Computer simulation of liquid-vapor coexistence of confined quantum fluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trejos, Víctor M.; Gil-Villegas, Alejandro, E-mail: gil@fisica.ugto.mx; Martinez, Alejandro

2013-11-14

The liquid-vapor coexistence (LV) of bulk and confined quantum fluids has been studied by Monte Carlo computer simulation for particles interacting via a semiclassical effective pair potential V{sub eff}(r) = V{sub LJ} + V{sub Q}, where V{sub LJ} is the Lennard-Jones 12-6 potential (LJ) and V{sub Q} is the first-order Wigner-Kirkwood (WK-1) quantum potential, that depends on β = 1/kT and de Boer's quantumness parameter Λ=h/σ√(mε), where k and h are the Boltzmann's and Planck's constants, respectively, m is the particle's mass, T is the temperature of the system, and σ and ε are the LJ potential parameters. The non-conformalmore » properties of the system of particles interacting via the effective pair potential V{sub eff}(r) are due to Λ, since the LV phase diagram is modified by varying Λ. We found that the WK-1 system gives an accurate description of the LV coexistence for bulk phases of several quantum fluids, obtained by the Gibbs Ensemble Monte Carlo method (GEMC). Confinement effects were introduced using the Canonical Ensemble (NVT) to simulate quantum fluids contained within parallel hard walls separated by a distance L{sub p}, within the range 2σ ⩽ L{sub p} ⩽ 6σ. The critical temperature of the system is reduced by decreasing L{sub p} and increasing Λ, and the liquid-vapor transition is not longer observed for L{sub p}/σ < 2, in contrast to what has been observed for the classical system.« less

Seismic and aseismic fault slip in response to fluid injection observed during field experiments at meter scale

NASA Astrophysics Data System (ADS)

Cappa, F.; Guglielmi, Y.; De Barros, L.; Wynants-Morel, N.; Duboeuf, L.

2017-12-01

During fluid injection, the observations of an enlarging cloud of seismicity are generally explained by a direct response to the pore pressure diffusion in a permeable fractured rock. However, fluid injection can also induce large aseismic deformations which provide an alternative mechanism for triggering and driving seismicity. Despite the importance of these two mechanisms during fluid injection, there are few studies on the effects of fluid pressure on the partitioning between seismic and aseismic motions under controlled field experiments. Here, we describe in-situ meter-scale experiments measuring synchronously the fluid pressure, the fault motions and the seismicity directly in a fault zone stimulated by controlled fluid injection at 280 m depth in carbonate rocks. The experiments were conducted in a gallery of an underground laboratory in south of France (LSBB, http://lsbb.eu). Thanks to the proximal monitoring at high-frequency, our data show that the fluid overpressure mainly induces a dilatant aseismic slip (several tens of microns up to a millimeter) at the injection. A sparse seismicity (-4 < Mw < -3) is observed several meters away from the injection, in a part of the fault zone where the fluid overpressure is null or very low. Using hydromechanical modeling with friction laws, we simulated an experiment and investigated the relative contribution of the fluid pressure diffusion and stress transfer on the seismic and aseismic fault behavior. The model reproduces the hydromechanical data measured at injection, and show that the aseismic slip induced by fluid injection propagates outside the pressurized zone where accumulated shear stress develops, and potentially triggers seismicity. Our models also show that the permeability enhancement and friction evolution are essential to explain the fault slip behavior. Our experimental results are consistent with large-scale observations of fault motions at geothermal sites (Wei et al., 2015; Cornet, 2016), and suggest that controlled field experiments at meter-scale are important for better assessing the role of fluid pressure in natural and human-induced earthquakes.

Beryllium chemical speciation in elemental human biological fluids.

PubMed

Sutton, Mark; Burastero, Stephen R

2003-09-01

The understanding of beryllium chemistry in human body fluids is important for understanding the prevention and treatment of chronic beryllium disease. Thermodynamic modeling has traditionally been used to study environmental contaminant migration and rarely in the examination of metal (particularly beryllium) toxicology. In this work, a chemical thermodynamic speciation code (MINTEQA2) has been used to model and understand the chemistry of beryllium in simulated human biological fluids such as intracellular, interstitial, and plasma fluids, a number of airway surface fluids for patients with lung conditions, saliva, sweat, urine, bile, gastric juice, and pancreatic fluid. The results show that predicted beryllium solubility and speciation vary markedly between each simulated biological fluid. Formation of beryllium hydroxide and/or phosphate was observed in most of the modeled fluids, and results support the postulation that beryllium absorption in the gastrointestinal tract may be limited by the formation of beryllium phosphate solids. It is also postulated that beryllium is potentially 13% less soluble in the airway surface fluid of a patient with asthma when compared to a "normal" case. The results of this work, supported by experimental validation, can aid in the understanding of beryllium toxicology. Our results can potentially be applied to assessing the feasibility of biological monitoring or chelation treatment of beryllium body burden.

Numerical models of caldera deformation: Effects of multiphase and multicomponent hydrothermal fluid flow

USGS Publications Warehouse

Hutnak, M.; Hurwitz, S.; Ingebritsen, S.E.; Hsieh, P.A.

2009-01-01

Ground surface displacement (GSD) in large calderas is often interpreted as resulting from magma intrusion at depth. Recent advances in geodetic measurements of GSD, notably interferometric synthetic aperture radar, reveal complex and multifaceted deformation patterns that often require complex source models to explain the observed GSD. Although hydrothermal fluids have been discussed as a possible deformation agent, very few quantitative studies addressing the effects of multiphase flow on crustal mechanics have been attempted. Recent increases in the power and availability of computing resources allow robust quantitative assessment of the complex time-variant thermal interplay between aqueous fluid flow and crustal deformation. We carry out numerical simulations of multiphase (liquid-gas), multicomponent (H 2O-CO2) hydrothermal fluid flow and poroelastic deformation using a range of realistic physical parameters and processes. Hydrothermal fluid injection, circulation, and gas formation can generate complex, temporally and spatially varying patterns of GSD, with deformation rates, magnitudes, and geometries (including subsidence) similar to those observed in several large calderas. The potential for both rapid and gradual deformation resulting from magma-derived fluids suggests that hydrothermal fluid circulation may help explain deformation episodes at calderas that have not culminated in magmatic eruption.

Garden City Vein Complex, Gale Crater, Mars: Implications for Late Diagenetic Fluid Flow

NASA Astrophysics Data System (ADS)

Kronyak, R. E.; Kah, L. C.; Blaney, D. L.; Sumner, D. Y.; Fisk, M. R.; Rapin, W.; Nachon, M.; Mangold, N.; Grotzinger, J. P.; Wiens, R. C.

2015-12-01

Calcium sulfate filled fractures are observed in nearly all stratigraphic units encountered by the Mars Science Laboratory (MSL) Curiosity rover. The mm-scale of veins, however, provides little evidence for emplacement style. From sols 924-949, Curiosity observed a vein rich outcrop called Garden City, which shows variation in both thickness and complexity of veins. Extensive Mastcam and MAHLI imaging was conducted across the outcrop to provide textural detail that can be related to emplacement mechanisms. Additionally, Curiosity collected geochemical data on 17 ChemCam targets and 7 APXS targets, shedding light on the composition and variety of potential vein fluids. The Garden City vein system records (1) the presence of distinct dark-toned and light-toned (calcium sulfate) mineralization, and (2) the presence of laminated, epitaxial, and brecciated fabrics that suggest multiple emplacement modes. Dark-toned mineralization is observed as erosionally resistant ridges predominantly along fracture walls. Although erosional resistance may reflect the permeability of host rock to fracture-borne fluids, at Garden City, laminated textures suggest that at least some mineralization may have occurred as fracture-fill. Light-toned mineralization often bisects dark-toned material, indicating re-use of fluid pathways. Light-toned veinlets permeate fracture walls, and the largest veins entrain host rock and dark-toned material within calcium sulfate matrix. Such brecciation indicates high forces associated with fluid expulsion. Elsewhere, linear patterns occur broadly perpendicular to fracture walls, and are interpreted to represent epitaxial crystal growth, suggesting lower flow rates and fluid flow pressures within the fracture system. Together these observations indicate multiple episodes of fluid flow in the Gale Crater system.

Electrokinetically driven active micro-mixers utilizing zeta potential variation induced by field effect

NASA Astrophysics Data System (ADS)

Lee, Chia-Yen; Lee, Gwo-Bin; Fu, Lung-Ming; Lee, Kuo-Hoong; Yang, Ruey-Jen

2004-10-01

This paper presents a new electrokinetically driven active micro-mixer which uses localized capacitance effects to induce zeta potential variations along the surface of silica-based microchannels. The mixer is fabricated by etching bulk flow and shielding electrode channels into glass substrates and then depositing Au/Cr thin films within the latter to form capacitor electrodes, which establish localized zeta potential variations near the electrical double layer (EDL) region of the electroosmotic flow (EOF) within the microchannels. The potential variations induce flow velocity changes within a homogeneous fluid and a rapid mixing effect if an alternating electric field is provided. The current experimental data confirm that the fluid velocity can be actively controlled by using the capacitance effect of the buried shielding electrodes to vary the zeta potential along the channel walls. While compared with commonly used planar electrodes across the microchannels, the buried shielding electrodes prevent current leakage caused by bad bonding and allow direct optical observation during operation. It also shows that the buried shielding electrodes can significantly induce the field effect, resulting in higher variations of zeta potential. Computational fluid dynamic simulations are also used to study the fluid characteristics of the developed active mixers. The numerical and experimental results demonstrate that the developed microfluidic device permits a high degree of control over the fluid flow and an efficient mixing effect. Moreover, the developed device could be used as a pumping device as well. The development of the active electrokinetically driven micro-mixer could be crucial for micro-total-analysis-systems.

Thermodynamic properties of triangle-well fluids in two dimensions: MC and MD simulations.

PubMed

Reyes, Yuri; Bárcenas, Mariana; Odriozola, Gerardo; Orea, Pedro

2016-11-07

With the aim of providing complementary data of the thermodynamics properties of the triangular well potential, the vapor/liquid phase diagrams for such potential with different interaction ranges were calculated in two dimensions by Monte Carlo and molecular dynamics simulations; also, the vapor/liquid interfacial tension was calculated. As reported for other interaction potentials, it was observed that the reduction of the dimensionality makes the phase diagram to shrink. Finally, with the aid of reported data for the same potential in three dimensions, it was observed that this potential does not follow the principle of corresponding states.

The Ingestion of Fluorescent, Magnetic Nanoparticles for Determining Fluid-uptake Abilities in Insects

DOE PAGES

Lehnert, Matthew S.; Reiter, Kristen E.; Bennett, Andrew; ...

2017-01-01

Here, fluid-feeding insects ingest a variety of liquids, which are present in the environment as pools, films, or confined to small pores. Studies of liquid acquisition require assessing mouthpart structure and function relationships; however, fluid uptake mechanisms are historically inferred from observations of structural architecture, sometimes unaccompanied with experimental evidence. Here, we report a novel method for assessing fluid-uptake abilities with butterflies (Lepidoptera) and flies (Diptera) using small amounts of liquids. Insects are fed with a 20% sucrose solution mixed with fluorescent, magnetic nanoparticles from filter papers of specific pore sizes. The crop (internal structure used for storing fluids) ismore » removed from the insect and placed on a confocal microscope. A magnet is waved by the crop to determine the presence of nanoparticles, which indicate if the insects are able to ingest fluids. This methodology is used to reveal a widespread feeding mechanism (capillary action and liquid bridge formation) that is potentially shared among Lepidoptera and Diptera when feeding from porous surfaces. In addition, this method can be used for studies of feeding mechanisms among a variety of fluid-feeding insects, including those important in disease transmission and biomimetics, and potentially other studies that involve nano- or micro-sized conduits where liquid transport requires verification.« less

The Ingestion of Fluorescent, Magnetic Nanoparticles for Determining Fluid-uptake Abilities in Insects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lehnert, Matthew S.; Reiter, Kristen E.; Bennett, Andrew

Here, fluid-feeding insects ingest a variety of liquids, which are present in the environment as pools, films, or confined to small pores. Studies of liquid acquisition require assessing mouthpart structure and function relationships; however, fluid uptake mechanisms are historically inferred from observations of structural architecture, sometimes unaccompanied with experimental evidence. Here, we report a novel method for assessing fluid-uptake abilities with butterflies (Lepidoptera) and flies (Diptera) using small amounts of liquids. Insects are fed with a 20% sucrose solution mixed with fluorescent, magnetic nanoparticles from filter papers of specific pore sizes. The crop (internal structure used for storing fluids) ismore » removed from the insect and placed on a confocal microscope. A magnet is waved by the crop to determine the presence of nanoparticles, which indicate if the insects are able to ingest fluids. This methodology is used to reveal a widespread feeding mechanism (capillary action and liquid bridge formation) that is potentially shared among Lepidoptera and Diptera when feeding from porous surfaces. In addition, this method can be used for studies of feeding mechanisms among a variety of fluid-feeding insects, including those important in disease transmission and biomimetics, and potentially other studies that involve nano- or micro-sized conduits where liquid transport requires verification.« less

Multiscale Behavior of Viscous Fluids Dynamics: Experimental Observations

NASA Astrophysics Data System (ADS)

Arciniega-Ceballos, Alejandra; Spina, Laura; Scheu, Bettina; Dingwell, Donald B.

2016-04-01

The dynamics of Newtonian fluids with viscosities of mafic to intermediate silicate melts (10-1000 Pa s) during slow decompression present multi-time scale processes. To observe these processes we have performed several experiments on silicon oil saturated with Argon gas for 72 hours, in a Plexiglas autoclave. The slow decompression, dropping from 10 MPa to ambient pressure, acting as the excitation mechanism, triggered several processes with their own distinct timescales. These processes generate complex non-stationary microseismic signals, which have been recorded with 7 high-dynamic piezoelectric sensors located along the conduit flanked by high-speed video recordings. The analysis in time and frequency of these time series and their correlation with the associated high-speed imaging enables the characterization of distinct phases and the extraction of the individual processes during the evolution of decompression of these viscous fluids. We have observed fluid-solid elastic interaction, degassing, fluid mass expansion and flow, bubble nucleation, growth, coalescence and collapse, foam building and vertical wagging. All these processes (in fine and coarse scales) are sequentially coupled in time, occur within specific pressure intervals, and exhibit a localized distribution along the conduit. Their coexistence and interactions constitute the stress field and driving forces that determine the dynamics of the conduit system. Our observations point to the great potential of this experimental approach in the understanding of volcanic conduit dynamics and volcanic seismicity.

Shear-induced orientational dynamics and spatial heterogeneity in suspensions of motile phytoplankton

PubMed Central

Barry, Michael T.; Rusconi, Roberto; Guasto, Jeffrey S.; Stocker, Roman

2015-01-01

Fluid flow, ubiquitous in natural and man-made environments, has the potential to profoundly impact the transport of microorganisms, including phytoplankton in aquatic habitats and bioreactors. Yet, the effect of ambient flow on the swimming behaviour of phytoplankton has remained poorly understood, largely owing to the difficulty of observing cell–flow interactions at the microscale. Here, we present microfluidic experiments where we tracked individual cells for four species of motile phytoplankton exposed to a spatially non-uniform fluid shear rate, characteristic of many flows in natural and artificial environments. We observed that medium-to-high mean shear rates (1–25 s−1) produce heterogeneous cell concentrations in the form of regions of accumulation and regions of depletion. The location of these regions relative to the flow depends on the cells' propulsion mechanism, body shape and flagellar arrangement, as captured by an effective aspect ratio. Species having a large effective aspect ratio accumulated in the high-shear regions, owing to shear-induced alignment of the swimming orientation with the fluid streamlines. Species having an effective aspect ratio close to unity exhibited little preferential accumulation at low-to-moderate flow rates, but strongly accumulated in the low-shear regions under high flow conditions, potentially owing to an active, behavioural response of cells to shear. These observations demonstrate that ambient fluid flow can strongly affect the motility and spatial distribution of phytoplankton and highlight the rich dynamics emerging from the interaction between motility, morphology and flow. PMID:26538558

Settling of a sphere through a fluid-fluid interface: influence of the Reynolds number

NASA Astrophysics Data System (ADS)

Pierson, Jean-Lou; Magnaudet, Jacques

2015-11-01

When a particle sediments through a horizontal fluid-fluid interface (a situation frequently encountered in oceanography as well as in coating processes), it often tows a tail of the upper fluid into the lower one. This feature is observed in both inertia- and viscosity-dominated regimes. Nevertheless the tail evolution and the particle motion are found to highly depend on the ratio of the two effects, i.e. on the Reynolds number. In this work we study numerically the settling of a sphere through a horizontal fluid-fluid interface using an Immersed Boundary Method combined with a Volume of Fluid approach. To get some more insight into the underlying physical mechanisms, we combine this computational approach with a semi-analytical description based on the concept of Darwin ''drift'' which allows us to predict the interface evolution, hence the thickness of the film encapsulating the sphere, in the two limits of Stokes flow and potential flow. This work was funded by DGA whose financial support is greatly appreciated.

Electro-osmosis of non-Newtonian fluids in porous media using lattice Poisson-Boltzmann method.

PubMed

Chen, Simeng; He, Xinting; Bertola, Volfango; Wang, Moran

2014-12-15

Electro-osmosis in porous media has many important applications in various areas such as oil and gas exploitation and biomedical detection. Very often, fluids relevant to these applications are non-Newtonian because of the shear-rate dependent viscosity. The purpose of this study was to investigate the behaviors and physical mechanism of electro-osmosis of non-Newtonian fluids in porous media. Model porous microstructures (granular, fibrous, and network) were created by a random generation-growth method. The nonlinear governing equations of electro-kinetic transport for a power-law fluid were solved by the lattice Poisson-Boltzmann method (LPBM). The model results indicate that: (i) the electro-osmosis of non-Newtonian fluids exhibits distinct nonlinear behaviors compared to that of Newtonian fluids; (ii) when the bulk ion concentration or zeta potential is high enough, shear-thinning fluids exhibit higher electro-osmotic permeability, while shear-thickening fluids lead to the higher electro-osmotic permeability for very low bulk ion concentration or zeta potential; (iii) the effect of the porous medium structure depends significantly on the constitutive parameters: for fluids with large constitutive coefficients strongly dependent on the power-law index, the network structure shows the highest electro-osmotic permeability while the granular structure exhibits the lowest permeability on the entire range of power law indices considered; when the dependence of the constitutive coefficient on the power law index is weaker, different behaviors can be observed especially in case of strong shear thinning. Copyright © 2014 Elsevier Inc. All rights reserved.

What fluids are given during air ambulance treatment of patients with trauma in the UK, and what might this mean for the future? Results from the RESCUER observational cohort study

PubMed Central

Naumann, David N; Hancox, James M; Raitt, James; Smith, Iain M; Crombie, Nicholas; Doughty, Heidi; Perkins, Gavin D; Midwinter, Mark J

2018-01-01

Objectives We investigated how often intravenous fluids have been delivered during physician-led prehospital treatment of patients with hypotensive trauma in the UK and which fluids were given. These data were used to estimate the potential national requirement for prehospital blood products (PHBP) if evidence from ongoing trials were to report clinical superiority. Setting The Regional Exploration of Standard Care during Evacuation Resuscitation (RESCUER) retrospective observational study was a collaboration between 11 UK air ambulance services. Each was invited to provide up to 5 years of data and total number of taskings during the same period. Participants Patients with hypotensive trauma (systolic blood pressure <90 mm Hg or absent radial pulse) attended by a doctor. Primary and secondary outcome measures The primary outcome was the number of patients with hypotensive trauma given prehospital fluids. Secondary outcomes were types and volumes of fluids. These data were combined with published data to estimate potential national eligibility for PHBP. Results Of 29 037 taskings, 729 (2.5%) were for patients with hypotensive trauma attended by a physician. Half were aged 21–50 years; 73.4% were male. A total of 537 out of 729 (73.7%) were given fluids. Five hundred and ten patients were given a single type of fluid; 27 received >1 type. The most common fluid was 0.9% saline, given to 486/537 (90.5%) of patients who received fluids, at a median volume of 750 (IQR 300–1500) mL. Three per cent of patients received PHBP. Estimated projections for patients eligible for PHBP at these 11 services and in the whole UK were 313 and 794 patients per year, respectively. Conclusions One in 40 air ambulance taskings were manned by physicians to retrievepatients with hypotensive trauma. The most common fluid delivered was 0.9% saline. If evidence justifies universal provision of PHBP, approximately 800 patients/year would be eligible in the UK, based on our data combined with others published. Prospective investigations are required to confirm or adjust these estimations. PMID:29362272

Polymeric nanospheres as a displacement fluid in enhanced oil recovery

NASA Astrophysics Data System (ADS)

Hendraningrat, Luky; Zhang, Julien

2015-12-01

This paper presents the investigation of using nanoscale polyacrylamide-based spheres (nanospheres) as a displacement fluid in enhanced oil recovery (EOR). Coreflood experiments were conducted to evaluate the impact of nanospheres and its concentration dispersed in model formation water on oil recovery during a tertiary oil recovery process. The coreflood results showed that nanospheres can enhance residual oil recovery in the sandstone rock samples and its concentration showed a significant impact into incremental oil. By evaluating the contact angle, it was observed that wettability alteration also might be involved in the possible oil displacement mechanism in this process together with fluid behavior and permeability to water that might divert injected fluid into unswept oil areas and enhance the residual oil recovery. These investigations promote nanospheres aqueous disperse solution as a potential displacement fluid in EOR.

Micro-poromechanics model of fluid-saturated chemically active fibrous media.

PubMed

Misra, Anil; Parthasarathy, Ranganathan; Singh, Viraj; Spencer, Paulette

2015-02-01

We have developed a micromechanics based model for chemically active saturated fibrous media that incorporates fiber network microstructure, chemical potential driven fluid flow, and micro-poromechanics. The stress-strain relationship of the dry fibrous media is first obtained by considering the fiber behavior. The constitutive relationships applicable to saturated media are then derived in the poromechanics framework using Hill's volume averaging. The advantage of this approach is that the resultant continuum model accounts for the discrete nature of the individual fibers while retaining a form suitable for porous materials. As a result, the model is able to predict the influence of micro-scale phenomena, such as the fiber pre-strain caused by osmotic effects and evolution of fiber network structure with loading, on the overall behavior and in particular, on the poromechanics parameters. Additionally, the model can describe fluid-flow related rate-dependent behavior under confined and unconfined conditions and varying chemical environments. The significance of the approach is demonstrated by simulating unconfined drained monotonic uniaxial compression under different surrounding fluid bath molarity, and fluid-flow related creep and relaxation at different loading-levels and different surrounding fluid bath molarity. The model predictions conform to the experimental observations for saturated soft fibrous materials. The method can potentially be extended to other porous materials such as bone, clays, foams and concrete.

Attenuation of Chemical Reactivity of Shale Matrixes following Scale Precipitation

NASA Astrophysics Data System (ADS)

Li, Q.; Jew, A. D.; Kohli, A. H.; Alalli, G.; Kiss, A. M.; Kovscek, A. R.; Zoback, M. D.; Brown, G. E.; Maher, K.; Bargar, J.

2017-12-01

Introduction of fracture fluids into shales initiates a myriad of fluid-rock reactions that can strongly influence migration of fluid and hydrocarbon through shale/fracture interfaces. Due to the extremely low permeability of shale matrixes, studies on chemical reactivity of shales have mostly focused on shale surfaces. Shale-fluid interactions inside within shale matrixes have not been examined, yet the matrix is the primary conduit through which hydrocarbons and potential contaminants are transmitted. To characterize changes in matrix mineralogy, porosity, diffusivity, and permeability during hydraulic stimulation, we reacted Marcellus (high clay and low carbonate) and Eagle Ford (low clay and high carbonate) shale cores with fracture fluids for 3 weeks at elevated pressure and temperature (80 oC, and 77 bars). In the carbonate-poor Marcellus system, fluid pH increased from 2 to 4, and secondary Fe(OH)3 precipitates were observed in the fluid. Sulfur X-ray fluorescence maps show that fluids had saturated and reacted with the entire 1-cm-diameter core. In the carbonate-rich Eagle Ford system, pH increased from 2 to 6 due to calcite dissolution. When additional Ba2+ and SO42- were present (log10(Q/K)=1.3), extensive barite precipitation was observed in the matrix of the Eagle Ford core (and on the surface). Barite precipitation was also observed on the surface of the Marcellus core, although to a lesser extent. In the Marcellus system, the presence of barite scale attenuated diffusivity in the matrix, as demonstrated by sharply reduced Fe leaching and much less sulfide oxidation. Systematic studies in homogeneous solution show that barite scale precipitation rates are highly sensitive to pH, salinity, and the presence of organic compounds. These findings imply that chemical reactions are not confined to shale/fluid interfaces but can penetrate into shale matrices, and that barite scale formation can clog diffusion pathways for both fluid and hydrocarbon.

Diversified seabed substrate, sediment remobilisation and fluid migration features offshore NW Greenland - new insights from marine seismic data acquisition in the Northern Nares Strait during the RV Oden cruise 2015

NASA Astrophysics Data System (ADS)

Andresen, Katrine Juul; Heirman, Katrien; Kamla, Elina; Nielsen, Tove; Rønø Clausen, Ole; Jakobsson, Martin; Mix, Alan C.; Andersen, Søren T.; Nørmark, Egon; Piotrowski, Jan A.; Knutz, Paul; Larsen, Nicolaj K.; Hogan, Kelly

2016-04-01

We present some preliminary observations from acquired seismic data from the Northern Nares Strait, NW Greenland. The studied area covers the Hall Basin in front of the Petermann Glacier and extends southward into the Kennedy Channel. It represents an area intensely affected by glacial related processes as well as deep tectonics. The data were acquired during the RV Oden cruise in late summer 2015, and thus represent valuable input to the understanding of the geological development of this scarcely accessed area of the Arctic. The data were acquired in nearly ice-free conditions and consist of >700 km 2D seismic airgun data, supplemented by high-resolution subbottom profiler data and multibeam data. The different acoustic data acquired simultaneously enable us to correlate deeper geological observations (e.g. faults observed on airgun seismics) with shallow depositional architectures (observed on subbottom profiler) and finally correlate the relatively scattered 2D interpretation with the detailed 3D seafloor morphology obtained by the multibeam. The seismic data reveal several provinces of varying seabed substrate geometry. The provinces include A: confined mini-basins; B: larger sedimentary basins; C: larger structural highs and D: "rough-and-faulted" terrain. The data also reveal a number of seismic anomalies, which indicate fluid flow and sediment remobilisation. The mini-basins are 100-600 m wide, in contrast to the larger basins which typically extend over 6-12 km. The mini-basins are characterized by a flat, smooth and continuous seafloor reflection and have an infill dominated by parallel and sub-horizontal reflections onlapping the edges of the basins. The larger basins, where the internal reflection pattern appears more diverse and less parallel, have much greater relief at the seafloor. Vertical disturbance zones typically emerging above minor structures at the floor of the mini-basins are likely related to vertical fluid migration. The zones occasionally continue to the seafloor but more often terminate within the sediments. Scattered amplitude anomalies in conjunction with sag-like depressions are further potential indications of fluid migration within the mini-basins (palaeo-pockmarks?). Slumps and mounded features within the mini-basins and at the larger structural highs indicate syn-depositional sediment remobilisation. A BSR-like reflection, potentially representing the base of gas hydrates, is occasionally observed in the larger sedimentary basins (ca. 15-20 ms TWT b.s.fl.) and at the culmination of the larger structural highs (ca. 40-50 ms TWT b.s.fl.). Cone-shaped to elongated ridges 15-20 m high and 500 m across appear to be linked with deeper structures and might indicate remobilisation of the shallow subsurface sediments potentially linked to fluid escape. Alternatively, they might be of glacial origin. Our preliminary results indicate that the basins are filled with subglacial and glaciofluvial sediments and that small-scale fluid migration and sediment remobilisation represent important processes in generating the depositional architecture in the Northern Nares Strait region. Further analyses are expected to constrain the interpretation of the observed features in detail, especially regarding the origin of the fluids.

The potentiation of the antimicrobial activities of cutting fluid preservatives by EDTA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Izzat, I.N.; Bennett, E.O.

1978-01-01

The potentiation of the antimicrobial activities of cutting fluid preservatives by EDTA was confirmed in experiments in which 500 ppm of the disodium salt of EDTA was used in combination with 12 different metalworking fluids containing 500 ppm of o-phenylphenol, tris(hydroxymethyl) nitromethane, hexahydro- 1,3,5-tris(2-hydroxyethyl)-s-triazine alone or complexed with iodine, hexahydro- 1,3,5-triethyl-s-triazine, 1-(3-chloroallyl)- 3,5,7-triaza- 1-azoniaadamantane hydrochloride, 1,2-benzisothiazolin-3-one, 4-(2-nitrobutyl) morpholine and 4,4-(2-ethyl-2-nitrotrimethylene) dimorpholine, or the sodium salt of 2-pyridinethiol- 1-oxide as a preservative. Based on a previous observation that the proper selection of the hydraulic fluid employed in the cutting machine is a major factor in controlling rancidity, the possibility of spoilagemore » control by treating the fluid with EDTA alone was also demonstrated; the EDTA had a greater beneficial effect with a synthetic coolant than with an oil emulsion. Published data on the effects of EDTA indicate that it poses no significant water pollution problems upon disposal, exhibits a low order of animal toxicity, and rarely causes human allergies. Tables and 65 references.« less

Surface Deformation Observed by InSAR due to Fluid Injection: a Test Study in the Central U.S.

NASA Astrophysics Data System (ADS)

Deng, F.; Dixon, T. H.

2017-12-01

The central and eastern U.S. has undergone a dramatic increase in seismicity over the past few years. Many of these recent earthquakes were likely induced by human activities, with underground fluid injection for oil and gas extraction being one of the main contributors. Surface deformation caused by fluid injection has been captured by GPS and InSAR observations in several areas. For example, surface uplift of up to 10 cm due to CO2 injection between 2007 and 2011 was measured by InSAR at an enhanced oil recovery site in west Texas. We are using Texas and Oklahoma as test areas to analyze the potential relationship between surface deformation, underground fluid injection and induced earthquakes. C-band SAR data from ENVISAT and Sentinel-1, and L-band SAR data from ALOS and ALOS-2 are used to form decade-long time series. Based on the surface deformation derived from the time series InSAR data, subsurface volume change and volumetric strain in an elastic half space are estimated. Seismic data provided by the USGS are used to analyze the spatial and temporal distribution pattern of earthquakes, and the potential link between surface deformation and induced earthquakes. The trigger mechanism will be combined with forward modeling to predict seismicity and assess related hazard for future study.

Experimental Observations of Multiscale Dynamics of Viscous Fluid Behavior: Implications in Volcanic Systems

NASA Astrophysics Data System (ADS)

Arciniega-Ceballos, A.; Spina, L.; Scheu, B.; Dingwell, D. B.

2015-12-01

We have investigated the dynamics of Newtonian fluids with viscosities (10-1000 Pa s; corresponding to mafic to intermediate silicate melts) during slow decompression, in a Plexiglas shock tube. As an analogue fluid we used silicon oil saturated with Argon gas for 72 hours. Slow decompression, dropping from 10 MPa to ambient pressure, acts as the excitation mechanism, initiating several processes with their own distinct timescales. The evolution of this multi-timescale phenomenon generates complex non-stationary microseismic signals, which have been recorded with 7 high-dynamic piezoelectric sensors located along the conduit. Correlation analysis of these time series with the associated high-speed imaging enables characterization of distinct phases of the dynamics of these viscous fluids and the extraction of the time and the frequency characteristics of the individual processes. We have identified fluid-solid elastic interaction, degassing, fluid mass expansion and flow, bubble nucleation, growth, coalescence and collapse, foam building and vertical wagging. All these processes (in fine and coarse scales) are sequentially coupled in time, occur within specific pressure intervals, and exhibit a localized distribution in space. Their coexistence and interactions constitute the stress field and driving forces that determine the dynamics of the system. Our observations point to the great potential of this experimental approach in the understanding of volcanic processes and volcanic seismicity.

Direction dependence of displacement time for two-fluid electroosmotic flow.

PubMed

Lim, Chun Yee; Lam, Yee Cheong

2012-03-01

Electroosmotic flow that involves one fluid displacing another fluid is commonly encountered in various microfludic applications and experiments, for example, current monitoring technique to determine zeta potential of microchannel. There is experimentally observed anomaly in such flow, namely, the displacement time is flow direction dependent, i.e., it depends if it is a high concentration fluid displacing a low concentration fluid, or vice versa. Thus, this investigation focuses on the displacement flow of two fluids with various concentration differences. The displacement time was determined experimentally with current monitoring method. It is concluded that the time required for a high concentration solution to displace a low concentration solution is smaller than the time required for a low concentration solution to displace a high concentration solution. The percentage displacement time difference increases with increasing concentration difference and independent of the length or width of the channel and the voltage applied. Hitherto, no theoretical analysis or numerical simulation has been conducted to explain this phenomenon. A numerical model based on finite element method was developed to explain the experimental observations. Simulations showed that the velocity profile and ion distribution deviate significantly from a single fluid electroosmotic flow. The distortion of ion distribution near the electrical double layer is responsible for the displacement time difference for the two different flow directions. The trends obtained from simulations agree with the experimental findings.

Direction dependence of displacement time for two-fluid electroosmotic flow

PubMed Central

Lim, Chun Yee; Lam, Yee Cheong

2012-01-01

Electroosmotic flow that involves one fluid displacing another fluid is commonly encountered in various microfludic applications and experiments, for example, current monitoring technique to determine zeta potential of microchannel. There is experimentally observed anomaly in such flow, namely, the displacement time is flow direction dependent, i.e., it depends if it is a high concentration fluid displacing a low concentration fluid, or vice versa. Thus, this investigation focuses on the displacement flow of two fluids with various concentration differences. The displacement time was determined experimentally with current monitoring method. It is concluded that the time required for a high concentration solution to displace a low concentration solution is smaller than the time required for a low concentration solution to displace a high concentration solution. The percentage displacement time difference increases with increasing concentration difference and independent of the length or width of the channel and the voltage applied. Hitherto, no theoretical analysis or numerical simulation has been conducted to explain this phenomenon. A numerical model based on finite element method was developed to explain the experimental observations. Simulations showed that the velocity profile and ion distribution deviate significantly from a single fluid electroosmotic flow. The distortion of ion distribution near the electrical double layer is responsible for the displacement time difference for the two different flow directions. The trends obtained from simulations agree with the experimental findings. PMID:22662083

Reactive oxygen species level in follicular fluid--embryo quality marker in IVF?

PubMed

Das, S; Chattopadhyay, R; Ghosh, S; Ghosh, S; Goswami, S K; Chakravarty, B N; Chaudhury, K

2006-09-01

The impact of oxidative stress in female reproduction is not clear. Contradictory reports on the effect of various oxidative stress markers on follicular fluid, oocytes and embryo quality and fertilization potential exist. The objectives of this study were to examine reactive oxygen species (ROS) levels in follicular fluid of women undergoing IVF and to relate these levels to embryo formation and quality. A total of 208 follicular fluid samples were obtained from 78 women undergoing controlled ovarian stimulation and analysed for ROS and lipid peroxidation (LPO). These samples were divided into groups I and II which represented follicular fluid containing grade III and grade II oocytes, respectively. These groups were further subdivided into groups IA, IB, IIA and IIB according to embryo quality. Subgroups IA and IIA consisted of follicular fluid samples corresponding to grade I/II embryo formation. Subgroups IB and IIB represented fertilization failure/pro-nucleolus (PN) arrest/grade III embryos. No significant correlation was observed in ROS levels on comparing groups I and II (P > 0.05). However, ROS levels were observed to be significantly different on comparing groups IA and IB (P < or = 0.01) and groups IIA and IIB (P < or = 0.05). LPO levels further supported our results. ROS levels in follicular fluid appear to play a significant role in embryo formation and quality.

A C-terminal cyclic 8-13 neurotensin fragment analog appears less exposed to neprilysin when it crosses the blood-brain barrier than the cerebrospinal fluid-brain barrier in mice.

PubMed

Van Kemmel, F M; Dubuc, I; Bourdel, E; Fehrentz, J A; Martinez, J; Costentin, J

1996-10-11

A C-terminal cyclic 8-13 neurotensin fragment analog. JMV 1193, a direct agonist of central neurotensin receptors, is able to cross both the cerebrospinal fluid-brain barrier and the blood-brain barrier. When administered intracerebroventricularly (i.c.v.), its hypothermic effect was potentiated by the enkephalinase inhibition induced either by thiorphan (simultaneous intracerebroventricular administration of 10 micrograms) or by the thiorphan prodrug. acetorphan (intravenous (i.v.) administration of 10 mg/kg). Such a potentiation was not observed when both JMV 1193 and acetorphan were administered intravenously. Therefore it appears that the sensitivity of JMV 1193 to enkephalinase depends on its route of administration. It is exposed to this peptidase after i.c.v. injection (when crossing the cerebrospinal fluid-brain barrier), while it is not after i.v. administration (when crossing the blood-brain barrier).

Interaction of anisotropic dark energy fluid with perfect fluid in the presence of cosmological term Λ

NASA Astrophysics Data System (ADS)

Singh, S. Surendra

2018-05-01

Considering the locally rotationally symmetric (LRS) Bianchi type-I metric with cosmological constant Λ, Einstein’s field equations are discussed based on the background of anisotropic fluid. We assumed the condition A = B 1 m for the metric potentials A and B, where m is a positive constant to obtain the viable model of the Universe. It is found that Λ(t) is positive and inversely proportional to time. The values of matter-energy density Ωm, dark energy density ΩΛ and deceleration parameter q are found to be consistent with the values of WMAP observations. State finder parameters and anisotropic deviation parameter are also investigated. It is also observed that the derived model is an accelerating, shearing and non-rotating Universe. Some of the asymptotic and geometrical behaviors of the derived models are investigated with the age of the Universe.

Calculation of a solid/liquid surface tension: A methodological study

NASA Astrophysics Data System (ADS)

Dreher, T.; Lemarchand, C.; Soulard, L.; Bourasseau, E.; Malfreyt, P.; Pineau, N.

2018-01-01

The surface tension of a model solid/liquid interface constituted of a graphene sheet surrounded by liquid methane has been computed using molecular dynamics in the Kirkwood-Buff formalism. We show that contrary to the fluid/fluid case, the solid/liquid case can lead to different structurations of the first fluid layer, leading to significantly different values of surface tension. Therefore we present a statistical approach that consists in running a series of molecular simulations of similar systems with different initial conditions, leading to a distribution of surface tensions from which an average value and uncertainty can be extracted. Our results suggest that these distributions converge as the system size increases. Besides we show that surface tension is not particularly sensitive to the choice of the potential energy cutoff and that long-range corrections can be neglected contrary to what we observed in the liquid/vapour interfaces. We have not observed the previously reported commensurability effect.

A corresponding-states framework for the description of the Mie family of intermolecular potentials

NASA Astrophysics Data System (ADS)

Ramrattan, N. S.; Avendaño, C.; Müller, E. A.; Galindo, A.

2015-05-01

The Mie (λr, λa) intermolecular pair potential has been suggested as an alternative to the traditional Lennard-Jones (12-6) potential for modelling real systems both via simulation and theory as its implementation leads to an accuracy and flexibility in the determination of thermophysical properties that cannot be obtained when potentials of fixed range are considered. An additional advantage of using variable-range potentials is noted in the development of coarse-grained models where, as the superatoms become larger, the effective potentials are seen to become softer. However, the larger number of parameters that characterise the Mie potential (λr, λa, σ, ɛ) can hinder a rational study of the particular effects that each individual parameter have on the observed thermodynamic properties and phase equilibria, and higher degeneracy of models is observed. Here a three-parameter corresponding states model is presented in which a cohesive third parameter α is proposed following a perturbation expansion and assuming a mean-field limit. It is shown that in this approximation the free energy of any two Mie systems sharing the same value of α will be the same. The parameter α is an explicit function of the repulsive and attractive exponents and consequently dictates the form of the intermolecular pair potential. Molecular dynamics simulations of a variety of Mie systems over a range of values of α are carried out and the solid-liquid, liquid-vapour and vapour-solid phase boundaries for the systems considered are presented. Using the simulation data, we confirm that systems of the same α exhibit conformal phase behaviour for the fluid-phase properties as well as for the solid-fluid boundary, although larger differences are noted in the solid region; these can be related to the approximations in the definition of the parameter. Furthermore, it is found that the temperature range over which the vapour-liquid envelope of a given Mie system is stable follows a linear dependency with α when expressed as the ratio of the critical-point temperature to the triple-point temperature. The limit where potentials of the Mie family will not present a stable fluid envelope is predicted in terms of the parameter α and the result is found to be in excellent agreement with previous studies. This unique relation between the fluid range and the cohesive parameter α is shown to be useful to limit the pairs of Mie exponents that can be used in coarse-grained potentials to treat real systems in order to obtain temperature ranges of stability for the fluid envelope consistent with experiment.

Perfect fluid Lagrangian and its cosmological implications in theories of gravity with nonminimally coupled matter fields

NASA Astrophysics Data System (ADS)

Avelino, P. P.; Azevedo, R. P. L.

2018-03-01

In this paper we show that the on-shell Lagrangian of a perfect fluid depends on microscopic properties of the fluid, giving specific examples of perfect fluids with different on-shell Lagrangians but with the same energy-momentum tensor. We demonstrate that if the fluid is constituted by localized concentrations of energy with fixed rest mass and structure (solitons) then the average on-shell Lagrangian of a perfect fluid is given by Lm=T , where T is the trace of the energy-momentum tensor. We show that our results have profound implications for theories of gravity where the matter Lagrangian appears explicitly in the equations of motion of the gravitational and matter fields, potentially leading to observable deviations from a nearly perfect cosmic microwave background black body spectrum: n -type spectral distortions, affecting the normalization of the spectral energy density. Finally, we put stringent constraints on f (R ,Lm) theories of gravity using the COBE-FIRAS measurement of the spectral radiance of the cosmic microwave background.

Experimental Studies of Hydrocarbon Flame Phenomena: Enabling Combustion Control

DTIC Science & Technology

2016-07-30

early discussions on the “ionic or electric wind ’ was a term used to describe a fluid flow driven only from the difference in electric potentials at two...locations, Chattock [2] and Robinson [11]. 4 To produce ionic wind , a high potential combined with a favorable electrode geometry, forms an...the secondary electrode. Beyond the formation of the ionic wind , it has been observed that high potentials in ambient air can produce ozone

Working memory - not processing speed - mediates fluid intelligence deficits associated with attention deficit/hyperactivity disorder symptoms.

PubMed

Brydges, Christopher R; Ozolnieks, Krista L; Roberts, Gareth

2017-09-01

Attention deficit/hyperactivity disorder (ADHD) is a psychological condition characterized by inattention and hyperactivity. Cognitive deficits are commonly observed in ADHD patients, including impaired working memory, processing speed, and fluid intelligence, the three of which are theorized to be closely associated with one another. In this study, we aimed to determine if decreased fluid intelligence was associated with ADHD, and was mediated by deficits in working memory and processing speed. This study tested 142 young adults from the general population on a range of working memory, processing speed, and fluid intelligence tasks, and an ADHD self-report symptoms questionnaire. Results showed that total and hyperactive ADHD symptoms correlated significantly and negatively with fluid intelligence, but this association was fully mediated by working memory. However, inattentive symptoms were not associated with fluid intelligence. Additionally, processing speed was not associated with ADHD symptoms at all, and was not uniquely predictive of fluid intelligence. The results provide implications for working memory training programs for ADHD patients, and highlight potential differences between the neuropsychological profiles of ADHD subtypes. © 2015 The British Psychological Society.

Biphasic investigation of contact mechanics in natural human hips during activities

PubMed Central

Hua, Xijin; Jin, Zhongmin; Fisher, John; Wilcox, Ruth K

2014-01-01

The aim of this study was to determine the cartilage contact mechanics and the associated fluid pressurisation of the hip joint under eight daily activities, using a three-dimensional finite element hip model with biphasic cartilage layers and generic geometries. Loads with spatial and temporal variations were applied over time and the time-dependent performance of the hip cartilage during walking was also evaluated. It was found that the fluid support ratio was over 90% during the majority of the cycles for all the eight activities. A reduced fluid support ratio was observed for the time at which the contact region slid towards the interior edge of the acetabular cartilage, but these occurred when the absolute level of the peak contact stress was minimal. Over 10 cycles of gait, the peak contact stress and peak fluid pressure remained constant, but a faster process of fluid exudation was observed for the interior edge region of the acetabular cartilage. The results demonstrate the excellent function of the hip cartilage within which the solid matrix is prevented from high levels of stress during activities owing to the load shared by fluid pressurisation. The findings are important in gaining a better understanding of the hip function during daily activities, as well as the pathology of hip degeneration and potential for future interventions. They provide a basis for future subject-specific biphasic investigations of hip performance during activities. PMID:24898443

First Observations of Boron on Mars and Implications for Gale Crater Geochemistry

NASA Astrophysics Data System (ADS)

Gasda, P. J.; Haldeman, E. B.; Wiens, R. C.; Rapin, W.; Frydenvang, J.; Maurice, S.; Clegg, S. M.; Delapp, D.; Sanford, V.; McInroy, R.

2016-12-01

Borates are potentially important precursor materials for the origin of life on Earth. It has been shown that borates are required to stabilize ribose, a component of RNA, when produced by the formose reaction, a prebiotically plausible mechanism to produce ribose from formaldehyde. Evaporites, including borates, also shed light on the history of aqueous activity on Mars. The ChemCam instrument onboard the NASA Curiosity rover provides quantitative elemental compositions of targets in Gale Crater, Mars, using laser-induced breakdown spectroscopy (LIBS). Laboratory observations of Fe-free targets indicate that a LIBS emission line is visible with as little as 10 ppm B. We have observed B lines in 23 calcium sulfate veins in Gale Crater: 3 in Yellowknife Bay and 20 in the Murray lacustrine mudstone and the Stimson eolian sandstone units since sol 727, as Curiosity arrived at the base of Mt. Sharp, a 5 km sedimentary mound in the center of Gale Crater. To calibrate these observations, samples composed of borates diluted with Hawaiian basalt have been analyzed using the LANL ChemCam engineering model. Preliminary results show that the Gale Crater veins have between 10-100 ppm B. One possible explanation for borates in veins is that Gale Lake evaporated, depositing evaporites, including borates. Later, Gale Crater was partially buried and its lacustrine and overlying eolian units were lithified and fractured. Water flowed through the evaporite-rich layers, partially dissolving them. Fluid moved through the fractures, re-precipitating the borates and sulfates as veins. ChemCam cannot directly determine mineralogy, but B is likely present as borax as the dominate borate phase in these veins, based on previous estimates of vein fluid temperature. Borates forming in this environment tend to precipitate from mildly alkaline fluids. The fluid temperature and pH implies these veins were potentially habitable environments.

Influence of Anti-inflammatory Drugs on the Rheological Properties of Synovial Fluid and Its Components

NASA Astrophysics Data System (ADS)

Krause, Wendy E.; Klossner, Rebecca R.; Liang, Jing; Colby, Ralph H.

2006-03-01

The polyelectrolyte hyaluronic acid (HA, hyaluronan), its interactions with anti-inflammatory drugs and other biopolymers, and its role in synovial fluid are being studied. We are investigating the rheological properties of sodium hyaluronate (NaHA) solutions and an experimental model of synovial fluid (comprised of NaHA, and the plasma proteins albumin and γ-globulins). Steady shear measurements on bovine synovial fluid, the synovial fluid model, and plasma protein solutions indicate that the fluids are rheopectic (stress increases with time under steady shear). In addition, the influence of anti-inflammatory agents on these solutions is being explored. Initial results indicate that D-penicillamine and hydroxychloroquine (HCQ) affect the rheology of the synovial fluid model and its components. While HCQ has no effect on the viscosity of NaHA solutions, it inhibits/suppresses the observed rheopexy of the synovial fluid model and plasma protein solutions. In contrast, D-penicillamine has a complex, time dependent effect on the viscosity of NaHA solutions,---reducing the zero shear rate viscosity of a 3 mg/mL NaHA (in phosphate buffered saline) by ca. 40% after 44 days. The potential implications of these results will be discussed.

Osmotic generation of 'anomalous' fluid pressures in geological environments

USGS Publications Warehouse

Neuzii, C.E.

2000-01-01

Osmotic pressures are generated by differences in chemical potential of a solution across a membrane. But whether osmosis can have a significant effect on the pressure of fluids in geological environments has been controversial, because the membrane properties of geological media are poorly understood. 'Anomalous' pressures - large departures from hydrostatic pressure that are not explicable in terms of topographic or fluid-density effects are widely found in geological settings, and are commonly considered to result from processes that alter the pore or fluid volume, which in turn implies crustal changes happening at a rate too slow to observe directly. Yet if osmosis can explain some anomalies, there is no need to invoke such dynamic geological processes in those cases. Here I report results of a nine- year in situ measurement of fluid pressures and solute concentrations in shale that are consistent with the generation of large (up to 20 MPa) osmotic-pressure anomalies which could persist for tens of millions of years. Osmotic pressures of this magnitude and duration can explain many of the pressure anomalies observed in geological settings. The require, however, small shale porosity and large contrasts in the amount of dissolved solids in the pore waters - criteria that may help to distinguish between osmotic and crystal-dynamic origins of anomalous pressures.

CLASH-VLT: CONSTRAINTS ON THE DARK MATTER EQUATION OF STATE FROM ACCURATE MEASUREMENTS OF GALAXY CLUSTER MASS PROFILES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sartoris, Barbara; Borgani, Stefano; Girardi, Marisa

2014-03-01

A pressureless scenario for the dark matter (DM) fluid is a widely adopted hypothesis, despite the absence of direct observational evidence. According to general relativity, the total mass-energy content of a system shapes the gravitational potential well, but different test particles perceive this potential in different ways depending on their properties. Cluster galaxy velocities, being <

Wave radiation and diffraction by a two-dimensional floating body with an opening near a side wall

NASA Astrophysics Data System (ADS)

Zhang, Hong-sheng; Zhou, Hua-wei

2013-08-01

The radiation and diffraction problem of a two-dimensional rectangular body with an opening floating on a semi-infinite fluid domain of finite water depth is analysed based on the linearized velocity potential theory through an analytical solution procedure. The expressions for potentials are obtained by the method of variation separation, in which the unknown coefficients are determined by the boundary condition and matching requirement on the interface. The effects of the position of the hole and the gap between the body and side wall on hydrodynamic characteristics are investigated. Some resonance is observed like piston motion in a moon pool and sloshing in a closed tank because of the existence of restricted fluid domains.

Hydroxyapatite formation on titania-based materials in a solution mimicking body fluid: Effects of manganese and iron addition in anatase.

PubMed

Shin, Euisup; Kim, Ill Yong; Cho, Sung Baek; Ohtsuki, Chikara

2015-03-01

Hydroxyapatite formation on the surfaces of implanted materials plays an important role in osteoconduction of bone substitutes in bone tissues. Titania hydrogels are known to instigate hydroxyapatite formation in a solution mimicking human blood plasma. To date, the relationship between the surface characteristics of titania and hydroxyapatite formation on its surface remains unclear. In this study, titania powders with varying surface characteristics were prepared by addition of manganese or iron to examine hydroxyapatite formation in a type of simulated body fluid (Kokubo solution). Hydroxyapatite formation was monitored by observation of deposited particles with scale-like morphology on the prepared titania powders. The effect of the titania surface characteristics, i.e., crystal structure, zeta potential, hydroxy group content, and specific surface area, on hydroxyapatite formation was examined. Hydroxyapatite formation was observed on the surface of titania powders that were primarily anatase, and featured a negative zeta potential and low specific surface areas irrespective of the hydroxy group content. High specific surface areas inhibited the formation of hydroxyapatite because calcium and phosphate ions were mostly consumed by adsorption on the titania surface. Thus, these surface characteristics of titania determine its osteoconductivity following exposure to body fluid. Copyright © 2014 Elsevier B.V. All rights reserved.

Synchronization crossover of polariton condensates in weakly disordered lattices

NASA Astrophysics Data System (ADS)

Ohadi, H.; del Valle-Inclan Redondo, Y.; Ramsay, A. J.; Hatzopoulos, Z.; Liew, T. C. H.; Eastham, P. R.; Savvidis, P. G.; Baumberg, J. J.

2018-05-01

We demonstrate that the synchronization of a lattice of solid-state condensates when intersite tunneling is switched on depends strongly on the weak local disorder. This finding is vital for implementation of condensate arrays as computation devices. The condensates here are nonlinear bosonic fluids of exciton-polaritons trapped in a weakly disordered Bose-Hubbard potential, where the nearest-neighboring tunneling rate (Josephson coupling) can be dynamically tuned. The system can thus be tuned from a localized to a delocalized fluid as the number density or the Josephson coupling between nearest neighbors increases. The localized fluid is observed as a lattice of unsynchronized condensates emitting at different energies set by the disorder potential. In the delocalized phase, the condensates synchronize and long-range order appears, evidenced by narrowing of momentum and energy distributions, new diffraction peaks in momentum space, and spatial coherence between condensates. Our paper identifies similarities and differences of this nonequilibrium crossover to the traditional Bose-glass to superfluid transition in atomic condensates.

Optofluidic two-dimensional grating volume refractive index sensor.

PubMed

Sarkar, Anirban; Shivakiran Bhaktha, B N; Khastgir, Sugata Pratik

2016-09-10

We present an optofluidic reservoir with a two-dimensional grating for a lab-on-a-chip volume refractive index sensor. The observed diffraction pattern from the device resembles the analytically obtained fringe pattern. The change in the diffraction pattern has been monitored in the far-field for fluids with different refractive indices. Reliable measurements of refractive index variations, with an accuracy of 6×10^-3 refractive index units, for different fluids establishes the optofluidic device as a potential on-chip tool for monitoring dynamic refractive index changes.

Detectability of primordial gravitational waves produced in bouncing models

NASA Astrophysics Data System (ADS)

Pinto-Neto, Nelson; Scardua, Arthur

2017-06-01

It is widely known that bouncing models with a dust hydrodynamical fluid satisfying cs2=pd/ρd≈0 , where cs , pd , ρd are the sound velocity, pressure, and energy density of the dust fluid, respectively, have almost scale invariant spectrum of scalar perturbations and negligible primordial gravitational waves. We investigate whether adding another fluid with 1 /3

Geochemical and Visual Indicators of Hydrothermal Fluid Flow through a Sediment-Hosted Volcanic Ridge in the Central Bransfield Basin (Antarctica)

PubMed Central

Aquilina, Alfred; Connelly, Douglas P.; Copley, Jon T.; Green, Darryl R. H.; Hawkes, Jeffrey A.; Hepburn, Laura E.; Huvenne, Veerle A. I.; Marsh, Leigh; Mills, Rachel A.; Tyler, Paul A.

2013-01-01

In the austral summer of 2011 we undertook an investigation of three volcanic highs in the Central Bransfield Basin, Antarctica, in search of hydrothermal activity and associated fauna to assess changes since previous surveys and to evaluate the extent of hydrothermalism in this basin. At Hook Ridge, a submarine volcanic edifice at the eastern end of the basin, anomalies in water column redox potential (Eh) were detected close to the seafloor, unaccompanied by temperature or turbidity anomalies, indicating low-temperature hydrothermal discharge. Seepage was manifested as shimmering water emanating from the sediment and from mineralised structures on the seafloor; recognisable vent endemic fauna were not observed. Pore fluids extracted from Hook Ridge sediment were depleted in chloride, sulfate and magnesium by up to 8% relative to seawater, enriched in lithium, boron and calcium, and had a distinct strontium isotope composition (87Sr/86Sr  = 0.708776 at core base) compared with modern seawater (87Sr/86Sr ≈0.70918), indicating advection of hydrothermal fluid through sediment at this site. Biogeochemical zonation of redox active species implies significant moderation of the hydrothermal fluid with in situ diagenetic processes. At Middle Sister, the central ridge of the Three Sisters complex located about 100 km southwest of Hook Ridge, small water column Eh anomalies were detected but visual observations of the seafloor and pore fluid profiles provided no evidence of active hydrothermal circulation. At The Axe, located about 50 km southwest of Three Sisters, no water column anomalies in Eh, temperature or turbidity were detected. These observations demonstrate that the temperature anomalies observed in previous surveys are episodic features, and suggest that hydrothermal circulation in the Bransfield Strait is ephemeral in nature and therefore may not support vent biota. PMID:23359806

Ultrasonication effect on thermophysical properties of Al2O3 nanofluids

NASA Astrophysics Data System (ADS)

Shah, Janki; Ranjan, Mukesh; Gupta, Sanjeev K.; Sonvane, Yogesh

2018-04-01

In this work, we studied the thermal conductivity and viscosity of alumina nanofluids for their excellent thermophysical properties. Here we considered the bath sonication time effects on thermal conductivity, viscosity and zeta potential of alumina nanofluid with different concentration (0.2, 0.3, 0.4, 0.5 Vol.%). We observed that the thermal conductivity of the nanofluids increased nonlinearly with an increased sonication time/energy as well as viscosity decreased. An enhancement of the thermal conductivity and viscosity at higher particle concentration is also observed. The results indicate that thermal properties of Al2O3 nanofluid enhances as the sonication time increases and prove Al2O3 nanofluid is one of the best thermostable heat transfer fluids compared to conventional cooling fluids.

