Microwave-Hydrothermal Synthesis and Characterization of High-Purity Nb Doped BaTiO3 Nanocrystals

Directory of Open Access Journals (Sweden)

A. Khanfekr

2014-01-01

Full Text Available The synthesis of Nb doped BaTiO3 has been investigated under Microwave-Hydrothermal (MH conditions in the temperature of 150°C for only 2 h using C16H36O4Ti, BaH2O2.8H2O and NbCl5 as Ba, Ti and  Nb sources, respectively.  Typical experiments performed on MH processing have not yet reported for Nb doped BaTiO3.  In the MH process, the formation of high purity nano tetragonal Nb-BaTiO3 was strongly enhanced. New hydrothermal method was used instead of the previous solid state reaction for the BaTiO3±Nb2O3 system. The new method uses high pressure to create nano dimension particles in a lower time and temperature. In case of the phase evolution studies, the XRD pattern measurements and Raman spectroscopy were performed. TEM and FE-SEM images were taken for the detailed analysis of the particle size, surface and morphology.  Synthesis of Nb doped BaTiO3 with the Microwave-hydrothermal provides an advantage of fast crystallization and reduced crystal size when compared to existing methods.

Seafloor Uplift in Middle Valley, Juan de Fuca Ridge: New High-Resolution Pressure Data

Science.gov (United States)

Inderbitzen, K. E.; Becker, K.; Davis, E. E.

2011-12-01

Currently, in-situ seafloor and basement pressures are continuously monitored and recorded by an ODP subseafloor hydrogeological observatory (CORK) located in Middle Valley, Juan de Fuca Ridge. Hole 857D was drilled in 1991 in thickly sedimented crust to a depth of 936 mbsf and instrumented with an original CORK that was replaced in 1996. A large hydrothermal field (Dead Dog) lies roughly 1.7 km north of the hole, and two isolated chimneys and several diffuse flow sites are located ~800 meters northeast. The borehole and the vent fields have been visited periodically by submersible/ROV since 1999. Recent results from the CORK at 857D have shown apparent seafloor uplift, supported by depth records from the submersible Alvin. A constant rate of pressure change of ~6 kPa/yr, from its initiation in 2005 to the visit in 2010, has reduced mean seafloor pressure by ~28 kPa, equivalent to nearly 3 meters of head. This uplift rate is several times the typical pre-eruption inflation rates observed at Axial Seamount further south along the Juan de Fuca Ridge. Initially, the apparent uplift at 857D did not seem to have any effect on local high-temperature hydrothermal venting, however recent operations in Middle Valley revealed distinct changes at not only the hydrothermal field to the northeast, but also a shutdown of high-temperature venting to the north of 857D. We will present new data from Middle Valley, including the first year of data collected by a high-resolution pressure data logger deployed at 857D in June, 2010.

Estimates of fluid pressure and tectonic stress in hydrothermal/volcanic areas:a methodological approach

Directory of Open Access Journals (Sweden)

G. Vilardo

2005-06-01

Full Text Available An analytical approach to estimate the relative contribution of the fluid pressure and tectonic stress in hydrothermal/ volcanic areas is proposed assuming a Coulomb criterion of failure. The analytical procedure requires the coefficient of internal friction, cohesion, rock density, and thickness of overburden to be known from geological data. In addition, the orientation of the principal stress axes and the stress ratio must be determined from the inversion of fault-slip or seismic data (focal mechanisms. At first, the stress magnitude is calculated assuming that faulting occurs in 'dry' conditions (fluid pressure=0. In a second step, the fluid pressure is introduced performing a grid search over the orientation of 1 fault planes that slip by shear failure or 2 cracks that open under different values of fluid pressure and calculating the consistency with the observed fault planes (i.e. strike and dip of faults, cracks, nodal planes from focal mechanisms. The analytical method is applied using fault-slip data from the Solfatara volcano (Campi Flegrei, Italy and seismic data (focal mechanisms from the Vesuvius volcano (Italy. In these areas, the fluid pressure required to activate faults (shear fractures and cracks (open fractures is calculated. At Solfatara, the ratio between the fluid pressure and the vertical stress ?is very low for faults ( ?=0.16 and relatively high for cracks ( ?=0.5. At Vesuvius, ?=0.6. Limits and uncertainties of the method are also discussed.

High-temperature synthesis of highly hydrothermal stable mesoporous silica and Fe-SiO2 using ionic liquid as a template

International Nuclear Information System (INIS)

Liu, Hong; Wang, Mengyang; Hu, Hongjiu; Liang, Yuguang; Wang, Yong; Cao, Weiran; Wang, Xiaohong

2011-01-01

Mesoporous silicas and Fe-SiO 2 with worm-like structures have been synthesized using a room temperature ionic liquid, 1-hexadecane-3-methylimidazolium bromide, as a template at a high aging temperature (150-190 o C) with the assistance of NaF. The hydrothermal stability of mesoporous silica was effectively improved by increasing the aging temperature and adding NaF to the synthesis gel. High hydrothermally stable mesoporous silica was obtained after being aged at 190 o C in the presence of NaF, which endured the hydrothermal treatment in boiling water at least for 10 d or steam treatment at 600 o C for 6 h. The ultra hydrothermal stability could be attributed to its high degree of polymerization of silicate. Furthermore, highly hydrothermal stable mesoporous Fe-SiO 2 has been synthesized, which still remained its mesostructure after being hydrothermally treated at 100 o C for 12 d or steam-treated at 600 o C for 6 h. -- Graphical abstract: Worm-like mesoporous silica and Fe-SiO 2 with high hydrothermal stability have been synthesized using ionic liquid 1-hexadecane-3-methylimidazolium bromide as a template under the assistance of NaF at high temperature. Display Omitted Research highlights: → Increasing aging temperature improved the hydrothermal stability of materials. →Addition of NaF enhanced the polymerization degree of silicates. → Mesoporous SiO 2 and Fe-SiO 2 obtained have remarkable hydrothermal stability.

Alteration of MX-80 by hydrothermal treatment under high salt content conditions

Energy Technology Data Exchange (ETDEWEB)

Pusch, R. [Geodevelopment AB, Lund (Sweden); Kasbohm, J. [Greifswald Univ. (Germany). Geological Dep.

2002-02-01

If brammalit, i.e. sodium illite, is formed from smectite in Na-rich salt water at high temperature such conversion can also take place in the buffer clay that surrounds the canisters in a KBS-3 repository. The present study comprised two laboratory test series with MX-80 clay, one with compacted clay powder with a dry density of 1200 to 1300 kg/m{sup 3} and saturation with 10% and 20% NaCl solutions followed by heating to 110 deg C under closed conditions for 30 days. In the second series air-dry compacted clay powder in a cell was heated at 110 deg C for the same period of time and connected to vessels with 10% and 20% NaCl solutions. The first series represents the conditions in the buffer clay after saturation with Na-rich salt water while the second one corresponds to the conditions in the course of saturation with such water. All laboratory tests were made after short-term percolation with distilled water for making sure that the hydro-thermally treated samples were fully fluid-saturated. The results from the physical testing showed that the hydraulic conductivity and swelling pressure of the hydrothermally treated clay samples were on the same order of magnitude as for untreated clay. Comparison with illitic clays shows that the latter are at least a hundred times more permeable than the hydrothermally treated salt clays in the present study, which hence indicates that conversion to illite was insignificant. This is obvious also from the fact that while illitic clays have very low swelling pressures the hydrothermally treated clays exhibited swelling pressures on the same order of magnitude as untreated MX-80. XRD analysis showed a clear difference in mineral constitution between the two test series. Thus, while no significant change from the typical mineralogy of untreated MX-80 was found for hydrothermal treatment of clay saturated with 10 and 20% NaCl solution, except for some very slight neoformation of illite-smectite mixed layers or irreversible

Hydrothermal liquefaction of biomass

DEFF Research Database (Denmark)

Toor, Saqib; Rosendahl, Lasse; Hoffmann, Jessica

2014-01-01

Biomass is one of the most abundant sources of renewable energy, and will be an important part of a more sustainable future energy system. In addition to direct combustion, there is growing attention on conversion of biomass into liquid en-ergy carriers. These conversion methods are divided...... into biochemical/biotechnical methods and thermochemical methods; such as direct combustion, pyrolysis, gasification, liquefaction etc. This chapter will focus on hydrothermal liquefaction, where high pressures and intermediate temperatures together with the presence of water are used to convert biomass...... into liquid biofuels, with the aim of describing the current status and development challenges of the technology. During the hydrothermal liquefaction process, the biomass macromolecules are first hydrolyzed and/or degraded into smaller molecules. Many of the produced molecules are unstable and reactive...

Application of Hydrothermal Treatment to High Concentrated Sewage Sludge for Anaerobic Digestion Process

OpenAIRE

M. Orikawa; H. Kamahara; Y. Atsuta; H. Daimon

2013-01-01

Tomato and seaweed were produced by utilizing CO2 and heat discharged from power generation using biogas in Toyogawa biomass park, Japan. The biogas was obtained by anaerobic digestion with hydrothermal treatment. The hydrothermal treatment was applied to the high concentrated sewage sludge (22 % total solids (TS) dewatered sludge). The purpose of this study is to clarify the effect of hydrothermal treatment on the qualities of high concentrated sewage sludge, by analyzing particulate organic...

Investigation of high pressure steaming (HPS) as a thermal treatment for lipid extraction from Chlorella vulgaris.

Science.gov (United States)

Aguirre, Ana-Maria; Bassi, Amarjeet

2014-07-01

Biofuels from algae are considered a technically viable energy source that overcomes several of the problems present in previous generations of biofuels. In this research high pressure steaming (HPS) was studied as a hydrothermal pre-treatment for extraction of lipids from Chlorella vulgaris, and analysis by response surface methodology allowed finding operational points in terms of target temperature and algae concentration for high lipid and glucose yields. Within the range covered by these experiments the best conditions for high bio-crude yield are temperatures higher than 174°C and low biomass concentrations (<5 g/L). For high glucose yield there are two suitable operational ranges, either low temperatures (<105°C) and low biomass concentrations (<4 g/L); or low temperatures (<105°C) and high biomass concentrations (<110 g/L). High pressure steaming is a good hydrothermal treatment for lipid recovery and does not significantly change the fatty acids profile for the range of temperatures studied. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synthesis of tungsten oxide nanoparticles using a hydrothermal method at ambient pressure

DEFF Research Database (Denmark)

Ahmadi, Majid; Younesi, Reza; Guinel, Maxime J-F

2014-01-01

) nanoparticles were synthesized using a simple and inexpensive low temperature and low pressure hydrothermal (HT) method. The precursor solution used for the HT process was prepared by adding hydrochloric acid to diluted sodium tungstate solutions (Na2WO4 center dot 2H(2)O) at temperatures below 5 degrees C...... and then dissolved using oxalic acid. This HT process yielded tungstite (WO3 center dot H2O) nanoparticles with the orthorhombic structure. A heat treatment at temperatures at or above 300 degrees C resulted in a phase transformation to monoclinic WO3, while preserving the nanoparticles morphology. The production...

Hydrothermal liquefaction of agricultural and forestry wastes: state-of-the-art review and future prospects.

Science.gov (United States)

Cao, Leichang; Zhang, Cheng; Chen, Huihui; Tsang, Daniel C W; Luo, Gang; Zhang, Shicheng; Chen, Jianmin

2017-12-01

Hydrothermal liquefaction has been widely applied to obtain bioenergy and high-value chemicals from biomass in the presence of a solvent at moderate to high temperature (200-550°C) and pressure (5-25MPa). This article summarizes and discusses the conversion of agricultural and forestry wastes by hydrothermal liquefaction. The history and development of hydrothermal liquefaction technology for lignocellulosic biomass are briefly introduced. The research status in hydrothermal liquefaction of agricultural and forestry wastes is critically reviewed, particularly for the effects of liquefaction conditions on bio-oil yield and the decomposition mechanisms of main components in biomass. The limitations of hydrothermal liquefaction of agricultural and forestry wastes are discussed, and future research priorities are proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chemical environments of submarine hydrothermal systems

Science.gov (United States)

Shock, Everett L.

1992-01-01

Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such

Mild hydrothermal treatment to prepare highly dispersed multi-walled carbon nanotubes

International Nuclear Information System (INIS)

Zhang Li; Hashimoto, Yoshio; Taishi, Toshinori; Ni Qingqing

2011-01-01

Multi-walled carbon nanotubes (MWCNTs) with improved dispersion property have been prepared by a mild and fast hydrothermal treatment. The hydrothermal process avoids using harsh oxidants and organic solvents, which is environmental friendly and greatly decreases the damage to intrinsic structure of MWCNTs. The modified MWCNTs were highly soluble in polar solvents such as water, ethanol and dimethylformamide. Morphological observation by TEM indicated that the diameter and inherent structure were well reserved in modified MWCNTs. X-ray photoelectron spectroscopy and Raman spectroscopy were used to quantify functional groups created on the MWCNT surface, and to determine rational parameters of hydrothermal process.

Improving the circular economy via hydrothermal processing of high-density waste plastics.

Science.gov (United States)

Helmer Pedersen, Thomas; Conti, Federica

2017-10-01

Rising environmental concerns on climate changes are causing an increasing attention on circular economies. The plastic economy, in particular, is in focus due to the accelerating consumption of plastics, mainly derived from virgin feedstock, combined with the lack of plastic recycling strategies. This work presents a novel outlook on the potential of using supercritical hydrothermal processing of waste plastic fractions for tertiary recycling. The study investigates hydrothermal processing of nine different, high-density types of plastics into original resin monomers and other value-added chemical compounds. The outlook presents conversion yields, carbon balances, and chemical details on the products obtained. It is found that all the investigated resins are prone to hydrothermal treatment, and that high yields of monomers and high value compounds (up to nearly 100%), suitable for chemicals and fuels applications, can be obtained. For instance, for polycarbonate, styrene-butadiene, poly(lactic acid), poly(ethylene terephthalate), and poly(butylene terephthalate), original monomeric compounds can be reclaimed for manufacturing new resins. The promising results presented demonstrate that hydrothermal processing of high-density plastics is a prospective technology for increasing the circularity of the plastic economy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Solidification of glass powder by a hydrothermal hot-pressing technique

International Nuclear Information System (INIS)

Nishioka, Mamoru; Yanagisawa, Kazumichi; Yamasaki, Nakamichi

1986-01-01

A borosilicate glass powder was solidified with a NaOH solution or distilled water by the hydrothermal hot-pressing technique. The effect of hydrothermal conditions on the compressive strength was investigated, and the densification mechanism of the glass powder during the hydrothermal hot-pressing was discussed in terms of isothermal shrinkage. The glass powder was successfully solidified by hydrothermal hot-pressing at a reaction temperature lower than that of an ordinary pressure sintering. The solidified body obtained in the presence of distilled water (10 wt%) at 280 deg C had a high compressive strength of about 2300 kg/cm 2 . The analysis of initial densification process of the glass powder in hydrothermal hot-pressing with Murray's rate equation revealed that the densification proceeds both by viscous flow and by rearrangement process. Analysis of the shrinkage rates with a rate equation of hydrothermal reaction suggested that the dissolution of particles into solution controlled the initial densification of the glass powder, and that the alkaline metal acted as a catalyst. (author)

Borehole plugging by hydrothermal transport. Final report

Energy Technology Data Exchange (ETDEWEB)

Roy, D.M.; White, W.B.

1976-02-28

Calcium silicate--and aluminosilicate--compositions based on mixtures of fine grained quartz with various cements or calcium silicate compounds have been investigated under hydrothermal conditions in the temperature range 110-250/sup 0/C and pressure range 1,000-10,000 psi, pressures which are always in excess of that required to maintain liquid H/sub 2/O, and approximate the confining pressures which might be anticipated in deep boreholes. All silicate cement combinations investigated produce materials having adequate strength after reaction times of 1 day or longer. The calcium aluminate cement was also adequate with respect to strength but would need to be investigated more extensively for overall properties because of its highly reactive chemistry. The mini-rock cylinder-cement plug hydrothermal experiments in both limestone and sandstone resulted in reasonable magnitudes of bonding strength. The typical shear strength of a hydrothermally treated cement-sandstone plug is 1030 psi, and the compressive strength of the extruded cement plug is 9550 psi. Reactions having a potential for producing calcium carbonate plugs in holes drilled in carbonate rocks were studied. It should be noted that most cements are calcium silicate systems and are chemically compatible with the CaCO/sub 3/ and CaMg(CO/sub 3/)/sub 2/ in the rock walls of the hole. A side benefit from this research is some insight into the suitability of massive carbonate rocks as disposal sites. Carbonate rocks by themselves are highly impermeable, have low exchange capacity, and a low water content--all properties that are desirable in the storage medium. A major drawback is the presence of secondary permeability in the form of solutionally modified joints, fractures, and bedding planes.

Borehole plugging by hydrothermal transport. Final report

International Nuclear Information System (INIS)

Roy, D.M.; White, W.B.

1976-01-01

Calcium silicate--and aluminosilicate--compositions based on mixtures of fine grained quartz with various cements or calcium silicate compounds have been investigated under hydrothermal conditions in the temperature range 110-250 0 C and pressure range 1,000-10,000 psi, pressures which are always in excess of that required to maintain liquid H 2 O, and approximate the confining pressures which might be anticipated in deep boreholes. All silicate cement combinations investigated produce materials having adequate strength after reaction times of 1 day or longer. The calcium aluminate cement was also adequate with respect to strength but would need to be investigated more extensively for overall properties because of its highly reactive chemistry. The mini-rock cylinder-cement plug hydrothermal experiments in both limestone and sandstone resulted in reasonable magnitudes of bonding strength. The typical shear strength of a hydrothermally treated cement-sandstone plug is 1030 psi, and the compressive strength of the extruded cement plug is 9550 psi. Reactions having a potential for producing calcium carbonate plugs in holes drilled in carbonate rocks were studied. It should be noted that most cements are calcium silicate systems and are chemically compatible with the CaCO 3 and CaMg(CO 3 ) 2 in the rock walls of the hole. A side benefit from this research is some insight into the suitability of massive carbonate rocks as disposal sites. Carbonate rocks by themselves are highly impermeable, have low exchange capacity, and a low water content--all properties that are desirable in the storage medium. A major drawback is the presence of secondary permeability in the form of solutionally modified joints, fractures, and bedding planes

A high-pressure thermal gradient block for investigating microbial activity in multiple deep-sea samples

DEFF Research Database (Denmark)

Kallmeyer, J.; Ferdelman, TG; Jansen, KH

2003-01-01

Details about the construction and use of a high-pressure thermal gradient block for the simultaneous incubation of multiple samples are presented. Most parts used are moderately priced off-the-shelf components that easily obtainable. In order to keep the pressure independent of thermal expansion...... range of temperatures and pressures and can easily be modified to accommodate different experiments, either biological or chemical. As an application, we present measurements of bacterial sulfate reduction rates in hydrothermal sediments from Guyamas Basin over a wide range of temperatures and pressures...

Hydrothermal processing of transuranic contaminated combustible waste

International Nuclear Information System (INIS)

Buelow, S.J.; Worl, L.; Harradine, D.; Padilla, D.; McInroy, R.

2001-01-01

Experiments at Los Alamos National Laboratory have demonstrated the usefulness of hydrothermal processing for the disposal of a wide variety of transuranic contaminated combustible wastes. This paper provides an overview of the implementation and performance of hydrothermal treatment for concentrated salt solutions, explosives, propellants, organic solvents, halogenated solvents, and laboratory trash, such as paper and plastics. Reaction conditions vary from near ambient temperatures and pressure to over 1000degC and 100 MPa pressure. Studies involving both radioactive and non-radioactive waste simulants are discussed. (author)

Development and evaluation of a tracer-injection hydrothermal technique for studies of waste package interactions

International Nuclear Information System (INIS)

Jones, T.E.; Coles, D.G.; Britton, R.C.; Burnell, J.R.

1986-11-01

A tracer-injection system has been developed for use in characterizing reactions of waste package materials under hydrothermal conditions. High-pressure liquid chromatographic instrumentation has been coupled with Dickson-type rocking autoclaves to allow injection of selected components into the hydrothermal fluid while maintaining run temperature and pressure. Hydrothermal experiments conducted using this system included the interactions of depleted uranium oxide and Zircaloy-4 metal alloy discs with trace levels of 99 Tc and non-radioactive Cs and I in a simulated groundwater matrix. After waste-package components and simulated waste forms were pre-conditioned in the autoclave systems (usually 4 to 6 weeks), known quantities of tracer-doped fluids were injected into the autoclaves' gold reaction bag at run conditions. Time-sequenced sampling of the hydrothermal fluid providing kinetic data on the reactions of tracers with waste package materials. The injection system facilitates the design of experiments that will better define ''steady-state'' fluid compositions in hydrothermal reactions. The injection system will also allow for the formation of tracer-bearing solid phases in detectable quantities

The critical singularities of water and its significance in the hydrothermal mineralization of uranium

International Nuclear Information System (INIS)

Hu Baoqun; Lv Guxian; Wang Fangzheng; Sun Zhanxue; Zhu Peng

2008-01-01

Water is the main composition of the geo-fiuid. With the changes of temperature and pressure, its phases and physicochemical properties will vary and the critical singularity occur at the critical point of second-order phase transition. These changes of water will enormously affect the hydrothermal mineralizations. This paper has introduced the types and characteristics of water phase transitions, studied the phase transitions of water in the lithosphere and showed the critical singularity of water with the example of the isobaric heat capacity. The conclusions are as follow: (1) the critical singularities of water are the most obvious as the temperature and pressure near to the critical constants of water; (2) Because the temperature changes with the pressure according to the thermal curve in the lithosphere, it is difficult to find a place where the temperature and pressure can be at the critical constants at same time except the coupling effect of the hydrothermal processes, intermediate-acidic magmatism and faulting; (3) To the hydrothermal mineralization, the significances of water's critical singularities at least include the sharp variation of solubility and instantaneous high pressure to conduct the deposit of ore-forming materials and fault formation. (authors)

Comparison of anti-corrosive properties between hot alkaline nitrate blackening and hydrothermal blackening routes

Energy Technology Data Exchange (ETDEWEB)

Fattah-alhosseini, A. [Department of Materials Engineering, Bu-Ali Sina University, Hamedan 65178-38695 (Iran, Islamic Republic of); Yazdani Khan, H., E-mail: hamid.yazdanikhan@gmail.com [Department of Materials Engineering, Bu-Ali Sina University, Hamedan 65178-38695 (Iran, Islamic Republic of); Heidarpour, A. [Department of Metallurgy and Materials Engineering, Hamedan University of Technology, Hamedan, 65155-579 (Iran, Islamic Republic of)

2016-08-15

In this study, the oxide films were formed on carbon steel by using hot alkaline nitrate and hydrothermal treatments. A dense and protective oxide film was obtained by hydrothermal method due to application of high pressure and by increasing solution temperature from boiling temperature (155 °C) to 250 °C. Oxide films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and electrochemical tests including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). These analyses showed that the magnetite film which was formed on carbon steel surface by hydrothermal treatment offers the best resistance in 3.5 wt.% NaCl solution. Although thicker oxide film could be obtained via hot alkaline nitrate black oxidizing, corrosion resistance was lower as a result of being highly porous and the presence of hematite. - Highlights: • Oxide films have been formed on steel by using of hot alkaline nitrate and hydrothermal treatments. • A dense and protective oxide film was obtained by hydrothermal treatment. • SEM micrographs showed that a dense and protective oxide film was obtained by hydrothermal treatment. • Film formed by hydrothermal treatment could have the best resistance in 3.5 wt.% NaCl solution.

Hydrothermal processing of Hanford tank wastes: Process modeling and control

International Nuclear Information System (INIS)

Currier, R.P.

1994-01-01

In the Los Alamos National Laboratory (LANL) hydrothermal process, waste streams are first pressurized and heated as they pass through a continuous flow tubular reactor vessel. The waste is maintained at reaction temperature of 300--550 C where organic destruction and sludge reformation occur. This report documents LANL activities in process modeling and control undertaken in FY94 to support hydrothermal process development. Key issues discussed include non-ideal flow patterns (e.g. axial dispersion) and their effect on reactor performance, the use and interpretation of inert tracer experiments, and the use of computational fluid mechanics to evaluate novel hydrothermal reactor designs. In addition, the effects of axial dispersion (and simplifications to rate expressions) on the estimated kinetic parameters are explored by non-linear regression to experimental data. Safety-related calculations are reported which estimate the explosion limits of effluent gases and the fate of hydrogen as it passes through the reactor. Development and numerical solution of a generalized one-dimensional mathematical model is also summarized. The difficulties encountered in using commercially available software to correlate the behavior of high temperature, high pressure aqueous electrolyte mixtures are summarized. Finally, details of the control system and experiments conducted to empirically determine the system response are reported

Multiple sample setup for testing the hydrothermal stability of adsorbents in thermal energy storage applications

International Nuclear Information System (INIS)

Fischer, Fabian; Laevemann, Eberhard

2015-01-01

Thermal energy storage based on adsorption and desorption of water on an adsorbent can achieve high energy storage densities. Many adsorbents lose adsorption capacity when operated under unfavourable hydrothermal conditions during adsorption and desorption. The stability of an adsorbent against stressing hydrothermal conditions is a key issue for its usability in adsorption thermal energy storage. We built an experimental setup that simultaneously controls the hydrothermal conditions of 16 samples arranged in a matrix of four temperatures and four water vapour pressures. This setup allows the testing of potential adsorbents between temperatures of 50 °C and 350 °C and water vapour pressures of up to 32 kPa. A measurement procedure that allows the detection of the hydrothermal stability of an adsorbent after defined time spans has been designed. We verified the functionality of the multiple sample measurements with a microporous adsorbent, a zeolite NaMSX. The hydrothermal stability of this zeolite is tested by water uptake measurements. A standard deviation lower than 1% of the 16 samples for detecting the hydrothermal stability enables setting different conditions in each sample cell. Further, we compared the water uptake measurements by measuring their adsorption isotherms with the volumetric device BELSORP Aqua 3 from Bel Japan. (paper)

Large Marks-decahedral Pd nanoparticles synthesized by a modified hydrothermal method using a homogeneous reactor

International Nuclear Information System (INIS)

Zhao, Haiqiang; Qi, Weihong; Ji, Wenhai; Wang, Tianran; Peng, Hongcheng; Wang, Qi; Jia, Yanlin; He, Jieting

2017-01-01

Fivefold symmetry appears only in small particles and quasicrystals because internal stress in the particles increases with the particle size. However, a typical Marks decahedron with five re-entrant grooves located at the ends of the twin boundaries can further reduce the strain energy. During hydrothermal synthesis, it is difficult to stir the reaction solution contained in a digestion high-pressure tank because of the relatively small size and high-temperature and high-pressure sealed environment. In this work, we optimized a hydrothermal reaction system by replacing the conventional drying oven with a homogeneous reactor to shift the original static reaction solution into a full mixing state. Large Marks-decahedral Pd nanoparticles (~90 nm) have been successfully synthesized in the optimized hydrothermal synthesis system. Additionally, in the products, round Marks-decahedral Pd particles were also found for the first time. While it remains a challenge to understand the growth mechanism of the fivefold twinned structure, we proposed a plausible growth-mediated mechanism for Marks-decahedral Pd nanoparticles based on observations of the synthesis process.

Large Marks-decahedral Pd nanoparticles synthesized by a modified hydrothermal method using a homogeneous reactor

Energy Technology Data Exchange (ETDEWEB)

Zhao, Haiqiang; Qi, Weihong, E-mail: qiwh216@csu.edu.cn; Ji, Wenhai; Wang, Tianran; Peng, Hongcheng; Wang, Qi; Jia, Yanlin; He, Jieting [Central South University, School of Materials Science and Engineering (China)

2017-05-15

Fivefold symmetry appears only in small particles and quasicrystals because internal stress in the particles increases with the particle size. However, a typical Marks decahedron with five re-entrant grooves located at the ends of the twin boundaries can further reduce the strain energy. During hydrothermal synthesis, it is difficult to stir the reaction solution contained in a digestion high-pressure tank because of the relatively small size and high-temperature and high-pressure sealed environment. In this work, we optimized a hydrothermal reaction system by replacing the conventional drying oven with a homogeneous reactor to shift the original static reaction solution into a full mixing state. Large Marks-decahedral Pd nanoparticles (~90 nm) have been successfully synthesized in the optimized hydrothermal synthesis system. Additionally, in the products, round Marks-decahedral Pd particles were also found for the first time. While it remains a challenge to understand the growth mechanism of the fivefold twinned structure, we proposed a plausible growth-mediated mechanism for Marks-decahedral Pd nanoparticles based on observations of the synthesis process.

Reduction of nitrate and nitrite salts under hydrothermal conditions

International Nuclear Information System (INIS)

Foy, B.R.; Dell'Orco, P.C.; Wilmanns, E.; McInroy, R.; Ely, J.; Robinson, J.M.; Buelow, S.J.

1994-01-01

The feasibility of reducing nitrate/nitrite salts under hydrothermal conditions for the treatment of aqueous mixed wastes stored in the underground tanks at the Department of Energy site at Hanford, Washington was studied. The reduction of nitrate and nitrite salts by reaction with EDTA using a tank waste simulant was examined at temperatures between 623K and 800K and pressures between 0.6 and 1.2 kbar. Continuous flow reactors were used to determine kinetics and products of reactions. All reactions were studied under pressures high enough to produce single phase conditions. The reactions are rapid, go to completion in less than a minute, and produce simple products, such as carbonate, nitrogen, and nitrous oxide gases. The experimental results demonstrate the ability of chemical reactions under hydrothermal conditions to reduce the nitrate and nitrite salts and destroy organic compounds in the waste mixtures

High hydrostatic pressure adaptive strategies in an obligate piezophile Pyrococcus yayanosii

KAUST Repository

Michoud, Gregoire; Jebbar, Mohamed

2016-01-01

Pyrococcus yayanosii CH1, as the first and only obligate piezophilic hyperthermophilic microorganism discovered to date, extends the physical and chemical limits of life on Earth. It was isolated from the Ashadze hydrothermal vent at 4,100 m depth. Multi-omics analyses were performed to study the mechanisms used by the cell to cope with high hydrostatic pressure variations. In silico analyses showed that the P. yayanosii genome is highly adapted to its harsh environment, with a loss of aromatic amino acid biosynthesis pathways and the high constitutive expression of the energy metabolism compared with other non-obligate piezophilic Pyrococcus species. Differential proteomics and transcriptomics analyses identified key hydrostatic pressure-responsive genes involved in translation, chemotaxis, energy metabolism (hydrogenases and formate metabolism) and Clustered Regularly Interspaced Short Palindromic Repeats sequences associated with Cellular apoptosis susceptibility proteins.

High hydrostatic pressure adaptive strategies in an obligate piezophile Pyrococcus yayanosii

KAUST Repository

Michoud, Gregoire

2016-06-02

Pyrococcus yayanosii CH1, as the first and only obligate piezophilic hyperthermophilic microorganism discovered to date, extends the physical and chemical limits of life on Earth. It was isolated from the Ashadze hydrothermal vent at 4,100 m depth. Multi-omics analyses were performed to study the mechanisms used by the cell to cope with high hydrostatic pressure variations. In silico analyses showed that the P. yayanosii genome is highly adapted to its harsh environment, with a loss of aromatic amino acid biosynthesis pathways and the high constitutive expression of the energy metabolism compared with other non-obligate piezophilic Pyrococcus species. Differential proteomics and transcriptomics analyses identified key hydrostatic pressure-responsive genes involved in translation, chemotaxis, energy metabolism (hydrogenases and formate metabolism) and Clustered Regularly Interspaced Short Palindromic Repeats sequences associated with Cellular apoptosis susceptibility proteins.

High hydrostatic pressure adaptive strategies in an obligate piezophile Pyrococcus yayanosii

Science.gov (United States)

Michoud, Grégoire; Jebbar, Mohamed

2016-01-01

Pyrococcus yayanosii CH1, as the first and only obligate piezophilic hyperthermophilic microorganism discovered to date, extends the physical and chemical limits of life on Earth. It was isolated from the Ashadze hydrothermal vent at 4,100 m depth. Multi-omics analyses were performed to study the mechanisms used by the cell to cope with high hydrostatic pressure variations. In silico analyses showed that the P. yayanosii genome is highly adapted to its harsh environment, with a loss of aromatic amino acid biosynthesis pathways and the high constitutive expression of the energy metabolism compared with other non-obligate piezophilic Pyrococcus species. Differential proteomics and transcriptomics analyses identified key hydrostatic pressure-responsive genes involved in translation, chemotaxis, energy metabolism (hydrogenases and formate metabolism) and Clustered Regularly Interspaced Short Palindromic Repeats sequences associated with Cellular apoptosis susceptibility proteins. PMID:27250364

Vein networks in hydrothermal systems provide constraints for the monitoring of active volcanoes.

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Cucci, Luigi; Di Luccio, Francesca; Esposito, Alessandra; Ventura, Guido

2017-03-10

Vein networks affect the hydrothermal systems of many volcanoes, and variations in their arrangement may precede hydrothermal and volcanic eruptions. However, the long-term evolution of vein networks is often unknown because data are lacking. We analyze two gypsum-filled vein networks affecting the hydrothermal field of the active Lipari volcanic Island (Italy) to reconstruct the dynamics of the hydrothermal processes. The older network (E1) consists of sub-vertical, N-S striking veins; the younger network (E2) consists of veins without a preferred strike and dip. E2 veins have larger aperture/length, fracture density, dilatancy, and finite extension than E1. The fluid overpressure of E2 is larger than that of E1 veins, whereas the hydraulic conductance is lower. The larger number of fracture intersections in E2 slows down the fluid movement, and favors fluid interference effects and pressurization. Depths of the E1 and E2 hydrothermal sources are 0.8 km and 4.6 km, respectively. The decrease in the fluid flux, depth of the hydrothermal source, and the pressurization increase in E2 are likely associated to a magma reservoir. The decrease of fluid discharge in hydrothermal fields may reflect pressurization at depth potentially preceding hydrothermal explosions. This has significant implications for the long-term monitoring strategy of volcanoes.

Multi-year high-frequency hydrothermal monitoring of selected high-threat Cascade Range volcanoes

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Crankshaw, I. M.; Archfield, S. A.; Newman, A. C.; Bergfeld, D.; Clor, L. E.; Spicer, K. R.; Kelly, P. J.; Evans, W. C.; Ingebritsen, S. E.

2018-05-01

From 2009 to 2015 the U.S. Geological Survey (USGS) systematically monitored hydrothermal behavior at selected Cascade Range volcanoes in order to define baseline hydrothermal and geochemical conditions. Gas and water data were collected regularly at 25 sites on 10 of the highest-risk volcanoes in the Cascade Range. These sites include near-summit fumarole groups and springs/streams that show clear evidence of magmatic influence (high 3He/4He ratios and/or large fluxes of magmatic CO2 or heat). Site records consist mainly of hourly temperature and hydrothermal-flux data. Having established baseline conditions during a multiyear quiescent period, the USGS reduced monitoring frequency from 2015 to present. The archived monitoring data are housed at (doi:10.5066/F72N5088). These data (1) are suitable for retrospective comparison with other continuous geophysical monitoring data and (2) will provide context during future episodes of volcanic unrest, such that unrest-related variations at these thoroughly characterized sites will be more clearly recognizable. Relatively high-frequency year-round data are essential to achieve these objectives, because many of the time series reveal significant diurnal, seasonal, and inter-annual variability that would tend to mask unrest signals in the absence of baseline data. Here we characterize normal variability for each site, suggest strategies to detect future volcanic unrest, and explore deviations from background associated with recent unrest.

Hydrothermal solid-gas route to TiO2 nanoparticles/nanotube arrays for high-performance supercapacitors

Science.gov (United States)

Fan, Haowen; Zhang, He; Luo, Xiaolei; Liao, Maoying; Zhu, Xufei; Ma, Jing; Song, Ye

2017-07-01

Although TiO2 nanotube arrays (TNTAs) have shown great promise as supercapacitor materials, their specific capacitances are still not comparable with some typical materials. Here, TiO2 nanoparticles (NPs)/TNTAs hybrid structure has been derived from the anodized TNTAs by a facile hydrothermal solid-gas method (HSGM), which can avoid cracking or curling of the TNTAs from Ti substrate. The obtained NPs/TNTAs hybrid structure can exhibit a ∼4.90 times increase in surface area and a ∼5.49 times increase in areal specific capacitance compared to the TNTAs without HSGM treatment. Besides, the argon-atmosphere annealing can offer improved areal capacitance and cycling stability relative to the air-atmosphere annealing. The hydrothermal vapor pressure is a key factor for controlling microscopic morphologies of TNTAs, the morphology transformations of TNTAs during the HSGM treatment can be accelerated under enhanced vapor pressures. The highest areal capacitance of HSGM-treated TNTAs is up to 76.12 mF cm-2 at 0.5 mA cm-2, well above that of any TiO2 materials reported to date.

Hydrothermal simulation experiments as a tool for studies of the origin of life on Earth and other terrestrial planets: a review.

Science.gov (United States)

Holm, Nils G; Andersson, Eva

2005-08-01

The potential of life's origin in submarine hydrothermal systems has been evaluated by a number of investigators by conducting high temperature-high pressure experiments involving organic compounds. In the majority of these experiments little attention has been paid to the importance of constraining important parameters, such as the pH and the redox state of the system. This is particularly revealed in the apparent difficulties in interpreting experimental data from hydrothermal organic synthesis and stability studies. However, in those cases where common mineral assemblages have been used in an attempt to buffer the pH and redox conditions to geologically and geochemically realistic values, theoretical and experimental data seem to converge. The use of mineral buffer assemblages provides a convenient way by which to constrain the experimental conditions. Studies at high temperatures and pressure in the laboratory have revealed a number of reactions that proceed rapidly in hydrothermal fluids, including the Strecker synthesis of amino acids. In other cases, the verification of postulated abiotic reaction mechanisms has not been possible, at least for large molecules such as large fatty acids and hydrocarbons. This includes the Fischer-Tropsch synthesis reaction. High temperature-high pressure experimental methods have been developed and used successfully for a long time in, for example, mineral solubility studies under hydrothermal conditions. By taking advantage of this experimental experience new and, at times, unexpected directions can be taken in bioorganic geochemistry, one being, for instance, primitive two-dimensional information coding. This article critically reviews some of the organic synthesis and stability experiments that have been conducted under simulated submarine hydrothermal conditions. We also discuss some of the theoretical and practical considerations that apply to hydrothermal laboratory studies of organic molecules related to the origin of

Raman spectroscopic study of calcite III to aragonite transformation under high pressure and high temperature

Science.gov (United States)

Liu, Chuanjiang; Zheng, Haifei; Wang, Duojun

2017-10-01

In our study, a series of Raman experiments on the phase transition of calcite at high pressure and high temperature were investigated using a hydrothermal diamond anvil cell and Raman spectroscopy technique. It was found that calcite I transformed to calcite II and calcite III at pressures of 1.62 and 2.12 GPa and room temperature. With increasing temperature, the phase transition of calcite III to aragonite occurred. Aragonite was retained upon slowly cooling of the system, indicating that the transition of calcite III to aragonite was irreversible. Based on the available data, the phase boundary between calcite III and aragonite was determined by the following relation: P(GPa) = 0.013 × T(°C) + 1.22 (100°C ≤ T ≤ 170°C). It showed that the transition pressure linearly rose with increasing temperature. A better understanding of the stability of calcite III and aragonite is of great importance to further explore the thermodynamic behavior of carbonates and carbon cycling in the mantle.

Seawater bicarbonate removal during hydrothermal circulation

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Proskurowski, G. K.; Seewald, J.; Sylva, S. P.; Reeves, E.; Lilley, M. D.

2013-12-01

High temperature fluids sampled at hydrothermal vents represent a complex alteration product of water-rock reactions on a multi-component mixture of source fluids. Sources to high-temperature hydrothermal samples include the 'original' seawater present in the recharge limb of circulation, magmatically influenced fluids added at depth as well as any seawater entrained during sampling. High-temperature hydrothermal fluids are typically enriched in magmatic volatiles, with CO2 the dominant species, characterized by concentrations of 10's-100's of mmol/kg (1, 2). Typically, the high concentration of CO2 relative to background seawater bicarbonate concentrations (~2.3 mmol/kg) obscures a full analysis of the fate of seawater bicarbonate during high-temperature hydrothermal circulation. Here we present data from a suite of samples collected over the past 15 years from high-temperature hydrothermal vents at 9N, Endeavour, Lau Basin, and the MAR that have endmember CO2 concentrations less than 10 mmol/kg. Using stable and radiocarbon isotope measurements these samples provide a unique opportunity to examine the balance between 'original' seawater bicarbonate and CO2 added from magmatic sources. Multiple lines of evidence from multiple hydrothermal settings consistently points to the removal of ~80% of the 'original' 2.3 mmol/kg seawater bicarbonate. Assuming that this removal occurs in the low-temperature, 'recharge' limb of hydrothermal circulation, this removal process is widely occurring and has important contributions to the global carbon cycle over geologic time. 1. Lilley MD, Butterfield DA, Lupton JE, & Olson EJ (2003) Magmatic events can produce rapid changes in hydrothermal vent chemistry. Nature 422(6934):878-881. 2. Seewald J, Cruse A, & Saccocia P (2003) Aqueous volatiles in hydrothermal fluids from the Main Endeavour Field, northern Juan de Fuca Ridge: temporal variability following earthquake activity. Earth and Planetary Science Letters 216(4):575-590.

Dynamics of the Yellowstone hydrothermal system

Science.gov (United States)

Hurwitz, Shaul; Lowenstern, Jacob B.

2014-01-01

The Yellowstone Plateau Volcanic Field is characterized by extensive seismicity, episodes of uplift and subsidence, and a hydrothermal system that comprises more than 10,000 thermal features, including geysers, fumaroles, mud pots, thermal springs, and hydrothermal explosion craters. The diverse chemical and isotopic compositions of waters and gases derive from mantle, crustal, and meteoric sources and extensive water-gas-rock interaction at variable pressures and temperatures. The thermal features are host to all domains of life that utilize diverse inorganic sources of energy for metabolism. The unique and exceptional features of the hydrothermal system have attracted numerous researchers to Yellowstone beginning with the Washburn and Hayden expeditions in the 1870s. Since a seminal review published a quarter of a century ago, research in many fields has greatly advanced our understanding of the many coupled processes operating in and on the hydrothermal system. Specific advances include more refined geophysical images of the magmatic system, better constraints on the time scale of magmatic processes, characterization of fluid sources and water-rock interactions, quantitative estimates of heat and magmatic volatile fluxes, discovering and quantifying the role of thermophile microorganisms in the geochemical cycle, defining the chronology of hydrothermal explosions and their relation to glacial cycles, defining possible links between hydrothermal activity, deformation, and seismicity; quantifying geyser dynamics; and the discovery of extensive hydrothermal activity in Yellowstone Lake. Discussion of these many advances forms the basis of this review.

Hydrothermal Processes

Science.gov (United States)

German, C. R.; von Damm, K. L.

2003-12-01

(after C. A. Stein and S. Stein, 1994). The first geochemical evidence for the existence of hydrothermal vents on the ocean floor came in the mid-1960s when investigations in the Red Sea revealed deep basins filled with hot, salty water (40-60 °C) and underlain by thick layers of metal-rich sediment (Degens and Ross, 1969). Because the Red Sea represents a young, rifting, ocean basin it was speculated that the phenomena observed there might also prevail along other young MOR spreading centers. An analysis of core-top sediments from throughout the world's oceans ( Figure 2) revealed that such metalliferous sediments did, indeed, appear to be concentrated along the newly recognized global ridge crest (Boström et al., 1969). Another early indication of hydrothermal activity came from the detection of plumes of excess 3He in the Pacific Ocean Basin (Clarke et al., 1969) - notably the >2,000 km wide section in the South Pacific ( Lupton and Craig, 1981) - because 3He present in the deep ocean could only be sourced through some form of active degassing of the Earth's interior, at the seafloor. (62K)Figure 2. Global map of the (Al+Fe+Mn):Al ratio for surficial marine sediments. Highest ratios mimic the trend of the global MOR axis (after Boström et al., 1969). One area where early heat-flow studies suggested hydrothermal activity was likely to occur was along the Galapagos Spreading Center in the eastern equatorial Pacific Ocean (Anderson and Hobart, 1976). In 1977, scientists diving at this location found hydrothermal fluids discharging chemically altered seawater from young volcanic seafloor at elevated temperatures up to 17 °C ( Edmond et al., 1979). Two years later, the first high-temperature (380±30 °C) vent fluids were found at 21° N on the East Pacific Rise (EPR) (Spiess et al., 1980) - with fluid compositions remarkably close to those predicted from the lower-temperature Galapagos findings ( Edmond et al., 1979). Since that time, hydrothermal activity has been

Quantitative characterization of the aqueous fraction from hydrothermal liquefaction of algae

Energy Technology Data Exchange (ETDEWEB)

Maddi, Balakrishna; Panisko, Ellen; Wietsma, Thomas; Lemmon, Teresa; Swita, Marie; Albrecht, Karl; Howe, Daniel

2016-10-01

Aqueous streams generated from hydrothermal liquefaction contain approximately 30% of the total carbon present from the algal feed. Hence, this aqueous carbon must be utilized to produce liquid fuels and/or specialty chemicals for economic sustainability of hydrothermal liquefaction on industrial scale. In this study, aqueous fractions produced from the hydrothermal liquefaction of fresh water and saline water algal cultures were analyzed using a wide variety of analytical instruments to determine their compositional characteristics. This study will also inform researchers designing catalysts for down-stream processing such as high-pressure catalytic conversion of organics in aqueous phase, catalytic hydrothermal gasification, and biological conversions. Organic chemical compounds present in all eight aqueous fractions were identified using two-dimensional gas chromatography equipped with time-of-flight mass spectrometry. Identified compounds include organic acids, nitrogen compounds and aldehydes/ketones. Conventional gas chromatography and liquid chromatography methods were utilized to quantify the identified compounds. Inorganic species in the aqueous stream of hydrothermal liquefaction of algae were identified using ion chromatography and inductively coupled plasma optical emission spectrometer. The concentrations of organic chemical compounds and inorganic species are reported. The amount quantified carbon ranged from 45 to 72 % of total carbon in the aqueous fractions.

The Anvils as Pressure Calibrants in the Hydrothermal Diamond Anvil Cell

Science.gov (United States)

Davis, M. K.; Panero, W. R.; Stixrude, L. P.

2003-12-01

Throughout the crust and the upper part of the mantle, water is an important agent of heat and mass transport in processes ranging from metasomatism to magma generation in arc environments. One of the important properties of water in this regime: its ability to dissolve significant amounts of solids, presents a substantial challenge to the experimental study of water-rich systems. Many commonly used pressure standards, such as quartz and ruby, dissolve in water under the conditions accessible to the hydrothermal diamond anvil cell (up to 1200 K and 5 GPa). For this reason, it is important to develop alternative pressure calibrants. Two methods have been developed by other groups for pressure calibration in the HDAC in the presence of water. One method relies on the equation of state of the ambient fluid and the observation that the sample chamber remains approximately isochoric on heating. Disadvantages of this method include our imperfect knowledge of the equation of state of water over the relevant pressure-temperature interval, possible changes in fluid composition, and sample chamber assembly relaxation at temperatures above 800 K. The second method is based on the Raman signal from diamond chips loaded with the sample. Synthetic 13C diamond is used to avoid overlap with the much stronger signal from the anvils. Diamond is an ideal pressure sensor since it is chemically inert and unaffected by water. Therefore, we use the tips of the diamond anvils as "internal" sensors. The primary disadvantage of this method is that the stress distribution inside the anvils is non-hydrostatic and inhomogeneous, although the normal stress across the diamond-sample interface must be continuous. Using confocal micro-Raman spectroscopy we are able to characterize both the inhomogeneity and the non-hydrostaticity of the diamond stress field by combining axial and radial transects with peak shapes. We find that on room temperature loading there is substantial inhomogeneity in the

Temperature and pressure gas geoindicators at the Solfatara fumaroles (Campi Flegrei

Directory of Open Access Journals (Sweden)

Carmine Minopoli

2011-06-01

Full Text Available Long time series of fluid pressure and temperature within a hydrothermal system feeding the Solfatara fumaroles are investigated here, on the basis of the chemical equilibria within the CO2–H2O–H2–CO gas system. The Pisciarelli fumarole external to Solfatara crater shows an annual cycle of CO contents that indicates the occurrence of shallow secondary processes that mask the deep signals. In contrast, the Bocca Grande and Bocca Nova fumaroles located inside Solfatara crater do not show evidence of secondary processes, and their compositional variations are linked to the temperature–pressure changes within the hydrothermal system. The agreement between geochemical signals and the ground movements of the area (bradyseismic phenomena suggests a direct relationship between the pressurization process and the ground uplift. Since 2007, the gas geoindicators have indicated pressurization of the system, which is most probably caused by the arrival of deep gases with high CO2 contents in the shallow parts of the hydrothermal system. This pressurization process causes critical conditions in the hydrothermal system, as highlighted by the increase in the fumarole temperature, the opening of new vents, and the localized seismic activity. If the pressurization process continues with time, it is not possible to rule out the occurrence of phreatic explosions.

Highly hydrothermally stable microporous silica membranes for hydrogen separation.

Science.gov (United States)

Wei, Qi; Wang, Fei; Nie, Zuo-Ren; Song, Chun-Lin; Wang, Yan-Li; Li, Qun-Yan

2008-08-07

Fluorocarbon-modified silica membranes were deposited on gamma-Al2O3/alpha-Al2O3 supports by the sol-gel technique for hydrogen separation. The hydrophobic property, pore structure, gas transport and separation performance, and hydrothermal stability of the modified membranes were investigated. It is observed that the water contact angle increases from 27.2+/-1.5 degrees for the pure silica membranes to 115.0+/-1.2 degrees for the modified ones with a (trifluoropropyl)triethoxysilane (TFPTES)/tetraethyl orthosilicate (TEOS) molar ratio of 0.6. The modified membranes preserve a microporous structure with a micropore volume of 0.14 cm3/g and a pore size of approximately 0.5 nm. A single gas permeation of H2 and CO2 through the modified membranes presents small positive apparent thermal activation energies, indicating a dominant microporous membrane transport. At 200 degrees C, a single H2 permeance of 3.1x10(-6) mol m(-2) s(-1) Pa(-1) and a H2/CO2 permselectivity of 15.2 were obtained after proper correction for the support resistance and the contribution from the defects. In the gas mixture measurement, the H2 permeance and the H2/CO2 separation factor almost remain constant at 200 degrees C with a water vapor pressure of 1.2x10(4) Pa for at least 220 h, indicating that the modified membranes are hydrothermally stable, benefiting from the integrity of the microporous structure due to the fluorocarbon modification.

Hydrothermal gasification of glucose and starch in a batch and continuous reactor

Directory of Open Access Journals (Sweden)

Kazuhiro Kumabe

2017-11-01

Full Text Available A batch reactor was used for the gasification of glucose and starch as carbohydrate model compounds. The effects of H2O in various states (low-pressure hot compressed water (LP-HCW, 300 °C and 10 MPa, high-pressure hot compressed water (HP-HCW, 360 °C and 20 MPa, high-temperature steam (HTS, 400 °C and 10 MPa, and supercritical water (SCW, 400 °C and 25 MPa, as well as reaction time (10, 30, and 60 min, sample concentration (10, 20, and 30 wt%, and catalyst (mixture of Ca(OH2 and Na2CO3 on gas production were investigated in the hydrothermal gasification. In addition, using a continuous reactor, the hydrothermal gasification of glucose was examined with LP-HCW (200 °C and 5 MPa, HP-HCW (200 °C and 25 MPa, HTS (600 °C, 5 MPa, and SCW (600 °C, 25 MPa in order to study the productions of gases and tar, and the mass balance. The reaction temperature affected gasification considerably, but pressure had little effect. In the batch experiments, the characteristics of the produced gases were almost identical after a reaction time of 10 min, and addition of Ca(OH2 and Na2CO3 as catalysts in a molar ratio of 7:3 led to selective production of H2 in the SCW gasification of 10 wt% glucose for 30 min. In a continuous experiment under the SCW conditions, the conversion efficiency of glucose to gas was 26% and the composition of the produced gas was 29 vol% CO, 23 vol% H2, and 16 vol% CH4. Under the hydrothermal conditions, glucose was mainly converted to char and suspended components of high-molecular-weight compounds such as fat, whereas starch was mainly converted to gas and liquid.

Synchrotron x-ray spectroscopy of EuHN O3 aqueous solutions at high temperatures and pressures and Nb-bearing silicate melt phases coexisting with hydrothermal fluids using a modified hydrothermal diamond anvil cell and rail assembly

Science.gov (United States)

Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

2007-01-01

A modified hydrothermal diamond anvil cell (HDAC) rail assembly has been constructed for making synchrotron x-ray absorption spectroscopy, x-ray fluorescence, and x-ray mapping measurements on fluids or solid phases in contact with hydrothermal fluids up to ???900??C and 700 MPa. The diamond anvils of the HDAC are modified by laser milling grooves or holes, for the reduction of attenuation of incident and fluorescent x rays and sample cavities. The modified HDAC rail assembly has flexibility in design for measurement of light elements at low concentrations or heavy elements at trace levels in the sample and the capability to probe minute individual phases of a multiphase fluid-based system using focused x-ray microbeam. The supporting rail allows for uniform translation of the HDAC, rotation and tilt stages, and a focusing mirror, which is used to illuminate the sample for visual observation using a microscope, relative to the direction of the incident x-ray beam. A structure study of Eu(III) aqua ion behavior in high-temperature aqueous solutions and a study of Nb partitioning and coordination in a silicate melt in contact with a hydrothermal fluid are described as applications utilizing the modified HDAC rail assembly. ?? 2007 American Institute of Physics.

Hydrothermal synthesis of sodium titanate nanotubes; Hydrotermalna synteza nanorurok titanatu sodneho

Energy Technology Data Exchange (ETDEWEB)

Miskoci, M.; Jesenak, K. [Univerzita Komenskeho, Prirodovedecka fakulta, Katedra anorganickej chemie, 84215 Bratislava (Slovakia); Caplovicova, M. [Univerzita Komenskeho, Prirodovedecka fakulta, Katedra loziskovej geologie, 84215 Bratislava (Slovakia)

2013-04-16

From suspension of nanoparticles TiO{sub 2} in concentrated water solution of NaOH were prepared by hydrothermal synthesis sodium titanates particles with different shapes. Influence of synthesis duration under temperature 180 grad C on the change of particles shapes was observed. The result of experiment showed that one day synthesis resulted to obtained product with high content of nanotubes, but the extension of this period led to the transformation of product's shape into stripes. From the results of experiment follows that as a precursor for TiO{sub 2} nanotubes preparation may be used only products of hydrothermal synthesis, which duration of pressure synthesis was not longer than 24 hours. (authors)

Study on the hydrothermal treatment of Shenhua coal

Energy Technology Data Exchange (ETDEWEB)

Zhicai Wang; Hengfu Shui; Zhanning Pei; Jinsheng Gao [Anhui University of Technology, Ma' anshan (China). School of Chemistry and Chemical Engineering

2008-04-15

In this paper, the hydrothermal treatment of Shenhua coal was carried out under 0.1 MPa (initial pressure) nitrogen and different temperature. Effects of hydrothermal treatment on the structure and the hydro-liquefaction activity of Shenhua coal were investigated by the ultimate and proximate analyses, the FTIR measurements and TG analyses of hydrothermally treated coals, and the characterizations of extraction and swelling properties, and the batch hydro-liquefaction of treated coal were also carried out. The results indicate that hydrothermal treatment above 200{sup o}C can increase the hydrogen content of treated coal and decrease the yield of volatiles and the content of ash, especially a large amount of CO and CH{sub 4} are found in gas products obtained by the hydrothermal treatment above 250{sup o}C. Hydrothermal treatment disrupts the weak covalent bond such as ether, ester and side-chain substituent by hydrolysis and pyrolysis, and changes the distribution of H-bond in coal. The swelling ratio and the Soxhlet extraction yield of treated coal decrease with the increase of hydrothermal treatment temperature. The conversion of liquefaction and the yield of CS{sub 2}/NMP mixed solvent extraction at ambient temperature are enhanced by hydrothermal treatment at 300{sup o}C. Therefore hydrogen donation reactions and the rupture of non-covalent bond and weak covalent bonds present in the process of hydrothermal treatment resulting in the changes of structure and reactivity of Shenhua coal. The results show that the hydro-liquefaction activity of Shenhua coal can be improved by hydrothermal pretreatment between 250{sup o}C and 300{sup o}C. 15 refs., 5 figs., 4 tabs.

Measurement of the thermal diffusivity and speed of sound of hydrothermal solutions via the laser-induced grating technique

International Nuclear Information System (INIS)

Butenhoff, T.J.

1994-01-01

Hydrothermal processing is being developed as a method for organic destruction for the Hanford Site in Washington. Hydrothermal processing refers to the redox reactions of chemical compounds in supercritical or near-supercritical aqueous solutions. In order to design reactors for the hydrothermal treatment of complicated mixtures found in the Hanford wastes, engineers need to know the thermophysical properties of the solutions under hydrothermal conditions. The author used the laser-induced grating technique to measure the thermal diffusivity and speed of sound of hydrothermal solutions. In this non-invasive optical technique, a transient grating is produced in the hydrothermal solution by optical absorption from two crossed time-coincident nanosecond laser pulses. The grating is probed by measuring the diffraction efficiency of a third laser beam. The grating relaxes via thermal diffusion, and the thermal diffusivity can be determined by measuring the decay of the grating diffraction efficiency as a function of the pump-probe delay time. In addition, intense pump pulses produce counterpropagating acoustic waves that appear as large undulations in the transient grating decay spectrum. The speed of sound in the sample is simply the grating fringe spacing divided by the undulation period. The cell is made from a commercial high pressure fitting and is equipped with two diamond windows for optical access. Results are presented for dilute dye/water solutions with T = 400 C and pressures between 20 and 70 MPa

Biological phosphate removal using a degradable carbon source produced by hydrothermal treatment of excess sludge

Directory of Open Access Journals (Sweden)

L. H. Haraguchi

2006-03-01

Full Text Available The possibility of reusing excess sludge treated by hydrothermal reaction for the purpose of improving the efficiency of the enhanced biological phosphate removal (EBPR process was investigated. Excess sludge from a fish-processing industry located in Japan was treated in high-temperature and high-pressure water, at a reaction temperature ranging from 200 to 400ºC, a pressure of 1.8 to 30MPa and a constant reaction time of 7 min. For the conditions tested, the results showed that when the reaction temperature was increased the content of readily biodegradable substrate in the total COD Cr increased. In addition, the amount of some volatile fatty acids (VFAs produced by the hydrothermal reaction increased as reaction temperature increased. From the phosphate release tests under anaerobic conditions, it was possible to demonstrate that not only the VFAs, but also the readily and slowly biodegradable substrates are used as potential carbon source by the phosphate-accumulating organisms (PAOs.

