneath TVZ geothermal systems. The intrusive complex consists of over 5 km3 of tonalite, diorite, basalt and aplitic dykes. Evidence of undercooling subsolidus magmatic textures such as myrmekite and skeletal overgrowth are commonly observed and often linked to volatile loss. The <span class="hlt">fluids</span> released during the crystallization of the intrusive complex are interpreted to be at the origin of the surrounding high temperature alteration halo. Advanced argillic to potassic alteration and high temperature acidic assemblage is associated with high-temperature quartz veining at depth and vuggy silica at the paleo-surface. Major element compositions of the white micas associated with the high temperature halo show a transition from, muscovite to phengite, muscovitic illite away from the intrusion, with a transition to pyrophyllite and/ or topaz, and andalusite characteristic of more acidic conditions. Abundant high-density (up to 59 wt% NaCl eq and homogenization temperatures of 550 degree Celsius and above) coexist with low-density vapor <span class="hlt">fluid</span> inclusions. This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BGD....12.8497P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BGD....12.8497P"><span id="translatedtitle">Comparative study of <span class="hlt">vent</span> and seep macrofaunal communities in the Guaymas Basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Portail, M.; Olu, K.; Escobar-Briones, E.; Caprais, J. C.; Menot, L.; Waeles, M.; Cruaud, P.; Sarradin, P. M.; Godfroy, A.; Sarrazin, J.</p> <p>2015-06-01</p> <p>Understanding the ecological processes and connectivity of chemosynthetic deep-sea ecosystems requires comparative studies. In the Guaymas Basin (Gulf of California, Mexico), the presence of seeps and <span class="hlt">vents</span> in the absence of biogeographic barrier, comparable sedimentary settings and depths offers a unique opportunity to assess the role of ecosystem specific environmental conditions on macrofaunal communities. Six seep and four <span class="hlt">vent</span> assemblages were studied, three of which were characterised by common major foundation taxa: vesicomyid bivalves, siboglinid tubeworms and microbial mats. Macrofaunal community structure at the family level showed that density, diversity and composition patterns were primarily shaped by seep and <span class="hlt">vent</span> common abiotic factors including methane and hydrogen sulphide concentrations. The type of substratum and the heterogeneity provided by foundation species were identified as additional structuring factors and their roles were found to vary according to <span class="hlt">fluid</span> regimes. Surprisingly, the presence of <span class="hlt">vent</span> environmental specificities, with higher temperature, higher metal concentrations and lower pH was not significant in explaining community patterns. Moreover, Guaymas seep and <span class="hlt">vent</span> shared an important number of common species suggesting frequent connections between the two ecosystems. Finally, this study provides further support for the hypothesis of continuity among deep-sea seep and <span class="hlt">vent</span> ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.V72A1282O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.V72A1282O"><span id="translatedtitle">Euryhaline Halophilic Microorganisms From the Suiyo Seamount Hydrothermal <span class="hlt">Vents</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Okamoto, T.; Kimura, H.; Maruyama, A.; Naganuma, T.</p> <p>2002-12-01</p> <p>The euryhaline halophilic microorganisms grow in a wide salinity range from <3% NaCl (seawater equivalent) to >15% NaCl or to even saturation (about 30% NaCl). A number of euryhaline halophiles have been found in a wide range of habitats from oceanic and terrestrial regimes, from deep-sea <span class="hlt">vents</span> and seeps, and from Antarctic sea ice and terrains. We have isolated the euryhaline strains independently from a Mid-Atlantic Ridge <span class="hlt">vent</span> <span class="hlt">fluids</span> and Antarctic terrains are closely related species of the genus Halomonas. Some euryhaline halophiles maintain intracellular osmotic balance by controlling the concentration of compatible solute such as ectoine. This compatible solute not only stabilizes the proteins from denaturation caused by high salt concentration but also serves as a protectant against stresses such as heating, freezing and drying. The sub-seafloor structure of a hydrothermal <span class="hlt">vent</span> is highly complicated with mosaic heterogeneity of physicochemical parameters such as temperature and salinity. This premise led us to the hypothesis that some euryhaline halophiles including Halomonas species well adapt to a wide salinity-ranged habitat in the sub-<span class="hlt">vent</span>. To test this hypothesis, isolation and characterization of euryhaline halophiles from the Suiyo Seamount hydrothermal <span class="hlt">vents</span> were conducted the drill-cored rock samples from the sites APSK-02, 03, and 07 and the filter-trapped <span class="hlt">fluid</span> particle samples from the sites APSK-01 and 05 were used. For initial cultivation, a heterotrophic bacterial medium of 15% NaCl was used. The samples was added to the medium and incubated under both aerobic and anaerobic conditions at room temperature. A total of 5 euryhaline halophilic strains were obtained and phylogenetically characterized: two strains (both related to Marinobacter) from APSK-02 core section 2; one strain (related to H. meridiana) from APSK-07 core section 3; and two strains (related to H. meridiana and H. variabilis) from APSK-01 trapped particles. In addition, some</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title46-vol5/pdf/CFR-2010-title46-vol5-sec151-15-5.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title46-vol5/pdf/CFR-2010-title46-vol5-sec151-15-5.pdf"><span id="translatedtitle">46 CFR 151.15-5 - <span class="hlt">Venting</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-10-01</p> <p>...) Pressure-vacuum <span class="hlt">venting</span>. A normally closed <span class="hlt">venting</span> system fitted with a device to automatically limit the pressure or vacuum in the tank to design limits. Pressure-vacuum relief valves shall comply with the... devices in accordance with the requirements of § 54.15-13 of this chapter. (2) When a...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110011447','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110011447"><span id="translatedtitle">Testing of an Ammonia EVA <span class="hlt">Vent</span> Tool for the International Space Station</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ungar, Eugene K.; Stanewich, Brett J.; Wilhelm, Sheri Munekata</p> <p>2000-01-01</p> <p>When components of the International Space Station ammonia External <span class="hlt">Active</span> Thermal Control System are replaced on-orbit, they must be <span class="hlt">vented</span> immediately after removal from the system. <span class="hlt">Venting</span> ensures that the component is not hard packed with liquid and thus does not pose a hazard. An extravehicular <span class="hlt">activity</span> (EVA) <span class="hlt">vent</span> tool has been developed to perform this function. However, there were concerns that the tool could whip, posing a hazard to the EVA astronaut, or would freeze. The ammonia <span class="hlt">vent</span> tool was recently tested in a thermal/vacuum chamber to demonstrate that it would operate safely and would not freeze during <span class="hlt">venting</span>. During the test, ammonia mimicking the <span class="hlt">venting</span> conditions for six different heat exchanger initial conditions was passed through representative test articles. In the present work, the model that was used to develop the ammonia state and flow for the test points is discussed and the test setup and operation is described. The qualitative whipping and freezing results of the test are discussed and <span class="hlt">vent</span> plume pressure measurements are described and interpreted.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25750992','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25750992"><span id="translatedtitle">Nepenthesin protease <span class="hlt">activity</span> indicates digestive <span class="hlt">fluid</span> dynamics in carnivorous nepenthes plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Buch, Franziska; Kaman, Wendy E; Bikker, Floris J; Yilamujiang, Ayufu; Mithöfer, Axel</p> <p>2015-01-01</p> <p>Carnivorous plants use different morphological features to attract, trap and digest prey, mainly insects. Plants from the genus Nepenthes possess specialized leaves called pitchers that function as pitfall-traps. These pitchers are filled with a digestive <span class="hlt">fluid</span> that is generated by the plants themselves. In order to digest caught prey in their pitchers, Nepenthes plants produce various hydrolytic enzymes including aspartic proteases, nepenthesins (Nep). Knowledge about the generation and induction of these proteases is limited. Here, by employing a FRET (fluorescent resonance energy transfer)-based technique that uses a synthetic fluorescent substrate an easy and rapid detection of protease <span class="hlt">activities</span> in the digestive <span class="hlt">fluids</span> of various Nepenthes species was feasible. Biochemical studies and the heterologously expressed Nep II from Nepenthes mirabilis proved that the proteolytic <span class="hlt">activity</span> relied on aspartic proteases, however an acid-mediated auto-<span class="hlt">activation</span> mechanism was necessary. Employing the FRET-based approach, the induction and dynamics of nepenthesin in the digestive pitcher <span class="hlt">fluid</span> of various Nepenthes plants could be studied directly with insect (Drosophila melanogaster) prey or plant material. Moreover, we observed that proteolytic <span class="hlt">activity</span> was induced by the phytohormone jasmonic acid but not by salicylic acid suggesting that jasmonate-dependent signaling pathways are involved in plant carnivory. PMID:25750992</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4353617','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4353617"><span id="translatedtitle">Nepenthesin Protease <span class="hlt">Activity</span> Indicates Digestive <span class="hlt">Fluid</span> Dynamics in Carnivorous Nepenthes Plants</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Buch, Franziska; Kaman, Wendy E.; Bikker, Floris J.; Yilamujiang, Ayufu; Mithöfer, Axel</p> <p>2015-01-01</p> <p>Carnivorous plants use different morphological features to attract, trap and digest prey, mainly insects. Plants from the genus Nepenthes possess specialized leaves called pitchers that function as pitfall-traps. These pitchers are filled with a digestive <span class="hlt">fluid</span> that is generated by the plants themselves. In order to digest caught prey in their pitchers, Nepenthes plants produce various hydrolytic enzymes including aspartic proteases, nepenthesins (Nep). Knowledge about the generation and induction of these proteases is limited. Here, by employing a FRET (fluorescent resonance energy transfer)-based technique that uses a synthetic fluorescent substrate an easy and rapid detection of protease <span class="hlt">activities</span> in the digestive <span class="hlt">fluids</span> of various Nepenthes species was feasible. Biochemical studies and the heterologously expressed Nep II from Nepenthes mirabilis proved that the proteolytic <span class="hlt">activity</span> relied on aspartic proteases, however an acid-mediated auto-<span class="hlt">activation</span> mechanism was necessary. Employing the FRET-based approach, the induction and dynamics of nepenthesin in the digestive pitcher <span class="hlt">fluid</span> of various Nepenthes plants could be studied directly with insect (Drosophila melanogaster) prey or plant material. Moreover, we observed that proteolytic <span class="hlt">activity</span> was induced by the phytohormone jasmonic acid but not by salicylic acid suggesting that jasmonate-dependent signaling pathways are involved in plant carnivory. PMID:25750992</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25493812','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25493812"><span id="translatedtitle">Generation of stationary and moving vortices in <span class="hlt">active</span> polar <span class="hlt">fluids</span> in the planar Taylor-Couette geometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Neef, M; Kruse, K</p> <p>2014-11-01</p> <p>We study the dynamics of an <span class="hlt">active</span> polar <span class="hlt">fluid</span> in the interstitial space between two fixed coaxial cylinders. For sufficiently large expansive or contractive <span class="hlt">active</span> stresses, the <span class="hlt">fluid</span> presents roll instabilities of axially symmetric states leading to the spontaneous formation of vortices in the flow field. These vortices are either stationary or travel around the inner cylinder. Increasing the <span class="hlt">activity</span> further, our numerical solutions indicate the existence of <span class="hlt">active</span> turbulence that coexists with regular vortex solutions. PMID:25493812</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6945722','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6945722"><span id="translatedtitle">Filtered <span class="hlt">venting</span> considerations in the United States</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dallman, R.J.; Hulman, L.G.; Kudrick, J.</p> <p>1988-01-01</p> <p>The capability to <span class="hlt">vent</span> with or without attenuation of fission products exists at some US facilities. In addition, two utilities have proposed enhanced capabilities, and generic enhancements are being considered under a regulatory evaluation of severe accident vulnerabilities at all US commercial reactors. The paper 1) summarizes the history of filtered <span class="hlt">venting</span> in the US including significant past and proposed related research; 2) summarizes an assessment of the positive and negative safety aspects of <span class="hlt">venting</span> for a class of 24 US reactors (BWR Mark I), and 3) discusses the regulatory assessments being made of filtered <span class="hlt">venting</span> as a severe accident management strategy, including potential attributes of both accident prevention and mitigation associated with <span class="hlt">venting</span>. Lastly, based on a review of available literature on European initiatives, questions are raised; answers to which would significantly help US evaluations. 