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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. Aqueous Volatiles in Hydrothermal fluids from the Main Endeavour Vent Field: Temporal Variability Following Earthquake Activity

    NASA Astrophysics Data System (ADS)

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

    2001-12-01

    Volatile species play a critical role in a broad spectrum of physical, chemical, and biological processes associated with hydrothermal circulation at oceanic spreading centers. Earthquake activity at the Main Endeavour vent field, northern Juan de Fuca Ridge in June 1999 [1] provided and opportunity to assess factors that regulate the flux of volatile species from the oceanic crust to the water column following a rapid change in subsurface reaction zone conditions. High temperature vent fluids were collected in gas-tight samplers at the Main Endeavour field in September 1999, approximately four months after the earthquakes, and again in July 2000, and were analyzed for the abundance of aqueous volatile and non-volatile species. Measured concentrations of aqueous H2, H2S, and CO2 increased substantially in September 1999 relative to pre-earthquake values [2,3], and subsequently decreased in July 2000, while aqueous Cl concentrations initially decreased in 1999 and subsequently increased in 2000. Concentrations of Cl in all fluids were depleted relative to seawater values. Aqueous CH4 and NH3 concentrations decreased in both the 1999 and 2000 samples relative to pre- earthquake values. Variations in Cl concentration of Endeavour fluids reflect varying degrees of phase separation under near critical temperature and pressure conditions. Because volatile species efficiently partition into the vapor phase, variations in their abundance as a function of Cl concentration can be used to constrain conditions of phase separation and fluid-rock interaction. For example, concentrations of volatile species that are not readily incorporated into minerals (CH4 and NH3) correlated weakly with Cl suggesting phase separation was occurring under supercritical conditions after the earthquake activity. In contrast, compositional data for fluids prior to the earthquakes indicate a strong negative correlation between these species and Cl suggesting phase separation under subcritical

  3. First hydroacoustic evidence of marine, active fluid vents in the Naples Bay continental shelf (Southern Italy)

    NASA Astrophysics Data System (ADS)

    Passaro, Salvatore; Genovese, Simona; Sacchi, Marco; Barra, Marco; Rumolo, Paola; Tamburrino, Stella; Mazzola, Salvatore; Basilone, Gualtiero; Placenti, Francesco; Aronica, Salvatore; Bonanno, Angelo

    2014-09-01

    We present the first results of a multidisciplinary research aimed at the detection and mapping of Active Fluid Vents (AFVs) at the seafloor of the Naples Bay, Italy. This segment of the Campania continental margin is characterised by severe Quaternary extension and intense volcanism at Ischia and Procida islands, the Campi Flegrei and Somma-Vesuvius volcanic complexes. High resolution hydroacoustic profilers were used to identify and localize fluid emission from the seafloor. ROV direct observation showed that each emission centre is generally composed by the coalescence of several emitting points. CTD probes showed that there are no significant gradients in temperature profiles. The results of this study include the detection and mapping of 54 fluid emission points all located in the - 71/- 158 m depth range, and spatially distributed into four main clusters. Three of the described clusters are located along the margin of a complex, toe-shaped seafloor morphology southwest of the Somma-Vesuvius, representing the shallow expression of partly buried, coalesced depositional features (namely, two flank collapses and one pyroclastic flow) associated with the Late Pleistocene activity of the volcano. The fourth AFV cluster was detected at the morphological - high, located about 8 km south of Naples (Banco della Montagna), represented by a field of volcaniclastic diapirs composed of massive pumiceous deposits originated from the Campi Flegrei intruding rising through the latest Quaternary-Holocene marine deposits. Our study suggests that the occurrence of AFV in this area could be genetically linked to the interaction between volcanic related seafloor morphologies and the main, NE striking faults present in the area, i.e. the Magnaghi-Sebeto line and the Vesuvian fault.

  4. 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.

  5. Geochemical constraints on the diversity and activity of H2 -oxidizing microorganisms in diffuse hydrothermal fluids from a basalt- and an ultramafic-hosted vent.

    PubMed

    Perner, Mirjam; Petersen, Jillian M; Zielinski, Frank; Gennerich, Hans-Hermann; Seifert, Richard

    2010-10-01

    Mixing processes of reduced hydrothermal fluids with oxygenated seawater and fluid-rock reactions contribute to the chemical signatures of diffuse venting and likely determine the geochemical constraints on microbial life. We examined the influence of fluid chemistry on microbial diversity and activity by sampling diffuse fluids emanating through mussel beds at two contrasting hydrothermal vents. The H(2) concentration was very low at the basalt-hosted Clueless site, and mixing models suggest O(2) availability throughout much of the habitat. In contrast, effluents from the ultramafic-hosted Quest site were considerably enriched in H(2) , while O(2) is likely limited to the mussel layer. Only two different hydrogenase genes were identified in clone libraries from the H(2) -poor Clueless fluids, but these fluids exhibited the highest H(2) uptake rates in H(2) -spiked incubations (oxic conditions, at 18 °C). In contrast, a phylogenetically diverse H(2) -oxidizing potential was associated with distinct thermal conditions in the H(2) -rich Quest fluids, but under oxic conditions, H(2) uptake rates were extremely low. Significant stimulation of CO(2) fixation rates by H(2) addition was solely illustrated in Quest incubations (P-value <0.02), but only in conjunction with anoxic conditions (at 18 °C). We conclude that the factors contributing toward differences in the diversity and activity of H(2) oxidizers at these sites include H(2) and O(2) availability.

  6. 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.

  7. The geochemical controls on vent fluids from the Lucky Strike vent field, Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Von Damm, K. L.; Bray, A. M.; Buttermore, L. G.; Oosting, S. E.

    1998-08-01

    Hydrothermal vent fluids were collected from the Lucky Strike site at 37°17'N on the Mid-Atlantic Ridge in both 1993 and 1996. Seven vents were sampled with the DSV Alvin in 1993 and six vents were sampled in 1996 using the ROV Jason during the LUSTRE '96 Cruise. As three of the vents were sampled in both 1993 and in 1996, a time series of vent fluid chemistry is also reported. Measured temperatures ranged from 202 to 333°C at the 1618-1726 m depth of the vent field, which is located on Lucky Strike Seamount. These fluids are either equal to or less than the local bottom seawater in chlorinity. While the range in fluid compositions at Lucky Strike is generally within that observed elsewhere, the unusual aspects of the fluid chemistries are the relatively high pH and low Fe, Mn, Li and Zn. We attribute this, as well as an usually low Sr/Ca ratio, to reaction with a highly altered substrate. The high Si and Cu contents suggest a deep, as well as hot, source for these fluids. The fluid compositions therefore suggest formation by super-critical phase separation at a depth not less than 1300 m below the seafloor, and reaction with a relatively oxic, and previously altered, substrate. There is temporal variability in some of the vent fluid compositions as Li, K, Ca and Fe concentrations have increased in some of the vents, as has the Fe/Mn (molar) ratio, although the chlorinities have remained essentially constant from 1993 to 1996. While there is not a simple relationship between vent fluid compositions (or temperatures) and distance from the lava lake at the summit of the seamount, the vent fluids from many of the vents can be shown to be related to others, often at distances >200 m. The most southeasterly vents (Eiffel Tower and the Marker/Mounds vents) are distinct in chlorinity and other chemical parameters from the rest of the vents, although closely related to each other within the southeastern area. Similarly all of the vents not in this one area, appear

  8. Sulfur Isotope Geochemistry of the Lost City Hydrothermal Vent Fluids

    NASA Astrophysics Data System (ADS)

    Frueh-Green, G. L.; Bernasconi, S. M.; Butterfield, D. A.; Kelley, D. S.

    2004-12-01

    At the Lost City Hydrothermal Vent Field (Mid-Atlantic Ridge, 30° N), reactions between seawater and ultramafic rocks produce high alkaline (pH 9 to 11) fluids that are venting at temperatures of 40 to 90° C and result in the formation of up to 60m tall carbonate-brucite structures. The fluids are enriched in hydrogen, methane and other hydrocarbons, and support dense microbial communities. We present sulfur isotope data of dissolved sulfate and coexisting sulfide in the fluids venting at Lost City, which together with C-isotope data provide constraints on the links between chemical and biological processes associated with serpentinization. The sulfur isotope composition of sulfate increases from seawater values of +21‰ (VCDT) in fluids with sulfate concentrations of 28 mM to values of up to +30‰ in the low sulfate-, high pH end-member hydrothermal fluids. Sulfide concentrations range between 50 and 2780 micromolar. Sulfur isotope compositions of the sulfides lie in a narrow range of +34 to +37‰ (VCDT) and show no clear correlation with concentrations. The isotopic compositions of dissolved inorganic carbon vary between -0.5‰ (VPDB) in the high sulfate samples and -18‰ in the low sulfate samples. This covariance indicates active sulfate reduction in the vent structures and/or in the shallow serpentinite subsurface. Sulfate reduction likely contributes to the variability of carbon isotope compositions observed in both the dissolved inorganic carbon and the carbonate minerals forming the structures. These data, together with C- and O-isotope data of the vent structures, provide evidence that methane oxidation coupled with sulfate reduction during mixing of the more pristine, hydrogen and methane-rich hydrothermal end-member fluids with seawater is an important process in hydrothermal carbonate precipitation at Lost City. Our results are consistent with previous microbiological and organic geochemical studies, which indicate a close association of methane

  9. Vented piston seal prevents fluid leakage between two chambers

    NASA Technical Reports Server (NTRS)

    Mac Glashan, W. F.; Morrison, R.

    1964-01-01

    To prevent fluid leakage around piston seals separating two fluids under differential pressure, a venting system has been devised. Two methods may be used for venting seals through internal passages to an external low-pressure area, O-ring or split-ring seals.

  10. Relationship between carbonate deposits and fluid venting: Oregon Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Kulm, Laverne D.; Suess, Erwin

    1990-06-01

    Active fluid venting and its surface manifestations (unique animals and carbonates) occur over the accretionary prism in the Cascadia subduction zone located off central Oregon. A large variety of authigenic carbonate deposits and unique carbonate structures have been observed from submersibles and remotely operated vehicles and recovered with aid of submersibles and bottom trawls from the outermost continental shelf and lower continental slope. The carbonate deposits range from relatively thin crusts and slabs to irregular edifices and well-formed circular chimneys that rise from 1 to 2 m above the seafloor. Mineralogically, the carbonate cement consists of aragonite, calcite, Mg-calcite, or dolomite with varying amounts of detrital constituents. Stable carbon and oxygen isotope data identify four distinct subgroups of methane-derived carbonates from several different vent sites and different fluid source zones. Subgroup I represents one vent site on the lower slope and is characterized by oxygen isotope values ranging from +6.8‰ to +4.7‰ PDB. Subgroup II represents another vent site about 1 km away and exhibits oxygen values of +3.4‰ to +4.9‰ PDB. Carbon isotopic values range from -40.96 to -30.23‰ versus -44.26 to -53.44‰ PDB, respectively, for the two vents. An irregular edifice from the outer shelf has the same isotopic composition as subgroup II. A companion study shows that the expelled fluids contain largely biogenic methane and methane-derived dissolved carbonate; a shallow fluid source zone (<1 km) is indicated. The isotopic carbon values of the subgroup I and II carbonates are consistent with the carbon composition of the expelled fluids and apparently represent a historical record of the composition of these fluids. In subgroup III, strong 18O enrichment and heavier carbon values characterize the dolomitic chimneys from the outer continental shelf. Cemented sandstones from a "window" in the accretionary complex of the lower slope (subgroup

  11. 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

  12. 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.

  13. 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

  14. 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

  15. Overview of Vent Fluid Chemistry From the Marianas Volcanic Arc

    NASA Astrophysics Data System (ADS)

    Butterfield, D. A.; Roe, K. K.; Bolton, S. A.; Baross, J. A.; Lupton, J. E.; Lilley, M. D.; Embley, R. W.; Chadwick, W. W.; Resing, J. A.

    2004-12-01

    In March and April 2004, a research expedition on the R.V.T.G. Thompason with the ROV ROPOS investigated and sampled hydrothermal systems on six submarine volcanoes of the Marianas volcanic arc between 14.3 and 21.5 degrees N. In this two-year project sponsored by NOAA Ocean Exploration, dive targets were selected based on bathymetric and hydrothermal plume mapping conducted in 2003. Hydrothermal plume intesity and chemistry was used with success to target and sample a remarkable variety of volcanic and hydrothermal features. At NW Rota-1 submarine volcano, there is clear evidence of ongoing eruptive activity producing clouds of particulate and molten sulfur as well as mm to cm-size glassy volcanic ejecta. Fluids (34 deg C) sampled directly from an eruptive pit crater has pH of 2.0, with a high content of particulated sulfur, excess sulfate relative to seawater, and very low H2s content. Fluids percolating through volcaniclastic sand adjacent to the pit reached 100 deg C and had higher silica, slightly higher pH, and millimolar levels of H2s. The chemistry of both types of fluids is indicative of input of volcanic SO2 and disproportionation into sulfate and H2s (in volcaniclastic sands) and elemental sulfur (in the pit crater). Molten sulfur droplets indicate a high-temperature source at the base of the pit crater that rapidly mixes with seawater, while fluids venting through the sand remain hotter and react with volcanic glass. DNA was collected by in-situ filtration and both archaea and bacteria were amplified by PCR. Bacterial clone libraries were dominated by epsilon Proteobacteria with a high degree of relatedness to microaerophilic sulfur-, sulfide-, and hydrogen oxidizers belonging to the genera Sulfurimonas and Calderomonas. At East Diamante submarine volcano, several hydrothermal areas were found on resurgent domes within the large caldera. One of these sites hosted the only high-temperature deposits. The high volatile content of the volcanic arc

  16. In Situ Materials Study in Hot Hydrothermal Vent Fluid

    NASA Astrophysics Data System (ADS)

    Holland, P. M.; Schindele, W. J.; Holland, C. E.; Lilley, M. D.; Olson, E. J.

    2004-12-01

    We are developing methods and technology for in situ sampling and analysis of volatiles from hot hydrothermal vent fluids inside the mixing boundary. These fluids can reach temperatures of up to 400° C and are known to be corrosive to most materials. While titanium has been the material of choice for contact with these fluids, we wanted to assess whether other materials, such as Hastelloy or nickel might be suitable for in situ sampling from hydrothermal vents. For the present study, small (1/16" o.d.) tubes of chemically pure titanium, Hastelloy C, and Nickel 200 were prepared, using 316 stainless steel as a control. These were placed in an assembly with other test items, and inserted into the hydrothermal vent Sully in the Main Endeavor Field on the Juan de Fuca Plate in June 2003 by the Jason II ROV operated from the R/V Thompson. The assembly was retrieved 46 days later after exposure to approximately 360° C hydrothermal vent fluid at a depth of 2200 m. Inspection showed the stainless steel to be completely eroded away and nickel to be extensively corroded, however both the Hastelloy and titanium tubes were in excellent condition with the 0.030" i.d. passages in the tubes remaining open. Other test items included a miniature titanium filtered inlet fitting containing an 80 mesh titanium screen made of 0.004" (0.1 mm) chemically pure titanium wire, an Inconel washer and a sapphire ball. Apart from some discoloration, there appeared to be no significant degradation in these materials apart from signs of etching on the sapphire.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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

    2010-05-04

    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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Chemistry of hydrothermal vent fluids from the Main Endeavour Field, northern Juan de Fuca Ridge: Geochemical controls in the aftermath of June 1999 seismic events

    NASA Astrophysics Data System (ADS)

    Seyfried, W. E.; Seewald, J. S.; Berndt, M. E.; Ding, Kang; Foustoukos, D. I.

    2003-09-01

    In June 1999, an intense swarm of earthquakes occurred on the Endeavour segment of the Juan de Fuca Ridge influencing hydrothermal activity in and around the Main Endeavour Field (MEF). Here we report the dissolved concentrations of 31 species from five high-temperature vents sampled 3 months after the seismic event. The spatial variability of vent fluid chemistry is extreme. Vapor-dominated vent fluids at Cantilever and Sully sites have high measured temperatures (375°-379°C), high dissolved gas and boron concentrations, but low SiO2. Modeling results indicate that these fluids can be accounted for by supercritical phase separation and brine condensation. Other vent fluids have moderate temperatures (340°-366°C) and chloride concentrations (208-426 mmol/kg), and may result from mixing of supercritical, vapor-rich fluids with evolved seawater. Phase equilibria calculations indicate that in addition to chloride, redox, temperature, and especially pressure play key roles in accounting for compositional variability of vent fluids at MEF. In comparison with earlier (1988) data, the 1999 data set reveals significantly lower chloride concentrations and higher boron, whereas alkali and alkaline earth cations are lower by 10-20% in keeping with chloride decrease. That dissolved chloride, boron, and other elements returned to preevent levels when again sampled in 2000 provide additional data documenting the inherently dynamic nature of hydrothermal systems at mid-ocean ridges.

  9. 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

  10. 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

  11. Detection of putatively thermophilic anaerobic methanotrophs in diffuse hydrothermal vent fluids.

    PubMed

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

    2013-02-01

    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 (P(GC)) is significantly higher in the ANME-1GBa group than in other ANME groups. Based on the positive correlation between the P(GC) and optimal growth temperatures (T(opt)) 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

  12. 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

  13. 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

  14. Stable Isotope Evidence for Abiotic Ammonium Production in the Hydrothermal Vent Fluids from the Mid-Cayman Rise

    NASA Astrophysics Data System (ADS)

    Charoenpong, C.; Wankel, S. D.; Seewald, J.

    2015-12-01

    The Mid-Cayman Rise hosts the world's deepest (up to 4,987 meters) hydrothermal vent field, Piccard. Under the tremendous pressure, the vent fluid from Piccard can be as hot as 398°C. Here, the concentration of ammonium (35 μmol/kg) is much higher than that of the bottom water nitrate (22 μmol/kg). The undetectable nitrate in the vent fluid suggests that nitrate is completely reduced to ammonium in the reaction zone and there has to be an additional source for ammonium production. Because Piccard is unsedimented (i.e., lacking significant sedimentary organic matter), the other possible source of ammonium is the reduction of nitrogen gas (N2). We demonstrated that the isotopic composition of ammonium (δ15N-NH4+) for the Piccard vent fluid end-member (3.4 ± 0.1 ‰) supports the mixing between two ammonium sources: the reduction of nitrate and the reduction of N2. However, at Von Damm, shallower depth (up to 2,300 meters) causes the vent fluid to be relatively cooler (138°C) compared to Piccard and it is very likely that the reduction of nitrate is the only source of ammonium in the vent fluid. Studying the vent fluids from these sites where the temperatures are well above the upper limit for life can be useful in assessing the conditions and abiotic processes that might have given rise to the ammonium production in the early prebiotic ocean.

  15. Water-Rock Reaction, Substrate Composition, Magmatic Degassing, and Mixing as Major Factors Controlling Vent Fluid Compositions in Manus Basin Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Seewald, J.; Reeves, E.; Saccocia, P.; Rouxel, O.; Walsh, E.; Price, R.; Tivey, M.; Bach, W.; Tivey, M.

    2006-12-01

    A major objective of cruise MGLN06MV to the Manus Basin, north of Papua New Guinea, was the use of vent fluid chemistry as a guide to sub-seafloor processes occurring within four major areas of hydrothermal activity. A broad spectrum of high and low temperature fluids were sampled using gas-tight and syringe style "major" samplers from black smoker chimneys, white smoker spires, and igneous and sediment substrates. The majority of fluids exhibit salinities lower or higher than seawater, consistent with phase separation having occurred at or below the seafloor. Preliminary shipboard analyses of 273 to 285C vent fluids at the basalt- hosted Vienna Woods system (Manus Spreading Center) indicate that black/grey smoker fluids are characterized by compositions and pH similar to fluids sampled from other basalt-hosted (e.g., mid-ocean ridge (MOR)) systems. In contrast, the majority of fluids sampled from felsic-hosted hydrothermal systems in the eastern Manus Basin exhibit substantially lower pH and greater compositional variability within an individual vent field. High temperature fluids from four different areas of venting at the PACMANUS (Papua New Guinea Australia Canada Manus) vent field exhibit temperatures from 271 to 356C, pH from 2.3 to 2.8, H2 from 8 to 325 umol/l, H2S from 2.5 to 26 mmol/l, and CH4 from 8 to 39 umol/l. The low pH of these fluids (relative to MOR fluids) may reflect water-rock reaction with felsic rocks, input of magmatic volatiles (as proposed for the Mariner Field on the Valu Fa Ridge), and subsurface deposition of metal sulfides. Lower temperature fluids (80 to 180C) at PACMANUS exhibit higher pH (4.9 to 3.4). White smoker fluids (70 to 115C) collected at the DESMOS Caldera, were extraordinarily acidic (pH = 1.0 to 1.5), with very low H2S and CH4 concentrations. The composition of these fluids supports the hypothesis of Gamo et al. (Geology 25, 1997) that they reflect a mixture of magmatic volatiles and heated seawater. Fluids collected from

  16. Vent fluid chemistry in Bahía Concepción coastal submarine hydrothermal system, Baja California Sur, Mexico

    NASA Astrophysics Data System (ADS)

    Prol-Ledesma, R. M.; Canet, C.; Torres-Vera, M. A.; Forrest, M. J.; Armienta, M. A.

    2004-10-01

    Shallow submarine hydrothermal activity has been observed in the Bahía Concepción bay, located at the Gulf coast of the Baja California Peninsula, along faults probably related to the extensional tectonics of the Gulf of California region. Diffuse and focused venting of hydrothermal water and gas occurs in the intertidal and shallow subtidal areas down to 15 m along a NW-SE-trending onshore-offshore fault. Temperatures in the fluid discharge area vary from 50 °C at the sea bottom up to 87 °C at a depth of 10 cm in the sediments. Chemical analyses revealed that thermal water is enriched in Ca, As, Hg, Mn, Ba, HCO 3, Li, Sr, B, I, Cs, Fe and Si, and it has lower concentrations of Cl, Na, SO 4 and Br than seawater. The chemical characteristics of the water samples indicate the occurrence of mixing between seawater and a thermal end-member. Stable isotopic oxygen and hydrogen composition of thermal samples plot close to the Local Meteoric Water Line on a mixing trend between a thermal end-member and seawater. The composition of the thermal end-member was calculated from the chemistry of the submarine samples data by assuming a negligible amount of Mg for the thermal end-member. The results of the mixing model based on the chemical and isotopic composition indicate a maximum of 40% of the thermal end-member in the submarine vent fluid. Chemical geothermometers (Na/Li, Na-K-Ca and Si) were applied to the thermal end-member concentration and indicate a reservoir temperature of approximately 200 °C. The application of K-Mg and Na/Li geothermometers for vent fluids points to a shallow equilibrium temperature of about 120 °C. Results were integrated in a hydrogeological conceptual model that describes formation of thermal fluids by infiltration and subsequent heating of meteoric water. Vent fluid is generated by further mixing with seawater.

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 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 sediment pore water from

  6. 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

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

    PubMed Central

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

    2016-01-01

    Summary 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

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Denitrification in diffuse hydrothermal vent fluids of Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Bourbonnais, A.; Lehmann, M. F.; Butterfield, D. A.; Devol, A.; Chang, B. X.; Juniper, K.

    2009-12-01

    Denitrification is a major and well-investigated sink of bio-available nitrogen (N) in the ocean. However, little is known about the removal of N in diffuse hydrothermal vents. Hydrothermal vent fluids are known to harbor diverse bacterial populations, and the use of nitrate as an electron acceptor for the microbially mediated oxidation of hydrogen sulphide has previously been documented in these extreme environments, but no direct measurements of denitrification rates have been reported. We present the first denitrification rate estimates (i.e. the conversion of nitrate to nitrogen gas) derived from 15N-label incubations at 7 diffuse hydrothermal vent sites along the Juan de Fuca Ridge (North-East Pacific). Incubation samples (in-situ temperatures between 6.8 and 40.8οC) were collected during research cruises in June and August 2008. We also measured the isotopic composition of nitrate and ammonium from low-T sites collected during several cruises from 2006 to 2009. Mixing between ambient seawater and sub-seafloor hydrothermal reservoirs is the dominant process that modulates DIN concentration and isotope dynamics. However, clear signs of isotope fractionation of the N (and O of nitrate) isotopes at some sites suggests the presence of nitrate consuming processes, likely denitrification and/or the assimilation by vent microorganisms. 15N incubation-based denitrification rates ranged from 0 to 0.6 μM N/day, with no consistent relationship with the in-situ temperature of the vent fluids. With only one exception, detectable denitrification rates were determined at all sites, suggesting that denitrification is an important N-elimination process in diffuse vent fluids. Ongoing work that aims at studying the environmental factors that potentially control rates of denitrification (e.g. temperature, flow rate, fluid chemistry), as well as other possible N removal pathways (e.g. anammox and DNRA coupled to anammox), will also be discussed.