Potential of fluid-attenuated inversion recovery (FLAIR) in identification of temporomandibular joint effusion compared with T2-weighted images.

PubMed

Imoto, Kenichi; Otonari-Yamamoto, Mika; Nishikawa, Keiichi; Sano, Tsukasa; Yamamoto, Aya

2011-08-01

The purpose of this study was to determine the potential of fluid-attenuated inversion recovery (FLAIR) sequence images in the identification of joint effusion (JE) compared with T2-weighted images. A total of 31 joints (28 patients) with JE were investigated by magnetic resonance imaging (MRI). Regions of interest were placed over JE, cerebrospinal fluid (CSF), and gray matter (GM) on T2-weighted and FLAIR images and their signal intensities compared. The signal intensity ratios (SIRs) of JE and CSF were calculated with GM as the reference point. The Pearson product-moment correlation coefficient was used for the statistical analysis. The SIR of JE showed a strong correlation between T2-weighted and FLAIR images. However, no correlation was observed for CSF. The average suppression ratio for JE was lower than that for CSF. MRI using FLAIR sequences revealed that JE was not just water content, but a fluid accumulation containing elements such as protein. Further studies are needed, and FLAIR sequences could be useful for the diagnosis of pain and symptoms of the temporomandibular joint (TMJ). Copyright © 2011 Mosby, Inc. All rights reserved.

Fluid-Solid Interaction and Multiscale Dynamic Processes: Experimental Approach

NASA Astrophysics Data System (ADS)

Arciniega-Ceballos, Alejandra; Spina, Laura; Mendo-Pérez, Gerardo M.; Guzmán-Vázquez, Enrique; Scheu, Bettina; Sánchez-Sesma, Francisco J.; Dingwell, Donald B.

2017-04-01

The speed and the style of a pressure drop in fluid-filled conduits determines the dynamics of multiscale processes and the elastic interaction between the fluid and the confining solid. To observe this dynamics we performed experiments using fluid-filled transparent tubes (15-50 cm long, 2-4 cm diameter and 0.3-1 cm thickness) instrumented with high-dynamic piezoelectric sensors and filmed the evolution of these processes with a high speed camera. We analyzed the response of Newtonian fluids to slow and sudden pressure drops from 3 bar-10 MPa to ambient pressure. We used fluids with viscosities of mafic to intermediate silicate melts of 1 to 1000 Pa s and water. The processes observed are fluid mass expansion, fluid flow, jets, bubbles nucleation, growth, coalescence and collapse, degassing, foam building at the surface and vertical wagging. All these processes (in fine and coarse scales) are triggered by the pressure drop and are sequentially coupled in time while interacting with the solid. During slow decompression, the multiscale processes are recognized occurring within specific pressure intervals, and exhibit a localized distribution along the conduit. In this, degassing predominates near the surface and may present piston-like oscillations. In contrast, during sudden decompression the fluid-flow reaches higher velocities, the dynamics is dominated by a sequence of gas-packet pulses driving jets of the gas-fluid mixture. The evolution of this multiscale phenomenon generates complex non-stationary microseismic signals recorded along the conduit. We discuss distinctive characteristics of these signals depending on the decompression style and compare them with synthetics. These synthetics are obtained numerically under an averaging modeling scheme, that accounted for the stress-strain of the cyclic dynamic interaction between the fluid and the solid wall, assuming an incompressible and viscous fluid that flows while the elastic solid responds oscillating. Analysis of time series, both experimental and synthetics, synchronized with high-speed imaging enables the explanation and interpretation of distinct phases of the dynamics of these fluids and the extraction of time and frequency characteristics of the individual processes. We observed that the effects of both, pressure drop triggering function and viscosity, control the characteristics of the micro-signals in time and frequency. This suggests the great potential that experimental and numerical approaches provide to untangle from field volcanic seismograms the multiscale processes of the stress field, driving forces and fluid-rock interaction that determine the volcanic conduit dynamics.

Physics based simulation of seismicity induced in the vicinity of a high-pressure fluid injection

NASA Astrophysics Data System (ADS)

McCloskey, J.; NicBhloscaidh, M.; Murphy, S.; O'Brien, G. S.; Bean, C. J.

2013-12-01

High-pressure fluid injection into subsurface is known, in some cases, to induce earthquakes in the surrounding volume. The increasing importance of ';fracking' as a potential source of hydrocarbons has made the seismic hazard from this effect an important issue the adjudication of planning applications and it is likely that poor understanding of the process will be used as justification of refusal of planning in Ireland and the UK. Here we attempt to understand some of the physical controls on the size and frequency of induced earthquakes using a physics-based simulation of the process and examine resulting earthquake catalogues The driver for seismicity in our simulations is identical to that used in the paper by Murphy et al. in this session. Fluid injection is simulated using pore fluid movement throughout a permeable layer from a high-pressure point source using a lattice Boltzmann scheme. Diffusivities and frictional parameters can be defined independently at individual nodes/cells allowing us to reproduce 3-D geological structures. Active faults in the model follow a fractal size distribution and exhibit characteristic event size, resulting in a power-law frequency-size distribution. The fluid injection is not hydraulically connected to the fault (i.e. fluid does not come into physical contact with the fault); however stress perturbations from the injection drive the seismicity model. The duration and pressure-time function of the fluid injection can be adjusted to model any given injection scenario and the rate of induced seismicity is controlled by the local structures and ambient stress field as well as by the stress perturbations resulting from the fluid injection. Results from the rate and state fault models of Murphy et al. are incorporated to include the effect of fault strengthening in seismically quite areas. Initial results show similarities with observed induced seismic catalogues. Seismicity is only induced where the active faults have not been rotated far from the ambient stress field; the ';structural keel' provided by the geology suppresses induction since the fluid induced stress levels are much smaller than the breaking strain of the host rocks. In addition, we observe a systematic increase in observed biggest magnitude event with time during any injection indicating that in none of our simulations is the maximum magnitude event observed; mmax is in fact not estimable from any of our simulations and is unlikely to be observed in any given injection scenario.

Two-Phase Flow Simulations through Experimentally Studied Porous Media Analogies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crandall, D.M.; Ahmadi, G.; Smith, D.H.

2007-07-01

The amount of CO2 that can be sequestered in deep brine reservoirs is dependant on fluid-fluid-solid interactions within heterogeneous porous media. Displacement of an in-place fluid by a less viscous invading fluid does not displace 100% of the defending fluid, due to capillary and viscous fingering. This has been studied experimentally and numerically with the use of pore-throat flow cells and pore-level models, respectively, in the last two decades. This current work solves the full Navier-Stokes and continuity equations in a random pore-throat geometry using the Volume of Fluid (VOF) method. To verify that the VOF model can be accuratelymore » applied within narrow apertures, qualitative agreement with the well-documented phenomenon of viscous fingering in a Hele-Shaw cell is first presented. While this motion is similar to the fingering observed in geological media, the random structure of rock restricts flow patterns not captured by flow in Hele-Shaw cells. To mimic this heterogeneous natural geometry, a novel experimental flowcell was created. Experiments of constant-rate injection of air into the water saturated model are described. This situation, where a non-wetting, invading fluid displaces a surface-wetting, more-viscous fluid, is known as drainage. As the injection flow rate was increased, a change from stable displacement fronts to dendritic fingering structures was observed, with a corresponding decrease in the fractal dimension of the interface and a decrease in the final saturation of invading air. Predictions of the VOF computational modeling within the same flowcell geometry are then shown to be in good agreement with the experimental results. Percent saturation and the fractal dimension of the invading fluid were calculated from the numerical model and shown to be similar to the experimental findings for air invasion of a watersaturated domain. The fluid properties (viscosity and density) were than varied and the viscosity ratio and capillary number of the fluids were shown to affect the percent of displaced fluid, with lower capillary number and higher viscosity ratio displacing a greater amount of the wetting fluid. Displacement of a non-wetting, in-place fluid by a less viscous, wetting fluid (the case of imbibition; contact angle > 90°) is then studied with the numerical model. The invading fluid is shown to preferentially move into small throats and displace a larger percent of the in-place fluid than observed in the drainage case. The interface was also observed to have a higher fractal dimension, closer to 2. These results highlight the potential for greater fundamental understanding of liquid-gas-solid interactions in heterogeneous, porous media that can be obtained from computational fluid dynamics (CFD). Situations, which are difficult to experimentally study, can be examined with CFD in a manner that more accurately accounts for the geological conditions relevant to CO2 sequestration. This allows for greater accuracy in the prediction of storage capacity within known geological structures. This study shows that as the contact angle between the invading fluid and the defending fluid increase, a greater portion of the porous medium is invaded. Thus, a greater portion of CO2 can be sequestered in reservoirs that are not strongly water wet. Low flow rates are shown to increase the final percent saturation of the invading fluid as well, regardless of wetting conditions.« less

Critical parameters of hard-core Yukawa fluids within the structural theory

NASA Astrophysics Data System (ADS)

Bahaa Khedr, M.; Osman, S. M.

2012-10-01

A purely statistical mechanical approach is proposed to account for the liquid-vapor critical point based on the mean density approximation (MDA) of the direct correlation function. The application to hard-core Yukawa (HCY) fluids facilitates the use of the series mean spherical approximation (SMSA). The location of the critical parameters for HCY fluid with variable intermolecular range is accurately calculated. Good agreement is observed with computer simulation results and with the inverse temperature expansion (ITE) predictions. The influence of the potential range on the critical parameters is demonstrated and the universality of the critical compressibility ratio is discussed. The behavior of the isochoric and isobaric heat capacities along the equilibrium line and the near vicinity of the critical point is discussed in details.

The CFVib Experiment: Control of Fluids in Microgravity with Vibrations

NASA Astrophysics Data System (ADS)

Fernandez, J.; Sánchez, P. Salgado; Tinao, I.; Porter, J.; Ezquerro, J. M.

2017-10-01

The Control of Fluids in Microgravity with Vibrations (CFVib) experiment was selected for the 2016 Fly Your Thesis! programme as part of the 65th ESA Parabolic Flight Campaign. The aim of the project is to observe the potentially complex behaviour of vibrated liquids in weightless environments and to investigate the extent to which small-amplitude vibrations can be used to influence and control this behaviour. Piezoelectric materials are used to generate high-frequency vibrations to drive surface waves and large-scale reorientation of the interface. The theory of vibroequilibria, which treats the quasi-stationary surface configurations achieved by this reorientation, was used to predict interesting parameter regimes and interpret fluid behaviour. Here we describe the scientific motivation, objectives, and design of the experiment.

Coexistence and interfacial properties of a triangle-well mimicking the Lennard-Jones fluid and a comparison with noble gases.

PubMed

Bárcenas, M; Reyes, Y; Romero-Martínez, A; Odriozola, G; Orea, P

2015-02-21

Coexistence and interfacial properties of a triangle-well (TW) fluid are obtained with the aim of mimicking the Lennard-Jones (LJ) potential and approach the properties of noble gases. For this purpose, the scope of the TW is varied to match vapor-liquid densities and surface tension. Surface tension and coexistence curves of TW systems with different ranges were calculated with replica exchange Monte Carlo and compared to those data previously reported in the literature for truncated and shifted (STS), truncated (ST), and full Lennard-Jones (full-LJ) potentials. We observed that the scope of the TW potential must be increased to approach the STS, ST, and full-LJ properties. In spite of the simplicity of TW expression, a remarkable agreement is found. Furthermore, the variable scope of the TW allows for a good match of the experimental data of argon and xenon.

Revised estimates of the ocean energy cycle and the key role of the western boundary in the APE to KE conversion due to high latitude cooling

NASA Astrophysics Data System (ADS)

Tailleux, Remi

2014-05-01

The ocean energy cycle is a key aspect of the ocean circulation, and has been traditionally framed in terms of Lorenz (1955) theory of available potential energy. However, the latest available observational estimate of the ocean energy cycle is due to Oort and Peixoto (1994) and is now very dated. Moreover, the latter estimate relies on the so-called Lorenz quasi-geostrophic approximation, which is known to be very inaccurate. Oort and Peixoto also neglected the internal energy contribution to the total available potential energy, which is now understood to be far from negligible, and to account for up to 40 percent of the total APE. The purpose of this work is to revisit observational estimates of the ocean energy cycle by taking advantage of a newly developed APE framework, as well as of the many new available observational products for temperature, salinity and surface buoyancy fluxes. In contrast to previous frameworks, our APE framework (Tailleux, 2013) relies on a physically well defined local APE definition, which is valid for a binary Boussinesq or fully compressible fluid with an arbitrary nonlinear equation of state. As part of our approach, we also developed a new fast and accurate way to construct Lorenz reference state of minimum potential energy, based on using the joint probability distribution function for temperature and salinity. Results will be presented for a variety of observational products, as well as for the ECCO2 ocean state estimate. The role of the deep western boundary as the place where the APE created by high latitude is converted into kinetic energy (KE) as part of driving the Atlantic meridional overturning circulation will be emphasized. References: Tailleux, R., 2013: Available potential energy density for a multicomponent Boussinesq fluid with arbitrary nonlinear equation of state.J. Fluid Mech., 735,499-518. Sijp, W., J.M.Gregory, R. Tailleux, P. Spence, 2012: The key role of the western boundary in linking the AMOC strength to the North South pressure gradient. J. Phys. Oceanogr., 42, 628-643.

Why do team-sport athletes drink fluid in excess when exercising in cool conditions?

PubMed

Bargh, Melissa J; King, Roderick F G J; Gray, Michael P; Jones, Ben

2017-03-01

This study assessed the potential physiological and perceptual drivers of fluid intake and thirst sensation during intermittent exercise. Ten male rugby players (17 ± 1 years, stature: 179.1 ± 4.2 cm, body mass (BM): 81.9 ± 8.1 kg) participated in six 6-min small-sided games, interspersed with 2 min rest, where fluid intake was ad libitum during rest periods. Pre- and postmeasurements of BM, subjective ratings (thirst, thermal comfort, thermal sensation, mouth dryness), plasma osmolality (POsm), serum sodium concentration (S[Na + ]), haematocrit and haemoglobin (to calculate plasma volume change; PV) were taken. Fluid intake was measured during rest periods. BM change was -0.17 ± 0.59% and fluid intake was 0.88 ± 0.38 L. Pre- to post-POsm decreased (-3.1 ± 2.3 mOsm·kg -1 ; p = 0.002) and S[Na + ] remained similar (-0.3 ± 0.7 mmol·L -1 , p = 0.193). ΔPV was 5.84 ± 3.65%. Fluid intake displayed a relationship with pre-POsm (r = -0.640, p = 0.046), prethermal comfort (r = 0.651; p = -0.041), ΔS[Na + ] (r = 0.816, p = 0.004), and ΔPV (r = 0.740; p = 0.014). ΔThirst sensation displayed a relationship with premouth dryness (r = 0.861, p = 0.006) and Δmouth dryness (r = 0.878, p = 0.004). Yet a weak positive relationship between Δthirst sensation and fluid intake was observed (r = 0.085, p = 0.841). These data observed in an ambient temperature of 13.6 ± 0.9 °C, suggest team-sport athletes drink in excess of fluid homeostasis requirements and thirst sensation in cool conditions; however, this was not influenced by thermal discomfort.

Archaeal Viruses Contribute to the Novel Viral Assemblage Inhabiting Oceanic, Basalt-Hosted Deep Subsurface Crustal Fluids

NASA Astrophysics Data System (ADS)

Nigro, O. D.; Rappe, M. S.; Jungbluth, S.; Lin, H. T.; Steward, G.

2015-12-01

Fluids contained in the basalt-hosted deep subsurface of the world's oceans represent one of the most inaccessible and understudied biospheres on earth. Recent improvements in sampling infrastructure have allowed us to collect large volumes of crustal fluids (~104 L) from Circulation Obviation Retrofit Kits (CORKs) placed in boreholes located on the eastern flank of the Juan de Fuca Ridge (JdFR). We detected viruses within these fluids by TEM and epifluorescence microscopy in samples collected from 2010 to 2014. Viral abundance, determined by epifluorescence counts, indicated that concentrations of viruses in subsurface basement fluids (~105 ml-1) are lower than the overlying seawater, but are higher in abundance than microbial cells in the same samples. Analysis of TEM images revealed distinct viral morphologies (rod and spindle-shaped) that resemble the morphologies of viral families infecting archaea. There are very few, if any, direct observations of these viral morphologies in marine samples, although they have been observed in enrichment cultures and their signature genes detected in metagenomic studies from hydrothermal vents and marine sediments. Analysis of metagenomes from the JdFR crustal fluids revealed sequences with homology to archaeal viruses from the rudiviridae, bicaudaviridae and fuselloviridae. Prokaryotic communities in fluids percolating through the basaltic basement rock of the JdFR flank are distinct from those inhabiting the overlying sediments and seawater. Similarly, our data support the idea that the viral assemblage in these fluids is distinct from viral assemblages in other marine and terrestrial aquatic environments. Our data also suggest that viruses contribute to the mortality of deep subsurface prokaryotes through cell lysis, and viruses may alter the genetic potential of their hosts through the processes of lysogenic conversion and horizontal gene transfer.

Seismic evidence for deep fluid circulation in the overriding plate of subduction zones

NASA Astrophysics Data System (ADS)

Tauzin, B.; Reynard, B.; Bodin, T.; Perrillat, J. P.; Debayle, E.

2015-12-01

In subduction zones, non-volcanic tremors are associated with fluid circulations (Obara, 2002). Their sources are often located on the interplate boundary (Rogers and Dragert, 2003; Shelly et al, 2006; La Rocca, 2009), consistent with fluids released by the dehydration of subducted plates (Hacker et al., 2003). Reports of tremors in the overriding continental crust of several subduction zones in the world (Kao et al., 2005; Payero et al., 2008; Ide, 2012) suggest fluid circulation at shallower depths but potential fluid paths are poorly documented. Here we obtained seismic observations from receiver functions that evidence the close association between the shallow tremor zone, electrical conductivity, and tectonic features of the Cascadia overriding plate. A seismic discontinuity near 15 km depth in the crust of the overriding North American plate is attributed to the Conrad discontinuity. This interface is segmented, and its interruption is spatially correlated with conductive regions and shallow swarms of seismicity and non-volcanic tremors. These observations suggest that shallow fluid circulation, tremors and seismicity are controlled by fault zones limiting blocks of accreted terranes in the overriding plate (Brudzinski and Allen, 2007). These zones constitute fluid "escape" routes that may contribute unloading fluid pressure on the megathrust. Obara, K. (2002). Science, 296, 1679-1681. Rogers, G., & Dragert, H. (2003). Science, 300, 1942-1943. Shelly, D. R., et al. (2006). Nature, 442, 188-191. La Rocca, M., et al. (2009). Science, 323, 620-623. Kao, H., et al. (2005). Nature, 436, 841-844. Payero, J. S., et al. (2008). Geophysical Research Letters, 35. Ide, S. (2012). Journal of Geophysical Research: Solid Earth, 117. Brudzinski, M. R., & Allen, R. M. (2007). Geology, 35, 907-910.

Fluids of the Lower Crust: Deep Is Different

NASA Astrophysics Data System (ADS)

Manning, Craig E.

2018-05-01

Deep fluids are important for the evolution and properties of the lower continental and arc crust in tectonically active settings. They comprise four components: H2O, nonpolar gases, salts, and rock-derived solutes. Contrasting behavior of H2O-gas and H2O-salt mixtures yields immiscibility and potential separation of phases with different chemical properties. Equilibrium thermodynamic modeling of fluid-rock interaction using simple ionic species known from shallow-crustal systems yields solutions too dilute to be consistent with experiments and resistivity surveys, especially if CO2 is added. Therefore, additional species must be present, and H2O-salt solutions likely explain much of the evidence for fluid action in high-pressure settings. At low salinity, H2O-rich fluids are powerful solvents for aluminosilicate rock components that are dissolved as polymerized clusters. Addition of salts changes solubility patterns, but aluminosilicate contents may remain high. Fluids with Xsalt = 0.05 to 0.4 in equilibrium with model crustal rocks have bulk conductivities of 10‑1.5 to 100 S/m at porosity of 0.001. Such fluids are consistent with observed conductivity anomalies and are capable of the mass transfer seen in metamorphic rocks exhumed from the lower crust.

Biphasic investigation of contact mechanics in natural human hips during activities.

PubMed

Li, Junyan; Hua, Xijin; Jin, Zhongmin; Fisher, John; Wilcox, Ruth K

2014-06-01

The aim of this study was to determine the cartilage contact mechanics and the associated fluid pressurisation of the hip joint under eight daily activities, using a three-dimensional finite element hip model with biphasic cartilage layers and generic geometries. Loads with spatial and temporal variations were applied over time and the time-dependent performance of the hip cartilage during walking was also evaluated. It was found that the fluid support ratio was over 90% during the majority of the cycles for all the eight activities. A reduced fluid support ratio was observed for the time at which the contact region slid towards the interior edge of the acetabular cartilage, but these occurred when the absolute level of the peak contact stress was minimal. Over 10 cycles of gait, the peak contact stress and peak fluid pressure remained constant, but a faster process of fluid exudation was observed for the interior edge region of the acetabular cartilage. The results demonstrate the excellent function of the hip cartilage within which the solid matrix is prevented from high levels of stress during activities owing to the load shared by fluid pressurisation. The findings are important in gaining a better understanding of the hip function during daily activities, as well as the pathology of hip degeneration and potential for future interventions. They provide a basis for future subject-specific biphasic investigations of hip performance during activities. © IMechE 2014.

Methodologies for Reservoir Characterization Using Fluid Inclusion Gas Chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dilley, Lorie M.

2015-04-13

The purpose of this project was to: 1) evaluate the relationship between geothermal fluid processes and the compositions of the fluid inclusion gases trapped in the reservoir rocks; and 2) develop methodologies for interpreting fluid inclusion gas data in terms of the chemical, thermal and hydrological properties of geothermal reservoirs. Phase 1 of this project was designed to conduct the following: 1) model the effects of boiling, condensation, conductive cooling and mixing on selected gaseous species; using fluid compositions obtained from geothermal wells, 2) evaluate, using quantitative analyses provided by New Mexico Tech (NMT), how these processes are recorded bymore » fluid inclusions trapped in individual crystals; and 3) determine if the results obtained on individual crystals can be applied to the bulk fluid inclusion analyses determined by Fluid Inclusion Technology (FIT). Our initial studies however, suggested that numerical modeling of the data would be premature. We observed that the gas compositions, determined on bulk and individual samples were not the same as those discharged by the geothermal wells. Gases discharged from geothermal wells are CO 2-rich and contain low concentrations of light gases (i.e. H 2, He, N, Ar, CH4). In contrast many of our samples displayed enrichments in these light gases. Efforts were initiated to evaluate the reasons for the observed gas distributions. As a first step, we examined the potential importance of different reservoir processes using a variety of commonly employed gas ratios (e.g. Giggenbach plots). The second technical target was the development of interpretational methodologies. We have develop methodologies for the interpretation of fluid inclusion gas data, based on the results of Phase 1, geologic interpretation of fluid inclusion data, and integration of the data. These methodologies can be used in conjunction with the relevant geological and hydrological information on the system to create fluid models for the system. The hope is that the methodologies developed will allow bulk fluid inclusion gas analysis to be a useful tool for estimating relative temperatures, identifying the sources and origins of the geothermal fluids, and developing conceptual models that can be used to help target areas of enhanced permeability.« less

Potential fluid mechanic pathways of platelet activation.

PubMed

Shadden, Shawn C; Hendabadi, Sahar

2013-06-01

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

Potential fluid mechanic pathways of platelet activation

PubMed Central

Shadden, Shawn C.; Hendabadi, Sahar

2012-01-01

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

Double dissociation of structure-function relationships in memory and fluid intelligence observed with magnetic resonance elastography.

PubMed

Johnson, Curtis L; Schwarb, Hillary; Horecka, Kevin M; McGarry, Matthew D J; Hillman, Charles H; Kramer, Arthur F; Cohen, Neal J; Barbey, Aron K

2018-05-01

Brain tissue mechanical properties, measured in vivo with magnetic resonance elastography (MRE), have proven to be sensitive metrics of neural tissue integrity. Recently, our group has reported on the positive relationship between viscoelasticity of the hippocampus and performance on a relational memory task in healthy young adults, which highlighted the potential of sensitive MRE measures for studying brain health and its relation to cognitive function; however, structure-function relationships outside of the hippocampus have not yet been explored. In this study, we examined the relationships between viscoelasticity of both the hippocampus and the orbitofrontal cortex and performance on behavioral assessments of relational memory and fluid intelligence. In a sample of healthy, young adults (N = 53), there was a significant, positive relationship between orbitofrontal cortex viscoelasticity and fluid intelligence performance (r = 0.42; p = .002). This finding is consistent with the previously reported relationship between hippocampal viscoelasticity and relational memory performance (r = 0.41; p = .002). Further, a significant double dissociation between the orbitofrontal-fluid intelligence relationship and the hippocampal-relational memory relationship was observed. These data support the specificity of regional brain MRE measures in support of separable cognitive functions. This report of a structure-function relationship observed with MRE beyond the hippocampus suggests a future role for MRE as a sensitive neuroimaging technique for brain mapping. Copyright © 2018 Elsevier Inc. All rights reserved.

A cell impedance measurement device for the cytotoxicity assay dependent on the velocity of supplied toxic fluid

NASA Astrophysics Data System (ADS)

Kang, Yoon-Tae; Kim, Min-Ji; Cho, Young-Ho

2018-04-01

We present a cell impedance measurement chip capable of characterizing the toxic response of cells depending on the velocity of the supplied toxic fluid. Previous impedance-based devices using a single open-top chamber have been limited to maintaining a constant supply velocity, and devices with a single closed-top chamber present difficulties in simultaneous cytotoxicity assay for varying levels of supply velocities. The present device, capable of generating constant and multiple levels of toxic fluid velocity simultaneously within a single stepwise microchannel, performs a cytotoxicity assay dependent on toxic fluid velocity, in order to find the effective velocity of toxic fluid to cells for maximizing the cytotoxic effect. We analyze the cellular toxic response of 5% ethanol media supplied to cancer cells within a toxic fluid velocity range of 0-8.3 mm s-1. We observe the velocity-dependent cell detachment rate, impedance, and death rate. We find that the cell detachment rate decreased suddenly to 2.4% at a velocity of 4.4 mm s-1, and that the change rates of cell resistance and cell capacitance showed steep decreases to 8% and 41%, respectively, at a velocity of 5.7 mm s-1. The cell death rate and impedance fell steeply to 32% at a velocity of 5.7 mm s-1. We conclude that: (1) the present device is useful in deciding on the toxic fluid velocity effective to cytotoxicity assay, since the cellular toxic response is dependent on the velocity of toxic fluid, and; (2) the cell impedance analysis facilitates a finer cellular response analysis, showing better correlation with the cell death rate, compared to conventional visual observation. The present device, capable of performing the combinational analysis of toxic fluid velocity and cell impedance, has potential for application to the fine cellular toxicity assay of drugs with proper toxic fluid velocity.

Remedial Amendment Delivery near the Water Table Using Shear Thinning Fluids: Experiments and Numerical Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oostrom, Martinus; Truex, Michael J.; Vermeul, Vincent R.

2014-08-19

The use of shear thinning fluids (STFs) containing xanthan is a potential enhancement for emplacing a solute amendment near the water table and within the capillary fringe. Most research to date related to STF behavior has involved saturated and confined conditions. A series of flow cell experiments were conducted to investigate STF emplacement in variable saturated homogeneous and layered heterogeneous systems. Besides flow visualization using dyes, amendment concentrations and pressure data were obtained at several locations. The experiments showed that injection of STFs considerably improved the subsurface distribution near the water table by mitigating preferential flow through higher permeability zonesmore » compared to no-polymer injections. The phosphate amendment migrated with the xanthan SFT without retardation. Despite the high viscosity of the STF, no excessive mounding or preferential flow were observed in the unsaturated zone. The STOMP simulator was able to predict the experimentally observed fluid displacement and amendment concentrations reasonably well. Cross flow between layers could be interpreted as the main mechanism to transport STFs into lower permeability layers based on the observed pressure gradient and concentration data in layers of differing hydraulic conductivity.« less

Changes in Physical Properties of the Nankai Trough Megasplay Fault Induced by Earthquakes, Detected by Continuous Pressure Monitoring

NASA Astrophysics Data System (ADS)

Kinoshita, C.; Saffer, D.; Kopf, A.; Roesner, A.; Wallace, L. M.; Araki, E.; Kimura, T.; Machida, Y.; Kobayashi, R.; Davis, E.; Toczko, S.; Carr, S.

2018-02-01

One primary objective of Integrated Ocean Drilling Program Expedition 365, conducted as part of the Nankai Trough Seismogenic Zone Experiment, was to recover a temporary observatory emplaced to monitor formation pore fluid pressure and temperature within a splay fault in the Nankai subduction zone offshore SW Honshu, Japan. Here we use a 5.3 year time series of formation pore fluid pressure, and in particular the response to ocean tidal loading, to evaluate changes in pore pressure and formation and fluid elastic properties induced by earthquakes. Our analysis reveals 31 earthquake-induced perturbations. These are dominantly characterized by small transient increases in pressure (28 events) and decreases in ocean tidal loading efficiency (14 events) that reflect changes to formation or fluid compressibility. The observed perturbations follow a magnitude-distance threshold similar to that reported for earthquake-driven hydrological effects in other settings. To explore the mechanisms that cause these changes, we evaluate the expected static and dynamic strains from each earthquake. The expected static strains are too small to explain the observed pressure changes. In contrast, estimated dynamic strains correlate with the magnitude of changes in both pressure and loading efficiency. We propose potential mechanism for the changes and subsequent recovery, which is exsolution of dissolved gas in interstitial fluids in response to shaking.

Intermolecular interactions and the thermodynamic properties of supercritical fluids.

PubMed

Yigzawe, Tesfaye M; Sadus, Richard J

2013-05-21

The role of different contributions to intermolecular interactions on the thermodynamic properties of supercritical fluids is investigated. Molecular dynamics simulation results are reported for the energy, pressure, thermal pressure coefficient, thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound of fluids interacting via both the Lennard-Jones and Weeks-Chandler-Andersen potentials. These properties were obtained for a wide range of temperatures, pressures, and densities. For each thermodynamic property, an excess value is determined to distinguish between attraction and repulsion. It is found that the contributions of intermolecular interactions have varying effects depending on the thermodynamic property. The maxima exhibited by the isochoric and isobaric heat capacities, isothermal compressibilities, and thermal expansion coefficient are attributed to interactions in the Lennard-Jones well. Repulsion is required to obtain physically realistic speeds of sound and both repulsion and attraction are necessary to observe a Joule-Thomson inversion curve. Significantly, both maxima and minima are observed for the isobaric and isochoric heat capacities of the supercritical Lennard-Jones fluid. It is postulated that the loci of these maxima and minima converge to a common point via the same power law relationship as the phase coexistence curve with an exponent of β = 0.32. This provides an explanation for the terminal isobaric heat capacity maximum in supercritical fluids.

Spray Formation from a Charged Liquid Jet of a Dielectric Fluid

NASA Astrophysics Data System (ADS)

Doak, William; de Bellis, Victor; Chiarot, Paul; Microfluidics; Multiphase Flow Laboratory Team

2017-11-01

Atomization of a dielectric micro-jet is achieved via an electrohydrodynamic charge injection process. The atomizer is comprised of a grounded nozzle housing (ground electrode) and an internal probe (high voltage electrode) that is concentric with the emitting orifice. The internal probe is held at electric potentials ranging from 1-10 kV. A pressurized reservoir drives a dielectric fluid at a desired flow rate through the 100-micrometer diameter orifice. The fluid fills the cavity between the electrodes as it passes through the atomizer, impeding the transport of electrons. This process injects charge into the flowing fluid. Upon exiting the orifice, the emitted jet is highly charged and it deforms via a bending instability that is qualitatively similar to the behavior observed in the electrospinning of fibers. We observed bulging regions, or nodes, of highly charged fluid forming along the bent, rotating jet. These nodes separate into highly charged droplets that emit satellite droplets. The remaining ligaments break up due to capillarity in a process that produces additional satellites. All of the droplets possess a normal (inertial) and radial (electrically-driven) momentum component. The radial component is responsible for the formation of a conical spray envelope. Our research focuses on the jet, its break up, and the droplet dynamics of this system. This research supported by the American Chemical Society.

Microgravity Transport Phenomena Experiment (MTPE) Overview

NASA Technical Reports Server (NTRS)

Mason, Larry W.

1999-01-01

The Microgravity Transport Phenomena Experiment (MTPE) is a fluids experiment supported by the Fundamentals in Biotechnology program in association with the Human Exploration and Development of Space (BEDS) initiative. The MTP Experiment will investigate fluid transport phenomena both in ground based experiments and in the microgravity environment. Many fluid transport processes are affected by gravity. Osmotic flux kinetics in planar membrane systems have been shown to be influenced by gravimetric orientation, either through convective mixing caused by unstably stratified fluid layers, or through a stable fluid boundary layer structure that forms in association with the membrane. Coupled transport phenomena also show gravity related effects. Coefficients associated with coupled transport processes are defined in terms of a steady state condition. Buoyancy (gravity) driven convection interferes with the attainment of steady state, and the measurement of coupled processes. The MTP Experiment measures the kinetics of molecular migration that occurs in fluids, in response to the application of various driving potentials. Three separate driving potentials may be applied to the MTP Experiment fluids, either singly or in combination. The driving potentials include chemical potential, thermal potential, and electrical potential. Two separate fluid arrangements are used to study membrane mediated and bulk fluid transport phenomena. Transport processes of interest in membrane mediated systems include diffusion, osmosis, and streaming potential. Bulk fluid processes of interest include coupled phenomena such as the Soret Effect, Dufour Effect, Donnan Effect, and thermal diffusion potential. MTP Experiments are performed in the Microgravity Transport Apparatus (MTA), an instrument that has been developed specifically for precision measurement of transport processes. Experiment fluids are contained within the MTA fluid cells, designed to create a one dimensional flow geometry of constant cross sectional area, and to facilitate fluid filling and draining operations in microgravity. The fluid cells may be used singly for bulk solutions, or in a Stokes diaphragm configuration to investigate membrane mediated phenomena. Thermal and electrical driving potentials are applied to the experiment fluids through boundary plates located at the ends of the fluid cells. In the ground based instrument, two constant temperature baths circulate through reservoirs adjacent to the boundary plates, and establish the thermal environment within the fluid cells. The boundary plates also serve as electrodes for measurement and application of electrical potentials. The Fluid Manipulation System associated with the MTA is a computer controlled system that enables storage and transfer of experiment fluids during on orbit operations. The system is used to automatically initiate experiments and manipulate fluids by orchestrating pump and valve operations through scripted sequences. Unique technologies are incorporated in the MTA for measurement of fluid properties. Volumetric Flow Sensors have been developed for precision measurement of total fluid volume contained within the fluid cells over time. This data is most useful for measuring the kinetics of osmosis, where fluid is transported from one fluid cell to another through a semipermeable membrane. The MicroSensor Array has been designed to perform in situ measurement of several important fluid parameters, providing simultaneous measurement of solution composition at multiple locations within the experiment fluids. Micromachined sensors and interface electronics have been developed to measure temperature, electrical conductivity, pH, cation activity, and anion activity. The Profile Refractometer uses a laser optical system to directly image the fluid Index of Refraction profile that exists along the MTA fluid cell axis. A video system acquires images of the RI profile over time, and records the transport kinetics that occur upon application of chemical, thermal, or electrical driving potentials. Image processing algorithms have been developed to analyze the refractometer images on a pixel by pixel basis, calibrating and scaling the measured Index of Refraction profile to correlated solution properties of interest such as density, concentration, and temperature. Additional software has been developed to compile the processed images into a three dimensional matrix that contains fluid composition data as a function of experiment time and position in the fluid cell. These data are combined with data from the other sensor systems, and analyzed in the context of transport coefficients associated with the various transport phenomena. Analysis protocols have been developed to measure the transient kinetics, and steady state distribution of fluid components that occur in response to the applied driving potentials. The results are expressed in terms of effective transport coefficients. Experiments have been performed using a variety of solutes, and results generated are that are in agreement with published transport coefficient values.

Perturbation theory of structure in classical liquid mixtures: Application to metallic systems near phase separation. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Henderson, R. L.

1974-01-01

The partial structure factors of classical simple liquid mixtures near phase separation are dicussed. The theory is developed for particles interacting through pair potentials, and is thus appropriate both to insulating fluids, and also to metallic systems if these may be described by an effective ion-ion pair interaction. The motivation arose from consideration of metallic liquid mixtures, in which resistive anomalies have been observed near phase separation. A mean field theory correction appropriate to 3 pair potential for the effects of correlated motions in the reference fluid is studied. The work is cast in terms of functions which are closely related to the direct correlation functions of Ornstein and Zernike. The results are qualitatively in accord with physical expectations. Quantitative agreement with experiment seems to turn on the selection of the hard core reference potential in terms of the metallic effective pair potential. It is suggested that the present effective pair potentials are perhaps not properly used to calculate the metallic structure factors at long wavelength.

Long-period long-duration seismic events during hydraulic fracturing: Implications for tensile fracture development

NASA Astrophysics Data System (ADS)

Hu, Hongru; Li, Aibing; Zavala-Torres, Ricardo

2017-05-01

Long-period long-duration (LPLD) seismic events are observed from a microseismic data set acquired by surface receivers in the Eagle Ford Shale. These events are characterized by low frequencies of 10-60 Hz and long durations of 30-60 s. The seismograms are dominated with P waves, and the frequency spectra have peaks at several isolated frequencies, similar to volcanic tremors. The LPLD events are located close to the horizontal hydraulic treatment well and migrate away from the well with time. These observations suggest that the LPLD events are related to hydraulic fracturing and are possibly caused by the jerky opening and resonance of fluid-filled cracks. Imaging this type of LPLD events can potentially map fluid flow and tensile fracture development during hydraulic fracturing.

Fluid-mediated redox transfer in subduction zones: Measuring the intrinsic fO2 of slab fluids in the lab

NASA Astrophysics Data System (ADS)

Iacovino, K.; Till, C. B.

2017-12-01

It is widely observed that arc magmas are the most oxidized magmas on Earth. One frequently cited explanation calls on the flux of aqueous fluid from the highly oxidized down-going slab to catalyze sub-arc mantle melting and impose a highly oxidized redox signature on the mantle wedge. Fluid inclusions from sub-arc mantle xenoliths provide evidence that "slab fluids" may be highly oxidizing (fO2 QFM+1.5; Brandon & Draper, 1996; Frost and Ballhaus, 1998), but for decades, determination of the precise reactive mechanism potentially responsible for the transfer of O2 from slab to mantle has been elusive. Pure H2O has been shown to have insufficient oxidizing capacity to affect mantle redox, but H2O-rich fluids may facilitate the mobilization of Fe3+ or other multivalent cations and/or O2 transfer via the reduction of sulfate, particularly if such fluids are hypersaline. Here we present the first results from experiments designed to investigate fluid-mediated element transfer, including redox reactions, at the slab-mantle interface. These data include the first direct measurements of the intrinsic oxygen fugacity of fluids released during slab dehydration using sliding binary alloy redox sensors. Experiments were performed on natural Fe3+-bearing antigorite serpentinite at 1-2 GPa and 800°C in a piston cylinder at Arizona State University, analogous to conditions in a subducting slab and sufficient to cause the breakdown of starting material into forsteritic olivine, Mg-rich clinopyroxene, magnetite, and aqueous fluid. Experimental time series allow for the detection of (and correction for) any buffering effect on the sample by the experimental assembly. Initial results indicate that the dehydration of sulfur-free antigorite serpentinite can generate fluids with fO2 several orders of magnitude above that of MORB mantle and similar to those observed in natural sub-arc fluid inclusions. Careful measurements of the chemistry of fluid and solid run products will elucidate the redox exchange reaction responsible for these fluid characteristics. These data suggest the dehydration of slab serpentine and the derivative fluid may play an important role in controlling the redox of arc magmas and the sub-arc mantle.

Streaming Potential In Rocks Saturated With Water And Oil

NASA Astrophysics Data System (ADS)

Tarvin, J. A.; Caston, A.

2011-12-01

Fluids flowing through porous media generate electrical currents. These currents cause electric potentials, called "streaming potentials." Streaming potential amplitude depends on the applied pressure gradient, on rock and fluid properties, and on the interaction between rock and fluid. Streaming potential has been measured for rocks saturated with water (1) and with water-gas mixtures. (2) Few measurements (3) have been reported for rocks saturated with water-oil mixtures. We measured streaming potential for sandstone and limestone saturated with a mixture of brine and laboratory oil. Cylindrical samples were initially saturated with brine and submerged in oil. Saturation was changed by pumping oil from one end of a sample to the other and then through the sample in the opposite direction. Saturation was estimated from sample resistivity. The final saturation of each sample was determined by heating the sample in a closed container and measuring the pressure. Measurements were made by modulating the pressure difference (of oil) between the ends of a sample at multiple frequencies below 20 Hz. The observed streaming potential is a weak function of the saturation. Since sample conductivity decreases with increasing oil saturation, the electro-kinetic coupling coefficient (Pride's L (4)) decreases with increasing oil saturation. (1) David B. Pengra and Po-zen Wong, Colloids and Surfaces, vol., p. 159 283-292 (1999). (2) Eve S. Sprunt, Tony B. Mercer, and Nizar F. Djabbarah, Geophysics, vol. 59, p. 707-711 (1994). (3) Vinogradov, J., Jackson, M.D., Geophysical Res. L., Vol. 38, Article L01301 (2011). (4) Steve Pride, Phys. Rev. B, vol. 50, pp. 15678-15696 (1994).

Computerized X-ray Microtomography Observations and Fluid Flow Measurements of the Effect of Effective Stress on Fractured Reservoir Seal Shale

NASA Astrophysics Data System (ADS)

Welch, N.; Crawshaw, J.; Boek, E.

2014-12-01

The successful storage of carbon dioxide in geologic formations requires an in-depth understanding of all reservoir characteristics and morphologies. An intact and substantial seal formation above a storage reservoir is required for a significant portion of the initial sealing mechanisms believed to occur during carbon dioxide storage operations. Shales are a common seal formation rock types found above numerous hydrocarbon reservoirs, as well as potential saline aquifer storage locations. Shales commonly have very low permeability, however they also have the tendency to be quite fissile, and the formation of fractures within these seals can have a significant detrimental effect on the sealing potential of a reservoir and amount to large areas of high permeability and low capillary pressures compared to the surrounding intact rock. Fractured shales also have an increased current interest due to the increasing development of shale gas reservoirs using hydraulic fracturing techniques. This work shows the observed changes that occur within fractured pieces of reservoir seal shale samples, along with quarry analogues, using an in-situ micro-CT fluid flow imaging apparatus with a Hassler type core holder. Changes within the preferential flow path under different stress regimes as well as physical changes to the fracture geometry are reported. Lattice Boltzmann flow simulations were then performed on the extracted flow paths and compared to experiment permeability measurements. The preferential flow path of carbon dioxide through the fracture network is also observed and compared to the results two-phase Lattice Boltzmann fluid flow simulations.

RAPAMYCIN INCREASES LENGTH AND MECHANOSENSORY FUNCTION OF PRIMARY CILIA IN RENAL EPITHELIAL AND VASCULAR ENDOTHELIAL CELLS.

PubMed

Sherpa, Rinzhin T; Atkinson, Kimberly F; Ferreira, Viviana P; Nauli, Surya M

2016-12-01

Primary cilia arebiophysically-sensitive organelles responsible for sensing fluid-flow and transducing this stimulus into intracellular responses. Previous studies have shown that the primary cilia mediate flow-induced calcium influx, and sensitivity of cilia function to flow is correlated to cilia length. Cells with abnormal cilia length or function can lead to a host of diseases that are collectively termed as ciliopathies. Rapamycin, a potent inhibitor of mTOR (mammalian target of rapamycin), has been demonstrated to be a potential pharmacological agent against the aberrant mTOR signaling seen in ciliopathies such as polycystic kidney disease (PKD) and tuberous sclerosis complex (TSC). Here we look at the effects of rapamycin on ciliary length and function for the first time. Compared to controls, primary cilia in rapamycin-treated porcine renal epithelial and mouse vascular endothelial cells showed a significant increase in length. Graded increases in fluid-shear stress further indicates that rapamycin enhances cilia sensitivity to fluid flow. Treatment with rapamycin led to G0 arrest in porcine epithelial cells while no significant change in cell cycle were observed in rapamycin-treated mouse epithelial or endothelial cells, indicating a species-specific effect of rapamycin. Given the previousin vitro and in vivo studies establishing rapamycin as a potential therapeutic agent for ciliopathies, such as PKD and TSC, our studies show that rapamycin enhances ciliary function and sensitivity to fluid flow. The results of our studies suggest a potential ciliotherapeutic effect of rapamycin.

A Study of Permeability Changes Due to Cold Fluid Circulation in Fractured Geothermal Reservoirs.

PubMed

Gholizadeh Doonechaly, Nima; Abdel Azim, Reda R; Rahman, Sheik S

2016-05-01

Reservoir behavior due to injection and circulation of cold fluid is studied with a shear displacement model based on the distributed dislocation technique, in a poro-thermoelastic environment. The approach is applied to a selected volume of Soultz geothermal reservoir at a depth range of 3600 to 3700 m. Permeability enhancement and geothermal potential of Soultz geothermal reservoir are assessed over a stimulation period of 3 months and a fluid circulation period of 14 years. This study-by shedding light onto another source of uncertainty-points toward a special role for the fracture surface asperities in predicting the shear dilation of fractures. It was also observed that thermal stress has a significant impact on changing the reservoir stress field. The effect of thermal stresses on reservoir behavior is more evident over longer circulation term as the rock matrix temperature is significantly lowered. Change in the fracture permeability due to the thermal stresses can also lead to the short circuiting between the injection and production wells which in turn decreases the produced fluid temperature significantly. The effect of thermal stress persists during the whole circulation period as it has significant impact on the continuous increase in the flow rate due to improved permeability over the circulation period. In the current study, taking into account the thermal stress resulted in a decrease of about 7 °C in predicted produced fluid temperature after 14 years of cold fluid circulation; a difference which notably influences the potential prediction of an enhanced geothermal system. © 2015, National Ground Water Association.

Detection of acute lymphoblastic leukemia involvement in pleural fluid in an adult patient with ataxia telangiectasia by flow cytometry method.

PubMed

Keklik, Muzaffer; Koker, M Yavuz; Sivgin, Serdar; Camlica, Demet; Pala, Cigdem; Cetin, Mustafa; Kaynar, Leylagul; Unal, Ali; Eser, Bulent

2014-09-01

Ataxia-telangiectasia (AT) is a rare multisystem, neurodegenerative genetic disorder. Patients should be closely monitored due to risk of malignancy development. Due to its wide clinical heterogeneity, it often leads physicians to an inaccurate or missed diagnosis, and insight into this rare disease is important. Pediatric patients may develop lymphomas and acute lymphoblastic leukemia (ALL). However, in adults, there are limited numbers of reports regarding association of AT and ALL. Rarely, ALL cases may present with pleural fluid involvement. In our study, we presented an adult case with AT, in which ALL involvement was detected in pleural fluid by flow cytometry (FC). A 20-years old male presented to emergency department with fever, shortness of breath and cough, as he had been followed with a diagnosis of AT. The following findings were detected in laboratory tests: Hb, 11.5 g/L; WBC, 36 × 10(9)/L; Plt: 140 × 10(9)/L. Blastic cells were observed in peripheral blood smear. On chest radiography, pleural fluid appearance was observed. On thorax CT, pleural fluid was detected in both hemithorax. Cytoplasmic CD3(+) and superficial CD3 (+), CD45 (+), CD5 (+), CD7 (+) and CD38 (+) was found in the flow cytometric evaluation of peripheral blood. Superficial CD3 (+), CD2 (+), CD5 (+) and CD7 (+) were found in flow cytometric evaluation of pleural fluid. These findings were considered as consistent with pleural involvement of T-ALL. FC is a potentially useful diagnostic tool for clinical practice and it is a convenience method which has an important role in detection of ALL in patients with pleural fluid.

Lipidomics analysis of follicular fluid by ESI-MS reveals potential biomarkers for ovarian endometriosis.

PubMed

Cordeiro, Fernanda Bertuccez; Cataldi, Thais Regiani; Perkel, Kayla Jane; do Vale Teixeira da Costa, Lívia; Rochetti, Raquel Cellin; Stevanato, Juliana; Eberlin, Marcos Nogueira; Zylbersztejn, Daniel Suslik; Cedenho, Agnaldo Pereira; Turco, Edson Guimarães Lo

2015-12-01

The aim of the present study was to analyze the lipid profile of follicular fluid from patients with endometriosis and endometrioma who underwent in vitro fertilization treatment (IVF). The control group (n = 10) was composed of women with tubal factor or minimal male factor infertility who had positive pregnancy outcomes after IVF. The endometriosis group consisted of women with endometriosis diagnosed by videolaparoscopy (n = 10), and from the same patients, the endometriomas fluids were collected, which composed the endometrioma group (n = 10). From the follicular fluid and endometriomas, lipids were extracted by the Bligh and Dyer method, and the samples were analyzed by tandem mass spectrometry. We observed phosphatidylglycerol phosphate, phosphatidylcholine, phosphatidylserine, and phosphatidylnositol bisphosphate in the control group. In the endometriosis group, sphingolipids and phosphatidylcholines were more abundant, while in the endometrioma group, sphingolipids and phosphatidylcholines with different m/z from the endometriosis group were found in high abundance. This analysis demonstrated that there is a differential representation of these lipids according to their respective groups. In addition, the lipids found are involved in important mechanisms related to endometriosis progress in the ovary. Thus, the metabolomic approach for the study of lipids may be helpful in potential biomarker discovery.

Effects of overlapping electric double layer on mass transport of a macro-solute across porous wall of a micro/nanochannel for power law fluid.

PubMed

Bhattacharjee, Saikat; Mondal, Mrinmoy; De, Sirshendu

2017-05-01

Effects of overlapping electric double layer and high wall potential on transport of a macrosolute for flow of a power law fluid through a microchannel with porous walls are studied in this work. The electric potential distribution is obtained by coupling the Poisson's equation without considering the Debye-Huckel approximation. The numerical solution shows that the center line potential can be 16% of wall potential at pH 8.5, at wall potential -73 mV and scaled Debye length 0.5. Transport phenomena involving mass transport of a neutral macrosolute is formulated by species advective equation. An analytical solution of Sherwood number is obtained for power law fluid. Effects of fluid rheology are studied in detail. Average Sherwood number is more for a pseudoplastic fluid compared to dilatant upto the ratio of Poiseuille to electroosmotic velocity of 5. Beyond that, the Sherwood number is independent of fluid rheology. Effects of fluid rheology and solute size on permeation flux and concentration of neutral solute are also quantified. More solute permeation occurs as the fluid changes from pseudoplastic to dilatant. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A qualitative view of cryogenic fluid injection into high speed flows

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Schlumberger, J.; Proctor, M.

1991-01-01

The injection of supercritical pressure, subcritical temperature fluids, into a 2-D, ambient, static temperature and static pressure supersonic tunnel and free jet supersonic nitrogen flow field was observed. Observed patterns with fluid air were the same as those observed for fluid nitrogen injected into the tunnel at 90 deg to the supersonic flow. The nominal injection pressure was of 6.9 MPa and tunnel Mach number was 2.7. When injected directly into and opposing the tunnel exhaust flow, the observed patterns with fluid air were similar to those observed for fluid nitrogen but appeared more diffusive. Cryogenic injection creates a high density region within the bow shock wake but the standoff distance remains unchanged from the gaseous value. However, as the temperature reaches a critical value, the shock faded and advanced into the supersonic stream. For both fluids, nitrogen and air, the phenomena was completely reversible.

Reactive-brittle dynamics in peridotite alteration

NASA Astrophysics Data System (ADS)

Evans, O.; Spiegelman, M. W.; Kelemen, P. B.

2017-12-01

The interactions between reactive fluids and brittle solids are critical in Earth dynamics. Implications of such processes are wide-ranging: from earthquake physics to geologic carbon sequestration and the cycling of fluids and volatiles through subduction zones. Peridotite alteration is a common feature in many of these processes, which - despite its obvious importance - is relatively poorly understood from a geodynamical perspective. In particular, alteration reactions are thought to be self-limiting in nature, contradicting observations of rocks that have undergone 100% hydration/carbonation. One potential explanation of this observation is the mechanism of "reaction-driven cracking": that volume changes associated with these reactions are large enough to fracture the surrounding rock, leading to a positive feedback where new reactive surfaces are exposed and fluid pathways are created. The purpose of this study is to investigate the relative roles of reaction, elastic stresses and surface tension in alteration reactions. In this regard we derive a system of equations describing reactive fluid flow in an elastically deformable porous media, and explore them via a combination of analytic and numerical solutions. Using this model we show that the final stress state of a dry peridotite that has undergone reaction depends strongly on the rates of reaction versus fluid transport: significant fluid flow driven by pressure and/or surface tension gradients implies higher fractions of serpentinization, leaving behind a highly stressed residuum of partially reacted material. Using a model set-up that mimics a cylindrical triaxial apparatus we predict that the resulting stresses would lead to tensile failure and the generation of radially oriented cracks.

In Vitro Investigations of Human Bioaccessibility from Reference Materials Using Simulated Lung Fluids

PubMed Central

Pelfrêne, Aurélie; Cave, Mark R.; Wragg, Joanna; Douay, Francis

2017-01-01

An investigation for assessing pulmonary bioaccessibility of metals from reference materials is presented using simulated lung fluids. The objective of this paper was to contribute to an enhanced understanding of airborne particulate matter and its toxic potential following inhalation. A large set of metallic elements (Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, and Zn) was investigated using three lung fluids (phosphate-buffered saline, Gamble’s solution and artificial lysosomal fluid) on three standard reference materials representing different types of particle sources. Composition of the leaching solution and four solid-to-liquid (S/L) ratios were tested. The results showed that bioaccessibility was speciation- (i.e., distribution) and element-dependent, with percentages varying from 0.04% for Pb to 86.0% for Cd. The higher extraction of metallic elements was obtained with the artificial lysosomal fluid, in which a relative stability of bioaccessibility was observed in a large range of S/L ratios from 1/1000 to 1/10,000. For further investigations, it is suggested that this method be used to assess lung bioaccessibility of metals from smelter-impacted dusts. PMID:28125027

Formaldehyde and some fully n-methylated substances in boar seminal fluids. Short communication.

PubMed

Szilágyi, M; Németh, Z I; Albert, L; Sarlós, P; Tyihák, E

2006-03-01

On the basis of recent observations it is supposed that seminal fluids may contain--mainly in hydroxymethyl groups--formaldehyde (HCHO) and quaternary ammonium compounds as potential HCHO generators, therefore, preliminary investigations were carried out for the identification of these compounds in pig seminal fluids using OPLC, HPLC and MALDI MS techniques. The fresh pig seminal fluid was frozen in liquid nitrogen, powdered and aliquots (0.25 g) were treated with 0.7 ml ethanolic dimedone solution. The suspension was centrifuged and the clear supernatant was used for analysis by OPLC or after dilution with HPLC or MALDI MS technique. After OPLC separation of formaldemethone the fully N-methylated compounds which are stayed on the start point were separated by OPLC using an other eluent system. It has been established that the HCHO is really a normal component of the pig seminal fluid, as well. It can be isolated and identified in dimedone adduct form. The measurable amount of HCHO depended on the concentration applied of dimedone. According to OPLC and MALDI MS investigations L-carnitine is the main quaternary ammonium compound in pig seminal fluid which can generate a protection of the sperm cells against environmental and other influences. Considerable differences have been found among individuals concerning concentrations of quaternary ammonium compounds in the seminal fluid of pigs.