10 refs., 2 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720010301','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720010301"><span id="translatedtitle">Low Gravity <span class="hlt">venting</span> of Refrigerant 11</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Labus, T. L.; Aydelott, J. C.; Lacovic, R. F.</p> <p>1972-01-01</p> <p>An experimental investigation was conducted in a five-second zero gravity facility to examine the effects of <span class="hlt">venting</span> initially saturated Refrigerant 11 from a cylindrical container (15-cm diameter) under reduced gravitational conditions. The system Bond numbers studied were 0 (weightlessness), 9 and 63; the liquid exhibited a nearly zero-degree contact angle on the container surface. During the <span class="hlt">venting</span> process, both liquid-vapor interface and liquid bulk vaporization occurred. The temperature of the liquid in the immediate vicinity of the liquid-vapor interface was found to decrease during <span class="hlt">venting</span>, while the liquid bulk temperature remained constant. Qualitative observations of the effects of system acceleration, <span class="hlt">vent</span> rate, and vapor volume presented. Quantitative information concerning the ullage pressure decay during low gravity <span class="hlt">venting</span> is also included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011AGUFM.V11E2549S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011AGUFM.V11E2549S&link_type=ABSTRACT"><span id="translatedtitle">Preliminary Modeling of Two-Phase Flow at the Main Endeavour <span class="hlt">Vent</span> Field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singh, S.; Lowell, R. P.</p> <p>2011-12-01</p> <p>The high temperature hydrothermal <span class="hlt">vents</span> of Main Endeavour Field (MEF), Juan de Fuca ridge exhibited quasi-steady North-South trending spatial gradients of both temperature and salinity for more than a decade before a magmatic event changed the <span class="hlt">vent</span> characteristics. In order to explain these observations, we construct two-dimensional numerical models of two-phase hydrothermal flow of the MEF. We consider both along-axis and across-axis simulations, taking into account the <span class="hlt">vent</span> field geometry and incorporating various parameters, such as different basal temperature distributions and permeability structures that might affect the <span class="hlt">vent</span> <span class="hlt">fluid</span> temperature and chemistry. Preliminary results from across-axis models, in which the basal temperature decreases linearly away from the ridge axis and results in a single high-temperature plume, indicate that basal temperature alone does not affect steady-state <span class="hlt">vent</span> temperature and salinity of the <span class="hlt">vents</span>. Simulations that include the presence of a high-permeability extrusive layer 2A atop the spreading ridge results in a zone of narrower and lower temperature <span class="hlt">venting</span>. The effect of a low permeability zone of anhydrite would tend to mitigate the decrease in temperature, however. Along-axis simulations performed to date, with an extended uniform high temperature basal boundary, produce multiple plumes; but the plumes do not exhibit a strong along-axis gradient in <span class="hlt">vent</span> salinity or temperature as observed at the MEF. These preliminary results suggest that the observed N-S gradient in temperature and salinity at MEF reflects interplay between heat source and either near the surface or deep-seated heterogeneous permeability structures. Three-dimensional simulations might ultimately be required to understand hydrothermal circulation at the MEF.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993PNAS...90.2940K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993PNAS...90.2940K"><span id="translatedtitle">Biocatalytic Synthesis of Acrylates in Supercritical <span class="hlt">Fluids</span>: Tuning Enzyme <span class="hlt">Activity</span> by Changing Pressure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kamat, Sanjay V.; Iwaskewycz, Brian; Beckman, Eric J.; Russell, Alan J.</p> <p>1993-04-01</p> <p>Supercritical <span class="hlt">fluids</span> are a unique class of non-aqueous media in which biocatalytic reactions can occur. The physical properties of supercritical <span class="hlt">fluids</span>, which include gas-like diffusivities and liquid-like densities, can be predictably controlled with changing pressure. This paper describes how adjustment of pressure, with the subsequent predictable changes of the dielectric constant and Hildebrand solubility parameter for fluoroform, ethane, sulfur hexafluoride, and propane, can be used to manipulate the <span class="hlt">activity</span> of lipase in the transesterification of methylmethacrylate with 2-ethyl-1-hexanol. Of particular interest is that the dielectric constant of supercritical fluoroform can be tuned from approximately 1 to 8, merely by increasing pressure from 850 to 4000 psi (from 5.9 to 28 MPa). The possibility now exists to predictably alter both the selectivity and the <span class="hlt">activity</span> of a biocatalyst merely by changing pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS43A2013S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS43A2013S"><span id="translatedtitle">Anhydrite Solubility and Ca Isotope Fractionation in the Vapor-Liquid Field of the NaCl-H2O System: Implications for Hydrothermal <span class="hlt">Vent</span> <span class="hlt">Fluids</span> at Mid-ocean Ridges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scheuermann, P.; Syverson, D. D.; Higgins, J. A.; Seyfried, W. E., Jr.</p> <p>2015-12-01</p> <p>Hydrothermal experiments were performed at 410, 420 and 450°C between 180-450 bar to investigate anhydrite (CaSO4) solubility and Ca isotope fractionation in the liquid-vapor stability field of the NaCl-H2O system. Experiments were conducted in flexible gold reaction cells and a fixed volume Ti reactor to reach all pressures between the critical curve and three-phase boundary. During isothermal decompression at 410°C, anhydrite solubility in the liquid phase increases (1 to 9 mmol/kg Ca), whereas the solubility decreases in the vapor phase (130 to < 10 umol/kg Ca). At 410°C and 290-270 bar, the partition coefficient, log Km = log (mv / ml), for Ca decreases from -1.35 to -2.46, and that of SO4 decreases from -1.76 to -2.82. At 420°C the Ca:SO4 ratio of the starting solution was 2:1, and the pH25°C decreases in the liquid and increases in the vapor upon decompression. Ca hydrolysis in the liquid and complex interactions between undetermined aqueous species in the vapor could explain this pattern. At 410 and 450°C, the experiments started with a Ca:SO4 ratio of 1:1. Along the 410°C isotherm, pH25°C initially increases in both the liquid and vapor, potentially caused by precipitation of an H+ bearing salt, such as NaHSO4. 30-40 bar below the critical curve there is a sudden decrease in pH25°C as the putative salt phase may become unstable and dissolve. At 450°C, pH25°C decreases in the vapor and increases in the liquid, as HCl and H2SO4 partition into the vapor. Ca isotope data at 420°C between 375-300 bar indicate that the vapor is isotopically light relative to the liquid. At lower pressures both phases approach the isotopic composition of the coexisting anhydrite, suggesting that dissolved Ca speciation becomes more structurally similar to anhydrite. This study furthers our understanding of elemental partitioning and isotopic fractionation in mineral-<span class="hlt">fluid</span> systems with implications for mass transfer reactions at/near the magma-hydrothermal boundary at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5647631','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5647631"><span id="translatedtitle">Oil heat <span class="hlt">venting</span> technology residential heating systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Krajewski, R.F.; Celebi, Y.; Strasser, J.</p> <p>1991-05-01</p> <p>Tests were conducted on two oil-fired space heating appliances (a boiler and a furnace). Instead of using a chimney these appliances were configured to exhaust the combustion products through the side wall of the building (sidewall <span class="hlt">vent</span>). The products of combustion were extracted mechanically (power-<span class="hlt">vent</span>) from each of the appliances by using a fan (induced-draft fan) in the <span class="hlt">vent</span> system. Measurements were made of the time required to clear the appliances of combustion products by running the <span class="hlt">vent</span> fan after burner shutdown (postpurge). These measurements indicated that one minute of postpurge was sufficient to clear the combustion products. The required postpurge duration was longer when based upon controlling nozzle temperature rise after burner shutdown. This is due to heat soakback from the combustion chamber. In order to hold nozzle temperatures down, the required postpurge period was estimated to be about 3 minutes for the furnace and about 7 minutes for the boiler. Measurements were also made of the off-cycle energy losses due to postpurge duration. Furnaces are more severely impacted by postpurge losses than are boilers. In addition, tests were conducted on two boilers to determine the off-cycle losses due to an actual chimney system. A comparison of these results to those of the side-wall <span class="hlt">vent</span> tests revealed the need for short postpurge durations to minimize losses. Calculations were made using the DOE test procedure and compared to the results of tests. Experimental results show that direct-<span class="hlt">vent</span> systems perform as well as chimney-<span class="hlt">vent</span> systems in terms of off-cycle losses. There is potential for an efficiency advantage for direct-<span class="hlt">vent</span> over chimney-<span class="hlt">vent</span> systems if postpurge requirements can be reduced. Initial efforts in developing a computer program for <span class="hlt">venting</span> design and analysis are described. 7 refs., 39 figs., 4 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6165743','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6165743"><span id="translatedtitle">Subtidal gastropods consume sulfur-oxidizing bacteria: evidence from coastal hydrothermal <span class="hlt">vents</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Stein, J.L.</p> <p>1984-02-17</p> <p>The black abalone (Haliotis cracherodii), a commercially important shallow-water gastropod common off White Point, Southern California, is found frequently at subtidal hydrothermal <span class="hlt">vents</span> within mats of filamentous sulfur-oxidizing bacteria. Foraging <span class="hlt">vent</span> abalones <span class="hlt">actively</span> consume the bacteria and confine their nightly feeding forays to bacterial mats surrounding the <span class="hlt">vents</span>. The growth of abalones consuming the sulfur bacteria exceeds that of control individuals consuming microalgae and is comparable to reported growth rates of abalones consuming macroalgae. Thus, off White Point, the black abalone may derive a portion of its nutrition from the subsidy of geothermal energy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984Sci...223..696S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984Sci...223..696S"><span id="translatedtitle">Subtidal Gastropods Consume Sulfur-Oxidizing Bacteria: Evidence from Coastal Hydrothermal <span class="hlt">Vents</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stein, Jeffrey L.</p> <p>1984-02-01</p> <p>The black abalone (Haliotis cracherodii), a commercially important shallow-water gastropod common off White Point, Southern California, is found frequently at subtidal hydrothermal <span class="hlt">vents</span> within mats of filamentous sulfur-oxidizing bacteria. Foraging <span class="hlt">vent</span> abalones <span class="hlt">actively</span> consume the bacteria and confine their nightly feeding forays to bacterial mats surrounding the <span class="hlt">vents</span>. The growth of abalones consuming the sulfur bacteria exceeds that of control individuals consuming microalgae and is comparable to reported growth rates of abalones consuming macroalgae. Thus, off White Point, the black abalone may derive a portion of its nutrition from the subsidy of geothermal energy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17841030','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17841030"><span id="translatedtitle">Subtidal gastropods consume sulfur-oxidizing bacteria: evidence from coastal hydrothermal <span class="hlt">vents</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stein, J L</p> <p>1984-02-17</p> <p>The black abalone (Haliotis cracherodii), a commercially important shallow-water gastropod common off White Point, Southern California, is found frequently at subtidal hydrothermal <span class="hlt">vents</span> within mats of filamentous sulfur-oxidizing bacteria. Foraging <span class="hlt">vent</span> abalones <span class="hlt">actively</span> consume the bacteria and confine their nightly feeding forays to bacterial mats surrounding the <span class="hlt">vents</span>. The growth of abalones consuming the sulfur bacteria exceeds that of control individuals consuming microalgae and is comparable to reported growth rates of abalones consuming macroalgae. Thus, off White Point, the black abalone may derive a portion of its nutrition from the subsidy of geothermal energy. PMID:17841030</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V13A0652O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V13A0652O"><span id="translatedtitle">Spatial and Temporal Changes in <span class="hlt">Fluid</span> Chemistry and Microbial Community Diversity in Subseafloor Habitats at Axial Seamount Following the 1998 Eruption</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Opatkiewicz, A. D.; Butterfield, D. A.; Baross, J. A.