Factors influencing formation of highly dispersed BaTiO3 nanospheres with uniform sizes in static hydrothermal synthesis

International Nuclear Information System (INIS)

Gao, Jiabing; Shi, Haiyue; Dong, Huina; Zhang, Rui; Chen, Deliang

2015-01-01

Highly dispersed BaTiO 3 nanospheres with uniform sizes have important applications in micro/nanoscale functional devices. To achieve well-dispersed spherical BaTiO 3 nanocrystals, we carried out as reported in this paper the systematic investigation on the factors that influence the formation of BaTiO 3 nanospheres by the static hydrothermal process, including the NaOH concentrations [NaOH], molar Ba/Ti ratios (R Ba/Ti ), hydrothermal temperatures, and durations, with an emphasis on understanding the related mechanisms. Barium nitrate and TiO 2 sols derived from tetrabutyl titanate were used as the starting materials. The as-synthesized BaTiO 3 samples were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, thermogravimetry, differential thermal analysis, and FT-IR spectra. The highly dispersed BaTiO 3 nanospheres (76 ± 13 nm) were achieved under the optimum hydrothermal conditions at 200 °C for 10 h: [NaOH] = 2.0 mol L −1 and R Ba/Ti  = 1.5. Higher NaOH concentrations, higher Ba/Ti ratios, higher hydrothermal temperatures, and longer hydrothermal durations are favorable in forming BaTiO 3 nanospheres with larger fractions of tetragonal phase and higher yields; but too long hydrothermal durations resulted in abnormal growth and reduced the uniformity in particle sizes. The possible formation mechanisms for BaTiO 3 nanocrystals under the static hydrothermal conditions were investigated

The Interplay Between Saline Fluid Flow and Dynamic Permeability in Magmatic-Hydrothermal Systems

Science.gov (United States)

Weis, P.

2014-12-01

Magmatic-hydrothermal ore deposits document the interplay between saline fluid flow and rock permeability. Numerical simulations of multi-phase flow of variably miscible, compressible H20-NaCl fluids in concert with a dynamic permeability model can reproduce characteristics of porphyry copper and epithermal gold systems. This dynamic permeability model incorporates depth-dependent permeability profiles characteristic for tectonically active crust as well as pressure- and temperature-dependent relationships describing hydraulic fracturing and the transition from brittle to ductile rock behavior. In response to focused expulsion of magmatic fluids from a crystallizing upper crustal magma chamber, the hydrothermal system self-organizes into a hydrological divide, separating an inner part dominated by ascending magmatic fluids under near-lithostatic pressures from a surrounding outer part dominated by convection of colder meteoric fluids under near-hydrostatic pressures. This hydrological divide also provides a mechanism to transport magmatic salt through the crust, and prevents the hydrothermal system to become "clogged" by precipitation of solid halite due to depressurization of saline, high-temperature magmatic fluids. The same physical processes at similar permeability ranges, crustal depths and flow rates are relevant for a number of active systems, including geothermal resources and excess degassing at volcanos. The simulations further suggest that the described mechanism can separate the base of free convection in high-enthalpy geothermal systems from the magma chamber as a driving heat source by several kilometers in the vertical direction in tectonic settings with hydrous magmatism. This hydrology would be in contrast to settings with anhydrous magmatism, where the base of the geothermal systems may be closer to the magma chamber.

Borehole plugging by hydrothermal transport. A feasibility report

International Nuclear Information System (INIS)

Roy, D.M.; White, W.B.

1975-01-01

The possibility of forming borehole plugs by hydrothermal transport was examined with respect to five systems, utilizing available literature data. In general, it would appear possible to create plugs with hydrothermal cements, with hydrothermally transported quartz, and with carbonates precipitated in-situ using carbon dioxide or carbon dioxide and water as reacting fluids. Hydrothermal cements appear to be most feasible from an engineering and economic point of view using a slurry with a lime-alumina-silica composition carried into the hole in a single pipe at temperatures in the range of 200 0 C and requiring only enough pressure to drive the mixture into the hole. Quartz or chalcedony plugs would be the most impervious, have the lowest chemical reactivity with groundwater, the lowest thermal expansion, and be most compatible with the wall rock. Deposition is likely to be slow, and there are severe engineering problems associated with a single pipe system carrying silica-rich solutions at temperatures in excess of 500 0 C at pressure of 2000 bars (30,000 psi). Calcite plugs could be formed as compatible plug materials in contact with a limestone or dolomite wall rock. It is not known whether non-porous plugs can be readily formed and there is also a problem of chemical reaction with percolating groundwater. The clay-water and sulfur-water systems do not appear to be viable plug systems. In-situ reconstitution of the wall rock does not appear to be an economically feasible possibility

Radiogeochemical features of hydrothermal metasomatic formations

International Nuclear Information System (INIS)

Plyushchev, E.V.; Ryabova, L.A.; Shatov, V.V.

1978-01-01

Considered are the most general peculiarities of uranium and thorium distributions in hydrothermal-metasomatic formations of three levels of substance formation: 1) in hydrothermal minerals; 2) in natural associations of these minerals (in the altered rocks, metasomatites, ores, etc.); 3) ordened series of zonally and in stage conjugated hydrothermal-metasomatic formations. Statistically stable recurrence of natural combinations of hydrothermal-metasomatic formations points out conjugation of their formation in the directed evolution in the general hydrothermal process. Series of metasomatic formations, the initial members of which are potassium metasomatites, mostly result in accumulation up to industrial concentrations of radioactive elements in final members of these formations. Development of midlow-temperature propylitic alterations in highly radiative rocks causes the same accumulation

Hydrothermal synthetic strategies of inorganic semiconducting nanostructures.

Science.gov (United States)

Shi, Weidong; Song, Shuyan; Zhang, Hongjie

2013-07-07

Because of their unique chemical and physical properties, inorganic semiconducting nanostructures have gradually played a pivotal role in a variety of research fields, including electronics, chemical reactivity, energy conversion, and optics. A major feature of these nanostructures is the quantum confinement effect, which strongly depends on their size, shape, crystal structure and polydispersity. Among all developed synthetic methods, the hydrothermal method based on a water system has attracted more and more attention because of its outstanding advantages, such as high yield, simple manipulation, easy control, uniform products, lower air pollution, low energy consumption and so on. Precise control over the hydrothermal synthetic conditions is a key to the success of the preparation of high-quality inorganic semiconducting nanostructures. In this review, only the representative hydrothermal synthetic strategies of inorganic semiconducting nanostructures are selected and discussed. We will introduce the four types of strategies based on exterior reaction system adjustment, namely organic additive- and template-free hydrothermal synthesis, organic additive-assisted hydrothermal synthesis, template-assisted hydrothermal synthesis and substrate-assisted hydrothermal synthesis. In addition, the two strategies based on exterior reaction environment adjustment, including microwave-assisted and magnetic field-assisted hydrothermal synthesis, will be also described. Finally, we conclude and give the future prospects of this research area.

Geothermic analysis of high temperature hydrothermal activities area in Western plateau of Sichuan province, China

Science.gov (United States)

Zhang, J.

2016-12-01

There is a high temperature hydrothermal activity area in the western plateau of Sichuan. More than 200 hot springs points have been found in the region, including 11 hot spring water temperature above local boiling point. Most of these distribute along Jinshajjiang fracture, Dege-Xiangcheng fracture, Ganzi-Litang fracture as well as Xianshuihe fracture, and form three high-temperature hydrothermal activity strips in the NW-SE direction. Using gravity, magnetic, seismic and helium isotope data, this paper analyzed the crust-mantle heat flow structure, crustal heat source distribution and water heating system. The results show that the geothermal activity mainly controlled by the "hot" crust. The ratio of crustal heat flow and surface heat flow is higher than 60%. In the high temperature hydrothermal activities area, there is lower S wave velocity zone with VsGeothermal water mainly reserve in the Triassic strata of the containing water good carbonate rocks, and in the intrusive granite which is along the fault zone. The thermal energy of Surface heat thermal activities mainly comes from the high-temperature hot source which is located in the middle and lower crust. Being in the deep crustal fracture, the groundwater infiltrated to the deep crust and absorbed heat, then, quickly got back to the surface and formed high hot springs.

Extreme hydrothermal conditions at an active plate-bounding fault

Science.gov (United States)

Sutherland, Rupert; Townend, John; Toy, Virginia; Upton, Phaedra; Coussens, Jamie; Allen, Michael; Baratin, Laura-May; Barth, Nicolas; Becroft, Leeza; Boese, Carolin; Boles, Austin; Boulton, Carolyn; Broderick, Neil G. R.; Janku-Capova, Lucie; Carpenter, Brett M.; Célérier, Bernard; Chamberlain, Calum; Cooper, Alan; Coutts, Ashley; Cox, Simon; Craw, Lisa; Doan, Mai-Linh; Eccles, Jennifer; Faulkner, Dan; Grieve, Jason; Grochowski, Julia; Gulley, Anton; Hartog, Arthur; Howarth, Jamie; Jacobs, Katrina; Jeppson, Tamara; Kato, Naoki; Keys, Steven; Kirilova, Martina; Kometani, Yusuke; Langridge, Rob; Lin, Weiren; Little, Timothy; Lukacs, Adrienn; Mallyon, Deirdre; Mariani, Elisabetta; Massiot, Cécile; Mathewson, Loren; Melosh, Ben; Menzies, Catriona; Moore, Jo; Morales, Luiz; Morgan, Chance; Mori, Hiroshi; Niemeijer, Andre; Nishikawa, Osamu; Prior, David; Sauer, Katrina; Savage, Martha; Schleicher, Anja; Schmitt, Douglas R.; Shigematsu, Norio; Taylor-Offord, Sam; Teagle, Damon; Tobin, Harold; Valdez, Robert; Weaver, Konrad; Wiersberg, Thomas; Williams, Jack; Woodman, Nick; Zimmer, Martin

2017-06-01

Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.

Extreme hydrothermal conditions at an active plate-bounding fault.

Science.gov (United States)

Sutherland, Rupert; Townend, John; Toy, Virginia; Upton, Phaedra; Coussens, Jamie; Allen, Michael; Baratin, Laura-May; Barth, Nicolas; Becroft, Leeza; Boese, Carolin; Boles, Austin; Boulton, Carolyn; Broderick, Neil G R; Janku-Capova, Lucie; Carpenter, Brett M; Célérier, Bernard; Chamberlain, Calum; Cooper, Alan; Coutts, Ashley; Cox, Simon; Craw, Lisa; Doan, Mai-Linh; Eccles, Jennifer; Faulkner, Dan; Grieve, Jason; Grochowski, Julia; Gulley, Anton; Hartog, Arthur; Howarth, Jamie; Jacobs, Katrina; Jeppson, Tamara; Kato, Naoki; Keys, Steven; Kirilova, Martina; Kometani, Yusuke; Langridge, Rob; Lin, Weiren; Little, Timothy; Lukacs, Adrienn; Mallyon, Deirdre; Mariani, Elisabetta; Massiot, Cécile; Mathewson, Loren; Melosh, Ben; Menzies, Catriona; Moore, Jo; Morales, Luiz; Morgan, Chance; Mori, Hiroshi; Niemeijer, Andre; Nishikawa, Osamu; Prior, David; Sauer, Katrina; Savage, Martha; Schleicher, Anja; Schmitt, Douglas R; Shigematsu, Norio; Taylor-Offord, Sam; Teagle, Damon; Tobin, Harold; Valdez, Robert; Weaver, Konrad; Wiersberg, Thomas; Williams, Jack; Woodman, Nick; Zimmer, Martin

2017-06-01

Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.

Hydrothermal synthesis of highly nitrogen-doped few-layer graphene via solid–gas reaction

International Nuclear Information System (INIS)

Liang, Xianqing; Zhong, Jun; Shi, Yalin; Guo, Jin; Huang, Guolong; Hong, Caihao; Zhao, Yidong

2015-01-01

Highlights: • A novel approach to synthesis of N-doped few-layer graphene has been developed. • The high doping levels of N in products are achieved. • XPS and XANES results reveal a thermal transformation of N bonding configurations. • The developed method is cost-effective and eco-friendly. - Abstract: Nitrogen-doped (N-doped) graphene sheets with high doping concentration were facilely synthesized through solid–gas reaction of graphene oxide (GO) with ammonia vapor in a self-designed hydrothermal system. The morphology, surface chemistry and electronic structure of N-doped graphene sheets were investigated by TEM, AFM, XRD, XPS, XANES and Raman characterizations. Upon hydrothermal treatment, up to 13.22 at% of nitrogen could be introduced into the crumpled few-layer graphene sheets. Both XPS and XANES analysis reveal that the reaction between oxygen functional groups in GO and ammonia vapor produces amide and amine species in hydrothermally treated GO (HTGO). Subsequent thermal annealing of the resultant HTGO introduces a gradual transformation of nitrogen bonding configurations in graphene sheets from amine N to pyridinic and graphitic N with the increase of annealing temperature. This study provides a simple but cost-effective and eco-friendly method to prepare N-doped graphene materials in large-scale for potential applications

Nucleation control and inhibition of BaTiO3 films using hydrothermal-electrochemical method

International Nuclear Information System (INIS)

Escobar, Ivan; Silva, Carmen; Silva, Eric; Vargas, Tomas; Fuenzalida, Victor

1999-01-01

The microstructure of BaTiO 3 films on titanium by the hydrothermal-electrochemical method was investigated using a three electrode high pressure electrochemical cell in a 0.2 M Ba(OH) 2 electrolyte at 150 0 C. The spontaneous initial linked to pure hydrothermal BaTiO 3 formation can be inhibited by cathodically protecting titanium electrode since its immersion in the electrolyte. The application of initial nucleation pulses of varying the cathodic potentials affected the grain size of the deposit. It is suggested that the formation of a titanium oxide layers is a necessary step previous to the nucleation of BaTiO 3

Structural and dielectric properties of barium strontium titanate produced by high temperature hydrothermal method

International Nuclear Information System (INIS)

Razak, K.A.; Asadov, A.; Yoo, J.; Haemmerle, E.; Gao, W.

2008-01-01

The preparation procedure, structural and dielectric properties of hydrothermally derived Ba x Sr 1-x TiO 3 (BST) were studied. BST with initial Ba compositions of 75, 80, 85 and 90 mol.% were prepared by a high temperature hydrothermal synthesis. The obtained powders were pressed into pellet, cold isostatically pressed and sintered at 1200 deg. C for 3 hours. The phase compositions and lattice parameters of the as prepared powders and sintered samples were analysed using X-ray diffractometry. A fitting software was used to analyse the XRD spectra to separate different phases. It was found that BST powder produced by the high temperature hydrothermal possessed a two-phase structure. This structure became more homogeneous during sintering due to interdiffusion but a small amount of minor phase can still be traced. Samples underwent an abnormal grain growth, whereby some grains grow faster than the other due to the presence of two-phase structure. The grain size increased with increasing Ba amount. Dielectric constant and polarisation increased with increasing Ba content but it was also affected by the electronic state and grain size of the compositions

Numerical Simulation of a Non-volcanic Hydrothermal System Caused by Formation of a High Permeability Fracture Zone

Science.gov (United States)

Oka, Daisuke; Ehara, Sachio; Fujimitsu, Yasuhiro

2010-05-01

Because in the Japanese islands the earth crust activity is very active, a disposal stratum for high-level radioactive waste produced by reprocessing the spent nuclear fuel from nuclear power plants will be selected in the tectonically stable areas in which the waste can be disposed underground safely for a long term and there is no influence of earthquakes, seismic activities, volcanic activities, upheaval, sedimentation, erosion, climate and global sea level change and so on, which causes the risk of the inflow of the groundwater to destroy the disposal site or the outflow to the ground surface. However, even if the disposal stratum in such condition will be chosen, in case that a new high permeability fracture zone is formed by the earthquake, and a new hydrothermal system may be formed for a long term (thousands or millions years) and the system may affect the disposal site. Therefore, we have to understand the feature of the non-volcanic hydrothermal system through the high permeability fracture zone. We estimated such influence by using HYDROTHERM Ver2.2 (Hayba & Ingebritsen, 1994), which is a three-dimensional numerical reservoir simulator. The model field is the northwestern part of Kego Fault, which was formed by a series of earthquakes called "the 2005 Fukuoka Prefecture Western Offshore Earthquakes" (the main shock of Mjma 7.0 on 20 March 2005) in Kyushu, Japan. The results of the numerical simulations show the development of a low temperature hydrothermal system as a new fracture zone is formed, in case that there is no volcanic heat source. The results of the simulations up to 100,000 years after formation of the fracture zone show that the higher heat flow and the wider and more permeable fracture zone accelerate the development of the hydrothermal system in the fracture zone. As a result of calculation of up to10 million years, we clarified the evolutional process of the non-volcanic hydrothermal system through the high permeability fracture zone. At

Guide to the Revised Ground-Water Flow and Heat Transport Simulator: HYDROTHERM - Version 3

Science.gov (United States)

Kipp, Kenneth L.; Hsieh, Paul A.; Charlton, Scott R.

2008-01-01

The HYDROTHERM computer program simulates multi-phase ground-water flow and associated thermal energy transport in three dimensions. It can handle high fluid pressures, up to 1 ? 109 pascals (104 atmospheres), and high temperatures, up to 1,200 degrees Celsius. This report documents the release of Version 3, which includes various additions, modifications, and corrections that have been made to the original simulator. Primary changes to the simulator include: (1) the ability to simulate unconfined ground-water flow, (2) a precipitation-recharge boundary condition, (3) a seepage-surface boundary condition at the land surface, (4) the removal of the limitation that a specified-pressure boundary also have a specified temperature, (5) a new iterative solver for the linear equations based on a generalized minimum-residual method, (6) the ability to use time- or depth-dependent functions for permeability, (7) the conversion of the program code to Fortran 90 to employ dynamic allocation of arrays, and (8) the incorporation of a graphical user interface (GUI) for input and output. The graphical user interface has been developed for defining a simulation, running the HYDROTHERM simulator interactively, and displaying the results. The combination of the graphical user interface and the HYDROTHERM simulator forms the HYDROTHERM INTERACTIVE (HTI) program. HTI can be used for two-dimensional simulations only. New features in Version 3 of the HYDROTHERM simulator have been verified using four test problems. Three problems come from the published literature and one problem was simulated by another partially saturated flow and thermal transport simulator. The test problems include: transient partially saturated vertical infiltration, transient one-dimensional horizontal infiltration, two-dimensional steady-state drainage with a seepage surface, and two-dimensional drainage with coupled heat transport. An example application to a hypothetical stratovolcano system with unconfined

REE controls in ultramafic hosted MOR hydrothermal systems: An experimental study at elevated temperature and pressure

Science.gov (United States)

Allen, Douglas E.; Seyfried, W. E.

2005-02-01

A hydrothermal experiment involving peridotite and a coexisting aqueous fluid was conducted to assess the role of dissolved Cl - and redox on REE mobility at 400°C, 500 bars. Data show that the onset of reducing conditions enhances the stability of soluble Eu +2 species. Moreover, Eu +2 forms strong aqueous complexes with dissolved Cl - at virtually all redox conditions. Thus, high Cl - concentrations and reducing conditions can combine to reinforce Eu mobility. Except for La, trivalent REE are not greatly affected by fluid speciation under the chemical and physical condition considered, suggesting control by secondary mineral-fluid partitioning. LREE enrichment and positive Eu anomalies observed in fluids from the experiment are remarkably similar to patterns of REE mobility in vent fluids issuing from basalt- and peridotite-hosted hydrothermal systems. This suggests that the chondrite normalized REE patterns are influenced greatly by fluid speciation effects and secondary mineral formation processes. Accordingly, caution must be exercised when using REE in hydrothermal vent fluids to infer REE sources in subseafloor reaction zones from which the fluids are derived. Although vent fluid patterns having LREE enrichment and positive Eu anomalies are typically interpreted to suggest plagioclase recrystallization reactions, this need not always be the case.

Contention between supply of hydrothermal fluid and conduit obstruction: inferences from numerical simulations

Science.gov (United States)

Tanaka, Ryo; Hashimoto, Takeshi; Matsushima, Nobuo; Ishido, Tsuneo

2018-05-01

We investigate a volcanic hydrothermal system using numerical simulations, focusing on change in crater temperature. Both increases and decreases in crater temperature have been observed before phreatic eruptions. We follow the system's response for up to a decade after hydrothermal fluid flux from the deep part of the system is increased and permeability is reduced at a certain depth in a conduit. Our numerical simulations demonstrate that: (1) changes in crater temperature are controlled by the magnitude of the increase in hydrothermal fluid flux and the degree of permeability reduction; (2) significant increases in hydrothermal flux with decreases in permeability induce substantial pressure changes in shallow depths in the edifice and decreases in crater temperature; (3) the location of maximum pressure change differs between the mechanisms. The results of this study imply that it is difficult to predict eruptions by crater temperature change alone. One should be as wary of large eruptions when crater temperature decreases as when crater temperature increases. It is possible to clarify the implications of changes in crater temperature with simultaneous observation of ground deformation.

Brine/Rock Interaction in Deep Oceanic Layered Gabbros: Petrological Evidence from Cl-Rich Amphibole, High-Temperature Hydrothermal Veins, and Experiments

Science.gov (United States)

Currin Sala, A. M.; Koepke, J.; Almeev, R. R.; Teagle, D. A. H.; Zihlmann, B.; Wolff, P. E.

2017-12-01

Evidence of high temperature brine/rock interaction is found in hydrothermal veins and dykelets that cross-cut layered olivine gabbros in the deep palaeocrust of the Sumail Ophiolite, Sultanate of Oman. Here we present petrological and geochemical data from these samples, and an experimental attempt to simulate brine/gabbro interaction using externally heated cold seal pressure vessels. The studied natural veins and dykelets contain pargasite, hornblende, actinolite, and Cl-rich pargasite with up to 5 wt% Cl, showing a range of formation conditions from magmatic to metamorphic (hydrothermal) and thus a complex history of brine/rock interaction. In addition, the isotopic study of the radiogenic 87/86Sr and stable 18O in different amphibole types provide an estimate for the extent of seawater influence as alteration agent in the veins of the studied samples. Experiments performed at 750 °C and 200 MPa with different starting materials (chlorine-free amphibole, olivine gabbro powder) and 20 wt% NaCl aqueous brine, illustrate the process by which gabbro-hosted amphibole-rich veins evolve at subsolidus temperatures in the presence of a seawater-derived fluid. Our results demonstrate a decrease in olivine, plagioclase and magnetite content in favour of hastingsite, pargasite and magnesiohornblende, a decrease of IVAl and Ti in the starting amphibole, and an increase in Cl in amphibole, up to 0.2 Cl wt%. Our experiments show the change of magmatic pargasite towards more magnesium and silica-rich end members with results comparable to mildly chlorine-rich pargasites and hornblendes found in the natural samples studied. However, the experimental setup also presents limitations in the attainment of very high-chlorine amphibole (up to 5 wt%). Our analytical and experimental results provide further evidence for the existence of a hydrothermal cooling system in the deep oceanic crust.

Production and analysis of hydroxyapatite from Australian corals via hydrothermal process

International Nuclear Information System (INIS)

Hu, J.; Russell, J.; Ben-Nissan, B.

1999-01-01

Since the 1970s it is well known that if a biocompatible ceramic prosthesis with appropriate interconnected pores is used, growth of hard and soft tissue into the surface pores will be observed. A very strong attachment and hence the resultant mechanical and chemical bond to the existing surrounding tissue will be produced. Current artificial eyes although widely used encounter various problems due to the their motility and fail to deliver natural movement. They also cause sagging of the lids due to unsupported weight of the prosthesis. It is expected that application of a porous bioceramic such as the hydroxyapatite can generate good bonding to the tissue and hence a life-like eye movement. Hydroxyapatite (HAp) and related calcium phosphates have been studied for many years as implant materials, due to their similarity with the mineral phase of bone. From the point of view of biocompatibility, HAp seems to be the most suitable ceramic material for tissue replacement implants. Hydroxyapatite ceramics do not exhibit any cytoxic effects. It shows excellent biocompatibility with hard and soft tissues. Moreover, HAp can directly bond to the bone. Various preparation methods for HAp including the hydrothermal method have been used. The hydrothermal method was first used for hydroxyapatite formation directly from corals in 1974 by Roy and Linnehan. Complete replacement of aragonite by phosphatic material was achieved under 270degC and 103MPa using the hydrothermal process. This process has the disadvantage that the hydrothermal treatment must be carried out at a relatively high temperature under very high pressure. In 1996, HAp derived from Indian coral using hydrothermal process was developed by Sivakumar et al. However, the resultant material was in the form of a powder. Australia has rich variety of corals. Their application for implants have been studied very little. In this study, Australian corals selected were used for hydroxyapatite conversion. A new hydrothermal

Hydrothermal systems on Mars: an assessment of present evidence

Science.gov (United States)

Farmer, J. D.

1996-01-01

Hydrothermal processes have been suggested to explain a number of observations for Mars, including D/H ratios of water extracted from Martian meteorites, as a means for removing CO2 from the Martian atmosphere and sequestering it in the crust as carbonates, and as a possible origin for iron oxide-rich spectral units on the floors of some rifted basins (chasmata). There are numerous examples of Martian channels formed by discharges of subsurface water near potential magmatic heat sources, and hydrothermal processes have also been proposed as a mechanism for aquifer recharge needed to sustain long term erosion of sapping channels. The following geological settings have been identified as targets for ancient hydrothermal systems on Mars: channels located along the margins of impact crater melt sheets and on the slopes of ancient volcanoes; chaotic and fretted terranes where shallow subsurface heat sources are thought to have interacted with ground ice; and the floors of calderas and rifted basins (e.g. chasmata). On Earth, such geological environments are often a locus for hydrothermal mineralization. But we presently lack the mineralogical information needed for a definitive evaluation of hypotheses. A preferred tool for identifying minerals by remote sensing methods on Earth is high spatial resolution, hyperspectral, near-infrared spectroscopy, a technique that has been extensively developed by mineral explorationists. Future efforts to explore Mars for ancient hydrothermal systems would benefit from the application of methods developed by the mining industry to look for similar deposits on Earth. But Earth-based exploration models must be adapted to account for the large differences in the climatic and geological history of Mars. For example, it is likely that the early surface environment of Mars was cool, perhaps consistently below freezing, with the shallow portions of hydrothermal systems being dominated by magma-cryosphere interactions. Given the smaller

Anhydrite precipitation in seafloor hydrothermal systems

Science.gov (United States)

Theissen-Krah, Sonja; Rüpke, Lars H.

2016-04-01

The composition and metal concentration of hydrothermal fluids venting at the seafloor is strongly temperature-dependent and fluids above 300°C are required to transport metals to the seafloor (Hannington et al. 2010). Ore-forming hydrothermal systems and high temperature vents in general are often associated with faults and fracture zones, i.e. zones of enhanced permeabilities that act as channels for the uprising hydrothermal fluid (Heinrich & Candela, 2014). Previous numerical models (Jupp and Schultz, 2000; Andersen et al. 2015) however have shown that high permeabilities tend to decrease fluid flow temperatures due to mixing with cold seawater and the resulting high fluid fluxes that lead to short residence times of the fluid near the heat source. A possible mechanism to reduce the permeability and thereby to focus high temperature fluid flow are mineral precipitation reactions that clog the pore space. Anhydrite for example precipitates from seawater if it is heated to temperatures above ~150°C or due to mixing of seawater with hydrothermal fluids that usually have high Calcium concentrations. We have implemented anhydrite reactions (precipitation and dissolution) in our finite element numerical models of hydrothermal circulation. The initial results show that the precipitation of anhydrite efficiently alters the permeability field, which affects the hydrothermal flow field as well as the resulting vent temperatures. C. Andersen et al. (2015), Fault geometry and permeability contrast control vent temperatures at the Logatchev 1 hydrothermal field, Mid-Atlantic Ridge, Geology, 43(1), 51-54. M. D. Hannington et al. (2010), Modern Sea-Floor Massive Sulfides and Base Metal Resources: Toward an Estimate of Global Sea-Floor Massive Sulfide Potential, in The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration, and New Discoveries, edited by R. J. Goldfarb, E. E. Marsh and T. Monecke, pp. 317-338, Society of Economic Geologists

Hydrothermal metallurgy for recycling of slag and glass

International Nuclear Information System (INIS)

Tanaka, Toshihiro; Yoshikawa, Takeshi; Hirai, Nobumitsu; Katsuyama, Shigeru

2009-01-01

The authors have applied hydrothermal reactions to develop recycling processing of slag or glass. As an example, under hydrothermal conditions such as 200 300 deg. C and 30 40MPa with H 2 O, powders made of glass can be sintered to become solidified glass materials containing about 10mass% H 2 O. When the glass containing H 2 O is heated again under normal pressure, the glass expands releasing H 2 O to make porous microstructure. H 2 O starts to emit just above the glass transition temperature. Therefore, when we have a glass with low glass transition temperature, we can make low temperature foaming glass. The SiO 2 -Na 2 O-B 2 O 3 glass is a candidate to be such a foaming glass. In this paper, we describe our recent trial on the fabrication of the low temperature foaming glass by using hydrothermal reaction.

Argentine hydrothermal panorama

Energy Technology Data Exchange (ETDEWEB)

1976-12-01

An attempt is made to give a realistic review of Argentine thermal waters. The topics discussed are the characteristics of the hydrothermal resources, classification according to their mineral content, hydrothermal flora and fauna, uses of hydrothermal resources, hydrothermal regions of Argentina, and meteorology and climate. A tabulation is presented of the principal thermal waters. (JSR)

Influence of the pressure applied to make LATP pellets

Science.gov (United States)

Lu, Xiaojuan

2018-02-01

NASICON structured Li1+xAlxTi2-x(PO4)3 (0.1≤x≤0.7) powders were prepared by hydrothermal synthesis method and the pressure applied to press the powders into pellets was investigated in this study. The conductivity was measured by an impedance analyzer and the microstructures were examined by SEM. The variation trend with Al amount was almost identical for LATP pressed at high pressure and low pressure. Both the total conductivities of LATP prepared at high pressures and low pressures peaked at x=0.6. The conductivities of LATP pressed at high pressures were all higher than those at low pressures. The reason was mainly attributed to the denser microstructures achieved at higher pressure.

Numerical Modeling of Hydrothermal Circulation at the Longqi-1 Field: Southwest Indian Ridge

Science.gov (United States)

Guo, Z.; Lowell, R. P.; Tao, C.; Rupke, L.; Lewis, K. C.

2017-12-01

The Longqi-1(Dragon Flag) hydrothermal field is the first high-temperature hydrothermal system observed on the ultra-slow spreading Southwest Indian Ridge. Hydrothermal vents with temperatures near 380 °C are localized by detachment faulting within which extensional deformation likely increases permeability to provide preferred pathways for hydrothermal discharge. To better understand the Longqi-1 circulation system, we construct a 2-D numerical simulations in a NaCl- H2O fluid constrained by key observational data, such as vent temperature and heat output, crust structure derived from seismic data, and fault zone geometry deduced from seismicity. Heat output from AUV surveys is estimated to be » 300 ± 100 MW, and this value, in conjunction with vent temperature was used with the single-pass modeling approach to obtain an average permeability of 10-13 m-2 within the fault zone. In analogy with other fault-controlled hydrothermal systems such as Logatchev-1 we assume a lower background permeability of 10-14 m-2. The top boundary of the system is permeable and maintained at constant seafloor pressure, which is divided into two parts by the detachment fault. The pressure of the southern part is lower than the northern part to simulate the effect of the seafloor topography. The top boundary is upstream weighted to allow high temperature fluid to exit, while recharging fluid is maintained at 10°C. The bottom boundary is impermeable and is given a fixed temperature distribution at a depth of 7 km below the seafloor. The highest value Tmax is maintained over a distance given lateral distance and decreases linearly towards two ends to 300 °C. The salinity is set to 3.2 wt. % NaCl, and the simulations are assumed to be single phase. The results show that with a 7 km deep circulation system, Tmax = 550 oC gives a reasonable temperature and heat output of venting plume.We infer that the observed high salinity results from serpentinization reactions. Assuming all salinity

High Blood Pressure

Science.gov (United States)

... normal blood pressure 140/90 or higher is high blood pressure Between 120 and 139 for the top number, ... prehypertension. Prehypertension means you may end up with high blood pressure, unless you take steps to prevent it. High ...

A high-temperature hydrothermal deposit on the East Pacific Rise near 70N

International Nuclear Information System (INIS)

Boulegue, J.; Stouff, P.; Perseil, E.A.; Bernat, M.; Dupre, B.; Francheteau, J.

1984-01-01

A SEABEAM survey of the East Pacific Rise (EPR) led to the selection of several sites having structural characteristics favorable for hydrothermal activity. Dredging of such an area located at 7 0 N on the EPR resulted in the recovery of sulfides, oxides and fresh basalt. Chemical analyses and isotopic compositions showed that the recovered pyrites were probably precipitated directly from hot vent hydrothermal waters. Chemical analyses and isotopic composition of manganese-iron oxides indicated that they too were of hydrothermal origin. 210 Pb/Pb measurements yielded ages of 90 +- 10 years for the deposits. This site may still be undergoing hydrothermal activity. (orig.)

The chemistry of hydrothermal magnetite: a review

Science.gov (United States)

Nadoll, Patrick; Angerer, Thomas; Mauk, Jeffrey L.; French, David; Walshe, John

2014-01-01

Magnetite (Fe3O4) is a well-recognized petrogenetic indicator and is a common accessory mineral in many ore deposits and their host rocks. Recent years have seen an increased interest in the use of hydrothermal magnetite for provenance studies and as a pathfinder for mineral exploration. A number of studies have investigated how specific formation conditions are reflected in the composition of the respective magnetite. Two fundamental questions underlie these efforts — (i) How can the composition of igneous and, more importantly, hydrothermal magnetite be used to discriminate mineralized areas from barren host rocks, and (ii) how can this assist exploration geologists to target ore deposits at greater and greater distances from the main mineralization? Similar to igneous magnetite, the most important factors that govern compositional variations in hydrothermal magnetite are (A) temperature, (B) fluid composition — element availability, (C) oxygen and sulfur fugacity, (D) silicate and sulfide activity, (E) host rock buffering, (F) re-equilibration processes, and (G) intrinsic crystallographic controls such as ionic radius and charge balance. We discuss how specific formation conditions are reflected in the composition of magnetite and review studies that investigate the chemistry of hydrothermal and igneous magnetite from various mineral deposits and their host rocks. Furthermore, we discuss the redox-related alteration of magnetite (martitization and mushketovitization) and mineral inclusions in magnetite and their effect on chemical analyses. Our database includes published and previously unpublished magnetite minor and trace element data for magnetite from (1) banded iron formations (BIF) and related high-grade iron ore deposits in Western Australia, India, and Brazil, (2) Ag–Pb–Zn veins of the Coeur d'Alene district, United States, (3) porphyry Cu–(Au)–(Mo) deposits and associated (4) calcic and magnesian skarn deposits in the southwestern United

Post-capture immune gene expression studies in the deep-sea hydrothermal vent mussel Bathymodiolus azoricus acclimatized to atmospheric pressure.

Science.gov (United States)

Barros, Inês; Divya, Baby; Martins, Inês; Vandeperre, Frederic; Santos, Ricardo Serrão; Bettencourt, Raul

2015-01-01

Deep-sea hydrothermal vents are extreme habitats that are distributed worldwide in association with volcanic and tectonic events, resulting thus in the establishment of particular environmental conditions, in which high pressure, steep temperature gradients, and potentially toxic concentrations of sulfur, methane and heavy metals constitute driving factors for the foundation of chemosynthetic-based ecosystems. Of all the different macroorganisms found at deep-sea hydrothermal vents, the mussel Bathymodiolus azoricus is the most abundant species inhabiting the vent ecosystems from the Mid-Atlantic Ridge (MAR). In the present study, the effect of long term acclimatization at atmospheric pressure on host-symbiotic associations were studied in light of the ensuing physiological adaptations from which the immune and endosymbiont gene expressions were concomitantly quantified by means of real-time PCR. The expression of immune genes at 0 h, 12 h, 24 h, 36 h, 48 h, 72 h, 1 week and 3 weeks post-capture acclimatization was investigated and their profiles compared across the samples tested. The gene signal distribution for host immune and bacterial genes followed phasic changes in gene expression at 24 h, 1 week and 3 weeks acclimatization when compared to other time points tested during this temporal expression study. Analyses of the bacterial gene expression also suggested that both bacterial density and activity could contribute to shaping the intricate association between endosymbionts and host immune genes whose expression patterns seem to be concomitant at 1 week acclimatization. Fluorescence in situ hybridization was used to assess the distribution and prevalence of endosymbiont bacteria within gill tissues confirming the gradual loss of sulfur-oxidizing (SOX) and methane-oxidizing (MOX) bacteria during acclimatization. The present study addresses the deep-sea vent mussel B. azoricus as a model organism to study how acclimatization in aquaria and the

Porosity evolution in Icelandic hydrothermal systems

Science.gov (United States)

Thien, B.; Kosakowski, G.; Kulik, D. A.

2014-12-01

Mineralogical alteration of reservoir rocks, driven by fluid circulation in natural or enhanced hydrothermal systems, is likely to influence the long-term performance of geothermal power generation. A key factor is the change of porosity due to dissolution of primary minerals and precipitation of secondary phases. Porosity changes will affect fluid circulation and solute transport, which, in turn, influence mineralogical alteration. This study is part of the Sinergia COTHERM project (COmbined hydrological, geochemical and geophysical modeling of geotTHERMal systems, grant number CRSII2_141843/1) that is an integrative research project aimed at improving our understanding of the sub-surface processes in magmatically-driven natural geothermal systems. These are typically high enthalphy systems where a magmatic pluton is located at a few kilometers depth. These shallow plutons increase the geothermal gradient and trigger the circulation of hydrothermal waters with a steam cap forming at shallow depth. Field observations suggest that active and fossil Icelandic hydrothermal systems are built from a superposition of completely altered and completely unaltered layers. With help of 1D and 2D reactive transport models (OpenGeoSys-GEM code), we investigate the reasons for this finding, by studying the mineralogical evolution of protoliths with different initial porosities at different temperatures and pressures, different leaching water composition and gas content, and different porosity geometries (i.e. porous medium versus fractured medium). From this study, we believe that the initial porosity of protoliths and volume changes due to their transformation into secondary minerals are key factors to explain the different alteration extents observed in field studies. We also discuss how precipitation and dissolution kinetics can influence the alteration time scales.

Pressure Dome for High-Pressure Electrolyzer

Science.gov (United States)

Norman, Timothy; Schmitt, Edwin

2012-01-01

A high-strength, low-weight pressure vessel dome was designed specifically to house a high-pressure [2,000 psi (approx. = 13.8 MPa)] electrolyzer. In operation, the dome is filled with an inert gas pressurized to roughly 100 psi (approx. = 690 kPa) above the high, balanced pressure product oxygen and hydrogen gas streams. The inert gas acts to reduce the clamping load on electrolyzer stack tie bolts since the dome pressure acting axially inward helps offset the outward axial forces from the stack gas pressure. Likewise, radial and circumferential stresses on electrolyzer frames are minimized. Because the dome is operated at a higher pressure than the electrolyzer product gas, any external electrolyzer leak prevents oxygen or hydrogen from leaking into the dome. Instead the affected stack gas stream pressure rises detectably, thereby enabling a system shutdown. All electrical and fluid connections to the stack are made inside the pressure dome and require special plumbing and electrical dome interfaces for this to be accomplished. Further benefits of the dome are that it can act as a containment shield in the unlikely event of a catastrophic failure. Studies indicate that, for a given active area (and hence, cell ID), frame outside diameter must become ever larger to support stresses at higher operating pressures. This can lead to a large footprint and increased costs associated with thicker and/or larger diameter end-plates, tie-rods, and the frames themselves. One solution is to employ rings that fit snugly around the frame. This complicates stack assembly and is sometimes difficult to achieve in practice, as its success is strongly dependent on frame and ring tolerances, gas pressure, and operating temperature. A pressure dome permits an otherwise low-pressure stack to operate at higher pressures without growing the electrolyzer hardware. The pressure dome consists of two machined segments. An O-ring is placed in an O-ring groove in the flange of the bottom

The BGU/CERN solar hydrothermal reactor

CERN Document Server

Bertolucci, Sergio; Caspers, Fritz; Garb, Yaakov; Gross, Amit; Pauletta, Stefano

2014-01-01

We describe a novel solar hydrothermal reactor (SHR) under development by Ben Gurion University (BGU) and the European Organization for Nuclear Research CERN. We describe in broad terms the several novel aspects of the device and, by extension, of the niche it occupies: in particular, enabling direct off-grid conversion of a range of organic feedstocks to sterile useable (solid, liquid) fuels, nutrients, products using only solar energy and water. We then provide a brief description of the high temperature high efficiency panels that provide process heat to the hydrothermal reactor, and review the basics of hydrothermal processes and conversion taking place in this. We conclude with a description of a simulation of the pilot system that will begin operation later this year.

High Pressure Reduction of Selenite by Shewanella oneidensis MR-1

Science.gov (United States)

Picard, A.; Daniel, I.; Testemale, D.; Letard, I.; Bleuet, P.; Cardon, H.; Oger, P.

2007-12-01

High-pressure biotopes comprise cold deep-sea environments, hydrothermal vents, and deep subsurface or deep-sea sediments. The latter are less studied, due to the technical difficulties to sample at great depths without contamination. Nevertheless, microbial sulfate reduction and methanogenesis have been found to be spatially distributed in deep deep-sea sediments (1), and sulfate reduction has been shown to be actually more efficient under high hydrostatic pressure (HHP) in some sediments (2). Sulfate-reducing bacteria obtained from the Japan Sea are characterized by an increased sulfide production under pressure (3,4). Unfortunately, investigations of microbial metabolic activity as a function of pressure are extremely scarce due to the experimental difficulty of such measurements at high hydrostatic pressure. We were able to measure the reduction of selenite Se(IV) by Shewanella oneidensis MR-1 as a function of pressure, to 150 MPa using two different high-pressure reactors that allow in situ X-ray spectroscopy measurements on a synchrotron source. A first series of measurements was carried out in a low-pressure Diamond Anvil Cell (DAC) of our own design (5) at ID22 beamline at ESRF (European Synchrotron Radiation Facility); a second one was performed in an autoclave (6) at the BM30B beamline at ESRF. Selenite reduction by strain MR-17 was monitored from ambient pressure to 150 MPa over 25 hours at 30 deg C by XANES spectroscopy (X-ray Analysis of Near Edge Structure). Spectra were recorded hourly in order to quantify the evolution of the oxidation state of selenium with time. Stationary-phase bacteria were inoculated at a high concentration into fresh growth medium containing 5 or 10 M of sodium selenite and 20 mM sodium lactate. Kinetic parameters of the Se (IV) reduction by Shewanella oneidensis strain MR-1 could be extracted from the data, as a function of pressure. They show 1) that the rate constant k of the reaction is decreased by a half at high pressure

Raman studies of hexagonal MoO{sub 3} at high pressure

Energy Technology Data Exchange (ETDEWEB)

Zhang, C.C.; Zhang, Z.M.; Dai, R.C.; Zhang, J.W.; Ding, Z.J. [Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zheng, L. [Department of Nanomaterials and Nanochemistry, Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wang, Z.P. [The Centre for Physical Experiments, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2011-05-15

The transition-metal oxide MoO{sub 3} is an important semiconductor and has various technological applications in catalysts, electrochromic and photochromic devices, gas sensors, and battery electrodes. In this study, the hexagonal MoO{sub 3} prepared by a hydrothermal method is in morphology of microrod with diameter of 0.8-1.2 {mu}m and length of 2.0-4.3 {mu}m. Its structural stability was investigated by an in situ Raman scattering method in a diamond anvil cell up to 28.7 GPa at room temperature. The new Raman peak around 1000 cm{sup -1} implies that a phase transition from hexagonal to amorphous starts at 5.6 GPa, and the evolution of the Raman spectra indicates that the structural transition is completed at about 13.2 GPa. After releasing pressure to ambient condition, the Raman spectrum pattern of the high pressure phase was retained, revealing that the phase transition is irreversible. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Synthesis and characterization of nanosized ceria powders by microwave-hydrothermal method

International Nuclear Information System (INIS)

Bonamartini Corradi, A.; Bondioli, F.; Ferrari, A.M.; Manfredini, T.

2006-01-01

Nanocrystalline ceria powders (CeO 2 ) have been prepared by adding NaOH to a cerium ammonium nitrate aqueous solution under microwave-hydrothermal conditions. In particular the effect of the synthesis conditions (time, pressure and concentration of both the precursor and the precipitant agent solutions) on the physical properties of the crystals have been evaluated. Microwave-hydrothermal treatment of 5 min at 13.4 atm allows to obtain almost crystallized powders (amorphous phase 4%) as underlined by Rietveld-reference intensity ratio (RIR) results

Hypertension (High Blood Pressure)

Science.gov (United States)

... Safe Videos for Educators Search English Español Hypertension (High Blood Pressure) KidsHealth / For Teens / Hypertension (High Blood Pressure) What's ... rest temperature diet emotions posture medicines Why Is High Blood Pressure Bad? High blood pressure means a person's heart ...

Template-free hydrothermal synthesis and high photocatalytic activity of ZnWO4 nanorods

International Nuclear Information System (INIS)

Gao, Bin; Fan, Huiqing; Zhang, Xiaojun; Song, Lixun

2012-01-01

Highlights: ► ZnWO 4 nanorods with uniform diameter are successfully prepared through a template-free hydrothermal method. ► The crystallinity of the products is influenced by the pH value of initial precursor suspension. ► Photocatalytic activity of the ZnWO 4 nanorods for degradation of methylene blue is evaluated. ► The ZnWO 4 nanorods exhibit good stability of photocatalytic activity. - Abstract: ZnWO 4 nanorods are successfully synthesized by a template-free hydrothermal method, and are characterized in detail by X-ray diffractometer (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED). The results show that the ZnWO 4 nanorods with wolframite structure are well-crystallized single crystallites. The crystallinity of the products is influenced by the pH value of initial precursor suspension. The width and length of the synthesized samples increase with hydrothermal reaction temperature. The photocatalytic efficiency of the ZnWO 4 nanorods for degradation of methylene blue (MB) in aqueous solution under UV light irradiation declines greatly with increasing crystallinity. The ZnWO 4 nanorods prepared at pH of 4 have the best activity in photo-degradation of MB. After six recycles, photocatalytic activity loss of the catalyst is not obvious.

Hydrothermal synthesis of nanostructured titania

International Nuclear Information System (INIS)

Yoshito, Walter Kenji; Ferreira, Nildemar A.M.; Rumbao, Ana Carolina S. Coutinho; Lazar, Dolores R.R.; Ussui, Valter

2009-01-01

Titania ceramics have many applications due to its surface properties and, recently, its nanostructured compounds, prepared by hydrothermal treatments, have been described to improve these properties. In this work, commercial titanium dioxide was treated with 10% sodium hydroxide solution in a pressurized reactor at 150°C for 24 hours under vigorous stirring and then washed following two different procedures. The first one consisted of washing with water and ethanol and the second with water and hydrochloric acid solution (1%). Resulting powders were characterized by X-ray diffraction, N 2 gas adsorption and field emission gun scanning and transmission electronic microscopy. Results showed that from an original starting material with mainly rutile phase, both anatase and H 2 Ti 3 O 7 phase could be identified after the hydrothermal treatment. Surface area of powders presented a notable increase of one order of magnitude and micrographs showed a rearrangement on the microstructure of powders. (author)

Hydrothermal synthesis of nanostructured titania

International Nuclear Information System (INIS)

Yoshito, W.K.; Ferreira, N.A.M.; Lazar, D.R.R.; Ussui, V.; Rumbao, A.C.S.

2011-01-01

Titania ceramics have many applications due to its surface properties and, recently, its nanostructured compounds, prepared by hydrothermal treatments, have been described to improve these properties. In this work, commercial titanium dioxide was treated with 10% sodium hydroxide solution in a pressurized reactor at 150 deg C for 24 hours under vigorous stirring and then washed following two different procedures. The first one consisted of washing with water and ethanol and the second with water and hydrochloric acid solution (1%). Resulting powders were characterized by X-ray diffraction, N 2 gas adsorption and field emission gun scanning and transmission electronic microscopy. Results showed that from an original starting material with mainly rutile phase, both anatase and H 2 Ti 3 O 7 phase could be identified after the hydrothermal treatment. Surface area of powders presented a notable increase of one order of magnitude and micrographs showed a rearrangement on the microstructure of powders. (author)

Chemical speciation of inorganic compounds under hydrothermal conditions. 1998 annual progress report

International Nuclear Information System (INIS)

Darab, J.G.; Fulton, J.L.; Steidler, G.T.; Stern, E.A.

1998-01-01

'To obtain the chemistry of metallic solute ions under aqueous and hydrothermal conditions in order to obtain key insights pertinent to the removal of toxic wastes. Elements present in Hanford tank wastes will be investigated to get a better understanding of how the high temperatures involved in vitrification will affect the hydrolysis-polymerization reaction. In the following summary of the x-ray absorption fine structure (XAFS) measurements under aqueous and hydrothermal conditions, most measurements below the critical temperature (375 C) were taken at about 200 bar pressure, while at supercritical temperatures the pressure was about 600 bar. Chemistry of Na 2 WO 4 Under Aqueous and Hydrothermal Conditions Tungsten, molybdenum, vanadium and, to a lesser agree, chromium, niobium and tantalum form isopolymetallates, polymeric species of rather complicated structure and complex chemical equilibria, in aqueous solution upon acidification. Except Tantalum, all of these elements are present in the Hanford tank wastes and it is not well understood how the high temperatures involved in vitrification will affect the hydrolysis-polymerization reaction. In March 1998, the authors launched a series of XAFS experiments to resolve these questions. Measurements were obtained for 0.2 molal tungstate solutions as a function of temperature (to 200 C) and as a function of starting pH. The outcome of these measurements is providing key insights into this chemistry as follows: (1) A change from tetrahedral to octahedral coordination of the oxygen atoms around the tungsten center atom can be detected upon increasing extent of polymerization. (2) At least one new feature shows up in the Fourier Transform of the k-weighted Chi plot (closely related to a radial distribution function) which is unambiguously attributed to a tungsten-tungsten scattering path, only present in the polymeric species. (3) Perhaps most interestingly, the XAFS data indicate a higher extent of polymerization at

Hydrothermal Cold Sintering

Science.gov (United States)

Kang, Xiaoyu

Solid state sintering transforms particle compact to a physically robust and dense polycrystalline monolith driven by reduction of surface energy and curvature. Since bulk diffusion is required for neck formation and pore elimination, sintering temperature about 2/3 of melting point is needed. It thus places limitations for materials synthesis and integration, and contributes to significant energy consumption in ceramic processing. Furthermore, since surface transport requires lower temperature than bulk processes, grain growth is often rapid and can be undesired for physical properties. For these reasons, several techniques have been developed including Liquid Phase Sintering (LPS), Hot Pressing (HP) and Field Assisted Sintering Technique (FAST), which introduce either viscous melt, external pressure or electric field to speed up densification rates at lower temperature. However, because of their inherent reliability on bulk diffusion, temperatures required are often too high for integrating polymers and non-noble metals. Reduction of sintering temperature below 400 °C would require a different densification mechanism that is based on surface transport with external forces to drive volume shrinkage. Densification method combining uniaxial pressure and solution under hydrothermal condition was first demonstrated by Kanahara's group at Kochi University in 1986 and was brought to our attention by the work of Kahari, etc, from University of Oulu on densification of Li2MoO 4 in 2015. This relatively new process showed promising ultra-low densification temperature below 300 °C, however little was known about its fundamental mechanism and scope of applications, which became the main focus of this dissertation. In this work, a uniaxial hydraulic press, a standard stainless steel 1/2 inch diameter die with heating band were utilized in densifying metal oxides. Applied pressure and sintering temperature were between 100 MPa and 700 MPa and from room temperature to 300 �

Geochemical constraints on chemolithoautotrophic reactions in hydrothermal systems

Science.gov (United States)

Shock, Everett L.; McCollom, Thomas; Schulte, Mitchell D.

1995-06-01

Thermodynamic calculations provide the means to quantify the chemical disequilibrium inherent in the mixing of redeuced hydrothermal fluids with seawater. The chemical energy available for metabolic processes in these environments can be evaluated by taking into account the pressure and temperature dependence of the apparent standard Gibbs free energies of reactions in the S-H2-H2O system together with geochemical constraints on pH, activities of aqueous sulfur species and fugacities of H2 and/or O2. Using present-day mixing of hydrothermal fluids and seawater as a starting point, it is shown that each mole of H2S entering seawater from hydrothermal fluids represents about 200,000 calories of chemical energy for metabolic systems able to catalyze H2S oxidation. Extrapolating to the early Earth, which was likely to have had an atmosphere more reduced than at present, shows that this chemical energy may have been a factor of two or so less. Nevertheless, mixing of hydrothermal fluids with seawater would have been an abundant source of chemical energy, and an inevitable consequence of the presence of an ocean on an initially hot Earth. The amount of energy available was more than enough for organic synthesis from CO2 or CO, and/or polymer formation, indicating that the vicinity of hydrothermal systems at the sea floor was an ideal location for the emergence of the first chemolithoautotrophic metabolic systems.

Water-rock interactions in discharge areas of Xiangshan Fossil hydrothermal system

International Nuclear Information System (INIS)

Zhou, Wenbin

1992-01-01

Xiangshan Fossil hydrothermal system is located within a volcanic basin of south-eastern China. The fact that most metal mineralizations were found in the discharge areas of the fossil hydrothermal system shows that the discharge areas were special geochemical fields. This paper discusses some important water-rock interactions in the discharge areas of Xiangshan fossil hydrothermal system. When the fluids circulating in the deep section of the hydrothermal system went upward to the discharge area, the physico-chemical conditions under which the fluids were saturated changed so considerably that the original physico-chemical equilibria were broken. Consequently, the fluids tended to move to new equilibrium by means of regulating their chemical compositions. Temperature and pressures of the fluids could be declined greatly in discharge area; the difference of temperature and pressure are determined to be 100--150 C and 1--2 x 10 7 Pa. As a result, a large amount of CO 2 in solution escaped from the fluids in the discharge area, and UO 2 (CO 3 ) n 2(1-n) , stable in CO 2 -rich solutions, could be decomposed into UUO 2 2+ , which could be easily reduced into pitchblende associated by calcite and hematite. The pH values for the fluids tended to increase with the CO 2 escaping, however, the interactions between the hydrothermal fluids and the wall rocks (dominantly aluminosilicate) served as the buffers for the pH, and regulated the pH value around neutral point. The buffer effect was of great importance to uranium mineralization. In addition, isotope exchangements between the fluids and rocks took place extensively

Fluid transfer and vein thickness distribution in high and low temperature hydrothermal systems at shallow crustal level in southern Tuscany (Italy

Directory of Open Access Journals (Sweden)

Francesco Mazzarini

2014-06-01

Full Text Available Geometric analysis of vein systems hosted in upper crustal rocks and developed in high and low temperature hydrothermal systems is presented. The high temperature hydrothermal system consists of tourmaline-rich veins hosted within the contact aureole of the upper Miocene Porto Azzurro pluton in the eastern Elba Island. The low temperature hydrothermal system consists of calcite-rich veins hosted within the Oligocene sandstones of the Tuscan Nappe, exposed along the coast in southern Tuscany. Vein thickness distribution is here used as proxy for inferring some hydraulic properties (transmissivity of the fluid circulation at the time of veins’ formation. We derive estimations of average thickness of veins by using the observed distributions. In the case of power law thickness distributions, the lower the scaling exponent of the distribution the higher the overall transmissivity. Indeed, power law distributions characterised by high scaling exponents have transmissivity three order of magnitude lower than negative exponential thickness distribution. Simple observations of vein thickness may thus provides some clues on the transmissivity in hydrothermal systems.

Birnessite-type MnO2 nanosheets with layered structures under high pressure: elimination of crystalline stacking faults and oriented laminar assembly.

Science.gov (United States)

Sun, Yugang; Wang, Lin; Liu, Yuzi; Ren, Yang

2015-01-21

Squeezing out crystalline stacking faults: Birnessite-type δ-phase MnO2 microflowers containing interconnected ultrathin nanosheets are synthesized through a microwave-assisted hydrothermal process and exhibit a layered crystalline structure with significant stacking faults. Compressing these MnO2 nanosheets in a diamond anvil cell with high pressure up to tens of GPa effectively eliminates the crystalline stacking faults. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Voltammetric Investigation Of Hydrothermal Iron Speciation

Directory of Open Access Journals (Sweden)

Charlotte eKleint

2016-05-01

Full Text Available Hydrothermal vent fluids are highly enriched in iron (Fe compared to ambient seawater, and organic ligands may play a role in facilitating the transport of some hydrothermal Fe into the open ocean. This is important since Fe is a limiting micronutrient for primary production in large parts of the world`s surface ocean. We have investigated the concentration and speciation of Fe in several vent fluid and plume samples from the Nifonea vent field, Coriolis Troughs, New Hebrides Island Arc, South Pacific Ocean using competitive ligand exchange - adsorptive cathodic stripping voltammetry (CLE - AdCSV with salicylaldoxime (SA as the artificial ligand. Our results for total dissolved Fe (dFe in the buoyant hydrothermal plume samples showed concentrations up to 3.86 µM dFe with only a small fraction between 1.1% and 11.8% being chemically labile. Iron binding ligand concentrations ([L] were found in µM level with strong conditional stability constants up to log K[L],Fe3+ of 22.9. Within the non-buoyant hydrothermal plume above the Nifonea vent field, up to 84.7% of the available Fe is chemically labile and [L] concentrations up to 97 nM were measured. [L] was consistently in excess of Felab, indicating that all available Fe is being complexed, which in combination with high Felab values in the non-buoyant plume, signifies that a high fraction of hydrothermal dFe is potentially being transported away from the plume into the surrounding waters, contributing to the global oceanic Fe budget.