  17. 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

  18. 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

  19. Characterizing microbial community and geochemical dynamics at hydrothermal vents using osmotically driven continuous fluid samplers.

    PubMed

    Robidart, Julie; Callister, Stephen J; Song, Pengfei; Nicora, Carrie D; Wheat, Charles G; Girguis, Peter R

    2013-05-01

    Microbes play a key role in mediating aquatic biogeochemical cycles. However, our understanding of the relationships between microbial phylogenetic/physiological diversity and habitat physicochemical characteristics is restrained by our limited capacity to concurrently collect microbial and geochemical samples at appropriate spatial and temporal scales. Accordingly, we have developed a low-cost, continuous fluid sampling system (the Biological OsmoSampling System, or BOSS) to address this limitation. The BOSS does not use electricity, can be deployed in harsh/remote environments, and collects/preserves samples with daily resolution for >1 year. Here, we present data on the efficacy of DNA and protein preservation during a 1.5 year laboratory study as well as the results of two field deployments at deep-sea hydrothermal vents, wherein we examined changes in microbial diversity, protein expression, and geochemistry over time. Our data reveal marked changes in microbial composition co-occurring with changes in hydrothermal fluid composition as well as the temporal dynamics of an enigmatic sulfide-oxidizing symbiont in its free-living state. We also present the first data on in situ protein preservation and expression dynamics highlighting the BOSS's potential utility in meta-proteomic studies. These data illustrate the value of using BOSS to study relationships among microbial and geochemical phenomena and environmental conditions.

  20. Composition and dissolution of black smoker particulates from active vents on the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Feely, Richard A.; Lewison, Maureen; Massoth, Gary J.; Robert-Baldo, Gillian; Lavelle, J. William; Byrne, Robert H.; Von Damm, Karen L.; Curl, Herbert C., Jr.

    1987-10-01

    During two Atlantis II/Alvin cruises to the Juan de Fuca Ridge in 1984 active high temperature (140°-284°C) vents were sampled for black smoker particulates using the Grassle Pump. Individual mineral phases were identified using standard X ray diffraction and petrographic procedures. In addition, elemental compositions and particle morphologies were determined by X ray energy spectrometry and scanning electron microscope/X ray energy spectrometry techniques. The vent particulates from the southern Juan de Fuca Ridge vent sites were highly enriched in S, Si, Fe, Zn, and Cu and were primarily composed of sphalerite, wurtzite, pyrite, pyrrhotite, barite, chalcopyrite, cubanite, hydrous iron oxides, and elemental sulfur. Two additional unidentified phases which were prevalent in the samples included an Fe-Si phase and a Ca-Si phase. The grain sizes of the individual particle phases ranged from < 2 μm for the sphalerite and Fe oxide particles to > 100 μm for the Fe-Si particles. Grain size and current meter data were used in a deposition model of individual phase dispersal. For many of the larger sulfide and sulfate particles, the model predicts dispersal to occur over length scales of only several hundreds of meters. The high-temperature black smokers from the more northerly Endeavour Segment vents were highly enriched in Fe, S, Ca, Cu, and Zn and were primarily composed of anhydrite, chalcopyrite, sphalerite, barite, sulfur, pyrite, and other less abundant metal sulfide minerals. The grain sizes of the individual particles ranged from < 10 μm to slightly larger than 500 μm. The composition and size distributions of the mineral phases are highly suggestive of high-temperature mixing between vent fluids and seawater. A series of field and laboratory studies were conducted to determine the rates of dissolution of several sulfate and sulfide minerals. The dissolution rates ranged over more than 3 orders of magnitude, from 3.2 × 10-8 cm s-1 for anhydrite to 1.2

  1. 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

  2. Active Gas Venting Through Hydrate-Bearing Sediments on the Vestnesa Ridge, Offshore W-Svalbard

    NASA Astrophysics Data System (ADS)

    Buenz, S.; Vadakkepuliyambatta, S.; Polyanov, S.; Mienert, J.

    2010-12-01

    Gas hydrate systems offshore western Svalbard are far more extensive (~4000km^2) than previously assumed and include the whole Vestnesa Ridge, an elongated sediment drift north of the Molloy Transform and just east of the Molloy Ridge, one of the shortest segments of the slow spreading North-Atlantic Ridge system. The crest of the Vestnesa Ridge at water depth between 1200-1300 m is pierced with fluid-flow features. Seafloor pockmarks vary in size up to 1 km in diameter. Pockmarks are generally larger at the onset of the Vestnesa Ridge than at its western termination. A recent cruise with R/V Jan Mayen discovered methane flares in the water column above the pockmark field at the onset of the Vestnesa Ridge. Over a period of one week at least 4 pockmarks were continuously active and methane flares in the water column reached a height of approximately 800 m. The extent of the active gas venting is much stronger than discovered earlier and it is still unclear what has triggered the increase in gas expulsion from seafloor sediments. Any connection to hundreds of active gas vents further to the east at the shelf edge in water depth of 250-400 m remains speculative at this point but cannot be ruled out. High -resolution 3D seismic data acquired in 2007 and 2010 also show significant dissimilarities of the sub-seafloor expression of these fluid leakage systems. At the western end of the Vestnesa Ridge, sub-seafloor fluid flow features resemble well-described pipe structures. However, the seismic expression of the active fluid flow features is much broader, much more chaotic, dome-shaped and is not very similar to a typical chimney structure. The Vestnesa Ridge gas-hydrate and free- gas system occurs within few km of a mid-oceanic ridge and transform fault, which makes this gas hydrate system unique on Earth. The close proximity to the spreading centre and its hydrothermal circulation system affects the dynamics of the gas-hydrate and free-gas system. The high heat flow

  3. Low-molecular weight hydrocarbons in vent fluids from the Main Endeavour Field, northern Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Cruse, Anna M.; Seewald, Jeffrey S.

    2010-11-01

    Despite its location on sediment-free basalt, vent fluids from the Main Endeavour Field (MEF) contain chemical species that indicate fluids have interacted with sediments during circulation. We report on the distribution and isotopic abundances of organic compounds ( C1- C3 alkanes and alkenes, benzene and toluene) in fluids collected from the Main Endeavour Field (MEF) in July, 2000, to understand the processes that regulate their abundances and characterize fluid sources. Aqueous organic compounds are derived from the thermal alteration of sedimentary organic matter and subsequently undergo further oxidation reactions during fluid flow. Fluid:sediment mass ratios calculated using ΣNH 4 concentrations indicate that the sediments are distal to the MEF, resulting in a common reservoir of fluids for all of the vents. Following the generation from sediment alteration, aqueous organic compounds undergo secondary alteration reactions via a stepwise oxidation reaction mechanism. Alkane distributions and isotopic compositions indicate that organic compounds in MEF fluids have undergone a greater extent of alteration as compared to Middle Valley fluids, either due to differences in subsurface redox conditions or the residence time of fluids at subsurface conditions. The distributions of the aromatic compounds benzene and toluene are qualitatively consistent with the subsurface conditions indicated by equilibration of aqueous alkanes and alkanes. However, benzene and toluene do not achieve chemical equilibrium in the subsurface. Methane and CO 2 also do not equilibrate chemically or isotopically at reaction zone temperatures, a likely result of an insufficient reaction time after addition of CO 2 from magmatic sources during upflow. The organic geochemistry supports the assumption that the sediments with which MEF fluids interact has the same composition as sediments present in Middle Valley itself, and highlight differences in subsurface reaction zone conditions and fluid

  4. Gas venting system

    DOEpatents

    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.

  5. 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.

  6. Comparison of Five Hydrothermal Vent Fields at the Mid-Atlantic Ridge: Which Parameters Control the Differences in Fluid Geochemistry?

    NASA Astrophysics Data System (ADS)

    Schmidt, K.; Koschinsky, A.; Garbe-Schönberg, D.; Seifert, R.

    2006-12-01

    Five different high-temperature hydrothermal vent sites along the Mid-Atlantic Ridge are investigated within a special priority program funded by the German Research Foundation (SPP 1144). The sites are all located at 3000 m water depth (near the critical point of seawater). Comparing the geochemical signature of the hydrothermal fluids with respect to the individual setting, it is possible to distinguish between the major controlling parameters as they are phase separation in the supercritical region of seawater, temperature, and host rock composition. Three of the vent sites were found at 4°49'S on the MAR in a young post-eruptive basaltic setting. Two of them are characterized by strong phase separation and the highest temperatures measured so far along the MAR (up to 407°C), assuming a very shallow heat source. It is assumed, that this hydrothermal system newly formed after a big eruption event in this region. The other one, although located at a distance of maximum 2 km from the other two, emanates somewhat cooler fluids (up to 349°C), with no indications for boiling and phase separation Despite their spatial proximity and the identical basaltic host rock in which these fields are situated, the vent fields show a clearly different fluid chemistry with depletion of alkali and earth alkali elements and some trace metals in the very hot, phase separated fluids. The Logatchev field at 14°45'N is located in an ultramafic setting with outcropping peridotitic and gabbroic rocks. The chlorinity of the fluids does not clearly indicate phase separation. Compared to the non-phase separated basaltic system at 4°49'S MAR the fluids are characterized by significantly higher concentrations of hydrogen and methane due to the serpentinization reactions, lower silica and lithium concentrations and a depletion of boron. A identical chemical signature characterizes a recently discovered system at 8°18'S, the Nibelungen field. Host rock composition with both mafic and

  7. 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

  8. 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

  9. 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

  10. An analysis of flaring and venting activity in the Alberta upstream oil and gas industry.

    PubMed

    Johnson, Matthew R; Coderre, Adam R

    2011-02-01

    Alberta, Canada, is an important global producer of petroleum resources. In association with this production, large amounts of gas (1.14 billion m3 in 2008) are flared or vented. Although the amount of flaring and venting has been measurably reduced since 2002, data from 2005 reveal sharp increases in venting, which have important implications in terms of resource conservation and greenhouse gas emissions (which exceeded 8 million tonnes of carbon dioxide equivalent in 2008). With use of extensive monthly production data for 18,203 active batteries spanning the years 2002-2008 obtained in close cooperation with the Alberta Energy Resources Conservation Board, a detailed analysis has been completed to examine activity patterns of flaring and venting and reasons behind these trends in the Alberta upstream oil and gas industry. In any given year, approximately 6000 batteries reported flaring and/or venting, but the distribution of volumes flared and vented at individual sites was highly skewed, such that small numbers of sites handled large fractions of the total gas flaring and venting in the Province. Examination of month-to-month volume variability at individual sites, cast in terms of a nominal turndown ratio that would be required for a compressor to capture that gas and direct it into a pipeline, further revealed that volumes at a majority of sites were reasonably stable and there was no evidence that larger or more stable sites had been preferentially reduced, leaving potential barriers to future mitigation. Through linking of geospatial data with production data coupled with additional statistical analysis, the 31.2% increase in venting volumes since 2005 was revealed to be predominantly associated with increased production of heavier oils and bitumen in the Lloydminster region of the Province. Overall, the data suggest that quite significant reductions in flaring and venting could be realized by seeking mitigation solutions for only the largest batteries in

  11. 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.

  12. 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

  13. Heat Source for Active Venting at the Lost City Hydrothermal Field

    NASA Astrophysics Data System (ADS)

    Smith, J. E.; Germanovich, L. N.; Lowell, R. P.

    2014-12-01

    Located at the inside corner high of the Mid-Atlantic Ridge (MAR), 30°N and the Atlantis Transform Fault (ATF), the Atlantis Massif has been uplifted over the past ~2 my. The Southern Ridge of this massif hosts the Lost City Hydrothermal Field (LCHF), an off-axis hydrothermal vent field with carbonate chimney ages surpassing 120,000 yrs. The fluids discharging at LCHF carry geochemical signals that show a direct interaction with serpentinites. However, mineralogical evidence suggests that peridotite hydration began early in the formation of oceanic core complexes and previous modeling results indicate that serpentinization is unlikely to generate the heat necessary to maintain current levels of discharge at LCHF. This work develops a model for the LCHF venting based on the evidence of tectonic strain, detachment faulting, serpentinization, and convective fluid flow. We constrain fluid flow at the LCHF by vent geochemistry, vent temperature, seismically inferred faulting, and expected geothermal gradient ≈100°C/km. Present understanding of tectonic processes at the intersection of MAR and ATF suggests that unroofing of the footwall and crustal flexing of the massif induced normal faults, which run parallel to the MAR, throughout the Southern Ridge. In the absence of the evidence of magmatism, we test the feasibility of the geothermal gradient to cause fluid circulation in the high-permeability, sub-vertical fault zone. Fluid circulation in the fault zone is complemented by the bulk porous flow driven through the Southern Ridge by the lateral temperature gradient between the cold water on the steep face along the ATF side and the hot interior of the massif. In this scenario, the high pH hydrothermal fluids pass through the serpentinized zone before discharging as both high-temperature focused flow (40°-91°C) and low-temperature (≈15°C) diffuse flow at the LCHF.

  14. Observations of seafloor fluid venting along the transform margin between the North American and Pacific plates in the Gulf of California

    NASA Astrophysics Data System (ADS)

    Lundsten, E. M.; Anderson, K.; Paull, C. K.; Caress, D. W.; Thomas, H.; Gwiazda, R.; Herguera, J.; McGann, M. L.; Edwards, B. D.; Hinojosa, A.; Mejia Mercado, B.; Sanchez, A.; Conlin, D.; Thompson, D.

    2012-12-01

    Detailed surveys of the seafloor morphology at nine representative sections of the North American - Pacific Plate boundary on the floor of the Gulf of California were conducted by the Monterey Bay Aquarium Research Institute (MBARI) during a two ship expedition in March and April 2012. One of the objectives of this program was to better understand the distribution and impact of seafloor fluid venting along an active transform fault. At issue is whether the fault itself forms an active fluid flow conduit. An autonomous underwater vehicle (AUV) provided detailed bathymetry of the seafloor, and a remotely operated vehicle (ROV) allowed ground-truth observations and sampling of the surveyed area. The AUV surveys provide high-resolution multibeam bathymetry with a vertical precision of 0.15 m, horizontal resolution of 1.0 and 2-10 kHz CHIRP seismic reflection profiles. The nine surveys captured the morphology of a highly active fault zone in unprecedented detail. Among the features highlighted by these surveys are areas of distinctive seafloor textures. This distinctive morphology commonly occurs on the surface of elevated features that are up to 10 m higher than the surrounding seafloor and is characterized by considerable fine scale surface topography observed in both the AUV and ROV surveys. The surface topography is made up of broken and irregular blocks of methane-derived carbonates, separated by seafloor craters and open cracks that are 1 to 2 m deep and up to 10 m across. Individual patches of this distinctive morphology which are commonly ~100 m across occur within two of the nine survey areas. The presence of active chemosynthetic biological communities in open karst-like cracks show many of these sites are areas of active fluid seepage. In some places methane bubble venting was observed. Seepage was only observed where truncated strata exposed permeable layers adjacent to the fault rather than directly along the fault trace.

  15. 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.

  16. Cu- and Zn-isotope systematics of seafloor hydrothermal vent fluids from a back-arc setting (Manus Basin)

    NASA Astrophysics Data System (ADS)

    Dekov, V.; Rouxel, O.

    2012-04-01

    Unique seafloor hydrothermal processes combine in back-arc basins (BAB) to produce a wide range of vent fluid chemistry and mineral deposits, which are generally considered as critically important for the genesis of volcanogenic massive sulfide ore deposits. While it has become apparent that volatile-rich magmatic fluids play a crucial role in many BAB hydrothermal systems, the source of metals to the vent fluids, including ore-forming metals such as Cu, Zn and precious metals such as Ag and Au, has been a matter of debate [1]. Here, we applied coupled Cu and Zn stable isotopes to delineate if metal enrichment patterns in back-arc hydrothermal systems reflect (1) water-rock reactions with felsic host rock at low pH, (2) direct input of metal-rich magmatic volatiles, (3) remobilization from previously deposited sulfide or enriched source rock compositions. We measured Cu and Zn isotope composition of hydrothermal fluids from ten vents located in the eastern Manus BAB, Papua New Guinea (cruise MLGN06MV, R/V Melville, ROV Jason II). Purified samples were measured by MC-ICP-MS (Neptune) at IFREMER and data were corrected from instrumental mass bias using internal normalization [2], with an overall precision of 0.03‰ (2s). Cu isotopic ratios were reported relative to the NIST SRM 976 standard while Zn isotopic ratios were reported relative to IRMM 3702, having a δ66Zn value of 0.3‰ relative to Lyon-JMC standard. For the first time, Cu isotope composition of seafloor hydrothermal fluids were investigated and results show systematic enrichment in heavy Cu isotopes relative to basalt values (δ65CuNIST976= 0.3‰ +/- 0.2‰, n=30). In general, the variations of δ65Cu values in hydrothermal fluids are consistent with δ65Cu values in chalcopyrite lining hydrothermal chimneys. In some case, heavier δ65Cu values of Cu-sulfides related to Cu in the fluids are interpreted to result from Cu-isotope fractionation during Cu oxidation and precipitation within local chimney

  17. 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

  18. 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

  19. The study of active submarine volcanoes and hydrothermal vents in the Southernmost Part of Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Tsai, C.; Lee, C.

    2004-12-01

    The study area is located in the Southernmost Part of Okinawa Trough (SPOT), which is a back-arc basin formed by extension of Eurasian plate. Previous research indicated two extensional stages in SPOT area. Many normal-fault structures were come into existence during both extensional processes. The SPOT is presently in an activity tectonic episode. Therefore, the area becomes a frequent earthquake and abundant magmatism. The purpose of this study is to discuss which relationship between tectonics, submarine volcanoes and hydrothermal vents in SPOT area. The investigations are continued from 1998 to 2004, we have found at least twelve active hydrothermal vents in study area. Compare the locations hydrothermal vents with fault systems, we find both of them have highly correlated. We can distinguish them into two shapes, pyramidal shape and non-pyramidal shape. According to plumes height, we are able to divide these vents into two groups near east longitude 122.5° . East of this longitude, the hydrothermal plumes are more powerful and west of it are the weaker. This is closely related to the present extensional axis (N80° E) of the southern part of the Okinawa Trough. This can be explained the reason of why the more powerful vents coming out of the east group. The east group is associated with the present back-arc spreading system. West of 122.5° , the spreading system are in a primary stage. The andesitic volcanic island, the Turtle Island, is a result of N60° E extensional tectonism with a lot of faults. Besides the pyramidal shape, this can be proved indirectly. The vents located in the west side were occurred from previous extensional faults and are weaker than the eastern. Therefore, we suggest that if last the extension keeps going on, the hydrothermal vents located at the west side of the longitude 122.5° will be intensified.

  20. 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

  1. 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.

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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.

  7. Submarine hydrothermal activity along the mid-Kermadec Arc, New Zealand: Large-scale effects on venting

    NASA Astrophysics Data System (ADS)

    de Ronde, C. E. J.; Baker, E. T.; Massoth, G. J.; Lupton, J. E.; Wright, I. C.; Sparks, R. J.; Bannister, S. C.; Reyners, M. E.; Walker, S. L.; Greene, R. R.; Ishibashi, J.; Faure, K.; Resing, J. A.; Lebon, G. T.

    2007-07-01

    The 2,500-km Kermadec-Tonga arc is the longest submarine arc on the planet. Here, we report on the second of a series of cruises designed to investigate large-scale controls on active hydrothermal venting on this arc. The 2002 NZAPLUME II cruise surveyed 12 submarine volcanic centers along ~580 km of the middle Kermadec arc (MKA), extending a 1999 cruise that surveyed 260 km of the southern Kermadec arc (SKA). Average spacing between volcanic centers increases northward from 30 km on backarc crust along the SKA, to 45 km on backarc crust along the southern MKA, to 58 km where the MKA joins the Kermadec Ridge. Volcanic cones dominate in the backarc, and calderas dominate the Kermadec Ridge. The incidence of venting is higher along the MKA (83%, 10 of 12 volcanic centers) than the SKA (67%, 8 of 12), but the relative intensity of venting, as given by plume thickness, areal extent, and concentration of dissolved gases and ionic species, is generally weaker in the MKA. This pattern may reflect subduction of the ~17-km-thick oceanic Hikurangi Plateau beneath the SKA. Subduction of this basaltic mass should greatly increase fluid loss from the downgoing slab, initiating extensive melting in the upper mantle wedge and invigorating the hydrothermal systems of the SKA. Conversely, volcanic centers in the southern MKA are starved of magma replenishment and so their hydrothermal systems are waning. Farther north, where the MKA centers merge with the Kermadec Ridge, fewer but larger magma bodies accumulate in the thicker (older) crust, ensuring more widely separated, caldera-dominated volcanic centers.

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

    PubMed

    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.

  9. 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

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

    PubMed

    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

  11. 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.

  12. 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

  13. 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

  14. From Black Hole to Hydrate Hole: Gas hydrates, authigenic carbonates and vent biota as indicators of fluid migration at pockmark sites of the Northern Congo Fan

    NASA Astrophysics Data System (ADS)

    Kasten, S.; Schneider, R.; Spiess, V.; Cruise Participants Of M56b

    2003-04-01

    A recent high-resolution seismic, echosounder and video survey combined with detailed geological and geochemical sampling of pockmark sites on the Northern Congo Fan was carried out with RV Meteor in November/December 2002 in the frame of the project "CONGO" (BMBF/BEO "Geotechnologien"). These investigations revealed the extensive occurrence of surface and sub-surface gas hydrates as well as characteristic features of fluid venting such as clams (Calyptogena), tube worms (Pogonophera) and huge amounts of authigenic carbonates. In a first approach the patchyness in the occurrence of these features was mapped in relation to pockmark structure and seismic reflectors. Detailed sampling of three pockmarks by gravity corer showed that gas hydrates are present at and close to the sediment surface and often occur as several distinct layers and/or veins intercalated with hemipelagic muds. The depth of the upper boundary of these hydrate-bearing sediments increases from the center towards the edge of the pockmark structures. Pore water concentration profiles of sulfate and methane document the process of anaerobic methane oxidation above the hydrate-bearing layers. For those cores which contained several gas hydrate layers preliminary pore water profiles suggest the occurrence of more than one zone of anaerobic methane oxidation. Authigenic carbonates are found in high abundance, irregularly distributed within the pockmarks close to the sediment surface. These carbonates occur in a wide variety with respect to size, shape, structure and mineralogy. Their formation is associated with high amounts of bicarbonate released by the process of anaerobic methane oxidation. In the gravity cores authigenic carbonates are always present above hydrate-bearing sections. However, the quantities and characteristics of these authigenic minerals in relation to venting and microbial activity as well as to gas hydrate dissociation are not clear yet. Unraveling this relationship will be a major

  15. New Equations for the Physical Properties of Geothermal Fluid near Vent Environments

    NASA Astrophysics Data System (ADS)

    Sun, H.

    2004-05-01

    A set of workable fitted polynomial equations for calculating the physical properties: density, specific heat, adiabetic lapse rate and potential temperature of geothermal fluid (0~370 degree centigrade) in response to the temperature, pressure and salinity change, are attempted to be established in this study. The freshwater component of the equations are extracted from the recently released tabulated data of freshwater properties by Wagner and Prub (2002) which is recommended by the International Association for the Properties of Water and Steam (IAPWS). The salt water component of the equation, based on the near-linear relationship of density/specific heat with the salinity, is extracted from the classical lower temperature Equation of State of Seawater 1980's data sets. The freshwater and salt water components are combined to make the set of workable equation. The polynomial equations are calibrated with the existing experimental data and are also applied to the available geothermal fluid data released by the Ocean Drilling Project (ODP) office for back calculating the density and porosity. Though there are no reliable experimental data on the effect of salinity on density and specific heat in high temperature (>40 degree centigrade), the theoretical extension of the salt component are better in estimating the physical properties of the geothermal fluid than using only the freshwater equations or using only the regular seawater equation which limits its temperature to 0 and 40 degree centigrade.