</p> <p>2006-12-01</p> <p>The subseafloor associated with hydrothermal <span class="hlt">vents</span> has the potential to contribute significantly to primary production and biogeochemical cycling in the ocean. However, too little is known about the phylogenetic and physiological diversity of the microbial communities or their in situ <span class="hlt">activity</span> to assess this potential. There are previous reports that subseafloor environments at <span class="hlt">active</span> <span class="hlt">vent</span> sites harbor a high diversity of microorganisms that include different thermal and metabolic groups of Bacteria and Archaea. However, little is known about how these communities change over time (minutes to years), at different <span class="hlt">vent</span> sites, or in response to perturbations. In an effort to address these issues, the subseafloor microbial community diversity was examined from five diffuse-flow hydrothermal <span class="hlt">vent</span> sites (distributed geographically over the seamount between three distinguishable <span class="hlt">vent</span> fields) over the course of six years following the 1998 eruption at Axial Seamount (45° 58'N; 130° 00' W). PCR-based Terminal Restriction Fragment Length Polymorphism (TRFLP) analyses were used to follow changes in the microbial community structure. 16S rRNA gene sequence analysis was used to identify the specific groups of Bacteria and Archaea from the TRFLP analyses. Deep-sea background seawater microorganisms were detected in hydrothermal <span class="hlt">fluid</span> samples (Bacteria: Alpha and Gamma Proteobacteria, Archaea: Marine Group I Crenarchaeota and Marine Group II Euryarchaeota). The unique subseafloor phylotypes detected included Epsilon, Delta and Beta Proteobacteria, Methanococcales and thermophilic Euryarchaeota. Temperature and key chemical species, which indicate the degree of mixing of hydrothermal <span class="hlt">fluid</span> with seawater in the subsurface, have been shown previously to be important in affecting the diversity of the microbial communities (Huber et al., 2003). This work substantiates these earlier findings and furthermore presents evidence that additional chemical species, distinguishing the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994PhDT.......192B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994PhDT.......192B"><span id="translatedtitle"><span class="hlt">Active</span> Control of Coupled Wave Propagation in <span class="hlt">Fluid</span>-Filled Elastic Cylindrical Shells.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brevart, Bertrand Jean</p> <p></p> <p>The vibrational energy propagating in straight <span class="hlt">fluid</span>-filled elastic pipes is carried by the structure as well as by the internal <span class="hlt">fluid</span>. This study demonstrates that, whether the propagating energy is predominantly conveyed in the shell or in the <span class="hlt">fluid</span>, large attenuations of the total power flow may be achieved by using an <span class="hlt">active</span> control approach. As the shell and <span class="hlt">fluid</span> motions are fully coupled, the implementation of intrusive sources/sensors in the acoustic field can be also avoided. The approach is based on using radial control forces applied to the outer shell wall and error sensors observing the structural motion. The cylindrical shell is assumed to be infinite, in vacuo or filled with water. The first disturbance source investigated is a propagating free wave of circumferential order n = 0 or n = 1. The control forces are appropriate harmonic line forces radially applied to the structure. The radial displacement of the shell wall at discrete locations downstream of the control forces is minimized using linear quadratic optimal control theory. The attenuation of the total power flow in the system after control is used to study the impact of the <span class="hlt">fluid</span> on the performance of the control approach. Results for the shell in vacuo are presented for comparison. Considering the breathing mode (n = 0), the <span class="hlt">fluid</span> decreases the control performance when the disturbance is a structural-type incident wave. Significant reductions of the transmitted power flow can be achieved when the disturbance is a <span class="hlt">fluid</span>-type of wave. Regarding the beam mode (n = 1), the <span class="hlt">fluid</span> increases the control performance below the first acoustic cut-off frequency and decreases it above this frequency. The analytical study is then extended to the <span class="hlt">active</span> control of the pipe vibrations induced by more realistic disturbances such as a point force or an internal monopole source. The point force disturbance addresses the problem of mechanical excitation whereas the internal monopole source directs the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFMOS43A2033H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFMOS43A2033H&link_type=ABSTRACT"><span id="translatedtitle">Iron-Oxidizing Bacteria Found at Slow-Spreading Ridge: a Case Study of Capelinhos Hydrothermal <span class="hlt">Vent</span> (Lucky Strike, MAR 37°N)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Henri, P. A.; Rommevaux, C.; Lesongeur, F.; Emerson, D.; Leleu, T.; Chavagnac, V.</p> <p>2015-12-01</p> <p>Iron-oxidizing bacteria becomes increasingly described in different geological settings from volcanically <span class="hlt">active</span> seamounts, coastal waters, to diffuse hydrothermal <span class="hlt">vents</span> near seafloor spreading centers [Emerson et al., 2010]. They have been mostly identified and described in Pacific Ocean, and have been only recently found in hydrothermal systems associated to slow spreading center of the Mid-Atlantic Ridge (MAR) [Scott et al., 2015]. During the MoMARSAT'13 cruise at Lucky Strike hydrothermal field (MAR), a new hydrothermal site was discovered at about 1.5 km eastward from the lava lake and from the main hydrothermal <span class="hlt">vents</span>. This <span class="hlt">active</span> <span class="hlt">venting</span> site, named Capelinhos, is therefore the most distant from the volcano, features many chimneys, both focused and diffuses. The hydrothermal end-member <span class="hlt">fluids</span> from Capelinhos are different from those of the other sites of Lucky Strike, showing the highest content of iron (Fe/Mn≈3.96) and the lowest chlorinity (270 mmol/l) [Leleu et al., 2015]. Most of the chimneys exhibit rust-color surfaces and bacterial mats near diffuse flows. During the MoMARSAT'15 cruise, an <span class="hlt">active</span> chimney, a small inactive one, and rust-color bacterial mat near diffuse flow were sampled at Capelinhos. Observations by SEM of the hydrothermal samples revealed the presence of iron oxides in an assemblage of tubular "sheaths", assembled "stalks", helical "stalks" and amorphous aggregates. These features are similar to those described from the Loihi iron-mats deposits and argue for the occurrence of iron-oxidizing bacteria. Cultures under micro-aerobic and neutral pH conditions allowed us to isolate strains from the small inactive chimney. Pyrosequencing of the 16S rRNA gene of the isolates and environmental samples will soon be performed, which should confirm the presence of iron-oxidizing bacteria and reveal the organization of bacterial communities in this original and newly discovered hydrothermal site of the slow spreading Mid-Atlantic Ridge. Emerson</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.sciencedirect.com/science/article/pii/S0016703710006344','USGSPUBS'); return false;" href="http://www.sciencedirect.com/science/article/pii/S0016703710006344"><span id="translatedtitle">Geochemistry of hydrothermal <span class="hlt">fluids</span> from the PACMANUS, Northeast Pual and Vienna Woods hydrothermal fields, Manus Basin, Papua New Guinea</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Reeves, Eoghan P.; Seewald, Jeffrey S.; Saccocia, Peter; Bach, Wolfgang; Craddock, Paul R.; Shanks, Wayne C.; Sylva, Sean P.; Walsh, Emily; Pichler, Thomas; Rosner, Martin</p> <p>2011-01-01</p> <p>Processes controlling the composition of seafloor hydrothermal <span class="hlt">fluids</span> in silicic back-arc or near-arc crustal settings remain poorly constrained despite growing evidence for extensive magmatic-hydrothermal <span class="hlt">activity</span> in such environments. We conducted a survey of <span class="hlt">vent</span> <span class="hlt">fluid</span> compositions from two contrasting sites in the Manus back-arc basin, Papua New Guinea, to examine the influence of variations in host rock composition and magmatic inputs (both a function of arc proximity) on hydrothermal <span class="hlt">fluid</span> chemistry. <span class="hlt">Fluid</span> samples were collected from felsic-hosted hydrothermal <span class="hlt">vent</span> fields located on Pual Ridge (PACMANUS and Northeast (NE) Pual) near the <span class="hlt">active</span> New Britain Arc and a basalt-hosted <span class="hlt">vent</span> field (Vienna Woods) located farther from the arc on the Manus Spreading Center. Vienna Woods <span class="hlt">fluids</span> were characterized by relatively uniform endmember temperatures (273-285 degrees C) and major element compositions, low dissolved CO2 concentrations (4.4 mmol/kg) and high measured pH (4.2-4.9 at 25 degrees C). Temperatures and compositions were highly variable at PACMANUS/NE Pual and a large, newly discovered <span class="hlt">vent</span> area (Fenway) was observed to be vigorously <span class="hlt">venting</span> boiling (358 degrees C) <span class="hlt">fluid</span>. All PACMANUS <span class="hlt">fluids</span> are characterized by negative delta DH2O values, in contrast to positive values at Vienna Woods, suggesting substantial magmatic water input to circulating <span class="hlt">fluids</span> at Pual Ridge. Low measured pH (25 degrees C) values (~2.6-2.7), high endmember CO2 (up to 274 mmol/kg) and negative delta 34SH2S values (down to -2.7 permille) in some <span class="hlt">vent</span> <span class="hlt">fluids</span> are also consistent with degassing of acid-volatile species from evolved magma. Dissolved CO2 at PACMANUS is more enriched in 13C (-4.1 permille to -2.3 permille) than Vienna Woods (-5.2 permille to -5.7 permille), suggesting a contribution of slab-derived carbon. The mobile elements (e.g. Li, K, Rb, Cs and B) are also greatly enriched in PACMANUS <span class="hlt">fluids</span> reflecting increased abundances in the crust there relative to the Manus</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010OptRv..17..410W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010OptRv..17..410W&link_type=ABSTRACT"><span id="translatedtitle">Effects of spatial variation of skull and cerebrospinal <span class="hlt">fluid</span> layers on optical mapping of brain <span class="hlt">activities</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Shuping; Shibahara, Nanae; Kuramashi, Daishi; Okawa, Shinpei; Kakuta, Naoto; Okada, Eiji; Maki, Atsushi; Yamada, Yukio</p> <p>2010-07-01</p> <p>In order to investigate the effects of anatomical variation in human heads on the optical mapping of brain <span class="hlt">activity</span>, we perform simulations of optical mapping by solving the photon diffusion equation for layered-models simulating human heads using the finite element method (FEM). Particularly, the effects of the spatial variations in the thicknesses of the skull and cerebrospinal <span class="hlt">fluid</span> (CSF) layers on mapping images are investigated. Mapping images of single <span class="hlt">active</span> regions in the gray matter layer are affected by the spatial variations in the skull and CSF layer thicknesses, although the effects are smaller than those of the positions of the <span class="hlt">active</span> region relative to the data points. The increase in the skull thickness decreases the sensitivity of the images to <span class="hlt">active</span> regions, while the increase in the CSF layer thickness increases the sensitivity in general. The images of multiple <span class="hlt">active</span> regions are also influenced by their positions relative to the data points and by their depths from the skin surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/2050244','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/2050244"><span id="translatedtitle">Antibacterial <span class="hlt">activity</span> of Eisenia fetida andrei coelomic <span class="hlt">fluid</span>: III--Relationship within the polymorphic hemolysins.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Roch, P; Lassegues, M; Valembois, P</p> <p>1991-01-01</p> <p>The antibacterial <span class="hlt">activity</span> exhibited by 10 different hemolytic, genetic families was established by measuring the inhibition of spontaneous in vitro growth by cell-free coelomic <span class="hlt">fluid</span> toward 2 bacteria which are pathogenic for the earthworm: Bacillus megaterium (Gram +) and Aeromonas hydrophila (Gram -). Only two families (B and K) displayed potent inhibitory <span class="hlt">activities</span>. This finding is consistent with the fact that the B family occurs most frequently in both natural as well as in industrial breedings. Nevertheless, evidence of a poor antibacterial defense in some frequent families suggests the existence of alternative antibacterial mechanisms. PMID:2050244</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930066187&hterms=innovative+management&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dinnovative%2Bmanagement','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930066187&hterms=innovative+management&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dinnovative%2Bmanagement"><span id="translatedtitle">Design and integrated operation of an innovative thermodynamic <span class="hlt">vent</span> system concept</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fazah, Michel M.; Lak, Tibor; Nguyen, Han; Wood, Charles C.