Solidification of ion-exchange resins by hydrothermal hot-pressing

International Nuclear Information System (INIS)

Kaneko, M.

1993-01-01

The solidification reaction which easily occurs while continuously keeping the mixture of cation and anion exchange resins compressed under hydrothermal conditions has been demonstrated. Dehydration was considered to occur between sulphonic acid (-SO 3 H) from the cation exchange resin and quaternary ammonium [-CH 2 -N(CH 3 ) 3 OH] from anion-exchange resin-on terminal groups. The cation-and anion-exchange resins were mixed in a 1:1 weight ratio, put in a hot-pressing autoclave and compressed between pistons from the top and bottom at 600 kg cm -2 pressure. The material was continuously compressed during hydrothermal treatment at 200 kg cm -2 by a hydraulic jack and heated to a desired temperature with an induction heater. This system could be used for rapid temperature increasing up to 30 o c min -1 . The pressure and temperature were kept constant for 10 min. The autoclave was cooled to room temperature after the hydrothermal treatment. After the specimen was taken out, the ion-exchange radical reactions were estimated and the product structures were examined. The cation- and anion-exchange resin mixture was solidified. The resultant solidified body at a 300 o C reaction condition for 10 min had a 1.0 g cm -3 density and 700 kg cm -2 compressive strength, and the weight loss did not change in distilled water for 2 weeks. On the other hand, a solidification reaction did not occur at below 250 o C when only the cation or anion was solidified, but they were decomposed. These results suggest that a mixture of cation- and anion-exchange resins causes a solidification reaction under hydrothermal hot-pressing conditions at 300 o C. (author)

An Integrative Genomic Island Affects the Adaptations of Piezophilic Hyperthermophilic Archaeon Pyrococcus yayanosii to High Temperature and High Hydrostatic Pressure

Directory of Open Access Journals (Sweden)

Zhen Li

2016-11-01

Full Text Available Deep-sea hydrothermal vent environments are characterized by high hydrostatic pressure and sharp temperature and chemical gradients. Horizontal gene transfer is thought to play an important role in the microbial adaptation to such an extreme environment. In this study, a 21.4-kb DNA fragment was identified as a genomic island, designated PYG1, in the genomic sequence of the piezophilic hyperthermophile Pyrococcus yayanosii. According to the sequence alignment and functional annotation, the genes in PYG1 could tentatively be divided into five modules, with functions related to mobility, DNA repair, metabolic processes and the toxin-antitoxin system. Integrase can mediate the site-specific integration and excision of PYG1 in the chromosome of P. yayanosii A1. Gene replacement of PYG1 with a SimR cassette was successful. The growth of the mutant strain ∆PYG1 was compared with its parent strain P. yayanosii A2 under various stress conditions, including different pH, salinity, temperature and hydrostatic pressure. The ∆PYG1 mutant strain showed reduced growth when grown at 100 °C, while the biomass of ∆PYG1 increased significantly when cultured at 80 MPa. Differential expression of the genes in module Ⅲ of PYG1 was observed under different temperature and pressure conditions. This study demonstrates the first example of an archaeal integrative genomic island that could affect the adaptation of the hyperthermophilic piezophile P. yayanosii to high temperature and high hydrostatic pressure.

Hydrothermal treatment followed by enzymatic hydrolysis and hydrothermal carbonization as means to valorise agro- and forest-based biomass residues.

Science.gov (United States)

Wikberg, Hanne; Grönqvist, Stina; Niemi, Piritta; Mikkelson, Atte; Siika-Aho, Matti; Kanerva, Heimo; Käsper, Andres; Tamminen, Tarja

2017-07-01

The suitability of several abundant but underutilized agro and forest based biomass residues for hydrothermal treatment followed by enzymatic hydrolysis as well as for hydrothermal carbonization was studied. The selected approaches represent simple biotechnical and thermochemical treatment routes suitable for wet biomass. Based on the results, the hydrothermal pre-treatment followed by enzymatic hydrolysis seemed to be most suitable for processing of carbohydrate rich corn leaves, corn stover, wheat straw and willow. High content of thermally stable components (i.e. lignin) and low content of ash in the biomass were advantageous for hydrothermal carbonization of grape pomace, coffee cake, Scots pine bark and willow. Copyright © 2017 Elsevier Ltd. All rights reserved.

Caldera unrest driven by CO2-induced drying of the deep hydrothermal system.

Science.gov (United States)

Moretti, R; Troise, C; Sarno, F; De Natale, G

2018-05-29

Interpreting volcanic unrest is a highly challenging and non-unique problem at calderas, since large hydrothermal systems may either hide or amplify the dynamics of buried magma(s). Here we use the exceptional ground displacement and geochemical datasets from the actively degassing Campi Flegrei caldera (Southern Italy) to show that ambiguities disappear when the thermal evolution of the deep hydrothermal system is accurately tracked. By using temperatures from the CO 2 -CH 4 exchange of 13 C and thermodynamic analysis of gas ascending in the crust, we demonstrate that after the last 1982-84 crisis the deep hydrothermal system evolved through supercritical conditions under the continuous isenthalpic inflow of hot CO 2 -rich gases released from the deep (~8 km) magma reservoir of regional size. This resulted in the drying of the base of the hot hydrothermal system, no more buffered along the liquid-vapour equilibrium, and excludes any shallow arrival of new magma, whose abundant steam degassing due to decompression would have restored liquid-vapour equilibrium. The consequent CO 2 -infiltration and progressive heating of the surrounding deforming rock volume cause the build-up of pore pressure in aquifers, and generate the striking temporal symmetry that characterizes the ongoing uplift and the post-1984 subsidence, both originated by the same but reversed deformation mechanism.

Highly Hydrothermally Stable Microporous Membranes for Hydroge Separation

NARCIS (Netherlands)

Wei, Qi; Wang, Fei; Wang, F.; Nie, Zuo-Ren; Song, C.; Wang, Yan-Li; Li, Qun-Yan

2008-01-01

Fluorocarbon-modified silica membranes were deposited on γ-Al2O3/α-Al2O3 supports by the sol−gel technique for hydrogen separation. The hydrophobic property, pore structure, gas transport and separation performance, and hydrothermal stability of the modified membranes were investigated. It is

Thermodynamic and physico-chemical fluctuations in hydrothermal systems suitable for the geological cradle of life

Science.gov (United States)

Kompanichenko, Vladimir

Thermodynamic and physico-chemical fluctuations in the medium seem are the necessary factor for the origin of life. Fluctuations are usual phenomena in hydrothermal systems including their outcrops in ocean or terrestrial groundwater aquifers. Investigation of the fluctuations regimes in natural hydrothermal systems can be used in advanced laboratory experiments on prebiotic organic synthesis under changeable conditions. To characterize a scale of the thermodynamic and physic-chemical fluctuations four hydrothermal systems were explored: several terrestrial hydrothermal systems, primarily on the Russian Far East. Temperature of water and water-steam mixture (from boreholes) in Mutnovsky and Pauzhetsky hydrothermal fields (Kamchatka peninsula) ranges from less than 100 o C up to 240 o C. Water from Kuldur thermal basin (in-tracontinental part of the Russian Far East) is characterized with the lower temperature: 60-70 o C. Data of monitoring of pressure, temperature and some chemical parameters in the boreholes of these fields were mathematically processed. Periods of long-range macrofluctuations of pres-sure and temperature in Mutnovsky and Kuldur fields are 2-4.5 months, maximum amplitudes of temperature in the wells' orifices are 53o C and 9 o C correspondingly, maximum amplitude of pressure in Mutnovsky field 34 bars. Periods of minioscillations are from 10 to 70 minutes in Mutnovsky and Pauzhetsky fields, average amplitudes of pressure are 0.2-0.7 bars. These data are comparable with similar data from Mura basin in Slovenia: amplitudes of temperature and pH minioscillations are about 1-2o C and 0.2 correspondingly; there exists strict positive correlation of temperature with pH, K+, Na+, Ca2+, HCO3-, SO42-, Cl-, F-, but concentra-tions of Mg2+, NH4+, CO2 change independently (Kralj, 2000).. The general conclusion is that minifluctuations of thermodynamic and physic-chemical parameters in hydrothermal sys-tems are usual phenomenon. From time to time the

Comparison of microbial communities associated with three Atlantic ultramafic hydrothermal systems.

Science.gov (United States)

Roussel, Erwan G; Konn, Cécile; Charlou, Jean-Luc; Donval, Jean-Pierre; Fouquet, Yves; Querellou, Joël; Prieur, Daniel; Bonavita, Marie-Anne Cambon

2011-09-01

The distribution of Archaea and methanogenic, methanotrophic and sulfate-reducing communities in three Atlantic ultramafic-hosted hydrothermal systems (Rainbow, Ashadze, Lost City) was compared using 16S rRNA gene and functional gene (mcrA, pmoA and dsrA) clone libraries. The overall archaeal community was diverse and heterogeneously distributed between the hydrothermal sites and the types of samples analyzed (seawater, hydrothermal fluid, chimney and sediment). The Lost City hydrothermal field, characterized by high alkaline warm fluids (pH>11; Tphylum and Methanopyrales order were also retrieved from the Rainbow and Ashadze hydrothermal fluids. However, the methanogenic Methanococcales was the most widely distributed hyper/thermophilic archaeal group among the hot and acidic ultramafic-hosted hydrothermal system environments. Most of the lineages detected are linked to methane and hydrogen cycling, suggesting that in ultramafic-hosted hydrothermal systems, large methanogenic and methanotrophic communities could be fuelled by hydrothermal fluids highly enriched in methane and hydrogen. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

High-pressure apparatus

NARCIS (Netherlands)

Schepdael, van L.J.M.; Bartels, P.V.; Berg, van den R.W.

1999-01-01

The invention relates to a high-pressure device (1) having a cylindrical high-pressure vessel (3) and prestressing means in order to exert an axial pressure on the vessel. The vessel (3) can have been formed from a number of layers of composite material, such as glass, carbon or aramide fibers which

Production of bio-oil via hydrothermal liquefaction of birch sawdust

International Nuclear Information System (INIS)

Malins, Kristaps

2017-01-01

Highlights: • NaOH has significant impact on hydrothermal liquefaction of birch sawdust. • High yield of bio-oil (54.1%) was obtained under developed optimal conditions. • Compounds in bio-oil have appropriate chemical structure for hydrocarbon synthesis. • The yield of marketable solid residue with potential for industrial application was 7.1%. • Solid residue has high calorific value (29.8 MJ/kg) and C content (74.6 wt.%). - Abstract: The effect of weight ratio of plywood manufacturing by-product birch sawdust (BS) to water (1/2–1/8), reaction temperature (200–340 °C), initial H 2 pressure (0–10 MPa), residence time (5–90 min), catalysts amount (0.25–7.0 wt.%) and type (FeSO 4 , ZnSO 4 , NiSO 4 , Raney-nickel, Ni65%/SiO 2 −Al 2 O 3 , Na 2 CO 3 and NaOH) on hydrothermal liquefaction of BS was investigated. High yield of bio-oil (54.1%) with calorific value (CV) 24.9 MJ/kg under developed optimal experimental conditions in the presence of NaOH (5 wt.%) utilizing weight ratio of BS to water 1/4, residence time 5 min, mixing speed 250 rpm at 300 °C without pressurized particular inert gas or H 2 atmosphere was achieved. Compounds in bio-oil analyzed by gas chromatography-mass spectrometry (GC-MS) have suitable chemical structures for conversion into renewable hydrocarbons. Marketable solid residue (SR) with yield 7.1%, high CV (29.8 MJ/kg) and perspective characteristics for industrial application was obtained. Produced gas in process analyzed by gas chromatography-thermal conductivity detector (GC–TCD) contains 60.1 vol.% of CO 2 .

Pressure pressure-balanced pH sensing system for high temperature and high pressure water

International Nuclear Information System (INIS)

Tachibana, Koji

1995-01-01

As for the pH measurement system for high temperature, high pressure water, there have been the circumstances that first the reference electrodes for monitoring corrosion potential were developed, and subsequently, it was developed for the purpose of maintaining the soundness of metallic materials in high temperature, high pressure water in nuclear power generation. In the process of developing the reference electrodes for high temperature water, it was clarified that the occurrence of stress corrosion cracking in BWRs is closely related to the corrosion potential determined by dissolved oxygen concentration. As the types of pH electrodes, there are metal-hydrogen electrodes, glass electrodes, ZrO 2 diaphragm electrodes and TiO 2 semiconductor electrodes. The principle of pH measurement using ZrO 2 diaphragms is explained. The pH measuring system is composed of YSZ element, pressure-balanced type external reference electrode, pressure balancer and compressed air vessel. The stability and pH response of YSZ elements are reported. (K.I.)

Hydrothermal Carbonization of Seaweed For Advanced Biochar Production

Directory of Open Access Journals (Sweden)

Prakoso Tirto

2018-01-01

Full Text Available Seaweed such as Eucheuma Cottonii is a potential source of biomaterialIts high moisture content makes it suitable for hydrothermal conversion process since it doesn’t need to utilize dry feedstock. The aim of this study is to convert the biomass of red seaweed Eucheuma Cottonii into alternative fuels and high value biomaterials using hydrothermal process. The hydrothermal process seaweed Eucheuma Cottonii produce two types of products, liquid product and char (solid. This research focus on the char product. The char from hydrothermal process was then activated using the tubular furnace. The yield for activated char is 7.5 % and results of SEM analysis of activated char showed the formation of allotropes carbon include carbon micro spheres, carbon micro fibres and graphene. These structures have encountered application in a wide range of technological fields, such as adsorption, catalysis, hydrogen storage or electronics.

High Blood Pressure Facts

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... Stroke Heart Disease Cholesterol Salt Million Hearts® WISEWOMAN High Blood Pressure Facts Recommend on Facebook Tweet Share Compartir On ... Top of Page CDC Fact Sheets Related to High Blood Pressure High Blood Pressure Pulmonary Hypertension Heart Disease Signs ...

High Blood Pressure (Hypertension)

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... Print Page Text Size: A A A Listen High Blood Pressure (Hypertension) Nearly 1 in 3 American adults has ... weight. How Will I Know if I Have High Blood Pressure? High blood pressure is a silent problem — you ...

Hydrothermal Synthesis and Biocompatibility Study of Highly Crystalline Carbonated Hydroxyapatite Nanorods

Science.gov (United States)

Xue, Caibao; Chen, Yingzhi; Huang, Yongzhuo; Zhu, Peizhi

2015-08-01

Highly crystalline carbonated hydroxyapatite (CHA) nanorods with different carbonate contents were synthesized by a novel hydrothermal method. The crystallinity and chemical structure of synthesized nanorods were studied by Fourier transform infrared spectroscopy (FTIR), X-ray photo-electronic spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). The biocompatibility of synthesized CHA nanorods was evaluated by cell viability and alkaline phosphatase (ALP) activity of MG-63 cell line. The biocompatibility evaluation results show that these CHA nanorods are biologically active apatites and potentially promising bone-substitute biomaterials for orthopedic application.

The dissociation mechanism and thermodynamic properties of HCl(aq) in hydrothermal fluids (to 700 °C, 60 kbar) by ab initio molecular dynamics simulations

Science.gov (United States)

Mei, Yuan; Liu, Weihua; Brugger, Joël; Sherman, David M.; Gale, Julian D.

2018-04-01

HCl is one of the most significant volatiles in the Earth's crust. It is well established that chloride activity and acidity (pH) play important roles in controlling the solubility of metals in aqueous hydrothermal fluids. Thus, quantifying the dissociation of HCl in aqueous solutions over a wide range of temperature and pressure is crucial for the understanding and numerical modeling of element mobility in hydrothermal fluids. Here we have conducted ab initio molecular dynamics (MD) simulations to investigate the mechanism of HCl(aq) dissociation and to calculate the thermodynamic properties for the dissociation reaction at 25-700 °C, 1 bar to 60 kbar, i.e. including high temperature and pressure conditions that are geologically important, but difficult to investigate via experiments. Our results predict that HCl(aq) tends to associate with increasing temperature, and dissociate with increasing pressure. In particular, HCl(aq) is highly dissociated at extremely high pressures, even at high temperatures (e.g., 60 kbar, 600-700 °C). At 25 °C, the calculated logKd values (6.79 ± 0.81) are close to the value (7.0) recommended by IUPAC (International Union of Pure and Applied Chemistry) and some previous experimental and theoretical studies (Simonson et al.., 1990; Sulpizi and Sprik, 2008, 2010). The MD simulations indicate full dissociation of HCl at low temperature; in contrast, some experiments were interpreted assuming significant association at high HCl concentrations (≥1 m HCltot) even at room T (logKd ∼0.7; e.g., Ruaya and Seward, 1987; Sretenskaya, 1992; review in Tagirov et al., 1997). This discrepancy is most likely the result of difficulties in the experimental determination of minor (if any) concentration of associated HCl(aq) under ambient conditions, and thus reflects differences in the activity models used for the interpretation of the experiments. With increasing temperature, the discrepancy between our MD results and previous experimental

Hydrothermal Processing of Macroalgal Feedstocks in Continuous-Flow Reactors

Energy Technology Data Exchange (ETDEWEB)

Elliott, Douglas C.; Hart, Todd R.; Neuenschwander, Gary G.; Rotness, Leslie J.; Roesijadi, Guri; Zacher, Alan H.; Magnuson, Jon K.

2014-02-03

Wet macroalgal slurries have been converted into a biocrude by hydrothermal liquefaction (HTL) in a bench-scale continuous-flow reactor system. Carbon conversion to a gravity-separable oil product of 58.8% was accomplished at relatively low temperature (350 °C) in a pressurized (subcritical liquid water) environment (20 MPa) when using feedstock slurries with a 21.7% concentration of dry solids. As opposed to earlier work in batch reactors reported by others, direct oil recovery was achieved without the use of a solvent, and biomass trace mineral components were removed by processing steps so that they did not cause processing difficulties. In addition, catalytic hydrothermal gasification (CHG) was effectively applied for HTL byproduct water cleanup and fuel gas production from water-soluble organics. Conversion of 99.2% of the carbon left in the aqueous phase was demonstrated. Finally, as a result, high conversion of macroalgae to liquid and gas fuel products was found with low levels of residual organic contamination in byproduct water. Both process steps were accomplished in continuous-flow reactor systems such that design data for process scale-up was generated.

Hydrothermal carbonization and torrefaction of grape pomace: a comparative evaluation.

Science.gov (United States)

Pala, Mehmet; Kantarli, Ismail Cem; Buyukisik, Hasan Baha; Yanik, Jale

2014-06-01

Grape pomace was treated by hydrothermal carbonization (sub-critical water, 175-275°C) and torrefaction (nitrogen atmosphere, 250 and 300°C), with mass yield of solid product (char) ranging between 47% and 78%, and energy densification ratio to 1.42-1.15 of the original feedstock. The chars were characterised with respect to their fuel properties, morphological and structural properties and combustion characteristics. The hydrothermal carbonization produced the char with greater energy density than torrefaction. The chars from torrefaction were found to be more aromatic in nature than that from hydrothermal carbonization. Hydrothermal carbonization process produced the char having high combustion reactivity. Most interesting was the finding that aqueous phase from hydrothermal carbonization had antioxidant activity. The results obtained in this study showed that HTC appears to be promising process for a winery waste having high moisture content. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hydrothermal diamond-anvil cell: Application to studies of geologic fluids

Science.gov (United States)

Chou, I.-Ming

2003-01-01

The hydrothermal diamond-anvil cell (HDAC) was designed to simulate the geologic conditions of crustal processes in the presence of water or other fluids. The HDAC has been used to apply external pressure to both synthetic and natural fluid inclusions in quartz to minimize problems caused by stretching or decrepitation of inclusions during microthermometric analysis. When the HDAC is loaded with a fluid sample, it can be considered as a large synthetic fluid inclusion and therefore, can be used to study the PVTX properties as well as phase relations of the sample fluid. Because the HDAC has a wide measurement pressure-temperature range and also allows in-situ optical observations, it has been used to study critical phenomena of various chemical systems, such as the geologically important hydrous silicate melts. It is possible, when the HDAC is combined with synchrotron X-ray sources, to obtain basic information on speciation and structure of metal including rare-earth elements (REE) complexes in hydrothermal solutions as revealed by X-ray absorption fine structure (XAFS) spectra. Recent modifications of the HDAC minimize the loss of intensity of X-rays due to scattering and absorption by the diamonds. These modifications are especially important for studying elements with absorption edges below 10 keV and therefore particularly valuable for our understanding of transport and deposition of first-row transition elements and REE in hydrothermal environments.

High pressure effect for high-Tc superconductors

International Nuclear Information System (INIS)

Takahashi, Hiroki; Tomita, Takahiro

2011-01-01

A number of experimental and theoretical studies have been performed to understand the mechanism of high-T c superconductivity and to enhance T c . High-pressure techniques have played a very important role for these studies. In this paper, the high-pressure techniques and physical properties of high-T c superconductor under high pressure are presented. (author)

Effect on High-Intensity Fields of a Tough Hydrophone With Hydrothermal PZT Thick-Film Vibrator and Titanium Front Layer.

Science.gov (United States)

Okada, Nagaya; Takeuchi, Shinichi

2017-07-01

A novel tough hydrophone was fabricated by depositing hydrothermally synthesized lead zirconate titanate polycrystalline film on the back-side surface of a titanium plate. Our developed tough hydrophone resisted damage in a high-pressure field (15 MPa) at a focal point of a sinusoidal continuous wave driven by a concave high-intensity focused ultrasound (HIFU) transducer with up to 50 W of power input to the sound source. The hydrophone was suitable for the HIFU field, even though the hydrophone has a flat-shape tip of 3.5 mm diameter, which is slightly larger than the wavelength of a few megahertz. In this paper, experiments are performed to assess the effect on the HIFU field of changing the shape of the tough hydrophone, with the aim of developing a tough hydrophone. The spatial distribution of the acoustic bubbles around the focal point was visualized by using ultrasonic diagnostic equipment with the tough hydrophone located at the focal point of the HIFU transducer. From the visualization, the trapped acoustic bubbles were seen to arise from the standing wave, which implies that the acoustic pressure is reduced by this cloud of acoustic bubbles that appeared during hydrophone measurement. Although cavitation and acoustic bubbles may be unavoidable when using high-intensity ultrasound, the estimated result of evaluating acoustic fields without misunderstanding by acoustic bubbles can be obtained by the aid of visualizing bubbles around the tough hydrophone.

Base hydrolysis and hydrothermal processing of PBX-9404

International Nuclear Information System (INIS)

Flesner, R.L.; Spontarelli, T.; Dell'Orco, P.C.; Sanchez, J.A.

1994-01-01

Base hydrolysis in combination with hydrothermal processing has been proposed as an environmentally acceptable alternative to open burning/open detonation for degradation and destruction of high explosives. In this report, the authors examine gaseous and aqueous products of base hydrolysis of the HMX-based plastic bonded explosive, PBX-9404. They also examined products from the subsequent hydrothermal treatment of the base hydrolysate. The gases produced from hydrolysis of PBX-9404 are ammonia, nitrous oxide, and nitrogen. Major aqueous products are sodium formate, acetate, nitrate, and nitrite, but not all carbon products have been identified. Hydrothermal processing of base hydrolysate destroyed up to 98% of the organic carbon in solution, and higher destruction efficiencies are possible. Major gas products detected from hydrothermal processing were nitrogen and nitrous oxide

Synthesis of nickel oxide - zirconia composites by coprecipitation route followed by hydrothermal treatment

International Nuclear Information System (INIS)

Yoshito, Walter Kenji; Ussui, Valter; Lazar, Dolores Ribeiro Ricci; Paschoal, Jose Octavio Armani

2009-01-01

Nickel oxide-yttria stabilized zirconia (NiO-YSZ) for use as solid oxide fuel cell anode were synthesized by coprecipitation to obtain amorphous zirconia and crystallized β-nickel gels of the corresponding metal hydroxides. Hydrothermal treatment at 200°C and 220 psi from 2 up to 16 hours, under stirring, was performed to produce nanocrystalline powder. The as-synthesized powders were uniaxially pressed and sintered in air. Powders were characterized by X-ray diffraction, laser scattering, scanning and transmission electron microscopy (SEM/TEM), gas adsorption technique (BET) and TGDTA thermal analysis. Ceramic samples were characterized by dilatometric analysis and density measurements by Archimedes method. The characteristics of hydrothermally synthesized powders and compacts were compared to those produced without temperature and pressure application. Crystalline powders were obtained after hydrothermal process, excluding the calcination step from this route. The specific surface area of powders decreases with increasing time of hydrothermal treatment while the agglomerate mean size is not affected by this parameter. (author)

Fractionation of boron isotopes in Icelandic hydrothermal systems

International Nuclear Information System (INIS)

Aggarwal, J.K.

1995-01-01

Boron isotope ratios have been determined in a variety of different geothermal waters from hydrothermal systems across Iceland. Isotope ratios from the high temperature meteoric water recharged systems reflect the isotope ratio of the host rocks without any apparent fractionation. Seawater recharged geothermal systems exhibit more positive δ 1 1B values than the meteoric water recharged geothermal systems. Water/rock ratios can be assessed from boron isotope ratios in the saline hydrothermal systems. Low temperature hydrothermal systems also exhibit more positive δ 1 1B than the high temperature systems, indicating fractionation of boron due to absorption of the lighter isotope onto secondary minerals. Fractionation of boron in carbonate deposits may indicate the level of equilibrium attained within the systems. (author). 14 refs., 2 figs

Evolution of Morphology and Crystallinity of Silica Minerals Under Hydrothermal Conditions

Science.gov (United States)

Isobe, H.

2011-12-01

Silica minerals are quite common mineral species in surface environment of the terrestrial planets. They are good indicator of terrestrial processes including hydrothermal alteration, diagenesis and soil formation. Hydrothermal quartz, metastable low temperature cristobalite and amorphous silica show characteristic morphology and crystallinity depending on their formation processes and kinetics under wide range of temperature, pressure, acidity and thermal history. In this study, silica minerals produced by acidic hydrothermal alteration related to volcanic activities and hydrothermal crystallization experiments from diatom sediment are examined with crystallographic analysis and morphologic observations. Low temperature form of cistobalite is a metastable phase and a common alteration product occured in highly acidic hydrothermal environment around fumaroles in geothermal / volcanic areas. XRD analysis revealed that the alteration degree of whole rock is represented by abundance of cristobalite. Detailed powder XRD analysis show that the primary diffraction peak of cristobalite composed with two or three phases with different d-spacing and FWHM by peak profile fitting analysis. Shorter d-spacing and narrower FWHM cristobalite crystallize from precursor materials with less-crystallized, longer d-spacing and wider FWHM cristobalite. Textures of hydrothermal cristobalite in altered rock shows remnant of porphylitic texture of the host rock, pyroxene-amphibole andesite. Diatom has amorphous silica shell and makes diatomite sediment. Diatomite found in less diagenetic Quarternary formation keeps amorphous silica diatom shells. Hydrothermal alteration experiments of amorphous silica diatomite sediment are carried out from 300 °C to 550 °C. Mineral composition of run products shows crystallization of cristobalite and quartz progress depending on temperature and run durations. Initial crystallization product, cristobalite grains occur as characteristic lepispheres and

Mechanisms involved in the hydrothermal growth of ultra-thin and high aspect ratio ZnO nanowires

Energy Technology Data Exchange (ETDEWEB)

Demes, Thomas [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Ternon, Céline, E-mail: celine.ternon@grenoble-inp.fr [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, LTM, F-38000 Grenoble (France); Morisot, Fanny [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, Grenoble-INP" 2, IMEP-LaHC, F-38000 Grenoble (France); Riassetto, David [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Legallais, Maxime [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, Grenoble-INP" 2, IMEP-LaHC, F-38000 Grenoble (France); Roussel, Hervé; Langlet, Michel [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France)

2017-07-15

Highlights: • ZnO nanowires are grown on sol-gel ZnO seed layers by hydrothermal synthesis. • Ultra-thin and high aspect ratio nanowires are obtained without using additives. • Nanowire diameter is 20–25 nm regardless of growth time and seed morphology. • A nanowire growth model is developed on the basis of thermodynamic considerations. • The nanowires are intended for integration into electrically conductive nanonets. - Abstract: Hydrothermal synthesis of ZnO nanowires (NWs) with tailored dimensions, notably high aspect ratios (AR) and small diameters, is a major concern for a wide range of applications and still represents a challenging and recurring issue. In this work, an additive-free and reproducible hydrothermal procedure has been developed to grow ultra-thin and high AR ZnO NWs on sol-gel deposited ZnO seed layers. Controlling the substrate temperature and using a low reagent concentration (1 mM) has been found to be essential for obtaining such NWs. We show that the NW diameter remains constant at about 20–25 nm with growth time contrary to the NW length that can be selectively increased leading to NWs with ARs up to 400. On the basis of investigated experimental conditions along with thermodynamic and kinetic considerations, a ZnO NW growth mechanism has been developed which involves the formation and growth of nuclei followed by NW growth when the nuclei reach a critical size of about 20–25 nm. The low reagent concentration inhibits NW lateral growth leading to ultra-thin and high AR NWs. These NWs have been assembled into electrically conductive ZnO nanowire networks, which opens attractive perspectives toward the development of highly sensitive low-cost gas- or bio-sensors.

A flow-through hydrothermal cell for in situ neutron diffraction studies of phase transformations

International Nuclear Information System (INIS)

O'Neill, Brian; Tenailleau, Christophe; Nogthai, Yung; Studer, Andrew; Brugger, Joel; Pring, Allan

2006-01-01

A flow-through hydrothermal cell for the in situ neutron diffraction study of crystallisation and phase transitions has been developed. It can be used for kinetic studies on materials that exhibit structural transformations under hydrothermal conditions. It is specifically designed for use on the medium-resolution powder diffractometer (MRPD) at ANSTO, Lucas Heights, Sydney. But it is planned to adapt the design for the Polaris beamline at ISIS and the new high-intensity powder diffractometer (Wombat) at the new Australian reactor Opal. The cell will operate in a flow-through mode over the temperature range from 25-300 deg. C and up to pressures of 100 bar. The first results of a successful transformation of pentlandite (Fe,Ni) 9 S 8 to violarite (Fe,Ni) 3 S 4 under mild conditions (pH∼4) at 120 deg. C and 3 bar using in situ neutron diffraction measurements are presented

Hydrothermal stability of SAPO-34 for refrigeration and air conditioning applications

International Nuclear Information System (INIS)

Chen, Haijun; Cui, Qun; Wu, Juan; Zhu, Yuezhao; Li, Quanguo; Zheng, Kai; Yao, Huqing

2014-01-01

Graphical abstract: The SAPO-34 was synthesized by a hydrothermal method using diethylamine as a template. Water adsorption strength on SAPO-34 is between that on 13X and A type silica gel. During 100–400 Pa, the water uptake on SAPO-34 increases sensitively to pressure, and equilibrium water uptake reaches 0.35 kg/kg, 25% higher than 13X. SAPO-34 shows no significant reduced cyclic water uptake over 60 cycles. Most of the initial SAPO-34 phase is restored, while the regular cubic-like morphology is well maintained, and the specific surface area only decreases by 8.6%. - Highlights: • Water adsorption strength on SAPO-34 is between that on 13X and A type silica gel. During 100–400 Pa, the water uptake on SAPO-34 increases sensitively to pressure, and equilibrium water uptake reaches 0.35 kg/kg, 25% higher than 13X. • SAPO-34 with diethylamine as the template shows no significant reduced cyclic water uptake over 60 cycles, and most of the initial SAPO-34 phase is well maintained. • SAPO-34 has an excellent adsorption performance and a good hydrothermal stability, thus is promising for application in adsorption refrigeration. - Abstract: Hydrothermal stability is one of the crucial factors in applying SAPO-34 molecular sieve to adsorption refrigration. The SAPO-34 was synthesized by a hydrothermal method using diethylamine as a template. Both a vacuum gravimetric method and an intelligent gravimetric analyzer were applied to analyze the water adsorption performance of SAPO-34. Cyclic hydrothermal performance was determined on the modified simulation adsorption refrigeration test rig. Crystal phase, morphology, and porosity of SAPO-34 were characterized by X-ray diffraction, scanning electron microscopy, and N 2 sorption, respectively. The results show that, water adsorption strength on SAPO-34 is between that on 13X and A type silica gel. During 100–400 Pa, the water uptake on SAPO-34 increases sensitively to pressure, and equilibrium water uptake reaches

Hydrothermal stability of SAPO-34 for refrigeration and air conditioning applications

Energy Technology Data Exchange (ETDEWEB)

Chen, Haijun [Jiangsu Key Laboratory of Process Enhancement and New Energy Equipment Technology, School of Mechanical and Power Engineering, Nanjing Tech University (China); Cui, Qun, E-mail: cuiqun@njtech.edu.cn [College of Chemistry and Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Gulou District, Nanjing 210009 (China); Wu, Juan; Zhu, Yuezhao [Jiangsu Key Laboratory of Process Enhancement and New Energy Equipment Technology, School of Mechanical and Power Engineering, Nanjing Tech University (China); Li, Quanguo; Zheng, Kai; Yao, Huqing [College of Chemistry and Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Gulou District, Nanjing 210009 (China)

2014-04-01

Graphical abstract: The SAPO-34 was synthesized by a hydrothermal method using diethylamine as a template. Water adsorption strength on SAPO-34 is between that on 13X and A type silica gel. During 100–400 Pa, the water uptake on SAPO-34 increases sensitively to pressure, and equilibrium water uptake reaches 0.35 kg/kg, 25% higher than 13X. SAPO-34 shows no significant reduced cyclic water uptake over 60 cycles. Most of the initial SAPO-34 phase is restored, while the regular cubic-like morphology is well maintained, and the specific surface area only decreases by 8.6%. - Highlights: • Water adsorption strength on SAPO-34 is between that on 13X and A type silica gel. During 100–400 Pa, the water uptake on SAPO-34 increases sensitively to pressure, and equilibrium water uptake reaches 0.35 kg/kg, 25% higher than 13X. • SAPO-34 with diethylamine as the template shows no significant reduced cyclic water uptake over 60 cycles, and most of the initial SAPO-34 phase is well maintained. • SAPO-34 has an excellent adsorption performance and a good hydrothermal stability, thus is promising for application in adsorption refrigeration. - Abstract: Hydrothermal stability is one of the crucial factors in applying SAPO-34 molecular sieve to adsorption refrigration. The SAPO-34 was synthesized by a hydrothermal method using diethylamine as a template. Both a vacuum gravimetric method and an intelligent gravimetric analyzer were applied to analyze the water adsorption performance of SAPO-34. Cyclic hydrothermal performance was determined on the modified simulation adsorption refrigeration test rig. Crystal phase, morphology, and porosity of SAPO-34 were characterized by X-ray diffraction, scanning electron microscopy, and N{sub 2} sorption, respectively. The results show that, water adsorption strength on SAPO-34 is between that on 13X and A type silica gel. During 100–400 Pa, the water uptake on SAPO-34 increases sensitively to pressure, and equilibrium water uptake

Hydrothermally synthesized PZT film grown in highly concentrated KOH solution with large electromechanical coupling coefficient for resonator

Science.gov (United States)

Feng, Guo-Hua; Lee, Kuan-Yi

2017-12-01

This paper presents a study of lead zirconate titanate (PZT) films hydrothermally grown on a dome-shaped titanium diaphragm. Few articles in the literature address the implementation of hydrothermal PZT films on curved-diaphragm substrates for resonators. In this study, a 50-μm-thick titanium sheet is embossed using balls of designed dimensions to shape a dome-shaped cavity array. Through single-process hydrothermal synthesis, PZT films are grown on both sides of the processed titanium diaphragm with good adhesion and uniformity. The hydrothermal synthesis process involves a high concentration of potassium hydroxide solution and excess amounts of lead acetate and zirconium oxychloride octahydrate. Varied deposition times and temperatures of PZT films are investigated. The grown films are characterized by X-ray diffraction and scanning electron microscopy. The 10-μm-thick PZT dome-shaped resonators with 60- and 20-μm-thick supporting layers are implemented and further tested. Results for both resonators indicate that large electromechanical coupling coefficients and a series resonance of 95 MHz from 14 MHz can be attained. The device is connected to a complementary metal-oxide-semiconductor integrated circuit for analysis of oscillator applications. The oscillator reaches a Q value of 6300 in air. The resonator exhibits a better sensing stability when loaded with water when compared with air.

High pressure X-ray studies

International Nuclear Information System (INIS)

Sikka, S.K.

1981-01-01

High pressure research has already led to new insights in the physical properties of materials and at times to the synthesis of new ones. In all this, X-ray diffraction has been a valuable diagnostic experimental tool. In particular, X-rays in high pressure field have been used (a) for crystallographic identification of high pressure polymorphs and (b) for study of the effect of pressure on lattice parameters and volume under isothermal conditions. The results in the area (a) are reviewed. The techniques of applying high pressures are described. These include both static and dynamic shockwave X-ray apparatus. To illustrate the effect of pressure, some of the pressure induced phase transitions in pure metals are described. It has been found that there is a clear trend for elements in any group of the periodic table to adopt similar structures at high pressures. These studies have enabled to construct generalized phase diagrams for many groups. In the case of alloys, the high pressure work done on Ti-V alloys is presented. (author)

High Blood Pressure (Hypertension) (For Parents)

Science.gov (United States)

... Safe Videos for Educators Search English Español Hypertension (High Blood Pressure) KidsHealth / For Parents / Hypertension (High Blood Pressure) What's ... High Blood Pressure) Treated? Print What Is Hypertension (High Blood Pressure)? Blood pressure is the pressure of blood against ...

High-pressure crystallography

Science.gov (United States)

Katrusiak, A.

2008-01-01

The history and development of high-pressure crystallography are briefly described and examples of structural transformations in compressed compounds are given. The review is focused on the diamond-anvil cell, celebrating its 50th anniversary this year, the principles of its operation and the impact it has had on high-pressure X-ray diffraction.

Cryogenic, Absolute, High Pressure Sensor

Science.gov (United States)

Chapman, John J. (Inventor); Shams. Qamar A. (Inventor); Powers, William T. (Inventor)

2001-01-01

A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

Cryogenic High Pressure Sensor Module

Science.gov (United States)

Chapman, John J. (Inventor); Shams, Qamar A. (Inventor); Powers, William T. (Inventor)

1999-01-01

A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

Deformation of a Volcanic Edifice by Pore Pressurization: An Analog Approach

Science.gov (United States)

Hyman, D.; Bursik, M. I.

2015-12-01

Volcanic flank destabilization, preceded by pressurization-induced surface deformation or weakening, presents a significant hazard at stratovolcanoes with ample supply of magmatic volatiles or preexisting hydrothermal systems as in Bezymianny- and Bandai-type eruptions, respectively. Deformation is also an important sign of the nature of unrest at large calderas such as Long Valley, USA. Previous studies of volcanic inflation have focused primarily on the role of ascending magma. Relatively few studies have centered on surface deformation caused by pressurization from other volcanic fluids, including exsolved volatiles and pressurized hydrothermal systems. Most investigations of pore-pressurization have focused on numerical modelling of pore pressure transients. In analog experiments presented here, pore-filling fluids are injected into the base of a damp sand medium without exceeding dike propagating pressures, simulating the pressurization and bulk-permeable flow of volatile fluids through volcanic systems. The experiments examine surface deformation from a range of source depths and pressures as well as edifice geometries. 3D imaging is possible through use of the Microsoft® Kinect™ sensor, which allows for the generation of high-resolution, high frame rate, lab-scale Digital Elevation Models (DEMs). After initial processing to increase signal-to-noise ratio, surface deformation is measured using the DEM time-series generated by the Kinect™. Analysis of preliminary experiments suggests that inflation is possible up to approx. 10 % of pressure source depth. We also show that the Kinect™ sensor is useful in analog volcanological studies, an environment to which it is well-suited.

Hydrothermal synthesis of high surface area ZIF-8 with minimal use of TEA

Science.gov (United States)

Butova, V. V.; Budnyk, A. P.; Bulanova, E. A.; Lamberti, C.; Soldatov, A. V.

2017-07-01

In this paper we present, for the first time, a simple hydrothermal recipe for the synthesis of ZIF-8 Metal-Organic Framework (MOF) with a large specific surface area (1340 m2/g by BET). An important feature of the method is that the product forms in aqueous medium under standard hydrothermal conditions without DMF and great excess of linker with the use of TEA as structure directing agent. The ZIF-8 crystal phase of the product was confirmed by XRD; this technique has been also exploited to check the crystallinity and to follow the changes in the MOF structure induced by heating. TGA and temperature dependent XRD testify the high thermal stability of the material (470 °C in N2 and at 400 °C in air). The IR spectral profile of the material provides a complete picture of vibrations assigned to the linker and the metal center. The systematic investigation of the products obtained by increasing the TEA amount in the reacting medium from 0 to 25.5 mol equivalent Zn2+, allowed us to understand its role and to find 2.6 mol equivalent Zn2+ as the minimum amount needed to obtain a single phase ZIF-8 material with the high standard reported above. The stability of the material under severe basic conditions makes it a promising candidate in heterogeneous catalysis. The material has shown high capacity in I2 uptake, making it interesting also for selective molecular adsorption.

High-Tc superconductors under very high pressure

International Nuclear Information System (INIS)

Wijngaarden, R.J.; Scholtz, J.J.; Eenige, E.N. van; Griessen, R.

1991-01-01

High pressure has played a crucial role in the short history of high T c superconductors. Soon after the discovery of superconductivity by Bednorz and Muller in La-Ba-Cu-O, Chu et al. showed that the critical temperature T c could be significantly increased by pressure. This observation led to the discovery of YBa 2 Cu 3 O 7 by Wu et al. with a T c above 90 K. Incidentally, this high T c is probably also due to the fact that YBa 2 Cu 3 O 7 has two CuO 2 layers per unit cell instead of a single one in La-Ba-Cu-O. The authors discuss the high pressure dependence of the oxide superconductors, particularly at pressures above 10 GPa, and the nonmonotonic dependence of transition temperature on pressure

Mineralogy and geological significance of hydrothermal deposits from the Okinawa Trough

Science.gov (United States)

Zhang, Xia; Zhai, Shikui; Yu, Zenghui; Wang, Shujie; Cai, Zongwei

2018-04-01

The study of hydrothermal deposits in the Okinawa Trough can help us to uncover the hydrothermal mineralization characteristics in the back-arc basin during the early expanding stage. Mineralogy and geological significance of hydrothermal deposits from both the middle and southern trough are studied in this paper. First of all, using optical microscope to confirm the mineral compositions, characteristics of crystal shape, paragenetic relationship and minerals crystallization order. Then the minerals chemical composition were analyzed in virtue of electron microprobe. On these basis, the paragenetic sequence and the mineralization characteristics of the hydrothermal deposits were discussed. The results show that the hydrothermal deposit from the mid-Okinawa Trough belongs to Zn-Cu-rich type, consisting dominantly of sulfide minerals such as sphalerite, chalcopyrite, pyrite, etc. The minerals crystallization order is first generation pyrite(PyI)-sphalerite-chalcopyrite-galena-second generation pyrite(PyII)-amorphous silica. While the deposit from the southern Okinawa Trough is Ba-Zn-Pb-rich type mainly composing of barite, sphalerite, galena, etc. The minerals crystallization order is barite-pyrite-sphalerite-tetrahedrite-galena-chalcopyrite-amorphous silica. Hydrothermal fluid temperature in the mid-Okinawa Trough undergoes a process from high to low, which is high up to 350 °C in the early stage, but decreasing gradually with the evolution of hydrothermal fluid. On the contrary, the hydrothermal activity in the southern Okinawa Trough is low temperature dominated, but the mineralization environment is unstable and the fluid temperature changes drastically during the period of hydrothermal activity.

Processing of Microalgae: Acoustic Cavitation and Hydrothermal Conversion

Science.gov (United States)

Greenly, Justin Michael

The production of energy dense fuels from renewable algal biomass feedstocks -- if sustainably developed at a sufficiently large scale -- may reduce the consumption of petroleum from fossil fuels and provide many environmental benefits. Achieving economic feasibility has several technical engineering challenges that arise from dilute concentration of growing algae in aqueous media, small cell sizes, and durable cell walls. For microalgae to be a sustainable source of biofuels and co-products, efficient fractionation and conversion of the cellular contents is necessary. Research was carried out to address two processing options for efficient microalgae biofuel production: 1. Ultrasonic cavitation for cell disruption and 2. Hydrothermal conversion of a model algal triglyceride. 1. Ultrasonic cell disruption, which relies on cavitating bubbles in the suspension to produce damaging shock waves, was investigated experimentally over a range of concentrations and species types. A few seconds of high intensity sonication at fixed frequency yielded significant cell disruption, even for the more durable cells. At longer exposure times, effectiveness was seen to decline and was attributed, using acoustic measurements, to ultrasonic power attenuation in the ensuing cloud of cavitating bubbles. Processing at higher cell concentrations slowed cell disintegration marginally, but increased the effectiveness of dissipating ultrasonic energy. A theoretical study effectively predicted optimal conditions for a variety of parameters that were inaccessible in this experimental investigation. In that study, single bubble collapse was modeled to identify operating conditions that would increase cavitation, and thus cell disruption. Simulations were conducted by varying frequency and pressure amplitude of the ultrasound wave, and initial bubble size. The simulation results indicated that low frequency, high sound wave amplitudes, and small initial bubble size generate the highest shock

The pH and pCO2 dependence of sulfate reduction in shallow-sea hydrothermal CO2 - venting sediments (Milos Island, Greece).

Science.gov (United States)

Bayraktarov, Elisa; Price, Roy E; Ferdelman, Timothy G; Finster, Kai

2013-01-01

Microbial sulfate reduction (SR) is a dominant process of organic matter mineralization in sulfate-rich anoxic environments at neutral pH. Recent studies have demonstrated SR in low pH environments, but investigations on the microbial activity at variable pH and CO2 partial pressure are still lacking. In this study, the effect of pH and pCO2 on microbial activity was investigated by incubation experiments with radioactive (35)S targeting SR in sediments from the shallow-sea hydrothermal vent system of Milos, Greece, where pH is naturally decreased by CO2 release. Sediments differed in their physicochemical characteristics with distance from the main site of fluid discharge. Adjacent to the vent site (T ~40-75°C, pH ~5), maximal sulfate reduction rates (SRR) were observed between pH 5 and 6. SR in hydrothermally influenced sediments decreased at neutral pH. Sediments unaffected by hydrothermal venting (T ~26°C, pH ~8) expressed the highest SRR between pH 6 and 7. Further experiments investigating the effect of pCO2 on SR revealed a steep decrease in activity when the partial pressure increased from 2 to 3 bar. Findings suggest that sulfate reducing microbial communities associated with hydrothermal vent system are adapted to low pH and high CO2, while communities at control sites required a higher pH for optimal activity.

Reconstruction of Ancestral Hydrothermal Systems on Mount Rainier Using Hydrothermally Altered Rocks in Holocene Debris Flows and Tephras

Science.gov (United States)

John, D. A.; Breit, G. N.; Sisson, T. W.; Vallance, J. W.; Rye, R. O.

2005-12-01

Mount Rainier is the result of episodic stages of edifice growth during periods of high eruptive activity and edifice destruction during periods of relative magmatic quiescence over the past 500 kyr. Edifice destruction occurred both by slow erosion and by catastrophic collapses, some of which were strongly influenced by hydrothermal alteration. Several large-volume Holocene debris-flow deposits contain abundant clasts of hydrothermally altered rocks, most notably the 4-km3 clay-rich Osceola Mudflow which formed by collapse of the northeast side and upper 1000+ m of the edifice about 5600 ya and flowed >120 km downstream into Puget Sound. Mineral assemblages and stable isotope data of hydrothermal alteration products in Holocene debris-flow deposits indicate formation in distinct hydrothermal environments, including magmatic-hydrothermal, steam-heated (including a large fumarolic component), magmatic steam (including a possible fumarolic component), and supergene. The Osceola Mudflow and phreatic components of coeval tephras contain the highest-temperature and inferred most deeply formed alteration minerals; assemblages include magmatic-hydrothermal quartz-alunite, quartz-topaz, quartz-pyrophyllite and quartz-illite (all +pyrite), in addition to steam-heated opal-alunite-kaolinite and abundant smectite-pyrite. In contrast, the Paradise lahar, which formed by a collapse of the surficial upper south side of the edifice, contains only steam-heated assemblages including those formed largely above the water table from condensation of fumarolic vapor (opal-alunite-jarosite). Younger debris-flow deposits on the west side of the volcano (Round Pass lahar and Electron Mudflow) contain only smectite-pyrite alteration, whereas an early 20th century rock avalanche on Tahoma Glacier also contains magmatic-hydrothermal alteration that is exposed in the avalanche headwall of Sunset Amphitheater. Mineralogy and isotopic composition of the alteration phases, geologic and

Dynamic Modeling and Validation of a Biomass Hydrothermal Pretreatment Process - A Demonstration Scale Study

DEFF Research Database (Denmark)

Prunescu, Remus Mihail; Blanke, Mogens; Jakobsen, Jon Geest

2015-01-01

for the enzymatic hydrolysis process. Several by-products are also formed, which disturb and act as inhibitors downstream. The objective of this study is to formulate and validate a large scale hydrothermal pretreatment dynamic model based on mass and energy balances, together with a complex conversion mechanism......Hydrothermal pretreatment of lignocellulosic biomass is a cost effective technology for second generation biorefineries. The process occurs in large horizontal and pressurized thermal reactors where the biomatrix is opened under the action of steam pressure and temperature to expose cellulose...... and kinetics. The study includes a comprehensive sensitivity and uncertainty analysis, with parameter estimation from real-data in the 178-185° range. To highlight the application utility of the model, a state estimator for biomass composition is developed. The predictions capture well the dynamic trends...

High performance dye-sensitized solar cell based on hydrothermally deposited multiwall carbon nanotube counter electrode

Science.gov (United States)

Siriroj, Sumeth; Pimanpang, Samuk; Towannang, Madsakorn; Maiaugree, Wasan; Phumying, Santi; Jarernboon, Wirat; Amornkitbamrung, Vittaya

2012-06-01

Conductive glass was coated with multiwall carbon nanotubes (MWCNTs) by a hydrothermal method. MWCNTs films were subsequently used as dye-sensitized solar cell (DSSC) counter electrodes. The performance of hydrothermal MWCNT DSSC was ˜2.37%. After film annealing in an Ar atmosphere, annealed-hydrothermal MWCNT (AHT-CNT) DSSC efficiency was significantly increased to ˜7.66%, in comparison to ˜8.01% for sputtered-Pt DSSC. Improvement of AHT-CNT DSSC performance is attributed to a decrease in charge-transfer resistance from 1500 Ω to 30 Ω as observed by electrochemical impedance spectroscopy.

Controlling your high blood pressure

Science.gov (United States)

... medlineplus.gov/ency/patientinstructions/000101.htm Controlling your high blood pressure To use the sharing features on this page, ... JavaScript. Hypertension is another term used to describe high blood pressure. High blood pressure can lead to: Stroke Heart ...

High pressure study of high-temperature superconductors

Energy Technology Data Exchange (ETDEWEB)

Souliou, Sofia-Michaela

2014-09-29

The current thesis studies experimentally the effect of high external pressure on high-T{sub c} superconductors. The structure and lattice dynamics of several members of the high-T{sub c} cuprate and Fe-based superconductors families were investigated by means of Raman spectroscopy and X-ray diffraction under well-controlled, hydrostatic high pressure and low temperature conditions. The lattice dynamics of the high-T{sub c} superconductor YBa{sub 2}Cu{sub 3}O{sub 6+x} have been investigated systematically by Raman spectroscopy as a function of doping (x = 0.95, 0.75, 0.60, 0.55, and 0.45) and external pressure. Under ambient pressure conditions, in addition to the Raman modes expected from group theory, we observe new Raman active phonons upon cooling the underdoped samples, at temperatures well above the superconducting transition temperature. The doping dependence and the onset temperatures of the new Raman features suggest that they are associated with the incommensurate charge density wave (CDW) state recently discovered in underdoped cuprates using synchrotron X-ray scattering techniques. Under high pressure conditions (from 2 to 12 GPa), our Raman measurements on highly ordered underdoped YBa{sub 2}Cu{sub 3}O{sub 6.55} samples do not show any of the new Raman phonons seen at ambient pressure. High pressure and low temperature Raman measurements have been performed on the underdoped superconductor YBa{sub 2}Cu{sub 4}O{sub 8}. A clear renormalization of some of the Raman phonons is seen below T{sub c} as a result of the changes in the phonon self-energy upon the opening of the superconducting gap, with the most prominent one being that of the B{sub 1g}-like buckling phonon mode. The amplitude of this renormalization strongly increases with pressure, resembling the effect of hole doping in YBa{sub 2}Cu{sub 3}O{sub 6+x}. At ∝ 10 GPa, the system undergoes a reversible pressure-induced structural phase transition to a non-centrosymmmetric structure (space group

High pressure study of high-temperature superconductors

International Nuclear Information System (INIS)

Souliou, Sofia-Michaela

2014-01-01

The current thesis studies experimentally the effect of high external pressure on high-T c superconductors. The structure and lattice dynamics of several members of the high-T c cuprate and Fe-based superconductors families were investigated by means of Raman spectroscopy and X-ray diffraction under well-controlled, hydrostatic high pressure and low temperature conditions. The lattice dynamics of the high-T c superconductor YBa 2 Cu 3 O 6+x have been investigated systematically by Raman spectroscopy as a function of doping (x = 0.95, 0.75, 0.60, 0.55, and 0.45) and external pressure. Under ambient pressure conditions, in addition to the Raman modes expected from group theory, we observe new Raman active phonons upon cooling the underdoped samples, at temperatures well above the superconducting transition temperature. The doping dependence and the onset temperatures of the new Raman features suggest that they are associated with the incommensurate charge density wave (CDW) state recently discovered in underdoped cuprates using synchrotron X-ray scattering techniques. Under high pressure conditions (from 2 to 12 GPa), our Raman measurements on highly ordered underdoped YBa 2 Cu 3 O 6.55 samples do not show any of the new Raman phonons seen at ambient pressure. High pressure and low temperature Raman measurements have been performed on the underdoped superconductor YBa 2 Cu 4 O 8 . A clear renormalization of some of the Raman phonons is seen below T c as a result of the changes in the phonon self-energy upon the opening of the superconducting gap, with the most prominent one being that of the B 1g -like buckling phonon mode. The amplitude of this renormalization strongly increases with pressure, resembling the effect of hole doping in YBa 2 Cu 3 O 6+x . At ∝ 10 GPa, the system undergoes a reversible pressure-induced structural phase transition to a non-centrosymmmetric structure (space group Imm2). The structural transition is clearly reflected in the high pressure

Sb{sub 2}Te{sub 3} nanobelts and nanosheets: Hydrothermal synthesis, morphology evolution and thermoelectric properties

Energy Technology Data Exchange (ETDEWEB)

Dong, Guo-Hui [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhu, Ying-Jie, E-mail: y.j.zhu@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Cheng, Guo-Feng; Ruan, Yin-Jie [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

2013-02-15

Graphical abstract: Sb{sub 2}Te{sub 3} nanobelts and nanosheets were synthesized by a hydrothermal method, and the morphology evolution from Sb{sub 2}Te{sub 3} nanobelts to nanosheets with the prolonging hydrothermal time was observed. Highlights: Black-Right-Pointing-Pointer Hydrothermal synthesis of Sb{sub 2}Te{sub 3} nanobelts and nanosheets is demonstrated. Black-Right-Pointing-Pointer The morphology of Sb{sub 2}Te{sub 3} can be adjusted by varying hydrothermal time. Black-Right-Pointing-Pointer The morphology evolution of Sb{sub 2}Te{sub 3} from nanobelts to nanosheets is observed. Black-Right-Pointing-Pointer High Seebeck coefficients (S) of Sb{sub 2}Te{sub 3} nanobelts and nanosheets are attained. - Abstract: Sb{sub 2}Te{sub 3} nanobelts and nanosheets were synthesized by a hydrothermal method using SbCl{sub 3} and TeO{sub 2} as the antimony and tellurium source, hydrazine hydrate as a reducing reagent, polyvinyl alcohol as a surfactant and water as the solvent. The effects of experimental parameters on the product were investigated. The experiments indicated that the elemental Te formed during the reaction, acting as a reactive and self-sacrificial template for the formation of Sb{sub 2}Te{sub 3} nanobelts. The morphology evolution from Sb{sub 2}Te{sub 3} nanobelts to nanosheets with the prolonging hydrothermal time was observed. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), selected area electron diffraction (SAED), Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The thermoelectric properties of the tablet samples of Sb{sub 2}Te{sub 3} nanostructured powders with different morphologies prepared by a room-temperature pressurized method were investigated.

Hydrothermal treatment for inactivating some hygienic microbial indicators from food waste-amended animal feed.

Science.gov (United States)

Jin, Yiying; Chen, Ting; Li, Huan

2012-07-01

To achieve the hygienic safety of food waste used as animal feed, a hydrothermal treatment process of 60-110 degrees C for 10-60 min was applied on the separated food waste from a university canteen. Based on the microbial analysis of raw waste, the inactivation of hygienic indicators of Staphylococcus aureus (SA), total coliform (TC), total aerobic plate counts (TPC), and molds and yeast (MY) were analyzed during the hydrothermal process. Results showed that indicators' concentrations were substantially reduced after hydrothermal treatment, with a greater reduction observed when the waste was treated with a higher temperature and pressure and a longer ramping time. The 110 degrees C hydrothermal treatment for 60 min was sufficient to disinfect food waste as animal feed from the viewpoint of hygienic safety. Results obtained so far indicate that hydrothermal treatment can significantly decrease microbial indicators' concentrations but does not lead to complete sterilization, because MY survived even after 60 min treatment at 110 degrees C. The information from the present study will contribute to the microbial risk control of food waste-amended animal feed, to cope with legislation on food or feed safety.