Kinetic simulations of scrape-off layer physics in the DIII-D tokamak

DOE PAGES

Churchill, Randy M.; Canik, John M.; Chang, C. S.; ...

2016-12-27

Simulations using the fully kinetic code XGCa were undertaken to explore the impact of kinetic effects on scrape-off layer (SOL) physics in DIII-D H-mode plasmas. XGCa is a total- f, gyrokinetic code which self-consistently calculates the axisymmetric electrostatic potential and plasma dynamics, and includes modules for Monte Carlo neutral transport. Fluid simulations are normally used to simulate the SOL, due to its high collisionality. However, depending on plasma conditions, a number of discrepancies have been observed between experiment and leading SOL fluid codes (e.g. SOLPS), including underestimating outer target temperatures, radial electric field in the SOL, parallel ion SOL flowsmore » at the low field side, and impurity radiation. Many of these discrepancies may be linked to the fluid treatment, and might be resolved by including kinetic effects in SOL simulations. The XGCa simulation of the DIII-D tokamak in a nominally sheath-limited regime show many noteworthy features in the SOL. The density and ion temperature are higher at the low-field side, indicative of ion orbit loss. The SOL ion Mach flows are at experimentally relevant levels ( Mi ~0.5), with similar shapes and poloidal variation as observed in various tokamaks. Surprisingly, the ion Mach flows close to the sheath edge remain subsonic, in contrast to the typical fluid Bohm criterion requiring ion flows to be above sonic at the sheath edge. Related to this are the presence of elevated sheath potentials, eΔΦ/T e ~ 3–4, over most of the SOL, with regions in the near-SOL close to the separatrix having eΔΦ/Te > 4. Finally, these two results at the sheath edge are a consequence of non-Maxwellian features in the ions and electrons there.« less

Utilization of MRI for Cerebral White Matter Injury in a Hypobaric Swine Model-Validation of Technique.

PubMed

McGuire, Jennifer A; Sherman, Paul M; Dean, Erica; Bernot, Jeremy M; Rowland, Laura M; McGuire, Stephen A; Kochunov, Peter V

2017-05-01

Repetitive hypobaric exposure in humans induces subcortical white matter change, observable on magnetic resonance imaging (MRI) and associated with cognitive impairment. Similar findings occur in traumatic brain injury (TBI). We are developing a swine MRI-driven model to understand the pathophysiology and to develop treatment interventions. Five miniature pigs (Sus scrofa domestica) were repetitively exposed to nonhypoxic hypobaria (30,000 feet/FIO 2 100%/transcutaneous PO 2 >90%) while under general anesthesia. Three pigs served as controls. Pre-exposure and postexposure MRIs were obtained that included structural sequences, dynamic contrast perfusion, and diffusion tensor quantification. Statistical comparison of individual subject and group change was performed utilizing a two-tailed t test. No structural imaging change was noted on T2-weighted or three-dimensional fluid-attenuated inversion recovery imaging between MRI 1 and MRI 2. No absolute difference in dynamic contrast perfusion was observed. A trend (p = 0.084) toward increase in interstitial extra-axonal fluid was noted. When individual subjects were examined, this trend toward increased extra-axonal fluid paralleled a decrease in contrast perfusion rate. This study demonstrates high reproducibility of quantitative noninvasive MRI, suggesting MRI is an appropriate assessment tool for TBI and hypobaric-induced injury research in swine. The lack of fluid-attenuated inversion recovery change may be multifactorial and requires further investigation. A trend toward increased extra-axonal water content that negatively correlates with dynamic contrast perfusion implies generalized axonal injury was induced. This study suggests this is a potential model for hypobaric-induced injury as well as potentially other axonal injuries such as TBI in which similar subcortical white matter change occurs. Further development of this model is necessary. Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.

Laboratory Simulations of Permeability Pertaining to Biosignature Development and Preservation Potential for Martian Subsurface Habitability

NASA Astrophysics Data System (ADS)

Perl, S. M.; Corsetti, F. A.; Berelson, W.; Nealson, K. H.; Bhartia, R.

2014-12-01

Sedimentological and mineralogical observations indicate that sandstones within the Eagle and Endurance crater sections of the Burns Formation of Meridiani Planum, Mars, were derived from sulfate-bearing altered basalt, possibly from a playa lake, and deposited by eolian and locally subaqueous processes in a eolian dune - sand sheet - interdune setting. Abrasion of rocks within the outcrop outlining Endurance Crater by the MER rover Opportunity revealed void spaces later determined to be secondary pore space created from the dissolution of soluble minerals from multiple groundwater movement (recharge) events. Previous investigations into the secondary porosity and permeability of rocks within the Karatepe section showed that the ability for fluid movement through the vertical sedimentary section was greatest between the Upper and Middle units at the Whatanga contact within Endurance Crater, where secondary porosity was measured to be ~40% of the rock. Our investigations into quantifying subsurface habitability involve simulating the paleo-groundwater environments on the micro-to-mesoscale (sub mm-scale to cm-scale) to determine how preservation potential changes with repeated water-rock interaction, varying fluid chemistry (pH, salinity, T, others), and pressure changes under Earth and Mars conditions. In addition to fluids, microbes (extremophiles) will be introduced into our simulation to observe how changing experimental input conditions impact the growth and development of biotic interactions and eventually biosignatures left behind within sedimentary microtextures. Moreover, detection of biosignatures using visual and UV methods will help inform the M2020 rover mission regarding in-situ analysis of abraded rock outcrops. Finally, results of this work will use terrestrial rocks and fluids from a known Mars analogue (the Rio Tinto basin) in order to aid in determining habitability and survivability in acidic and high saline conditions that are similar to Meridiani Planum, Mars.

Modeling viscous dissipation during vocal fold contact: the influence of tissue viscosity and thickness with implications for hydration.

PubMed

Erath, Byron D; Zañartu, Matías; Peterson, Sean D

2017-06-01

The mechanics of vocal fold contact during phonation is known to play a crucial role in both normal and pathological speech production, though the underlying physics is not well understood. Herein, a viscoelastic model of the stresses during vocal fold contact is developed. This model assumes the cover to be a poroelastic structure wherein interstitial fluid translocates in response to mechanical squeezing. The maximum interstitial fluid pressure is found to generally increase with decreasing viscous dissipation and/or decreasing tissue elasticity. A global minimum in the total contact stress, comprising interstitial fluid pressure and elastic stress in the tissue, is observed over the studied dimensionless parameter range. Interestingly, physiologically reasonable estimates for the governing parameters fall within this global minimum region. The model is validated against prior experimental and computational work, wherein the predicted contact stress magnitude and impact duration agree well with published results. Lastly, observations of the potential relationship between vocal fold hydration and increased risk of tissue damage are discussed based upon model predictions of stress as functions of cover layer thickness and viscosity.

Aqueous extract of Psidium guajava leaves: phenolic compounds and inhibitory potential on digestive enzymes.

PubMed

Simão, Anderson A; Marques, Tamara R; Marcussi, Silvana; Corrêa, Angelita D

2017-01-01

Leaves of Psidium guajava L. (guava) have been widely used in the popular way for prevention and treatment of various diseases. Thus, the objective of this study was to evaluate the inhibitory potential of leaves aqueous extract from three cultivars of P. guajava (Pedro Sato, Paluma and Século XXI) on α-amylase, α-glycosidase, lipase, and trypsin enzymes, in the presence or not of simulated gastric fluid and to determine the content of phenolic compounds by high performance liquid chromatography. All cultivars presented the same composition in phenolic compounds, but in different proportions. The compounds identified are gallic acid, epigallocatechin gallate, syringic acid, o-coumaric acid, resveratrol, quercetin, and catechin (which was the major compound in all the cultivars evaluated). In the absence of simulated gastric fluid, it was observed different inhibitions exercised by the leaves aqueous extracts from three cultivars of P. guajava on each enzyme. In presence of simulated gastric fluid, all cultivars showed increase in the inhibition of lipase and α-glycosidase, and decrease in inhibition of α-amylase and trypsin enzymes. These results indicate that P. guajava leaves aqueous extracts from all cultivars evaluated possess potential of use as an adjuvant in the treatment of obesity and other dyslipidemias.

Combinatorial effects of quercetin and sex-steroids on fluid and electrolytes’ (Na+, Cl-, HCO3-) secretory mechanisms in the uterus of ovariectomised female Sprague-Dawley rats

PubMed Central

Shahzad, Huma; Giribabu, Nelli; Karim, Kamarulzaman; Kassim, Normadiah M.; Muniandy, Sekaran

2017-01-01

Dysregulation of uterine fluid environment could impair successful reproduction and this could be due to the effect of environmental estrogens. Therefore, in this study, effect of quercetin, an environmental estrogen on uterine fluid and electrolytes concentrations were investigated under sex-steroid influence. Ovariectomised adult female Sprague-Dawley rats were given 10, 50 or 100mg/kg/day quercetin subcutaneously with 17-β estradiol (E) for seven days or three days E, then three days E plus progesterone (P) (E+P) treatment. Uterine fluid secretion rate, Na+, Cl- and HCO3- concentrations were determined by in-vivo perfusion. Following sacrifice, uteri were harvested and levels of the proteins of interest were identified by Western blotting and Realtime PCR. Distribution of these proteins in the uterus was observed by immunofluorescence. Levels of uterine cAMP were measured by enzyme-linked immunoassay (EIA). Administration of quercetin at increasing doses increased uterine fluid secretion rate, Na+, Cl- and HCO3- concentrations, but to the levels lesser than that of E. In concordant, levels of CFTR, SLC4A4, ENaC (α, β and γ), Na+/K+-ATPase, GPα/β, AC and cAMP in the uterus increased following increased in the doses of quercetin. Co-administration of quercetin with E caused uterine fluid secretion rate, Na+, Cl- and HCO3- concentrations to decrease. In concordant, uterine CFTR, SLC26A6, SLC4A4, ENaC (α, β and γ), Na+/K+-ATPase, GPα/β, AC and cAMP decreased. Greatest effects were observed following co-administration of 10mg/kg/day quercetin with E. Co-administration of quercetin with E+P caused uterine fluid Na+ and HCO3- concentrations to increase but no changes in fluid secretion rate and Cl- concentration were observed. Co-administration of high dose quercetin (100 mg/kg/day) with E+P caused uterine CFTR, SLC26A6, AC, GPα/β and ENaC (α, β and γ) to increase. Quercetin-induced changes in the uterine fluid secretion rate and electrolytes concentrations could potentially affect the uterine reproductive functions under female sex-steroid influence. PMID:28253299

Continuum kinetic and multi-fluid simulations of classical sheaths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cagas, P.; Hakim, A.; Juno, J.

The kinetic study of plasma sheaths is critical, among other things, to understand the deposition of heat on walls, the effect of sputtering, and contamination of the plasma with detrimental impurities. The plasma sheath also provides a boundary condition and can often have a significant global impact on the bulk plasma. In this paper, kinetic studies of classical sheaths are performed with the continuum kinetic code, Gkeyll, which directly solves the Vlasov-Maxwell equations. The code uses a novel version of the finite-element discontinuous Galerkin scheme that conserves energy in the continuous-time limit. The fields are computed using Maxwell equations. Ionizationmore » and scattering collisions are included; however, surface effects are neglected. The aim of this work is to introduce the continuum kinetic method and compare its results with those obtained from an already established finite-volume multi-fluid model also implemented in Gkeyll. Novel boundary conditions on the fluids allow the sheath to form without specifying wall fluxes, so the fluids and fields adjust self-consistently at the wall. Our work demonstrates that the kinetic and fluid results are in agreement for the momentum flux, showing that in certain regimes, a multifluid model can be a useful approximation for simulating the plasma boundary. There are differences in the electrostatic potential between the fluid and kinetic results. Further, the direct solutions of the distribution function presented here highlight the non-Maxwellian distribution of electrons in the sheath, emphasizing the need for a kinetic model. The densities, velocities, and the potential show a good agreement between the kinetic and fluid results. But, kinetic physics is highlighted through higher moments such as parallel and perpendicular temperatures which provide significant differences from the fluid results in which the temperature is assumed to be isotropic. Besides decompression cooling, the heat flux is shown to play a role in the temperature differences that are observed, especially inside the collisionless sheath. Published by AIP Publishing.« less

Continuum kinetic and multi-fluid simulations of classical sheaths

DOE PAGES

Cagas, P.; Hakim, A.; Juno, J.; ...

2017-02-21

The kinetic study of plasma sheaths is critical, among other things, to understand the deposition of heat on walls, the effect of sputtering, and contamination of the plasma with detrimental impurities. The plasma sheath also provides a boundary condition and can often have a significant global impact on the bulk plasma. In this paper, kinetic studies of classical sheaths are performed with the continuum kinetic code, Gkeyll, which directly solves the Vlasov-Maxwell equations. The code uses a novel version of the finite-element discontinuous Galerkin scheme that conserves energy in the continuous-time limit. The fields are computed using Maxwell equations. Ionizationmore » and scattering collisions are included; however, surface effects are neglected. The aim of this work is to introduce the continuum kinetic method and compare its results with those obtained from an already established finite-volume multi-fluid model also implemented in Gkeyll. Novel boundary conditions on the fluids allow the sheath to form without specifying wall fluxes, so the fluids and fields adjust self-consistently at the wall. Our work demonstrates that the kinetic and fluid results are in agreement for the momentum flux, showing that in certain regimes, a multifluid model can be a useful approximation for simulating the plasma boundary. There are differences in the electrostatic potential between the fluid and kinetic results. Further, the direct solutions of the distribution function presented here highlight the non-Maxwellian distribution of electrons in the sheath, emphasizing the need for a kinetic model. The densities, velocities, and the potential show a good agreement between the kinetic and fluid results. But, kinetic physics is highlighted through higher moments such as parallel and perpendicular temperatures which provide significant differences from the fluid results in which the temperature is assumed to be isotropic. Besides decompression cooling, the heat flux is shown to play a role in the temperature differences that are observed, especially inside the collisionless sheath. Published by AIP Publishing.« less

An EQT-cDFT approach to determine thermodynamic properties of confined fluids.

PubMed

Mashayak, S Y; Motevaselian, M H; Aluru, N R

2015-06-28

We present a continuum-based approach to predict the structure and thermodynamic properties of confined fluids at multiple length-scales, ranging from a few angstroms to macro-meters. The continuum approach is based on the empirical potential-based quasi-continuum theory (EQT) and classical density functional theory (cDFT). EQT is a simple and fast approach to predict inhomogeneous density and potential profiles of confined fluids. We use EQT potentials to construct a grand potential functional for cDFT. The EQT-cDFT-based grand potential can be used to predict various thermodynamic properties of confined fluids. In this work, we demonstrate the EQT-cDFT approach by simulating Lennard-Jones fluids, namely, methane and argon, confined inside slit-like channels of graphene. We show that the EQT-cDFT can accurately predict the structure and thermodynamic properties, such as density profiles, adsorption, local pressure tensor, surface tension, and solvation force, of confined fluids as compared to the molecular dynamics simulation results.

Fault and fracture patterns in low porosity chalk and their potential influence on sub-surface fluid flow-A case study from Flamborough Head, UK

NASA Astrophysics Data System (ADS)

Sagi, D. A.; De Paola, N.; McCaffrey, K. J. W.; Holdsworth, R. E.

2016-10-01

To better understand fault zone architecture and fluid flow in mesoscale fault zones, we studied normal faults in chalks with displacements up to 20 m, at two representative localities in Flamborough Head (UK). At the first locality, chalk contains cm-thick, interlayered marl horizons, whereas at the second locality marl horizons were largely absent. Cm-scale displacement faults at both localities display ramp-flat geometries. Mesoscale fault patterns in the marl-free chalk, including a larger displacement fault (20 m) containing multiple fault strands, show widespread evidence of hydraulically-brecciated rocks, whereas clays smears along fault planes, and injected into open fractures, and a simpler fault zone architecture is observed where marl horizons are present. Hydraulic brecciation and veins observed in the marl-free chalk units suggest that mesoscale fault patterns acted as localized fault conduit allowing for widespread fluid flow. On the other hand, mesoscale fault patterns developed in highly fractured chalk, which contains interlayered marl horizons can act as localized barriers to fluid flow, due to the sealing effect of clays smears along fault planes and introduced into open fractures in the damage zone. To support our field observations, quantitative analyses carried out on the large faults suggest a simple fault zone in the chalk with marl units with fracture density/connectivity decreasing towards the protolith. Where marls are absent, density is high throughout the fault zone, while connectivity is high only in domains nearest the fault core. We suggest that fluid flow in fractured chalk is especially influenced by the presence of marls. When present, it can smear onto fault planes, forming localised barriers. Fluid flow along relatively large displacement faults is additionally controlled by the complexity of the fault zone, especially the size/geometry of weakly and intensely connected damage zone domains.

Are seismic velocity time-lapse changes due to fluid substitution or matrix dissolution? A CO2 sequestration study at Pohokura Field, New Zealand

NASA Astrophysics Data System (ADS)

Adam, L.; Sim, C. Y.; Macfarlane, J.; van Wijk, K.; Shragge, J. C.; Higgs, K.

2015-12-01

Time-lapse seismic signatures can be used to quantify fluid saturation and pressure changes in a reservoir undergoing CO2 sequestration. However, the injection of CO2 acidifies the water, which may dissolve and/or precipitate minerals. Understanding the impact on the rock frame from field seismic time-lapse changes remains an outstanding challenge. Here, we study the effects of carbonate-CO2-water reactions on the physical and elastic properties of rock samples with variable volumes of carbonate cementation. The effects of fluid substitution alone (brine to CO2) and those due to the combination of fluid substitution and mineral dissolution on time-lapse seismic signatures are studied by combining laboratory data, geophysical well-log data and 1-D seismic modeling. Nine rocks from Pohokura Field (New Zealand) are reacted with carbonic acid. The elastic properties are measured using a high-density laser-ultrasonic setup. We observe that P-wave velocity changes up to -19% and correlate with sandstone grain size. Coarse-grained sandstones show greater changes in elastic wave velocities due to dissolution than fine-grained sandstones. To put this in perspective, this velocity change is comparable to the effect of fluid substitution from brine to CO2. This can potentially create an ambiguity in the interpretation of the physical processes responsible for time-lapse signatures in a CO2injection scenario. The laboratory information is applied onto well-log data to model changes in elastic properties of sandstones at the well-log scale. Well-logs and core petrographic analyses are used to find an elastic model that best describes the observed elastic waves velocities in the cemented reservoir sandstones. The Constant-cement rock physics model is found to predict the elastic behaviour of the cemented sandstones. A possible late-time sequestration scenario is that both mineral dissolution and fluid substitution occur in the reservoir. 1-D synthetic seismograms show that seismic amplitudes can change up to 126% in such a scenario. Our work shows that it is important to consider that time-lapse seismic signatures in carbonate-cemented reservoirs can result not only from fluid and pressure changes but also potentially from chemical reaction between CO2-water mixtures and carbonate cemented sandstones.

Measurement potential of laser speckle velocimetry

NASA Technical Reports Server (NTRS)

Adrian, R. J.

1982-01-01

Laser speckle velocimetry, the measurement of fluid velocity by measuring the translation of speckle pattern or individual particles that are moving with the fluid, is described. The measurement is accomplished by illuminating the fluid with consecutive pulses of Laser Light and recording the images of the particles or the speckles on a double exposed photographic plate. The plate contains flow information throughout the image plane so that a single double exposure may provide data at hundreds or thousands of points in the illuminated region of the fluid. Conventional interrogation of the specklegram involves illuminating the plate to form Young's fringes, whose spacing is inversely proportional to the speckle separation. Subsequently the fringes are digitized and analyzed in a computer to determine their frequency and orientation, yielding the velocity magnitude and orientation. The Young's fringe technique is equivalent to performing a 2-D spatial correlation of the double exposed specklegram intensity pattern, and this observation suggests that correlation should be considered as an alternative processing method. The principle of the correlation technique is examined.

Serpentinite Mud Volcanism: Observations, Processes, and Implications

NASA Astrophysics Data System (ADS)

Fryer, Patricia

2012-01-01

Large serpentinite mud volcanoes form on the overriding plate of the Mariana subduction zone. Fluids from the descending plate hydrate (serpentinize) the forearc mantle and enable serpentinite muds to rise along faults to the seafloor. The seamounts are direct windows into subduction processes at depths far too deep to be accessed by any known technology. Fluid compositions vary with distance from the trench, signaling changes in chemical reactions as temperature and pressure increase. The parageneses of rocks in the mudflows permits us to constrain the physical conditions of the decollement region. If eruptive episodes are related to seismicity, seafloor observatories at these seamounts hold the potential to capture a subduction event and trace the effects of eruption on the biological communities that the slab fluids support, such as extremophile Archaea. The microorganisms that inhabit this high-pH, extreme environment support their growth by utilizing chemical constituents present in the slab fluids. Some researchers now contend that the serpentinization process itself may hold the key to the origin of life on Earth.

Serpentinite mud volcanism: observations, processes, and implications.

PubMed

Fryer, Patricia

2012-01-01

Large serpentinite mud volcanoes form on the overriding plate of the Mariana subduction zone. Fluids from the descending plate hydrate (serpentinize) the forearc mantle and enable serpentinite muds to rise along faults to the seafloor. The seamounts are direct windows into subduction processes at depths far too deep to be accessed by any known technology. Fluid compositions vary with distance from the trench, signaling changes in chemical reactions as temperature and pressure increase. The parageneses of rocks in the mudflows permits us to constrain the physical conditions of the decollement region. If eruptive episodes are related to seismicity, seafloor observatories at these seamounts hold the potential to capture a subduction event and trace the effects of eruption on the biological communities that the slab fluids support, such as extremophile Archaea. The microorganisms that inhabit this high-pH, extreme environment support their growth by utilizing chemical constituents present in the slab fluids. Some researchers now contend that the serpentinization process itself may hold the key to the origin of life on Earth.

Affinity adsorption of glucose degradation products improves the biocompatibility of conventional peritoneal dialysis fluid.

PubMed

Ishikawa, Naoyoshi; Miyata, Toshio; Ueda, Yasuhiko; Inagi, Reiko; Izuhara, Yuko; Yuzawa, Hiroko; Onogi, Hiroshi; Nishina, Makoto; Nangaku, Masaomi; Van Ypersele De Strihou, Charles; Kurokawa, Kiyoshi

2003-01-01

Reactive carbonyl compounds (RCOs) present in peritoneal dialysis (PD) fluid have been incriminated in the progressive deterioration of the peritoneal membrane in long-term PD patients. They are initially present in fresh conventional heat-sterilized glucose PD fluid and are supplemented during dwell time by the diffusion of blood RCOs within the peritoneal cavity. In the present study, RCO entrapping agents were immobilized on affinity beads to adsorb RCOs both in fresh PD fluid and in PD effluent. The RCO trapping potential of various compounds was assessed in vitro first by dissolving them in the tested fluid and subsequently after coupling with either epoxy- or amino-beads. The tested fluids include fresh heat-sterilized glucose and non-glucose PD fluids, and PD effluent. Their RCOs contents, that is, glyoxal (GO), methylglyoxal (MGO), 3-deoxyglucosone (3-DG), formaldehyde, 5-hydroxymethylfuraldehyde, acetaldehyde, and 2-furaldehyde were monitored by reverse-phase high-pressure liquid chromatography. The biocompatibility of PD fluid was assessed by a cytotoxic assay with either human epidermoid cell line A431 cells or with primary cultured human peritoneal mesothelial cells. Among the tested RCO entrapping agents, hydrazine coupled to epoxy-beads proved the most efficient. It lowered the concentrations of three dicarbonyl compounds (GO, MGO, and 3-DG) and those of aldehydes present in fresh heat-sterilized glucose PD fluid toward the low levels observed in filter-sterilized glucose PD fluid. It did not change the glucose and electrolytes concentration of the PD fluid but raised its pH from 5.2 to 5.9. Hydrazine-coupled epoxy-bead also lowered the PD effluent content of total RCOs, measured by the 2,4-dinitrophenylhydrazone (DNPH) method. The cytotoxicity of heat-sterilized PD fluid incubated with hydrazine-coupled epoxy-beads was decreased to the level observed in filter-sterilized PD fluid as the result of the raised pH and the lowered RCOs levels. Hydrazine-coupled epoxy-beads reduce the levels of a variety of dicarbonyls and aldehydes present in heat-sterilized glucose PD fluid to those in filter-sterilized PD fluid, without altering glucose, lactate, and electrolytes contents but with a rise in pH. Incubated with PD effluents, it is equally effective in reducing the levels of serum-derived RCOs. RCO entrapping agents immobilized on affinity beads improve in vitro the biocompatibility of conventional heat-sterilized glucose PD fluid. Their clinical applicability requires further studies.

Reduction of hexavalent chromium by fasted and fed human gastric fluid. I. Chemical reduction and mitigation of mutagenicity.

PubMed

De Flora, Silvio; Camoirano, Anna; Micale, Rosanna T; La Maestra, Sebastiano; Savarino, Vincenzo; Zentilin, Patrizia; Marabotto, Elisa; Suh, Mina; Proctor, Deborah M

2016-09-01

Evaluation of the reducing capacity of human gastric fluid from healthy individuals, under fasted and fed conditions, is critical for assessing the cancer hazard posed by ingested hexavalent chromium [Cr(VI)] and for developing quantitative physiologically-based pharmacokinetic models used in risk assessment. In the present study, the patterns of Cr(VI) reduction were evaluated in 16 paired pre- and post-meal gastric fluid samples collected from 8 healthy volunteers. Human gastric fluid was effective both in reducing Cr(VI), as measured by using the s-diphenylcarbazide colorimetric method, and in attenuating mutagenicity in the Ames test. The mean (±SE) Cr(VI)-reducing ability of post-meal samples (20.4±2.6μgCr(VI)/mL gastric fluid) was significantly higher than that of pre-meal samples (10.2±2.3μgCr(VI)/mL gastric fluid). When using the mutagenicity assay, the decrease of mutagenicity produced by pre-meal and post-meal samples corresponded to reduction of 13.3±1.9 and 25.6±2.8μgCr(VI)/mL gastric fluid, respectively. These data are comparable to parallel results conducted by using speciated isotope dilution mass spectrometry. Cr(VI) reduction was rapid, with >70% of total reduction occurring within 1min and 98% of reduction is achieved within 30min with post-meal gastric fluid at pH2.0. pH dependence was observed with decreasing Cr(VI) reducing capacity at higher pH. Attenuation of the mutagenic response is consistent with the lack of DNA damage observed in the gastrointestinal tract of rodents following administration of ≤180ppm Cr(VI) for up to 90days in drinking water. Quantifying Cr(VI) reduction kinetics in the human gastrointestinal tract is necessary for assessing the potential hazards posed by Cr(VI) in drinking water. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Reactive transport modeling of ferroan dolomitization by seawater interaction with mafic igneous dikes and carbonate host rock at the Latemar platform, Italy

NASA Astrophysics Data System (ADS)

Blomme, Katreine; Fowler, Sarah Jane; Bachaud, Pierre

2017-04-01

The Middle Triassic Latemar carbonate platform, northern Italy, has featured prominently in the longstanding debate regarding dolomite petrogenesis [1-4]. Recent studies agree that ferroan and non-ferroan dolomite replaced calcite in limestone during reactive fluid flow at <0.1 GPa and 40-80°C. Regional igneous activity drove heating that provided kinetically favorable conditions for the replacement reaction. However, the origin of the dolomitizing fluid is unclear. Seawater may have been an important component, but its Fe concentrations are insufficient to account for ferroan dolomite. New field, petrographic, XRD, and geochemical data document a spatial, temporal, and geochemical link between ferroan replacement dolomite and altered mafic igneous dikes that densely intrude the platform. A critical observation is that ferroan dolomite abundances increase towards the dikes. We hypothesize that seawater interacted with mafic minerals in the dikes, leading to Fe enrichment in the fluid that subsequently participated in dolomitization. This requires that dolomite formation was preceded by dike alteration reactions that liberated Fe and did not consume Mg. Another requirement is that ferroan and non-ferroan dolomite (instead of other Fe- and Mg-bearing minerals) formed during fluid circulation within limestone host rock. We present reactive transport numerical simulations (Coores-Arxim, [5]) that predict equilibrium mineral assemblages and the evolution of fluid dolomitizing potential from dike crystallization, through dike alteration by seawater, to replacement dolomitization in carbonate host rock. The simulations are constrained by observations. A major advantage of the simulations is that stable mineral assemblages are identified based on a forward modeling approach. In addition, the dominant igneous minerals (plagioclase, clinopyroxene olivine and their alteration products) are solid solutions. Most reactive transport simulations of carbonate petrogenesis do not share these benefits (e.g. [6]). Predicted alteration mineral assemblages are consistent with observations on dikes and with ferroan and non-ferroan dolomite genesis. The simulation results also show that fluid dolomitizing potential (Mg/Ca and Fe/Mg) increases during dissolution of igneous solid solution minerals. Enrichment in fluid Fe concentration is sufficient to stabilize ferroan replacement dolomite. Consistent with field observations, ferroan dolomite forms closest to dikes due to the abundance of Fe associated with the dikes. This leads to depletion of Fe in fluid flowing away from dikes and formation of non-ferroan replacement dolomite further afield. References S.K. Carmichael, J.M. Ferry, W.F. McDonough, Formation of replacement dolomite in the Latemar carbonate buildup, Dolomites, Northern Italy: Part 1. Field relations, mineralogy and geochemistry, Am. J. Sci. 308 (2008) 851-884. J.M. Ferry, B.H. Passey, C. Vasconcelos, J.M. Eiler, Formation of dolomite at 40 - 80 °C in the Latemar carbonate buildup, Dolomites, Italy, from clumped isotope thermometry, Geology. 39 (2011) 571-574. C. Jacquemyn, M. Huysmans, D. Hunt, G. Casini, R. Swennen, Multi-scale three-dimensional distribution of fracture- and igneous intrusion- controlled hydrothermal dolomite from digital outcrop model, Latemar platform, Dolomites, northern Italy, Am. Assoc. Pet. Geol. Bull. 99 (2015) 957-984. C. Jacquemyn, H. El Desouky, D. Hunt, G. Casini, R. Swennen, Dolomitization of the Latemar platform: Fluid flow and dolomite evolution, Mar. Pet. Geol. 55 (2014) 43-67. L. Trenty, A. Michel, E. Tillier, Y. Le Gallo, A Sequential Splitting Strategy for CO2 Storage Modelling, in: ECMOR X - 10th Eur. Conf. Math. Oil Recover., 2006. T. Gabellone, F. Whitaker, Secular variations in seawater chemistry controlling dolomitisation in shallow reflux systems: Insights from reactive transport modelling, Sedimentology. 63 (2016) 1233-1259.

Characterization and Modeling of Dust Emissions from an Instrumented Mine Tailings Site

NASA Astrophysics Data System (ADS)

Betterton, E. A.; Stovern, M.; Saez, A.; Csavina, J. L.; Felix Villar, O. I.; Field, J. P.; Rine, K. P.; Russell, M. R.; Saliba, P.

2012-12-01

Mining operations are potential sources of airborne particulate metal and metalloid contaminants through both direct smelter emissions and wind erosion of mine tailings. The warmer, drier conditions predicted for the Southwestern US by climate models may make contaminated atmospheric dust and aerosols increasingly important, due to potential deleterious effects on human health and ecology. Dust emissions and dispersion of contaminants from the Iron King Mine tailings in Dewey-Humboldt, Arizona, a Superfund site, are currently being investigated through in situ field measurements and computational fluid dynamics modeling. These tailings are heavily contaminated with lead and arsenic. We report on the chemical characterization of atmospheric dust and aerosol sampled near the mine tailings. Instrumented eddy flux towers were also setup on the mine tailings to give both spatial and temporal dust observations. The eddy flux towers have multiple DUSTTRAK monitors as well as weather stations. These in situ observations allow us to assess spatial distribution of suspended particulate. Using the DUSTTRAK flux tower observations at 10-second resolution in conjunction with a computational fluid dynamics model, we have been able to model dust transport from the mine tailings to downwind areas. In order to improve the accuracy of the dust transport simulations both regional topographical features and local weather patterns have been incorporated into the model simulations.

Exercise Effects on the Course of Gray Matter Changes Over 70 Days of Bed Rest

NASA Technical Reports Server (NTRS)

Koppelmans, V.; Ploutz-Snyder, L.; DeDios, Y. E.; Wood, S. J.; Reuter-Lorenz, P. A.; Kofman, I.; Bloomberg, J. J.; Mulavara, A. P.; Seidler, R. D.

2014-01-01

Long duration spaceflight affects posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes through direct effects on peripheral changes that result from reduced vestibular stimulation and body unloading. Effects of microgravity on sensorimotor function have been investigated on earth using bed rest studies. Long duration bed rest serves as a space-flight analogue because it mimics microgravity in body unloading and bodily fluid shifts. It has been hypothesized that the cephalad fluid shift that has been observed in microgravity could potentially affect central nervous system function and structure, and thereby indirectly affect sensorimotor or cognitive functioning. Preliminary results of one of our ongoing studies indeed showed that 70 days of long duration head down-tilt bed rest results in focal changes in gray matter volume from pre-bed rest to various time points during bed rest. These gray matter changes that could reflect fluid shifts as well as neuroplasticity were related to decrements in motor skills such as maintenance of equilibrium. In consideration of the health and performance of crewmembers both inand post-flight we are currently conducting a study that investigates the potential preventive effects of exercise on gray matter and motor performance changes that we observed over the course of bed rest. Numerous studies have shown beneficial effects of aerobic exercise on brain structure and cognitive performance in healthy and demented subjects over a large age range. We therefore hypothesized that an exercise intervention in bed rest could potentially mitigate or prevent the effects of bed rest on the central nervous system. Here we present preliminary outcomes of our study.

Focusing fluids towards the arc: the role of rheology and reactions

NASA Astrophysics Data System (ADS)

Wilson, C. R.; Spiegelman, M. W.

2014-12-01

Aqueous fluids released from the down-going slab in subduction zones are generally thought to be the cause of arc volcanism. However there is a significant discrepancy between the consistent location of the volcanic front with respect to intermediate depth earthquakes (e.g. 100+/-40 km; England et al., GJI, 2004, Syracuse & Abers, G-cubed, 2006) and the large depth range over which dehydration reactions are predicted to occur in the slab (e.g. 80-250 km; van Keken et al., JGR, 2011). By coupling the fluid flow to the solid rheology through compaction pressure, recent numerical models (Wilson et al., EPSL, 2014) demonstrated a number of focusing mechanisms that can be invoked to explain this apparent discrepancy. Most notable among these were permeability channels within the slab. These were shown to be highly effective in transporting fluid from deeper fluid sources along the slab towards the shallowest source. In the presence of these channels the majority of the fluid is released into the mantle wedge far shallower and closer to the arc than it was originally generated. While observations consistent with free fluids in the slab have been reported (e.g. Shiina et al., GRL, 2013), it is possible that changing the rheology and reactivity of the slab can change the efficiency of in-slab transport. We present a series of simplified model problems of fluid flow within the slab and mantle wedge demonstrating the potential effect of these processes on fluid flux. In particular, pseudo-1D models show that if fluids can efficiently rehydrate slab minerals, then these reactions can shut down fluid pathways within the slab, resulting in deeper release of fluid into the mantle wedge. However, the behavior in full subduction zone models remains to be determined.

Rheological investigation of high-acyl gellan gum hydrogel and its mixtures with simulated body fluids.

PubMed

Osmałek, Tomasz Zbigniew; Froelich, Anna; Jadach, Barbara; Krakowski, Marek

2018-05-01

Purpose Most of the studies concerning gellan have been focused on its application as a food ingredient, however, gellan is often considered as a candidate for the development of novel pharmaceutical formulations. Taking into account that gellan is ion-sensitive, it can be assumed that its initial mechanical properties can change upon contact with body secretions. Therefore, the aim of the work was to investigate the rheological properties of pure high-acyl gellan gum hydrogel (0.4%) and its mixtures with selected simulated body fluids. Methods The rheological investigations were performed on rotational rheometer and included oscillatory temperature, amplitude, and frequency sweeping. The results enabled estimation of the linear viscoelastic regime, calculation of the cross-over points, and percentage of structure recovery. Results In the case of pure hydrogel no evidence of thermosensitivity was observed in the range of 20-40°C. In pH = 1.2 (NaCl/HCl) the hydrogel structure was almost entirely destroyed. Mixing with phosphate buffer (pH = 4.5) resulted in higher gel strength than after dilution with deionized water. The opposite effect was observed in the case of pH = 7.4. The studies performed for the mixture of GG hydrogel and mucin indicated interaction between the components. The hydrogel elasticity increased in the presence of simulated tear, but decreased in simulated saliva and vaginal fluid. Conclusions In this study, it was shown that the stability of a three-dimensional gellan structure may be affected by pH and the presence of mucin which most probably competed with gellan gum in divalent cations binding. The observations presented in this study may be important in terms of potential application of gellan gum as a potential carrier in drug delivery systems.

PVA and PEG functionalised LSMO nanoparticles for magnetic fluid hyperthermia application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jadhav, S.V.; Nikam, D.S.; Khot, V.M.

2015-04-15

La{sub 0.7}Sr{sub 0.3}MnO{sub 3} magnetic nanoparticles are synthesized by a solution combustion method and functionalised with polyvinyl alcohol and polyethylene glycol. The induction heating characteristics of coated magnetic nanoparticles (42 °C) were observed at a reasonably low concentration (5 mg/mL). Remarkably, coated magnetic nanoparticles exhibited a promisingly high specific absorption rate with varying magnetic field and constant frequency. The surface analysis is carried out by X-ray photoelectron spectroscopy. A reduction in the agglomeration of the particles was observed when the magnetic nanoparticles were functionalised with polyvinyl alcohol or polyethylene glycol and can be confirmed by transmission electron microscopy and dynamicmore » light scattering studies. Vibrating sample magnetometer measurements indicate superparamagnetic behaviour at room temperature before and after coating. Colloidal stability revealed a considerably higher zeta potential value for coated system. In vitro cytotoxicity test of the magnetic nanoparticles indicates that coated nanoparticles have no significant effect on cell viability within the tested concentrations (1–5 mg mL{sup -1}) as compared to uncoated La{sub 0.7}Sr{sub 0.3}MnO{sub 3}. All these findings explore the potentiality of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} nanoparticles for magnetic fluid hyperthermia. - Highlights: • Surface functionalization of LSMO nanoparticles — first time with PVA • Surface functionalization of LSMO nanoparticles — first time with PEG • BSA protein — first time used as dispersion medium for stability of LSMO nanoparticles • The heating ability observed at low concentration • Improved efficiency of magnetic fluid hyperthermia treatment with surfactants.« less

Focusing Fluids towards the Arc: the Role of Rehydration Reactions and Rheology

NASA Astrophysics Data System (ADS)

Wilson, C. R.; Spiegelman, M. W.; Van Keken, P. E.; Hacker, B. R.

2015-12-01

Aqueous fluids released from the down-going slab in subduction zones are generally thought to be the cause of arc volcanism. However there is a significant discrepancy between the consistent location of the volcanic front with respect to intermediate depth earthquakes (e.g. 100+/-40 km; England et al., GJI, 2004, Syracuse & Abers, G-cubed, 2006) and the large depth range over which dehydration reactions are predicted to occur in the slab (e.g. 80-250 km; van Keken et al., JGR, 2011).By coupling the fluid flow to the solid rheology through compaction pressure, recent numerical models (Wilson et al., EPSL, 2014) demonstrated a number of focusing mechanisms that can be invoked to explain this apparent discrepancy. Most notable among these were permeability channels within the slab. These were shown to be highly effective in transporting fluid from deeper fluid sources along the slab towards the shallowest source. In the presence of these channels the majority of the fluid is released into the mantle wedge far shallower and closer to the arc than it was originally generated.While observations consistent with free fluids in the slab have been reported (e.g. Shiina et al., GRL, 2013), it is possible that changing the reactivity and rheology of the slab can change the efficiency of in-slab transport (e.g. Wada et al., EPSL, 2012, Faccenda et al., G3, 2012). We present a series of simplified model problems of fluid flow within the slab and mantle wedge demonstrating the potential effect of these processes on fluid flux. In particular, pseudo-1D models show that if fluids can efficiently rehydrate slab minerals, then these reactions can shut down fluid pathways within the slab, resulting in deeper release of fluid into the mantle wedge. We will expand these results to consider the effects of rehydration in 2-D calculations. In addition, our previous models have considered only the simplest rheologies and geometries for the slab. We will also discuss new results that investigate simple visco-plastic models for the slab that limit the stresses and maximum viscosities in the slab for more realistic slab geometries. Despite these additional complexities, the robust observation of the location of the volcanic front with respect to intermediate depth earthquakes provides a clear test for evaluating subduction zone models.

Organic synthesis during fluid mixing in hydrothermal systems

NASA Astrophysics Data System (ADS)

Shock, Everett L.; Schulte, Mitchell D.

1998-12-01

Hydrothermal circulation can lead to fluid mixing on any planet with liquid water and a source of heat. Aqueous fluids with differing compositions, especially different oxidation states, are likely to be far from thermodynamic equilibrium when they mix, and provide a source of free energy that can drive organic synthesis from CO2 and H2, and/or supply a source of geochemical energy to chemolithoautotrophic organisms. Results are presented that quantify the potential for organic synthesis during unbuffered fluid mixing in present submarine hydrothermal systems, as well as hypothetical systems that may have existed on the early Earth and Mars. Dissolved hydrogen, present in submarine hydrothermal fluids owing to the high-temperature reduction of H2O as seawater reacts with oceanic crustal rocks, provides the reduction potential and the thermodynamic drive for organic synthesis from CO2 (or bicarbonate) as hydrothermal fluids mix with seawater. The potential for organic synthesis is a strong function of the H2 content of the hydrothermal fluid, which is, in turn, a function of the prevailing oxidation state controlled by the composition of the rock that hosts the hydrothermal system. Hydrothermal fluids with initial oxidation states at or below those set by the fayalite-magnetite-quartz mineral assemblage show the greatest potential for driving organic synthesis. These calculations show that it is thermodynamically possible for 100% of the carbon in the mixed fluid to be reduced to a mixture of carboxylic acids, alcohols, and ketones in the range 250-50°C as cold seawater mixes with the hydrothermal fluid. As the temperature drops, larger organic molecules are favored, which implies that fluid mixing could drive the geochemical equivalent of a metabolic system. This enormous reduction potential probably drives a large portion of the primary productivity around present seafloor hydrothermal vents and would have been present in hydrothermal systems on the early Earth or Mars. The single largest control on the potential for organic synthesis is the composition of the rock that hosts the hydrothermal system.

Thermal transpiration: A molecular dynamics study

NASA Astrophysics Data System (ADS)

T, Joe Francis; Sathian, Sarith P.

2014-12-01

Thermal transpiration is a phenomenon where fluid molecules move from the cold end towards the hot end of a channel under the influence of longitudinal temperature gradient alone. Although the phenomenon of thermal transpiration is observed at rarefied gas conditions in macro systems, the phenomenon can occur at atmospheric pressure if the characteristic dimensions of the channel is less than 100 nm. The flow through these nanosized channels is characterized by the free molecular flow regimes and continuum theory is inadequate to describe the flow. Thus a non-continuum method like molecular dynamics (MD) is necessary to study such phenomenon. In the present work, MD simulations were carried out to investigate the occurance of thermal transpiration in copper and platinum nanochannels at atmospheric pressure conditions. The mean pressure of argon gas confined inside the nano channels was maintained around 1 bar. The channel height is maintained at 2nm. The argon atoms interact with each other and with the wall atoms through the Lennard-Jones potential. The wall atoms are modelled using an EAM potential. Further, separate simulations were carried out where a Harmonic potential is used for the atom-atom interaction in the platinum channel. A thermally insulating wall was introduced between the low and high temperature regions and those wall atoms interact with fluid atoms through a repulsive potential. A reduced cut off radius were used to achieve this. Thermal creep is induced by applying a temperature gradient along the channel wall. It was found that flow developed in the direction of the increasing temperature gradient of the wall. An increase in the volumetric flux was observed as the length of the cold and the hot regions of the wall were increased. The effect of temperature gradient and the wall-fluid interaction strength on the flow parameters have been studied to understand the phenomenon better.

Rapid Diagnosis of Infection in the Critically Ill, a Multicenter Study of Molecular Detection in Bloodstream Infections, Pneumonia, and Sterile Site Infections*

PubMed Central

Brealey, David; Libert, Nicolas; Abidi, Nour Elhouda; O’Dwyer, Michael; Zacharowski, Kai; Mikaszewska-Sokolewicz, Malgorzata; Schrenzel, Jacques; Simon, François; Wilks, Mark; Picard-Maureau, Marcus; Chalfin, Donald B.; Ecker, David J.; Sampath, Rangarajan; Singer, Mervyn

2015-01-01

Objective: Early identification of causative microorganism(s) in patients with severe infection is crucial to optimize antimicrobial use and patient survival. However, current culture-based pathogen identification is slow and unreliable such that broad-spectrum antibiotics are often used to insure coverage of all potential organisms, carrying risks of overtreatment, toxicity, and selection of multidrug-resistant bacteria. We compared the results obtained using a novel, culture-independent polymerase chain reaction/electrospray ionization-mass spectrometry technology with those obtained by standard microbiological testing and evaluated the potential clinical implications of this technique. Design: Observational study. Setting: Nine ICUs in six European countries. Patients: Patients admitted between October 2013 and June 2014 with suspected or proven bloodstream infection, pneumonia, or sterile fluid and tissue infection were considered for inclusion. Interventions: None. Measurements and Main Results: We tested 616 bloodstream infection, 185 pneumonia, and 110 sterile fluid and tissue specimens from 529 patients. From the 616 bloodstream infection samples, polymerase chain reaction/electrospray ionization-mass spectrometry identified a pathogen in 228 cases (37%) and culture in just 68 (11%). Culture was positive and polymerase chain reaction/electrospray ionization-mass spectrometry negative in 13 cases, and both were negative in 384 cases, giving polymerase chain reaction/electrospray ionization-mass spectrometry a sensitivity of 81%, specificity of 69%, and negative predictive value of 97% at 6 hours from sample acquisition. The distribution of organisms was similar with both techniques. Similar observations were made for pneumonia and sterile fluid and tissue specimens. Independent clinical analysis of results suggested that polymerase chain reaction/electrospray ionization-mass spectrometry technology could potentially have resulted in altered treatment in up to 57% of patients. Conclusions: Polymerase chain reaction/electrospray ionization-mass spectrometry provides rapid pathogen identification in critically ill patients. The ability to rule out infection within 6 hours has potential clinical and economic benefits. PMID:26327198

Body heat storage during physical activity is lower with hot fluid ingestion under conditions that permit full evaporation.

PubMed

Bain, A R; Lesperance, N C; Jay, O

2012-10-01

To assess whether, under conditions permitting full evaporation, body heat storage during physical activity measured by partitional calorimetry would be lower with warm relative to cold fluid ingestion because of a disproportionate increase in evaporative heat loss potential relative to internal heat transfer with the ingested fluid. Nine males cycled at 50% VO(2max) for 75 min at 23.6 ± 0.6 °C and 23 ± 11% RH while consuming water of either 1.5 °C, 10 °C, 37 °C or 50 °C in four 3.2 mL kg(-1) boluses. The water was administered 5 min before and 15, 30 and 45 min following the onset of exercise. No differences in metabolic heat production, sensible or respiratory heat losses (all P > 0.05) were observed between fluid temperatures. However, while the increased internal heat loss with cold fluid ingestion was paralleled by similar reductions in evaporative heat loss potential at the skin (E(sk) ) with 10 °C (P = 0.08) and 1.5 °C (P = 0.55) fluid, the increased heat load with warm (50 °C) fluid ingestion was accompanied by a significantly greater E(sk) (P = 0.04). The resultant calorimetric heat storage was lower with 50 °C water ingestion in comparison to 1.5 °C, 10 °C and 37 °C (all P < 0.05). In contrast, heat storage derived conventionally using thermometry yielded higher values following 50 °C fluid ingestion compared to 1.5 °C (P = 0.025). Under conditions permitting full sweat evaporation, body heat storage is lower with warm water ingestion, likely because of disproportionate modulations in sweat output arising from warm-sensitive thermosensors in the esophagus/stomach. Local temperature changes of the rectum following fluid ingestion exacerbate the previously identified error of thermometric heat storage estimations. © 2012 The Authors Acta Physiologica © 2012 Scandinavian Physiological Society.

Photoacoustic Doppler effect from flowing small light-absorbing particles.

PubMed

Fang, Hui; Maslov, Konstantin; Wang, Lihong V

2007-11-02

From the flow of a suspension of micrometer-scale carbon particles, the photoacoustic Doppler shift is observed. As predicted theoretically, the observed Doppler shift equals half of that in Doppler ultrasound and does not depend on the direction of laser illumination. This new physical phenomenon provides a basis for developing photoacoustic Doppler flowmetry, which can potentially be used for detecting fluid flow in optically scattering media and especially low-speed blood flow of relatively deep microcirculation in biological tissue.

Role of tumor necrosis factor-alpha and platelet-activating factor in neoangiogenesis induced by synovial fluids of patients with rheumatoid arthritis.

PubMed

Lupia, E; Montrucchio, G; Battaglia, E; Modena, V; Camussi, G

1996-08-01

The aim of the present study was to investigate in vivo in a mouse model the stimulation of neoangiogenesis by synovial fluids of patients with rheumatoid arthritis (RA) and to determine the role of tumor necrosis factor (TNF)-alpha and platelet-activating factor (PAF) in the formation of new vessels. Angiogenesis was studied in a mouse model in which Matrigel, injected subcutaneously, was used as a vehicle for the delivery of potential angiogenic stimuli. Synovial fluids of patients with RA but not with osteoarthritis (OA) were shown to induce neoangiogenesis. Since synovial fluid of patients with RA contained significantly higher levels of TNF-alpha-like bioactivity and of PAF than that of patients with OA, the role of these mediators was evaluated by using an anti-TNF-alpha neutralizing monoclonal antibody (mAb) and a PAF receptor antagonist, WEB 2170. When added to Matrigel, anti-TNF-alpha mAb and particularly WEB 2170 significantly reduced neoangiogenesis induced by synovial fluids of RA patients. Moreover, PAF extracted and purified from synovial fluid induced angiogenesis. These results suggest that the neoangiogenesis observed in rheumatoid synovitis may be due, at least in part, to the angiogenic effect of locally produced TNF-alpha and PAF.

Secretory NaCl and volume flow in renal tubules.

PubMed

Beyenbach, K W

1986-05-01

This review attempts to give a retrospective survey of the available evidence concerning the secretion of NaCl and fluid in renal tubules of the vertebrate kidney. In the absence of glomerular filtration, epithelial secretory mechanisms, which to this date have not been elucidated, are responsible for the renal excretion of NaCl and water in aglomerular fish. However, proximal tubules isolated from glomerular fish kidneys of the flounder, killifish, and the shark also have the capacity to secrete NaCl and fluid. In shark proximal tubules, fluid secretion appears to be driven via secondary active transport of Cl. In another marine vertebrate, the sea snake, secretion of Na (presumably NaCl) and fluid is observed in freshwater-adapted and water-loaded animals. Proximal tubules of mammals can be made to secrete NaCl in vitro together with secretion of aryl acids. An epithelial cell line derived from dog kidney exhibits secondary active secretion of Cl when stimulated with catecholamines. Tubular secretion of NaCl and fluid may serve a variety of renal functions, all of which are considered here. The occurrence of NaCl and fluid secretion in glomerular proximal tubules of teleosts, elasmobranchs, and reptiles and in mammalian renal tissue cultures suggests that the genetic potential for NaCl secretion is present in every vertebrate kidney.

Intra-slab COH fluid fluxes evidenced by fluid-mediated decarbonation of lawsonite eclogite-facies altered oceanic metabasalts

NASA Astrophysics Data System (ADS)

Vitale Brovarone, Alberto; Chu, Xu; Martin, Laure; Ague, Jay J.; Monié, Patrick; Groppo, Chiara; Martinez, Isabelle; Chaduteau, Carine

2018-04-01

The interplay between the processes controlling the mobility of H2O and C-bearing species during subduction zone metamorphism exerts a critical control on plate tectonics and global volatile recycling. Here we present the first study on fresh, carbonate-bearing, lawsonite eclogite-facies metabasalts from Alpine Corsica, France, which reached the critical depths at which important devolatilization reactions occur in subducting slabs. The studied samples indicate that the evolution of oceanic crustal sequences subducted under present-day thermal regimes is dominated by localized fluid-rock interactions that are strongly controlled by the nature and extent of inherited (sub)seafloor hydrothermal processes, and by the possibility of deep fluids to be channelized along inherited or newly-formed discontinuities. Fluid channelization along inherited discontinuities controlled local rehydration and dehydration/decarbonation reactions and the stability of carbonate and silicate minerals at the blueschist-eclogite transition. Fluid-mediated decarbonation was driven by upward, up-temperature fluid flow in the inverted geothermal gradient of a subducting oceanic slab, a process that has not been documented in natural samples to date. We estimate that the observed fluid-rock reactions released 20-60 kg CO2 per m3 of rock (i.e. 0.7-2.1 wt% CO2), which is in line with the values predicted from decarbonation of metabasalts in open systems at these depths. Conversely, the estimated time-integrated fluid fluxes (20-50 t/m2) indicate that the amount of carbon transported by channelized fluid flow within the volcanic part of subducting oceanic plates is potentially much higher than previous numerical estimates, testifying to the percolation of C-bearing fluids resulting from devolatilization/dissolution processes operative in large reservoirs.

Thermo-Physical Properties of Intermediate Temperature Heat Pipe Fluids

NASA Technical Reports Server (NTRS)

Beach, Duane E. (Technical Monitor); Devarakonda, Angirasa; Anderson, William G.

2005-01-01

Heat pipes are among the most promising technologies for space radiator systems. The paper reports further evaluation of potential heat pipe fluids in the intermediate temperature range of 400 to 700 K in continuation of two recent reports. More thermo-physical property data are examined. Organic, inorganic, and elemental substances are considered. The evaluation of surface tension and other fluid properties are examined. Halides are evaluated as potential heat pipe fluids. Reliable data are not available for all fluids and further database development is necessary. Many of the fluids considered are promising candidates as heat pipe fluids. Water is promising as a heat pipe fluid up to 500 to 550 K. Life test data for thermo-chemical compatibility are almost non-existent.

Thermo-Physical Properties of Intermediate Temperature Heat Pipe Fluids

NASA Technical Reports Server (NTRS)

Devarakonda, Angirasa; Anderson, William G.

2004-01-01

Heat pipes are among the most promising technologies for space radiator systems. The paper reports further evaluation of potential heat pipe fluids in the intermediate temperature range of 400 to 700 K in continuation of two recent reports. More thermo-physical property data are examined. Organic, inorganic and elemental substances are considered. The evaluation of surface tension and other fluid properties are examined. Halides are evaluated as potential heat pipe fluids. Reliable data are not available for all fluids and further database development in necessary. Many of the fluids considered are promising candidates as heat pipe fluids. Water is promising as a heat pipe fluid up to 500-550 K. Life test data for thermo-chemical compatibility are almost non-existent.

Antioxidant and Antilipid Peroxidation Potential of Supercritical Fluid Extract and Ethanol Extract of Leaves of Vitex Negundo Linn.

PubMed Central

Nagarsekar, K. S.; Nagarsenker, M. S.; Kulkarni, S. R.

2011-01-01

Supercritical fluid extract and ethanol extract of Vitex negundo Linn. were subjected to the chromatographic evaluation for identification of their constituents. Free radical scavenging activity of both extracts was studied by subjecting them to DPPH assay. IC50 values of ethanol and supercritical fluid extract of Vitex negundo indicate that ethanol extract has stronger reducing potential and ability to scavenge free radicals as compared to the supercritical fluid extract. The in vivo effect of extracts on lipid peroxidation was studied using ethanol induced oxidative stress model in rat. Ingestion of extracts for 14 days exhibited significant reduction in plasma MDA level of stressed animals. Ethanol extract exhibited higher in vivo antilipid peroxidation potential as compared to supercritical fluid extract which correlated well with radical scavenging potential of extract. PMID:22707827

Quasi-geostrophic free mode models of long-lived Jovian eddies: Forcing mechanisms and crucial observational tests

NASA Technical Reports Server (NTRS)

Read, P. L.