  16. Sulfur isotope study of chimney minerals and vent fluids from 21°N, East Pacific Rise: Hydrothermal sulfur sources and disequilibrium sulfate reduction

    NASA Astrophysics Data System (ADS)

    Woodruff, Laurel G.; Shanks, Wayne C., III

    1988-05-01

    Sulfur isotopic analyses of hydrothermal chimneys and coexisting fluids collected from hot vent areas at 21°N, East Pacific Rise, indicate δ34S values for sulfide minerals of 0.9-6.2‰ and for aqueous H2S of 1.3-5.5‰. The chemical processes resulting in mineral zoning of chimney structures are a controlling influence on 34S variation within individual chimneys. In general, coarsely crystalline chalcopyrite, which lines chimney interiors, is depleted in δ34S relative to exterior ZnS (either sphalerite or wurtzite). Chalcopyrite which formed by replacement of other sulfides has higher sulfur isotope values than chalcopyrite which precipitated directly from hydrothermal fluid. Bornite and other Cu-rich sulfides, which occur as thin layers replacing the outer margins of massive chalcopyrite zones, have the highest δ34S values of any 21°N samples, ranging from 5.2‰ to 6.2‰. The significant 34S enrichment in bornite requires reduction of isotopically heavy seawater-derived sulfate in the chimney walls. Vent fluid δ34SH2S values are similar to δ34S values of inner wall chimney sulfides for seven of 11 samples. In other samples, aqueous H2S is enriched isotopically in δ34S compared with coexisting sulfides, suggesting admixture of H2S derived from reduced seawater sulfate. The δ34S value of end-member hydrothermal fluid at 21°N is about 1.0-1.5‰, which is somewhat higher than basaltic sulfide, the main source of sulfur in the hydrothermal system. This 34S enrichment apparently is due to sulfate reduction in the deep hydrothermal system during conversion of basaltic pyrrhotite to pyrite. The South West (SW) vent field has significantly higher average δ34S values (3.1‰) compared with the other 21°N vent fields. The SW field is situated on the edge of a lava collapse structure, promoting development of an extensive feeder zone which is the site of near-surface sulfate reduction during redissolution of previously deposited anhydrite. The δ34S values for

  17. 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

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

    NASA Astrophysics Data System (ADS)

    Lutz, Richard A.; Kennish, Michael J.

    1993-08-01

    Studies of the many active and inactive hydrothermal vents found during the past 15 years have radically altered views of biological and geological processes in the deep sea. The biological communities occupying the vast and relatively stable soft bottom habitats of the deep sea are characterized by low population densities, high species diversity, and low biomass. In contrast, those inhabiting the generally unstable conditions of hydrothermal vent environments exhibit high densities and biomass, low species diversity, rapid growth rates, and high metabolic rates. Biological processes, such as rates of metabolism and growth, in vent organisms are comparable to those observed in organisms from shallow-water ecosystems. An abundant energy source is provided by chemosynthetic bacteria that constitute the primary producers sustaining the lush communities at the hydrothermal sites. Fluxes in vent flow and fluid chemistry cause changes in growth rates, reproduction, mortality, and/or colonization of vent fauna, leading to temporal and spatial variation of the vent communities. Vent populations that cannot adapt to modified flow rates are adversely affected, as is evidenced by high mortality or lower rates of colonization, growth, or reproduction. Substantial changes in biota have been witnessed at several vents, and successional cycles have been proposed for the Galapagos vent fields. Dramatic temporal and spatial variations in vent community structure may also relate to variations in larval dispersal and chance recruitment, as well as biotic interactions.

  19. 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.

  20. 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

  1. 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.

  2. Chemosynthetic microbial activity at Mid-Atlantic Ridge hydrothermal vent sites

    NASA Astrophysics Data System (ADS)

    Wirsen, Carl O.; Jannasch, Holger W.; Molyneaux, Stephen J.

    1993-06-01

    Chemosynthetic production of microbial biomass, determined by 14CO2 fixation and enzymatic (RuBisCo) activity, at the Mid-Atlantic Ridge (MAR) 23° and 26°N vent sites was found in various niches: warm water emissions, loosely rock-attached flocculent material, dense morphologically diverse bacterial mats covering the surfaces of polymetal sulfide deposits, and filamentous microbes on the carapaces of shrimp (Rimicaris exoculata). The bacterial mats on polymetal sulfide surfaces contained unicellular and filamentous bacteria which appeared to use as their chemolithotrophic electron or energy source either dissolved reduced minerals from vent emissions, mainly sulfur compounds, or solid metal sulfide deposits, mainly pyrite. Moderately thermophilic Chemosynthetic activity was observed in carbon dioxide fixation experiments and in enrichments, but no thermophilic aerobic sulfur oxidizers could be isolated. Both obligate and facultative chemoautotrophs growing at mesophilic temperatures were isolated from all chemosynthetically active surface scrapings. The obligate autotrophs could oxidize sterilized MAR natural sulfide deposits as well as technical pyrite at near neutral pH, in addition to dissolved reduced sulfur compounds. While the grazing by shrimp on the surface mats of MAR metal sulfide deposits was observed and deemed important, the animals' primary occurrence in dense swarms near vent emissions suggests that they were feeding at these sites, where conditions for Chemosynthetic growth of their filamentous microbial epiflora were optimal. The data show that the transformation of geothermal energy at the massive polymetal sulfide deposits of the MAR is based on the lithoautotrophic oxidation of soluble sulfides and pyrites into microbial biomass.

  3. 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

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

    PubMed Central

    Fortunato, Caroline S; Huber, Julie A

    2016-01-01

    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 13C 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

  5. Characterization of Six Vent Fields Within the Lau Basin

    NASA Astrophysics Data System (ADS)

    Tivey, M. K.; Craddock, P.; Seewald, J.; Ferrini, V.; Kim, S.; Mottl, M.; Sterling, N. A.; Reysenbach, A.; Wheat, C. G.

    2005-12-01

    Six active vent fields on the Valu Fa Ridge and Eastern Lau Spreading Center were successfully characterized on R/V Melville cruise TUIM05MV. The Kilo Moana (20deg3.2'S), Tow Cam (20deg19'S), and ABE (20deg45.6-46'S) vent fields were first noted during two R/V Kilo Moana cruises (in April (F. Martinez, Chief Scientist) and Sept (C. Langmuir, Chief Scientist) 2004). A fourth vent field, Mariner at 22deg10.8'S, was located Sept 2004 during the Shinkai 6500 program (K. Takai, Chief Scientist) using data from previous cruises. The fifth vent field examined was the Vai Lili vent field at 22deg12.95'S (Fouquet et al., 1991, Nature 349). On the TUIM05MV cruise, a sixth large active vent field was found at 21deg59.4'S using Jason2 and data from multiple CTD tow-yos, following up on plume observations provided by the Martinez et al. cruise. Tasks conducted to characterize each vent field included 1) detailed SM2000 bathymetric surveys; 2) down-looking and/or forward-looking camera surveys to create photomosaics of megafauna distributions; 3) recovery of biological, rock (basalt and sulfide), and fluid samples, and microbiological sampling of sulfide and diffuse fluid samples; 4) MOCNESS tows to recover larval plankton from plumes; 5) CTD casts to collect plume particles. At the Kilo Moana, Tow Cam, ABE and Tui Malila vent fields, hydrothermal activity occurs in proximity to major faults. At Kilo Moana, active venting occurs in three areas from ~5m tall, branched structures as focused, high temperature flow (to 333C) through chalcopyrite (Cp)- and/or wurtzite (Zn)- lined conduits and as diffuse flow through beehive-type structures. At Tow Cam high temperature (to 330C) active venting occurs in two areas at the base of a western fault from Cp- and/or Zn-lined conduits; diffuse flow exits basalt east of the black smoker areas. Within the ABE vent field there are three large areas of active venting spaced 150 to 300 m apart along NNE trending faults and benches; fluid exits

  6. Vent Fluid Chemistry From Six Hydrothermal Fields Along the Eastern Lau Spreading Center From 20°03'S to 22°13'S.

    NASA Astrophysics Data System (ADS)

    Sharkey, J.; Wheat, C. G.; Mottl, M. J.; Seewald, J.

    2005-12-01

    As part of a series of R2K and NSF funded explorations of the Eastern Lau Spreading Center, we participated in a cruise between April and May of 2005 aboard the R/V Melville. Eighty-one fluid samples were collected from six hydrothermal fields that span from 20°03'S to 22°13'S (from north to south: Kilo Moana, TowCam, Abe, Tui Malia, Mariner, and Vai Lili) using the ROV Jason 2. Fluids samples were collected using both isobaric gas-tight and major samplers from focused and diffuse vents to determine vent fluid composition and establish the hydrogeologic and geochemical processes occurring at depth. We report here on dissolved ion concentrations from vent fluids. The maximum vent temperature and magnesium concentration from individual orifices ranged from 11 to 363 ° C and from 51.7 to 0.65mmol/kg, respectively. The Mariner site had the lowest pH of 2.5 and the greatest H2S concentration of approximately 9mmol/kg. All samples had alkalinities less than seawater. Chlorinities were both depleted and enriched relative to seawater (around 538 mmol/kg), ranging from 530 to 650mmol/kg. Fe endmember concentration is about 12mmol/kg at Mariner and 3mmol/kg at Kilo Moana, but less than 0.3mmol/kg for the other sites. Fe/Mn molar ratios range from 4.7 at Kilo Moana to 0.1 at Vai Lili. Systematic along strike variations were observed in the endmember abundance of some aqueous species. For example, values for Si and Li are greater to the north whereas concentrations of K are greater to the south. Compilations of endmember compositions for individual orifices and fields are being compiled for all major, minor and certain trace ions in seawater. Trends will be incorporated with geological and biological data to elucidate hydrothermal processes along this geologically diverse transect. We are particularly interested in assessing the response of fluid chemistry to variations in the composition and structure of the crust resulting from the increase influence of subduction related

  7. 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.

  8. 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

  9. 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.

  10. Immersed Boundary Simulations of Active Fluid Droplets

    PubMed Central

    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

  11. 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

  12. Decline of a Hydrothermal Vent Field - Escanaba Trough 12 Years Later

    NASA Astrophysics Data System (ADS)

    Zierenberg, R. A.; Clague, D. A.; Davis, A. S.; Lilley, M. D.; McClain, J. S.; Olson, E. S.; Ross, S. L.; Von Damm, K. L.

    2001-12-01

    Hydrothermal venting was discovered in Escanaba Trough, the southern sediment-covered portion of the Gorda Ridge, in 1988. Large pyrrhotite-rich massive sulfide mounds are abundant at each of the volcanic/intrusive centers that have been investigated in Escanaba Trough, but the only area of known hydrothermal venting is the NESCA site along the ridge axis at 41\\deg N. Hydrothermal fluids venting at 217\\deg C and 108\\deg C were sampled in 1988 on two sulfide mounds separated by about 275 m. The end-member fluid compositions were indistinguishable within analytical errors. Several sulfide mounds were observed in 1988 which had diffusely venting low temperature (< 20\\deg C) fluids that supported extensive vent communities dominated by fields of Ridgia. Nine holes were drilled in the NESCA area in 1996 on ODP Leg 169, including Hole 1036I that penetrated to basaltic basement at 405 m below sea floor (mbsf). Surveys of the area using the drill string camera located only one area of active venting at the same mound where 217\\deg C vent fluids were sampled from two active vents in 1988. Drill hole 1036A was spudded between the two active vents on this sulfide mound (approximately 4 and 8 m away) and penetrated to 115 mbsf. The NESCA site was revisited in 2000 using MBARI's R/V Western Flyer and ROV Tiburon. The hydrothermal vents appeared essentially identical to observations made from the drill string camera in 1996 despite the presence of a drill hole within meters of the two vents. The maximum vent temperature measured in 2000 was 212\\deg C. Fluid samples have major element and isotopic compositions very similar to those collected in 1988. The vent fluids have higher methane ( ~19 mmol/kg) than those from the geologically similar Middle Valley vent field, but lower values than those at Guaymas Basin. Drill hole 1036A was weakly venting, but the diffuse hydrothermal fluids could not be sampled with the equipment available. The walls of the drill hole were

  13. The thermal and chemical evolution of hydrothermal vent fluids in shale hosted massive sulphide (SHMS) systems from the MacMillan Pass district (Yukon, Canada)

    NASA Astrophysics Data System (ADS)

    Magnall, J. M.; Gleeson, S. A.; Blamey, N. J. F.; Paradis, S.; Luo, Y.

    2016-11-01

    At Macmillan Pass (YT, Canada), the hydrothermal vent complexes beneath two shale-hosted massive sulphide (SHMS) deposits (Tom, Jason) are well preserved within Late Devonian strata. These deposits provide a unique opportunity to constrain key geochemical parameters (temperature, salinity, pH, fO2, ΣS) that are critical for metal transport and deposition in SHMS systems, and to evaluate the interaction between hydrothermal fluids and the mudstone host rock. This has been achieved using a combination of detailed petrography, isotopic techniques (δ34S, δ13C and δ18O values), carbonate rare earth element analysis (LA-ICP-MS), fluid inclusion analysis (microthermometry, gas analysis via incremental crush fast scan mass spectrometry), and thermodynamic modelling. Two main paragenetic stages are preserved in both vent complexes: Stage 1 comprises pervasive ankerite alteration of the organic-rich mudstone host rock and crosscutting stockwork ankerite veining (±pyrobitumen, pyrite and quartz) and; Stage 2 consists of main stage massive sulphide (galena-pyrrhotite-pyrite ± chalcopyrite-sphalerite) and siderite (±quartz and barytocalcite) mineralisation. Co-variation of δ18O and δ13C values in ankerite can be described by temperature dependent fractionation and fluid rock interaction. Together with fluid inclusion microthermometry, this provides evidence of a steep thermal gradient (from 300 to ∼100 °C) over approximately 15 m stratigraphic depth, temporally and spatially constrained within the paragenesis of both vent complexes and developed under shallow lithostatic (<1 km; 250 bars) to hydrostatic (<400 m; 40 bars) conditions. There is evidence of mixing between diagenetic and hydrothermal fluids recorded in chondrite-normalised rare earth element (REE) profiles of ankerite and siderite. Middle REE enrichments and superchondritic Y/Ho ratios (>28), characteristic of diagenetic fluids, are coupled with positive europium anomalies and variable light REE

  14. 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.

  15. Activities report in fluid mechanics

    NASA Astrophysics Data System (ADS)

    1986-10-01

    The research conducted at the Lille Institute of Fluid Mechanics (IMFL) concerns four areas: flight mechanics, structural mechanics, aerodynamics and applied fluid mechanics. Within these four areas, these topics are discussed: characterization of the unsteady pressures on an airfoil in turbulence; adaptation of the Kalman-Rauch filtering-smoothing method to instrumented free spin tests; vulnerability of aircraft fuel tanks; water surface impact; influence of an oscillating spoiler on the surrounding aerodynamic field; gunfiring similarity theory and rules; flow around a cylinder at low Reynolds number by holographic velocimetry and laser Doppler velocimetry; compressible turbulent flow computation; and the wake of wind turbine towers are discussed.

  16. 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).

  17. Active cancellation of occlusion: an electronic vent for hearing aids and hearing protectors.

    PubMed

    Mejia, Jorge; Dillon, Harvey; Fisher, Michael

    2008-07-01

    The occlusion effect is commonly described as an unnatural and mostly annoying quality of the voice of a person wearing hearing aids or hearing protectors. As a result, it is often reported by hearing aid users as a deterrent to wearing hearing aids. This paper presents an investigation into active occlusion cancellation. Measured transducer responses combined with models of an active feedback scheme are first examined in order to predict the effectiveness of occlusion reduction. The simulations predict 18 dB of occlusion reduction in completely blocked ear canals. Simulations incorporating a 1 mm vent (providing passive occlusion reduction) predict a combined active and passive occlusion reduction of 20 dB. A prototype occlusion canceling system was constructed. Averaged across 12 listeners with normal hearing, it provided 15 dB of occlusion reduction. Ten of the subjects reported a more natural own voice quality and an appreciable increase in comfort with the cancellation active, and 11 out of the 12 preferred the active system over the passive system. PMID:18646971

  18. Active cancellation of occlusion: an electronic vent for hearing aids and hearing protectors.

    PubMed

    Mejia, Jorge; Dillon, Harvey; Fisher, Michael

    2008-07-01

    The occlusion effect is commonly described as an unnatural and mostly annoying quality of the voice of a person wearing hearing aids or hearing protectors. As a result, it is often reported by hearing aid users as a deterrent to wearing hearing aids. This paper presents an investigation into active occlusion cancellation. Measured transducer responses combined with models of an active feedback scheme are first examined in order to predict the effectiveness of occlusion reduction. The simulations predict 18 dB of occlusion reduction in completely blocked ear canals. Simulations incorporating a 1 mm vent (providing passive occlusion reduction) predict a combined active and passive occlusion reduction of 20 dB. A prototype occlusion canceling system was constructed. Averaged across 12 listeners with normal hearing, it provided 15 dB of occlusion reduction. Ten of the subjects reported a more natural own voice quality and an appreciable increase in comfort with the cancellation active, and 11 out of the 12 preferred the active system over the passive system.

  19. 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.

  20. 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.

  1. Diffuse versus discrete venting at the Tour Eiffel vent site, Lucky Strike hydrothermal field

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, E. L.; Escartin, J.; Gracias, N.; Olive, J. L.; Barreyre, T.; Davaille, A. B.; Cannat, M.

    2010-12-01

    Two styles of fluid flow at the seafloor are widely recognized: (1) localized outflows of high temperature (>300°C) fluids, often black or grey color in color (“black smokers”) and (2) diffuse, lower temperature (<100°C), fluids typically transparent and which escape through fractures, porous rock, and sediment. The partitioning of heat flux between these two types of hydrothermal venting is debated and estimates of the proportion of heat carried by diffuse flow at ridge axes range from 20% to 90% of the total axial heat flux. Here, we attempt to improve estimates of this partitioning by carefully characterizing the heat fluxes carried by diffuse and discrete flows at a single vent site, Tour Eiffel in the Lucky Strike hydrothermal field along the Mid-Atlantic Ridge. Fluid temperature and video data were acquired during the recent Bathyluck’09 cruise to the Lucky Strike hydrothermal field (September, 2009) by Victor aboard “Pourquoi Pas?” (IFREMER, France). Temperature measurements were made of fluid exiting discrete vents, of diffuse effluents immediately above the seafloor, and of vertical temperature gradients within discrete hydrothermal plumes. Video data allow us to calculate the fluid velocity field associated with these outflows: for diffuse fluids, Diffuse Flow Velocimetry tracks the displacement of refractive index anomalies through time; for individual hydrothermal plumes, Particle Image Velocimetry tracks eddies by cross-correlation of pixels intensities between subsequent images. Diffuse fluids exhibit temperatures of 8-60°C and fluid velocities of ~1-10 cm s-1. Discrete outflows at 204-300°C have velocities of ~1-2 m s-1. Combined fluid flow velocities, temperature measurements, and full image mosaics of the actively venting areas are used to estimate heat flux of both individual discrete vents and diffuse outflow. The total integrated heat flux and the partitioning between diffuse and discrete venting at Tour Eiffel, and its

  2. 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

  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. 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

  5. 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

  6. Phylogenetic diversity of sulfate-reducing prokaryotes in active deep-sea hydrothermal vent chimney structures.

    PubMed

    Nakagawa, Tatsunori; Nakagawa, Satoshi; Inagaki, Fumio; Takai, Ken; Horikoshi, Koki

    2004-03-19

    The phylogenetic diversity of sulfate-reducing prokaryotes occurring in active deep-sea hydrothermal vent chimney structures was characterized based on the deduced amino acid sequence analysis of the polymerase chain reaction-amplified dissimilatory sulfite reductase (DSR) gene. The DSR genes were successfully amplified from microbial assemblages of the chimney structures, derived from three geographically and geologically distinct deep-sea hydrothermal systems in the Central Indian Ridge (CIR), in the Izu-Bonin Arc (IBA), and the Okinawa Trough (OT), respectively. Phylogenetic analysis revealed seven major phylogenetic groups. More than half of the clones from the CIR chimney structure were related to DSR amino acid sequences of the hyperthermophilic archaeal members of the genus Archaeoglobus, and those of environmental DSR clones within the class Thermodesulfobacteria. From the OT chimney structure, a different group was obtained, which comprised a novel, deep lineage associated with the DSRs of the thermophilic sulfate-reducing bacterium Thermodesulfovibrio. Most of the DSR clones from the IBA chimney structure were phylogenetically associated with the delta-proteobacterial sulfate-reducing bacteria represented by the genus Desulfobulbus. Sequence analysis of DSR clones demonstrated a diverse sulfate-reducing prokaryotic community in the active deep-sea hydrothermal chimney structures.

  7. 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

  8. Hydrothermal Vents in Yellowstone Lake: Chemical Fluxes, Siliceous Deposits, and Collapse Structures

    NASA Astrophysics Data System (ADS)

    Shanks, W. P.; Morgan, L. A.; Balistrieri, L.; Alt, J.; Meeker, G.

    2002-12-01

    The geochemistry of Yellowstone Lake is strongly influenced by sublacustrine hydrothermal vent activity. The hydrothermal source fluid is identified using Cl and dD data on water column and sublacustrine hydrothermal vent fluid samples. Silica-rich hydrothermal deposits occur on the lake bottom near active and presently inactive hydrothermal vents. Pipe- and flange-like deposits contain cemented and recrystallized diatoms and represent pathways for hydrothermal fluid migration. Another major type of hydrothermal deposit comprises hard, porous siliceous spires up to 7 m tall that occur in 15 m of water in Bridge Bay. Bridge Bay spires are hydrothermal silica deposits formed in place by growth of chimney-like features from lake-bottom hydrothermal vents. The Cl concentrations indicate that Yellowstone Lake water is about 1 percent hydrothermal source fluid and 99 percent inflowing stream water and that the flux is about 10 percent of the total hydrothermal water flux in Yellowstone National Park. With recent swath-sonar mapping studies that show numerous new hydrothermal features, Yellowstone Lake should now be considered one of the most significant hydrothermal basins in the Park. Many lake-bottom hydrothermal vents occur in small depressions that are clearly imaged on multibeam sonar, some of which are interpreted as collapse structures based on seismic reflection data. Sediments collected from such vents show chemical evidence of leaching of 60-70 wt. percent SiO2, which may result in volume reductions up to 80 percent and provides a mechanism for vent structure formation.

  9. 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.

  10. Shallow vent architecture of Puyehue Cordón-Caulle, as revealed by direct observation of explosive activity

    NASA Astrophysics Data System (ADS)

    Schipper, C. I.; Tuffen, H.; Castro, J. M.

    2012-04-01

    On June 4, 2011, an explosive eruption of rhyodacitic magma began at the Puyehue Cordón-Caulle volcanic complex (PCCVC), southern Chile. Initial Plinian phases of the eruption produced tephra plumes reaching > 14 km high, the ash from which quickly circumnavigated the globe to cause widespread disruption to air traffic in the Southern Hemisphere. Within two weeks, the continuing explosive eruption was joined by synchronous effusion of lava. We present observations of complex vent activity made 7 months after the eruption onset, on January 4th and 10th, 2012, when explosive activity from PCCVC continued at a lower level of intensity. Fortuitous climatic conditions permitted direct, ground-based observation and video recording of transient vent dynamics within the asymmetrical tephra cone around the main eruptive vent complex and site of lava effusion, as well as real-time collection of juvenile ash as it rained out directly from the active plume. On Jan. 4, explosive activity was semi-continuous ash jetting punctuated by Vulcanian-like blasts. In the ~50m-diameter sub-circular base of the ~400 m-wide, asymmetrical tephra cone, near-continuous ash jetting was observed from two primary point sources. The northerly source was clearly visible, with time-averaged diameter of ~10 m, and the apparently larger southerly source was mostly obscured from view by the ash plume. Activity was at all times somewhat erratic, but followed a rough cyclicity on 30-45 s timescales, consisting of: (1) restriction of the point source into a focused ash jet up to ~50 m high, producing coarse ash dominated by tube pumice (with minor free pyroxene crystals); followed by (2) Vulcanian-like failure of the region around the point source, producing incandescent ballistic bombs thrown up to 100-200 m from the vent. Jetting from the two main point sources combined in the crater to produce a low gas-thrust region and sustained buoyant plume. Directed ash plumes that climbed and breached the inner

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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)).

  20. 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

  1. Vent for an electrochemical cell

    SciTech Connect

    Wilson, J.A.; Staniewicz, R.J.; Webber, B.; Allvey, G.W.