Pore structure modification of diatomite as sulfuric acid catalyst support by high energy electron beam irradiation and hydrothermal treatment

International Nuclear Information System (INIS)

Li, Chong; Zhang, Guilong; Wang, Min; Chen, Jianfeng; Cai, Dongqing; Wu, Zhengyan

2014-01-01

Highlights: • High energy electron beam (HEEB) irradiation and hydrothermal treatment were used. • HEEB irradiation could make the impurities in the pores of diatomite loose. • Hydrothermal treatment (HT) could remove these impurities from the pores. • They could effectively improve pore size distribution and decrease the bulk density. • Catalytic performance of the corresponding catalyst was significantly improved. - Abstract: High energy electron beam (HEEB) irradiation and hydrothermal treatment (HT), were applied in order to remove the impurities and enlarge the pore size of diatomite, making diatomite more suitable to be a catalyst support. The results demonstrated that, through thermal, charge, impact and etching effects, HEEB irradiation could make the impurities in the pores of diatomite loose and remove some of them. Then HT could remove rest of them from the pores and contribute significantly to the modification of the pore size distribution of diatomite due to thermal expansion, water swelling and thermolysis effects. Moreover, the pore structure modification improved the properties (BET (Brunauer–Emmett–Teller) specific surface area, bulk density and pore volume) of diatomite and the catalytic efficiency of the catalyst prepared from the treated diatomite

Pore structure modification of diatomite as sulfuric acid catalyst support by high energy electron beam irradiation and hydrothermal treatment

Energy Technology Data Exchange (ETDEWEB)

Li, Chong [Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Guilong; Wang, Min [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Chen, Jianfeng [Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China); Cai, Dongqing, E-mail: dqcai@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Wu, Zhengyan, E-mail: zywu@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China)

2014-08-15

Highlights: • High energy electron beam (HEEB) irradiation and hydrothermal treatment were used. • HEEB irradiation could make the impurities in the pores of diatomite loose. • Hydrothermal treatment (HT) could remove these impurities from the pores. • They could effectively improve pore size distribution and decrease the bulk density. • Catalytic performance of the corresponding catalyst was significantly improved. - Abstract: High energy electron beam (HEEB) irradiation and hydrothermal treatment (HT), were applied in order to remove the impurities and enlarge the pore size of diatomite, making diatomite more suitable to be a catalyst support. The results demonstrated that, through thermal, charge, impact and etching effects, HEEB irradiation could make the impurities in the pores of diatomite loose and remove some of them. Then HT could remove rest of them from the pores and contribute significantly to the modification of the pore size distribution of diatomite due to thermal expansion, water swelling and thermolysis effects. Moreover, the pore structure modification improved the properties (BET (Brunauer–Emmett–Teller) specific surface area, bulk density and pore volume) of diatomite and the catalytic efficiency of the catalyst prepared from the treated diatomite.

Modeling of the fault-controlled hydrothermal ore-forming systems

International Nuclear Information System (INIS)

Pek, A.A.; Malkovsky, V.I.

1993-07-01

A necessary precondition for the formation of hydrothermal ore deposits is a strong focusing of hydrothermal flow as fluids move from the fluid source to the site of ore deposition. The spatial distribution of hydrothermal deposits favors the concept that such fluid flow focusing is controlled, for the most part, by regional faults which provide a low resistance path for hydrothermal solutions. Results of electric analog simulations, analytical solutions, and computer simulations of the fluid flow, in a fault-controlled single-pass advective system, confirm this concept. The influence of the fluid flow focusing on the heat and mass transfer in a single-pass advective system was investigated for a simplified version of the metamorphic model for the genesis of greenstone-hosted gold deposits. The spatial distribution of ore mineralization, predicted by computer simulation, is in reasonable agreement with geological observations. Computer simulations of the fault-controlled thermoconvective system revealed a complex pattern of mixing hydrothermal solutions in the model, which also simulates the development of the modern hydrothermal systems on the ocean floor. The specific feature of the model considered, is the development under certain conditions of an intra-fault convective cell that operates essentially independently of the large scale circulation. These and other results obtained during the study indicate that modeling of natural fault-controlled hydrothermal systems is instructive for the analysis of transport processes in man-made hydrothermal systems that could develop in geologic high-level nuclear waste repositories

High blood pressure - children

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... this page: //medlineplus.gov/ency/article/007696.htm High blood pressure - children To use the sharing features on this page, please enable JavaScript. High blood pressure (hypertension) is an increase in the force of ...

High blood pressure - infants

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... this page: //medlineplus.gov/ency/article/007329.htm High blood pressure - infants To use the sharing features on this page, please enable JavaScript. High blood pressure (hypertension) is an increase in the force of ...

High blood pressure medications

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... this page: //medlineplus.gov/ency/article/007484.htm High blood pressure medicines To use the sharing features on this page, please enable JavaScript. Treating high blood pressure will help prevent problems such as heart disease, ...

Asymmetrical structure, hydrothermal system and edifice stability: The case of Ubinas volcano, Peru, revealed by geophysical surveys

Science.gov (United States)

Gonzales, Katherine; Finizola, Anthony; Lénat, Jean-François; Macedo, Orlando; Ramos, Domingo; Thouret, Jean-Claude; Fournier, Nicolas; Cruz, Vicentina; Pistre, Karine

2014-04-01

Ubinas volcano, the historically most active volcano in Peru straddles a low-relief high plateau and the flank of a steep valley. A multidisciplinary geophysical study has been performed to investigate the internal structure and the fluids flow within the edifice. We conducted 10 self-potential (SP) radial (from summit to base) profiles, 15 audio magnetotelluric (AMT) soundings on the west flank and a detailed survey of SP and soil temperature measurements on the summit caldera floor. The typical “V” shape of the SP radial profiles has been interpreted as the result of a hydrothermal zone superimposed on a hydrogeological zone in the upper parts of the edifice, and depicts a sub-circular SP positive anomaly, about 6 km in diameter. The latter is centred on the summit, and is characterised by a larger extension on the western flank located on the low-relief high plateau. The AMT resistivity model shows the presence of a conductive body beneath the summit at a depth comparable to that of the bottom of the inner south crater in the present-day caldera, where intense hydrothermal manifestations occur. The lack of SP and temperature anomalies on the present caldera floor suggests a self-sealed hydrothermal system, where the inner south crater acts as a pressure release valve. Although no resistivity data exists on the eastern flank, we presume, based on the asymmetry of the basement topography, and the amplitude of SP anomalies on the east flank, which are approximately five fold that on the west flank, that gravitational flow of hydrothermal fluids may occur towards the deep valley of Ubinas. This hypothesis, supported by the presence of hot springs and faults on the eastern foot of the edifice, reinforces the idea that a large part of the southeast flank of the Ubinas volcano may be altered by hydrothermal activity and will tend to be less stable. One of the major findings that stems from this study is that the slope of the basement on which a volcano has grown

Hydrothermal synthesis of highly luminescent blue-emitting ZnSe(S) quantum dots exhibiting low toxicity

Energy Technology Data Exchange (ETDEWEB)

Mirnajafizadeh, Fatemeh; Ramsey, Deborah; McAlpine, Shelli [School of Chemistry, University of New South Wales, Sydney, NSW 2052 (Australia); Wang, Fan; Reece, Peter [School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia); Stride, John Arron, E-mail: j.stride@unsw.edu.au [School of Chemistry, University of New South Wales, Sydney, NSW 2052 (Australia); Bragg Institute, Australian Nuclear Science and Technology Organisation, PMB 1, Menai, NSW 2234 (Australia)

2016-07-01

Highly luminescent quantum dots (QDs) that emit in the visible spectrum are of interest to a number of imaging technologies, not least that of biological samples. One issue that hinders the application of luminescent markers in biology is the potential toxicity of the fluorophore. Here we show that hydrothermally synthesized ZnSe(S) QDs have low cytotoxicity to both human colorectal carcinoma cells (HCT-116) and human skin fibroblast cells (WS1). The QDs exhibited a high degree of crystallinity, with a strong blue photoluminescence at up to 29% quantum yield relative to 4′,6-diamidino-2-phenylindole (DAPI) without post-synthetic UV-irradiation. Confocal microscopy images obtained of HCT-116 cells after incubation with the QDs highlighted the stability of the particles in cell media. Cytotoxicity studies showed that both HCT-116 and WS1 cells retain 100% viability after treatment with the QDs at concentrations up to 0.5 g/L, which makes them of potential use in biological imaging applications. - Highlights: • Highly luminescent ZnSe(S) QDs were synthesized using a simple, one-step hydrothermal method. • The as-synthesized QDs were found to be nontoxic in the presence of biological cells. • The QDs were stable in biological media with identical emission profile to that in water.

High-pressure tritium

International Nuclear Information System (INIS)

Coffin, D.O.

1976-01-01

Some solutions to problems of compressing and containing tritium gas to 200 MPa at 700 0 K are discussed. The principal emphasis is on commercial compressors and high-pressure equipment that can be easily modified by the researcher for safe use with tritium. Experience with metal bellows and diaphragm compressors has been favorable. Selection of materials, fittings, and gauges for high-pressure tritium work is also reviewed briefly

Complexing and hydrothermal ore deposition

CERN Document Server

Helgeson, Harold C

1964-01-01

Complexing and Hydrothermal Ore Deposition provides a synthesis of fact, theory, and interpretative speculation on hydrothermal ore-forming solutions. This book summarizes information and theory of the internal chemistry of aqueous electrolyte solutions accumulated in previous years. The scope of the discussion is limited to those aspects of particular interest to the geologist working on the problem of hydrothermal ore genesis. Wherever feasible, fundamental principles are reviewed. Portions of this text are devoted to calculations of specific hydrothermal equilibriums in multicompone

The pH and pCO2 dependence of sulfate reduction in shallow-sea hydrothermal CO2 – venting sediments (Milos Island, Greece)

Science.gov (United States)

Bayraktarov, Elisa; Price, Roy E.; Ferdelman, Timothy G.; Finster, Kai

2013-01-01

Microbial sulfate reduction (SR) is a dominant process of organic matter mineralization in sulfate-rich anoxic environments at neutral pH. Recent studies have demonstrated SR in low pH environments, but investigations on the microbial activity at variable pH and CO2 partial pressure are still lacking. In this study, the effect of pH and pCO2 on microbial activity was investigated by incubation experiments with radioactive 35S targeting SR in sediments from the shallow-sea hydrothermal vent system of Milos, Greece, where pH is naturally decreased by CO2 release. Sediments differed in their physicochemical characteristics with distance from the main site of fluid discharge. Adjacent to the vent site (T ~40–75°C, pH ~5), maximal sulfate reduction rates (SRR) were observed between pH 5 and 6. SR in hydrothermally influenced sediments decreased at neutral pH. Sediments unaffected by hydrothermal venting (T ~26°C, pH ~8) expressed the highest SRR between pH 6 and 7. Further experiments investigating the effect of pCO2 on SR revealed a steep decrease in activity when the partial pressure increased from 2 to 3 bar. Findings suggest that sulfate reducing microbial communities associated with hydrothermal vent system are adapted to low pH and high CO2, while communities at control sites required a higher pH for optimal activity. PMID:23658555

Synthesis of high intrinsic loss power aqueous ferrofluids of iron oxide nanoparticles by citric acid-assisted hydrothermal-reduction route

International Nuclear Information System (INIS)

Behdadfar, Behshid; Kermanpur, Ahmad; Sadeghi-Aliabadi, Hojjat; Morales, Maria del Puerto; Mozaffari, Morteza

2012-01-01

Monodispersed aqueous ferrofluids of iron oxide nanoparticle were synthesized by hydrothermal-reduction route. They were characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy and dynamic light scattering. The results showed that certain concentrations of citric acid (CA) are required to obtain only magnetic iron oxides with mean particle sizes around 8 nm. CA acts as a modulator and reducing agent in iron oxide formation which controls nanoparticle size. The XRD, magnetic and heating measurements showed that the temperature and time of hydrothermal reaction can affect the magnetic properties of obtained ferrofluids. The synthesized ferrofluids were stable at pH 7. Their mean hydrodynamic size was around 80 nm with polydispersity index (PDI) of 0.158. The calculated intrinsic loss power (ILP) was 9.4 nHm 2 /kg. So this clean and cheap route is an efficient way to synthesize high ILP aqueous ferrofluids applicable in magnetic hyperthermia. - Graphical abstract: Monodispersed aqueous ferrofluids of iron oxide nanoparticles were synthesized by hydrothermal-reduction method with citric acid as reductant which is an efficient way to synthesize aqueous ferrofluids applicable in magnetic hyperthermia. Highlights: ► Aqueous iron oxide ferrofluids were synthesized by hydrothermal-reduction route. ► Citric acid acted as reducing agent and surfactant in the route. ► This is a facile, low energy and environmental friendly route. ► The aqueous iron oxide ferrofluids were monodispersed and stable at pH of 7. ► The calculated intrinsic loss power of the synthesized ferrofluids was very high.

High-pressure boron hydride phases

International Nuclear Information System (INIS)

Barbee, T.W. III; McMahan, A.K.; Klepeis, J.E.; van Schilfgaarde, M.

1997-01-01

The stability of boron-hydrogen compounds (boranes) under pressure is studied from a theoretical point of view using total-energy methods. We find that the molecular forms of boranes known to be stable at ambient pressure become unstable at high pressure, while structures with extended networks of bonds or metallic bonding are energetically favored at high pressures. If such structures are metastable on return to ambient pressure, they would be energetic as well as dense hydrogen storage media. An AlH 3 -like structure of BH 3 is particularly interesting in that it may be accessible by high-pressure diamond anvil experiments, and should exhibit both second-order structural and metal-insulator transitions at lower pressures. copyright 1997 The American Physical Society

Dual shell pressure balanced reactor vessel. Final project report

International Nuclear Information System (INIS)

Robertus, R.J.; Fassbender, A.G.

1994-10-01

The Department of Energy's Office of Energy Research (OER) has previously provided support for the development of several chemical processes, including supercritical water oxidation, liquefaction, and aqueous hazardous waste destruction, where chemical and phase transformations are conducted at high pressure and temperature. These and many other commercial processes require a pressure vessel capable of operating in a corrosive environment where safety and economy are important requirements. Pacific Northwest Laboratory (PNL) engineers have recently developed and patented (U.S. patent 5,167,930 December 1, 1992) a concept for a novel Dual Shell Pressure Balanced Vessel (DSPBV) which could solve a number of these problems. The technology could be immediately useful in continuing commercialization of an R ampersand D 100 award-winning technology, Sludge-to-oil Reactor System (STORS), originally developed through funding by OER. Innotek Corporation is a small business that would be one logical end-user of the DSPBV reactor technology. Innotek is working with several major U.S. engineering firms to evaluate the potential of this technology in the disposal of wastes from sewage treatment plants. PNL entered into a CRADA with Innotek to build a bench-scale demonstration reactor and test the system to advance the economic feasibility of a variety of high pressure chemical processes. Hydrothermal processing of corrosive substances on a large scale can now be made significantly safer and more economical through use of the DSPBV. Hydrothermal chemical reactions such as wet-air oxidation and supercritical water oxidation occur in a highly corrosive environment inside a pressure vessel. Average corrosion rates from 23 to 80 miles per year have been reported by Rice (1994) and Latanision (1993)

Hydrothermal Upflow, Serpentinization and Talc Alteration Associated with a High Angle Normal Fault Cutting an Oceanic Detachment, Northern Apennines, Italy

Science.gov (United States)

Alt, J.; Crispini, L.; Gaggero, L.; Shanks, W. C., III; Gulbransen, C.; Lavagnino, G.

2017-12-01

Normal faults cutting oceanic core complexes are observed at the seafloor and through geophysics, and may act as flow pathways for hydrothermal fluids, but we know little about such faults in the subsurface. We present bulk rock geochemistry and stable isotope data for a fault that acted as a hydrothermal upflow zone in a seafloor ultramafic-hosted hydrothermal system in the northern Apennines, Italy. Peridotites were exposed on the seafloor by detachment faulting, intruded by MORB gabbros, and are overlain by MORB lavas and pelagic sediments. North of the village of Reppia are fault shear zones in serpentinite, oriented at a high angle to the detachment surface and extending 300 m below the paleo-seafloor. The paleo-seafloor strikes roughly east-west, dipping 30˚ to the north. At depth the fault zone occurs as an anticlinal form plunging 40˚ to the west. A second fault strikes approximately north-south, with a near vertical dip. The fault rock outcrops as reddish weathered talc + sulfide in 0.1-2 m wide anastomosing bands, with numerous splays. Talc replaces serpentinite in the fault rocks, and the talc rocks are enriched in Si, metals (Fe, Cu, Pb), Light Rare Earth Elements (LREE), have variable Eu anomalies, and have low Mg, Cr and Ni contents. In some cases gabbro dikes are associated with talc-alteration and may have enhanced fluid flow. Sulfide from a fault rock has d34S=5.7‰. The mineralogy and chemistry of the fault rocks indicate that the fault acted as the upflow pathway for high-T black-smoker type fluids. Traverses away from the fault (up to 1 km) and with depth below the seafloor (up to 500 m) reveal variable influences of hydrothermal fluids, but there are no consistent trends with distance. Background serpentinites 500 m beneath the paleoseafloor have LREE depleted trends. Other serpentinites exhibit correlations of LREE with HFSE as the result of melt percolation, but there is significant scatter, and hydrothermal effects include LREE enrichment

Psoriasis and high blood pressure.

Science.gov (United States)

Salihbegovic, Eldina Malkic; Hadzigrahic, Nermina; Suljagic, Edin; Kurtalic, Nermina; Sadic, Sena; Zejcirovic, Alema; Mujacic, Almina

2015-02-01

Psoriasis is a chronic skin ailment which can be connected with an increased occurrence of other illnesses, including high blood pressure. A prospective study has been conducted which included 70 patients affected by psoriasis, both genders, older than 18 years. Average age being 47,14 (SD= ±15,41) years, from that there were 36 men or 51,43 and 34 women or 48,57%. Average duration of psoriasis was 15,52 (SD=±12,54) years. Frequency of high blood pressure in those affected by psoriasis was 54,28%. Average age of the patients with psoriasis and high blood pressure was 53,79 year (SD=±14,15) and average duration of psoriasis was 17,19 years (SD=±13,51). Average values of PASI score were 16,65. Increase in values of PASI score and high blood pressure were statistically highly related (r=0,36, p=0,0001). Psoriasis was related to high blood pressure and there was a correlation between the severity of psoriasis and high blood pressure.

High-pressure torsion of hafnium

International Nuclear Information System (INIS)

Edalati, Kaveh; Horita, Zenji; Mine, Yoji

2010-01-01

Pure Hf (99.99%) is processed by high-pressure torsion (HPT) under pressures of 4 and 30 GPa to form an ultrafine-grained structure with a gain size of ∼180 nm. X-ray diffraction analysis shows that, unlike Ti and Zr, no ω phase formation is detected after HPT processing even under a pressure of 30 GPa. A hydride formation is detected after straining at the pressure of 4 GPa. The hydride phase decomposes either by application of a higher pressure as 30 GPa or by unloading for prolong time after HPT processing. Microhardness, tensile and bending tests show that a high hardness (360 Hv) and an appreciable ductility (8%) as well as high tensile and bending strength (1.15 and 2.75 GPa, respectively) are achieved following the high-pressure torsion.

Preventing High Blood Pressure

Science.gov (United States)

... Heart Disease Cholesterol Salt Million Hearts® WISEWOMAN Preventing High Blood Pressure: Healthy Living Habits Recommend on Facebook Tweet Share ... meal and snack options can help you avoid high blood pressure and its complications. Be sure to eat plenty ...

Assessment of hydrothermal pretreatment of various lignocellulosic biomass with CO2 catalyst for enhanced methane and hydrogen production.

Science.gov (United States)

Eskicioglu, Cigdem; Monlau, Florian; Barakat, Abdellatif; Ferrer, Ivet; Kaparaju, Prasad; Trably, Eric; Carrère, Hélène

2017-09-01

Hydrothermal pretreatment of five lignocellulosic substrates (i.e. wheat straw, rice straw, biomass sorghum, corn stover and Douglas fir bark) were conducted in the presence of CO 2 as a catalyst. To maximize disintegration and conversion into bioenergy (methane and hydrogen), pretreatment temperatures and subsequent pressures varied with a range of 26-175 °C, and 25-102 bars, respectively. Among lignin, cellulose and hemicelluloses, hydrothermal pretreatment caused the highest reduction (23-42%) in hemicelluloses while delignification was limited to only 0-12%. These reductions in structural integrity resulted in 20-30% faster hydrolysis rates during anaerobic digestion for the pretreated substrates of straws, sorghum, and corn stover while Douglas fir bark yielded 172% faster hydrolysis/digestion due to its highly refractory nature in the control. Furans and phenolic compounds formed in the pretreated hydrolyzates were below the inhibitory levels for methane and hydrogen production which had a range of 98-340 ml CH 4 /g volatile solids (VS) and 5-26 ml H 2 /g VS, respectively. Results indicated that hydrothermal pretreatment is able to accelerate the rate of biodegradation without generating high levels of inhibitory compounds while showing no discernible effect on ultimate biodegradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biosphere in 3.5 Ga submarine hydrothermal system

Energy Technology Data Exchange (ETDEWEB)

Ueno, Yuichiro [Tokyo Univ. (Japan). Dept. of Earth Science and Astronomy

2003-04-01

Abundant organic matter (kerogen) was identified in {approx}3.5 Ga hydrothermal silica dikes from the North Pole area in the Pilbara craton, Western Australia. The silica dikes developed in the uppermost 1000 m of the ancient oceanic crust. Thus, they would have been deposited in the 3.5 Ga sub-seafloor hydrothermal system. The carbon and nitrogen isotopic compositions of the kerogen were analyzed in this study. Their highly {sup 13}C-depleted isotopic compositions ({delta}{sup 13}C = -38 to -33 per mille) strongly suggest that they are originally derived from biologically produced organic matter. The remarkable similarity of the {delta}{sup 13}C values between the kerogen and modern hydrothermal vent organisms may suggest that the kerogen was derived from chemoautotrophic organisms. This idea is also consistent with their nitrogen isotopic compositions ({delta}{sup 15}N = -4 to +4 per mille). The silica dikes consist mainly of fine-grained silica with minor pyrite and sphalerite. These mineral assemblages indicate that the silica dike was deposited from relatively low-temperature (probably less than 150degC) reducing hydrothermal fluid. Thus, anaerobic thermophilic/hyperthermophilic organisms could have survived in the hydrothermal fluid, which formed the silica dikes. Therefore, it is plausible that a chemoautotrophic-based biosphere (possibly methanogenesis) probably existed in the Early Archean sub-seafloor hydrothermal system. (author)

Mechanisms involved in the hydrothermal growth of ultra-thin and high aspect ratio ZnO nanowires

Science.gov (United States)

Demes, Thomas; Ternon, Céline; Morisot, Fanny; Riassetto, David; Legallais, Maxime; Roussel, Hervé; Langlet, Michel

2017-07-01

Hydrothermal synthesis of ZnO nanowires (NWs) with tailored dimensions, notably high aspect ratios (AR) and small diameters, is a major concern for a wide range of applications and still represents a challenging and recurring issue. In this work, an additive-free and reproducible hydrothermal procedure has been developed to grow ultra-thin and high AR ZnO NWs on sol-gel deposited ZnO seed layers. Controlling the substrate temperature and using a low reagent concentration (1 mM) has been found to be essential for obtaining such NWs. We show that the NW diameter remains constant at about 20-25 nm with growth time contrary to the NW length that can be selectively increased leading to NWs with ARs up to 400. On the basis of investigated experimental conditions along with thermodynamic and kinetic considerations, a ZnO NW growth mechanism has been developed which involves the formation and growth of nuclei followed by NW growth when the nuclei reach a critical size of about 20-25 nm. The low reagent concentration inhibits NW lateral growth leading to ultra-thin and high AR NWs. These NWs have been assembled into electrically conductive ZnO nanowire networks, which opens attractive perspectives toward the development of highly sensitive low-cost gas- or bio-sensors.

Phase transitions in solids under high pressure

CERN Document Server

Blank, Vladimir Davydovich

2013-01-01

Phase equilibria and kinetics of phase transformations under high pressureEquipment and methods for the study of phase transformations in solids at high pressuresPhase transformations of carbon and boron nitride at high pressure and deformation under pressurePhase transitions in Si and Ge at high pressure and deformation under pressurePolymorphic α-ω transformation in titanium, zirconium and zirconium-titanium alloys Phase transformations in iron and its alloys at high pressure Phase transformations in gallium and ceriumOn the possible polymorphic transformations in transition metals under pressurePressure-induced polymorphic transformations in АIBVII compoundsPhase transformations in AIIBVI and AIIIBV semiconductor compoundsEffect of pressure on the kinetics of phase transformations in iron alloysTransformations during deformation at high pressure Effects due to phase transformations at high pressureKinetics and hysteresis in high-temperature polymorphic transformations under pressureHysteresis and kineti...

Organic sulfur metabolisms in hydrothermal environments.

Science.gov (United States)

Rogers, Karyn L; Schulte, Mitchell D

2012-07-01

Sulfur is central to the metabolisms of many organisms that inhabit extreme environments. While biotic and abiotic cycling of organic sulfur compounds has been well documented in low-temperature anaerobic environments, cycling of organic sulfur in hydrothermal environments has received less attention. Recently published thermodynamic data have been used to estimate aqueous alkyl thiol and sulfide activities in deep-sea hydrothermal systems. Here we use geochemical mixing models to predict fluid compositions that result from mixing end-member hydrothermal fluid from the East Pacific Rise with bottom seawater. These fluid compositions are combined with estimates of methanethiol and dimethylsulfide activities to evaluate energy yields for potential organic sulfur-based metabolisms under hydrothermal conditions. Aerobic respiration has the highest energy yields (over -240 kJ/mol e⁻) at lower temperature; however, oxygen is unlikely to persist at high temperatures, restricting aerobic respiration to mesophilic communities. Nitrite reduction to N₂ has the highest energy yields at higher temperatures (greater than ∼40 °C). Nitrate and nitrite reduction to ammonium also yield significant energy (up to -70 kJ/mol e⁻). Much lower, but still feasible energy yields are calculated for sulfate reduction, disproportionation, and reduction with H₂. Organic compound family and the activity of methanethiol and dimethylsulfide were less important than metabolic strategy in determining overall energy yields. All metabolic strategies considered were exergonic within some portion of the mixing regime suggesting that organic sulfur-based metabolisms may be prevalent within deep-sea hydrothermal vent microbial communities. © 2012 Blackwell Publishing Ltd.

High Blood Pressure (Hypertension)

Science.gov (United States)

... other risk factors, like diabetes, you may need treatment. How does high blood pressure affect pregnant women? A few women will get ... HIV, Birth Control Heart Health for Women Pregnancy Menopause More Women's Health ... High Blood Pressure--Medicines to Help You Women and Diabetes Heart ...

Hydrothermal alteration in oceanic ridge volcanics: A detailed study at the Galapagos Fossil Hydrothermal Field

Science.gov (United States)

Ridley, W.I.; Perfit, M.R.; Josnasson, I.R.; Smith, M.F.

1994-01-01

The Galapagos Fossil Hydrothermal Field is composed of altered oceanic crust and extinct hydrothermal vents within the eastern Galapagos Rift between 85??49???W and 85??55???W. The discharge zone of the hydrothermal system is revealed along scarps, thus providing an opportunity to examine the uppermost mineralized, and highly altered interior parts of the crust. Altered rocks collected in situ by the submersible ALVIN show complex concentric alteration zones. Microsamples of individual zones have been analysed for major/minor, trace elements, and strontium isotopes in order to describe the complex compositional details of the hydrothermal alteration. Interlayered chlorite-smectite and chlorite with disequilibrium compositions dominate the secondary mineralogy as replacement phases of primary glass and acicular pyroxene. Phenocrysts and matrix grains of plagioclase are unaffected during alteration. Using a modification of the Gresens' equation we demonstrate that the trivalent rare earth elements (REEs) are relatively immobile, and calculate degrees of enrichment and depletion in other elements. Strontium isotopic ratios increase as Sr concentrations decrease from least-altered cores to most-altered rims and cross-cutting veins in individual samples, and can be modeled by open system behaviour under low fluid-rock ratio (< 10) conditions following a period of lower-temperature weathering of volcanics within the rift zone. The complex patterns of element enrichment and depletion and strontium isotope variations indicate mixing between pristine seawater and ascending hot fluids to produce a compositional spectrum of fluids. The precipitation of base-metal sulfides beneath the seafloor is probably a result of fluid mixing and cooling. If, as suggested here, the discharge zone alteration occurred under relatively low fluid-rock ratios, then this shallow region must play an important role in determining the exit composition of vent fluids in marine hydrothermal systems

Influence of microstructure on hydrothermal corrosion of chemically vapor processed SiC composite tubes

Science.gov (United States)

Kim, Daejong; Lee, Ho Jung; Jang, Changheui; Lee, Hyeon-Geun; Park, Ji Yeon; Kim, Weon-Ju

2017-08-01

Multi-layered SiC composites consisting of monolithic SiC and a SiCf/SiC composite are one of the accident tolerant fuel cladding concepts in pressurized light water reactors. To evaluate the integrity of the SiC fuel cladding under normal operating conditions of a pressurized light water reactor, the hydrothermal corrosion behavior of multi-layered SiC composite tubes was investigated in the simulated primary water environment of a pressurized water reactor without neutron fluence. The results showed that SiC phases with good crystallinity such as Tyranno SA3 SiC fiber and monolithic SiC deposited at 1200 °C had good corrosion resistance. However, the SiC phase deposited at 1000 °C had less crystallinity and severely dissolved in water, particularly the amorphous SiC phase formed along grain boundaries. Dissolved hydrogen did not play a significant role in improving the hydrothermal corrosion resistance of the CVI-processed SiC phases containing amorphous SiC, resulting in a significant weight loss and reduction of hoop strength of the multi-layered SiC composite tubes after corrosion.

Fundamentals of high pressure adsorption

Energy Technology Data Exchange (ETDEWEB)

Zhou, Y.P.; Zhou, L. [Tianjin University, Tianjin (China). High Pressure Adsorption Laboratory

2009-12-15

High-pressure adsorption attracts research interests following the world's attention to alternative fuels, and it exerts essential effect on the study of hydrogen/methane storage and the development of novel materials addressing to the storage. However, theoretical puzzles in high-pressure adsorption hindered the progress of application studies. Therefore, the present paper addresses the major theoretical problems that challenged researchers: i.e., how to model the isotherms with maximum observed in high-pressure adsorption; what is the adsorption mechanism at high pressures; how do we determine the quantity of absolute adsorption based on experimental data. Ideology and methods to tackle these problems are elucidated, which lead to new insights into the nature of high-pressure adsorption and progress in application studies, for example, in modeling multicomponent adsorption, hydrogen storage, natural gas storage, and coalbed methane enrichment, was achieved.

Experimentally Testing Hydrothermal Vent Origin of Life on Enceladus and Other Icy/Ocean Worlds.

Science.gov (United States)

Barge, Laura M; White, Lauren M

2017-09-01

We review various laboratory strategies and methods that can be utilized to simulate prebiotic processes and origin of life in hydrothermal vent systems on icy/ocean worlds. Crucial steps that could be simulated in the laboratory include simulations of water-rock chemistry (e.g., serpentinization) to produce hydrothermal fluids, the types of mineral catalysts and energy gradients produced in vent interfaces where hydrothermal fluids interface with the surrounding seawater, and simulations of biologically relevant chemistry in flow-through gradient systems (i.e., far-from-equilibrium experiments). We describe some examples of experimental designs in detail, which are adaptable and could be used to test particular hypotheses about ocean world energetics or mineral/organic chemistry. Enceladus among the ocean worlds provides an ideal test case, since the pressure at the ocean floor is more easily simulated in the lab. Results for Enceladus could be extrapolated with further experiments and modeling to understand other ocean worlds. Key Words: Enceladus-Ocean worlds-Icy worlds-Hydrothermal vent-Iron sulfide-Gradient. Astrobiology 17, 820-833.

Effect of Hydrothermal Alteration on Rock Properties in Active Geothermal Setting

Science.gov (United States)

Mikisek, P.; Bignall, G.; Sepulveda, F.; Sass, I.

2012-04-01

Hydrothermal alteration records the physical-chemical changes of rock and mineral phases caused by the interaction of hot fluids and wall rock, which can impact effective permeability, porosity, thermal parameters, rock strength and other rock properties. In this project, an experimental approach has been used to investigate the effects of hydrothermal alteration on rock properties. A rock property database of contrastingly altered rock types and intensities has been established. The database details horizontal and vertical permeability, porosity, density, thermal conductivity and thermal heat capacity for ~300 drill core samples from wells THM12, THM13, THM14, THM17, THM18, THM22 and TH18 in the Wairakei-Tauhara geothermal system (New Zealand), which has been compared with observed hydrothermal alteration type, rank and intensity obtained from XRD analysis and optical microscopy. Samples were selected from clay-altered tuff and intercalated siltstones of the Huka Falls Formation, which acts as a cap rock at Wairakei-Tauhara, and tuffaceous sandstones of the Waiora Formation, which is a primary reservoir-hosting unit for lateral and vertical fluid flows in the geothermal system. The Huka Falls Formation exhibits argillic-type alteration of varying intensity, while underlying Waiora Formations exhibits argillic- and propylithic-type alteration. We plan to use a tempered triaxial test cell at hydrothermal temperatures (up to 200°C) and pressures typical of geothermal conditions, to simulate hot (thermal) fluid percolation through the rock matrix of an inferred "reservoir". Compressibility data will be obtained under a range of operating (simulation reservoir) conditions, in a series of multiple week to month-long experiments that will monitor change in permeability and rock strength accompanying advancing hydrothermal alteration intensity caused by the hot brine interacting with the rock matrix. We suggest, our work will provide new baseline information concerning

Fast preparation of Na0.44MnO2 nanorods via a high NaOH concentration hydrothermal soft chemical reaction and their lithium storage properties

International Nuclear Information System (INIS)

Liu, Cai; Li, Jiangang; Zhao, Pengxiang; Guo, Wenli; Yang, Xiaoping

2015-01-01

This paper describes a high NaOH concentration hydrothermal soft chemical reaction to prepare Na 0.44 MnO 2 nanorods. In this process, Na-birnessite precursors and concentrated NaOH solution are introduced into the hydrothermal reaction. As a result, the hydrothermal time can be significantly shortened from 96 to 24 h, the hydrothermal temperature can be reduced from 205 to 180 °C and the yield of Na 0.44 MnO 2 can be increased from about 0.6 to about 2.4 g/(mL . day), respectively. Furthermore, the obtained Na 0.44 MnO 2 nanorods with one-dimensional tunnel structures exhibit favorable electrochemical lithium storage properties, which make them promising for the cathode materials of lithium-ion batteries

Hydrothermal germination models: Improving experimental efficiency by limiting data collection to the relevant hydrothermal range

Science.gov (United States)

Hydrothermal models used to predict germination response in the field are usually parameterized with data from laboratory experiments that examine the full range of germination response to temperature and water potential. Inclusion of low water potential and high and low-temperature treatments, how...

Effects of hydrothermal treatment of sewage sludge on pyrolysis and steam gasification

International Nuclear Information System (INIS)

Moon, Jihong; Mun, Tae-Young; Yang, Won; Lee, Uendo; Hwang, Jungho; Jang, Ensuk; Choi, Changsik

2015-01-01

Highlights: • Hydrothermal treatment (HT) is energy efficient and increases fuel energy density. • Pyrolysis and steam gasification were performed with sewage sludge before/after HT. • Product gases resembled those from wood chips, particularly at high temperature. • HT increases sludge lignin content, possibly enhancing methane yield of product gas. • HT can improve sewage sludge for use as an alternative to biomass and fossil fuels. - Abstract: Hydrothermal treatment is a promising option for pretreatment drying of organic waste, due to its low energy consumption and contribution to increasing fuel energy density. In this study, the characteristics of hydrothermally treated sewage sludge were investigated, and pyrolysis and steam gasification were performed with the sludge before and after hydrothermal treatment. The overall composition of product gases from treated sludge was similar to that obtained from steam gasification of wood chips, particularly under high-temperature conditions. In addition, the increase in lignin content of sewage sludge following hydrothermal treatment could help enhance methane yield in product gas during pyrolysis and steam gasification. The findings suggest that hydrothermal treatment is an appropriate method for improving sewage sludge for use as an alternative to biomass and fossil fuels

Evaluation of high temperature pressure sensors

International Nuclear Information System (INIS)

Choi, In-Mook; Woo, Sam-Yong; Kim, Yong-Kyu

2011-01-01

It is becoming more important to measure the pressure in high temperature environments in many industrial fields. However, there is no appropriate evaluation system and compensation method for high temperature pressure sensors since most pressure standards have been established at room temperature. In order to evaluate the high temperature pressure sensors used in harsh environments, such as high temperatures above 250 deg. C, a specialized system has been constructed and evaluated in this study. The pressure standard established at room temperature is connected to a high temperature pressure sensor through a chiller. The sensor can be evaluated in conditions of changing standard pressures at constant temperatures and of changing temperatures at constant pressures. According to the evaluation conditions, two compensation methods are proposed to eliminate deviation due to sensitivity changes and nonlinear behaviors except thermal hysteresis.

Hydrothermal synthesis of highly water-dispersible anatase nanocrystals from transparent aqueous sols of titanate colloids

International Nuclear Information System (INIS)

Ban, Takayuki; Tanaka, Yusuke; Ohya, Yutaka

2011-01-01

Transparent colloidal aqueous solutions of anatase nanocrystals were hydrothermally synthesized from aqueous transparent sols with tetramethylammonium titanate colloids, the surfaces of which were modified with citric acid, by structural conversion of the titanate to anatase. This modification hindered coalescence of the titanate colloids during the hydrothermal synthesis. Although the amount of citric acid adsorbed on the colloids was reduced during hydrothermal treatment, a small amount of citric acid was adsorbed on the resulting anatase nanocrystals. Moreover, the use of the titanate colloids as a precursor was compared with the use of a citrato Ti complex, tetramethylammonium citratotitanate. The hydrothermal treatment of the transparent aqueous solutions of the Ti complex yielded opaque solutions with large anatase colloids, suggesting that the titanate colloids were useful for preparing transparent anatase colloidal solutions. Because the shape and size of resulting colloids may be dependent on the size and shape of starting colloids, the use of titanate colloids as a precursor may make it easy to control size and shape of anatase colloids.

Hydrothermal carbonization of biomass waste under low temperature condition

Directory of Open Access Journals (Sweden)

Putra Herlian Eriska

2018-01-01

Full Text Available In this paper, the use of banana peel for energy purposes was investigated. Banana peel is a lignocellulosic waste since it is the most widely produced and consumed fruit in Indonesia. Among the others, hydrothermal carbonization (HTC was chosen as alternative themochemical process, suitable for high moisture biomass. Through a 1 L stirred reactor, hydrothermal treatments were performed under low temperature condition (190, 210 and 230 °C, residence times (30 and 60 min, and biomass to water ratio (1:3, 1:5, and 1:10. Three of product were collected from the process with primary material balance. Solid phase (hydrochar was evaluated in terms of calorific value, proximate and ultimate analysis. The results suggested that the hydrothermal carbonization of banana peel gave high heating value (HHV of 20.09 MJ/kg for its char after dried naturally.

600 kyr of Hydrothermal Activity on the Cleft Segment of the Juan de Fuca Ridge

Science.gov (United States)

Middleton, J. L.; Mukhopadhyay, S.; Langmuir, C. H.; Costa, K.; McManus, J. F.; Katz, R. F.; Huybers, P. J.; Winckler, G.; Li, Y.

2017-12-01

Pressure fluctuations caused by glacially driven variations in sea level may modulate magmatic and hydrothermal output at submarine volcanic centers, with falling sea level driving increased volcanic activity. In turn, glacially paced changes in submarine volcanism could induce globally synchronous variations in the delivery of bioavailable iron and CO2 from mid-ocean ridges and thus provide solid-Earth feedbacks into the climate system. While evaluation of submarine volcanic output on orbital-timescales is technically challenging, near-ridge sediment cores hosting hydrothermal plume precipitates provide continuous, spatially integrated, and datable records to investigate the long-term behavior of hydrothermal systems. We will present new sedimentary records of hydrothermal variability spanning the past 600 kyr on the Cleft Segment of the Juan de Fuca Ridge in the Northeast Pacific. As an intermediate spreading-rate ridge, the Juan de Fuca Ridge is hypothesized to be particularly sensitive to sea level forcing at the Milankovitch frequencies of Pleistocene glacial cycles. Thus, the new records can be used to examine the connection between sea level and hydrothermal activity over multiple glacial cycles. Hydrothermal input is determined from iron and copper, with a titanium-based correction for lithogenic contributions. Sedimentary fluxes are then constrained using excess thorium-230 and extraterrestrial helium-3 as constant flux proxies. Preliminary results indicate 10-fold changes in hydrothermal iron and copper fluxes over the past 600 kyr and suggest a quasiperiodic variability in hydrothermal deposition on 100 to 120 kyr cycles. Comparison of the Juan de Fuca record with model predictions for an intermediate spreading ridge forced by Pleistocene glacial cycles finds frequent coincidence between predicted positive anomalies in magmatic output and observed peaks in hydrothermal deposition. This work encourages the continued exploration of the relationship between

Dynamic behavior of Kilauea Volcano and its relation to hydrothermal systems and geothermal energy

Science.gov (United States)

Kauhikaua, Jim; Moore, R.B.; ,

1993-01-01

Exploitation of hydrothermal systems on active basaltic volcanoes poses some unique questions about the role of volcanism and hydrothermal system evolution. Volcanic activity creates and maintains hydrothermal systems while earthquakes create permeable fractures that, at least temporarily, enhance circulation. Magma and water, possibly hydrothermal water, can interact violently to produce explosive eruptions. Finally, we speculate on whether volcanic behavior can be affected by high rates of heat extraction.

Automated high pressure cell for pressure jump x-ray diffraction.

Science.gov (United States)

Brooks, Nicholas J; Gauthe, Beatrice L L E; Terrill, Nick J; Rogers, Sarah E; Templer, Richard H; Ces, Oscar; Seddon, John M

2010-06-01

A high pressure cell for small and wide-angle x-ray diffraction measurements of soft condensed matter samples has been developed, incorporating a fully automated pressure generating network. The system allows both static and pressure jump measurements in the range of 0.1-500 MPa. Pressure jumps can be performed as quickly as 5 ms, both with increasing and decreasing pressures. Pressure is generated by a motorized high pressure pump, and the system is controlled remotely via a graphical user interface to allow operation by a broad user base, many of whom may have little previous experience of high pressure technology. Samples are loaded through a dedicated port allowing the x-ray windows to remain in place throughout an experiment; this facilitates accurate subtraction of background scattering. The system has been designed specifically for use at beamline I22 at the Diamond Light Source, United Kingdom, and has been fully integrated with the I22 beamline control systems.

Automated high pressure cell for pressure jump x-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Brooks, Nicholas J.; Gauthe, Beatrice L. L. E.; Templer, Richard H.; Ces, Oscar; Seddon, John M. [Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Terrill, Nick J. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Rogers, Sarah E. [ISIS, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom)

2010-06-15

A high pressure cell for small and wide-angle x-ray diffraction measurements of soft condensed matter samples has been developed, incorporating a fully automated pressure generating network. The system allows both static and pressure jump measurements in the range of 0.1-500 MPa. Pressure jumps can be performed as quickly as 5 ms, both with increasing and decreasing pressures. Pressure is generated by a motorized high pressure pump, and the system is controlled remotely via a graphical user interface to allow operation by a broad user base, many of whom may have little previous experience of high pressure technology. Samples are loaded through a dedicated port allowing the x-ray windows to remain in place throughout an experiment; this facilitates accurate subtraction of background scattering. The system has been designed specifically for use at beamline I22 at the Diamond Light Source, United Kingdom, and has been fully integrated with the I22 beamline control systems.

Automated high pressure cell for pressure jump x-ray diffraction

International Nuclear Information System (INIS)

Brooks, Nicholas J.; Gauthe, Beatrice L. L. E.; Templer, Richard H.; Ces, Oscar; Seddon, John M.; Terrill, Nick J.; Rogers, Sarah E.

2010-01-01

A high pressure cell for small and wide-angle x-ray diffraction measurements of soft condensed matter samples has been developed, incorporating a fully automated pressure generating network. The system allows both static and pressure jump measurements in the range of 0.1-500 MPa. Pressure jumps can be performed as quickly as 5 ms, both with increasing and decreasing pressures. Pressure is generated by a motorized high pressure pump, and the system is controlled remotely via a graphical user interface to allow operation by a broad user base, many of whom may have little previous experience of high pressure technology. Samples are loaded through a dedicated port allowing the x-ray windows to remain in place throughout an experiment; this facilitates accurate subtraction of background scattering. The system has been designed specifically for use at beamline I22 at the Diamond Light Source, United Kingdom, and has been fully integrated with the I22 beamline control systems.

African Americans and High Blood Pressure

Science.gov (United States)

ANSWERS by heart Lifestyle + Risk Reduction High Blood Pressure What About African Americans and High Blood Pressure? African Americans in the U.S. have a higher prevalence of high blood pressure (HBP) than ...

Hydrothermal systems in small ocean planets.

Science.gov (United States)

Vance, Steve; Harnmeijer, Jelte; Kimura, Jun; Hussmann, Hauke; Demartin, Brian; Brown, J Michael

2007-12-01

We examine means for driving hydrothermal activity in extraterrestrial oceans on planets and satellites of less than one Earth mass, with implications for sustaining a low level of biological activity over geological timescales. Assuming ocean planets have olivine-dominated lithospheres, a model for cooling-induced thermal cracking shows how variation in planet size and internal thermal energy may drive variation in the dominant type of hydrothermal system-for example, high or low temperature system or chemically driven system. As radiogenic heating diminishes over time, progressive exposure of new rock continues to the current epoch. Where fluid-rock interactions propagate slowly into a deep brittle layer, thermal energy from serpentinization may be the primary cause of hydrothermal activity in small ocean planets. We show that the time-varying hydrostatic head of a tidally forced ice shell may drive hydrothermal fluid flow through the seafloor, which can generate moderate but potentially important heat through viscous interaction with the matrix of porous seafloor rock. Considering all presently known potential ocean planets-Mars, a number of icy satellites, Pluto, and other trans-neptunian objects-and applying Earth-like material properties and cooling rates, we find depths of circulation are more than an order of magnitude greater than in Earth. In Europa and Enceladus, tidal flexing may drive hydrothermal circulation and, in Europa, may generate heat on the same order as present-day radiogenic heat flux at Earth's surface. In all objects, progressive serpentinization generates heat on a globally averaged basis at a fraction of a percent of present-day radiogenic heating and hydrogen is produced at rates between 10(9) and 10(10) molecules cm(2) s(1).

High pressure metrology for industrial applications

Science.gov (United States)

Sabuga, Wladimir; Rabault, Thierry; Wüthrich, Christian; Pražák, Dominik; Chytil, Miroslav; Brouwer, Ludwig; Ahmed, Ahmed D. S.

2017-12-01

To meet the needs of industries using high pressure technologies, in traceable, reliable and accurate pressure measurements, a joint research project of the five national metrology institutes and the university was carried out within the European Metrology Research Programme. In particular, finite element methods were established for stress-strain analysis of elastic and nonlinear elastic-plastic deformation, as well as of contact processes in pressure-measuring piston-cylinder assemblies, and high-pressure components at pressures above 1 GPa. New pressure measuring multipliers were developed and characterised, which allow realisation of the pressure scale up to 1.6 GPa. This characterisation is based on research including measurements of material elastic constants by the resonant ultrasound spectroscopy, hardness of materials of high pressure components, density and viscosity of pressure transmitting liquids at pressures up to 1.4 GPa and dimensional measurements on piston-cylinders. A 1.6 GPa pressure system was created for operation of the 1.6 GPa multipliers and calibration of high pressure transducers. A transfer standard for 1.5 GPa pressure range, based on pressure transducers, was built and tested. Herewith, the project developed the capability of measuring pressures up to 1.6 GPa, from which industrial users can calibrate their pressure measurement devices for accurate measurements up to 1.5 GPa.

Bacterial Diets of Primary Consumers at Hydrothermal Vents

Science.gov (United States)

Govenar, B.; Shank, T. M.

2008-12-01

Chemical energy produced by mixing hydrothermal fluids and seawater supports dense biological communities on mid-ocean ridges. The base of the food web at deep-sea hydrothermal vents 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 vent-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 vent 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 vent primary consumers and to track the flow of energy in hydrothermal vent communities, we employed molecular genetic techniques to identify the gut contents of four species of co-occurring hydrothermal vent gastropods, Eulepetopsis vitrea, Lepetodrilus elevatus, Lepetodrilus ovalis and Lepetodrilus pustulosus, collected from a single diffuse-flow hydrothermal vent 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

Distribution of hydrothermal fluid around the ore body in the subseafloor of the Izena hydrothermal field

Science.gov (United States)

Toki, T.; Otake, T.; Ishibashi, J. I.; Matsui, Y.; Kawagucci, S.; Kato, H.; Fuchida, S.; Miyahara, R.; Tsutsumi, A.; Kawakita, R.; Uza, H.; Uehara, R.; Shinjo, R.; Nozaki, T.; Kumagai, H.; Maeda, L.

2017-12-01

From 16th November to 15th December 2016, D/V Chikyu drilled the sea bottom around hydrothermal fields at HAKUREI site in the Izena Hole, Okinawa Trough. Site C9025, C9026, C9027, C9028, and C9032 are located along the transect line from the top of the northern mound of HAKUREI site to the eastward, and Site C9030 for the control site is located about 500 m northwest of the mound. Mg concentrations have generally been used to estimate mixing ratios between hydrothermal end-member and seawater in samples from hydrothermal vents. Higher Mg concentrations, however, were detected in the interstitial water than that of seawater, which could be due to artificially dissolution of Mg-bearing minerals that had formed in in-situ environments, when the cored sediments had become cool after their recovery on ship. Similar features were observed with regard to sulfate concentrations, and it suggests that these chemical species are not suitable to estimate quantitatively the contribution of hydrothermally-derived components. In some layers, chloride concentrations were different from that of seawater, indicating that hydrothermal fluids that had been suffered from phase separation flowed into the layers. The deviation, however, was positive or negative relative to that of seawater for an influence of brine or vapor phase, respectively. Therefore chloride concentrations are also not suitable to evaluate a quantitative contribution of hydrothermal end-member. On the other hand, K and B showed only enrichments relative to the seawater, and their highest concentrations are consistent with the reported hydrothermal end-members of each species at HAKUREI site. Using the concentrations of K and B can be evaluated for an influence of hydrothermal components. Furthermore, the headspace gas data are useful in the layers of sulfide minerals and silicified rocks, even though the interstitial waters could not be obtained because of their hardness. Based on these indices, hydrothermal fluids

Sb(III)-Imprinted Organic-Inorganic Hybrid Sorbent Prepared by Hydrothermal-Assisted Surface Imprinting Technique for Selective Adsorption of Sb(III)

Science.gov (United States)

Zhang, Dan; Zhao, Yue; Xu, Hong-Bo

2018-03-01

Sb(III)-imprinted organic-inorganic hybrid sorbent was prepared by hydrothermal-assisted surface imprinting technique and was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy coupled to an energy dispersive spectrometer and N2 adsorption/desorption isotherms. Hydrothermal-assisted process can improve the selectivity of the Sb(III)-imprinted hybrid sorbent for Sb(III) due to stable control of temperature and pressure. The Sb(III)-imprinted hybrid sorbent IIS indicated higher selectivity for Sb(III), had high static adsorption capacity of 37.3 mg g-1 for Sb(III), displayed stable adsorption capacity in pH range from 4 to 8, reached an rapid adsorption equilibrium within 30 min. According to the correlation coefficient ( r 2 > 0.99), the experimental data fitted better the pseudo-second-order kinetic model and Langmuir equilibrium isotherm.

What Is High Blood Pressure?

Science.gov (United States)

... Disease Venous Thromboembolism Aortic Aneurysm More What is High Blood Pressure? Updated:Feb 27,2018 First, let’s define high ... resources . This content was last reviewed October 2016. High Blood Pressure • Home • Get the Facts About HBP Introduction What ...

Characteristics of Biochar Obtained by Hydrothermal Carbonization of Cellulose for Renewable Energy

OpenAIRE

Daegi Kim; Kunio Yoshikawa; Ki Young Park

2015-01-01

The effect of hydrothermal carbonization on the properties of cellulose present in lignocellulosic biomass was investigated for converting it into a renewable energy resource with high energy recovery efficiency. The biochar obtained from cellulose subjected to hydrothermal carbonization showed a significant increase in its carbon content and a calorific value. 13C NMR spectroscopy showed that when raw cellulose was subjected to hydrothermal carbonization above 220 °C, the resulting biochar h...

High Pressure Biomass Gasification

Energy Technology Data Exchange (ETDEWEB)

Agrawal, Pradeep K [Georgia Tech Research Corporation, Atlanta, GA (United States)

2016-07-29

According to the Billion Ton Report, the U.S. has a large supply of biomass available that can supplement fossil fuels for producing chemicals and transportation fuels. Agricultural waste, forest residue, and energy crops offer potential benefits: renewable feedstock, zero to low CO₂ emissions depending on the specific source, and domestic supply availability. Biomass can be converted into chemicals and fuels using one of several approaches: (i) biological platform converts corn into ethanol by using depolymerization of cellulose to form sugars followed by fermentation, (ii) low-temperature pyrolysis to obtain bio-oils which must be treated to reduce oxygen content via HDO hydrodeoxygenation), and (iii) high temperature pyrolysis to produce syngas (CO + H₂). This last approach consists of producing syngas using the thermal platform which can be used to produce a variety of chemicals and fuels. The goal of this project was to develop an improved understanding of the gasification of biomass at high pressure conditions and how various gasification parameters might affect the gasification behavior. Since most downstream applications of synags conversion (e.g., alcohol synthesis, Fischer-Tropsch synthesis etc) involve utilizing high pressure catalytic processes, there is an interest in carrying out the biomass gasification at high pressure which can potentially reduce the gasifier size and subsequent downstream cleaning processes. It is traditionally accepted that high pressure should increase the gasification rates (kinetic effect). There is also precedence from coal gasification literature from the 1970s that high pressure gasification would be a beneficial route to consider. Traditional approach of using thermogravimetric analyzer (TGA) or high-pressure themogravimetric analyzer (PTGA) worked well in understanding the gasification kinetics of coal gasification which was useful in designing high pressure coal gasification processes. However

High pressure phase transformations revisited

Science.gov (United States)

Levitas, Valery I.

2018-04-01

High pressure phase transformations play an important role in the search for new materials and material synthesis, as well as in geophysics. However, they are poorly characterized, and phase transformation pressure and pressure hysteresis vary drastically in experiments of different researchers, with different pressure transmitting media, and with different material suppliers. Here we review the current state, challenges in studying phase transformations under high pressure, and the possible ways in overcoming the challenges. This field is critically compared with fields of phase transformations under normal pressure in steels and shape memory alloys, as well as plastic deformation of materials. The main reason for the above mentioned discrepancy is the lack of understanding that there is a fundamental difference between pressure-induced transformations under hydrostatic conditions, stress-induced transformations under nonhydrostatic conditions below yield, and strain-induced transformations during plastic flow. Each of these types of transformations has different mechanisms and requires a completely different thermodynamic and kinetic description and experimental characterization. In comparison with other fields the following challenges are indicated for high pressure phase transformation: (a) initial and evolving microstructure is not included in characterization of transformations; (b) continuum theory is poorly developed; (c) heterogeneous stress and strain fields in experiments are not determined, which leads to confusing material transformational properties with a system behavior. Some ways to advance the field of high pressure phase transformations are suggested. The key points are: (a) to take into account plastic deformations and microstructure evolution during transformations; (b) to formulate phase transformation criteria and kinetic equations in terms of stress and plastic strain tensors (instead of pressure alone); (c) to develop multiscale continuum

High pressure phase transformations revisited.

Science.gov (United States)

Levitas, Valery I

2018-04-25

High pressure phase transformations play an important role in the search for new materials and material synthesis, as well as in geophysics. However, they are poorly characterized, and phase transformation pressure and pressure hysteresis vary drastically in experiments of different researchers, with different pressure transmitting media, and with different material suppliers. Here we review the current state, challenges in studying phase transformations under high pressure, and the possible ways in overcoming the challenges. This field is critically compared with fields of phase transformations under normal pressure in steels and shape memory alloys, as well as plastic deformation of materials. The main reason for the above mentioned discrepancy is the lack of understanding that there is a fundamental difference between pressure-induced transformations under hydrostatic conditions, stress-induced transformations under nonhydrostatic conditions below yield, and strain-induced transformations during plastic flow. Each of these types of transformations has different mechanisms and requires a completely different thermodynamic and kinetic description and experimental characterization. In comparison with other fields the following challenges are indicated for high pressure phase transformation: (a) initial and evolving microstructure is not included in characterization of transformations; (b) continuum theory is poorly developed; (c) heterogeneous stress and strain fields in experiments are not determined, which leads to confusing material transformational properties with a system behavior. Some ways to advance the field of high pressure phase transformations are suggested. The key points are: (a) to take into account plastic deformations and microstructure evolution during transformations; (b) to formulate phase transformation criteria and kinetic equations in terms of stress and plastic strain tensors (instead of pressure alone); (c) to develop multiscale continuum

High-resolution insights into episodes of crystallization, hydrothermal alteration and remelting in the Skaergaard intrusive complex

DEFF Research Database (Denmark)

Wotzlaw, Joern-Frederik; Bindeman, Ilya N.; Schaltegger, Urs

2012-01-01

of the most incompatible trace element rich horizon, similar to 100 m above SH. As the Skaergaard intrusion is also the most classic example of a shallow meteoric hydrothermal system, this work documents the alternating processes in a life of an intrusion with periods of hydrothermal cooling, heating by new...

High blood pressure - adults

Science.gov (United States)

... pressure is found. This is called essential hypertension. High blood pressure that is caused by another medical condition or medicine you are taking is called secondary hypertension. Secondary hypertension may be due to: Chronic ...