</p> <p>1993-01-01</p> <p>A unique zero-g thermodynamic <span class="hlt">vent</span> system (TVS) is being developed by NASA's Marshall Space Flight Center (MSFC) and Rockwell International to meet cryogenic propellant management requirements for future space missions. The design is highly innovative in that it integrates the functions of a spray-bar tank mixer and a TVS. This concept not only satisfies the requirement for efficient tank mixing and zero-g <span class="hlt">venting</span> but also accommodates thermal conditioning requirements for other components (e.g., engine feed lines, turbopumps, and liquid acquisition devices). In addition, operations can be extended to accomplish tank chill-down, no-<span class="hlt">vent</span> fill, and emergency <span class="hlt">venting</span> during zero-g propellant transfer. This paper describes the system performance characterization and future test <span class="hlt">activities</span> that are part of MSFC's Multipurpose Hydrogen Test Bed (MHTB) program. The testing will demonstrate the feasibility and merit of the design, and serve as a proof-of-concept development <span class="hlt">activity</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9258E..23A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9258E..23A"><span id="translatedtitle">Applications of magneto-rheologic <span class="hlt">fluids</span> in semi-<span class="hlt">active</span> suspension systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andronic, Florin; Mihai, Ioan; Suciu, Cornel; Beniuga, Marius</p> <p>2015-02-01</p> <p>The present paper aims to investigate the impact of using magneto-rheologic <span class="hlt">fluids</span> in semi-<span class="hlt">active</span> suspension systems. For that purpose, the suspension system behavior will be analyzed in the case of dynamic control. It is verified whether a semi-<span class="hlt">active</span> suspension system that uses magneto-rheologic <span class="hlt">fluids</span> offers significant advantages by report to passive suspension systems. Two approaches were considered. The first one consisted of simulating both passive and semiactive suspension systems using Matlab Simulink. The conducted simulations yielded results for motion, speed, and accelerations of sprung and un-sprung masses. The second approach consisted of building an experimental set-up that uses a damper that is constructively contains a magneto-rheologic <span class="hlt">fluid</span>, to which an adjustable variable magnetic field can be applied by means of a coil, in its turn controlled in current by a driver. The driver receives its excitation signals from sensors put in contact to the road surface model. The experimental set-up was conceived so that the un-sprung mass follows the road bumps. Simulation results were then compared to experimental ones.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26719894','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26719894"><span id="translatedtitle">The Balance of <span class="hlt">Fluid</span> and Osmotic Pressures across <span class="hlt">Active</span> Biological Membranes with Application to the Corneal Endothelium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheng, Xi; Pinsky, Peter M</p> <p>2015-01-01</p> <p>The movement of <span class="hlt">fluid</span> and solutes across biological membranes facilitates the transport of nutrients for living organisms and maintains the <span class="hlt">fluid</span> and osmotic pressures in biological systems. Understanding the pressure balances across membranes is crucial for studying <span class="hlt">fluid</span> and electrolyte homeostasis in living systems, and is an area of <span class="hlt">active</span> research. In this study, a set of enhanced Kedem-Katchalsky (KK) equations is proposed to describe fluxes of water and solutes across biological membranes, and is applied to analyze the relationship between <span class="hlt">fluid</span> and osmotic pressures, accounting for <span class="hlt">active</span> transport mechanisms that propel substances against their concentration gradients and for fixed charges that alter ionic distributions in separated environments. The equilibrium analysis demonstrates that the proposed theory recovers the Donnan osmotic pressure and can predict the correct <span class="hlt">fluid</span> pressure difference across membranes, a result which cannot be achieved by existing KK theories due to the neglect of fixed charges. The steady-state analysis on <span class="hlt">active</span> membranes suggests a new pressure mechanism which balances the <span class="hlt">fluid</span> pressure together with the osmotic pressure. The source of this pressure arises from <span class="hlt">active</span> ionic fluxes and from interactions between solvent and solutes in membrane transport. We apply the proposed theory to study the transendothelial <span class="hlt">fluid</span> pressure in the in vivo cornea, which is a crucial factor maintaining the hydration and transparency of the tissue. The results show the importance of the proposed pressure mechanism in mediating stromal <span class="hlt">fluid</span> pressure and provide a new interpretation of the pressure modulation mechanism in the in vivo cornea. PMID:26719894</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4697791','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4697791"><span id="translatedtitle">The Balance of <span class="hlt">Fluid</span> and Osmotic Pressures across <span class="hlt">Active</span> Biological Membranes with Application to the Corneal Endothelium</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cheng, Xi; Pinsky, Peter M.</p> <p>2015-01-01</p> <p>The movement of <span class="hlt">fluid</span> and solutes across biological membranes facilitates the transport of nutrients for living organisms and maintains the <span class="hlt">fluid</span> and osmotic pressures in biological systems. Understanding the pressure balances across membranes is crucial for studying <span class="hlt">fluid</span> and electrolyte homeostasis in living systems, and is an area of <span class="hlt">active</span> research. In this study, a set of enhanced Kedem-Katchalsky (KK) equations is proposed to describe fluxes of water and solutes across biological membranes, and is applied to analyze the relationship between <span class="hlt">fluid</span> and osmotic pressures, accounting for <span class="hlt">active</span> transport mechanisms that propel substances against their concentration gradients and for fixed charges that alter ionic distributions in separated environments. The equilibrium analysis demonstrates that the proposed theory recovers the Donnan osmotic pressure and can predict the correct <span class="hlt">fluid</span> pressure difference across membranes, a result which cannot be achieved by existing KK theories due to the neglect of fixed charges. The steady-state analysis on <span class="hlt">active</span> membranes suggests a new pressure mechanism which balances the <span class="hlt">fluid</span> pressure together with the osmotic pressure. The source of this pressure arises from <span class="hlt">active</span> ionic fluxes and from interactions between solvent and solutes in membrane transport. We apply the proposed theory to study the transendothelial <span class="hlt">fluid</span> pressure in the in vivo cornea, which is a crucial factor maintaining the hydration and transparency of the tissue. The results show the importance of the proposed pressure mechanism in mediating stromal <span class="hlt">fluid</span> pressure and provide a new interpretation of the pressure modulation mechanism in the in vivo cornea. PMID:26719894</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016NatSR...622163N&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016NatSR...622163N&link_type=ABSTRACT"><span id="translatedtitle">Rapid growth of mineral deposits at artificial seafloor hydrothermal <span class="hlt">vents</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nozaki, Tatsuo; Ishibashi, Jun-Ichiro; Shimada, Kazuhiko; Nagase, Toshiro; Takaya, Yutaro; Kato, Yasuhiro; Kawagucci, Shinsuke; Watsuji, Tomoo; Shibuya, Takazo; Yamada, Ryoichi; Saruhashi, Tomokazu; Kyo, Masanori; Takai, Ken</p> <p>2016-02-01</p> <p>Seafloor massive sulphide deposits are potential resources for base and precious metals (Cu-Pb-Zn ± Ag ± Au), but difficulties in estimating precise reserves and assessing environmental impacts hinder exploration and commercial mining. Here, we report petrological and geochemical properties of sulphide chimneys less than 2 years old that formed where scientific boreholes <span class="hlt">vented</span> hydrothermal <span class="hlt">fluids</span> in the Iheya-North field, Okinawa Trough, in East China Sea. One of these infant chimneys, dominated by Cu-Pb-Zn-rich sulphide minerals, grew a height of 15 m within 25 months. Portions of infant chimneys are dominated by sulphate minerals. Some infant chimneys are sulphide-rich similar to high-grade Cu-Pb-Zn bodies on land, albeit with relatively low As and Sb concentrations. The high growth rate reaching the 15 m height within 25 months is attributed to the large hydrothermal <span class="hlt">vent</span> more than 50 cm in diameter created by the borehole, which induced slow mixing with the ambient seawater and enhanced efficiency of sulphide deposition. These observations suggest the possibility of cultivating seafloor sulphide deposits and even controlling their growth and grades through manipulations of how to mix and quench hydrothermal <span class="hlt">fluids</span> with the ambient seawater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4766430','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4766430"><span id="translatedtitle">Rapid growth of mineral deposits at artificial seafloor hydrothermal <span class="hlt">vents</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nozaki, Tatsuo; Ishibashi, Jun-Ichiro; Shimada, Kazuhiko; Nagase, Toshiro; Takaya, Yutaro; Kato, Yasuhiro; Kawagucci, Shinsuke; Watsuji, Tomoo; Shibuya, Takazo; Yamada, Ryoichi; Saruhashi, Tomokazu; Kyo, Masanori; Takai, Ken</p> <p>2016-01-01</p> <p>Seafloor massive sulphide deposits are potential resources for base and precious metals (Cu-Pb-Zn ± Ag ± Au), but difficulties in estimating precise reserves and assessing environmental impacts hinder exploration and commercial mining. Here, we report petrological and geochemical properties of sulphide chimneys less than 2 years old that formed where scientific boreholes <span class="hlt">vented</span> hydrothermal <span class="hlt">fluids</span> in the Iheya-North field, Okinawa Trough, in East China Sea. One of these infant chimneys, dominated by Cu-Pb-Zn-rich sulphide minerals, grew a height of 15 m within 25 months. Portions of infant chimneys are dominated by sulphate minerals. Some infant chimneys are sulphide-rich similar to high-grade Cu-Pb-Zn bodies on land, albeit with relatively low As and Sb concentrations. The high growth rate reaching the 15 m height within 25 months is attributed to the large hydrothermal <span class="hlt">vent</span> more than 50 cm in diameter created by the borehole, which induced slow mixing with the ambient seawater and enhanced efficiency of sulphide deposition. These observations suggest the possibility of cultivating seafloor sulphide deposits and even controlling their growth and grades through manipulations of how to mix and quench hydrothermal <span class="hlt">fluids</span> with the ambient seawater. PMID:26911272</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26911272','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26911272"><span id="translatedtitle">Rapid growth of mineral deposits at artificial seafloor hydrothermal <span class="hlt">vents</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nozaki, Tatsuo; Ishibashi, Jun-Ichiro; Shimada, Kazuhiko; Nagase, Toshiro; Takaya, Yutaro; Kato, Yasuhiro; Kawagucci, Shinsuke; Watsuji, Tomoo; Shibuya, Takazo; Yamada, Ryoichi; Saruhashi, Tomokazu; Kyo, Masanori; Takai, Ken</p> <p>2016-01-01</p> <p>Seafloor massive sulphide deposits are potential resources for base and precious metals (Cu-Pb-Zn ± Ag ± Au), but difficulties in estimating precise reserves and assessing environmental impacts hinder exploration and commercial mining. Here, we report petrological and geochemical properties of sulphide chimneys less than 2 years old that formed where scientific boreholes <span class="hlt">vented</span> hydrothermal <span class="hlt">fluids</span> in the Iheya-North field, Okinawa Trough, in East China Sea. One of these infant chimneys, dominated by Cu-Pb-Zn-rich sulphide minerals, grew a height of 15 m within 25 months. Portions of infant chimneys are dominated by sulphate minerals. Some infant chimneys are sulphide-rich similar to high-grade Cu-Pb-Zn bodies on land, albeit with relatively low As and Sb concentrations. The high growth rate reaching the 15 m height within 25 months is attributed to the large hydrothermal <span class="hlt">vent</span> more than 50 cm in diameter created by the borehole, which induced slow mixing with the ambient seawater and enhanced efficiency of sulphide deposition. These observations suggest the possibility of cultivating seafloor sulphide deposits and even controlling their growth and grades through manipulations of how to mix and quench hydrothermal <span class="hlt">fluids</span> with the ambient seawater. PMID:26911272</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS22B..01B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS22B..01B&link_type=ABSTRACT"><span id="translatedtitle">On the global distribution of hydrothermal <span class="hlt">vent</span> fields: One decade later</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beaulieu, S. E.; Baker, E. T.; German, C. R.