1986-01-01

Observations of Jupiter and Saturn long-lived eddies, such as Jupiter's Great Red Spot and White Ovals, are presently compared with laboratory experiments and corresponding numerical simulations for free thermal convection in a rotating fluid that is subject to horizontal differential heating and cooling. Difficulties in determining the essential processes maintaining and dissipating stable eddies, on the basis of global energy budget studies, are discussed; such difficulties do not arise in considerations of the flow's potential vorticity budget. On Jupiter, diabatically forced and transient eddy-driven flows primarily differ in the implied role of transient eddies in transporting potential vorticity across closed geostrophic streamlines in the time mean.

The formation of spikes in the displacement of miscible fluids

NASA Technical Reports Server (NTRS)

Rashidnia, N.; Balasubramaniam, R.; Schroer, R. T.

2004-01-01

We report on experiments in which a more viscous fluid displaces a less viscous one in a vertical cylindrical tube. These experiments were performed using silicone oils in a vertical pipette of small diameter. The more viscous fluid also had a slightly larger density than the less viscous fluid. In the initial configuration, the fluids were at rest, and the interface was nominally flat. A dye was added to the more viscous fluid for ease of observation of the interface between the fluids. The flow was initiated by pumping the more viscous fluid into the less viscous one. The displacement velocity was such that the Reynolds number was smaller than unity and the Peclet number for mass transfer between the fluids was large compared to unity. For upward displacement of the more viscous fluid from an initially stable configuration, an axisymmetric finger was observed under all conditions. However, a needle-shaped spike was seen to propagate from the main finger in many cases, similar to that observed by Petitjeans and Maxworthy for the displacement of a more viscous fluid by a less viscous one.

Evidence for natural molecular hydrogen seepage associated with Carolina bays (surficial, ovoid depressions on the Atlantic Coastal Plain, Province of the USA)

NASA Astrophysics Data System (ADS)

Zgonnik, Viacheslav; Beaumont, Valérie; Deville, Eric; Larin, Nikolay; Pillot, Daniel; Farrell, Kathleen M.

2015-12-01

A study of soil gases was made in North Carolina (USA) in and around morphological depressions called "Carolina bays." This type of depression is observed over the Atlantic coastal plains of the USA, but their origin remains debated. Significant concentrations of molecular hydrogen (H2) were detected, notably around the bays. These measurements suggest that Carolina bays are the surficial expression of fluid flow pathways for hydrogen gas moving from depth to the surface. The potential mechanisms of H2 production and transport and the geological controls on the fluid migration pathways are discussed, with reference to the hypothesis that Carolina bays are the result of local collapses caused by the alteration of rock along the deep pathways of H2 migrating towards the surface. The present H2 seepages are comparable to those in similar structures previously observed in the East European craton.

Rheological assessment of nanofluids at high pressure high temperature

NASA Astrophysics Data System (ADS)

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).

Environmental Stability and Infectivity of Hepatitis C Virus (HCV) in Different Human Body Fluids.

PubMed

Pfaender, Stephanie; Helfritz, Fabian A; Siddharta, Anindya; Todt, Daniel; Behrendt, Patrick; Heyden, Julia; Riebesehl, Nina; Willmann, Wiebke; Steinmann, Joerg; Münch, Jan; Ciesek, Sandra; Steinmann, Eike

2018-01-01

Background: Hepatitis C virus (HCV) is a hepatotropic, blood-borne virus, but in up to one-third of infections of the transmission route remained unidentified. Viral genome copies of HCV have been identified in several body fluids, however, non-parental transmission upon exposure to contaminated body fluids seems to be rare. Several body fluids, e.g., tears and saliva, are renowned for their antimicrobial and antiviral properties, nevertheless, HCV stability has never been systematically analyzed in those fluids. Methods: We used state of the art infectious HCV cell culture techniques to investigate the stability of HCV in different body fluids to estimate the potential risk of transmission via patient body fluid material. In addition, we mimicked a potential contamination of HCV in tear fluid and analyzed which impact commercially available contact lens solutions might have in such a scenario. Results: We could demonstrate that HCV remains infectious over several days in body fluids like tears, saliva, semen, and cerebrospinal fluid. Only hydrogen-peroxide contact lens solutions were able to efficiently inactivate HCV in a suspension test. Conclusion: These results indicate that HCV, once it is present in various body fluids of infected patients, remains infective and could potentially contribute to transmission upon direct contact.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bag, Satadru; Sahni, Varun; Viznyuk, Alexander

We obtain a closed system of equations for scalar perturbations in a multi-component braneworld. Our braneworld possesses a phantom-like equation of state at late times, w {sub eff} < −1, but no big-rip future singularity. In addition to matter and radiation, the braneworld possesses a new effective degree of freedom—the 'Weyl fluid' or 'dark radiation'. Setting initial conditions on super-Hubble spatial scales at the epoch of radiation domination, we evolve perturbations of radiation, pressureless matter and the Weyl fluid until the present epoch. We observe a gradual decrease in the amplitude of the Weyl-fluid perturbations after Hubble-radius crossing, which resultsmore » in a negligible effect of the Weyl fluid on the evolution of matter perturbations on spatial scales relevant for structure formation. Consequently, the quasi-static approximation of Koyama and Maartens provides a good fit to the exact results during the matter-dominated epoch. We find that the late-time growth of density perturbations on the brane proceeds at a faster rate than in ΛCDM. Additionally, the gravitational potentials Φ and Ψ evolve differently on the brane than in ΛCDM, for which Φ = Ψ. On the brane, by contrast, the ratio Φ/Ψ exceeds unity during the late matter-dominated epoch ( z ∼< 50). These features emerge as smoking gun tests of phantom brane cosmology and allow predictions of this scenario to be tested against observations of galaxy clustering and large-scale structure.« less

An integrated fluid-chemical model toward modeling the formation of intra-luminal thrombus in abdominal aortic aneurysms.

PubMed

Biasetti, Jacopo; Spazzini, Pier Giorgio; Swedenborg, Jesper; Gasser, T Christian

2012-01-01

Abdominal Aortic Aneurysms (AAAs) are frequently characterized by the presence of an Intra-Luminal Thrombus (ILT) known to influence their evolution biochemically and biomechanically. The ILT progression mechanism is still unclear and little is known regarding the impact of the chemical species transported by blood flow on this mechanism. Chemical agonists and antagonists of platelets activation, aggregation, and adhesion and the proteins involved in the coagulation cascade (CC) may play an important role in ILT development. Starting from this assumption, the evolution of chemical species involved in the CC, their relation to coherent vortical structures (VSs) and their possible effect on ILT evolution have been studied. To this end a fluid-chemical model that simulates the CC through a series of convection-diffusion-reaction (CDR) equations has been developed. The model involves plasma-phase and surface-bound enzymes and zymogens, and includes both plasma-phase and membrane-phase reactions. Blood is modeled as a non-Newtonian incompressible fluid. VSs convect thrombin in the domain and lead to the high concentration observed in the distal portion of the AAA. This finding is in line with the clinical observations showing that the thickest ILT is usually seen in the distal AAA region. The proposed model, due to its ability to couple the fluid and chemical domains, provides an integrated mechanochemical picture that potentially could help unveil mechanisms of ILT formation and development.

Grain scale observations of stick-slip dynamics in fluid saturated granular fault gouge

NASA Astrophysics Data System (ADS)

Johnson, P. A.; Dorostkar, O.; Guyer, R. A.; Marone, C.; Carmeliet, J.

2017-12-01

We are studying granular mechanics during slip. In the present work, we conduct coupled computational fluid dynamics (CFD) and discrete element method (DEM) simulations to study grain scale characteristics of slip instabilities in fluid saturated granular fault gouge. The granular sample is confined with constant normal load (10 MPa), and sheared with constant velocity (0.6 mm/s). This loading configuration is chosen to promote stick-slip dynamics, based on a phase-space study. Fluid is introduced in the beginning of stick phase and characteristics of slip events i.e. macroscopic friction coefficient, kinetic energy and layer thickness are monitored. At the grain scale, we monitor particle coordination number, fluid-particle interaction forces as well as particle and fluid kinetic energy. Our observations show that presence of fluids in a drained granular fault gouge stabilizes the layer in the stick phase and increases the recurrence time. In saturated model, we observe that average particle coordination number reaches higher values compared to dry granular gouge. Upon slip, we observe that a larger portion of the granular sample is mobilized in saturated gouge compared to dry system. We also observe that regions with high particle kinetic energy are correlated with zones of high fluid motion. Our observations highlight that spatiotemporal profile of fluid dynamic pressure affects the characteristics of slip instabilities, increasing macroscopic friction coefficient drop, kinetic energy release and granular layer compaction. We show that numerical simulations help characterize the micromechanics of fault mechanics.

Multipole Vortex Blobs (MVB): Symplectic Geometry and Dynamics.

PubMed

Holm, Darryl D; Jacobs, Henry O

2017-01-01

Vortex blob methods are typically characterized by a regularization length scale, below which the dynamics are trivial for isolated blobs. In this article, we observe that the dynamics need not be trivial if one is willing to consider distributional derivatives of Dirac delta functionals as valid vorticity distributions. More specifically, a new singular vortex theory is presented for regularized Euler fluid equations of ideal incompressible flow in the plane. We determine the conditions under which such regularized Euler fluid equations may admit vorticity singularities which are stronger than delta functions, e.g., derivatives of delta functions. We also describe the symplectic geometry associated with these augmented vortex structures, and we characterize the dynamics as Hamiltonian. Applications to the design of numerical methods similar to vortex blob methods are also discussed. Such findings illuminate the rich dynamics which occur below the regularization length scale and enlighten our perspective on the potential for regularized fluid models to capture multiscale phenomena.

A unifying hypothesis for a patient with superficial siderosis, low-pressure headache, intraspinal cyst, back pain, and prominent vascularity.

PubMed

Kumar, Neeraj; Miller, Gary M; Piepgras, David G; Mokri, Bahram

2010-07-01

A source of bleeding is often not evident during the evaluation of patients with superficial siderosis of the CNS despite extensive imaging. An intraspinal fluid-filled collection of variable dimensions is frequently observed on spine MR imaging in patients with idiopathic superficial siderosis. A similar finding has also been reported in patients with idiopathic intracranial hypotension. The authors report on a patient with superficial siderosis and a longitudinally extensive intraspinal fluid-filled collection secondary to a dural tear. The patient had a history of low-pressure headaches. His spine MR imaging and spine CT suggested the possibility of an underlying vascular malformation, but none was found on angiography. Repair of the dural tear resulted in resolution of the intraspinal fluid collection and CSF abnormalities. The significance of the association between superficial siderosis and idiopathic intracranial hypotension, and potential therapeutic and pathophysiological implications, are the subject of this report.

Iron isotope fractionation among magnetite, pyrrhotite, chalcopyrite, rhyolite melt and aqueous fluid at magmatic-hydrothermal conditions

NASA Astrophysics Data System (ADS)

Bilenker, L. D.; Simon, A.; Lundstrom, C.; Gajos, N.

2012-12-01

Fractionation of non-traditional stable isotopes (NTSI) such as Fe in magmatic systems is a relatively understudied subject. The fractionation of Fe stable isotopes has been quantified in some natural igneous samples, but there is a paucity of experimental data that could provide further insight into the causative processes of the observed fractionation. Substantial experimental work has been performed at higher temperatures pertaining to the formation of chondrites and the Earth's core, but only a handful of studies have addressed crustal rocks. To fill this knowledge gap, we performed isothermal, isobaric experiments containing mineral (e.g., magnetite, Fe-sulfides) and fluid, or mineral, rhyolite melt, and fluid assemblages to quantify equilibrium fractionation factors (α). These data, to our knowledge, are the first data that quantify the effect of a fluid phase on iron isotope fractionation at conditions appropriate for evolving magmatic systems. Charges were run inside gold capsules held in a René-41 cold seal vessel, and heated to 400, 600, or 800°C at 150 MPa for mineral-fluid, and 800°C and 100 MPa for mineral-melt-fluid runs. Use of the René vessel fixed the fO2 at the NNO buffer, an oxidation state consistent with arc magmas. The isotopic compositions of the starting and quenched phases were obtained by using a Multi-Collector Plasma Mass Spectrometer (MC-ICP-MS). Equilibrium was assessed by performing time-series runs and the three-isotope method, used only once before in a similar Fe isotope study. Correlation between Fe isotope mass and oxidation state is also being explored. Magnetite-fluid results indicate enrichment of heavy Fe isotopes in the mineral relative to the fluid, consistent with measurements of felsic igneous rocks. Magnetite-melt-fluid relationships are also consistent with measurements of natural samples. In the latter assemblage, over the course of the run, the rhyolite melt becomes heavy relative to the fluid while magnetite takes on a heavier Fe isotope signature than the starting value. These data corroborate the hypothesis that fluid exsolution caused the isotopic patterns observed in highly-differentiated igneous rocks. Further, owing to the ubiquitous importance of melt degassing as a critical process for the formation of magmatic-hydrothermal ore deposits, these data may be potentially serve as an exploration tool. This work contributes to our overall understanding of igneous processes by elucidating the Fe isotope fingerprints observed in the field as well as develop the laboratory techniques needed to study NTSI fractionation in magmatic systems and build a reliable dataset for interpretation of natural systems.

Boiling-induced formation of colloidal gold in black smoker hydrothermal fluids

USGS Publications Warehouse

Gartman, Amy; Hannington, Mark; Jamieson, John W.; Peterkin, Ben; Garbe-Schönberg, Dieter; Findlay, Alyssa J; Fuchs, Sebastian; Kwasnitschka, Tom

2017-01-01

Gold colloids occur in black smoker fluids from the Niua South hydrothermal vent field, Lau Basin (South Pacific Ocean), confirming the long-standing hypothesis that gold may undergo colloidal transport in hydrothermal fluids. Six black smoker vents, varying in temperature from 250 °C to 325 °C, were sampled; the 325 °C vent was boiling at the time of sampling and the 250 °C fluids were diffusely venting. Native gold particles ranging from <50 nm to 2 µm were identified in 4 of the fluid samples and were also observed to precipitate on the sampler during collection from the boiling vent. Total gold concentrations (dissolved and particulate) in the fluid samples range from 1.6 to 5.4 nM in the high-temperature, focused flow vents. Although the gold concentrations in the focused flow fluids are relatively high, they are lower than potential solubilities prior to boiling and indicate that precipitation was boiling induced, with sulfide lost upon boiling to exsolution and metal sulfide formation. Gold concentrations reach 26.7 nM in the 250 °C diffuse flow sample, and abundant native gold particles were also found in the fluids and associated sulfide chimney and are interpreted to be a product of colloid accumulation and growth following initial precipitation upon boiling. These results indicate that colloid-driven precipitation as a result of boiling, the persistence of colloids after boiling, and the accumulation of colloids in diffuse flow fluids are important mechanisms for the enrichment of gold in seafloor hydrothermal systems.

Management of fluid mud in estuaries, bays, and lakes. II: Measurement, modeling, and management

USGS Publications Warehouse

McAnally, W.H.; Teeter, A.; Schoellhamer, David H.; Friedrichs, C.; Hamilton, D.; Hayter, E.; Shrestha, P.; Rodriguez, H.; Sheremet, A.; Kirby, R.

2007-01-01

Techniques for measurement, modeling, and management of fluid mud are available, but research is needed to improve them. Fluid mud can be difficult to detect, measure, or sample, which has led to new instruments and new ways of using existing instruments. Multifrequency acoustic fathometers sense neither density nor viscosity and are, therefore, unreliable in measuring fluid mud. Nuclear density probes, towed sleds, seismic, and drop probes equipped with density meters offer the potential for accurate measurements. Numerical modeling of fluid mud requires solving governing equations for flow velocity, density, pressure, salinity, water surface, plus sediment submodels. A number of such models exist in one-, two-, and three-dimensional form, but they rely on empirical relationships that require substantial site-specific validation to observations. Management of fluid mud techniques can be classified as those that accomplish: Source control, formation control, and removal. Nautical depth, a fourth category, defines the channel bottom as a specific fluid mud density or alternative parameter as safe for navigation. Source control includes watershed management measures to keep fine sediment out of waterways and in-water measures such as structures and traps. Formation control methods include streamlined channels and structures plus other measures to reduce flocculation and structures that train currents. Removal methods include the traditional dredging and transport of dredged material plus agitation that contributes to formation control and/or nautical depth. Conditioning of fluid mud by dredging and aerating offers the possibility of improved navigability. Two examples—the Atchafalaya Bar Channel and Savannah Harbor—illustrate the use of measurements and management of fluid mud.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sasaki, Kazuki; Suzuki, Naoya; Saito, Hiroki

Vortex shedding from an obstacle potential moving in a Bose-Einstein condensate is investigated. Long-lived alternately aligned vortex pairs are found to form in the wake, which is similar to the Benard-von Karman vortex street in classical viscous fluids. Various patterns of vortex shedding are systematically studied and the drag force on the obstacle is calculated. It is shown that the phenomenon can be observed in a trapped system.

Stresses in non-equilibrium fluids: Exact formulation and coarse-grained theory.

PubMed

Krüger, Matthias; Solon, Alexandre; Démery, Vincent; Rohwer, Christian M; Dean, David S

2018-02-28

Starting from the stochastic equation for the density operator, we formulate the exact (instantaneous) stress tensor for interacting Brownian particles and show that its average value agrees with expressions derived previously. We analyze the relation between the stress tensor and forces due to external potentials and observe that, out of equilibrium, particle currents give rise to extra forces. Next, we derive the stress tensor for a Landau-Ginzburg theory in generic, non-equilibrium situations, finding an expression analogous to that of the exact microscopic stress tensor, and discuss the computation of out-of-equilibrium (classical) Casimir forces. Subsequently, we give a general form for the stress tensor which is valid for a large variety of energy functionals and which reproduces the two mentioned cases. We then use these relations to study the spatio-temporal correlations of the stress tensor in a Brownian fluid, which we compute to leading order in the interaction potential strength. We observe that, after integration over time, the spatial correlations generally decay as power laws in space. These are expected to be of importance for driven confined systems. We also show that divergence-free parts of the stress tensor do not contribute to the Green-Kubo relation for the viscosity.

Stresses in non-equilibrium fluids: Exact formulation and coarse-grained theory

NASA Astrophysics Data System (ADS)

Krüger, Matthias; Solon, Alexandre; Démery, Vincent; Rohwer, Christian M.; Dean, David S.

2018-02-01

Starting from the stochastic equation for the density operator, we formulate the exact (instantaneous) stress tensor for interacting Brownian particles and show that its average value agrees with expressions derived previously. We analyze the relation between the stress tensor and forces due to external potentials and observe that, out of equilibrium, particle currents give rise to extra forces. Next, we derive the stress tensor for a Landau-Ginzburg theory in generic, non-equilibrium situations, finding an expression analogous to that of the exact microscopic stress tensor, and discuss the computation of out-of-equilibrium (classical) Casimir forces. Subsequently, we give a general form for the stress tensor which is valid for a large variety of energy functionals and which reproduces the two mentioned cases. We then use these relations to study the spatio-temporal correlations of the stress tensor in a Brownian fluid, which we compute to leading order in the interaction potential strength. We observe that, after integration over time, the spatial correlations generally decay as power laws in space. These are expected to be of importance for driven confined systems. We also show that divergence-free parts of the stress tensor do not contribute to the Green-Kubo relation for the viscosity.

Field gradients can control the alignment of nanorods.

PubMed

Ooi, Chinchun; Yellen, Benjamin B

2008-08-19

This work is motivated by the unexpected experimental observation that field gradients can control the alignment of nonmagnetic nanorods immersed inside magnetic fluids. In the presence of local field gradients, nanorods were observed to align perpendicular to the external field at low field strengths, but parallel to the external field at high field strengths. The switching behavior results from the competition between a preference to align with the external field (orientational potential energy) and preference to move into regions of minimum magnetic field (positional potential energy). A theoretical model is developed to explain this experimental behavior by investigating the statistics of nanorod alignment as a function of both the external uniform magnetic field strength and the local magnetic field variation above a periodic array of micromagnets. Computational phase diagrams are developed which indicate that the relative population of nanorods in parallel and perpendicular states can be adjusted through several control parameters. However, an energy barrier to rotation was discovered to influence the rate kinetics and restrict the utility of this assembly technique to nanorods which are slightly shorter than the micromagnet length. Experimental results concerning the orientation of nanorods inside magnetic fluid are also presented and shown to be in strong agreement with the theoretical work.

Orbeez: the magic water absorbing bead--risk of pediatric bowel obstruction?

PubMed

Darracq, Michael A; Cullen, Jennifer; Rentmeester, Landen; Cantrell, F Lee; Ly, Binh T

2015-06-01

In December 2012, the U.S. Consumer Product Safety Commission recalled the water-absorbing toy WaterBalz after reports of small intestine obstruction after ingestion by children. Orbeez, another water-absorbing bead, remains available and is marketed as a children's toy. We sought to determine the extent to which Orbeez enlarge in various liquid media and the potential risk for bowel obstruction. Three Orbeez beads were added to 210 mL of the following liquid media: room temperature tap water, whole milk, simulated gastric fluid, GoLytely (polyethelyelene glycol, 3350 and electrolytes), and vodka (40% ethanol by volume). Diameters before exposure to media were measured using a caliper to the nearest 0.1 mm and again at 1, 2, 4, 6, 12, and 24 hours. Ten beads were then added to the beads already immersed in simulated gastric fluid and water and observed for an additional 72 hours (96 hours total) for clumping or increase in diameter. Clumping was defined as two or more beads remaining persistently adherent to one another despite gentle circular movement (swirling) of the liquid. Growth in each of the media was observed. Growth in simulated gastric fluid was minimal, whereas the beads were observed to be the largest after 24 hours in vodka. Clumping of the beads was not observed to occur. Orbeez beads enlarge to a different extent in different liquid media. It is unlikely that Orbeez beads would expand to sizes or demonstrate clumping that would be concerning for intestinal obstruction.

Liquid Microjunction Surface Sampling Probe Fluid Dynamics: Computational and Experimental Analysis of Coaxial Intercapillary Positioning Effects on Sample Manipulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

ElNaggar, Mariam S; Barbier, Charlotte N; Van Berkel, Gary J

A coaxial geometry liquid microjunction surface sampling probe (LMJ-SSP) enables direct extraction of analytes from surfaces for subsequent analysis by techniques like mass spectrometry. Solution dynamics at the probe-to-sample surface interface in the LMJ-SSP has been suspected to influence sampling efficiency and dispersion but has not been rigorously investigated. The effect on flow dynamics and analyte transport to the mass spectrometer caused by coaxial retraction of the inner and outer capillaries from each other and the surface during sampling with a LMJ-SSP was investigated using computational fluid dynamics and experimentation. A transparent LMJ-SSP was constructed to provide the means formore » visual observation of the dynamics of the surface sampling process. Visual observation, computational fluid dynamics (CFD) analysis, and experimental results revealed that inner capillary axial retraction from the flush position relative to the outer capillary transitioned the probe from a continuous sampling and injection mode through an intermediate regime to sample plug formationmode caused by eddy currents at the sampling end of the probe. The potential for analytical implementation of these newly discovered probe operational modes is discussed.« less

Fluid-structure finite-element vibrational analysis

NASA Technical Reports Server (NTRS)

Feng, G. C.; Kiefling, L.

1974-01-01

A fluid finite element has been developed for a quasi-compressible fluid. Both kinetic and potential energy are expressed as functions of nodal displacements. Thus, the formulation is similar to that used for structural elements, with the only differences being that the fluid can possess gravitational potential, and the constitutive equations for fluid contain no shear coefficients. Using this approach, structural and fluid elements can be used interchangeably in existing efficient sparse-matrix structural computer programs such as SPAR. The theoretical development of the element formulations and the relationships of the local and global coordinates are shown. Solutions of fluid slosh, liquid compressibility, and coupled fluid-shell oscillation problems which were completed using a temporary digital computer program are shown. The frequency correlation of the solutions with classical theory is excellent.

Can sterile and pyrogen-free on-line substitution fluid be routinely delivered? A multicentric study on the microbiological safety of on-line haemodiafiltration.

PubMed

Vaslaki, L; Karátson, A; Vörös, P; Major, L; Pethö, F; Ladányi, E; Weber, C; Mitteregger, R; Falkenhagen, D

2000-01-01

Microbial contamination is characterized not only by the presence of bacteria, but also by high concentrations of biologically active by-products. They are potentially able to cross ultrafiltration and dialysis membranes and stimulate immunocompetent blood cells to synthesize cytokines. In turn, cytokine induction causes acute symptoms and has been incriminated in the long-term complications of haemodialysis patients. Infusion of large volumes of substitution fluids following ultrafiltration of microbially contaminated dialysis fluids may place patients on on-line therapies at particular risk. In this study we evaluated 30 machines with a two-stage ultrafiltration system in routine clinical haemodiafiltration settings in six centres for 6 months. Microbiological safety was assessed monthly and at the last use of the filters by determining microbial counts, endotoxin concentration and cytokine-inducing activity. No pyrogenic episodes were observed during the study period. Double-filtration of standard dialysis fluid (range, <1-895 cfu/ml, 0.0028-4.6822 IU/ml) resulted in sterile substitution fluids with endotoxin concentrations well below the Ph.Eur. standard for haemofiltration solutions (range, 0.0014-0.0281 vs 0.25 IU/ml). Moreover, they did not differ from commercial haemofiltration solutions and depyrogenated saline. Likewise, there was no difference in the cytokine-inducing activity between the solutions tested. The high microbiological quality of the ultrafiltered dialysis fluid, which was in the same range as substitution fluid, translates into both the absence of cytokine induction by dialyser back-transport and a redundant safety mode of the on-line system by a second filtration step. On-line HDF treatment can routinely be provided with ultra-pure dialysis fluids and sterile substitution fluids at pyrogen-free levels. The online preparation of substitution fluids thus can be considered microbiologically safe.

An Index-Mismatch Scattering Approach to Optical Limiting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Exarhos, Gregory J.; Ferris, Kim F.; Windisch, Charles F.

A densely packed bed of alkaline earth fluoride particles percolated by a fluid medium has been investigated as a potential index-matched optical limiter in the spirit of a Christiansen-Shelyubskii filter. Marked optical limiting was observed through this transparent medium under conditions where the focused second-harmonic output of a Q-swtiched Nd: YAG laser was on the order of about 1 J/cm2. An open-aperture Z-scan technique was used to quantify the limiting behavior. In this case, the mechanism of optical limiting is thought to be a nonlinear shift in the fluid index of refraction, resulting in an index mismatch between the disparatemore » phases at high laser fluence.« less

Acceleration of ions and neutrals by a traveling electrostatic wave

NASA Astrophysics Data System (ADS)

Lee, K. H.; Lee, L. C.; Wong, A. Y.

2018-02-01

We propose a new scheme for accelerating a weakly ionized gas by externally imposing a sinusoidal electrostatic (ES) potential in a tubular system. The weakly ionized gas consists of three fluid components: neutral hydrogen fluid ( H ), positively charged fluid ( H + ), and negatively charged fluids ( H - and/or e - ), as an example. The sinusoidal ES potential is imposed on a series of conductive meshes in the tubular system, and its phase varies with time and space to mimic a traveling ES wave. The charged fluids are trapped and accelerated by the sinusoidal ES potential, while the neutral fluid is accelerated through neutral-ion collisions. The neutral fluid can be accelerated to the wave phase velocity in a few neutral-ion collision times. The whole device remains charge-neutral, and there is no build-up of space charge. The acceleration scheme can be applied to, for example, the propulsion of glider in the air, partially ionized plasma in a chamber, spacecraft, and wind tunnel.

Smectite diagenesis, pore-water freshening, and fluid flow at the toe of the Nankai wedge

USGS Publications Warehouse

Brown, K.M.; Saffer, D.M.; Bekins, B.A.

2001-01-01

The presence of low-chloride fluids in the lowermost sediments drilled at Ocean Drilling Program Site 808, at the Nankai accretionary wedge, has been considered as prime evidence for long-distance, lateral fluid flow from depth. Here, we re-evaluate the potential role of in situ reaction of smectite (S) to illite (I) in the genesis of this low chloride anomaly. This reaction is known to be occurring at Site 808, with both the S content and S to I ratio in the mixed layer clays decreasing substantially with depth. We show that the bulk of the chloride anomaly can generate by in situ clay dehydration, particularly if pre-reaction smectite abundances (Ai) approach ?? 10-15% of the bulk sediment. The Ai values, however, are not well constrained. At Ai values < 10-15%, an additional source of low-Cl fluid centered close to the de??collement could be required. Thus, there remains the important possibility that the observed low-Cl anomaly is a compound effect of both lateral flow and in situ smectite dehydration. ?? 2001 Elsevier Science B.V. All rights reserved.

Effects of irregular cerebrospinal fluid production rate in human brain ventricular system

NASA Astrophysics Data System (ADS)

Hadzri, Edi Azali; Shamsudin, Amir Hamzah; Osman, Kahar; Abdul Kadir, Mohammed Rafiq; Aziz, Azian Abd

2012-06-01

Hydrocephalus is an abnormal accumulation of fluid in the ventricles and cavities in the brain. It occurs when the cerebrospinal fluid (CSF) flow or absorption is blocked or when excessive CSF is secreted. The excessive accumulation of CSF results in an abnormal widening of the ventricles. This widening creates potentially harmful pressure on the tissues of the brain. In this study, flow analysis of CSF was conducted on a three-dimensional model of the third ventricle and aqueduct of Sylvius, derived from MRI scans. CSF was modeled as Newtonian Fluid and its flow through the region of interest (ROI) was done using EFD. Lab software. Different steady flow rates through the Foramen of Monro, classified by normal and hydrocephalus cases, were modeled to investigate its effects. The results show that, for normal and hydrocephalus cases, the pressure drop of CSF flow across the third ventricle was observed to be linearly proportionally to the production rate increment. In conclusion, flow rates that cause pressure drop of 5 Pa was found to be the threshold for the initial sign of hydrocephalus.

Lung biodurability and free radical production of cellulose nanomaterials

PubMed Central

Stefaniak, Aleksandr B.; Seehra, Mohindar S.; Fix, Natalie R.; Leonard, Stephen S.

2015-01-01

The potential applications of cellulose nanomaterials in advanced composites and biomedicine makes it imperative to understand their pulmonary exposure to human health. Here, we report the results on the biodurability of three cellulose nanocrystal (CNC), two cellulose nanofibril (CNF) and a benchmark cellulose microcrystal (CMC) when exposed to artificial lung airway lining fluid (SUF, pH 7.3) for up to 7 days and alveolar macrophage phagolysosomal fluid (PSF, pH 4.5) for up to 9 months. X-ray diffraction analysis was used to monitor biodurability and thermogravimetry, surface area, hydrodynamic diameter, zeta potential and free radical generation capacity of the samples were determined (in vitro cell-free and RAW 264.7 cell line models). The CMC showed no measurable changes in crystallinity (xCR) or crystallite size D in either SUF or PSF. For one CNC, a slight decrease in xCR and D in SUF was observed. In acidic PSF, a slight increase in xCR with exposure time was observed, possibly due to dissolution of the amorphous component. In a cell-free reaction with H2O2, radicals were observed; the CNCs and a CNF generated significantly more ●OH radicals than the CMC (p<0.05). The ●OH radical production correlates with particle decomposition temperature and is explained by the higher surface area to volume ratio of the CNCs. Based on their biodurability, mechanical clearance would be the primary mechanism for lung clearance of cellulose materials. The production of ●OH radicals indicates the need for additional studies to characterize the potential inhalation hazards of cellulose. PMID:25265049

Interleukin-2 activation of cytotoxic cells in postmastectomy seroma.

PubMed

Gercel-Taylor, C; Hoffman, J P; Taylor, D D; Owens, K J; Eisenberg, B L

1996-02-15

Lymphocytes were isolated from breast seroma fluids and used to study the mechanism of activation of cytotoxic lymphocytes and possible role of immunological potentiation following surgery in breast cancer patients. Single or serial samples were obtained from patients who had undergone mastectomy or lumpectomy with axillary node dissection. Lymphocytes were activated with rIL-2 (interleukin-2) and their cytotoxic activity was studied against Daudi and K562 cells and against a breast tumor line (SKBr-3). All of the patients (21/21) responded to IL-2 stimulation by significant activation of cytotoxic activity. The unstimulated cytotoxic activity of these cells against NK targets was low with less than 10% specific release in cytotoxicity assays. In simultaneous experiments, autologous seroma fluid was included during activation of lymphocytes to study possible regulatory molecules that may be present. In 17/21 patients, the presence of their seroma fluid, during the activation period, enhanced or did not effect the cytotoxic potential of their lymphocytes; inhibition was observed when seroma fluids from 4/21 patients were included. Analysis of the cytotoxic population derived from combined IL-2 and seroma treatments indicates the presence of cells with increased expression of CD56, and CD2, as well as in some cases CD16 expression. Cytotoxic lymphocytes derived from IL-2 and seroma treatments appeared to be more effective killers. Modulation of CD2 expression with seroma alone appeared to result in the generation of this highly cytotoxic population. This study demonstrates the role of CD2 expression in the effectiveness of LAK cell killing and also potential benefit of an immunotherapeutic approach to the postoperative treatment of carcinoma of the breast.

Penetration and distribution of gadolinium-based contrast agents into the cerebrospinal fluid in healthy rats: a potential pathway of entry into the brain tissue.

PubMed

Jost, Gregor; Frenzel, Thomas; Lohrke, Jessica; Lenhard, Diana Constanze; Naganawa, Shinji; Pietsch, Hubertus

2017-07-01

Signal hyperintensity on unenhanced MRI in certain brain regions has been reported after multiple administrations of some, but not all, gadolinium-based contrast agents (GBCAs). One potential initial pathway of GBCA entry into the brain, infiltration from blood into the cerebrospinal fluid (CSF), was systematically evaluated in this preclinical study. GBCA infiltration and distribution in the CSF were investigated in healthy rats using repeated fluid-attenuated MRI up to 4 h after high-dose (1.8 mmol/kg) administration of six marketed and one experimental GBCA. Additionally, gadolinium measurements in CSF, blood and brain tissue samples (after 24 h) were performed using inductively coupled plasma mass spectrometry. Enhanced MRI signals in the CSF spaces with similar distribution kinetics were observed for all GBCAs. No substantial differences in the gadolinium concentrations among the marketed GBCAs were found in the CSF, blood or brain tissue. After 4.5 h, the concentration in the CSF was clearly higher than in blood but was almost completely cleared and lower than the brain tissue concentration after 24 h. In contrast to the brain signal hyperintensities, no differences in penetration and distribution into the CSF of healthy rats exist among the marketed GBCAs. • Gadolinium-based contrast agents can cross the blood-CSF barrier. • Fluid-attenuated MRI shows GBCA distribution with CSF flow. • GBCA structure and physicochemical properties do not impact CSF penetration and distribution. • GBCA clearance from CSF was almost complete within 24 h in rats. • CSF is a potential pathway of GBCA entry into the brain.

Roadside drug testing: An evaluation of the Alere DDS® 2 mobile test system.

PubMed

Rohrig, Timothy P; Moore, Christine M; Stephens, Kimberly; Cooper, Kelsey; Coulter, Cynthia; Baird, Tyson; Garnier, Margaux; Miller, Samuel; Tuyay, James; Osawa, Kei; Chou, Joshua; Nuss, Carson; Collier, Jeff; Wittman, Karen Cudlin

2018-04-01

The number of drivers using drugs has increased over the last few years, and is likely to continue its upward trend. Testing drivers for alcohol use is routine and standardized, but the same is not true for the identification of driving under the influence of drugs (DUID). The Drug Evaluation and Classification Program (DECP) was developed to train police officers to recognize the signs and symptoms of recent drug use and remains an invaluable program; however, there are insufficient numbers of these highly trained drug recognition experts (DREs) available to attend every potential drug involved traffic incident. While blood and urine samples are used to test for drugs in a driver, both have disadvantages, particularly as they pertain to the length of time required after a traffic stop to sample collection. Therefore, the development of oral fluid testing devices which can be operated at the roadside and have the potential to assist officers in the identification of drug use is a major advancement in DUID cases. This project evaluated the performance of one instrumental oral fluid roadside testing device (Alere DDS®2) compared to DRE opinion, oral fluid laboratory-based analysis, and routine blood testing. The results showed that there was a good correlation with DRE observations and the device performance was >80% in all drug categories compared to laboratory-based analytical testing, both in oral fluid and blood, with few exceptions. The instrument can be considered a useful tool to assist law enforcement in identifying a drugged driver. Because the device does not test for all potentially impairing drugs, the opinion of the police officer regarding the condition of the driver should still be considered the most important aspect for arrest and further action. Copyright © 2017 John Wiley & Sons, Ltd.

The Boundary Layers in Fluids with Little Friction

NASA Technical Reports Server (NTRS)

Blasius, H.

1950-01-01

The vortices forming in flowing water behind solid bodies are not represented correctly by the solution of the potential theory nor by Helmholtz's jets. Potential theory is unable to satisfy the condition that the water adheres at the wetted bodies, and its solutions of the fundamental hydrodynamic equations are at variance with the observation that the flow separates from the body at a certain point and sends forth a highly turbulent boundary layer into the free flow. Helmholtz's theory attempts to imitate the latter effect in such a way that it joins two potential flows, jet and still water, nonanalytical along a stream curve. The admissibility of this method is based on the fact that, at zero pressure, which is to prevail at the cited stream curve, the connection of the fluid, and with it the effect of adjacent parts on each other, is canceled. In reality, however, the pressure at these boundaries is definitely not zero, but can even be varied arbitrarily. Besides, Helmholtz's theory with its potential flows does not satisfy the condition of adherence nor explain the origin of the vortices, for in all of these problems, the friction must be taken into account on principle, according to the vortex theorem.

Streaming Potential Modeling to Understand the Identification of Hydraulically Active Fractures and Fracture-Matrix Fluid Interactions Using the Self-Potential Method

NASA Astrophysics Data System (ADS)

Jougnot, D.; Roubinet, D.; Linde, N.; Irving, J.

2016-12-01

Quantifying fluid flow in fractured media is a critical challenge in a wide variety of research fields and applications. To this end, geophysics offers a variety of tools that can provide important information on subsurface physical properties in a noninvasive manner. Most geophysical techniques infer fluid flow by data or model differencing in time or space (i.e., they are not directly sensitive to flow occurring at the time of the measurements). An exception is the self-potential (SP) method. When water flows in the subsurface, an excess of charge in the pore water that counterbalances electric charges at the mineral-pore water interface gives rise to a streaming current and an associated streaming potential. The latter can be measured with the SP technique, meaning that the method is directly sensitive to fluid flow. Whereas numerous field experiments suggest that the SP method may allow for the detection of hydraulically active fractures, suitable tools for numerically modeling streaming potentials in fractured media do not exist. Here, we present a highly efficient two-dimensional discrete-dual-porosity approach for solving the fluid-flow and associated self-potential problems in fractured domains. Our approach is specifically designed for complex fracture networks that cannot be investigated using standard numerical methods due to computational limitations. We then simulate SP signals associated with pumping conditions for a number of examples to show that (i) accounting for matrix fluid flow is essential for accurate SP modeling and (ii) the sensitivity of SP to hydraulically active fractures is intimately linked with fracture-matrix fluid interactions. This implies that fractures associated with strong SP amplitudes are likely to be hydraulically conductive, attracting fluid flow from the surrounding matrix.

Fluid Extravasation in Shoulder Arthroscopic Surgery: A Systematic Review

PubMed Central

Memon, Muzammil; Kay, Jeffrey; Gholami, Arian; Simunovic, Nicole; Ayeni, Olufemi R.

2018-01-01

Background: Arthroscopic surgery of the shoulder joint has become increasingly more common given its advantages over open surgery; however, one rare but potentially life-threatening complication is fluid extravasation into the surrounding tissues, causing edema, respiratory compromise, abnormal results on laboratory blood tests, and possibly death. Currently, no systematic review exists that summarizes the existing clinical research on this topic. Purpose: To perform a systematic review on fluid extravasation as a complication of shoulder arthroscopic surgery, specifically assessing clinical presentation, risk factors, management, and outcomes. Study Design: Systematic review; Level of evidence, 4. Methods: Two reviewers independently searched 3 databases (PubMed, Ovid [MEDLINE], and Embase) from database inception until July 1, 2017. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) checklist guided the reporting and data abstraction. The methodological quality of these studies was assessed using the Methodological Index for Non-Randomized Studies (MINORS) checklist. The results are presented in a narrative summary fashion using descriptive statistics including ranges and agreement statistics. Results: A total of 26 studies (20 case reports, 4 case series, and 2 prospective comparative studies) encompassing 205 patients (mean age, 50.8 years [range, 15-83 years]) were included. The most common signs of fluid extravasation included chest wall swelling (n = 86) and neck swelling (n = 116). In 32 patients, observation alone was sufficient. Other patients required airway intubation (n = 16), diuretics (n = 7), steroids (n = 1), and percutaneous drainage of fluid (n = 1). Clinical edema resolved after 2 to 48 hours, and patients were discharged 1 to 20 days postoperatively. Serious complications included transfer to the intensive care unit (n = 14), anterior interosseous nerve palsy (n = 4), rhabdomyolysis (n = 1), and death (n = 1). Conclusion: Fluid extravasation has the potential to be a life-threatening complication of shoulder arthroscopic surgery; however, it is most commonly managed nonoperatively, and symptoms typically resolve with no evidence of long-term complications. Intraoperative surgical decisions, such as minimizing the surgical time and volume of irrigation fluid used, may limit fluid extravasation, while careful intraoperative monitoring may facilitate prompt diagnosis and management to optimize patient outcomes. PMID:29785406

Fluid Extravasation in Shoulder Arthroscopic Surgery: A Systematic Review.

PubMed

Memon, Muzammil; Kay, Jeffrey; Gholami, Arian; Simunovic, Nicole; Ayeni, Olufemi R

2018-05-01

Arthroscopic surgery of the shoulder joint has become increasingly more common given its advantages over open surgery; however, one rare but potentially life-threatening complication is fluid extravasation into the surrounding tissues, causing edema, respiratory compromise, abnormal results on laboratory blood tests, and possibly death. Currently, no systematic review exists that summarizes the existing clinical research on this topic. To perform a systematic review on fluid extravasation as a complication of shoulder arthroscopic surgery, specifically assessing clinical presentation, risk factors, management, and outcomes. Systematic review; Level of evidence, 4. Two reviewers independently searched 3 databases (PubMed, Ovid [MEDLINE], and Embase) from database inception until July 1, 2017. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) checklist guided the reporting and data abstraction. The methodological quality of these studies was assessed using the Methodological Index for Non-Randomized Studies (MINORS) checklist. The results are presented in a narrative summary fashion using descriptive statistics including ranges and agreement statistics. A total of 26 studies (20 case reports, 4 case series, and 2 prospective comparative studies) encompassing 205 patients (mean age, 50.8 years [range, 15-83 years]) were included. The most common signs of fluid extravasation included chest wall swelling (n = 86) and neck swelling (n = 116). In 32 patients, observation alone was sufficient. Other patients required airway intubation (n = 16), diuretics (n = 7), steroids (n = 1), and percutaneous drainage of fluid (n = 1). Clinical edema resolved after 2 to 48 hours, and patients were discharged 1 to 20 days postoperatively. Serious complications included transfer to the intensive care unit (n = 14), anterior interosseous nerve palsy (n = 4), rhabdomyolysis (n = 1), and death (n = 1). Fluid extravasation has the potential to be a life-threatening complication of shoulder arthroscopic surgery; however, it is most commonly managed nonoperatively, and symptoms typically resolve with no evidence of long-term complications. Intraoperative surgical decisions, such as minimizing the surgical time and volume of irrigation fluid used, may limit fluid extravasation, while careful intraoperative monitoring may facilitate prompt diagnosis and management to optimize patient outcomes.

Proteomics detection of S100A6 in tumor tissue interstitial fluid and evaluation of its potential as a biomarker of cholangiocarcinoma.

PubMed

Onsurathum, Sudarat; Haonon, Ornuma; Pinlaor, Porntip; Pairojkul, Chawalit; Khuntikeo, Narong; Thanan, Raynoo; Roytrakul, Sittiruk; Pinlaor, Somchai

2018-04-01

Tumor interstitial fluid contains tumor-specific proteins that may be useful biomarkers for cancers. In this study, we identified proteins present in cholangiocarcinoma interstitial fluid. Proteins derived from three samples of tumor interstitial fluid and paired samples of adjacent normal interstitial fluid from cholangiocarcinoma patients were subjected to two-dimensional liquid chromatography with tandem mass spectrometry. Candidate proteins were selected based on a greater than twofold change in expression levels between tumor interstitial fluid and normal interstitial fluid. Upregulation of six proteins in tumor interstitial fluid, including S100 calcium binding protein A6 (S100A6), S100 calcium binding protein A9, aldo-keto reductase family 1 member C4, neuropilin-1, 14-3-3 zeta/delta, and triosephosphate isomerase was assessed by western blot and immunohistochemistry. Their potential as markers was evaluated in human cholangiocarcinoma tissue arrays, and in serum using enzyme-linked immunosorbent assay. Expression of S100A6 was higher in tumor interstitial fluid than in normal interstitial fluid and showed the highest positive rate (98.96%) in cholangiocarcinoma tissues. Serum levels of S100A6 did not differ between cholangitis and cholangiocarcinoma patients, but were significantly higher than in healthy individuals ( p < 0.0001). In cholangiocarcinoma cases, S100A6 level was associated with vascular invasion ( p = 0.007) and could distinguish cholangiocarcinoma patients from healthy individuals as effectively as the carbohydrate antigen 19-9. In addition, potential for drug treatment targeting S100A6 and other candidate proteins was also demonstrated using STITCH analysis. In conclusion, proteomics analysis of tumor interstitial fluid could be a new approach for biomarker discovery, and S100A6 is a potential risk marker for screening of cholangiocarcinoma.

Raman spectroscopic signature of vaginal fluid and its potential application in forensic body fluid identification.

PubMed

Sikirzhytskaya, Aliaksandra; Sikirzhytski, Vitali; Lednev, Igor K

2012-03-10

Traces of human body fluids, such as blood, saliva, sweat, semen and vaginal fluid, play an increasingly important role in forensic investigations. However, a nondestructive, easy and rapid identification of body fluid traces at the scene of a crime has not yet been developed. The obstacles have recently been addressed in our studies, which demonstrated the considerable potential of Raman spectroscopy. In this study, we continued to build a full library of body fluid spectroscopic signatures. The problems concerning vaginal fluid stain identification were addressed using Raman spectroscopy coupled with advanced statistical analysis. Calculated characteristic Raman and fluorescent spectral components were used to build a multidimensional spectroscopic signature of vaginal fluid, which demonstrated good specificity and was able to handle heterogeneous samples from different donors. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

In-situ Cl/Br measurements in scapolite and fluid inclusions by LA-ICP-MS: A powerful tool to constrain fluid sources

NASA Astrophysics Data System (ADS)

Hammerli, J.; Rusk, B.; Spandler, C.; Oliver, N. H. S.; Emsbo, P.

2012-04-01

Chlorine and bromine are highly conservative elements, and are therefore widely used to trace the origin of fluids in sedimentary and hydrothermal/magmatic systems (e.g. Hanor & McIntosh, 2007; Nahnybida et al., 2009). Halogens are important ligands for metal transport in hydrothermal solutions and thus their behavior in hydrothermal environments is crucial for comprehending ore-forming processes. Besides fluid inclusions, scapolite-group minerals hold great potential as a tracer of igneous, metamorphic, and hydrothermal processes, as no Cl/Br fractionation in scapolite has been observed and therefore halogen ratios in scapolite are thought to mirror the halogen ratios in coexisting melts and fluids (Pan & Dong, 2003). Hence, Cl/Br ratios in fluid inclusions and minerals can be utilized to trace the origin of fluids and fluid-rock interaction pathways. Due to their high ionization energies, bromine and chlorine are not routinely measured by LA-ICP-MS and suitable standards are rare. Little is known about the potential interferences and analytical limitations of in-situ chlorine and bromine analysis by LA-ICP-MS. Nevertheless, Seo et al. (2011) showed that quantification of Br and Cl in single synthetic and natural fluid inclusions is possible. In this study, we have analyzed several scapolite grains of known bromine and chlorine concentrations by LA-ICP-MS and assess the capabilities and limitations of this method. The results show that Cl/Br ratios measured by LA-ICP-MS closely reproduce known values determined by microprobe (Cl), the Noble Gas Method (Br) and INAA (Br) (Kendrick, 2011; Lieftink et al., 1993) using laser ablation spot sizes from 24-120 μm. The well-characterized scapolite grains cover bromine concentrations from 50-883 ppm and chlorine concentrations from 3 to 4 wt.%. In order to further assess the method, we analyzed Cl/Br ratios in natural fluid inclusions hosted in sphalerite that were previously characterized by crush and leach ion chromatography. This is the first time that bulk crush and leach Cl/Br analyses can be compared with Cl/Br ratios within individual fluid inclusions. Our LA-ICP-MS measurements are in good agreement with bulk crush and leach analyses. For instance, molar Cl/Br ratios of single fluid inclusions (183±33) in sphalerite form East Tennessee match those obtained by crush and leach (206±8) Additionally, scapolite in samples from dykes of the Burstall granite, associated banded skarns and metasediments from the Mary Kathleen Fold Belt, Queensland, Australia are being studied. Scapolite is highly luminescent and therefore, cathodoluminescence images resolve chemical zoning in scapolite group minerals that, in combination with in-situ Cl/Br analyses, is a powerful tool to better understand fluid sources and fluid-rock interaction within various geological environments.

Coherent thermodynamic model for solid, liquid and gas phases of elements and simple compounds in wide ranges of pressure and temperature

NASA Astrophysics Data System (ADS)

Holzapfel, Wilfried B.

2018-06-01

Thermodynamic modeling of fluids (liquids and gases) uses mostly series expansions which diverge at low temperatures and do not fit to the behavior of metastable quenched fluids (amorphous, glass like solids). These divergences are removed in the present approach by the use of reasonable forms for the "cold" potential energy and for the thermal pressure of the fluid system. Both terms are related to the potential energy and to the thermal pressure of the crystalline phase in a coherent way, which leads to simpler and non diverging series expansions for the thermal pressure and thermal energy of the fluid system. Data for solid and fluid argon are used to illustrate the potential of the present approach.

Origins of Central Pits and Domes on Ceres: Dawn Mapping Constraints and Ganymede Comparisons

NASA Astrophysics Data System (ADS)

Schenk, P.; Hiesinger, H.; Platz, T.; Bowling, T.; Schmidt, B.; Sizemore, H.

2017-09-01

The bright faculae (spots) on Ceres are the most provocative features on this small planetary body and in Occator crater are associated with a prominent fractured dome and pit complex. This feature is analogous to those observed on large icy moon Ganymede and is potentially related to hydrothermal venting of carbonate-rich fluids followed by doming of the pit floor.

Optimizing the restoration and maintenance of fluid balance after exercise-induced dehydration.

PubMed

Evans, Gethin H; James, Lewis J; Shirreffs, Susan M; Maughan, Ronald J

2017-04-01

Hypohydration, or a body water deficit, is a common occurrence in athletes and recreational exercisers following the completion of an exercise session. For those who will undertake a further exercise session that day, it is important to replace water losses to avoid beginning the next exercise session hypohydrated and the potential detrimental effects on performance that this may lead to. The aim of this review is to provide an overview of the research related to factors that may affect postexercise rehydration. Research in this area has focused on the volume of fluid to be ingested, the rate of fluid ingestion, and fluid composition. Volume replacement during recovery should exceed that lost during exercise to allow for ongoing water loss; however, ingestion of large volumes of plain water results in a prompt diuresis, effectively preventing longer-term maintenance of water balance. Addition of sodium to a rehydration solution is beneficial for maintenance of fluid balance due to its effect on extracellular fluid osmolality and volume. The addition of macronutrients such as carbohydrate and protein can promote maintenance of hydration by influencing absorption and distribution of ingested water, which in turn effects extracellular fluid osmolality and volume. Alcohol is commonly consumed in the postexercise period and may influence postexercise rehydration, as will the coingestion of food. Future research in this area should focus on providing information related to optimal rates of fluid ingestion, advisable solutions to ingest during different duration recovery periods, and confirmation of mechanistic explanations for the observations outlined. Copyright © 2017 the American Physiological Society.

Extreme Events on a Low-Gradient River and Delta: Evidence for Sediment Mass Movements on the Subaqueous Delta and a Mechanism for Creating Hyperpycnal Flow onto the Shelf

NASA Astrophysics Data System (ADS)

Dellapenna, T. M.; Carlin, J. A.; Williams, J. R.

2016-02-01

The Brazos River empties into the Gulf of Mexico (GOM) forming a wave-influenced, muddy, subaqueous delta (SAD). Recent research in the estuarine reach of the river and on the SAD, however, found evidence for significant mass wasting of the delta-front and potential evidence of hyperpycnal flow, a processes typically associated with higher gradient and higher sediment yield rivers. The study used high-resolution geophysics on the SAD and water-column profiling in the lower river to investigate the transfer to and fate of fluvial sediment on the shelf. The SAD side scan mosaic combined with core data reveal that the eastern portion was dominated by exposed relict, consolidated sediment; an erosional scarp along the upper shoreface; and a thinning of the Holocene strata immediately downslope of the scarp. Holocene strata thickness increases into deeper water. These features suggest sediment mass wasting on the delta front. After rapidly prograding during the early and mid 20th century, reductions in sediment load due anthropogenic influences, and a shift in the primary depocenter lead to erosion on these abandoned portions of the delta. During an elevated fluvial discharge event, a >1 m thick fluid mud layer was found along a 6 km span of the river 2 km upstream from the mouth. The river's salt wedge was shown to inhibit sediment export from the river to the GOM, and facilitate deposition of mud in the lower river. We believe that the mud layer in the lower river builds during moderate and low discharge periods and remobilized during increased discharge, potentially resulting in hyperpyncnal flow to the shelf. We observed suspended sediment concentrations up to 100 g/l in the fluid mud layer during this event. While our observations did not capture the transition from fluid mud to hyperpycnal flow, we believe that with persistent increased discharge the fluid mud layer could transition to hyperpycnal flow.

Elevated microRNA miR-21 Levels in Pancreatic Cyst Fluid Are Predictive of Mucinous Precursor Lesions of Ductal Adenocarcinoma

PubMed Central

Ryu, Ji Kon; Matthaei, Hanno; dal Molin, Marco; Hong, Seung-Mo; Canto, Marcia I.; Schulick, Richard D.; Wolfgang, Christopher; Goggins, Michael G.; Hruban, Ralph H.; Cope, Leslie; Maitra, Anirban

2011-01-01

Background Biomarkers for the diagnostic classification of pancreatic cysts are urgently needed. Deregulated microRNA (miRNAs) expression is widespread in pancreatic cancer. We assessed whether aberrant miRNAs in pancreatic cyst fluid could be used as potential biomarkers for cystic precursor lesions of pancreatic cancer. Methods Cyst fluid specimens were prospectively collected from 40 surgically resected pancreatic cysts, and small RNAs were extracted. The ‘mucinous’ cohort included 14 intraductal papillary mucinous neoplasms (including 3 with an associated adenocarcinoma) and 10 mucinous cystic neoplasms; the ‘nonmucinous’ cohort included 11 serous cystadenomas and 5 other benign cysts. Quantitative reverse transcription PCR was performed for five miRNAs (miR-21, miR-155, miR-221, miR-17-3p, miR-191), which were previously reported as overexpressed in pancreatic adenocarcinomas. Results Significantly higher expression of miR-21, miR-221, and miR-17-3p was observed in the mucinous versus nonmucinous cysts (p < 0.01), with the mean relative fold differences being 7.0-, 7.9-, and 5.4-fold, respectively. Receiver operating characteristic curves demonstrated the highest median area under the curve for miR-21, with a median specificity of 76%, at a sensitivity of 80%. Conclusion This pilot study demonstrates that profiling miRNAs in pancreatic cyst fluid samples is feasible and can yield potential biomarkers for the classification of cystic lesions of the pancreas. PMID:21757972

Acute exposure to space flight results in evidence of reduced lymph Transport, tissue fluid Shifts, and immune alterations in the rat gastrointestinal system

NASA Astrophysics Data System (ADS)

Cromer, W. E.; Zawieja, D. C.