    1987-05-12

    A pressure relief vent is described for use with a container subjected to internal pressure by a fluid, the vent comprising: pressure relief means comprising a diaphragm essentially flat in shape fastened to the exterior of the container at the perimeter of the diaphragm and at a location within the perimeter of the diaphragm; an opening in the container disposed so that fluid from the container can pass between the diaphragm and the container and exert pressure on the diaphragm; and the pressure relief means being ruptured at a predetermined pressure exerted by the fluid on the diaphragm.

  2. Permeability-Porosity Relationships in Deep Sea Hydrothermal Vent Deposits

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Gittings, H.; Tivey, M. K.

    2003-12-01

    To map out the thermal and chemical regimes within vent deposits where micro-and macro-organisms reside requires accurate modeling of mixing and reaction between hydrothermal fluid and seawater within the vent structures. However, a critical piece of information, quantitative knowledge of the permeability of vent deposits, and how it relates to porosity and pore geometry, is still missing. To address this, systematic laboratory measurements of permeability and porosity were conducted on 3 large vent structures from the Mothra Hydrothermal vent field on the Endeavor Segment of the Juan de Fuca Ridge. Twenty-five cylindrical cores with diameters of 2.54 cm and various lengths were taken from Phang (a tall sulfide-dominated spire that was not actively venting when sampled), Roane (a lower temperature spire with dense macrofaunal communities growing on its sides that was venting diffuse fluid of < 300° C) and Finn (an active black smoker with a well-defined inner conduit that was venting 302° C fluids prior to recovery (Delaney et al., 2000; Kelley et al, 2000)). Measurements were made to obtain porosity and permeability of these drill cores using a helium porosimeter (UltraPoreTM300) and a nitrogen permeameter (UltrapermTM400) from Core Laboratories Instruments. The porosimeter uses Boyle's law to determine pore volume from the expansion of a know mass of helium into a calibrated sample holder, whereas the permeameter uses Darcy's law to determine permeability by measuring the steady-state flow rate through the sample under a given pressure gradient. A moderate confining pressure of 1.38 MPa was applied during the measurements to prevent leakage between the sample surface and the sample holder. The permeability and porosity relationship is best described by two different power law relationships with exponents of ˜9 (group I) and ˜3 (group II), respectively. Microstructural observations suggest that the difference in the two permeability-porosity relationships

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Diversity and distribution of subseafloor Thermococcales populations in diffuse hydrothermal vents at an active deep-sea volcano in the northeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Huber, Julie A.; Butterfield, David A.; Baross, John A.

    2006-12-01

    The presence, diversity, and distribution of a key group of subseafloor archaea, the Thermococcales, was examined in multiple diffuse flow hydrothermal vents at Axial Seamount, an active deep-sea volcano located in the northeast Pacific Ocean. A polymerase chain reaction (PCR) approach was used to determine if this group of subseafloor indicator organisms showed any phylogenetic distribution that may indicate distinct subseafloor communities at vents with different physical and chemical characteristics. Targeted primers for the Thermococcales 16S rRNA (small subunit ribosomal RNA) gene and intergenic transcribed spacer (ITS) region were designed and applied to organisms filtered directly from a variety of diffuse flow vents. Thermococcales were amplified from 9 of 11 samples examined, and it was determined that the ITS region is a better phylogenetic marker than the 16S rRNA in defining consistent groups of closely related sequences. Results show a relationship between environmental clone distribution and source vent chemistry. The most highly diluted vents with elevated iron and alkalinity contained a distinct group of Thermococcales as defined by the ITS region, suggesting separate subseafloor Thermococcales populations at diffuse vents within the Axial caldera.

  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. 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.

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

    PubMed

    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

    2011-08-01

    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.

  12. 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.

  13. 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.

  14. Risk-Free Volcano Observations Using an Unmanned Autonomous Helicopter: seismic observations near the active vent of Sakurajima volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ohminato, T.; Kaneko, T.; Koyama, T.; Yasuda, A.; Watanabe, A.; Takeo, M.; Honda, Y.; Kajiwara, K.; Kanda, W.; Iguchi, M.; Yanagisawa, T.

    2010-12-01

    Observations in the vicinity of summit area of active volcanoes are important not only for understanding physical processes in the volcanic conduit but also for eruption prediction and volcanic hazards mitigation. It is, however, challenging to install observation sensors near active vents because of the danger of sudden eruptions. We need safe and efficient ways of installing sensors near the summit of active volcanoes. We have been developing an volcano observation system based on an unmanned autonomous vehicle (UAV) for risk-free volcano observations. Our UAV is an unmanned autonomous helicopter manufactured by Yamaha-Motor Co., Ltd. The UAV is 3.6m long and weighs 84kg with maximum payload of 10kg. The UAV can aviate autonomously along a previously programmed path within a meter accuracy using real-time kinematics differential GPS equipment. The maximum flight time and distance from the operator are 90 minutes and 5km, respectively. We have developed various types of volcano observation techniques adequate for the UAV, such as aeromagnetic survey, taking infrared and visible images from onboard high-resolution cameras, volcanic ash sampling in the vicinity of active vents. Recently, we have developed an earthquake observation module (EOM), which is exclusively designed for the UAV installation in the vicinity of active volcanic vent. In order to meet the various requirements for UAV installation, the EOM is very compact, light-weight (5-6kg), and is solar-powered. It is equipped with GPS for timing, a communication device using cellular-phone network, and triaxial accelerometers. Our first application of the EOM installation using the UAV is one of the most active volcanoes in Japan, Sakurajima volcano. Since 2006, explosive eruptions have been continuing at the reopened Showa crater at the eastern flank near the summit of Sakurajima. Entering the area within 2 km from the active craters is prohibited, and thus there were no observation station in the vicinity

  15. 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.

  16. Potential fluid mechanic pathways of platelet activation

    PubMed Central

    Shadden, Shawn C.; Hendabadi, Sahar

    2012-01-01

    Platelet activation is a precursor for blood clotting, which plays leading roles in many vascular complications and causes of death. Platelets can be activated by chemical or mechanical stimuli. Mechanically, platelet activation has been shown to be a function of elevated shear stress and exposure time. These contributions can be combined by considering the cumulative stress or strain on a platelet as it is transported. Here we develop a framework for computing a hemodynamic-based activation potential that is derived from a Lagrangian integral of strain rate magnitude. We demonstrate that such a measure is generally maximized along, and near to, distinguished material surfaces in the flow. The connections between activation potential and these structures are illustrated through stenotic flow computations. We uncover two distinct structures that may explain observed thrombus formation at the apex and downstream of stenoses. More broadly, these findings suggest fundamental relationships may exist between potential fluid mechanic pathways for mechanical platelet activation and the mechanisms governing their transport. PMID:22782543

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. Volcano Vents

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 5 May 2003

    This low-relief shield volcano imaged with the THEMIS visible camera has two large vents which have erupted several individual lava flows. The positions of the origins of many of the flows indicate that it is probable that the vents are secondary structures that formed only after the shield was built up by eruptions from a central caldera.

    Image information: VIS instrument. Latitude 17.6, Longitude 243.6 East (116.4 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  6. Space shuttle orbiter venting: Lessons learned

    NASA Technical Reports Server (NTRS)

    Lutfi, H. S.; Nieder, R. L.

    1983-01-01

    The orbiter vent system provides dedicated vent areas to permit the gases trapped inside the vehicle to escape during accent. The same vent system also repressurizes the vehicle during entry. The vent system is one of six systems that constitutes the purge, vent and drain subsystem. The orbiter active vent system has been very adaptable to the changing requirements that have occurred during the development of the Space Shuttle orbiter. Good correlation has been obtained between predicted and measured compartment pressures during the orbital flight test (OFT) program. An investigation of the flight data showed that the difference between preflight prediction and the measured values were primarily due to the difference between the baseline external pressures, which was based on subscale wind tunnel test data, and the actual vehicle local external pressures measured during the flight. The current predictions are based on flight derived vent port pressure coefficients since the wind tunnel data does not adequately define the orbiter ascent pressure environment.

  7. 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.

  8. 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.

  9. 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.

  10. Geological and hydrothermal controls on the distribution of megafauna in Ashes Vent Field, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Arquit, Anne M.

    1990-08-01

    A computerized data base was constructed to aid in the interpretation of biological and geological observations recorded from 7662 photographs taken of Ashes vent field (located along the SW wall of the summit caldera of Axial Volcano, Juan de Fuca Ridge) during 1985-1986 using the Pisces IV submersible and a towed camera system. The transition region between the locus of high-temperature vents in Ashes vent field (i.e., Inferno, 326°C; Hell, 301°C; and Virgin Mound, 298°C) and more typical environmental conditions for the summit caldera of Axial Volcano as a whole is zoned spatially with respect to sediment type and organism assemblage. Three general ecological zones are identified within the vent field: (1) the central vent zone (within 100 m of a high-temperature vent), dominated by vent-associated organisms (vestimentiferan tube worms, clams, bacterial mats) and sedimentation (high-temperature, plume-derived and low-temperature, in situ deposits); (2) the distal vent zone (100-725 m from any high-temperature vent), characterized by extensive fields of iron oxide, iron silicate and silica chimneys and sediment (nontronite assemblage material), as well as maximum densities of most nonvent fauna; and (3) the nonvent impact zone (725-1300 m), indicated by elevated densities of nonvent organisms relative to regional (i.e., caldera-wide) values and maximum Bathydorus sp. sponge densities. The distribution of vestimentiferan tube worms is limited to within 90 m of known high-temperature venting (central vent zone); and anemones were observed only between 30 and 40 m from hot vents. Clams and microbial mats are concentrated in the central vent zone, as well, but occur sporadically up to 1250 m from the hot vents in association with hydrothermal nontronite that is probably precipitating in situ from <60°C vent fluid; thus megafaunal distributions are a useful indicator of poorly defined, often diffuse low-temperature hydrothermal activity on the seafloor. Maximum

  11. Permeability-porosity relationships in seafloor vent deposits: Dependence on pore evolution processes

    NASA Astrophysics Data System (ADS)

    Zhu, Wenlu; Tivey, Margaret K.; Gittings, Hilary; Craddock, Paul R.

    2007-05-01

    Systematic laboratory measurements of permeability and porosity were conducted on three large vent structures from the Mothra Hydrothermal vent field on the Endeavor segment of the Juan de Fuca Ridge. Geometric means of permeability values obtained from a probe permeameter are 5.9 × 10-15 m2 for Phang, a tall sulfide-dominated spire that was not actively venting when sampled; 1.4 × 10-14 m2 for Roane, a lower-temperature spire with dense macrofaunal communities growing on its sides that was venting diffuse fluid of <300°C and 1.6 × 10-14 m2 for Finn, an active black smoker with a well-defined inner conduit that was venting 302°C fluids prior to recovery. Twenty-three cylindrical cores were then taken from these vent structures. Permeability and porosity of the drill cores were determined on the basis of Darcy's law and Boyle's law, respectively. Permeability values range from ˜10-15 to 10-13 m2 for core samples from Phang, from ˜10-15 to 10-12 m2 for cores from Roane, and from ˜10-15 to 3 × 10-13 m2 for cores from Finn, in good agreement with the probe permeability measurements. Permeability and porosity relationships are best described by two different power law relationships with exponents of ˜9 (group I) and ˜3 (group II). Microstructural analyses reveal that the difference in the two permeability-porosity relationships reflects different mineral precipitation processes as pore space evolves within different parts of the vent structures, either with angular sulfide grains depositing as aggregates that block fluid paths very efficiently (group I), or by late stage amorphous silica that coats existing grains and reduces fluid paths more gradually (group II). The results suggest that quantification of permeability and porosity relationships leads to a better understanding of pore evolution processes. Correctly identifying permeability and porosity relationships is an important first step toward accurately estimating fluid distribution, flow rate, and

  12. 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

  13. 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.

  14. 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

  15. Liquid CO2 venting on the seafloor: Yonaguni Knoll IV hydrothermal system, Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Konno, U.; Tsunogai, U.; Nakagawa, F.; Nakaseama, M.; Ishibashi, J.; Nunoura, T.; Nakamura, K.

    2006-12-01

    In 2000, an active hydrothermal site, venting high-temperature fluid up to 300 oC, was discovered by Shinkai 6500 on the top of Yonaguni Knoll IV during YK 00-06 cruise in Okinawa Trough. During the subsequent subseafloor survey using Shinkai 6500 in 2003 (YK03-05), vents of liquid CO2 droplets were found at the site. Similar liquid CO2 droplets had previously been found at the active hydrothermal sites at JADE hydrothermal field, Okinawa Trough, during the extensive seafloor survey using submersibles in 1989 [Sakai et al., 1990]. Besides, similar liquid CO2 venting has also been recognized in NW Eifuku hydrothermal site on Izu-Bonin- Mariana arc. It thus appears that liquid CO2 venting might be usual phenomenon in some submarine arc volcanoes. The detailed relation between seafloor venting liquid CO2 and the surrounding high-temperature hydrothermal fluid, however, was not clarified in their studies. Furthermore, no definite evidence was obtained for the presence of CO2-hydrate in the subsurface. In this study, in order to discuss the subseafloor processes responsible for producing liquid CO2 at the Yonaguni Knoll IV site, as well as the possibility of the occurrence of solid CO2-hydrate within the sediments, we determined the chemical and isotopic compositions of the liquid CO2 found on the site, as well as those in hydrothermal fluid venting from the surrounding chimneys. In consequence, the ^13C of both CO2 and CH4 in the liquid CO2 almost coincide with those in the hydrothermal fluid, suggesting that the liquid CO2 must be derived from the hydrothermal fluid. While showing homogeneous ^13C, the hydrothermal fluids exhibit wide variation in gas contents. Active phase separation must be taking place within the conduits. Besides, H2-depletion in the liquid CO2 suggests formation of solid CO2-hydrate must also precede the venting of liquid CO2. In conclusion, liquid CO2 must be produced through following subseafloor processes: phase separation of hydrothermal

  16. 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.

  17. 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

  18. 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.

  19. 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

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

    PubMed

    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

    2010-08-10

    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 approximately 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 approximately 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.

  1. 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

  2. Sizing an emergency venting system for a cryogenic dewar

    NASA Technical Reports Server (NTRS)

    Liu, C. K.; Naes, L. G.; Manikowski, A. F., Jr.

    1986-01-01

    If the vacuum vessel that insulates a cryogenic dewar for a spaceborne experiment prior to launch is damaged, air will leak into the vacuum insulation space. As the sudden heat load causes the pressure to rise in the dewar, a safety disk in the emergency vent line will burst at the design pressure differential to allow vaporized cryogenic fluid to escape. The emergency vent line should be sized such that sufficient gaseous cryogen will be vented to keep the pressure inside the dewar below the design limit. On the other hand, the line should not be so large as to impose an unnecessary heat load on the dewar filled with cryogenic fluid. A vent-line computer program was generated to compute the maximum flow rate allowed for a proposed vent-line system. Parametric studies have been carried out for different burst disk pressure differentials, liquid cryogen ullage, and vent-line sizes.

  3. 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

  4. 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

  5. Active mixing of complex fluids at the microscale.

    PubMed

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

    2015-10-01

    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

  6. Active mixing of complex fluids at the microscale.

    PubMed

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

    2015-10-01

    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.

  7. Dielectric measurements of activated electrorheological fluids (ERF)

    SciTech Connect

    Korobko, E.

    1994-12-31

    The dependence of the dielectric characteristics of electrorheological fluids of different compositions on the electric field intensity and frequency has been found experimentally. The observed variation of tg{delta} and {epsilon} are attributed to the relaxations between polarization and electric conductivity inducing heavy structurization in the ERF. ER suspensions find wide application in mechanical engineering, instrument manufacture, motor-car industry, robotics, aerospace technology, and ship-building industry. Perspective developments of valves without moving parts, clamps, brakes and shock absorbers, vibro-protection systems, hydraulic drives, step-by-step motors, two-stage batching devices, clutches, tensioning devices, display units, acoustic lenses, delay units and many others are known.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

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

    PubMed

    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

    2010-11-23

    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.

  14. 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

  15. 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

  16. Biogeography, biodiversity and fluid dependence of deep-sea cold-seep communities at active and passive margins

    NASA Astrophysics Data System (ADS)

    Sibuet, Myriam; Olu, Karine

    1998-01-01

    To date, several cold-seep areas which fuel chemosynthesis-based benthic communities have been explored, mainly by deployment of manned submersibles. They are located in the Atlantic and in the Eastern and Western Pacific oceans and in the Mediterranean Sea, in depths ranging between 400 and 6000 m in different geological contexts in passive and active margins. Our study is based on a review of the existent literature on 24 deep cold seeps. The geographic distribution of seeps, the variations of origin and composition of fluids, and rates of fluid flow are presented as they are important factors which explain the spatial heterogeneity and the biomass of biological communities. Methane-rich fluid of thermogenic and/or biogenic origin is the principal source of energy for high-productive communities; however, production of sulphide by sulphate reduction in the sediment also has a major role. The dominant seep species are large bivalves belonging to the families Vesicomyidae or Mytilidae. Other symbiont-containing species occur belonging to Solemyidae, Thyasiridae, Lucinidae bivalves, Pogonophora worms, Cladorhizidae and Hymedesmiidae sponges. Most of the symbiont-containing cold-seep species are new to science. Different symbiont-containing species rely on sulphide or methane oxidation, or both, via chemoautotrophic endosymbiotic bacteria. A total of 211 species, from which 64 are symbiont-containing species, have been inventoried. Patterns in biodiversity and biogeography are proposed. A large majority of the species are endemic to a seep area and the symbiont-containing species are mainly endemic to the cold-seep ecosystem. A comparison of species found in other deep chemosynthesis-based ecosystems, hydrothermal vents, whale carcass and shipwreck reduced habitats, reveals from the existing data, that only 13 species, of which five are symbiont-containing species occur, at both seeps and hydrothermal vents. The species richness of cold-seep communities decreases

  17. 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…

  18. 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

  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. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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

  13. 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

  14. Aqueous volatiles in hydrothermal fluids from the Main Endeavour Field, northern Juan de Fuca Ridge: temporal variability following earthquake activity

    NASA Astrophysics Data System (ADS)

    Seewald, Jeffrey; Cruse, Anna; Saccocia, Peter

    2003-12-01

    The Main Endeavour Field, northern Juan de Fuca Ridge, experienced intense seismic activity in June 1999. Hydrothermal vent fluids were collected from sulfide structures in September 1999 and July 2000 and analyzed for the abundance of H2, H2S, CH4, CO2, NH3, Mg and Cl to document temporal and spatial changes following the earthquakes. Dissolved concentrations of CO2, H2, and H2S increased dramatically in the September 1999 samples relative to pre-earthquake abundances, and subsequently decreased during the following year. In contrast, dissolved NH3 and CH4 concentrations in 1999 and 2000 were similar to or less than pre-earthquake values. Aqueous Cl abundances showed large decreases immediately following the earthquakes followed by increases to near pre-earthquake values. The abundances of volatile species at the Main Endeavour Field were characterized by strong inverse correlations with chlorinity. Phase separation can account for 20-50% enrichments of CO2, CH4, and NH3 in low-chlorinity fluids, while temperature- and pressure-dependent fluid-mineral equilibria at near-critical conditions are responsible for order of magnitude greater enrichments in dissolved H2S and H2. The systematic variation of dissolved gas concentrations with chlorinity likely reflects mixing of a low-chlorinity volatile-enriched vapor generated by supercritical phase separation with a cooler gas-poor hydrothermal fluid of seawater chlorinity. Decreased abundances of sediment-derived NH3 and CH4 in 1999 indicate an earthquake-induced change in subsurface hydrology. Elevated CO2 abundances in vent fluids collected in September 1999 provide evidence that supports a magmatic origin for the earthquakes. Temperature-salinity relationships are consistent with intrusion of a shallow dike and suggest that the earthquakes were associated with movement of magma beneath the ridge crest. These data demonstrate the large and rapid response of chemical fluxes at mid-ocean ridges to magmatic activity and

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

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

    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.

  16. 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.

  17. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    .... Link to an amendment published at 78 FR 73986, Dec. 9, 2013. (a) General. Each plumbing fixture trap... more than one fixture, or, (iii) Two or more vented drains when at least one is wet-vented, or 2-inch.... Each individually vented fixture with a 11/2 inch or smaller trap shall be provided with a vent...

  18. 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.

  19. 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.

  20. Comparison of thiol subproteome of the vent mussel Bathymodiolus azoricus from different Mid-Atlantic Ridge vent sites.

    PubMed

    Company, Rui; Torreblanca, Amparo; Cajaraville, Miren; Bebianno, Maria João; Sheehan, David

    2012-10-15

    Deep-sea hydrothermal mussels Bathymodiolus azoricus live in the mixing zone where hydrothermal fluid mixes with bottom seawater, creating large gradients in the environmental conditions and are one of the most studied hydrothermal species as a model of adaptation to extreme conditions. Thiol proteins, i.e. proteins containing a thiol or sulfhydryl group (SH) play major roles in intracellular stress defense against reactive oxygen species (ROS) and are especially susceptible to oxidation. However, they are not particularly abundant, representing a small percentage of proteins in the total proteome and therefore are difficult to study by proteomic approaches. Activated thiol sepharose (ATS) was used for the rapid and quantitative selection of proteins comprising thiol- or disulfide-containing subproteomes. This study aims to isolate thiol-containing proteins from the gills of B. azoricus collected in distinct hydrothermal vents and to study the thiol-containing subproteome as a function of site-specific susceptibility to ROS. Results show that ATS is a powerful tool to isolate the thiol-containing sub-proteome and differently-expressed protein spots showed significant differences among the three vent sites, supporting previous findings that specific environmental conditions are crucial for ROS formation and that B. azoricus have different susceptibilities to oxidative stress depending on the vent site they inhabit.

  1. Dynamic character of the hydrothermal vent habitat and the nature of sulphide chimney fauna

    NASA Astrophysics Data System (ADS)

    Tunnicliffe, Verena; Kim Juniper, S.

    A major substratum for vent organisms on Juan de Fuca and Explorer Ridges of the northeast Pacific is the polymetallic sulphide chimney. The deposition processes and subsequent growth of such chimneys provide a dynamic and extreme habitat that changes rapidly. During initial venting stages, colonization must await stabilization of the chimney structure. As the porous anhydrite shell accumulates sulphide minerals, protection from direct hot water contact increases for organisms colonizing the outer walls while sufficient vent water still diffuses for the support of chemosynthesis. Vestimentiferan worms are found on small sulphide mounds but the active growth and collapse of anhydrite spires is a major source of disruption and mortality. High temperature venting and spire growth appear to attract alvinellid polychaetes which may be implicated in the process of strengthening and sealing the anhydrite spires. Fauna on the growing chimney is subject to changes in fluid flow patterns that can make the structure uninhabitable. Large chimneys are inhabited by more species indicating that a diversification of habitat results from variations in mineralization and fluid availability. Chimney fauna has become specialized in exploiting an unpredictable and unstable habitat in an extreme example of the control of biotic development by the physical environment.

  2. 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.

  3. Biodiversity and biogeography of hydrothermal vent species in the western Pacific: a biological perspective of TAIGA project

    NASA Astrophysics Data System (ADS)

    Seo, M.; Watanabe, H.; Nakamura, M.; Sasaki, T.; Ogura, T.; Yahagi, T.; Takahashi, Y.; Ishibashi, J.; Kojima, S.