</p> <p>2012-12-01</p> <p>Since the last global compilation one decade ago, the known number of <span class="hlt">active</span> submarine hydrothermal <span class="hlt">vent</span> fields has almost doubled. At the end of 2009, a total of 518 <span class="hlt">active</span> <span class="hlt">vent</span> fields was catalogued, with about half (245) visually confirmed and others (273) inferred <span class="hlt">active</span> at the seafloor. About half (52%) of these <span class="hlt">vent</span> fields are at mid-ocean ridges (MORs), 25% at volcanic arcs, 21% at back-arc spreading centers (BASCs), and 2% at intra-plate volcanoes and other settings. One third are in high seas, and the nations with the most known <span class="hlt">active</span> <span class="hlt">vent</span> fields within EEZs are Tonga, USA, Japan, and New Zealand. The increase in known <span class="hlt">vent</span> fields reflects a number of factors, including increased national and commercial interests in seafloor hydrothermal deposits as mineral resources. Here, we have comprehensively documented the percentage of strike length at MORs and BASCs that has been systematically explored for hydrothermal <span class="hlt">activity</span>. As of the end of 2009, almost 30% of the ~60,000 km of MORs had been surveyed at least with spaced vertical profiles to detect hydrothermal plumes. A majority of the <span class="hlt">vents</span> discovered at MORs in the past decade occurred at segments with < 60 mm/yr full spreading rate. Discoveries at ultra-slow MORs in the past decade included the deepest known <span class="hlt">vent</span> (Beebe at Mid-Cayman Rise) and high-temperature black smoker <span class="hlt">vents</span> (e.g., Dragon at SWIR and Loki's Castle at Mohns Ridge), and the highest temperature <span class="hlt">vent</span> was measured at the slow-spreading S MAR (Turtle Pits). Using a previously published equation for the linear relationship between the number of <span class="hlt">active</span> <span class="hlt">vent</span> fields per 100 km strike length (F_s) vs. weighted-average full spreading rate (u_s), we predicted 676 <span class="hlt">vent</span> fields remaining to be discovered at MORs. Even accounting for the lower F_s at slower spreading rates, almost half of the <span class="hlt">vents</span> that are predicted remaining to be discovered at MORs are at ultra-slow to slow spreading rates (< 40 mm/yr) and about 1/3 at intermediate rates (40-80 mm</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20050167855&hterms=Field+electric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DField%2Belectric','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20050167855&hterms=Field+electric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DField%2Belectric"><span id="translatedtitle">Electro-<span class="hlt">Active</span> Device Using Radial Electric Field Piezo-Diaphragm for Control of <span class="hlt">Fluid</span> Movement</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bryant, Robert G. (Inventor); Working, Dennis C. (Inventor)</p> <p>2005-01-01</p> <p>A <span class="hlt">fluid</span>-control electro-<span class="hlt">active</span> device includes a piezo-diaphragm made from a ferroelectric material sandwiched by first and second electrode patterns configured to introduce an electric field into the ferroelectric material when voltage is applied thereto. The electric field originates at a region of the ferroelectric material between the first and second electrode patterns, and extends radially outward from this region of the ferroelectric material and substantially parallel to the plane of the ferroelectric material. The piezo-diaphragm deflects symmetrically about this region in a direction substantially perpendicular to the electric field. An annular region coupled to and extending radially outward from the piezo-diaphragm perimetrically borders the piezo-diaphragm, A housing is connected to the region and at least one <span class="hlt">fluid</span> flow path with piezo-diaphragm disposed therein.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/864039','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/864039"><span id="translatedtitle">Monitoring arrangement for <span class="hlt">vented</span> nuclear fuel elements</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Campana, Robert J.</p> <p>1981-01-01</p> <p>In a nuclear fuel reactor core, fuel elements are arranged in a closely packed hexagonal configuration, each fuel element having diametrically opposed <span class="hlt">vents</span> permitting 180.degree. rotation of the fuel elements to counteract bowing. A grid plate engages the fuel elements and forms passages for communicating sets of three, four or six individual <span class="hlt">vents</span> with respective monitor lines in order to communicate <span class="hlt">vented</span> radioactive gases from the fuel elements to suitable monitor means in a manner readily permitting detection of leakage in individual fuel elements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26627734','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26627734"><span id="translatedtitle">Spontaneous <span class="hlt">Activity</span> of Cochlear Hair Cells Triggered by <span class="hlt">Fluid</span> Secretion Mechanism in Adjacent Support Cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Han Chin; Lin, Chun-Chieh; Cheung, Rocky; Zhang-Hooks, YingXin; Agarwal, Amit; Ellis-Davies, Graham; Rock, Jason; Bergles, Dwight E</p> <p>2015-12-01</p> <p>Spontaneous electrical <span class="hlt">activity</span> of neurons in developing sensory systems promotes their maturation and proper connectivity. In the auditory system, spontaneous <span class="hlt">activity</span> of cochlear inner hair cells (IHCs) is initiated by the release of ATP from glia-like inner supporting cells (ISCs), facilitating maturation of central pathways before hearing onset. Here, we find that ATP stimulates purinergic autoreceptors in ISCs, triggering Cl(-) efflux and osmotic cell shrinkage by opening TMEM16A Ca(2+)-<span class="hlt">activated</span> Cl(-) channels. Release of Cl(-) from ISCs also forces K(+) efflux, causing transient depolarization of IHCs near ATP release sites. Genetic deletion of TMEM16A markedly reduces the spontaneous <span class="hlt">activity</span> of IHCs and spiral ganglion neurons in the developing cochlea and prevents ATP-dependent shrinkage of supporting cells. These results indicate that supporting cells in the developing cochlea have adapted a pathway used for <span class="hlt">fluid</span> secretion in other organs to induce periodic excitation of hair cells. PMID:26627734</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23036924','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23036924"><span id="translatedtitle">Antimicrobial <span class="hlt">activity</span> and composition profile of grape (Vitis vinifera) pomace extracts obtained by supercritical <span class="hlt">fluids</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Oliveira, Daniela A; Salvador, Ana Augusta; Smânia, Artur; Smânia, Elza F A; Maraschin, Marcelo; Ferreira, Sandra R S</p> <p>2013-04-10</p> <p>The possibility of increasing the aggregated value of the huge amount of residues generated by wineries around the world foment studies using the grape pomace - the residue from the wine production, composed by seed, skin and stems - to obtain functional ingredients. Nowadays, consumers in general prefer natural and safe products mainly for food and cosmetic fields, where the supercritical <span class="hlt">fluid</span> extraction is of great importance due to the purity of the extracts provided. Therefore, the objective of this work is to evaluate the global extraction yield, the antimicrobial <span class="hlt">activity</span> and the composition profile of Merlot and Syrah grape pomace extracts obtained by supercritical CO2 (SC-CO2) and CO2 added with co-solvent at pressures up to 300 bar and temperatures of 50 and 60 °C. The results were compared with the ones obtained by Soxhlet and by ultrasound-assisted leaching extraction methods. The main components from the extracts, identified by HPLC, were gallic acid, p-OH-benzoic acid, vanillic acid and epicatechin. The antibacterial and antifungal <span class="hlt">activities</span> of the extracts were evaluated using four strains of bacteria (Staphylococcus aureus, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa) and three fungi strains (Candida albicans, Candida parapsilosis, Candida krusei). Despite lower extraction yield results, the supercritical <span class="hlt">fluid</span> extracts presented the highest antimicrobial effectiveness compared to the other grape pomace extracts due to the presence of antimicrobial <span class="hlt">active</span> compounds. Syrah extracts were less efficient against the microorganisms tested and Merlot extracts were more <span class="hlt">active</span> against Gram-positive bacteria. PMID:23036924</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title24-vol5/pdf/CFR-2010-title24-vol5-sec3280-710.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title24-vol5/pdf/CFR-2010-title24-vol5-sec3280-710.pdf"><span id="translatedtitle">24 CFR 3280.710 - <span class="hlt">Venting</span>, ventilation and combustion air.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-04-01</p> <p>... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false <span class="hlt">Venting</span>, ventilation and combustion... Fuel Burning Systems § 3280.710 <span class="hlt">Venting</span>, ventilation and combustion air. (a) The <span class="hlt">venting</span> as required by... appliance listing and the appliance manufacturer's instructions. (b) <span class="hlt">Venting</span> and combustion air...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title24-vol5/pdf/CFR-2011-title24-vol5-sec3280-710.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title24-vol5/pdf/CFR-2011-title24-vol5-sec3280-710.pdf"><span id="translatedtitle">24 CFR 3280.710 - <span class="hlt">Venting</span>, ventilation and combustion air.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-04-01</p> <p>... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false <span class="hlt">Venting</span>, ventilation and combustion... Fuel Burning Systems § 3280.710 <span class="hlt">Venting</span>, ventilation and combustion air. (a) The <span class="hlt">venting</span> as required by... appliance listing and the appliance manufacturer's instructions. (b) <span class="hlt">Venting</span> and combustion air...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol15/pdf/CFR-2011-title40-vol15-sec65-143.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol15/pdf/CFR-2011-title40-vol15-sec65-143.pdf"><span id="translatedtitle">40 CFR 65.143 - Closed <span class="hlt">vent</span> systems.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Closed <span class="hlt">vent</span> systems. 65.143 Section 65...) CONSOLIDATED FEDERAL AIR RULE Closed <span class="hlt">Vent</span> Systems, Control Devices, and Routing to a Fuel Gas System or a Process § 65.143 Closed <span class="hlt">vent</span> systems. (a) Closed <span class="hlt">vent</span> system equipment and operating requirements....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title46-vol5/pdf/CFR-2010-title46-vol5-sec153-362.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title46-vol5/pdf/CFR-2010-title46-vol5-sec153-362.pdf"><span id="translatedtitle">46 CFR 153.362 - <span class="hlt">Venting</span> system drain.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-10-01</p> <p>... 46 Shipping 5 2010-10-01 2010-10-01 false <span class="hlt">Venting</span> system drain. 153.362 Section 153.362 Shipping... Systems § 153.362 <span class="hlt">Venting</span> system drain. Unless a cargo <span class="hlt">vent</span> system at every point is level or slopes back... system must have a drain valve at each low point (trap) in the <span class="hlt">vent</span> line....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title14-vol3/pdf/CFR-2010-title14-vol3-sec125-159.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title14-vol3/pdf/CFR-2010-title14-vol3-sec125-159.pdf"><span id="translatedtitle">14 CFR 125.159 - <span class="hlt">Vent</span> and drain lines.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false <span class="hlt">Vent</span> and drain lines. 125.159 Section 125... Requirements § 125.159 <span class="hlt">Vent</span> and drain lines. All <span class="hlt">vent</span> and drain lines, and their fittings, that are located in... Administrator finds that the rupture or breakage of any <span class="hlt">vent</span> or drain line may result in a fire hazard....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS22C..04F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS22C..04F"><span id="translatedtitle">Shallow Water Hydrothermal <span class="hlt">Vents</span> in the Gulf of California: Natural Laboratories for Multidisciplinary Research</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Forrest, M.; Hilton, D. R.; Price, R. E.; Kulongoski, J. T.</p> <p>2015-12-01</p> <p>Modern and fossil examples of shallow water submarine hydrothermal <span class="hlt">vents</span> occur throughout the Gulf of California. These sites offer important information about the processes involved in the extensional tectonics that created the Gulf of California and continue to shape the region to this day. Due to their accessibility, shallow water marine hydrothermal <span class="hlt">vents</span> are far easier to access and study than their deeper analogs, and these settings can provide natural laboratories to study biogeochemical processes. Certain biogeochemical and biomineralizing processes occurring at shallow <span class="hlt">vents</span> are very similar to those observed around deep-sea hydrothermal <span class="hlt">vents</span>. In some cases, authigenic carbonates form around shallow <span class="hlt">vents</span>. However, the hydrothermal precipitates are generally composed of Fe-oxyhydroxides, Mn-oxides, opal, calcite, pyrite and cinnabar, and their textural and morphological characteristics suggest microbial mediation for mineral deposition. Modern shallow-water hydrothermal <span class="hlt">vents</span> also support complex biotic communities, characterized by the coexistence of chemosynthetic and photosynthetic organisms. These shallow <span class="hlt">vents</span> are highly productive and provide valuable resources to local fishermen. Extant shallow water hydrothermal <span class="hlt">activity</span> has been studied in Bahía Concepción, San Felipe, Punta Estrella, El Coloradito, Puertecitos, and around the Islas Encantadas. Discrete streams of gas bubbles are often discharged along with hot liquids at shallow water <span class="hlt">vents</span>. The <span class="hlt">vent</span> liquids generally exhibit lower salinities than seawater, and their isotopic compositions indicate that they contain meteoric water mixed with seawater. The composition of the shallow <span class="hlt">vent</span> gas is primarily made up of CO2, but may also be enriched in N2, H2S, CH4, and other higher hydrocarbons. The geochemistry of these gases can be informative in determining the sources and processes involved in their generation. In particular, 3He/4He ratios may provide valuable information about the origin of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JGRB..112.7101S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JGRB..112.7101S"><span id="translatedtitle">Stochastic analysis of exit <span class="hlt">fluid</span> temperature records from the <span class="hlt">active</span> TAG hydrothermal mound (Mid-Atlantic Ridge, 26°N): 1. Modes of variability and implications for subsurface flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sohn, R. A.