2018-05-01

Space flight causes a number of alterations in physiological systems, changes in the immunological status of subjects, and altered interactions of the host to environmental stimuli. We studied the effect of space flight on the lymphatic system of the gastrointestinal tract which is responsible for lipid transport and immune surveillance which includes the host interaction with the gut microbiome. We found that there were signs of tissue damage present in the space flown animals that was lacking in ground controls (epithelial damage, crypt morphological changes, etc.). Additionally, morphology of the lymphatic vessels in the tissue suggested a collapsed state at time of harvest and there was a profound change in the retention of lipid in the villi of the ileum. Contrary to our assumptions there was a reduction in tissue fluid volume likely associated with other fluid shifts described. The reduction of tissue fluid volume in the colon and ileum is a likely contributing factor to the state of the lymphatic vessels and lipid transport issues observed. There were also associated changes in the number of MHC-II+ immune cells in the colon tissue, which along with reduced lymphatic competence would favor immune dysfunction in the tissue. These findings help expand our understanding of the effects of space flight on various organ systems. It also points out potential issues that have not been closely examined and have to potential for the need of countermeasure development.

Response of the ECG to short-term diuresis in patients with heart failure.

PubMed

Madias, John E; Song, Jessica; White, C Michael; Kalus, James S; Kluger, Jeffrey

2005-07-01

Increase in the amplitude of electrocardiogram (ECG) QRS complexes has been observed in patients treated for heart failure (HF), but the underlying mechanism has not been delineated. Also, correlation of augmentation of the QRS potentials with loss of weight has been noted in patients recovering from anasarca of varying etiology, or after hemodialysis. We assessed the effect of diuresis-based fluid loss in patients treated for HF on the amplitude of ECG QRS complexes. This is a cohort study based on ECG and other data from a previously published investigation of patients with HF conducted at a university affiliated hospital, which used new measurements and analysis, performed by a totally blinded investigator based at another institution. Twenty-one patients (10 men) aged 70.5+/-12.7 years, 13 with ischemic, and 8 with nonischemic cardiomyopathy, were admitted to the hospital for management of exacerbated HF and were observed for 48 hours. The patients received diuresis, and had routine laboratory testing, documentation of the net fluid lost, and recording of ECGs prior to the initiation of therapy and at 24 and 48 hours. Percent change (%Delta) over the course of observation in the sums of the amplitude of QRS complexes from 12 leads (SigmaQRS12), 6-limb leads (SigmaQRS6), and leads 1+2 (SigmaQRS2) in mm of standard ECGs were correlated with net fluid loss corrected for admission weight in mL/kg. Fluid loss amounted to 3204.9+/-1399.5 mL in the course of 40+/-23 hours of diuresis. SigmaQRS12 was 160.9+/-42.3 mm before and 170.0+/-50.7 mm after diuresis (P=0. 024). Percent change in SigmaQRS12, SigmaQRS6, and SigmaQRS2 correlated well with the net fluid loss (r=-0.70, -0.82, -0.61, and P=0.002, 0.0005, 0.001) correspondingly. Changes in sums of the amplitude of QRS complexes of the standard ECG correlates well with net fluid loss in response to short-term diuresis in patients with HF. Change in the SigmaQRS12, SigmaQRS6, and SigmaQRS2 from ECGs before and after diuresis can be used as an easily obtainable and universally available bedside index of the net fluid loss experienced by bedridden patients with HF undergoing therapy.

A biophysical observation model for field potentials of networks of leaky integrate-and-fire neurons.

PubMed

Beim Graben, Peter; Rodrigues, Serafim

2012-01-01

We present a biophysical approach for the coupling of neural network activity as resulting from proper dipole currents of cortical pyramidal neurons to the electric field in extracellular fluid. Starting from a reduced three-compartment model of a single pyramidal neuron, we derive an observation model for dendritic dipole currents in extracellular space and thereby for the dendritic field potential (DFP) that contributes to the local field potential (LFP) of a neural population. This work aligns and satisfies the widespread dipole assumption that is motivated by the "open-field" configuration of the DFP around cortical pyramidal cells. Our reduced three-compartment scheme allows to derive networks of leaky integrate-and-fire (LIF) models, which facilitates comparison with existing neural network and observation models. In particular, by means of numerical simulations we compare our approach with an ad hoc model by Mazzoni et al. (2008), and conclude that our biophysically motivated approach yields substantial improvement.

A biophysical observation model for field potentials of networks of leaky integrate-and-fire neurons

PubMed Central

beim Graben, Peter; Rodrigues, Serafim

2013-01-01

We present a biophysical approach for the coupling of neural network activity as resulting from proper dipole currents of cortical pyramidal neurons to the electric field in extracellular fluid. Starting from a reduced three-compartment model of a single pyramidal neuron, we derive an observation model for dendritic dipole currents in extracellular space and thereby for the dendritic field potential (DFP) that contributes to the local field potential (LFP) of a neural population. This work aligns and satisfies the widespread dipole assumption that is motivated by the “open-field” configuration of the DFP around cortical pyramidal cells. Our reduced three-compartment scheme allows to derive networks of leaky integrate-and-fire (LIF) models, which facilitates comparison with existing neural network and observation models. In particular, by means of numerical simulations we compare our approach with an ad hoc model by Mazzoni et al. (2008), and conclude that our biophysically motivated approach yields substantial improvement. PMID:23316157

Structure and Dynamics of Fluid Planets

NASA Astrophysics Data System (ADS)

Houben, H.

2014-12-01

Attention to conservation laws gives a comprehensive picture of the structure and dynamics of gas giants: Atmospheric differential rotation is generated by tidal torques (dependent on tropospheric static stability) and is dragged into the interior by turbulent viscosity. The consequent heat dissipation generates baroclinicity and approximate thermal wind balance, not Taylor-Proudman conditions. Magnetic Lorentz forces have no effect on the zonal wind, but generate a meridional wind approximately parallel to field lines. Thus, magnetic field generation in the interior is dominated by the ω-effect (zonal field wound up by differential rotation), with the α-effect (meridional field generated by turbulence) severely limited by the β-effect (turbulence-enhanced resistivity). The meridional circulation quenches the ω-effect so that a steady state is reached and also limits the magnitude of the non-axisymmetric field under certain circumstances. The stability of the steady state requires further study. The magnetic field travels with the E X B drift, rather than the fluid velocity. Work by the fluid on the magnetic field balances work by the magnetic field on the fluid, so the global heat flux is little changed. In conducting regions the meridional density distribution (and gravity field) is most sensitive to the total pressure (gas + magnetic) and the ω-effect. In nonconducting regions, the gas pressure, centrifugal force, and differential rotation dominate. The differential rotation varies at least as fast as r³, so the gravitational signal is small compared to that for differential rotation on cylinders. The entropy minimum near the tropopause allows meteorology to be dominated by (relatively) long-lived, closed potential temperature surfaces, usually called spots, which conserve potential vorticity. All of the above must be taken into account to properly assimilate any available observational data to further specify the interior properties of fluid planets.

Lee waves, benign and malignant

NASA Technical Reports Server (NTRS)

Wurtele, M. G.; Datta, A.

1992-01-01

The flow of an incompressible, stratified fluid over an obstacle will produce an oscillation in which buoyancy is the restoring force, called a gravity wave. For disturbances of this scale, the atmosphere may be treated as incompressible; and even the linear approximation will explain many of the phenomena observed in the lee of mountains. However, nonlinearities arise in two ways: (1) through the large (scaled) size of the mountain, and (2) from dynamically singular levels in the fluid field. These produce a complicated array of phenomena that present hazards to aircraft and to lee surface areas. If there is no dynamic barrier, these waves can penetrate vertically into the middle atmosphere (30-100 km attitude), where recent observations show them to be of a length scale that must involve the Coriolis force in any modeling. At these altitudes, the amplitude of the waves is very large, and the waves are studied with a view to their potential impact on the projected National Aerospace Plane. This paper presents the results of analyses and state-of-the-art numerical simulations, validated where possible by observational data.

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

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

Occurrence and growth characteristics of Escherichia coli and enterococci within the accumulated fluid of the northern pitcher plant (Sarracenia purpurea L.).

PubMed

Whitman, Richard L; Byers, Stacey E; Shively, Dawn A; Ferguson, Donna M; Byappanahalli, Muruleedhara

2005-12-01

Sarracenia purpurea L., a carnivorous bog plant (also known as the pitcher plant), represents an excellent model of a well-defined, self-contained ecosystem; the individual pitchers of the plant serve as a microhabitat for a variety of micro- and macro-organisms. Previously, fecal indicator bacteria (Escherichia coli and enterococci) were shown as incidental contaminants in pitcher fluid; however, whether their occurrence in pitcher fluid is incidental or common has not been established. The purpose of this study was to investigate the occurrence, distribution, and growth potential of E. coli and enterococci in pitcher plant fluid from a protected bog in northwest Indiana. Escherichia coli and enterococci were recovered in pitcher fluids (n=43 plants), with mean densities (log CFU mL-1) of 1.28+/-0.23 and 1.97+/-0.27, respectively. In vitro experiments showed that E. coli growth in fluid not containing insects or indigenous organisms was directly proportional to the fluid concentration (growth was 10-fold in 24 h in 100% fluid); however, in the presence of other indigenous organisms, E. coli and enterococci were only sustained for 5 days at 26 degrees C. Pulsed-field gel electrophoresis (PFGE) analysis showed that the plant Enterococcus faecalis isolates were genetically distinct from the human isolates; identical PFGE patterns were observed among plant isolates that fell into one of six clonal groups. These findings suggest that (i) E. coli and enterococci occurrence in pitcher plants is rather common in the bog studied, although their originating source is unclear, and (ii) the pitcher fluid contains adequate nutrients, especially carbon and energy sources, to promote the growth of indicator bacteria; however, under natural conditions, the biotic factors (e.g., competition for nutrients) may restrict their growth.

Occurrence and growth characteristics of Escherichia coli and enterococci within the accumulated fluid of the northern pitcher plant (Sarracenia purpurea L.)

USGS Publications Warehouse

Whitman, Richard L.; Byers, Stacey E.; Shively, Dawn A.; Ferguson, Donna M.; Byappanahalli, Muruleedhara N.

2005-01-01

Sarracenia purpurea L., a carnivorous bog plant (also known as the pitcher plant), represents an excellent model of a well-defined, self-contained ecosystem; the individual pitchers of the plant serve as a microhabitat for a variety of micro- and macro-organisms. Previously, fecal indicator bacteria (Escherichia coli and enterococci) were shown as incidental contaminants in pitcher fluid; however, whether their occurrence in pitcher fluid is incidental or common has not been established. The purpose of this study was to investigate the occurrence, distribution, and growth potential of E. coli and enterococci in pitcher plant fluid from a protected bog in northwest Indiana. Escherichia coli and enterococci were recovered in pitcher fluids (n = 43 plants), with mean densities (log CFU mL-1) of 1.28 ± 0.23 and 1.97 ± 0.27, respectively. In vitro experiments showed that E. coli growth in fluid not containing insects or indigenous organisms was directly proportional to the fluid concentration (growth was 10-fold in 24 h in 100% fluid); however, in the presence of other indigenous organisms, E. coli and enterococci were only sustained for 5 days at 26 °C. Pulsed-field gel electrophoresis (PFGE) analysis showed that the plant Enterococcus faecalis isolates were genetically distinct from the human isolates; identical PFGE patterns were observed among plant isolates that fell into one of six clonal groups. These findings suggest that (i) E. coli and enterococci occurrence in pitcher plants is rather common in the bog studied, although their originating source is unclear, and (ii) the pitcher fluid contains adequate nutrients, especially carbon and energy sources, to promote the growth of indicator bacteria; however, under natural conditions, the biotic factors (e.g., competition for nutrients) may restrict their growth.

Fluid Extravasation in Hip Arthroscopy: A Systematic Review.

PubMed

Ekhtiari, Seper; Haldane, Chloe E; de Sa, Darren; Simunovic, Nicole; Ayeni, Olufemi R

2017-04-01

The purpose of this systematic review was to (1) characterize cases of fluid extravasation during hip arthroscopy and explore common factors among them and (2) describe management strategies and outcomes of this complication. The databases MEDLINE, EMBASE, and PubMed were searched and screened in duplicate. Data regarding patient demographics, fluid management, presentation, management, and outcomes were collected. Study quality was assessed in duplicate using the Methodological Index for Non-Randomized Studies Criteria. Fourteen studies (1,286 patients) were included. Twenty-two occurrences of symptomatic fluid extravasation were reported in 21 patients (1.6% of total patients; one patient had fluid extravasation during 2 separate hip arthroscopies). Two studies of normal fluid extravasation in asymptomatic patients reported 1.13 to 3.06 L of extravasated fluid observed on computed tomography. Nine case studies were included, which provided detailed patient and surgical information. Of these 9 patients (10 cases) with a mean age of 38.2 years old (range, 15 to 55 years), 6 were female. Signs of fluid extravasation included abdominal distension (89%), hypothermia (56%), hypotension. and metabolic acidosis (33% each). Four patients required surgical intervention, while 3 underwent paracentesis. Two patients were managed conservatively. All patients stabilized and were discharged, with one patient reporting abdominal complaints at latest follow-up (length of follow-up unspecified). Fluid extravasation is a rare but potentially life-threatening complication of hip arthroscopy. It is important for surgeons and anaesthesiologists to be aware of its existence in order to recognize and manage it promptly. Most patients require interventional management by surgery or paracentesis, but some stabilize with conservative management. Level IV, systematic review of Level IV studies. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Creep cavitation can establish a dynamic granular fluid pump in ductile shear zones.

PubMed

Fusseis, F; Regenauer-Lieb, K; Liu, J; Hough, R M; De Carlo, F

2009-06-18

The feedback between fluid migration and rock deformation in mid-crustal shear zones is acknowledged as being critical for earthquake nucleation, the initiation of subduction zones and the formation of mineral deposits. The importance of this poorly understood feedback is further highlighted by evidence for shear-zone-controlled advective flow of fluids in the ductile lower crust and the recognition that deformation-induced grain-scale porosity is a key to large-scale geodynamics. Fluid migration in the middle crust cannot be explained in terms of classical concepts. The environment is considered too hot for a dynamic fracture-sustained permeability as in the upper crust, and fluid pathways are generally too deformed to be controlled by equilibrium wetting angles that apply to hotter, deeper environments. Here we present evidence that mechanical and chemical potentials control a syndeformational porosity generation in mid-crustal shear zones. High-resolution synchrotron X-ray tomography and scanning electron microscopy observations allow us to formulate a model for fluid migration in shear zones where a permeable porosity is dynamically created by viscous grain-boundary sliding, creep cavitation, dissolution and precipitation. We propose that syndeformational fluid migration in our 'granular fluid pump' model is a self-sustained process controlled by the explicit role of the rate of entropy production of the underlying irreversible mechanical and chemical microprocesses. The model explains fluid transfer through the middle crust, where strain localization in the creep regime is required for plate tectonics, the formation of giant ore deposits, mantle degassing and earthquake nucleation. Our findings provide a key component for the understanding of creep instabilities in the middle crust.

Electroosmotic flow of Phan-Thien-Tanner fluids at high zeta potentials: An exact analytical solution

NASA Astrophysics Data System (ADS)

Sarma, Rajkumar; Deka, Nabajit; Sarma, Kuldeep; Mondal, Pranab Kumar

2018-06-01

We present a mathematical model to study the electroosmotic flow of a viscoelastic fluid in a parallel plate microchannel with a high zeta potential, taking hydrodynamic slippage at the walls into account in the underlying analysis. We use the simplified Phan-Thien-Tanner (s-PTT) constitutive relationships to describe the rheological behavior of the viscoelastic fluid, while Navier's slip law is employed to model the interfacial hydrodynamic slip. Here, we derive analytical solutions for the potential distribution, flow velocity, and volumetric flow rate based on the complete Poisson-Boltzmann equation (without considering the frequently used Debye-Hückel linear approximation). For the underlying electrokinetic transport, this investigation primarily reveals the influence of fluid rheology, wall zeta potential as modulated by the interfacial electrochemistry and interfacial slip on the velocity distribution, volumetric flow rate, and fluid stress, as well as the apparent viscosity. We show that combined with the viscoelasticity of the fluid, a higher wall zeta potential and slip coefficient lead to a phenomenal enhancement in the volumetric flow rate. We believe that this analysis, besides providing a deep theoretical insight to interpret the transport process, will also serve as a fundamental design tool for microfluidic devices/systems under electrokinetic influence.

Survival of Organic Materials in Ancient Cryovolcanically-Produced Halite Crystals

NASA Technical Reports Server (NTRS)

Zolensky, M.; Fries, M.; Chan, Q. H.-S.; Kebukawa, Y.; Bodnar, R.; Burton, A.; Callahan, M.; Steele, A.; Sandford, S.

2015-01-01

Spectroscopic evidence supports the presence of Mg-Na-K salts derived from cryovolcanism on the surface of Europa. Halite (NaCl) is effective at very long-term preservation of organic phases and structures. Collection of salt crystals from Europan plumes would provide solid inclusions of organics, potentially also biomaterials, all suitable for analysis. Two thermally-metamorphosed ordinary chondrite regolith breccias (Monahans 1998 (H5) and Zag (H3-6)) contain fluid and solid inclusion-bearing halite crystals, dated to approximately 4.5 billion years, and thus the trapped aqueous fluids and solids are at least as old. Heating/freezing studies of the aqueous fluid inclusions in these halites demonstrated that they were trapped near 25 degrees Centigrade, and their continued presence in the halite grains requires that their incorporation into the H chondrite asteroid occurred after that body's metamorphism ended, since heating would have dessicated the halite. O and H isotopes of the trapped fluids are consistent with mixing of asteroidal and cometary water. Cryovolcanic Origin of the Halite: We hypothesize that these meteoritic halites derive from ancient cryovolcanism based on the following points. (1) Salts crystals are observed as products of current cryovolcanism on Enceladus. (2) In-situ spacecraft analysis of some of the icy grains associated with the Enceladus salt found minor organic or siliceous components, including methane, also found in the Monahans halite. (3) Cryovolcanic fluids are observed to be in chemical disequilibrium, reflecting incomplete reactions between interior volatiles and rocky materials. The coexistence of N2 and HCN in Enceladus' cryovolcanic fluids requires that the plume consists of a mixture of materials whose sources experienced different degrees of aqueous processing, including primordial material trapped in ice that has not been in contact with liquid water. The observed mineral assemblage within the Monahans and Zag halites is also far from equilibrium. Cryovolcanoes on Ceres are a potential source of our halite, however the processes that form halite should also be operating within Europa. Dissolution of Monahans halite grains has revealed a remarkable variety of organics, which dominate the population of solid inclusions. Thermal alteration of this macromolecular carbon (measured by Raman spectroscopy) shows remarkable diversity. We have identified highly-condensed aromatics, diamond, carbonates and chloromethane. Light organic compounds like methane tend to be water soluble and require cold formation temperatures at high hydrogen fugacity - i.e. require water ice. Another indication that these halites have not been heated is that light organics readily volatilize or aromaticize into PAHs. We are currently analyzing the organics by Raman and C-XANES, and measuring the content and exploring the potential chirality of amino acids in the halite. Implications for Europa Plumes: Organic materials and structures erupted by a Europa cryovolcano should be similarly preserved within halite, and other salts, which will be a convenient form for capture and analysis, since halite will serve to encapsulate and protect the organics from spacecraft contamination. Also, being transparent at many wavelengths halite will permit analysis by spacecraft-mounted spectroscopic techniques. In addition, halite is readily dissolved, permitting further analysis of entrained organics.

A Heliosphere Buffeted by Interstellar Turbulence?

NASA Astrophysics Data System (ADS)

Jokipii, J. R.; Giacalone, J.

2014-12-01

Recent observations from IBEX combined with previous measurements from other sources suggest new, local, effects of interstellar turbulence. Observations of various interstellar parameters such as the magnetic field, fluid velocity and electron density, over large spatial scales, have revealed a broadband Kolmogorov spectrum of interstellar turbulence which pervades most of interstellar space. The outer scale (or coherence scale of this turbulence) is found to be approximately 10^19 cm and the inner cutoff scale is less than 1000 km. The root-mean-square relative fluctuation in the fluid and the magnetic-field parameters is of order unity. If this turbulence exists at the heliosphere, the root-mean-square relative fluctuations at 100 (heliospheric) AU scales is approximately 0.1. The recently published value for the change In observed velocity direction for the interstellar flow relative to the heliosphere (Frisch, etal, 2014)is consistent with this. Similarly, interpreting the width of the IBEX ribbon in terms of a fluctuating magnetic field also is in agreement with this picture. Observations of TeV cosmic rays can also be explained. Potential effects of these fluctuations in the interstellar medium on the heliosphere will be discussed. Reference: Frisch, etal, Science, 341, 480

Electrokinetic high pressure hydraulic system

DOEpatents

Paul, Phillip H.; Rakestraw, David J.

2000-01-01

A compact high pressure hydraulic pump having no moving mechanical parts for converting electric potential to hydraulic force. The electrokinetic pump, which can generate hydraulic pressures greater than 2500 psi, can be employed to compress a fluid, either liquid or gas, and manipulate fluid flow. The pump is particularly useful for capillary-base systems. By combining the electrokinetic pump with a housing having chambers separated by a flexible member, fluid flow, including high pressure fluids, is controlled by the application of an electric potential, that can vary with time.

Exposure of Athletic Trainers to Potentially Infectious Bodily Fluids in the High School Setting.

ERIC Educational Resources Information Center

Middlemas, David A.; Jessee, K. Brian; Mulder, Diane K.; Rehberg, Robb S.

1997-01-01

Examined high school athletic trainers' exposure to potentially infectious bodily fluids. Data on number of potential exposures per game and practice, number of athletes removed from competition for bleeding, and number of times athletes changed uniforms indicated that trainers had significant chances of being exposed to potentially infectious…

On the role of fluids in stick-slip dynamics of saturated granular fault gouge using a coupled computational fluid dynamics-discrete element approach

NASA Astrophysics Data System (ADS)

Dorostkar, Omid; Guyer, Robert A.; Johnson, Paul A.; Marone, Chris; Carmeliet, Jan

2017-05-01

The presence of fault gouge has considerable influence on slip properties of tectonic faults and the physics of earthquake rupture. The presence of fluids within faults also plays a significant role in faulting and earthquake processes. In this paper, we present 3-D discrete element simulations of dry and fluid-saturated granular fault gouge and analyze the effect of fluids on stick-slip behavior. Fluid flow is modeled using computational fluid dynamics based on the Navier-Stokes equations for an incompressible fluid and modified to take into account the presence of particles. Analysis of a long time train of slip events shows that the (1) drop in shear stress, (2) compaction of granular layer, and (3) the kinetic energy release during slip all increase in magnitude in the presence of an incompressible fluid, compared to dry conditions. We also observe that on average, the recurrence interval between slip events is longer for fluid-saturated granular fault gouge compared to the dry case. This observation is consistent with the occurrence of larger events in the presence of fluid. It is found that the increase in kinetic energy during slip events for saturated conditions can be attributed to the increased fluid flow during slip. Our observations emphasize the important role that fluid flow and fluid-particle interactions play in tectonic fault zones and show in particular how discrete element method (DEM) models can help understand the hydromechanical processes that dictate fault slip.

Substellar fragmentation in self-gravitating fluids with a major phase transition

NASA Astrophysics Data System (ADS)

Füglistaler, A.; Pfenniger, D.

2015-06-01

Context. The observation of various ices in cold molecular clouds, the existence of ubiquitous substellar, cold H2 globules in planetary nebulae and supernova remnants, or the mere existence of comets suggest that the physics of very cold interstellar gas might be much richer than usually envisioned. At the extreme of low temperatures (≲10 K), H2 itself is subject to a phase transition crossing the entire cosmic gas density scale. Aims: This well-known, laboratory-based fact motivates us to study the ideal case of a cold neutral gaseous medium in interstellar conditions for which the bulk of the mass, instead of trace elements, is subject to a gas-liquid or gas-solid phase transition. Methods: On the one hand, the equilibrium of general non-ideal fluids is studied using the virial theorem and linear stability analysis. On the other hand, the non-linear dynamics is studied using computer simulations to characterize the expected formation of solid bodies analogous to comets. The simulations are run with a state-of-the-art molecular dynamics code (LAMMPS) using the Lennard-Jones inter-molecular potential. The long-range gravitational forces can be taken into account together with short-range molecular forces with finite limited computational resources, using super-molecules, provided the right scaling is followed. Results: The concept of super-molecule, where the phase transition conditions are preserved by the proper choice of the particle parameters, is tested with computer simulations, allowing us to correctly satisfy the Jeans instability criterion for one-phase fluids. The simulations show that fluids presenting a phase transition are gravitationally unstable as well, independent of the strength of the gravitational potential, producing two distinct kinds of substellar bodies, those dominated by gravity (planetoids) and those dominated by molecular attractive force (comets). Conclusions: Observations, formal analysis, and computer simulations suggest the possibility of the formation of substellar H2 clumps in cold molecular clouds due to the combination of phase transition and gravity. Fluids presenting a phase transition are gravitationally unstable, independent of the strength of the gravitational potential. Arbitrarily small H2 clumps may form even at relatively high temperatures up to 400-600 K, according to virial analysis. The combination of phase transition and gravity may be relevant for a wider range of astrophysical situations, such as proto-planetary disks. Figures 33-44 are available in electronic form at http://www.aanda.org

A physicochemical framework for interpreting the biological calcification response to CO2-induced ocean acidification

NASA Astrophysics Data System (ADS)

Ries, J. B.

2011-12-01

Researchers investigating the responses of marine calcifiers to CO2-induced ocean acidification have reported surprisingly variable results. A generalized proton-pumping-based model of marine organisms' calcifying fluids, considered for present and forecasted atmospheric pCO2 scenarios (400 - 2850 μatm), is able to generate the full spectrum of calcification response patterns observed in prior ocean acidification experiments, including negative, non-linear, and positive. The removal of H+ from an organism's calcifying fluid requires energy. Two factors that influence the amount of energy required to regulate calcification site pH are the quantity of H+ removed from a given volume of the calcifying fluid and the H+-gradient across the membrane(s) that bounds the calcifying fluid. The energy required to maintain a H+-gradient across a membrane, known as the Nernst potential (E), can be defined as: E = (RT)/(nF) x ln([H+]e/[H+]i) where R is the universal gas constant, T is absolute temperature, n is the valence charge of H+, F is the Faraday constant, and [H+]e and [H+]i are H+ concentrations of the external seawater and of the organism's calcifying fluid, respectively. Because R, T, n and F are constants in the described H+-membrane system, the magnitude of the Nernst potential, or the energetic cost of maintaining a H+-gradient between external seawater and an organism's membrane-bound calcifying fluid, should be roughly proportional to [H+]e/[H+]i. The proton-pumping model is therefore parameterized by two end-member scenarios: one in which a fixed number of H+ is removed from the calcifying fluid, regardless of atmospheric pCO2, and another in which a fixed [H+]e/[H+]i is maintained. The model is empirically evaluated for the temperate scleractinian coral Astrangia poculata with in situ pH microelectrode measurements of the coral's calcifying fluid under control and acidified conditions. These measurements reveal that (1) the pH and, thus, aragonite saturation state (ΩA) of the coral's calcifying fluid (CF) is substantially elevated relative to the coral's external seawater (SW) under both the control (CF pH = 10.1±0.1, ΩA = 25 ± 1; SW pH = 8.2, ΩA = 2.9) and acidified treatments (CF pH = 9.4±0.1, ΩA = 19 ± 1; SW pH = 7.5, ΩA = 0.6), (2) the coral's [H+]e/[H+]i remains constant (~80:1) under control and acidified conditions, and (3) the coral removes fewer H+ from its CF under acidified conditions (1570 ± 70 μmol H+/kg-SW) than under control conditions (2230 ± 150 μmol H+/kg-SW). Thus, the carbonate system dynamics of A. poculata's calcifying fluid appear to be most consistent with the fixed [H+]e/[H+]i end-member scenario. These models and observations are consistent with the assertion that organisms' calcification response to future CO2-induced ocean acidification will be more negative for marine calcifiers that exert weaker control over the pH of their calcifying fluid. This control over calcifying fluid pH-and thus response to ocean acidification- should vary not only amongst taxa, but also within taxa, depending upon developmental stage, health, nutritional status, and existence of additional stressors (e.g., warming, pollution).

Evaluation of haemoglobin in blister fluid as an indicator of paediatric burn wound depth.

PubMed

Tanzer, Catherine; Sampson, Dayle L; Broadbent, James A; Cuttle, Leila; Kempf, Margit; Kimble, Roy M; Upton, Zee; Parker, Tony J

2015-08-01

The early and accurate assessment of burns is essential to inform patient treatment regimens; however, this first critical step in clinical practice remains a challenge for specialist burns clinicians worldwide. In this regard, protein biomarkers are a potential adjunct diagnostic tool to assist experienced clinical judgement. Free circulating haemoglobin has previously shown some promise as an indicator of burn depth in a murine animal model. Using blister fluid collected from paediatric burn patients, haemoglobin abundance was measured using semi-quantitative Western blot and immunoassays. Although a trend was observed in which haemoglobin abundance increased with burn wound severity, several patient samples deviated significantly from this trend. Further, it was found that haemoglobin concentration decreased significantly when whole cells, cell debris and fibrinous matrix was removed from the blister fluid by centrifugation; although the relationship to depth was still present. Statistical analyses showed that haemoglobin abundance in the fluid was more strongly related to the time between injury and sample collection and the time taken for spontaneous re-epithelialisation. We hypothesise that prolonged exposure to the blister fluid microenvironment may result in an increased haemoglobin abundance due to erythrocyte lysis, and delayed wound healing. Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.

Total Fluid and Water Consumption and the Joint Effect of Exposure to Disinfection By-Products on Risk of Bladder Cancer

PubMed Central

Michaud, Dominique S.; Kogevinas, Manolis; Cantor, Kenneth P.; Villanueva, Cristina M.; Garcia-Closas, Monteserrat; Rothman, Nathaniel; Malats, Nuria; Real, Francisco X.; Serra, Consol; Garcia-Closas, Reina; Tardon, Adonina; Carrato, Alfredo; Dosemeci, Mustafa; Silverman, Debra T.

2007-01-01

Background Findings on water and total fluid intake and bladder cancer are inconsistent; this may, in part, be due to different levels of carcinogens in drinking water. High levels of arsenic and chlorinated by-products in drinking water have been associated with elevated bladder cancer risk in most studies. A pooled analysis based on six case–control studies observed a positive association between tap water and bladder cancer but none for nontap fluid intake, suggesting that contaminants in tap water may be responsible for the excess risk. Objectives We examined the association between total fluid and water consumption and bladder cancer risk, as well as the interaction between water intake and trihalomethane (THM) exposure, in a large case–control study in Spain. Methods A total of 397 bladder cancer cases and 664 matched controls were available for this analysis. Odds ratios (OR) were estimated using unconditional logistic regression, controlling for potential confounders. Results Total fluid intake was associated with a decrease in bladder cancer risk [OR = 0.62; 95% confidence interval (CI), 0.40–0.95 for highest vs. lowest quintile comparison]. A significant inverse association was observed for water intake (for > 1,399 vs. < 400 mL/day, OR = 0.47; 95% CI, 0.33–0.66; p for trend < 0.0001), but not for other individual beverages. The inverse association between water intake and bladder cancer persisted within each level of THM exposure; we found no statistical interaction (p for interaction = 0.13). Conclusion Findings from this study suggest that water intake is inversely associated with bladder cancer risk, regardless of THM exposure level. PMID:18007986

Geophysical signature of hydration-dehydration processes in active subduction zones

NASA Astrophysics Data System (ADS)

Reynard, Bruno

2013-04-01

Seismological and magneto-telluric tomographies are potential tools for imaging fluid circulation when combined with petrophysical models. Recent measurements of the physical properties of serpentine allow refining hydration of the mantle and fluid circulation in the mantle wedge from geophysical data. In the slab lithospheric mantle, serpentinization caused by bending at the trench is limited to a few kilometers below the oceanic crust (<5 km). Double Wadati-Benioff zones, 20-30 km below the crust, are explained by deformation of dry peridotites, not by serpentine dehydration. It reduces the required amount of water stored in solid phases in the slab (Reynard et al., 2010). In the cold (<700°C) fore-arc mantle wedge above the subducting slab, serpentinization is caused by the release of large amounts of hydrous fluids in the cold mantle above the dehydrating subducted plate. Low seismic velocities in the wedge give a time-integrated estimate of hydration and serpentinization. Serpentinization reaches 50-100% in hot subduction, while it is below 10% in cold subduction (Bezacier et al., 2010; Reynard, 2012). Electromagnetic profiles of the mantle wedge reveal high electrical-conductivity bodies. In hot areas of the mantle wedge (> 700°C), water released by dehydration of the slab induces melting of the mantle under volcanic arcs, explaining the observed high conductivities. In the cold melt-free wedge (< 700°C), high conductivities in electromagnetic profiles provide "instantaneous" images of fluid circulation because the measured electrical conductivity of serpentine is below 0.1 mS/m (Reynard et al., 2011). A small fraction (ca. 1% in volume) of connective high-salinity fluids accounts for the highest observed conductivities. Low-salinity fluids (≤ 0.1 m) released by slab dehydration evolve towards high-salinity (≥ 1 m) fluids during progressive serpentinization in the wedge. These fluids can mix with arc magmas at depths and account for high-chlorine melt inclusions in arc lavas. High electrical conductivities up to 1 S/m in the hydrated wedge of the hot subductions (Ryukyu, Kyushu, Cascadia) reflect high fluid concentration, while low to moderate (<0.01 S/m) conductivities in the cold subductions (N-E Japan, Bolivia) reflect low fluid flow. This is consistent with the seismic observations of extensive shallow serpentinization in hot subduction zones, while serpentinization is sluggish in cold subduction zones. Bezacier, L., et al. 2010. Elasticity of antigorite, seismic detection of serpentinites, and anisotropy in subduction zones. Earth and Planetary Science Letters, 289, 198-208. Reynard, B., 2012. Serpentine in active subduction zones. Lithos, http://dx.doi.org/10.1016/j.lithos.2012.10.012. Reynard, B., Mibe, K. & Van de Moortele, B., 2011. Electrical conductivity of the serpentinised mantle and fluid flow in subduction zones. Earth and Planetary Science Letters, 307, 387-394. Reynard, B., Nakajima, J. & Kawakatsu, H., 2010. Earthquakes and plastic deformation of anhydrous slab mantle in double Wadati-Benioff zones. Geophysical Research Letters, 37, L24309.

Thermodynamic modeling of non-ideal mineral-fluid equilibria in the system Si-Al-Fe-Mg-Ca-Na-K-H-O-Cl at elevated temperatures and pressures: Implications for hydrothermal mass transfer in granitic rocks

NASA Astrophysics Data System (ADS)

Dolejš, David; Wagner, Thomas

2008-01-01

We present the results of thermodynamic modeling of fluid-rock interaction in the system Si-Al-Fe-Mg-Ca-Na-H-O-Cl using the GEM-Selektor Gibbs free energy minimization code. Combination of non-ideal mixing properties in solids with multicomponent aqueous fluids represents a substantial improvement and it provides increased accuracy over existing modeling strategies. Application to the 10-component system allows us to link fluid composition and speciation with whole-rock mineralogy, mass and volume changes. We have simulated granite-fluid interaction over a wide range of conditions (200-600 °C, 100 MPa, 0-5 m Cl and fluid/rock ratios of 10-2-104) in order to explore composition of magmatic fluids of variable salinity, temperature effects on fluid composition and speciation and to simulate several paths of alteration zoning. At low fluid/rock ratios (f/r) the fluid composition is buffered by the silicate-oxide assemblage and remains close to invariant. This behavior extends to a f/r of 0.1 which exceeds the amount of exsolved magmatic fluids controlled by water solubility in silicate melts. With increasing peraluminosity of the parental granite, the Na-, K- and Fe-bearing fluids become more acidic and the oxidation state increases as a consequence of hydrogen and ferrous iron transfer to the fluid. With decreasing temperature, saline fluids become more Ca- and Na-rich, change from weakly acidic to alkaline, and become significantly more oxidizing. Large variations in Ca/Fe and Ca/Mg ratios in the fluid are a potential geothermometer. The mineral assemblage changes from cordierite-biotite granites through two-mica granites to chlorite-, epidote- and zeolite-bearing rocks. We have carried out three rock-titration simulations: (1) reaction with the 2 m NaCl fluid leads to albitization, chloritization and desilication, reproducing essential features observed in episyenites, (2) infiltration of a high-temperature fluid into the granite at 400 °C leads to hydrolytic alteration commencing with alkali-feldspar breakdown and leading to potassic, phyllic and argillic assemblages; this is associated with reduction and iron metasomatism as observed in nature and (3) interaction with a multicomponent fluid at 600 °C produces sodic-calcic metasomatism. Na, Ca and Fe are the most mobile elements whereas immobility of Al is limited by f/r ∼ 400. All simulations predict a volume decrease by 3.4-5.4%, i.e., porosity formation at f/r < 30. At higher fluid/rock ratios simulation (2) produces a substantial volume increase (59%) due to mineral precipitation, whereas simulation (3) predicts a volume decrease by 49% at the advanced albitization-desilication stage. Volume changes closely correlate with mass changes of SiO2 and are related to silica solubility in fluids. The combined effects of oxygen fugacity, fluid acidity and pH for breakdown of aqueous metal complexes and precipitation of ore minerals were evaluated by means of reduced activity products. Sharp increases in saturation indexes for oxidative breakdown occur at each alteration zone whereas reductive breakdown or involvement of other chloride complexes favor precipitation at high fluid/rock ratios only. Calculations of multicomponent aqueous-solid equilibria at high temperatures and pressures are able to accurately predict rock mineralogy and fluid chemistry and are applicable to diverse reactive flow processes in the Earth's crust.

Term amniotic fluid: an unexploited reserve of mesenchymal stromal cells for reprogramming and potential cell therapy applications.

PubMed

Moraghebi, Roksana; Kirkeby, Agnete; Chaves, Patricia; Rönn, Roger E; Sitnicka, Ewa; Parmar, Malin; Larsson, Marcus; Herbst, Andreas; Woods, Niels-Bjarne

2017-08-25

Mesenchymal stromal cells (MSCs) are currently being evaluated in numerous pre-clinical and clinical cell-based therapy studies. Furthermore, there is an increasing interest in exploring alternative uses of these cells in disease modelling, pharmaceutical screening, and regenerative medicine by applying reprogramming technologies. However, the limited availability of MSCs from various sources restricts their use. Term amniotic fluid has been proposed as an alternative source of MSCs. Previously, only low volumes of term fluid and its cellular constituents have been collected, and current knowledge of the MSCs derived from this fluid is limited. In this study, we collected amniotic fluid at term using a novel collection system and evaluated amniotic fluid MSC content and their characteristics, including their feasibility to undergo cellular reprogramming. Amniotic fluid was collected at term caesarean section deliveries using a closed catheter-based system. Following fluid processing, amniotic fluid was assessed for cellularity, MSC frequency, in-vitro proliferation, surface phenotype, differentiation, and gene expression characteristics. Cells were also reprogrammed to the pluripotent stem cell state and differentiated towards neural and haematopoietic lineages. The average volume of term amniotic fluid collected was approximately 0.4 litres per donor, containing an average of 7 million viable mononuclear cells per litre, and a CFU-F content of 15 per 100,000 MNCs. Expanded CFU-F cultures showed similar surface phenotype, differentiation potential, and gene expression characteristics to MSCs isolated from traditional sources, and showed extensive expansion potential and rapid doubling times. Given the high proliferation rates of these neonatal source cells, we assessed them in a reprogramming application, where the derived induced pluripotent stem cells showed multigerm layer lineage differentiation potential. The potentially large donor base from caesarean section deliveries, the high yield of term amniotic fluid MSCs obtainable, the properties of the MSCs identified, and the suitability of the cells to be reprogrammed into the pluripotent state demonstrated these cells to be a promising and plentiful resource for further evaluation in bio-banking, cell therapy, disease modelling, and regenerative medicine applications.

Fluid transport by dipolar vortices

NASA Astrophysics Data System (ADS)

I, Eames; J.-B, Flór

1998-08-01

The transport properties of dipolar vortices propagating on an f-plane are studied experimentally by examining the distortion of a series of material surfaces. The observations are compared with a model based on characterising the flow around the dipole as irrotational flow past a rigid cylinder of volume V. Measurements made of the volume of fluid permanently displaced forward by the vortices, agree to within 20% of that predicted by the proposition of Darwin [Darwin, C., 1953. A note on hydrodynamics. Proc. Cambridge Philos. Soc., 49, 342-354], namely that the vortex will displace a volume CMV forward, where CM=1 for a Lamb's dipole. The results are applied to examine fluid transport by dipolar vortices propagating on the β-plane, where the ambient potential vorticity field causes easterly propagating dipolar vortices to meander sinusoidally between the North and South. We demonstrate that as the vortex moves between the North and South, it exchanges a volume CMV sin α by the drift effect (where α is the angle between the velocity of the dipole and the material surface), which is generally larger than that attributed to other mechanisms such as lobe shedding. The results are applied to give new insight to the effect of vortices in enhancing diffusion, and the secondary flow generated by the transport of ambient potential vorticity.

Optimization of a hydrodynamic separator using a multiscale computational fluid dynamics approach.

PubMed

Schmitt, Vivien; Dufresne, Matthieu; Vazquez, Jose; Fischer, Martin; Morin, Antoine

2013-01-01

This article deals with the optimization of a hydrodynamic separator working on the tangential separation mechanism along a screen. The aim of this study is to optimize the shape of the device to avoid clogging. A multiscale approach is used. This methodology combines measurements and computational fluid dynamics (CFD). A local model enables us to observe the different phenomena occurring at the orifice scale, which shows the potential of expanded metal screens. A global model is used to simulate the flow within the device using a conceptual model of the screen (porous wall). After validation against the experimental measurements, the global model was used to investigate the influence of deflectors and disk plates in the structure.

Multi-Fluid Simulations of Field Reversed Configuration Formation

NASA Astrophysics Data System (ADS)

Sousa, Eder; Martin, Robert

2017-10-01

The use of field reversed configuration (FRC) have been studied extensively for fusion application but here we investigate them for propulsion purposes. FRCs have the potential to produce highly variable thrust and specific impulse using different gases as propellant. Aspects of the FRC formation physics, using a rotating magnetic field (RMF) at low power, are simulated using a multi-fluid plasma model. Results are compared with experimental observations with emphasis in the development of instabilities and robustness of the field reversal. The use of collisional radiative models are used to help compare experiment versus simulation results. Distribution A: Approved for public release; distribution unlimited; Clearance No. 17445. This work is supported by the Air Force Office of Scientific Research Grant Number 17RQCOR465.

Theory of a peristaltic pump for fermionic quantum fluids

NASA Astrophysics Data System (ADS)

Romeo, F.; Citro, R.

2018-05-01

Motivated by the recent developments in fermionic cold atoms and in nanostructured systems, we propose the model of a peristaltic quantum pump. Differently from the Thouless paradigm, a peristaltic pump is a quantum device that generates a particle flux as the effect of a sliding finite-size microlattice. A one-dimensional tight-binding Hamiltonian model of this quantum machine is formulated and analyzed within a lattice Green's function formalism on the Keldysh contour. The pump observables, as, e.g., the pumped particles per cycle, are studied as a function of the pumping frequency, the width of the pumping potential, the particles mean free path, and system temperature. The proposed analysis applies to arbitrary peristaltic potentials acting on fermionic quantum fluids confined to one dimension. These confinement conditions can be realized in nanostructured systems or, in a more controllable way, in cold atoms experiments. In view of the validation of the theoretical results, we describe the outcomes of the model considering a fermionic cold atoms system as a paradigmatic example.

Measurement of localized tissue water - clinical application of bioimpedance spectroscopy in wound management

NASA Astrophysics Data System (ADS)

Ward, L. C.; Sharpe, K.; Edgar, D.; Finlay, V.; Wood, F.

2013-04-01

Wound healing is a complex process which can be impeded by the presence of accumulated cell fluid or oedema. A simple and convenient method for the assessment of wound oedema would aid improvement in patient care. In this proof of concept study we investigated whether bioelectrical impedance spectroscopy has the potential to provide such a tool. A number of important observations were made. Firstly, the method was highly reproducible and data can be obtained from electrodes located at different positions around the region of interest; important given the highly variable topography of surface wounds, e.g. burns. Secondly, the method was highly sensitive with the potential to detect changes of as little as 20 μl in extracellular fluid. Thirdly the relative changes in R0, R∞ and Ri following sub-cutaneous injections of saline were consistent with redistribution of water from the extracellular to intracellular space and /or removal from the local area as may occur during wound healing.

Shearing black holes and scans of the quark matter phase diagram

NASA Astrophysics Data System (ADS)

McInnes, Brett

2014-01-01

Future facilities such as FAIR and NICA are expected to produce collisions of heavy ions generating quark-gluon plasmas (QGPs) with large values of the quark chemical potential; peripheral collisions in such experiments will also lead to large values of the angular momentum density, associated with the internal shearing motion of the plasma. It is well known that shearing motions in fluids can lead to instabilities which cause a transition from laminar to turbulent flow, and such instabilities in the QGP have recently attracted some attention. We set up a holographic model of this situation by constructing a gravitational dual system exhibiting an instability which is indeed triggered by shearing angular momentum in the bulk. We show that holography indicates that the transition to an unstable fluid happens more quickly as one scans across the quark matter phase diagram towards large values of the chemical potential. This may have negative consequences for the observability of quark polarization effects.

Transient electrokinetic transport in a finite length microchannel: currents, capacitance, and an electrical analogy.

PubMed

Mansouri, Ali; Bhattacharjee, Subir; Kostiuk, Larry W

2007-11-08

Numerical simulations with the fluid mechanics based on the unsteady Navier-Stokes equations and the Poisson-Nernst-Planck formulation of electrostatics and ion transport were used to explore the transient transport of charge through a finite length cylindrical microchannel that is driven by a pressure difference. The evolution of the transcapillary potential from a no-flow equilibrium to the steady-state-steady-flow streaming potential was analyzed by following the convection, migration, and net currents. Observations of the unsteady characteristics of the streaming current, electrical resistance, and capacitance led to an electrical analogy. This electrical analogy was made from a current source (to represent convection current), which was placed in parallel with a capacitor (to allow the accumulation of charge) and a resistor (to permit a migration current). A parametric study involving a range of geometries, fluid mechanics, electrostatics, and mass transfer states allowed predictive submodels for the current source, capacitor, and resistor to be developed based on a dimensional analysis.

Near-trench slip potential of megaquakes evaluated from fault properties and conditions

PubMed Central

Hirono, Tetsuro; Tsuda, Kenichi; Tanikawa, Wataru; Ampuero, Jean-Paul; Shibazaki, Bunichiro; Kinoshita, Masataka; Mori, James J.

2016-01-01

Near-trench slip during large megathrust earthquakes (megaquakes) is an important factor in the generation of destructive tsunamis. We proposed a new approach to assessing the near-trench slip potential quantitatively by integrating laboratory-derived properties of fault materials and simulations of fault weakening and rupture propagation. Although the permeability of the sandy Nankai Trough materials are higher than that of the clayey materials from the Japan Trench, dynamic weakening by thermally pressurized fluid is greater at the Nankai Trough owing to higher friction, although initially overpressured fluid at the Nankai Trough restrains the fault weakening. Dynamic rupture simulations reproduced the large slip near the trench observed in the 2011 Tohoku-oki earthquake and predicted the possibility of a large slip of over 30 m for the impending megaquake at the Nankai Trough. Our integrative approach is applicable globally to subduction zones as a novel tool for the prediction of extreme tsunami-producing near-trench slip. PMID:27321861

Metabolic endotoxaemia--a potential novel link between ovarian inflammation and impaired progesterone production.

PubMed

Tremellen, Kelton; Syedi, Naeema; Tan, Sze; Pearce, Karma

2015-04-01

Medical conditions such as obesity and inflammatory bowel disease are associated with impaired luteal function, menstrual disturbance and infertility. It is proposed that the disturbance in gut wall integrity ("leaky gut") seen in these conditions may result in the passage of bacterial endotoxin (LPS) from the colonic lumen into the circulation that may initiate inflammation in the ovary and subsequently impair hormone production. Quantify the association between systemic levels of LBP, a marker of endotoxin exposure, and levels of inflammation in the ovary (follicular fluid IL-6), plus steroid hormone production in 45 women undergoing IVF treatment. Endotoxaemia (LBP) were positively correlated with plasma CRP and inflammation within the ovary (follicular fluid IL-6). Furthermore, endotoxaemia was negatively correlated with progesterone production. The observed correlations, together with previously published animal studies linking endotoxin exposure to impaired luteal function, suggest that the translocation of bacterial endotoxin from the gut lumen into the circulation has the potential to interfere with progesterone production and result in luteal deficiency.

The growth of Staphylococcus aureus and Escherichia coli in low-direct current electric fields.

PubMed

Zituni, Dunya; Schütt-Gerowitt, Heidi; Kopp, Marion; Krönke, Martin; Addicks, Klaus; Hoffmann, Christian; Hellmich, Martin; Faber, Franz; Niedermeier, Wilhelm

2014-03-01

Electrical potentials up to 800 mV can be observed between different metallic dental restorations. These potentials produce fields in the mouth that may interfere with microbial communities. The present study focuses on the impact of different electric field strengths (EFS) on the growth of Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) in vitro. Cultures of S. aureus and E. coli in fluid and gel medium were exposed to different EFS. Effects were determined by calculation of viable counts and measurement of inhibition zones. In gel medium, anodic inhibition zones for S. aureus were larger than those for E. coli at all field strength levels. In fluid medium, the maximum decrease in the viable count of S. aureus cells was at 10 V⋅m(-1). Field-treated S. aureus cells presented ruptured cell walls and disintegrated cytoplasm. Conclusively, S. aureus is more sensitive to increasing electric field strength than E. coli.

Simethicone residue remains inside gastrointestinal endoscopes despite reprocessing.

PubMed

Ofstead, Cori L; Wetzler, Harry P; Johnson, Ellen A; Heymann, Otis L; Maust, Thomas J; Shaw, Michael J

2016-11-01

During a study designed to assess endoscope reprocessing effectiveness, a borescope was used to examine lumens and ports. Cloudy, white, viscous fluid was observed inside fully reprocessed gastroscopes and colonoscopes. This fluid resembled simethicone, which is commonly administered to reduce foam and bubbles that impede visualization during gastrointestinal endoscopy. This article describes methods used to determine whether the observed fluid contained simethicone. Photographs of residual fluid were taken using a borescope. Sterile cotton-tipped swabs were used to collect samples of fluid observed in 3 endoscope ports. Samples were evaluated using Fourier transform infrared spectroscopy (FTIR)-attenuated total reflection analysis. Residual fluid was observed inside 19 of 20 endoscopes. Fluid photographed in 8 endoscopes resembled simethicone solutions. FTIR analysis confirmed the presence of simethicone in 2 endoscopes. Fluid containing simethicone remained inside endoscopes despite reprocessing. Simethicone is an inert, hydrophobic substance that may reduce reprocessing effectiveness. Simethicone solutions commonly contain sugars and thickeners, which may contribute to microbial growth and biofilm development. Studies are needed to assess the prevalence of residual moisture and simethicone in endoscopes and determine the impact on reprocessing effectiveness. We recommend minimizing the use of simethicone pending further research into its safety. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

A multiscale quasi-continuum theory to determine thermodynamic properties of fluid mixtures in nanochannels

NASA Astrophysics Data System (ADS)

Motevaselian, Mohammad Hossein; Mashayak, Sikandar Y.; Aluru, Narayana R.

2015-11-01

We present an empirical potential-based quasi-continuum theory (EQT) that seamlessly integrates the interatomic potentials into a continuum framework such as the Nernst-Planck equation. EQT is a simple and fast approach, which provides accurate predictions of potential of mean force (PMF) and density distribution of confined fluids at multiple length-scales, ranging from few Angstroms to macro meters. The EQT potentials can be used to construct the excess free energy functional in the classical density functional theory (cDFT). The combination of EQT and cDFT (EQT-cDFT), allows one to predict the thermodynamic properties of confined fluids. Recently, the EQT-cDFT framework was developed for single component LJ fluids confined in slit-like graphene channels. In this work, we extend the framework to confined LJ fluid mixtures and demonstrate it by simulating a mixture of methane and hydrogen molecules inside slit-like graphene channels. We show that the EQT-cDFT predictions for the structure of the confined fluid mixture compare well with the MD simulations. In addition, our results show that graphene nanochannels exhibit a selective adsorption of methane over hydrogen.

Temporal changes in fluid chemistry and energy profiles in the vulcano island hydrothermal system.

PubMed

Rogers, Karyn L; Amend, Jan P; Gurrieri, Sergio

2007-12-01

In June 2003, the geochemical composition of geothermal fluids was determined at 9 sites in the Vulcano hydrothermal system, including sediment seeps, geothermal wells, and submarine vents. Compositional data were combined with standard state reaction properties to determine the overall Gibbs free energy (DeltaG(r) ) for 120 potential lithotrophic and heterotrophic reactions. Lithotrophic reactions in the H-O-N-S-C-Fe system were considered, and exergonic reactions yielded up to 120 kJ per mole of electrons transferred. The potential for heterotrophy was characterized by energy yields from the complete oxidation of 6 carboxylic acids- formic, acetic, propanoic, lactic, pyruvic, and succinic-with the following redox pairs: O(2)/H(2)O, SO(4) (2)/H(2)S, NO(3) ()/NH(4) (+), S(0)/H(2)S, and Fe(3)O(4)/Fe(2+). Heterotrophic reactions yielded 6-111 kJ/mol e(). Energy yields from both lithotrophic and heterotrophic reactions were highly dependent on the terminal electron acceptor (TEA); reactions with O(2) yielded the most energy, followed by those with NO(3) (), Fe(III), SO(4) (2), and S(0). When only reactions with complete TEA reduction were included, the exergonic lithotrophic reactions followed a similar electron tower. Spatial variability in DeltaG(r) was significant for iron redox reactions, owing largely to the wide range in Fe(2+) and H(+) concentrations. Energy yields were compared to those obtained for samples collected in June 2001. The temporal variations in geochemical composition and energy yields observed in the Vulcano hydrothermal system between 2001 and 2003 were moderate. The largest differences in DeltaG(r) over the 2 years were from iron redox reactions, due to temporal changes in the Fe(2+) and H(+) concentrations. The observed variations in fluid composition across the Vulcano hydrothermal system have the potential to influence not only microbial diversity but also the metabolic strategies of the resident microbial communities.

Geochemical Modeling of Zinc Silicate Ore Formation from Sedimentary Hydrothermal Fluids

NASA Astrophysics Data System (ADS)

Appold, M. S.

2008-12-01

Sediment-hosted zinc deposits dominated by willemite (Zn2SiO4) instead of sphalerite (ZnS) are known from several prominent occurrences worldwide, including Vazante, Brazil, the Aroona Trend, Australia, Kabwe, Zambia, Berg Aukas, Namibia, and Abu Samar, Sudan. Although willemite-dominant zinc deposits appear to be much less common and are on average smaller than sphalerite-dominant zinc deposits, they nonetheless represent major enrichments of zinc in the Earth's crust, reaching sizes on the order of 1's to 10's of millions of tons and grades commonly between 20 and 40%. Sediment-hosted willemite- and sphalerite-dominant deposits share many similarities including their predominantly carbonate host rocks, gangue mineralogy, presumed derivation from sedimentary basinal brines, and spatial proximity. However, the conditions and processes that led to one style of mineralization versus the other have only recently begun to be investigated. The current study presents solubility, reaction path, and reactive transport modeling results that attempt to define more clearly the conditions that favor willemite ore formation in sedimentary basins, with a focus on the Vazante deposit. Solubility calculations for willemite and sphalerite as a function of temperature, pH, salinity, and oxidation potential were carried out using a simple 3 molal NaCl solution saturated with respect to quartz. The results show that (1) willemite solubility is relatively insensitive to changes in temperature and oxidation potential whereas sphalerite solubility decreases sharply with decreasing temperature and oxidation potential, (2) willemite solubility decreases more strongly than sphalerite with increasing pH, (3) willemite and sphalerite have a similar strong decrease in solubility with decreasing salinity. The results support a previously proposed genetic model for a willemite-dominant, sphalerite-subordinate ore body like Vazante in which a hot, acidic, metal-rich ore fluid mixed with a cooler, more oxidizing, dilute, and basic fluid. This scenario was investigated further with reaction path and reactive transport modeling. In these models, a more complex ore fluid was used that was assumed to have a major element composition similar to the global average for Mississippi Valley-type (MVT) deposits determined from the literature, modified by heating from 150 to 300° C, saturated with respect to dolomite and quartz, moderately acidic, and an oxidation potential near the value defined by magnetite-hematite equilibrium. The ore fluid was allowed to mix with a second, possibly meteoric fluid with about three orders of magnitude lower salinity, neutral pH, and a temperature of 50° C. The modeling results showed general agreement with the mineral assemblage observed at Vazante, and confirmed the need for a strong pH increase to induce willemite precipitation, and no more than a moderate increase in oxidation potential to allow some sphalerite to precipitate. The localization of mineralization within a shear zone was found to depend strongly on the shear zone having acted as a high permeability conduit for the ore fluid from deeper parts of the sedimentary basin.