    2012-12-01

    Deep-sea hydrothermal vents are scientifically interesting environments where strong interactions of geology, chemistry, and biology can be observed. The hydrothermal vents are geologically controlled in association with magmatic activities while diversity of chemicals (such as hydrogen sulfide) contained in hydrothermal fluid is controlled by geochemical interaction between heated seawater and surrounding rocks. In addition to those geological and chemical characters of hydrothermal vents, high biomasses of chemosynthetic community have been known around many vents since the first discovery in the 1970s. To understand the unique system and diversity of biological communities associated with vents is highly valuable in geological, chemical, and biological sciences. As an activity of the research project "TAIGA (Trans-crustal Advection & In-situ bio-geochemical processes of Global sub-seafloor Aquifer)" (Representative: Tetsuro Urabe, Department of Earth & Planetary Science, the University of Tokyo), we analyzed population structures and connectivity as well as larval ecology of various hydrothermal vent species in the Okinawa Trough and the Mariana Trough in an attempt to estimate faunal transitional history associated with hydrothermal activities. The specimens analyzed in the present study were collected by R/V Yokosuka with manned submersible Shinkai6500 and R/V Natsushima with ROV Hyper-Dolphin during YK10-11 and NT11-20 cruises, respectively. In the Mariana Trough (YK10-11), benthic and planktonic faunas were investigated by multiple sampling and use of plankton samplers in three hydrothermal vents (Snail, Archaean, and Urashima-Pika fields). Faunal compositions were then compared as well as size compositions and genetic diversities of major vent species among local populations. In the Okinawa Trough (NT11-20), multiple quantitative sampling was made with simultaneous environmental measurements at more than two sites in five hydrothermal vents (Minami

  4. Modeling microbial reaction rates in a submarine hydrothermal vent chimney wall

    NASA Astrophysics Data System (ADS)

    LaRowe, Douglas E.; Dale, Andrew W.; Aguilera, David R.; L'Heureux, Ivan; Amend, Jan P.; Regnier, Pierre

    2014-01-01

    The fluids emanating from active submarine hydrothermal vent chimneys provide a window into subseafloor processes and, through mixing with seawater, are responsible for steep thermal and compositional gradients that provide the energetic basis for diverse biological communities. Although several models have been developed to better understand the dynamic interplay of seawater, hydrothermal fluid, minerals and microorganisms inside chimney walls, none provide a fully integrated approach to quantifying the biogeochemistry of these hydrothermal systems. In an effort to remedy this, a fully coupled biogeochemical reaction-transport model of a hydrothermal vent chimney has been developed that explicitly quantifies the rates of microbial catalysis while taking into account geochemical processes such as fluid flow, solute transport and oxidation-reduction reactions associated with fluid mixing as a function of temperature. The metabolisms included in the reaction network are methanogenesis, aerobic oxidation of hydrogen, sulfide and methane and sulfate reduction by hydrogen and methane. Model results indicate that microbial catalysis is generally fastest in the hottest habitable portion of the vent chimney (77-102 °C), and methane and sulfide oxidation peak near the seawater-side of the chimney. The fastest metabolisms are aerobic oxidation of H2 and sulfide and reduction of sulfate by H2 with maximum rates of 140, 900 and 800 pmol cm-3 d-1, respectively. The maximum rate of hydrogenotrophic methanogenesis is just under 0.03 pmol cm-3 d-1, the slowest of the metabolisms considered. Due to thermodynamic inhibition, there is no anaerobic oxidation of methane by sulfate (AOM). These simulations are consistent with vent chimney metabolic activity inferred from phylogenetic data reported in the literature. The model developed here provides a quantitative approach to describing the rates of biogeochemical transformations in hydrothermal systems and can be used to constrain the

  5. 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

  6. Video Observations by Telepresence Reveal Two Types of Hydrothermal Venting on Kawio Barat Seamount

    NASA Astrophysics Data System (ADS)

    Butterfield, D. A.; Holden, J. F.; Shank, T. M.; Tunnicliffe, V.; Sherrin, J.; Herrera, S.; Baker, E. T.; Lovalvo, D.; Makarim, S.; Malik, M. A.; Wirasantosa, S.; Hammond, S. R.

    2010-12-01

    The INDEX-SATAL 2010 expedition began an international exploration of the seafloor in Indonesian waters using the methodology of telepresence, conducting EM302 multibeam mapping, water column CTD, and ROV high-definition video operations and sending data back to Exploration Command Centers in Indonesia and Seattle. Science observers in other locations in the US and Canada were engaged in real-time observations and interpretation of results. One mission goal was to locate hydrothermal or volcanic activity. Intense light scattering and redox potential measurements in the water column over Kawio Barat (KB)indicated a high level of hydrothermal activity, and direct video observations confirmed venting near the summit. None of the other volcanic features west of the Sangihe arc that were investigated during the mission had confirmed hydrothermal activity. ROV capabilities did not include physical sampling or temperature measurement, so our interpretation is based on visual comparison to other known sites. The steep western flank of KB from 2000 m depth to the summit (1850 m) has many areas of white and orange staining on exposed rocks, with some elemental sulfur, and broad areas covered with dark volcaniclastic sand, but no active venting was seen. KB has a summit ridge running WNW-ESE, with a major cross-cutting ridge on the western portion of the summit. Hydrothermal activity is concentrated near the eastern side of this intersection, on both the northern and southern sides of the summit ridge. Venting on the northern side of the summit ridge is characterized by intense white particle-rich fluids emanating directly from the rocky substrate with frozen flows of elemental sulfur down slope. This type of venting is visually very similar to the venting seen on NW Rota-1, an actively erupting volcano in the Mariana arc, and suggests that KB is actively releasing magmatic gases rich in sulfur dioxide to produce the elemental sulfur flows, inferred fine particulate sulfur

  7. 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

  8. 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.

  9. 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.

  10. Cemented mounds and hydrothermal sediments on the detachment surface at Kane Megamullion: A new manifestation of hydrothermal venting

    NASA Astrophysics Data System (ADS)

    Tucholke, Brian E.; Humphris, Susan E.; Dick, Henry J. B.

    2013-09-01

    Long-lived detachment faults are now known to be important in tectonic evolution of slow-spreading mid-ocean ridges, and there is increasing evidence that fluid flow plays a critical role in development of detachment systems. Here we document a new manifestation of low-temperature hydrothermal venting associated with the detachment fault that formed Kane Megamullion ˜3.3-2.1 m.y. ago in the western rift-valley wall of the Mid-Atlantic Ridge. Hydrothermal effects on the detachment surface include (1) cemented mounds of igneous rock and chalk debris containing hydrothermal Mn oxides and Fe oxyhydroxides, and (2) layered deposits of similar Fe-Mn minerals ± interbedded chalks. Mounds are roughly conical, ˜1-10 m high, and contain primarily basalts with lesser gabbro, serpentinite, and polymict breccia. The layered Fe-Mn-rich sediments are flat-bedded to contorted and locally are buckled into low-relief linear or polygonal ridges. We propose that the mounds formed where hydrothermal fluids discharged through the detachment hanging wall near the active fault trace. Hydrothermal precipitates cemented hanging-wall debris and welded it to the footwall, and this debris persisted as mounds as the footwall was exhumed and surrounding unconsolidated material sloughed off the sloping detachment surface. Some of the layered Fe-Mn-rich deposits may have precipitated from fluids discharging from the hanging-wall vents, but they also precipitated from low-temperature fluids venting from the exposed footwall through overlying chalks. Observed natural disturbance and abnormally thin hydrogenous Fe-Mn crusts on some contorted, hydrothermal Fe-Mn-rich chalks on ˜2.7 Ma crust suggest diffuse venting that is geologically recent. Results of this study imply that there are significant fluid pathways through all parts of detachment systems and that low-temperature venting through fractured detachment footwalls may continue for several million years off-axis.

  11. 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

  12. 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.

  13. 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

  14. 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

  15. Arsenic concentrations and species in three hydrothermal vent worms, Ridgeia piscesae, Paralvinella sulficola and Paralvinella palmiformis

    NASA Astrophysics Data System (ADS)

    Maher, W. A.; Duncan, E.; Dilly, G.; Foster, S.; Krikowa, F.; Lombi, E.; Scheckel, K.; Girguis, P.

    2016-10-01

    Hydrothermal vents are surficial expressions of subsurface geological and hydrological processes. Fluids emitting from active vents are chemically distinct from bottom seawater, and are enriched in dissolved metals and metalloids, including arsenic. Vent organisms accumulate arsenic but the arsenic speciation in these non-photosynthetic organisms is largely unknown. Here, arsenic concentrations and chemical species were measured in three deep sea hydrothermal vent worms (Ridgeia piscesae, Paralvinella sulfincola and Paralvinella palmiformis) from the Juan de Fuca Ridge in the Northwest pacific. R. piscesae has similar arsenic concentrations (3.8-35 μg g-1) to shallow water polychaetes while P. sulfincola and P. palmiformis have significantly higher arsenic concentrations (420-1417 and 125-321 μg g-1 respectively). R. piscesae contains appreciable quantities of inorganic arsenic (36±14%), monomethyl arsenic (2±2%), dimethyl arsenic (34±21%), an unknown methyl arsenical (7±16%), OSO3-arsenosugar (5±9%), TETRA (4±5%), ThioPO4/ThioDMAE (1±2%) and an unknown thio-arsenical (12±14%). These results suggests that host and symbionts are either involved in the methylation of arsenic, or are bathed in fluids enriched in methylated arsenic as a result of free-living microbial activity. The host carrying out methylation, however, cannot be ruled out. In contrast, 96-97% of the arsenic in P. sulfincola and P. palmiformis is inorganic arsenic, likely the result of arsenic precipitation within and upon the mucus they ingest while feeding. While all worms have oxo- and thio arsenosugars (2-30%), Paralvinella also have small amounts of arsenobetaine (<0.001-0.21%). The presence of arsenosugars, arsenobetaine and other minor arsenic species in the absence of photosynthesising algae/bacteria indicates that they may be formed by vent animals in the absence of sunlight, but at this time their formation cannot be explained.

  16. 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.

  17. Spontaneous and specific activation of chemical bonds in macromolecular fluids.

    PubMed

    Park, Insun; Shirvanyants, David; Nese, Alper; Matyjaszewski, Krzysztof; Rubinstein, Michael; Sheiko, Sergei S

    2010-09-01

    Mechanical activation of chemical bonds typically involves the application of external forces, which implies a broad distribution of bond tensions. We demonstrate that controlling the flow profile of a macromolecular fluid generates and delineates mechanical force concentration, enabling a hierarchical activation of chemical bonds on different length scales from the macroscopic to the molecular. Bond tension is spontaneously generated within brushlike macromolecules as they spread on a solid substrate. The molecular architecture creates an uneven distribution of tension in the covalent bonds, leading to spatially controlled bond scission. By controlling the flow rate and the gradient of the film pressure, one can sever the flowing macromolecules with high precision. Specific chemical bonds are activated within distinct macromolecules located in a defined area of a thin film. Furthermore, the flow-controlled loading rate enables quantitative analysis of the bond activation parameters.

  18. 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.

  19. Fluid Shear Stress Increases Neutrophil Activation via Platelet-Activating Factor

    PubMed Central

    Mitchell, Michael J.; Lin, Kimberly S.; King, Michael R.

    2014-01-01

    Leukocyte exposure to hemodynamic shear forces is critical for physiological functions including initial adhesion to the endothelium, the formation of pseudopods, and migration into tissues. G-protein coupled receptors on neutrophils, which bind to chemoattractants and play a role in neutrophil chemotaxis, have been implicated as fluid shear stress sensors that control neutrophil activation. Recently, exposure to physiological fluid shear stresses observed in the microvasculature was shown to reduce neutrophil activation in the presence of the chemoattractant formyl-methionyl-leucyl-phenylalanine. Here, however, human neutrophil preexposure to uniform shear stress (0.1–2.75 dyn/cm2) in a cone-and-plate viscometer for 1–120 min was shown to increase, rather than decrease, neutrophil activation in the presence of platelet activating factor (PAF). Fluid shear stress exposure increased PAF-induced neutrophil activation in terms of L-selectin shedding, αMβ2 integrin activation, and morphological changes. Neutrophil activation via PAF was found to correlate with fluid shear stress exposure, as neutrophil activation increased in a shear stress magnitude- and time-dependent manner. These results indicate that fluid shear stress exposure increases neutrophil activation by PAF, and, taken together with previous observations, differentially controls how neutrophils respond to chemoattractants. PMID:24853753

  20. Aqueous Volatiles in Lau Basin Hydrothermal Fluids

    NASA Astrophysics Data System (ADS)

    Seewald, J.; McCollom, T.; Proskurowski, G.; Reeves, E.; Mottl, M.; Sharkey, J.; Wheat, C. G.; Tivey, M.

    2005-12-01

    The Lau Basin is a back-arc spreading center characterized by widespread hydrothermal activity. High and low temperature vent fluids were collected from six vent fields along the Eastern Lau Spreading Center (ELSC) and the Valu Fa Ridge (VFR) using isobaric gas-tight samplers during R/V Melville cruise TUIM05MV. Fluids were analyzed for the abundances of H2, H2S, CH4, CO2, and CO to assess chemical environments inhabited by biological vent communities and constrain fluid-rock reactions and magmatic processes in subsurface environments. Maximum measured temperatures for focused venting in these areas varied from 309 to 363°C. Water depths decreased from ~2700m for sites sampled at the northern end of the ELSC to ~1725m for the southern most site sampled on the VFR. Endmember concentrations of dissolved H2 at the Kilo Moana, TowCam, and ABE vent fields on the ELSC varied from 0.054 to 0.498 mmol/l and showed a systematic interfield decrease from north to south along the ridge crest. A similar spatial trend was observed for endmember H2S concentrations that varied from 2.6 to 6.6 mmol/l. In contrast to H2 and H2S, aqueous CH4 abundances that varied from 0.028 to 0.057 mmol/l increased from north to south. In general, fluids from the Tui Malila, Mariner, and Vai Lili vent fields on the VFR showed greater compositional variability than fluids venting along the ELSC and an absence of systematic along strike chemical trends. Endmember H2, H2S, and CH4 abundances at VFR ranged from 0.0029 to 0.178 mmol/l, 0.010 to 9.6 mmol/l, and 0.0029 to 0.043 mmol/l, respectively. Endmember concentrations of dissolved CO at ELSC and VFR varied from 0.01 to 0.1 umol/l and showed systematic variations with dissolved H2 and CO2 abundances. Assessment of the CO, CO2, and H2 concentrations within a thermodynamic framework suggests that these species have attained equilibrium states at measured vent temperatures and pressures. The higher degree of compositional variability observed in vents

  1. 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

  2. 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

  3. 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.

  4. 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

  5. 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.

  6. Integrated approach for active coupling of structures and fluids

    NASA Technical Reports Server (NTRS)

    Guruswamy, Guru P.

    1989-01-01

    Strong coupling of structure and fluids is common in many engineering environments, particularly when the flow is nonlinear and very sensitive to structural motions. Such coupling can give rise to physically important phenomena, such as a dip in the transonic flutter boundary of a wing. The coupled phenomenon can be analyzed in closed form for simple cases that are defined by linear structural and fluid equations of motion. However, complex cases defined by nonlinear equations pose a more difficult task for solution. It is important to understand these nonlinear coupled problems, since they may lead to physically important new phenomena. Flow discontinuities, such as a shock wave, and structural discontinuities, such as a hinge line of a control surface of a wing, can magnify the coupled effects and give rise to new phenomena. To study such a strongly coupled phenomenon, an integrated approach is presented in this paper. The aerodynamic and structural equations of motion are simultaneously integrated by a time-accurate numerical scheme. The theoretical simulation is done using the time-accurate unsteady transonic aerodynamic equations coupled with modal structural equations of motion. As an example, the coupled effect of shock waves and hinge-line discontinuities are studied for aeroelastically flexible wings with active control surfaces. The simulation in this study is modeled in the time domain and can be extended to simulate accurately other systems where fluids and structures are strongly coupled.

  7. 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.

  8. Food-Web Complexity in Guaymas Basin Hydrothermal Vents and Cold Seeps

    PubMed Central

    Olu, Karine; Dubois, Stanislas F.; Escobar-Briones, Elva; Gelinas, Yves; Menot, Lénaick; Sarrazin, Jozée

    2016-01-01

    In the Guaymas Basin, the presence of cold seeps and hydrothermal vents in close proximity, similar sedimentary settings and comparable depths offers a unique opportunity to assess and compare the functioning of these deep-sea chemosynthetic ecosystems. The food webs of five seep and four vent assemblages were studied using stable carbon and nitrogen isotope analyses. Although the two ecosystems shared similar potential basal sources, their food webs differed: seeps relied predominantly on methanotrophy and thiotrophy via the Calvin-Benson-Bassham (CBB) cycle and vents on petroleum-derived organic matter and thiotrophy via the CBB and reductive tricarboxylic acid (rTCA) cycles. In contrast to symbiotic species, the heterotrophic fauna exhibited high trophic flexibility among assemblages, suggesting weak trophic links to the metabolic diversity of chemosynthetic primary producers. At both ecosystems, food webs did not appear to be organised through predator-prey links but rather through weak trophic relationships among co-occurring species. Examples of trophic or spatial niche differentiation highlighted the importance of species-sorting processes within chemosynthetic ecosystems. Variability in food web structure, addressed through Bayesian metrics, revealed consistent trends across ecosystems. Food-web complexity significantly decreased with increasing methane concentrations, a common proxy for the intensity of seep and vent fluid fluxes. Although high fluid-fluxes have the potential to enhance primary productivity, they generate environmental constraints that may limit microbial diversity, colonisation of consumers and the structuring role of competitive interactions, leading to an overall reduction of food-web complexity and an increase in trophic redundancy. Heterogeneity provided by foundation species was identified as an additional structuring factor. According to their biological activities, foundation species may have the potential to partly release the

  9. 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.

  10. Scientists as stakeholders in conservation of hydrothermal vents.

    PubMed

    Godet, Laurent; Zelnio, Kevin A; VAN Dover, Cindy L

    2011-04-01

    Hydrothermal vents are deep-sea ecosystems that are almost exclusively known and explored by scientists rather than the general public. Continuing scientific discoveries arising from study of hydrothermal vents are concommitant with the increased number of scientific cruises visiting and sampling vent ecosystems. Through a bibliometric analysis, we assessed the scientific value of hydrothermal vents relative to two of the most well-studied marine ecosystems, coral reefs and seagrass beds. Scientific literature on hydrothermal vents is abundant, of high impact, international, and interdisciplinary and is comparable in these regards with literature on coral reefs and seagrass beds. Scientists may affect hydrothermal vents because their activities are intense and spatially and temporally concentrated in these small systems. The potential for undesirable effects from scientific enterprise motivated the creation of a code of conduct for environmentally and scientifically benign use of hydrothermal vents for research. We surveyed scientists worldwide engaged in deep-sea research and found that scientists were aware of the code of conduct and thought it was relevant to conservation, but they did not feel informed or confident about the respect other researchers have for the code. Although this code may serve as a reminder of scientists' environmental responsibilities, conservation of particular vents (e.g., closures to human activity, specific human management) may effectively ensure sustainable use of vent ecosystems for all stakeholders.

  11. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    .... (a) General. Each plumbing fixture trap shall be protected against siphonage and back pressure, and... 2-inch wet vented drain that carries the waste of not more than one fixture, or, (iii) Two or more... § 3280.611(c)(5) for 3-inch trap arms. (2) Vent pipe areas. Each individually vented fixture with a...

  12. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .... (a) General. Each plumbing fixture trap shall be protected against siphonage and back pressure, and... 2-inch wet vented drain that carries the waste of not more than one fixture, or, (iii) Two or more... § 3280.611(c)(5) for 3-inch trap arms. (2) Vent pipe areas. Each individually vented fixture with a...

  13. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    .... (a) General. Each plumbing fixture trap shall be protected against siphonage and back pressure, and... 2-inch wet vented drain that carries the waste of not more than one fixture, or, (iii) Two or more... § 3280.611(c)(5) for 3-inch trap arms. (2) Vent pipe areas. Each individually vented fixture with a...

  14. 24 CFR 3280.611 - Vents and venting.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    .... (a) General. Each plumbing fixture trap shall be protected against siphonage and back pressure, and... 2-inch wet vented drain that carries the waste of not more than one fixture, or, (iii) Two or more... § 3280.611(c)(5) for 3-inch trap arms. (2) Vent pipe areas. Each individually vented fixture with a...

  15. 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

  16. 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.

  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. Reliable activation to novel stimuli predicts higher fluid intelligence.

    PubMed

    Euler, Matthew J; Weisend, Michael P; Jung, Rex E; Thoma, Robert J; Yeo, Ronald A

    2015-07-01

    The ability to reliably respond to stimuli could be an important biological determinant of differences in fluid intelligence (Gf). However, most electrophysiological studies of Gf employ event-related potential (ERP) measures that average brain activity over trials, and hence have limited power to quantify neural variability. Time-frequency analyses can capture cross-trial variation in the phase of neural activity, and thus can help address the importance of neural reliability to differences in Gf. This study recruited a community sample of healthy adults and measured inter-trial phase clustering (ITPC), total spectral power, and ERP amplitudes elicited by Repeated and Novel non-target stimuli during two visual oddball tasks. Condition effects, relations among the EEG measures, and relations with Gf were assessed. Early visual responses to Repeated stimuli elicited higher ITPC, yet only ITPC elicited by Novel stimuli was associated with Gf. Analyses of spectral power further highlighted the contribution of phase consistency to the findings. The link between Gf and reliable responding to changing inputs suggests an important role for flexible resource allocation in fluid intellectual skills.

  19. 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

  20. Young asteroidal fluid activity revealed by absolute age from apatite in carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Zhang, Ai-Cheng; Li, Qiu-Li; Yurimoto, Hisayoshi; Sakamoto, Naoya; Li, Xian-Hua; Hu, Sen; Lin, Yang-Ting; Wang, Ru-Cheng

    2016-09-01

    Chondritic meteorites, consisting of the materials that have formed in the early solar system (ESS), have been affected by late thermal events and fluid activity to various degrees. Determining the timing of fluid activity in ESS is of fundamental importance for understanding the nature, formation, evolution and significance of fluid activity in ESS. Previous investigations have determined the relative ages of fluid activity with short-lived isotope systematics. Here we report an absolute 207Pb/206Pb isochron age (4,450+/-50 Ma) of apatite from Dar al Gani (DaG) 978, a type ~3.5, ungrouped carbonaceous chondrite. The petrographic, mineralogical and geochemical features suggest that the apatite in DaG 978 should have formed during metamorphism in the presence of a fluid. Therefore, the apatite age represents an absolute age for fluid activity in an asteroidal setting. An impact event could have provided the heat to activate this young fluid activity in ESS.

  1. 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.

  2. 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

  3. Liquid CO2 venting on the seafloor: Yonaguni Knoll IV hydrothermal system, Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Konno, Uta; Tsunogai, Urumu; Nakagawa, Fumiko; Nakaseama, Miwako; Ishibashi, Jun-ichiro; Nunoura, Takuro; Nakamura, Ko-ichi

    2006-08-01

    We determined the chemical and isotopic compositions of the liquid CO2 found on Yonaguni IV knoll hydrothermal site, as well as those in hydrothermal fluid venting from the surrounding chimneys. The δ13C of both CO2 and CH4 in the liquid CO2 almost coincide with those in the hydrothermal fluid, suggesting that the liquid CO2 must be derived from the hydrothermal fluid. While showing homogeneous δ13C, the hydrothermal fluids exhibit wide variation in gas contents. Active phase separation must be taking place within the conduits. Besides, H2-depletion in the liquid CO2 suggests formation of solid CO2-hydrate must also precede the venting of liquid CO2. In conclusion, liquid CO2 must be produced through following subseafloor processes: phase separation of hydrothermal fluid due to boiling, formation of solid CO2-hydrate due to cooling of vapor phase, and melting of the solid CO2-hydrate to liquid CO2 due to a temperature increase within the sedimentary layer.

  4. 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.

  5. Current Results and Proposed Activities in Microgravity Fluid Dynamics

    NASA Technical Reports Server (NTRS)

    Polezhaev, V. I.

    1996-01-01

    The Institute for Problems in Mechanics' Laboratory work in mathematical and physical modelling of fluid mechanics develops models, methods, and software for analysis of fluid flow, instability analysis, direct numerical modelling and semi-empirical models of turbulence, as well as experimental research and verification of these models and their applications in technological fluid dynamics, microgravity fluid mechanics, geophysics, and a number of engineering problems. This paper presents an overview of the results in microgravity fluid dynamics research during the last two years. Nonlinear problems of weakly compressible and compressible fluid flows are discussed.

  6. CFD Activity at Aerojet Related to Seals and Fluid Film Bearing

    NASA Technical Reports Server (NTRS)

    Bache, George E.

    1991-01-01

    Computational Fluid Dynamics (CFD) activities related to seals and fluid film bearings are presented. Among the topics addressed are the following: Aerovisc Numeric and its capabilities; Recent Seal Applications; and Future Code Developments.

  7. Distributions and contents of the organic carbon and major heavy metals in aquatic environment surrounding the active submarine hydrothermal vent in the Northwestern Pacific

    NASA Astrophysics Data System (ADS)

    Lee, S.; Iizasa, K.; Shimoda, G.