</p> <p>2007-07-01</p> <p>Yearlong time series records of exit <span class="hlt">fluid</span> temperature from the <span class="hlt">active</span> TAG hydrothermal mound (Mid-Atlantic Ridge, 26°N) reveal a complex space-time pattern of flow variability within the mineral deposit. Exit <span class="hlt">fluid</span> temperatures were measured every 8-10 min from 17 sites distributed across the upper terrace of the mound from June 2003 to June 2004. High-temperature records were obtained using Deep Sea Power and Light SeaLogger® probes deployed in fractures discharging ˜360°C black smoker <span class="hlt">fluids</span>, and low-temperature records were obtained using VEMCO Ltd. Minilog probes deployed in cracks discharging ˜20°C diffuse flow <span class="hlt">fluids</span>. The temperature records are considerably more variable than those acquired from <span class="hlt">vent</span> fields on the fast spreading East Pacific Rise and exhibit a complex mix of both episodic and periodic variability. The diffuse flow records alternate between periods of discharge and periods of what I infer to be recharge when <span class="hlt">fluid</span> temperatures are equal to background water column levels (˜2.7°C) as ambient seawater is drawn into the seafloor. The space-time patterns of these episodic variations suggest that they represent reorganizations of the secondary circulation system driving diffuse discharge on the upper terrace of the mound on timescales from a few hours to a few days, most likely in response to permeability perturbations. Harmonic temperature oscillations were observed over a range of periods, with the principal lunar semidiurnal tidal period (M2) being most dominant. During certain times, exit <span class="hlt">fluid</span> temperatures at diffuse sites pulse at diurnal and semidiurnal tidal periods when they are hovering near background water column levels, which I interpret as flow reversals associated with the vertical displacement of a <span class="hlt">fluid</span> boundary layer at the seafloor interface when the local net flux is near zero. The pulsing behavior is predicted by poroelastic models of tidal loading but is not consistent with effects from tidal currents, which</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=38590&keyword=Aviation&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=64261160&CFTOKEN=23949000','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=38590&keyword=Aviation&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=64261160&CFTOKEN=23949000"><span id="translatedtitle">BIOREMEDIATED SOIL <span class="hlt">VENTING</span> OF LIGHT HYDROCARBONS</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The effectiveness and feasibility of bioremediated soil <span class="hlt">venting</span> of light hydrocarbons in the unsaturated zone was investigated. Degradation mechanics were considered as a one dimensional balance of storage, linear sorption, vertical advection, and Michaelis-Menton kinetics. he re...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850008660','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850008660"><span id="translatedtitle">External Tank GH2 <span class="hlt">Vent</span> Arm</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reichle, G. E.; Glassburn, C. W.</p> <p>1985-01-01</p> <p>Because the <span class="hlt">venting</span> of free hydrogen gas to the atmosphere presents an extremely hazardous situation, it was necessary to devise a means for safe, controlled <span class="hlt">venting</span> of the shuttle external tank gaseous hydrogen during and after liquid hydrogen tank loading. Several design concepts that were considered initially were discarded as unfeasible because of vehicle weight restrictions, high cost, and because the proposed structure was itself deemed a hazard due to the vehicle's nonvertical launch trajectory. These design concepts are discussed. A design employing a support structure/access arm attached to the fixed service structure was finally selected. The various design problems resolved included <span class="hlt">vent</span> arm disconnect/drop interference, minimizing refurbishment due to launch damage, disconnect reliability, vehicle movement tracking, minimizing <span class="hlt">vent</span> line pressure drop, and the presence of other vehicle services at the same centralized supply area. Six launches have proven the system to be reliable, efficient, and of nearly zero refurbishment cost.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870000239&hterms=Reciprocating+Compressor&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DReciprocating%2BCompressor','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870000239&hterms=Reciprocating+Compressor&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DReciprocating%2BCompressor"><span id="translatedtitle">Efficient <span class="hlt">Vent</span> Unloading of Air Compressors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Muhonen, Alvin J.</p> <p>1987-01-01</p> <p>Method for unloading one-and two-stage reciprocating air compressors increases energy efficiency and inhibits deterioration of components. In new unloader configuration, compressor <span class="hlt">vented</span> to atmosphere on downstream side. Method implemented expeditiously as modification of existing systems.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4444256','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4444256"><span id="translatedtitle">Subretinal <span class="hlt">Fluid</span> in Eyes with <span class="hlt">Active</span> Ocular Toxoplasmosis Observed Using Spectral Domain Optical Coherence Tomography</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shao, Qing; Heussen, Florian M.; Keane, Pearse A.; Stübiger, Nicole; Sadda, Srinivas R.; Pleyer, Uwe</p> <p>2015-01-01</p> <p>Purpose To describe the clinical finding of subretinal <span class="hlt">fluid</span> (SRF) in the posterior pole by spectral domain optical coherence tomography (SD-OCT) in eyes with <span class="hlt">active</span> ocular toxoplasmosis (OT). Design Retrospective case series. Participants Thirty-eight eyes from 39 patients with <span class="hlt">active</span> OT. Methods Eyes with <span class="hlt">active</span> OT which underwent SD-OCT were reviewed. SRFs in the posterior pole were further analyzed. Main Outcome Measures Presence of SRF; its accompanying features, e.g. retinal necrosis, cystoid macular edema (CME), choroidal neovascularization (CNV); and longitudinal changes of SRF, including maximum height and total volume before and after treatment. Results SRF presented in 45.5% (or 15/33) of eyes with typical <span class="hlt">active</span> OT and in 51.3% (or 20/39) of eyes with <span class="hlt">active</span> OT. The mean maximum height and total volume of SRF were 161.0 (range: 23–478) µm and 0.47 (range: 0.005–4.12) mm3, respectively. For 12 eyes with SRF related to <span class="hlt">active</span> retinal necrosis, SRF was observed with complete absorption after conventional anti-toxoplasmosis treatment. The mean duration for observation of SRF clearance was 33.8 (range: 7–84) days. The mean rate of SRF clearance was 0.0128 (range: 0.0002–0.0665) mm3/day. Conclusions SRF (i.e., serous retinal detachment) is a common feature in patients with <span class="hlt">active</span> OT when SD-OCT is performed. The majority of SRF was associated with retinal necrosis and reacted well to conventional therapy, regardless of total <span class="hlt">fluid</span> volume. However, SRF accompanying with CME or CNV responded less favorably or remained refractory to conventional or combined intravitreal treatment, even when the SRF was small in size. PMID:26010656</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JPhCS.407a2002N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JPhCS.407a2002N"><span id="translatedtitle">Effects of Intense Physical <span class="hlt">Activity</span> with Free Water Replacement on Bioimpedance Parameters and Body <span class="hlt">Fluid</span> Estimates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neves, E. B.; Ulbricht, L.; Krueger, E.; Romaneli, E. F. R.; Souza, M. N.</p> <p>2012-12-01</p> <p>Authors have emphasized the need for previous care in order to perform reliable bioimpedance acquisition. Despite of this need some authors have reported that intense physical training has little effect on Bioimpedance Analysis (BIA), while other ones have observed significant effects on bioimpedance parameters in the same condition, leading to body composition estimates considered incompatible with human physiology. The aim of this work was to quantify the changes in bioimpedance parameters, as well as in body <span class="hlt">fluids</span> estimates by BIA, after four hours of intense physical <span class="hlt">activity</span> with free water replacement in young males. Xitron Hydra 4200 equipment was used to acquire bioimpedance data before and immediately after the physical training. After data acquisition body <span class="hlt">fluids</span> were estimates from bioimpedance parameters. Height and weight of all subjects were also acquired to the nearest 0.1 cm and 0.1 kg, respectively. Results point that among the bioimpedance parameter, extracellular resistance presented the most coherent behavior, leading to reliable estimates of the extracellular <span class="hlt">fluid</span> and part of the total body water. Results also show decreases in height and weight of the participants, which were associated to the decrease in body hydration and in intervertebral discs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFMOS12A..03D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFMOS12A..03D&link_type=ABSTRACT"><span id="translatedtitle">Hydrothermal <span class="hlt">vent</span> flow and turbulence measurements with acoustic scintillation instrumentation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>di Iorio, D.; Xu, G.</p> <p>2009-12-01</p> <p>Acoustically derived measurements of hydrothermal <span class="hlt">vent</span> flow and turbulence were obtained from the <span class="hlt">active</span> black smoker Dante in the Main Endeavour <span class="hlt">vent</span> field, using scintillation analysis from one-way transmissions. The scintillation transmitter and receiver array formed a 93 m acoustic path through the buoyant plume 20 m above the structure. The acoustic path was parallel to the valley sidewall where the M2 tidal currents are approximately aligned along ridge due to topographic steering by the valley walls and hence most of the plume displacement is expected to occur along the acoustic path. On one deployment, data were collected for 6.5 weeks and vertical velocities range from 0.1 to 0.2 m/s showing a strong dependence on the spring/neap tidal cycle. The refractive index fluctuations which can be paramaterized in terms of the root-mean-square temperature fluctuations also shows a strong tidal modulation during spring tide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V43B2876S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V43B2876S"><span id="translatedtitle">Techniques for constraining short term eruptive processes at Kilauea's Overlook <span class="hlt">Vent</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sutton, A. J.; Elias, T.; Garbeil, H.; Horton, K. A.; Kern, C.; Oppenheimer, C.; Orr, T. R.; Patrick, M. R.; Poland, M. P.; Thelen, W. A.; Werner, C. A.</p> <p>2013-12-01</p> <p>The <span class="hlt">activity</span> within Kilauea's summit eruptive <span class="hlt">vent</span> has provided ongoing opportunities to study lava lake dynamics, especially since the <span class="hlt">active</span> lava surface became persistently visible in early 2010. Patrick et al. attributed 20-30 m lava rise/fall cycles to accumulation and release of gas beneath a shallow crust (2010), and Nadeau et al. (2010) reported rapid SO2 release during two of these rise/fall cycles. Since that time, the summit eruptive <span class="hlt">vent</span> has widened incrementally from about 70 to more than 160 meters in diameter, and this expanding geometry has been accompanied overall changes in pond dynamics. Recently, pond <span class="hlt">activity</span> has been temporally dominated by relatively constant magmatic convection with <span class="hlt">active</span> and persistent gas release. This predominant mode of <span class="hlt">activity</span>, especially during the past year, has been punctuated by short, (minutes-to-hours-long) more passive periods of little spattering, with decreased magmatic circulation, that usually end in brief, turbulent upset of the lava lake followed by a return to steadier <span class="hlt">active</span> convection and gas release. In addition to thermal and conventional webcams and seismic monitoring, an array of upward-looking UV spectrometers (Horton et al., 2012) and an SO2 camera system (Kern et al., session V043) are now tracking changes in Kilauea summit degassing, and inferentially, changes in pond <span class="hlt">activity</span>, by continuously recording SO2 gas release rates during daylight hours. The continuous SO2 emission rate data combined with continuous camera, seismic, and gravity measurements, all support a hypothesis that the dominant process controlling short term behavior of the lava lake surface is shallow--occurring within a kilometer of less of the <span class="hlt">active</span> free surface. SO2 exsolution occurs predominately at shallow depths (hundreds of meters or less) and would reasonably produce a low-density, bubble-dominated <span class="hlt">fluid</span>. Observationally, upset of the lava lake surface is accompanied by rapid and coincident increases in SO2 emissions</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/842638','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/842638"><span id="translatedtitle">NATURAL CO2 FLOW FROM THE LOIHI <span class="hlt">VENT</span>: IMPACT ON MICROBIAL PRODUCTION AND FATE OF THE CO2</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Richard B. Coffin; Thomas J. Boyd; David L. Knies; Kenneth S. Grabowski; John W. Pohlman; Clark S. Mitchell</p> <p>2004-02-27</p> <p>The program for International Collaboration on CO{sub 2} Ocean Sequestration was initiated December 1997. Preliminary steps involved surveying a suite of biogeochemical parameters off the coast of Kona on the Big Island of Hawaii. The preliminary survey was conducted twice, in 1999 and 2000, to obtain a thorough data set including measurements of pH, current profiles, CO{sub 2} concentrations, microbial <span class="hlt">activities</span>, and water and sediment chemistries. These data were collected in order to interpret a planned CO{sub 2} injection experiment. After these preliminary surveys were completed, local environment regulation forced moving the project to the coast north east of Bergen, Norway. The preliminary survey along the Norwegian Coast was conducted during 2002. However, Norwegian government revoked a permit, approved by the Norwegian State Pollution Control Authority, for policy reasons regarding the CO{sub 2} injection experiment. As a result the research team decided to monitor the natural CO{sub 2} flow off the southern coast of the Big Island. From December 3rd-13th 2002 scientists from four countries representing the Technical Committee of the International Carbon Dioxide Sequestration Experiment examined the hydrothermal <span class="hlt">venting</span> at Loihi Seamount (Hawaiian Islands, USA). Work focused on tracing the <span class="hlt">venting</span> gases, the impacts of the <span class="hlt">vent</span> <span class="hlt">fluids</span> on marine organisms, and CO{sub 2} influence on biogeochemical cycles. The cruise on the R/V Ka'imikai-O-Kanaloa (KOK) included 8 dives by the PISCES V submarine, 6 at Loihi and 2 at a nearby site in the lee of the Big Island. Data for this final report is from the last 2 dives on Loihi.