Reduction of hexavalent chromium by fasted and fed human gastric fluid. I. Chemical reduction and mitigation of mutagenicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Flora, Silvio, E-mail: sdf@unige.it

Evaluation of the reducing capacity of human gastric fluid from healthy individuals, under fasted and fed conditions, is critical for assessing the cancer hazard posed by ingested hexavalent chromium [Cr(VI)] and for developing quantitative physiologically-based pharmacokinetic models used in risk assessment. In the present study, the patterns of Cr(VI) reduction were evaluated in 16 paired pre- and post-meal gastric fluid samples collected from 8 healthy volunteers. Human gastric fluid was effective both in reducing Cr(VI), as measured by using the s-diphenylcarbazide colorimetric method, and in attenuating mutagenicity in the Ames test. The mean (± SE) Cr(VI)-reducing ability of post-meal samplesmore » (20.4 ± 2.6 μg Cr(VI)/mL gastric fluid) was significantly higher than that of pre-meal samples (10.2 ± 2.3 μg Cr(VI)/mL gastric fluid). When using the mutagenicity assay, the decrease of mutagenicity produced by pre-meal and post-meal samples corresponded to reduction of 13.3 ± 1.9 and 25.6 ± 2.8 μg Cr(VI)/mL gastric fluid, respectively. These data are comparable to parallel results conducted by using speciated isotope dilution mass spectrometry. Cr(VI) reduction was rapid, with > 70% of total reduction occurring within 1 min and 98% of reduction is achieved within 30 min with post-meal gastric fluid at pH 2.0. pH dependence was observed with decreasing Cr(VI) reducing capacity at higher pH. Attenuation of the mutagenic response is consistent with the lack of DNA damage observed in the gastrointestinal tract of rodents following administration of ≤ 180 ppm Cr(VI) for up to 90 days in drinking water. Quantifying Cr(VI) reduction kinetics in the human gastrointestinal tract is necessary for assessing the potential hazards posed by Cr(VI) in drinking water. - Highlights: • Cr(VI) reduction capacity was greater in post-meal than paired pre-meal samples. • Cr(VI) reduction was rapid, pH dependent, and due to heat stable components. • Gastric fluid attenuates the mutagenicity of Cr(VI) and reduces risk of GI cancer. • The results are useful to quantitatively evaluate the fate of ingested Cr(VI).« less

Impact on a Compressible Fluid

NASA Technical Reports Server (NTRS)

Egorov, L. T.

1958-01-01

Upon impact of a solid body on the plane surface of a fluid, there occurs on the vetted surface of the body an abrupt pressure rise which propagates into both media with the speed of sound. Below, we assume the case where the speed of propagation of sound in the body which falls on the surface of the fluid may be regarded as infinitely large in comparison with the speed of propagation of sound in the fluid; that is, we shall assume that the falling body is absolutely rigid. IN this case, the entire relative speed of the motion which takes place at the beginning of the impact is absorbed by the fluid. The hydrodynamic pressures arising thereby are propagated from the contact surface within the fluid with the speed of sound in the form of compression and expansion waves and are gradually damped. After this, they are dispersed like impact pressures, reach ever larger regions of the fluid remote fran the body and became equal to zero; in the fluid there remain hydrodynamic pressures corresponding to the motion of the body after the impact. Neglecting the forces of viscosity and taking into account, furthermore, that the motion of the fluid begins from a state of rest, according to Thomson's theorem, we may consider the motion of an ideal compressible fluid in the process of impact to be potential. We examine the case of impact upon the surface of a ccmpressible fluid of a flat plate of infinite extent or of a body, the immersed part of the surface of which may be called approximately flat. In this report we discuss the first phase of the impact pressure on the surface of a fluid, prior to the appearance of a cavity, since at this stage the hydrodynamic pressures reach their maximum values. Observations, after the fall of the bodies on the surface of the fluid, show that the free surface of the fluid at this stage is almost completely at rest if one does not take into account the small rise in the neighborhood of the boundaries of the impact surface.

Destabilization of confined granular packings due to fluid flow

NASA Astrophysics Data System (ADS)

Monloubou, Martin; Sandnes, Bjørnar

2016-04-01

Fluid flow through granular materials can cause fluidization when fluid drag exceeds the frictional stress within the packing. Fluid driven failure of granular packings is observed in both natural and engineered settings, e.g. soil liquefaction and flowback of proppants during hydraulic fracturing operations. We study experimentally the destabilization and flow of an unconsolidated granular packing subjected to a point source fluid withdrawal using a model system consisting of a vertical Hele-Shaw cell containing a water-grain mixture. The fluid is withdrawn from the cell at a constant rate, and the emerging flow patterns are imaged in time-lapse mode. Using Particle Image Velocimetry (PIV), we show that the granular flow gets localized in a narrow channel down the center of the cell, and adopts a Gaussian velocity profile similar to those observed in dry grain flows in silos. We investigate the effects of the experimental parameters (flow rate, grain size, grain shape, fluid viscosity) on the packing destabilization, and identify the physical mechanisms responsible for the observed complex flow behaviour.

Flow Coupling between a Rotor and a Stator in Turbomachinery

DTIC Science & Technology

1990-04-01

potential-flow effects which would occur if the working fluid were perfectly inviscid. All observations made in practical situations represent a combination...interest. They are primarily working papers intended for internal use. They carry an identifying number which indicates their type and the numerical code of...release; distribution is unlimited. 4. PERFORMING ORGANIZATION REPORT NUMBER(S) s. MONITORING ORGANIZATION REPORT NUMBER(S) DTRC-PAS-90/15 Si. NAME OF

Advanced Colloids Experiment-1 (ACE-1)

NASA Image and Video Library

2013-07-22

ISS036-E-023770 (22 July 2013) --- NASA astronaut Chris Cassidy, Expedition 36 flight engineer, conducts science work with the ongoing experiment Advanced Colloids Experiment-1 (ACE-1) inside the Fluids Integrated Rack. The experiment observes colloids, microscopic particles evenly dispersed throughout materials, with the potential for manufacturing improved materials and products on Earth. Cassidy is working at the Light Microscopy Module (LMM) in the Destiny laboratory of the International Space Station.

Total fluid pressure imbalance in the scrape-off layer of tokamak plasmas

NASA Astrophysics Data System (ADS)

Churchill, R. M.; Canik, J. M.; Chang, C. S.; Hager, R.; Leonard, A. W.; Maingi, R.; Nazikian, R.; Stotler, D. P.

2017-04-01

Simulations using the fully kinetic neoclassical code XGCa (X-point included guiding- center axisymmetric) were undertaken to explore the impact of kinetic effects on scrape-off layer (SOL) physics in DIII-D H-mode plasmas. XGCa is a total-f, gyrokinetic code which self-consistently calculates the axisymmetric electrostatic potential and plasma dynamics, and includes modules for Monte Carlo neutral transport. Previously presented XGCa results showed several noteworthy features, including large variations of ion density and pressure along field lines in the SOL, experimentally relevant levels of SOL parallel ion flow (Mach number  ˜ 0.5), skewed ion distributions near the sheath entrance leading to subsonic flow there, and elevated sheath potentials (Churchill 2016 Nucl. Mater. Energy 1-6). In this paper, we explore in detail the question of pressure balance in the SOL, as it was observed in the simulation that there was a large deviation from a simple total pressure balance (the sum of ion and electron static pressure plus ion inertia). It will be shown that both the contributions from the ion viscosity (driven by ion temperature anisotropy) and neutral source terms can be substantial, and should be retained in the parallel momentum equation in the SOL, but still falls short of accounting for the observed fluid pressure imbalance in the XGCa simulation results.

On the role of fluids in stick-slip dynamics of saturated granular fault gouge using a coupled computational fluid dynamics-discrete element approach: STICK-SLIP IN SATURATED FAULT GOUGE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dorostkar, Omid; Guyer, Robert A.; Johnson, Paul A.

The presence of fault gouge has considerable influence on slip properties of tectonic faults and the physics of earthquake rupture. The presence of fluids within faults also plays a significant role in faulting and earthquake processes. In this study, we present 3-D discrete element simulations of dry and fluid-saturated granular fault gouge and analyze the effect of fluids on stick-slip behavior. Fluid flow is modeled using computational fluid dynamics based on the Navier-Stokes equations for an incompressible fluid and modified to take into account the presence of particles. Analysis of a long time train of slip events shows that themore » (1) drop in shear stress, (2) compaction of granular layer, and (3) the kinetic energy release during slip all increase in magnitude in the presence of an incompressible fluid, compared to dry conditions. We also observe that on average, the recurrence interval between slip events is longer for fluid-saturated granular fault gouge compared to the dry case. This observation is consistent with the occurrence of larger events in the presence of fluid. It is found that the increase in kinetic energy during slip events for saturated conditions can be attributed to the increased fluid flow during slip. Finally, our observations emphasize the important role that fluid flow and fluid-particle interactions play in tectonic fault zones and show in particular how discrete element method (DEM) models can help understand the hydromechanical processes that dictate fault slip.« less

On the role of fluids in stick-slip dynamics of saturated granular fault gouge using a coupled computational fluid dynamics-discrete element approach: STICK-SLIP IN SATURATED FAULT GOUGE

DOE PAGES

Dorostkar, Omid; Guyer, Robert A.; Johnson, Paul A.; ...

2017-05-01

The presence of fault gouge has considerable influence on slip properties of tectonic faults and the physics of earthquake rupture. The presence of fluids within faults also plays a significant role in faulting and earthquake processes. In this study, we present 3-D discrete element simulations of dry and fluid-saturated granular fault gouge and analyze the effect of fluids on stick-slip behavior. Fluid flow is modeled using computational fluid dynamics based on the Navier-Stokes equations for an incompressible fluid and modified to take into account the presence of particles. Analysis of a long time train of slip events shows that themore » (1) drop in shear stress, (2) compaction of granular layer, and (3) the kinetic energy release during slip all increase in magnitude in the presence of an incompressible fluid, compared to dry conditions. We also observe that on average, the recurrence interval between slip events is longer for fluid-saturated granular fault gouge compared to the dry case. This observation is consistent with the occurrence of larger events in the presence of fluid. It is found that the increase in kinetic energy during slip events for saturated conditions can be attributed to the increased fluid flow during slip. Finally, our observations emphasize the important role that fluid flow and fluid-particle interactions play in tectonic fault zones and show in particular how discrete element method (DEM) models can help understand the hydromechanical processes that dictate fault slip.« less

Integration of Reference Frames Using VLBI

NASA Technical Reports Server (NTRS)

Ma, Chopo; Smith, David E. (Technical Monitor)

2001-01-01

Very Long Baseline Interferometry (VLBI) has the unique potential to integrate the terrestrial and celestial reference frames through simultaneous estimation of positions and velocities of approx. 40 active VLBI stations and a similar number of stations/sites with sufficient historical data, the position and position stability of approx. 150 well-observed extragalactic radio sources and another approx. 500 sources distributed fairly uniformly on the sky, and the time series of the five parameters that specify the relative orientation of the two frames. The full realization of this potential is limited by a number of factors including the temporal and spatial distribution of the stations, uneven distribution of observations over the sources and the sky, variations in source structure, modeling of the solid/fluid Earth and troposphere, logistical restrictions on the daily observing network size, and differing strategies for optimizing analysis for TRF, for CRF and for EOP. The current status of separately optimized and integrated VLBI analysis will be discussed.

Molecular simulation of fluid adsorption in buckytubes and MCM-41

NASA Astrophysics Data System (ADS)

Maddox, M. W.; Gubbins, K. E.

1994-11-01

We report grand canonical Monte Carlo (GCMC) molecular-simulation studies of argon and nitrogen in models of two novel adsorbents, buckytubes and MCM-41. Buckytubes are monodisperse carbon tubes with internal diameters of 1 5 nm and a regular pore structure. MCM-41 is one member of a new family of highly uniform mesoporous aluminosilicates produced by Mobil. The pore size of MCM-41 can be accurately controlled within the range 1.5-I.0 nm. The adsorption of argon in a buckytube and the adsorption of nitrogen in two different MCM-41 pores are studied at 77 K. Both fluids are modeled as Lennard-Jones spheres. and an averaged fluid-wall potential, dependent only on the distance of the adsorbed molecule from the center of the tube or pore is used. Isotherms and isosteric heats are calculated. Layering transitions and a hysteresis loop are observed for the buckytube and good agreement is found between simulated and experimental isotherms for the MCM-41 systems.

Equilibrium electrodeformation of a spheroidal vesicle in an ac electric field

NASA Astrophysics Data System (ADS)

Nganguia, H.; Young, Y.-N.

2013-11-01

In this work, we develop a theoretical model to explain the equilibrium spheroidal deformation of a giant unilamellar vesicle (GUV) under an alternating (ac) electric field. Suspended in a leaky dielectric fluid, the vesicle membrane is modeled as a thin capacitive spheroidal shell. The equilibrium vesicle shape results from the balance between mechanical forces from the viscous fluid, the restoring elastic membrane forces, and the externally imposed electric forces. Our spheroidal model predicts a deformation-dependent transmembrane potential, and is able to capture large deformation of a vesicle under an electric field. A detailed comparison against both experiments and small-deformation (quasispherical) theory showed that the spheroidal model gives better agreement with experiments in terms of the dependence on fluid conductivity ratio, permittivity ratio, vesicle size, electric field strength, and frequency. The spheroidal model also allows for an asymptotic analysis on the crossover frequency where the equilibrium vesicle shape crosses over between prolate and oblate shapes. Comparisons show that the spheroidal model gives better agreement with experimental observations.

Simultaneous voltammetric determination of prednisone and prednisolone in human body fluids.

PubMed

Goyal, Rajendra N; Bishnoi, Sunita

2009-08-15

A sensitive, rapid and reliable electrochemical method based on voltammetry at single wall carbon nanotube (SWNT) modified edge plane pyrolytic graphite electrode (EPPGE) is proposed for the simultaneous determination of prednisolone and prednisone in human body fluids and pharmaceutical preparations. The electrochemical response of both the drugs was evaluated by osteryoung square wave voltammetry (OSWV) in phosphate buffer medium of pH 7.2. The modified electrode exhibited good electrocatalytic properties towards prednisone and prednisolone reduction with a peak potential of approximately -1230 and approximately -1332 mV respectively. The concentration versus peak current plots were linear for both the analytes in the range 0.01-100 microM and the detection limit (3 sigma/slope) observed for prednisone and prednisolone were 0.45 x 10(-8), 0.90 x 10(-8)M, respectively. The results of the quantitative estimation of prednisone and prednisolone in biological fluids were also compared with HPLC and the results were in good agreement.

Yield Hardening of Electrorheological Fluids in Channel Flow

NASA Astrophysics Data System (ADS)

Helal, Ahmed; Qian, Bian; McKinley, Gareth H.; Hosoi, A. E.

2016-06-01

Electrorheological fluids offer potential for developing rapidly actuated hydraulic devices where shear forces or pressure-driven flow are present. In this study, the Bingham yield stress of electrorheological fluids with different particle volume fractions is investigated experimentally in wall-driven and pressure-driven flow modes using measurements in a parallel-plate rheometer and a microfluidic channel, respectively. A modified Krieger-Dougherty model can be used to describe the effects of the particle volume fraction on the yield stress and is in good agreement with the viscometric data. However, significant yield hardening in pressure-driven channel flow is observed and attributed to an increase and eventual saturation of the particle volume fraction in the channel. A phenomenological physical model linking the densification and consequent microstructure to the ratio of the particle aggregation time scale compared to the convective time scale is presented and used to predict the enhancement in yield stress in channel flow, enabling us to reconcile discrepancies in the literature between wall-driven and pressure-driven flows.

Characterization of naturally developing small intestinal bacterial overgrowth in 16 German shepherd dogs.

PubMed

Willard, M D; Simpson, R B; Fossum, T W; Cohen, N D; Delles, E K; Kolp, D L; Carey, D P; Reinhart, G A

1994-04-15

Sixteen German Shepherd Dogs were found, via quantitative microbial culture of intestinal fluid samples, to have small intestinal bacterial overgrowth (IBO) over an 11-month period. All dogs were deficient in serum IgA. Consistent clinical signs suggestive of an alimentary tract disorder were not observed. Serum cobalamin determinations were not helpful in detecting IBO. Serum folate concentrations had variable sensitivity and specificity for detecting dogs from which we could culture > or = 1 x 10(5) bacterial/ml from intestinal fluid samples in the nonfed state. Histologic and intestinal mucosal cytologic examinations were not useful in detecting IBO. Substantial within-dog and between-dog variation was found in the numbers and species of bacteria in the intestines. The difficulty in diagnosing IBO, the variability in organisms found in individual dogs on repeated sampling, the likelihood that intestinal fluid microbial cultures failed to diagnose IBO in some dogs, and the potential of IBO to be clinically inapparent were the most important findings in this study.

Magnetic Fluids Have Ability to Decrease Amyloid Aggregation Associated with Amyloid-Related Diseases

NASA Astrophysics Data System (ADS)

Antosova, Andrea; Koneracka, Martina; Siposova, Katarina; Zavisova, Vlasta; Daxnerova, Zuzana; Vavra, Ivo; Fabian, Martin; Kopcansky, Peter; Gazova, Zuzana

2010-12-01

At least twenty human proteins can fold abnormally to form pathological deposits that are associated with several amyloid-related diseases. We have investigated the effect of four magnetic fluids (MFs)—electrostatically stabilized Fe3O4 magnetic nanoparticles (MF1) and sterically stabilized Fe3O4 magnetic nanoparticles by sodium oleate (MF2, MF3 and MF4) with adsorbed BSA (MF2) or dextran (MF4)—on amyloid aggregation of two proteins, human insulin and chicken egg lysozyme. The morphology, particle size and size distribution of the prepared magnetic fluids were characterized. We have found that MFs are able to decrease amyloid aggregation of both studied proteins and the extent of depolymerization depended on the MF properties. The most effective reduction was observed for MF4 as 90% decrease of amyloids was detected for insulin and lysozyme amyloid aggregates. Our findings indicate that MFs have potential to be used for treatment of amyloid diseases.

An investigation into dispersion upon switching between solvents within a microfluidic system using a chemically resistant integrated optical refractive index sensor.

PubMed

Parker, Richard M; Gates, James C; Wales, Dominic J; Smith, Peter G R; Grossel, Martin C

2013-02-07

A planar Bragg grating device has been developed that is capable of detecting changes in the refractive index of a wide range of fluids including solvents, acids and bases. The integration of this high precision refractive index sensor within a chemically resistant microfluidic flow system has enabled the investigation of diverse fluid interactions. By cycling between different solvents, both miscible and immiscible, within the microfluidic system it is shown that the previous solvent determines the nature of the refractive index profile across the transition in composition. This solvent dispersion effect is investigated with particular attention to the methanol-water transition, where transients in refractive index are observed that are an order of magnitude larger in amplitude than the difference between the bulk fluids. The potential complications of such phenomenon are discussed together with an example of a device that exploits this effect for the unambiguous composition measurement of a binary solvent system.

Labyrinth and cerebral-spinal fluid pressure changes in guinea pigs and monkeys during simulated zero G

NASA Technical Reports Server (NTRS)

Parker, D. E.

1977-01-01

This study was undertaken to explore the hypothesis that shifts of body fluids from the legs and torso toward the head contribute to the motion sickness experienced by astronauts and cosmonauts. The shifts in body fluids observed during zero-G exposure were simulated by elevating guinea pigs' and monkeys' torsos and hindquarters. Cerebral-spinal fluid pressure was recorded from a transducer located in a brain ventricle; labyrinth fluid pressure was recorded from a pipette cemented in a hole in a semicircular canal. An anticipated divergence in cerebral-spinal fluid pressure and labyrinth fluid pressure during torso elevation was not observed. The results of this study do not support a fluid shift mechanism of zero-G-induced motion sickness. However, a more complete test of the fluid shift mechanism would be obtained if endolymph and perilymph pressure changes were determined separately; we have been unable to perform this test to date.

Health effects of oil mists: a brief review.

PubMed

Mackerer, C R

1989-05-01

Metal cutting/grinding fluids are of three basic types: straight oil (insoluble), oil-in-water emulsions (soluble) and synthetic/semisynthetic. All contain a variety of additives to improve performance. Human exposure occurs primarily by direct skin contact with the liquid or by skin and respiratory contact after fluid misting. Dermatitis caused by primary or direct skin irritation is the most prevalent health effect of exposure to cutting fluids. Occasionally allergic dermatitis is seen which is related to the development of sensitization to one or more of the additive components. Recent studies indicate that long-term exposure to cutting fluids does not result in increased incidences of lung cancer, urinary bladder cancer, gastrointestinal cancer, or death from non-malignant respiratory diseases. Long-term exposure to certain cutting fluids, however, is believed to have resulted in certain types of skin cancer, especially scrotal cancer. It is likely that these carcinogenic responses were caused by contact with polycyclic aromatic compounds (PCA) of 3-7 rings. Modern base oils which are severely refined have very low levels of PCA, are not carcinogenic in animal bioassays, and are unlikely to be carcinogenic in man. This is not necessarily true for re-refined oils which may contain significant levels of PCA and polychlorinated biphenyls derived from comingling used cutting oils with used engine oils and transformer oils. Cutting oils, themselves, generally do not accumulate significant levels of carcinogenic PCA during use. Additives, in theory, can cause a variety of health effects either directly or through the generation of reaction products such as nitrosamines. In actual use, adverse health effects appear to be limited to occasional instances of allergic contact dermatitis. Nitrosamines are extremely carcinogenic in test animals; although no human cancer cases directly attributable to nitrosamine contamination have been observed, nitrosating agents and amines should not be combined in cutting fluid formulations. It is difficult to anticipate or predict the potential toxicity of a particular cutting fluid formulation because of the presence of variable amounts of proprietary additives which, themselves, are often complex reaction mixtures. Thus, each additive and final formulation must be evaluated on a case by case basis to appropriately assess potential health hazards.

Relationship between karstification and burial dolomitization in Permian platform carbonates (Lower Khuff - Oman)

NASA Astrophysics Data System (ADS)

Beckert, Julia; Vandeginste, Veerle; John, Cédric M.

2016-08-01

Large breccia fabrics associated with karst constitute an important structure in massive limestone successions. The dimensions and shapes of breccia structures are controlled by the initial fracture pattern of the limestone and preferential pathways of the karstifying fluids, but subsequently breccia fabrics can also govern the migration of later fluids. Therefore, breccias are highly relevant features to capture for reservoir characterisation. Outcrop analogues for Lower Khuff units in the Middle East present in the Central Oman Mountains reveal brecciated fabrics up to 10s of metres in diameter. These brecciated units are closely associated with dolomite bodies of late diagenetic origin. Based on an integrated set of data, the breccias are interpreted as collapsed karst cavities either formed by meteoric or hypogenic fluids. The exact origin of the fluids could not be constrained due to an overprint by later dolomitizing fluids. Based on the composition of the clasts and matrix in the breccias, two dolomitization events are interpreted to have affected the succession, one prior to (early diagenetic [ED] dolomite) and one after brecciation (late diagenetic [DT2] dolomite). Dolomite of shallow burial origin (ED dolomite) was only observed as clasts within breccia and is much more frequent than late diagenetic (medium to deep burial) dolomite clasts. Thus, the timing of the brecciation and collapse is assumed to postdate shallow burial early diagenetic dolomitization. Late diagenetic replacive dolomite (DT2 dolomite) forms 90% of the matrix in the breccia fabrics with the exception of a small area that was not affected by dolomitization, but is rarely present as clasts. Stable isotope measurements [δ18O: - 2.5‰ to - 6‰ VPDB and δ13C: 2.9‰ to 4.8‰ VPDB] suggest a burial origin for the late diagenetic dolomite potentially with the participation of hydrothermal fluids. The dolomitized matrix indicates a migration of late dolomitizing fluids subsequent to or postdating the collapse of the karstic cavities. Thus, early karstification processes seem to have played a big role in controlling subsequent loci of late dolomitization in the Oman Mountains, and potentially in other similar settings elsewhere.

Hard sphere perturbation theory for fluids with soft-repulsive-core potentials

NASA Astrophysics Data System (ADS)

Ben-Amotz, Dor; Stell, George

2004-03-01

The thermodynamic properties of fluids with very soft repulsive-core potentials, resembling those of some liquid metals, are predicted with unprecedented accuracy using a new first-order thermodynamic perturbation theory. This theory is an extension of Mansoori-Canfield/Rasaiah-Stell (MCRS) perturbation theory, obtained by including a configuration integral correction recently identified by Mon, who evaluated it by computer simulation. In this work we derive an analytic expression for Mon's correction in terms of the radial distribution function of the soft-core fluid, g0(r), approximated using Lado's self-consistent extension of Weeks-Chandler-Andersen (WCA) theory. Comparisons with WCA and MCRS predictions show that our new extended-MCRS theory outperforms other first-order theories when applied to fluids with very soft inverse-power potentials (n⩽6), and predicts free energies that are within 0.3kT of simulation results up to the fluid freezing point.

Non-convex dissipation potentials in multiscale non-equilibrium thermodynamics

NASA Astrophysics Data System (ADS)

Janečka, Adam; Pavelka, Michal

2018-04-01

Reformulating constitutive relation in terms of gradient dynamics (being derivative of a dissipation potential) brings additional information on stability, metastability and instability of the dynamics with respect to perturbations of the constitutive relation, called CR-stability. CR-instability is connected to the loss of convexity of the dissipation potential, which makes the Legendre-conjugate dissipation potential multivalued and causes dissipative phase transitions that are not induced by non-convexity of free energy, but by non-convexity of the dissipation potential. CR-stability of the constitutive relation with respect to perturbations is then manifested by constructing evolution equations for the perturbations in a thermodynamically sound way (CR-extension). As a result, interesting experimental observations of behavior of complex fluids under shear flow and supercritical boiling curve can be explained.

Proteoform analysis of lipocalin-type prostaglandin D-synthase from human cerebrospinal fluid by isoelectric focusing and superficially porous liquid chromatography with Fourier transform mass spectrometry.

PubMed

Zhang, Junmei; Corbett, John R; Plymire, Daniel A; Greenberg, Benjamin M; Patrie, Steven M

2014-05-01

Lipocalin-type prostaglandin D-synthase (L-PGDS) in cerebrospinal fluid contributes to the maturation and maintenance of the CNS. L-PGDS PTMs may contribute to pathobiology of different CNS diseases, but methods to monitor its proteoforms are limited. Herein, we combined off-gel IEF and superficially porous LC (SPLC) with Fourier transform MS to characterize common cerebrospinal fluid L-PGDS proteoforms. Across 3D physiochemical space (pI, hydrophobicity, and mass), 217 putative proteoforms were observed from 21 to 24 kDa and pI 5-10. Glycoprotein accurate mass information, combined with MS/MS analysis of peptides generated from 2D-fractionated proteoforms, enabled the putative assignment of 208 proteoforms with varied PTM positional occupants. Fifteen structurally related N-glycans at N29 and N56 were observed, with different N-glycan compositional variants being preferred on each amino acid. We also observed that sialic acid content was a major factor for pI shifts between L-PGDS proteoforms. Other putative PTMs characterized include a core-1 HexHexNAc-O-glycan at S7, acetylation at K16 and K138, sulfonation at S41 and T142, and dioxidation at C43 and C145. The IEF-SPLC-MS platform presented provides 30-40× improved peak capacity versus conventional 2DE and shows potential for repeatable proteoform analysis of surrogate PTM-based biomarkers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An approach to modeling coupled thermal-hydraulic-chemical processes in geothermal systems

USGS Publications Warehouse

Palguta, Jennifer; Williams, Colin F.; Ingebritsen, Steven E.; Hickman, Stephen H.; Sonnenthal, Eric

2011-01-01

Interactions between hydrothermal fluids and rock alter mineralogy, leading to the formation of secondary minerals and potentially significant physical and chemical property changes. Reactive transport simulations are essential for evaluating the coupled processes controlling the geochemical, thermal and hydrological evolution of geothermal systems. The objective of this preliminary investigation is to successfully replicate observations from a series of hydrothermal laboratory experiments [Morrow et al., 2001] using the code TOUGHREACT. The laboratory experiments carried out by Morrow et al. [2001] measure permeability reduction in fractured and intact Westerly granite due to high-temperature fluid flow through core samples. Initial permeability and temperature values used in our simulations reflect these experimental conditions and range from 6.13 × 10−20 to 1.5 × 10−17 m2 and 150 to 300 °C, respectively. The primary mineralogy of the model rock is plagioclase (40 vol.%), K-feldspar (20 vol.%), quartz (30 vol.%), and biotite (10 vol.%). The simulations are constrained by the requirement that permeability, relative mineral abundances, and fluid chemistry agree with experimental observations. In the models, the granite core samples are represented as one-dimensional reaction domains. We find that the mineral abundances, solute concentrations, and permeability evolutions predicted by the models are consistent with those observed in the experiments carried out by Morrow et al. [2001] only if the mineral reactive surface areas decrease with increasing clay mineral abundance. This modeling approach suggests the importance of explicitly incorporating changing mineral surface areas into reactive transport models.

Regional fluid flow as a factor in the thermal history of the Illinois basin: Constraints from fluid inclusions and the maturity of Pennsylvanian coals

USGS Publications Warehouse

Rowan, E.L.; Goldhaber, M.B.; Hatch, J.R.

2002-01-01

Vitrinite reflectance measurements on Pennsylvanian coals in the Illinois basin indicate significantly higher thermal maturity than can be explained by present-day burial depths. An interval of additional sedimentary section, now removed by erosion, has been suggested to account for the discrepancy. Although burial could indeed account for the observed maturity levels of organic matter, fluid-inclusion temperatures provide a stringent additional constraint. In this article, we combine measurements of coal maturity with fluid-inclusion temperatures from three sites to constrain the basin's thermal and burial history: the Fluorspar district at the Illinois basin's southern margin, the Upper Mississippi Valley zinc district at the basin's northern margin, and a north-central location. Two-dimensional numerical modeling of a north-south cross section through the basin tests scenarios both with and without regional fluid flow. Vitrinite reflectance values can be matched assuming burial by 1.8-2.8 km of southward-thickening additional, post-Pennsylvanian sedimentary section. In the central and northern Illinois basin, however, these burial depths and temperatures are not sufficient to account for the fluid-inclusion data. To account for both parameters with burial alone does not appear feasible. In contrast, our best hypothesis assumes a wedge of post-Pennsylvanian sediment-thickening southward to about 1.2 km and a brief period of magmatism in the Fluorspar district. Significant advective heat redistribution by northward regional fluid flow accounts for fluid-inclusion temperatures and coal maturities throughout the basin. The modeling results demonstrate the potential contribution of advective heat transport to the thermal history of the Illinois basin.

Contributions of fluid convection and electrical migration to transport in cartilage: relevance to loading.

PubMed

Garcia, A M; Frank, E H; Grimshaw, P E; Grodzinsky, A J

1996-09-15

We have studied the contributions of diffusion, fluid flow and electrical migration to molecular transport through adult articular cartilage explants using neutral and charged solutes that were either radiolabeled (3H2O, [35S]sulfate, [3H]thymidine, [3H]raffinose, and a synthetic matrix metalloproteinase inhibitor) or fluorescently tagged (NSPA and Lissamine-dextran). In order to induce fluid flow within the cartilage matrix without mechanical deformation, electric current densities were applied across cartilage disks. These currents produced electroosmotic fluid velocities of 1-2 microns/s, magnitudes that have been reported to exist during joint loading in vivo. This fluid convection enhanced neutral solute flux relative to passive diffusion alone by a factor that increased with the size of the solute. While the enhancement factor for 3H2O was 2.3-fold, that for [3H]raffinose (594 Da) and similar sized neutral solutes was 10-fold, suggesting that the effect of fluid flow is important even for small solutes. The largest enhancement (25-fold) was seen for the neutral 10-kDa Lissamine-dextran, confirming that fluid convection is most important for large solutes. We also studied the electrophoretic contribution to solute flux, which is relevant to the presence of intratissue streaming potentials induced during loading in vivo. Using the negatively charged [35S]sulfate ion with a range of current densities, as much as a 10-fold enhancement in flux was observed. Values for the intrinsic transport properties of the solutes (e.g., diffusivity, electrical mobility, hydrodynamic hindrance factor) can be obtained from the data.

Wave-induced fluid flow in random porous media: Attenuation and dispersion of elastic waves

NASA Astrophysics Data System (ADS)

Müller, Tobias M.; Gurevich, Boris

2005-05-01

A detailed analysis of the relationship between elastic waves in inhomogeneous, porous media and the effect of wave-induced fluid flow is presented. Based on the results of the poroelastic first-order statistical smoothing approximation applied to Biot's equations of poroelasticity, a model for elastic wave attenuation and dispersion due to wave-induced fluid flow in 3-D randomly inhomogeneous poroelastic media is developed. Attenuation and dispersion depend on linear combinations of the spatial correlations of the fluctuating poroelastic parameters. The observed frequency dependence is typical for a relaxation phenomenon. Further, the analytic properties of attenuation and dispersion are analyzed. It is shown that the low-frequency asymptote of the attenuation coefficient of a plane compressional wave is proportional to the square of frequency. At high frequencies the attenuation coefficient becomes proportional to the square root of frequency. A comparison with the 1-D theory shows that attenuation is of the same order but slightly larger in 3-D random media. Several modeling choices of the approach including the effect of cross correlations between fluid and solid phase properties are demonstrated. The potential application of the results to real porous materials is discussed. .

Dynamics of Small Inertia-Free Spheroidal Particles in a Turbulent Channel Flow

NASA Astrophysics Data System (ADS)

Challabotla, Niranjan Reddy; Zhao, Lihao; Andersson, Helge I.; Department of Energy; Process Engineering Team

2015-11-01

The study of small non-spherical particles suspended in turbulent fluid flows is of interest in view of the potential applications in industry and the environment. In the present work, we investigated the dynamics of inertia-free spheroidal particles suspended in fully-developed turbulent channel flow at Re τ = 180 by using the direct numerical simulations (DNS) for the Eulerian fluid phase coupled with the Lagrangian point-particle tracking. We considered inertia-free spheroidal particles with a wide range of aspect ratios from 0.01 to 50, i.e. from flat disks to long rods. Although the spheroids passively translate along with the fluid, the particle orientation and rotation strongly depend on the particle shape. The flattest disks were preferentially aligned with their symmetry axis normal to the wall, whereas the longest rods aligned parallel to the wall. Strong mean rotational spin was observed for spherical particles and this has been damped with increasing asphericity both for rod-like and disk-like spheroids. The anisotropic mean and fluctuating fluid vorticity resulted in particle spin anisotropies which exhibited a complex dependence on the particle asphericty. The Research Council of Norway, Notur and COST Action FP1005 are gratefully acknowledged.

Effect of attractive interactions on the water-like anomalies of a core-softened model potential.

PubMed

Pant, Shashank; Gera, Tarun; Choudhury, Niharendu

2013-12-28

It is now well established that water-like anomalies can be reproduced by a spherically symmetric potential with two length scales, popularly known as core-softened potential. In the present study we aim to investigate the effect of attractive interactions among the particles in a model fluid interacting with core-softened potential on the existence and location of various water-like anomalies in the temperature-pressure plane. We employ extensive molecular dynamic simulations to study anomalous nature of various order parameters and properties under isothermal compression. Order map analyses have also been done for all the potentials. We observe that all the systems with varying depth of attractive wells show structural, dynamic, and thermodynamic anomalies. As many of the previous studies involving model water and a class of core softened potentials have concluded that the structural anomaly region encloses the diffusion anomaly region, which in turn, encloses the density anomaly region, the same pattern has also been observed in the present study for the systems with less depth of attractive well. For the systems with deeper attractive well, we observe that the diffusion anomaly region shifts toward higher densities and is not always enclosed by the structural anomaly region. Also, density anomaly region is not completely enclosed by diffusion anomaly region in this case.

Microbial Community Shifts due to Hydrofracking: Observations from Field-Scale Observations and Laboratory-Scale Incubations

NASA Astrophysics Data System (ADS)

Mouser, P. J.; Ansari, M.; Hartsock, A.; Lui, S.; Lenhart, J.

2012-12-01

The use of fluids containing chemicals and variable water sources during the hydrofracking of unconventional shale is the source of considerable controversy due to perceived risks from altered subsurface biogeochemistry and the potential for contaminating potable water supplies. Rapid shifts in subsurface biogeochemistry are often driven by available macronutrients combined with the abundance and metabolic condition of the subsurface microbiota. While the depth that fracturing occurs in the Marcellus formation is reasonably deep to pose little risk to groundwater supplies, no published studies have systematically characterized the indigenous microbial population and how this community is altered through variable fluid management practices (e.g., chemical composition, source water makeup). In addition, limited information is available on how shallower microbial communities and geochemical conditions might be affected through the accidental release of these fluids to groundwater aquifers. Our measurements indicate field-applied and laboratory-generated fracking fluids contain levels of organic carbon greater than 300 mg/l and nitrogen concentrations greater than 80 mg/l that may differentially stimulate microbial growth in subsurface formations. In contrast to certain inorganic constituents (e.g., chloride) which increase in concentration through the flowback period; dissolved organic carbon levels decrease with time after the fracturing process through multiple attenuation processes (dilution, sorption, microbial utilization). Pyrosequencing data of the 16S rRNA gene indicate a shift from a more diverse source water microbial community to a less diverse community typical of a brine formation as time after fracturing increases. The introduction of varying percentages of a laboratory-generated fracking fluid to microcosm bottles containing groundwater and aquifer media stimulated biogeochemical changes similar to the introduction of landfill leachate, another wastewater containing elevated carbon, nitrogen, and complex organic constituents (e.g., decreased redox conditions, stepwise utilization of available terminal electron acceptors, enriched Fe(II) and sulfide concentrations). These research findings are important for understanding how fluids used during shale energy development may alter in situ microbial communities and provide insight into processes that attenuate the migration of these fluids in shallow aquifers and deep shale formations.

Frequency spectrum of transepithelial potential difference reveals transport-related oscillations.

PubMed

Montalbetti, Nicolás; Fischbarg, Jorge

2009-09-16

How epithelia transport fluid is a fundamental issue that is unresolved. Explanations offered include molecular engines, local transcellular osmosis, local paracellular osmosis, and paracellular fluid transport. On the basis of experimental and theoretical work done on corneal endothelium, a fluid transporting epithelium, we suggest electroosmotic coupling at the level of the intercellular junctions driven by the transendothelial electrical potential difference as an explanation of paracellular fluid transport. We collect frequency spectra of that potential difference in real-time. For what we believe is the first time for any epithelium, we report that, unexpectedly, the potential difference displays oscillations at many characteristic frequencies. We also show that on both stimulating cell activity and inhibiting ion transport mechanisms, there are corresponding changes in the oscillations amplitudes that mirror changes known previously in rates of fluid transport. We believe these findings provide a novel tool to study the kinetics of electrogenic elements such as channels and transporters, which from this evidence would give rise to current oscillations with characteristic periods going from 150 ms to 8 s.

Removal of common organic solvents from aqueous waste streams via supercritical C02 extraction: a potential green approach to sustainable waste management in the pharmaceutical industry.

PubMed

Leazer, Johnnie L; Gant, Sean; Houck, Anthony; Leonard, William; Welch, Christopher J

2009-03-15

Supercritical CO2 extraction of aqueous streams is a convenient and effective method to remove commonly used solvents of varying polarities from aqueous waste streams. The resulting aqueous layers can potentially be sewered; whereas the organic layer can be recovered for potential reuse. Supercritical fluid extraction (SFE) is a technology that is increasingly being used in commercial processes (1). Supercritical fluids are well suited for extraction of a variety of media, including solids, natural products, and liquid products. Many supercritical fluids have low critical temperatures, allowing for extractions to be done at modestly low temperatures, thus avoiding any potential thermal decomposition of the solutes under study (2). Furthermore, the CO2 solvent strength is easily tuned by adjusting the density of the supercritical fluid (The density is proportional to the pressure of the extraction process). Since many supercritical fluids are gases at ambient temperature, the extract can be concentrated by simply venting the reaction mixture to a cyclone collection vessel, using appropriate safety protocols.

Fluid transition layer between rigid solute and liquid solvent: is there depletion or enrichment?

PubMed

Djikaev, Yuri S; Ruckenstein, Eli

2016-03-21

The fluid layer between solute and liquid solvent is studied by combining the density functional theory with the probabilistic hydrogen bond model. This combination allows one to obtain the equilibrium distribution of fluid molecules, taking into account the hydrogen bond contribution to the external potential whereto they are subjected near the solute. One can find the effective width of the fluid solvent-solute transition layer and fluid average density in that layer, and determine their dependence on temperature, solvent-solute affinity, vicinal hydrogen bond (hb) energy alteration ratio, and solute radius. Numerical calculations are performed for the solvation of a plate and spherical solutes of four different radii in two model solvents (associated liquid and non-associated one) in the temperature range from 293 K to 333 K for various solvent-solute affinities and hydrogen bond energy alteration ratios. The predictions of our model for the effective width and average density of the transition layer are consistent with experiments and simulations. The small-to-large crossover lengthscale for hydrophobic hydration is expected to be about 3-5 nm. Remarkably, characterizing the transition layer with the average density, one can observe that for small hydrophobes, the transition layer becomes enriched with rather than depleted of fluid when the solvent-solute affinity and hb-energy alteration ratio become large enough. The boundary values of solvent-solute affinity and hb-energy alteration ratio, needed for the "depletion-to-enrichment" crossover (in the smoothed density sense), are predicted to decrease with increasing temperature.

cAMP Stimulates Transepithelial Short-Circuit Current and Fluid Transport Across Porcine Ciliary Epithelium.

PubMed

Cheng, Angela King-Wah; Civan, Mortimer M; To, Chi-Ho; Do, Chi-Wai

2016-12-01

To investigate the effects of cAMP on transepithelial electrical parameters and fluid transport across porcine ciliary epithelium. Transepithelial electrical parameters were determined by mounting freshly isolated porcine ciliary epithelium in a modified Ussing chamber. Similarly, fluid movement across intact ciliary body was measured with a custom-made fluid flow chamber. Addition of 1, 10, and 100 μM 8-Br-cAMP (cAMP) to the aqueous side (nonpigmented ciliary epithelium, NPE) induced a sustained increase in short-circuit current (Isc). Addition of niflumic acid (NFA) to the aqueous surface effectively blocked the cAMP-induced Isc stimulation. The administration of cAMP to the stromal side (pigmented ciliary epithelium, PE) triggered a significant stimulation of Isc only at 100 μM. No additive effect was observed with bilateral application of cAMP. Likewise, forskolin caused a significant stimulation of Isc when applied to the aqueous side. Concomitantly, cAMP and forskolin increased fluid transport across porcine ciliary epithelium, and this stimulation was effectively inhibited by aqueous NFA. Depleting Cl- in the bathing solution abolished the baseline Isc and inhibited the subsequent stimulation by cAMP. Pretreatment with protein kinase A (PKA) blockers (H89/KT5720) significantly inhibited the cAMP- and forskolin-induced Isc responses. Our results suggest that cAMP triggers a sustained stimulation of Cl- and fluid transport across porcine ciliary epithelium; Cl- channels in the NPE cells are potentially a cellular site for this PKA-sensitive cAMP-mediated response.

Vapor-liquid phase behavior of a size-asymmetric model of ionic fluids confined in a disordered matrix: The collective-variables-based approach

NASA Astrophysics Data System (ADS)

Patsahan, O. V.; Patsahan, T. M.; Holovko, M. F.

2018-02-01

We develop a theory based on the method of collective variables to study the vapor-liquid equilibrium of asymmetric ionic fluids confined in a disordered porous matrix. The approach allows us to formulate the perturbation theory using an extension of the scaled particle theory for a description of a reference system presented as a two-component hard-sphere fluid confined in a hard-sphere matrix. Treating an ionic fluid as a size- and charge-asymmetric primitive model (PM) we derive an explicit expression for the relevant chemical potential of a confined ionic system which takes into account the third-order correlations between ions. Using this expression, the phase diagrams for a size-asymmetric PM are calculated for different matrix porosities as well as for different sizes of matrix and fluid particles. It is observed that general trends of the coexistence curves with the matrix porosity are similar to those of simple fluids under disordered confinement, i.e., the coexistence region gets narrower with a decrease of porosity and, simultaneously, the reduced critical temperature Tc* and the critical density ρi,c * become lower. At the same time, our results suggest that an increase in size asymmetry of oppositely charged ions considerably affects the vapor-liquid diagrams leading to a faster decrease of Tc* and ρi,c * and even to a disappearance of the phase transition, especially for the case of small matrix particles.

Analogy between fluid cavitation and fracture mechanics

NASA Astrophysics Data System (ADS)

Hendricks, R. C.; Mullen, R. L.; Braun, M. J.

When the stresses imposed on a fluid are sufficiently large, rupture or cavitation can occur. Such conditions can exist in many two-phase flow applications, such as the choked flows, which can occur in seals and bearings. Nonspherical bubbles with large aspect ratios have been observed in fluids under rapid acceleration and high shear fields. These bubbles are geometrically similar to fracture surface patterns (Griffith crack model) existing in solids. Analogies between crack growth in solid and fluid cavitation are proposed and supported by analysis and observation (photographs). Healing phenomena (void condensation), well accepted in fluid mechanics, have been observed in some polymers and hypothesized in solid mechanics. By drawing on the strengths of the theories of solid mechanics and cavitation, a more complete unified theory can be developed.

Analogy between fluid cavitation and fracture mechanics

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Mullen, R. L.; Braun, M. J.

1983-01-01

When the stresses imposed on a fluid are sufficiently large, rupture or cavitation can occur. Such conditions can exist in many two-phase flow applications, such as the choked flows, which can occur in seals and bearings. Nonspherical bubbles with large aspect ratios have been observed in fluids under rapid acceleration and high shear fields. These bubbles are geometrically similar to fracture surface patterns (Griffith crack model) existing in solids. Analogies between crack growth in solid and fluid cavitation are proposed and supported by analysis and observation (photographs). Healing phenomena (void condensation), well accepted in fluid mechanics, have been observed in some polymers and hypothesized in solid mechanics. By drawing on the strengths of the theories of solid mechanics and cavitation, a more complete unified theory can be developed.

Concise Review: Amniotic Fluid Stem Cells: The Known, the Unknown, and Potential Regenerative Medicine Applications.

PubMed

Loukogeorgakis, Stavros P; De Coppi, Paolo

2017-07-01

The amniotic fluid has been identified as an untapped source of cells with broad potential, which possess immunomodulatory properties and do not have the ethical and legal limitations of embryonic stem cells. CD117(c-Kit)+ cells selected from amniotic fluid have been shown to differentiate into cell lineages representing all three embryonic germ layers without generating tumors, making them ideal candidates for regenerative medicine applications. Moreover, their ability to engraft in injured organs and modulate immune and repair responses of host tissues, suggest that transplantation of such cells may be useful for the treatment of various degenerative and inflammatory diseases. Although significant questions remain regarding the origin, heterogeneous phenotype, and expansion potential of amniotic fluid stem cells, evidence to date supports their potential role as a valuable stem cell source for the field of regenerative medicine. Stem Cells 2017;35:1663-1673. © 2016 AlphaMed Press.

An inkjet-printed electrowetting valve for paper-fluidic sensors.

PubMed

Koo, Charmaine K W; He, Fei; Nugen, Sam R

2013-09-07

Paper-fluidic devices have become an emerging trend for micro total analysis systems (microTAS) in the bioengineering field due to their ability to maintain the rapid, sensitive and specific attributes of microfluidic devices. Subsequently, paper-fluidic devices are also more portable, have a lower production cost and are easier to use. However, one of the obstacles in developing paper fluidic devices is the limited ability to control the rate of fluid flow during an assay. In our project, we use electrowetting on dielectrics where a dielectric, which is normally hydrophobic, is polarized and becomes hydrophilic. We have fabricated paper-fluidic devices by inkjet printing and spraying conductive hydrophobic electrodes/valves in conjunction with conductive hydrophilic electrodes which are able to stop the fluid front of phosphate buffered saline (PBS). The hydrophobic valves were then actuated by an applied potential which altered the fluorinated monolayer on the electrode. As the applied potential between the electrodes was increased, the amount of time for the fluid front to pass the valve decreased because the monolayer was altered faster. However, we did not observe significant differences in time as we increased the distance between the electrodes. The valves were also incorporated in a lateral flow assay where the device was used to detect Saccharomyces cerevisiae rRNA sequences. With the ability to control the fluid flow in a paper-fluidic device, more complex and intricate assays can be developed, which not only can be applied in the biomedical, food and environmental fields, but also can be used in low resource settings for the detection of diseases.

Acute exposure to space flight results in evidence of reduced lymph Transport, tissue fluid Shifts, and immune alterations in the rat gastrointestinal system.

PubMed

Cromer, W E; Zawieja, D C

2018-05-01

Space flight causes a number of alterations in physiological systems, changes in the immunological status of subjects, and altered interactions of the host to environmental stimuli. We studied the effect of space flight on the lymphatic system of the gastrointestinal tract which is responsible for lipid transport and immune surveillance which includes the host interaction with the gut microbiome. We found that there were signs of tissue damage present in the space flown animals that was lacking in ground controls (epithelial damage, crypt morphological changes, etc.). Additionally, morphology of the lymphatic vessels in the tissue suggested a collapsed state at time of harvest and there was a profound change in the retention of lipid in the villi of the ileum. Contrary to our assumptions there was a reduction in tissue fluid volume likely associated with other fluid shifts described. The reduction of tissue fluid volume in the colon and ileum is a likely contributing factor to the state of the lymphatic vessels and lipid transport issues observed. There were also associated changes in the number of MHC-II + immune cells in the colon tissue, which along with reduced lymphatic competence would favor immune dysfunction in the tissue. These findings help expand our understanding of the effects of space flight on various organ systems. It also points out potential issues that have not been closely examined and have to potential for the need of countermeasure development. Copyright © 2018 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

Composition of chitosan-hydroxyapatite-collagen composite scaffold evaluation after simulated body fluid immersion as reconstruction material

NASA Astrophysics Data System (ADS)

Verisqa, F.; Triaminingsih, S.; Corputty, J. E. M.

2017-08-01

Hydroxyapatite (HA) formation is one of the most important aspects of bone regeneration. Because domestically made chitosan-hydroxyapatite-collagen composite scaffolding from crab shell and bovine bone and tendon has potential as a maxillofacial reconstruction material, the material’s HA-forming ability requires evaluation. The aim of this research is to investigate chitosan-hydroxyapatite-collagen composite scaffold’s potential as a maxillofacial reconstruction material by observing the scaffold’s compositional changes. Scaffold specimens were immersed in 37°C simulated body fluid (SBF) for periods of 2, 4, 6, and 8 days. Scaffold composition was then evaluated by using energy dispersive spectroscopy (EDS). The calcium (Ca) and phosphorus (P) percentages of the scaffold were found to increase following SBF immersion. The high Ca/P ratio (3.82) on the scaffold indicated HA formation. Ion exchange played a significant role in the increased percentages of Ca and P, which led to new HA layer formation. The scaffold’s HA acted as a nucleation site of Ca and P from the SBF, with collagen and chitosan as the scaffold’s matrix. Chitosan-hydroxyapatite-collagen composite scaffold shows potential as a maxillofacial reconstruction material, since its composition favors HA formation.

Intravenous Solutions for Exploration Missions

NASA Technical Reports Server (NTRS)

Miller, Fletcher J.; Niederhaus, Charles; Barlow, Karen; Griffin, DeVon

2007-01-01

This paper describes the intravenous (IV) fluids requirements being developed for medical care during NASA s future exploration class missions. Previous research on IV solution generation and mixing in space is summarized. The current exploration baseline mission profiles are introduced, potential medical conditions described and evaluated for fluidic needs, and operational issues assessed. We briefly introduce potential methods for generating IV fluids in microgravity. Conclusions on the recommended fluid volume requirements are presented.

The Numerical Simulation of Time Dependent Flow Structures Over a Natural Gravel Surface.

NASA Astrophysics Data System (ADS)

Hardy, R. J.; Lane, S. N.; Ferguson, R. I.; Parsons, D. R.

2004-05-01

Research undertaken over the last few years has demonstrated the importance of the structure of gravel river beds for understanding the interaction between fluid flow and sediment transport processes. This includes the observation of periodic high-speed fluid wedges interconnected by low-speed flow regions. Our understanding of these flows has been enhanced significantly through a series of laboratory experiments and supported by field observations. However, the potential of high resolution three dimensional Computational Fluid Dynamics (CFD) modeling has yet to be fully developed. This is largely the result of the problems of designing numerically stable meshes for use with complex bed topographies and that Reynolds averaged turbulence schemes are applied. This paper develops two novel techniques for dealing with these issues. The first is the development and validation of a method for representing the complex surface topography of gravel-bed rivers in high resolution three-dimensional computational fluid dynamic models. This is based upon a porosity treatment with a regular structured grid and the application of a porosity modification to the mass conservation equation in which: fully blocked cells are assigned a porosity of zero; fully unblocked cells are assigned a porosity of one; and partly blocked cells are assigned a porosity of between 0 and 1, according to the percentage of the cell volume that is blocked. The second is the application of Large Eddy Simulation (LES) which enables time dependent flow structures to be numerically predicted over the complex bed topographies. The regular structured grid with the embedded porosity algorithm maintains a constant grid cell size throughout the domain implying a constant filter scale for the LES simulation. This enables the prediction of coherent structures, repetitive quasi-cyclic large-scale turbulent motions, over the gravel surface which are of a similar magnitude and frequency to those previously observed in both flume and field studies. These structures are formed by topographic forcing within the domain and are scaled with the flow depth. Finally, this provides the numerical framework for the prediction of sediment transport within a time dependent framework. The turbulent motions make a significant contribution to the turbulent shear stress and the pressure fluctuations which significantly affect the forces acting on the bed and potentially control sediment motion.

Ionic fluids with r-6 pair interactions have power-law electrostatic screening

NASA Astrophysics Data System (ADS)

Kjellander, Roland; Forsberg, Björn

2005-06-01

The decay behaviour of radial distribution functions for large distances r is investigated for classical Coulomb fluids where the ions interact with an r-6 potential (e.g. a dispersion interaction) in addition to the Coulombic and the short-range repulsive potentials (e.g. a hard core). The pair distributions and the density-density (NN), charge-density (QN) and charge-charge (QQ) correlation functions are investigated analytically and by Monte Carlo simulations. It is found that the NN correlation function ultimately decays like r-6 for large r, just as it does for fluids of electroneutral particles interacting with an r-6 potential. The prefactor is proportional to the squared compressibility in both cases. The QN correlations decay in general like r-8 and the QQ correlations like r-10 in the ionic fluid. The average charge density around an ion decays generally like r-8 and the average electrostatic potential like r-6. This behaviour is in stark contrast to the decay behaviour for classical Coulomb fluids in the absence of the r-6 potential, where all these functions decay exponentially for large r. The power-law decays are, however, the same as for quantum Coulomb fluids. This indicates that the inclusion of the dispersion interaction as an effective r-6 interaction potential in classical systems yields the same decay behaviour for the pair correlations as in quantum ionic systems. An exceptional case is the completely symmetric binary electrolyte for which only the NN correlation has a power-law decay but not the QQ correlations. These features are shown by an analysis of the bridge function.