Characterising hydrothermal fluid pathways beneath Aluto volcano, Main Ethiopian Rift, using shear wave splitting

Science.gov (United States)

Nowacki, Andy; Wilks, Matthew; Kendall, J.-Michael; Biggs, Juliet; Ayele, Atalay

2018-05-01

Geothermal resources are frequently associated with silicic calderas which show evidence of geologically-recent activity. Hence development of geothermal sites requires both an understanding of the hydrothermal system of these volcanoes, as well as the deeper magmatic processes which drive them. Here we use shear wave splitting to investigate the hydrothermal system at the silicic peralkaline volcano Aluto in the Main Ethiopian Rift, which has experienced repeated uplift and subsidence since at least 2004. We make over 370 robust observations of splitting, showing that anisotropy is confined mainly to the top ∼3 km of the volcanic edifice. We find up to 10% shear wave anisotropy (SWA) is present with a maximum centred at the geothermal reservoir. Fast shear wave orientations away from the reservoir align NNE-SSW, parallel to the present-day minimum compressive stress. Orientations on the edifice, however, are rotated NE-SW in a manner we predict from field observations of faults at the surface, providing fluid pressures are sufficient to hold two fracture sets open. These fracture sets may be due to the repeated deformation experienced at Aluto and initiated in caldera formation. We therefore attribute the observed anisotropy to aligned cracks held open by over-pressurised gas-rich fluids within and above the reservoir. This study demonstrates that shear wave splitting can be used to map the extent and style of fracturing in volcanic hydrothermal systems. It also lends support to the hypothesis that deformation at Aluto arises from variations of fluid pressures in the hydrothermal system. These constraints will be crucial for future characterisation of other volcanic and geothermal systems, in rift systems and elsewhere.

Hydrothermal dolomite reservoir facies in the Sinian Dengying Fm, central Sichuan Basin

Directory of Open Access Journals (Sweden)

Yuqiang Jiang

2017-07-01

Full Text Available The Upper Sinian Dengying Fm is the focus of natural gas exploration in the central part of the Sichuan Basin (central Sichuan Basin in recent years. Especially, epigenic karstification and its resulted reservoir-seepage spaces have always been the focal points in researches. Based on the petrographic characteristics of drilling cuttings and core samples, and through experimental analysis by using trace elements, isotopes, and cathodoluminescence, the Dengying Fm dolomite was demonstrated to have matrix recrystallized dolomite (MRD, filled saddle dolomite (FSD (the mean homogenization temperature of inclusion: 178.5 °C, high concentrations of Fe & Mn, slightly positive 87Sr/86Sr value and hydrothermal minerals combination (including sphalerite, galena, pyrite, and quartz, etc.. Thus, it was proposed that hydrothermal dolomite reservoir facies (HDRF exist in the Dengying Fm dolomite, in other words, the dolomite reservoir is composed of hydrothermal dissolved pores, intercrystalline pores of hydrothermal origin, hydrothermal caverns and expanded fractures, and was formed due to the reworking of hydrothermal fluid on tight matrix dolomite. Identification marks are presented in terms of petrography and geochemistry so that hydrothermal dolomite reservoir facies can be effectively recognized and identified. It is concluded that the development of hydrothermal dolomite reservoir facies in this area are preliminary controlled by deep and large basement faults and the strength of hydrothermal fluids.

Borders of life: lessons from Microbiology of deep-sea hydrothermal vents

Science.gov (United States)

Prieur, D.

Thirty years ago, the deep-sea was known as a low density biotope due to coldness, darkness and famine-like conditions. The discovery of deep-sea hydrothermal vents in the Eastern Pacific in 1977 and the associated black smokers in 1979 considerably changed our views about life on Earth. For the first time, an ecosystem almost independent (at least for tens of years) of solar nergy was discovered. Besides the spectacular and unexpected communities of invertebrates based on symbiotic associations with chemo-litho-autotrophic bacteria, prokaryotic communities associated with high temperature black smokers fascinated microbiologists of extreme environments. Within mineral structures where temperature gradients may fluctuate from ambient seawater temperatures (2°C) up to 350°C, thermophilic (optimal growth above 60°C) and hyperthermophilic (optimal growth above 80°C) microorganisms thrived under very severe conditions due to elevated hydrostatic pressure, toxic compounds or strong ionizing radiations. These organisms belong to both domains of Bacteria and Archaea and live aerobically but mostly anaerobically, using a variety of inorganic and organic carbon sources, and a variety of electron donnors and acceptors as well. The most thermophilic organism known on Earth was isolated from a mid-Atlantic-Ridge hydrotermal vent: Pyrolobus fumarii grows optimally at 110°c and its upper temperature limit for life is 113°C. Such an organism survived to autoclaving conditions currently used for sterilization procedures. Many other hyperthermophilic organisms were isolated and described, including fermenters, sulphate and sulphur reducers, hydrogen oxidizers, nitrate reducers, methanogens, etc. Although most of anaerobes are killed when exposed to oxygen, several deep-sea hyperthermophiles appeared to survive to both oxygen and starvation exposures, indicating that they probably can colonize rather distant environments Because of elevated hydrostatic pressure that exists at

High blood pressure - medicine-related

Science.gov (United States)

Drug-induced hypertension is high blood pressure caused by using a chemical substance or medicine. ... of the arteries There are several types of high blood pressure : Essential hypertension has no cause that can be ...

Methane- and Hydrogen-Influenced Microbial Communities in Hydrothermal Plumes above the Atlantis Massif, Mid Atlantic Ridge

Science.gov (United States)

Stewart, C. L.; Schrenk, M.

2017-12-01

Ultramafic-hosted hydrothermal systems associated with slow-spreading mid ocean ridges emit copious amounts of hydrogen and methane into the deep-sea, generated through a process known as serpentinization. Hydrothermal plumes carrying the reduced products of water-rock interaction dissipate and mix with deep seawater, and potentially harbor microbial communities adapted to these conditions. Methane and hydrogen enriched hydrothermal plumes were sampled from 3 sites near the Atlantis Massif (30°N, Mid Atlantic Ridge) during IODP Expedition 357 and used to initiate cultivation experiments targeting methanotrophic and hydrogenotrophic microorganisms. One set of experiments incubated the cultures at in situ hydrostatic pressures and gas concentrations resulting in the enrichment of gammaproteobacterial assemblages, including Marinobacter spp. That may be involved in hydrocarbon degradation. A second set of experiments pursued the anaerobic enrichment of microbial communities on solid media, resulting in the enrichment of alphaproteobacteria related to Ruegeria. The most prodigious growth in both case occurred in methane-enriched media, which may play a role as both an energy and carbon source. Ongoing work is evaluating the physiological characteristics of these isolates, including their metabolic outputs under different physical-chemical conditions. In addition to providing novel isolates from hydrothermal habitats near the Lost City Hydrothermal Field, these experiments will provide insight into the ecology of microbial communities from serpentinization influenced hydrothermal systems that may aid in future exploration of these sites.

High-pressure microbiology

National Research Council Canada - National Science Library

Michiels, Chris; Bartlett, Douglas Hoyt; Aertsen, Abram

2008-01-01

... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. High Hydrostatic Pressure Effects in the Biosphere: from Molecules to Microbiology * Filip Meersman and Karel Heremans . . . . . . . . . . . . 2. Effects...

Experimental estimates of the energy budget of hydrothermal eruptions; application to 2012 Upper Te Maari eruption, New Zealand

Science.gov (United States)

Montanaro, Cristian; Scheu, Bettina; Cronin, Shane J.; Breard, Eric C. P.; Lube, Gert; Dingwell, Donald B.

2016-10-01

Sudden hydrothermal eruptions occur in many volcanic settings and may include high-energy explosive phases. Ballistics launched by such events, together with ash plumes and pyroclastic density currents, generate deadly proximal hazards. The violence of hydrothermal eruptions (or explosive power) depends on the energy available within the driving-fluids (gas or liquid), which also influences the explosive mechanisms, volumes, durations, and products of these eruptions. Experimental studies in addition to analytical modeling were used here to elucidate the fragmentation mechanism and aspects of energy balance within hydrothermal eruptions. We present results from a detailed study of recent event that occurred on the 6th of August 2012 at Upper Te Maari within the Tongariro volcanic complex (New Zealand). The eruption was triggered by a landslide from this area, which set off a rapid stepwise decompression of the hydrothermal system. Explosive blasts were directed both westward and eastward of the collapsed area, with a vertical ash plume sourced from an adjacent existing crater. All explosions ejected blocks on ballistic trajectories, hundreds of which impacted New Zealand's most popular hiking trail and a mountain lodge, 1.4 km from the explosion locus. We have employed rocks representative of the eruption source area to perform rapid decompression experiments under controlled laboratory conditions that mimic hydrothermal explosions under controlled laboratory conditions. An experimental apparatus for 34 by 70 mm cylindrical samples was built to reduce the influence of large lithic enclaves (up to 30 mm in diameter) within the rock. The experiments were conducted in a temperature range of 250 °C-300 °C and applied pressure between 4 MPa and 6.5 MPa, which span the range of expected conditions below the Te Maari crater. Within this range we tested rapid decompression of pre-saturated samples from both liquid-dominated conditions and the vapor-dominated field

Impact-generated Hydrothermal Activity at the Chicxulub Crater

Science.gov (United States)

Kring, D. A.; Zurcher, L.; Abramov, O.

2007-05-01

Borehole samples recovered from PEMEX exploration boreholes and an ICDP scientific borehole indicate the Chicxulub impact event generated hydrothermal alteration throughout a large volume of the Maya Block beneath the crater floor and extending across the bulk of the ~180 km diameter crater. The first indications of hydrothermal alteration were observed in the crater discovery samples from the Yucatan-6 borehole and manifest itself in the form of anhydrite and quartz veins. Continuous core from the Yaxcopoil-1 borehole reveal a more complex and temporally extensive alteration sequence: following a brief period at high temperatures, impact- melt-bearing polymict breccias and a thin, underlying unit of impact melt were subjected to metasomatism, producing alkali feldspar, sphene, apatite, and magnetite. As the system continued to cool, smectite-series phyllosilicates appeared. A saline solution was involved. Stable isotopes suggest the fluid was dominated by a basinal brine created mostly from existing groundwater of the Yucatan Peninsula, although contributions from down-welling water also occurred in some parts of the system. Numerical modeling of the hydrothermal system suggests circulation occurred for 1.5 to 2.3 Myr, depending on the permeability of the system. Our understanding of the hydrothermal system, however, is still crude. Additional core recovery projects, particularly into the central melt sheet, are needed to better evaluate the extent and duration of hydrothermal alteration.

Fault-controlled development of shallow hydrothermal systems: Structural and mineralogical insights from the Southern Andes

Science.gov (United States)

Roquer, T.; Arancibia, G.; Rowland, J. V.; Iturrieta, P. C.; Morata, D.; Cembrano, J. M.

2017-12-01

Paleofluid-transporting systems can be recognized as meshes of fracture-filled veins in eroded zones of extinct hydrothermal systems. Here we conducted meso-microstructural analysis and mechanical modeling from two exhumed exposures of the faults governing regional tectonics of the Southern Andes: the Liquiñe-Ofqui Fault System (LOFS) and the Andean Transverse Faults (ATF). A total of 107 fractures in both exposures were analyzed. The ATF specific segment shows two tectonic solutions that can be modeled as Andersonian and non-Andersonian tectonic regimes: (1) shear (mode II/III) failure occurs at differential stresses > 28 MPa and fluid pressures 85-98% lithostatic in the non-Andersonian regime. Additionally, the LOFS exposure cyclically fails in extension (mode I) or extension + shear (modes I + II/III) in the Andersonian regime, at differential stresses 40-80% lithostatic. In areas of spatial interaction between ATF and LOFS, these conditions might favor: (1) the storage of overpressured fluids in hydrothermal systems associated with the ATF faults, and (2) continuous fluid flow through vertical conduits in the LOFS faults. These observations suggest that such intersections are highly probable locations for concentrated hydrothermal activity, which must be taken into consideration for further geothermal exploration. ACKNOWLEDGEMENTS. PhD CONICYT grants, Centro de Excelencia en Geotermia de los Andes (CEGA-FONDAP/CONICYT Project #15090013), FONDECYT Project #1130030 and Project CONICYT REDES #140036.

Hydrothermal synthesis of magnetic reduced graphene oxide sheets

International Nuclear Information System (INIS)

Shen, Jianfeng; Shi, Min; Ma, Hongwei; Yan, Bo; Li, Na; Ye, Mingxin

2011-01-01

Graphical abstract: An environmental friendly and efficient route for preparation of magnetic reduced graphene oxide composite with a one-step hydrothermal method was demonstrated. The reducing process was accompanied by generation of magnetic nanoparticles. Highlights: → A one-step hydrothermal method for preparation of MN-CCG was demonstrated. → Glucose was used as the 'green' reducing agent. → The reducing process was accompanied by generation of magnetic nanoparticles. → The prepared MN-CCG is highly water suspendable and sensitive to magnetic field. -- Abstract: We demonstrated an environmental friendly and efficient route for preparation of magnetic reduced graphene oxide composite (MN-CCG). Glucose was used as the reducing agent in this one-step hydrothermal method. The reducing process was accompanied by generation of magnetic nanoparticles. The structure and composition of the nanocomposite was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, thermal gravimetric analysis, atomic force microscopy and transmission electron microscopy. It was found that the prepared MN-CCG is highly water suspendable and sensitive to magnetic field.

High-purity aluminium creep under high hydrostatic pressure

International Nuclear Information System (INIS)

Zajtsev, V.I.; Lyafer, E.I.; Tokij, V.V.

1977-01-01

The effect of the hydrostatic pressure on the rate of steady-state creep of high-purity aluminium was investigated. It is shown that the hydrostatic pressure inhibits the creep. The activation volume of the creep is independent of the direction in the range of (4.7-6.2) kg/mm 2 and of the pressure in the range of (1-7.8000) atm. It is concluded that self-diffusion does not control the creep of high-purity aluminium at room temperature in the investigated stress and pressure range

High-performance hybrid pervaporation membranes with superior hydrothermal and acid stability

Energy Technology Data Exchange (ETDEWEB)

Castricum, H.L. [Inorganic Materials Science, MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Blank, D.H.A.; Ten Elshof, J.E. [Van ' t Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam (Netherlands); Kreiter, R.; Van Veen, H.M.; Vente, J.F. [ECN Efficiency and Infrastructure, Petten (Netherlands)

2009-05-15

A new organic-inorganic hybrid membrane has been prepared with exceptional performance in dewatering applications. The only precursor used in the sol-gel synthesis of the selective layer was organically linked 1,2-bis(triethoxysilyl)ethane (BTESE). The microporous structure of this layer enables selective molecular sieving of small molecules from larger ones. In the dehydration of n-butanol with 5% of water, the membrane shows a high separation factor of over 4000 and ultra-fast water transport at a rate of more than 20 kg m{sup -2} h{sup -1} at 150C. This can be related to the high adsorption capacity of the material and the sub-micron thickness of the selective layer. The selectivity has now remained constant over almost one and a half years under continuous process testing conditions. Apart from the hydrothermal stability, the membrane exhibits a high tolerance for acid contamination. A slow performance decline in flux and separation factor is only observed at a pH lower than 2. The high stability and effective separation indicate a broad industrial application potential of the hybrid membrane material.

Magma-Hydrothermal Transition: Basalt Alteration at Supercritical Conditions in Drill Core from Reykjanes, Iceland, Iceland Deep Drilling Project.

Science.gov (United States)

Zierenberg, R. A.; Fowler, A. P.; Schiffman, P.; Fridleifsson, G. Ó.; Elders, W. A.

2017-12-01

The Iceland Deep Drilling Project well IDDP-2, drilled to 4,659 m in the Reykjanes geothermal system, the on-land extension of the Mid Atlantic Ridge, SW Iceland. Drill core was recovered, for the first time, from a seawater-recharged, basalt-hosted hydrothermal system at supercritical conditions. The well has not yet been allowed to heat to in situ conditions, but temperature and pressure of 426º C and 340 bar was measured at 4500 m depth prior to the final coring runs. Spot drill cores were recovered between drilling depths of 3648.00 m and 4657.58 m. Analysis of the core is on-going, but we present the following initial observations. The cored material comes from a basaltic sheeted dike complex in the brittle-ductile transition zone. Felsic (plagiogranite) segregation veins are present in minor amounts in dikes recovered below 4300 m. Most core is pervasively altered to hornblende + plagioclase, but shows only minor changes in major and minor element composition. The deepest samples record the transition from the magmatic regime to the presently active hydrothermal system. Diabase near dike margins has been locally recrystallized to granoblastic-textured orthopyroxene-clinopyroxe-plagioclase hornfels. High temperature hydrothermal alteration includes calcic plagioclase (up to An100) and aluminous hornblende (up to 11 Wt. % Al2O3) locally intergrown with hydrothermal biotite, clinopyroxene, orthopyroxene and/or olivine. Hydrothermal olivine is iron-rich (Mg # 59-64) compared to expected values for igneous olivine. Biotite phenocrysts in felsic segregation veins have higher Cl and Fe compared to hydrothermal biotites. Orthopyroxene-clinopyroxene pairs in partially altered quench dike margins give temperature of 955° to 1067° C. Orthopyroxene-clinopyroxene pairs from hornfels and hydrothermal veins and replacements give temperature ranging from 774° to 888° C. Downhole fluid sampling is planned following thermal equilibration of the drill hole. Previous work

High pressure study of water-salt systems, phase equilibria, partitioning, thermodynic properties and implication for large icy worlds hydrospheres.

Science.gov (United States)

Journaux, B.; Brown, J. M.; Abramson, E.; Petitgirard, S.; Pakhomova, A.; Boffa Ballaran, T.; Collings, I.

2017-12-01

Water salt systems are predicted to be present in deep hydrosphere inside water-rich planetary bodies, following water/rock chemical interaction during early differentiation stages or later hydrothermal activity. Unfortunately the current knowledge of the thermodynamic and physical properties of aqueous salt mixtures at high pressure and high temperature is still insufficient to allow realistic modeling of the chemical or dynamic of thick planetary hydrospheres. Recent experimental results have shown that the presence of solutes, and more particularly salts, in equilibrium with high pressure ices have large effects on the stability fields, buoyancy and chemistry of all the phases present at these extreme conditions. Effects currently being investigated by our research group also covers ice melting curve depressions that depend on the salt species and incorporation of solutes inside the crystallographic lattice of high pressure ices. Both of these could have very important implication at the planetary scale, enabling thicker/deeper liquid oceans, and allowing chemical transportation through the high pressure ice layer in large icy worlds. We will present the latest results obtained in-situ using diamond anvil cell, coupled with Synchrotron X-Ray diffraction, Raman Spectroscopy and optical observations, allowing to probe the crystallographic structure, equations of state, partitioning and phase boundary of high pressure ice VI and VII in equilibrium with Na-Mg-SO4-Cl ionic species at high pressures (1-10 GPa). The difference in melting behavior depending on the dissolved salt species was characterized, suggesting differences in ionic speciation at liquidus conditions. The solidus P-T conditions were also measured as well as an increase of lattice volumes interpreted as an outcome of ionic incorporation in HP ice during incongruent crystallization. The measured phase diagrams, lattice volumes and important salt incorporations suggest a more complex picture of the

High pressure experimental water loop

International Nuclear Information System (INIS)

Grenon, M.

1958-01-01

A high pressure experimental water loop has been made for studying the detection and evolution of cladding failure in a pressurized reactor. The loop has been designed for a maximum temperature of 360 deg. C, a maximum of 160 kg/cm 2 and flow rates up to 5 m 3 /h. The entire loop consists of several parts: a main circuit with a canned rotor circulation pump, steam pressurizer, heating tubes, two hydro-cyclones (one de-gasser and one decanter) and one tubular heat exchanger; a continuous purification loop, connected in parallel, comprising pressure reducing valves and resin pots which also allow studies of the stability of resins under pressure, temperature and radiation; following the gas separator is a gas loop for studying the recombination of the radiolytic gases in the steam phase. The preceding circuits, as well as others, return to a low pressure storage circuit. The cold water of the low pressure storage flask is continuously reintroduced into the high pressure main circuit by means of a return pump at a maximum head of 160 kg /cm 2 , and adjusted to the pressurizer level. This loop is also a testing bench for the tight high pressure apparatus. The circulating pump and the connecting flanges (Oak Ridge type) are water-tight. The feed pump and the pressure reducing valves are not; the un-tight ones have a system of leak recovery. To permanently check the tightness the circuit has been fitted with a leak detection system (similar to the HRT one). (author) [fr

Common High Blood Pressure Myths

Science.gov (United States)

... Disease Venous Thromboembolism Aortic Aneurysm More Common High Blood Pressure Myths Updated:May 4,2018 Knowing the facts ... This content was last reviewed October 2016. High Blood Pressure • Home • Get the Facts About HBP Introduction What ...

Medications for High Blood Pressure

Science.gov (United States)

... Consumers Home For Consumers Consumer Updates Medications for High Blood Pressure Share Tweet Linkedin Pin it More sharing options ... age and you cannot tell if you have high blood pressure by the way you feel, so have your ...

High blood pressure and diet

Science.gov (United States)

... this page: //medlineplus.gov/ency/article/007483.htm High blood pressure and diet To use the sharing features on ... diet is a proven way to help control high blood pressure . These changes can also help you lose weight ...

Hydrothermal synthesis of polyethylenimine-protected high luminescent Pt-nanoclusters and their application to the detection of nitroimidazoles

International Nuclear Information System (INIS)

Xu, Na; Li, Hong-Wei; Wu, Yuqing

2017-01-01

A novel one-step hydrothermal synthesis of highly fluorescent platinum nanoclusters protected by polyethylenimine (Pt-NCs@PEI) is described. The products are characterized well by UV–vis absorption, fluorescence spectra, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) imaging. The Pt-NCs@PEI possess high quantum yield at 28%, which is the relatively high one among the reported Pt-NCs; especially, the synthesis is in one-step and the reaction time is much shorter (<1 h) than the related methods. In addition, the Pt-NCs@PEI have large Stocks-shift (∼150 nm), high tolerability to the extreme pH and high ionic strengths, and excellent photo-stability under UV–vis irradiation, lay the foundation for the practical bio-applications. Finally, the obtained Pt-NCs@PEI are used to determine trace amount of metronidazole (MTZ) in buffer solution in showing a linear response over a concentration range of 0.25–300 μM and a low detection limit of 0.1 μM. Furthermore, the related investigation on response mechanism will be helpful to design and synthesize new metal nanoclusters as fluorescent probe to detect the trace amount of harmful medicine residuum as nitroimidazoles in human body. - Highlights: • This paper provides the first hydrothermal synthesis of platinum nanoclusters. • The prepared polyethylenimine-protected platinum nanoclusters possess high quantum yield of 28%. • A new method to detect trace amount of metronidazole in urine is proposed.

Hydrothermal synthesis of polyethylenimine-protected high luminescent Pt-nanoclusters and their application to the detection of nitroimidazoles

Energy Technology Data Exchange (ETDEWEB)

Xu, Na [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012 (China); College of Materials Science and Engineering, Jilin Institute of Chemical Technology, Jilin, 132022 (China); Li, Hong-Wei, E-mail: lihongwei@jlu.edu.cn [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012 (China); Wu, Yuqing, E-mail: yqwu@jlu.edu.cn [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012 (China)

2017-03-15

A novel one-step hydrothermal synthesis of highly fluorescent platinum nanoclusters protected by polyethylenimine (Pt-NCs@PEI) is described. The products are characterized well by UV–vis absorption, fluorescence spectra, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) imaging. The Pt-NCs@PEI possess high quantum yield at 28%, which is the relatively high one among the reported Pt-NCs; especially, the synthesis is in one-step and the reaction time is much shorter (<1 h) than the related methods. In addition, the Pt-NCs@PEI have large Stocks-shift (∼150 nm), high tolerability to the extreme pH and high ionic strengths, and excellent photo-stability under UV–vis irradiation, lay the foundation for the practical bio-applications. Finally, the obtained Pt-NCs@PEI are used to determine trace amount of metronidazole (MTZ) in buffer solution in showing a linear response over a concentration range of 0.25–300 μM and a low detection limit of 0.1 μM. Furthermore, the related investigation on response mechanism will be helpful to design and synthesize new metal nanoclusters as fluorescent probe to detect the trace amount of harmful medicine residuum as nitroimidazoles in human body. - Highlights: • This paper provides the first hydrothermal synthesis of platinum nanoclusters. • The prepared polyethylenimine-protected platinum nanoclusters possess high quantum yield of 28%. • A new method to detect trace amount of metronidazole in urine is proposed.

Hydrothermal signature in the axial-sediments from the Carlsberg Ridge in the northwest Indian Ocean

Science.gov (United States)

Yu, Zenghui; Li, Huaiming; Li, Mengxing; Zhai, Shikui

2018-04-01

30 sediments grabbed from 24 sites between the equator and 10°N along the Carlsberg Ridge (CR) in the northwest Indian Ocean has been analyzed for bulk chemical compositions. Hydrothermal components in the sediments are identified and characterized. They mainly occur at 6.3°N as sulfide debris and at 3.6°N as both sulfide and high temperature water-rock interaction products. The enrichment of chalcophile elements such as Zn, Cu, Pb and the depletion of alkalis metals such as K and Rb are the typical features of hydrothermal components. High U/Fe, low (Nd/Yb)N and negative Ce anomaly infer the uptake of seawater in the hydrothermal deposits by oxidizing after deposition. However, the general enrichment of Mn in hydrothermal plumed-derived materials is not found in the sediments, which may indicate the limited diffusion of fluids or plumes, at least in the direction along the Carlsberg spreading center. The hydrothermal components show their similarity to the hydrothermal deposits from the Indian Ocean Ridge. At 3.6°N ultramafic rocks or gabbroic intrusions, may be involved in the hydrothermal system.

Chemistry of a serpentinization-controlled hydrothermal system at the Lost City hydrothermal vent field

Science.gov (United States)

Ludwig, K. A.; Kelley, D. S.; Butterfield, D. A.; Nelson, B. K.; Karson, J. A.

2003-12-01

The Lost City Hydrothermal Field (LCHF), at 30° N near the Mid-Atlantic Ridge, is an off-axis, low temperature, high-pH, ultramafic-hosted vent system. Within the field, carbonate chimneys tower up to 60 m above the seafloor, making them the tallest vent structures known. The chemistry of the vent structures and fluids at the LCHF is controlled by reactions between seawater and ultramafic rocks beneath the Atlantis massif. Mixing of warm alkaline vent fluids with seawater causes precipitation of calcium carbonate and growth of the edifaces, which range from tall, graceful pinnacles to fragile flanges and colloform deposits. Geochemical and petrological analyses of the carbonate rocks reveal distinct differences between the active and extinct structures. Actively venting chimneys and flanges are extremely porous, friable formations composed predominantly of aragonite and brucite. These structures provide important niches for well-developed microbial communities that thrive on and within the chimney walls. Some of the active chimneys may also contain the mineral ikaite, an unstable, hydrated form of calcium carbonate. TIMS and ICP-MS analyses of the carbonate chimneys show that the most active chimneys have low Sr isotope values and that they are low in trace metals (e.g., Mn, Ti, Pb). Active structures emit high-pH, low-Mg fluids at 40-90° C. The fluids also have low Sr values, indicating circulation of hydrothermal solutions through the serpentinite bedrock beneath the field. In contrast to the active structures, extinct chimneys are less porous, are well lithified, and they are composed predominantly of calcite that yields Sr isotopes near seawater values. Prolonged lower temperature seawater-hydrothermal fluid interaction within the chimneys results in the conversion of aragonite to calcite and in the enrichment of some trace metals (e.g., Mn, Ti, Co, Zn). It also promotes the incorporation of foraminifera within the outer, cemented walls of the carbonate

An in situ vapour phase hydrothermal surface doping approach for fabrication of high performance Co3O4 electrocatalysts with an exceptionally high S-doped active surface.

Science.gov (United States)

Tan, Zhijin; Liu, Porun; Zhang, Haimin; Wang, Yun; Al-Mamun, Mohammad; Yang, Hua Gui; Wang, Dan; Tang, Zhiyong; Zhao, Huijun

2015-04-04

A facile in situ vapour phase hydrothermal (VPH) surface doping approach has been developed for fabrication of high performance S-doped Co3O4 electrocatalysts with an unprecedentedly high surface S content (>47%). The demonstrated VPH doping approach could be useful for enrichment of surface active sites for other metal oxide electrocatalysts.

High pressure effects on fruits and vegetables

NARCIS (Netherlands)

Timmermans, R.A.H.; Matser, A.M.

2016-01-01

The chapter provides an overview on different high pressure based treatments (high pressure pasteurization, blanching, pressure-assisted thermal processing, pressure-shift freezing and thawing) available for the preservation of fruits and vegetable products and extending their shelf life. Pressure

Hydrothermal liquefaction of microalgae's for bio oil production

DEFF Research Database (Denmark)

Toor, Saqib; Reddy, Harvind; Deng, Shuguang

process water for algae cultivation. GC-MS, elemental analyzer, calorimeter and nutrient analysis were used to analyze bio-crude, lipid-extracted algae and water samples produced in the hydrothermal liquefaction process. The highest bio-oil yield of 46% was obtained on Nannochloropsis salina at 310 °C...... and 107 bar. For Spirulina platensis algae sample, the highest bio-oil yield is 38% at 350 °C and 195 bar. Preliminary data also indicate that a lipid-extracted algae solid residue sample obtained in the hydrothermal liquefaction process contains a high level of proteins...

Method transfer from high-pressure liquid chromatography to ultra-high-pressure liquid chromatography. II. Temperature and pressure effects.

Science.gov (United States)

Åsberg, Dennis; Samuelsson, Jörgen; Leśko, Marek; Cavazzini, Alberto; Kaczmarski, Krzysztof; Fornstedt, Torgny

2015-07-03

The importance of the generated temperature and pressure gradients in ultra-high-pressure liquid chromatography (UHPLC) are investigated and compared to high-pressure liquid chromatography (HPLC). The drug Omeprazole, together with three other model compounds (with different chemical characteristics, namely uncharged, positively and negatively charged) were used. Calculations of the complete temperature profile in the column at UHPLC conditions showed, in our experiments, a temperature difference between the inlet and outlet of 16 °C and a difference of 2 °C between the column center and the wall. Through van't Hoff plots, this information was used to single out the decrease in retention factor (k) solely due to the temperature gradient. The uncharged solute was least affected by temperature with a decrease in k of about 5% while for charged solutes the effect was more pronounced, with k decreases up to 14%. A pressure increase of 500 bar gave roughly 5% increase in k for the uncharged solute, while omeprazole and the other two charged solutes gave about 25, 20 and 15% increases in k, respectively. The stochastic model of chromatography was applied to estimate the dependence of the average number of adsorption/desorption events (n) and the average time spent by a molecule in the stationary phase (τs) on temperature and pressure on peak shape for the tailing, basic solute. Increasing the temperature yielded an increase in n and decrease in τs which resulted in less skew at high temperatures. With increasing pressure, the stochastic modeling gave interesting results for the basic solute showing that the skew of the peak increased with pressure. The conclusion is that pressure effects are more pronounced for both retention and peak shape than the temperature effects for the polar or charged compounds in our study. Copyright © 2015 Elsevier B.V. All rights reserved.

High-pressure high-temperature experiments: Windows to the Universe

International Nuclear Information System (INIS)

Santaria-Perez, D.

2011-01-01

From Earth compositional arguments suggested by indirect methods, such as the propagation of seismic waves, is possible to generate in the laboratory pressure and temperature conditions similar to those of the Earth or other planet interiors and to study how these conditions affect to a certain metal or mineral. These experiments are, therefore, windows to the Universe. The aim of this chapter is to illustrate the huge power of the experimental high-pressure high-temperature techniques and give a global overview of their application to different geophysical fields. Finally, we will introduce the MALTA Consolider Team, which gather most of the Spanish high-pressure community, and present their available high-pressure facilities. (Author) 28 refs.

Hydrothermal activity, functional diversity and chemoautotrophy are major drivers of seafloor carbon cycling

NARCIS (Netherlands)

Bell, J.B.; Woulds, C.; van Oevelen, D.

2017-01-01

Hydrothermal vents are highly dynamic ecosystems and are unusually energy rich in the deep-sea. Insitu hydrothermal-based productivity combined with sinking photosynthetic organic matter in a softsedimentsetting creates geochemically diverse environments, which remain poorly studied. Here,we use

Catalytic Hydrothermal Conversion of Wet Biomass Feedstocks and Upgrading – Process Design and Optimization

DEFF Research Database (Denmark)

Hoffmann, Jessica; Toor, Saqib; Rosendahl, Lasse

Liquid biofuels will play a major role for a more sustainable energy system of the future. The CatLiq® process is a 2nd generation biomass conversion process that is based on hydrothermal liquefaction. Hydrothermal liquefaction offers a very efficient and feedstock flexible way of converting...... biomass to bio-oil. Bio-oils from hydrothermal liquefaction are characterised by their high feedstock flexibility. Upgrading of complete bio-oils derived from hydrothermal conversion has not yet been extensively studied. Purpose of this work is to reduce the oxygen content of the bio-oil to improve...

One-step hydrothermal synthesis of hexangular starfruit-like vanadium oxide for high power aqueous supercapacitors

Science.gov (United States)

Shao, Jie; Li, Xinyong; Qu, Qunting; Zheng, Honghe

2012-12-01

Homogenous hexangular starfruit-like vanadium oxide was prepared for the first time by a one-step hydrothermal method. The assembly process of hexangular starfruit-like structure was observed from TEM images. The electrochemical performance of starfruit-like vanadium oxide was examined by cyclic voltammetry and galvanostatic charge/discharge. The obtained starfruit-like vanadium oxide exhibits a high power capability (19 Wh kg-1 at the specific power of 3.4 kW kg-1) and good cycling stability for supercapacitors application.

Carbon dioxide in magmas and implications for hydrothermal systems

Science.gov (United States)

Lowenstern, J. B.

2001-01-01

This review focuses on the solubility, origin, abundance, and degassing of carbon dioxide (CO2) in magma-hydrothermal systems, with applications for those workers interested in intrusion-related deposits of gold and other metals. The solubility of CO2 increases with pressure and magma alkalinity. Its solubility is low relative to that of H2O, so that fluids exsolved deep in the crust tend to have high CO2/H2O compared with fluids evolved closer to the surface. Similarly, CO2/H2O will typically decrease during progressive decompression- or crystallization-induced degassing. The temperature dependence of solubility is a function of the speciation of CO2, which dissolves in molecular form in rhyolites (retrograde temperature solubility), but exists as dissolved carbonate groups in basalts (prograde). Magnesite and dolomite are stable under a relatively wide range of mantle conditions, but melt just above the solidus, thereby contributing CO2 to mantle magmas. Graphite, diamond, and a free CO2-bearing fluid may be the primary carbon-bearing phases in other mantle source regions. Growing evidence suggests that most CO2 is contributed to arc magmas via recycling of subducted oceanic crust and its overlying sediment blanket. Additional carbon can be added to magmas during magma-wallrock interactions in the crust. Studies of fluid and melt inclusions from intrusive and extrusive igneous rocks yield ample evidence that many magmas are vapor saturated as deep as the mid crust (10-15 km) and that CO2 is an appreciable part of the exsolved vapor. Such is the case in both basaltic and some silicic magmas. Under most conditions, the presence of a CO2-bearing vapor does not hinder, and in fact may promote, the ascent and eruption of the host magma. Carbonic fluids are poorly miscible with aqueous fluids, particularly at high temperature and low pressure, so that the presence of CO2 can induce immiscibility both within the magmatic volatile phase and in hydrothermal systems

Nuclear magnetic resonance studies at high pressures

International Nuclear Information System (INIS)

Jonas, J.

1980-01-01

Recent advances in the field of NMR spectroscopy at high pressure are reviewed. After a brief discussion of two novel experimental techniques, the main focus of this review is on several specific studies which illustrate the versatility and power of this high pressure field. Experimental aspects of NMR measurements at high pressure and high temperature and the techniques for the high resolution NMR spectroscopy at high pressure are discussed. An overview of NMR studies of the dynamic structure of simple polyatomic liquids and hydrogen bonded liquids is followed by a discussion of high resolution spectroscopy at high pressure. Examples of NMR studies of disordered organic solids and polymers conclude the review. (author)

The origin of methanethiol in midocean ridge hydrothermal fluids.

Science.gov (United States)

Reeves, Eoghan P; McDermott, Jill M; Seewald, Jeffrey S

2014-04-15

Simple alkyl thiols such as methanethiol (CH3SH) are widely speculated to form in seafloor hot spring fluids. Putative CH3SH synthesis by abiotic (nonbiological) reduction of inorganic carbon (CO2 or CO) has been invoked as an initiation reaction for the emergence of protometabolism and microbial life in primordial hydrothermal settings. Thiols are also presumptive ligands for hydrothermal trace metals and potential fuels for associated microbial communities. In an effort to constrain sources and sinks of CH3SH in seafloor hydrothermal systems, we determined for the first time its abundance in diverse hydrothermal fluids emanating from ultramafic, mafic, and sediment-covered midocean ridge settings. Our data demonstrate that the distribution of CH3SH is inconsistent with metastable equilibrium with inorganic carbon, indicating that production by abiotic carbon reduction is more limited than previously proposed. CH3SH concentrations are uniformly low (∼10(-8) M) in high-temperature fluids (>200 °C) from all unsedimented systems and, in many cases, suggestive of metastable equilibrium with CH4 instead. Associated low-temperature fluids (<200 °C) formed by admixing of seawater, however, are invariably enriched in CH3SH (up to ∼10(-6) M) along with NH4(+) and low-molecular-weight hydrocarbons relative to high-temperature source fluids, resembling our observations from a sediment-hosted system. This strongly implicates thermogenic interactions between upwelling fluids and microbial biomass or associated dissolved organic matter during subsurface mixing in crustal aquifers. Widespread thermal degradation of subsurface organic matter may be an important source of organic production in unsedimented hydrothermal systems and may influence microbial metabolic strategies in cooler near-seafloor and plume habitats.

Exploration Method Development for hydrothermal plume hunting by XCTD

Science.gov (United States)

Kitagawa, Y.; Ikeda, M.; Kadoshima, K.; Koizumi, Y.; Nakano, J.; Asakawa, E.; Sumi, T.

2017-12-01

J-MARES (Research and Development Partnership for Next Generation Technology of Marine Resources Survey, JAPAN) has been designing a low-cost and high-efficiency exploration system for seafloor hydrothermal massive sulfide deposits in "Cross-ministerial Strategic Innovation Promotion Program (SIP)" granted by the Cabinet Office, Government of Japan since 2014. We proposed hydrothermal plume hunting by XCTD (eXpendables Conductivity, Temperature and Depth). We applied this method to an area of interest more than 100km x 100km over Okinawa Trough, including some known seafloor massive sulfide deposits. Generally, hydrothermal plume exploration has been by ship mounted with MBES (Multi Beam Echo Sounder) or AUV with sound anomaly observation. However, these methods have to charter the sophisticated ship costly. On the other hand, throw-in type water quality meters (eg. XCTD and XBT) can be low-cost and easily operable. Moreover, that can make a quick look at seawater temperature and conductivity even in rough waters.Firstly, we confirmed XCTD probes position on the seafloor by ROV mounted deep-sea high vision camera. As a result of the test, probes swept downstream about 40 m in horizontal distance from throwing positions with about 1,600m in water depth. Following the previous test results, we had performed to the next test that confirmed detection range of hydrothermal plume at the chimney of North Mound in Izena Cauldron, so we had caught anomaly of seawater temperature and conductivity successfully which could be possibly derived from hydrothermal activities. Although averaged seawater temperature at a depth of 1500 m or more was about 3.95 degrees C, near the chimney was about 4.93 degrees C. The temperature anomalies originated from the hydrothermal plumes could be distributed at most 30m in horizontal distance and became smaller away from the chimney. Moreover, temperature anomaly mass of sea water tended to move upward in depth with distance away from the

High pressure effects on fruits and vegetables

OpenAIRE

Timmermans, R.A.H.; Matser, A.M.

2016-01-01

The chapter provides an overview on different high pressure based treatments (high pressure pasteurization, blanching, pressure-assisted thermal processing, pressure-shift freezing and thawing) available for the preservation of fruits and vegetable products and extending their shelf life. Pressure treatment can be used for product modification through pressure gelatinization of starch and pressure denaturation of proteins. Key pressure–thermal treatment effects on vitamin, enzymes, flavor, co...

Conversion of a wet waste feedstock to biocrude by hydrothermal processing in a continuous-flow reactor: grape pomace

Energy Technology Data Exchange (ETDEWEB)

Elliott, Douglas C.; Schmidt, Andrew J.; Hart, Todd R.; Billing, Justin M.

2017-05-13

Wet waste feedstocks present an apt opportunity for biomass conversion to fuels by hydrothermal processing. In this study, grape pomace slurries from two varieties, Montepulciano and cabernet sauvignon, have been converted into a biocrude by hydrothermal liquefaction (HTL) in a bench-scale, continuous-flow reactor system. Carbon conversion to gravity-separable biocrude product up to 56 % was accomplished at relatively low temperature (350 C) in a pressurized (sub-critical liquid water) environment (20 MPa) when using grape pomace feedstock slurry with a 16.8 wt% concentration of dry solids processed at a liquid hourly space velocity of 2.1 h-1. Direct oil recovery was achieved without the use of a solvent and biomass trace mineral components were removed by processing steps so that they did not cause processing difficulties. In addition, catalytic hydrothermal gasification (CHG) was effectively applied for HTL byproduct water cleanup using a Ru on C catalyst in a fixed bed producing a gas composed of methane and carbon dioxide from water soluble organics. Conversion of 99.8% of the chemical oxygen demand (COD) left in the aqueous phase was demonstrated. As a result, high conversion of grape pomace to liquid and gas fuel products was found with residual organic contamination in byproduct water reduced to <150 mg/kg COD.

High Blood Pressure - Multiple Languages

Science.gov (United States)

... Being 8 - High Blood Pressure - Amarɨñña / አማርኛ (Amharic) MP3 Siloam Family Health Center Arabic (العربية) Expand Section ... Being 8 - High Blood Pressure - myanma bhasa (Burmese) MP3 Siloam Family Health Center Chinese, Simplified (Mandarin dialect) ( ...

Anxiety: A Cause of High Blood Pressure?

Science.gov (United States)

... of high blood pressure? Can anxiety cause high blood pressure? Answers from Sheldon G. Sheps, M.D. Anxiety doesn't cause long-term high blood pressure (hypertension). But episodes of anxiety can cause dramatic, ...

High-throughput continuous hydrothermal synthesis of an entire nanoceramic phase diagram.

Science.gov (United States)

Weng, Xiaole; Cockcroft, Jeremy K; Hyett, Geoffrey; Vickers, Martin; Boldrin, Paul; Tang, Chiu C; Thompson, Stephen P; Parker, Julia E; Knowles, Jonathan C; Rehman, Ihtesham; Parkin, Ivan; Evans, Julian R G; Darr, Jawwad A

2009-01-01

A novel High-Throughput Continuous Hydrothermal (HiTCH) flow synthesis reactor was used to make directly and rapidly a 66-sample nanoparticle library (entire phase diagram) of nanocrystalline Ce(x)Zr(y)Y(z)O(2-delta) in less than 12 h. High resolution PXRD data were obtained for the entire heat-treated library (at 1000 degrees C/1 h) in less than a day using the new robotic beamline I11, located at Diamond Light Source (DLS). This allowed Rietveld-quality powder X-ray diffraction (PXRD) data collection of the entire 66-sample library in <1 day. Consequently, the authors rapidly mapped out phase behavior and sintering behaviors for the entire library. Out of the entire 66-sample heat-treated library, the PXRD data suggests that 43 possess the fluorite structure, of which 30 (out of 36) are ternary compositions. The speed, quantity and quality of data obtained by our new approach, offers an exciting new development which will allow structure-property relationships to be accessed for nanoceramics in much shorter time periods.

Effects of hydrostatic pressure on yeasts isolated from deep-sea hydrothermal vents.

Science.gov (United States)

Burgaud, Gaëtan; Hué, Nguyen Thi Minh; Arzur, Danielle; Coton, Monika; Perrier-Cornet, Jean-Marie; Jebbar, Mohamed; Barbier, Georges

2015-11-01

Hydrostatic pressure plays a significant role in the distribution of life in the biosphere. Knowledge of deep-sea piezotolerant and (hyper)piezophilic bacteria and archaea diversity has been well documented, along with their specific adaptations to cope with high hydrostatic pressure (HHP). Recent investigations of deep-sea microbial community compositions have shown unexpected micro-eukaryotic communities, mainly dominated by fungi. Molecular methods such as next-generation sequencing have been used for SSU rRNA gene sequencing to reveal fungal taxa. Currently, a difficult but fascinating challenge for marine mycologists is to create deep-sea marine fungus culture collections and assess their ability to cope with pressure. Indeed, although there is no universal genetic marker for piezoresistance, physiological analyses provide concrete relevant data for estimating their adaptations and understanding the role of fungal communities in the abyss. The present study investigated morphological and physiological responses of fungi to HHP using a collection of deep-sea yeasts as a model. The aim was to determine whether deep-sea yeasts were able to tolerate different HHP and if they were metabolically active. Here we report an unexpected taxonomic-based dichotomic response to pressure with piezosensitve ascomycetes and piezotolerant basidiomycetes, and distinct morphological switches triggered by pressure for certain strains. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

49 CFR 192.621 - Maximum allowable operating pressure: High-pressure distribution systems.

Science.gov (United States)

2010-10-01

... STANDARDS Operations § 192.621 Maximum allowable operating pressure: High-pressure distribution systems. (a) No person may operate a segment of a high pressure distribution system at a pressure that exceeds the... segment of a distribution system otherwise designed to operate at over 60 p.s.i. (414 kPa) gage, unless...

Learning about hydrothermal volcanic activity by modeling induced geophysical changes

Science.gov (United States)

Currenti, Gilda M.; Napoli, Rosalba

2017-05-01

Motivated by ongoing efforts to understand the nature and the energy potential of geothermal resources, we devise a coupled numerical model (hydrological, thermal, mechanical), which may help in the characterization and monitoring of hydrothermal systems through computational experiments. Hydrothermal areas in volcanic regions arise from a unique combination of geological and hydrological features which regulate the movement of fluids in the vicinity of magmatic sources capable of generating large quantities of steam and hot water. Numerical simulations help in understanding and characterizing rock-fluid interaction processes and the geophysical observations associated with them. Our aim is the quantification of the response of different geophysical observables (i.e. deformation, gravity and magnetic field) to hydrothermal activity on the basis of a sound geological framework (e.g. distribution and pathways of the flows, the presence of fractured zones, caprock). A detailed comprehension and quantification of the evolution and dynamics of the geothermal systems and the definition of their internal state through a geophysical modeling approach are essential to identify the key parameters for which the geothermal system may fulfill the requirements to be exploited as a source of energy. For the sake of illustration only, the numerical computations are focused on a conceptual model of the hydrothermal system of Vulcano Island by simulating a generic 1-year unrest and estimating different geophysical changes. We solved (i) the mass and energy balance equations of flow in porous media for temperature, pressure and density changes, (ii) the elastostatic equation for the deformation field and (iii) the Poisson’s equations for gravity and magnetic potential fields. Under the model assumptions, a generic unrest of 1-year engenders on the ground surface low amplitude changes in the investigated geophysical observables, that are, however, above the accuracies of the modern

Learning about Hydrothermal Volcanic Activity by Modeling Induced Geophysical Changes

Directory of Open Access Journals (Sweden)

Gilda M. Currenti

2017-05-01

Full Text Available Motivated by ongoing efforts to understand the nature and the energy potential of geothermal resources, we devise a coupled numerical model (hydrological, thermal, mechanical, which may help in the characterization and monitoring of hydrothermal systems through computational experiments. Hydrothermal areas in volcanic regions arise from a unique combination of geological and hydrological features which regulate the movement of fluids in the vicinity of magmatic sources capable of generating large quantities of steam and hot water. Numerical simulations help in understanding and characterizing rock-fluid interaction processes and the geophysical observations associated with them. Our aim is the quantification of the response of different geophysical observables (i.e., deformation, gravity, and magnetic fields to hydrothermal activity on the basis of a sound geological framework (e.g., distribution and pathways of the flows, the presence of fractured zones, caprock. A detailed comprehension and quantification of the evolution and dynamics of the geothermal systems and the definition of their internal state through a geophysical modeling approach are essential to identify the key parameters for which the geothermal system may fulfill the requirements to be exploited as a source of energy. For the sake of illustration only, the numerical computations are focused on a conceptual model of the hydrothermal system of Vulcano Island by simulating a generic 1-year unrest and estimating different geophysical changes. We solved (i the mass and energy balance equations of flow in porous media for temperature, pressure and density changes, (ii the elastostatic equation for the deformation field and (iii the Poisson's equations for gravity and magnetic potential fields. Under the model assumptions, a generic unrest of 1-year engenders on the ground surface low amplitude changes in the investigated geophysical observables, that, being above the accuracies of

Thermodynamic analysis of hydrogen production via hydrothermal gasification of hexadecane

KAUST Repository

Alshammari, Yousef M.

2012-04-01

This work reports the equilibrium behaviour of the hydrothermal gasification of hexadecane, a heavy saturate model compound, under non-oxidative isothermal and oxidative adiabatic conditions, using the Peng-Robinson equation of state and the direct minimisation of Gibbs free energy employed within the Aspen HYSYS. This modelling enabled establishing both the limits and optimum conditions at which the hydrogen molar yield may be theoretically maximised. The effects of parameters including the reactor isothermal temperature, pressure, water to carbon ratio, and oxygen to carbon ratio on the molar yields of produced gaseous species were analysed. The model has been validated by comparing its results with different reported modelling and experimental data under identical conditions which resulted in a good agreement. The results reported in this work show the potential of achieving economic yields of hydrogen and syngas from liquid hydrocarbons under downhole hydrothermal conditions. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.

Recrystallization Experiments of Pyrite From Circulating Hydrothermal Solution by Thermal Convection

Science.gov (United States)

Tanaka, K.; Isobe, H.

2005-12-01

Pyrite is one of the most common accessory minerals in many rocks and generally occurs in hydrothermal deposit. However, pyrite morphology and association with other sulfide minerals is not well known with respect to the solution condition, especially with the hydrothermal solution under circulation. In this study, recrystallization experiments of pyrite from circulating hydrothermal solution by thermal convection were carried out. A rectangular circuit (42.6 cm by 17.3 cm) of SUS316 pressure tubing with 5 mm in inner diameter was used as a reaction vessel. The volume of the circuit is approximately 24 ml. Long sides of the rectangular circuit were held to be 20 degrees inclination. One of the long sides was heated by an electric furnace. Solution in the circuit evaporates in the high temperature tubing and the vapor condenses in room temperature tubing. The solution backs to the bottom of the high temperature tubing. Thus, thermal convection of the solution produces circulation in the circuit. Starting material was filled in the high temperature tubing. The lower half was filled with mixture of 2 g of powdered natural pyrite and 4 g of quartz grains. The upper half was filled with quartz grains only. 9 ml of 5 mol/l NH4Cl solution was sealed in the circuit with the starting material. Temperature gradient of the sample was monitored by 6 thermocouples. Maximum temperature was controlled at 350°C. Experimental durations are 3, 5, 10 and 30 days. After the experiments, the run products are fixed with resin and cut every 2 cm. Thin sections of vertical cross-sections are made and observed by microscope and SEM. Tiny pyrite crystals occurred at the upper outside of the furnace, where temperature should be much lower than 200°C. In the lower half of the starting material, pyrite decomposed and pyrrhotite formed around pyrite grains. At higher temperature area, pyrite decomposition and pyrrhotite formation is remarkable. Circulating sulfur-bearing solution provided by

High-Performance Pressure Sensor for Monitoring Mechanical Vibration and Air Pressure

Directory of Open Access Journals (Sweden)

Yancheng Meng

2018-05-01

Full Text Available To realize the practical applications of flexible pressure sensors, the high performance (sensitivity and response time as well as more functionalities are highly desired. In this work, we fabricated a piezoresistive pressure sensor based on the micro-structured composites films of multi-walled carbon nanotubes (MWCNTs and poly (dimethylsiloxane (PDMS. In addition, we establish efficient strategies to improve key performance of our pressure sensor. Its sensitivity is improved up to 474.13 kPa−1 by minimizing pressure independent resistance of sensor, and response time is shorten as small as 2 μs by enhancing the elastic modulus of polymer elastomer. Benefiting from the high performance, the functionalities of sensors are successfully extended to the accurate detection of high frequency mechanical vibration (~300 Hz and large range of air pressure (6–101 kPa, both of which are not achieved before.

Robust Mesoporous CoMo/γ-Al2O3 Catalysts from Cyclodextrin-Based Supramolecular Assemblies for Hydrothermal Processing of Microalgae: Effect of the Preparation Method.

Science.gov (United States)

Bleta, Rudina; Schiavo, Benedetto; Corsaro, Natale; Costa, Paula; Giaconia, Alberto; Interrante, Leonardo; Monflier, Eric; Pipitone, Giuseppe; Ponchel, Anne; Sau, Salvatore; Scialdone, Onofrio; Tilloy, Sébastien; Galia, Alessandro

2018-04-18

Hydrothermal liquefaction (HTL) is a promising technology for the production of biocrude oil from microalgae. Although this catalyst-free technology is efficient under high-temperature and high-pressure conditions, the biocrude yield and quality can be further improved by using heterogeneous catalysts. The design of robust catalysts that preserve their performance under hydrothermal conditions will be therefore very important in the development of biorefinery technologies. In this work, we describe two different synthetic routes (i.e., impregnation and cyclodextrin-assisted one-pot colloidal approach), for the preparation in aqueous phase of six high surface area CoMo/γ-Al 2 O 3 catalysts. Catalytic tests performed on the HTL of Nannochloropsis gaditana microalga indicate that solids prepared by the one-pot colloidal approach show higher hydrothermal stability and enhanced biocrude yield with respect to the catalyst-free test. The positive effect of the substitution of the block copolymer Tetronic T90R4 for Pluronic F127 in the preparation procedure was evidenced by diffuse reflectance UV-visible spectroscopy, X-ray diffraction, N 2 -adsorption-desorption, and H 2 -temperature-programmed reduction measurements and confirmed by the higher quality of the obtained biocrude, which exhibited lower oxygen content and higher-energy recovery equal to 62.5% of the initial biomass.

The interplay of evolved seawater and magmatic-hydrothermal fluids in the 3.24 Ga panorama volcanic-hosted massive sulfide hydrothermal system, North Pilbara Craton, Western Australia

Science.gov (United States)

Drieberg, Susan L.; Hagemann, Steffen G.; Huston, David L.; Landis, Gary; Ryan, Chris G.; Van Achterbergh, Esmé; Vennemann, Torsten

2013-01-01

The ~3240 Ma Panorama volcanic-hosted massive sulfide (VHMS) district is unusual for its high degree of exposure and low degree of postdepositional modification. In addition to typical seafloor VHMS deposits, this district contains greisen- and vein-hosted Mo-Cu-Zn-Sn mineral occurrences that are contemporaneous with VHMS orebodies and are hosted by the Strelley granite complex, which also drove VHMS circulation. Hence the Panorama district is a natural laboratory to investigate the role of magmatic-hydrothermal fluids in VHMS hydrothermal systems. Regional and proximal high-temperature alteration zones in volcanic rocks underlying the VHMS deposits are dominated by chlorite-quartz ± albite assemblages, with lesser low-temperature sericite-quartz ± K-feldspar assemblages. These assemblages are typical of VHMS hydrothermal systems. In contrast, the alteration assemblages associated with granite-hosted greisens and veins include quartz-topaz-muscovite-fluorite and quartz-muscovite (sericite)-chlorite-ankerite. These vein systems generally do not extend into the overlying volcanic pile. Fluid inclusion and stable isotope studies suggest that the greisens were produced by high-temperature (~590°C), high-salinity (38–56 wt % NaCl equiv) fluids with high densities (>1.3 g/cm3) and high δ18O (9.3 ± 0.6‰). These fluids are compatible with the measured characteristics of magmatic fluids evolved from the Strelley granite complex. In contrast, fluids in the volcanic pile (including the VHMS ore-forming fluids) were of lower temperature (90°–270°C), lower salinity (5.0–11.2 wt % NaCl equiv), with lower densities (0.88–1.01 g/cm3) and lower δ18O (−0.8 ± 2.6‰). These fluids are compatible with evolved Paleoarchean seawater. Fluids that formed the quartz-chalcopyrite-sphalerite-cassiterite veins, which are present within the granite complex near the contact with the volcanic pile, were intermediate in temperature and isotopic composition between the greisen

Terbium oxide at high pressures

International Nuclear Information System (INIS)

Dogra, Sugandha; Sharma, Nita Dilawar; Singh, Jasveer; Bandhyopadhyay, A.K.

2011-01-01

In this work we report the behaviour of terbium oxide at high pressures. The as received sample was characterized at ambient by X-ray diffraction and Raman spectroscopy. The X-ray diffraction showed the sample to be predominantly cubic Tb 4 O 7 , although a few peaks also match closely with Tb 2 O 3 . In fact in a recent study done on the same sample, the sample has been shown to be a mixture of Tb 4 O 7 and Tb 2 O 3 . The sample was subjected to high pressures using a Mao-Bell type diamond anvil cell upto a pressure of about 42 GPa with ruby as pressure monitor

High-pressure phase transitions of strontianite

Science.gov (United States)

Speziale, S.; Biedermann, N.; Reichmann, H. J.; Koch-Mueller, M.; Heide, G.

2015-12-01

Strontianite (SrCO3) is isostructural to aragonite, a major high-pressure polymorph of calcite. Thus it is a material of interest to investigate the high-pressure phase behavior of aragonite-group minerals. SrCO3 is a common component of natural carbonates and knowing its physical properties at high pressures is necessary to properly model the thermodynamic properties of complex carbonates, which are major crustal minerals but are also present in the deep Earth [Brenker et al., 2007] and control carbon cycling in the Earth's mantle. The few available high-pressure studies of SrCO3 disagree regarding both pressure stability and structure of the post-aragonite phase [Lin & Liu, 1997; Ono et al., 2005; Wang et al. 2015]. To clarify such controversies we investigated the high-pressure behavior of synthetic SrCO3 by Raman spectroscopy. Using a diamond anvil cell we compressed single-crystals or powder of strontianite (synthesized at 4 GPa and 1273 K for 24h in a multi anvil apparatus), and measured Raman scattering up to 78 GPa. SrCO3 presents a complex high-pressure behavior. We observe mode softening above 20 GPa and a phase transition at 25 - 26.9 GPa, which we interpret due to the CO3 groups rotation, in agreement with Lin & Liu [1997]. The lattice modes in the high-pressure phase show dramatic changes which may indicate a change from 9-fold coordinated Sr to a 12-fold-coordination [Ono, 2007]. Our results confirm that the high-pressure phase of strontianite is compatible with Pmmn symmetry. References Brenker, F.E. et al. (2007) Earth and Planet. Sci. Lett., 260, 1; Lin, C.-C. & Liu, L.-G. (1997) J. Phys. Chem. Solids, 58, 977; Ono, S. et al. (2005) Phys. Chem. Minerals, 32, 8; Ono, S. (2007) Phys. Chem. Minerals, 34, 215; Wang, M. et al. (2015) Phys Chem Minerals 42, 517.