    2009-12-01

    Since seafloor massive sulfides (SMSs) were firstly found in the central Red Sea in the middle of 20 century, many SMSs have been reported in the settings of oceanic ridges and island arcs. Although seafloor mining of SMSs is likely to be realized in the near future, there are some concerns on hydrothermal biota and ambient environments after seafloor mining. As biota and ambient environments will be affected by the mining of SMSs in direct, researches on the aquatic environment surrounding submarine hydrothermal vents are strongly needed. Because submarine hydrothermal activities are not stable and their life times are relatively short, it is conceivable that the aquatic environments in the hydrothermal field are different from the other site. Therefore, the regular and the long term monitoring in the aquatic environment of the hydrothermal field be strongly required for the more exact and detailed knowledge about the submarine hydrothermal environment. The distributions and the contents of organic carbon and major heavy metals in the seawater columns around hydrothermal fields will be discussed in the present study. In recent, the submarine hydrothermal activities are presumed as one of the factors causing the seasonal fluctuation in concentration of the total organic carbon in the subtropical Northwestern Pacific, but the practical demonstration about this was not carried out yet. The discussion about the distributions and the contents of major heavy metals in the seawater columns around hydrothermal fields will help to understanding of the diffusion through the plume discharged from hydrothermal vents to ambient environments. The samples were collected at and around the hydrothermal fields of the Bayonnaise Knoll caldera on the back-arc rift and the Myojin Knoll and Myojinsho in the Izu-Ogasawara arc, and the Izena cauldron in Okinawa Trough, during at summer in 2008 and 2009 throughout the HT08 cruise by Hakurei-maru and KT09-12 cruise by Tansei-maru. Seawater

  8. 14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel tank vents and carburetor vapor vents... Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... addition— (1) The vents must be arranged to avoid stoppage by dirt or ice formation; (2) The...

  9. 14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel tank vents and carburetor vapor vents... Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... addition— (1) Each vent must be arranged to avoid stoppage by dirt or ice formation; (2) The...

  10. 14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fuel tank vents and carburetor vapor vents... Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... hazard; or (ii) From which fumes could enter personnel compartments. (b) Carburetor vapor vents....

  11. 14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fuel tank vents and carburetor vapor vents... Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... during landing, ground operations, or a survivable impact. (b) Carburetor vapor vents. Each...

  12. 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

  13. 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

  14. 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

  15. 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

  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.

  17. 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.

  18. 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

  19. 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

  20. Time Series Studies of Faunal Colonization and Temperature Variations at Diffuse-Flow Hydrothermal Vent Sites Near 9° 50'N, EPR

    NASA Astrophysics Data System (ADS)

    Shank, T. M.; Scheirer, D.; Fornari, D. J.

    2001-12-01

    The April 1991 discovery of newly-formed hydrothermal vents in areas of intense volcanic activity along the East Pacific Rise (EPR) between 9\\deg 45' and 9\\deg 52'N provided a unique opportunity to follow temporal changes in biological community structure and vent fluid temperature and chemistry since the birth of numerous deep-sea hydrothermal vents. Discrete high resolution biological imaging and fluid chemistry samples have been collected in conjunction with autonomous temperature probe arrays that have monitored the fluid temperature at 10-15 minute intervals since 1993, within four diffuse-flow regions of the BioTransect at 9\\deg 50'N on the EPR. During ~1 year deployments between 1993 and 2000, active vent invertebrate colonization by greater than 500 individuals (representing 8 species) occurred on more than 60 recovered temperature probes comprising 12 arrays. On each temperature probe, the position and length of individual organisms were mapped to correlate the position of settlement and growth rates with the environmental temperatures experienced by these colonists. Regressions of colonization parameters with temperature measures (such as average, minimum, and maximum T) from multiple communities, along with size-frequency histograms and growth rates, indicate that the abundance of the vestimentiferan Tevnia jerichonana was greater than Riftia pachyptila tube worms and bathymodiolid mussels on temperature probes bathed in significantly higher average and maximum temperatures. Results strongly suggest that Tevnia has a greater physiological tolerance to higher temperatures and elevated geochemical concentrations (e.g., sulfide species) than Riftia and mussels. Significant differential colonization onto probes within an array demonstrates thermal and chemical habitat preferences by vestimentiferan tubeworms and mussels. Thus, patterns of active faunal colonization in hydrothermal areas vary with differing temperature regimes and associated environmental

  1. 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.

  2. Quantifying metabolic rates in submarine hydrothermal vent chimneys: A reaction transport model

    NASA Astrophysics Data System (ADS)

    LaRowe, D.; Dale, A.; Aguilera, D.; Amend, J. P.; Regnier, P.

    2012-12-01

    The fluids emanating from active submarine hydrothermal vent chimneys provide a window into subseafloor processes and, through mixing with seawater, are responsible for steep thermal and compositional gradients that provide the energetic basis for diverse biological communities. Although several models have been developed to better understand the dynamic interplay of seawater, hydrothermal fluid, minerals and microorganisms inside chimney walls, none provide a fully integrated approach to quantifying the biogeochemistry of these hydrothermal systems. In an effort to remedy this, a fully coupled biogeochemical reaction transport model of a hydrothermal vent chimney has been developed that explicitly quantifies the rate of microbial catalysis while taking into account geochemical processes such as fluid flow, solute transport and oxidation-reduction reactions associated with fluid mixing as a function of temperature. Methanogenesis, hydrogen oxidation by oxygen and sulfate, sulfide oxidation by oxygen and methane oxidation by oxygen and sulfate are the metabolisms included in the reaction network. Model results indicate that microbial catalysis is fastest in the hottest habitable portion of the vent chimney except for methane oxidation by oxygen, which peaks near the seawater-side of the chimney at 20 nmol /cm^3 yr. The dominant metabolisms in the chimney are hydrogen oxidation by sulfate and oxygen and sulfide oxidation at peak rates 3200 , 300 and 900 nmol /cm^3 yr, respectively. The maximum rate of hydrogenotrophic methanogensis is just under 0.07 nmol /cm^3 yr, the slowest of the metabolisms considered. Due to thermodynamic inhibition, there is no anaerobic oxidation of methane by sulfate (AOM). The model developed here provides a quantitative approach to understanding the rates of biogeochemical transformations in hydrothermal systems and can be used to better understand the role of microbial activity in the deep subsurface.

  3. 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

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

    PubMed

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

    2014-07-01

    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.

  5. 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.

  6. 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.

  7. Microbial Communities in Erupting Fluids from West Mata Volcano, Tonga Arc

    NASA Astrophysics Data System (ADS)

    Huber, J. A.; Cantin, H.; Resing, J.; Butterfield, D. A.

    2009-12-01

    Eruptions provide unique opportunities for sampling the subseafloor microbial habitat due to the release of crustal fluids and microbes into the overlying water column via plumes and new diffuse vents. Work at mid-ocean ridges show that as post-eruption fluids evolve chemically, the subseafloor microbial communities also experience shifts in population structure and diversity. Timely sampling of plume and venting fluids is critical to understanding the microbial response to active volcanic eruptions, as well as resolving the relationship between stability and diversity. In response to eruption indicators observed in the water column during a November 2008 NOAA PMEL cruise, a multidisciplinary expedition funded by NSF and NOAA was mounted in May 2009 with the ROV Jason 2 to survey and observe eruption-related processes at West Mata volcano and the Northeast Lau Spreading Center (NELSC). While eruptive activity was not found at NELSC, explosive and effusive activity was found at W. Mata, located about 200 km southwest of Samoa at a depth of 1200 m. Diffuse venting and eruptive plumes were observed around the summit, and fluids were collected for cell counts, culturing, and DNA- and RNA-based analyses. Despite many vents having a pH of less than 3, all diffuse fluids contained cell concentrations elevated above background seawater, with large clumps of cells and filaments often present. Positive enrichments of anaerobic microbes, including thermophiles and hyperthermophiles, were obtained from a variety of vent and plume samples at 37, 55, 70, and 85 degrees Celsius. DNA- and RNA-based 16S rRNA clone libraries were built from all vent and plume samples. Results indicate that all sites are dominated by bacteria, but at relatively low diversity compared to other diffuse vent sites studied to date, suggesting that the microbial community may be at the early stages of development. Similar to other diffuse vents, most fluids hosted members of the mesophilic sulfur

  8. Dispersal mechanisms of deep-sea hydrothermal vent fauna

    NASA Astrophysics Data System (ADS)

    Mullineaux, Lauren S.; France, Scott C.

    Species living at hydrothermal vents are faced with the problem of how to maintain their populations in a habitat that is patchy and ephemeral on time scales as short as decades. Because active hydrothermal venting is essential for the survival of vent communities, species must be capable of dispersing to a new location before a local vent closes. Many vent species are sessile or have limited mobility as adults, so dispersal can occur only in the larval stage of their life cycle. Larvae are typically small and are relatively weak swimmers, but they can potentially be transported long distances in oceanic currents. The range and frequency of larval dispersal influence how far away and how quickly a species can colonize a new vent habitat (i.e., will it be an opportunistic pioneer colonist or a later arrival), and constrain the amount of genetic exchange among existing vent populations. If dispersal between vent habitats is consistently impeded by geographic or physiological barriers, then gene flow will be reduced. Such barriers to dispersal can result in setting boundaries to a species' range and in genetic differentiation between previously interbreeding populations.

  9. Anti-arthritic activity of root bark of Oroxylum indicum (L.) vent against adjuvant-induced arthritis

    PubMed Central

    Karnati, Mamatha; Chandra, Rodda H; Veeresham, Ciddi; Kishan, Bookya

    2013-01-01

    Background: Oroxylum indicum (Bignoniaceae) also known as Sonapatha is an indigenous medicinal plant widely used in Ayurvedic medicine for over thousands of years. It is an active ingredient of well-known Ayurvedic formulations such as Chyawanprash and Dasamula. Root bark of this plant has tonic and astringent properties and it is also used in rheumatism. Objective: The present investigation was carried out to evaluate the anti-arthritic activity of different extracts of root bark of Oroxylum indicum against adjuvant - induced arthritis in rats. Materials and Methods: Male Wistar rats were used in this study. Arthritis was induced by injecting 0.1 ml Freund's complete adjuvant intra-dermally into the left hind paw of the rats. The paw volume, hematological, biochemical, radiographic and histopathological aspects were evaluated. Results: The relative percentage inhibition potential of paw volume in rats treated with various extracts of Oroxylum indicum was found to be ethyl acetate extract (67.69%) >chloroform extract (64.61%) >n-butanol extract (58.46%) respectively. The hematological parameters like RBC count, hemoglobin content showed significant increase while there was a significant decrease in total WBC count and ESR in all the groups of animals pretreated with root bark extracts. The biochemical parameters such as catalase, glutathione contents showed a significant increase while the lipid peroxide and Cathepsin-D content decreased significantly only in case of ethyl acetate pretreated rats when compared to others. Conclusion: The present study suggests that the chloroform, ethyl acetate and n-butanol extracts of root bark of Oroxylum indicum exhibit anti-arthritic activity. The order of activity of extracts was found to be ethyl acetate >chloroform >n-butanol respectively. PMID:23798888

  10. Vent conditions for expected eruptions at Vesuvius

    NASA Astrophysics Data System (ADS)

    Papale, Paolo; Longo, Antonella

    2008-12-01

    Determining consistent sets of vent conditions for next expected eruptions at Vesuvius is crucial for the simulation of the sub-aerial processes originating the volcanic hazard and the eruption impact. Here we refer to the expected eruptive scales and conditions defined in the frame of the EC Exploris project, and simulate the dynamics of magma ascent along the volcanic conduit for sub-steady phases of next eruptions characterized by intensities of the Violent Strombolian (VS), Sub-Plinian 2 (SP2), and Sub-Plinian 1 (SP1) scale. Sets of conditions for the simulations are determined on the basis of the bulk of knowledge on the past history of Vesuvius [Cioni, R., Bertagnini, A., Santacroce, R., Andronico, D., Explosive activity and eruption scenarios at Somma-Vesuvius (Italy): towards a new classification scheme. Journal of Volcanology and Geothermal Research, this issue.]. Volatile contents (H 2O and CO 2) are parameterized in order to account for the uncertainty in their expected amounts for a next eruption. In all cases the flow in the conduit is found to be choked, with velocities at the conduit exit or vent corresponding to the sonic velocity in the two-phase non-equilibrium magmatic mixture. Conduit diameters and vent mixture densities are found to display minimum overlapping between the different eruptive scales, while exit gas and particle velocities, as well as vent pressures, largely overlap. Vent diameters vary from as low as about 5 m for VS eruptions, to 35-55 m for the most violent SP1 eruption scale. Vent pressures can be as low as less than 1 MPa for the lowest volatile content employed of 2 wt.% H 2O and no CO 2, to 7-8 MPa for highest volatile contents of 5 wt.% H 2O and 2 wt.% CO 2 and large eruptive scales. Gas and particle velocities at the vent range from 100-250 m/s, with a tendency to decrease, and to increase the mechanical decoupling between the phases, with increasing eruptive scale. Except for velocities, all relevant vent quantities are

  11. Wound fluids from human pressure ulcers contain elevated matrix metalloproteinase levels and activity compared to surgical wound fluids.

    PubMed

    Yager, D R; Zhang, L Y; Liang, H X; Diegelmann, R F; Cohen, I K

    1996-11-01

    Fluid from acute surgical wounds and from nonhealing pressure ulcers was examined for the presence of several matrix metalloproteinases. Gelatin zymography demonstrated the presence of two major gelatinases with apparent molecular masses of 72 kDa and 92 kDa and two minor gelatinases with apparent mobilities of 68 kDa and 125 kDa. Antigen-specific sera identified the 72-kDa protein as matrix melloproteinase-2. The same sera also reacted with the 68-kDa protein, which is consistent with it being an activated form of matrix metalloproteinase-2. Antigen-specific sera identified the 92-kDa and 125-kDa proteins as matrix metalloproteinase-9. Levels of matrix metalloproteinase-2 and matrix metalloproteinase-9 were elevated more than 10-fold and 25-fold, respectively, in fluids from pressure ulcers compared with fluids from healing wounds. Examination of total potential and actual collagenolytic activity revealed that fluid from pressure ulcers contained significantly greater levels of both total and active collagenase compared with that of acute surgical wounds. In addition, an enzyme-linked immunosorbent assay demonstrated that fluids from pressure ulcers contained significantly more collagenase complexed with the inhibitor, tissue inhibitor of metalloproteinases. Together, these observations suggest that an imbalance exists between levels of matrix metalloproteinases and their inhibitors in the fluids of pressure ulcers and that this is primarily the result of elevated levels of the matrix metalloproteinases. The presence of excessive levels of activated forms of matrix-degrading enzymes at the wound surface of pressure ulcers may impede the healing of these wounds and may be relevant to the development of new rationales for treatment.

  12. Active microchannel fluid processing unit and method of making

    DOEpatents

    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

    2002-12-10

    The present invention is an active microchannel fluid 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.

  13. Active microchannel fluid processing unit and method of making

    DOEpatents

    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

    2001-01-01

    The present invention is an active microchannel fluid 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.

  14. Active fluid mixing with magnetic microactuators for capture of salmonella

    NASA Astrophysics Data System (ADS)

    Hanasoge, S.; Owen, D.; Ballard, M.; Mills, Z.; Xu, J.; Erickson, M.; Hesketh, P. J.; Alexeev, A.