An accurate density functional theory for the vapor-liquid interface of associating chain molecules based on the statistical associating fluid theory for potentials of variable range

NASA Astrophysics Data System (ADS)

Gloor, Guy J.; Jackson, George; Blas, Felipe J.; del Río, Elvira Martín; de Miguel, Enrique

2004-12-01

A Helmholtz free energy density functional is developed to describe the vapor-liquid interface of associating chain molecules. The functional is based on the statistical associating fluid theory with attractive potentials of variable range (SAFT-VR) for the homogenous fluid [A. Gil-Villegas, A. Galindo, P. J. Whitehead, S. J. Mills, G. Jackson, and A. N. Burgess, J. Chem. Phys. 106, 4168 (1997)]. A standard perturbative density functional theory (DFT) is constructed by partitioning the free energy density into a reference term (which incorporates all of the short-range interactions, and is treated locally) and an attractive perturbation (which incorporates the long-range dispersion interactions). In our previous work [F. J. Blas, E. Martín del Río, E. de Miguel, and G. Jackson, Mol. Phys. 99, 1851 (2001); G. J. Gloor, F. J. Blas, E. Martín del Río, E. de Miguel, and G. Jackson, Fluid Phase Equil. 194, 521 (2002)] we used a mean-field version of the theory (SAFT-HS) in which the pair correlations were neglected in the attractive term. This provides only a qualitative description of the vapor-liquid interface, due to the inadequate mean-field treatment of the vapor-liquid equilibria. Two different approaches are used to include the correlations in the attractive term: in the first, the free energy of the homogeneous fluid is partitioned such that the effect of correlations are incorporated in the local reference term; in the second, a density averaged correlation function is incorporated into the perturbative term in a similar way to that proposed by Toxvaerd [S. Toxvaerd, J. Chem. Phys. 64, 2863 (1976)]. The latter is found to provide the most accurate description of the vapor-liquid surface tension on comparison with new simulation data for a square-well fluid of variable range. The SAFT-VR DFT is used to examine the effect of molecular chain length and association on the surface tension. Different association schemes (dimerization, straight and branched chain formation, and network structures) are examined separately. The surface tension of the associating fluid is found to be bounded between the nonassociating and fully associated limits (both of which correspond to equivalent nonassociating systems). The temperature dependence of the surface tension is found to depend strongly on the balance between the strength and range of the association, and on the particular association scheme. In the case of a system with a strong but very localized association interaction, the surface tension exhibits the characteristic "s shaped" behavior with temperature observed in fluids such as water and alkanols. The various types of curves observed in real substances can be reproduced by the theory. It is very gratifying that a DFT based on SAFT-VR free energy can provide an accurate quantitative description of the surface tension of both the model and experimental systems.

Reactive transport modeling to study changes in water chemistry induced by CO2 injection at the Frio-I Brine Pilot

USGS Publications Warehouse

Xu, T.; Kharaka, Y.K.; Doughty, C.; Freifeld, B.M.; Daley, T.M.

2010-01-01

To demonstrate the potential for geologic storage of CO2 in saline aquifers, the Frio-I Brine Pilot was conducted, during which 1600 tons of CO2 were injected into a high-permeability sandstone and the resulting subsurface plume of CO2 was monitored using a variety of hydrogeological, geophysical, and geochemical techniques. Fluid samples were obtained before CO2 injection for baseline geochemical characterization, during the CO2 injection to track its breakthrough at a nearby observation well, and after injection to investigate changes in fluid composition and potential leakage into an overlying zone. Following CO2 breakthrough at the observation well, brine samples showed sharp drops in pH, pronounced increases in HCO3- and aqueous Fe, and significant shifts in the isotopic compositions of H2O and dissolved inorganic carbon. Based on a calibrated 1-D radial flow model, reactive transport modeling was performed for the Frio-I Brine Pilot. A simple kinetic model of Fe release from the solid to aqueous phase was developed, which can reproduce the observed increases in aqueous Fe concentration. Brine samples collected after half a year had lower Fe concentrations due to carbonate precipitation, and this trend can be also captured by our modeling. The paper provides a method for estimating potential mobile Fe inventory, and its bounding concentration in the storage formation from limited observation data. Long-term simulations show that the CO2 plume gradually spreads outward due to capillary forces, and the gas saturation gradually decreases due to its dissolution and precipitation of carbonates. The gas phase is predicted to disappear after 500 years. Elevated aqueous CO2 concentrations remain for a longer time, but eventually decrease due to carbonate precipitation. For the Frio-I Brine Pilot, all injected CO2 could ultimately be sequestered as carbonate minerals. ?? 2010 Elsevier B.V.

Geo Techno Park potential at Arjuno-Welirang Volcano hosted geothermal area, Batu, East Java, Indonesia (Multi geophysical approach)

NASA Astrophysics Data System (ADS)

Maryanto, Sukir

2017-11-01

Arjuno Welirang Volcano Geothermal (AWVG) is located around Arjuno-Welirang Volcano in Malang, East Java, about 100 km southwest of Surabaya, the capital city of East Java province, and is still an undeveloped area of the geothermal field. The occurrence of solfatara and fumaroles with magmatic gasses indicated the existence of a volcanic geothermal system in the subsurface. A few hot springs are found in the Arjuno-Welirang volcanic complex, such as Padusan hot spring, Songgoriti hot spring, Kasinan hot spring, and Cangar hot spring. Multi geophysical observations in AWVG complex was carried out in order to explore the subsurface structure in supporting the plan of Geo Techno Park at the location. Gravity, Magnetic, Microearthquake, and Electrical Resistivity Tomography (ERT) methods were used to investigate the major and minor active faulting zones whether hot springs circulation occurs in these zones. The gravity methods allowed us to locate the subsurface structure and to evaluate their geometrical relationship base on density anomaly. Magnetic methods allow us to discriminate conductive areas which could correspond to an increase in thermal fluid circulation in the investigated sites. Micro-earthquakes using particle motion analysis to locate the focal depth related with hydrothermal activity and electrical resistivity tomography survey offers methods to locate more detail subsurface structure and geothermal fluids near the surface by identifying areas affected by the geothermal fluid. The magnetic and gravity anomaly indicates the subsurface structure of AWVG is composed of basalt rock, sulfide minerals, sandstone, and volcanic rock with high minor active fault structure as a medium for fluid circulation. While using micro-earthquake data in AWVG shown shallow focal depth range approximate 60 meters which indicates shallow hydrothermal circulation in AWVG. The geothermal fluid circulation zones along the fault structure resulted in some hot springs in a central and north-western part of AWVG detected by the Electrical Resistivity Tomography, appear to be well correlated with corresponding features derived from the gravity, magnetic, and micro-earthquake survey. We just ongoing process to develop Arjuno Welirang Volcano & Geothermal Research Center (AWVGRC) located at Universitas Brawijaya Agro Techno Park, Cangar in the flank of Arjuno Welirang volcano complex. Due to our initial observations, AWVG has a great potential for a pilot project of an educational geo technopark development area.

Physiological and behavioral effects of tilt-induced body fluid shifts

NASA Technical Reports Server (NTRS)

Parker, D. E.; Tjernstrom, O.; Ivarsson, A.; Gulledge, W. L.; Poston, R. L.

1983-01-01

This paper addresses the 'fluid shift theory' of space motion sickness. The primary purpose of the research was the development of procedures to assess individual differences in response to rostral body fluid shifts on earth. Experiment I examined inner ear fluid pressure changes during head-down tilt in intact human beings. Tilt produced reliable changes. Differences among subjects and between ears within the same subject were observed. Experiment II examined auditory threshold changes during tilt. Tilt elicited increased auditory thresholds, suggesting that sensory depression may result from increased inner ear fluid pressure. Additional observations on rotation magnitude estimation during head-down tilt, which indicate that rostral fluid shifts may depress semicircular canal activity, are briefly described. The results of this research suggest that the inner ear pressure and auditory threshold shift procedures could be used to assess individual differences among astronauts prior to space flight. Results from the terrestrial observations could be related to reported incidence/severity of motion sickness in space and used to evaluate the fluid shift theory of space motion sickness.

Equation of state and critical point behavior of hard-core double-Yukawa fluids.

PubMed

Montes, J; Robles, M; López de Haro, M

2016-02-28

A theoretical study on the equation of state and the critical point behavior of hard-core double-Yukawa fluids is presented. Thermodynamic perturbation theory, restricted to first order in the inverse temperature and having the hard-sphere fluid as the reference system, is used to derive a relatively simple analytical equation of state of hard-core multi-Yukawa fluids. Using such an equation of state, the compressibility factor and phase behavior of six representative hard-core double-Yukawa fluids are examined and compared with available simulation results. The effect of varying the parameters of the hard-core double-Yukawa intermolecular potential on the location of the critical point is also analyzed using different perspectives. The relevance of this analysis for fluids whose molecules interact with realistic potentials is also pointed out.

Fluids in porous media. IV. Quench effect on chemical potential.

PubMed

Qiao, C Z; Zhao, S L; Liu, H L; Dong, W

2017-06-21

It appears to be a common sense to measure the crowdedness of a fluid system by the densities of the species constituting it. In the present work, we show that this ceases to be valid for confined fluids under some conditions. A quite thorough investigation is made for a hard sphere (HS) fluid adsorbed in a hard sphere matrix (a quench-annealed system) and its corresponding equilibrium binary mixture. When fluid particles are larger than matrix particles, the quench-annealed system can appear much more crowded than its corresponding equilibrium binary mixture, i.e., having a much higher fluid chemical potential, even when the density of each species is strictly the same in both systems, respectively. We believe that the insight gained from this study should be useful for the design of functionalized porous materials.

A randomized controlled trial to evaluate the effectiveness of a cognitive behavioural group approach to improve patient adherence to peritoneal dialysis fluid restrictions: a pilot study.

PubMed

Hare, Jennifer; Clark-Carter, David; Forshaw, Mark

2014-03-01

Peritoneal dialysis (PD) requires patients to take an active role in their adherence to fluid restrictions. Although fluid non-adherence had been identified among this patient group, no specific interventions have been researched or published with in the PD population. The current study sought to investigate whether an applied cognitive behavioural therapy (CBT-based intervention) used among haemodialysis patients would improve fluid adherence among PD patients; utilizing clinical indicators used in practice. Fifteen PD patients identified as fluid non-adherent were randomly assigned to an intervention group (IG) or a deferred-entry control group (CG). The study ran for a total of 21 weeks, with five data collection points; at baseline, post-intervention and at three follow-up points; providing a RCT phase and a combined longitudinal analysis phase. The content of the group intervention encompassed educational, cognitive and behavioural components, aimed to assist patients' self-management of fluid. No significant differences in weight (kg) reduction were found in either phase and undesirable changes in blood pressure (BP) were observed. However, in the longitudinal phase, a statistically significant difference in oedematous status was observed at 6-week follow-up; which may be indicative of fluid adherence. Positive and significant differences were observed in the desired direction for measures of psychological well-being, quality of life and health beliefs; areas correlated with enhanced fluid adherence in other research. This study reveals encouraging and significant changes in predictors of fluid adherence. Although there were no significant changes in weight as a crude clinical measure of fluid intake, significant reductions in oedematous status were observed as a consequence of this CBT-based group intervention.

Tensiometer and method of determining soil moisture potential in below-grade earthen soil

DOEpatents

Hubbell, J.M.; Mattson, E.D.; Sisson, J.B.

1998-06-02

A tensiometer to in-situ determine below-grade soil moisture, potential of earthen soil includes, (a) an apparatus adapted for insertion into earthen soil below grade, the apparatus having a below-grade portion, and, comprising; (b) a porous material provided in the below-grade portion, the porous material at least in part defining a below-grade first fluid chamber; (c) a first fluid conduit extending outwardly of the first fluid chamber; (d) a first controllable isolation valve provided within the first fluid conduit, the first controllable isolation valve defining a second fluid chamber in fluid communication with the first fluid chamber through the first fluid conduit and the isolation valve, the first controllable isolation valve being received within the below-grade portion; and (e) a pressure transducer in fluid communication with the first fluid chamber, the pressure transducer being received within the below-grade portion. An alternate embodiment includes an apparatus adapted for insertion into earthen soil below grade, the apparatus having a below-grade portion, and including: (1) a porous material provided in the below-grade portion, the porous material at least in part defining a below-grade first fluid chamber; and (2) a pressure sensing apparatus in fluid communication with the first fluid chamber, the pressure sensing apparatus being entirely received within the below-grade portion. A method is also disclosed using the above and other apparatus. 6 figs.

Tensiometer and method of determining soil moisture potential in below-grade earthen soil

DOEpatents

Hubbell, Joel M.; Mattson, Earl D.; Sisson, James B.

1998-01-01

A tensiometer to in situ determine below-grade soil moisture, potential of earthen soil includes, a) an apparatus adapted for insertion into earthen soil below grade, the apparatus having a below-grade portion, and, comprising; b) a porous material provided in the below-grade portion, the porous material at least in part defining a below-grade first fluid chamber; c) a first fluid conduit extending outwardly of the first fluid chamber; d) a first controllable isolation valve provided within the first fluid conduit, the first controllable isolation valve defining a second fluid chamber in fluid communication with the first fluid chamber through the first fluid conduit and the isolation valve, the first controllable isolation valve being received within the below-grade portion; and e) a pressure transducer in fluid communication with the first fluid chamber, the pressure transducer being received within the below-grade portion. An alternate embodiment includes an apparatus adapted for insertion into earthen soil below grade, the apparatus having a below-grade portion, and including: i) a porous material provided in the below-grade portion, the porous material at least in part defining a below-grade first fluid chamber; and ii) a pressure sensing apparatus in fluid communication with the first fluid chamber, the pressure sensing apparatus being entirely received within the below-grade portion. A method is also disclosed using the above and other apparatus.

Potential landscape and flux field theory for turbulence and nonequilibrium fluid systems

NASA Astrophysics Data System (ADS)

Wu, Wei; Zhang, Feng; Wang, Jin

2018-02-01

Turbulence is a paradigm for far-from-equilibrium systems without time reversal symmetry. To capture the nonequilibrium irreversible nature of turbulence and investigate its implications, we develop a potential landscape and flux field theory for turbulent flow and more general nonequilibrium fluid systems governed by stochastic Navier-Stokes equations. We find that equilibrium fluid systems with time reversibility are characterized by a detailed balance constraint that quantifies the detailed balance condition. In nonequilibrium fluid systems with nonequilibrium steady states, detailed balance breaking leads directly to a pair of interconnected consequences, namely, the non-Gaussian potential landscape and the irreversible probability flux, forming a 'nonequilibrium trinity'. The nonequilibrium trinity characterizes the nonequilibrium irreversible essence of fluid systems with intrinsic time irreversibility and is manifested in various aspects of these systems. The nonequilibrium stochastic dynamics of fluid systems including turbulence with detailed balance breaking is shown to be driven by both the non-Gaussian potential landscape gradient and the irreversible probability flux, together with the reversible convective force and the stochastic stirring force. We reveal an underlying connection of the energy flux essential for turbulence energy cascade to the irreversible probability flux and the non-Gaussian potential landscape generated by detailed balance breaking. Using the energy flux as a center of connection, we demonstrate that the four-fifths law in fully developed turbulence is a consequence and reflection of the nonequilibrium trinity. We also show how the nonequilibrium trinity can affect the scaling laws in turbulence.

Fluid aspects of electron streaming instability in electron-ion plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jao, C.-S.; Hau, L.-N.; Department of Physics, National Central University, Jhongli, Taiwan

2014-02-15

Electrons streaming in a background electron and ion plasma may lead to the formation of electrostatic solitary wave (ESW) and hole structure which have been observed in various space plasma environments. Past studies on the formation of ESW are mostly based on the particle simulations due to the necessity of incorporating particle's trapping effects. In this study, the fluid aspects and thermodynamics of streaming instabilities in electron-ion plasmas including bi-streaming and bump-on-tail instabilities are addressed based on the comparison between fluid theory and the results from particle-in-cell simulations. The energy closure adopted in the fluid model is the polytropic lawmore » of d(pρ{sup −γ})/dt=0 with γ being a free parameter. Two unstable modes are identified for the bump-on-tail instability and the growth rates as well as the dispersion relation of the streaming instabilities derived from the linear theory are found to be in good agreement with the particle simulations for both bi-streaming and bump-on-tail instabilities. At the nonlinear saturation, 70% of the electrons are trapped inside the potential well for the drift velocity being 20 times of the thermal velocity and the pρ{sup −γ} value is significantly increased. Effects of ion to electron mass ratio on the linear fluid theory and nonlinear simulations are also examined.« less

The Hemolymph Proteome of Fed and Starved Drosophila Larvae

PubMed Central

Goetze, Sandra; Ahrens, Christian H.; Omasits, Ulrich; Marty, Florian; Simigdala, Nikiana; Meyer, Imke; Wollscheid, Bernd; Brunner, Erich; Hafen, Ernst; Lehner, Christian F.

2013-01-01

The co-operation of specialized organ systems in complex multicellular organisms depends on effective chemical communication. Thus, body fluids (like blood, lymph or intraspinal fluid) contain myriads of signaling mediators apart from metabolites. Moreover, these fluids are also of crucial importance for immune and wound responses. Compositional analyses of human body fluids are therefore of paramount diagnostic importance. Further improving their comprehensiveness should increase our understanding of inter-organ communication. In arthropods, which have trachea for gas exchange and an open circulatory system, the single dominating interstitial fluid is the hemolymph. Accordingly, a detailed analysis of hemolymph composition should provide an especially comprehensive picture of chemical communication and defense in animals. Therefore we used an extensive protein fractionation workflow in combination with a discovery-driven proteomic approach to map out the detectable protein composition of hemolymph isolated from Drosophila larvae. Combined mass spectrometric analysis revealed more than 700 proteins extending far beyond the previously known Drosophila hemolymph proteome. Moreover, by comparing hemolymph isolated from either fed or starved larvae, we provide initial provisional insights concerning compositional changes in response to nutritional state. Storage proteins in particular were observed to be strongly reduced by starvation. Our hemolymph proteome catalog provides a rich basis for data mining, as exemplified by our identification of potential novel cytokines, as well as for future quantitative analyses by targeted proteomics. PMID:23840627

Fluid-structure coupling for an oscillating hydrofoil

NASA Astrophysics Data System (ADS)

Münch, C.; Ausoni, P.; Braun, O.; Farhat, M.; Avellan, F.

2010-08-01

Fluid-structure investigations in hydraulic machines using coupled simulations are particularly time-consuming. In this study, an alternative method is presented that linearizes the hydrodynamic load of a rigid, oscillating hydrofoil. The hydrofoil, which is surrounded by incompressible, turbulent flow, is modeled with forced and free pitching motions, where the mean incidence angle is 0° with a maximum angle amplitude of 2°. Unsteady simulations of the flow, performed with ANSYS CFX, are presented and validated with experiments which were carried out in the EPFL High-Speed Cavitation Tunnel. First, forced motion is investigated for reduced frequencies ranging from 0.02 to 100. The hydrodynamic load is modeled as a simple combination of inertia, damping and stiffness effects. As expected, the potential flow analysis showed the added moment of inertia is constant, while the fluid damping and the fluid stiffness coefficients depend on the reduced frequency of the oscillation motion. Behavioral patterns were observed and two cases were identified depending on if vortices did or did not develop in the hydrofoil wake. Using the coefficients identified in the forced motion case, the time history of the profile incidence is then predicted analytically for the free motion case and excellent agreement is found for the results from coupled fluid-structure simulations. The model is validated and may be extended to more complex cases, such as blade grids in hydraulic machinery.

Effects of radiofrequency probe application on irrigation fluid temperature in the wrist joint.

PubMed

Sotereanos, Dean G; Darlis, Nickolaos A; Kokkalis, Zinon T; Zanaros, George; Altman, Gregory T; Miller, Mark Carl

2009-12-01

Radiofrequency (RF) probes used in wrist arthroscopy may raise joint fluid temperature, increasing the risk of capsular and ligamentous damage. The purposes of the current study were to measure joint fluid temperature during wrist arthroscopy with the use of RF probes, and to determine whether using an outlet portal will reduce the maximum temperature. We performed wrist arthroscopy on 8 cadaveric arms. Ablation and coagulation cycles using RF probe were performed at documented locations within the joint. This was done for 60-second intervals on both the radial and ulnar side of the wrist, to mimic clinical practice. We used 4 fiberoptic phosphorescent probes to measure temperature (radial, ulnar, inflow-tube, and outflow-tube probes) and measured joint fluid temperature with and without outflow. There was a significant difference between wrists with and without outflow when examining maximum ablation temperatures (p < .002). All specimens showed higher maximum and average ablation temperatures without outflow. Maximum joint temperatures, greater than 60 degrees C, were observed in only no-outflow conditions. In performing RF ablation during wrist arthroscopy, the use of an outlet portal reduces the joint fluid temperature. Without an outlet portal, maximum temperatures can exceed desirable levels when using ablation; such temperatures have the potential to damage adjacent tissues. It is useful to maintain adequate outflow when using the radiofrequency probes during wrist arthroscopy.

The hemolymph proteome of fed and starved Drosophila larvae.

PubMed

Handke, Björn; Poernbacher, Ingrid; Goetze, Sandra; Ahrens, Christian H; Omasits, Ulrich; Marty, Florian; Simigdala, Nikiana; Meyer, Imke; Wollscheid, Bernd; Brunner, Erich; Hafen, Ernst; Lehner, Christian F

2013-01-01

The co-operation of specialized organ systems in complex multicellular organisms depends on effective chemical communication. Thus, body fluids (like blood, lymph or intraspinal fluid) contain myriads of signaling mediators apart from metabolites. Moreover, these fluids are also of crucial importance for immune and wound responses. Compositional analyses of human body fluids are therefore of paramount diagnostic importance. Further improving their comprehensiveness should increase our understanding of inter-organ communication. In arthropods, which have trachea for gas exchange and an open circulatory system, the single dominating interstitial fluid is the hemolymph. Accordingly, a detailed analysis of hemolymph composition should provide an especially comprehensive picture of chemical communication and defense in animals. Therefore we used an extensive protein fractionation workflow in combination with a discovery-driven proteomic approach to map out the detectable protein composition of hemolymph isolated from Drosophila larvae. Combined mass spectrometric analysis revealed more than 700 proteins extending far beyond the previously known Drosophila hemolymph proteome. Moreover, by comparing hemolymph isolated from either fed or starved larvae, we provide initial provisional insights concerning compositional changes in response to nutritional state. Storage proteins in particular were observed to be strongly reduced by starvation. Our hemolymph proteome catalog provides a rich basis for data mining, as exemplified by our identification of potential novel cytokines, as well as for future quantitative analyses by targeted proteomics.

The reliability of the physical examination to guide fluid therapy in adults with severe falciparum malaria: an observational study.

PubMed

Hanson, Josh; Lam, Sophia W K; Alam, Shamsul; Pattnaik, Rajyabardhan; Mahanta, Kishore C; Uddin Hasan, Mahatab; Mohanty, Sanjib; Mishra, Saroj; Cohen, Sophie; Day, Nicholas; White, Nicholas; Dondorp, Arjen

2013-10-01

Adults with severe malaria frequently require intravenous fluid therapy to restore their circulating volume. However, fluid must be delivered judiciously as both under- and over-hydration increase the risk of complications and, potentially, death. As most patients will be cared for in a resource-poor setting, management guidelines necessarily recommend that physical examination should guide fluid resuscitation. However, the reliability of this strategy is uncertain. To determine the ability of physical examination to identify hypovolaemia, volume responsiveness, and pulmonary oedema, clinical signs and invasive measures of volume status were collected independently during an observational study of 28 adults with severe malaria. The physical examination defined volume status poorly. Jugular venous pressure (JVP) did not correlate with intravascular volume as determined by global end diastolic volume index (GEDVI; r(s) = 0.07, p = 0.19), neither did dry mucous membranes (p = 0.85), or dry axillae (p = 0.09). GEDVI was actually higher in patients with decreased tissue turgor (p < 0.001). Poor capillary return correlated with GEDVI, but was present infrequently (7% of observations) and, therefore, insensitive. Mean arterial pressure (MAP) correlated with GEDVI (rs = 0.16, p = 0.002), but even before resuscitation patients with a low GEDVI had a preserved MAP. Anuria on admission was unrelated to GEDVI and although liberal fluid resuscitation led to a median hourly urine output of 100 ml in 19 patients who were not anuric on admission, four (21%) developed clinical pulmonary oedema subsequently. MAP was unrelated to volume responsiveness (p = 0.71), while a low JVP, dry mucous membranes, dry axillae, increased tissue turgor, prolonged capillary refill, and tachycardia all had a positive predictive value for volume responsiveness of ≤50%. Extravascular lung water ≥11 ml/kg indicating pulmonary oedema was present on 99 of the 353 times that it was assessed during the study, but was identified on less than half these occasions by tachypnoea, chest auscultation, or an elevated JVP. A clear chest on auscultation and a respiratory rate <30 breaths/minute could exclude pulmonary oedema on 82% and 72% of occasions respectively. Findings on physical examination correlate poorly with true volume status in adults with severe malaria and must be used with caution to guide fluid therapy. Clinicaltrials.gov identifier: NCT00692627.

Search for Fluid Inclusions in a Carbonaceous Chondrite Using a New X-Ray Micro-Tomography Technique Combined with FIB Sampling

NASA Technical Reports Server (NTRS)

Tsuchiyama, A.; Miyake, A.; Zolensky, M. E.; Uesugi, K.; Nakano, T.; Takeuchi, A.; Suzuki, Y.; Yoshida, K.

2014-01-01

Early solar system aqueous fluids are preserved in some H chondrites as aqueous fluid inclusions in halite (e.g., [1]). Although potential fluid inclusions are also expected in carbonaceous chondrites [2], they have not been surely confirmed. In order to search for these fluid inclusions, we have developped a new X-ray micro-tomography technique combined with FIB sampling and applied this techniqu to a carbanaceous chondrite. Experimental: A polished thin section of Sutter's Mill meteorite (CM) was observed with an optical microscope and FE-SEM (JEOL 7001F) for chosing mineral grains of carbonates (mainly calcite) and sulfides (FeS and ZnS) 20-50 microns in typical size, which may have aqueous fluid inclusions. Then, a "house" similar to a cube with a roof (20-30 microns in size) is sampled from the mineral grain by using FIB (FEI Quanta 200 3DS). Then, the house was atached to a thin W-needle by FIB and imaged by a SR-based imaging microtomography system with a Fresnel zone plate at beamline BL47XU, SPring-8, Japan. One sample was imaged at two X-ray energies, 7 and 8 keV, to identify mineral phases (dual-enegy microtomography: [3]). The size of voxel (pixel in 3D) was 50-80 nm, which gave the effective spatial resolution of approx. 200 nm. A terrestrial quartz sample with an aqueous fluid inclusion with a bubble was also examined as a test sample by the same method. Results and discussion: A fluid inclusion of 5-8 microns in quartz was clearly identified in a CT image. A bubble of approx. 4 microns was also identified as refraction contrast although the X-ray absorption difference between fluid and bubble is small. Volumes of the fluid and bubble were obtained from the 3D CT images. Fourteen grains of calcite, two grains of iron sulfide and one grain of (Zn,Fe)S were examined. Ten calcite, one iron sulfide and one (Zn,Fe)S grains have inclusions >1 micron in size (the maximum: approx. 5 microns). The shapes are spherical or irregular. Tiny inclusions (<1 micron) are also present in all the grains examined. These results show that mineral grains have more inclusions than expected from 2D observations. The X-ray absorption of the inclusions shows that they are not solid inclusions. No bubbles were observed inside, indicating that we cannot determine whether they are really aqueous fluids or merely voids. One calcite grain has an inclusion approx. 2 microns in size, which seems to have a bubble and a tiny solid daughter crystal inside (three-phase inclusion). As we know the exact 3D position of the inclusion, we will anlyze the inclusion by SIMS after freezing the sample as has been done for a halite sample [3]. The present technique is useful for finding small inclusions not only in carbonaceous chondrites but also for terrestrial materials.

Fate and Transport of Select Hydraulic Fracturing Compounds of Potential Concern

EPA Pesticide Factsheets

Use of proprietary mixtures of reagents in fracing fluids injected in deep zones, has led to controversy over potential contamination of drinking water aquifers. This presentation focuses on the different classes of compounds identified in fracing fluids.

Space Station fluid management logistics

NASA Technical Reports Server (NTRS)

Dominick, Sam M.

1990-01-01

Viewgraphs and discussion on space station fluid management logistics are presented. Topics covered include: fluid management logistics - issues for Space Station Freedom evolution; current fluid logistics approach; evolution of Space Station Freedom fluid resupply; launch vehicle evolution; ELV logistics system approach; logistics carrier configuration; expendable fluid/propellant carrier description; fluid carrier design concept; logistics carrier orbital operations; carrier operations at space station; summary/status of orbital fluid transfer techniques; Soviet progress tanker system; and Soviet propellant resupply system observations.

Stability and thermophysical studies on deep eutectic solvent based carbon nanotube nanofluid

NASA Astrophysics Data System (ADS)

Chen, Yan Yao; Walvekar, Rashmi; Khalid, Mohammad; Shahbaz, Kaveh; Gupta, T. C. S. M.

2017-07-01

Commercial coolants such as water, ethylene glycol and triethylene glycol possess very low thermal conductivity, high vapor pressure, corrosion issues and low thermal stability thus limiting the thermal enhancement of the nanofluids. Thus, a new type of base fluid known as deep eutectic solvents (DESs) is proposed in this work as a potential substitute for the conventional base fluid due to their unique solvent properties such as low vapor pressure, high thermal stability, biodegradability and non-flammability. In this work, 33 different DESs derived from phosphonium halide salt and ammonium halide salts were synthesised. Carbon nantubes (CNTs) with different concentrations (0.01 wt%-0.08 wt%) were dispersed into DESs with the help of sonication. Stability of the nanofluids were determined using both qualitative (visual observation) and quantitative (UV spectroscopy) approach. In addition, thermo-physical properties such as thermal conductivity, specific heat, viscosity and density were investigated. The stability results indicated that phosphonium based DESs have higher stability (up to 4 d) as compared to ammonium-based DESs (up to 3 d). Thermal enhancement of 30% was observed for ammonium based DES-CNT nanofluid whereas negative thermal enhancement was observed in phosphonium based DES-CNT nanofluid.

The Effect of Surface Induced Flows on Bubble and Particle Aggregation

NASA Technical Reports Server (NTRS)

Guelcher, Scott A.; Solomentsev, Yuri E.; Anderson, John L.; Boehmer, Marcel; Sides, Paul J.

1999-01-01

Almost 20 years have elapsed since a phenomenon called "radial specific coalescence" was identified. During studies of electrolytic oxygen evolution from the back side of a vertically oriented, transparent tin oxide electrode in alkaline electrolyte, one of the authors (Sides) observed that large "collector" bubbles appeared to attract smaller bubbles. The bubbles moved parallel to the surface of the electrode, while the electric field was normal to the electrode surface. The phenomenon was reported but not explained. More recently self ordering of latex particles was observed during electrophoretic deposition at low DC voltages likewise on a transparent tin oxide electrode. As in the bubble work, the field was normal to the electrode while the particles moved parallel to it. Fluid convection caused by surface induced flows (SIF) can explain these two apparently different experimental observations: the aggregation of particles on an electrode during electrophoretic deposition, and a radial bubble coalescence pattern on an electrode during electrolytic gas evolution. An externally imposed driving force (the gradient of electrical potential or temperature), interacting with the surface of particles or bubbles very near a planar conducting surface, drives the convection of fluid that causes particles and bubbles to approach each other on the electrode.

Cold Seep Epifaunal Communities on the Hikurangi Margin, New Zealand: Composition, Succession, and Vulnerability to Human Activities

PubMed Central

Bowden, David A.; Rowden, Ashley A.; Thurber, Andrew R.; Baco, Amy R.; Levin, Lisa A.; Smith, Craig R.

2013-01-01

Cold seep communities with distinctive chemoautotrophic fauna occur where hydrocarbon-rich fluids escape from the seabed. We describe community composition, population densities, spatial extent, and within-region variability of epifaunal communities at methane-rich cold seep sites on the Hikurangi Margin, New Zealand. Using data from towed camera transects, we match observations to information about the probable life-history characteristics of the principal fauna to develop a hypothetical succession sequence for the Hikurangi seep communities, from the onset of fluid flux to senescence. New Zealand seep communities exhibit taxa characteristic of seeps in other regions, including predominance of large siboglinid tubeworms, vesicomyid clams, and bathymodiolin mussels. Some aspects appear to be novel; however, particularly the association of dense populations of ampharetid polychaetes with high-sulphide, high-methane flux, soft-sediment microhabitats. The common occurrence of these ampharetids suggests they play a role in conditioning sulphide-rich sediments at the sediment-water interface, thus facilitating settlement of clam and tubeworm taxa which dominate space during later successional stages. The seep sites are subject to disturbance from bottom trawling at present and potentially from gas hydrate extraction in future. The likely life-history characteristics of the dominant megafauna suggest that while ampharetids, clams, and mussels exploit ephemeral resources through rapid growth and reproduction, lamellibrachid tubeworm populations may persist potentially for centuries. The potential consequences of gas hydrate extraction cannot be fully assessed until extraction methods and target localities are defined but any long-term modification of fluid flow to seep sites would have consequences for all chemoautotrophic fauna. PMID:24204691

Cold seep epifaunal communities on the Hikurangi margin, New Zealand: composition, succession, and vulnerability to human activities.

PubMed

Bowden, David A; Rowden, Ashley A; Thurber, Andrew R; Baco, Amy R; Levin, Lisa A; Smith, Craig R

2013-01-01

Cold seep communities with distinctive chemoautotrophic fauna occur where hydrocarbon-rich fluids escape from the seabed. We describe community composition, population densities, spatial extent, and within-region variability of epifaunal communities at methane-rich cold seep sites on the Hikurangi Margin, New Zealand. Using data from towed camera transects, we match observations to information about the probable life-history characteristics of the principal fauna to develop a hypothetical succession sequence for the Hikurangi seep communities, from the onset of fluid flux to senescence. New Zealand seep communities exhibit taxa characteristic of seeps in other regions, including predominance of large siboglinid tubeworms, vesicomyid clams, and bathymodiolin mussels. Some aspects appear to be novel; however, particularly the association of dense populations of ampharetid polychaetes with high-sulphide, high-methane flux, soft-sediment microhabitats. The common occurrence of these ampharetids suggests they play a role in conditioning sulphide-rich sediments at the sediment-water interface, thus facilitating settlement of clam and tubeworm taxa which dominate space during later successional stages. The seep sites are subject to disturbance from bottom trawling at present and potentially from gas hydrate extraction in future. The likely life-history characteristics of the dominant megafauna suggest that while ampharetids, clams, and mussels exploit ephemeral resources through rapid growth and reproduction, lamellibrachid tubeworm populations may persist potentially for centuries. The potential consequences of gas hydrate extraction cannot be fully assessed until extraction methods and target localities are defined but any long-term modification of fluid flow to seep sites would have consequences for all chemoautotrophic fauna.

Highly resolved fluid flows: "liquid plasmas" at the kinetic level.

PubMed

Morfill, Gregor E; Rubin-Zuzic, Milenko; Rothermel, Hermann; Ivlev, Alexei V; Klumov, Boris A; Thomas, Hubertus M; Konopka, Uwe; Steinberg, Victor

2004-04-30

Fluid flow around an obstacle was observed at the kinetic (individual particle) level using "complex (dusty) plasmas" in their liquid state. These "liquid plasmas" have bulk properties similar to water (e.g., viscosity), and a comparison in terms of similarity parameters suggests that they can provide a unique tool to model classical fluids. This allows us to study "nanofluidics" at the most elementary-the particle-level, including the transition from fluid behavior to purely kinetic transport. In this (first) experimental investigation we describe the kinetic flow topology, discuss our observations in terms of fluid theories, and follow this up with numerical simulations.

Transcapillary protein flux following blood volume modification in dog.

PubMed

Miki, K; Nose, H; Tanaka, Y; Morimoto, T

1984-01-01

The net fluid and protein movements between intravascular and interstitial space following blood withdrawal and retransfusion of 15% of circulating blood volume were measured in dogs using a continuous monitoring method of circulating blood volume. A significant (p less than 0.01) increase in transvascular fluid shift was observed after the start of blood withdrawal and a new equilibrium state was reached within 15 to 20 min. Associated with the fluid shift, a significant increase in plasma protein of about 1 g was observed. On the other hand, blood retransfusion caused significant (p less than 0.01) increases in the shift of fluid and protein from intravascular space to interstitial space. The magnitudes of the shift of fluid and protein were almost identical in both blood withdrawal and retransfusion. The Kedem-Katchalsky transport equation was applied to the results obtained in the present study in order to analyze the relative role of diffusion and convection and to estimate the reflection coefficient for protein. A significant (p less than 0.01) linear relationship was observed between fluid and protein movement. These results suggest that the convective process is involved in the shift of protein between intravascular and interstitial space observed after blood volume modification.

Clonal analysis of synovial fluid stem cells to characterize and identify stable mesenchymal stromal cell/mesenchymal progenitor cell phenotypes in a porcine model: a cell source with enhanced commitment to the chondrogenic lineage.

PubMed

Ando, Wataru; Kutcher, Josh J; Krawetz, Roman; Sen, Arindom; Nakamura, Norimasa; Frank, Cyril B; Hart, David A

2014-06-01

Previous studies have demonstrated that porcine synovial membrane stem cells can adhere to a cartilage defect in vivo through the use of a tissue-engineered construct approach. To optimize this model, we wanted to compare effectiveness of tissue sources to determine whether porcine synovial fluid, synovial membrane, bone marrow and skin sources replicate our understanding of synovial fluid mesenchymal stromal cells or mesenchymal progenitor cells from humans both at the population level and the single-cell level. Synovial fluid clones were subsequently isolated and characterized to identify cells with a highly characterized optimal phenotype. The chondrogenic, osteogenic and adipogenic potentials were assessed in vitro for skin, bone marrow, adipose, synovial fluid and synovial membrane-derived stem cells. Synovial fluid cells then underwent limiting dilution analysis to isolate single clonal populations. These clonal populations were assessed for proliferative and differentiation potential by use of standardized protocols. Porcine-derived cells demonstrated the same relationship between cell sources as that demonstrated previously for humans, suggesting that the pig may be an ideal preclinical animal model. Synovial fluid cells demonstrated the highest chondrogenic potential that was further characterized, demonstrating the existence of a unique clonal phenotype with enhanced chondrogenic potential. Porcine stem cells demonstrate characteristics similar to those in human-derived mesenchymal stromal cells from the same sources. Synovial fluid-derived stem cells contain an inherent phenotype that may be optimal for cartilage repair. This must be more fully investigated for future use in the in vivo tissue-engineered construct approach in this physiologically relevant preclinical porcine model. Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Methanethiol abundance in high-temperature hydrothermal fluids from the Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Reeves, E.; Seewald, J. S.; Saccocia, P.; van der Meer, M.

2008-12-01

The formation of aqueous organic sulfur compounds in hydrothermal systems remains poorly constrained, despite their potential significance in 'prebiotic' chemistry and the origin of life. The simplest - methanethiol (CH3SH) - has been implicated as a critical abiogenic precursor to the establishment of primitive microbial metabolism in early Earth hydrothermal settings. It also represents a readily-utilized substrate for microbial sulfate-reducing communities and a potential intermediate species in abiotic CH4 formation. To assess the abundance of CH3SH and factors regulating its stability under hydrothermal conditions we measured CH3SH concentrations in a suite of hydrothermal fluids collected from the Rainbow, Lucky Strike, TAG and Lost City hydrothermal sites located on the Mid-Atlantic Ridge. Fluids were collected using isobaric gas-tight samplers and analyzed for CH3SH by shipboard purge-and-trap gas chromatography. Measured concentrations at Rainbow (1.2 -- 223nM), Lucky Strike (1.1 -- 26nM), TAG (8.5 -- 11nM) and Lost City (1.6 -- 3.0nM) are all substantially lower than predicted for thermodynamic equilibrium with CO2, H2 and H2S at measured vent conditions. The highest concentrations (91 -- 223nM), however, were observed at Rainbow in intermediate temperature (128 -- 175°C) H2-rich fluids that may have undergone conductive cooling. Increased concentrations with decreasing temperature is consistent with the thermodynamic drive for the formation from CO2, suggesting a possible abiotic origin for CH3SH in some fluids. Substantially lower concentrations in the low temperature fluids at Lost City are consistent with the extremely low levels of CO2 and H2S in these fluids. Other possible sources of CH3SH to vent fluids must be considered, however, and include thermal alteration of biomass present in low-temperature environments and microbial consortia that produce CH3SH as a byproduct of anaerobic methane oxidation. Current models for the emergence of primordial metabolism in highly-reducing alkaline hydrothermal environments invoke CH3SH as a key reactant leading to Acetyl CoA-based (Wood-Ljungdahl) carbon fixation pathways. Results of this study challenge the notion that high-pH, reducing fluids emanating from serpentinite-hosted hydrothermal systems like Lost City were favorable for the production of CH3SH, the establishment of a primitive metabolic cycle and the emergence of microbial life on Earth.

The role of chemical processes and brittle deformation during shear zone formation and its potential geophysical implications

NASA Astrophysics Data System (ADS)

Goncalves, Philippe; Leydier, Thomas; Mahan, Kevin; Albaric, Julie; Trap, Pierre; Marquer, Didier

2017-04-01

Ductile shear zones in the middle and lower continental crust are the locus of interactions between mechanical and chemical processes. Chemical processes encompass metamorphic reactions, fluid-rock interactions, fluid flow and chemical mass-transfer. Studying these processes at the grain scale, and even the atom scale, on exposed inactive shear zones can give insights into large-scale geodynamics phenomena (e.g. crustal growth and mountain building through the reconstruction of P-T-t-D-Ɛ evolutionary paths. However, other major issues in earth sciences can be tackled through these studies as well. For instance, the mechanism of fluid flow and mass transfer in the deep crust where permeability should be small and transient is still largely debated. Studying exhumed inactive shear zones can also help to interpret several new geophysical observations like (1) the origin of tremor and very low frequency earthquakes observed in the ductile middle and lower crust, (2) mechanisms for generating slow slip events and (3) the physical origin of puzzling crustal anisotropy observed in major active crustal shear zones. In this contribution, we present a collection of data (deformation, petrology, geochemistry, microtexture) obtained on various shear zones from the Alps that were active within the viscous regime (T > 450°C). Our observations show that the development of a shear zone, from its nucleation to its growth and propagation, is not only governed by ductile deformation coeval with reactions but also involves brittle deformation. Although brittle deformation is a very short-lived phenomenon, our petrological and textural observations show that brittle failure is also associated with fluid flow, mass transfer, metasomatic reactions and recrystallization. We speculate that the fluids and the associated mineralogical changes involved during this brittle failure in the ductile crust might play a role in earthquake / tremor triggering below the brittle - ductile transition. Furthermore, the occurrence of micro-fracturing in the ductile crust must have an influence on elastic wave propagation. While in the upper crust, fractures are believed to be the primary contributor to seismic anisotropy, at high pressure, the intrinsic rock Vp and Vs velocities are largely a function of the shape and crystallographic preferred orientation of minerals. However, if microfracturing is involved during ductile deformation, it may have a stronger influence on seismic properties (velocity and anisotropy) than the SPO and CPO of the main mineral phases, particularly if the microfractures are preferentially oriented. Thus, in major active ductile shear zones, like the Main Himalayan Thrust, the speculated transient but pervasive micro-fracturing during ongoing ductile deformation should be considered when interpreting seismic anisotropy. Finding evidences for brittle deformation, and associated fluid flow, in the ductile crust is a major challenge because many of these textural and mineralogical features tend to be obliterated by the pro-eminent ductile deformation. However, in order to fully understand the causes of some of these geophysical observations, the chemical and physical characterization of exhumed "fossil" ductile shear zones remains essential.

Barium isotope fractionation during witherite (BaCO3) dissolution, precipitation and at equilibrium

NASA Astrophysics Data System (ADS)

Mavromatis, Vasileios; van Zuilen, Kirsten; Purgstaller, Bettina; Baldermann, Andre; Nägler, Thomas F.; Dietzel, Martin

2016-10-01

This study examines the behavior of Ba isotope fractionation between witherite and fluid during mineral dissolution, precipitation and at chemical equilibrium. Experiments were performed in batch reactors at 25 °C in 10-2 M NaCl solution where the pH was adjusted by continuous bubbling of a water saturated gas phase of CO2 or atmospheric air. During witherite dissolution no Ba isotope fractionation was observed between solid and fluid. In contrast, during witherite precipitation, caused by a pH increase, a preferential uptake of the lighter 134Ba isotopomer in the solid phase was observed. In this case, the isotope fractionation factor αwitherite-fluid is calculated to be 0.99993 ± 0.00004 (or Δ137/134Bawitherite-fluid ≈ -0.07 ± 0.04‰, 2 sd). The most interesting feature of this study, however, is that after the attainment of chemical equilibrium, the Ba isotope composition of the aqueous phase is progressively becoming lighter, indicating a continuous exchange of Ba2+ ions between witherite and fluid. Mass balance calculations indicate that the detachment of Ba from the solid is not only restricted to the outer surface layer of the solid, but affects several (∼7 unit cells) subsurface layers of the crystal. This observation comes in excellent agreement with the concept of a dynamic system at chemical equilibrium in a mineral-fluid system, denoting that the time required for the achievement of isotopic equilibrium in the witherite-fluid system is longer compared to that observed for chemical equilibrium. Overall, these results indicate that the isotopic composition of Ba bearing carbonates in natural environments may be altered due to changes in fluid composition without a net dissolution/precipitation to be observed.

Isotope Variations in Terrestrial Carbonates and Thermal Springs as Biomarkers: Analogs for Martian Processes

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Gibson, Everett K., Jr.; Bissada, K. K.

2006-01-01

Stable isotope measurements of carbonate minerals contained within ALH84001 [1] suggest that fluids were present at 3.9 Gy on Mars [2, 3, 4, 5]. Both oxygen and carbon isotopes provide independent means of deciphering paleoenvironmental conditions at the time of carbonate mineral precipitation. In terrestrial carbonate rocks oxygen isotopes not only indicate the paleotemperature of the precipitating fluid, but also provide clues to environmental conditions that affected the fluid chemistry. Carbon isotopes, on the other hand, can indicate the presence or absence of organic compounds during precipitation (i.e. biogenically vs. thermogenically-generated methane), thus serving as a potential biomarker. We have undertaken a study of micro scale stable isotope variations measured in some terrestrial carbonates and the influence of organic compounds associated with the formation of these carbonates. Preliminary results indicate that isotope variations occur within narrow and discrete intervals, providing clues to paleoenvironmental conditions that include both biological and non-biological activity. These results carry implications for deciphering Martian isotope data and therefore potential biological prospecting on the planet Mars. Recently, Fourier Transform Spectrometer observations have detected methane occurring in the Martian atmosphere [6] that could be attributed to a possible biogenic source. Indeed, Mars Express has detected the presence of methane in the Martian atmosphere [7], with evidence indicating that methane abundances are greatest above those basins with high water concentrations.

Potential Impacts of Spilled Hydraulic Fracturing Fluid Chemicals on Water Resources: Types, volumes, and physical-chemical properties of chemicals

EPA Science Inventory

Hydraulic fracturing (HF) fluid chemicals spilled on-site may impact drinking water resources. While chemicals generally make up <2% of the total injected fluid composition by mass, spills may have undiluted concentrations. HF fluids typically consist of a mixture of base flui...

In-situ Mechanical Manipulation of Wellbore Cements as a Solution to Leaky Wells

NASA Astrophysics Data System (ADS)

Kupresan, D.; Radonjic, M.; Heathman, J.

2013-12-01

Wellbore cement provides casing support, zonal isolation, and casing protection from corrosive fluids, which are essential for wellbore integrity. Cements can undergo one or more forms of failure such as debonding at cement/formation and cement/casing interface, fracturing and defects within cement matrix. Failures and defects within cement will ultimately lead to fluids migration, resulting in inter-zonal fluid migration and premature well abandonment. There are over 27,000 abandoned oil and gas wells only in The Gulf of Mexico (some of them dating from the late 1940s) with no gas leakage monitoring. Cement degradation linked with carbon sequestration can potentially lead to contamination of fresh water aquifers with CO2. Gas leaks can particularly be observed in deviated wells used for hydraulic fracking (60% leakage rate as they age) as high pressure fracturing increases the potential for migration pathways. Experimental method utilized in this study enables formation of impermeable seals at interfaces present in a wellbore by mechanically manipulating wellbore cement. Preliminary measurements obtained in bench scale experiments demonstrate that an impermeable cement/formation and cement/casing interface can be obtained. In post-modified cement, nitrogen gas flow-through experiments showed complete zonal isolation and no permeability in samples with pre-engineered microannulus. Material characterization experiments of modified cement revealed altered microstructural properties of cement as well as changes in mineralogical composition. Calcium-silicate-hydrate (CSH), the dominant mineral in hydrated cement which provides low permeability of cement, was modified as a result of cement pore water displacement, resulting in more dense structures. Calcium hydroxide (CH), which is associated with low resistance of cement to acidic fluids and therefore detrimental in most wellbore cements, was almost completely displaced and/or integrated in CSH as a result of mechanical manipulation (shear stress). The main advantage of this methodology is that mechanical manipulation of cement can induce healing of existing fractures, channels and microannulus seal in a wellbore without introducing new materials (e.g. cement squeeze jobs). Furthermore, this methodology is less sensitive to the influence of downhole conditions such as pressure, temperature and formation fluids, since it uses cement pore water as a medium to alter cement sheath. Based on lab experiments observation, it is possible to perceive that once tested at the industrial scale and if successful, the implementation of this method in the field can potentially mitigate leaky wells in CO2 sequestration projects, wellbores completed for hydraulic-fracturing and other conventional oil and gas producing wells. Key words: Wellbore cement integrity; Leaky wells; Cement microstructures; Casing expansion effect on cement mineralogy alterations.

Using estimated risk to develop stimulation strategies for induced seismicity in enhanced geothermal systems

NASA Astrophysics Data System (ADS)

Douglas, John; Aochi, Hideo

2014-05-01

Enhanced Geothermal Systems (EGS) are an attractive source of low-carbon electricity and heating. Consequently, a number of tests of this technology have been made during the past couple of decades and various projects are being planned or under development. EGS work by the injection of fluid into deep boreholes to increase permeability and hence allow the circulation and heating of fluid through a geothermal reservoir. Permeability is irreversibly increased by the shearing of pre-existing factures or fault segments, and hence by the generation of microseismicity. One aspect of this technology that can cause public concern and consequently could limit the widespread adoption of EGS within populated areas is the risk of generating earthquakes that are sufficiently large to be felt (or even to cause building damage). Therefore, there is a need to balance stimulation and exploitation of the geothermal reservoir by injecting fluids against the pressing requirement to keep the earthquake risk below an acceptable level. Current strategies to balance these potentially conflicting requirements rely on a traffic light system based on the observed magnitudes of the triggered earthquakes and the measured peak ground velocities from these events. Douglas and Aochi (Pageoph, 2014) propose an alternative system that uses the actual risk of generating felt (or damaging) earthquake ground motions at a site of interest (e.g. a nearby town) to control the injection rate. This risk is computed by combining characteristics of the observed seismicity rate of the previous six hours, with a (potentially site-specific) ground-motion prediction equation to obtain a real-time seismic hazard curve, and then the convolution of this with the derivative of a (potentially site-specific) fragility curve. Based on the relation between computed risk and pre-defined acceptable risk thresholds the injection is: increased (if the risk is below the amber level), decreased (if the risk is between amber and red levels) or stopped completely (if the risk is above the red level). Based on simulations using a recently developed model of induced seismicity in geothermal systems (Aochi et al., GJI, 2014), which is validated here using observations from the Basel EGS in 2006, it is shown that the proposed procedure could lead to both acceptable levels of risk and increased permeability.

Thermodynamics and simulation of hard-sphere fluid and solid: Kinetic Monte Carlo method versus standard Metropolis scheme

NASA Astrophysics Data System (ADS)

Ustinov, E. A.

2017-01-01

The paper aims at a comparison of techniques based on the kinetic Monte Carlo (kMC) and the conventional Metropolis Monte Carlo (MC) methods as applied to the hard-sphere (HS) fluid and solid. In the case of the kMC, an alternative representation of the chemical potential is explored [E. A. Ustinov and D. D. Do, J. Colloid Interface Sci. 366, 216 (2012)], which does not require any external procedure like the Widom test particle insertion method. A direct evaluation of the chemical potential of the fluid and solid without thermodynamic integration is achieved by molecular simulation in an elongated box with an external potential imposed on the system in order to reduce the particle density in the vicinity of the box ends. The existence of rarefied zones allows one to determine the chemical potential of the crystalline phase and substantially increases its accuracy for the disordered dense phase in the central zone of the simulation box. This method is applicable to both the Metropolis MC and the kMC, but in the latter case, the chemical potential is determined with higher accuracy at the same conditions and the number of MC steps. Thermodynamic functions of the disordered fluid and crystalline face-centered cubic (FCC) phase for the hard-sphere system have been evaluated with the kinetic MC and the standard MC coupled with the Widom procedure over a wide range of density. The melting transition parameters have been determined by the point of intersection of the pressure-chemical potential curves for the disordered HS fluid and FCC crystal using the Gibbs-Duhem equation as a constraint. A detailed thermodynamic analysis of the hard-sphere fluid has provided a rigorous verification of the approach, which can be extended to more complex systems.

Salt tectonics and shallow subseafloor fluid convection: Models of coupled fluid-heat-salt transport

USGS Publications Warehouse

Wilson, A.; Ruppel, C.

2007-01-01

Thermohaline convection associated with salt domes has the potential to drive significant fluid flow and mass and heat transport in continental margins, but previous studies of fluid flow associated with salt structures have focused on continental settings or deep flow systems of importance to petroleum exploration. Motivated by recent geophysical and geochemical observations that suggest a convective pattern to near-seafloor pore fluid flow in the northern Gulf of Mexico (GoMex), we devise numerical models that fully couple thermal and chemical processes to quantify the effects of salt geometry and seafloor relief on fluid flow beneath the seafloor. Steady-state models that ignore halite dissolution demonstrate that seafloor relief plays an important role in the evolution of shallow geothermal convection cells and that salt at depth can contribute a thermal component to this convection. The inclusion of faults causes significant, but highly localized, increases in flow rates at seafloor discharge zones. Transient models that include halite dissolution show the evolution of flow during brine formation from early salt-driven convection to later geothermal convection, characteristics of which are controlled by the interplay of seafloor relief and salt geometry. Predicted flow rates are on the order of a few millimeters per year or less for homogeneous sediments with a permeability of 10−15 m2, comparable to compaction-driven flow rates. Sediment permeabilities likely fall below 10−15 m2 at depth in the GoMex basin, but such thermohaline convection can drive pervasive mass transport across the seafloor, affecting sediment diagenesis in shallow sediments. In more permeable settings, such flow could affect methane hydrate stability, seafloor chemosynthetic communities, and the longevity of fluid seeps.

Analysis of sources of bulk conductivity change in saturated silica sand after unbuffered TCE oxidation by permanganate.

PubMed

Hort, Ryan D; Revil, André; Munakata-Marr, Junko

2014-09-01

Time lapse resistivity surveys could potentially improve monitoring of permanganate-based in situ chemical oxidation (ISCO) of organic contaminants such as trichloroethene (TCE) by tracking changes in subsurface conductivity that result from injection of permanganate and oxidation of the contaminant. Bulk conductivity and pore fluid conductivity changes during unbuffered TCE oxidation using permanganate are examined through laboratory measurements and conductivity modeling using PHREEQC in fluid samples and porous media samples containing silica sand. In fluid samples, oxidation of one TCE molecule produces three chloride ions and one proton, resulting in an increase in fluid electrical conductivity despite the loss of two permanganate ions in the reaction. However, in saturated sand samples in which up to 8mM TCE was oxidized, at least 94% of the fluid conductivity associated with the presence of protons was removed within 3h of sand contact, most likely through protonation of silanol groups found on the surface of the sand grains. Minor conductivity effects most likely associated with pH-dependent reductive dissolution of manganese dioxide were also observed but not accounted for in pore-fluid conductivity modeling. Unaccounted conductivity effects resulted in an under-calculation of post-reaction pore fluid conductivity of 2.1% to 5.5%. Although small increases in the porous media formation factor resulting from precipitation of manganese dioxide were detected (about 3%), these increases could not be confirmed to be statistically significant. Both injection of permanganate and oxidation of TCE cause increases in bulk conductivity that would be detectable through time-lapse resistivity surveys in field conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

Assessing the Potential for Sediment Gravity-Driven Underflows at the Currently Active Mouth of the Huanghe Delta

NASA Astrophysics Data System (ADS)

Mullane, M.; Kumpf, L. L.; Kineke, G. C.