Thallium isotope variations in seawater and hydrogenetic, diagenetic, and hydrothermal ferromanganese deposits

Science.gov (United States)

Rehkamper, M.; Frank, M.; Hein, J.R.; Porcelli, D.; Halliday, A.; Ingri, J.; Liebetrau, V.

2002-01-01

Results are presented for the first in-depth investigation of TI isotope variations in marine materials. The TI isotopic measurements were conducted by multiple collector-inductively coupled plasma mass spectrometry for a comprehensive suite of hydrogenetic ferromanganese crusts, diagenetic Fe-Mn nodules, hydrothermal manganese deposits and seawater samples. The natural variability of TI isotope compositions in these samples exceeds the analytical reproducibility (?? 0.05???) by more than a factor of 40. Hydrogenetic Fe-Mn crusts have ??205TI of + 10 to + 14, whereas seawater is characterized by values as low as -8 (??205TI represents the deviation of the 205TI/203TI ratio of a sample from the NIST SRM 997 TI isotope standard in parts per 104). This ~ 2??? difference in isotope composition is thought to result from the isotope fractionation that accompanies the adsorption of TI onto ferromanganese particles. An equilibrium fractionation factor of ?? ~ 1.0021 is calculated for this process. Ferromanganese nodules and hydrothermal manganese deposits have variable TI isotope compositions that range between the values obtained for seawater and hydrogenetic Fe-Mn crusts. The variability in ??205TI in diagenetic nodules appears to be caused by the adsorption of TI from pore fluids, which act as a closed-system reservoir with a TI isotope composition that is inferred to be similar to seawater. Nodules with ??205TI values similar to seawater are found if the scavenging of TI is nearly quantitative. Hydrothermal manganese deposits display a positive correlation between ??205TI and Mn/Fe. This trend is thought to be due to the derivation of TI from distinct hydrothermal sources. Deposits with low Mn/Fe ratios and low ??205TI are produced by the adsorption of TI from fluids that are sampled close to hydrothermal sources. Such fluids have low Mn/Fe ratios and relatively high temperatures, such that only minor isotope fractionation occurs during adsorption. Hydrothermal

High-Pressure Polymorphism in Orthoamphiboles

Science.gov (United States)

Finkelstein, G. J.; Zhang, D.; Shelton, H.; Dera, P.

2017-12-01

Amphiboles are double-chain silicate minerals that are the structurally hydrated counterpart to single-chain, anhydrous pyroxenes. They may play an important role in the earth as a carrier for volatiles in subduction zones, as well as a generator for seismic anisotropy in the upper mantle. Recent work has described previously unrecognized high-pressure polymorphism at low temperatures in a variety of pyroxene minerals, which may be relevant for the structure and dynamics of thick, cold, subducted slabs. However, high-pressure polymorphism in amphiboles above a few GPa in pressure has not been well explored, and if similar polymorphism to pyroxenes exists in this mineral family, it may affect the extent and depth of volatile transport in amphiboles, as well as their rheological properties. At low temperatures and high pressures, orthopyroxenes undergo crystal structure transitions at lower pressures than clinopyroxenes (10-30 GPa vs. > 50 GPa), so for this study we have investigated polymorphism in the anthophyllite-gedrite (Al-free and Al rich) orthoamphibole solid solution series. Using neon gas-loaded diamond anvil cells, we compressed both phases to a maximum pressure of 31 GPa, and observed transitions to new monoclinic structures in both endmembers. In this presentation, we will discuss the details of these transitions and implications for the earth's interior.

Application and possible benefits of high hydrostatic pressure or high-pressure homogenization on beer processing: A review.

Science.gov (United States)

Santos, Lígia Mr; Oliveira, Fabiano A; Ferreira, Elisa Hr; Rosenthal, Amauri

2017-10-01

Beer is the most consumed beverage in the world, especially in countries such as USA, China and Brazil.It is an alcoholic beverage made from malted cereals, and the barley malt is the main ingredient, added with water, hops and yeast. High-pressure processing is a non-traditional method to preserve food and beverages. This technology has become more interesting compared to heat pasteurization, due to the minimal changes it brings to the original nutritional and sensory characteristics of the product, and it comprises two processes: high hydrostatic pressure, which is the most industrially used process, and high-pressure homogenization. The use of high pressure almost does not affect the molecules that are responsible for the aroma and taste, pigments and vitamins compared to the conventional thermal processes. Thus, the products processed by high-pressure processing have similar characteristics compared to fresh products, including beer. The aim of this paper was to review what has been investigated about beer processing using this technology regarding the effects on physicochemical, microbiology and sensory characteristics and related issues. It is organized by processing steps, since high pressure can be applied to malting, mashing, boiling, filtration and pasteurization. Therefore, the beer processed with high-pressure processing may have an extended shelf-life because this process can inactivate beer spoilage microorganisms and result in a superior sensory quality related to freshness and preservation of flavors as it does to juices that are already commercialized. However, beyond this application, high-pressure processing can modify protein structures, such as enzymes that are present in the malt, like α- and β-amylases. This process can activate enzymes to promote, for example, saccharification, or instead inactivate at the end of mashing, depending on the pressure the product is submitted, besides being capable of isomerizing hops to raise beer bitterness

Pressure-temperature condition and hydrothermal-magmatic fluid evolution of the Cu-Mo Senj deposit, Central Alborz: fluid inclusion evidence

Directory of Open Access Journals (Sweden)

Ebrahim Tale Fazel

2017-02-01

Full Text Available Introduction The Senj deposit has significant potential for different types of mineralization, particularly porphyry-like Cu deposits, associated with subduction-related Eocene–Oligocene calc-alkaline porphyritic volcano-plutonic rocks. The study of fluid inclusions in hydrothermal ore deposits aims to identify and characterize the pressure, temperature, volume and fluid composition, (PTX conditions of fluids under which they were trapped (Heinrich et al., 1999; Ulrich and Heinrich, 2001; Redmond et al., 2004. Different characteristics of the deposit such as porphyrtic nature, alteration assemblage and the quartz-sulfide veins of the stockwork were poorly known. In this approach on the basis of alterations, vein cutting relationship and field distribution of fluid inclusions, the physical and chemical evolution of the hydrothermal system forming the porphyry Cu-Mo (±Au-Ag deposit in Senj is reconstructed. Materials and Methods Over 1000 m of drill core was logged at a scale of 1:1000 by Pichab Kavosh Co. and samples containing various vein and alteration types from different depths were collected for laboratory analyses. A total of 14 samples collected from the altered and least altered igneous rocks in the Senj deposit were analyzed for their major oxide concentrations by X-ray fluorescence in the SGS Mineral Services (Toronto, Canada. The detection limit for major oxide analysis is 0.01%. Trace and rare earth elements (REE were analyzed using inductively coupled plasma-mass spectrometery (ICP-MS, in the commercial laboratory of SGS Mineral Services. The analytical error for most elements is less than 2%. The detection limit for trace elements and REEs analysis is 0.01 to 0.1 ppm. Fluid inclusion microthermometry was conducted using a Linkam THMS600 heating–freezing stage (-190 °C to +600 °C mounted on a ZEISS Axioplan2 microscope in the fluid inclusion laboratory of the Iranian Mineral Processing Research Center (Karaj, Iran. Results

High Blood Pressure: Medicines to Help You

Science.gov (United States)

... For Consumers Consumer Information by Audience For Women High Blood Pressure--Medicines to Help You Share Tweet Linkedin Pin ... Click here for the Color Version (PDF 533KB) High blood pressure is a serious illness. High blood pressure is ...

High-pressure oxidation of methane

DEFF Research Database (Denmark)

Hashemi, Hamid; Christensen, Jakob Munkholt; Gersen, Sander

2016-01-01

Methane oxidation at high pressures and intermediate temperatures was investigated in a laminar flow reactor and in a rapid compression machine (RCM). The flow-reactor experiments were conducted at 700–900 K and 100 bar for fuel-air equivalence ratios (Φ) ranging from 0.06 to 19.7, all highly...... diluted in nitrogen. It was found that under the investigated conditions, the onset temperature for methane oxidation ranged from 723 K under reducing conditions to 750 K under stoichiometric and oxidizing conditions. The RCM experiments were carried out at pressures of 15–80 bar and temperatures of 800......–1250 K under stoichiometric and fuel-lean (Φ=0.5) conditions. Ignition delays, in the range of 1–100 ms, decreased monotonically with increasing pressure and temperature. A chemical kinetic model for high-pressure methane oxidation was established, with particular emphasis on the peroxide chemistry...

Biodiversity patterns, environmental drivers and indicator species on a High-temperature Hydrothermal edifice, mid-Atlantic ridge

KAUST Repository

Sarrazin, Jozée

2015-04-25

Knowledge on quantitative faunal distribution patterns of hydrothermal communities in slow-spreading vent fields is particularly scarce, despite the importance of these ridges in the global mid-ocean system. This study assessed the composition, abundance and diversity of 12 benthic faunal assemblages from various locations on the Eiffel Tower edifice (Lucky Strike vent field, Mid-Atlantic Ridge) and investigated the role of key environmental conditions (temperature, total dissolved iron (TdFe), sulfide (TdS), copper (TdCu) and pH) on the distribution of macro- and meiofaunal species at small spatial scales (< 1 m). There were differences in macro- and meiofaunal community structure between the different sampling locations, separating the hydrothermal community of the Eiffel Tower edifice into three types of microhabitats: (1) cold microhabitats characterized by low temperatures (<6 °C), high TdCu (up to 2.4±1.37 µmol l−1), high pH (up to 7.34±0.13) but low TdS concentrations (<6.98±5.01 µmol l−1); (2) warm microhabitats characterized by warmer temperatures (>6 °C), low pH (<6.5) and high TdS/TdFe concentrations (>12.8 µmol l−1/>1.1 µmol l−1 respectively); and (3) a third microhabitat characterized by intermediate abiotic conditions. Environmental conditions showed more variation in the warm microhabitats than in the cold microhabitats. In terms of fauna, the warm microhabitats had lower macro- and meiofaunal densities, and lower richness and Shannon diversity than the cold microhabitats. Six macrofaunal species (Branchipolynoe seepensis, Amathys lutzi, Bathymodiolus azoricus, Lepetodrilus fucensis, Protolira valvatoides and Chorocaris chacei) and three meiofaunal taxa (Paracanthonchus, Cephalochaetosoma and Microlaimus) were identified as being significant indicator species/taxa of particular microhabitats. Our results also highlight very specific niche separation for copepod juveniles among the different hydrothermal microhabitats. Some sampling

Hydrothermal pretreatments of macroalgal biomass for biorefineries

DEFF Research Database (Denmark)

Ruiz, Héctor A.; Rodríguez-Jasso, Rosa M.; Aguedo, Mario

2015-01-01

in accordance with the integrated biorefineries. Furthermore, biorefinery concept requires processes that allow efficient utilization of all components of the biomass. The pretreatment step in a biorefinery is often based on hydrothermal principles of high temperatures in aqueous solution. Therefore...

Exploratory benefit-cost analysis of environmental controls on hydrothermal energy

Energy Technology Data Exchange (ETDEWEB)

Scott, M.J.; Wells, K.D.; Currie, J.W.; King, M.J.

1981-02-01

A study of the value of environmental benefits generated by environmental regulation of hydrothermal sites was initiated to compare these benefits with the estimated costs of regulation. Primary objectives were to 1) evaluate the environmental damages caused by unregulated hydrothermal resource development, 2) use existing environmental and economic data to estimate the dollar value of preventing expected environmental damages at two sites, and 3) compare the benefits and costs of preventing the damages. The sites chosen for analyses were in the Imperial Valley at Heber and Niland, California. Reasons for this choice were 1) there is a high level of commercial interest in developing the Heber known geothermal resource area (KGRA) and the Salton Sea KGRA; 2) the potential for environmental damage is high; 3) existing data bases for these two sites are more comprehensive than at other sites. The primary impacts analyzed were those related to hydrogen sulfide (H/sub 2/S) emissions and those related to disposal of spent hydrothermal brine. (MHR)

A thermoelectric cap for seafloor hydrothermal vents

International Nuclear Information System (INIS)

Xie, Yu; Wu, Shi-jun; Yang, Can-jun

2016-01-01

Highlights: • We developed a thermoelectric cap (TC) to harvest hydrothermal energy. • The TC was deployed at a hydrothermal vent site near Kueishantao islet, Taiwan. • The TC monitored the temperature of the hydrothermal fluids during the field test. • The TC could make the thermal energy of hydrothermal fluids a viable power source. - Abstract: Long-term in situ monitoring is crucial to seafloor scientific investigations. One of the challenges of operating sensors in seabed is the lifespan of the sensors. Such sensors are commonly powered by batteries when other alternatives, such as tidal or solar energy, are unavailable. However, the batteries have a limited lifespan and must be recharged or replaced periodically, which is costly and impractical. A thermoelectric cap, which harvests the thermal energy of hydrothermal fluids through a conduction pipe and converts the heat to electrical energy by using thermoelectric generators, was developed to avoid these inconveniences. The thermoelectric cap was combined with a power and temperature measurement system that enables the thermoelectric cap to power a light-emitting diode lamp, an electronic load (60 Ω), and 16 thermocouples continuously. The thermoelectric cap was field tested at a shallow hydrothermal vent site near Kueishantao islet, which is located offshore of northeastern Taiwan. By using the thermal gradient between hydrothermal fluids and seawater, the thermoelectric cap obtained a sustained power of 0.2–0.5 W during the field test. The thermoelectric cap successfully powered the 16 thermocouples and recorded the temperature of the hydrothermal fluids during the entire field test. Our results show that the thermal energy of hydrothermal fluids can be an alternative renewable power source for oceanographic research.

Hydrothermal Synthesis of Analcime from Kutingkeng Formation Mudstone

Science.gov (United States)

Hsiao, Yin-Hsiu; Chen, Kuan-Ting; Ray, Dah-Tong

2015-04-01

In southwest of Taiwan, the foothill located in Tainan-Kaohsiung city is the exposed area of Pliocene strata to early Pleistocene strata. The strata are about a depth of five thousand, named as Kutigkeng Formation. The outcrop of Kutigkeng Formation is typical badlands, specifically called 'Moon World.' It is commonly known as no important economic applications of agricultural land. The mineral compositions of Kutingkeng Formation are quartz, clay minerals and feldspar. The clay minerals consist of illite, clinochlore and swelling clays. To study how the phase and morphology of analcime formed by hydrothermal synthesis were affected, analcime was synthesized from the mudstone of Kutinkeng Formation with microwave hydrothermal reaction was investigated. The parameters of the experiment were the reaction temperature, the concentration of mineralizer, solids/liquid ratio and time. The sodium silicate (Na2SiO3) were used as mineralizer. The results showed that the analcime could be synthesized by hydrothermal reaction above 180° from Kutinkeng Formation mudstone samples. At the highest temperature (240°) of this study, the high purity analcime could be produced. When the concentration of Na2SiO3=3~6M, analcime could be synthesized at 240°. The best solids/liquid ratio was approximate 1 to 5. The hydrothermal reaction almost was completed after 4 hours.

Advances in high pressure science and technology: proceedings of the fourth national conference on high pressure science and technology

International Nuclear Information System (INIS)

Yousuf, Mohammad; Subramanian, N.; Govinda Rajan, K.

1997-09-01

The proceedings of the fourth National Conference on High Pressure Science and Technology covers a wide area of research and development activities in the field of high pressure science and technology, broadly classified into the following themes: mechanical behaviour of materials; instrumentation and methods in high pressure research; pressure calibration, standards and safety aspects; phase transitions; shock induced reactions; mineral science, geophysics, geochemistry and planetary sciences; optical, electronic and transport properties; synthesis of materials; soft condensed matter physics and liquid crystals; computational methods in high pressure research. Papers relevant to INIS are indexed separately

Surface-discharging hydrothermal systems at Yucca Mountain: Examining the evidence

International Nuclear Information System (INIS)

Levy, S.S.

1992-01-01

This paper discusses exposures of altered rock that have been thought to form by recent discharge of water from depth. They were examined to address a concern that hydrothermal processes could compromise the isolation capability of a potential high-level nuclear waste repository at Yucca Mountain. Suspected hot-spring and hydrothermal-vent deposits are more likely the products of infiltration of meteoric water into newly deposited and still-hot pyroclastic flows >12 Myr ago

Geologic evolution of the Lost City Hydrothermal Field

Science.gov (United States)

Denny, Alden R.; Kelley, Deborah S.; Früh-Green, Gretchen L.

2016-02-01

The Lost City Hydrothermal Field (LCHF) is a novel serpentinite-hosted vent field located on the Atlantis Massif southern wall. Results of 2 m resolution bathymetry, side scan, and video and still imagery, integrated with direct submersible observations provide the first high-resolution geologic map of the LCHF. These data form the foundation for an evolutionary model for the vent system over the past >120,000 years. The field is located on a down-dropped bench 70 m below the summit of the massif. The bench is capped by breccia and pelagic carbonate deposits underlain by variably deformed and altered serpentinite and gabbroic rocks. Hydrothermal activity is focused at the 60 m tall, 100 m across, massive carbonate edifice "Poseidon," which is venting 91°C fluid. Hydrothermal activity declines south and west of the Poseidon complex and dies off completely at distances greater than 200 m. East of Poseidon, the most recent stage of hydrothermal flow is characterized by egress of diffuse fluids from narrow fissures within a low-angle, anastomosing mylonite zone. South of the area of current hydrothermal activity, there is evidence of two discrete previously unrecognized relict fields. Active venting sites defined by carbonate-filled fissures that cut the carbonate cap rock at the summit of the massif mark the present-day northernmost extent of venting. These spatial relationships reflect multiple stages of field development, the northward migration of venting over time, and the likely development of a nascent field at the massif summit.

Hydraulic High Pressure Valve Controller Using the In-Situ Pressure Difference

Science.gov (United States)

Bao, Xiaoqi (Inventor); Sherrit, Stewart (Inventor); Badescu, Mircea (Inventor); Bar-Cohen, Yoseph (Inventor); Hall, Jeffery L. (Inventor)

2016-01-01

A hydraulic valve controller that uses an existing pressure differential as some or all of the power source for valve operation. In a high pressure environment, such as downhole in an oil or gas well, the pressure differential between the inside of a pipe and the outside of the pipe may be adequately large to drive a linear slide valve. The valve is operated hydraulically by a piston in a bore. When a higher pressure is applied to one end of the bore and a lower pressure to the other end, the piston moves in response to the pressure differential and drives a valve attached to it. If the pressure differential is too small to drive the piston at a sufficiently high speed, a pump is provided to generate a larger pressure differential to be applied. The apparatus is conveniently constructed using multiport valves, which can be rotary valves.

Application of High Pressure in Food Processing

Directory of Open Access Journals (Sweden)

Herceg, Z.

2011-01-01

Full Text Available In high pressure processing, foods are subjected to pressures generally in the range of 100 – 800 (1200 MPa. The processing temperature during pressure treatments can be adjusted from below 0 °C to above 100 °C, with exposure times ranging from a few seconds to 20 minutes and even longer, depending on process conditions. The effects of high pressure are system volume reduction and acceleration of reactions that lead to volume reduction. The main areas of interest regarding high-pressure processing of food include: inactivation of microorganisms, modification of biopolymers, quality retention (especially in terms of flavour and colour, and changes in product functionality. Food components responsible for the nutritive value and sensory properties of food remain unaffected by high pressure. Based on the theoretical background of high-pressure processing and taking into account its advantages and limitations, this paper aims to show its possible application in food processing. The paper gives an outline of the special equipment used in highpressure processing. Typical high pressure equipment in which pressure can be generated either by direct or indirect compression are presented together with three major types of high pressure food processing: the conventional (batch system, semicontinuous and continuous systems. In addition to looking at this technology’s ability to inactivate microorganisms at room temperature, which makes it the ultimate alternative to thermal treatments, this paper also explores its application in dairy, meat, fruit and vegetable processing. Here presented are the effects of high-pressure treatment in milk and dairy processing on the inactivation of microorganisms and the modification of milk protein, which has a major impact on rennet coagulation and curd formation properties of treated milk. The possible application of this treatment in controlling cheese manufacture, ripening and safety is discussed. The opportunities

Hydrothermal impacts on trace element and isotope ocean biogeochemistry.

Science.gov (United States)

German, C R; Casciotti, K A; Dutay, J-C; Heimbürger, L E; Jenkins, W J; Measures, C I; Mills, R A; Obata, H; Schlitzer, R; Tagliabue, A; Turner, D R; Whitby, H

2016-11-28

Hydrothermal activity occurs in all ocean basins, releasing high concentrations of key trace elements and isotopes (TEIs) into the oceans. Importantly, the calculated rate of entrainment of the entire ocean volume through turbulently mixing buoyant hydrothermal plumes is so vigorous as to be comparable to that of deep-ocean thermohaline circulation. Consequently, biogeochemical processes active within deep-ocean hydrothermal plumes have long been known to have the potential to impact global-scale biogeochemical cycles. More recently, new results from GEOTRACES have revealed that plumes rich in dissolved Fe, an important micronutrient that is limiting to productivity in some areas, are widespread above mid-ocean ridges and extend out into the deep-ocean interior. While Fe is only one element among the full suite of TEIs of interest to GEOTRACES, these preliminary results are important because they illustrate how inputs from seafloor venting might impact the global biogeochemical budgets of many other TEIs. To determine the global impact of seafloor venting, however, requires two key questions to be addressed: (i) What processes are active close to vent sites that regulate the initial high-temperature hydrothermal fluxes for the full suite of TEIs that are dispersed through non-buoyant hydrothermal plumes? (ii) How do those processes vary, globally, in response to changing geologic settings at the seafloor and/or the geochemistry of the overlying ocean water? In this paper, we review key findings from recent work in this realm, highlight a series of key hypotheses arising from that research and propose a series of new GEOTRACES modelling, section and process studies that could be implemented, nationally and internationally, to address these issues.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'. © 2015 The Authors.

Homogenization Experiments of Crystal-Rich Inclusions in Spodumene from Jiajika Lithium Deposit, China, under Elevated External Pressures in a Hydrothermal Diamond-Anvil Cell

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Jiankang Li

2017-01-01

Full Text Available Extensive studies of the crystal-rich inclusions (CIs hosted in minerals in pegmatite have resulted in substantially different models for the formation mechanism of the pegmatite. In order to evaluate these previously proposed formation mechanisms, the total homogenization processes of CIs hosted in spodumene from the Jiajika pegmatite deposit in Sichuan, China, were observed in situ under external H2O pressures in a new type of hydrothermal diamond-anvil cell (HDAC. The CIs in a spodumene chip were loaded in the sample chamber of HDAC with water, such that the CIs were under preset external H2O pressures during heating to avoid possible decrepitation. Our in situ observations showed that the crystals within the CIs were dissolved in carbonic-rich aqueous fluid during heating and that cristobalite was usually the first mineral being dissolved, followed by zabuyelite and silicate minerals until their total dissolution at temperatures between 500 and 720°C. These observations indicated that the minerals within the CIs were daughter minerals crystallized from an entrapped carbonate- and silica-rich aqueous solution and therefore provided useful information for evaluating the formation models of granitic pegmatites.

The Guaymas Basin hiking guide to hydrothermal mounds, chimneys and microbial mats: complex seafloor expressions of subsurface hydrothermal circulation

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Andreas eTeske

2016-02-01

Full Text Available The hydrothermal mats, mounds and chimneys of the southern Guaymas Basin are the surface expression of complex subsurface hydrothermal circulation patterns. In this overview we document the most frequently visited features of this hydrothermal area with photographs, temperature measurements, and selected geochemical data; many of these distinct habitats await characterization of their microbial communities and activities. Microprofiler deployments on microbial mats and hydrothermal sediments show their steep geochemical and thermal gradients at millimeter-scale vertical resolution. Mapping these hydrothermal features and sampling locations within the southern Guaymas Basin suggest linkages to underlying shallow sills and heatflow gradients. Recognizing the inherent spatial limitations of much current Guaymas Basin sampling calls for a wider survey of the entire spreading region.

Gram-scale synthesis of highly crystalline, 0-D and 1-D SnO2 nanostructures through surfactant-free hydrothermal process

International Nuclear Information System (INIS)

Pal, Umapada; Pal, Mou; Sánchez Zeferino, Raul

2012-01-01

We report the synthesis of highly crystalline SnO 2 nanoparticle and nanorod structures with average diameters well within quantum confinement limit (3.5−6.4 nm), through surfactant-free hydrothermal synthesis. The size and shape of the nanostructures could be controlled by controlling the pH (4.5–13.0) of the reaction mixture and the temperature of hydrothermal treatment. Probable mechanisms for the variation of particle size and growth of one-dimensional structures are presented considering the size-dependent crystal solubility at lower pH values of the reaction solution and Ostwald ripening of the quasi-spherical nanoparticles at higher pH values, respectively. Variation of optical band gap energy and hence the effects of quantum confinement in the nanostructures have been studied.

Synthesis and characterization of nanosized MnZn ferrites via a modified hydrothermal method

Science.gov (United States)

Li, Mingling; Liu, Xiansong; Xu, Taotao; Nie, Yu; Li, Honglin; Zhang, Cong

2017-10-01

Nanosized MnZn ferrite particles, with narrow size distribution, regular morphology and high saturation magnetization have been synthesized via a modified hydrothermal method. This modified hydrothermal method involves a chemical co-precipitation of hydroxides under a vacuum condition using potassium hydroxide as precipitating agent, followed by a separate hydrothermal process. The microstructure and magnetic properties of the synthesized nanoparticles were investigated by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). The effects of different synthesis conditions (excess ratio of precipitating agent and hydrothermal reaction time) on the microstructure and magnetic properties of the as-synthesized nanoparticles were discussed. The magnetic measurements indicated that the obtained samples were superparamagnetic in nature at room temperature. Moreover, the MnZn ferrite nanoparticles with excellent magnetic performance could be synthesized at 180 °C for a short reaction time (3 h).

Ultrasonic and hydrothermal mediated synthesis routes for functionalized Mg-Al LDH: Comparison study on surface morphology, basic site strength, cyclic sorption efficiency and effectiveness.

Science.gov (United States)

Ezeh, Collins I; Tomatis, Marco; Yang, Xiaogang; He, Jun; Sun, Chenggong

2018-01-01

Amine functionalized layered double hydroxide (LDHs) adsorbents prepared using three different routes: co-precipitation, sono-chemical and ultrasonic-assisted high pressure hydrothermal. The prepared adsorbent samples were characterized using X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning electron microscope-Energy dispersive X-ray spectroscopy (SEM-EDX), Temperature Programmed Desorption (TPD), Brunauer-Emmett-Teller (BET), and Thermogravimetric analysis (TGA), respectively. The performance of the prepared adsorbents was tested in a controlled thermal-swing adsorption process to measure its adsorption capacity, regeneration and cyclic efficiencies subsequently. The characterisation results were compared with those obtained using the conventional preparation routes but taking into account of the impact of sonochemical and hydrothermal pre-treatment on textural properties, adsorption capacity, regeneration and cyclic efficiencies. Textural results depicts a surge in surface area of the adsorbent synthesised by hydrothermal route (311m 2 /g) from 25 to 171m 2 /g for conventional and ultrasonic routes respectively. Additionally, it has been revealed from the present study that adsorbents prepared using ultrasonic-assisted hydrothermal route exhibit a better CO 2 uptake capacity than that prepared using sonochemical and conventional routes. Thus, the ultrasonic-assisted hydrothermal treatment can effectively promote the adsorption capacity of the adsorbent. This is probably due to the decrease of moderate (M-O) and weak (OH - groups) basic sites with subsequent surge in the number of strong basic sites (O 2- ) resulting from the hydrothermal process. Moreover, the cyclic adsorption efficiency of the ultrasonic mediated process was found to be 76% compared with 60% for conventional and 53% for hydrothermal routes, respectively. According to the kinetic model analysis, adsorption mechanism is mostly dominated by physisorption before amine

High Blood Pressure

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... factors Diabetes High blood pressure Family history Obesity Race/ethnicity Full list of causes and risk factors ... give Give monthly Memorials and tributes Donate a car Donate gently used items Stock donation Workplace giving ...

High Blood Pressure

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... kidney disease, diabetes, or metabolic syndrome Read less Unhealthy lifestyle habits Unhealthy lifestyle habits can increase the risk of high blood pressure. These habits include: Unhealthy eating patterns, such as eating too much sodium ...

Role of triton X-100 and hydrothermal treatment on the morphological features of nanoporous hydroxyapatite nanorods

International Nuclear Information System (INIS)

Iyyappan, E.; Wilson, P.; Sheela, K.; Ramya, R.

2016-01-01

Hydroxyapatite (HA) particles were synthesized using Ca(NO 3 ) 2 ·4H 2 O and (NH 4 ) 2 HPO 4 as precursors with varying contents of non-ionic surfactant viz., triton X-100 (organic modifier) via co-precipitation method followed by hydrothermal treatment. The prepared HA particles have been characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Energy Dispersive X-ray Analysis (EDX), High Resolution Scanning Electron Microscopy (HRSEM), High Resolution Transmission Electron Microscopy (HRTEM) and Nitrogen adsorption–desorption experiments. The XRD and FTIR studies indicate the formation of HA phase in all the synthesized samples. The specific roles of triton X-100 and hydrothermal treatment in dispersing and in directing the crystal growth respectively have been discussed by comparing the observations from individual experiments using triton X-100 and hydrothermal treatment with that of combined protocol involving both. The plausible mechanism for the individual roles of both triton X-100 and hydrothermal treatment have been proposed. - Highlights: • Nanoporous HA nanorods are synthesized via triton X-100 assisted hydrothermal treatment. • Triton X-100 hinder the agglomeration of HA primary particles • Hydrothermal treatment increase the aspect ratio of the HA particles • Oriented attachment of HA particles occurs under hydrothermal treatment facilitated by triton X-100 stabilized HA collides • The percentage of mesopore volume is higher for hydrothermally treated samples

Synthesis of zinc aluminate with high surface area by microwave hydrothermal method applied in the transesterification of soybean oil (biodiesel)

International Nuclear Information System (INIS)

Quirino, M.R.; Oliveira, M.J.C.; Keyson, D.; Lucena, G.L.; Oliveira, J.B.L.; Gama, L.

2016-01-01

Highlights: • ZnAl_2O_4 spinel was synthesized by the microwave hydrothermal method in only 15 or 30 min. • The powders show high specific surface area. • ZAT_b15 showed activity of 52.22% for the conversion of soybean oil into biodiesel. - Abstract: Zinc aluminate is a material with high thermal stability and high mechanical strength that, owing to these properties, is used as a catalyst or support. In this work, zinc aluminate spinel was synthesized by the microwave hydrothermal method in only 15 or 30 min at a low temperature (150 °C) without templates, using only Al(NO_3)_3·9H_2O, Zn(NO_3)_2·6H_2O, and urea as precursors and applied in the transesterification of soybean oil. X-ray diffraction analysis showed that ZnAl_2O_4 had a cubic structure without secondary phases. The nitrogen adsorption measurements (BET) revealed a high surface area (266.57 m"2 g"−"1) for the nanopowder synthesized in 15 min. This powder showed activity of 52.22% for the catalytic conversion of soybean oil into biodiesel by transesterification.

Inactivation of Escherichia coli Endotoxin by Soft Hydrothermal Processing▿

Science.gov (United States)

Miyamoto, Toru; Okano, Shinya; Kasai, Noriyuki

2009-01-01

Bacterial endotoxins, also known as lipopolysaccharides, are a fever-producing by-product of gram-negative bacteria commonly known as pyrogens. It is essential to remove endotoxins from parenteral preparations since they have multiple injurious biological activities. Because of their strong heat resistance (e.g., requiring dry-heat sterilization at 250°C for 30 min) and the formation of various supramolecular aggregates, depyrogenation is more difficult than sterilization. We report here that soft hydrothermal processing, which has many advantages in safety and cost efficiency, is sufficient to assure complete depyrogenation by the inactivation of endotoxins. The endotoxin concentration in a sample was measured by using a chromogenic limulus method with an endotoxin-specific limulus reagent. The endotoxin concentration was calculated from a standard curve obtained using a serial dilution of a standard solution. We show that endotoxins were completely inactivated by soft hydrothermal processing at 130°C for 60 min or at 140°C for 30 min in the presence of a high steam saturation ratio or with a flow system. Moreover, it is easy to remove endotoxins from water by soft hydrothermal processing similarly at 130°C for 60 min or at 140°C for 30 min, without any requirement for ultrafiltration, nonselective adsorption with a hydrophobic adsorbent, or an anion exchanger. These findings indicate that soft hydrothermal processing, applied in the presence of a high steam saturation ratio or with a flow system, can inactivate endotoxins and may be useful for the depyrogenation of parenterals, including end products and medical devices that cannot be exposed to the high temperatures of dry heat treatments. PMID:19502435

High-pressure system for Compton scattering experiments

International Nuclear Information System (INIS)

Oomi, G.; Honda, F.; Kagayama, T.; Itoh, F.; Sakurai, H.; Kawata, H.; Shimomura, O.

1998-01-01

High-pressure apparatus for Compton scattering experiments has been developed to study the momentum distribution of conduction electrons in metals and alloys at high pressure. This apparatus was applied to observe the Compton profile of metallic Li under pressure. It was found that the Compton profile at high pressure could be obtained within several hours by using this apparatus and synchrotron radiation. The result on the pressure dependence of the Fermi momentum of Li obtained here is in good agreement with that predicted from the free-electron model

Hydrothermal uranium vein deposits in Marysvale volcanic field, Utah

International Nuclear Information System (INIS)

Rasmussen, J.D.; Cunningham, C.G.; Steven, T.A.; Rye, R.O.; Romberger, S.B.

1984-01-01

Hydrothermal uranium veins are exposed over a 300 m (980 ft) vertical range in mines of the Central Mining area, near Marysvale, Utah. They cut 23 Ma quartz monzonite, 21 Ma granite, and 19 Ma rhyolite ash-flow tuff. The veins formed 18-19 Ma, in an area 1 km (0.6 mi) across, above the center of a composite magma chamber at least 12 x 6 km across that fed a sequence of 21-14 Ma hypabyssal granitic stocks, and rhyolitic lava flows, ash-flow tuffs, and volcanic domes. Intrusive pressure uplifted and fractured the roof; molybdenite-bearing, uranium-rich glassy dikes were intruded; and a breccia pipe and uranium-bearing veins were formed. The veins appear to have been deposited near the surface above a concealed rhyolite stock, where they filled high-angle fault zones and flat-lying to concave-downward pull-apart fractures. Low pH and fO 2 hydrothermal fluids at temperatures near 200 0 C (392 0 F) permeated the fractured rocks; these fluids were rich in fluorine and potassium, and contained uranium as uranous-fluoride complexes. Fluid-wall rock interaction increased fluid pH, causing precipitation of uranium minerals. At the deepest exposed levels, wall rocks were altered to kaolinite and sericite, and uraninite, coffinite, jordisite, fluorite, molybdenite, quartz, and pyrite (with delta 34 S near zero per mil) were deposited. The fluids were progressively oxidized higher in the system; iron in the wall rocks was oxidized to hematite, and sooty uraninite and umohoite were deposited

Hydrothermal activity at slow-spreading ridges: variability and importance of magmatic controls

Science.gov (United States)

Escartin, Javier

2016-04-01

Hydrothermal activity along mid-ocean ridge axes is ubiquitous, associated with mass, chemical, and heat exchanges between the deep lithosphere and the overlying envelopes, and sustaining chemiosynthetic ecosystems at the seafloor. Compared with hydrothermal fields at fast-spreading ridges, those at slow spreading ones show a large variability as their location and nature is controlled or influenced by several parameters that are inter-related: a) tectonic setting, ranging from 'volcanic systems' (along the rift valley floor, volcanic ridges, seamounts), to 'tectonic' ones (rift-bounding faults, oceanic detachment faults); b) the nature of the host rock, owing to compositional heterogeneity of slow-spreading lithosphere (basalt, gabbro, peridotite); c) the type of heat source (magmatic bodies at depth, hot lithosphere, serpentinization reactions); d) and the associated temperature of outflow fluids (high- vs.- low temperature venting and their relative proportion). A systematic review of the distribution and characteristics of hydrothermal fields along the slow-spreading Mid-Atlantic Ridge suggests that long-lived hydrothermal activity is concentrated either at oceanic detachment faults, or along volcanic segments with evidence of robust magma supply to the axis. A detailed study of the magmatically robust Lucky Strike segment suggests that all present and past hydrothermal activity is found at the center of the segment. The association of these fields to central volcanos, and the absence of indicators of hydrothermal activity along the remaining of the ridge segment, suggests that long-lived hydrothermal activity in these volcanic systems is maintained by the enhanced melt supply and the associated magma chamber(s) required to build these volcanic edifices. In this setting, hydrothermal outflow zones at the seafloor are systematically controlled by faults, indicating that hydrothermal fluids in the shallow crust exploit permeable fault zones to circulate. While

High-pressure applications in medicine and pharmacology

Energy Technology Data Exchange (ETDEWEB)

Silva, Jerson L; Foguel, Debora; Suarez, Marisa; Gomes, Andre M O; Oliveira, Andrea C [Centro Nacional de Ressonancia Magnetica Nuclear, Departamento de Bioquimica Medica, Instituto de Ciencias Biomedicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-590 (Brazil)

2004-04-14

High pressure has emerged as an important tool to tackle several problems in medicine and biotechnology. Misfolded proteins, aggregates and amyloids have been studied, which point toward the understanding of the protein misfolding diseases. High hydrostatic pressure (HHP) has also been used to dissociate non-amyloid aggregates and inclusion bodies. The diverse range of diseases that result from protein misfolding has made this theme an important research focus for pharmaceutical and biotech companies. The use of high pressure promises to contribute to identifying the mechanisms behind these defects and creating therapies against these diseases. High pressure has also been used to study viruses and other infectious agents for the purpose of sterilization and in the development of vaccines. Using pressure, we have detected the presence of a ribonucleoprotein intermediate, where the coat protein is partially unfolded but bound to RNA. These intermediates are potential targets for antiviral compounds. The ability of pressure to inactivate viruses, prions and bacteria has been evaluated with a view toward the applications of vaccine development and virus sterilization. Recent studies demonstrate that pressure causes virus inactivation while preserving the immunogenic properties. There is increasing evidence that a high-pressure cycle traps a virus in the 'fusion intermediate state', not infectious but highly immunogenic.

High-pressure applications in medicine and pharmacology

International Nuclear Information System (INIS)

Silva, Jerson L; Foguel, Debora; Suarez, Marisa; Gomes, Andre M O; Oliveira, Andrea C

2004-01-01

High pressure has emerged as an important tool to tackle several problems in medicine and biotechnology. Misfolded proteins, aggregates and amyloids have been studied, which point toward the understanding of the protein misfolding diseases. High hydrostatic pressure (HHP) has also been used to dissociate non-amyloid aggregates and inclusion bodies. The diverse range of diseases that result from protein misfolding has made this theme an important research focus for pharmaceutical and biotech companies. The use of high pressure promises to contribute to identifying the mechanisms behind these defects and creating therapies against these diseases. High pressure has also been used to study viruses and other infectious agents for the purpose of sterilization and in the development of vaccines. Using pressure, we have detected the presence of a ribonucleoprotein intermediate, where the coat protein is partially unfolded but bound to RNA. These intermediates are potential targets for antiviral compounds. The ability of pressure to inactivate viruses, prions and bacteria has been evaluated with a view toward the applications of vaccine development and virus sterilization. Recent studies demonstrate that pressure causes virus inactivation while preserving the immunogenic properties. There is increasing evidence that a high-pressure cycle traps a virus in the 'fusion intermediate state', not infectious but highly immunogenic

Modelling of hydrothermal characteristics of centrifugal nozzles

International Nuclear Information System (INIS)

Yarkho, A.A.; Omelchenko, M.P.; Borshchev, V.A.

1990-01-01

Presented for the first time is a method of recalculating the hydrothermal characteristics of centrifugal nozzles obtained in laboratory conditions for full-scale nozzles. From the experimental hydrothermal characteristics of nozzles observed in the laboratory it is allowed to calculate the hydrothermal characteristics of any other centrifugal nozzle whose diameter and dimensionless geometric characteristic are known

Hydrothermal synthesis and characterization of polycrystalline gadolinium aluminum perovskite (GdAlO3, GAP

Directory of Open Access Journals (Sweden)

N. Girish H.

2015-06-01

Full Text Available Gadolinium aluminum perovskite (GdAlO3, GAP is a promising high temperature ceramic material, known for its wide applications in phosphors. Polycrystalline gadolinium aluminum perovskites were synthesized using a precursor of co-precipitate gel of GdAlO3 by employing hydrothermal supercritical fluid technique under pressure and temperature ranging from 150 to 200 MPa and 600 to 700 °C, respectively. The resulted products of GAP were studied using the characterization techniques, such as powder X-ray diffraction analysis (XRD, infrared spectroscopy (IR, scanning electron microscopy (SEM and energy dispersive analysis of X-ray (EDX. The X-ray diffraction pattern matched well with the reported orthorhombic GAP pattern (JCPDS-46-0395.

What Is High Blood Pressure Medicine?

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... a medicine calendar. • Set a reminder on your smartphone. What types of medicine may be prescribed? One ... High Blood Pressure Medicine? What are their side effects? For many people, high blood pressure medicine can ...

High Blood Pressure in Pregnancy

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... of the baby. Controlling your blood pressure during pregnancy and getting regular prenatal care are important for ... your baby. Treatments for high blood pressure in pregnancy may include close monitoring of the baby, lifestyle ...

Enhanced bioactivity and biocompatibility of nanostructured hydroxyapatite coating by hydrothermal annealing

International Nuclear Information System (INIS)

Hahn, Byung-Dong; Lee, Jeong-Min; Park, Dong-Soo; Choi, Jong-Jin; Ryu, Jungho; Yoon, Woon-Ha; Choi, Joon-Hwan; Lee, Byoung-Kuk; Kim, Jong-Woo; Kim, Hyoun-Ee; Kim, Seong-Gon

2011-01-01

The crystallinity of hydroxyapatite (HA) coatings prepared by aerosol deposition may be increased by heating in air or low-temperature hydrothermal processing. From the X-ray diffraction and Fourier transform infrared spectroscopy results, it was revealed that the crystallinity of the HA coatings significantly increased after the post-annealing. Transmission electron microscopy showed that the conventional furnace heating induced the substantial growth of the HA crystallites, whereas the hydrothermal treatment did not bring about any remarkable change in the HA crystallite size, which remained below 20 nm. The bioactivity of the HA coatings was estimated by the acellular simulated body fluid immersion test. After immersion for 7 days, newly-precipitated apatite crystals were only observed on the surfaces of the samples hydrothermally treated at 170 and 190 deg. C. In addition, the alkaline phosphatase activity of MC3T3-E1 preosteoblast cells cultured on the hydrothermally treated samples was significantly higher than those on the as-deposited coating and conventional furnace heated samples. The enhanced bioactivity and excellent biological in vitro cellular response of the hydrothermally treated samples were attributed to their nanostructured nature and high degree of crystallinity.

On high-pressure melting of tantalum

Science.gov (United States)

Luo, Sheng-Nian; Swift, Damian C.

2007-01-01

The issues related to high-pressure melting of Ta are discussed within the context of diamond-anvil cell (DAC) and shock wave experiments, theoretical calculations and common melting models. The discrepancies between the extrapolations of the DAC melting curve and the melting point inferred from shock wave experiments, cannot be reconciled either by superheating or solid-solid phase transition. The failure to reproduce low-pressure DAC melting curve by melting models such as dislocation-mediated melting and the Lindemann law, and molecular dynamics and quantum mechanics-based calculations, undermines their predictions at moderate and high pressures. Despite claims to the contrary, the melting curve of Ta (as well as Mo and W) remains inconclusive at high pressures.

First Survey For Submarine Hydrothermal Vents In NE Sulawesi, Indonesia

Science.gov (United States)

McConachy, T.; Binns, R.; Permana, H.

2001-12-01

The IASSHA-2001 cruise (Indonesia-Australia Survey for Submarine Hydrothermal Activity) was successfully conducted from June 1 to June 29 on board Baruna Jaya VIII. Preliminary results are reported of the first expedition to locate and study submarine hydrothermal activity in north east Sulawesi. Leg A focussed on Tomini Bay, a virtually unexplored Neogene sedimentary basin. Its objective was to test whether modern sediment-hosted hydrothermal activity occurred on the sea floor. The results of new bathymetric mapping, sediment coring and CTD/transmissometer hydrocasts negate the likely presence in central Tomini Bay of large-scale modern analogues of hydrothermal massive sulfide environments involving hydrothermal venting of basinal or magma-derived fluids into reduced sediments. It is possible that the "heat engine" required to drive circulation of basinal and hydrothermal fluids is today too weak. Surveys around Colo volcano indicate that it may be in its final stage of evolution. Leg B studied the arc and behind-arc sectors of the Sangihe volcanic island chain extending northwards from Quaternary volcanoes on the northeastern tip of Sulawesi's North Arm, near Manado. West of the main active chain and extending northwards from Manado there is a subparallel ridge surmounted by a number of high (>2000 m) seamounts of uncertain age. Fifteen relatively high-standing submarine edifices were crossed during this leg, of which nine were tested for hydrothermal activity by hydrocast and dredging. Eight sites were known from previous bathymetric surveys, and seven are new discoveries made by narrow-beam or multibeam echo sounding. Two submarine edifices at least 1000 m high were discovered in the strait immediately north of Awu volcano on Sangihe Island. One, with crest at 206 m, is surrounded by a circular platform 300m deep which we infer to be a foundered fringing reef to a formerly emergent island. The other, lacking such a platform, appears relatively young and may be

Laser-Machined Microcavities for Simultaneous Measurement of High-Temperature and High-Pressure

Directory of Open Access Journals (Sweden)

Zengling Ran

2014-08-01

Full Text Available Laser-machined microcavities for simultaneous measurement of high-temperature and high-pressure are demonstrated. These two cascaded microcavities are an air cavity and a composite cavity including a section of fiber and an air cavity. They are both placed into a pressure chamber inside a furnace to perform simultaneous pressure and high-temperature tests. The thermal and pressure coefficients of the short air cavity are ~0.0779 nm/°C and ~1.14 nm/MPa, respectively. The thermal and pressure coefficients of the composite cavity are ~32.3 nm/°C and ~24.4 nm/MPa, respectively. The sensor could be used to separate temperature and pressure due to their different thermal and pressure coefficients. The excellent feature of such a sensor head is that it can withstand high temperatures of up to 400 °C and achieve precise measurement of high-pressure under high temperature conditions.

Laser-machined microcavities for simultaneous measurement of high-temperature and high-pressure.

Science.gov (United States)

Ran, Zengling; Liu, Shan; Liu, Qin; Huang, Ya; Bao, Haihong; Wang, Yanjun; Luo, Shucheng; Yang, Huiqin; Rao, Yunjiang

2014-08-07

Laser-machined microcavities for simultaneous measurement of high-temperature and high-pressure are demonstrated. These two cascaded microcavities are an air cavity and a composite cavity including a section of fiber and an air cavity. They are both placed into a pressure chamber inside a furnace to perform simultaneous pressure and high-temperature tests. The thermal and pressure coefficients of the short air cavity are ~0.0779 nm/°C and ~1.14 nm/MPa, respectively. The thermal and pressure coefficients of the composite cavity are ~32.3 nm/°C and ~24.4 nm/MPa, respectively. The sensor could be used to separate temperature and pressure due to their different thermal and pressure coefficients. The excellent feature of such a sensor head is that it can withstand high temperatures of up to 400 °C and achieve precise measurement of high-pressure under high temperature conditions.

Techniques in high pressure neutron scattering

CERN Document Server

Klotz, Stefan

2013-01-01

Drawing on the author's practical work from the last 20 years, Techniques in High Pressure Neutron Scattering is one of the first books to gather recent methods that allow neutron scattering well beyond 10 GPa. The author shows how neutron scattering has to be adapted to the pressure range and type of measurement.Suitable for both newcomers and experienced high pressure scientists and engineers, the book describes various solutions spanning two to three orders of magnitude in pressure that have emerged in the past three decades. Many engineering concepts are illustrated through examples of rea

High blood pressure and eye disease

Science.gov (United States)

... this page: //medlineplus.gov/ency/article/000999.htm High blood pressure and eye disease To use the sharing features on this page, please enable JavaScript. High blood pressure can damage blood vessels in the retina . The ...

Mechanical and transport properties of rocks at high temperatures and pressures. Task II. Fracture permeability of crystalline rocks as a function of temperature, pressure, and hydrothermal alteration. Final report

Energy Technology Data Exchange (ETDEWEB)

Johnson, B.

1985-11-01

Pore-fluid chemical interactions on both short and long time scales can significantly change the permeability of a rock. Measurement of the permeability variations requires adaption and modification on standard measurement systems, with special attention given to pore-fluid flow rates and metal corrosion of system components. In this report, system requirements and capabilities are reviewed, analyzed, and recommendations made. Special attention is given to the choice of corrosion resistant metals, fluid-flow systems, back-pressure systems, jacketing materials, and flow-rate measurement. On the basis of this study, an economical, highly flexible, permeability system was designed and built. The system allows measurement of permeability over the darcy to nanodarcy range, using geologically meaningful, chemically reactive, pore fluids under constant volume flow rates as small as 0.2 ml/day at temperatures in excess of 300C, fluid pressures to 20 MPa, and confining pressures to 100 MPa. 7 refs., 3 figs., 1 tab.

Rare Earth Oxide Fluoride Nanoparticles And Hydrothermal Method For Forming Nanoparticles

Science.gov (United States)

Fulton, John L.; Hoffmann, Markus M.

2003-12-23

A hydrothermal method for forming nanoparticles of a rare earth element, oxygen and fluorine has been discovered. Nanoparticles comprising a rare earth element, oxygen and fluorine are also described. These nanoparticles can exhibit excellent refractory properties as well as remarkable stability in hydrothermal conditions. The nanoparticles can exhibit excellent properties for numerous applications including fiber reinforcement of ceramic composites, catalyst supports, and corrosion resistant coatings for high-temperature aqueous solutions.

Hydrothermal performance of catalyst supports

Energy Technology Data Exchange (ETDEWEB)

Elam, Jeffrey W.; Marshall, Christopher L.; Libera, Joseph A.; Dumesic, James A.; Pagan-Torres, Yomaira J.

2018-04-10

A high surface area catalyst with a mesoporous support structure and a thin conformal coating over the surface of the support structure. The high surface area catalyst support is adapted for carrying out a reaction in a reaction environment where the thin conformal coating protects the support structure within the reaction environment. In various embodiments, the support structure is a mesoporous silica catalytic support and the thin conformal coating comprises a layer of metal oxide resistant to the reaction environment which may be a hydrothermal environment.

In-situ Raman spectroscopic study of aluminate speciation in H2O-KOH solutions at high pressures and temperatures

Science.gov (United States)

Mookherjee, M.; Keppler, H.; Manning, C. E.

2009-12-01

The solubility of corundum in H2O is low even at high pressure and temperatures. Therefore, it is commonly assumed that alumina remains essentially immobile during fluid-rock interaction. However, field and experimental evidence suggests that alumina solubility is strongly enhanced in the presence of silica as well as in alkaline solutions. In order to understand what controls the alumina solubility and how it is enhanced as a function of fluid composition, we conducted Raman-spectroscopic study of Al speciation in aqueous fluids at high pressure and temperature. Experiments were carried out in an externally heated hydrothermal diamond-anvil cell equipped with low-fluorescence diamonds and iridium gaskets. Raman spectra were collected with a Horiba Jobin-Yvon Labram HR spectrometer using the 514 nm line of an argon laser for excitation. In a first series of experiments, the speciation of alumina was studied in a 1 M KOH solution in equilibrium with corundum up to 700 oC and ~1 GPa. The Raman spectra show a prominent band at 618 cm-1 interpreted to arise from Al-O stretching vibrations associated with the tetrahedral [Al(OH)4]1- species. At higher pressure and temperature, an additional vibrational mode appears in the spectra at 374 cm-1 (full width at half maximum ~ 20 cm-1). This feature is tentatively attributed to [(OH)3Al-O-Al(OH)3]2- (Moolenaar et al. 1970, Jour. Phys. Chem., 74, 3629-3636). No evidence for KAl(OH)4 was observed, consistent with piston cylinder experiments at 700 oC and 1 GPa (Wohlers & Manning, 2009, Chem. Geol., 262, 310). Upon cooling from high-pressure and high temperature, slow kinetics of corundum regrowth lead to oversaturation in the solutions, as evidenced by sharp peaks at 930 and 1066 cm-1 observed upon cooling. These features are probably due to colloidal aluminum hydroxide. The results provide the first evidence for aluminate polymerization at high pressure and temperature, and offer insights into the causes for enhancement of

Magnetic and Superconducting Materials at High Pressures

Energy Technology Data Exchange (ETDEWEB)

Struzhkin, Viktor V. [Carnegie Inst. of Washington, Washington, DC (United States)

2015-03-24

The work concentrates on few important tasks in enabling techniques for search of superconducting compressed hydrogen compounds and pure hydrogen, investigation of mechanisms of high-Tc superconductivity, and exploring new superconducting materials. Along that route we performed several challenging tasks, including discovery of new forms of polyhydrides of alkali metal Na at very high pressures. These experiments help us to establish the experimental environment that will provide important information on the high-pressure properties of hydrogen-rich compounds. Our recent progress in RIXS measurements opens a whole field of strongly correlated 3d materials. We have developed a systematic approach to measure major electronic parameters, like Hubbard energy U, and charge transfer energy Δ, as function of pressure. This technique will enable also RIXS studies of magnetic excitations in iridates and other 5d materials at the L edge, which attract a lot of interest recently. We have developed new magnetic sensing technique based on optically detected magnetic resonance from NV centers in diamond. The technique can be applied to study superconductivity in high-TC materials, to search for magnetic transitions in strongly correlated and itinerant magnetic materials under pressure. Summary of Project Activities; development of high-pressure experimentation platform for exploration of new potential superconductors, metal polyhydrides (including newly discovered alkali metal polyhydrides), and already known superconductors at the limit of static high-pressure techniques; investigation of special classes of superconducting compounds (high-Tc superconductors, new superconducting materials), that may provide new fundamental knowledge and may prove important for application as high-temperature/high-critical parameter superconductors; investigation of the pressure dependence of superconductivity and magnetic/phase transformations in 3d transition metal compounds, including

High Blood Pressure: Unique to Older Adults

Science.gov (United States)

... our e-newsletter! Aging & Health A to Z High Blood Pressure Hypertension Unique to Older Adults This section provides ... Pressure Targets are Different for Very Old Adults High blood pressure (also called hypertension) increases your chance of having ...

Characterized hydrochar of algal biomass for producing solid fuel through hydrothermal carbonization.

Science.gov (United States)

Park, Ki Young; Lee, Kwanyong; Kim, Daegi

2018-06-01

The aim of this work was to study the characterized hydrochar of algal biomass to produce solid fuel though hydrothermal carbonization. Hydrothermal carbonization conducted at temperatures ranging from 180 to 270 °C with a 60 min reaction improved the upgrading of the fuel properties and the dewatering of wet-basis biomasses such as algae. The carbon content, carbon recovery, energy recovery, and atomic C/O and C/H ratios in all the hydrochars in this study were improved. These characteristic changes in hydrochar from algal biomass are similar to the coalification reactions due to dehydration and decarboxylation with an increase in the hydrothermal reaction temperature. The results of this study indicate that hydrothermal carbonization can be used as an effective means of generating highly energy-efficient renewable fuel resources using algal biomass. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evolutionary strategies of viruses, bacteria and archaea in hydrothermal vent ecosystems revealed through metagenomics.

Directory of Open Access Journals (Sweden)

Rika E Anderson

Full Text Available The deep-sea hydrothermal vent habitat hosts a diverse community of archaea and bacteria that withstand extreme fluctuations in environmental conditions. Abundant viruses in these systems, a high proportion of which are lysogenic, must also withstand these environmental extremes. Here, we explore the evolutionary strategies of both microorganisms and viruses in hydrothermal systems through comparative analysis of a cellular and viral metagenome, collected by size fractionation of high temperature fluids from a diffuse flow hydrothermal vent. We detected a high enrichment of mobile elements and proviruses in the cellular fraction relative to microorganisms in other environments. We observed a relatively high abundance of genes related to energy metabolism as well as cofactors and vitamins in the viral fraction compared to the cellular fraction, which suggest encoding of auxiliary metabolic genes on viral genomes. Moreover, the observation of stronger purifying selection in the viral versus cellular gene pool suggests viral strategies that promote prolonged host integration. Our results demonstrate that there is great potential for hydrothermal vent viruses to integrate into hosts, facilitate horizontal gene transfer, and express or transfer genes that manipulate the hosts' functional capabilities.

Evolutionary strategies of viruses, bacteria and archaea in hydrothermal vent ecosystems revealed through metagenomics.

Science.gov (United States)

Anderson, Rika E; Sogin, Mitchell L; Baross, John A

2014-01-01

The deep-sea hydrothermal vent habitat hosts a diverse community of archaea and bacteria that withstand extreme fluctuations in environmental conditions. Abundant viruses in these systems, a high proportion of which are lysogenic, must also withstand these environmental extremes. Here, we explore the evolutionary strategies of both microorganisms and viruses in hydrothermal systems through comparative analysis of a cellular and viral metagenome, collected by size fractionation of high temperature fluids from a diffuse flow hydrothermal vent. We detected a high enrichment of mobile elements and proviruses in the cellular fraction relative to microorganisms in other environments. We observed a relatively high abundance of genes related to energy metabolism as well as cofactors and vitamins in the viral fraction compared to the cellular fraction, which suggest encoding of auxiliary metabolic genes on viral genomes. Moreover, the observation of stronger purifying selection in the viral versus cellular gene pool suggests viral strategies that promote prolonged host integration. Our results demonstrate that there is great potential for hydrothermal vent viruses to integrate into hosts, facilitate horizontal gene transfer, and express or transfer genes that manipulate the hosts' functional capabilities.