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740006543','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740006543"><span id="translatedtitle">Zero-gravity <span class="hlt">venting</span> of three refrigerants</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Labus, T. L.; Aydelott, J. C.; Amling, G. E.</p> <p>1974-01-01</p> <p>An experimental investigation of <span class="hlt">venting</span> cylindrical containers partially filled with initially saturated liquids under zero-gravity conditions was conducted in the NASA Lewis Research Center 5-second zero-gravity facility. The effect of interfacial mass transfer on the ullage pressure response during <span class="hlt">venting</span> was analytically determined, based on a conduction analysis applied to an infinitely planer (flat) liquid-vapor interface. This pressure response was compared with both the experimental results and an adiabatic decompression computation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/62635','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/62635"><span id="translatedtitle">Safe <span class="hlt">venting</span> of ``red oil`` runaway reactions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Paddleford, D.F.; Fauske, H.K.</p> <p>1994-12-21</p> <p>Calorimetry testing of Tri-n-butyl phosphate (TBP) saturated with strong nitric acid was performed to determine the relationship between <span class="hlt">vent</span> size and pressure buildup in the event of a runaway reaction. These experiments show that runaway can occur in an open system, but that even when runaway is induced in the TBP/HN0{sub 3} system, dangerous pressure buildup will be prevented with practical <span class="hlt">vent</span> size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002seip.conf....7S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002seip.conf....7S"><span id="translatedtitle">Hydrothermal <span class="hlt">Vents</span> of Juan de Fuca Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stark, Joyce</p> <p></p> <p>As a member of REVEL (Research and Education: Volcanoes, Exploration and Life), I had an opportunity to participant in a scientific research cruise focused on the <span class="hlt">active</span> volcanoes along the Juan de Fuca Ridge, the submarine spreading center off the Washington- Oregon-Canada coast. REVEL was sponsored by the National Science Foundation, University of Washington, Pennsylvania State University and the American Museum of Natural History. We studied the geological, chemical and biological processes associated with <span class="hlt">active</span> hydrothermal systems and my research focused on the biological communities of the sulfide structures. We worked on board the Woods Hole Oceanographic Institution Vessel, R/V Atlantis and the submersible ALVIN was used to sample the "Black Smokers". As a member of the scientific party, I participated in collection and sorting of biological specimens from the <span class="hlt">vent</span> communities, attended lectures by scientists, contributed to the cruise log website, maintained a journal and developed my own research project. It was my responsibility to bring this cutting-edge research back to the classroom.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GGG.....7.8007L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GGG.....7.8007L"><span id="translatedtitle">Submarine <span class="hlt">venting</span> of liquid carbon dioxide on a Mariana Arc volcano</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lupton, John; Butterfield, David; Lilley, Marvin; Evans, Leigh; Nakamura, Ko-Ichi; Chadwick, William; Resing, Joseph; Embley, Robert; Olson, Eric; Proskurowski, Giora; Baker, Edward; de Ronde, Cornel; Roe, Kevin; Greene, Ronald; Lebon, Geoff; Young, Conrad</p> <p>2006-08-01</p> <p>Although CO2 is generally the most abundant dissolved gas found in submarine hydrothermal <span class="hlt">fluids</span>, it is rarely found in the form of CO2 liquid. Here we report the discovery of an unusual CO2-rich hydrothermal system at 1600-m depth near the summit of NW Eifuku, a small submarine volcano in the northern Mariana Arc. The site, named Champagne, was found to be discharging two distinct <span class="hlt">fluids</span> from the same <span class="hlt">vent</span> field: a 103°C gas-rich hydrothermal <span class="hlt">fluid</span> and cold (<4°C) droplets composed mainly of liquid CO2. The hot <span class="hlt">vent</span> <span class="hlt">fluid</span> contained up to 2.7 moles/kg CO2, the highest ever reported for submarine hydrothermal <span class="hlt">fluids</span>. The liquid droplets were composed of ˜98% CO2, ˜1% H2S, with only trace amounts of CH4 and H2. Surveys of the overlying water column plumes indicated that the <span class="hlt">vent</span> <span class="hlt">fluid</span> and buoyant CO2 droplets ascended <200 m before dispersing into the ocean. Submarine <span class="hlt">venting</span> of liquid CO2 has been previously observed at only one other locality, in the Okinawa Trough back-arc basin (Sakai et al., 1990a), a geologic setting much different from NW Eifuku, which is a young arc volcano. The discovery of such a high CO2 flux at the Champagne site, estimated to be about 0.1% of the global MOR carbon flux, suggests that submarine arc volcanoes may play a larger role in oceanic carbon cycling than previously realized. The Champagne field may also prove to be a valuable natural laboratory for studying the effects of high CO2 concentrations on marine ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7050356','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7050356"><span id="translatedtitle"><span class="hlt">Vented</span> coke oven door apparatus</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Brown, H. B.; Gerding, C. C.</p> <p>1980-08-12</p> <p>A <span class="hlt">vented</span> coke oven door includes a door frame having a vertical face surface carrying a plug assembly having a central vertical internal opening to conduct coke oven gas generated at the bottom of a coal charge in a coke oven chamber. The plug assembly includes a plurality of u-shaped refractory plug segments arranged in an end-to-end aligned relation with leg sections of each u-shaped segment extending horizontally into an abutting relation with the face surface of the door frame. Each leg section carries either an embedded hooked end or a t-shaped head of a threaded fastener which is supported by the door frame so that the leg sections are unrestrained against movement toward and away from each other in response to a thermal gradient across the wall thickness of the refractory plug segment. A backing plug plate is fitted into a recess in the leg sections of each plug segment to provide a closure wall to the u-shaped configuration of the segments and forms the vertical passageway for conducting coke oven gas. The backing plug plate has an exposed layer of cast refractory overlying a layer of insulation used to protect the door frame. A seal strip extends about the outer periphery of the door frame to prevent emission of coke oven gas from the coking chamber.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26416846','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26416846"><span id="translatedtitle">Cerebrospinal <span class="hlt">Fluid</span> Hypernatremia Elevates Sympathetic Nerve <span class="hlt">Activity</span> and Blood Pressure via the Rostral Ventrolateral Medulla.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stocker, Sean D; Lang, Susan M; Simmonds, Sarah S; Wenner, Megan M; Farquhar, William B</p> <p>2015-12-01</p> <p>Elevated NaCl concentrations of the cerebrospinal <span class="hlt">fluid</span> increase sympathetic nerve <span class="hlt">activity</span> (SNA) in salt-sensitive hypertension. Neurons of the rostral ventrolateral medulla (RVLM) play a pivotal role in the regulation of SNA and receive mono- or polysynaptic inputs from several hypothalamic structures responsive to hypernatremia. Therefore, the present study investigated the contribution of RVLM neurons to the SNA and pressor response to cerebrospinal <span class="hlt">fluid</span> hypernatremia. Lateral ventricle infusion of 0.15 mol/L, 0.6 mol/L, and 1.0 mol/L NaCl (5 µL/10 minutes) produced concentration-dependent increases in lumbar SNA, adrenal SNA, and arterial blood pressure, despite no change in splanchnic SNA and a decrease in renal SNA. Ganglionic blockade with chlorisondamine or acute lesion of the lamina terminalis blocked or significantly attenuated these responses, respectively. RVLM microinjection of the gamma-aminobutyric acid (GABAA) agonist muscimol abolished the sympathoexcitatory response to intracerebroventricular infusion of 1 mol/L NaCl. Furthermore, blockade of ionotropic glutamate, but not angiotensin II type 1, receptors significantly attenuated the increase in lumbar SNA, adrenal SNA, and arterial blood pressure. Finally, single-unit recordings of spinally projecting RVLM neurons revealed 3 distinct populations based on discharge responses to intracerebroventricular infusion of 1 mol/L NaCl: type I excited (46%; 11/24), type II inhibited (37%; 9/24), and type III no change (17%; 4/24). All neurons with slow conduction velocities were type I cells. Collectively, these findings suggest that acute increases in cerebrospinal <span class="hlt">fluid</span> NaCl concentrations selectively <span class="hlt">activate</span> a discrete population of RVLM neurons through glutamate receptor <span class="hlt">activation</span> to increase SNA and arterial blood pressure. PMID:26416846</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24371721','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24371721"><span id="translatedtitle">Quantitation of fibroblast <span class="hlt">activation</span> protein (FAP)-specific protease <span class="hlt">activity</span> in mouse, baboon and human <span class="hlt">fluids</span> and organs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Keane, Fiona M; Yao, Tsun-Wen; Seelk, Stefanie; Gall, Margaret G; Chowdhury, Sumaiya; Poplawski, Sarah E; Lai, Jack H; Li, Youhua; Wu, Wengen; Farrell, Penny; Vieira de Ribeiro, Ana Julia; Osborne, Brenna; Yu, Denise M T; Seth, Devanshi; Rahman, Khairunnessa; Haber, Paul; Topaloglu, A Kemal; Wang, Chuanmin; Thomson, Sally; Hennessy, Annemarie; Prins, John; Twigg, Stephen M; McLennan, Susan V; McCaughan, Geoffrey W; Bachovchin, William W; Gorrell, Mark D</p> <p>2013-01-01</p> <p>The protease fibroblast <span class="hlt">activation</span> protein (FAP) is a specific marker of <span class="hlt">activated</span> mesenchymal cells in tumour stroma and fibrotic liver. A specific, reliable FAP enzyme assay has been lacking. FAP's unique and restricted cleavage of the post proline bond was exploited to generate a new specific substrate to quantify FAP enzyme <span class="hlt">activity</span>. This sensitive assay detected no FAP <span class="hlt">activity</span> in any tissue or <span class="hlt">fluid</span> of FAP gene knockout mice, thus confirming assay specificity. Circulating FAP <span class="hlt">activity</span> was ∼20- and 1.3-fold less in baboon than in mouse and human plasma, respectively. Serum and plasma contained comparable FAP <span class="hlt">activity</span>. In mice, the highest levels of FAP <span class="hlt">activity</span> were in uterus, pancreas, submaxillary gland and skin, whereas the lowest levels were in brain, prostate, leukocytes and testis. Baboon organs high in FAP <span class="hlt">activity</span> included skin, epididymis, bladder, colon, adipose tissue, nerve and tongue. FAP <span class="hlt">activity</span> was greatly elevated in tumours and associated lymph nodes and in fungal-infected skin of unhealthy baboons. FAP <span class="hlt">activity</span> was 14- to 18-fold greater in cirrhotic than in non-diseased human liver, and circulating FAP <span class="hlt">activity</span> was almost doubled in alcoholic cirrhosis. Parallel DPP4 measurements concorded with the literature, except for the novel finding of high DPP4 <span class="hlt">activity</span> in bile. The new FAP enzyme assay is the first to be thoroughly characterised and shows that FAP <span class="hlt">activity</span> is measurable in most organs and at high levels in some. This new assay is a robust tool for specific quantitation of FAP enzyme <span class="hlt">activity</span> in both preclinical and clinical samples, particularly liver fibrosis. PMID:24371721</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3871272','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3871272"><span id="translatedtitle">Quantitation of fibroblast <span class="hlt">activation</span> protein (FAP)-specific protease <span class="hlt">activity</span> in mouse, baboon and human <span class="hlt">fluids</span> and organs☆</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Keane, Fiona M.; Yao, Tsun-Wen; Seelk, Stefanie; Gall, Margaret G.; Chowdhury, Sumaiya; Poplawski, Sarah E.; Lai, Jack H.; Li, Youhua; Wu, Wengen; Farrell, Penny; Vieira de Ribeiro, Ana Julia; Osborne, Brenna; Yu, Denise M.T.; Seth, Devanshi; Rahman, Khairunnessa; Haber, Paul; Topaloglu, A. Kemal; Wang, Chuanmin; Thomson, Sally; Hennessy, Annemarie; Prins, John; Twigg, Stephen M.; McLennan, Susan V.; McCaughan, Geoffrey W.; Bachovchin, William W.; Gorrell, Mark D.