    2016-05-01

    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 fluid 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 active mixing produced by the microbeads and the cilia in a microchannel. Also, we demonstrate the capture of target species in a sample using microbeads.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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> </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://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://www.ncbi.nlm.nih.gov/pubmed/23785361','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23785361"><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="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</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('https://www.ncbi.nlm.nih.gov/pubmed/23785361','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23785361"><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="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</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://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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4435803','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4435803"><span id="translatedtitle">How do <span class="hlt">activities</span> walking, standing, and resting influence trans-tibial amputee residual limb <span class="hlt">fluid</span> volume?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sanders, Joan; Cagle, John; Allyn, Katheryn; Harrison, Daniel; Ciol, Marcia</p> <p>2015-01-01</p> <p>The purpose of this research was to determine how <span class="hlt">fluid</span> volume changes in the residual limbs of people with trans-tibial amputation were affected by <span class="hlt">activity</span> during test sessions with equal durations of resting, standing, and walking. Residual limb extracellular <span class="hlt">fluid</span> volume was measured using biompedance analysis on 24 participants. Results showed that all subjects lost <span class="hlt">fluid</span> volume during standing with equal weight-bearing, averaging a loss rate of 0.4%/min, and a mean loss over the 25 min test session of 2.6% (s.d.1.1). Sixteen subjects gained limb <span class="hlt">fluid</span> volume during standing (mean gain of 1.0% (s.d.2.5)), and fifteen gained <span class="hlt">fluid</span> volume during rest (mean gain of 1.0% (s.d.2.2)). Walking explained only 39.3% of the total session <span class="hlt">fluid</span> volume change. There was a strong correlation between walk and rest <span class="hlt">fluid</span> volume changes (−0.81). Subjects with peripheral arterial disease experienced relatively high <span class="hlt">fluid</span> volume gains during sitting but minimal changes or losses during sit-to-stand and stand-to-sit transitioning. Healthy female subjects experienced high <span class="hlt">fluid</span> volume changes during transitioning from sit-to-stand and stand-to-sit. The differences in <span class="hlt">fluid</span> volume response among subjects suggest that volume accommodation technologies should be matched to the <span class="hlt">activity</span>-dependent, <span class="hlt">fluid</span> transport characteristics of the individual prosthesis user. PMID:24933719</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=47466&keyword=soil+AND+venting&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=69450876&CFTOKEN=12225873','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=47466&keyword=soil+AND+venting&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=69450876&CFTOKEN=12225873"><span id="translatedtitle">EVALUATION OF SOIL <span class="hlt">VENTING</span> APPLICATION</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 ability of soil <span class="hlt">venting</span> to inexpensively remove large amounts of volatile organic compounds (VOCs) from contaminated soils is well established. However, the time required using <span class="hlt">venting</span> to remediate soils to low contaminant levels often required by state and federal regulators...</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('https://www.ncbi.nlm.nih.gov/pubmed/24862554','PUBMED'); return false;" href="https://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.</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://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://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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5056421','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5056421"><span id="translatedtitle">Young asteroidal <span class="hlt">fluid</span> <span class="hlt">activity</span> revealed by absolute age from apatite in carbonaceous chondrite</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhang, Ai-Cheng; Li, Qiu-Li; Yurimoto, Hisayoshi; Sakamoto, Naoya; Li, Xian-Hua; Hu, Sen; Lin, Yang-Ting; Wang, Ru-Cheng</p> <p>2016-01-01</p> <p>Chondritic meteorites, consisting of the materials that have formed in the early solar system (ESS), have been affected by late thermal events and <span class="hlt">fluid</span> <span class="hlt">activity</span> to various degrees. Determining the timing of <span class="hlt">fluid</span> <span class="hlt">activity</span> in ESS is of fundamental importance for understanding the nature, formation, evolution and significance of <span class="hlt">fluid</span> <span class="hlt">activity</span> in ESS. Previous investigations have determined the relative ages of <span class="hlt">fluid</span> <span class="hlt">activity</span> with short-lived isotope systematics. Here we report an absolute 207Pb/206Pb isochron age (4,450±50 Ma) of apatite from Dar al Gani (DaG) 978, a type ∼3.5, ungrouped carbonaceous chondrite. The petrographic, mineralogical and geochemical features suggest that the apatite in DaG 978 should have formed during metamorphism in the presence of a <span class="hlt">fluid</span>. Therefore, the apatite age represents an absolute age for <span class="hlt">fluid</span> <span class="hlt">activity</span> in an asteroidal setting. An impact event could have provided the heat to <span class="hlt">activate</span> this young <span class="hlt">fluid</span> <span class="hlt">activity</span> in ESS. PMID:27682449</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://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.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://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('https://www.ncbi.nlm.nih.gov/pubmed/22233630','PUBMED'); return false;" href="https://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>2012-01-10</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>.</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.; 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://adsabs.harvard.edu/abs/2010AGUFMOS14A..04M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS14A..04M"><span id="translatedtitle">Evidence for deep sea hydrothermal <span class="hlt">fluid</span>-mineral equilibrium from multiple S isotopes</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.; Ono, S.; Tivey, M. K.; Seewald, J.</p> <p>2010-12-01</p> <p>The multiple sulfur isotope systematics of hydrothermal <span class="hlt">fluids</span> and associated sulfide mineral deposits collected in 2006 in the eastern Manus Basin, Papua New Guinea, provide an opportunity to better understand the processes of mineral precipitation, pore <span class="hlt">fluid</span> composition, chemosynthetic energy sources, and metal-rich ore deposition in a felsic-hosted back arc hydrothermal system. Recent advances in multiple-stable isotope analytical techniques now enable the precise determination of all four stable isotopes of sulfur in hydrothermal <span class="hlt">vent</span> <span class="hlt">fluids</span> and co-precipitated sulfide mineral deposits, which may be used as a tracer to distinguish between sulfide derived from igneous rock, microbial sulfate reduction, and thermochemical reduction of seawater sulfate [1]. Multiple-stable isotopes of sulfur may also help constrain the relative contribution of sulfur derived by degassing of magmatic SO2 and sedimentary sulfide mineral inputs, as either process could generate the isotopically light δ34S (< 0‰) observed in some <span class="hlt">vent</span> <span class="hlt">fluids</span>, chalcopyrite chimney linings, and native sulfur collected at Manus Basin. We have analyzed the sulfur isotopic composition of high temperature black smoker <span class="hlt">vent</span> <span class="hlt">fluid</span> and associated chalcopyrite lining the inner walls of <span class="hlt">active</span> conduits from two <span class="hlt">vent</span> fields within the Manus Basin, including PACMANUS, located on the neovolcanic Pual ridge, and <span class="hlt">vents</span> on discrete volcanic domes at SuSu Knolls. Preliminary results yield <span class="hlt">vent</span> <span class="hlt">fluid</span> δ34SH2S values ranging from -4.89 ± 0.02 to 5.41 ± 0.01, which closely match coexisting inner wall δ34Schalcopyrite values, ranging from -4.43 ± 0.01 to 5.64 ± 0.01. These results contrast with previous studies that report systematic differences in <span class="hlt">vent</span> <span class="hlt">fluid</span> δ34SH2S and sulfide minerals from the inner conduits of chimney structures [1, 2, 3]. The Δ33SH2S values of <span class="hlt">vent</span> <span class="hlt">fluids</span> range from -0.031 ± 0.027 to 0.011 ± 0.016, and those of chalcopyrite range from -0.042 ± 0.012 to 0.012 ± 0.010. Preliminary results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007SPIE.6527E..0OA','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007SPIE.6527E..0OA"><span id="translatedtitle">A magnetorheological <span class="hlt">fluid</span>-based controllable <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>Ahmadkhanlou, Farzad; Zite, Jamaal L.; Washington, Gregory N.</p> <p>2007-04-01</p> <p>High customization costs and reduction of natural mobility put current rehabilitative knee braces at a disadvantage. A resolution to this problem is to integrate a Magnetorheological (MR) <span class="hlt">fluid</span>-based joint into the system. A MR joint will allow patients to apply and control a resistive torque to knee flexion and extension. The resistance torque can also be continuously adjusted as a function of extension angle and patient strength (or as a function of time), which is currently impossible with state of the art rehabilitative knee braces. A novel MR <span class="hlt">fluid</span>-based controllable knee brace is designed and prototyped in this research. The device exhibits large resistive torque in the on-state and low resistance in the offstate. The controllable variable stiffness, compactness, and portability of the system make it a proper alternative to current rehabilitative knee braces.</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/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://adsabs.harvard.edu/abs/2007AGUFMOS43A0989S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMOS43A0989S"><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/2012AGUFMOS22B..05D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS22B..05D"><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('https://www.ncbi.nlm.nih.gov/pubmed/19010682','PUBMED'); return false;" href="https://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.</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://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://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('https://www.ncbi.nlm.nih.gov/pubmed/404210','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/404210"><span id="translatedtitle">[Antibacterial and antimycotic <span class="hlt">activity</span> of the amniotic <span class="hlt">fluid</span> against selected germs (author's transl)].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jankowski, R P; Rauskolb, R; Gupta, K G</p> <p>1977-03-01</p> <p>60 samples of amniotic <span class="hlt">fluid</span> from 60 patients were obtained between 14 and 42 weeks gestation by dates and tested for their antibacterial <span class="hlt">activity</span> against staphlococcus aureus strains and brucella abortus and their antimycotic <span class="hlt">activity</span> against Candida albicans. The antibacterial and antimycotic <span class="hlt">activity</span> of the amniotic <span class="hlt">fluid</span> was confirmed. This <span class="hlt">activity</span> increases steadily from the 15th week and reaches its maximum around term between 36 and 42 weeks. The amniotic samples obtained at 20 weeks gestation showed a weak antibacterial <span class="hlt">activity</span> especially against staphlococcus aureus of human origin. The above results are important because of the increasing frequency of early and late diagnostic amniocentesis in pregnancy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20544439','PUBMED'); return false;" href="https://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.</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://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://www.osti.gov/scitech/biblio/6734670','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/6734670"><span id="translatedtitle"><span class="hlt">Fluid</span> relief and check valve</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Blaedel, K.L.; Lord, S.C.; Murray, I.</p> <p>1986-07-17</p> <p>A passive <span class="hlt">fluid</span> pressure relief and check valve allows the relief pressure to be slaved to a reference pressure independently of the exhaust pressure. The pressure relief valve is embodied by a submerged <span class="hlt">vent</span> line in a sealing <span class="hlt">fluid</span>, the relief pressure being a function of the submerged depth. A check valve is embodied by a vertical column of <span class="hlt">fluid</span> (the maximum back pressure being a function of the height of the column of <span class="hlt">fluid</span>). The pressure is <span class="hlt">vented</span> into an exhaust system which keeps the exhaust out of the area providing the reference pressure.</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://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('https://www.ncbi.nlm.nih.gov/pubmed/17841485','PUBMED'); return false;" href="https://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.</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> <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/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/2008TePhL..34..650B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008TePhL..34..650B"><span id="translatedtitle"><span class="hlt">Active</span> control of <span class="hlt">fluid</span> equilibrium in a thermosyphon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bratsun, D. A.; Zyuzgin, A. V.; Polovinkin, K. V.; Putin, G. F.</p> <p>2008-08-01</p> <p>We have theoretically and experimentally studied the problem of automated control over the mechanical equilibrium of an inhomogeneously heated <span class="hlt">fluid</span> in a rectangular convection loop (thermosyphon), which comprises two coupled vertical channels with rectangular cross sections arranged in a unit made of a heat-conducting material. The equilibrium is maintained using a control feedback subsystem (controller) capable of responding to the onset of a convective motion by introducing small changes in the spatial orientation of the thermosyphon in the gravitational field. The effect of the dynamic stabilization of the equilibrium, which is unstable in the absence of control, is achieved in a broad range of parameters of the system. It is established that excess feedback leads to the excitation of oscillations in the system. An analysis of the theoretical model showed that these oscillations are related to a delay in the correction introduced by the controller into the state of the system under control. The experimental data are in perfect agreement with the results of analysis of the theoretical model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=475278','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=475278"><span id="translatedtitle"><span class="hlt">Activation</span> of peripheral blood mononuclear cells in bronchoalveolar lavage <span class="hlt">fluid</span> from patients with sarcoidosis: visualisation of single cell <span class="hlt">activation</span> products.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Pantelidis, P.; Southcott, A. M.; Cambrey, A. D.; Laurent, G. J.; du Bois, R. M.</p> <p>1994-01-01</p> <p>BACKGROUND--Interstitial lung diseases are characterised by the recruitment of mononuclear cells to disease sites where maturation occurs and <span class="hlt">activation</span> products, including lysozyme (LZM), are released. Analysis of in vitro cell culture supernatants for <span class="hlt">activation</span> products masks the functional heterogeneity of cell populations. It is therefore necessary to examine the secretion of <span class="hlt">activation</span> products by single cells to assess whether the <span class="hlt">activation</span> of newly recruited mononuclear phagocytes at the sites of disease in the lung is uniform and controlled by the local microenvironment. METHODS--The reverse haemolytic plaque assay was used to evaluate, at a single cell level, the ability of bronchoalveolar lavage (BAL) <span class="hlt">fluid</span> from seven patients with sarcoidosis to <span class="hlt">activate</span> Ficoll-Hypaque-separated peripheral blood mononuclear cells by comparison with BAL <span class="hlt">fluid</span> from six normal volunteers and nine patients with systemic sclerosis. Monolayers of peripheral blood mononuclear cells and sheep red blood cells were cultured either alone or in the presence of 20% (v/v) BAL <span class="hlt">fluid</span> with a polyclonal anti-LZM antibody. LZM/anti-LZM complexes bound to red blood cells surrounding the secreting cells were disclosed following complement lysis of red blood cells and quantification of plaque dimensions using microscopy and image analysis. RESULTS--Bronchoalveolar lavage <span class="hlt">fluid</span> from all the patients with sarcoidosis increased LZM secretion by peripheral blood mononuclear cells compared with unstimulated mononuclear cells. By contrast, BAL <span class="hlt">fluid</span> from the other individuals had no effect on LZM secretion. CONCLUSIONS--Single cells <span class="hlt">activated</span> by BAL <span class="hlt">fluid</span> can be evaluated by the reverse haemolytic plaque assay. BAL <span class="hlt">fluid</span> from patients with sarcoidosis, but not from patients with systemic sclerosis or normal individuals, contains components capable of <span class="hlt">activating</span> mononuclear phagocytes to secrete lysozyme. Images PMID:7831632</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.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('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://ntrs.nasa.gov/search.jsp?R=19990106579&hterms=vents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dvents','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990106579&hterms=vents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dvents"><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://adsabs.harvard.edu/abs/2005AGUFM.V51C1505B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.V51C1505B"><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('https://www.ncbi.nlm.nih.gov/pubmed/16117781','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16117781"><span id="translatedtitle">Production of lysophosphatidic acid in blister <span class="hlt">fluid</span>: involvement of a lysophospholipase D <span class="hlt">activity</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mazereeuw-Hautier, Juliette; Gres, Sandra; Fanguin, Madie; Cariven, Clotilde; Fauvel, Josette; Perret, Bertrand; Chap, Hugues; Salles, Jean-Pierre; Saulnier-Blache, Jean-Sébastien</p> <p>2005-09-01</p> <p>Lysophosphatidic acid (LPA) is present in abundance in serum resulting from platelet <span class="hlt">activation</span> and is also found in other biological <span class="hlt">fluids</span>. LPA controls numerous cellular responses and plays a role in specific functions such as wound healing, especially in the skin. Nevertheless, its presence in the skin has never been investigated. Since re-epithelialization occurs after blister rupture, we tested the presence of endogenous LPA in blister <span class="hlt">fluid</span> and investigated a possible mechanism for its biosynthesis and biological functions. Using a radioenzymatic assay, LPA was detected in 33 blister <span class="hlt">fluids</span> originating from 24 bullous dermatoses, and at higher concentrations than in plasma. In parallel, blister <span class="hlt">fluids</span> contained a lysophospholipase D (LPLD) <span class="hlt">activity</span> but no detectable phospholipase A2 <span class="hlt">activity</span>. The expressions of the LPLD autotaxin (ATX) and of LPA1-receptor (LPA1-R) were greatly increased in blister skin when compared with normal skin. Finally, LPA was found to have a positive effect on the migration of cultured keratinocytes. These results show that LPA is present in blister <span class="hlt">fluid</span> synthesized by the LPLD ATX. Due to its ability to enhance keratinocyte migration, LPA in blister <span class="hlt">fluid</span> could, via the LPA1-R, play an important role in re-epithelialization occurring after blister rupture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/7607784','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/7607784"><span id="translatedtitle">Changes in cerebrospinal <span class="hlt">fluid</span> levels of malondialdehyde and glutathione reductase <span class="hlt">activity</span> in multiple sclerosis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Calabrese, V; Raffaele, R; Cosentino, E; Rizza, V</p> <p>1994-01-01</p> <p>The chemical composition of human cerebrospinal <span class="hlt">fluid</span> (CSF) is considered to reflect brain metabolism. In this study we measured malondialdehyde (MDA) levels and the <span class="hlt">activity</span> of enzymes involved in antioxidative processes, glutathione reductase and glutathione peroxidase, in human cerebrospinal <span class="hlt">fluid</span> of multiple-sclerosis (MS) patients and normal healthy volunteers. Our results indicated that the cerebrospinal <span class="hlt">fluid</span> in MS showed significantly higher endogenous levels of MDA than the control, as well as a much greater resistance to in-vitro stimulation test. In addition, we found the <span class="hlt">activity</span> of GSH reductase significantly increased, about twice the control values, whereas the <span class="hlt">activity</span> of glutathione peroxidase was markedly decreased as compared to control values. Our findings suggest that in MS the <span class="hlt">activity</span> of antioxidant enzymes is modified, and indicates the conceivable possibility of a pathogenic role of oxidative stress in the determinism of the disease. PMID:7607784</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://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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4836313','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4836313"><span id="translatedtitle">Neuraminidase <span class="hlt">Activity</span> and Resistance of 2009 Pandemic H1N1 Influenza Virus to Antiviral <span class="hlt">Activity</span> in Bronchoalveolar <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>Ruangrung, Kanyarat; Suptawiwat, Ornpreya; Maneechotesuwan, Kittipong; Boonarkart, Chompunuch; Chakritbudsabong, Warunya; Assawabhumi, Jirawatna; Bhattarakosol, Parvapan; Uiprasertkul, Mongkol; Puthavathana, Pilaipan; Wiriyarat, Witthawat; Jongkaewwattana, Anan</p> <p>2016-01-01</p> <p>ABSTRACT Human bronchoalveolar <span class="hlt">fluid</span> is known to have anti-influenza <span class="hlt">activity</span>. It is believed to be a frontline innate defense against the virus. Several antiviral factors, including surfactant protein D, are believed to contribute to the <span class="hlt">activity</span>. The 2009 pandemic H1N1 influenza virus was previously shown to be less sensitive to surfactant protein D. Nevertheless, whether different influenza virus strains have different sensitivities to the overall anti-influenza <span class="hlt">activity</span> of human bronchoalveolar <span class="hlt">fluid</span> was not known. We compared the sensitivities of 2009 pandemic H1N1, seasonal H1N1, and seasonal H3N2 influenza virus strains to inhibition by human bronchoalveolar lavage (BAL) <span class="hlt">fluid</span>. The pandemic and seasonal H1N1 strains showed lower sensitivity to human BAL <span class="hlt">fluid</span> than the H3N2 strains. The BAL <span class="hlt">fluid</span> anti-influenza <span class="hlt">activity</span> could be enhanced by oseltamivir, indicating that the viral neuraminidase (NA) <span class="hlt">activity</span> could provide resistance to the antiviral defense. In accordance with this finding, the BAL <span class="hlt">fluid</span> anti-influenza <span class="hlt">activity</span> was found to be sensitive to sialidase. The oseltamivir resistance mutation H275Y rendered the pandemic H1N1 virus but not the seasonal H1N1 virus more sensitive to BAL <span class="hlt">fluid</span>. Since only the seasonal H1N1 but not the pandemic H1N1 had compensatory mutations that allowed oseltamivir-resistant strains to maintain NA enzymatic <span class="hlt">activity</span> and transmission fitness, the resistance to BAL <span class="hlt">fluid</span> of the drug-resistant seasonal H1N1 virus might play a role in viral fitness. IMPORTANCE Human airway secretion contains anti-influenza <span class="hlt">activity</span>. Different influenza strains may vary in their susceptibilities to this antiviral <span class="hlt">activity</span>. Here we show that the 2009 pandemic and seasonal H1N1 influenza viruses were less sensitive to human bronchoalveolar lavage (BAL) <span class="hlt">fluid</span> than H3N2 seasonal influenza virus. The resistance to the pulmonary innate antiviral <span class="hlt">activity</span> of the pandemic virus was determined by its neuraminidase (NA) gene, and it was shown that the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920041226&hterms=operations+management+definition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Doperations%2Bmanagement%2Bdefinition','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920041226&hterms=operations+management+definition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Doperations%2Bmanagement%2Bdefinition"><span id="translatedtitle">CONE - An STS-based cryogenic <span class="hlt">fluid</span> management experiment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bell, R. S.; Vento, D. M.; Hanna, G. J.</p> <p>1992-01-01</p> <p>An overview of the CONE program is presented which includes a definition of the technology addressed by CONE and a baseline experiment set, a description of the experimental and support subsystems, interface requirements between the STS and the experiment carrier (Hitchhiker M), and the reusability and expansion capacity for additional experiment flights. CONE evaluates three primary technologies: the <span class="hlt">active</span> thermodynamic <span class="hlt">vent</span> system, the passive thermodynamic <span class="hlt">vent</span> system, and liquid acquisition device performance. The cryogenic <span class="hlt">fluid</span> management technology database that the system offers will allow for efficient subcritical cryogenic system designs for operation in a low-gravity environment. This system maximizes the balance between existing component technology and the need for the development of a cryogenic-<span class="hlt">fluid</span>-management (CFM) test bed to investigate and demonstrate methods of storage and handling arenas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS23C2028S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS23C2028S"><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://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://adsabs.harvard.edu/abs/2016GML....36...15C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GML....36...15C"><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('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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4820435','PMC'); return false;" href="https://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('https://www.ncbi.nlm.nih.gov/pubmed/27092118','PUBMED'); return false;" href="https://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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160011495','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160011495"><span id="translatedtitle">Metabolic Potential and <span class="hlt">Activity</span> in <span class="hlt">Fluids</span> of the Coast Range Ophiolite Microbial Observatory, California, USA</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoehler, T.; Som, S.; Schrenk, M.; McCollom, T.; Cardace, D.</p> <p>2016-01-01</p> <p>Metabolic potential and <span class="hlt">activity</span> associated with hydrogen and carbon monoxide were characterized in <span class="hlt">fluids</span> sampled from the the Coast Range Ophiolite Microbial Observatory (CROMO). CROMO consists of two clusters of science-dedicated wells drilled to varying depths up to 35m in the <span class="hlt">actively</span> serpentinizing, Jurassic-age Coast Range Ophiolite of Northern California, along with a suite of pre-existing monitoring wells at the same site. Consistent with the <span class="hlt">fluid</span> chemistry observed in other serpentinizing systems, CROMO <span class="hlt">fluids</span> are highly alkaline, with pH up to 12.5, high in methane, with concentrations up 1600 micromolar, and low in dissolved inorganic carbon (DIC), with concentrations of 10's to 100's of micromolar. CROMO is conspicuous for <span class="hlt">fluid</span> H2 concentrations that are consistently sub-micromolar, orders of magnitude lower than is typical of other systems. However, higher H2 concentrations (10's -100's of micromolar) at an earlier stage of <span class="hlt">fluid</span> chemical evolution are predicted by, or consistent with: thermodynamic models for <span class="hlt">fluid</span> chemistry based on parent rock composition equivalent to local peridotite and with water:rock ratio constrained by observed pH; the presence of magnetite at several wt% in CROMO drill cores; and concentrations of formate and carbon monoxide that would require elevated H2 if formed in equilibrium with H2 and DIC. Calculated Gibbs energy changes for reaction of H2 and CO in each of several metabolisms, across the range of <span class="hlt">fluid</span> composition encompassed by the CROMO wells, range from bioenergetically feasible (capable of driving ATP synthesis) to thermodynamically unfavorable. <span class="hlt">Active</span> consumption relative to killed controls was observed for both CO and H2 during incubation of <span class="hlt">fluids</span> from the pre-existing monitoring wells; in incubations of freshly cored solids, consumption was only observed in one sample set (corresponding to the lowest pH) out of three. The specific metabolisms by which H2 and CO are consumed remain to be determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009DSRII..56.1622P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009DSRII..56.1622P"><span id="translatedtitle">Development of assemblages associated with alvinellid colonies on the walls of high-temperature <span class="hlt">vents</span> at the East Pacific Rise</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pradillon, F.; Zbinden, M.; Le Bris, N.; Hourdez, S.; Barnay, A.-S.; Gaill, F.</p> <p>2009-09-01</p> <p>Several species of the polychaete family Alvinellidae may be considered as 'ecosystem engineer' because, by building their tubes, they modify the architecture of the hydrothermal <span class="hlt">fluid</span>-seawater interface on the walls of <span class="hlt">vent</span> chimneys. This affects the thermal and chemical gradients, and creates a mosaic of micro-niches, which could enable colonization by a variety of less-tolerant species. On high temperature <span class="hlt">vents</span> of the Juan de Fuca Ridge, Alvinellid-dominated communities colonizing first mineral surfaces are followed by a succession of communities with different species composition. On the East Pacific Rise (EPR), tubes of Alvinella spp, may seal the mineral surface on which they grow and decrease <span class="hlt">fluid</span> seepage, or tubes may become encrusted in mineral precipitations. An alvinellid colony may therefore persist for only a restricted time period at a given place. Here we investigated the development of alvinellid colonies on the EPR <span class="hlt">vent</span> sites in order to detect whether a succession of new species less tolerant would follow colonization by Alvinella spp. or if different assemblages are forming depending on local conditions. Using a specially designed device called TRAC (titanium ring for alvinellid colonization), we described the evolution of newly formed colonies. Fifteen experiments were conducted on several chimneys of the 9°N and 13°N <span class="hlt">vent</span> fields of the EPR, over durations ranging from 5 days up to 5 months. Through video analysis, different types of colonies were identified, characterized by increasing thickness of the Alvinella coverage, decreasing <span class="hlt">fluid</span> flow bathing the colony, and decreasing surface temperatures. We showed that the assemblage formed by minerals, tubes, and organisms is produced at a very high rate. While animals may colonize the new surface in less than a week, and tubes are also quickly produced ( Alvinella species may grow their tube up to 1 cm day -1 during the early stages of colonization), mineral precipitation progressively</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.ncbi.nlm.nih.gov/pubmed/24852549','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24852549"><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="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mirigian, Stephen; Schweizer, Kenneth S</p> <p>2014-05-21</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. PMID:24852549</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('http://adsabs.harvard.edu/abs/2014EGUGA..1616710Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1616710Y"><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/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://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://www.osti.gov/scitech/biblio/6952025','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6952025"><span id="translatedtitle">Implications of perennial saline springs for abnormally high <span class="hlt">fluid</span> pressures and <span class="hlt">active</span> thrusting in western California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Unruh, J.R.; Davisson, M.L.; Criss, R.E.; Moores, E.M. )</p> <p>1992-05-01</p> <p>Perennial saline springs in the Rumsey Hills area, southwestern Sacramento Valley, California, locally discharge at high elevations and near ridgetops. The springs are cold, are commonly associated with natural gas seeps, and typically emerge along west-vergent thrust faults. Stable isotope analyses indicate that the spring waters are similar to oil-field formation <span class="hlt">fluids</span> and they have had a significant residence time in the subsurface at moderate temperatures. The nonmeteoric character of the springs demonstrates that they are not being fed by perched water tables. The authors propose that these subsurface formation waters are being forced to the surface by anomalously high porefluid pressures. The Rumsey Hills area is one of Quaternary uplift, thrusting, and crustal shortening, and prospect wells drilled there have encountered anomalously high <span class="hlt">fluid</span> pressures at shallow depths. They attribute these high <span class="hlt">fluid</span> pressures to <span class="hlt">active</span> tectonic compression and shortening of Cretaceous marine sedimentary rocks. The widespread occurrence of anomalously high pore-<span class="hlt">fluid</span> pressures and perennial saline springs in the Coast Ranges and western Great Valley suggests that much of western California may be characterized as a seismically <span class="hlt">active</span>, overpressured thrust belt. The emergence of formation waters along thrust faults further suggests that patterns of subsurface <span class="hlt">fluid</span> flow in western California may be similar to those in overpressured accretionary prisms, and that excess <span class="hlt">fluid</span> pressures may also play a role in the distribution of seismicity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol2/pdf/CFR-2010-title33-vol2-sec159-61.