Transportable, small high-pressure preservation vessel for cells

International Nuclear Information System (INIS)

Kamimura, N; Sotome, S; Shimizu, A; Nakajima, K; Yoshimura, Y

2010-01-01

We have previously reported that the survival rate of astrocytes increases under high-pressure conditions at 4 0 C. However, pressure vessels generally have numerous problems for use in cell preservation and transportation: (1) they cannot be readily separated from the pressurizing pump in the pressurized state; (2) they are typically heavy and expensive due the use of materials such as stainless steel; and (3) it is difficult to regulate pressurization rate with hand pumps. Therefore, we developed a transportable high-pressure system suitable for cell preservation under high-pressure conditions. This high-pressure vessel has the following characteristics: (1) it can be easily separated from the pressurizing pump due to the use of a cock-type stop valve; (2) it is small and compact, is made of PEEK and weighs less than 200 g; and (3) pressurization rate is regulated by an electric pump instead of a hand pump. Using this transportable high-pressure vessel for cell preservation, we found that astrocytes can survive for 4 days at 1.6 MPa and 4 0 C.

Process characteristics for microwave assisted hydrothermal carbonization of cellulose.

Science.gov (United States)

Zhang, Junting; An, Ying; Borrion, Aiduan; He, Wenzhi; Wang, Nan; Chen, Yirong; Li, Guangming

2018-07-01

The process characteristics of microwave assisted hydrothermal carbonization of cellulose was investigated and a first order kinetics model based on carbon concentration was developed. Chemical properties analysis showed that comparing to conventional hydrothermal carbonization, hydrochar with comparable energy properties can be obtained with 5-10 times decrease in reaction time with assistance of microwave heating. Results from kinetics study was in great agreement with experimental analysis, that they both illustrated the predominant mechanism of the reaction depend on variations in the reaction rates of two co-existent pathways. Particularly, the pyrolysis-like intramolecular dehydration reaction was proved to be the predominant mechanism for hydrochar generation under high temperatures. Finally, the enhancement effects of microwave heating were reflected under both soluble and solid pathways in this research, suggesting microwave-assisted hydrothermal carbonization as a more attracting method for carbon-enriched hydrochar recovery. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydrothermal Synthesis and Electrochemical Properties of Spherical α-MnO2 for Supercapacitors.

Science.gov (United States)

Chen, Ya; Qin, Wenqing; Fan, Ruijuan; Wang, Jiawei; Chen, Baizhen

2015-12-01

In the present work, spherical α-MnO2 with a high specific capacitance was synthesized by a two-step hydrothermal route. MnCO3 precursors were first prepared by a common hydrothermal method, and then converted to α-MnO2 via a hydrothermal reaction between the precursors and KMnO4 solutions. The effects of hydrothermal temperature on the morphology, crystal structure and specific area of the MnO2 were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET measurements. The electrochemical capacitive properties of the manganese dioxides with different morphologies and structures were evaluated by cyclic voltammetry and galvonostatic charge-discharge tests. The results showed that the temperature in the second hydrothermal step had prominent impact on the capacitive properties of a-MnO2. The MnO2 synthesized at 150 *C exhibited a highest specific capacitance of 328.4 Fx g(-1) at a charge-discharge current density of 100 mA x g(-1).

Production of lightweight refractory material by hydrothermal process

International Nuclear Information System (INIS)

Sulejmani, Ramiz B.

2002-01-01

Many different processes of production of lightweight refractories are well known over the World. Traditional production of lightweight refractories is by addition of combustibles or by a special frothing process. This work is concerned with hydrothermal of lightweight refractories from rice husk ash. The rice husk ash, used in present investigations were from Kocani region, R. Macedonia. The chemical analysis of the rice husk ash shows that it contains 91,8 - 93,7% SiO 2 and some alkaline and alkaline earth oxides. Microscopic and X - ray diffraction examinations of the rice husk ash have shown that it is composed of cristobalite, tridimite and amorphous silica. The composition of the mixture for lightweight refractory brick production is 93,4% rice husk ash and 6,6% Ca(OH) 2 . The mixtures were well mixed, moistened and pressed at 5 - 10 MPa. The hydrothermal reactions between calcium hydroxide and rice husk ash over the temperature range 80 - 160 o C were investigated. The period of autoclave treatment was from 2 to 72 h. After the hydrothermal treatment of the samples, the mineralogical composition, bulk density, density, cold crushing strength, porosity, refractoriness and thermal expansion were examined. Analysing the properties of the obtained samples it can be concluded that from rice husk ash and calcium hydroxide under hydrothermal condition it is possible to obtain lightweight acid refractory material with high quality.(Author)

Hydrothermal synthesis of NiCo2O4 nanowires/nitrogen-doped graphene for high-performance supercapacitor

International Nuclear Information System (INIS)

Yu, Mei; Chen, Jianpeng; Ma, Yuxiao; Zhang, Jingdan; Liu, Jianhua; Li, Songmei; An, Junwei

2014-01-01

Highlights: • NCO/NG composites were synthesized in a water–glycerol mixed solvent via hydrothermal treatment and subsequent calcination. • NiCo 2 O 4 nanowires are dispersed on NG nanosheets and the composite has porous structure. • The NCO/NG composite exhibits a high specific capacitance and long cycling performance. - Abstract: NiCo 2 O 4 nanowires/nitrogen-doped graphene (NCO/NG) composite materials were synthesized by hydrothermal treatment in a water–glycerol mixed solvent and subsequent thermal transformation. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The electrochemical performance of the composites was evaluated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectrum techniques. NiCo 2 O 4 nanowires are densely coated by nitrogen-doped graphene and the composite displays good electrochemical performance. The maximum specific capacitance of NCO/NG is 1273.13 F g −1 at 0.5 A g −1 in 6 M KOH aqueous solution, and it exhibits good capacity retention without noticeable degradation after 3000 cycles at 4 A g −1

Asymmetrical hydrothermal system below Merapi volcano imaged by geophysical data.

Science.gov (United States)

Byrdina, Svetlana; Friedel, Sven; Budi-Santoso, Agus; Suryanto, Wiwit; Suhari, Aldjarishy; Vandemeulebrouck, Jean; Rizal, Mohhamed H.; Grandis, Hendra

2017-04-01

A high-resolution image of the hydrothermal system of Merapi volcano is obtained using electrical resistivity tomography (ERT), self-potential, and CO2 flux mappings. The ERT inversions identify two distinct low-resistivity bodies, at the base of the south flank and in the summit area, that represent likely two parts of an interconnected hydrothermal system. In the summit area, the extension of the hydrothermal system is clearly limited by the main geological structures which are actual and ancient craters. A sharp resistivity contrast at ancient crater rim Pasar-Bubar separates a conductive hydrothermal system (20 - 50 Ωm) from the resistive andesite lava flows and pyroclastic deposits (2000 - 50 000 Ωm). High diffuse CO2 degassing (with a median value of 400g m -2 d -1) is observed in a narrow vicinity of the active crater rim and close to the Pasar-Bubar. The existence of preferential fluid circulation along this ancient crater rim is also evidenced by self-potential data. The total CO2 degassing across the accessible summit area with a surface of 1.4 · 10 5 m 2 is around 20 td -1. Before the 2010 eruption, Toutain et al. (2009) estimated a higher value of the total diffuse degassing from the summit area (about 200 - 230 td -1). This drop in the diffuse degassing can be related to the decrease in the magmatic activity, to the change of the summit morphology or to a combination of these factors. On the south flank of Merapi, the resistivity model shows spectacular stratification. While surficial recent andesite lava flows are characterized by resistivity exceeding 100 000 Ωm, resistivity as low as 10 Ωm has been encountered at a depth of 200 m at the base of the south flank and was interpreted as a presence of the hydrothermal system. We suggest that a sandwich-like structure of stratified pyroclastic deposits on the flanks of Merapi screen and separate the flow of hydrothermal fluids with the degassing occurring mostly through the fractured crater rims

Role of triton X-100 and hydrothermal treatment on the morphological features of nanoporous hydroxyapatite nanorods

Energy Technology Data Exchange (ETDEWEB)

Iyyappan, E.; Wilson, P., E-mail: catwils@gmail.com; Sheela, K.; Ramya, R.

2016-06-01

Hydroxyapatite (HA) particles were synthesized using Ca(NO{sub 3}){sub 2}·4H{sub 2}O and (NH{sub 4}){sub 2}HPO{sub 4} as precursors with varying contents of non-ionic surfactant viz., triton X-100 (organic modifier) via co-precipitation method followed by hydrothermal treatment. The prepared HA particles have been characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Energy Dispersive X-ray Analysis (EDX), High Resolution Scanning Electron Microscopy (HRSEM), High Resolution Transmission Electron Microscopy (HRTEM) and Nitrogen adsorption–desorption experiments. The XRD and FTIR studies indicate the formation of HA phase in all the synthesized samples. The specific roles of triton X-100 and hydrothermal treatment in dispersing and in directing the crystal growth respectively have been discussed by comparing the observations from individual experiments using triton X-100 and hydrothermal treatment with that of combined protocol involving both. The plausible mechanism for the individual roles of both triton X-100 and hydrothermal treatment have been proposed. - Highlights: • Nanoporous HA nanorods are synthesized via triton X-100 assisted hydrothermal treatment. • Triton X-100 hinder the agglomeration of HA primary particles • Hydrothermal treatment increase the aspect ratio of the HA particles • Oriented attachment of HA particles occurs under hydrothermal treatment facilitated by triton X-100 stabilized HA collides • The percentage of mesopore volume is higher for hydrothermally treated samples.

A feasibility study of hydrothermal treatment of rice straw for multi-production of solid fuel and liquid fertilizer

Science.gov (United States)

Samnang, S.; Prawisudha, P.; Pasek, A. D.

2017-05-01

Energy use has increased steadily over the last century due to population and industry increase. With the growing of GHG, biomass becomes an essential contributor to the world energy need. Indonesia is the third rice producer in the world. Rice straw has been converted to solid fuel by Hydrothermal Treatment (HT) for electricity generation. HT is a boiling solid organic or inorganic substance in water at high pressure and temperature within a holding time. HT converts high moisture content biomass into dried, uniform, pulverized, and higher energy density solid fuels. HT can effectively transport nutrient components in biomass into a liquid product known as fertilizer. This paper deals with an evaluation of hydrothermal treatment of rice straw for solid fuel and liquid fertilizer. An investigation of rice straw characteristics were completed for Bandung rice straw with various condition of temperature, biomass-water ratio, and holding time in the purpose to find the changes of calorific value for solid product and (N, P, K, and pH) for liquid product. The results showed that solid product at 225 °C and 90 min consists in a heating value 13.8 MJ/kg equal to lignite B. Liquid product at 225 °C and 90 min had the NPK content similar to that of micronutrients compound liquid fertilizer. The dried solid product should be useful for Coal Fire Power Plant, and the liquid product is suitable for plants. This research proves that hydrothermal process can be applied to rice straw to produce solid fuel and liquid fertilizer with adequate quality.

Phase Transformation of Hydrothermally Synthesized Nanoparticle ...

African Journals Online (AJOL)

Mild hydrothermal hydrolysis of TiCl4 produces nanorods of the rutile phase of titanium dioxide in high yield, while in the presence of organic acids (citric, acetic, D-tartaric and benzoic acids) anatase is the only product. The effect of these organic acids on the products of the hydrolysis reaction as well as the reaction kinetics ...

High-pressure high-temperature phase diagram of organic crystal paracetamol

Science.gov (United States)

Smith, Spencer J.; Montgomery, Jeffrey M.; Vohra, Yogesh K.

2016-01-01

High-pressure high-temperature (HPHT) Raman spectroscopy studies have been performed on the organic crystal paracetamol in a diamond anvil cell utilizing boron-doped heating diamond anvil. Isobaric measurements were conducted at pressures up to 8.5 GPa and temperature up to 520 K in five different experiments. Solid state phase transitions from monoclinic Form I  →  orthorhombic Form II were observed at various pressures and temperatures as well as transitions from Form II  →  unknown Form IV. The melting temperature for paracetamol was observed to increase with increasing pressures to 8.5 GPa. This new data is combined with previous ambient temperature high-pressure Raman and x-ray diffraction data to create the first HPHT phase diagram of paracetamol.

High-pressure high-temperature phase diagram of organic crystal paracetamol

International Nuclear Information System (INIS)

Smith, Spencer J; Montgomery, Jeffrey M; Vohra, Yogesh K

2016-01-01

High-pressure high-temperature (HPHT) Raman spectroscopy studies have been performed on the organic crystal paracetamol in a diamond anvil cell utilizing boron-doped heating diamond anvil. Isobaric measurements were conducted at pressures up to 8.5 GPa and temperature up to 520 K in five different experiments. Solid state phase transitions from monoclinic Form I  →  orthorhombic Form II were observed at various pressures and temperatures as well as transitions from Form II  →  unknown Form IV. The melting temperature for paracetamol was observed to increase with increasing pressures to 8.5 GPa. This new data is combined with previous ambient temperature high-pressure Raman and x-ray diffraction data to create the first HPHT phase diagram of paracetamol. (paper)

High potential for temperate viruses to drive carbon cycling in chemoautotrophy-dominated shallow-water hydrothermal vents.

Science.gov (United States)

Rastelli, Eugenio; Corinaldesi, Cinzia; Dell'Anno, Antonio; Tangherlini, Michael; Martorelli, Eleonora; Ingrassia, Michela; Chiocci, Francesco L; Lo Martire, Marco; Danovaro, Roberto

2017-11-01

Viruses are the most abundant life forms in the world's oceans and they are key drivers of biogeochemical cycles, but their impact on the microbial assemblages inhabiting hydrothermal vent ecosystems is still largely unknown. Here, we analysed the viral life strategies and virus-host interactions in the sediments of a newly discovered shallow-water hydrothermal field of the Mediterranean Sea. Our study reveals that temperate viruses, once experimentally induced to replicate, can cause large mortality of vent microbes, significantly reducing the chemoautotrophic carbon production, while enhancing the metabolism of microbial heterotrophs and the re-cycling of the organic matter. These results provide new insights on the factors controlling primary and secondary production processes in hydrothermal vents, suggesting that the inducible provirus-host interactions occurring in these systems can profoundly influence the functioning of the microbial food web and the efficiency in the energy transfer to the higher trophic levels. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Foaming Glass Using High Pressure Sintering

DEFF Research Database (Denmark)

Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob

Foam glass is a high added value product which contributes to waste recycling and energy efficiency through heat insulation. The foaming can be initiated by a chemical or physical process. Chemical foaming with aid of a foaming agent is the dominant industrial process. Physical foaming has two...... to expand. After heat-treatment foam glass can be obtained with porosities of 80–90 %. In this study we conduct physical foaming of cathode ray tube (CRT) panel glass by sintering under high pressure (5-25 MPa) using helium, nitrogen, or argon at 640 °C (~108 Pa s). Reheating a sample in a heating...... variations. One way is by saturation of glass melts with gas. The other involves sintering of powdered glass under a high gas pressure resulting in glass pellets with high pressure bubbles entrapped. Reheating the glass pellets above the glass transition temperature under ambient pressure allows the bubbles...

Application of Hydrothermal and Non-Hydrothermal TiO2 Nanoporous Materials as New Adsorbents for Removal of Heavy Metal Ions from Aqueous System

Directory of Open Access Journals (Sweden)

Mansoor Anbia

2016-06-01

Full Text Available Hydrothermal and non-hydrothermal spherical TiO2 nanoporous with crystalline framework were prepared by sol-gel method. The Crystalline structures, morphologies and surface texturing of materials were determined by X-ray diffraction (XRD, scanning electron microscopy (SEM and N2 adsorption-desorption isotherms. The Hydrothermal spherical TiO2 nanoporous was found to have a narrow and strong pore size distribution peaks with average of 37.8 Å and pore volume of 0.41 cm3/g and the (Brunauer–Emmett–TellerBET specific surface area of 365 m2/g. Hydrothermal and non-hydrothermal spherical TiO2 nanoporous have been used as adsorbent to study of the adsorption behavior of Pb(II, Co(II and Ni(II ions from aqueous system in a batch system. Effect of equilibrium time on adsorption Pb(II, Co(II and Ni(II ions on these adsorbent was studied The results show that the shaking time 0.5 to 10h has no serious effect on the percentage of ions removal, and the adsorption is fast in all cases. The maximum uptake capacities of Hydrothermal and non-hydrothermal spherical TiO2 nanoporous was calculated. Both hydrothermal and non-hydrothermal TiO2 nanoporous materials were found to have very good potential as new adsorbents in removal of these ions. In batch systems the maximum uptake capacities of Pb(II, Ni(II and Co(II on the hydrothermal and non-hydrothermal TiO2 nanoporous materials was Co(II > Pb(II > Ni(II and Co(II > Ni(II > Pb(II, respectively.

Assessment of operation reserves in hydrothermal electric systems with high wind generation

NARCIS (Netherlands)

Ramos, Andres; Rivier, Michel; García-González, Javier; Latorre, Jesus M.; Morales Espana, G.

2016-01-01

In this paper, we propose a method to analyze the amount of operation reserves procured in a system based on two stages. The first stage is a detailed hourly unit commitment and the second stage is a simulation model with a shorter time period. The method is applied to the Spanish hydrothermal

HIGH PRESSURE COAL COMBUSTON KINETICS PROJECT

Energy Technology Data Exchange (ETDEWEB)

Stefano Orsino

2005-03-30

As part of the U.S. Department of Energy (DoE) initiative to improve the efficiency of coal-fired power plants and reduce the pollution generated by these facilities, DOE has funded the High-Pressure Coal Combustion Kinetics (HPCCK) Projects. A series of laboratory experiments were conducted on selected pulverized coals at elevated pressures with the specific goals to provide new data for pressurized coal combustion that will help extend to high pressure and validate models for burnout, pollutant formation, and generate samples of solid combustion products for analyses to fill crucial gaps in knowledge of char morphology and fly ash formation. Two series of high-pressure coal combustion experiments were performed using SRI's pressurized radiant coal flow reactor. The first series of tests characterized the near burner flame zone (NBFZ). Three coals were tested, two high volatile bituminous (Pittsburgh No.8 and Illinois No.6), and one sub-bituminous (Powder River Basin), at pressures of 1, 2, and 3 MPa (10, 20, and 30 atm). The second series of experiments, which covered high-pressure burnout (HPBO) conditions, utilized a range of substantially longer combustion residence times to produce char burnout levels from 50% to 100%. The same three coals were tested at 1, 2, and 3 MPa, as well as at 0.2 MPa. Tests were also conducted on Pittsburgh No.8 coal in CO2 entrainment gas at 0.2, 1, and 2 MPa to begin establishing a database of experiments relevant to carbon sequestration techniques. The HPBO test series included use of an impactor-type particle sampler to measure the particle size distribution of fly ash produced under complete burnout conditions. The collected data have been interpreted with the help of CFD and detailed kinetics simulation to extend and validate devolatilization, char combustion and pollutant model at elevated pressure. A global NOX production sub-model has been proposed. The submodel reproduces the performance of the detailed chemical

Study on optimizing ultrasonic irradiation period for thick polycrystalline PZT film by hydrothermal method.

Science.gov (United States)

Ohta, Kanako; Isobe, Gaku; Bornmann, Peter; Hemsel, Tobias; Morita, Takeshi

2013-04-01

The hydrothermal method utilizes a solution-based chemical reaction to synthesize piezoelectric thin films and powders. This method has a number of advantages, such as low-temperature synthesis, and high purity and high quality of the product. In order to promote hydrothermal reactions, we developed an ultrasonic assisted hydrothermal method and confirmed that it produces dense and thick lead-zirconate-titanate (PZT) films. In the hydrothermal method, a crystal growth process follows the nucleation process. In this study, we verified that ultrasonic irradiation is effective for the nucleation process, and there is an optimum irradiation period to obtain thicker PZT films. With this optimization, a 9.2-μm-thick PZT polycrystalline film was obtained in a single deposition process. For this film, ultrasonic irradiation was carried out from the beginning of the reaction for 18 h, followed by a 6 h deposition without ultrasonic irradiation. These results indicate that the ultrasonic irradiation mainly promotes the nucleation process. Copyright © 2012 Elsevier B.V. All rights reserved.

High Pressure Physics at Brigham Young University

Science.gov (United States)

Decker, Daniel

2000-09-01

I will discuss the high pressure research of Drs. J. Dean Barnett, Daniel L. Decker and Howard B. Vanfleet of the department of Physics and Astronomy at Brigham Young University and their many graduate students. I will begin by giving a brief history of the beginning of high pressure research at Brigham Young University when H. Tracy Hall came to the University from General Elecrtric Labs. and then follow the work as it progressed from high pressure x-ray diffraction experiments, melting curve measurements under pressure to pressure effects on tracer diffusion and Mossbauer effect spectra. This will be followed by showing the development of pressure calibration techniques from the Decker equation of state of NaCl to the ruby fluorescence spectroscopy and a short discussion of using a liquid cell for hydrostatic measurements and temperature control for precision high pressure measurements. Then I will conclude with a description of thermoelectric measuremnts, critical phenomena at the magnetic Curie point, and the tricritical point of BaTiO_3.

Ideas and perspectives: hydrothermally driven redistribution and sequestration of early Archaean biomass - the "hydrothermal pump hypothesis"

Science.gov (United States)

Duda, Jan-Peter; Thiel, Volker; Bauersachs, Thorsten; Mißbach, Helge; Reinhardt, Manuel; Schäfer, Nadine; Van Kranendonk, Martin J.; Reitner, Joachim

2018-03-01

Archaean hydrothermal chert veins commonly contain abundant organic carbon of uncertain origin (abiotic vs. biotic). In this study, we analysed kerogen contained in a hydrothermal chert vein from the ca. 3.5 Ga Dresser Formation (Pilbara Craton, Western Australia). Catalytic hydropyrolysis (HyPy) of this kerogen yielded n-alkanes up to n-C22, with a sharp decrease in abundance beyond n-C18. This distribution ( ≤ n-C18) is very similar to that observed in HyPy products of recent bacterial biomass, which was used as reference material, whereas it differs markedly from the unimodal distribution of abiotic compounds experimentally formed via Fischer-Tropsch-type synthesis. We therefore propose that the organic matter in the Archaean chert veins has a primarily microbial origin. The microbially derived organic matter accumulated in anoxic aquatic (surface and/or subsurface) environments and was then assimilated, redistributed and sequestered by the hydrothermal fluids (hydrothermal pump hypothesis).

Hydrothermal carbonization. Investigation of process parameters

Energy Technology Data Exchange (ETDEWEB)

Steinbrueck, J.; Rossbach, M.; Reichert, D.; Bockhorn, H. [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. of Technical Chemistry and Polymerchemistry; Walz, L. [Energie Baden-Wuerttemberg AG, Karlsruhe (Germany); Eyler, D. [European Institute for Energy Research, Karlsruhe (Germany)

2010-07-01

For energetic use and as a raw material lignocellulosic biomass becomes more and more important. Among pyrolytic refining, the hydrothermal treatment can be an alternative way to deoxygenerate biomass. The objective of this study is to gain deeper insights into the Hydrothermal Carbonization (HTC) process and also to define basic parameters for the construction of a small pilot plant. The biomass is converted in an autoclave at temperatures between 180 C and 240 C establishing the respective vapour pressure. Reaction times between 1 and 12 hours are applied and various catalysts in different concentrations are tested. Elemental analysis of the product, a brown coal-like solid, shows a composition of ca. C{sub 4}H{sub 3}O{sub 1}, corresponding to a carbon recovery of 60% of initial carbon mass. The elemental composition of the product is independent of the process temperature and the applied biomass, if a minimal reaction time is adhered, which however heavily depends on the reaction temperature. The remaining carbon species in intermediate reaction products in the liquid and gas phase are characterised by use of GC/MS, HPLC and FTIR. From the experimental data a two-way mechanism is deduced that includes a rapid formation of an initial solid and dehydration and decomposition reactions which lead to smaller organic molecules, e.g. furfural and aromatic species, and can be promoted by acid catalysis, e.g. H{sub 2}SO{sub 4}. (orig.)

Rare-earth elements and uranium in high-temperature solutions from East Pacific Rise hydrothermal vent field (130N)

International Nuclear Information System (INIS)

Michard, A.; Albarede, F.; Michard, G.; Minster, J.F.; Charlou, J.L.

1983-01-01

The mobility of rare-earth elements (REE) and U during hydrothermal alteration of the basalts at spreading centres has long been a matter of concern because of its bearing on the evolution and recycling of the oceanic crust. Previous approaches to this problem have been indirect, through studies on altered dredged basalts or ophiolites. Sampling of hydrothermal vent waters from the East Pacific Rise (EPR) at 13 0 N is reported. It provides the first direct evidence of REE-enriched solutions which, however, leave the budget of these elements in the crust and the ocean rather unmodified. In constrast, uranium, like magnesium, is quantitatively taken up from the seawater during the hydrothermal process. (author)

Hydrothermal processes in the Edmond deposits, slow- to intermediate-spreading Central Indian Ridge

Science.gov (United States)

Cao, Hong; Sun, Zhilei; Zhai, Shikui; Cao, Zhimin; Jiang, Xuejun; Huang, Wei; Wang, Libo; Zhang, Xilin; He, Yongjun

2018-04-01

The Edmond hydrothermal field, located on the Central Indian Ridge (CIR), has a distinct mineralization history owing to its unique magmatic, tectonic, and alteration processes. Here, we report the detailed mineralogical and geochemical characteristics of hydrothermal metal sulfides recovered from this area. Based on the mineralogical investigations, the Edmond hydrothermal deposits comprise of high-temperature Fe-rich massive sulfides, medium-temperature Zn-rich sulfide chimney and low-temperature Ca-rich sulfate mineral assemblages. According to these compositions, three distinctive mineralization stages have been identified: (1) low-temperature consisting largely of anhydrite and pyrite/marcasite; (2) medium-high temperature distinguished by the mineral assemblage of pyrite, sphalerite and chalcopyrite; and (3) low-temperature stage characterized by the mineral assemblage of colloidal pyrite/marcasite, barite, quartz, anglesite. Several lines of evidence suggest that the sulfides were influenced by pervasive low-temperature diffuse flows in this area. The hydrothermal deposits are relatively enriched in Fe (5.99-18.93 wt%), Zn (2.10-10.00 wt%) and Ca (0.02-19.15 wt%), but display low Cu (0.28-0.81 wt%). The mineralogical varieties and low metal content of sulfides in the Edmond hydrothermal field both indicate that extensive water circulation is prevalent below the Edmond hydrothermal field. With regard to trace elements, the contents of Pb, Ba, Sr, As, Au, Ag, and Cd are significantly higher than those in other sediment-starved mid-ocean ridges, which is indicative of contribution from felsic rock sources. Furthermore, the multiphase hydrothermal activity and the pervasive water circulation underneath are speculated to play important roles in element remobilization and enrichment. Our findings deepen our understanding about the complex mineralization process in slow- to intermediate-spreading ridges globally.

Effect of biomass pretreatment on the product distribution and composition resulting from the hydrothermal liquefaction of short rotation coppice willow

DEFF Research Database (Denmark)

Grigoras, Ionela; Stroe, Rodica-Elisabeta; Sintamarean, Iulia-Maria

2017-01-01

A major challenge for the implementation of hydrothermal liquefaction (HTL) as a continuous process is the formulation of lignocellulosic feedstock, which is prone to phase separation into water and biomass parts when pressurized. One approach to remedy such phase separation is to reduce the dry...... from the HTL of willow and proposes short rotation coppice as an alternative biomass feedstock for biofuels production. Alkaline–thermal pretreatment, besides making high dry matter pumpable feedstock slurries, also led to an increase in the production of the bio-crude product with an oxygen content...

30 CFR 57.13021 - High-pressure hose connections.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-pressure hose connections. 57.13021... Air and Boilers § 57.13021 High-pressure hose connections. Except where automatic shutoff valves are...-pressure hose lines of 3/4-inch inside diameter or larger, and between high-pressure hose lines of 3/4-inch...

Recent progress in high-pressure studies on organic conductors

Directory of Open Access Journals (Sweden)

Syuma Yasuzuka and Keizo Murata

2009-01-01

Full Text Available Recent high-pressure studies of organic conductors and superconductors are reviewed. The discovery of the highest Tc superconductivity among organics under high pressure has triggered the further progress of the high-pressure research. Owing to this finding, various organic conductors with the strong electron correlation were investigated under high pressures. This review includes the pressure techniques using the cubic anvil apparatus, as well as high-pressure studies of the organic conductors up to 10 GPa showing extraordinary temperature and pressure dependent transport phenomena.

Synthesis and in-depth analysis of highly ordered yttrium doped hydroxyapatite nanorods prepared by hydrothermal method and its mechanical analysis

International Nuclear Information System (INIS)

Nathanael, A. Joseph; Mangalaraj, D.; Hong, S.I.; Masuda, Y.

2011-01-01

In this study, undoped and yttrium (Y) doped nanocrystalline hydroxyapatite crystals were synthesized by the hydrothermal method at 180 °C for 24 h. Highly ordered and oriented hydroxyapatite (HAp) nanorods were prepared by yttrium doping and their nanostructure and physical properties were compared with those of undoped HAp rods. FESEM images showed that the doping with Y ions reduced the diameter (from 25 nm to 15 nm) and increased the length (from 95 nm to 115 nm) of the synthesized rods. The aspect ratio of the undoped and Y-doped nanorods were calculated to be 4.303 (SD = 0.0959) and 7.61 (SD = 0.0355), respectively. Specific surface area (SSA) analysis showed that SSA also increased from 66.74 m 2 /g to 68.57 m 2 /g with the addition of yttrium. Y-doped HAp nanorod reinforced HMWPE composites displayed the better mechanical performance than those reinforced with pure HAp nanorods. The possible strengthening of nanorods and the increase of SSA due to the reduction in the size of nanorods in the presence of yttrium may have contributed to the strengthening of Y-doped HAp/HMWPE composites. - Graphical Abstract: Highly ordered and oriented yttrium doped hydroxyapatite (HAp) nanorods were prepared by hydrothermal method. For undoped HAp the average length of the nanorod is 95 nm with mean diameter of 24 nm and for a Y doped nanorod the average length is ∼ 115 nm and the mean diameter is 15 nm. Mechanical analysis was carried out by polymer/nanoparticle composite method. Highlights: ► Yttrium doped hydroxyapatite nanorods were prepared by hydrothermal method. ► The nanorods have highly uniform size distribution. ► Yttrium substitution and nanostructure formation was confirmed by careful analysis. ► Mechanical strength was analyzed by polymer nanoparticle reinforcement method.

Experimental modeling of Au and Pt coupled transport by chloride hydrothermal fluids at 350-450°C and 500-1000 bar

Science.gov (United States)

Zotov, A. V.; Tagirov, B. R.; Koroleva, L. A.; Volchenkova, V. A.

2017-09-01

The coupled solubility of Au(cr) and Pt(cr) has been measured in acidic chloride solutions at 350-450°C and 0.5 and 1 kb using the autoclave technique with determination of dissolved metal contents after quenching. The constants of the reaction combining the dominant species of Au and Pt in high-temperature hydrothermal fluids ( K (Au-Pt)) have been determined: 2 Au(cr) + PtCl4 2- = Pt(cr) + 2AuCl2 -; log K (Au-Pt) =-1.02 ± 0.25 (450°C, 1 kb), 0.09 ± 0.15 (450°C, 0.5 kb), and -1.31 ± 0.20 (350°C, 1 kb). It has been established that the factors affecting the Au/Pt concentration ratio in hydrothermal fluids and precipitated ores are temperature, pressure, redox potential, and sulfur fugacity. An increase in temperature results in an increase in the Au/Pt concentration ratio (up to 550°C at P = 1 kb). A decrease in pressure and redox potential leads to enrichment of fluid in Au. An increase in sulfur fugacity in the stability field of Pt sulfides results in increase in the Au/Pt concentration ratio. Native platinum is replaced by sulfide mineral in low-temperature systems enriched in Pt (relative to Au).

Synthesis of zinc aluminate with high surface area by microwave hydrothermal method applied in the transesterification of soybean oil (biodiesel)

Energy Technology Data Exchange (ETDEWEB)

Quirino, M.R. [Chemistry Laboratory of Federal University of Paraiba (LABQUIM), Campus III, 58200-000 Bananeiras, PB (Brazil); Oliveira, M.J.C. [Academic Unit of Materials Engineering, UFCG, Campina Grande Campus I, 58429-900 Campina Grande, PB (Brazil); Keyson, D. [Laboratory of study in Science, DME, Federal University of Paraíba, Campus I, 58051-900 João Pessoa, PB (Brazil); Lucena, G.L., E-mail: guilherme_leo1@yahoo.com.br [Chemistry Laboratory of Federal University of Paraiba (LABQUIM), Campus III, 58200-000 Bananeiras, PB (Brazil); Oliveira, J.B.L. [Federal University of Rio Grande do Norte, UFRN, Campus I, 59078-970 Natal, RN (Brazil); Gama, L. [Academic Unit of Materials Engineering, UFCG, Campina Grande Campus I, 58429-900 Campina Grande, PB (Brazil)

2016-02-15

Highlights: • ZnAl{sub 2}O{sub 4} spinel was synthesized by the microwave hydrothermal method in only 15 or 30 min. • The powders show high specific surface area. • ZAT{sub b}15 showed activity of 52.22% for the conversion of soybean oil into biodiesel. - Abstract: Zinc aluminate is a material with high thermal stability and high mechanical strength that, owing to these properties, is used as a catalyst or support. In this work, zinc aluminate spinel was synthesized by the microwave hydrothermal method in only 15 or 30 min at a low temperature (150 °C) without templates, using only Al(NO{sub 3}){sub 3}·9H{sub 2}O, Zn(NO{sub 3}){sub 2}·6H{sub 2}O, and urea as precursors and applied in the transesterification of soybean oil. X-ray diffraction analysis showed that ZnAl{sub 2}O{sub 4} had a cubic structure without secondary phases. The nitrogen adsorption measurements (BET) revealed a high surface area (266.57 m{sup 2} g{sup −1}) for the nanopowder synthesized in 15 min. This powder showed activity of 52.22% for the catalytic conversion of soybean oil into biodiesel by transesterification.

Deuterium high pressure target

International Nuclear Information System (INIS)

Perevozchikov, V.V.; Yukhimchuk, A.A.; Vinogradov, Yu.I.

2001-01-01

The design of the deuterium high-pressure target is presented. The target having volume of 76 cm 3 serves to provide the experimental research of muon catalyzed fusion reactions in ultra-pure deuterium in the temperature range 80-800 K under pressures of up to 150 MPa. The operation of the main systems of the target is described: generation and purification of deuterium gas, refrigeration, heating, evacuation, automated control system and data collection system

Hydrothermal-synthesized NiO nanowall array for lithium ion batteries

International Nuclear Information System (INIS)

Yan, Xiaoyan; Tong, Xili; Wang, Jian; Gong, Changwei; Zhang, Mingang; Liang, Liping

2013-01-01

Graphical abstract: Freestanding NiO nanowall array is prepared via a hydrothermal synthesis method and shows noticeable Li battery performance with good cycle life and high capacity. Highlights: ► NiO nanowall array is prepared by a hydrothermal synthesis method. ► NiO nanowall array with high capacity as anode material for Li ion battery. ► Nanowall array structure is favorable for fast ion/electron transfer. -- Abstract: We report a self-supported NiO nanowall array prepared by a facile hydrothermal synthesis method. The microstructure and morphology of the sample are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The hydrothermal-synthesized NiO nanowalls with thicknesses of ∼20 nm arrange vertically to the substrate forming a net-like nanowall array structure. As anode material for lithium ion batteries, the NiO nanowall array exhibits better electrochemical performances with higher coulombic efficiency and better cycling performance as compared to the dense NiO film. The NiO nanowall array shows an initial coulombic efficiency of 76%, as well as good cycling stability with a capacity of 567 mAh g −1 at 0.3 A g −1 after 50 cycles, higher than those of the dense polycrystalline NiO film (361 mAh g −1 ). The superior electrochemical performance is mainly due to the unique nanowall array structure with shorter diffusion length for mass and charge transport

High-pressure oxidation of ethane

DEFF Research Database (Denmark)

Hashemi, Hamid; G. Jacobsen, Jon; Rasmussen, Christian T.

2017-01-01

Ethane oxidation at intermediate temperatures and high pressures has been investigated in both a laminar flow reactor and a rapid compression machine (RCM). The flow-reactor measurements at 600–900 K and 20–100 bar showed an onset temperature for oxidation of ethane between 700 and 825 K, depending...... on pressure, stoichiometry, and residence time. Measured ignition delay times in the RCM at pressures of 10–80 bar and temperatures of 900–1025 K decreased with increasing pressure and/or temperature. A detailed chemical kinetic model was developed with particular attention to the peroxide chemistry. Rate...

Developments in the monitoring and control of Eh and pH conditions in hydrothermal experiments

International Nuclear Information System (INIS)

Myers, J.; Ulmer, G.C.; Grandstaff, D.E.; Brozdowski, R.; Danielson, M.J.; Koski, O.H.

1984-01-01

In the design of a high-level nuclear waste repository it is essential to obtain accurate groundwater Eh-pH data. Design considerations such as the choice of matrix for the waste form, type and dimensions of canister material, use of buffers, and type and amount of backfill would all benefit from an exact knowledge of oxidation potentials (Eh) and acidity levels (pH) of the groundwater. The Basalt Waste Isolation Project (BWIP) has initiated a research effort to develop sensors which can be mounted in autoclaves to provide constant monitoring of the Eh-pH conditions that exist during waste form/barrier material/groundwater hydrothermal interaction tests. Sensors must withstand temperatures up to 300 0 C and pressures up to 300 bars. This report considers Teflon hydrogen diffusion membranes and zirconia pH sensors. The development of these sensors represents a significant advance in the environmental monitoring of Eh and pH conditions at elevated temperatures and pressures

Controllable hydrothermal synthesis of Ni/H-BEA with a hierarchical core-shell structure and highly enhanced biomass hydrodeoxygenation performance.

Science.gov (United States)

Ma, Bing; Cui, Huimei; Wang, Darui; Wu, Peng; Zhao, Chen

2017-05-11

Ni based catalysts are wildly used in catalytic industrial processes due to their low costs and high activities. The design of highly hierarchical core-shell structured Ni/HBEA is achieved using a sustainable, simple, and easy-tunable hydrothermal synthesis approach using combined NH 4 Cl and NH 3 ·H 2 O as a co-precipitation agent at 120 °C. Starting from a single-crystalline hierarchical H + -exchanged beta polymorph zeolite (HBEA), the adjustment of the precipitate conditions shows that mixed NH 4 Cl and NH 3 ·H 2 O precipitates with proper concentrations are vital in the hydrothermal synthesis for preserving a good crystalline morphology of HBEA and generating abundant highly-dispersed Ni nanoparticles (loading: 41 wt%, 5.9 ± 0.7 nm) encapsulated onto/into the support. NH 4 Cl solution without an alkali is unable to generate abundant Ni nanoparticles from Ni salts under the hydrothermal conditions, whereas NH 3 ·H 2 O seriously damages the pore structure. After studying the in situ changes in infrared, X-ray diffractometry, temperature-programmed reduction, and scanning electron microscopy measurements, as well as variations in the filtrate pH, Si/Al ratios, and solid sample Ni loading, a two-step dissolution-recrystallization process is proposed. The process consists of Si dissolution and no change in elemental Al, and after the dissolved Si(iv) concentrations have promoted Ni phyllosilicate nanosheet solubility, further growth of multilayered Ni phyllosilicate nanosheets commences. The precursor Ni phyllosilicate is changeable between Ni 3 Si 2 O 5 (OH) 4 and Ni 3 Si 4 O 10 (OH) 2 , because of competition in kinetically-favored and thermodynamically-controlled species caused by different basic agents. The superior catalytic performance is demonstrated in the metal/acid catalyzed biomass derived bulky stearic acid hydrodeoxygenation with 90% octadecane selectivity and a promising rate of 54 g g -1 h -1 , which highly excels the reported rates catalyzed by

Stable isotopic and mineralogical studies of hydrothermal alteration at Arima Spa, Southwest Japan

International Nuclear Information System (INIS)

Masuda, Harue; Osaka City Univ.; Sakai, Hitoshi; Chiba, Hitoshi; Matsuhisa, Yukihiro; Nakamura, Takeshi

1986-01-01

The waters of Arima Spa, Southwest Japan, have high salinity (Cl = 54 g/kg) and high isotopic ratios (deltaD = -32, and delta 18 O = +10 per mille), and issue from shallow wells drilled into altered rhyolitic pyroclastic rocks of Cretaceous age. Alteration of the host rocks occurred in two stages. The earlier regional alteration stage is characterized by the presence of 2M- and 1M-type muscovite, albite, chlorite, calcite and epidote, whereas muscovite and Fe-chlorite formation at the expense of partly albitized plagioclase and altered biotite or hornblende occurred in the following hydrothermal stage. Pyrite, sphalerite, galena and siderite are present in the central part of the hydrothermal alteration zone. Oxygen and hydrogen isotopic ratios of secondary muscovite show that regional alteration proceeded under the meteoric circulation, and that the hydrothermal fluid for the second stage had chemical and stable isotopic characteristics of non-meteoric origin similar to the present-day Arima brine. The oxygen and to a lesser extent the hydrogen isotopic ratios of the muscovite rapidly decrease with increasing distance from the central zone of hydrothermal alteration. The isotopic variation is best interpreted as reflecting rapidly decreasing fluid/rock ratios with increasing distance of fluid penetration from the narrow hydrothermal alteration zone into the surrounding area. The results are discussed. (author)

Preparation high photocatalytic activity of CdS/halloysite nanotubes (HNTs) nanocomposites with hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Xing Weinan [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Ni Liang, E-mail: xingweinan3@126.com [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Huo Pengwei; Lu Ziyang; Liu Xinlin; Luo Yingying; Yan Yongsheng [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

2012-10-15

Highlights: Black-Right-Pointing-Pointer CdS/halloysite nanotubes (HNTs) were synthesized by hydrothermal method. Black-Right-Pointing-Pointer The CdS/HNTs had better photocatalytic activity for degradation of tetracycline. Black-Right-Pointing-Pointer The presence of halloysite nanotubes both improved its photocatalytic activity and stability. - Abstract: A novel nanocatalyst CdS/halloysite nanotubes (HNTs) was synthesized by hydrothermal method with direct growth of CdS nanoparticles on the surface of HNTs. The as-prepared photocatalysts had been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis DRS), Fourier transform infrared (FT-IR) and the thermo gravimetric analysis (TGA). The photocatalytic activity of the sample was evaluated by the degradation of tetracycline (TC) under visible light irradiation. Benefit from the excellent properties of CdS and HNTs, the photocatalyst exhibited good photocatalytic activity and stability. In order to find out the optimum synthesis condition to obtain the best photocatalytic activity, a series of experiments were performed with different CdS loading capacity, different sources of sulfide and different hydrothermal temperatures, etc. The best photodegradation rate could reach 93% in 60 min under visible light irradiation. Therefore, the combination of CdS nanoparticles with HNTs endowed this material with a potential use in environmental treatments in industries.

Preparation high photocatalytic activity of CdS/halloysite nanotubes (HNTs) nanocomposites with hydrothermal method

International Nuclear Information System (INIS)

Xing Weinan; Ni Liang; Huo Pengwei; Lu Ziyang; Liu Xinlin; Luo Yingying; Yan Yongsheng

2012-01-01

Highlights: ► CdS/halloysite nanotubes (HNTs) were synthesized by hydrothermal method. ► The CdS/HNTs had better photocatalytic activity for degradation of tetracycline. ► The presence of halloysite nanotubes both improved its photocatalytic activity and stability. - Abstract: A novel nanocatalyst CdS/halloysite nanotubes (HNTs) was synthesized by hydrothermal method with direct growth of CdS nanoparticles on the surface of HNTs. The as-prepared photocatalysts had been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (UV–vis DRS), Fourier transform infrared (FT-IR) and the thermo gravimetric analysis (TGA). The photocatalytic activity of the sample was evaluated by the degradation of tetracycline (TC) under visible light irradiation. Benefit from the excellent properties of CdS and HNTs, the photocatalyst exhibited good photocatalytic activity and stability. In order to find out the optimum synthesis condition to obtain the best photocatalytic activity, a series of experiments were performed with different CdS loading capacity, different sources of sulfide and different hydrothermal temperatures, etc. The best photodegradation rate could reach 93% in 60 min under visible light irradiation. Therefore, the combination of CdS nanoparticles with HNTs endowed this material with a potential use in environmental treatments in industries.

Novel thermosyphon driven hydrothermal flow-through cell for in situ and time resolved neutron diffraction studies

International Nuclear Information System (INIS)

Xia, Fang; Qian, Gujie; Etschmann, Barbara; University of Adelaide, South Australia, Australia; University of Adelaide, South Australia, Australia; Studer, Andrew; Olsen, Scott

2009-01-01

Full text: A flow-through cell for hydrothermal phase transformation studies by in situ and time-resolved neutron diffraction has been designed and constructed. The cell has a large internal volume of 320 m L and can work at up to 300 degree Centigrade under autogeneous vapour pressures (-85 bar). The fluid flow is driven by thermosyphon which is realized by the proper design of temperature difference around the closed loop[1,2). The main body of the cell is made of stainless steel (316 type), but the sample compartment is constructed from non-scattering Ti/Zr alloy. We have successfully commissioned the cell on Australia's new high intensity powder diffractometer WOMBAT in ANSTO, using a simple transformation reaction from leucite (KAISi 2 O 6 ) to analcime (NaAISi 2 O 6H2O ) and then back from analcime to leucite. The demonstration proved that the cell is an excellent tool for probing hydrothermal phase transformations. By collecting diffraction data every 5 min, it was clearly seen that leucite was progressively transformed to analcime in a NaCI solution, and the produced analcime was progressively transformed back to leucite in a K 2 CO 3 solution.

High pressure-elevated temperature x-ray micro-computed tomography for subsurface applications.

Science.gov (United States)

Iglauer, Stefan; Lebedev, Maxim

2018-06-01

Physical, chemical and mechanical pore-scale (i.e. micrometer-scale) mechanisms in rock are of key importance in many, if not all, subsurface processes. These processes are highly relevant in various applications, e.g. hydrocarbon recovery, CO 2 geo-sequestration, geophysical exploration, water production, geothermal energy production, or the prediction of the location of valuable hydrothermal deposits. Typical examples are multi-phase flow (e.g. oil and water) displacements driven by buoyancy, viscous or capillary forces, mineral-fluid interactions (e.g. mineral dissolution and/or precipitation over geological times), geo-mechanical rock behaviour (e.g. rock compaction during diagenesis) or fines migration during water production, which can dramatically reduce reservoir permeability (and thus reservoir performance). All above examples are 3D processes, and 2D experiments (as traditionally done for micro-scale investigations) will thus only provide qualitative information; for instance the percolation threshold is much lower in 3D than in 2D. However, with the advent of x-ray micro-computed tomography (μCT) - which is now routinely used - this limitation has been overcome, and such pore-scale processes can be observed in 3D at micrometer-scale. A serious complication is, however, the fact that in the subsurface high pressures and elevated temperatures (HPET) prevail, due to the hydrostatic and geothermal gradients imposed upon it. Such HPET-reservoir conditions significantly change the above mentioned physical and chemical processes, e.g. gas density is much higher at high pressure, which strongly affects buoyancy and wettability and thus gas distributions in the subsurface; or chemical reactions are significantly accelerated at increased temperature, strongly affecting fluid-rock interactions and thus diagenesis and deposition of valuable minerals. It is thus necessary to apply HPET conditions to the aforementioned μCT experiments, to be able to mimic subsurface

Hydrothermal Synthesis of Highly Water-dispersible Anatase Nanoparticles with Large Specific Surface Area and Their Adsorptive Properties

OpenAIRE

Hu Xueting; Zhang Dongyun; Zhao Siqin; Asuha Sin

2016-01-01

Highly water-dispersible and very small TiO2 nanoparticles (~3 nm anatase) with large specific surface area have been synthesized by hydrolysis and hydrothermal reactions of titanium butoxide and used for the removal of three azo dyes (Congo red, orange II, and methyl orange) with different molecular structure from simulated wastewaters. The synthesized TiO2 nanoparticles are well dispersed in water with large specific surface area up to 417 m2 g−1. Adsorption experiments demonstrated that th...

Hydrothermal alterations as natural analogues of radionuclide migration in granitic rocks

International Nuclear Information System (INIS)

Piantone, P.

1989-01-01

The document is the final report of the project Hydrothermal alteration systems as analogues of nuclear waste repositories in granitic rocks which was the subject of contract n 0 F1 1 W/0072-F (CD) performed at shared cost between the Bureau de Recherches Geologiques et Minieres (BRGM), the Commissariat a l'Energie Atomique and the Commission of the European Communities as part of the MIRAGE programme. This study is the continuation of a preliminary study made by BRGM in 1986 and which concerned the same programme. The data given in this report were obtained from the study of the infilling and hydrothermalized walls of a mineralized vein located at Fombillou, Lot Department, in the French Massif Central. A satisfactory model of the processes generated by hydrothermal alteration then by climatic weathering such as formation of new minerals, flow of elements and variations in volume, was thus built. The mobility of elements displaying physical and chemical properties similar to those of radionuclides present in high-level radioactive waste was studied. A preliminary thermodynamic simulation of mineral transformations and transfers of matter during hydrothermal alteration was performed using the calculation code CEQCSY (Chemical EQuilibrium in Complex SYstem). This simulation is based on the values of the main physical and chemical parameters deduced from the analysis of the natural system. On the basis of the results obtained from Fombillou, an appraisal was made of the response of the granitic environment which has been disturbed by a hydrothermal system produced by heat emitted by the storage of high-level radio-active waste as well as its potential capacities of retention in case of possible leakage

In-pile Hydrothermal Corrosion Evaluation of Coated SiC Ceramics and Composites

Energy Technology Data Exchange (ETDEWEB)

Carpenter, David [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Ang, Caen [Univ. of Tennessee, Knoxville, TN (United States); Katoh, Yutai [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Linton, Kory D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-09-01

Hydrothermal corrosion accelerated by water radiolysis during normal operation is among the most critical technical feasibility issues remaining for silicon carbide (SiC) composite-based cladding that could provide enhanced accident-tolerance fuel technology for light water reactors. An integrated in-pile test was developed and performed to determine the synergistic effects of neutron irradiation, radiolysis, and pressurized water flow, all of which are relevant to a typical pressurized water reactor (PWR). The test specimens were chosen to cover a range of SiC materials and a variety of potential options for environmental barrier coatings. This document provides a summary of the irradiation vehicle design, operations of the experiment, and the specimen loading into the irradiation vehicle.

Effect of hydrothermal treatment on some properties of Shenhua coal

Energy Technology Data Exchange (ETDEWEB)

Wang Zhi-cai; Shui Heng-fu; Zhang De-xiang; Gao Jin-sheng [East China University of Science and Technology, Shanghai (China). College of Resource and Environmental Engineering

2006-10-15

Effects of hydrothermal treatment on swelling, extraction and liquefaction behavior of Shenhua coal were studied through analyses of element content, ash content, volatile content and IR spectrum of treated coal. The results indicate that hydrogenation of coal is distinctly carried out in the process of hydrothermal pre-treatment and the hydrogen content of treated coal is more than that of raw coal. The contents of ash and volatile matters of treated coal are lower than those of raw coal. With the increase of treatment temperature the volatile content of the hydrothermal treated coal decreases and the ash content of treated coal increases. CO{sub 2} is main gas product and unvaries with the temperature changing, whereas CO and CH{sub 4} are formed when the temperature is above 250{sup o}C and increase with the temperature during hydrothermal treatment. Hydrothermal treatment is not in favor of coal swelling and the swelling ratio of treated coal decreases with the increase of treatment temperature. The swelling ratio of extraction residue by CS{sub 2}/NMP mixed solvent in NMP solvent is lower than that of the corresponding raw coal. The CS{sub 2}/NMP mixed solvent extraction yields of coal treated at appropriate temperature are higher than that of raw coal, but the extraction yields of treated coal obtained by n-hexane, toluene and THF successive Soxhelt extraction are lower. Hydrothermal treatment at 250-300{sup o}C can increase the conversion of treated coal in direct hydro-liquefaction. The gas + oil yield of treated coal is lower than that of raw coal and the preasphaltene yield of treated coal is much higher. IR spectra of treated coals show that the forms of non-covalent bonds are changed by hydrothermal treatment, and the hydrolysis of ester and ether bonds and the pyrolysis of aromatic side chains also maybe occur at high treatment temperature. 21 refs., 3 figs., 4 tabs.

Energy Systems High-Pressure Test Laboratory | Energy Systems Integration

Science.gov (United States)

Facility | NREL Energy Systems High-Pressure Test Laboratory Energy Systems High-Pressure Test Laboratory In the Energy Systems Integration Facility's High-Pressure Test Laboratory, researchers can safely test high-pressure hydrogen components. Photo of researchers running an experiment with a hydrogen fuel

HIGH BLOOD PRESSURE: DOES THIS CONCERN ME?

CERN Multimedia

2007-01-01

To find out, the Medical Service's nurses are organising A HIGH BLOOD PRESSURE SCREENING AND PREVENTION CAMPAIGN from Monday, 26th to Thursday, 29th March 2007 at the Infirmary - Building 57 - ground floor A blood pressure test, advice, information and, if necessary, referral for specialist medical treatment will be offered to any person working on the CERN site. High blood pressure is a silent threat to health. So come and get your blood pressure checked.

HIGH BLOOD PRESSURE: DOES THIS CONCERN ME?

CERN Multimedia

2007-01-01

To find out, the Medical Service's nurses are organising A HIGH BLOOD PRESSURE SCREENING AND PREVENTION CAMPAIGN from Monday, 26th to Thursday, 29th March 2007 at the Infirmary - Building 57 - ground floor A blood pressure test, advice, information and, if necessary, referral for specialist medical treatment will be offered to any person working on the CERN site. High blood pressure is a stealth threat to health. So come and get your blood pressure checked.

Raman spectroscopy of triolein under high pressures

Science.gov (United States)

Tefelski, D. B.; Jastrzębski, C.; Wierzbicki, M.; Siegoczyński, R. M.; Rostocki, A. J.; Wieja, K.; Kościesza, R.

2010-03-01

This article presents results of the high pressure Raman spectroscopy of triolein. Triolein, a triacylglyceride (TAG) of oleic acid, is an unsaturated fat, present in natural oils such as olive oil. As a basic food component and an energy storage molecule, it has considerable importance for food and fuel industries. To generate pressure in the experiment, we used a high-pressure cylindrical chamber with sapphire windows, presented in (R.M. Siegoczyński, R. Kościesza, D.B. Tefelski, and A. Kos, Molecular collapse - modification of the liquid structure induced by pressure in oleic acid, High Press. Res. 29 (2009), pp. 61-66). Pressure up to 750 MPa was applied. A Raman spectrometer in "macro"-configuration was employed. Raman spectroscopy provides information on changes of vibrational modes related to structural changes of triolein under pressure. Interesting changes in the triglyceride C‒H stretching region at 2650-3100 cm-1 were observed under high-pressures. Changes were also observed in the ester carbonyl (C˭ O) stretching region 1700-1780 cm-1 and the C‒C stretching region at 1050-1150 cm-1. The overall luminescence of the sample decreased under pressure, making it possible to set longer spectrum acquisition time and obtain more details of the spectrum. The registered changes suggest that the high-pressure solid phase of triolein is organized as β-polymorphic, as was reported in (C. Akita, T. Kawaguchi, and F. Kaneko, Structural study on polymorphism of cis-unsaturated triacylglycerol: Triolein, J. Phys. Chem. B 110 (2006), pp. 4346-4353; E. Da Silva and D. Rousseau, Molecular order and thermodynamics of the solid-liquid transition in triglycerides via Raman spectroscopy, Phys. Chem. Chem. Phys. 10 (2008), pp. 4606-4613) (with temperature-induced phase transitions). The research has shown that Raman spectroscopy in TAGs under pressure reveals useful information about its structural changes.

Understanding the Compositional Variability of the Major Components of Hydrothermal Plumes in the Okinawa Trough

Directory of Open Access Journals (Sweden)

Zhigang Zeng

2018-01-01

Full Text Available Studies of the major components of hydrothermal plumes in seafloor hydrothermal fields are critical for an improved understanding of biogeochemical cycles and the large-scale distribution of elements in the submarine environment. The composition of major components in hydrothermal plume water column samples from 25 stations has been investigated in the middle and southern Okinawa Trough. The physical and chemical properties of hydrothermal plume water in the Okinawa Trough have been affected by input of the Kuroshio current, and its influence on hydrothermal plume water from the southern Okinawa Trough to the middle Okinawa Trough is reduced. The anomalous layers of seawater in the hydrothermal plume water columns have higher K+, Ca2+, Mn2+, B3+, Ca2+/SO42-, and Mn2+/Mg2+ ratios and higher optical anomalies than other layers. The Mg2+, SO42-, Mg2+/Ca2+, and SO42-/Mn2+ ratios of the anomalous layers are lower than other layers in the hydrothermal plume water columns and are consistent with concentrations in hydrothermal vent fluids in the Okinawa Trough. This suggests that the chemical variations of hydrothermal plumes in the Tangyin hydrothermal field, like other hydrothermal fields, result in the discharge of high K+, Ca2+, and B3+ and low Mg2+ and SO42- fluid. Furthermore, element ratios (e.g., Sr2+/Ca2+, Ca2+/Cl− in hydrothermal plume water columns were found to be similar to those in average seawater, indicating that Sr2+/Ca2+ and Ca2+/Cl− ratios of hydrothermal plumes might be useful proxies for chemical properties of seawater. The hydrothermal K+, Ca2+, Mn2+, and B3+ flux to seawater in the Okinawa Trough is about 2.62–873, 1.04–326, 1.30–76.4, and 0.293–34.7 × 106 kg per year, respectively. The heat flux is about 0.159–1,973 × 105 W, which means that roughly 0.0006% of ocean heat is supplied by seafloor hydrothermal plumes in the Okinawa Trough.

Submarine Hydrothermal Activity and Gold-Rich Mineralization at Brothers Volcano, Southern Kermadec Arc, New Zealand

Science.gov (United States)

de Ronde, C. E.; Massoth, G. J.; Christenson, B. W.; Butterfield, D. A.; Ishibashi, J.; Hannington, M. D.; Ditchburn, B. G.; Embley, R. W.; Lupton, J. E.; Kamenetsky, D.; Reyes, A. G.; Lahr, J.; Takai, K.