2017-12-01

The Huanghe (Yellow River), once known for extremely high suspended-sediment concentrations (SSCs) that could produce hyperpycnal plumes (10s of g/l), has experienced a dramatic reduction in sediment load following the construction of several reservoirs, namely the Xiaolangdi reservoir completed in 1999. Except for managed flushing events, SSC in the lower river is now on the order of 1 g/l or less. Adaptations of the Chezy equation for gravity-driven transport show that dominant parameters driving hyperpycnal underflows include concentration (and therefore density), thickness of a sediment-laden layer and bed slope. The objectives of this research were to assess the potential for gravity-driven underflows given modern conditions at the active river mouth. Multiple shore-normal transects were conducted during research cruises in mid-July of 2016 and 2017 using a Knudsen dual-frequency echosounder to collect bathymetric data and to document the potential presence of fluid mud layers. An instrumented profiling tripod equipped with a CTD, optical backscatterance sensor and in-situ pump system were used to sample water column parameters. SSCs were determined from near-bottom and surface water samples. Echosounder data were analyzed for bed slopes at the delta-front and differences in depth of return for the two frequencies (50 and 200 kHz), which could indicate fluid muds. Bathymetric data analysis yielded bed slope measurements near or above threshold values to produce gravity-driven underflows (0.46°). The maximum observed thickness of a potential fluid mud layer was 0.7 m, and the highest sampled near-bed SSCs were nearly 14 g/l for both field campaigns. These results indicate that the modern delta maintains potential for sediment gravity-driven underflows, even during ambient conditions prior to maximum summer discharge. These results will inform future work quantitatively comparing the contributions of all sediment dispersal mechanisms near the active Huanghe delta environment, including advection of the buoyant river plume and wave resuspension and transport by tidal currents.

Crystallization of soft matter under confinement at interfaces and in wedges

NASA Astrophysics Data System (ADS)

Archer, Andrew J.; Malijevský, Alexandr

2016-06-01

The surface freezing and surface melting transitions that are exhibited by a model two-dimensional soft matter system are studied. The behaviour when confined within a wedge is also considered. The system consists of particles interacting via a soft purely repulsive pair potential. Density functional theory (DFT) is used to calculate density profiles and thermodynamic quantities. The external potential due to the confining walls is modelled via a hard wall with an additional repulsive Yukawa potential. The surface phase behaviour depends on the range and strength of this repulsion: when the repulsion is weak, the wall promotes freezing at the surface of the wall. The thickness of this frozen layer grows logarithmically as the bulk liquid-solid phase coexistence is approached. Our mean-field DFT predicts that this crystalline layer at the wall must be nucleated (i.e. there is a free energy barrier) and its formation is necessarily a first-order transition, referred to as ‘prefreezing’, by analogy with the prewetting transition. However, in contrast to the latter, prefreezing cannot terminate in a critical point, since the phase transition involves a change in symmetry. If the wall-fluid interaction is sufficiently long ranged and the repulsion is strong enough, surface melting can occur instead. Then the interface between the wall and the bulk crystalline solid is wetted by the liquid phase as the chemical potential is decreased towards the value at liquid-solid coexistence. It is observed that the finite thickness fluid film at the wall has a broken translational symmetry due to its proximity to the bulk crystal, and so the nucleation of the wetting film can be either first order or continuous. Our mean-field theory predicts that for certain wall potentials there is a premelting critical point analogous to the surface critical point for the prewetting transition. When the fluid is confined within a linear wedge, this can strongly promote freezing when the opening angle of the wedge is commensurate with the crystal lattice.

Microwave Propagation in Dielectric Fluids.

ERIC Educational Resources Information Center

Lonc, W. P.

1980-01-01

Describes an undergraduate experiment designed to verify quantitatively the effect of a dielectric fluid's dielectric constant on the observed wavelength of microwave radiation propagating through the fluid. The fluid used is castor oil, and results agree with the expected behavior within 5 percent. (Author/CS)

Standing electromagnetic solitons in hot ultra-relativistic electron-positron plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heidari, E., E-mail: ehphys75@iaubushehr.ac.ir; Aslaninejad, M.; Eshraghi, H.

2014-03-15

Using a one-dimensional self-consistent fluid model, we investigate standing relativistic bright solitons in hot electron-positron plasmas. The positron dynamics is taken into account. A set of nonlinear coupled differential equations describing the evolution of electromagnetic waves in fully relativistic two-fluid plasma is derived analytically and solved numerically. As a necessary condition for the existence of standing solitons the system should be relativistic. For the case of ultra-relativistic plasma, we investigate non-drifting bright solitary waves. Detailed discussions of the acceptable solutions are presented. New single hump non-trivial symmetric solutions for the scalar potential were found, and single and multi-nodal symmetric andmore » anti-symmetric solutions for the vector potential are presented. It is shown that for a fixed value of the fluid velocity excited modes with more zeros in the profile of the vector potential show a higher magnitude for the scalar potential. An increase in the plasma fluid velocity also increases the magnitude of the scalar potential. Furthermore, the Hamiltonian and the first integral of the system are given.« less

Persistent hyperphagia in acquired brain injury; an observational case study of patients receiving inpatient rehabilitation.

PubMed

Rowell, Arleen M; Faruqui, Rafey A

2010-01-01

Morbid hunger or persistent hyperphagia is a relatively rare but potentially life threatening complication of acquired brain injury (ABI). This paper presents findings from an observational case study of patients with hyperphagia receiving inpatient neurobehavioural rehabilitation following their acquired brain injury. The case study has utilized dietetic and medical records of identified patients to confirm the persistent and serious nature of this presentation in order to extract important management principles. The findings confirmed that hyperphagia or morbid hunger posed potentially life-threatening health risks to the patient, primarily around weight control and fluid balance, and risks of aggression towards professional and family carers. Pharmacological or behaviour modification interventions were only partially successful in management of this presentation. The study identified a high need for environmental and cue exposure control in management of this condition.

Surface tension driven flow in glass melts and model fluids

NASA Technical Reports Server (NTRS)

Mcneil, T. J.; Cole, R.; Subramanian, R. S.

1982-01-01

Surface tension driven flow has been investigated analytically and experimentally using an apparatus where a free column of molten glass or model fluids was supported at its top and bottom faces by solid surfaces. The glass used in the experiments was sodium diborate, and the model fluids were silicone oils. In both the model fluid and glass melt experiments, conclusive evidence was obtained to prove that the observed flow was driven primarily by surface tension forces. The experimental observations are in qualitative agreement with predictions from the theoretical model.

Could Fluid Seeps Originate from the Seismogenic Zone? Evidence from Southern Costa Rica

NASA Astrophysics Data System (ADS)

Silver, E. A.; Kluesner, J. W.; Nale, S. M.; Bangs, N. L.; McIntosh, K. D.; Ranero, C. R.; Tryon, M. D.; Spinelli, G. A.; Rathburn, T.; von Huene, R.

2013-12-01

The prevailing conceptual model of convergent margin hydrogeology is one in which fluid sourced from porosity loss and dehydration reactions seaward of the updip limit of the seismogenic zone reach the seafloor via relatively low angle splay faults that act as high permeability conduits through an otherwise nearly impermeable upper plate [e.g., Lauer and Saffer, GRL, 39:L13604, 2012; Saffer and Tobin, Ann. Rev. Earth Planet. Sci., 39:157-186, 2011]. Interpretation of newly acquired 3D seismic reflection data and high resolvability multibeam and backscatter data, showing evidence for abundant potential fluid seeps sourced beneath the sediment cover and farther landward than previously thought possible, may require reevaluation of this concept. Kluesner et al. [2013, G3, doi:10.1002/ggge.20058], identified 160 potential fluid seeps in an 11 km wide swath off southern Costa Rica, based on pockmarks and high backscatter mounds, each showing subsurface indicators of fluid migration in the seismic data. Approximately half of these potential seeps are on the outer continental shelf; these are landward of the updip limit of the seismogenic zone, as estimated by both the transition from high to low reflectivity of the plate boundary and the intersection of the 150°C isotherm with the plate boundary [Ranero et al., 2008, G3, doi:10.1029/2007GC001679; Bangs et al., 2012, AGU Fall Meeting, T13A-2587; Bangs et al., this meeting]. We have mapped high probability fluid pathways beneath these potential seeps, based on seismic meta-attribute volumes calculated using user-trained neural network algorithms [Kluesner et al., this meeting]. The mapped fluid pathways are high-angle through the sedimentary section, and they root into basement highs and basement faults. Fluids could originate along the plate interface, where potential sources and pathways are known (Mid-slope sites: Hensen et al., 2004, Geology, 32:201-204), or above or below the interface, although sources from these regions have not been reported. They could travel near vertical paths through the crustal rocks, or along a landward-dipping path, because the seismic data show landward dips but not seaward dips. If the fluids do come from the plate interface, they originate in the seismogenic zone. This inference can be tested by geochemical study of the outer shelf fluid seeps, where such sampling has not yet occurred.

Quantitative body fluid proteomics in medicine - A focus on minimal invasiveness.

PubMed

Csősz, Éva; Kalló, Gergő; Márkus, Bernadett; Deák, Eszter; Csutak, Adrienne; Tőzsér, József

2017-02-05

Identification of new biomarkers specific for various pathological conditions is an important field in medical sciences. Body fluids have emerging potential in biomarker studies especially those which are continuously available and can be collected by non-invasive means. Changes in the protein composition of body fluids such as tears, saliva, sweat, etc. may provide information on both local and systemic conditions of medical relevance. In this review, our aim is to discuss the quantitative proteomics techniques used in biomarker studies, and to present advances in quantitative body fluid proteomics of non-invasively collectable body fluids with relevance to biomarker identification. The advantages and limitations of the widely used quantitative proteomics techniques are also presented. Based on the reviewed literature, we suggest an ideal pipeline for body fluid analyses aiming at biomarkers discoveries: starting from identification of biomarker candidates by shotgun quantitative proteomics or protein arrays, through verification of potential biomarkers by targeted mass spectrometry, to the antibody-based validation of biomarkers. The importance of body fluids as a rich source of biomarkers is discussed. Quantitative proteomics is a challenging part of proteomics applications. The body fluids collected by non-invasive means have high relevance in medicine; they are good sources for biomarkers used in establishing the diagnosis, follow up of disease progression and predicting high risk groups. The review presents the most widely used quantitative proteomics techniques in body fluid analysis and lists the potential biomarkers identified in tears, saliva, sweat, nasal mucus and urine for local and systemic diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

Identification of sandstone core damage using scanning electron microscopy

NASA Astrophysics Data System (ADS)

Ismail, Abdul Razak; Jaafar, Mohd Zaidi; Sulaiman, Wan Rosli Wan; Ismail, Issham; Shiunn, Ng Yinn

2017-12-01

Particles and fluids invasion into the pore spaces causes serious damage to the formation, resulting reduction in petroleum production. In order to prevent permeability damage for a well effectively, the damage mechanisms should be identified. In this study, water-based drilling fluid was compared to oil-based drilling fluids based on microscopic observation. The cores were damaged by several drilling fluid systems. Scanning electron microscope (SEM) was used to observe the damage mechanism caused by the drilling fluids. Results showed that the ester based drilling fluid system caused the most serious damage followed by synthetic oil based system and KCI-polymer system. Fine solids and filtrate migration and emulsion blockage are believed to be the major mechanisms controlling the changes in flow properties for the sandstone samples.

Altered neuronal activities in the motor cortex with impaired motor performance in adult rats observed after infusion of cerebrospinal fluid from amyotrophic lateral sclerosis patients.

PubMed

Sankaranarayani, R; Nalini, A; Rao Laxmi, T; Raju, T R

2010-01-05

Although definite evidences are available to state that, neuronal activity is a prime determinant of animal behavior, the specific relationship between local field potentials of the motor cortex after intervention with CSF from human patients and animal behavior have remained opaque. The present study has investigated whether cerebrospinal fluid from sporadic amyotrophic lateral sclerosis (sALS) patients could disrupt neuronal activity of the motor cortex, which could be associated with disturbances in the motor performance of adult rats. CSF from ALS patients (ALS-CSF) was infused into the lateral ventricle of Wistar rats. After 24h, the impact of ALS-CSF on the local field potentials (LFPs) of the motor cortex and on the motor behavior of animals were examined. The results indicate that ALS-CSF produced a bivariate distribution on the relative power values of the LFPs of the motor cortex 24h following infusion. However, the behavioral results did not show bimodality, instead showed consistent decrease in motor performance: on rotarod and grip strength meter. The neuronal activity of the motor cortex negatively correlated with the duration of ALS symptoms at the time of lumbar puncture. Although the effect of ALS-CSF was more pronounced at 24h following infusion, the changes observed in LFPs and motor performance appeared to revert to baseline values at later time points of testing. In the current study, we have shown that, ALS-CSF has the potential to perturb neuronal activity of the rat motor cortex which was associated with poor performance on motor function tests.

Characterization of the potential energy landscape of an antiplasticized polymer.

PubMed

Riggleman, Robert A; Douglas, Jack F; de Pablo, Juan J

2007-07-01

The nature of the individual transitions on the potential energy landscape (PEL) associated with particle motion are directly examined for model fragile glass-forming polymer melts, and the results are compared to those of an antiplasticized polymer system. In previous work, we established that the addition of antiplasticizer reduces the fragility of glass formation so that the antiplasticized material is a stronger glass former. In the present work, we find that the antiplasticizing molecules reduce the energy barriers for relaxation compared to the pure polymer, implying that the antiplasticized system has smaller barriers to overcome in order to explore its configuration space. We examine the cooperativity of segmental motion in these bulk fluids and find that more extensive stringlike collective motion enables the system to overcome larger potential energy barriers, in qualitative agreement with both the Stillinger-Weber and Adam-Gibbs views of glass formation. Notably, the stringlike collective motion identified by our PEL analysis corresponds to incremental displacements that occur within larger-scale stringlike particle displacement processes associated with PEL metabasin transitions that mediate structural relaxation. These "substrings" nonetheless seem to exhibit changes in relative size with antiplasticization similar to those observed in "superstrings" that arise at elevated temperatures. We also study the effects of confinement on the energy barriers in each system. Film confinement makes the energy barriers substantially smaller in the pure polymer, while it has little effect on the energy barriers in the antiplasticized system. This observation is qualitatively consistent with our previous studies of stringlike motion in these fluids at higher temperatures and with recent experimental measurements by Torkelson and co-workers.

Xylary pH and Reduction Potential Levels of Iron-stressed Silver Maple (Acer saccharinum L.) 1

PubMed Central

Morris, Robert L.; Swanson, Bert T.

1980-01-01

Xylary fluid pH and reduction potentials were measured on silver maple (Acer saccharinum L.) grown under Fe and pH stress. Although pH and reduction potential (millivolt/59.2) varied significantly in the nutrient solution, xylary pH and reduction potential remained constant. It was concluded that changes in the pH and reduction potential in the xylary fluid of silver maple are not responsible for iron chlorosis. PMID:16661196

Flux rates and sulfur isotopic composition of pore fluids from three mud volcanoes in the northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Gilhooly, W. P.; Ruppel, C. D.; Dickens, G. R.; Berg, P.; Macko, S. A.

2010-12-01

Chloride and sulfate pore water analyses were performed on a total of 29 piston and gravity cores collected along center to flank transects across 3 mud volcanoes, which were located on the Louisiana continental slope in Garden Banks (GB425), Green Canyon (CG185), and Mississippi Canyon (MC852). All three sites are known areas of oil and gas discharge. In addition, seepage at GC185 and GB425 supports highly developed chemosynthetic communities, whereas no known communities have been observed at MC852. Comparison of pore water chemistry (sulfur concentrations and sulfur isotope compositions) among these 3 sites provides initial insight about fluid migration processes and advection rates and about the connection between fluid flux and the establishment of chemosynthetic communities. Pore water advection velocities were calculated from chloride profiles using a steady-state one dimensional advection-diffusion model. In general, chloride concentrations increased with depth to more than four times seawater concentrations. Incidences of pore water freshening are likely associated with hydrate dissociation. Chloride profiles show characteristic concave-up shapes at the center of each mud volcano and concave-down shapes along the flanks, a pattern that we previously interpreted and modeled (doi:10.1029/2004GL021909; doi:10.1111/j.1468-8123.2007.00191.x) in terms of seawater recharge-discharge. The depth of the sulfate-methane interface (SMI) shoals toward the center of the mud volcanoes, indicating potentially rapid anaerobic methane oxidation in these areas. Where the SMI is shallow, pore water sulfide S-isotope values are correspondingly elevated (~ +10 ‰) relative to seawater sulfate (δ34S = +21‰) and presumably represent near-quantitative reduction of pore water sulfate at GB425 and MC852. There is no such pattern at GC185. Such differences potentially reflect advection rates, the ages of the fluids, timing of fluid efflux, and differences in their chemistry.

Proteomic Changes of Alveolar Lining Fluid in Illnesses Associated with Exposure to Inhaled Non-Infectious Microbial Particles

PubMed Central

Teirilä, Laura; Karvala, Kirsi; Ahonen, Niina; Riska, Henrik; Pietinalho, Anne; Tuominen, Päivi; Piirilä, Päivi

2014-01-01

Background Hyperresponsiveness to inhaled non-infectious microbial particles (NIMPs) has been associated with illnesses in the airways. Hypersensitivity pneumonitis (HP) is considered to be the prototype for these NIMPs-related diseases; however, there is no consensus on the definitions or diagnostic criteria for HP and the spectrum of related illnesses. Methods and Findings In order to identify the possible diagnostic markers for illnesses associated with NIMPs in alveolar lining fluid, we performed a proteomic analysis using a two-dimensional difference gel electrophoresis on bronchoalveolar lavage (BAL) fluid from patients with exposure to NIMPs in the context of damp building-related illness (DBRI) or conditions on the borderline to acute HP, designated here as agricultural type of microbial exposure (AME). Samples from patients with HP and sarcoidosis (SARC) were included for reference. Results were compared to results of healthy subjects (CTR). Western blot was used for validation of potential marker proteins from BAL fluid and plasma. Protein expression patterns suggest a close similarity between AME and HP, while DBRI was similar to CTR. However, in DBRI the levels of the inflammation associated molecules galectin-3 and alpha-1-antitrypsin were increased. A novel finding emerging from this study was the increases of semenogelin levels in BAL fluid from patients with AME, HP and SARC. Histone 4 levels were increased in AME, HP and SARC. Elevated plasma levels of histone 2B were detected in HP and SARC, suggesting it to be a potential blood indicator for inflammatory diseases of the lungs. Conclusions In this study, the proteomic changes in bronchoalveolar lavage of DBRI patients were distinct from other NIMP exposure associated lung diseases, while changes in AME overlapped those observed for HP patient samples. Some of the proteins identified in this study, semenogelin and histone 4, could function as diagnostic markers for differential diagnosis between DBRI and HP-like conditions. PMID:25033447

Trapping, Deformation, and Rotation of Giant Unilamellar Vesicles in Octode Dielectrophoretic Field Cages

PubMed Central

Korlach, J.; Reichle, C.; Müller, T.; Schnelle, T.; Webb, W. W.

2005-01-01

The behavior of freestanding lipid bilayer membranes under the influence of dielectric force potentials was studied by trapping, holding, and rotating individual giant unilamellar vesicles (GUVs) inside dielectrophoretic microfield cages. Using laser scanning confocal microscopy and three-dimensional image reconstructions of GUVs labeled with fluorescent membrane probes, field strength and frequency-dependent vesicle deformations were observed which are explained by calculations of the dielectric force potentials inside the cage. Dynamical membrane properties under the influence of the field cage were studied by fluorescence correlation spectroscopy, circumventing potential artifacts associated with measurements involving GUV immobilization on support surfaces. Lipid transport could be accelerated markedly by the applied fields, aided by hydrodynamic fluid streaming which was also studied by fluorescence correlation spectroscopy. PMID:15863477

Nonminimal kinetic coupled gravity: Inflation on the warped DGP brane

NASA Astrophysics Data System (ADS)

Darabi, F.; Parsiya, A.; Atazadeh, K.

2016-03-01

We consider the nonminimally kinetic coupled version of DGP brane model, where the kinetic term of the scalar field is coupled to the metric and Einstein tensor on the brane by a coupling constant ζ. We obtain the corresponding field equations, using the Friedmann-Robertson-Walker metric and the perfect fluid, and study the inflationary scenario to confront the numerical analysis of six typical scalar field potentials with the current observational results. We find that among the suggested potentials and coupling constants, subject to the e-folding N = 60, the potentials V (ϕ) = σϕ, V (ϕ) = σϕ2 and V (ϕ) = σϕ3 provide the best fits with both Planck+WP+highL data and Planck+WP+highL+BICEP2 data.

Hydrodynamics of the Dirac fluid in graphene

NASA Astrophysics Data System (ADS)

Lucas, Andrew

Recent advances in materials physics have allowed us to observe hydrodynamic electron flow in multiple materials. A uniquely interesting possibility is the emergence of a quasi-relativistic plasma of electrons and holes appearing in Dirac semimetals such as graphene. I will briefly review the unique features of the hydrodynamics of the Dirac fluid, and then discuss the theroetical signatures for the Dirac fluid, and its observation in experiment.

In vitro percutaneous absorption and metabolism of Bisphenol A (BPA) through fresh human skin.

PubMed

Toner, Frank; Allan, Graham; Dimond, Stephen S; Waechter, John M; Beyer, Dieter

2018-03-01

Bisphenol A (BPA) is a high production volume compound. It is mainly used as a monomer to make polymers for various applications including food-contact materials. The primary route of exposure to BPA in the general population is through oral intake (EFSA 2015) however, other potential sources of exposure have also been identified, such as dermal contact. In the present study, the percutaneous absorption through human skin has been investigated in an in vitro study according to OECD TG 428 (Skin Absorption: In Vitro Method). In order to investigate potential dermal BPA metabolism during absorption, radiolabelled BPA was applied to fresh, metabolically competent, human skin samples (ring labelled 14 C BPA concentrations tested were 2.4, 12, 60 and 300mg/L). Measured as total radioactivity the mean absorbed dose (receptor compartment) ranged from 1.7-3.6% of the applied doses and the dermal delivery (epidermis+dermis+receptor compartment), sometimes also named bioavailable dose was 16-20% of the applied doses, with the majority of the radioactivity associated with epidermis compared to dermis and receptor fluid. No metabolism was observed in any of the epidermis samples; however some metabolism was observed in dermis and receptor fluid samples with formation of BPA-glucuronide and BPA-sulfate, and some polar metabolites. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Total fluid pressure imbalance in the scrape-off layer of tokamak plasmas

DOE PAGES

Churchill, Randy M.; Canik, John M.; Chang, C. S.; ...

2017-03-10

Simulations using the fully kinetic neoclassical code XGCa (X-point included guiding-center axisymmetric) were undertaken to explore the impact of kinetic effects on scrape-off layer (SOL) physics in DIII-D H-mode plasmas. XGCa is a total-f, gyrokinetic code which self-consistently calculates the axisymmetric electrostatic potential and plasma dynamics, and includes modules for Monte Carlo neutral transport. Previously presented XGCa results showed several noteworthy features, including large variations of ion density and pressure along field lines in the SOL, experimentally relevant levels of SOL parallel ion flow (Mach number similar to 0.5), skewed ion distributions near the sheath entrance leading to subsonic flowmore » there, and elevated sheath potentials (Churchill 2016 Nucl. Mater. Energy 1-6). In this paper, we explore in detail the question of pressure balance in the SOL, as it was observed in the simulation that there was a large deviation from a simple total pressure balance (the sum of ion and electron static pressure plus ion inertia). It will be shown that both the contributions from the ion viscosity (driven by ion temperature anisotropy) and neutral source terms can be substantial, and should be retained in the parallel momentum equation in the SOL, but still falls short of accounting for the observed fluid pressure imbalance in the XGCa simulation results.« less

Comparative analysis of 2D and 3D model of a PEMFC in COMSOL

NASA Astrophysics Data System (ADS)

Lakshmi, R. Bakiya; Harikrishnan, N. P.; Juliet, A. Vimala

2017-10-01

In this article, 2D and 3D model of a PEMFC has been simulated in order to study their performance when subjected to similar operating conditions. The comparison reveals interesting phenomena of performance enhancement of the fuel cell. Design of fuel cell channel and stationary studies were done in COMSOL. Variations in current density and electrolyte potential from simulation results were observed when operated at a temperature of 120 °C. The electrolyte potential was found to have increased from 1 to 2.5 V and the surface pressure due to fluid flow was found to have increased from 3 to 9.58 Pa.

Localized corrosion of 316L stainless steel with SiO2-CaO films obtained by means of sol-gel treatment.

PubMed

Vallet-Regí, M; Izquierdo-Barba, I; Gil, F J

2003-11-01

Sol-gel films on austenitic stainless steel (AISI 316L) polished wafer were prepared from sono-sols obtained from tetraethylorthosilane and hydrated calcium nitrate. However, pitting was observed in different places on the stainless steel surfaces. The corrosion resistance was evaluated by the polarization resistance in simulated body fluid environment at 37 degrees C. The critical current density, the passive current density, the corrosion potential, and the critical pitting potential were studied. The austenitic stainless steel 316L treated presents important electrochemical corrosion and consequently its application as endosseous implants is not possible. Copyright 2003 Wiley Periodicals, Inc.

Numerical and experimental investigations of human swimming motions

PubMed Central

Takagi, Hideki; Nakashima, Motomu; Sato, Yohei; Matsuuchi, Kazuo; Sanders, Ross H.

2016-01-01

ABSTRACT This paper reviews unsteady flow conditions in human swimming and identifies the limitations and future potential of the current methods of analysing unsteady flow. The capability of computational fluid dynamics (CFD) has been extended from approaches assuming steady-state conditions to consideration of unsteady/transient conditions associated with the body motion of a swimmer. However, to predict hydrodynamic forces and the swimmer’s potential speeds accurately, more robust and efficient numerical methods are necessary, coupled with validation procedures, requiring detailed experimental data reflecting local flow. Experimental data obtained by particle image velocimetry (PIV) in this area are limited, because at present observations are restricted to a two-dimensional 1.0 m2 area, though this could be improved if the output range of the associated laser sheet increased. Simulations of human swimming are expected to improve competitive swimming, and our review has identified two important advances relating to understanding the flow conditions affecting performance in front crawl swimming: one is a mechanism for generating unsteady fluid forces, and the other is a theory relating to increased speed and efficiency. PMID:26699925

Numerical and experimental investigations of human swimming motions.

PubMed

Takagi, Hideki; Nakashima, Motomu; Sato, Yohei; Matsuuchi, Kazuo; Sanders, Ross H

2016-08-01

This paper reviews unsteady flow conditions in human swimming and identifies the limitations and future potential of the current methods of analysing unsteady flow. The capability of computational fluid dynamics (CFD) has been extended from approaches assuming steady-state conditions to consideration of unsteady/transient conditions associated with the body motion of a swimmer. However, to predict hydrodynamic forces and the swimmer's potential speeds accurately, more robust and efficient numerical methods are necessary, coupled with validation procedures, requiring detailed experimental data reflecting local flow. Experimental data obtained by particle image velocimetry (PIV) in this area are limited, because at present observations are restricted to a two-dimensional 1.0 m(2) area, though this could be improved if the output range of the associated laser sheet increased. Simulations of human swimming are expected to improve competitive swimming, and our review has identified two important advances relating to understanding the flow conditions affecting performance in front crawl swimming: one is a mechanism for generating unsteady fluid forces, and the other is a theory relating to increased speed and efficiency.

A DC electrophoresis method for determining electrophoretic mobility through the pressure driven negation of electro osmosis

NASA Astrophysics Data System (ADS)

Karam, Pascal; Pennathur, Sumita

2016-11-01

Characterization of the electrophoretic mobility and zeta potential of micro and nanoparticles is important for assessing properties such as stability, charge and size. In electrophoretic techniques for such characterization, the bulk fluid motion due to the interaction between the fluid and the charged surface must be accounted for. Unlike current industrial systems which rely on DLS and oscillating potentials to mitigate electroosmotic flow (EOF), we propose a simple alternative electrophoretic method for optically determining electrophoretic mobility using a DC electric fields. Specifically, we create a system where an adverse pressure gradient counters EOF, and design the geometry of the channel so that the flow profile of the pressure driven flow matches that of the EOF in large regions of the channel (ie. where we observe particle flow). Our specific COMSOL-optimized geometry is two large cross sectional areas adjacent to a central, high aspect ratio channel. We show that this effectively removes EOF from a large region of the channel and allows for the accurate optical characterization of electrophoretic particle mobility, no matter the wall charge or particle size.

Correction of glutathione deficiency in the lower respiratory tract of HIV seropositive individuals by glutathione aerosol treatment.

PubMed

Holroyd, K J; Buhl, R; Borok, Z; Roum, J H; Bokser, A D; Grimes, G J; Czerski, D; Cantin, A M; Crystal, R G

1993-10-01

Concentrations of glutathione, a ubiquitous tripeptide with immune enhancing and antioxidant properties, are decreased in the blood and lung epithelial lining fluid of human immunodeficiency virus (HIV) seropositive individuals. Since the lung is the most common site of infection in those who progress to AIDS it is rational to consider whether it is possible to safely augment glutathione levels in the epithelial lining fluid of HIV seropositive individuals, thus potentially improving local host defence. Purified reduced glutathione was delivered by aerosol to HIV seropositive individuals (n = 14) and the glutathione levels in lung epithelial lining fluid were compared before and at one, two, and three hours after aerosol administration. Before treatment total glutathione concentrations in the epithelial lining fluid were approximately 60% of controls. After three days of twice daily doses each of 600 mg reduced glutathione, total glutathione levels in the epithelial lining fluid increased and remained in the normal range for at least three hours after treatment. Strikingly, even though > 95% of the glutathione in the aerosol was in its reduced form, the percentage of oxidised glutathione in epithelial lining fluid increased from 5% before treatment to about 40% three hours after treatment, probably reflecting the use of glutathione as an antioxidant in vivo. No adverse effects were observed. It is feasible and safe to use aerosolised reduced glutathione to augment the deficient glutathione levels of the lower respiratory tract of HIV seropositive individuals. It is rational to evaluate further the efficacy of this tripeptide in improving host defence in HIV seropositive individuals.

Correction of glutathione deficiency in the lower respiratory tract of HIV seropositive individuals by glutathione aerosol treatment.

PubMed Central

Holroyd, K. J.; Buhl, R.; Borok, Z.; Roum, J. H.; Bokser, A. D.; Grimes, G. J.; Czerski, D.; Cantin, A. M.; Crystal, R. G.

1993-01-01

BACKGROUND--Concentrations of glutathione, a ubiquitous tripeptide with immune enhancing and antioxidant properties, are decreased in the blood and lung epithelial lining fluid of human immunodeficiency virus (HIV) seropositive individuals. Since the lung is the most common site of infection in those who progress to AIDS it is rational to consider whether it is possible to safely augment glutathione levels in the epithelial lining fluid of HIV seropositive individuals, thus potentially improving local host defence. METHODS--Purified reduced glutathione was delivered by aerosol to HIV seropositive individuals (n = 14) and the glutathione levels in lung epithelial lining fluid were compared before and at one, two, and three hours after aerosol administration. RESULTS--Before treatment total glutathione concentrations in the epithelial lining fluid were approximately 60% of controls. After three days of twice daily doses each of 600 mg reduced glutathione, total glutathione levels in the epithelial lining fluid increased and remained in the normal range for at least three hours after treatment. Strikingly, even though > 95% of the glutathione in the aerosol was in its reduced form, the percentage of oxidised glutathione in epithelial lining fluid increased from 5% before treatment to about 40% three hours after treatment, probably reflecting the use of glutathione as an antioxidant in vivo. No adverse effects were observed. CONCLUSIONS--It is feasible and safe to use aerosolised reduced glutathione to augment the deficient glutathione levels of the lower respiratory tract of HIV seropositive individuals. It is rational to evaluate further the efficacy of this tripeptide in improving host defence in HIV seropositive individuals. PMID:8256245

Pleiotrophin, the angiogenic and mitogenic growth factor: levels in serum and synovial fluid in rheumatoid arthritis and osteoarthritis : And correlation with clinical, laboratory and radiological indices.

PubMed

Fadda, S M H; Bassyouni, I H; Khalifa, R H; Elsaid, N Y

2018-05-01

Few studies have reported a possible involvement of pleiotrophin (PTN) in the pathophysiology of osteoarthritis (OA) and very little is known about its role in rheumatoid arthritis (RA). This study is to measure PTN in the sera and synovial fluids in RA and OA and to assess its relation to activity, functional class and radiological staging. Serum and synovial fluid samples were collected from 35 RA patients and 40 knee OA patients and serum samples were withdrawn from 20 healthy controls. Demographic, clinical and serological data were prospectively assessed. Functional and radiographic grades were also assessed. Serum and synovial fluid PTN levels were measured using enzyme-linked immunosorbent assay (ELISA). There was no statistical significant differences (p > 0.05) on comparing the mean PTN level in sera of RA, OA patients and healthy controls. However the mean synovial fluid level of PTN in both patient groups was significantly higher than mean serum level (p < 0.001). Significant correlations between the serum PTN level and both morning stiffness duration (p = 0.008) and mHAQ score (p = 0.039) were only observed in RA patients. Our results point to a possible important role of PTN in RA and OA. We firstly report a serological pattern of PTN in the sera and synovial fluids of RA patients. However its implementation as a disease marker or a potential target therapy in both diseases awaits larger studies and further investigations.

The geothermal system of Caviahue-Copahue Volcanic Complex (Chile-Argentina): New insights from self-potential, soil CO2 degassing, temperature measurements and helium isotopes, with structural and fluid circulation implications.

NASA Astrophysics Data System (ADS)

Roulleau, Emilie; Bravo, Francisco; Barde-Cabusson, Stephanie; Pizarro, Marcela; Muños, Carlos; Sanchez, Juan; Tardani, Daniele; Sano, Yuji; Takahata, Naoto; de Cal, Federico; Esteban, Carlos

2016-04-01

Geothermal systems represent natural heat transfer engines in a confined volume of rock which are strongly influenced by the regional volcano-tectonic setting controlling the formation of shallow magmatic reservoirs, and by the local faults/fracture network, that permits the development of hydrothermal circulation cells and promote the vertical migration of fluids and heat. In the Southern Volcanic Zone of Chile-Argentina, geothermal resources occur in close spatial relationship with active volcanism along the Cordillera which is primarily controlled by the 1000 km long, NNE Liquiñe-Ofqui Fault Zone (LOFZ), an intra-arc dextral strike-slip fault system, associated with second-order intra-arc anisotropy of overall NE-SW (extensional) and NW-SE orientation (compressional). However there is still a lack of information on how fault network (NE and WNW strinking faults) and lithology control the fluid circulation. In this study, we propose new data of dense self-potential (SP), soil CO2 emanation and temperature (T) measurements within the geothermal area from Caviahue-Copahue Volcanic Complex (CCVC), coupled with helium isotopes ratios measured in fumaroles and thermal springs. We observe that inside the geothermal system the NE-striking faults, characterized by a combination of SP-CO2 and T maxima with high 3He/4He ratios (7.86Ra), promote the formation of high vertical permeability pathways for fluid circulation. Whereas, the WNW-striking faults represent low permeability pathways for hydrothermal fluids ascent associated with moderate 3He/4He ratios (5.34Ra), promoting the infiltration of meteoric water at shallow depth. These active zones are interspersed by SP-CO2- T minima, which represent self-sealed zones (e.g. impermeable altered rocks) at depth, creating a barrier inhibiting fluids rise. The NE-striking faults seem to be associated with the upflow zones of the geothermal system, where the boiling process produces a high vapor-dominated zone close to the surface. The WNW-striking faults seems to limit to the south the Copahue geothermal area.

Direct Detection and Identification of Prosthetic Joint Infection Pathogens in Synovial Fluid by Metagenomic Shotgun Sequencing.

PubMed

Ivy, Morgan I; Thoendel, Matthew J; Jeraldo, Patricio R; Greenwood-Quaintance, Kerryl E; Hanssen, Arlen D; Abdel, Matthew P; Chia, Nicholas; Yao, Janet Z; Tande, Aaron J; Mandrekar, Jayawant N; Patel, Robin

2018-05-30

Background: Metagenomic shotgun sequencing has the potential to transform how serious infections are diagnosed by offering universal, culture-free pathogen detection. This may be especially advantageous for microbial diagnosis of prosthetic joint infection (PJI) by synovial fluid analysis, since synovial fluid cultures are not universally positive, and synovial fluid is easily obtained pre-operatively. We applied a metagenomics-based approach to synovial fluid in an attempt to detect microorganisms in 168 failed total knee arthroplasties. Results: Genus- and species-level analysis of metagenomic sequencing yielded the known pathogen in 74 (90%) and 68 (83%) of the 82 culture-positive PJIs analyzed, respectively, with testing of two (2%) and three (4%) samples, respectively, yielding additional pathogens not detected by culture. For the 25 culture-negative PJIs tested, genus- and species-level analysis yielded 19 (76%) and 21 (84%) samples with insignificant findings, respectively, and 6 (24%) and 4 (16%) with potential pathogens detected, respectively. Genus- and species-level analysis of the 60 culture-negative aseptic failure cases yielded 53 (88.3%) and 56 (93.3%) cases with insignificant findings, and 7 (11.7%) and 4 (6.7%) with potential clinically-significant organisms detected, respectively. There was one case of aseptic failure with synovial fluid culture growth; metagenomic analysis showed insignificant findings, suggesting possible synovial fluid culture contamination. Conclusion: Metagenomic shotgun sequencing can detect pathogens involved in PJI when applied to synovial fluid and may be particularly useful for culture-negative cases. Copyright © 2018 American Society for Microbiology.

Boundaries of the thoracic paravertebral space: potential risks and benefits of the thoracic paravertebral block from an anatomical perspective.

PubMed

Bouman, Esther A C; Sieben, Judith M; Balthasar, Andrea J R; Joosten, Elbert A; Gramke, Hans-Fritz; van Kleef, Maarten; Lataster, Arno

2017-10-01

Thoracic paravertebral block (TPVB) may be an alternative to thoracic epidural analgesia. A detailed knowledge of the anatomy of the TPV-space (TPVS), content and adnexa is essential in understanding the clinical consequences of TPVB. The exploration of the posterior TPVS accessibility in this study allows (1) determination of the anatomical boundaries, content and adnexa, (2) description of an ultrasound-guided spread of low and high viscous liquid. In two formalin-fixed specimens, stratification of the several layers and the 3D-architecture of the TPVS were dissected, observed and photographed. In a third unembalmed specimen, ultrasound-guided posterolateral injections at several levels of the TPVS were performed with different fluids. TPVS communicated with all surrounding spaces including the segmental dorsal intercostal compartments (SDICs) and the prevertebral space. TPVS transitions to the SDICs were wide, whereas the SDICs showed narrowed transitions to the lateral intercostal spaces at the costal angle. Internal subdivision of the TPVS in a subendothoracic and an extra-pleural compartment by the endothoracic fascia was not observed. Caudally injected fluids spread posteriorly to the costodiaphragmatic recess, showing segmental intercostal and slight prevertebral spread. Our detailed anatomical study shows that TPVS is a potential space continuous with the SDICs. The separation of the TPVS in a subendothoracic and an extra-pleural compartment by the endothoracic fascia was not observed. Based on the ultrasound-guided liquid spread we conclude that the use of a more lateral approach might increase the probability of intravascular puncture or catheter position.

Abiotic methane formation during experimental serpentinization of olivine

PubMed Central

2016-01-01

Fluids circulating through actively serpentinizing systems are often highly enriched in methane (CH4). In many cases, the CH4 in these fluids is thought to derive from abiotic reduction of inorganic carbon, but the conditions under which this process can occur in natural systems remain unclear. In recent years, several studies have reported abiotic formation of CH4 during experimental serpentinization of olivine at temperatures at or below 200 °C. However, these results seem to contradict studies conducted at higher temperatures (300 °C to 400 °C), where substantial kinetic barriers to CH4 synthesis have been observed. Here, the potential for abiotic formation of CH4 from dissolved inorganic carbon during olivine serpentinization is reevaluated in a series of laboratory experiments conducted at 200 °C to 320 °C. A 13C-labeled inorganic carbon source was used to unambiguously determine the origin of CH4 generated in the experiments. Consistent with previous high-temperature studies, the results indicate that abiotic formation of CH4 from reduction of dissolved inorganic carbon during the experiments is extremely limited, with nearly all of the observed CH4 derived from background sources. The results indicate that the potential for abiotic synthesis of CH4 in low-temperature serpentinizing environments may be much more limited than some recent studies have suggested. However, more extensive production of CH4 was observed in one experiment performed under conditions that allowed an H2-rich vapor phase to form, suggesting that shallow serpentinization environments where a separate gas phase is present may be more favorable for abiotic synthesis of CH4. PMID:27821742

Abiotic methane formation during experimental serpentinization of olivine.

PubMed

McCollom, Thomas M

2016-12-06

Fluids circulating through actively serpentinizing systems are often highly enriched in methane (CH 4 ). In many cases, the CH 4 in these fluids is thought to derive from abiotic reduction of inorganic carbon, but the conditions under which this process can occur in natural systems remain unclear. In recent years, several studies have reported abiotic formation of CH 4 during experimental serpentinization of olivine at temperatures at or below 200 °C. However, these results seem to contradict studies conducted at higher temperatures (300 °C to 400 °C), where substantial kinetic barriers to CH 4 synthesis have been observed. Here, the potential for abiotic formation of CH 4 from dissolved inorganic carbon during olivine serpentinization is reevaluated in a series of laboratory experiments conducted at 200 °C to 320 °C. A 13 C-labeled inorganic carbon source was used to unambiguously determine the origin of CH 4 generated in the experiments. Consistent with previous high-temperature studies, the results indicate that abiotic formation of CH 4 from reduction of dissolved inorganic carbon during the experiments is extremely limited, with nearly all of the observed CH 4 derived from background sources. The results indicate that the potential for abiotic synthesis of CH 4 in low-temperature serpentinizing environments may be much more limited than some recent studies have suggested. However, more extensive production of CH 4 was observed in one experiment performed under conditions that allowed an H 2 -rich vapor phase to form, suggesting that shallow serpentinization environments where a separate gas phase is present may be more favorable for abiotic synthesis of CH 4 .

Detailed computational procedure for design of cascade blades with prescribed velocity distributions in compressible potential flows

NASA Technical Reports Server (NTRS)

Costello, George R; Cummings, Robert L; Sinnette, John T , Jr

1952-01-01

A detailed step-by-step computational outline is presented for the design of two-dimensional cascade blades having a prescribed velocity distribution on the blade in a potential flow of the usual compressible fluid. The outline is based on the assumption that the magnitude of the velocity in the flow of the usual compressible nonviscous fluid is proportional to the magnitude of the velocity in the flow of a compressible nonviscous fluid with linear pressure-volume relation.

The assessment of circulating volume using inferior vena cava collapse index and carotid Doppler velocity time integral in healthy volunteers: a pilot study.

PubMed

Peachey, Tom; Tang, Andrew; Baker, Elinor C; Pott, Jason; Freund, Yonathan; Harris, Tim

2016-09-02

Assessment of circulating volume and the requirement for fluid replacement are fundamental to resuscitation but remain largely empirical. Passive leg raise (PLR) may determine fluid responders while avoiding potential fluid overload. We hypothesised that inferior vena cava collapse index (IVCCI) and carotid artery blood flow would change predictably in response to PLR, potentially providing a non-invasive tool to assess circulating volume and identifying fluid responsive patients. We conducted a prospective proof of concept pilot study on fasted healthy volunteers. One operator measured IVC diameter during quiet respiration and sniff, and carotid artery flow. Stroke volume (SV) was also measured using suprasternal Doppler. Our primary endpoint was change in IVCCI after PLR. We also studied changes in IVCCI after "sniff", and correlation between carotid artery flow and SV. Passive leg raise was associated with significant reduction in the mean inferior vena cava collapsibility index from 0.24 to 0.17 (p < 0.01). Mean stroke volume increased from 56.0 to 69.2 mL (p < 0.01). There was no significant change in common carotid artery blood flow. Changes in physiology consequent upon passive leg raise normalised rapidly. Passive leg raise is associated with a decrease of IVCCI and increase in stroke volume. However, the wide range of values observed suggests that factors other than circulating volume predominate in determining the proportion of collapse with respiration. In contrast to other studies, we did not find that carotid blood flow increased with passive leg raise. Rapid normalisation of post-PLR physiology may account for this.

Lagrangian clustering detection of internal wave boluses

NASA Astrophysics Data System (ADS)

Allshouse, M.; Salvador Vieira, G.; Swinney, H. L.

2016-02-01

The shoaling of internal waves on a continental slope or shelf produces boluses that travel up the slope with the wave. The boluses are regions of trapped fluid that are transported along with the wave, unlike fluid in the bulk that is temporarily pertubed by a passing wave. Boluses have been observed to transport oxygen-depleted water and induce rapid changes in temperature (Walter et al, JGR, 2012), both of which have potential ramifications for marine biology. Several previous studies have investigated boluses in systems with two layers of different density (e.g., Helfrich, JFM, 1992, and Sutherland et al., JGR, 2013). We conduct laboratory and computational studies of bolus generation and material transport in continuously stratified fluids with a pycnocline, as in the oceans. Our laboratory experiments in a 4 m long tank are complemented by 2-dimensional direct numerical simulations of the Navier-Stokes equations. Efforts have been made to identify boluses with Eularian measures in the past, but a Lagrangian perspective is necessary to objectively identify the bolus over its lifespan. Here we use a Lagrangian based coherent structure method relying on trajectory clustering using the fuzzy c-means approach (Froyland and Padberg-Gehle, Chaos, 2015). The objective detection of a bolus enables examination of the volume, distance traveled, and increased available potential energy of a bolus, as a function of the stratification, wave properties, and the angle of the sloping topography. The decay of a bolus through turbulent mixing is investigated by locating where the Richardson number drops below ¼, where velocity shear overcomes the tendency of a stratified fluid to remain stratified. (supported by ONR MURI grant N000141110701)

Influence of Internal Waves on Transport by a Gravity Current

NASA Astrophysics Data System (ADS)

Koseff, Jeffrey; Hogg, Charlie; Ouillon, Raphael; Ouellette, Nicholas; Meiburg, Eckart

2017-11-01

Gravity currents moving along the continental slope can be influenced by internal waves shoaling on the slope resulting in mixing between the gravity current and the ambient fluid. Whilst some observations of the potential influence of internal waves on gravity currents have been made, the process has not been studied systematically. We present laboratory experiments, and some initial numerical simulations, in which a gravity current descends down a sloped boundary through a pycnocline at the same time as an internal wave at the pycnocline shoals on the slope. Measurements of the downslope mass flux of the gravity current fluid in cases with different amplitudes of the incident internal wave will be discussed. For the parameter regime considered, the mass flux in the head of the gravity current was found to reduce with increasingly larger incident amplitude waves. This reduction was effectively caused by a ``decapitation'' process whereby the breaking internal wave captures and moves fluid from the head of the gravity current back up the slope. The significance of the impact of the internal waves on gravity current transport, strongly suggests that the local internal wave climate may need to be considered when calculating gravity current transport. The Bob and Norma Street Environmental Fluid Mechanics Laboratory.

Lattice Boltzmann Method of Different BGA Orientations on I-Type Dispensing Method

PubMed Central

Gan, Z. L.; Ishak, M. H. H.; Abdullah, M. Z.; Khor, Soon Fuat

2016-01-01

This paper studies the three dimensional (3D) simulation of fluid flows through the ball grid array (BGA) to replicate the real underfill encapsulation process. The effect of different solder bump arrangements of BGA on the flow front, pressure and velocity of the fluid is investigated. The flow front, pressure and velocity for different time intervals are determined and analyzed for potential problems relating to solder bump damage. The simulation results from Lattice Boltzmann Method (LBM) code will be validated with experimental findings as well as the conventional Finite Volume Method (FVM) code to ensure highly accurate simulation setup. Based on the findings, good agreement can be seen between LBM and FVM simulations as well as the experimental observations. It was shown that only LBM is capable of capturing the micro-voids formation. This study also shows an increasing trend in fluid filling time for BGA with perimeter, middle empty and full orientations. The perimeter orientation has a higher pressure fluid at the middle region of BGA surface compared to middle empty and full orientation. This research would shed new light for a highly accurate simulation of encapsulation process using LBM and help to further increase the reliability of the package produced. PMID:27454872

Acoustic radiation force impulse (ARFI) ultrasound imaging of pancreatic cystic lesions.

PubMed

D'Onofrio, M; Gallotti, A; Salvia, R; Capelli, P; Mucelli, R Pozzi

2011-11-01

To evaluate the ARFI ultrasound imaging with Virtual Touch tissue quantification in studying pancreatic cystic lesions, compared with phantom fluid models. Different phantom fluids at different viscosity or density (water, iodinate contrast agent, and oil) were evaluated by two independent operators. From September to December 2008, 23 pancreatic cystic lesions were prospectively studied. All lesions were pathologically confirmed. Non-numerical values on water and numerical values on other phantoms were obtained. Inter-observer evaluation revealed a perfect correlation (rs=1.00; p<0.0001) between all measurements achieved by both operators per each balloon and fluid. Among the pancreatic cystic lesions, 14 mucinous cystadenomas, 4 pseudocysts, 3 intraductal papillary-mucinous neoplasms and 2 serous cystadenomas were studied. The values obtained ranged from XXXX/0-4,85 m/s in mucinous cystadenomas, from XXXX/0-3,11 m/s in pseudocysts, from XXXX/0-4,57 m/s in intraductal papillary-mucinous neoplasms. In serous cystadenomas all values measured were XXXX/0m/s. Diagnostic accuracy in benign and non-benign differentiation of pancreatic cystic lesions was 78%. Virtual Touch tissue quantification can be applied in the analysis of fluids and is potentially able to differentiate more complex (mucinous) from simple (serous) content in studying pancreatic cystic lesions. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Computational Fluid Dynamics Analysis of High Injection Pressure Blended Biodiesel

NASA Astrophysics Data System (ADS)

Khalid, Amir; Jaat, Norrizam; Faisal Hushim, Mohd; Manshoor, Bukhari; Zaman, Izzuddin; Sapit, Azwan; Razali, Azahari

2017-08-01

Biodiesel have great potential for substitution with petrol fuel for the purpose of achieving clean energy production and emission reduction. Among the methods that can control the combustion properties, controlling of the fuel injection conditions is one of the successful methods. The purpose of this study is to investigate the effect of high injection pressure of biodiesel blends on spray characteristics using Computational Fluid Dynamics (CFD). Injection pressure was observed at 220 MPa, 250 MPa and 280 MPa. The ambient temperature was kept held at 1050 K and ambient pressure 8 MPa in order to simulate the effect of boost pressure or turbo charger during combustion process. Computational Fluid Dynamics were used to investigate the spray characteristics of biodiesel blends such as spray penetration length, spray angle and mixture formation of fuel-air mixing. The results shows that increases of injection pressure, wider spray angle is produced by biodiesel blends and diesel fuel. The injection pressure strongly affects the mixture formation, characteristics of fuel spray, longer spray penetration length thus promotes the fuel and air mixing.

Transverse uterine fundal incision for placenta praevia with accreta, involving the entire anterior uterine wall: a case series.

PubMed

Kotsuji, F; Nishijima, K; Kurokawa, T; Yoshida, Y; Sekiya, T; Banzai, M; Minakami, H; Udagawa, Y

2013-08-01

To determine the feasibility and safety of transverse fundal incision with manual placental removal in women with placenta praevia and possible placenta accreta. Case series. Four level-three Japanese obstetric centres. Thirty-four women with prior caesarean section and placenta praevia that widely covers the anterior uterine wall, in whom placenta accreta cannot be ruled out. A transverse fundal incision was performed at the time of caesarean section and manual placental removal was attempted under direct observation. Operative fluid loss. The total volume of fluid lost during our operative procedure compares favourably with the volume lost during our routine transverse lower-segment caesarean sections performed in patients without placenta praevia or accreta. The average fluid loss was 1370 g. No patients required transfer to intensive care, and there were no cases of fetal anaemia. This procedure has the potential to reduce the heavy bleeding that arises from caesarean deliveries in women with placenta praevia and placenta accreta. © 2013 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2013 RCOG.

Severe metabolic acidosis in adult patients with Duchenne muscular dystrophy.

PubMed

Lo Cascio, Christian M; Latshang, Tsogyal D; Kohler, Malcolm; Fehr, Thomas; Bloch, Konrad E

2014-01-01

Duchenne muscular dystrophy (DMD) leads to progressive paresis, respiratory failure and premature death. Long-term positive pressure ventilation can improve quality of life and survival, but previously unrecognized complications may arise. We analyzed the characteristics of severe metabolic acidosis occurring in 8 of 55 DMD patients, of 20-36 years of age, observed over a 5-year period. All patients were on positive pressure ventilation and were being treated for chronic constipation. Before admission, they had had a reduced intake of fluids and food. Upon examination, they were severely ill, dyspneic and suffering from abdominal discomfort. Metabolic acidosis with a high anion gap was noted in 5 of the 8 patients and with a normal anion gap in the other 3. They all recovered after the administration of fluids and nutrition, the regulation of bowel movements and treatment with antibiotics, as appropriate. Metabolic acidosis is a life-threatening, potentially preventable complication in older DMD patients. Early recognition, subsequent administration of fluids, nutrition and antibiotics and regulation of bowel movements seem to be essential. © 2014 S. Karger AG, Basel.

Enhanced dissolution, stability and physicochemical characterization of ATRA/2-hydroxypropyl-β-cyclodextrin inclusion complex pellets prepared by fluid-bed coating technique.

PubMed

Chen, Zhongjian; Lu, Yi; Qi, Jianping; Wu, Wei

2013-02-01

The aim of this work was to prepare stable all-trans-retinoic acid (ATRA)/2-hydroxypropyl-β-cyclodextrin (HPCD) inclusion complex pellets with industrial feasible technology, the fluid-bed coating technique, using PVP K30 simultaneously as binder and reprecipitation retarder. The coating process was fluent with high coating efficiency. In vitro dissolution of the inclusion complex pellets in 5% w/v Cremopher EL solution was dramatically enhanced with no reprecipitation observed, and significantly improved stability against humidity (92.5% and 75% RH) and illumination (4500 lx ± 500 lx) was achieved by HPCD inclusion. Differential scanning calorimetry and powder X-ray diffractometry confirmed the absence of crystallinity of ATRA. Fourier transform-infrared spectrometry revealed interaction between ATRA and HPCD adding evidence on inclusion of ATRA moieties into HPCD cavities. Solid-state (13)C NMR spectrometry indicated possible inclusion of ATRA through the polyene chain, which was the main reason for the enhanced photostability. It is concluded that the fluid-bed coating technique has the potential use in the industrial preparation of ATRA/HPCD inclusion complex pellets.

Modeling of viscoelastic properties of nonpermeable porous rocks saturated with highly viscous fluid at seismic frequencies at the core scale

NASA Astrophysics Data System (ADS)

Wang, Zizhen; Schmitt, Douglas R.; Wang, Ruihe

2017-08-01

A core scale modeling method for viscoelastic properties of rocks saturated with viscous fluid at low frequencies is developed based on the stress-strain method. The elastic moduli dispersion of viscous fluid is described by the Maxwell's spring-dash pot model. Based on this modeling method, we numerically test the effects of frequency, fluid viscosity, porosity, pore size, and pore aspect ratio on the storage moduli and the stress-strain phase lag of saturated rocks. And we also compared the modeling results to the Hashin-Shtrikman bounds and the coherent potential approximation (CPA). The dynamic moduli calculated from the modeling are lower than the predictions of CPA, and both of these fall between the Hashin-Shtrikman bounds. The modeling results indicate that the frequency and the fluid viscosity have similar effects on the dynamic moduli dispersion of fully saturated rocks. We observed the Debye peak in the phase lag variation with the change of frequency and viscosity. The pore structure parameters, such as porosity, pore size, and aspect ratio affect the rock frame stiffness and result in different viscoelastic behaviors of the saturated rocks. The stress-strain phase lags are larger with smaller stiffness contrasts between the rock frame and the pore fluid. The viscoelastic properties of saturated rocks are more sensitive to aspect ratio compared to other pore structure parameters. The results suggest that significant seismic dispersion (at about 50-200 Hz) might be expected for both compressional and shear waves passing through rocks saturated with highly viscous fluids.