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol2/pdf/CFR-2010-title33-vol2-sec159-61.pdf"><span id="translatedtitle">33 CFR 159.61 - <span class="hlt">Vents</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>2010-07-01</p> <p>... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false <span class="hlt">Vents</span>. 159.61 Section 159.61 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.61 <span class="hlt">Vents</span>. <span class="hlt">Vents</span> must be designed and...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol2/pdf/CFR-2011-title33-vol2-sec159-61.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol2/pdf/CFR-2011-title33-vol2-sec159-61.pdf"><span id="translatedtitle">33 CFR 159.61 - <span class="hlt">Vents</span>.</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>... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false <span class="hlt">Vents</span>. 159.61 Section 159.61 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.61 <span class="hlt">Vents</span>. <span class="hlt">Vents</span> must be designed and...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DSRII.121..193G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DSRII.121..193G"><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/2012AGUFMOS42A..03F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS42A..03F"><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=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('https://www.ncbi.nlm.nih.gov/pubmed/24440264','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24440264"><span id="translatedtitle">Characterizing endogenous and exogenous peroxidase <span class="hlt">activity</span> for bleaching of <span class="hlt">fluid</span> whey and retentate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Campbell, R E; Gerard, P D; Drake, M A</p> <p>2014-03-01</p> <p>The lactoperoxidase (LP) system may be used to achieve the desired bleaching of <span class="hlt">fluid</span> whey with the addition of low concentrations (<50mg/kg) of hydrogen peroxide. The addition of an exogenous peroxidase (EP) to whey may also be used to aid in whey bleaching when the LP system is not fully <span class="hlt">active</span>. The objectives of this study were to monitor LP <span class="hlt">activity</span> in previously refrigerated or frozen milk, <span class="hlt">fluid</span> whey, and whey retentate (10% solids) and to evaluate peroxidase <span class="hlt">activity</span> in <span class="hlt">fluid</span> whey and whey retentate (10% solids), with and without additional EP (2, 1, or 0.5 dairy bleaching units), over a range of pH (5.5-6.5) and temperatures (4-60°C). Subsequent experiments were conducted to determine the relationship between enzyme <span class="hlt">activity</span> and bleaching efficacy. Raw and pasteurized milk, fat-separated pasteurized whey, and whey retentate (10% solids) were evaluated for LP <span class="hlt">activity</span> following storage at 4 or -20°C, using an established colorimetric method. A response surface model was applied to evaluate both endogenous and EP <span class="hlt">activity</span> at various temperatures and pH in freshly manufactured whey and retentate. Refrigerated or frozen storage at the parameters evaluated did not affect LP <span class="hlt">activity</span> in milk, whey, or retentate. In <span class="hlt">fluid</span> whey, with and without added EP, as pH decreased (to 5.5) and temperature increased (to 60°C), peroxidase <span class="hlt">activity</span> increased. Retentate with EP exhibited behavior similar to that of <span class="hlt">fluid</span> whey: as pH decreased and temperature increased, <span class="hlt">activity</span> increased. However, in retentate without EP, as pH increased and temperature increased, <span class="hlt">activity</span> increased. Enzyme <span class="hlt">activity</span> was negatively correlated to bleaching time (time for >80% norbixin destruction) in <span class="hlt">fluid</span> whey but a linear relationship was not evident in retentate. When <span class="hlt">fluid</span> whey is bleached enzymatically, if pH is decreased and temperature is increased, the rate of reaction increases (e.g., bleaching occurs in less time). When bleaching in retentate, a higher pH (pH 6.5 vs. pH 5.5) is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3246237','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3246237"><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="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRB..113.8S06S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRB..113.8S06S"><span id="translatedtitle">Culture-independent characterization of a novel microbial community at a hydrothermal <span class="hlt">vent</span> at Brothers volcano, Kermadec arc, New Zealand</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stott, M. B.; Saito, J. A.; Crowe, M. A.; Dunfield, P. F.; Hou, S.; Nakasone, E.; Daughney, C. J.; Smirnova, A. V.; Mountain, B. W.; Takai, K.; Alam, M.</p> <p>2008-08-01</p> <p>The bacterial and archaeal diversity of a hydrothermal <span class="hlt">vent</span> microbial community at Brothers volcano situated in the Kermadec arc, ˜400 km off the north coast of New Zealand, was examined using culture-independent molecular analysis. An unusual microbial community was detected with only 1% and 40% of the bacterial phylotypes exhibiting >92% small subunit (SSU) rRNA gene sequence similarity with cultivated and noncultivated microbes, respectively. Of the 29 bacterial representative phylotypes, over one third of the SSU rRNA gene sequences retrieved belonged to uncultivated candidate divisions including OP1, OP3, OP5, OP8, OD1, and OP11. All archaeal phylotypes belonged to the phylum Euryarchaeota in the uncultivated groups deep hydrothermal <span class="hlt">vent</span> euryarchaeotal (DHVE) I and II or to the phylum Korarchaeota. Like the bacterial clone library, only a small proportion of archaeal SSU rRNA gene sequences (˜2% and 20%) displayed >92% sequence identity with any archaeal isolates or noncultivated microbes, respectively. Although the bacterial phylotypes detected were phylogenetically most similar to microbial communities detected in methane, hydrocarbon, and carbon dioxide-based hydrothermal and seep environments, no phylotypes directly associated with anaerobic methane oxidation and mcrA <span class="hlt">activity</span> could be detected. The geochemical composition of the <span class="hlt">vent</span> <span class="hlt">fluids</span> at the Brothers-lower cone sample site is unusual and we suggest that it may play a prominent role in the species selection of this microbial community.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11449263','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11449263"><span id="translatedtitle">An off-axis hydrothermal <span class="hlt">vent</span> field near the Mid-Atlantic Ridge at 30 degrees N.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kelley, D S; Karson, J A; Blackman, D K; Früh-Green, G L; Butterfield, D A; Lilley, M D; Olson, E J; Schrenk, M O; Roe, K K; Lebon, G T; Rivizzigno, P</p> <p>2001-07-12</p> <p>Evidence is growing that hydrothermal <span class="hlt">venting</span> occurs not only along mid-ocean ridges but also on old regions of the oceanic crust away from spreading centres. Here we report the discovery of an extensive hydrothermal field at 30 degrees N near the eastern intersection of the Mid-Atlantic Ridge and the Atlantis fracture zone. The <span class="hlt">vent</span> field--named 'Lost City'--is distinctly different from all other known sea-floor hydrothermal fields in that it is located on 1.5-Myr-old crust, nearly 15 km from the spreading axis, and may be driven by the heat of exothermic serpentinization reactions between sea water and mantle rocks. It is located on a dome-like massif and is dominated by steep-sided carbonate chimneys, rather than the sulphide structures typical of 'black smoker' hydrothermal fields. We found that <span class="hlt">vent</span> <span class="hlt">fluids</span> are relatively cool (40-75 degrees C) and alkaline (pH 9.0-9.8), supporting dense microbial communities that include anaerobic thermophiles. Because the geological characteristics of the Atlantis massif are similar to numerous areas of old crust along the Mid-Atlantic, Indian and Arctic ridges, these results indicate that a much larger portion of the oceanic crust may support hydrothermal <span class="hlt">activity</span> and microbial life than previously thought.</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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3483289','PMC'); return false;" href="https://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('https://www.ncbi.nlm.nih.gov/pubmed/23144754','PUBMED'); return false;" href="https://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.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2885518','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2885518"><span id="translatedtitle">Cerebrospinal <span class="hlt">Fluid</span> Secretory Ca2+-Dependent Phospholipase A2 <span class="hlt">Activity</span>: A Biomarker of Blood-Cerebrospinal <span class="hlt">Fluid</span> Barrier Permeability</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chalbot, Sonia; Zetterberg, Henrik; Blennow, Kaj; Fladby, Tormod; Grundke-Iqbal, Inge; Iqbal, Khalid</p> <p>2010-01-01</p> <p>The blood-brain barrier, the blood-cerebrospinal <span class="hlt">fluid</span> barrier (BCB) and other specialized brain barriers are increasingly recognized as a major obstacle to the treatment of most brain disorders. The impairment of these barriers has been implicated in neuropathology of several diseases, such as autism, ischemia, multiple sclerosis and Alzheimer disease. This dual function of the blood-neural barriers points out the importance and need for the development of techniques that can evaluate the nature and level of their integrity. Here we report the discovery of CSF secretory Ca2+-dependent phospholipase A2 (sPLA2) <span class="hlt">activity</span> as a measure of BCB permeability. Lumbar CSF from BCB-impaired (n=26), multiple sclerosis (n=18) and healthy control (n=32) cases was analyzed using both a newly developed continuous fluorescence assay for CSF sPLA2 <span class="hlt">activity</span> and CSF/Serum albumin ratio (QAlb), the most common and established method to evaluate BCB permeability. While both measurements showed no significant differences between multiple sclerosis and age-matched normal healthy cases, they were highly correlated. Though the CSF sPLA2 <span class="hlt">activity</span> and QAlb had over 95 % agreement, the former was found to be more sensitive than the latter in measuring low levels of BCB impairment. PMID:20470866</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> </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.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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25681182','PUBMED'); return false;" href="https://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.</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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4752255','PMC'); return false;" href="https://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://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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3025736','PMC'); return false;" href="https://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://adsabs.harvard.edu/abs/2004AGUFM.V23D..03M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.V23D..03M"><span id="translatedtitle"><span class="hlt">Vent</span> , Voluminous Lava Emissions, Steep Slopes and Pyroclastic Flows at Arenal Volcano, Costa Rica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Malavassi, E.; Fernández, E.; Duarte, E.; van der Laat, R.; Berrocal, M.; Barboza, V.; Hernández, E.; Marino, T.; Sáenz, W.; Hernández, L.</p> <p>2004-12-01</p> <p>The initial explosion of Arenal Volcano, occurred July 29-31, 1968, opened three new craters on the west flank of the volcano. The first lava flow was issued from crater A (1050 m) on September 20, 1968. This crater continued the emission of lava flows until November, 1973. In April, 1974 crater C (1460m) erupted its first lava flow. Between 1974 and 2004 crater C has been constructing a cone which is off set 500 m from the prehistoric summit Arenal cone (1633 m) and has reached an elevation of 1670 m. The slopes of the present day cone developed on crater C are very steep, specially north, northeast and northwest of the cone. Crater C lavas were issued from two <span class="hlt">vents</span>: south and north <span class="hlt">vents</span>. The location of the <span class="hlt">vents</span> inside crater C controlled the direction of flow of the lavas issued from each <span class="hlt">vent</span>. During the last 30 years both <span class="hlt">vents</span> of crater C have been <span class="hlt">active</span> at different times, and it was only in the late eighties during a period of intense strombolian <span class="hlt">activity</span>, that both <span class="hlt">vents</span> were <span class="hlt">active</span> at the same time. During the highest intensity of strombolian <span class="hlt">activity</span> (1987-1989) fall back ejecta from strombolian explosions produced pyroclastic flows. The shift of <span class="hlt">activity</span> from the south <span class="hlt">vent</span> to the north <span class="hlt">vent</span> coincided with the generation of the two largest pyroclastic flows issued by Arenal volcano since 1968. During July, 1975 a very voluminous lava flow erupted from the north <span class="hlt">vent</span> of crater C was descending the NW flank of Arenal when gravitational collapse of the flow produced the 1975 Tabacón River valley pyroclastic flow. This was the first time that a lava was flowing on the very steep, partially altered unconsolidated slopes of the NW flank of Arenal. This pyroclastic flow reached Arenal River located 4.3 km from the summit, this is the largest pyroclastic flow produced by gravitational collapse at Arenal volcano. A similar event occurred in August, 1993 when the migration of <span class="hlt">activity</span> from the south <span class="hlt">vent</span> to the north <span class="hlt">vent</span> of crater C and the emission of a</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('https://www.ncbi.nlm.nih.gov/pubmed/12505866','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12505866"><span id="translatedtitle">Increased cellular <span class="hlt">activity</span> in rat insular cortex after water and salt ingestion induced by <span class="hlt">fluid</span> depletion.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pastuskovas, Cinthia V; Cassell, Martin D; Johnson, Alan Kim; Thunhorst, Robert L</p> <p>2003-04-01</p> <p>Insular cortex (IC) receives inputs from multiple sensory systems, including taste, and from receptors that monitor body electrolyte and <span class="hlt">fluid</span> balance and blood pressure. This work analyzed metabolic <span class="hlt">activity</span> of IC cells after water and sodium ingestion induced by sodium depletion. Rats were injected with the diuretic furosemide (10 mg/kg body wt), followed 5 min later by injections of the angiotensin-converting enzyme inhibitor captopril (5 mg/kg body wt). After 90 min, some rats received water and 0.3 M NaCl to drink for 2 h while others did not. A third group had access to water and saline but was not depleted of <span class="hlt">fluids</span>. All rats were killed for processing of brain tissue for Fos-immunoreactivity (Fos-ir). Nondepleted animals had weak-to-moderate levels of Fos-ir within subregions of IC. <span class="hlt">Fluid</span>-depleted rats without <span class="hlt">fluid</span> access had significantly increased Fos-ir in all areas of IC. Levels of Fos-ir were highest in <span class="hlt">fluid</span>-depleted rats that drank water and sodium. Fos-ir levels were highest in anterior regions of IC and lowest in posterior regions of IC. These results implicate visceral, taste, and/or postingestional factors in the increased metabolic <span class="hlt">activity</span> of cells in IC.</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/abs/2015AGUFMGC53I..04L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMGC53I..04L"><span id="translatedtitle">Nanoparticulate, sub-micron and micron sized particles emanating from 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>Luther, G. W., III; Gartman, A.; Findlay, A.; Yucel, M.; Chan, C. S. Y.</p> <p>2015-12-01</p> <p>Recent data from Geotraces cruises over the MAR and SEPR indicate dissolved and particulate Fe enrichment in waters 1000 and 4000 km from their <span class="hlt">vent</span> sources, respectively. Deep-sea hydrothermal <span class="hlt">vents</span> and the waters in the reactive mixing zone above <span class="hlt">vent</span> orifices have been suggested to be an important source of fine material that can pass through normal filters (0.2 and 0.4 μm). In this work, nanoparticles are defined operationally as that which can pass through a 0.2 μm filter. We investigated two <span class="hlt">vent</span> sites (Lau Basin and the MAR). Chimneys from both <span class="hlt">vent</span> sites have <span class="hlt">fluids</span> that can be sulfide rich or metal rich. We also present chemical and physical chemical data (SEM-EDS, TEM, XRD, EELS) showing some of the materials found in these (nano)particulate phases including pyrite, metal sulfides, silicate and aluminosilicate material. Enrichment of Mg and K in the latter suggest that reverse weathering may occur in the waters within 1-2 meters of the <span class="hlt">vent</span> orifice where <span class="hlt">vent</span> waters mix with cold oxygenated bottom waters.</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://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://adsabs.harvard.edu/abs/2016GeoRL..43.6205C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.6205C"><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://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/2005AGUFMOS21C..05H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFMOS21C..05H"><span id="translatedtitle">Hydrothermal <span class="hlt">Activity</span> and Volcanism on the 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>Haase, K. M.; Scientific Party, M.</p> <p>2005-12-01</p> <p>In April 2005 four recently discovered different hydrothermal fields on the slow-spreading Mid-Atlantic Ridge (MAR) south of the Equator were studied and sampled using a remotely operated vehicle (ROV) during cruise METEOR 64/1. Three of these hydrothermally <span class="hlt">active</span> fields (called Turtle Pits, Red Lion, and Wideawake) occur at about 3000 m water depth in the centre of a MAR segment at 4° 48'S which appears to be volcanically very <span class="hlt">active</span>. The youngest lava flow partly covers the low-temperature, diffuse flow Wideawake mussel field and is thus probably only a few years old. The high-temperature Turtle Pits hydrothermal field with four <span class="hlt">active</span> <span class="hlt">vent</span> structures lies some 300 m west of the diffuse <span class="hlt">vent</span> field and is characterized by boiling <span class="hlt">fluids</span> with temperatures close to 400° C. The mineral assemblage recovered from inactive hydrothermal mounds includes massive magnetite+hematite+sulfate and differs from that of the presently <span class="hlt">active</span> <span class="hlt">vents</span> and indicates more oxidizing conditions during the earlier <span class="hlt">activity</span>. The <span class="hlt">vent</span> <span class="hlt">fluids</span> at Turtle Pits contain relatively high contents of hydrogen which may have formed during iron oxidation processes when basaltic magmas crystallized. The high <span class="hlt">fluid</span> temperatures, the change to more reducing conditions, and the relatively high hydrogen contents in the <span class="hlt">fluids</span> are most likely due to the ascent of magmas from the mantle that fed the very recent eruption. The high-temperature Red Lion hydrothermal field lies some 2 km north of the Turtle Pits field and consists of at least four <span class="hlt">active</span> black smokers surrounded by several inactive sulfide mounds. The composition of the Red Lion <span class="hlt">fluids</span> differs significantly from the Turtle Pits <span class="hlt">fluids</span>, possibly owing largely to a difference in the temperature of the two systems. The fourth hydrothermally <span class="hlt">active</span> field on the southern MAR, the Liliput field, was discovered near 9° 33'S in a water depth of 1500 m and consists of several low-temperature <span class="hlt">vents</span>. A shallow hydrothermal plume in the water column</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://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://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/1980STIN...8021724U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1980STIN...8021724U"><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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Urban, E. W.</p> <p>1980-03-01</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> </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://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://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/1999CSR....19...79T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999CSR....19...79T"><span id="translatedtitle">Effect of shallow-water hydrothermal <span class="hlt">venting</span> on the biota of Matupi Harbour (Rabaul Caldera, New Britain Island, Papua New Guinea)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tarasov, V. G.; Gebruk, A. V.; Shulkin, V. M.; Kamenev, G. M.; Fadeev, V. I.; Kosmynin, V. N.; Malakhov, V. V.; Starynin, D. A.; Obzhirov, A. I.</p> <p>1999-01-01</p> <p>Coastal hydrothermal <span class="hlt">vents</span> in the depth range 0-27 m were studied in Matupi Harbour, a marine bight that is partly isolated from the open sea on the north-east coast of New Britain, Papua New Guinea, where volcanoes are <span class="hlt">active</span>. Planktonic and benthic communities (including bacteria) in the Harbour were compared with adjacent fully marine areas. The environmental parameters assessed included temperature, salinity, O 2, H 2, hydrocarbons, metals, some species of nitrogen and sulphur, inorganic phosphate, silicate and chlorophyll a. There was pronounced stratification of the waters in the Harbour as a result of inflow of heated volcanic <span class="hlt">fluids</span>, most evident in the surface 0-3 m layer. The volcanic <span class="hlt">fluids</span> are rich in phytoplankton nutrients and reduced compounds which stimulate growth of bacterial plankton, bacterial production and enhance primary production. The highest values of photosynthetic fixation (almost 100 mg C m 3 d) and bacterial production (216 mg C m 3 d) found in the Harbour are much greater than previously reported for marine ecosystems. The chemosynthetic fraction of bacterial production varied from 15 to 60%, with highest values in the surface and the near-bottom layers. The zooplankton in the Harbour was dominated by cyclopoid copepods and was low in diversity. Bacterial mats were very evident at the areas of <span class="hlt">venting</span>, dominated by Thiodendron-like species, but both epifauna and infauna were sparse at the <span class="hlt">vents</span>. However, areas adjacent to the hydrothermal <span class="hlt">vents</span> showed the richest benthic communities, with epifauna dominated by corals and sponges and infauna by nematodes. It appeared that benthic community development was inhibited by the hot sediment, rapid sedimentation, lack of hard substratum and large numbers of sponge spicules in the sediment. From dating of the last major volcanic eruption (1943), the Harbour provides an excellent model for studying processes of succession and adaptation in marine communities stressed by shallow</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4512689','PMC'); return false;" href="https://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://adsabs.harvard.edu/abs/2011JPhCS.327a2032S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JPhCS.327a2032S"><span id="translatedtitle">Ground-based <span class="hlt">activities</span> in preparation of SELENE ISS experiment on self-rewetting <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>Savino, R.; Abe, Y.; Castagnolo, D.; Celata, G. P.; Kabov, O.; Kawaji, M.; Sato, M.; Tanaka, K.; Thome, J. R.; Van Vaerenbergh, S.</p> <p>2011-12-01</p> <p>SELENE (SELf rewetting <span class="hlt">fluids</span> for thermal ENErgy management) is a microgravity experiment proposed to the European Space Agency (ESA) in response to the Announcement of Opportunities for Physical Sciences. Main objectives of the microgravity research onboard ISS include the quantitative investigation of heat transfer performances of "self-rewetting <span class="hlt">fluids</span>" and "nano self-rewetting <span class="hlt">fluids</span>" in model heat pipes and validation of adequate theoretical and numerical modelling able to predict their behaviour in microgravity conditions. This article summarizes the results of ground-based research <span class="hlt">activities</span> in preparation of the microgravity experiments. They include: 1) thermophysical properties measurements; 2) study of thermo-soluto-capillary effects in micro-channels; 3) numerical modelling; 4) thermal and concentration distribution measurements with optical (e.g. interferometric) and intrusive techniques; 5) surface tension-driven effects and thermal performances test on different capillary structures and heat pipes; 6) breadboards development and support to definition of scientific requirements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.S23D..07U&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.S23D..07U&link_type=ABSTRACT"><span id="translatedtitle">Velocity-dependent frictional behavior and slip magnitude of a fault affected by <span class="hlt">fluid</span> injection <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>Urpi, L.; Rinaldi, A. P.; Spiers, C. J.</p> <p>2014-12-01</p> <p><span class="hlt">Fluid</span> injection is performed or planned for various <span class="hlt">activities</span>, such as CO2 sequestration, gas storage, waste water disposal, and engineered geothermal system. Static stress and pressure perturbation due to the <span class="hlt">fluid</span> injection may cause different scale earthquake phenomena, from instrumental recorded micro-seismicity to triggering of human-felt events. With this study we present a sensitivity analysis of the slip magnitude for the <span class="hlt">fluid</span> injection in a reservoir-like structure. The reservoir, confined within impervious rock units, is composed by a porous rock mass laterally bounded by a fault. The fault is hydraulically connected to the <span class="hlt">fluid</span> hosting unit. The numerical analysis is based on fully explicit sequential coupling between a multiphase <span class="hlt">fluid</span> flow and a hydromechanical finite element calculation code. When the system conditions approaches failure, the simulation is performed in a fully dynamic mode. The coupling allows simulating change in permeability due to stress/strain change, as well as the slip on the fault due to overpressure and associated stress changes. Interface elements have been used to include the constitutive law characterizing the frictional behaviour of the fault. The change in friction with different slip velocities has been derived from laboratory results. Velocity- and strain-dependent frictional behavior of different patches of the fault influence the system evolution, resulting in larger or smaller slip length for the same injected volume.</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://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('https://www.ncbi.nlm.nih.gov/pubmed/2902043','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2902043"><span id="translatedtitle">Immunosuppressive <span class="hlt">activity</span> of human amniotic <span class="hlt">fluid</span> of normal and abnormal pregnancies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shohat, B; Faktor, J M</p> <p>1988-01-01</p> <p>Twenty specimens of amniotic <span class="hlt">fluid</span> (AF) obtained between week 16 and 18 of gestation from normal pregnant women and six specimens from pregnant women in which trisomia of chromosome 21 was found were tested for immunosuppressive <span class="hlt">activity</span>. Incubation of normal human donor lymphocytes with 0.2-1 mL of AF from normal pregnant women for one hour at 37 degrees C was sufficient for induction of significant inhibition of the ability of these cells to induce a local xenogeneic graft-versus-host reaction (GVHR) as well as inhibition of E and E-<span class="hlt">active</span> rosette formation, the GVHR being the most sensitive test. On the other hand, amniotic <span class="hlt">fluid</span> obtained from the six pregnant women in which trisomia of chromosome 21 was found showed no inhibitory <span class="hlt">activity</span> in either the E or E-<span class="hlt">active</span> rosette formation, nor in the local xenogeneic graft-versus-host reaction. AF from all the women tested was found to have no effect on phenotype expression of the lymphocytes, as tested by the monoclonal antibodies OKT4+ and OKT8+, nor on B-lymphocytes, as tested by surface immunoglobulins. No correlation was found between the alpha-fetoprotein levels in the sera of those women and the immunosuppressive <span class="hlt">activity</span>. These findings indicate that genetic defects of the conceptus are not limited to the embryo but may affect the composition of immunosuppressive components present in normal amniotic <span class="hlt">fluid</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4937142','PMC'); return false;" href="https://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/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('https://www.ncbi.nlm.nih.gov/pubmed/12529639','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12529639"><span id="translatedtitle">Discovery of abundant hydrothermal <span class="hlt">venting</span> on the ultraslow-spreading Gakkel ridge in the Arctic Ocean.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Edmonds, H N; Michael, P J; Baker, E T; Connelly, D P; Snow, J E; Langmuir, C H; Dick, H J B; Mühe, R; German, C R; Graham, D W</p> <p>2003-01-16</p> <p>Submarine hydrothermal <span class="hlt">venting</span> along mid-ocean ridges is an important contributor to ridge thermal structure, and the global distribution of such <span class="hlt">vents</span> has implications for heat and mass fluxes from the Earth's crust and mantle and for the biogeography of <span class="hlt">vent</span>-endemic organisms. Previous studies have predicted that the incidence of hydrothermal <span class="hlt">venting</span> would be extremely low on ultraslow-spreading ridges (ridges with full spreading rates <2 cm x yr(-1)-which make up 25 per cent of the global ridge length), and that such <span class="hlt">vent</span> systems would be hosted in ultramafic in addition to volcanic rocks. Here we present evidence for <span class="hlt">active</span> hydrothermal <span class="hlt">venting</span> on the Gakkel ridge, which is the slowest spreading (0.6-1.3 cm x yr(-1)) and least explored mid-ocean ridge. On the basis of water column profiles of light scattering, temperature and manganese concentration along 1,100 km of the rift valley, we identify hydrothermal plumes dispersing from at least nine to twelve discrete <span class="hlt">vent</span> sites. Our discovery of such abundant <span class="hlt">venting</span>, and its apparent localization near volcanic centres, requires a reassessment of the geologic conditions that control hydrothermal circulation on ultraslow-spreading ridges.</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://adsabs.harvard.edu/abs/2013AGUFM.V32B..06C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V32B..06C"><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/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://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('https://www.ncbi.nlm.nih.gov/pubmed/25750992','PUBMED'); return false;" href="https://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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4353617','PMC'); return false;" href="https://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> </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.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://adsabs.harvard.edu/abs/2006AGUFM.B34A..03F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.B34A..03F"><span id="translatedtitle">Dissolved Carbon Species in Diffuse and Focused Flow Hydrothermal <span class="hlt">Vents</span> at the Main Endeavour Field, Northern 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>Foustoukos, D. I.; Seyfried, W. E.; Ding, K.; Pester, N. J.</p> <p>2006-12-01</p> <p>The magmatic and tectonic event of 1999 had a significant impact on the chemical composition of <span class="hlt">vent</span> <span class="hlt">fluids</span> issuing from the Main Endeavour Field (MEF), Juan de Fuca Ridge. Here, we report dissolved concentrations of H2, CO2, CO and C1-C3 alkanes measured in low and high-temperature hydrothermal <span class="hlt">fluids</span> collected in August 2005 during an RV Atlantis/DSV Alvin expedition at MEF. In comparison with time series data, temperatures of the 2005 <span class="hlt">vent</span> <span class="hlt">fluids</span> were slightly lower than those recorded in the aftermaths of the tectonic event of 1999. The possible cooling of the hydrothermal subseafloor reaction zone is consistent with the observed increase in dissolved Cl to pre-1999 values. Converging compositional trends to pre-1999 conditions are also suggested for dissolved CO2 concentrations (~20 mmol/kg) in Puffer, Sully, Bastille and S&M <span class="hlt">vent</span> <span class="hlt">fluids</span>. In these focused flow and high-temperature <span class="hlt">vent</span> <span class="hlt">fluids</span>, dissolved CO2 is in thermodynamic equilibrium with CO(aq). The systematics of organic species in diffuse flow <span class="hlt">fluids</span>, however, appears to be closely related to processes occurring within the near-seafloor environment. For example, excess CO(aq) observed in the diffuse flow <span class="hlt">fluids</span> at Easter Island is attributed to sluggish CO- CO2(aq) equilibria at low temperatures, suggesting hydrothermal circulation of short-residence times. Short-lived hydrothermal circulation is further supported by the nearly identical C1/(C2+C3) ratios between focused and diffuse flow <span class="hlt">fluids</span>. Furthermore, alkane distribution in the MEF diffuse flow <span class="hlt">fluids</span> suggests direct mixing between seawater and hydrothermal <span class="hlt">fluid</span> with minimal biological inputs, in contrast with the greater effect of microbial methanogenesis proposed in other ridge-crest hydrothermal environments. Thus, the coupling of CO2(aq)-CO(aq) redox equilibrium with dissolved carbon species in low- temperature <span class="hlt">vent</span> <span class="hlt">fluids</span> could provide a better understanding of the effect of subsurface microbial communities upon the composition of mid</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25493812','PUBMED'); return false;" href="https://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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=46212','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=46212"><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://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kamat, S V; Iwaskewycz, B; Beckman, E J; Russell, A J</p> <p>1993-01-01</p> <p>Supercritical <span class="hlt">fluids</span> are a unique class of nonaqueous 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. Images Fig. 6 PMID:8464910</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.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,