2006-12-01

Brothers volcano is one of several hydrothermally active volcanoes that occur along the Kermadec active arc front, NE of New Zealand. It forms an elongate edifice 13 km long by 8 km across that strikes NW-SE. The volcano has a caldera with a basal diameter of ~3 km and a floor at 1,850 m below sea level, surrounded by 290 to 530 m high walls. A volcanic cone of dacite rises 350 m from the caldera floor and partially coalesces with the southern caldera wall. Three hydrothermal sites have been located; on the NW caldera wall, on the SE caldera wall, and on the dacite cone. The NW caldera vent site is a long-term hydrothermal system that is today dominated by evolved seawater but has had episodic injections of magmatic fluid. The SE caldera site represents the main upflow of a relatively well-established magmatic-hydrothermal system on the seafloor where sulfide-rich chimneys are extant. The cone site is a nascent magmatic-hydrothermal system where crack zones localize upwelling acidic waters. Each of these different vent sites represent diverse parts of an evolving hydrothermal system, any one of which may be typical of submarine volcanic arcs. Hydrothermal venting is today occurring at the NW caldera and cone sites. The former is characterized by high-temperature (up to 302°C) venting with pH down to 2.8, low Mg and SO4 values, Cl between 510 and 760 mM, elevated Si and increasing Fe and Mn values with increasing Cl concentrations, consistent with a mostly Cl-enriched endmember. By contrast, vent fluids from the cone site are gas-rich (up to 220 mM total gas), have temperatures 30 ppm) zones in some chimneys formed over a short period of time, coincident with pulses of magmatic fluid into the hydrothermal system.

Comparative analyses of the bacterial community of hydrothermal deposits and seafloor sediments across Okinawa Trough

Science.gov (United States)

Wang, Long; Yu, Min; Liu, Yan; Liu, Jiwen; Wu, Yonghua; Li, Li; Liu, Jihua; Wang, Min; Zhang, Xiao-Hua

2018-04-01

As an ideal place to study back-arc basins and hydrothermal eco-system, Okinawa Trough has attracted the interests of scientists for decades. However, there are still no in-depth studies targeting the bacterial community of the seafloor sediments and hydrothermal deposits in Okinawa Trough. In the present study, we reported the bacterial community of the surface deposits of a newly found hydrothermal field in the southern Okinawa Trough, and the horizontal and vertical variation of bacterial communities in the sediments of the northern Okinawa Trough. The hydrothermal deposits had a relatively high 16S rRNA gene abundance but low bacterial richness and diversity. Epsilonproteobacteria and Bacteroidetes were predominant in hydrothermal deposits whereas Deltaproteobacteria, Gammaproteobacteria and Chloroflexi were abundant across all samples. The bacterial distribution in the seafloor of Okinawa Trough was significantly correlated to the content of total nitrogen, and had consistent relationship with total carbon. Gradual changes of sulfur-oxidizing bacteria were found with the distance away from hydrothermal fields, while the hydrothermal activity did not influence the distribution of the major clades of sulfate-reducing bacteria. Higher abundance of the sulfur cycle related genes (aprA and dsrB), and lower abundance of the bacterial ammonia-oxidizing related gene (amoA) were quantified in hydrothermal deposits. In addition, the present study also compared the inter-field variation of Epsilonproteobacteria among multi-types of hydrothermal vents, revealing that the proportion and diversity of this clade were quite various.

High temperature and high pressure equation of state of gold

International Nuclear Information System (INIS)

Matsui, Masanori

2010-01-01

High-temperature and high-pressure equation of state (EOS) of Au has been developed using measured data from shock compression up to 240 GPa, volume thermal expansion between 100 and 1300 K and 0 GPa, and temperature dependence of bulk modulus at 0 GPa from ultrasonic measurements. The lattice thermal pressures at high temperatures have been estimated based on the Mie-Grueneisen-Debye type treatment with the Vinet isothermal EOS. The contribution of electronic thermal pressure at high temperatures, which is relatively insignificant for Au, has also been included here. The optimized EOS parameters are K' 0T = 6.0 and q = 1.6 with fixed K 0T = 167 GPa, γ 0 = 2.97, and Θ 0 = 170 K from previous investigations. We propose the present EOS to be used as a reliable pressure standard for static experiments up to 3000K and 300 GPa.

High pressure apparatus for neutron scattering at low temperature

International Nuclear Information System (INIS)

Munakata, Koji; Uwatoko, Yoshiya; Aso, Naofumi

2010-01-01

Effects of pressure on the physical properties are very important for understanding highly correlated electron systems, in which pressure-induced attractive phenomena such as superconductivity and magnetically ordered non-Fermi liquid have been observed. Up to now, many scientists have developed a lot of high pressure apparatus for each purpose. The characteristic features of various materials and pressure transmitting media for use of high pressure apparatus are reported. Then, two kinds of clamp type high-pressure cell designed for low-temperature neutron diffraction measurements are shown; one is a piston cylinder type high-pressure cell which can be attached to the dilution refrigerator, and the other one is a newly-developed cubic anvil type high-pressure cell which can generate pressure above 7GPa. We also introduce the results of magnetic neutron scattering under pressure on a pressure-induced superconducting ferromagnet UGe 2 in use of the piston cylinder type clamp cell, and those on an iron arsenide superconductor SrFe 2 As 2 in use of the cubic anvil type clamp cell. (author)

Whole Algae Hydrothermal Liquefaction Technology Pathway

Energy Technology Data Exchange (ETDEWEB)

Biddy, M.; Davis, R.; Jones, S.

2013-03-01

This technology pathway case investigates the feasibility of using whole wet microalgae as a feedstock for conversion via hydrothermal liquefaction. Technical barriers and key research needs have been assessed in order for the hydrothermal liquefaction of microalgae to be competitive with petroleum-derived gasoline-, diesel-, and jet-range hydrocarbon blendstocks.

Evolution of interstellar organic compounds under asteroidal hydrothermal conditions

Science.gov (United States)

Vinogradoff, V.; Bernard, S.; Le Guillou, C.; Remusat, L.

2018-05-01

Carbonaceous chondrites (CC) contain a diversity of organic compounds. No definitive evidence for a genetic relationship between these complex organic molecules and the simple organic molecules detected in the interstellar medium (ISM) has yet been reported. One of the many difficulties arises from the transformations of organic compounds during accretion and hydrothermal alteration on asteroids. Here, we report results of hydrothermal alteration experiments conducted on a common constituent of interstellar ice analogs, Hexamethylenetetramine (HMT - C6H12N4). We submitted HMT to asteroidal hydrothermal conditions at 150 °C, for various durations (up to 31 days) and under alkaline pH. Organic products were characterized by gas chromatography mass spectrometry, infrared spectroscopy and synchrotron-based X-ray absorption near edge structure spectroscopy. Results show that, within a few days, HMT has evolved into (1) a very diverse suite of soluble compounds dominated by N-bearing aromatic compounds (> 150 species after 31 days), including for instance formamide, pyridine, pyrrole and their polymers (2) an aromatic and N-rich insoluble material that forms after only 7 days of experiment and then remains stable through time. The reaction pathways leading to the soluble compounds likely include HMT dissociation, formose and Maillard-type reactions, e.g. reactions of sugar derivatives with amines. The present study demonstrates that, if interstellar organic compounds such as HMT had been accreted by chondrite parent bodies, they would have undergone chemical transformations during hydrothermal alteration, potentially leading to the formation of high molecular weight insoluble organic molecules. Some of the diversity of soluble and insoluble organic compounds found in CC may thus result from asteroidal hydrothermal alteration.

Formation of hydrothermal tin deposits: Raman spectroscopic evidence for an important role of aqueous Sn(IV) species

Science.gov (United States)

Schmidt, Christian

2018-01-01

The speciation of tin and the solubility of cassiterite in H2O + HCl were determined at temperatures to 600 °C using in situ Raman spectroscopy. In addition, information on the fluid-melt partition of Sn was obtained at 700 °C and indicated a preference of the fluid only at HCl concentrations that are much higher than in fluids exsolved from natural felsic melts. Dissolution of cassiterite generally resulted in formation of Sn(IV) species unless reduced conditions were generated by hydrogen permeation or carbohydrates in the starting material. The prevalent aqueous Sn(IV) species was [SnCl4(H2O)2]0, with additional [SnCl3(H2O)3]+ and [SnCl5(H2O)]-. The only detectable Sn(II) species was very likely [Sn(II)Cl3]-. Cassiterite solubility increased with HCl concentration and was generally high in H2O+HCl fluids, with no strong dependencies on temperature, pressure, or the oxidation state of tin in the fluid. The Sn(IV) concentrations at 500 and 600 °C determined from the integrated ν1[Sn(IV)sbnd Cl] band intensity are in good agreement with literature data on the cassiterite solubility in H2O + HCl at oxygen fugacities along the hematite-magnetite buffer. The combined results from previous experimental studies and this study demonstrate that HCl molality is a crucial parameter for hydrothermal mobilization and transport of tin and for cassiterite precipitation, and that pH, pressure and temperature are less important. Current models on hydrothermal tin deposit formation need to be augmented to include Sn(IV)sbnd Cl complexes as significant tin-transporting species. Irrespective of the oxidation state of tin in the fluid, cassiterite precipitates due to reaction of the hydrothermal fluid with the wall rock (greisen or skarn formation), dilution (mixing with meteoric water) or a decrease in the HCl activity in the aqueous liquid by boiling. A redox reaction is only required for tin transported as Sn(II) to be converted to Sn(IV).

7 CFR 58.219 - High pressure pumps and lines.

Science.gov (United States)

2010-01-01

... 7 Agriculture 3 2010-01-01 2010-01-01 false High pressure pumps and lines. 58.219 Section 58.219....219 High pressure pumps and lines. High pressure lines may be cleaned-in-place and shall be of such construction that dead ends, valves and the high pressure pumps can be disassembled for hand cleaning. The high...

Nuclide separation by hydrothermal treatment and ion exchange: a highly effective method for treatment of liquid effluents - 59217

International Nuclear Information System (INIS)

Braehler, Georg; Rieck, Ronald; Avramenko, V.A.; Sergienko, V.I.; Antonov, E.A.

2012-01-01

Liquid low level radioactive effluents, when solidified in e.g. cement matrix, contribute to a significant extent to the waste amount to be disposed of in final repositories. Accordingly, since many years scientists and engineers investigate processes to remove the radioactive nuclides selectively from the effluents, to split the raw solution into two separate fractions: a large fraction with activity concentrations below the limits for free release; and a small fraction, containing the activity in concentrated form on e. g. ion exchanger materials (ion exchange has proven to be the most promising method for such 'nuclide separation'). The challenge to be taken up is: When (and this is most often the case) the effluent contains organic materials and complexing agents, the formation of e. g. the 60-Co-EDTA complex prohibits its fixation to the ion exchangers. Accordingly the complexing agent needs to be removed or destroyed. The Institute for Chemistry of the Russian Academy of Sciences has applied the method of hydrothermal treatment (at elevated temperature and pressure, 200 deg. C, 200 bar), supported by Hydrogen Peroxide oxidation, to allow virtually complete removal of radioactive nuclides on inorganic ion exchangers. Pilot plants have been operated successfully in Russian power stations, and an operational plant has been designed. The method is being extended for an interesting and promising application: spent organic ion exchange resins, loaded up to the medium activity level, represent a serious disposal problem. With the hydrothermal process, in a process cycle, the activity can be stripped from the resins, the organic content is destroyed, and the activity is fixed on an inorganic absorber, well suited for final disposal. (authors)

Fluorinert as a pressure-transmitting medium for high-pressure diffraction studies

International Nuclear Information System (INIS)

Varga, Tamas; Wilkinson, Angus P.; Angel, Ross J.

2003-01-01

Fluorinert is a liquid pressure-transmitting medium that is widely used in high-pressure diffraction work. A systematic study of five different fluorinerts was carried out using single-crystal x-ray diffraction in a diamond-anvil cell in order to determine the pressure range over which they provide a hydrostatic stress state to the sample. It was found that none of the fluorinerts studied can be considered hydrostatic above 1.2 GPa, a lower pressure than reported previously

Thermodynamic relations in high temperature and high pressure physics of solids

International Nuclear Information System (INIS)

Kumar, Munish

1998-01-01

Various possible simple relations based on the exact and approximate thermodynamic relations are derived. These relations can be used to investigate the variation of unit cell volume under the effect of pressure and temperature. Thermal expansivity and compressibility can be investigated directly at any pressure or temperature, or through the knowledge of equation of state (EOS). A relation to determine Anderson-Grueneisen parameter δ T under the effect of pressure is predicted. It is discussed that δ T is independent of pressure and thus Murnaghan equation of state works well in low pressure ranges, while the variation of δ T under high pressure should be taken into account. The product of coefficient of volume thermal expansion and bulk modulus remains constant, is correct at high pressure, provided that the pressure dependence of δ T is considered. (author)

Nb effect on Zr-alloy oxidation under high pressure steam at high temperatures

International Nuclear Information System (INIS)

Park, Kwangheon; Yang, Sungwoo; Kim, Kyutae

2005-01-01

The high-pressure steam effects on the oxidation of Zircaloy-4 (Zry-4) and Zirlo (Zry-1%Nb) claddings at high temperature have been analyzed. Test temperature range was 700-900degC, and pressures were 1-150 bars. High pressure-steam enhances oxidation of Zry-4, and the dependency of enhancement looks exponential to steam pressure. The origin of the oxidation enhancement turned out to be the formation of cracks in oxide. The loss of tetragonal phase by high-pressure steam seems related to the crack formation. Addition of Nb as an alloying element to Zr alloy reduces significantly the steam pressure effects on oxidation. The higher compressive stresses and the smaller fraction of tetragonal oxides in Zry-1%Nb seem to be the diminished effect of high-pressure steam on oxidation. (author)

High-pressure differential scanning microcalorimeter.

Science.gov (United States)

Senin, A A; Dzhavadov, L N; Potekhin, S A

2016-03-01

A differential scanning microcalorimeter for studying thermotropic conformational transitions of biopolymers at high pressure has been designed. The calorimeter allows taking measurements of partial heat capacity of biopolymer solutions vs. temperature at pressures up to 3000 atm. The principles of operation of the device, methods of its calibration, as well as possible applications are discussed.

Hydrothermal treatment of municipal solid waste incineration fly ash for dioxin decomposition

International Nuclear Information System (INIS)

Hu, Yuyan; Zhang, Pengfei; Chen, Dezhen; Zhou, Bin; Li, Jianyi; Li, Xian-wei

2012-01-01

Highlights: ► The first study to apply Fe-sulfate in hydrothermal treatment of municipal solid waste incineration fly ash for dioxin decomposition. ► The first study to comprehensively evaluate the effect of hydrothermal treatment on dioxin decomposition and heavy metal stabilization in municipal solid waste incineration fly ash. ► Gaussian software chemical computational simulation was performed to investigate the mechanism of dioxin decomposition based on quantum chemistry calculation, and to support the experimental data by the calculation results. - Abstract: Hydrothermal treatment of MSWI fly ash was performed in this paper with a purpose to reduce its dioxin content. First a hydrothermal reactor was set up with a mixture of ferric sulphate and ferrous sulphate serviced as the reactant, then the effects caused by reaction conditions such as reaction temperature, pre-treatment by water-washing and reactant dosage were checked; the results showed that as a promising technology, hydrothermal treatment exhibited considerable high efficiencies in decomposition of PCDDs/PCDFs and good stabilization of heavy metals as well. Experimental results also showed that for dioxin destruction, higher reaction temperature is the most important influencing factor followed by Fe addition, and pre-treatment of raw fly ash by water-washing increased the destruction efficiencies of dioxins only very slightly. Finally with help of Gaussian software chemical computational simulation was performed to investigate the mechanism of dioxin decomposition based on quantum chemistry calculation. The calculation results were supported by the experimental data. The leaching toxicities of hydrothermal products were higher than upper limits defined in the latest Chinese standard GB 16889-2008 for sanitary landfill disposal, thus an auxiliary process is suggested after the hydrothermal treatment for heavy metal stabilization.

30 CFR 56.13021 - High-pressure hose connections.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-pressure hose connections. 56.13021... and Boilers § 56.13021 High-pressure hose connections. Except where automatic shutoff valves are used, safety chains or other suitable locking devices shall be used at connections to machines of high-pressure...

In situ analysis of proteins at high temperatures mediated by capillary-flow hydrothermal UV-vis spectrophotometer with a water-soluble chromogenic reagent.

Science.gov (United States)

Kawamura, Kunio; Nagayoshi, Hiroki; Yao, Toshio

2010-05-14

In situ monitoring of quantities, interactions, and conformations of proteins is essential for the study of biochemistry under hydrothermal environments and the analysis of hyperthermophilic organisms in natural hydrothermal systems on Earth. We have investigated the potential of a capillary-flow hydrothermal UV-vis spectrophotometer (CHUS) for performing in situ measurements of proteins and determining their behavior at extremely high temperatures, in combination with a chromogenic reagents probe, which interacts with the proteins. The spectral shift obtained using a combination of water-soluble porphyrin (TPPS) and bovine serum albumin (BSA) was the best among the spectral shifts obtained using different combinations of chromogenic reagents and proteins. The association behavior of TPPS with BSA was investigated in detail using CHUS at temperatures up to 175 degrees C and the association constant (K(ass)) of TPPS with BSA was successfully determined at temperatures up to 100 degrees C. The lnK(ass) values were inversely proportional to the T(-1) values in the temperature range 50-100 degrees C. These analyses showed for the first time that the decrease of association of TPPS with BSA is due to the conformational change, fragmentation, and/or denaturing of BSA rather than the decrease of the hydrophobic association between TPPS and BSA. This study conclusively demonstrates the usability of the CHUS system with a chromogenic reagent as an in situ detection and measurement system for thermostable proteins at extremely high temperatures. Copyright 2010 Elsevier B.V. All rights reserved.

To the probe theory in a highly-ionized high-pressure plasma

International Nuclear Information System (INIS)

Baksht, F.G.; Rybakov, A.B.

1997-01-01

The probe theory in highly-ionized high-pressure plasma is presented. The situation typical for high-pressure plasma, when the plasma in the main part of the near-probe layer is in the state of local ionization equilibrium with general temperature for electrons and heavy particles. Possibility is discussed for determining the parameters of non-perturbed plasma through analysis of the probe characteristic at place of ion saturation, transition area and by the probe floating potential. The experiments were carried out by example of highly-ionized xenon plasma under atmospheric pressure

Evaluation of lime and hydrothermal pretreatments for efficient enzymatic hydrolysis of raw sugarcane bagasse.

Science.gov (United States)

Grimaldi, Maira Prearo; Marques, Marina Paganini; Laluce, Cecília; Cilli, Eduardo Maffud; Sponchiado, Sandra Regina Pombeiro

2015-01-01

Ethanol production from sugarcane bagasse requires a pretreatment step to disrupt the cellulose-hemicellulose-lignin complex and to increase biomass digestibility, thus allowing the obtaining of high yields of fermentable sugars for the subsequent fermentation. Hydrothermal and lime pretreatments have emerged as effective methods in preparing the lignocellulosic biomass for bioconversion. These pretreatments are advantageous because they can be performed under mild temperature and pressure conditions, resulting in less sugar degradation compared with other pretreatments, and also are cost-effective and environmentally sustainable. In this study, we evaluated the effect of these pretreatments on the efficiency of enzymatic hydrolysis of raw sugarcane bagasse obtained directly from mill without prior screening. In addition, we evaluated the structure and composition modifications of this bagasse after lime and hydrothermal pretreatments. The highest cellulose hydrolysis rate (70 % digestion) was obtained for raw sugarcane bagasse pretreated with lime [0.1 g Ca(OH)2/g raw] for 60 min at 120 °C compared with hydrothermally pretreated bagasse (21 % digestion) under the same time and temperature conditions. Chemical composition analyses showed that the lime pretreatment of bagasse promoted high solubilization of lignin (30 %) and hemicellulose (5 %) accompanied by a cellulose accumulation (11 %). Analysis of pretreated bagasse structure revealed that lime pretreatment caused considerable damage to the bagasse fibers, including rupture of the cell wall, exposing the cellulose-rich areas to enzymatic action. We showed that lime pretreatment is effective in improving enzymatic digestibility of raw sugarcane bagasse, even at low lime loading and over a short pretreatment period. It was also demonstrated that this pretreatment caused alterations in the structure and composition of raw bagasse, which had a pronounced effect on the enzymes accessibility to the

Magnetization at high pressure in CeP

Science.gov (United States)

Naka, T.; Matsumoto, T.; Okayama, Y.; Môri, N.; Haga, Y.; Suzuki, T.

1995-02-01

We have investigated the pressure dependence of magnetization below 60 K up to 1.6 GPa in the low-carrier concentration system CeP showing two step transitions at T = TL and TH under high pressure. At high pressure, M( P, T) exhibits a maximum at around the lower transition temperature TL. This behavior implies that the magnetic state changes at TL. The pressure dependence of isothermal magnetization M( P) is different above and below TL. In fact, M( P) below TL exhibits a maximum at around 1.4 GPa, whereas M( P) above TL increases steeply with pressure up to 1.6 GPa.

High pressure and high temperature EXAFS and diffraction study of AgI

International Nuclear Information System (INIS)

Yoshiasa, Akira; Arima, Hiroshi; Fukui, Hiroshi; Okube, Maki; Katayama, Yoshinori; Ohtaka, Osamu

2009-01-01

We have determined the precise P-T phase diagram of AgI by in-situ high-pressure high-temperature synchrotron experiments. X-ray diffraction and XAFS measurements were performed up to 6.0 GPa and 1100 K using a multi-anvil high-pressure device and synchrotron radiation from SPring-8. In the disordered rock-salt phase, Ag ions occupy both octahedral and tetrahedral sites and twenty percent of Ag ions occupy the tetrahedral site as a maximum value at 2 GPa. From the viewpoint of the local structure analyses, some sudden changes are recognized near broad phase transition point. Analysis of EXAFS Debye-Waller factor is useful because the force constant can be decided directly even at high pressure and high temperature. Pressure influences greatly the effective potential and anharmonicity decreases with increasing pressure. (author)

Trends in high pressure developments for new perspectives

Science.gov (United States)

Largeteau, Alain; Prakasam, Mythili

2018-06-01

Temperature and Pressure are two parameters in the universe, where pressure represents the largest scale in comparison to temperature. The design of high pressure equipment depends mainly on the media used which could be gas, liquid or solid and the objective could be synthesis of materials or in situ characterization. The development of new research fields requiring high pressure equipment which are currently in Bordeaux - France are based on the historical development of high pressure domain initiated by Professor Gerard DEMAZEAU and his team during the last half century, which is discussed here. The main concepts governing the effect of pressure on materials synthesis is by the combination of high pressure and high temperature which are described with apt examples. There is an upsurge in various technologies for strong development for the synthesis of materials to drive several possibilities, for example: to reach very high density to obtain optical ceramics (by conventional SPS), to diminish parameters (P, T, t) of synthesis (by HP-SPS), to sinter at low temperature thermal sensitive composition (by HyS), to consolidate porous materials (by FIP), to densify biocomposite with cold decontamination (by HHP) simultaneously, etc.

Proposed dedicated high pressure beam lines at CHESS

International Nuclear Information System (INIS)

Ruoff, A.L.; Vohra, Y.K.; Bassett, W.A.; Batterman, B.W.; Bilderback, D.H.

1988-01-01

An instrumentation proposal for dedicated high pressure beam lines at CHESS is described. It is the purpose of this proposed program to provide researchers in high pressure science with beam lines for X-ray diffraction studies in the megabar regime. This will involve radiation from a bending magnet as well as from a wiggler. Examples of the high pressure results up to 2.16 Mbar are shown. Diffraction patterns from bending magnet and wiggler beams are shown and compared. The need for this facility by the high pressure community is discussed. (orig.)

Highly sensitive avoidance plays a key role in sensory adaptation to deep-sea hydrothermal vent environments.

Directory of Open Access Journals (Sweden)

Tetsuya Ogino

Full Text Available The environments around deep-sea hydrothermal vents are very harsh conditions for organisms due to the possibility of exposure to highly toxic compounds and extremely hot venting there. Despite such extreme environments, some indigenous species have thrived there. Alvinellid worms (Annelida are among the organisms best adapted to high-temperature and oxidatively stressful venting regions. Although intensive studies of the adaptation of these worms to the environments of hydrothermal vents have been made, little is known about the worms' sensory adaptation to the severe chemical conditions there. To examine the sensitivity of the vent-endemic worm Paralvinella hessleri to low pH and oxidative stress, we determined the concentration of acetic acid and hydrogen peroxide that induced avoidance behavior of this worm, and compared these concentrations to those obtained for related species inhabiting intertidal zones, Thelepus sp. The concentrations of the chemicals that induced avoidance behavior of P. hessleri were 10-100 times lower than those for Thelepus sp. To identify the receptors for these chemicals, chemical avoidance tests were performed with the addition of ruthenium red, a blocker of transient receptor potential (TRP channels. This treatment suppressed the chemical avoidance behavior of P. hessleri, which suggests that TRP channels are involved in the chemical avoidance behavior of this species. Our results revealed for the first time hypersensitive detection systems for acid and for oxidative stress in the vent-endemic worm P. hessleri, possibly mediated by TRP channels, suggesting that such sensory systems may have facilitated the adaptation of this organism to harsh vent environments.

Neutron powder diffraction under high pressure at J-PARC

International Nuclear Information System (INIS)

Utsumi, Wataru; Kagi, Hiroyuki; Komatsu, Kazuki; Arima, Hiroshi; Nagai, Takaya; Okuchi, Takuo; Kamiyama, Takashi; Uwatoko, Yoshiya; Matsubayashi, Kazuyuki; Yagi, Takehiko

2009-01-01

It is expected that high-pressure material science and the investigation of the Earth's interior will progress greatly using the high-flux pulse neutrons of J-PARC. In this article, we introduce our plans for in situ neutron powder diffraction experiments under high pressure at J-PARC. The use of three different types of high-pressure devices is planned; a Paris-Edinburgh cell, a new opposed-anvil cell with a nano-polycrystalline diamond, and a cubic anvil high-pressure apparatus. These devices will be brought to the neutron powder diffraction beamlines to conduct a 'day-one' high-pressure experiment. For the next stage of research, we propose construction of a dedicated beamline for high-pressure material science. Its conceptual designs are also introduced here.

DASH diet to lower high blood pressure

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... patientinstructions/000770.htm DASH diet to lower high blood pressure To use the sharing features on this page, ... Hypertension. The DASH diet can help lower high blood pressure and cholesterol and other fats in your blood. ...

Safety supervision on high-pressure gas regulations

International Nuclear Information System (INIS)

Lee, Won Il

1991-01-01

The first part lists the regulation on safety supervision of high-pressure gas, enforcement ordinance on high-pressure gas safety supervision and enforcement regulations about high-pressure gas safety supervision. The second part indicates safety regulations on liquefied petroleum gas and business, enforcement ordinance of safety on liquefied petroleum gas and business, enforcement regulation of safety supervision over liquefied petroleum gas and business. The third part lists regulation on gas business, enforcement ordinance and enforcement regulations on gas business. Each part has theory and explanation for questions.

High-Pressure Oxygen Generation for Outpost EVA Study

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Jeng, Frank F.; Conger, Bruce; Ewert, Michael K.; Anderson, Molly S.

2009-01-01

The amount of oxygen consumption for crew extravehicular activity (EVA) in future lunar exploration missions will be significant. Eight technologies to provide high pressure EVA O2 were investigated. They are: high pressure O2 storage, liquid oxygen (LOX) storage followed by vaporization, scavenging LOX from Lander followed by vaporization, LOX delivery followed by sorption compression, water electrolysis followed by compression, stand-alone high pressure water electrolyzer, Environmental Control and Life Support System (ECLSS) and Power Elements sharing a high pressure water electrolyzer, and ECLSS and In-Situ Resource Utilization (ISRU) Elements sharing a high pressure electrolyzer. A trade analysis was conducted comparing launch mass and equivalent system mass (ESM) of the eight technologies in open and closed ECLSS architectures. Technologies considered appropriate for the two architectures were selected and suggested for development.

Hydrothermal conversion of FAU zeolite into RUT zeolite in TMAOH system

OpenAIRE

Jon, Hery; Takahashi, Shoutarou; Sasaki, Hitoshi; Oumi, Yasunori; Sano, Tsuneji

2008-01-01

The highly crystalline and pure RUT (RUB-10) zeolite could be obtained from the hydrothermal conversion of FAU zeolite used as a crystalline Si/Al source in tetramethylammonium hydroxide (TMAOH) media. As compared to amorphous silica/Al(OH)3 and amorphous silica/γ-Al2O3 sources, the crystallization rate for the formation of RUT zeolite was clearly faster when FAU zeolite was employed as the Si/Al source. Moreover, it was found that the hydrothermal conversion of FAU zeolite into RUT zeolite d...

Dynamism or Disorder at High Pressures?

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Angel, R. J.; Bismayer, U.; Marshall, W. G.

2002-12-01

Phase transitions in minerals at elevated temperatures typically involve dynamics as a natural consequence of the increase in thermal energy available to the system. Classic examples include quartz, cristobalite, and carbonates in which the high-temperature, high symmetry phase is dynamically disordered. This disorder has important thermodynamic consequences, including displacement and curvature of phase boundaries (e.g. calcite-aragonite). In other minerals such as clinopyroxenes and anorthite feldspar, the dynamic behaviour is restricted to the neighbourhood of the phase transition. The fundamental question is whether increasing pressure generally suppresses such dynamic behaviour (as in anorthite; Angel, 1988), or not. In the latter case it must be included in thermodynamic models of high-pressure phase equilibria and seismological modelling of the mantle; the potential dynamics and softening in stishovite may provide the critical observational constraint on the presence or otherwise of free silica in the lower mantle. We have continued to use the lead phosphate as a prototype ferroelastic in which to understand dynamic behaviour, simply because its dynamics and transition behaviour is far better characterised than any mineral. Furthermore, the phase transition is at a pressure where experimental difficulties do not dominate the experimental results. Our previous neutron diffraction study (Angel et al., 2001) revealed that some disorder, either dynamic or static, is retained in the high-symmetry, high-pressure phase just above the phase transition. New neutron diffraction data on the pure material now suggests that this disorder slowly decreases with increasing pressure until at twice the transition pressure it is ordered. Further data for doped material provides insights into the nature of this disorder. Angel (1988) Amer. Mineral. 73:1114. Angel et al (2001) J PhysC 13: 5353.

Hydrothermal and alkaline hydrothermal pretreatments plus anaerobic digestion of sewage sludge for dewatering and biogas production: Bench-scale research and pilot-scale verification.

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Li, Chunxing; Wang, Xingdong; Zhang, Guangyi; Yu, Guangwei; Lin, Jingjiang; Wang, Yin

2017-06-15

To test the feasibility and practicability of the process combing hydrothermal pretreatment for dewatering with biogas production for full utilization of sewage sludge, hydrothermal/alkaline hydrothermal pretreatments and in turn anaerobic digestion of the filtrates obtained after dewatering the pretreated sludge were performed at bench- and pilot-scales. The hydrothermal temperature fell within the range of 140 °C-220 °C and the pretreatment time varied from 30 min to 120 min. For the alkaline hydrothermal pretreatment the pH value of the sludge was adjusted to 9.0-11.0 by adding Ca(OH) 2 . The results showed that the dewaterability of the sewage sludge was improved with increasing pretreatment temperature but the impact of the pretreatment time was not significant. The addition of Ca(OH) 2 gave better performance on the subsequent mechanical dewatering of the pretreated sludge compared to pure hydrothermal pretreatment, and the higher the pH value was, the better the dewaterability of the pretreated sludge was. The conditions of 180 °C/30 min and 160 °C/60 min/pH = 10.0 (for hydrothermal and alkaline hydrothermal pretreatments, respectively) resulted in relatively good results in the theoretical energy balance, which were verified in the pilot-scale tests. Based on the data from the pilot tests, the alkaline hydrothermal process realized self-sufficiency in energy at the cost of a proper amount of CaO. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrothermal synthesis of Fe_2O_3/polypyrrole/graphene oxide composites as highly efficient electrocatalysts for oxygen reduction reaction in alkaline electrolyte

International Nuclear Information System (INIS)

Ren, Suzhen; Ma, Shaobo; Yang, Ying; Mao, Qing; Hao, Ce

2015-01-01

Graphical abstract: Fe_2O_3/polypyrrole/graphene oxide electrocatalysts for oxygen reduction reaction (ORR) are successfully prepared through one simple polypyrrole-assisted hydrothermal method and possess very high ORR activity and are able to selectively reduce O_2 to water through the four-electron transfer reaction mechanism in alkaline electrolyte. - Abstract: Advantages in low cost, and excellent catalytic activity of Fe-based nanomaterials dispersed on nitrogen-doped graphene supports render them to be good electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells. Here, Fe_2O_3/polypyrrole/graphene oxide (Fe_2O_3/Ppy/GO) composites with the Fe_2O_3 embedded in the Ppy modified GO are synthesized using hydrothermal method. With an optimal iron atom content ratio of 1.6% in graphene oxide and heat treatment at 800 °C, the Fe_2O_3/Ppy/GO exhibited enhanced catalytic performance for ORR with the onset potential of −0.1 V (vs SCE), cathodic potential of −0.24 V (vs SCE), an approximate 4e"− transfer process in O_2-saturated 0.1 M KOH, and superior stability that only reduced 5% catalytic activity after 5000 cycles. The decisive factors in improving the electrocatalytic and durable performance are the intimate and large contact interfaces between nanocrystallines of Fe_2O_3 and Ppy/GO, in addition to the high electron withdrawing/storing ability and the high conductivity of GO doped with nitrogen from Ppy during the hydrothermal reaction. The Fe_2O_3/Ppy/GO showed significantly improved ORR properties and confirmed that Fe-N-C-based electrocatalysts played a key role in fuel cells.

Mechano-hydrothermal preparation of Li-Al-OH layered double hydroxides

Science.gov (United States)

Zhang, Fengrong; Hou, Wanguo

2018-05-01

A mechano-hydrothermal (MHT) method was used to synthesize Li-Al-OH layered double hydroxides (LDHs) from LiOH·H2O, Al(OH)3 and H2O as starting materials. A two-step synthesis was conducted, that is, Al(OH)3 was milled for 1 h, followed by hydrothermal treatment with LiOH·H2O solution. Effects of the LiOH/Al(OH)3 molar ratio (RLi/Al) and hydrothermal temperature (Tht) on the crystallinity, morphology, and composition of the product were examined. The resulting LDHs were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared, and elemental analyses. The results showed that pre-milling plays a key role in the LDH formation during subsequent hydrothermal treatment. The Li/Al molar ratio of the obtained LDHs keeps constant at 0.5, independent from theRLi/Al (0.5-5.0) in the starting materials. An increase in the Tht (20-80 °C) can enhance the crystallinity and morphology regularity of the products. The so-obtained Li-Al-OH LDHs exhibit high crystallinity and well-dispersity, which may have wider applications than the aggregate ones obtained using conventional mechanochemical and Li+-imbibition methods.

Vertical Cable Seismic Survey for Hydrothermal Deposit

Science.gov (United States)

Asakawa, E.; Murakami, F.; Sekino, Y.; Okamoto, T.; Ishikawa, K.; Tsukahara, H.; Shimura, T.

2012-04-01

The vertical cable seismic is one of the reflection seismic methods. It uses hydrophone arrays vertically moored from the seafloor to record acoustic waves generated by surface, deep-towed or ocean bottom sources. Analyzing the reflections from the sub-seabed, we could look into the subsurface structure. This type of survey is generally called VCS (Vertical Cable Seismic). Because VCS is an efficient high-resolution 3D seismic survey method for a spatially-bounded area, we proposed the method for the hydrothermal deposit survey tool development program that the Ministry of Education, Culture, Sports, Science and Technology (MEXT) started in 2009. We are now developing a VCS system, including not only data acquisition hardware but data processing and analysis technique. Our first experiment of VCS surveys has been carried out in Lake Biwa, JAPAN in November 2009 for a feasibility study. Prestack depth migration is applied to the 3D VCS data to obtain a high quality 3D depth volume. Based on the results from the feasibility study, we have developed two autonomous recording VCS systems. After we carried out a trial experiment in the actual ocean at a water depth of about 400m and we carried out the second VCS survey at Iheya Knoll with a deep-towed source. In this survey, we could establish the procedures for the deployment/recovery of the system and could examine the locations and the fluctuations of the vertical cables at a water depth of around 1000m. The acquired VCS data clearly shows the reflections from the sub-seafloor. Through the experiment, we could confirm that our VCS system works well even in the severe circumstances around the locations of seafloor hydrothermal deposits. We have, however, also confirmed that the uncertainty in the locations of the source and of the hydrophones could lower the quality of subsurface image. It is, therefore, strongly necessary to develop a total survey system that assures a accurate positioning and a deployment techniques

Combined hydrothermal liquefaction and catalytic hydrothermal gasification system and process for conversion of biomass feedstocks

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Elliott, Douglas C.; Neuenschwander, Gary G.; Hart, Todd R.

2017-09-12

A combined hydrothermal liquefaction (HTL) and catalytic hydrothermal gasification (CHG) system and process are described that convert various biomass-containing sources into separable bio-oils and aqueous effluents that contain residual organics. Bio-oils may be converted to useful bio-based fuels and other chemical feedstocks. Residual organics in HTL aqueous effluents may be gasified and converted into medium-BTU product gases and directly used for process heating or to provide energy.

Modeling, Parameters Identification, and Control of High Pressure Fuel Cell Back-Pressure Valve

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Fengxiang Chen

2014-01-01

Full Text Available The reactant pressure is crucial to the efficiency and lifespan of a high pressure PEMFC engine. This paper analyses a regulated back-pressure valve (BPV for the cathode outlet flow in a high pressure PEMFC engine, which can achieve precisely pressure control. The modeling, parameters identification, and nonlinear controller design of a BPV system are considered. The identified parameters are used in designing active disturbance rejection controller (ADRC. Simulations and extensive experiments are conducted with the xPC Target and show that the proposed controller can not only achieve good dynamic and static performance but also have strong robustness against parameters’ disturbance and external disturbance.

Resistivity structure and geochemistry of the Jigokudani Valley hydrothermal system, Mt. Tateyama, Japan

Science.gov (United States)

Seki, Kaori; Kanda, Wataru; Tanbo, Toshiya; Ohba, Takeshi; Ogawa, Yasuo; Takakura, Shinichi; Nogami, Kenji; Ushioda, Masashi; Suzuki, Atsushi; Saito, Zenshiro; Matsunaga, Yasuo

2016-10-01

This study clarifies the hydrothermal system of Jigokudani Valley near Mt. Tateyama volcano in Japan by using a combination of audio-frequency magnetotelluric (AMT) survey and hot-spring water analysis in order to assess the potential of future phreatic eruptions in the area. Repeated phreatic eruptions in the area about 40,000 years ago produced the current valley morphology, which is now an active solfatara field dotted with hot springs and fumaroles indicative of a well-developed hydrothermal system. The three-dimensional (3D) resistivity structure of the hydrothermal system was modeled by using the results of an AMT survey conducted at 25 locations across the valley in 2013-2014. The model suggests the presence of a near-surface highly conductive layer of falling largely on a mixing line between magmatic fluids and local meteoric water (LMW). The geochemical analysis suggests that the hydrothermal system includes a two-phase zone of vapor-liquid. A comparison of the resistivity structure and the geochemically inferred structure suggests that a hydrothermal reservoir is present at a depth of approximately 500 m, from which hot-spring water differentiates into the three observed types. The two-phase zone appears to be located immediately beneath the cap rock structure. These findings suggest that the hydrothermal system of Jigokudani Valley exhibits a number of factors that could trigger a future phreatic eruption.

Hydrothermal liquefaction of high- and low-lipid algae: Mass and energy balances.

Science.gov (United States)

Cheng, Feng; Cui, Zheng; Mallick, Kwonit; Nirmalakhandan, Nagamany; Brewer, Catherine E

2018-06-01

Hydrothermal liquefaction (HTL) of high-lipid microalgae Nannochloropsis salina (N. salina) and low-lipid microalgae Galdieria sulphuraria (G. sulphuraria) were run under subcritical conditions (310-350 °C and 10-17 MPa) in a 1.8 L batch autoclave system. HTL mass and energy balances for both species were compared under different operating conditions to predict the optimum reaction conditions for new algae strains based on their feedstock composition. Bio-crude oils and chars were characterized by bomb calorimetry, elemental analysis, inductively coupled plasma optical emission spectrometry (ICP-OES), and thermogravimetric analysis (TGA). Under the optimized conditions, 59 wt% and 31 wt% bio-crude oil yields were obtained from HTL of N. salina and G. sulphuraria, while 85% and 59% of the feedstock energy were partitioned into N. salina-derived and G. sulphuraria-derived bio-crude oils, respectively. More favorable energy balances were related to shorter reaction times and higher algal solid contents. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydrothermal plume anomalies over the southwest Indian ridge: magmatic control

Science.gov (United States)

Yue, X.; Li, H.; Tao, C.; Ren, J.; Zhou, J.; Chen, J.; Chen, S.; Wang, Y.

2017-12-01

Here we firstly reported the extensive survey results of the hydrothermal activity along the ultra-slow spreading southwest Indian ridge (SWIR). The study area is located at segment 27, between the Indomed and Gallieni transform faults, SWIR. The seismic crustal thickness reaches 9.5km in this segment (Li et al., 2015), which is much thicker than normal crustal. The anomaly thickened crust could be affected by the Crozet hotspot or highly focused melt delivery from the mantle. The Duanqiao hydrothermal field was reported at the ridge valley of the segment by Tao et al (2009). The Deep-towed Hydrothermal Detection System (DHDS) was used to collect information related with hydrothermal activity, like temperature, turbidity, oxidation-reduction potential (ORP) and seabed types. There are 15 survey lines at the interval of 2 to 3 km which are occupied about 1300 km2 in segment 27. After processing the raw data, including wiping out random noise points, 5-points moving average processing and subtracting the ambient, we got anomalous Nephelometric Turbidity Units values (ΔNTU). And dE/dt was used to identify the ORP anomalous as the raw data is easily influenced by electrode potentials drifting (Baker et al., 2016). According to the results of water column turbidity and ORP distributions, we confirmed three hydrothermal anomaly fields named A1, A2 and A3. The three fields are all located in the western part of the segment. The A1 field lies on the ridge valley, west side of Duanqiao field. The A2 and A3 field lie on the northern and southern of the ridge valley, respectively. We propose that recent magmatic activity probably focus on the western part of segment 27.And the extensive distribution of hydrothermal plume in the segment is the result of the discrete magma intrusion. References Baker E T, et al. How many vent fields? New estimates of vent field populations on ocean ridges from precise mapping of hydrothermal discharge locations. EPSL, 2016, 449:186-196. Li J

Managing Stress to Control High Blood Pressure

Science.gov (United States)

... Aortic Aneurysm More Managing Stress to Control High Blood Pressure Updated:Jan 29,2018 The importance of stress ... This content was last reviewed October 2016. High Blood Pressure • Home • Get the Facts About HBP • Know Your ...

Al-doped SnO2 nanocrystals from hydrothermal systems

International Nuclear Information System (INIS)

Jin Haiying; Xu Yaohua; Pang Guangsheng; Dong Wenjun; Wan Qiang; Sun Yan; Feng Shouhua

2004-01-01

Nanoparticles of Al-doped SnO 2 have been hydrothermally synthesized. The influences of the hydrothermal reaction time, the molar ratio of Sn/Al as well as the pH value of the solution have been studied. During the hydrothermal synthesis, the particle's core is rich in Sn and the surface is rich in Al. The Al-rich surface prevents the particles from further growing up either in the hydrothermal condition or during the calcination at 600 deg. C for a short period of time. The optimal hydrothermal synthesis condition of the nanoparticles is pH 5, Sn/Al=4:1 and 12 h at 160 deg. C. The products have been studied by XRD, TEM and 27 Al solid-state NMR

High-pressure-assisted synthesis of high-volume ZnGeP2 polycrystalline

Science.gov (United States)

Huang, Changbao; Wu, Haixin; Xiao, Ruichun; Chen, Shijing; Ma, Jiaren

2018-06-01

The pnictide and chalcogenide semiconductors are promising materials for the applications in the field of photoelectric. High-purity and high-volume polycrystalline required in the real-world applications is hard to be synthesized due to the high vapor pressure of phosphorus and sulfur components at high temperature. A new high-pressure-resisted method was used to investigate the synthesis of the nonlinear-optical semiconductor ZnGeP2. The high-purity ZnGeP2 polycrystalline material of approximately 500 g was synthesized in one run, which enables the preparation of nominally stoichiometric material. Since increasing internal pressure resistance of quartz crucible and reducing the reaction space, the high-pressure-resisted method can be used to rapidly synthesize other pnictide and chalcogenide semiconductors and control the components ratio.

Pressure balanced type membrane covered polarographic oxygen detectors for use in high temperature-high pressure water, (1)

International Nuclear Information System (INIS)

Nakayama, Norio; Uchida, Shunsuke

1984-01-01

A pressure balanced type membrane covered polarographic oxygen detector was developed to determine directly oxygen concentrations in high temperature, high pressure water without cooling and pressure reducing procedures. The detector is characterized by the following features: (1) The detector body and the membrane for oxygen penetration are made of heat resistant resin. (2) The whole detector body is contained in a pressure chamber where interior and exterior pressures of the detector are balanced. (3) Thermal expansion of the electrolyte is absorbed by deformation of a diaphragm attached to the detector bottom. (4) The effect of dissolved Ag + on the signal current is eliminated by applying a guard electrode. As a result of performance tests at elevated temperature, it was demonstrated that a linear relationship between oxygen concentration and signal current was obtained up to 285 0 C, which was stabilized by the guard electrode. The minimum O 2 concentration detectable was 0.03ppm (9.4 x 10 -7 mol/kg). (author)

Non-traditional Stable Isotope Systematics of Seafloor Hydrothermal Systems

Science.gov (United States)

Rouxel, O. J.

2009-05-01

Seafloor hydrothermal activity at mid-ocean ridges is one of the fundamental processes controlling the chemistry of the oceans and the altered oceanic crust. Past studies have demonstrated the complexity and diversity of seafloor hydrothermal systems and have highlighted the importance of subsurface environments in controlling the composition of hydrothermal fluids and mineralization types. Traditionally, the behavior of metals in seafloor hydrothermal systems have been investigated by integrating results from laboratory studies, theoretical models, mineralogy and fluid and mineral chemistry. Isotope ratios of various metals and metalloids, such as Fe, Cu, Zn, Se, Cd and Sb have recently provided new approaches for the study of seafloor hydrothermal systems. Despite these initial investigations, the cause of the isotopic variability of these elements remains poorly constrained. We have little understanding of the isotope variations between vent types (black or white smokers) as well as the influence of source rock composition (basalt, felsic or ultrabasic rocks) and alteration types. Here, I will review and present new results of metal isotope systematics of seafloor hydrothermal systems, in particular: (1) determination of empirical isotope fractionation factors for Zn, Fe and Cu-isotopes through isotopic analysis of mono-mineralic sulfide grains lining the internal chimney wall in contact with hydrothermal fluid; (2) comparison of Fe- and Cu-isotope signatures of vent fluids from mid- oceanic and back-arc hydrothermal fields, spanning wide ranges of pH, temperature, metal concentrations and contributions of magmatic fluids enriched in SO2. Ultimately, the use of complementary non-traditional stable isotope systems may help identify and constrain the complex interactions between fluids,minerals, and organisms in seafloor hydrothermal systems.

Hydrothermal systems and volcano geochemistry

Science.gov (United States)

Fournier, R.O.

2007-01-01

The upward intrusion of magma from deeper to shallower levels beneath volcanoes obviously plays an important role in their surface deformation. This chapter will examine less obvious roles that hydrothermal processes might play in volcanic deformation. Emphasis will be placed on the effect that the transition from brittle to plastic behavior of rocks is likely to have on magma degassing and hydrothermal processes, and on the likely chemical variations in brine and gas compositions that occur as a result of movement of aqueous-rich fluids from plastic into brittle rock at different depths. To a great extent, the model of hydrothermal processes in sub-volcanic systems that is presented here is inferential, based in part on information obtained from deep drilling for geothermal resources, and in part on the study of ore deposits that are thought to have formed in volcanic and shallow plutonic environments.

Hydrothermal reactions of nuclear waste solids . A preliminary study

International Nuclear Information System (INIS)

Westsik, J.H. Jr.; Turcotte, R.P.

1978-09-01

A simulated high-level waste glass, Supercalcine, and some common ceramic and metallic solids were exposed to hydrothermal conditions at 250 and 350 0 C for time periods ranging from three days to three weeks. Most of the experiments were done in salt brine, but the glass study did include deionized water tests so that the influence of salt could be better understood. Under the extreme hydrothermal conditions of these tests, all of the materials examined underwent measurable changes. The glass is converted to a mixture of crystalline phases, depending upon conditions, giving NaFeSi 2 O 6 as the primary alteration product. The rate of alteration is higher in deionized water than in salt brine; however, under equivalent test conditions, 66% of the Cs originally in the glass is released to the salt brine, while only 6% is released to deionized water. Rb and Mo are the only other fission product elements significantly leached from the glass. Evidence is presented which shows that sintered Supercalcine undergoes chemical changes in salt brine that are qualitatively similar to those experienced by glass samples. High concentrations of Cs enter the aqueous phase, and Sn and Mo are mobilized. Scouting tests were made with a variety of materials including commercial glasses, granite, UO 2 , Al 2 O 3 , steel, and waste glasses. Weight losses under hydrothermal conditions are in a relatively narrow band, with glass and ceramic materials showing 3 to 20 times greater weight losses than 304L stainless steel in the 250 0 C test used. The conclusion from these studies is that virtually all solid materials show hydrothermal reactivity at temperatures between 250 and 350 0 C, and that these extreme conditions are not desirable

Diamonds: powerful tools for high-pressure physics

International Nuclear Information System (INIS)

Anon.

1983-01-01

Diamond-anvil high-pressure studies have progressed to the point where they complement shock-wave studies. Because they operate at static high pressure, they permit time-consuming procedures, such as x-ray diffraction measurements for determining crystal structure. The sample material is completely recoverable and the method is adaptable to minute advantage when dealing with rare or hazardous materials. One of our goals in investigating the high-pressure behavior of iridium was to test the theoretical prediction that iridium would exhibit a phase transformation from the face-centered cubic crystal structure at about 9 GPa. Our finding that no such transformation takes place even at pressures up to 30 GPa will need to be taken into account by physicsts working to improve solid-state theory

The partitioning of barium and lead between silicate melts and aqueous fluids at high pressures and temperatures

International Nuclear Information System (INIS)

Bureau, Helene; Menez, Benedicte; Khodja, Hicham; Daudin, Laurent; Gallien, Jean-Paul; Massare, Dominique; Shaw, Cliff; Metrich, Nicole

2003-01-01

The origin of subduction-related magmas is still a matter of debate in the Earth Sciences. These magmas are characterised by their distinctive trace element compositions compared to magmas from other tectonic settings, e.g. mid-ocean ridges or rifts. The distinct trace element composition of these magmas is generally attributed to alteration of the source region by a contaminating agent: either a silicate melt or a hydrous fluid, possibly chlorine-enriched. In this study, we have used μPIXE (proton induced X-ray emission) to analyse synthetic samples obtained from a micro-experimental petrology study that aims to determine the partitioning behaviour of two key elements, Ba and Pb, between silicate melt and both pure water and saline fluids. Our experiments were performed at high-pressure (>0.34-1.53 GPa) and high-temperature (697-1082 deg. C) in a hydrothermal diamond anvil cell, that was used as a transparent rapid quench autoclave. We observed that at high pressure and temperature, in the presence of pure water, Ba and Pb are not strongly fractionated into one phase or the other. The partition coefficient of Pb is ranging from 0.46 to 1.28. Results from one experiment performed at 0.83 GPa and 847 deg. C, in the presence of a saline fluid indicate that the presence of Cl induces strong fractionation of Pb and moderate fractionation of Ba both into the silicate melt. In addition, our data indicate that Cl is strongly partitioned into the fluid phase

Ideas and perspectives: hydrothermally driven redistribution and sequestration of early Archaean biomass – the “hydrothermal pump hypothesis”

Directory of Open Access Journals (Sweden)

J.-P. Duda

2018-03-01

Full Text Available Archaean hydrothermal chert veins commonly contain abundant organic carbon of uncertain origin (abiotic vs. biotic. In this study, we analysed kerogen contained in a hydrothermal chert vein from the ca. 3.5 Ga Dresser Formation (Pilbara Craton, Western Australia. Catalytic hydropyrolysis (HyPy of this kerogen yielded n-alkanes up to n-C22, with a sharp decrease in abundance beyond n-C18. This distribution ( ≤  n-C18 is very similar to that observed in HyPy products of recent bacterial biomass, which was used as reference material, whereas it differs markedly from the unimodal distribution of abiotic compounds experimentally formed via Fischer–Tropsch-type synthesis. We therefore propose that the organic matter in the Archaean chert veins has a primarily microbial origin. The microbially derived organic matter accumulated in anoxic aquatic (surface and/or subsurface environments and was then assimilated, redistributed and sequestered by the hydrothermal fluids (hydrothermal pump hypothesis.

High-pressure-high-temperature treatment of natural diamonds

CERN Document Server

Royen, J V

2002-01-01

The results are reported of high-pressure-high-temperature (HPHT) treatment experiments on natural diamonds of different origins and with different impurity contents. The diamonds are annealed in a temperature range up to 2000 sup o C at stabilizing pressures up to 7 GPa. The evolution is studied of different defects in the diamond crystal lattice. The influence of substitutional nitrogen atoms, plastic deformation and the combination of these is discussed. Diamonds are characterized at room and liquid nitrogen temperature using UV-visible spectrophotometry, Fourier transform infrared spectrophotometry and photoluminescence spectrometry. The economic implications of diamond HPHT treatments are discussed.

High pressure discharges in cavities formed by microfabrication techniques

International Nuclear Information System (INIS)

Khan, B.A.; Cammack, D.A.; Pinker, R.D.; Racz, J.

1997-01-01

High pressure discharges are the basis of small high intensity light sources. In this work, we demonstrate the formation of high pressure discharges, in cavities formed by applying micromachining and integrated circuit techniques to quartz substrates. Cavities containing varying amounts of mercury and argon were fabricated to obtain high pressure discharges. A high pressure mercury discharge was formed in the electrodeless cavities by exciting them with a microwave source, operating at 2.45 GHz and in the electroded cavities by applying a dc voltage. The contraction of the discharge into a high pressure arc was observed. A broad emission spectrum due to self-absorption and collisions between excited atoms and normal atoms, typical of high pressure mercury discharges, was measured. The light output and efficacy increased with increasing pressure. The measured voltage was used to estimate the pressure within the electroded cavities, which is as high as 127 atm for one of the two cavities discussed in this work. Efficacies over 40 lumens per watt were obtained for the electrodeless cavities and over 50 scr(l)m/W for the electroded cavities. copyright 1997 American Institute of Physics

Hydrothermal Synthesis of Hydroxyapatite Nanorods for Rapid Formation of Bone-Like Mineralization

Science.gov (United States)

Hoai, Tran Thanh; Nga, Nguyen Kim; Giang, Luu Truong; Huy, Tran Quang; Tuan, Phan Nguyen Minh; Binh, Bui Thi Thanh

2017-08-01

Hydroxyapatite (HAp) is an excellent biomaterial for bone repair and regeneration. The biological functions of HAp particles, such as biomineralization, cell adhesion, and cell proliferation, can be enhanced when their size is reduced to the nanoscale. In this work, HAp nanoparticles were synthesized by the hydrothermal technique with addition of cetyltrimethylammonium bromide (CTAB). These particles were also characterized, and their size controlled by modifying the CTAB concentration and hydrothermal duration. The results show that most HAp nanoparticles were rod-like in shape, exhibiting the most uniform and smallest size (mean diameter and length of 39 nm and 125 nm, respectively) at optimal conditions of 0.64 g CTAB and hydrothermal duration of 12 h. Moreover, good biomineralization capability of the HAp nanorods was confirmed through in vitro tests in simulated body fluid. A bone-like mineral layer of synthesized HAp nanorods formed rapidly after 7 days. This study shows that highly bioactive HAp nanorods can be easily prepared by the hydrothermal method, being a potential nanomaterial for bone regeneration.

Rheological assessment of nanofluids at high pressure high temperature

Science.gov (United States)

Kanjirakat, Anoop; Sadr, Reza

2013-11-01

High pressure high temperature (HPHT) fluids are commonly encountered in industry, for example in cooling and/or lubrications applications. Nanofluids, engineered suspensions of nano-sized particles dispersed in a base fluid, have shown prospective as industrial cooling fluids due to their enhanced rheological and heat transfer properties. Nanofluids can be potentially utilized in oil industry for drilling fluids and for high pressure water jet cooling/lubrication in machining. In present work rheological characteristics of oil based nanofluids are investigated at HPHT condition. Nanofluids used in this study are prepared by dispersing commercially available SiO2 nanoparticles (~20 nm) in a mineral oil. The basefluid and nanofluids with two concentrations, namely 1%, and 2%, by volume, are considered in this investigation. The rheological characteristics of base fluid and the nanofluids are measured using an industrial HPHT viscometer. Viscosity values of the nanofluids are measured at pressures of 100 kPa to 42 MPa and temperatures ranging from 25°C to 140°C. The viscosity values of both nanofluids as well as basefluid are observed to have increased with the increase in pressure. Funded by Qatar National Research Fund (NPRP 08-574-2-239).

Waste treatment process by solidifying cementitious materials using hydrothermal hot-pressing

International Nuclear Information System (INIS)

Matsumoto, Y.; Kamakura, T.; Yamasaki, N.; Hashida, T.

2001-01-01

Solidification of low-level radioactive wastes containing Na 2 SO 4 with cement by hydrothermal hot-pressing (HHP) technique was examined. Relatively high mechanical strength, reduced leaching ratio of SO 3 , and higher resistance to the carbonation of the HHP product were attained in comparison with conventional concrete. The solidification by the HHP treatment may be proceeded by the rearrangement of particles and the bonding material formation among the particles by dissolution-deposition process. The possibility of developing the accelerated testing method for duration of cemented materials by hydrothermal method was discussed. (author)

High pressure Moessbauer spectroscopy of perovskite iron oxide