</p> <p>2013-01-01</p> <p>The protease fibroblast <span class="hlt">activation</span> protein (FAP) is a specific marker of <span class="hlt">activated</span> mesenchymal cells in tumour stroma and fibrotic liver. A specific, reliable FAP enzyme assay has been lacking. FAP's unique and restricted cleavage of the post proline bond was exploited to generate a new specific substrate to quantify FAP enzyme <span class="hlt">activity</span>. This sensitive assay detected no FAP <span class="hlt">activity</span> in any tissue or <span class="hlt">fluid</span> of FAP gene knockout mice, thus confirming assay specificity. Circulating FAP <span class="hlt">activity</span> was ∼20- and 1.3-fold less in baboon than in mouse and human plasma, respectively. Serum and plasma contained comparable FAP <span class="hlt">activity</span>. In mice, the highest levels of FAP <span class="hlt">activity</span> were in uterus, pancreas, submaxillary gland and skin, whereas the lowest levels were in brain, prostate, leukocytes and testis. Baboon organs high in FAP <span class="hlt">activity</span> included skin, epididymis, bladder, colon, adipose tissue, nerve and tongue. FAP <span class="hlt">activity</span> was greatly elevated in tumours and associated lymph nodes and in fungal-infected skin of unhealthy baboons. FAP <span class="hlt">activity</span> was 14- to 18-fold greater in cirrhotic than in non-diseased human liver, and circulating FAP <span class="hlt">activity</span> was almost doubled in alcoholic cirrhosis. Parallel DPP4 measurements concorded with the literature, except for the novel finding of high DPP4 <span class="hlt">activity</span> in bile. The new FAP enzyme assay is the first to be thoroughly characterised and shows that FAP <span class="hlt">activity</span> is measurable in most organs and at high levels in some. This new assay is a robust tool for specific quantitation of FAP enzyme <span class="hlt">activity</span> in both preclinical and clinical samples, particularly liver fibrosis. PMID:24371721</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813981W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813981W"><span id="translatedtitle">Pulses of earthquake <span class="hlt">activity</span> in the mantle wedge track the route of slab <span class="hlt">fluid</span> ascent</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>White, Lloyd; Rawlinson, Nicholas; Lister, Gordon; Tanner, Dominique; Macpherson, Colin; Morgan, Jason</p> <p>2016-04-01</p> <p>Earthquakes typically record the brittle failure of part of the Earth at a point in space and time. These almost invariably occur within the crust or where the upper surface of subducting lithosphere interacts with the overriding mantle. However, there are also reports of rare, enigmatic earthquakes beneath rifts, above mantle plumes or very deep in the mantle. Here we report another type of mantle earthquake and present three locations where earthquake clusters occur in the mantle wedge overlying <span class="hlt">active</span> subduction zones. These earthquake clusters define broadly circular to ellipsoidal columns that are 50 km or greater in diameter from depths between ~150 km and the surface. We interpret these rare pulses of earthquakes as evidence of near vertical transport of <span class="hlt">fluids</span> (and associated flux-melts) from the subducted lithosphere through the mantle wedge. Detailed temporal analysis shows that most of these earthquakes occur over two-year periods, with the majority of events occurring in discrete month-long flurries of <span class="hlt">activity</span>. As the time and location of each earthquake is recorded, pulses of seismic <span class="hlt">activity</span> may provide information about the rate of magma ascent from the dehydrated subducted slab to sub-arc/backarc crust. This work indicates that <span class="hlt">fluids</span> are not transported through the mantle wedge by diapirism, but through sub-vertical pathways facilitated by fracture networks and dykes on monthly to yearly time scales. These rare features move us toward solving what has until now represented a missing component of the subduction factory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26651694','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26651694"><span id="translatedtitle">Role of interfacial friction for flow instabilities in a thin polar-ordered <span class="hlt">active</span> <span class="hlt">fluid</span> layer.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sarkar, Niladri; Basu, Abhik</p> <p>2015-11-01</p> <p>We construct a generic coarse-grained dynamics of a thin inflexible planar layer of polar-ordered suspension of <span class="hlt">active</span> particles that is frictionally coupled to an embedding isotropic passive <span class="hlt">fluid</span> medium with a friction coefficient Γ. Being controlled by Γ, our model provides a unified framework to describe the long-wavelength behavior of a variety of thin polar-ordered systems, ranging from wet to dry <span class="hlt">active</span> matter and free-standing <span class="hlt">active</span> films. Investigations of the linear instabilities around a chosen orientationally ordered uniform reference state reveal generic moving and static instabilities in the system that can depend sensitively on Γ. Based on our results, we discuss estimation of bounds on Γ in experimentally accessible systems. PMID:26651694</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26742682','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26742682"><span id="translatedtitle">Nonequilibrium phase transitions, fluctuations and correlations in an <span class="hlt">active</span> contractile polar <span class="hlt">fluid</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gowrishankar, Kripa; Rao, Madan</p> <p>2016-02-21</p> <p>We study the patterning, fluctuations and correlations of an <span class="hlt">active</span> polar <span class="hlt">fluid</span> consisting of contractile polar filaments on a two-dimensional substrate, using a hydrodynamic description. The steady states generically consist of arrays of inward pointing asters and show a continuous transition from a moving lamellar phase, a moving aster street, to a stationary aster lattice with no net polar order. We next study the effect of spatio-temporal athermal noise, parametrized by an <span class="hlt">active</span> temperature TA, on the stability of the ordered phases. In contrast to its equilibrium counterpart, we find that the <span class="hlt">active</span> crystal shows true long range order at low TA. On increasing TA, the asters dynamically remodel, concomitantly we find novel phase transitions characterized by bond-orientational and polar order upon "heating". PMID:26742682</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvE..92e2306S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvE..92e2306S"><span id="translatedtitle">Role of interfacial friction for flow instabilities in a thin polar-ordered <span class="hlt">active</span> <span class="hlt">fluid</span> layer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sarkar, Niladri; Basu, Abhik</p> <p>2015-11-01</p> <p>We construct a generic coarse-grained dynamics of a thin inflexible planar layer of polar-ordered suspension of <span class="hlt">active</span> particles that is frictionally coupled to an embedding isotropic passive <span class="hlt">fluid</span> medium with a friction coefficient Γ . Being controlled by Γ , our model provides a unified framework to describe the long-wavelength behavior of a variety of thin polar-ordered systems, ranging from wet to dry <span class="hlt">active</span> matter and free-standing <span class="hlt">active</span> films. Investigations of the linear instabilities around a chosen orientationally ordered uniform reference state reveal generic moving and static instabilities in the system that can depend sensitively on Γ . Based on our results, we discuss estimation of bounds on Γ in experimentally accessible systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4175459','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4175459"><span id="translatedtitle">Heat and Mass Transfer in Unsteady Rotating <span class="hlt">Fluid</span> Flow with Binary Chemical Reaction and <span class="hlt">Activation</span> Energy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Awad, Faiz G.; Motsa, Sandile; Khumalo, Melusi</p> <p>2014-01-01</p> <p>In this study, the Spectral Relaxation Method (SRM) is used to solve the coupled highly nonlinear system of partial differential equations due to an unsteady flow over a stretching surface in an incompressible rotating viscous <span class="hlt">fluid</span> in presence of binary chemical reaction and Arrhenius <span class="hlt">activation</span> energy. The velocity, temperature and concentration distributions as well as the skin-friction, heat and mass transfer coefficients have been obtained and discussed for various physical parametric values. The numerical results obtained by (SRM) are then presented graphically and discussed to highlight the physical implications of the simulations. PMID:25250830</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DFDM33004K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DFDM33004K"><span id="translatedtitle">Inside Out: <span class="hlt">Active</span> learning in <span class="hlt">fluid</span> dynamics in and out of the classroom</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaye, Nigel; Benson, Lisa; Sill, Ben</p> <p>2014-11-01</p> <p><span class="hlt">Active</span> learning can be broadly defined as any <span class="hlt">activity</span> that engages students beyond just listening. But is it worth the effort, when we can just lecture and tell students all they need to know? Learning theories posit that students remember far more of what they say and do than of what they hear and see. The benefits of <span class="hlt">active</span> learning include increased attendance (because class is now something different and attending is more worthwhile) and deeper understanding of concepts (because students get to practice answering and generating questions). A recent meta-analysis of research on <span class="hlt">active</span> learning has summarized evidence of real outcomes of <span class="hlt">active</span> learning. Research is showing that students' performance on exams are higher and that they fail at lower rates in classes that involve <span class="hlt">active</span> learning compared to traditional lecturing. Other studies have shown evidence of improved performance in follow-on classes, showing that the improved learning lasts. There are some topics and concepts that are best taught (or at least introduced) through lecturing, but even lecturing can be broken up by short <span class="hlt">activities</span> that engage students so they learn more effectively. In this presentation, we will review the findings of the meta study and provide examples of <span class="hlt">active</span> learning both inside and outside the classroom that demonstrate simple ways of introducing this approach in <span class="hlt">fluid</span> dynamics classes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009DSRII..56.1586M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009DSRII..56.1586M"><span id="translatedtitle">Post-eruption succession of macrofaunal communities at diffuse flow hydrothermal <span class="hlt">vents</span> on Axial Volcano, Juan de Fuca Ridge, Northeast Pacific</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marcus, Jean; Tunnicliffe, Verena; Butterfield, David A.</p> <p>2009-09-01</p> <p>Hydrothermal <span class="hlt">vents</span> harbor dense aggregations of invertebrate fauna supported by chemosynthesis. Severe tectonic events and volcanic eruptions frequently destroy <span class="hlt">vent</span> communities and initiate primary succession at new <span class="hlt">vents</span> on ridge-crest submarine lava flows. An eruption on Axial Volcano (˜1500 m depth), a seamount on the Juan de Fuca Ridge (JdFR) in the northeast Pacific Ocean, occurred in January 1998, which created new substratum and <span class="hlt">vents</span>. This study examines the development of the macrofaunal <span class="hlt">vent</span> assemblages associated with tubeworms ( Ridgeia piscesae) at eight diffuse flow <span class="hlt">vents</span> over the following 3 years. Biological collections by suction of lava surfaces also characterized "pre-tubeworm assemblages". Coupled <span class="hlt">fluid</span> sampling showed an overall decrease in temperature, sulphide, and sulphide-to-heat ratios over 3 years as well as large spatial variability across the new <span class="hlt">vents</span>. We examined collections of pre-eruption diffuse flow <span class="hlt">vent</span> assemblages at Axial Volcano to compare the stages of new community development to "mature" <span class="hlt">vents</span>. Mature <span class="hlt">vent</span> assemblages are characterized by two major community types dominated by limpets ( Lepetodrilus fucensis) and alvinellid polychaetes ( Paralvinella pandorae and/or P. palmiformis). The following post-eruption succession patterns emerged. First, R. piscesae tubeworms took up to 3 years to establish aggregations at the new <span class="hlt">vents</span>, and the majority of pre-tubeworm assemblages were dominated by grazing polychaetes. Second, species colonized quickly and by 30 months after habitat creation >60% of Axial's species pool had arrived at the new <span class="hlt">vents</span>; abundance at mature <span class="hlt">vents</span> predicted colonization success with some notable exceptions. Third, shifts in species dominance occurred rapidly and by Year 3 new <span class="hlt">vent</span> assemblages resembled mature, pre-eruption communities. In general, tubeworm assemblages were dominated by alvinellid polychaetes ( P. pandorae and P. palmiformis) in the first 2 years post-eruption, with limpets ( L</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4620420','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4620420"><span id="translatedtitle">Geomicrobiology of sublacustrine thermal <span class="hlt">vents</span> in Yellowstone Lake: geochemical controls on microbial community structure and function</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Inskeep, William P.; Jay, Zackary J.; Macur, Richard E.; Clingenpeel, Scott; Tenney, Aaron; Lovalvo, David; Beam, Jacob P.; Kozubal, Mark A.; Shanks, W. C.; Morgan, Lisa A.; Kan, Jinjun; Gorby, Yuri; Yooseph, Shibu; Nealson, Kenneth</p> <p>2015-01-01</p> <p>Yellowstone Lake (Yellowstone National Park, WY, USA) is a large high-altitude (2200 m), fresh-water lake, which straddles an extensive caldera and is the center of significant geothermal <span class="hlt">activity</span>. The primary goal of this interdisciplinary study was to evaluate the microbial populations inhabiting thermal <span class="hlt">vent</span> communities in Yellowstone Lake using 16S rRNA gene and random metagenome sequencing, and to determine how geochemical attributes of <span class="hlt">vent</span> waters influence the distribution of specific microorganisms and their metabolic potential. Thermal <span class="hlt">vent</span> waters and associated microbial biomass were sampled during two field seasons (2